Note: Descriptions are shown in the official language in which they were submitted.
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SPECIFICATION
Optical Disc Driving Device
Technical Field
This invention relates to an optical disc driving device
whereby plural sorts of the optical discs different in design
formats, such as recording capacity, can be selectively employed.
Background Art
Up to now, an optical disc enabling information signals to
be recorded and/or reproduced using an optical beam has been
used. Among the optical discs of this sort in use, there are a
read-only compact disc (CD) having pre-recorded music data or
information data to be processed by a computer, and a CD-ROM.
There have also been proposed a high-density (HD) disc or
a high density (HD)-CD-ROM having the recording density twice or
three times as high as that of the CD or CD-ROM having the
standard recoding density.
There is also proposed a digital versatile disc/digital
video disc (DVD) as an optical disc having the same size as but
having the recording density seven to eight times as high as the
CD or the CD-ROM.
Also in use is a magneto-optical disc which is a
recording/reproducing optical disc having the same size as the
CD or CD-ROM and capable of re-recording data signals.
An optical disc drive device, having the above optical discs
as a recording medium, has a disc table which is run in rotation
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by a spindle motor and in which the optical disc is set in a
horizontal position. The signal recording surface of the optical
disc, thus rotated, is scanned across its inner and outer rims
by a light beam radiated from an optical pickup for
recording/reproducing data on or from the optical disc. The light
beam radiated from the optical pickup is radiated perpendicularly
on the signal recording surface of the optical disc as it is
converged for being focused on the signal recording surface.
For recording and/or reproducing data on or from the optical
disc with satisfactory recording/reproducing characteristics, it
is desirable that the light beam radiated from the optical pickup
be incident perpendicularly on the signal recording surface of
the optical disc. With the light beam being incident
perpendicularly on the signal recording surface of the optical
disc, a beam spot of the light beam converged by the objective
lens for being radiated on the signal recording surface of the
optical disc becomes truly circular, as a result of which the
beam spot can correctly scan a recording track formed on the
signal recording surface of the optical disc for recording and/or
reproducing data with good recording/reproducing characteristics.
Meanwhile, in consideration of warping of an optical disc
and mounting accuracy of a spindle motor or an optical pickup,
a pre-set allowance is provided in an optical disc driving device
employing an optical disc as a recording medium by a standard
with respect to a relative tilt between the signal recording
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surface of the optical disc and the optical axis of the objective
lens converging and radiating the light beam on the optical disc.
For example, in an optical disc driving device employing an
optical disc, such as a CD or CD-ROM 12 cm in diameter, as a
recording medium, the allowance of the relative tilt between the
optical axes of the optical disc and the objective lens is
unified at 1.2~ or less. That is, the relative tilt of 1.2~ or
less between the optical axis of the optical disc and that of the
objective lens with respect to the optical axis of the objective
lens perpendicular to the signal recording surface of the optical
disc is allowed. Specifically, the allowance of the tilt of the
objective lens is set to 0.6~ or less, while that of the spindle
motor or of the objective lens on the device is set to 0.6~ or
less.
On the other hand, with an optical disc, such as HD-CD or
HD-CD-ROM, having a recording density higher than that of a CD
or a CD-ROM having a standard recording density, not only the
recording track for data recording is reduced in width, but also
the track pitch is reduced for increasing the recording density
per unit area for improving the recording density.
In an optical disc drive device employing the optical disc
of such high recording density as a recording medium, it is
necessary to set verticality of the objective lens with respect
to the optical disc to a higher accuracy. If, when the optical
disc of high recording density is used asa recording medium, the
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verticality of the objective lens with respect to the optical
disc is not maintained at high accuracy, the beam spot of the
light beam radiated on the signal recording surface is distorted
in shape and narrow in width such that the recording track of
narrow pitch width cannot be scanned correctly. For example, it
may be an occurrence that a sole beam spot radiates the
neighboring recording tracks simultaneously such that the light
beam radiated on a pre-set recording track is reduced in energy
density with the result that data recording/reproduction cannot
be performed correctly.
This it is not possible to record and/or reproduce data on
or from an optical disc of high recording density with the use
of an optical disc player employing a CD or a CD-ROM having a
standard recording density.
DISCLOSURE OF THE INVENTION
It is therefore an object of the present invention to
provide an optical disc device whereby data can be selectively
recorded and/or reproduced on or from a first optical disc having
a standard recording density, such as a CD or a DC-ROM, and a
second optical disc having a recording density higher than that
of the first optical di.sc, such as a HD-CD or HD-CD-ROM.
It is another object of the present invention to provide
an optical disc device whereby it may be discriminated whether
the loaded optical disc is a first optical disc having a standard
recording density or a second optical disc having a higher
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recording density for controlling tilt of the objective lens
with respect to the optical disc for realization of high-
precision skew control.
It is yet another object of the present invention to provide
an optical disc device in which the device itself can be reduced
in thickness despite the fact that the device has a skew control
mechanism for adjusting the relative tilt between the optical
disc and the objective lens with a view towards realization of
selective recording and/or reproduction of data on or from an
optical disc having a standard recording density and a second
optical disc having a higher recording density.
An optical disc driving device of the present inventionJ
proposed for accomplishing the above objectJ includes a skew
control mechanism for controlling relative tilt between an
optical disc and an objective lens for selectively recording
and/or reproducing data on or from a first optical disc having
a standard recoding density and a second optical disc having a
high recording density. The relative tilt between the second
optical disc and the objective lens is controlled by the skew
control mechanism only when the second optical disc is loaded and
data is recorded and/or reproduced on or from the second optical
disc.
The skew control mechanism according to the present
invention controls tilt of the spindle motor rotationally driving
the optical disc for controlling the relative tilt between the
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objective lens and the second optical disc.
The skew control mechanism according to the present
invention controls relative tilt between the objective lens and
the optical disc by securing the spindle motor rotationally
driving the optical disc and by controlling the tilt of the
optical pickup carrying the objective lens.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig.l is a perspective view showing an optical disc driving
device according to a first embodiment of the present invention
and showing the state in which a disc tray has been pulled out
to a position enabling loading/unloading of the optical disc.
Fig.2 is a perspective view of the optical disc driving
device showing the optical disc loading state in which the disc
tray has been pulled into the inside of a main body portion of
the device.
Fig.3 is a perspective view showing the relation between the
disc tray and the disc clamper.
Fig.4 is a plan view showing a lift frame and a driving
mechanism for the device.
Fig.5 is a perspective view showing an optical pickup and
a lift frame.
Fig.6 is an exploded perspective view showing the loading
driving mechanism and a chassis.
Fig.7 is a side cross-sectional view showing the state of
ejecting the disc tray.
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Fig.8 is a side cross-sectional view of the optical disc
drive device showing the disc loading state.
Fig.9 is a cross-sectional view along line IX-IX of Fig.ll
for illustrating the skew control mechanism of the optical disc
driving device.
Fig.10 is a cross-sectional view along line X-X of Fig.ll
showing essential portions of the skew control mechanism.
Fig.ll is a plan view showing the skew control mechanism.
Fig.12 is a bottom view showing the skew control mechanism.
Fig.13 is an enlarged side view showing a slide cam of the
skew control mechanism.
Fig.14 is an exploded perspective view showing the skew
control mechanism.
Fig.15 is a perspective view showing the skew control
mechanism.
Fig.16 is a side cross-sectional view showing a rotational
fulcrum point constituting the skew control mechanism.
Fig.17 is a side cross-sectional view showing another
embodiment of the rotational fulcrum point.
Fig.18 is a side cross-sectional view showing still another
embodiment of the rotational fulcrum point.
Fig.l9 is a block diagram showing a control circuit section
of the optical disc driving device.
Fig.20 is a flowchart showing the operation of a working
distance of the optical disc drive device.
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Fig.21 is a flowchart for illustrating the control operation
of the optical disc device.
Fig.22 is a perspective view showing the appearance of an
optical disc device of a second embodiment according to the
present invention.
Fig.23 is a perspective view showing a disc tray and a disc
driving device.
Fig.24 is a plan view of the optical disc device with a disc
driving unit in an initial state.
Fig.25 is a front view showing the optical disc device with
the disc driving unit in an initial state.
Fig.26 is a plan view of the optical disc drive device in
a state in which the disc tray has been pulled to the loading
position.
Fig.27 is a front view showing the optical disc driving
device in a state in which the disc tray has been pulled to the
loading position.
Fig.28 is an exploded perspective view showing a first
supporting frame carrying a disc rotating device and a second
supporting frame supporting an optical pickup.
Fig.29 is a schematic side view showing the state in which
the second supporting frame has been rotated and skew control is
being carried out.
Fig.30 is a block diagram showing a control circuit section
of an optical disc driving device according to a second
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embodiment of the present invention.
Fig.31 is a flowchart showing the control operation of the
optical disc drive device.
Fig.32 is a flowchart for illustrating the specified
operation when an optical disc not having disc sort
identification data recorded thereon is loaded on the optical
disc drive device.
BEST MODE FOR CARRYING OUT THE INVENTION
Referring to the drawings, a first embodiment of the optical
disc drive device according to the present invention is
explained in detail.
The present optical disc driving device is configured for
selectively reproducing a first optical disc la of 12 cm in
diameter having a standard recording density, such as CD or CD-
ROM, or a second optical disc lb similarly of 12 cm in diameter
having a higher recording density, such as HD-CD or HD-CD-ROM.
The present optical disc device has a disc tray movable
horizontally across the inside and the outside of the main body
portion of the device, and performs loading of the first or
second optical disc la, lb using this disc tray.
In addition, the present optical disc drive device is used
as an external storage device of a computer.
Schematics of Optical Disc Drive Device
The outline of the optical disc drive device of the present
embodiment is first explained.
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The optical disc drive device has a disc tray 2 movable
horizontally across the inside and the outside of a main body
portion 5 of the device, as shown in Fig.l. The disc tray 2 has
a dished disc holder 3 on its upper surface. The optical disc la
or lb, reproduced by the present optical disc drive device, is
accommodated so that it is set on the bottom surface of the disc
holder 3 of the disc tray 2. When the disc tray 2 has been pulled
out of the main body portion 5 of the device, as shown in Fig.l,
the disc holder 3 faces the outside of the main body portion 5
of the device for enabling insertion and ejection of the first
or second optical discs la, lb.
For loading the first or second optical discs la, lb, the
disc tray 2 is pulled out of the main body portion 5 of the
device and the first or second optical discs la, lb to be
reproduced is set on the disc holder 3. If now a front side 2a
of the disc tray 2 pulled out of the main body portion 5 of the
device is thrust in a direction indicated by arrow Al in Fig.l,
the disc tray 3 acts n a loading switch, not shown, provided
within the main body portion 5 of the device. On actuation of
the loading switch, the disc tray 2 is horizontally pulled by a
loading driving mechanism, as later explained, in a direction as
indicated by arrow Al in Fig.l towards the inside of the main
body portion 5 of the device via a tray inlet/outlet formed in
a front panel 5a of the main body portion 5 of the device, as
shown in Fig.2. When the disc tray 2 is completely accommodated
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within the main body portion 5 of the device, as shown in Fig.2,
the first or second optical discs la, lb, held on the disc holder
3, are automatically horizontally loaded on the disc table run
in rotation by the spindle motor.
If, after loading of the first or second optical discs la,
lb, a playback command signal is entered from a host computer,
the spindle motor starts to be driven, such that the first or
second optical discs la, lb, held on the disc holder 3, are run
in rotation at a constant linear velocity (CLV) or at a constant
angular velocity (CAV). With start of rotation of the first or
second optical discs la, lb, the optical pickup starts to be
driven. As the light beam radiated from a light source, such asa
semiconductor laser, scans the signal recording area of the first
or second optical discs la, lb, the optical pickup reads out data
recorded on the first or second optical discs la, lb.
If, after reproduction of desired data recorded on the first
or second optical discs la, lb, an ejection command signal is
inputted from the host computer, the disc tray 2 is moved in a
direction shown by arrow A2 in Fig.1, corresponding to the
direction of ejection proceeding from the tray inlet/outlet 4 to
outside of the main body portion 5 of the device. This ejection
operation comes to a close when the disc holder 3 has been pulled
out of the main body portion 5 of the device, as shown in Fig.1.
Schematics of Loading mechanism
The loading mechanism of loading the first or second optical
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disc la or lb is hereinafter explained.
The loading mechanism includes a disc tray 2 for
transporting the first or second optical discs la, lb, reproduced
by the present optical disc driving device, across the inside and
the outside of the main body portion 5 of the device, as shown
in Fig.l. The disc tray 2, produced on molding a synthetic
resin material, is formed with an elongated bottom opening 8
extending along a tray centerline Pl from the center of the disc
holder 3 as far as a rear end 2b positioned inwardly of the main
body portion 5, as shown in Fig.3. On both lateral sides of the
disc tray 2 parallel to its movement direction are formed left-
hand and right-hand side guide rails 9 parallel to the tray
centerline Pl. On a lateral side of the bottom surface of the
disc tray 2 are formed a rack gear 10 and a rack groove 11 for
extending parallel to the movement direction of the disc tray 2,
as shown in Fig.4. The rack gear 10 and the rack groove 11 are
J-shaped in their entirety and delimit a semi-circular arcuate
portion on the front side 2a. That is, the rack gear 10 and the
rack groove 11 are formed by linear portions 10a, lla extending
parallel to the tray centerline Pl and arcuate portions 10b, llb
formed at the end portions towards the front side 2a of the
linear portions 10a, lla, respectively.
Within the inside of the main body portion 5 is arranged a
chassis 14 in the from of a shallow rectangular box formed of
e.g., synthetic resin, as shown in Fig.4. The disc tray 2 is
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supported by its left and right side guide rails 9 supported by
plural tray guides 15 integrally molded with the chassis 14 on
the inner sides of left and right side plates 14a, 14a thereof,
and are guided by these tray guides 15 in a direction extending
between the inside and the outside of the main body portion 5 as
indicated by arrows Aland A2Of Fig.l.
On the bottom surface 14b of the chassis 14 is mounted a
lift frame 16 formed by molding a synthetic resin material, as
shown in Fig.4. The lift frame 16 is formed with left-hand and
right-hand side insulator mounting portion 17, 17 and a center
insulator mounting portion 18, as shown in Fig.4. The insulator
mounting portions 17, 17 are formed towards the rear end 16a on
the inner side of the main body portion 5, while the center
mounting portion 18 is formed on the front end 16b on the front
side of the main body portion 5. Three insulators 19, 19, 20
formed of an elastic material, such as rubber, are mounted via
these insulator mounting portions 17, 18. The left and right
side insulators 19, 19, mounted on the rear end 16a of the lift
frame 16, are mounted on the bottom surface 14b of the chassis
14 by set screws 21 inserted into mid portions thereof, as shown
in Figs.4, 7 and 8. The insulator 20, mounted on the front end
16b of the lift frame 16, is mounted on the foremost part of a
lift driving lever 23 by a set screw 22 inserted in its mid
portion, as shown in Figs.4, 7 and 8. The lift driving lever 23
is arranged at right angles with the tray centerline Pl, as shown
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in Fig.4. The lift driving lever 23 is mounted on the bottom
portion 14b of the chassis 14 via left and right horizontal
supporting pins 24 protuberantly formed on both sides of the
proximal portion for rotation in directions shown by arrows Bl
and B2 in Fig.6 corresponding to the vertical direction. When the
lift driving lever 23 is rotated in a direction indicated by
arrows Bl or B2 in Fig.6, the lift frame 16 is lifted or lowered
by being rotated in a direction shown by arow Cl in Fig.7 or by
an arow C2 in Fig.8, corresponding to the vertical direction,
with left and right insulators 19, 19 on the rear end 16a as
fulcrum points.
The upper surface of the lift frame 16 is formed with a
dished disc driving unit mounting portion 25.
A loading driving mechanism 27, configured for moving the
disc tray 2 and for lifting the lift frame 16, is mounted on the
bottom portion 14b of the chassis 14 on a lateral side towards
the front end 16b of the lift frame 16, as shown in Figs.4 and
6. The loading driving mechanism 27 includes a loading motor 28,
and a pinion gear 29 run in rotation in the forward and reverse
directions by this loading motor 28. The loading driving
mechanism 27 also includes a pinion lever 31 for swinging a
center shaft 29a of the pinion gear 29 about a vertically
extending supporting shaft 30 in a horizontal plane in directions
indicated by arrows Dl and D2 in Fig.6, and a cam lever 34 driven
by a pair of sector gears 32 by this pinion lever 31 about a
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vertically extending supporting shaft 33 in directions indicated
by arrows El and E2 in Fig.6. The loading driving mechanism 27
similarly includes a vertically stepped cam groove 35 formed
arcuately around the supporting shaft 33 of the cam lever 34 and
a cam follower pin 36 formed as one with the foremost lateral
side if the lift driving lever 23 so as to be loosely fitted in
the cam groove 35. The pinion gear 29 meshes with the rack gear
10 of the disc tray 2, with the center shaft 29a of the pinion
gear 29 being loosely fitted in the guide groove 11.
With the loading driving mechanism 27, the center shaft 29a
of the pinion gear 29 is guided within the J-shaped guide groove
11 formed in the disc tray 2 for moving the pinion gear 29 along
the J-shaped rack gear 10 of the disc tray 2.
That is, during loading of the disc tray 2, the linear
portion lOa of the rack gear 10 is linearly driven from the rear
end 2b towards the front side 2a of the disc tray 2 by the
pinion gear 29 driven in the forward and reverse directions by
the loading motor 28 for horizontally pulling the disc tray 2 in
a direction of arrow Al in Fig.4 proceeding towards the inside
of the main body portion 5.
If, by continued forward rotation of the pinion gear 29 by
the loading motor 28, the pinion gear 29 is swung in a direction
indicated by arrow D1 in Fig.4 along the arcuate path of the
track gear 10, the pinion lever 31 causes the cam lever 34 to be
rotated vias a pair of sector gears 32 in a direction indicated
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16
by arrow E1 in Fig.4. If the cam lever 34 is rotated in a
direction indicated by arrow E1 in Fig.4, the cam follower pin 36
of the lift driving lever 23 is lifted by the cam groove 35
formed in the cam lever 34 in a direction indicated by arrow B
in Fig.8, corresponding to the upward direction. This causes the
lift driving frame 16 to be lifted via insulator 20 from an
obliquely downwardly inclined lower position shown in Fig.7 to
a horizontal rased position shown in Fig.8, in a direction
indicated by arow C1 in Fig.8, about the left and right
insulators 19, 19 as center.
The disc tray 2 is ejected by an operation reversed from the
loading operation. That is, while the pinion gear 29, run in
rotation in the reverse direction by the loading motor 28, is
swung in a direction indicated by arow D2 in Fig.4 along the
arcuate path lOb of the rack gear 10, the cam lever 34 is run in
rotation in a direction indicated by arrow E2 in Fig.4 for moving
the cam follower pin 36 by a cam groove 35 formed in the cam
lever 34 in a direction indicated by arrow B2 in Fig.7
corresponding to the downward direction for lowering the lift
frame 16 by the lift driving lever 36 via insulator 20 from the
upper position shown in Fig.8 to the lower position shown in
Fig.7 in a direction shown by arrow C2 in Fig.7 with the left
and right insulators 19, 19 as center.
By continued reversed rotation of the pinion gear 29 by the
loading motor 28, the linear portion lOa of the rack gear 10 is
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driven linearly by the pinion gear 29 from the front side 2a
towards the rear end 2b of the disc tray 2, for pulling out the
disc tray 2 in a direction indicated by arrow A2 in Fig.4
proceeding towards outside the main body portion 5.
Schematics of the Disc Driving Unit
The disc driving unit for reproducing the first or second
optical sics la, lb, loaded by the above-described loading
mechanism, is hereinafter explained.
The disc driving unit is mainly comprised of a spindle motor
39 for running the loaded first or second optical sics la, lb in
rotation, an optical pickup 41 for reading out data recorded on
the first or second optical sics la, lb rotationally driven by
the spindle motor 39 and a disc clamper 53 for clamping the first
or second optical sics la, lb, set on the disc table 40 run in
rotation by the spindle motor 39 in cooperation with the disc
table 40.
Referring to Figs.4, 7 and 8, the spindle motor 39 is
mounted upright within the disc driving unit holding portion 25
of the lift frame 16 at a position offset towards the front end
16b. The disc table 40 is mounted horizontally as one with the
upper end of a motor shaft 39a of the spindle motor 39. The
upper mid portion of the disc table 40 is formed as one with a
centering member 40a engaged n a center aperture lc of the first
optical disc la or the second optical disc lb.
Within the the disc driving unit holding portion 25 of the
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lift frame 16 of the lift frame 16 is horizontally mounted the
optical pickup 41 rearwardly of the spindle motor 39. The optical
pickup 41 has a carriage 44 within which are mounted upright an
objective lens 42 and a light reflection type skew sensor 43, as
shown in Fig.5. The light beam is incident on the objective lens
42, the reflected light from which is incident on an optical
block 45 mounted integrally on a lateral side of the carriage 44.
The lift frame 16 has a carriage movement mechanism 47
mounted thereon, as shown in Fig.5. The carriage movement
mechanism 47 is configured for linearly moving the carriage 44
along left and right side guide shafts 46, 46 in directions
indicated by arrows Aland A2 in Fig.4. The carriage movement
mechanism 47 includes a pinion gear 50, rotationally driven in
the forward and reverse directions by a carriage driving motor
48 via a gear train 49, and a rack gear 51 mounted on a lateral
side of the carriage 44 for being linearly driven by the pinion
gear 50.
The spindle motor 39 and the objective lens 42 are arranged
on the tray centerline Pl, while the objective lens 42 is
arranged on the optical pickup 41 for movement along the tray
centerline Pl in directions indicated by arrows Al and A2 in
Fig.4.
A disc clamper supporting plate 52 is mounted horizontally
across the upper ends of left and right side plates 14a of the
chassis 14 for traversing the upper portion of the disc tray 2.
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19
On the disc clamper supporting plate 52 is held a disc clamper
53 at a position directly above the disc table 40, as shown in
Fig.3. The disc clamper 53 is held at a mid portion of the disc
table 40 for movement in the up-and-down, left-and-right and in
the fore-and-aft directions within pre-set limits.
Unloading of the Optical Disc from the Disc Table and Playback
Operation
When the first or second optical disc la, lb is pulled into
the inside of the main body portion of the device 5 by the disc
tray 2 and loaded on the disc table 40, with the lift frame 16
being lifted to the upper horizontal position, as shown in Fig.8,
the disc table 40 is protruded upwards via bottom aperture 8
formed in the disc tray 2, with the centering member 40a being
engaged from below with a center aperture lc in the first or
second optical disc la or lb. By the disc table 40, the first
or second optical disc la or lb is floated upwards within the
disc holder 3 of the disc tray 2, while the disc la or lb is
clamped horizontally on the disc table 40 by the disc clamper 53,
for completing the loading.
If, after the first or second optical disc la or lb is
loaded in position, a playback command signal is supplied from
a host computer to the optical disc driving device, the spindle
motor 39 starts to be driven so that the first or second optical
disc la, lb is rotated at a high velocity with CLV or CAV. With
start of driving of the spindle motor 39, the carriage 44 of the
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optical pickup 41 is moved by the carriage movement mechanism 47
in a direction indicated by arrow Al or A2 in Fig.4, with the
objective lens 42 being moved in the same direction along the
tray centerline Pl.
The objective lens 42 is moved at this time along the tray
centerline Pl in a direction indicated by arrow Alor A2 through
a recording area RA between an innermost position ID and an
outermost position OD of the optical disc 1 as indicated by a
chain-dotted line and a double-dotted chain line in Fig.9,
respectively.
The light beam radiated from the optical block 45 is
directed by the objective lens 42 on to the signal recording
surface of the first or second optical disc la, lb, while the
return light reflected from the signal recording surface falls
on the optical disc 45 so as to be detected by a photodetector
provided in the optical pickup 41 for reading out data recorded
on the first or second optical disc la, lb.
Meanwhile, the carriage movement mechanism 47 causes the
carriage 44 to be moved along left and right guide shafts 46, 46
in directions indicated by arrows Al or A~ in Fig.9, by the
pinion gear being run in rotation in the forward and reverse
directions by the carriage driving motor 48 via gear train 49 for
linearly driving the rack gear 51.
If, after the desired data recorded on the first or second
optical disc la, lb, an ejection command signal is entered from
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the host computer to the optical disc device, the lift frame 16
is lowered to its lower position in a direction indicated by
arrow C2 in Fig.7, so that the disc table 40 is detached
downwards from the first or second optical disc la, lb. The first
or second optical disc la, lb is then set horizontally within the
disc holder 3 of the disc tray 2. The disc tray is then pulled
out of the main body portion 5 to complete the ejection
operation.
Skew Control mechanism
A skew control mechanism 61, configured for controlling the
relative tilt between the optical pickup 41 and the first or
second optical disc la, lb, is now explained.
Referring to Fig.9, the skew control mechanism 61 is
configured for adjusting the tilt of the spindle motor 39 in
directions indicated by arrows Fl and F2 n Fig.9 along the tray
centerline Pl, about left and right rotational pivots 62 arranged
on left and right sides of the spindle motor 39, as shown n
Fig.10, on a horizontal reference line P3 passing through the
axis P2 of the spindle motor 39 and extending at right angles
with the tray centerline Pl, as shown in Fig.9.
The spindle motor 39 is arranged within a cylindrical
opening 63 formed in the front end 16b of the lift frame 16, as
shown in Fig.ll. A pair of balls 64 operating as left and right
rotational pivots 62, are mounted vertically downwardly on left
and right sides of the opening 63 by left and right ball holders
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65, as shown in Fig.10.
A first spring plate 66, operating as pressure securing
means, is arranged horizontally below a base plate 39b of the
spindle motor 39 in parallel with the reference line P3, with
left and right ends of the first spring plate 66 being secured
from below by right set screws 67 on the lower surface of the
lift frame 16, as shown in Figs.10 and 14. Directly blow the left
and right balls 64 are formed left and right protrusions 66a
formed by drawing on the spring plate 66, as shown in Fig.14.
These protrusions 66a strongly thrust a horizontal surface 39c
of a base plate 39b of the spindle motor 39, as shown in Fig.10,
for strongly thrusting two points of the reference line P3 on
left and right sides of a horizontal reference surface 39d formed
by the upper surface of the base plate 39b from below against the
left and right balls 64.
On left and right sides of the base plate 39d of the spindle
motor 39 are formed left and right guide grooves 68 extending
along the reference line P3, as shown in Fig.14, for facing the
lift frame 16 in a horizontal state on both lateral sides of the
opening 63, with left and right guide pins 69 being loosely
fitted in these left and right guide grooves 66.
Thus the spindle motor 39, controlled in movement in the
directions indicated by arrows Aland A2 and in the left-and-right
direction perpendicular to the directions indicated by arrows Al
and A2 in Fig.9 relative to the lift frame 16 by the left and
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right guide pins 69, is mounted for rotation in directions
indicated by arrows F1 and F2 in Fig.9 relative to the lift
frame 16 about the left and right rotational pivot points 62 as
the center of rotation.
Referring to Fig.10, a skew driving mechanism 71 in the skew
control mechanism 61 has a slide cam 74, mounted horizontally on
the lower surface of the lift frame 16 and slid parallel to the
reference line P3 under guidance by plural guide pins 72 and
guide through-holes 73, and a cam follower roll 75, as a cam
follower, horizontally mounted on the base plate 39b of the
spindle motor 39 so as to be pressed against a slide cam 74, as
shown in Figs.14 and 15. The skew driving mechanism 71 also
includes a skew motor 76 mounted on the lift frame 16, and a
pinion gear rotationally driven by the skew motor 76 in both the
forward and reverse directions. The skew driving mechanism
further includes a rack gear 78 formed as one with the slide cam
74 for being linearly driven in directions indicated by arrows
G1 and G2 in Figs.11 and 14, and a second spring plate 79 as
pressuring means for horizontally pressuring the cam follower
roll 75 from below against the slide cam 74.
The second spring plate 79 is arranged parallel to the first
spring plate 66, with left and right lateral sides ends of the
second spring plate 79 being secured by left and right set screws
80 to the lower surface of the lift frame 16, as shown in Fig.9.
At a mid portion of the second spring plate 79 is formed an
CA 02208~32 1997-06-23
24
upwardly directed protrusion 79a by drawing. The second spring
plate 79 thrusts the cam follower roll 75 strongly against the
slide cam 74 from below by the protrusion 79a strongly thrusting
the vicinity of the cam follower roll 75 from below by the lower
surface 39c of the base plate 39b of the spindle motor 39, as
shown in Fig.9.
The cam follower roll 75 is rotatably mounted on a height
adjustment plate 81, as shown in Figs.9 and 12. This height
adjustment plate 81 is secured to the base plate 39b by a set
screw 82 for being mounted for height adjustment on a mounting
plate 83, as shown in Fig.12.
Referring to Fig.13, the slide cam 74 has a skew controlling
cam surface 85 of a length Ll, smoothly sloped along the
direction of arrows G1 and G2, representing its slide direction,
and a working distance enlargement cam surface 86, which is a
horizontal raised portion of a length L2 formed on an end of
the skew controlling cam surface 85 in a direction indicated by
arrow G1. The slide cam 74 also includes an inclined surface 87
interconnecting the skew controlling cam surface 85 and the
working distance enlargement cam surface 86. A step difference
Yl is formed between the skew controlling cam surface 85 and
the working distance enlargement cam surface 86 for forming a
step difference Y2 for the skew controlling cam surface 85.
A skew initial position sensor 88 for detecting whether or
not the current position is the skew initial position depending
CA 02208~32 1997-06-23
on the sliding position of the slide cam 74 is mounted by a set
screw 89 on the lower surface of the lift frame 16, as shown in
Fig.12.
Explanation of the Skew Control Operation
The skew control operation by the above-described skew
control mechanism 61 is carried out with the high-density second
optical disc lb loaded on the present optical disc drive device,
as will be explained later. That is, the skew control operation
occurs when the second optical disc lb is clamped by the disc
clamper 53 on the disc table 40 and rotationally driven by the
spindle motor 39, as shown in Figs.9 and 10.
When the spindle motor 39 is driven under this playback mode
for rotationally driving the second optical disc lb, the tilt of
the second optical disc lb with respect to the objective lens 42
is sensed by the light reflection type skew sensor 43.
The skew control mechanism 61 controls the tilt of the
optical disc 1 relative to the objective lens 42 so that the
optical axis Fo of the light beam radiated by the objective lens
42 on the optical disc 1 will be perpendicular (90~) to the
optical disc 1.
That is, the pinion gear 77, rotationally driven in the
forward and reverse directions by the skew motor 76 of the skew
driving mechanism 71, drives the rack gear 78 on the basis of
a detection output of the skew sensor 43 for adjusting the
sliding of the slide cam 74 in directions indicated by arrows G
CA 02208~32 1997-06-23
or G2 of Figs.12 and 15.
This causes the skew adjustment cam 85 f the slide cam 74
to lift or lower the cam follower roll 75 with a minor stroke in
directions indicated by arrows Hl or H2 in Fig.9 corresponding
to the vertical direction, for adjusting the tilt of the spindle
motor 39 in directions indicated by arrows Fl or F2 n Fig.9
about the left and right rotational pivot points 62 as center.
The second optical disc lb, horizontally clamped on the disc
table 40, is tilt-adjusted in directions imitated by arrows I
and I2 relative to the horizontal reference plane Pll,
corresponding to the vertical direction, as shown in Fig.9.
By this tilt adjustment of the second optical disc lb, the
optical disc 1 is radial skew controlled so that the optical disc
1 will become perpendicular (90~) relative to the optical axis Fo
of the light beam from the objective lens 42.
Specifically, if, based on the detection output from the
skew sensor 43, the second objective lens lb is tilted relative
to the objective lens 42 in the direction indicated by arrow I
corresponding to the (+) direction relative to the horizontal
reference plane Pll as shown by a chain dotted line in Fig.9,
the radial skew control operation is carried out so that the tilt
of the second optical disc lb will be corrected in a direction
indicated by arrow I2 corresponding to the (-) direction
relative to the horizontal reference plane Pll. Conversely, if
the second objective lens lb is tilted relative to the objective
-
CA 02208~32 1997-06-23
lens 42 in the direction indicated by arrow I2 corresponding to
the (-) direction relative to the horizontal reference plane Pll
as shown by a double-dotted chain line in Fig.9, the radial skew
control operation is carried out so that the tilt of the second
optical disc lb will be corrected in a direction indicated by
arrow Il corresponding to the (+) direction relative to the
horizontal reference plane Pll.
The result is that data reproduction is carried out with the
second optical disc lb being maintained at all times at a
perpendicular position (90~) relative to the optical axis Fo of
the objective lens 42, thus enabling high-density high-precision
data reproduction.
The above-described skew control mechanism 61, in which
radial skew control of the second optical disc lb in the
directions indicated by arrows Il or I2 is performed by tilt
adjustment of the spindle motor 39 in the directions indicated
by arrows Fl or F2 in Fig.9, is simpler in structure and
consumes less power than a conventional mechanism in which
optical pickup 41 in its entirety is controlled in tilt, thus
realizing a small-sized low-cost optical disc drive device 5 of
the power saving type.
In addition, the skew control mechanism 61, in which left
and right side points of the reference plane 39d of the base
plate 39b of the spindle motor 39 are pressured from below by the
spring plate 66 against the left and right balls 64 constituting
-
CA 02208~32 1997-06-23
28
left and right rotational pivot points 62 for tilt adjustment of
the spindle motor 39 in directions indicated by arrows Fl or F2
in Fig.9 about the left and right rotational pivot points 62 as
center, can smoothly perform tilt adjustment of the second
optical disc lb in directions indicated by arrows Il and I2
relative to the objective lens 42. In addition, since only small
power is required for controlling the tilt of the spindle motor
39 in the directions indicated by arrows Fl and F2 in Fig.9,
the skew motor 76 may be reduced in size, thus reducing the space
and realizing saving in power consumption.
Moreover, the skew control mechanism 61 is constructed so
that the slide cam 74 is slid by the slide motor 76 in directions
indicated by arrows Gl or G2 in Fig.15, and the cam follower
roll 75 is lifted or lowered in directions Hl and H2 in Fig.13
corresponding to the vertical direction by the skew control cam
surface 85 of the slide cam 74 for adjusting the angle of the
spindle motor 39 in the directions Fl or F2 in Fig.9, so that
an extremely small driving power suffices for sliding driving
of the slide cam 75, thus enabling reduction in space and saving
in power consumption otherwise brought about by the reduction in
size of the skew motor 76.
Furthermore, since the optical disc driving device has the
disc tray 2 for loading and ejecting the optical disc 1 and the
lift frame 16 lifted and lowered within the main body portion 5
in the directions indicated by arrows Cl and C2 in Figs.8 and
CA 02208~32 1997-06-23
29
9, and the lift frame 16 is fitted with the spindle motor 39,
optical pickup 41 and the skew control mechanism 61, the second
optical disc lb can be controlled for tilt relative to the
objective lens 42 in the disc tray type disc driving device.
Structure of the Rotational Pivots in the Skew Control Mechanism
An illustrative structure of the rotational pivot
constituting the skew control mechanism 61 is hereinafter
explained. The rotational pivot includes the ball holder 65
comprised of a main body member 65a, a cap 65b, a large-sized
ball 64 approximately 5 mm in diameter rotatably mounted on the
lower end of the ball holder 65, and about 100 ultra-small-sized
balls 64a about 0.5 mm in diameter on the inner upper side of the
large-sized ball 64, as shown in Fig.16.
The ball holder 65 is screwed from below to the lift frame
16 shown in Fig.10 by a screw 65c formed as one with the upper
mid portion of the main body member 65a, as shown in Fig.10, so
that the reference surface 39d of the motor base 39b of the
spindle motor 39 secured under pressure from the direction
indicated by arrow Hl in Fig.10 is received by the rotational
pivot 62 constituting the apex point of the large-sized ball 64
for performing tilt control of the spindle motor 39 in the
directions indicated by arrows Fl or F2 in Fig.16 about the
rotational pivot 62 as center.
Therefore, with the above-described rotational pivot, the
large-sized ball 64 can be rotated in stability with low friction
CA 02208~32 1997-06-23
by the ball-bearing function assured by about 100 ultra-small
sized balls 64a, thus assuring smooth high-precision radial skew
adjustment as described above.
A rotational pivot shown in Fig.17 has a ball holder 65 of
a metal sheet made up of a main body member 65a and a cap 65b,
a large-sized ball 64 approximately 5 mm in diameter rotatably
mounted on the lower end of the ball holder 65 and a small-sized
ball 64b approximately 3 mm in diameter rotatably mounted on the
lower end of the large-sized ball, with the center P21 of the
large-sized ball 64 being slightly offset at Go relative to the
center P22 of the small-sized ball. The ball holder 65 is formed
with a substantially conically-shaped tapered surface 65d
extending along the outer peripheral surfaces of the large-sized
ball 64 and the small-sized balls 64b. Meanwhile, the contact
portion of the tapered surface 65d with the small-sized ball 64b
is preferably coated with a lubricant, such as molybdenum.
The ball holder 65 is mounted, such as by press fitting,
within a mounting hole 97 formed in the lift frame 16 so that the
reference surface 39d of the motor base 39b of the spindle motor
39 press-fitted from the direction shown by arrow h for tilt-
adjusting the spindle motor 39 in the directions indicated by
arrows Fl or F2 in Fig.17 about the rotational pivot as center.
Thus, with the present rotational pivot mechanism, only two
balls suffice, while the ball holder 65 is made up of two
components, namely the main body member 65a and the cap 65b, that
CA 02208~32 1997-06-23
may be easily fabricated from metal sheets. In addition, the
ball holder 65 can be easily mounted, such as by press fitting,
in the mounting hole 97 in the motor base 39b, thus simplifying
the structure and production and achieving low production cost.
In addition, the large-sized ball 64 and the small-sized
ball 64b can be rotated with a low friction by relative rolling,
while the large-sized ball 64 and the small-sized ball 64b,
offset by Go relative to each other, can be rotated in stability
as the balls are thrust against the opposite sides of the tapered
surface 65d of the ball holder 65 by the components of pressuring
force of the base plate 39b applied to the rotational pivot point
62 from the direction shown by arrow H1 so that the large-sized
ball 64 and the small-sized ball 64b can be rotated in stability
without vibrations. If the tapered surface 65d is coated with a
lubricant, such as molybdenum, the large-sized ball 64 and the
small-sized ball 64b can be rotated in stability more smoothly.
Consequently, the above-described radial skew control operation
can be performed smoothly with higher accuracy.
In a rotational pivot shown in Fig.18, the small-sized ball
64b shown in Fig.17 is replaced by a small-sized roll 64c. In
other respects, the structure of Fig.18 is the same as that shown
in Fig.17. Therefore, the rotational pivot shown in Fig.18 gives
the structure and effect equivalent to those of the rotational
pivot shown in Fig.17.
However, the main body member 65a of the ball holder 65 of
CA 02208~32 1997-06-23
a metal sheet constituting the rotational pivot shown in Fig.18
has a substantially vee-shaped groove-like tapered surfaces 65d
on both sides in the direction of the offset Go between the
large-sized ball 64 and the small-sized ball 64b, while the
tapered surface 65d is not formed in a direction perpendicular
to the direction of offset Go of the main body member 65a. In
this case, it is similarly preferred to apply a lubricant, such
as molybdenum, on at least the contact portion of the tapered
surface 65d with the small-sized roll 64c.
Working Distance
If the optical disc drive device of the instant embodiment
is set to the playback mode as described above, the cam follower
roll 75 is lifted or lowered in the direction indicated by arrows
Hl or H2 by the skew controlling cam surface 85 of the slide
cam 74 of the skew control mechanism 61, as shown by a solid line
in Fig.13, for controlling the tilt of the spindle motor 39 for
controlling the tilt of the first optical disc la or the second
optical disc lb loaded on the spindle motor 40 by way of
performing radial skew control.
Thus, in the playback mode, a working distance WDl between
the major surface of the first optical disc la or the second
optical disc lb loaded on the disc table 40 and the upper surface
of the objective lens 42 may be reduced significantly up to
approximately 1.2 mm, as shown in Fig.9.
Control of Working Distance
CA 02208~32 1997-06-23
When the slide cam 74, shown in Fig.13, constituting the
above-described skew control mechanism 61, is slid by the skew
motor 76 from the radial skew operating position shown by a solid
line in Fig.13 to the initial position shown by a chain-dotted
line in Fig.13, the cam follower roll 75 rides from the skew
controlling cam surface 85 on the inclined surface 87 of the
slide cam 74 so as to be lifted up to the working distance
enlargement cam surface 86 in a direction indicated by arrow H
therein.
The spindle motor 39 is the rotated up to the initial
position indicated by arrow Fl in Fig.9 so that the optical disc
la or the second optical disc lb loaded on the disc table 40 is
lifted up to the initial position Pl2 indicated by a chain-dotted
line in Fig.9 in the direction indicated by arrow I, in Fig.9.
This reduces the working distance between the optical disc la or
the second optical disc lb and the objective lens 42 from a small
value WDl of approximately 1.2 mm for the playback mode to a
larger value WD2 of approximately 2.0 mm which is of the same
size as that in the conventional optical disc driving device.
The optical disc driving device of the instant embodiment
has a control circuit 90 constructed as shown in Fig.l9. This
control circuit 90 controls the rotation of the spindle motor 39
by a servo circuit 92 controlled by a CPU 91 having a micro-
computer, while controlling the reproduction of the optical disc
la or the second optical disc lb by the optical pickup 41 and
CA 02208~32 1997-06-23
34
controlling the rotation of the skew motor 76 of the skew control
mechanism 61. The input/output signal from the control circuit
90 to the CPU 91 or the output signal of the playback signals
from a playback circuit 94 is temporarily stored in a RAM circuit
95 and is exchanged via an external interface 93 with the host
computer connected to the present optical disc driving device.
The control circuit 90 operates so that, when the optical
disc driving device is set to the playback mode, the working
distance, which is the relative distance between the optical disc
la or the second optical disc lb and the optical pickup device
42 shown in Fig.9, is reduced to is small value of WDl of
approximately 1.2 mm, and so that, on power down, this working
distance is automatically increased to a larger value WD2 of
approximately 2.0 mm.
Thus, referring to the flowchart of Fig.20, if the optical
disc driving device is set to the playback mode, it is judged by
the CPU 91 at step Sl whether or not a stop command has been
received via external interface 93 from the host computer. If at
step Sl, the stop command has been received, the CPU 91 causes
the spindle motor 1 to be halted at step S2 . At the next step
S3, contiguous to the stop of the spindle motor 39, the CPU
controls the servo circuit 92 in order to cause the skew motor
76 to be driven to slide the slide cam 74 in the direction shown
by arrow Gl up to the initial position shown by a chain-dotted
line in Fig.9 in order to lift the first optical disc la or the
CA 02208~32 1997-06-23
second optical disc lb to the initial position Pl2 shown by the
chain-dotted line in Fig.9 in a direction shown by arrow Il in
Fig.9.
If the optical disc driving device is set to the playback
mode, and if the power is turned off in the absence of the stop
commend from the host computer, such as by power supply
interruption, with the first optical disc la or the second
optical disc lb being in the course of reproduction, the skew
motor 76 is driven by exploiting the counter-electromotive force
of the spindle motor 39 at step 5 for sliding the slide cam 74
in a direction indicated by arrow Gl to the initial position
shown by the chain-dotted line in Fig.13 for lifting the first
optical disc la or the second opticaI disc lb to the initial
position Pl2 shown by the chain-dotted line in Fig.9.
The above-mentioned working distance enlarging operation is
similarly carried out when the power source is turned on in the
playback mode but the operation of reproducing the first optical
disc la or the second optical disc lb by the optical pickup 41
is not going on or if the power source is suddenly turned off
such as by power supply interruption when the first optical disc
la or the second optical disc lb is being loaded on the disc
table 40.
In the former case, the skew motor 76 is run in rotation for
sliding the slide cam 74 in a direction indicated by arrow Gl to
the initial position shown by a chain-dotted line in Fig.13. In
CA 02208~32 1997-06-23
the latter case, the skew motor 76 is driven by the counter-
electromotive force of the spindle motor 39 for sliding the slide
cam 74 in a direction indicated by arrow G1 to the initial
position shown by a chain-dotted line in Fig.13 for lifting the
first optical disc la or the second optical disc lb in a
direction indicated by arrow I1 to the initial position shown by
the chain-dotted line in Fig.13.
By the above-described arrangement in which the working
distance is reduced in the playback mode to a small value WD1 for
the playback mode and increased to a larger value WD2 on power
down, there is no risk of the first optical disc la or the second
optical disc lb loaded on the disc table 40 being collided
against the objective lens 42 even if the optical disc driving
device is subjected to an excessive external shock, resulting in
significantly improved impact resistance.
Moreover, since the working distance WD2 may be reduced for
the playback mode from approximately 2.0 mm for the conventional
optical disc driving device to approximately 1.2 mm, thus
enabling the device itself to be reduced in thickness.
By controlling the sole skew control mechanism 61 by the
control circuit 90 constituting the control means of the optical
disc driving device of the instant embodiment, for controlling
the radial skew of the first optical disc la or the second
optical disc lb on the disc table 40 with respect to the
objective lens 42 and for moving the first optical disc la or the
CA 02208~32 1997-06-23
second optical disc lb to the initial position Pl2 for enlarging
the working distance from the small value WDl to the larger value
WDz, the sole skew control mechanism 61 can be used
simultaneously for radial skew control and for enlarging the
working distance for simplifying the structure and reducing the
cost.
Since the operation of controlling the radial skew and the
operation of enlarging the working distance can be performed by
rotating the spindle motor 39 in the directions indicated by
arrows Fl or F2 about the rotational pivot 62 as the center of
rotation, the radial skew control and working distance enlarging
operations can be performed easily and smoothly.
By forming the working distance enlarging cam surface 86 as
one with the skew controlling cam surface 85 of the slide cam 74,
the radial skew control and working distance enlarging operations
can be performed by the sole slide cam 74 thus simplifying the
structure and assuring a reliable operation.
Selection of the Standard Recording density First Optical Disc
and High Recording Density Optical Disc
With the optical disc driving device of the instant
embodiment, the first optical disc la of the standard recording
density, with the diameter of 12 cm, such as CD or CD-ROM, or the
second optical disc lb of the high recording density, with the
diameter of 12 cm, such as HD-CD or HD-CD-ROM, can be reproduced
selectively.
CA 02208~32 1997-06-23
The second optical disc lb having the high recording
density, such as HD-CD or HD-CD-ROM, is required to have high
dimensional accuracy, while the first optical disc la of the
standard recording density, such as CD or CD-ROM, is not required
to have accuracy as high as that of the second optical disc lb.
However, if radial skew control is performed by the skew
control mechanism 61 of the optical disc driving device of the
instant embodiment on the first optical disc la for which high
dimensional accuracy is not required, the radial skew control
range, that is the tilt control range in the direction indicated
by arrow Il or Iz in Fig.9, corresponding to the up-and-down
direction of the optical disc la or the second optical disc lb
loaded on the disc table 40 shown in Fig.9, needs to be set to
a larger value, such that it becomes necessary to set a larger
spacing in the direction of thickness of the main body portion
5 in which to perform radial skew control. In addition, the
length in the sliding direction of the slide cam 74 in the skew
control mechanism 61, that is the length in the directions
indicated by arrows Gl or G2 in Fig.13, needs to be increased,
thus increasing the size of the skew control mechanism 61 itself.
The result is that, if it is desired to perform radial skew
of the first optical disc for which high dimensional accuracy is
not required, it is necessary to increase the thickness of the
main body portion of the disc driving device itself, thus
inevitably increasing the size of the disc driving device itself.
CA 02208~32 1997-06-23
With this in view, the present optical disc driving device
is arranged so that, for selectively reproducing the first
optical disc la for which high dimensional accuracy is not
required or the second optical disc lb for which high dimensional
accuracy is required, these two disc types, that is the optical
disc la or the second optical disc lb, are discriminated, and
radial skew control is halted when the first optical disc la is
loaded, while the radial skew control is performed only when the
first optical disc la is loaded, for realization of the reduced
thickness of the disc driving device itself.
This operation is hereinafter explained by referring to the
block diagram of the optical disc driving device shown in Fig.9
and the flowchart shown in Fig.21.
First, the power source of the optical disc device is turned
on, the optical disc la or the second optical disc lb is set on
the disc holder 3 of the disc tray 2 pulled out of the main body
portion of the device 5, and the loading operation of moving the
disc tray 2 into the inside of the main body portion 5 is carried
out.
If the loading operation for the disc tray 2 is performed,
the CPU 91 detects at step Sll that the disc tray 2 has been
moved to the loading position, and outputs a detection signal.
When it is detected that the disc tray 2 has been loaded,
then it is judged at step S12 by the CPU 91 whether the detection
output of the detection signal by the skew sensor 43 is not less
CA 02208~32 1997-06-23
than a pre-set level. If the detection output of the detection
signal by the skew sensor 43 is higher than the pre-set level,
the carriage driving motor 48 is driven at step 13 for moving the
optical pickup 41 to the innermost radial position of the first
optical disc la or the second optical disc lb loaded on the disc
table 40.
If the detection output of the detection signal from the
skew sensor 43 is not higher than a pre-set level, it is judged
at step S14 that neither the first optical disc la nor the second
optical disc lb is loaded on the disc table 40, such that no
processing operation is performed.
If, at step S13, the optical pickup 41 is moved to the
innermost radial position ID of the optical disc la or lb, the
skew is initialized at step 15 by the servo circuit 92 based on
the control signal from the CPU 91. That is, the CPU 91 performs
control for moving the slide cam 74 to the skew initial position,
based on the output signal from the skew initial position sensor
88 mounted on the lift frame 16, as shown in Fig.12. The skew
initial position is such a skew position in which the axis P2 of
the spindle motor shown in Fig.10 is substantially a zero design
value (signifying a substantially vertical position).
The control to the skew initial position is performed so
that, if the skew initial position sensor 88 shown in Fig.12 is
acted upon by the slide cam 74 and thereby turned on, the slide
cam 74 is slid in the direction indicated by arrow Gz in Fig.15
CA 02208~32 1997-06-23
until the skew initial position sensor 88 is turned off, and so
that, if the skew initial position sensor 88 is not acted on by
the slide cam 74 and hence is turned off, the slide cam 74 is
slid in the direction indicated by arrow Glln Fig.15 until the
skew initial position sensor 88 is turned on.
When the setting to the skew initial position is done, the
CPU 91 turns the skew servo on at step 16. The CPU 91 then drives
the spindle motor 39 at step 17 for rotationally driving the
optical disc la or the second optical disc lb.
The CPU 91 then turns on the semiconductor laser, as a light
source of the optical pickup 41 at step 18 for radiating a light
beam.
At step Sl9, the CPU 91 causes the disc sort identification
data, recorded on the innermost radial position ID of the
rotating first or second optical disc la, lb, to be read out by
the optical pickup 41. The disc sort identification data, read
out by the optical pickup 41, is entered to a data processing
circuit 96, as shown in Fig.l9, so as to be supplied thence to
the CPU 91.
The CPU 91 judges at step S20, based on the disc sort
identification data entered from the data processing circuit 96,
whether the optical disc loaded on the disc table 40 is the first
or second optical disc la, lb.
If the optical disc loaded on the disc table 40 is judged
to be the first optical disc la of standard recording density,
CA 02208~32 1997-06-23
42
the CPU 91 sets the skew servo at step S21 to an off state and
halts the radial skew control for the optical disc la.
The CPU 91 reproduces data at this step forgiving judgment
whether the loaded optical disc is the optical disc of standard
recording density or the optical disc of high recording density.
If it is judged at step S20 that the optical disc as loaded
on the disc table 40 is the second optical disc lb with high
recording density, the CPU 91 turns the skew servo on at step
S22, at the same time as it causes data, signifying that the
loaded optical disc is the second optical disc of high recording
density lb, to be stored in the RAM 95.
The CPU 91 then causes data in meeting with the sort of the
optical disc loaded on the disc table 40 to be reproduced at step
S23. If the optical disc loaded on the disc table 40 is the first
optical disc la, data reproduction is carried out in a state in
which radial skew control is inhibited.
If the optical disc loaded on the disc table 40 is the
second optical disc lb, data specifying that the loaded optical
disc is the second optical disc lb is entered to the CPU 91, such
that data reproduction is carried out whilst the radial skew of
the second optical disc lb is controlled by the CPU 91.
Meanwhile, data read out by the optical pickup 41 is entered
to the data processing circuit 96 where it is separated from
control data or the like so as to be outputted as playback data.
When reproduction of the desired data recorded on the first
CA 02208~32 1997-06-23
43
optical disc la or the second optical disc lb loaded on the disc
table 40 comes to a close, the first optical disc la or the
second optical disc lb loaded on the disc table 40 is ejected at
step S23.
At step S24, the CPU 91 causes the first optical disc la or
the second optical disc lb to be ejected. At step S25, the CPU
initializes the skew control mechanism 61 to complete the
playback operation.
The foregoing description of the illustrative operation is
made for a case in which disc sort identification data has been
recorded on the innermost radial position ID of the first optical
disc la or the second optical disc lb. However, even if this data
is not recorded on the first optical disc la or the second
optical disc lb, it is possible to discriminate the disc sort by
detecting the difference in reflectance due to the difference in
the recording density on the signal recording surface of each
disc or by detecting the focal length of the objective lens 42
for detecting the differences in the focal length.
With the optical disc driving device of the instant
embodiment, the first optical disc la or the second optical disc
lb having different recording densities may be selectively
reproduced by one and the same device.
With the present optical disc device, the optical disc of
high recording density, having a small data unit area, can be
reproduced by a radial skew control operation with high density
CA 02208~32 1997-06-23
and to high accuracy.
Since the radial skew control operation is not done in
reproducing the first optical disc la of standard recording
density for which high dimensional accuracy is not required, the
driving device itself may be reduced in thickness.
With the present optical disc driving device, in which the
innermost radial position ID loaded on the disc table 40 is read
out by the optical pickup 41 for discriminating whether the
loaded optical disc is the first optical disc la or the second
optical disc lb, there is no necessity of using special means for
discriminating the sort of the optical disc sort, thus
simplifying the structure and reducing the cost.
Referring to the drawings, an optical disc device according
to a second embodiment of the present invention will be explained
in detail.
With the optical disc driving device of the instant
embodiment, a first optical disc of a standard recording density,
with a diameter of 12 cm, such as CD or CD-ROM, or a second
optical disc of a high recording density, with a diameter of 12
cm, such as HD-CD or HD-CD-ROM, can be reproduced selectively.
Schematics of Optical Disc Driving Device
The outline of the optical disc driving device of the
instant embodiment is first explained.
The present optical disc device includes a disc tray 102
moved horizontally across the inner side and the outer side of
CA 02208~32 1997-06-23
a main body portion 105 of the device, as shown in Figs.22 and
23. This disc tray 102 has a dished disc holder 103. The first
optical disc la or the second optical disc lb, reproduced by the
present disc driving device, is accommodated so as to be set on
the bottom surface of the disc holder 103. When the disc tray
102 has been pulled out of the main body portion 105 of the
device, the disc holder 103 faces the outside of the main body
portion 105 of the device for enabling loading/unloading of the
first or second optical disc lOla, lOlb, as shown in Fig.23.
For loading the first or second optical disc lOla, lOlb, the
disc tray 102 is pulled out of the main body portion 105 of the
device, as shown in Fig.23, and the first or second optical disc
lOla, lOlb desired to be reproduced is set on the disc holder
103. When a front side 102a of the disc tray 102 pulled out of
the main body portion 105 of the device is thrust towards the
inside of the main body portion 105 of the device, the disc tray
103 acts upon a loading switch, not shown, provided within the
main body portion 105 of the device. If the loading switch is
acted upon, the disc tray 102 is horizontally pulled into the
inside of the main body portion 105 of the device by a loading
driving mechanism 106 via a tray inlet/outlet 104 formed in the
front panel 107 of the main body portion 105 of the device. When
the disc tray 102 is fully accommodated within the main body
portion 105, as shown in Fig.21, the first or second optical disc
lOla, lOlb, held by the disc holder 3, is automatically loaded
CA 02208~32 1997-06-23
46
horizontally on the disc table, run in rotation by the spindle
motor, as will be explained subsequently.
If, after loading of the first or second optical disc lOla,
lOlb, a playback command signal is inputted from the host
computer, the spindle motor is stated to be driven for running
the first or second optical disc lOla, lOlb set on the disc table
at a CLV (constant linear velocity) or CAV (constant angular
velocity). Simultaneously with start of the rotation of the first
or second optical disc lOla, lOlb, the optical pickup starts its
operation. The optical pickup scans the signal recording area of
the first or second optical disc lOla, lOlb by a light beam
radiated from a light source, such as a semiconductor laser, for
reading out data recorded on the first or second optical disc
lOla, lOlb.
If, after desired data recorded on the first or second
optical disc lOla, lOlb is reproduced, an ejection command signal
is inputted from the host computer, or an ejection button
provided on the front panel 10 is thrust, the disc movement
operating mechanism is actuated for moving the disc tray 102 in
the ejecting direction proceeding from the tray inlet/output 104
towards the outside of the main body portion 105 of the device.
This ejection operation comes to a close when the disc holder 103
has been pulled out of the main body portion of the device 105,
as shown in Fig.23.
Disc Tray and Loading Driving Mechanism
CA 02208~32 1997-06-23
47
The disc tray 102 and the loading driving mechanism 106 for
the disc tray 102 for moving the disc tray 102 across the inner
side and the outer side of the main body portion 105 of the
device will be hereinafter explained. The disc tray 102, moved
across the inner side and the outer side of the main body portion
105, is molded from a synthetic resin material and has an
elongated bottom opening 108 extending from the mid portion of
the disc holder 103 towards the rear end thereof disposed on the
inner side of the main body portion 105, as shown in Fig.23.
When the disc tray 102 is moved to the playback position within
the main body portion 105, the bottom opening 108 is faced by a
disc table and an optical pickup making up the disc driving unit.
On opposite lateral sides of the disc tray 102 parallel to
its movement direction are formed left and right side guide rails
109. On a bottom side lateral surface of the disc tray 102 is
formed a rack gear 108 meshing with a feed gear 110 of the
loading driving mechanism 106.
Within the main body portion 105 is arranged a chassis 114
formed by punching and warping a thin metallic sheet. The disc
tray 102 has its left and right side guide rails 109 supported
by plural tray guides 115 of synthetic resin formed on the inner
sides of left and right facing side plates 114a, 114b of the
chassis 114, as shown in Fig.14, so that the disc tray is moved
across the inside an the outside of the main body portion 105 by
being guided by these tray guides 115, as shown in Fig.23.
CA 02208~32 1997-06-23
48
The loading driving mechanism 106 for moving the disc tray
102 across the inside an the outside of the main body portion 105
is arranged on the front side towards the tray inlet/outlet 104
of the chassis 114 arranged within the main body portion 105, as
shown in Figs.23, 24. The loading driving mechanism 106 includes
a loading motor 116 mounted on the bottom side on the front side
of the chassis 114 and a tray feed gear 118 meshing with a
driving gear 117 mounted on a driving shaft of the loading motor
116 so as to be rotated by the loading motor 116, as shown in
Figs.23, 24. The driving gear 117 meshes with a first coupling
gear 118a formed as one with the tray feed gear 118 for
transmitting the driving force of the loading motor 116 to the
tray feed gear 116. The tray feed gear 118 has an integral
second coupling gear 118b of the maximum diameter engaged with
the rack gear 108 for being thereby connected to the disc tray
102. Thus, when the loading gear 116 is driven, the disc tray 102
is fed via tray feed gear 118 across the inside and the outside
of the main body portion 105.
The loading driving mechanism 106 has a swinging gear 122
for moving a lifting plate 121 for lifting or lowering a spindle
motor constituting the disc driving unit 120 mounted on the
chassis 114, as will be explained subsequently. The swinging gear
122 is rotatably mounted on one end of a swinging lever 124
having its mid portion supported by a supporting shaft 119 of the
tray feed gear 118 for being rotated about the supporting shaft
CA 02208~32 1997-06-23
49
119 as the center of rotation. This swinging gear 122 is coupled
to the tray feed gear 118 by having a small-sized coupling gear
124 engaged with a third coupling gear 18c formed integrally with
the tray feed gear 118. The small-sized coupling gear 124 is
formed as one with the swinging gear 122. When the loading motor
116 is driven such that the tray feed gear 118 is run in
rotation, the swinging gear 122 is rotated around the outer
perimeter of the tray feed gear 118, depending on the direction
of rotation of the tray feed gear 118, for rotating the swinging
lever 124 in the directions indicated by arrows R1 or R2 in
Fig.24, about the supporting shaft 119 of the tray feed gear 118
as the center of rotation. On one side of a mid portion of the
swinging lever 123 is formed a sector gear meshing with the rack
gear 14 formed on a lateral side of the proximal end of the lift
plate 121. Thus, when the swinging gear 123 is rotated in the
directions indicated by arrows R1 or R2 in Fig.24, the lift plate
121 is moved in the directions indicated by arrows S1 or S2 in
Fig.24, depending on the direction of rotation of the swinging
gear 123.
On the bottom surface of the chassis 114 of the lift plate
121 is formed an upstanding piece 121a formed with an inclined
cam groove 126, as shown in Fig.25. In this inclined cam groove
126 is engaged a lift pin 127 formed on the disc driving unit
120. Thus, when the lift plate 121 is moved in the directions
indicated by arrow S1 in Fig.24, the lift pin 127 is moved along
CA 02208~32 1997-06-23
the inclined cam groove 126. The spindle motor on the disc
driving unit 120 is moved in the up-and-down direction towards
or away from the disc tray 102 moved on the chassis 114.
Meanwhile, the spindle motor on the disc driving unit 120
is lifted and lowered in a state in which the disc tray 102 is
accommodated within the main body portion 105. That is, the
spindle motor is moved towards the disc tray 102 during movement
of the disc tray 102 for avoiding conflict of the spindle motor
with the disc tray 102. To this end, the swinging lever 123 for
moving the lift plate 121 has its rotational movement controlled
depending on the movement position of the disc tray 102. The
rotational movement of the swinging lever 123 is controlled by
a lock lever 128 rotated by the disc tray 102. This lock lever
128 is supported on an upstanding supporting shaft 129 formed on
the chassis 114, as shown in Fig.24, and is mounted for rotation
about the shaft 129 as the center of rotation. The lock lever 128
is biased into a rotational movement, in a direction in which the
end lock portion 128a is engaged with a retention portion 123a
formed on the opposite side of the lever 123 by a torsion coil
spring 130 which is wound about the supporting shaft 129 and
which has its arm retained between the lock lever 125 and the
chassis 114.
When the disc tray 102 is moved to a loading position inside
the main body portion 105, the lock lever 128 has its thrust pin
on its proximal end thrust by a thrusting portion 128b formed on
CA 02208~32 1997-06-23
the front side on the bottom of the disc tray 102, as shown in
Fig.27. This rotates the lock lever 128 against the bias of the
torsion coil spring 130 for unlocking the lock portion 128a
engaged in the retention portion 123a of the swinging lever 123.
When the disc tray 102 is moved into the inside of the main
body portion 105 so as to be released from the locked state by
the lock lever 128, the swinging lever 123 is rotated by rotation
of the tray feed gear 118 for moving the lift plate 121. When the
lift plate 121 is moved in this manner, the lift pin 127 is moved
along the lift cam groove 126 between the lower position shown
in Fig.25 and the upper position shown in Fig.27.
On the chassis 114 are mounted a loading detection switch
133 for detecting that the disc tray 102 has been moved to the
loading position within the main body portion 5 for stopping the
driving of the loading motor 116 and a lift plate detection
switch 134 for detecting the movement position of the lift plate
121.
Disc Driving Unit
A disc driving unit 140, held on the above-described disc
tray 102 and having the first or second optical disc 101a, 101b
loaded thereon for reproducing data recorded on the disc lOla or
101b, is explained.
This disc driving unit 140 is supported on the chassis 114
and arranged within the main body portion 105, as shown in
Fig.23. Referring to Figs.23 and 26, the disc driving unit 140
CA 02208~32 1997-06-23
includes a disc rotational driving unit 141, on which is loaded
the first or second optical disc lOla, lOlb transported into the
inside of the main body portion 105 via disc tray 102, and an
optical pickup 142 for scanning the signal recording surface of
the first or second optical disc lOla, lOlb rotationally driven
by the disc rotational driving unit 141 by an optical beam for
reading out data recorded on the first or second optical disc
lOla, lOlb. The disc driving unit 140 also includes a disc
clamper 143 for clamping the first or second optical disc lOla,
lOlb, set on the disc table 143 of the disc rotational driving
unit 141, in cooperation with the disc table 143.
The disc rotational driving unit 141 and the optical pickup
142 are mounted on separate first and second supporting frames
144, 145, respectively, as shown in Fig.28.
The first supporting frame 144, in which is mounted the disc
rotational driving unit 141, is formed by punching a thin
metallic plate and warping the rim portions into a rectangular
shape, as shown in Fig.28. This first supporting frame 144 has
a substantially rectangular aperture 146 at a mid position
thereof for facing the optical pickup 142 mounted on the second
supporting frame 145. The disc rotational driving unit 141 is
mounted on the forward side of the first supporting frame 144,
that is on the side of the first supporting frame 144 positioned
towards the tray inlet/outlet 104 when the first supporting frame
144 is supported on the chassis 114 and arranged within the main
CA 02208~32 1997-06-23
53
body portion 105.
Meanwhile, the disc rotational driving unit 141 is made up
of a spindle motor 147 and a disc table 149 mounted integrally
on the distal end of a driving shaft 148 of the spindle motor
147. At a mid upper end of the disc table 148 is formed a
centering member 150 for being moved back and forth along the
axis of the driving shaft 148. The centering member is adapted
for being engaged in a center opening 101c of the first or second
optical disc 101a, 101b loaded on the disc table 149.
The disc rotational drivng mechanism 141 is mounted with a
mounting plate 151 on the outer perimeter of the spindle motor
147 secured to the first supporting plate 144, with the driving
shaft 148 extending at right angles with the first supporting
frame 144.
On a lateral side of the first supporting plate 144 is
arranged a pickup feed mechanism 152 configured for feeding the
optical pickup 142 mounted on the second supporting frame 145
aIong the radius of the first or second optical disc 101a, 101b
set on the disc table 149. This pickup feed mechanism 152 has a
pickup feed motor 153 and first to third interconnected driving
force transmitting gears 154 to 156 rotationally driven by this
pickup feed motor 153. The first driving gear 154 is connected
to a driving gear 157 mounted on a driving shaft f the feed motor
153, while the third force transmitting driving gear 1~6 is
connected to a rack gear 158 provided on the optical pickup 142.
CA 02208~32 1997-06-23
On the rear end of the first supporting frame 144 opposite
to the front side thereof carrying the disc rotational drivng
unit 141 is arranged a skew control mechanism 160 configured for
rotating the second supporting frame 145 for controlling the tilt
of the optical pickup 142 relative to the first or second optical
disc 101a, 101b set on the second supporting frame 145, as shown
in Fig.28. This skew control mechanism 160 has a skew motor 161
and a cam gear 162 rotationally driven by this skew motor 161.
The skew motor 161 and the cam gear 162 are mounted via a
mounting plate 163 mounted upright on the rear end of the first
supporting frame 144. That is, the skew motor 161 is mounted on
the mounting plate 163 so that a driving shaft 164 is
perpendicular to the driving shaft 148 of the spindle motor 147,
that is so that the driving shaft 164 will be perpendicular to
the optical axes of the first and second objective lenses 165,
166 making up the optical pickup 142. The cam gear 162 is also
mounted, via an upstanding supporting shaft 167 mounted on the
mounting plate 163, so that its plane of rotation will be
perpendicular to the optical axes of the of the first and second
objective lenses 165, 166 making up the optical pickup 142.
In the major surface of the cam gear 162 is formed an
arcuately-shaped cam groove 168. This cam groove 168 is formed
in a helix centered about the rotational center of the cam gear
162, with the radius of the cam gear being different in radius
from one end towards the opposite end. In the cam groove 168 is
CA 02208~32 1997-06-23
formed a lift pin 127 engaged in the inclined cam groove 126
formed in the lift plate 121 arranged on the chassis 114.
On both ends on the rear end of the first supporting frame
144 are mounted insulator mounting portions 171, 172, in which
are mounted insulators 173, 174 formed of an elastic material,
such as rubber. The first supporting frame 144 is supported on
the chassis 114 by having these insulators 173, 174 supported by
supporting shafts 173a, 174a set upright in the chassis 114.
The first supporting frame 144, having its both lateral rear
ends supported by paired elastically flexible insulators 173, 174
on the chassis 114 and having the front side lift pin 127
inserted into and engaged in the inclined cam groove 126 formed
in the lift plate 121, is rotated about paired insulators 173,
174 as center by the lift plate 121 being moved in the directions
indicated by arrows Sl, S2 in Fig.24 and by the lift pin 127
moved in the up-and-down direction along the inclined cam groove
126. By the first supporting frame 144 being rotated about the
paired insulators 173, 174 mounted on the rear side as fulcrum
points, the disc rotational drivng unit 141 mounted on the front
side is lifted and lowered with respect to the disc tray 102.
Similarly to the first supporting frame 144, the second
supporting frame 145, carrying the optical pickup 142, is formed
in a rectangular shape by warping a thin metal sheet and warping
the rm portions, as shown in Fig.28. In this second supporting
frame 145 is formed a substantially rectangular center aperture
CA 02208~32 1997-06-23
175 for arranging the optical pickup 142 therein.
The optical pickup 142, mounted on the second supporting
frame 145, is mounted on a lateral side of an optical block 176
housing optical components therein. On one side of the center
aperture 175 is mounted a guide shaft 176 for supporting the
optical pickup 142 and for guiding the movement direction, as
shown in Fig.28. On the opposite side of the optical block 176
to the side carrying the guide shaft 176 is mounted a guide
support 177 of a U-shaped cross-section engaged with the lateral
edge of the aperture 175. The optical pickup 142 is mounted on
the second supporting frame 145 for movement in a direction
parallel to the guide shaft 177, with the guide shaft 177 as a
reference, by having a guide support 177 engaged with the lateral
edge of the aperture 175 and by having both ends of the guide
shaft 177 supported by support pieces 179, 180 formed on the
second frame 145. On the outer lateral side of the optical pickup
142 carrying the guide shaft 177 is mounted a rack gear 158. When
the second supporting frame 145 is supported by the first support
frame 144, the rack gear 158 meshes with the third force
transmitting driving gear 156 of the pickup feed mechanism 152.
Therefore, when the driving motor 172 of the pickup feed
mechanism 152 is driven, the driving force of the driving power
is transmitted to the rack gear 158 via first, second and third
driving force transmitting gears 145 to 156 , so that the optical
pickup 142 is moved in the directions indicated by arrows T1 and
CA 02208~32 1997-06-23
T2 in Fig.28. That is, when the second supporting frame 145 is
supported on the first supporting frame 144, the optical pickup
142 is moved n a direction along the radius of the first or
second optical disc lOla, lOlb set on the disc table 149, that
is in a direction towards and away from the disc rotational
driving mechanism 141.
Meanwhile, since it is intended with the present optical
disc driving device of the instant embodiment to render it
possible to selectively reproduce the optical disc lOla with the
standard recording density or the second optical disc lOlb with
high recording density, such as DVD, the optical pickup 142
employed in the present device includes a first pickup unit 181
having an optical system as a laser light source optimized for
the first optical disc lOla and a second pickup unit 182
separated from the first optical pickup unit 181 and having an
optical system as a laser light source optimized for the second
optical disc lOlb. The first and second objective lenses 165,
166 converging and radiating the light beam from the laser light
sources on the first or second optical disc lOla, lOlb are
provided on the pickup units 181, 182, respectively, as shown in
Figs.24 and 28.
Meanwhile, in the optical pickup 142, the second objective
lens 166 is arranged on a line parallel to the movement direction
of the optical pickup 142, while the first objective lens 165 is
arranged with a pre-set angular offset with respect to the second
CA 02208~32 1997-06-23
objective lens 166. In this manner, the light beam radiated from
the second objective lens 166 for scanning the second objective
lens 166 can scan the recording track with higher accuracy.
On the upper surface of the optical block 176 of the optical
pickup 142 are loaded the optical pickup 142 and a skew sensor
183 comprised of a light emitting element and a light receiving
element for detecting the relative tilt between the optical disc
142 and the second optical disc 101b loaded on the disc table
149. The skew sensor measures the time which elapses until the
light radiated from the light emitting element is reflected by
the second optical disc 101b loaded on the disc table 149 so as
to be received by the light receiving element for detecting the
skew state.
At mid portions on the opposing lateral sides of the second
supporting frame 145 parallel to the movement direction of the
optical pickup 142 are protuberantly formed a pair of supporting
pins 184, 185, as shown in Fig.28. The second supporting frame
145 is supported on the first supporting frame 144 by passing the
supporting pins 184, 185 in through-holes 188, 189 formed in
opposing sidewall sections 186, 187 on the first supporting frame
144 and by engaging the engagement pins 170 on the rear end face
in the cam groove 168 formed in the cam groove 162 of the skew
control mechanism 160. In this manner, the cam gear 162 is
rotated by the skew motor 161 and the engagement pin 170 is moved
in the up-and-down direction in the directions indicated by
CA 02208~32 1997-06-23
arrows Yl, Y2 in Fig.29, depending on the amount of offset of the
cam groove 168, so that the second supporting frame 145 supported
by the first supporting frame 144 is rotated in the directions
indicated by arrows Xl, X2 in Fig.29, about the supporting pins
184, 185 as the center of rotation. By the optical pickup 142
being moved in the up-and-down direction as indicated by arrows
Yl and Y2 relative to the horizontal reference plane P2l, as shown
in Fig.29, the optical axis ~l of the second objective lens 166
is tilt-controlled in the directions indicated by arrows Ql or Q2
in Fig.29 relative to the major surface of the second optical
disc lOlb set on the disc table 149, with the optical axis of the
second objective lens 166 of the optical pickup 142 being
perpendicular to the signal recording surface of the second
optical disc lOlb, by way of performing a radial skew control
operation.
This radial skew control operation is carried out depending
on a detection output obtained by the skew sensor 183.
Meanwhile, the radial skew control operation by the skew
control mechanism is performed only in case the second optical
disc lOlb is loaded in position.
A pair of supporting pins 184, 185 constituting rotational
pivot points of the second supporting frame 145 are provided
substantially at the center of a radius Rl of the optical disc
lOlb loaded on the disc table 149. By providing the supporting
pins 184, 185 at such position, the radial skew control operation
CA 02208~32 1997-06-23
for the optical pickup 142 relative to the optical disc 101b can
be realized with a reduced amount of rotation of the second
supporting frame 145 for reducing the thickness of the disc
driving unit 140 and hence that of the disc driving device.
The disc driving unit 140 is provided with the disc clamper
143 for clamping the first or second optical disc 101a, 101b set
on the disc table 149 in cooperation with the disc table 149. The
disc clamper 143 is mounted on a disc clamper supporting plate
191 mounted horizontally across upper ends of left and right
sidewall sections 114a, 114b of the chassis 114, as shown in
Fig.23.
Playback operation for the First or Second Optical Discs
The operation of reproducing the first or second optical
disc 101a, 101b by the above-described second embodiment of the
optical disc driving device is explained by referring to the
block diagram of the optical disc driving device of the present
embodiment shown in Fig.30 and to a flowchart shown in Fig.31.
The first optical disc 101a is an optical disc, 12 cm in
diameter, having a standard recording density, such as CD or CD-
ROM, while the second optical disc 101b is an optical disc,
similarly 12 cm in diameter, having a high recording density,
such as DVD.
For reproducing the above-described first or second optical
disc 101a, 101b, the power source for the optical pickup device
is turned on and the disc tray 101 is pulled out of the main body
CA 02208~32 1997-06-23
61
portion 105. The first or second optical disc lOla, lOlb is then
held on the disc holder 3 and the disc tray 102 is moved towards
the inner side of the man body portion 5 by way of performing the
loading operation.
When the disc tray 102 has been moved into the inside of the
main body portion 105, the loading switch 133 detects that the
disc tray 102 has been moved as far as the loading position, and
the loading motor 116 is halted transiently.
When the movement of the disc tray 102 to the loading
position is detected, and the loading motor 116 is halted
transiently, the loading motor is driven in the reverse
direction. At this time, the lock lever 128 is rotated by the
thrusting portion 132 provided on the dis tray 102, against the
bias of the col spring 130, thus unlocking the swinging lever
123. When the lift plate 121 is moved in this manner, the lift
pin 127 provided on the first supporting frame 145 of the disc
driving unit 140 is moved from the position below the inclined
cam groove 126 shown in Fig.25 to an upper position shown in
Fig.27. The first supporting frame 145 is lifted towards the disc
tray 102, about the insulators 173, 174 as the center of
rotation, so that the first or second optical disc lOla, lOlb
held on the disc tray 102 is set on the disc table 149, at the
same time as the disc clamper 143 is pressed towards the disc
table 149 for clamping the first or second optical disc lOla,
lOlb for enabling the disc lOla or lOlb to be rotated in unison
CA 02208~32 1997-06-23
62
with the disc table 149. When the lift plate 121 has moved the
first supporting frame 145 to is uplifted position of clamping
the first or second optical disc 101a, 101b to the disc table
149, the lift plate detection switch 134 is actuated and the
loading motor 116 is stopped to detect the completion of loading.
When the completion of loading is detected by the lift plate
detection switch 134, the spindle motor 147 of the disc
rotational driving mechanism 141 starts to be rotated, at the
same time as the skew sensor 183 is turned on.
With the present optical disc driving device, as described
above, it is checked whether the optical disc to be reproduced
is the first optical disc lOla with the standard recording
density or the second optical disc 101b with the high recording
density and data is reproduced under a condition appropriate for
the optical disc, that is by switching between the first optical
pickup unit 181 for the first optical disc lOla and the second
optical pickup unit 182 for the second optical disc with the high
recording density and by setting skew servo on/off.
The first optical disc 101a is a CD or a CD-ROM, while the
second optical disc 101b is a DVD.
The operation of reproducing the optical disc driving device
of the instant embodiment is now explained by referring to the
block diagram of Fig.30 and the flowchart of Fig.31.
First, if, at step S1 in Fig.31, the system controller 30
receives a signal to the effect that the above-mentioned loading
CA 02208~32 1997-06-23
63
detection switch 133 has detected movement of the disc tray 102
to the loading position, the system controller actuates a servo
processor 231.
At step S2, the servo processor 231 judges, based on the
signal level of the output signal of the skew sensor 183, whether
any optical discs has been loaded on the disc tray 102.
Specifically, the skew sensor 183 detects the distance as far as
the recording surface of the optical disc, as described above,
and outputs a detection signal of a level inversely proportionate
to the detected distance. If no optical disc is loaded on the
disc tray 102, the detection signal level is decreased. The servo
processor 231 checks whether or not the detection signal of the
skew sensor 183 is not less than a pre-set value in order to
decide whether or not any optical disc is loaded. If the result
is YES, the servo processor 231 transfers to step S4. If
otherwise, the servo processor 231 transfers to step S3.
At step S3, data specifying that no disc is loaded is sent
by the servo processor 231 to a system controller 230 which then
controls the optical disc driving device in its entirety for not
performing further operations, while advising the host computer
of that effect.
At step S4, the servo processor 231 sends a signal for
moving the optical pickup 142 to the innermost radial position
of the optical disc to a feed motor driving unit 217 of the
pickup feed mechanism 152. The feed motor driving unit 217
CA 02208~32 1997-06-23
64
amplifies this signal to drive the feed motor 153. Thus the
optical pickup 142 is positioned at the innermost radial position
of the optical disc.
At step S5, the servo processor 231 initializes the skew.
That is, the servo processor 231 sends a signal of setting the
optical pickup 142 to the horizontal position to a skew driving
unit 216 of the skew adjustment mechanism. The skew driving unit
216 amplifies the signal for driving the skew motor 9. This sets
the optical pickup 142 to its horizontal position.
At step S6, the servo processor 231 turns the skew servo on.
That is, based on the detection signal from the skew sensor 183,
the servo processor 231 sends to the skew driving unit 216 a
signal setting a constant level of the detection signal.
Substantially simultaneously, at step S7, the servo
processor 231 sends to the spindle motor driving unit 219 a
signal for causing rotation of the spindle motor 147 at an rpm
corresponding to the accepted standard rpm in a CD player. The
spindle motor driving unit 219 amplifies this signal for driving
the spindle motor 147. This causes rotation of the optical disc.
At this time, the rpm of the spindle motor 147 is detected for
performing servo control for assuring a constant linear velocity
using a rpm detection mechanism, not shown.
At step S8, the system controller 230 controls the
changeover switches 222 to 224 for connecting a changeover
contact TCD in circuit. The servo processor 231 sends a signal of
CA 02208~32 1997-06-23
6~
causing light emission of a laser diode for CD 181a to a laser
diode driving unit 220a. The laser diode driving unit 220a
amplifies this signal so that the outgoing light will be at a
level appropriate for reproduction and drives the laser diode for
CD 181a. The laser light radiated by the laser diode for CD 181a
is converged by the objective lens 165 so as to be radiated on
and reflected by the recording surface of the optical disc. The
reflected light, that is the return light, is changed in signal
level depending on the presence or absence of, for example, pits,
pre-formed on the recording surface of the optical disc. The
return light is separated by a beam splitter so as to be incident
on the photodetector. The components for the beam splitter are
not illustrated in the drawings. The photodetector outputs an RF
signal depending on the light volume of the return light. Thus
the optical pickup 142 outputs RF signals corresponding to the
information (data) recorded on the optical disc.
Meanwhile, the optical pickup 142 outputs focusing error
signals or tracking error signals, in addition to the RF signals
by, for example, the so-called astigmatic method or the
differential amplification method.
Since the optical pickup 142 has been moved at step S9 to
the innermost radial position of the optical disc, that is to the
TOC recording position, the optical pickup 142 outputs RF signals
corresponding to TOC. An RF signal amplifier 221a waveform-
equalizes and amplifies the RF signals and routes the resulting
CA 02208~32 1997-06-23
66
signals via changeover switch 222 to a bi-level circuit 225,
while routing the focusing error signals and the tracking signals
to the servo processor 231. The bi-level circuit 225
discriminates the RF signals to reproduce the EFMed data to
supply the reproduced data to a decoder 226. The decoder 226
decodes the modulated data to route the resulting reproduced data
to the system controller 230. Since the reproduced data is data
corresponding to the TOC, disc sort identification data for
identifying the optical disc type is contained therein. If the
discrimination of the optical disc as later explained has come
to a close and the usual playback operation is preformed, the
reproduced data is outputted to the host computer.
At step Sll, the system controller 230 discriminates, based
on the sort identification data supplied from the decoder 226,
whether the optical disc loaded on the disc tray 102 is the high
recording density optical disc 101b, that is the DVD. If the
result is YES, the system controller 30 proceeds to step S12 and,
if otherwise, to step Sll.
At step Sll, the system controller 230 sends data specifying
that the optical disc loaded on the disc tray 102 is the first
optical disc 101a, that is the CD or the CD-ROM, to the servo
processor 231, which then stops, that is turns off, the skew
servo, that is, sends a value 0 signal (that is, sends nothing)
to the skew driving unit 216, irrespective of the value of the
detection signal from the skew sensor 183.
CA 02208~32 1997-06-23
67
On the other hand, the system controller 230 routes data
specifying that the loaded optical disc is the second optical
disc 101b at step S12 to the servo processor 231, which then
maintains the on-state of the skew servo and simultaneously sends
to the spindle motor driving unit 219 a signal of causing
rotation of the spindle motor 147 at an rpm corresponding to the
accepted standard rpm of the DVD. The system controller 230 also
controls the changeover switches 222 to 224 for connecting the
changeover contact TDV in circuit.
At step S13, data reproduction from the optical disc is
performed depending on the sort of the optical disc. That is, if
the loaded optical disc is the second optical disc 101b, the
servo processor 231 sends a signal of causing light emission of
a laser diode 182a for the second optical disc 101b via
changeover switch 223 to a laser diode driving unit 220b, which
then amplifies this signal so that the outgoing light will be at
an appropriate signal level for reproduction for driving the
laser diode 182a.
If the loaded optical disc is a CD, that is the first
optical disc 101a, the servo processor 231 performs the above-
described operation of step S8. Therefore, the detailed
description is not made for simplicity. It should be noted that
the servo processor 231 sends control signals via changeover
switch 224 to bi-axial diving units 218a, 218b based on the
focusing error signals and focusing error signals supplied
-
CA 02208~32 1997-06-23
68
thereto via changeover switch 222, so that these signals will be
zero, by way of applying focusing servo and tracking servo.
If, at step S14, the user performs an operation for
terminating the data reproduction, and the disc tray 102 is
pulled out, the system controller 230 receives a signal that the
loading detection switch 230 has detected movement of the disc
tray 102 to the loading position, and causes cessation of the
playback operation of the servo processor 31 and so forth.
At step S15, the servo processor 231 performs the above-
described operation of the step S5 for initializing the skew.
In the above description on the operation, it is assumed
that the disc sort discrimination data for optical disc sort
identification has been pre-recorded on the optical disc. The
illustrative operation for a case in which no disc sort
identification data is recorded on the optical disc is explained
by referring to the flowchart of Fig.32.
At step S21, the system controller 230 controls the servo
processor 231 and the changeover switches 222 to 224 for
operating the optical disc driving device in the CD mode.
Specifically, the servo processor 231 causes the spindle motor
147 to be rotated at the same velocity as that for the CD. The
servo processor 231 also causes the laser diode 181a to emit
light, while connecting the changeover switches 222 to 224 in
circuit and turning the tracking servo on.
At step S22, the system controller 230 issues a command for
CA 02208~32 1997-06-23
69
detecting the focusing distance of the objective lens 165 to the
servo processor 231, which then sends a signal with a linearly
changed signal level, for gradually approaching or separating the
objective lens 165 to or from the optical disc vias the
changeover switch 224 to the bi-axial driving unit 218a. The
servo processor 231 also monitors the focusing error signal
supplied via changeover switch 222 and detects the level of the
signal supplied to the bi-axial driving unit 218a when the
focusing error signal has become equal to zero. The servo
processor 231 sends data specifying this level, that is data
specifying the focusing distance of the objective lens 165 from
the recording surface of the optical disc, to the system
controller 230.
At step S23, the system controller 230 checks whether or not
the distance data supplied from the servo processor is larger
than a pre-set level. If the result is YES, the system controller
230 proceeds to step S24 and, if otherwise, to step S26.
At step S24, the servo processor 231 sends data specifying
the level of a signal supplied to the motor driving unit 217 for
linear feed of the optical pickup 142, that is data specifying
the track pitch. The system controller 230 judges whether or not
the data is not less than a pre-set value. If the result is YES,
the system controller 230 proceeds to step S25 and, if otherwise,
to step S26.
At step S25, the system controller 230 decides that the
CA 02208~32 1997-06-23
7o
optical disc loaded on the disc tray 102 is the CD, that is the
first optical disc 101a, and accordingly performs the operation
of the step S13 and the following steps as shown in Fig.31.
On the other hand, the system controller 230 controls the
servo processor 231 and the changeover switches 222 to 224 at
step S26 to cause the operation of the optical disc driving
device under the DVD mode. Specifically, the servo processor 231
causes the spindle motor 147 to be operated under the DVD mode.
Specifically, the servo processor 231 causes the spindle motor
147 to be rotated at the same velocity as the second optical disc
101b, that is the DVD, while causing the laser diode 182a to emit
light. In addition, the servo processor 231 connects the
changeover terminal TVD in circuit, while turning the tracking
servo on.
At step S27, the system controller 230 issues a command for
detecting the focusing distance of the objective lens 166 to the
servo processor 231, which then sends a signal with a linearly
changed signal level for gradually approaching or separating the
objective lens 166 to or from the optical disc via the changeover
switch 224 to the bi-axial driving unit 218a. The servo processor
231 also monitors the focusing error signal supplied via
changeover switch 222 and detects the level of the signal
supplied to the bi-axial driving unit 218b when the focusing
error signal has become equal to zero. The servo processor 231
sends data specifying this level, that is data specifying the
CA 02208~32 1997-06-23
focusing distance of the objective lens 166 from the recording
surface of the optical disc, to the system controller 230.
At step S28, the system controller 230 checks whether or not
the distance data supplied from the servo processor is within a
pre-set level. If the result is YES, the system controller 230
proceeds to step S29 and, if otherwise, to step S31.
At step S29, the servo processor 231 sends data specifying
the level of the signal supplied to the motor driving unit 217
for linear feed of the optical pickup 142, that is data
specifying the track pitch. The system controller 230 judges
whether or not the data is not less than a pre-set value. If the
result is YES, the system controller 230 proceeds to step S30
and, if otherwise, to step S31.
At step S30, the system controller 230 decides that the
optical disc loaded on the disc tray 102 is the DVD, that is the
second optical disc lOlb, and accordingly performs the operation
of the step S13 and the following steps, as shown in Fig.30.
At step S31, the system controller 230 deems that no optical
disc has been set on the disc tray 102, or that an optical disc
other than the CD or DVD is loaded thereon, and controls the
optical disc driving device in its entirety for not performing
further operations, while advising the host computer of that
effect.
In the present optical disc driving device according to the
present invention, the recording medium may also be a disc
CA 02208~32 1997-06-23
cartridge comprised of a cartridge and an optical disc housed
therein.
Although the above-described embodiments are directed to an
apparatus for exclusively reproducing data recorded on an optical
disc, the present invention may also be applied to a
recording/reproducing apparatus also having data recording means.
INDUSTRIAL APPLICABILITY
With the above-described optical disc driving device and the
recording/reproducing method according to the present invention,
since the first optical disc having the standard data recording
density and the second optical disc having the high recording
density are adapted to be selectively used for recording and/or
reproducing data, while the sort of the loaded optical disc is
discriminated, such that the skew control mechanism is actuated
only in recording/reproducing data on or from the second optical
disc with high recording density for adjusting the relative tilt
between the objective lens and the second optical disc, it
becomes possible to set verticality between the second optical
disc and the objective lens to high precision for recording
and/or reproducing data on or from the second optical disc of
high recording density with good recording/reproducing
characteristics.
In addition, since the relative tilt between the objective
lens and the optical disc is not controlled if data is recorded
and./or reproduced on or from the first optical disc with
CA 02208~32 1997-06-23
standard data recording density, the range of tilt control for
the objective lens by the skew control mechanism can be
suppressed to a smaller value for reducing the size of the disc
driving device.
