Note: Descriptions are shown in the official language in which they were submitted.
~ 3 PHN 8680
VMI7RJ
1~o3~77
"Video disc player".
The invention relates to a video disc player
for playing baclc optically readable video discs, com-
prising: a housing with a reoess; a cover ~hich is
movable about a pivoting axis between a fully opened
position and a fully closed playing position and
which in the playing position co~ers a video disc
which has been put on; latching means for latching
the cover in its playing positionl comprising a
spring-loaded movably journalled catch, and a cam
bcdy which is secured to a side of the cover opposite
the pivotlng axis (front side), which cam body in the
playing position extends into the said recess in the
housing and is provided with a latching cam which co-
operates with the catch in the playing position of
the cover, and with a safety cam; unlatching means
for releasing the cover from its latched position.
- into an unlatched position from which the cover,
without being impeded by latching means, can be
moved into the fully opened position, which unlatch
Z0 ing means compri~e a manual actuating member, an un-
latching member on which the catch is journalled
which unlatching member is movable between an initial
position and an unlatching position by means of the
manual actuating member, as well as unlatching spring
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PHN 8680
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means for resiliently urging the cover from its play-
lng position towards its unlatched position9 the un-
latching member being moved from its initial position
to its unlatching position by actuation of the manual
actuating member, so that the catch is moved relative
to the cam body from the latching cam into a position
in which the cover, without being impeded by the
latching cam, can be opened by the unlatching spring
means into a safety position wh:Lch is situated be-
t~een the latched position and -the unlatched position,
in which safety position the safety cam of the oam
support lS pressed against the catch by unlatching
spring means, and owing to the unlatching member re-
turning from its unlatching position to its initial
position the catch being moved relative to -the cam
body into a position in which the cover~ without be-
ing impeded by the sa:fety can, can be opened further
to its unlatched position by the unlatching spring
means; a main motor; a drive spindle driven by the
main mojtor for rotating a video disc is; an electric
supply source for powering the main motor; a main motor
switch for switching on and switching off the supply
of an electric supply current to the main motor with
the aid of the cam body, switching on being effected
by a movement of the cover from its unlatched posi~
tion to its playing position and switching off being
ef~ected by a movement of the cover from its playing
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PHN 8680
position to its safety position; and a safety mechanism
which prevents the unlatching member from returning
from its unlatching position to its initial position
for a certain time interval which suffices to allow
5 the speed of rotation of the drive spindle to be !
reduced to a non-hazardous safe value.
Such a video disc player has already been
described in the Applicant's Canadian Patent 1,086,860
which issued on September 30, 1980. In this video
disc player the cam body on the cover is profiled in
such a way that when the cover is fully closed :into
its latched position, the main motor is switched on
with the aid of the main motor switch. A problem is
that in practice it is impossible to make the instant
at which the catch has exactly reached the level on
the latching cam for which the cover is latched and
thus cannot be opened unless ater actuation o the
unlatching means exactly coincide with the instant at
which the main motor is switched on. There~ore, this
video disc player is constructed so that the main
motor switch is actuated just before the catch latches
the cover when this cover is being closed. However, as
a result of this an incorrect operation of the video
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disc player is possible, which may lead to an unsafe
, 25 situation. This is because a user may lower the cover
so far that the main motor is already switched on but
` the cover
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PHN 8680
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is not yet latched, and subsequently opens the cover
again. A video disc is generally driven with a speed
which during pla~ring is 1800 revolutions per minute
~mains frequency 60 Hz) or 1500 revolutions per minute
(mains frequency 50 Hz). In the Applicant's previous-
ly described video disc player -the video disc is
braked by automatic braking means provided for this
purpose if the cover is re-opened. ~Iowever, it is
considered to be undesirable when braking is effect-
; 10 ed whilst the cover is open. An additional unsafe fac~
tor is then that when the cover is open the video
disc is not pressed onto the drive spindle by a
disc-loading means, as is the case when the cover
is closed, but lies freely on the drive spindle.
When the drive spindle is braked abruptly by the
automatic braking means it is not unlikely that the
video disc, which may still rotat0 rapidly, is flung
off the drive spind:Le. Also in video disc players
which are not provided with an automatic braking
means~ however, the high speed may give rise to the
video disc being flung off the drive spindle.
It is an object of the invention to provide
a video disc player of the type mentioned in the pre-
amble with a grea-ter safety of operation and which
iIl particular prevents the cover from being re-
opened immediately after the main motor has been
switched on, and the invention is characterized ~n
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PHN 8680
18.3.77
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that the cam body is provided with an additional
latchlng cam which, if the said unlatching member is
in its initial position, co-operates with the catch
if the cover is in an intermediate position situated
between the unlatched position and the playing posi-
tion, in which intermediate position the application
of supply current to the main motor has not yet been
switched on by the cam body and the cam body is fur-
thermore provid0d with an additional safel;y cam which
when the catch is situated on the addit.ional latching
cam prevents the movement of the unlatching member
from its initial position to its unlatching position
by co-operation with the catch, so as to prevent the
cover from being open0d completely when the cover
has not yet reached its playing position, but in
the meantime has assumed a position in which the
supply current is already applied to the main mo-
tor.
The invention will now be d~scribed in
: 20 more detail with reference to the drawing, in which:
Fig 1 is a perspective view of a video
disc player with opened covèr,
. Fig. 2 is a perspective view of a number
o~ parts of the video disc player of Fig. 1 9 in-
cluding a cam body which is connected to the cover
of the player and latching, unlatching and safety
means co-operating therewith, and
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PHN 86~o
18.3.77
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Fig. 3 is an elevation of the cam body and,
; in cross-section, a catch.
The video disc player shown in Fig. 1 is
of the type in which optical information on a video
disc is read by reflection with the aid of a laser
beam. The player comprises a housing 1 on which a
cover 2 is mounted which is hingeable about a pi-
voting axis 50. On the player a video disc 3 is plac-
ed which durlng playing i5 covered by the cover 2.
In thi 9 pl aying pos-ltion the cover is latched by
latohin~ means to be discussed hereinafter, un-
latching being possible by means of a manual actuat-
ing member consisting of an unlatching button 4, and
by means of a number of unlatching means also to be
discussed her0inafter. In the housing a motor 5 is
mounted, see Fig. 2, for rotating the video disc.
i This motor, hereinafter to be referred to as main
motor~ is coupled with a drive spindle 6 for the
rotary support of the video disc which has been put
1 20 on. Furthermore, the housing ~ accommodates a ra-
diation source in the form of a laser 7, which is
schematically shown in Figs. 1 and 2 and which may
for example consist of a helium-neon laser. In Fig.
2 the beam of radiation produced by the laser is de-
signated 8.
During unlatching the unlatching means yet
to be discussed co-operate with a number of safety
, :
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PHN 8680
18.3.77
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means (see Fig. 2). Said safety means comprise:
a) Switching means in the form of a switch 9,
provided with a plurality of switching contacts, not
shown, for switching on and off a power supply source,
not shown, for the main motor 5. In Fig. Z the elec-
trical connections between an electric power supply
source and the switch 9 and the main motor 5 are
neither shown for the sake of clarity. By the ac-
tuation of the switch 9, which is provided with a
push-button 10, the power supply to the main motor
i9 switched on or off.
b) Automatic braking means for braking and
stopping the drive spindle 6. In the embodiment of
Fig. 2 these means comprise a brake lever 11 which
-~ 15 is pivotably connected to the housing, a brake disc
12 on the drive spindle, as well as a brake band
13, which is provided with a brake lining 14 and
which at one of lts ends 15 is connected to the hous-
ing and with its other end 16 to the brake lever 1 1 .
As will appear subsequently when the operation of
the various sa~ety means is described the brake band
13 co-operates with a part of the circumference of
the brake disc 12 when the cover is open, but leaves
said disc completely free in the playing position.
The braking means also include a tension spring 17,
which at one side is connected to tlle brake lever
11 and at the other side is rigidly connected to the
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P~ 8680
18.3.77
housing via a pin 18~ This spring urges the brake lever
continuously in a direc-tion towards the braking posl-
tion~
i
c~ Switching means for extinguishing the ra-
diation source, also comprising at least one switching
contact on the switch 9. The ele~trical connections
-to *he laser are neither shown.
d) Shielding means which enter into the ra-
diation path of the radiation beam 8 for shielding
said rad:iation beam before it can ernerge from the
housing 1~ In the embodiment of Fig. 2 -these shield-
ing means comprise a shielding lever 19 which is
hingeably connected to the housing and a vane 20
which i8 connected thereto,which vane is situated
. in the radiation path of the radiation beam 8 in the
shielding position of the shielding lever 11 and masks
said beam, if present 9 but in the playing position of
the cover allows this beam to pass freely through an
opening 21 for~led in the vane ~urthermore, the
shielding means include a tension spring 31 which
continuously urges the shielding lev~r 19 in a direc-
tion towards the bent tab 22 of the brake lever 11.
Thus, the brake lever 11 and the shieldlng lever 19
~ are continuously in contact with each other and co-
.;~ 25 operate with each other, only the brake lever 11
;: co-operating with the cover 2 of the video disc
player in a manner yet to be discussed.
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PHN 8680
The video disc player of Fig. 1 is provided
with directing means 23 for directing a read beam at
~ the information tracks of the video disc 3. These `~.
: directing means comprise an objective which belongs :~
to a focussing device, which objective is provided
with a number of optical elements for focussing the
light beam onto the information track and with means
; for receiving the reflected light beam. A suitable ;~
focussing device is for example described in our
Canadian Patent 1,073,101 which issued on March 4,
1980. This focussing device is mounted on a carriage
underneath the deck 44 of the video disc player, which
: carriage is radially movable relative to the drive
spindle. This carriage is not shown in the drawing
15 and can be driven in its direction of movement by : ~
means of an electric auxiliary motor, not shown. In `~:.
order to prevent the video disc player from being
damaged during removal of a video disc further safety
means are provided, vlz.~
e) Interrupting means, comprising at least
one switching contact on the switch 9, for prevent-
ing an electric current from being appliea to the
said auxiliary motor,
; Furthermore, for preventing the focussing
device and in particular the objective from being
` damaged, there are provided:
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PHN 8680
18.3.77
f) Interrup-ting means, also comprising at
least one switching contact on the switcih 9, for pre-
venting an electric current f'rom being applied to the
objective motor.
B~th the auxiliary motor of the carriage
and the objective motor are motors which are ene~giz-
ed via a servo system. Consequently, they are includ-
ed in a control circuit. The auxiliary motor is includ-
ed in a con-trol circu:Lt ~or the radial tracking of the
spiral trac:k on a video disc and the objective motor
in a control circuit for following the axial rnove-
ments of the disc with the objective. When the video
disc is removed this results in the said control cir-
cuits continuously receiving an error signal, as a
result of which the auxiliary motor will move the
carriage into one of its extreme positions, whilst
the objective motor will set the objective to its
highest oositi.on. Thus, the objective may be damag-
ed for example by manipulations with the next disc
.~ 20 to be put on~ whilst it is also undesirable that the
carriage is continuously kept in the extreme posi-
tion, because the motor would then constantly re-
.
~ ceive a voltage of maximum value in the stationary
: condition~
The latching and unlatching means will now
be discussed hereinafter,
The latching means comprise a cam body 24
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PHN 8680
18.3.77
which is connected to the cover 2. Said cam body has
a fairly complicated shape and is most clearly visible
in Figs. 2 and 3. It has a free bevelled end 25 and
a partly oblique side face 26 which co-operates with
the brake lever 11 and carries a latching cam 45, a
safety cam 41, an additional latching cam 46 and an
additional safety cam 47. In the playing position o~
the cover the brake lever 11 is pressed against the
side face 26 under the influence of the tension
spring 17 and is thus kept out of the braking posi-
tion. In this position of the cover the cam body pro-
~ects into a recess 49 in the housing and the free
end 25 co-operates with a leaf spring 27. This spring
is connected to the housing 1 and continuously bears
against the free end 25 in the playing position. ~l-
so connected to the leaf spring 27 is a hook-shaped
member 28 When the cover is open, i.e. in the si-
tuation shown in Fig. 2, the hook-shaped member 28
blocks the brake le~er 11. The latching means further-
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more comprise a catchrin the form of a pin 29 which,
against the force of a pressure spring 30, can be
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moved in its longitudinal direction, i.e. axially.
The unlatching means comprise the said un-
latching button 4 which can manually be moved to the
left by the user, in order to unlatch the cover 2. `
The button 4 co-operates with a pin 32 which is
mounted on an unlatchine slide 33 which also carries
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18.3.77
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the said pin 29,
On the unlatchi~g slide a bracket 34 is fi~sd,
to which a tension spring 39 is attached which with
i-ts other end is connected to a pin 40 on the housing
1 and which continuously loads the bracket 34, The
unlatching slide 33 is thus continuously pulled to
the right in Fig. 2 by the tension spring 39. During
unlatching the force of this spring must consequent-
ly be overcome by means of the button 4.
At the instant that the cover 2 is closcd
the various co-operating parts are in a position as
shown in Fig. 2. At a given instant during the down-
ward movement of the cover 2 the end 25 of the cam
body 24 comes into contact with the leaf spring 27.
The cover is now in what will be referred to as its
"unlatched position". In this position the end of
the catch 29 which faces the cam body 24 is situat-
ed on a flat portion 42 of the cam body. In Fig. 3
the patch ~1 which is followed by the end of the
-~ 20 catch over the cam body when the cover 2 is moved
from its unlatched position to its latched position
and is subsequently unlatched again is lndicated by
~ means of a dashed line and arrows. In the unlatch-
;~ ed position of the cover the end of the catch is
- 25 in a position relative to the cam body which in
Fig. 3 is designated I. By further closing the
cover against the force of the leaf spring 27, the
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PHN 8680
18.3.77
catch 29 is moved over the additional cam 46 into an
intermediate position II. Once arrived in this posi-
tion the cover can no longer be opened, not even by
the actuation of the unlatching button 4, because
the additional safety cam 47 in conjunctlon with
the catch 29 prevents the latching slide 33 from
being moved to the left,
Owing to the downward moverllent of the
leaf spring 27, the hook-shaped rr.ember 28 has been
moved downwardsand can no longer prev~nt the brake
lever 1l from being rotated. This happens by pres-
' sing the cover do~nwards from its intermediate po-
sition II into its latched position III against the
latching of the leaf spring 27. The catch then moves
over the cam body 24 to a pOsitioIl above the latch-
ing cam 45. Moreover, the oblique portion of the
side face 26 moves the brake lever 'I 1, so that the
brake band 14 is disengaged from the brake disc 12
and the main motor is switched on by the main
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switch 9. Moreover, servo-circuits for the pre-
viously mentioned auxiliary motor and objective
, ~ motor are switched on, the shielcling lever 19 is
actuated and the laser 7 is ignited. A hazardous
manipulation with the cover and at -the same time
~ 25 with the manual actuating member 4 is e~cluded
'~ because the additional latching carn 46 and the ad-
,' ditional sa,fety cam 47 prevent the catch from fol-
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PHN 8680
18.3~77
lowing a path relative to the cam body other than
that indicated in Fig. 3 by 51. Hence, the cover
can be unlatched only after complete latching.
The cover is released from the latched
position III by manually moving the button 4 to the
left. As a result the unlatching slide 33 is also
moved to the le~t, so that the end of the catch 29
slides off the top of the latching cam 1~5 and comes
on a flat portion 48, The leaf spring 27 presses
the cover 2 upwards. However, the safety cam 41 now
prevents the cover Z from being op0ned ~urther, be-
cause in the left-hand position of the unlatching
slide 33 the catch 29 butts against the cam 41. The
cover is now in its safety position (IV, Fig. 3), A
safety mechanism comprises a plunger 35 which is
connected to the bracket 34 and forms part of a
~ ~; grease damper ~6, comprising a housing 37 contain-
s ing grease, the plunger 35 and a fixing bracket 39.
'~ The grease damper ~ prevents the unlatching slide
ZO 33~ from being moved -to the right, unless after a
certain time has elapsed. Only when the unlatching
~ slide 33 has been slid back completely to the right
,.~ can the cover 2 be opened fully again, The initial
displacement of the cover 2 immediately after the
actuation of the unlatching button 4, which initial
displacement is equal to the distance between the
top faces of the cams 45 and 41, is sufficient to
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PHN 8680
18.3.77
ensure that the brake le~er l1 no longer co-operates
with the side face 26 of the unlatching hook 24. Thus,
immediately after the actua-tion of the unlatching
button 4 the -tension spring 17 can rotate the brake
lever about its hinge pin 43. Owing to t:his rotation
the end 16 of the brake band 13 is moved over such a
distance that the brake lining 11~ comes into contact
with the brake disc 12. However, duri.ng the movement
of the brake lever 11 9 the button 10 of the switch 9
10 has also been moved outwards, so that; the swltching
contacts on the switch 9 have alreacly changed over.
The main motor 5 is thus sw.itched off 9 whilst the
. laser beam 8 has been extinguished and the auxiliary
motor of the slide as well as the objective motor
of the focussing device have been switched off. As
an additional safety measure to prevent laser beam
~rom emerging from the objective in the absence of
a video disc whilst the cover is open, the tab 22
.~, moreover rotates the shielding lever 19 about its
.~ . 20 hinge pin 4~ when the brake lever 11 is rotated, so
;~ that a closed portion of the vane 20 enters into the
. path of the laser beam 8.
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