Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
lZ64374
MET~OD & APPARAll) S FOR CLEANI~X~ OPERATING COMPONENTS
OF A VIDEO PLAYER/RECORDER
BACKGROUND OF THE I~VE;NTION
~eçhnical Field
The present invention relates to a method and
apparatus for cleaning operating components of a video
player/recorder.
In recent years, video player/recorders have become
quite popular. ~ypically, there is a video head which
either records or plays back the video portion of the
playing tape, an audio head which performs the same
functions for the sound portion of the tape, an erase
head, and possibly other components which engage the
tape. In the proper operation of the player/recorder, it
is desirable that the surfaoe portion of at least some
(and desirably all) of these components which contact the
tape be cleaned periodically. I~ere are in the prior art
cassette cleaners which have a cassette housing in which
i6 mounted a cleaning ribbon. In operation, the cassette
housing is placed into a playing receptacle of the
player/recorder, and the start knob or button is moved to
the on~ position so that guide members of the
player/recorder engage the cleaning ribbon and bring it
into engagement with at least the drum of the video head,
and in some instances, the other operating components
which would normally come into contact with the playing
tape.
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In some player/recorders, the drum in which the
playing head is mounted rotates at a high rate of speed.
In other player/recorders, the drum for the playing head
remains stationary, while the playing head itself rotates
at a high rate of speed along the circumference of the
drum. During the normal de of operation, the magnetic
tape which is either being played or on which the
recording is being made moves along its length at a
controlled rate of speed adjacent the playing head. If
the drum of the playing head is stationary, the relative
movement between the magnetic tape and the drum is at a
substantially lower level. On the other hand, if the
drum is rotating at a high rate of speed (e.g. 1000 to
2000 revolutions per minute), the relative speed between
the drum and the magnetic tape is rather high.
In general, the cassette cleaners have had the
cleaning ribbon mounted in one of two ways. In one
arrangement, the cleaning ribbon is moved out of the
cassette housing into engagement with the drum of the
cleaning head, and the cleaning ribbon does not move
along it6 axial length. Thus, it is the rapid rotation
of the dr~m of the cleaning head which accounts for the
relative movement between the cleaning ribbon and the
drum. In the second arrangement, the cleaning ribbon is
unted on spools within the cassette housing so that
after it is moved out of the cassette housing into
cleaning engagement with the drum (and possibly other
components of the player/recorder), the cleaning ribbon
moves along its axial length at substantially the same
rate of speed as the magnetic tape in the normal mode of
operation of the player/recorder. In either case, there
1;~64374
is relative movement between the cleaning ribbon and the
drum of the playing head.
One of the major problems in providing such cassette
cleaners is the sensitivity of the operating components
of the various player/recorders. For example, the
cassettes for magnetic tapes generally have two spools
which engage spindles of the player/recorder. During
normal operations, the magnetic tape will be unwound from
one spool and wound onto the other. If the spindles (or
possibly other operating components of the
player/recorder) sense a re~istance to rotation greater
than a certain level, this will generally activate a
shutoff mechanism in the player/recorder. The reason for
this is that the increased resistance indi Qtes a
problem, and the player/recorder shuts off to avoid
damage to the magnetic tape or possibly damage to the
player/recorder itself.
In addition, a number of player/recorders have other
shutoff mechanisms. For example, there are the capstan
and pinch roller which grip opposite sides of the tape,
with the capstan being rotated under power so as to cause
rotation of the pinch roller and move the magnetic tape
along its length at a controlled rate. If for some
reason the capstan is not causing the corresponding
rotation of the pinch roller, so that the tape is not
being moved, this might also trigger a ~hutoff mechanism.
Generally, the magnetic tape is made of a quite thin,
rather flexible, low friction material. ~owever; the
cleaning ribbon of a cassette cleaner, in order to
perform its cleaning function properly, has a somewhat
different structure. First, it will generally be made of
an absorbant material so that it can absorb a cleaning
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liquid. Second, since the cleaning is achieved by a
wiping action against the drum, and possibly other
components of the player/recorder, the friction of the
cleaning ribbon moving relative to the dr~m may be
somewhat greater than the friction of the conventional
magnetic tape moving through the player/recorder and
against the drum. Further, the cleaning ribbon is quite
often made somewhat thicker than the conventional
magnetic tape, so it would be more absorbant, with the
result that if the cleaning ribbon is arranged so that it
moves through the player/recorder along generally the
same path a~ the magnetic tape, the greater stiffness of
the cleaning ribbon (relative to the magnetic tape) might
create greater resistance to the movement of the cleaning
ribbon. Overall, these various operating characteristics
of the cleaning ribbon sometimes create sufficient
resistance to the operating components of the
player/recorder so as to trigger an automatic shutoff
mecbanism of the player/recorder, thus prematurely
stopping the cleaning action.
A further complicating factor is that quite commonly
the action of the cleaning fluid increases the frictional
force resulting from engagement of the wetted ribbon
against the drum. Thus, there is a tendency for the
cleaning ribbon to create an excessive resisting force to
the rotation of the drum, thus prematurely triggering the
shutoff mechanism of the player/recorder. There have
been various attempts to lower the resistance created by
the cleaning ribbon, such as modifying the material used,
the thickness of the material, the material's absorbancy,
etc. In some instances, such attempts to decrease the
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frictional resistance or other resistance have the effect
of diminishing the cleaning effectiveness of the ribbon.
~264374
SUMMARY OF l~E INVENTION
It is an object of the present invention to provide a
cleaning apparatus and method for a video
player/recorder, particularly ada~ted to alleviate some
of the problems noted above, while properly performing a
cleaning function.
The cleaning apparatus of the present invention is
arranged to clean a playing and/or recording machine,
where the machine has:
a. a structure defining a recess to receive a
tape cassette, said recess having a forward
portion to receive a front portion of said
cassette, and a rear portion to receive a
rear portion of said cassette;
b. a head c~rrying member which carries a
rotating head element and has a curved
peripheral surface;
c. first and second guide means movable between
first and second nonoperating positions,
respectively, and first and second operating
positions, respectively, said first guide
means in said first nonoperating position
being located at a first retracted guide
location, said second guide means in said
second nonoperating position being located at
a second nonoperating guide location, said
first guide means being arranged 80 that with
a tape cassette in the recess, the first
guide means in moving from the first
nonoperating position to the first operating
position engages a first tapP portion
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positioned along a first section of the front
portion of the cassette and moves the tape
outwardly from the cassette into engagement
with a first side portion of the peripheral
surface of the head carrying member, said
second guide means being arranged so that
with the tape cassette in the recess, the
second guide means in moving from the second
nonoperating position to the second operating
position engages a second tape portion
positioned along a second section of the
front portion of the cassette and moves the
tape outwardly from the cassette into
engagement with a second side portion of the
head carrying member.
The cleaning apparatus comprises a housing having a
front portion, a back portion, and first and second side
portions. m e housing is adapted to be positioned in the
recess of the machine.
A cleaning ribbon is mounted in the housing in a
manner to have a first retracted position and a second
cleaning position. The ribbon has first and second end
portions operatively connected to the housing, and a
third intermediate portion which, with the ribbon in its
first retracted position, and with the housing positioned
in the reces~, extends along a forward edge portion of
the housing. First and second sections of the
intermediate ribbon portion are positioned forwardly of
the first and second retracted guide locations,
respectively, when the housing is positioned in the
recess of the machine. mere is a locating element
mounted to the housing at a stationary location at the
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front portion of the housing. This locating element is
positioned between the first and second retracted guide
locations, when the housing is positioned in the recess
of the machine.
The locating element is positioned forwardly of a
third adjacent section of the ri~bon which extends
between the first and second sections. The locating
element is positioned, with the housing located in the
recess, relative to the first and second guide means and
relative to the peripheral surface of the head carrying
member, in a manner that when said first and second guide
means engage said first and second sections of the
intermediate ribbon portion and move outwardly to their
first and second operating positions, the locating
e}ement restrains outward movement of the third section
of the intermediate ribbon portion so as to maintain said
third ribbon section out of engagement with the
periperhal surface of the head carrying member. This is
accomplished in a manner that the peripheral surface of
the head carrying member is engaged by the cleaning
ribbon along an arcuate length of the peripheral surface
which is less than an arcuate length of engagement of the
tape when the tape in said tape cassette is in said
operating position extending in a curved path around the
peripheral surface of the head carrying member.
}n the preferred embodiment, there are first and
~econd spool means rotatably mounted to the housing at
first and second spool locations to engage first and
second sprockets, respectively, of the machine. The
first and second end portions of the ribbon are connected
to the first and second ~pool means, respectively.
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In ~he preferred configuration, the locating element
comprises a roller rotatably mounted in the housing so as
to engage the cleaning ribbon with a relatively low
frictional engagement.
Also in the preferred form, the cleaning ribbon is a
wettable ribbon adapted to receive a cleaning solution on
the ribbon, in a manner that when the ribbon comes into
engagement with the peripheral surface of the head
Q rrying member, the cleaning solution is able to be
applied to the head carrying member.
In the specific embodiment shown herein, the cleaning
apparatus is provided with means to enable the cleaning
ribbon to be wetted at spaced locations along its length.
Thus, the ribbon has alternate wetted and dry locations
along the length of the cleaning ribbon. Specifically,
the housing is provided with opening means enclosing
spaced segments of the ribbon. This permits application
of a cleaning solution at said spaced locations by
applying the cleaning solution through the opening means.
In the preferred form, the cleaning ribbon has first
and second contact portions which engage first and second
surface portions of the peripheral surface of the head
carrying memher. There is a third surface portion of the
peripheral surface of the head carrying member which is
out of contact with the ribbon, this third surface
portion being located between the first and second
surface portions and facing the third ribbon section.
Desirably, this third portion of the peripheral surface
of the head carrying member is at least about l/4th of a
circle in arcuate length around the head carrying member.
Further, each of the first and second contact
portions of the cleaning ribbon engage first and second
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surface portions of the peripheral surface of the head
carrying member along an arcuate length of the peripheral
surface no greater than approximately l/8th of a circle.
In the method of the present invention, a cleaning
apparatus is provided as described above. The cleaning
apparatus is placed in the recess of the machine, and the
first and second guide means are caused to move outwardly
to bring the cleaning ribbon into cleaning engagement
with the peripheral surface of the head carrying member.
The locating element is utilized to restrain out~ard
movement of the cleaning ribbon in the manner described
above.
Other features of the present invention will become
apparent from the following detailed description.
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BRIEF DESCRI~ION OF T~IE DRA~ING
Figure 1 is a plan view of a typical video tape
cassette and the operating components of one type of a
video player/recorder for which the present invention is
adapted to be used, with the tape being in its retracted
position in the cassette;
Figure 2 is a view similar to Figure 1, illustrating
the tape being extracted from the cassette and in its
operating position;
Figure 3 is a top plan view of a cassette cleaner of
the present invention, shown in its operating position in
a cassette receiving recess of a video player/recorder,
and with a portion of the top cover removed for purposes
of illustration, and with the cleaning ribbon in its
retracted position;
Figure 4 is a view similar to Figure 3, showing the
cleaning ribbon extracted fro~ the cassette cleaner and
in its operating or cleaning position;
Figure 5 is a top plan view similar to Figure 3, but
showing the cassette cleaner of the present invention in
broken lines, and illustrating in full lines the ribbon
tensioning device present in the existing
player/recorder, and with the cleaning ribbon in its
retracted position;
Figure 6 i~ a view similar to Figure 5, illustrating
the ribbon positioned outwardly in its cleaning position,
and with the tensioning device of the player/recorder
operating to control tension on the ribbon; and
Figure 7 is a front elevational view taken at
line 7-7 of Figure 3 and illustrating a retaining element
126437A
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or roller of the cassette cleaner of the present
invention.
~264374
DESCRIpTION 0~ THE_PRE~ERRE~ EMBODIMENT
The present invention is particularly adapted to
clean the operating components of a video
playing/recording unit which is adapted to accept
cassette-type playing tapes, where the tape is extracted
by guide members to be positioned in its
playing/recording location in a manner that the tape
extends in approximately a 180 arc around the periphery
of the drum. Further, the tape is positioned so that one
set of vable guide members ~ulls the tape outwardly
from the cassette housing to be positioned along one side
of the drum, while a second set of guide members pulls
the tape outwardly so as to be positioned on an opposite
side of the drum, with the tape extending along the 180
arc between the two sides. Accordingly, it is believed
that a clearer understanding of the present invention
will be obtained ~y first describing the operating
components of such a conventional video playing/recording
unit, and then describing the present invention. In the
following description, the video playing/recording
unit 10 will be referred to as ~the video unit~ or simply
as ~unit~.
In Figures 1 and 2, some of the main operating
components of the video unit 10 are shown in plan view,
with a conventional tape cassette also being shown in
plan view in its operating position in the video unit.
In the illustrations of Figures 1 and 2, the housing,
circuit co~ponets, operating knobs and certain other
components of the video unit 10 are not shown, since
these are not required for an understanding of the
present invention.
~264374
me tape cassette 12 comprises a case or housing 14
and a magnetic tape 16. The tape 16 is wound on right
and left ~pools 18 and 20, the tape extending from one
spool 18 to a location 22 at the front left corner of the
case 14, thence along the front edge 24 of the case 14 to
the ri~ht front location 26, and thence back to the right
spool 20. In Figure 1, the tape 16 is shown in its
nonplaying or retracted position, and in Figure 2 in its
operating position.
To describe the operating components of the video
unit 10, there are three magnetic operating components
which either respond to the magnetic signals on the
tape 16, affect the magnetic signals on the tape 16, or
do both. These magnetic operatin~ components are: an
erase head 28, a drum 30 with a playing head or
element 32, and an audio head 34. The drum 30 has the
general configuration of a circular disc (i.e. a shallow
cylinder), and has a peripheral cylindrically-shaped
operating surface 36. The playing head or element 32 is
mounted at the peripheral surface 36 and in this
particular player/recorder, the drum 30 itself rotates
about the center axis 38.
The unit 10 also comprises a number of mechanical
components which operate directly on the tape 16 to
properly position the tape 16 in the operating mode, and
also to move the tape 16 along its operating path.
First, there is a capstan 40 and a pinch roller 42.
Further, there are guide rollers 44 and 46. Finally,
there are six moveable guide members designated 48-58,
respectively. In operation, the guide members 50-58
engage the back side of the tape 16 and move it outwardly
into the playing position shown in Figure 2. In this
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particular unit 10, three of the guide rollers (50-54)
carry the tape 16 outwardly along one side of the
drum 30, while two other guide rollers 56 and 58 carry
the tape 16 to the opposite side of the drum 30, with the
guide roller 48 performing a locating function.
There is a first drive sprocket 60 which fits into
the center portion of the right spool 20 in a spline fit
so that it is able to drive the spool 20. There is a
second take-up sprocket 62 which fits through the center
of the left spool 18 in a spline fit. When the tape
cassette 12 is initially placed in the unit 10, the
unit 10 is in its nonoperating position, and the
operating components are in the position shown in
Figure 1. When the unit 10 is placed in its operating
mode, the guide members 48-58 move outwardly to the
position of Figure 2, and the pinch roller 42 moves
rearwardly to press the right hand portion of the tape 16
against the capstan 40. Also, the drive sprocket 60
rotates the sprocket 20 clockwise to cause the tape 16 to
be wound thereon.
There is a shutoff light 64 which fits in a matching
recess formed in the forward middle portion of the bottom
of the case 14. At the forward portions of the left and
right edges of the case 14, there are two openings 66
and 68, respectively. The unit 10 has a left
photocell 70 positioned adjacent the left side of the
ca~e 14 and in alignment with the light 64 and the left
opening 66. In some instances, there may be a right
photocell 72 positioned adjacent the right side of the
case 14 and in alignment with the light 64 and the right
opening 68. During normal operation, the photocell 70
(and the photocell 72 if it exists) is shielded by the
~264374
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tape. However, when the tape 16 travels to its end
position, there is a clear leader portion which permits
the light 58 to activate the photocell 70 ~or the
photocell 72) to activate the shutoff mechanism in the
unit 10.
It is to be understood that the video player 10, the
tape cassette 12 and the above-described mode of
operation of these, already exist in the prior art.
To describe the present invention, reference is
presently made to Figures 3 and 4, where a cassette
cleaner 74 of the present invention is shown in ~ts
operating position in the video unit 10. As a matter of
minor clarification, the prior art video unit 10 which is
shown in Figures 3-6 is of the same basic type as that
shown in Figures 1 and 2 and already exists in the prior
art, but has some minor differences. The somewhat
modified prior art version of the video unit 10 is shown
in Figures 3-6 primarily for convenience of illustration
and also for convenience in explaining certain operating
characteristics of such a prior art video unit, and more
specifically, the tape tensioning means of the video
unit 10. The specific structural differences in the
unit 10 shown in Figures 3-6 will be explained later
herein. ~owever, it's to be understood that the cassette
cleaner 74 of the present invention could be used with
either of the video units (i.e. the one shown in
Figures 1 and 2, or the one in Figures 3-6).
The cassette cleaner 74 of the present invention
comprises a ca~e or housing 76 which is or may be
substantially similar to the housing 14 of the
conventional tape cassette 12. As shown herein, this
housing 76 comprises a front wall portion 78, a rear
126~374
wall 80, two side walls 82, a top wall 84 and a bottom
wall 86 (a small portion of which is shown in Figure 3).
Further, the front edge portion of the housing 76 is
formed with two recesses, nhmely a left recess 88
provided to accommodate the guide members 50', 52 and 54,
and a central forward recess 90, located to accommodate
the two movable guide members 56 and 58.
A cleaning ribbon 92 is mounted in the housing 76 in
a manner that a first left end portion g4 is connected to
a left spool 96 and a second right end portion 98 is
connected to a right spool 100. me two spools 96
and 100 are mounted in the housing 76 in generally the
same manner and in generally the same location as the
~pools 60 and 62 in the conventional tape cassette 12, so
that these spools 96 and 100 engage the drive spindles 62
and 60 of the player/recorder unit 10.
As shown in Figure 3, the left end portion 94 of the
ribbon 92 extends forwardly to engage and extend around a
locating pin 102 positioned in the left forward corner of
the housing 76. From the pin 102, the ribbon 92 extends
at 92a across the forward part of the aforementioned left
forward recess 88. The ribbon 92 then extends from the
ribbon portion 92a to engage the front edge of a left
locating wall or abutment 104 and then moderately
rearwardly and to the right to reach behind a locating
element or roller 106 and then extend further to the
right and moderately forwardly to engage a forward edge
of a second right abutment or locating wall 108. This
locating roller 106 is particularly critical in the
operation of the present invention, and its function will
be discussed more fully later herein in the description
of the operation of the present invention. That portion
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of the ribbon 92 extending between the two abutments or
walls 104 and 108 and behind the locating roller 106 is
designated 92b.
The ribbon 92 extends from the ribbon portion 92b
further to the right, as at 92c, to be positioned at the
forward portion of the aforementioned recess 90 and then
extends further to the right to a forward end location
adjacent to the capstan 40. The locating of the right
forward portion of the ribbon 92 can be accomplished in a
number of ways. In the particular embodiment shown
herein, there is provided a pair of cleaning pads, namely
a first pad 110 positioned to engage and clean the
capstan 40, and a second pad 112 positioned to engage and
clean the pinch roller 42. The cleaning ribbon
portion 92c extends from the right locating wall lOB to
engage the forward end of the capstan pad 110, and to
extend therefrom at 92d to engage the spool 100. These
cleaning pads 110 and 112 can be mounted and positioned
in accordance with teachings presently existing in the
prior art.
The top wall 84 of the housing 76 is provided with a
removable circular cover 114 that fits over the left
spool 96. This cover 114 i6 provided with a pair of
diametrically opposed openings 116 which are positioned
to expose portions of the cleaning ribbon 92. By
applying a cleaning fluid through these openings 116 and
onto the ribbon 92, the ribbon 92 becomes wetted with the
solution at spaced locations along the length thereof.
To describe the operation of the present invention,
the cleaning ribbon 92 is positioned so that the
ribbon 92 is wound a number of times around the left
spool 96 so that several overlapping portions of the
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ribbon 92 appear at the openings 116 which are for~ed in
the top cover 114. Further, the ribbon 92 is positioned
so that the forward ribbon portions 92a-c fit closely
against the front edge portion of the housing 76. Then a
cleaning solution is applied through the openings 116 to
wet portions of the ribbon ~2, this resulting in a wetted
pattern of alternate wet and dry portions of the
ribbon 92.
Then the cassette cleaner 74 i~ inserted into the
recess or cavity 118 that already exists in the
player/recorder 10, and which is arranged to receive the
conventional ~ape cassette 12. This recess 118 is
indicated somewhat schematically in Figures 3 and 4 by
showing at 120 a portion of the video unit structure
which defines the cassette receiving recess 118. With
the Cassette cleaneL 74 so positioned, as shown in
Figure 3, the three left guide members 50', 52 and 54 are
positioned in the forward cassette housing recess 88,
while the two movable guide members 56 and 58 are located
in the cassette housing recess 90. Further, the cleaning
ribbon portion 92a is positioned just forwardly of the
guide members 50', 52 and 54, while the cleaning ribbon
portion 92c is positioned just forwardly of the two
movable guide member~ 56 and 58.
With the cassette cleaner 74 positioned as shown in
Figure 3, the operating knob or button of the video
unit 10 is moved to the play or record position to cause
the guide members 50' and 52-58 to move outwardly from
the two recessed areas 88 and 90 to the positions shown
in Figure 4. m e guide members 50', 52 and 54 carry a
left forward portion 92e of the ribbon 92 outwardly so
that it comes into engagement with the erase head 28, the
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StatiQnary guide roller 46 and with a left
circumferential portion 36a of the surface 36 of the
drum 30. The two right guides 56 and 58 carry the
ribbon 92 forwardly so that there is a ribbon portion 92f
which comes into cleaning engagement with the audio
head 34 and with a right peripheral portion 36b of the
cylindrical surface 36 of the drum 30.
It will be noted that the locating roller 106 engages
and restrains the cleaning ribbon portion 92b so that one
ribbon portion 929 extends from the drum surface
portion 36a rearwardly with a moderate slant to the right
ta~ard the locating roller 106, and so that a second
ribbon portion 92h extends from the drum surface
portion 36b rearwardly with a moderate slant to the left
toward the locating roller 106.
The locating roller 106 is so positioned, relative to
the location of the guide member 54 and the drum
surface 36, that the length of the drum surface
segment 36a that is engaged by a related contact portion
of the cleaning ribbon 92 is approximately 45 in arcuate
length (i.e. about l/8tb of a circle). In like manner,
the locating roller 106 is positioned relative to the
dr~n surface 36 and the locating element 56 that the drum
surface portion 36b that is engaged by a related contact
portion of the ribbon 92 has an arcuate length of
approximately 30. Thus, there is a substantial arcuate
length 36c of the drum surface 36 which is intermediate
to the two portions 36a and 36b and which is out of
contact with the ribbon 92.
Al~o, the capstan 42 moves to press the ribbon 92
against the capstan 40, so that rotation of the
capstan 40 causes the ribbon 92 to move along its length,
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with the ribbon 92 being unwound from the left spool 96
and wound onto the right spool 100. After the cleaning
cycle is accomplished, the guide members 50' and 52-58
are moved back to their retracted positions (e.g. by
turning the control knob of the unit 10 to its ~off n
position), as shown in Figure 3, and the drive
spindles 62 and ~0 operate to cause the ribbon 92 to be
wound onto one or the other of the spools 96 and 100.
(The precise manner in which this occurs may vary,
depending upon the particular type of unit 10 bein~
used . )
To comment on the beneficial results achieved by the
present lnvention, it will be recalled that earlier in
this description it was stated that the locating
roller 106 is significant in the operation of the present
invention. To comment on this further, it has been found
that the utilization of the locating roller 106, in
combination with the other components of the cassette
cleaner 74 and with the operating components of the
unit 10, provides engagement of the cleaning ribbon 92
with the components in a manner to properly achieve the
cleaning action, while alleviating to a significant
extent the problems related to the frictional engagement
of the ribbon 92 with the various components
(e.g. problems of premature shut off of the unit 10 or
possibly inadequate engagement for proper cleaning of the
components). To explain this more fully, reference is
now made to Figures 5 and 6, where the present invention
is shown somewhat schematically in broken lines, and a
cover member or plate member of the unit 10 at the
lo Q tion of the recess 118 is removed to display the tape
tensioning mechanism 122 of the unit 10. It is to be
:~26437~
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emphasized that this tape tensioning mechanism 122 is or
may be conventional, and the mechanism 122 is simply one
type of such mechanism which is known in the prior art.
In this particular arrangement, the tensioning
mechanism 122 comprises a friction band or brake band 124
which curves in an arc of about 180 and is positioned to
engage a cylindrical surface 126 of a disc 128 which is
fixedly connected ts the left spindle 62 at a location
below the spindle 62. One end 130 of this band 124 is
connected to stationary structure at 132 in the housing
of the unit 10. A second end 133 of the band 124 is
connected at 134 to an arm 136 that is pivotally
connected at 138 to fixed structure in the video unit 10
An outer swing end of the arm 136 carries the
aforementioned guide member 50'.
In this particular arrangement of the tensioning
mechanism 122, the guide member 50' is positioned
somewhat differently from the guide member 50 shown in
Figures 1 and 2. me reason for this is believed to be
due simply to differences in the specific construction of
the video unit 10 which is shown in Figures 1 and 2, and
the unit 10 which is shown in Figures 3-6.
To describe briefly the operation of the tensioning
mechanism 122, it will be noted that in the position of
Figure 6, the guide member 50' is moved by an actuating
mechanism (not shown for ease of illustration) to push
the ribbon 92 to the left beyond a line drawn between the
two stationary guide rollers 48' and 48". In the
position of Figure 6, the arm 136 causes the brake
band 124 to come into frictional engagement with the disc
surface 126 to retard rotation of the disc 128, and thus
retard rotation of the spindle 62 attached thereto. As
~Z64374
the capstan 40 and pinch roller 42 continue to move the
ribbon so that the ribbon 92 moves in a direction to be
wound onto the right spool 100, under circumstances where
the brake band 124 is retarding rotation of the
spindle 62, tension on the ribbon 9? will tend to
increase, thus causing the ribbon portion 92 that is
between the guide rollers 48' and 48" to push the guide
member 50' to the right, and thus cause the lever arm 136
to decrease the pressure of the band 124 against the disc
surface 126. This in turn reduces tension on the
ribbon 92. The overall effect of this is that the
ribbon 92 is kept at a substantially constant tension
along its length.
To appreciate the benefits achieved by the present
invention, it is to be recalled that this same tensioning
mechanism 122 acts in substantially the same manner on a
conventional magnetic tape 16 of a conventional tape
cassette 12. Thus, in a conventional video unit 10, the
tape tensioning mechanism 122 will be optimized to
produce just the right amount of tension on the magnetic
tape 16 so that proper operation can be achieved.
Bowever, as indicated previously under ~Background of the
Inventionn, to optimize the cleaning effect of the
ribbon 92, it may be desirable to form the ribbon 92 of a
material which for a given ribbon tension has greater
frictional resistance against the various 6urfaces with
which it comes into contact. Further, the wetting of the
ribbon 92 increases the frictional resistance to a yet
greater extent.
Thus, to alleviate this problem, the locating
roller 106 causes the cleaning ribbon 92 to engage two
relatively smaller arcuate outer surface segments of the
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drum surface 36, in comparison with the arcuate length of
the drum surface 36 engaged by the magnetic tape 16,
operating in the conventional manner, as illustrated in
Figures 1 and 2. The result is that the total frictional
force exerted by the ribbon 92 against the surface 36 of
the drum 30 is substantially less than it would be if the
cleaning ribbon 92 were engaging a full 180 of the
cylindrical surface 36 of the drum 30. Thus, for a given
tension on the cleaning ribbon 92 at the location of the
tensioning guide member 50', the overall resistanoe
created by the ribbon 92 can be kept within appropriate
limits so as not to prematurely trigger any shutoff
mechanisms in the video unit 10.
With regard to the structuring of the locating
roller 106, as shown in Figure 7, in the preferred form
this roller 106 has the configuration of a vertical
cylinder 140, extending between the bottom wall 86 and
top wall 8~, and rotatably mounted to a pin 142 connected
between the walls 84 and 86. m e roller 140 is at a
fixed location relative to the case or housing 76, and
its position $s selected so that the frictional
engagement of the ribbon 92 with the drum 30 and with the
other components is optimized to allow proper cleaning
action and not create excess frictional force.
It is to be recognized that various modifications
could be made to the cleaning cassette 74 of the present
invention, and to the method of using the same, without
departing from the basic teachings thereof. Further, the
preceding description is not intended to be limiting, and
is given by way of describing the presently preferred
embodiment of the present invention.
