Note: Descriptions are shown in the official language in which they were submitted.
223~35~
This invention relates to a cassette that has a releas-
able clutch assembly for permitting one of its reels to be rotated
in one direction only until released.
It will be described in relation to a video tape cas-
sette for which there is a requirement to permit the tape to be
wound from the supply reel to the take-up reel but then to prevent
rewinding to the supply reel except under the control of the per-
son responsible for the further use of the tape. The requirement
arises in the business of renting tape cassettes. Owners of pro-
prietary material contained on these tapes rent them and they
would like to be assured that the lessee will play the tape past a
reproducing head of a video tape machine only once. The producer
of a movie, for example, who places his movie on a video tape cas-
sette has it available to him to rent such a cassette to the many
owners of video tape playing machines. If, however, on one single
rental, and for one rental fee, the tape is played many times the
owner of the movie is deprived of the value of his proprietary in-
terest in the copyright to the movie if he receives a rental for
only one play of the tape.
It is an object of this invention to provide a tape or
wire cassette with a reliable, inexpensive clutch mechanism that
will permit the tape or wire to be wound from one reel to the
other but not rewound to the first reel until the clutch mechanism
has been released by application of a means that can be retained
within the knowledge of the tape owner.
~ . . . . .
1~3853
With this and other objects in view, a tape or wire cas-
sette having a casing and reels mounted for rotation within the
casing and connectable to a rotatable drive shaft to transfer tape
from one reel to the other is characterized by: locking means for
locking one of said reels against rotation with respect to the cas-
ing in only one direction when operative; said locking means being
releasable to render it inoperative and to permit said reel free
rotation with respect to the casing in either direction; said lock-
ing means including a roller cage, brake means and rollers; one of
said roller cage and brake means being nonrotatable with respect
to said body the other of the roller cage and brake means being
nonrotatable with respect to the reel; said roller cage having a
series of channels arranged in a circle; each channel of said
series of channels having one of said rollers therein; said brake
means having a brake surface; said roller cage and said brake sur-
face of said brake means defining a space therebetween that is an-
nular in cross section, each of said channels of said series of
channels having a ramp surface at its bottom that slopes towards
the brake surface on the brake means in the direction against
which the locking means locks; said rollers being moveable longi-
tudinally of their respective channels between positions to actu-
ate said locking means between an operative position and an inoper-
ative position, said operative position being one where they can
cooperate with the roller cage and brake means to wedge between a
brake surface of the brake means and the ramp surface of the rol-
ler cage to lock against rotation of reel with respect to the cas-
~:23~35~
ing in one direction and permit free rotation in the other direc-
tion, the inoperative position being one where the rollers have no
cooperative relation with the roller cage and brake means whereby
to permit free rotation of the reel with respect to the casing in
either direction of rotation. The invention will be clearly under-
stood after reference to the following detailed specification read
in conjunction with the drawings.
In the drawings:
Figure 1 is an illustration of a video tape cassette;
Figure 2 is an exploded view of the clutch assembly des-
cribed herein;
Figure 3 is a sectional view through the clutch assembly
of the take-up reel illustrating the rollers in wedging relation
between the roller cage and brake;
Figure 4 is a partial sectional view through the clutch
assembly along the line 4-4 of Figure 3 illustrating the manner in
which the rollers are caused to wedge between the ramp surface of
the channels of the roller cage and the brake ring as will be des-
cribed;
Figure 5 is an illustration similar to Figure 3 but il-
lustrating the rollers in an inoperative position wherein the rol-
lers have been moved longitudinally of themselves to cause their
respective grooves to be located opposite the brake ring whereby
to render the clutch inoperative;
Figure 6 is an illustration showing the relationship of
the brake ring and the pins in the inoperative position;
, .. .
:~L2~38~;3
Figure 7 is an illustration of a cross-section through
one end of a cassette illustrating an alternativ~ embodiment; and
Figure 8 is an illustration along the lines 8-8 of
Figure 7.
The drawings generally refer to a cassette for a video
tape. It has a suppIy reel 12 and a take-up reel 14 mounted for
rotation within a body generally indica-ted by numeral 10. In use
the cassette is mounted in a video machine and the tape is drawn
past a video playing or recording head as it is taken from the
supply reel to the take-up reel. The tape can be rewound on the
supply reel by reversing the tape drive. The general construction
of the cassette and its use in a video tape machine is well known
and not referred to in any further detail in this specification.
This invention is concerned with a clutch between the
take-up reel, in the case of the embodiment described herein, and
the body of the cassette. The purpose of the clutch, while opera-
tive, is to permit tape feed in one direction only so that the
tape can be wound onto the take-up reel from the supply reel but
cannot be rewound from the take-up reel back to the supply reel
unless the clutch is rendered inoperative. Alternatively, the
clutch can be designed to lock the supply reel against rotation
that permits transfer to the take-up when operative. Provision is
included in the clutch for rendering it inoperative.
Figure 3 is an illustration of a cross-section of the
take up reel which illustrates the operation and design of the em-
bodiment illustrated. In this drawing, the take-up reel is gener-
ally indicate~d by the numeral 14. It has a conventional winding
~223853
surface upon which the tape can be wound and a central opening 16,
the wall of which is keyed for connection to a drive spindle of a
conventional tape deck.
The assembly includes a roller cage 18 which is maintain-
ed nonrotatable with respect to the body of the cassette. The rol-
ler cage 18 is illustrated in Figure 2. It has a series of axial-
ly aligned channels 20, each adapted to receive a cylindrical rol-
ler clutch element 22. Cylindrical roller clutch elements 22 il-
lustrated are supported at one end by the flanged bottom of the
roller cage and are urged into contact with the bottom by compress-
ed springs 24. A spring holder ring 26 is provided with a boss
28 for the upper end of each spring and is, in turn, held in posi-
tion by the housing 30 which is rigidly mounted on and secured
with respect to the rotatable reel 14. Housing 30 has an inwardly
directed brake ring 32 the brake surface of which bears against
the side of the roller elements 22 to prevent rotation in one
direction when the clutch is operative. Housing 30 has a flange
31 at its lower edge that is sprung over a mating flange on the
roller cage as illustrated in Figure 3. This is a free fit that
permits the relative rotation of the parts as described. Princi-
pal parts are moulded from a plastics material.
In use, the cassette with its clutch assembly is mounted
on the tape deck in the usual way, the drive splines 16 being stan-
dard and connecting with the standard drive spindles on the tape
deck. The roller cage 18 is nonrotatable with respect to the cas-
sette body and when driving power is applied to the take-up reel
~23~353
to rotate the takeup reel, the clutch assembly just described
will, when operative, permit the free rotation of the reel and the
associated housing 30 with respect to the cassette body and roller
cage in one direction only. The roller cage in the embodiment il-
lustrated has a flat strip of brass 19 that engages in a hole in
the cassette body to prevent relative rotation between roller cage
and cassette body. The operation of the clutch will now be des-
cribed.
The channels 20, cylindrical rollers 22 that are move-
able longitudinally of the channel, and locking ring 32 are ele-
ments of a novel roller clutch assembly that is able to achieve
the desired result in a very efficacious manner.
Figure 4 illustrates the operation of the clutch. The
channels 20 which house the rollers 22 have a flat ramp surface 34
at their bottom. When a force is applied to rotate the reel 14 in
the lock direction as indicated by the arrow 36, the rollers 22
wedge between the locking ring 32 and the ramp surface 34 of the
channels 20 to lock the reel against further rotation with respect
to the cassette housing. When the reel is rotated in the opposite
or free-wheeling direction the rollers 22 tend to move in the
direction of rotation and become freely spaced between the chan-
nels 20 and ring 32 so that rotation is possible. The dotted line
position of roller 22 illustrates an extreme free position of the
rollers on the ramp. In use they do not move this far to the
right. They move to the right and down their respective ramp only
a sufficient distance that permits free rotation of the reel.
lZ23853
The design of the rollers, surfaces of the roller cage,
the ramp and the ring 32 under these conditions is according to
standard roller clutch design practice.
In this connection the numeral 38 is a line from the
center of rotation of the reel through the longitudinal axis of
the roller when the roller is in wedging relation with the ramp.
Numeral 37 is a line that is tangent to the ramp surface at the
point of contact of the roller with the ramp and line 40 is a line
at right angles to line 38 and through the point of contact of the
roller with the ramp. The contained angle "alpha" between lines
37 and 40 is, in the case of the design illustrated, about 10
degrees and is herein referred to as the ramp angle. According to
standard design practice for clutches of this nature, this angle
should be smaller than the angle of friction between the roller
and the ramp surface. The roller, in the case of the design illus-
trated, is aluminum and the ramp surface is an acetal resin.
The direction of the longitudinal axis of the springs 28
is biased to urge the rollers with a slight force in a direction
up the ramp in the embodiment of the invention illustrated. The
upper ends of the springs are located by bosses 28 on the spring
holder ring 26 and by rotating the spring holder slightly in the
same direction as the arrow 36 one can achieve a latteral spring
force on the springs that biases the rollers slightly in the direc-
tion of up the ramp as viewed in Figure 4. It has been found that
if the upper end of the spring is about one or two degrees from
the longitudinal axis of the locking pin that good biasing is
~223853
achieved. The lateral biasing spring force is small and substan-
tially unrelated to the compression spring force that forces the
rollers downwardly.
In the case where the clutch assembly is normally in use
in a horizontal position the springs 24 can be dispensed with, the
rollers being urged to the downward position by gravity. In this
case the rollers are free to move laterally and this freedom to-
gether with bearing play between the roller cage and the locking
ring will enable wedging engagement upon attempt to reverse rota-
tion of the reel.
An important feature of the clutch assembly is its abili-
ty to be released to permit rotation in either direction. This is
achieved by moving the rollers longitudinally of their respective
channels from an operative position between the roller cage and
brake ring to an inoperative position between the roller cage and
brake ring.
Each of the rollers has a circumferentially extending
groove 42 which, under conditions of normal operation of the clutch,
is spaced from the locking ring to put the rollers in wedging capa-
bility. However, the rollers can be moved axially of themselves
against the compressed roller springs 24 or against the gravity of
their own weight when no springs are used. This can be achieved by
means of inserting a pin through a hole in the bottom of the roller
cage 16. With an appropriate length pin the rollers can each be mov-
ed longitudinally of their respective channels so that their respec-
tive grooves 42 are aligned laterally with the braking surface of
:lZ238~i3
the locking ring 32. The width and depth of the grooves is of a
dimension so that when this occurs the locking ring can no longer
be in wedging contact with the rollers so that they cannot wedge
between the ramp surface of the roller cage and brake ring as
explained above and the reel can be rotated freely in either
direction. The rollers are out of wedging capability. The
opening in the bottom of the cassette body through which the
central opening 16 extends is large enough to expose the bottom of
the casing 18 for access by pins.
The grooves 42 are located at four different elevations
longitudinally of their respective pins. To achieve an effective
release of the clutch operation it is necessary that the grooves
of all rollers be aligned with the locking ring. Thus, it re-
quires pins of four different pin lengths to locate the various
rollers in a disengaged position where they are spaced so that
they cannot wedge between the roller cage and the brake ring. The
locking pins 46 can be conveniently mounted on a ring 44. Ring 44
with correctly sized pins and in correct rotational relationship
with respect to the reel will serve to move each of the rollers to
a location where its groove is aligned with the locking ring with
one operation. It will be apparent that the number of combina-
tions of pin lengths and ring positions is large. It is 413,
only one of which will render the clutch inoperative.
Figure 5 is a cross-sectional illustration which shows
the ring 44 in place and one pin which elevates its roller to the
inoperative position. Each of the other pins actuates its respec-
tive roller in the same manner.
, ~
~;~23~53
Thus, it is necessary to have a ring that is co-related
to the design of the rollers in respect of their grooves to free
the clutch for rotation in either direction.
The rollers are put in at manufacture in a known order
and cannot be easily tampered with so that, in effect, it requires
a ring of a very special pin size and arrangement to free the
clutch. This is a security feature for the clutch. The ring must
be aligned with the roller cage in the direction of rotation and
this is achieved by aligning marks 45 nd 47 on the roller cage and
ring respectively.
It has utility in the case where it is desired to pre-
vent the showing of a particular tape. Unless freed, it can be
locked against rotation in the cassette in one direction.
The locking ring is thin enough to be located on the out-
side of the cassette casing and permit the cassette to operate in
the usual way on a tape deck.
The invention has been described for use with a one play
tape cassette. The clutch assembly could also be used to lock the
cassette from play unless a locking ring like ring 44 were insert-
ed. In this case it would be installed on the supply roll of the
cassette, the ramp would slope in the opposite direction and the
clutch would lock rotation of the supply reel unless a release
ring like ring 44 is inserted.
Alternative ways for operating the rollers into and out
of the inoperative position will be apparent to those skilled in
the art. The important thing is a roller clutch of a design that
~23853
can be rendered operative and inoperative by manipulation of a
series of rollers or the like to a predetermined position in the
channel of the roller cage the location of which is secure and
confidential to the owner of the cassette.
While a cylindrical roller has been used it is contem-
plated that other rollers such as balls could be used and also
that other means for taking the rollers into and out of wedging
capability between the ramp surface of the channels and the brake
surface could be used. If ball rollers were used they could be
rendered inoperative by causing them to enter into a round hole in
the bottom of the channel that was located at a predetermined dis-
tance between the ends of the channel. The form oE the brake and
channels is also capable of variation within the scope of the
invention.
Figures 7 and 8 illustrate a further embodiment of the
invention. Figure 7 is a cross-sectional view through an end of a
cassette and Figure 8 is a view along the line 8-8 of Figure 7,
but showing only the reels of the cassette that have the releas-
able locking means.
A reel 52 is mounted within the casing for rotation. It
is a standard reel and has a splined opening 54 for connection to
a drive shaft of a tape deck. The roller cage 56 is kept from ro-
tation with respect to the casing 50 by means of arms 76 that ex-
tend from the roller cage and set between posts 78 on the casing.
Roller cage 56 has a series of channels 58, that open towards the
centre of rotation of the reel. There are two brake surfaces, an
, ~ .. . ........ .. .. .. . . .. .. . .. . .
~223853
upper one 60 being formed integral with the reel and a lower one
62 which is separately formed and rigidly secured to the reel.
The channels 58 each have a ramp surface 64 and rollers 66 in each
of the channels 64 can be moved longitudinally of the channels
between an operative position wherein they can wedge between the
ramp surface 64 of their respective channel 58 and one of the two
break surfaces 60 or 62 to permit rotation of the reel in one
direction only and an inoperative position wherein they have no
cooperative relation with the brake surfaces and permit rotation
of the reel in both directions.
The roller 66 on the left hand side of Figure 7 is shown
in wedging relation between the ramp surface 64 of its channel 58
and the lower break surface 62.
The ramp surface 64 is designed to have a slope such
that the wide diameter of the rollers 66 will wedge between the
ramp and a brake surface when the reel is turned in one direction
with respect to the casing, but roll down the ramp and space it-
self between the ramp surface and the locking ring when the reel
is rotated in the opposite direction. The principles of design of
the ramp to achieve this purpose have been explained in associa-
tion with the embodiment of Figure 1 and will not be referred to
in detail again in connection with this embodiment.
In the embodiment illustrated the roller cage and break
engage when the rollers are in an operative position in their
respective channel and there is rotation of the reel in the direc-
tion of the arrow 68.
12
12X3853
With this embodiment it will be noted that all rollers
66 are of the same dimension, the only difference between them
being that they can be inserted with the small diameter up as
illustrated on the left of Figure 7 or with the small diameter
down as illustrated on the right of Figure 7.
To move any roller so that it is inoperative, one moves
the roller longitudinally of its char.nel so that the large dia-
meter of the roller is opposite the groove 70 between the two
break surfaces 60 and 62 of the brake means. When the large dia-
meter of a roller is in this position there is too much space be-
tween the ramp surface of the roller cage and the reel to achieve
any clutch action and the reel is free to rotate in the body cas-
ing in either direction of rotation.
This embodiment has advantage in that there is only one
design of roller and only two positions of vertical adjustment for
each roller. The roller on the left hand side of the drawing is
shown in its lower position. When moved to its second or upper
position its large diameter is aligned with the groove 70 and it
becomes inoperative. The roller on the right hand side of the
Figure 7 is shown in a inoperative position but can be rendered
operative by moving it longitudinally of its channel to its upper
position. The rollers can be moved between their two positions of
ad~ustment by means of pins 72 that are mounted around the ring
74. The channels of the roller cage are accessible through holes
in the bottom of the casing and the roller cage to permit the pins
to enter and move the rollers between their two positions one of
13
~LZZ3~3
which is operative and the other inoperative from the clutching
operation point o view.
The rollers illustrated on t'ne left hand side of Figure
7 are illustrated in a position wherein they cooperate with the
roller cage and break ring to achieve clutch action and the rol-
lers on the right hand side of Figure 7 have been illustrated in
the noncooperative position wherein they permit relative rotation
between the reel and casing in both directions. To achieve free
rotation of the reel they should all be moved to the inoperative
position.
This embodiment has the channels outboard of the break-
ing surfaces and provides for reel hub of reduced diameter and a
greater reel tape capacity. The release is more simple because
there are only two positions of each roller in its channel. The
roller design is uniform. At the same time there are over 67 mil-
lion roller position combinations in a clutch assembly having 26
rollers.
The release need not be performed by a ring. Any means
for making the movement is possible. A solenoid could be used in
the case of a ferrous metal roller. With this embodiment and only
two positions of the roller it would only be necessary to provide
an up and a down solenoid movement, each of which could be against
a stop.
In use the owner could rent a cassette for a single
playl repossess it after it had been played once, render the
clutch inoperative, rewind the tape, render the clutch operative
14
~3~5~
and rerent it for a further single play. This is a practical use
of the device and in this case a more sophisticated release
mechanism to perform the function of the rings would likely be
used.
Embodiments of the invention other than the ones describ-
ed will be apparent to those skilled in the art and it is not in-
tended that the invention should be restricted to the embodiments
described.
