FR2601805A1 - SPOOL BRAKE FOR MAGNETIC TAPE CASSETTE - Google Patents

Abstract

THE INVENTION RELATES TO A CASSETTE SPOOL BRAKE. IT RELATES TO A BRAKE INCLUDING A BODY 101 WHICH PUSHES TWO RATCHETS 105, 106 WHICH DIFFER FROM ONE OF THE OTHER AND WHICH ARE THINNED IN THEIR MIDDLE PART 107, 108. THE RATCHETS STOP AGAINST BUTTONS 119, 120, 122 SO ALTHOUGH THEIR ELASTIC DEFORMATION IS LIMITED. IN THIS WAY THEY MAY ALWAYS REMAIN IN CONTACT WITH A CUT 103C SHAPED IN THE LOWER PLUG OF THE COIL. THE COILS ARE THEREFORE PERMANENTLY BRAKED. APPLICATION TO MAGNETIC TAPE CASSETTES FOR VCRs.

Description

The present invention relates generally to a coil brake

  for preventing the rotation or pivoting of a magnetic tape support coil in a magnetic tape cassette, in a direction which introduces play into a strand of the tape. More specifically, the invention relates to a reel brake that prevents rotation of the reel that supports the tape when the cassette is not in use, even when vibrations are applied to the cassette. In a magnetic tape cassette such as a video cassette (videocassette cassette), a pulse code modulation (PCM) audiofrequency cassette and the like, used with a recording and / or playback apparatus, a A magnetic tape housed in a cassette housing passes from a supply reel housed in the internal space of the housing to an assembly having a rotating magnetic head placed in the body of the recording and / or read apparatus, the tape then returning to a receiver coil placed in the housing of the

  cassette. The length of the tape section that contacts the set comprising the head in the recording and / or playback apparatus is outside the cassette housing and is exposed when the cassette is not in use. .

  Typically, the magnetic stripe cassette has elastic bands for braking the magnetic stripe as it moves away from and toward a reel, so that the exposed stripe portion of the magnetic stripe does not exhibit undesired play. . However, the conventional coil brake has a tendency to no longer brake and allow rotation of the spool with play in the web as the rotational force is applied to the spool by vibration. More specifically, as the

  conventional reel brake has two braking bands associated with the supply reel and the reel

  trice and who are in solidarity with a body. braking, it moves the braking bands in translation relative to locking teeth of the cheeks of the coils.

  This construction of the conventional coil brake tends to tilt towards a coil when the force

  rotation is applied in one direction. This causes the separation of the other braking band from its cooperation with the locking teeth of the corresponding coil. As this separation is performed, the other coil can rotate and can relax the band.

  It is therefore an object of the invention to provide a reel brake of a magnetic tape cassette which prevents rotation of the reel so that the web

does not present a game

  For this purpose, the magnetic tape reel brake of a cassette has two brake bands associated with the supply reel and the take-up reel.

  The braking bands have at least one hinge section allowing their elastic deformation. Thanks to the elastic deformation of the braking bands, the cooperation of these bands with the teeth can be preserved, even in the presence of vibrations which apply

a rotational force to the coils.

  In a first aspect of the invention, a reel brake for a magnetic tape cassette having a reel having a cheek, the reel being placed in a cassette housing, has a cutout at the outer periphery of the cheek, a set of brake having a body and a brake tongue 30 having a pawl shape, the braking assembly being movable between a locking position in which the brake pawl is in contact with the cut and limits the rotation of the coil, and a unlocking position in which the brake pawl is spaced from the cut and allows the rotation of the spool, and a device associated with the braking assembly and cooperating with the pawl so that it absorbs a force applied to the ratchet. braking assembly by cooperation of the brake pawl with the cutout, the pawl then being driven into the unlocking position, so that the braking assembly can be maintained in the position of blocking. In the preferred construction, the force absorbing device provides flexibility to the brake pawl so that it can elastically deform under the action of the force, so that it is absorbed. The force absorbing device allows elastic deformation of the brake pawl in a predetermined portion. More precisely, by virtue of the deformation of the braking pawl, the kinematic energy intended to be applied to the braking assembly and thus pushing it back, which is moved from the locking position to the unlocking position, can be absorbed. in a satisfying manner. On the other hand, thanks to the flexibility of the brake pawl, the presence of a device intended to limit the amplitude of the elastic deformation of the brake pawl

  may be preferable so that accidental release by separation of the ratchet and the cutout is avoided.

  The device for limiting the deformation may comprise an abutment member oriented near the predetermined portion so that this limitation of the deformation of the pawl is effectively ensured. It is preferred that the abutment member comprises a first member which limits the lateral deformation of the braking pawl in a first direction and a second member which limits the lateral deformation of the braking pawl in

a second meaning, opposite to the first.

  In addition, the coil braking device of the type described may comprise a device for delimiting a longitudinal guide path of the braking assembly, in which this braking assembly moves between blocking and unlocking positions. device defining the guide path comprising

  guide walls disposed along the guide path. In this case, the guide walls comprise a part which acts as a retaining member of the braking assembly on the guide path.

  In addition, the retention portion of the guide walls is preferably used and advantageously as

  first element of the stop member.

  In a convenient embodiment in practice, the force absorbing device may be a thin portion formed in the brake pawl. This thin portion is formed in an intermediate longitudinal section of the pawl and / or at a connecting end of the brake pawle to which the pawl connects

to the body.

  Other features and benefits of

  the invention will be better understood on reading the following description of embodiments, with reference to the appended drawings in which:

  Fig. 1 is an exploded perspective showing the various main elements of a magnetic tape cassette to which is associated an advantageous coil brake embodiment; Fig. 2 is a plan view of the magnetic tape cassette, with torn parts, including a preferred embodiment of the reel brake shown in Fig. 1; Figure 3 is an exploded and enlarged perspective view of a preferred coil brake embodiment of the invention; Fig. 4 is an enlarged plan view of the preferred coil brake embodiment of Fig. 1, shown in a working position in which it blocks the coils; Figures 5 and 6 are plan views analogous to Figure 4 but showing the positions in which rotational and lateral forces are applied to the coils; Figure 7 is a plan view of a coil brake variant according to the invention; and Fig. 8 is a plan view of another

  variant of the coil brake according to the invention.

  We now refer to the drawings and

  particularly in Figures 1 and 2; a preferred embodiment of a reel brake according to the invention is associated with a particular type of magnetic tape cassette particularly suitable for an 8 mm video recorder.

  Although the particular construction of the magnetic tape cassette is described in combination with the preferred coil brake embodiment of the invention, the invention is not limited to the illustrated embodiment of the particular construction of the cassette. magnetic tape, but can take any suitable form suitable for various types of tape tapes. Accordingly, Figs. 1 and 2 show a magnetic tape cassette of a type in which the invention is practiced and is described essentially by way of reference for the understanding of the use of the upper cheek. the coil according to the invention. Reference can also be made to United States Patent Application No. 651,452, filed September 17, 1984, and giving further details on the elements shown.

  in Figure 1. The tape cassette 10 is of a type for use in an 8 mm VCR.

  The cassette 10 has a substantially rectangular cassette housing 11 comprising an upper portion and a lower portion 11A and 11B, two coils having the general references 12A and 12B, housed in the housing 11 so that they can rotate and placed side by side. a magnetic tape 13 being wound on the coils. The cassette 10 has an assembly 14 forming a rear cover and an assembly 15 forming a front cover. The cover 14 is hinged to the housing 11 so that it moves between open and closed positions. In the open position of the cover 14, a strand of magnetic tape formed between the coils 12A and 12B is exposed and can be removed from the housing 11 while, in the closed position, the cover 14 covers the strand of magnetic tape. and surrounds it, both at the front and at the back. The upper and lower portions 11A and 11B of the housing have walls. substantially rectangular upper and lower 17A and 17B respectively and cheeks 18A and 18B are disposed along the margins of the upper and lower walls 17A and 17B respectively and mutually cooperate in a separation plane 15 which is substantially parallel to the walls 17A and 17B when the The housing portions 11A and 11B are vertically aligned with one another, that is, perpendicular to the plane of separation so that these walls form a peripheral structure 20 of the housing. The peripheral structure of the housing has end walls 19 and 20 placed at the relatively short and opposite ends of the housing 11 and a side or rear wall 21 placed along one of the relatively large sides of the rectangular housing. 25 At the front or along the other relatively large side

  of the housing, an opening is formed between the rear cover 14 and the front cover 15 and is practically from one of the end walls 19 and 20 to the other.

  The bottom wall 17B has a cutout 23 of substantially trapezoidal shape which communicates with the passage opening of the strip. Thus, the ends of the cutout 23 are placed at a distance from the walls 19 and

end.

  A substantially rectangular cutout 24 35 having substantially a width equal to that of the cutout 23 is formed in the front portion of the top wall 17A and has a depth less than that of the cutout 23 when measured in the middle of the housing 11. A flange 25A having curved portions protrudes from the top wall 17A behind the cutout 24 and cooperates with a flange 25B having similar bending portions directed upwardly from the bottom wall 17B along the trailing edge 23. When the housing portions 11A and 11B are vertically engaged, the flanges 25A and 25B of the upper and lower housings 11A and 11B cooperate and form a partition wall by means of which a space containing the coils 12A and 12B to the inside of the case is isolated from the opening

22 and the cut 23.

  At the opposite ends of the blank 23, the housing portion 11B has walls 27 and 28 which are formed or molded forwardly from opposite ends of the flange 25B. The walls 27 and 28 are taller than the flange 25B so that they protrude freely from the bottom wall 17B to the top wall 17A in the mounted cassette 10. The surfaces of the walls 27 and 28 which face outwards and which are remote from the end walls 19 and 20 have rounded or semicylindrical portions 29 and 30 acting as a guide for the magnetic tape at opposite ends of the opening. The bottom wall 17B has openings

  31A and 31B, spaced laterally, and in which hubs of the coils 12A and 12B are loosely housed so that the coils are held when they rotate in the cassette 10 and through which pins or shafts The drive (not shown) of a VCR can conventionally cooperate with the hubs of the coils 12A and 12B when the cassette 10 is in the operating position in the VCR.

  The strip 13 which is disposed between the coils 12A and 12B is directed forward from the coils and passes around the guides 29 and 30 so that it forms a strand of tape disposed in front of the opening. The walls 27 and 28 have curved guiding grooves 32 disposed in an approximately vertical direction in the inwardly facing surfaces so that pivoting of the inner cover relative to the outer cover 15 is adjusted as the latter moves. lid between the open positions

and closing the assembly 14.

  The outer cover 15 has a front wall portion 33 which is laterally elongate so that its length is substantially equal to the distance between the walls 19 and 20 of the housing 11, an upper wall 34 which is shallow and from the edge top of the front wall, this wall 34

  having a width smaller than that of the cutout 24 formed in the upper wall 17A so that it can bear on flat-shaped, offset extensions 17 belonging to the top wall 17A at the opposite ends of the cutout 24.

  Lugs 36 and 37 facing rearwardly from the opposite ends of the front and top walls 33 and 34 have inwardly facing journals 38 for pivotally mounting the outer cover 25 to the end walls 19 and 20. The outer cover 15, when mounted in an articulated manner on the housing 11, has, in its closed position, its wall 33 which covers the front face of the magnetic strip while the upper part 34 of the lid 30 is disposed over the magnetic tape section. The inner cover 16 has a length substantially equal to that of the cutout 24 and has an elongated head portion 40 whose dimensions are such that it covers the space between the longitudinal edge of the cutout 24 and the upper wall.

  34 of the outer cover 15, in the closed position of the latter. The inner lid 16 has an inclined skirt

  born 41 generally turned downwards and forwards from the head 40, over the entire length of the latter. The skirt 41 has dimensions such that, when the cover assembly 14 is in its closed position, the skirt 41 is turned downward behind the magnetic tape section, the lower edge 41A of the skirt 41 being substantially abutting against the lower edge of the front wall 33, below the strip section. Thus, the strip section 10 formed between the coils 12A and 12B is practically enclosed and protected in a space defined between the covers 15 and 16, in the closed position of the assembly 14, so that the dust is not at risk. to accumulate on the rear face of the strip section by the cutout 23, and no other harmful contact can be ensured with this rear face. Mounting tabs 42 and 43 are preferably secured to the upper lid wall 34 at laterally spaced locations, corresponding to the ends of the inner lid 16, and are formed with apertures 44 and 45 for pivotal housing. aligned lugs 46 and 47 extending from opposite ends of an intermediate portion 41B of the skirt 41. The lugs 42 and 43 are advantageously elastically in the lateral direction while the end surfaces of the axes 46 and 47 are inclined so that the pivot axes can be engaged in the respective holes 44 and 45 of the mounting lugs 42 and 43. After introduction

  pins 46 and 47 in the holes of the tabs 42 and 43, the inner cover 16 is mounted on the outer cover 15 and is pivotable relative thereto.

  The movements of the inner cover 16 with respect to the outer cover 15 are made subsequent to the pivoting of the outer cover 15 with respect to the housing 11, by means of the cam contact pins 48 and 49 placed at the opposite ends of the free edge 41A of FIG. the skirt 41. These pins 48 can slide in the guide or cam grooves 32 formed in the walls 27 and 28 end. The shape shown for each of the guide grooves 32 is chosen so that the lower edge 41A of the skirt 41 comes close to the lower edge of the front wall 33 only when the whole of the cover 14 is approximately in its position. of total closure, so that any contact 10 of the assembly forming the cover with the section

  magnetic tape is avoided when moving the cover between the open and closed positions.

  The tape cassette 10 further includes a spiral spring 57 associated with the hinge pin 15 so that the lid assembly 14 is always

  pushed back towards its closed position.

  The tape cassette 10 further includes a locking member 64 mounted near the end wall 19 of the housing 11. This member 64 has a cooperative position in which it locks the cover 14 in its closed position and a release or separation position allowing the movement of the entire lid towards its open position. The spiral spring 57 is thus intended to push the assembly 14 towards its closed position, but it also acts on the locking element 64 when the housing parts 11A and 11B are mounted on one another so that the set 64 be pushed back

towards his position of cooperation.

  The cassette 10 further comprises a coil brake which acts as a coil lock and which comprises a brake body 101 and a brake guide structure 102 placed in the housing 11 at a location between the coils 12A and 12B, 35 near the side of the housing which is opposite the opening 22. The structure 102 of guiding the brake has the role of guiding the body 101 in the front-back direction, that is to say parallel to the plane separating the housing portions 11A and 11B. Two braking pawls 105 and 106 which are resilient and in the form of lamella-like extensions, protrude from the body 101 to the coils 12A and 12B respectively, and cooperate with the two peripheries 103A and 103B of the lower cheeks 104A and 104B, several 103C being formed along the periphery, at regular intervals determined, for the application of the pawl. Each ratchet application surface 103C is in the form of a substantially rectangular or square cutout intended to house the free end of the associated ratchet 105 or 106 so that a locking of

the reel is insured.

  The detailed construction of the embodiment

  The preferred coil brake 100 according to the invention is now described with reference to FIGS. 2 to 4.

  In the embodiment shown, the brake body 101 has two braking pawls 105 and 106 which are elastically deformable, their free ends

  being oriented to cooperate with one of the lands 103C formed at the associated periphery 103A, 103B of the bottom cheek 104A, 104B of a reel.

  For this purpose, each of the pawls 105 and 106 protrudes forwardly of the front peripheral end of the body 101. The pawls 105 and 106 are resilient so that they can deform and they can elastically retain their initial positions. . In the initial positions, the free ends of the pawls 105 and 106 are spaced from each other and are at a greater distance than the distance between their connecting portions 109 and 110 of the brake body 101. Accordingly, the respective brake pawls are disposed obliquely outwardly with respect to the longitudinal axis of the body 101 and form

  a substantially V-shaped configuration. Each pawl 105, 106 has a surface facing the ratchet corresponding to

  which is called in the following "internal surface".

  The surface of the pawls 105, 106 on the other side is called the "outer surface". Essentially vertical grooves 107 and 108 are formed on the inner faces of pawls 105 and 106. In addition, these pawls 105

  and 106 have a reduced thickness at the sections 109 and 110 to which they are connected to the body 101.

  The grooves 107 and 108 and the connecting sections 109 and 110 having a reduced thickness cooperate to give the pawls 105 and 106 excellent contact holding properties with the staves.

103C, with braking.

  The body 101 of the brake and the ratchets 105 and 106- described above constitute a brake 111. The brake 111 is placed on a longitudinal path 112

  delimited by guide walls 113 and 114 projecting forwardly from the rear face 21.

  The elastic member 115 which is in the form of a helical spring in the illustrated embodiment, is also placed on the longitudinal path 112. The rear end of the elastic member 115 in the form of a helical spring is bearing against the inner periphery of the rear wall 21 and its front end is housed in a cutout 116 formed in the rear face 25 of the brake body. As shown, protrusions 117

  retainers protrude from the side walls 118 delimiting the rear cutout 116 and are intended to cooperate with the front end of the elastic member 115 in the form of a spring so that the elastic member 30 and the body remain in cooperation.

  Front ends 119 and 120 of the guide walls 113 and 114 are folded towards each other so that they form a limited opening path 121, through which the braking pawls 105 and 106 project 35 forward. . These front ends folded 11-9 and play the role, in cooperation, of a stop member for retaining the brake 111 in the longitudinal path. For this purpose, the distance between the nearest ends of the folded front portions 119 and 120 is less than the lateral width of the body. On the other hand, the front ends 119 and 120 which are inwardly folded are also intended to limit the outward deformation of the pawls 105 and 106, especially when a rotational torque and / or a lateral force are applied to the coil

in the coil lock state.

  An abutment protrusion 122 protrudes from the wall

  lower 17B of the lower part 11B of the housing.

  This abutment protrusion 122 has a laterally elongate shape and is placed in an intermediate position between the opposite ends of the folded front portions 119 and 120. The lateral ends of the abutment protrusions are rounded and cooperate with the inner surfaces of the pawls 105 and 106. braking. As a result, the projection 122 limits the deformation of the ratchets

towards the inside.

  As shown in Figure 1, a slot 123 is formed in the bottom wall 17B. A member mounted on a recording and / or reading apparatus for moving the brake 111 rearward, despite the force of the spring, is introduced into the slot 123 to eliminate the blockage due to the cooperation.

  braking pawls 105 and 106 and bearing surfaces 103C. The brake release member may have a function and a construction known elsewhere.

  When the illustrated tape cassette is not used, the braking assembly 112 is moved forward by the spring member 115 so that the pawls 105 and 106 advance beyond the path 121 and cooperate with each other. 103C and 103B surfaces of the lower flange cheeks 103A and 104B, as shown in FIG. 4. Under these conditions, when a torque applied to the spool 12A is converted into a torque

* 2601805

  of rotation transmitted by the lower cheek 104A as indicated by the arrow R in Figure 5, the pawl 105 deforms outwardly and continues to cooperate with the range 103C. Deformation to the outside of the pawl 105 is limited by the folded forward end 119 of the guide wall 113. As a result, the coil 12A can not rotate more significantly. On the other hand, when the coil 12A is laterally displaced to the other coil 12B as shown by the arrow L in FIG.

  ratchet 105 braking deforms inwardly.

  However, this inward deformation of the pawl 105 is limited by the stop protrusion 122. As a result, the pawl 105 is held in the locking position in which it locks the seat 103C. In both cases of FIGS. 5 and 6, as the braking pawls 105 and 106 have sufficient flexibility to deform inwardly and outwardly and absorb backward force, this force can not cause a rearward movement of the brake despite the antagonistic force of the elastic member 105, and the cooperation of the elements

  blocking can not be deleted.

  As a result, as indicated in the description

  In the foregoing, this advantageous embodiment of the invention ensures the conservation of the cooperation of the braking pawls and the spans of the lower cheeks.

reels, at any time.

  Figures 7 and 8 show variants

  of the previous embodiment of coil brake according to the invention. In the variant of FIG. 7, the folded forward ends 130 and 131 of the guide walls 113 and 114 are fork-shaped and thus form two contact points 132, 133 and 134, 135.

  In this construction, the limitation of the outward deformation of the pawls 105 and 106 is better ensured. On the other hand, in the variant of FIG. 8, the abutment projections 136 and 137 are formed separately from the guide walls 113 and 114 so that they limit the outward deformation of the pawls 105 and 106. In this case, the folded ends 138 and 139 of the guide walls 113 and 114 essentially act as a retaining device.

  brake 111 in the longitudinal path 112.

  The same effect of restraining the cooperation of the braking pawls and the lower cheeks of the reels can be obtained with these variants.

  Of course, various modifications can

  The devices described above may be provided by those skilled in the art only as non-limiting examples without departing from the scope of the invention.

26'0 1805

Claims (16)

  1. Brake for a reel of a magnetic tape cassette, having a reel having a cheek, the reel being placed in a cassette case, said brake being characterized in that it comprises a cutout (103C) formed at the outer periphery the cheek of the spool, a braking assembly (111) having a body (101) and a ratchet (105, 106) of lamellar braking, the braking assembly being movable between a locking position in which the ratchet is in cooperation with the cut and limits the rotation of the spool, and a release position in which the pawl is placed at a distance from the cut and allows rotation of the spool, and a device (107, 108) associated with the spool. braking assembly and cooperating with the brake pawl so that it absorbs a force applied to the braking assembly through the ratchet which is in contact with the cut-out, the force tending to push back the ratchet in positio n unlocking, the braking assembly can thus be maintained in the blocking position.   A brake according to claim 1, characterized in that the force absorbing device (107, 108) provides flexibility to the brake pawl (105, 106) so that it can deform elastically under the action   of force and so absorbs it.   3. Brake according to claim 2, characterized in that the force absorbing device (107, 108) allows an elastic deformation of the ratchet   (105,106) in a predetermined part.   4. Brake according to claim 3, characterized   in that it further comprises a device (119,120,122) 35 for limiting the amplitude of the elastic deformation of the brake pawl.   5. Brake according to claim 4, characterized in that the device (119, 120, 122) intended to limit the deformation comprises a stop member oriented   near the predetermined part.   Brake according to claim 5, characterized in that the stop member comprises a first element (119, 120) limiting the lateral deformation of the pawl in a first direction and a second element (122) limiting the lateral deformation of the pawl in a second sense, opposite to the first.   7. Brake according to claim 6, characterized in that it further comprises a device for defining a longitudinal path (112) for guiding the braking assembly, the latter moving on this path between the locking positions and for unlocking, the device for delimiting the guide path comprising guide walls (113, 114)   formed along the guide path.   8. Brake according to claim 7, characterized in that the guide walls (113,114) comprise a portion (138,139) acting as a retaining member of the braking assembly on the guide path. 9. Brake according to claim 8, characterized in that the retaining portion (119, 120) of the guide walls plays the role of the first element of the organ. stop.   Brake according to claim 2, characterized   in that the force absorbing device comprises a thin part (107, 108) formed in the braking pawl.   11. Brake according to claim 10, characterized in that the thin portion (107,108) is formed in an intermediate longitudinal portion of the ratchet braking.   12. Brake according to claim 10, characterized in that the thin part (109, 110) is formed at the connecting end of the brake pawl (105,106) on the body (101).   13. Brake according to claim 11, characterized in that the thin portion (109, 110) is also formed at a connecting end of the brake pawl to the body. 14. Brake according to claim 13, characterized in that it further comprises a device (130, 131) intended to limit the amplitude of the deformation.   elastic brake pawl (105,106).   15. Brake according to claim 14, characterized in that the device (119, 120, 122) intended to limit the deformation comprises an abutment member.   oriented near the predetermined portion.   Brake according to claim 15, characterized in that the abutment member comprises a first element (119, 120) limiting the lateral deformation of the pawl in a first direction and a second element (122) limiting the lateral deformation of the pawl in a second sense opposite to the first.