GB2137591A - Indexing means for tape cassette - Google Patents

Abstract

The cassette has a springloaded indexing mechanism (31,33,38, Fig. 1) to urge the cassette reels (see teeth 23) in a tape winding direction so as to tension the free run of tape between the reels whenever the cassette is removed from the tape transport machine. Alternatively, a plate (33a, Fig. 3) forming two gear racks may be used. <IMAGE>

Description

SPECIFICATION Indexing means for tape cassette Background of the invention This invention relates to tape cassettes, and particularly to means for maintaining tape tension when the cassette is removed from a tape transport machine.

Tape cassettes usually contain two reels with tape coiled thereon so as to present a free run of tape between the reels, this run being accessible along one side of the cassette that is either open or has a cover door that can be opened when the cassette is inserted into a tape transport machine (e.g., a magnetic tape recording, playing and rewinding machine). Usually also, the sides of the cassette adjacent and orthogonal to the open side have smaller openings for the lateral insertion of a capstan, play-record and erasing heads, and various guides, all of which are part of the transport machine but must engage the tape on the side thereof that faces toward the interior of the cassette.If the free run of tape is too loose, it may drop too far back into the cassette so that the capstan and other such elements fail to pass behind the free tape run and the machine cannot function to transport and record or play the tape; conversely, if the loose run of tape falls too far out of the cassette while it is being loaded, the tape may become tangled in the transport interior mechanism and other malfunctions will result. Also, if the reels are loose when the cassette is being shipped or handled outside the transport machine, then vibrations or other sudden jolts may cause the tape coils to unwind somewhat and sag into conical shapes, resulting in immediate or eventual tape edge damage and later guding malfunctions in the transport machine.

Previously in the art it has been attempted to control this problem by arranging springloaded friction brakes or pawl-and-pinion combinations within the cassette to lock or restrain the reels in the positions that they occupy at the moment the cassette is withdrawn from the transport machine; and portions of the transport mechanism are arranged to engage the pawls directly or indirectly as the cassette is loaded into the transport to cause the pawls to retract and free the reels while the cassette remains in the machine-loaded condition.

Such an arrangement is shown in U.S. Patent 3,900,172, in which the cassette cover door is opened automatically by mechanism within the transport as the cassette is loaded, and the door in turn retracts the pawls that engage pinion gear teeth on the cassette reels.

Such arrangements are limited, however, to per petuating the tape tension or tape slack conditions that exist at the moment when the cassette is removed from the machine, and the run of tape at the open side of the cassette may still be too loose for proper funcitoning at the time of the next subsequent insertion. Nothing positive is done to ensure that the tape is actually placed under tension if it is not already in tensioned condition.

Brief description of the invention The present invention provides, in a preferred form. a cassette having a springloaded indexing mechanism to urge the reels in a tape winding direction so as to positively tension the free run of tape between the reels whenever the cassette is removed frow the transport machine.

Description of the drawings Figure 1 is an open-side elevation view of a tape cassette showing the free run of tape between the reels; Figure 2 is a plan view of the cassette of Figure 1 with the top cover removed and taken partly in cross-section along the plane 2-2 of Figure 1; and Figure 3 is a fragmentary view showing a variational form of the mechanism illustrated in Figure 2.

Description of the preferred embodiments Figures 1 and 2 show a generally rectangular cassette 11 having a top 12, bottom 13, end walls 14 and 15,a backwall 16, and an open front side 17 at which a free tape run 18 is presented as by means of guides 19. The tape is coiled in opposite directions on a pair of reels 21,22, the hubs and flanges of which are shown only in phantom in Figure 2, but each reel has a lower concentric extension formed as a pinion gearwith gear teeth 23 and a central arbor hole 24 for impalement on respective mounting arbors of the tape transport machine (not shown); these pinion extensions are shown in cross-section in Figure 2.

Whenever the cassette is not in the transport machine, the reels 21,22 are loosely positioned in the cassette by means of the extensions bearing pinion teeth 23, portions of the extensions extending downwardly through openings 26 in the bottom wall 13 of the cassette; each of the openings 25 is circumvallated by a raised rib 27, which is arranged to bear against and support the bottom flange of the respective reel. Each rib 27 has an opening 28forthe insertion of a tooth portion 31 of a rack assembly 32 comprising a carrier member 33 on which are pivoted two pawls 34 by means of pivot pins 36. The teeth 31 are actually formed on the pawls 34, and the pawls are springloaded as by springs 37 to be urged in the direction of engagement with the respective pinion teeth 23 of the reels.The rack carrier member 33 is mounted for sliding motion in a direction perpendicular to the plane joining and containing the two reel axes, and along a path that is midway between the reels, and is springloaded by a compression spring 38 to carry the pawls 34 into engagement with the pinion teeth 23 and to load each of the reels in a winding direction to positively tension the tape run 18.

Each of the pawls 34 has an arm 41 extending to a position at which openings 42 are provided in the bottom wall 13 of the cassette for access by a pair of key elements 43 from the transport mechanism, and for movement of the keys 43 in a downward direction (i.e., toward the bottom of the drawing paper) to cause retraction of the pawl teeth 31 from the pinion teeth 23 in a radial direction that has at least a directional component parallel to the plane of the reel axes. Compounded with this motion, the rack carrier member 33 is caused to move upwardly (i.e., toward the top of the drawing) by means of a pivoting key pin 44 extending from the transport mechanism and riding in an opening 46 in the cassette bottom 13.The carrier member 33 also has a central opening 47 by which the member rides in sliding motion on a pair of track bolts, which also serve to retain a retaining plate 48 that partly overlies and guides the member 33 in its sliding motion, and serves also to assist in retaining one end of the spring 38.

For some purposes, the rack and pinion combination may be arranged in simpler form, as shown for example in Figure 3, in which a rack plate 33a is arranged for the same springloaded and pin retractable rectilinear motion as the member 33 of Figure 2; and the plate 33a has one more guide 51 extending from the cassette bottom wall and riding in a slot 52 in the plate 33a. A pair of rectilinear arrays of rack gear teeth 46 are formed on the sides of the plate 33a to engage the pinion teeth 23 and load the reels in the tape winding direction. The advantage of the arrangement of Figure 3 is the simpler structure, without need for the pawls 34 or the transport keys 43. However, the arrangement of Figure 3 does require a much longer path of motion for the plate 33a to ensure both adequate loading of the reels and tensioning of the tape in one direction,togetherwith adequate retraction to completely clear the teeth 23 in the other direction; and if the reels fit too loosely in the cassette, there may be risk that the teeth of plate 33a may slip out of engagement with the pinion teeth 23. For most purposes therefore the arrangement of Figure 2 is preferred.

Claims (14)

1. A tape cassette of the type having a housing containing at least one tape reel, wherein: means are provided for securing an extending portion of said tape and for engaging and loading said reel in the tape-winding direction for tensioning said tape portion; said means being accessible from outside said housing for releasing said securing and loading means so as to free said reel and tape for operation.

2. A cassette as recited in Claim 1, wherein said means for securing said tangentially extending portion of said tape comprises another reel to which said tape is secured, and means also accessible from outside said housing for preventing rotation of said other reel in a tape-unwinding direction.

3. A cassette as recited in Claim 2, wherein said means for preventing unwinding rotation of said other reel comprises means for loading said other reel in a tape winding direction.

4. A cassette as recited in Claim 3, wherein said loading means includes rack means engaging pinion portions of both reels and mounted for tangential movement with respect to said pinion portions so as to urge both pinion portions in the respective tape-winding directions thereof.

5. A cassette as recited in Claim 4, wherein said tangentially moving rack means is arranged to move in a direction that is perpendicular to a plane containing the axes of both reels.

6. A cassette as recited in Claim 5, wherein the portions of said tangentially moving means that engage said pinion portions of said reels move only in a zone that is remote from said plane of the reel axes, said reel-engaging portions beng adapted to move also in directions that are parallel to said plane.

7. A cassette as recited in Claim 6, wherein said reels rotate in opposite directions for winding, and said tangentially moving rack means includes a carrier member mounted for track guided sliding movement perpendicular to said axial plane and midway between said reel axes, said carrier member being springloaded to normally urge said reels in winding direction, and said reel-engaging portions are pawls mounted for pivoting motion on said carrier member and springloaded with respect there- to in directions to engage said respective pinion portions of said reels and to assist in urging said reels in the winding direction; said housing being provided with a first opening for access to retract said carrier member against the spring loading thereof; and said housing also being provided with a pair of second openings for access to retract said pawls against the springloadings thereof.

8. A cassette as recited in Claim 7, wherein said pinion reel portions are provided with gear teeth, and said pawls are shaped to engage said gear teeth to cause simultaneious indexing movement of both reels in the winding direction so as to tension said tape between the reels.

9. An indexing mechanismfortensioning a free run of tape between the reels of a tape cassette, wherein: said mechanism is formed as a rack; each of said reels has a pinion portion engaged by said rack and urged thereby in the tape-winding direction; and said mechanism is accessible from outside said cassette for retraction of said rack to free said reels for the normal transport of said tape.

10. An indexing mechanism as recited in Claim 9, wherein said rack is mounted in said cassette for translation along a path that is midway between the reels and is perpendicular to the plane joining and containing the axes of the reels.

11. An indexing mechanism as recited in Claim 10, wherein each of said reel pinion portions is formed with gear teeth; and said rack is an assembly comprising a carrier member mounted for translational motion along said path, and a pair of pawls each mounted for pivoting motion on said carrier member so as to engage the gear teeth of a different reel pinion portion and index the respective reel in the winding direction when said carrier member moves in a first direction on said path.

12. An indexing mechanism as recited in Claim 11, wherein said carrier member is springloaded in said first direction thereof, and said pawls are each springloaded for engagement with the pinion portions of the respective reels.

13. An indexing mechanism as recited in Claim 11, wherein said cassette is provided with a first access opening for the insertion of a key to engage and retract said carrier member in a second direction opposite to said first direction, and a pair of second access openings for the insertion of keys to engage and retract said pawls in pivoting motion away from said respective reel pinion portions.

14. An indexing mechanism as recited in Claim 10, wherein the portions of said rack that engage said pinion portions of said reels are formed with rectilinear arrays of first gear teeth, and said pinion portions are formed with circular arrays of second gear teeth mating with said first gear teeth.