Reuseable write enable/disable indicator for a video tape cassette

Abstract: A write enable tab (12) is repeatedly movable from a first position, enabling writing on a signal storage unit, to a second position, disabling writing thereon. The write enable tab preferably includes a central body (42) and a flexible member (46) which exert force against first and second walls of a tape cassette shell. The flexible member is attached at a first end to the central body. A second end (52) of the flexible member projects into first and second depressions in the first wall when the central body is in the first and second positions, respectively.

Description: The present invention relates to write enable device on a tape cassette according to the preamble of claim 1. Such a device is known from the teachings of the US-A-4,607,299. It discloses a movable tab having a wall which abuts an inner wall of the cassette, however, fails to disclose a movable tab which is flush with the exterior wall of the tape cassette when in one of the positions. Also, there is no cooperative structural engagement between the walls. As a result, manufacturing tolerances, age, heat, wear, over, use, etc., all would put in question the ability of the known tab to reliably remain in the respective positions shown in FIGS. 2 and 4 of this reference. During shipment, handling, etc., it might be possible that the known tab would move to an undesirable position, perhaps allowing writing to occur inadvertently. Further, GB-A-1 501 075 = US-A-4,041,537 is directed to an audio tape cassette and more particularly to a slide tab which is located in the direct corner of the audio tape cassette - not on the flat rear surface of the tape cassette. Because of this, there is a substantial opening for collection of debris and the like when the slide tab of the GB-Reference is in its upward position as shown in its FIG. 4. Moreover, as shown in its FIG. 3, even in its downward position the slide tab still is not substantially flush with the side surface of the tape cassette. Even more importantly, the known slide tab as best shown in its FIGS. 1 and 2, must be sandwiched between the cover and base shell halves during assembly and in the final assembled tape cassette product. The known slide tab is therefore not fully retained in one of two retainer subhousings, the first being completely formed in the base cover shell and the other completely formed in the cover shell half. Thus, the assembly of the known tape cassette is significantly complicated and costly because of the requirement of having to sandwich the slide tab during assembly of the cassette. Finally, and perhaps most importantly from a consumer user friendly standpoint, said British Reference teaches that it is required to insert a sharp object in the openings in order to move the slide tab between its two positions. In addition to one hand of the consumer having to hold a sharp object to insert into either the opening, the consumer must use its other hand to actually move the slide tab in the opening at the corner of the tape cassette. Thus, the consumer must use two hands in a very awkward operation to move the slide tab of the reference between its first an second enable and disable positions. U.S. Patent No. 4,536,812 shows a read/write tab for a floppy disk. The tab merely rests on a planar floppy disc jacket base at a corner thereof. There are no first and second retaining subhousings. Prior to ultrasonically welding the jacket cover to the base, but after inserting the floppy disc and temporarily positioning the cover, the disc is quality tested. If the disc is not up to particular quality standards, the cover must be removed from the base and the disc is discarded. Often, at this stage of production, the tab falls out during handling. When a new disc is placed in the jacket, the write/protect tab must be reinserted in the tab pocket before the cover can be replaced on the base and the testing repeated. Of course, this type of assembly is time and cost inefficient. The tab of this patent, therefore, is not fully retained in one of the subhousings, as is also true of the British reference. SUMMARY OF THE INVENTION An object of the present invention is to provide a write enable tab which is reuseable. Another object of the present invention is to provide a reuseable write enable tab for a video cassette without any changes in conventional design and performance specifications. Yet another object of the present invention is to provide a write enable tab which remains attached to a tape cassette shell when moved to a write disabled position. A further object of the present invention is to provide a write enable tab which is easily moved between two positions, one of which enables writing of a signal onto a tape cassette and the other of which disables writing on the tape cassette. The above-mentioned objects are attained by providing a write enable device as characterized in claim 1. In one embodiment of the present invention, the write enable indicator is used on a tape cassette comprising a shell substantially surrounding a signal storage element. Retaining means are preferably formed as an integral part of the shell of the tape cassette. The movable means preferably includes sliding means with a central body, extensions and internal and external surfaces and movement retarding means formed by a flexible member attached at a first end to the internal surface of the sliding means. The retaining means preferably includes first and second walls having respective first and second surfaces facing each other to form a cavity therebetween. The first surface of the first wall preferably includes two depressions separated along a first axis. The sliding means moves along the first axis from the first position to the second position in response to the external force. The flexible member preferably includes a second end projecting into the first and second depressions when the sliding means is in the first and second positions, respectively. These objects, together with other objects and advantages which will be subsequently apparent, reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof wherein like reference numerals refer to like parts throughout. BRIEF DESCRIPTIONS OF THE DRAWINGS Fig. 1 is a perspective view of an external corner of a videotape cassette including a write enable tab according to the present invention; Fig. 2 is a front view of the write enable indicator according to the present invention; Figs. 3A-3D are cross sectional views taken along line 3-3 in Fig. 2, illustrating a write enable tab according to the present invention in write enable and write disable positions and two intermediate positions therebetween; Fig. 4 is an exploded perspective view of a write enable indicator according to the present invention; Fig. 5 is a rear view of a tab used in a write enable indicator according to the present invention; Fig. 6 is a side view of a tab used in a write enable indicator according to the present invention; and Fig. 7 is a perspective view of a tab used in a write enable indicator according to the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention is most easily applied to a videotape cassette, such as a VHS standard tape cassette which is conventionally manufactured with a single write enable tab covering a majority of a rectangular opening in the shell of the tape cassette. A VHS videotape cassette has a relatively large write enable tab compared to other commonly used signal storage units such as audio tape cassettes and floppy diskettes and has been used for illustration in the drawings. In the case of the VHS videotape cassette, a write enable indicator is positioned as illustrated in Fig. 1. The tape cassette shell 10 substantially surrounds two spools holding magnetic tape (not shown) which acts as a signal storage element. According to the present invention, a write enable tab 12 is formed of a single piece of moldable material, preferably acetal for lubricity, and preferably having a colour such as red contrasting with the dark colour of the video cassette shell 10. Initially, the write enable tab 12 is positioned as illustrated in Figs. 1, 2 and 3A. The write enable tab 12 provides movable means for enabling the recording of a signal on the signal storage element (magnetic tape) in the signal storage unit (cassette) when the movable means is in the first position illustrated in Figs. 1, 2 and 3A. The position of the write enable tab 12 may be detected in any conventional manner, including exerting an external force against the tab 12 using a sensor element which will not significantly move the tab 12, due to the relatively small force, e.g., no more than 100 grams, which is typically applied. The rear surface 14 of the tape cassette 10 has two walls, an internal wall 16 and an external wall 18, integrally formed as part of the cassette shell 10. A narrow cavity 20 is formed between a first surface 22 of the internal wall 16 and a second surface 24 of the external wall 18. The walls 16 and 18 form retaining means for retaining the write enable tab 12 in the first and second positions and for permitting the write enable tab to repeatedly move between the first and second positions. The internal wall 16 is formed sufficiently close to the external wall 18 so that the internal wall 16 does not intrude on the space allocated for the tape and spools. The write enable tab 12 is moved from the first position, illustrated in Fig. 3A to the second position illustrated in Fig. 3D by exerting an external force on the external surface 26 of the write enable tab 12. The external force is exerted inwards and upwards on the write enable tab 12 so that the write enable tab 12 leaves the plane of the external wall 18 and moves to the position illustrated in Fig. 3B. As the force continues to be exerted, the write enable tab 12 moves to the position illustrated in Fig. 3C and continues moving until it stops in the second position illustrated in Fig. 3D. As illustrated in Fig. 4, the cassette shell 10 is formed from two halves 28 and 30, preferably injected molded plastic. The lower half or base 28 includes a first depression or opening 32 in the first or inner wall 16 and a large opening 34 defined by edges 36 of the second or outer wall 18. The lower half 28 also includes part of a second depression or opening 38 and E-ribs 39 which are formed as part of the inner wall 16 to force the tab outwards until it is flush with the outer wall 18 when it fills the opening 34. The opening 38 is further defined by the upper half or cover 30 which also includes a slot 40 in the first wall 16 and stops 41 on the top of the cover 30. As illustrated in Figs. 5-7, the write enable tab 12 includes a central body 42 and extensions 44 which are pressed against the second surface 24 (Figs. 3A and 3B) of the second wall 18 by a flexible member 46. The flexible member 46 has a first end 48 attached to the internal surface 50 of the central body 42 and a second end 52 which exerts an internal force against the first surface 22 (Fig. 4) of the first wall 16. As illustrated in Figs. 3B and 3C, the flexible member 46 is flexed as the write enable tab 12 is moved from the first position in Fig. 3A to the second position Fig. 3D. In the first and second positions, the flexible member 46 projects the second end 52 into the first and second depressions 32 and 38, respectively, thereby holding the write enable tab 12 in place. When used in a conventional VHS video cassette, the flexible member 46 withstands the force exerted by the sensor element in the first position (illustrated in Fig. 3A) to enable writing on the video cassette. The write enable tab 12 also includes a projection 54 which extends into the slot 40. The corners of the projection 54 may be rounded as illustrated at the top of Fig. 5 or squared as illustrated in the center of Fig. 5. The projection 54 and slot 40 form first and second alignment means which direct the write enable tab 12 to move along a first axis between the first and second positions. As described above, the flexible member 48 exerts the internal force along a second axis which intersects the first axis. As best seen in Fig. 4, the external surface 26 of the write enable tab 12 includes a notch 58 or a pinhole 59, or both, which provide engagement means for a stiff object, such as a fingernail in the notch 58 or a ballpoint pen in the pinhole 59, to exert a downward or upward force on the write enable tab 12. The stops 41 (Fig. 4) are included to ensure that the notch 58 or pinhole 59 is exposed when the majority of the write enable tab 12 has been moved to the position illustrated in Fig. 3D, out of the opening 34 and offset from the plane of the external wall 18. This arrangement allows the write enable tab 12 to be easily moved from the second position illustrated in Fig. 3D to the first position illustrated in Fig. 3A to again enable writing of a signal onto the signal storage element, i.e., on magnetic tape in the tape cassette 10. The notch 58 and pinhole 59 are preferable to a positive projection extending from the external surface 26 of the tab 12, because they reduce the chance of accidental movement by the cassette user. The above write enable/disable indicator is particularly suitable for video tape cassettes because it is readily adaptable to existing video tape cassette specifications, easy to manufacture of a moldable material and easy to assemble into the video tape cassette cover and base shell halves for mass production. The many features and advantages of the present invention are apparent from the detailed specification, and thus it is intended by the appended claims to cover all such features and advantages of the system which fall within the true spirit and scope of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, from the disclosure of this invention, it is not desired to limit the invention to the exact construction and operation illustrated and described. For example, it may be possible to "retrofit" existing VCR casettes by manufacturing inserts which fit into the space left by a broken conventional tab and which include a write enable tab and tracks to hold the tab in place at all four (4) positions illustrated in Figs. 3A-3D. The present invention could also be applied to write enable tabs used on audio cassettes. In addition, commonly used floppy diskettes, e.g., 5 1/4 inch diskettes, have a write enable notch which is covered by tape when it is desired to prevent writing on the diskette. If a write enable indicator according to the present invention was used in this application, the tab would be moved to cover the opening to disable writing, instead of being moved out of the opening to disable writing. Accordingly, suitable modifications and equivalents may be resorted to, all falling within the scope and spirit of the invention.

Claims: A write enable device on a tape cassette (10) to allow and prohibit recording on the tape, the cassette (10) having a tape cassette housing with a first shell portion (30) and a second shell portion (28), the tape cassette housing forming an elongated front surface through which the tape contained by the tape cassette housing is accessed, an elongated rear surface (14) opposite the front surface, side surfaces, and top and bottom surfaces, (a) movable sliding means (12) accommodated within the cassette (10) for enabling recording of a signal on the tape when said movable means (12) is in a first position and for disabling the recording of a signal on the tape when said movable means (12) is in a second position; and (b) retaining means (16, 18, 32, 38) for retaining said movable means (12) in the first or second positions and for permitting said movable means (12) to repeatedly move between the first and second positions in response to an external force, wherein the movable means (12) and retaining means (16, 18, 32, 38) are located at the rear surface (14) of the cassette housing, the retaining means (16, 18, 32, 38) having a first cavity (20) portion defined by a first internal wall (16) of the second shell portion (28) and a second external wall (18) of the cassette (10), and a second cavity (20) portion defined by the first internal wall (16) of the first shell portion (30) and the second external wall (18), a single opening (34) existing within the second external wall (18) of one of the cavity (20) portions, and the movable means (12) being movable along an axis in the transverse direction at the tape cassette housing rear surface (14) between the first enabling position located in the first cavity (20) portion and the second disabling position located in the second cavity (20) portion, characterized by the movable means (12) including a flexible member (46) which pushes the movable means (12) in a direction away from the first interior wall (16) and into the opening (34), flush with the rear surface (14), when the movable means (12) is in the first position, and away from the first interior wall (16) and against the second exterior wall (18), when the movable means (12) is in the second position, wherein the first position is in a first plane and the second position is in a second, parallel plane. A write enable device as recited in claim 1, further characterized by the movable means (12) being substantially visible at the rear surface (14) when in the first enabling position in the first cavity (20) portion of the second shell portion (28), and being substantially invisible at the rear surface (14) when in the second disabling position in the second cavity (20) portion of the first shell portion (30). A write enable device as recited in claim 1, further characterized by: said flexible member (46) cooperating with said retaining means (16, 18, 32, 38) to prevent said movable means (12) from moving from the first and second positions except when the external force is applied. A write enable device as recited in claim 3, further characterized by said retaining means (16, 18, 32, 38) being formed as an integral part of the tape cassette housing and including said first interior wall (16) of the tape cassette housing having a first surface (22); and said second exterior wall (18) of the tape cassette housing formed substantially parallel to the first wall (16), having a second surface (24) facing the first surface (22) of the first interior wall (16) to form the cavity (20) therebetween, wherein said movable means (12) moves between the first and second positions by sliding between the first (22) and second (24) surfaces. A write enable device as recited in claim 4, further characterized by said flexible member (46) exerting an internal force along a second substantially perpendicular axis to produce a friction between said retaining means (16, 18, 32, 38) and said movable means (12), at least when said movable means (12) is in the first and second positions. A write enable device as recited in claim 5, further characterized by the first surface (22) of the first interior wall (16) including first and second depressions (32, 38) separated along the first axis, wherein said flexible member (46) has a first end attached to said movable means (12) and a second end (52) projecting into the first and second depressions (32, 38) when said movable means (12) is in the first and second positions, respectively. A write enable device as recited in claim 6, further characterized by said opening (34) being defined by edges (36) formed in said second external wall (18), wherein said first interior wall (16) includes first alignment means (40) for directing said movable means (12) along the first axis, and wherein said movable means (12) further includes - a central body (42) having an internal surface (50) to which is attached said flexible member (46) and having an external surface (26) exposed by the opening (34) in said second external wall (18); extensions (44) integral with said central body (42), extending beyond two of the edges (36) of said second external wall (18) on opposite sides of the central body (42) and contacting the second surface (24) of the second external wall (18); and second alignment means (54) for interacting with said first alignment means (40) to direct said movable means (12) along the first axis. A write enable device as recited in claim 7, further characterized by the external force being exerted by a stiff object, wherein said movable means (12) is further characterized by engagement means (58, 59) for engaging the stiff object to transmit the external force to said central body (42). A write enable device as recited in claim 8, further characterized by said movable means (12) substantially filling the opening (34) in said second external wall (18), when said movable means (12) is in the first position and a majority of said movable means (12), excluding the engagement means (58, 59), is removed from the opening (34) in said second external wall when the movable means (12) is in the second position. A write enable device as recited in claim 8, further characterized by said engagement means (58, 59) being a pinhole (59) in the external surface (26) of said central body (42). A write enable device as recited in claim 8, further characterized by said engagement means (58, 59) being a notch (58) in the external surface (26) of said central body (42). A write enable device as recited in any one of claims 1, 2, 7 further characterized by the single opening (34) being formed in the second shell portion (28) for applying the external force to the movable means (12) and thereby moving the movable means (12) between the first and second positions. A write enable device as recited in claim 9, further characterized by the tape cassette (18) being a video tape cassette. A write enable device as recited in claim 1, further characterized by the first cavity (20) portion being integrally formed as part of the second shell portion (28) and the second cavity (20) portion being integrally formed as a part of the first shell portion (30). A write enable device as recited in claim 1, further characterized by said flexible member (46) exerting an internal force along a second axis different from the first axis, and means formed on the retaining means (16, 18, 32, 38) along the first axis for cooperating with the flexible member (46) only in the first and second positions, wherein the means for cooperating includes two depressions (32, 38) separated along the first axis, and wherein said flexible member (46) cooperates with said depressions (32, 38) to prevent said movable means (12) from moving from the first and second positions except when the external force is applied. A write enable device as recited in claim 1, wherein said movable means (12) is constructed of acetal. A write enable device as recited in claim 1, wherein the tape cassette (10) housing has a first colour, and the movable means (12) has a second contrasting colour.

Inventors: GELARDI PAUL J, LOWRY ALAN B, ROCHELO DONALD R, GELARDI, PAUL J., LOWRY, ALAN B., ROCHELO, DONALD R.
Applicants: SHAPE INC, SHAPE INC.
Application year: 1987
Main classification: G11B23
IPC codes: G11B23