Recording cassette

Abstract: A tape cassette has one or more manually settable slider elements that are detected to prevent erroneous erasure of information recorded on the cassette. The or each slider (50) slides in a through hole (31) in the cassette case (2, 3) and includes stops (53 a , 53 b ) that limit the travel of the slider element (50) by co-operating with protrusions or shoulders that are formed by the respective half cases (2, 3) making up the cassette case. The slider element (50) also includes a click-stop protrusion (51) that co-operates with a protrusion (32) in the through hole (31) that is formed in only one of the two half-cases (2, 3). The slider element (50) further includes a through slot (55) that permits deformation of the slider element (50) as the click-stop protrusion (51) goes over the protrusion (32) in the through-hole (31), thereby requiring less force to move the element. The stops (53 a , 53 b ) can be formed by two spaced apart protrusions that also permit deformation of the slide element as the click-stop protrusion (51) travels past the protrusion (32) in the through-hole (31).

Description: The invention relates to a recording cassette. Most tape cassettes are provided with some means to protect recorded information from erroneous erasure. One such tape cassette is provided with an erase preventive lug as the erroneous erase preventive device, which erase preventive lug is broken and removed after information is recorded on the tape. The drawback in such previously proposed device is that because the broken erase preventive lug cannot be restored to the tape cassette, another member must be attached to the tape cassette in place of the erase preventive lug at the position that had previously been occupied by the erase preventive lug if it is desired to record new signals on the tape in the tape cassette. Japanese Patent Application Laid-open (Kokai) No. Hei 1-102788 discloses a tape cassette provided with an erase prevention slider capable of moving between an erase enable position and a write protect position and is provided with first and second protrusions protruding in opposite directions that deviate from the direction of sliding of the slider. The cassette case is provided with a slider receiving hole provided with first and second recesses in the edge thereof. The slider is held at a first position with its first protrusion received in the first recess of the case or at a second position with its second protrusion received in the second recess of the case to set the tape cassette in the erase enable state or the write protect state, respectively. Thus, the tape cassette can repeatedly be set to the erase enable state or the write protect state by shifting the slider alternatively in opposite directions, and the slider can securely be held in place by the engagement of the first recess and the first protrusion or by the engagement of the second recess and the second protrusion. In the case, however, when neither the first protrusion nor the second protrusion of the slider is received in the corresponding recess, that is, in a transitional position when both the first and second protrusions of the slider are on the inner surface of the slider receiving hole of the case, there is a high pressure acting on the slider. Because of this pressure, the slider is difficult to move and hence the slider must be pushed hard in order to shift it, which effort may possibly damage the slider and the case of the tape cassette. This also makes the tape cassette containing the erroneous erasure preventing device difficult to handle. According to the invention there is provided a recording cassette comprising a case having a through hole at a predetermined position extending through the thickness of the case and a slider inserted in the through hole and slidable therein between predetermined positions that can be detected to prevent erroneous erasure of signals already recorded on a recording medium contained in the case, the slider including: an elongate body having a plurality of side surfaces; a plurality of stopping surfaces protruding at predetermined positions on the body to engage respective first protrusions formed in the through hole of the case and define a range of sliding movement of the body in the through hole; a click-stop protrusion formed at a predetermined position on a side surface of the body so as to engage a second protrusion formed in the through hole of the case to hold the body at either a first position corresponding to a record protect state or a second position corresponding to a record enable state; and a through slot formed in the body between opposite side surfaces adjacent the side surface on which the click-stop protrusion is formed. Such a recording medium cassette provided with an erroneous erase prevention slider can be capable of being held in a stable manner at a desired position, thereby to ensure the prevention of erroneous erasing. Such a tape cassette with an erroneous erase prevention slider can be capable of being easily set at an erase enable position or at a write protect position with a positive click action, and can be readily and satisfactorily operated even if the upper and lower half cases of the cassette are not joined together exactly or even if the erroneous erase prevention slider and the hole receiving same have some dimensional errors. The slider can be provided with a slot extending between the opposite side surfaces thereof and adjacent to the side surfaces on which is formed the protrusion in order to make the slider more flexible. The invention is diagrammatically illustrated by way of example in the accompanying drawings, in which:- Figure 1(a), 1(b), 1(c), 1(d), and 1(e) are a front view, a top view, a side view, a front perspective view, and a side perspective view, respectively, of a first embodiment of a slider employed in a tape cassette according to the invention; Figures 2(a), 2(b), and 2(c) are partial sectional views of an erroneous erase prevention mechanism included in the tape cassette of Figures 1(a) to 1(e); Figure 3 is a perspective view of a tape cassette according to an embodiment of the invention; Figure 4 is a perspective view of the tape cassette of Figure 3 in juxtaposition to a rotary head drum; Figure 5 is a plan view of a lower half case of the tape cassette of Figure 3; Figure 6 is a plan view of the tape cassette of Figure 3 disposed in an operating position relative to the head drum; Figure 7 includes partial sectional views of a second embodiment of a slider of a tape cassette according to the invention; Figure 8 includes partial sectional views of a third embodiment of a slider of a tape cassette according to the invention; Figure 9 includes partial sectional views of a fourth embodiment of a slider of a tape cassette according to the invention; and Figure 10 includes partial sectional views of a fifth embodiment of a slider of a tape cassette according to the invention. The invention will be described by way of example with relation to miniature tape cassettes of which a first embodiment is shown in Figures 1 to 6. Specifically, referring to Figures 3 to 6, a tape cassette has a case 1 for holding a magnetic tape for recording signals, such as PCM signals. The case 1 is formed by joining together an upper half-case 2 and a lower half-case 3 with screws 4, and pivotally attaching a lid 6 to the front end to cover a front opening 5 of the case 1. The upper half-case 2 is provided with through holes 2 a and 2 b , and the lower half-case 3 is provided with through holes 3 a and 3 b to receive hub driving shafts. A first hub 7 is disposed coaxially with the through holes 2 a and 3 a , and a second hub 8 is disposed coaxially with the through holes 2 b and 3 b . A magnetic tape T is wound round the hubs 7 and 8 with one end thereof fastened to the first hub 7 and the other end thereof fastened to the second hub 8 so as to extend tautly between the hubs 7 and 8 and around pinch rollers 9 and 10, which also serve as guide rollers and which are supported for rotation at the opposite ends of a front side of the case 1. The magnetic tape T extends across the front opening 5. A braking mechanism 11 is provided within the case 1 to brake the hubs 7 and 8 while the tape cassette is not in use. Erroneous erase prevention mechanisms 12 and 13 are provided at the opposite corners of the back end of the case 1. A front reference positioning hole 14 and a back reference positioning hole 15 are formed along a centre line of the case 1, as shown in Figure 6. Reference positioning holes 16 and 17 are arranged near the opposite corners at the back of the case, a plurality of detection holes 18 and 19 are arranged along the back edge, and gripping recesses 20 and 21 are provided at opposite sides toward the back of the case 1. The lid 6 for covering the front opening 5 of the case 1 is provided with a longitudinal guide groove 22 along its front surface and also with notches 23 for use with a cassette changer. Signals can be recorded on or reproduced from the magnetic tape T contained in the case 1 by a rotary magnetic head 41 in a helical scanning mode. Referring to Figure 4, the rotary magnetic head 41 revolves about an axis inclined at a predetermined angle to the axis of rotation of a head drum 42. The head drum 42 is partially received in the front opening 5 after turning the lid 6 upward or downward to open the front opening 5, so that the magnetic tape T slides along a portion of the circumference of the head drum 42 and the rotary magnetic head 41 travels obliquely relative to the magnetic tape T to perform the helical scanning operation. A pair of tape guide members 24 and 25 are shown in Figure 5 inclined respectively in opposite directions and disposed respectively inside the guide rollers 9 and 10 in the opening 5 of the case. The tape guide members 24 and 25 are mounted for lateral movement and for swinging motion to ensure helical sliding contact of the magnetic tape T with the head drum 42. Therefore, when the head drum 42 is inserted in the front opening 5, as shown in Figure 6, the tape guide members 24 and 25 come into contact with the tape T wrapped around the circumference of the head drum 42 to hold the magnetic tape T on the head drum 42. As shown in Figure 4, wing guides 43 and 44 having respective rollers 43 a and 44 a are provided on the opposite sides of the head drum 42. When the head drum 42 is inserted in the front opening 5 of the case 1, the rollers 43 a and 44 a are inserted between the pinch roller 9 and the tape guide member 24 and between the pinch roller 10 and the tape guide member 25, respectively, to press the magnetic tape T against the tape guide members 24 and 25. The wing guides 43 and 44 are inserted in the front opening 5 through a space between a stay 26 and a tape retaining pin 28 disposed between the pinch roller 9 and the stay 26 and through a space between a stay 27 and tape retaining pin 29 disposed between the pinch roller 10 and the stay 27, respectively. The erroneous erase prevention mechanisms 12 and 13 provided in the case 1 of the tape cassette are shown in Figures 1(a) to 1(e) and 2(a) to 2(c). Because the erroneous erase prevention mechanisms 12 and 13 are identical in construction, only the mechanism 12 will be described. The erroneous erase preventive mechanism 12 is disposed near one corner at the back portion of the case 1 and has a slider element 50 slidably held in a through hole 31, as shown in Figures 2(a) to 2(c). The slider element 50 extends across the width of the through hole 31. The slider element 50 is formed of an elastic synthetic resin in a shape substantially resembling a quadrangular prism and has four side surfaces 52 a , 52 b , 52 c , and 52 d . A rounded click-stop protrusion 51 protrudes from the side surface 52 a , and protrusions 53 a and 53 b protrude from the surface 52 c so as to form a recess 54 therebetween. The slide element 50 has a slot 55 extending therethrough between the opposite side surfaces 52 b and 52 d . As shown in Figure 1(a), a neck portion 57 is formed by recessing the respective middle portions of the side surfaces 52 b and 52 d , in which the slot 55 opens, and between the upper and lower ends 56 a and 56 b . When the slider element 50 is inserted into the through hole 31, spaces are formed between the opposite surfaces of the neck portion 57 and the inner surfaces of the through hole 31. In a preferred embodiment, a top surface 56 ap and bottom surface 56 bp of the slider element 50 are respectively colour coded, for example, red and blue. Figures 2(a), 2(b), and 2(c) are partial sectional views showing a portion of the tape cassette around the through hole 31 with the slider element 50 inserted therein. Figure 2(a) is a sectional view from the side of the surface 52 a of the slider element 50, and Figures 2(b) and 2(c) are sectional views from the side of the surface 52 d of the slider element 50. When the slider element 50 having a shape substantially resembling a quadrangular prism is inserted in the through hole 31, the side surfaces of the upper and lower ends 56 a and 56 b of the slider element 50 are in light contact with the side surfaces of the through hole 31. As shown in Figures 2(b) and 2(c), a click-stop protrusion 32 is formed on a side surface of the through hole 31 corresponding to the side surface 42 a of the slider 50 on the lower half-case 3 to hold the slider 50 at either a lower position with the click-stop protrusion 51 in contact with the lower surface of the click-stop protrusion 32, as shown in Figure 2(b), or in an upper position with the click-stop protrusion 51 in contact with the upper surface of the click-stop protrusion 32, as shown in Figure 2(c). Steps 33 are formed contiguously with the click-stop protrusion 32 on the upper half case 2 to compensate for any mechanical deviation of the upper half-case 2 and the lower half-case 3 relative to each other. The protrusions 53 a and 53 b protruding from the side surface 52 c of the slider element 50 slide along a slide surface 34 formed on the lower half-case 3. Upward movement of the slider element 50 is limited by a limiting portion 35 of the upper half-case 2 and downward movement of the slider element 50 is limited by a limiting portion 36 of the lower half-case 3. In Figure 2(b) the slider element 50 is shown at its lowermost position, with the lower protrusion 53 b in contact with the limiting portion 36 and being held in place by the engagement of the click-stop protrusion 51 and the click-stop protrusion 32 in the through hole 31. In changing the status of the tape cassette between an erase enable state and a write protect state, the slider element 50 is pressed at the top surface 56 ap or the bottom surface 56 bp with a thin stylus, such as a mechanical pencil, to shift the slider element 50 between the uppermost position and the lowermost position. This causes the click-stop protrusion 51 to ride over the click-stop protrusion 32 to allow the slider 50 to be moved in the direction in which pressure is applied thereto. Because the slider element 50 is provided with the slot 55, the portion of the slider element 50 having the side surface 52 a provided with the click-stop protrusion 51 is able to flex toward the slot 55, so that the slider element 50 can be moved from the lowermost position, as shown in Figure 2(b), to the uppermost position, as shown in Figure 2(c), and vice versa . Thus, the slot 55 allows the portion of the slider having the side surface 52 a provided with the click-stop protrusion 51 to flex easily, so that the slider element 50 can be shifted with a click to either the uppermost position or the lowermost position, as desired, using only moderate pressure. Because the pressure acting between the click-stop protrusions 51 and 53 is not excessively high, the durability of the erroneous erase prevention mechanism 12 is improved, and the pressure required to shift the slider element 50 will vary only a little over its lifetime. The high yielding capability of the click-stop protrusion 51 owing to the elastic bending of the portion of the slider 50 having the side surface 52 a also compensates for any dimensional errors in the components and parts, including the click-stop protrusion 32, as well as any errors in joining together the upper half-case 2 and the lower half-case 3, so that the slider element 50 is able to function satisfactorily even if the plastics tape cassette is some dimensional errors. Because the click-stop protrusions 51 and 32 are rounded, the slider element 50 is bistable, that is to say it will never be suspended between the uppermost and lowermost positions but must be positively shifted to either the lowermost position, as shown in Figure 2(b), or to the uppermost position, as shown in Figure 2(c), so that the status of the tape cassette can positively be discriminated between the erase enable state and the write protect state. Since the click-stop protrusion 32 is formed in a rounded shape substantially in the middle portion of the through hole 31 on only the lower half-case 3, and the upper half-case 2 is joined to the lower half-case 3 in a plane above the click-stop protrusion 32, the click-stop protrusion 32 has a smooth surface even if the upper half-case 2 and the lower half-case 3 are dislocated relative to each other. This feature enables the click-stop protrusion 51 of the slider element 50 to ride smoothly over the click-stop protrusion 32. Since the slide surface 34 along which the protrusions 53 a and 53 b slide is formed only on the lower half-case 3, the slide surface 34 is a smooth, continuous surface even if the upper half-case 2 and the lower half-case 3 are dislocated relative to each other. This feature enables the slider element 50 to slide smoothly along the slide surface 34. Alternatively, the click-stop protrusion 32 and the slide surface 24 may be formed on the upper half-case 2 instead of on the lower half-case 3, with the same beneficial results. As described above in reference to Figure 1(a), the opposite side surfaces of the neck portion 57 of the slider element 50 are separated from the inner surfaces of the through hole 31. Accordingly, even if the upper half-case 2 and the lower half-case 3 are dislocated relatively laterally in a direction parallel to the side surface 52 a having the click-stop protrusion 51, steps formed at the junction of the upper half-case 2 and the lower half-case 3 are unable to come into contact with the side surfaces of the slider element 50 and, hence, the sliding movement of the slider element 50 is not obstructed by any such steps caused by the dislocation. As best understood from Figures 2(b) and 2(c), because the protrusions 53 a and 53 b are formed at the opposite ends of the side surface 52 c , and the click-stop protrusion 51 is formed at the middle of the side surface 52 a opposite the side surface 52 c , the slider element 50 is held stably at three points on the side surfaces of the through hole 31. The top surface 56 ap of the slider element 50 is colour coded red and the bottom surface 56 bp of the slider element 50 is colour coded blue, for example. If it is assumed that the erroneous erase prevention mechanism 12 shown in Figures 2(a) to 2(c) is for side A of the tape cassette, then side A is in the write protect state when the slider element 50 is at the lowermost position having the blue bottom surface 56 bp exposed on the surface of the lower half-case 2, as shown in Figure 2(c). Then, the erase enable and write protect status of side A and that of side B of the tape cassette can readily be discriminated at a glance simply by recognising the colour exposed in the surface of the tape cassette. In the embodiment of Figure 7, a slider element 60 is provided with two protrusions 61 a and 61 b respectively on opposite side surfaces thereof, with click-stop protrusions 62 a and 62 b respectively on the other opposite side surfaces thereof. A through slot 63 is formed between the side surfaces provided with the protrusions 61 a and 61 b . Two click-stop protrusions 65 a and 65 b are formed respectively on the opposite inner surfaces of a through hole 64 in the cassette case 1. The through hole 64 is provided with an upper shoulder 66 a and a lower shoulder 67 a to co-operate with the protrusion 61 a and an upper shoulder 66 b and a lower shoulder 65 b to co-operate with the protrusion 61 b . In the embodiment of Figure 8, which is similar to the embodiment shown in Figure 7, the opposite ends of the through hole 64 near the opposite outer surfaces of the case 1 are expanded to facilitate the actuation and operation of the slider element 60. Figure 9 shows an embodiment which is a modification of the erroneous erase prevention mechanism shown in Figure 8, in which the slider element 60 employs only one click-stop mechanism formed by protrusions 62 a and 65 a . Figure 10 shows an embodiment which is a further modification of the erroneous erase prevention mechanism shown in Figure 8, wherein the slider employed has omitted therefrom the click-stop protrusions 62 b and 65 b , the protrusion 61 b and the shoulders 66 b and 67 b . The positive click-stop action is provided only on one side by elements 62 a and 65 a , and the slider element is limited by protrusion 66 a abutting stops 61 a and 67 a at opposite ends of its travel, as in Figure 7. In all embodiments, the effect of the slider element is the same and the top and bottom surfaces of the slider 60 are coloured respectively in red and blue to facilitate discrimination of the status of the tape cassette between the write enable state and the write protect state. The slider elements 50 and 60 may be formed by two-colour moulding and the write enable state and the write protect state may be indicated respectively by red and blue, or vice versa. Alternatively, the write enable state and the write protect state may be indicated by any two contrasting colours other than red and blue. Because it is only necessary that the top surface 56 ap and the bottom surface 56 pb can be discriminated from each other, only one of the top surface 56 ap or the bottom surface 56 pb may be coloured, however, it is desirable that the colours of the top surface 56 ap and the bottom surface 56 pb are readily discernable as being different to the colour of the case 1.

Claims: A recording cassette comprising a case (1) having a through hole (31, 64) at a predetermined position extending through the thickness of the case (1), and a slider (50, 60) inserted in the through hole (31, 64) and slidable therein between predetermined positions that can be detected to prevent erroneous erasure of signals already recorded on a recording medium contained in the case (1), the slider (50, 60) including: an elongate body having a plurality of side surfaces (52 a - d ); a plurality of stopping surfaces (53 a , 53 b , 61 a , 61 b ) protruding at predetermined positions on the body to engage respective first protrusions (35, 36, 66 a , 66 b , 67 a , 67 b ) formed in the through hole (31, 64) of the case (1) and define a range of sliding movement of the body in the through hole; a click-stop protrusion (51, 62 a , 62 b ) formed at a predetermined position on a side surface of the body so as to engage a second protrusion (32, 65 a , 65 b ) formed in the through hole (31, 64) of the case (1) to hold the body at either a first position corresponding to a record protect state or a second position corresponding to a record enable state; and a through slot (55, 63) formed in the body between opposite side surfaces adjacent the side surface on which the click-stop protrusion (51, 62 a , 62 b ) is formed. A recording cassette according to claim 1, wherein the body has a shape substantially in the form of a quadrangular prism. A recording cassette according to claim 1, wherein the plurality of stopping surfaces (53 a , 53 b ) and the click-stop protrusion (51) are formed on opposite side surfaces of the elongate body. A recording cassette according to claim 1, wherein the plurality of stopping surfaces are formed by two protrusions (61 a , 61 b ) that protrude from the side surfaces of the elongate body adjacent to the side surface on which the click-stop protrusion (62 a , 62 b ) is formed, and the through slot (63) extends through the side surfaces on which the two protrusions (61 a , 61 b ) are formed. A recording cassette according to claim 1, wherein the stopping surfaces are formed by two protrusions (53 a , 53 b ) both formed on the same side surface (52 c ) of the body and are spaced apart from each other with respect to a direction of movement of the slider (50). A recording cassette according to claim 1, wherein the plurality of stopping surfaces comprise two protrusions (61 a , 61 b ) spaced apart from each other with respect to a direction perpendicular to a direction of movement of the slider (60) and formed respectively on opposite side surfaces of the body. A recording cassette according to claim 1, wherein the click-stop protrusion (51, 62 a , 62 b ) is formed substantially at a mid-position in the length of the elongate body. A recording cassette according to claim 1, wherein the click-stop protrusion (51, 62 a , 62 b ) is formed as a rounded protrusion. A recording cassette according to claim 1, wherein the second protrusion (31, 65 a , 65 b ) is formed at a middle position in the through hole (31, 64). A recording cassette according to claim 1, wherein the second protrusion (31, 65 a , 65 b ) is formed as a rounded protrusion. A recording cassette according to claim 1, wherein the case (1) is formed by joining together an upper half-case (2) and a lower half-case (3) and in which a slide surface (34), along which the plurality of stopping surfaces protruding on the elongate body can slide, is formed entirely in the upper half-case (2). A recording cassette according to claim 1, wherein the case (1) is formed by joining together an upper half-case (2) and a lower half-case (3) and in which a slide surface (34), along which the plurality of stopping surfaces protruding on the elongate body can slide, is formed entirely in the lower half-case (3). A recording cassette according to claim 1, wherein the case (1) is formed by joining together an upper half-case (2) and a lower half-case (3) and in which the second protrusion (32, 65 a , 65 b ) formed in the through hole (31, 64) that engages the click-stop protrusion (51, 62 a , 62 b ) is formed entirely on the upper half-case (2). A recording cassette according to claim 1, wherein the case (1) is formed by joining together an upper half-case (2) and a lower half-case (3) and in which the second protrusion (32, 65 a , 65 b ) formed in the through hole (31, 64) that engages the click-stop protrusion (51, 62 a , 62 b ) is formed entirely on the lower half-case (3). A recording cassette according to claim 1, wherein the elongate body is provided with a neck portion (57) formed by recesses on respective intermediate portions of the side surfaces adjacent the side surface on which the click-stop protrusion is formed, so that the surface of the neck portion (57) are separated from the inner walls of the through hole (31). A recording cassette according to claim 1, wherein one longitudinal end surface (56 ap ) of the elongate body is coloured in a first colour different to a colour of the case (1), and the other longitudinal end surface (56 bp ) of the elongate body is coloured in a second colour different to the colour of the said case (1) and from the first colour. A recording cassette according to claim 1, wherein the through hole (31, 64) extends from one flat side of the case (1) to the other, and the slider (50, 60) is disposed for sliding movement in the through hole (31, 64) between two end positions; the click-stop protrusion (51, 62 a , 62 b ) resides either at a first position on one side of the second protrusion or a second position on the other side of the second protrusion; and the slot (55, 63) is formed completely through the body between the opposite side surfaces. A recording cassette according to claim 17, wherein the plurality of stop surfaces are formed by two protrusions 53 a , 53 b ) and the click-stop protrusion (51) and two protrusions (53 a , 53 b ) are formed on opposite side surfaces of the elongate body, and the slot (55) extends through side surfaces of the elongate body adjacent the side surface on which the click-stop protrusion (51) is formed. A recording cassette according to claim 17, wherein the plurality of stop surfaces are formed by two protrusions (61 a , 61 b ) protruding from the side surfaces of the elongate body adjacent to the side surface on which the click-stop protrusion (62 a , 62 b ) is formed, and the slot (63) extends between the side surfaces on which the two protrusions (61 a , 61 b ) are formed. A recording cassette according to claim 17, further comprising a second click-stop protrusion (62 b ) formed on a side surface of the body opposite the first click-stop protrusion (62 a ), the plurality of stop surfaces (61 a , 61 b ) being arranged on at least one of the remaining side surfaces of the elongate body. A recording cassette according to claim 20, wherein the first (51, 62 a , 62 b ) and second (32, 65 a , 65 b ) click-stop protrusions are both substantially at a mid-position on the elongate body in the length thereof. A recording cassette according to claim 17, wherein the elongate body is provided with a neck portion (57) formed by recesses on respective intermediate portions of side surfaces adjacent the side surface on which the click-stop protrusion (51) is formed, so that the surfaces of the neck portion (57) are separated from the inner walls of the through hole (31).

Inventors: TANAKA MASATO, YANAKA KIYOTAKA, TANAKA, MASATO,, YANAKA, KIYOTAKA,, TANAKA, MASATO, C/O PATENTS DIVISION, YANAKA, KIYOTAKA, C/O PATENTS DIVISION
Applicants: SONY CORP, SONY CORPORATION
Application year: 1991
Main classification: G11B23
IPC codes: G11B23