Disc cartridge

Abstract: A disc cartridge (1) including a cartridge body (3) having apertures for exposing a part of a disc (2) accommodated in it to outside and a shutter (10) formed integrally of a slide portion (13) engaged with a groove (14) in a lateral side of the cartridge body (3) so as to be slidably supported by the cartridge body (3) and shutter portions (11, 12) to open or close the apertures (7, 8). The shutter (10) is mounted on the cartridge body (3) for sliding between a first position of closing the apertures (7, 8) and a position of opening the apertures (7, 8). The shutter (10) is formed with a tongue (13 a ) extended along said one lateral side of the cartridge body (3) so that the length of the slide portion (13, 13 a ) in the sliding direction is longer than the length of the shutter portion (11, 12) in the same direction. The shutter (10) is prevented from being tilted in the sliding direction to ensure stable sliding.

Description: The invention relates to a disc cartridge. Disc cartridges have been previously proposed each having accommodated therein a disc on which predetermined information signals are recordable or have been recorded, such as a magneto-optical disc or an optical disc. A shutter is provided to open and close an aperture by means of which at least a part of a signal recording area of the disc may be radially exposed to outside. One such previously proposed disc comprises a disc-shaped base plate and a recording layer formed on at least one major surface of the base plate. The central portion of the disc is formed as a clamp area which is to be retained by a disc driving unit of a disc recording and/or reproducing apparatus which can record and/or reproduce information signals on or from the disc. The portion of the disc lying around the clamp area is reserved as a signal recording area on or from which the information signals are recorded or read. Referring to Figure 1 of the accompanying drawings, there has hitherto been proposed a disc cartridge 101 comprising a cartridge body 103 and a shutter member 110 which is accommodated within the cartridge body 103 and the shutter member 110 with a view to preventing deposition of dust and dirt on a disc 102 or damage thereto due to contact especially with a user's fingers as well as to facilitate handling of the disc 102. The disc 102 accommodated within the cartridge body 103 may be rotated therein by disc rotating means. Referring to Figure 2, the major surface of the cartridge body 103 is formed with an aperture 107 by means of which at least a part of the signal recording area of the disc may be exposed to outside between its inner and outer peripheries. Information signals may be recorded on and/or reproduced from the signal recording surface by means of disc recording and/or reproducing apparatus, through the aperture 107. The disc cartridge is provided with the shutter member 110 which can close the aperture 107 during non-use of the disc cartridge, as shown in Figure 1, to protect the disc 101 by preventing intrusion of dust and dirt into the inside of the cartridge body 103. The shutter member 110 is provided with a shutter portion or plate portion 111 of a size large enough to close the aperture 107. The shutter portion 111 is formed with an opening 109 corresponding in size and shape to the aperture 107. The shutter member 110 is mounted by the cartridge body 103 for sliding along a lateral side of the cartridge body 103 by having an end face 113 supported by a corresponding lateral side of the cartridge body 103. The shutter member 110 is supported in this manner for sliding between a first position in which the shutter portion 111 closes the aperture 107 as shown in Figure 1 and a second position in which the aperture 107 is open with the aperture 109 then being in register with the aperture 107 as shown in Figure 2, and as disclosed for example in Patent Specifications US-A-4 714 973 and US-A-4 685 017. A recess 115 to guide the shutter portion 111 is formed on a major surface of the cartridge body 103 in an area thereof in which the shutter portion 111 is to travel. The recess 115 is of a depth corresponding to the thickness of the shutter portion 111. Thus the outer surface of the shutter portion 111 is substantially flush with the major surface of the cartridge body 103 for the entire sliding stroke of the shutter member 110 with respect to the cartridge body 103. The shutter member 110 may be formed by bending a substantially rectangular metallic plate. The shutter member 110 may however be formed by bending a plate of synthetic resin or by integral moulding of synthetic resin. It is noted that, when the disc cartridge is loaded into disc recording and/or reproducing apparatus, the shutter member 110 has its end face 113, supported by the corresponding lateral side of the cartridge body 103, thrust by shutter opening means, not shown, provided in the disc recording and/or reproducing apparatus, so that the shutter member 110 is slid from the above mentioned first position to the second position, as indicated by arrow c in Figure 2. When the shutter member 110 is slid in this manner by the disc recording and/or reproducing apparatus, the shutter member 111 is subjected to a tilting force relative to the sliding direction due to friction between the cartridge body 103 and the end face 113 of the shutter portion 111. If the shutter portion 111 is shorter in length in a direction along a lateral side of the cartridge body 103 indicated by double-headed arrow a in Figure 1 than in a direction normal to the aforementioned lateral side indicated by double-headed arrow b in Figure 1, the shutter portion 11 tends to be tilted with respect to the sliding direction as indicated by arrow d in Figure 1. Should the shutter portion 111 be tilted with respect to the sliding direction, the shutter member 10 cannot be slid smoothly with respect to the cartridge body 103. On the other hand, if the shutter portion 111 is shorter in length in the direction along the aforementioned one lateral side of the cartridge body 103 than in the direction normal thereto, the shutter portion 111 extends a longer distance from its end face 113 towards its distal end, so that it becomes difficult to form the shutter port ion 111 as a flat plate . For this reason, the shutter portion 111 is usually longer in the direction along the aforementioned one lateral side of the cartridge body 103, that is, in the sliding direction of the shutter member 110, than in the direction normal to the sliding direction of the shutter member 110. Above all, if the shutter portion 111 is formed of synthetic resin, since the shutter portion 111 is lower in toughness than if the shutter portion is formed of metal, it becomes even more important that the shutter portion 111 be longer in the direction along its sliding direction than in the direction normal thereto. However, if the shutter portion 111 has a longer length in its sliding direction, the proportion of the area taken up by the shutter section guide recess 115 to the entire area of the major surface of the cartridge body 103 is necessarily increased. If the proportion of the area taken up by the shutter guide recess 115 is increased in this manner, it becomes difficult to provide the major surface with socalled positioning holes or to apply a label on the major surface. These positioning holes are used for securing the disc cartridge in position within disc recording and/or reproducing apparatus, while the labels are used to indicate the contents of information signals recorded on the disc 102. On the other hand, if the length in the sliding direction of the shutter portion 111 is increased as described above, there may arise a risk that the cartridge body 103 be correspondingly increased in size. That is, since the distance by which the shutter member 110 must be slid relative to the cartridge body 103 is determined by the size of the aperture 107 formed in the cartridge body 103, if the shutter portion 111 is of a longer length in the sliding direction of the shutter member 110, there may arise the risk that, when the shutter member 110 is slid relative to the cartridge body 103, the shutter portion 111 will protrude beyond the corresponding lateral side of the cartridge body 103. Patent Specification EP-A-264 237 discloses a disk cartridge having a shutter member of U-shaped profile including cover portions wide enough to cover head entry apertures in the cartridge and a front plate portion joining the cover portions and projecting laterally of the cover portions in the sliding direction so that the front plate portion, which includes means to cooperate with a shutter opening member, is wider than the cover portions. According to the invention there is provided a disc cartridge comprising: a cartridge body which can expose a portion of a disc accommodated therein to outside by means of an aperture; a shutter integrally formed of synthetic resin with a slide portion slidably mounted on the cartridge body by being engaged with a groove formed in one lateral side of the cartridge body, and a shutter portion to open or close the aperture, the shutter being formed of a synthetic material and being slidable between a first position in which the aperture is closed by the shutter portion and a second position in which the aperture is open; the slide portion being formed with a tongue extended along said one lateral side of the cartridge body so that the length of the slide portion in the sliding direction of the shutter is longer than the length of the shutter portion in the sliding direction, the tongue being formed with an engaging portion engaged with the groove; characterised in that the shutter portion is provided on its surface facing the cartridge body with reinforcement means to reinforce the shutter portion, the reinforcement means including a first rib extending in the sliding direction of the shutter and provided on a surface of the shutter portion facing the cartridge body and a second rib provided on a surface of the shutter portion facing the cartridge body and extending on a lateral side of the shutter portion as considered in the sliding direction. In such a disc cartridge the shutter portion for opening or closing the aperture formed in the cartridge body, may be reduced in size to reduce the size of the disc cartridge yet may be slid smoothly with the aperture formed in the cartridge body being opened or closed positively. The shutter may be moulded of synthetic resin. The invention is diagrammatically illustrated by way of example in the accompanying drawings, in which:- Figure 1 is a plan view showing a disc cartridge including a shutter member of previously proposed kind, with the shutter member closing a recording/reproducing aperture; Figure 2 is a similar view to Figure 1 but with the shutter member moved to open the recording/reproducing aperture; Figure 3 is an exploded perspective view showing another disc cartridge of previously proposed kind provided with a shutter member; Figure 4 is a plan view showing the disc cartridge of Figure 3, with a shutter portion of the shutter member in a first position; Figure 5 is a plan view showing the disc cartridge shown in Figure 3, with the shutter portion in a second position; Figure 6 is an enlarged perspective view showing the shutter member of Figures 3 to 5 with a portion thereof broken away; Figure 7 is an enlarged side view showing the disc cartridge of Figures 3 to 5 with a portion thereof broken away; Figure 8 is an enlarged perspective view showing a modified shutter member for a disc cartridge with a portion thereof broken away; Figure 9 is an enlarged side view similar to Figure 7 showing a further disc cartridge from that shown in Figure 5, with a portion thereof broken away; Figure 10 is an exploded perspective view showing a disc cartridge according to the invention provided with a shutter member; Figure 11 is a plan view showing the disc cartridge of Figure 10, with the shutter portion of the shutter member in a first position; Figure 12 is a plan view showing the disc cartridge of Figure 10, with the shutter portion of the shutter member in a second position; Figure 13 is an enlarged perspective view showing a shutter member for the disc cartridge according to the invention, with a portion thereof broken away; and Figure 14 is an enlarged perspective view showing the shutter member for the disc cartridge according to the invention, shown in a direction different from that of Figure 13 and shown with a portion thereof broken away. Referring to the drawings and firstly to Figure 3, a disc cartridge 1 includes a disc 2 and a cartridge body 3 to accommodate the disc 2. The disc 2, accommodated in the cartridge body 3, is a so-called optical disc in which a recording layer is formed by depositing and moulding an optical recording material or a light reflective material on a base plate formed of a light-transmitting synthetic resin or glass. The disc 2 is formed with a central disc hub 4 by means of which the disc may be clamped with respect to a disc rotating device provided within disc recording and/or reproducing apparatus which can record on and/or reproduce from information signals the recording layer. The disc hub 4 is disc-shaped and formed of a magnetic material, such as metal. The portion of the disc 2 lying around the disc hub 4 represents a signal recording area to record and/or reproduce information signals with the aid of the disc recording and/or reproducing apparatus. The cartridge body 3 comprises an upper half 5 and a mating lower half 6 made of synthetic resin which are abutted and connected to each other such as by ultrasonic welding, adhesive or with set screws in the form of a thin-walled substantially square-shaped casing. That is, each of upper and lower major surfaces 5 a and 6 a of the cartridge body 3 extending parallel to the major surface of the disc 1 is in the form of a square each side of which is slightly longer than the disc diameter. The distance between the major surfaces 5 a and 6 a , that is the thickness of the cartridge body 3, is slightly greater than the thickness of the disc hub 4. The major surfaces 5 a and 6 a of the cartridge body 3 are formed with an upper recording/reproducing aperture 7 and a lower recording/ reproducing aperture 8, respectively, which are in register with each other. These recording/reproducing apertures 7 and 8 are rectangular in profile and extend from near the centre of the major surfaces 5 a and 6 a to close to one side of the respective surface 5 a and 6 a that is to close to one lateral side of the cartridge body 3, so as to be in register with each other with the disc 1 in-between. The upper aperture 7 can expose a portion of the signal recording surface of the disc 2 directed towards the upper half 5 to outside between the inner and outer peripheries of the disc. The lower aperture 8 can expose a portion of the signal recording surface of the disc 2 directed towards the lower half 6 to outside between the inner and outer peripheries of the disc. A recording and/or reproducing unit of disc recording and/or reproducing apparatus, such as an optical head device, is introduced via these apertures 7 and 8 into the cartridge body 3 to record and/or reproduce information signals on or from the disc 1. If the disc 2 accommodated within the cartridge body 3 is a magneto-optical disc, an external magnetic field generating device to supply the external magnetic field to the disc needs to be provided in the disc recording and/or reproducing apparatus in addition to the optical head device. The major surface of the lower half 6 is formed with a circular chucking aperture 9 to permit the lower surface of the disc hub 4 to be exposed to outside. It is by means of the chucking aperture 9 that a chucking device of disc rotating means of the disc recording and/or reproducing apparatus, such as a disc table, can be introduced into the cartridge body 3 to chuck the disc 2. A shutter member 10 to open or close the recording/reproducing apertures 7 and 8 is mounted on the cartridge body 3. The shutter means 10 comprises a slide portion 13, supported by one lateral side of the cartridge body 3, and upper and lower plate portions or shutter portions 11 and 12, and is formed integrally from a synthetic resin, such as polyacetal resin. The slide portion 13 is in the form of an elongate plate having a width equal to the thickness of the cartridge body 3. The shutter portions 11 and 12 are in the shape of rectangles larger in size than the recording/reproducing apertures 7 and 8 to close the apertures 7 and 8 and are of a predetermined thickness of approximately 0.3mm for example. When seen in cross-section, the shutter member 10 is in the form of a letter U having the slide portion 13 as a web and the shutter portions 11 and 12 as the sides of the letter U, so that the shutter portions face each other and are spaced apart. The slide portion 13 is formed with a tongue 13 a extending in one longitudinal direction. The tongue 13 a is in the form of a flat rectangular plate portion of substantially the same width and thickness as the slide portion 13 interconnecting the shutter portions 11 and 12. The tongue 13 a extends in one longitudinal direction beyond the respective lateral side of the shutter portions 11 and 12. Referring to Figures 3, 6 and 7, the inner surface of the slide portion 13, directed towards the distal ends or free ends of the shutter portions 11 and 12, is formed with first and second engaging pawls 17, 18 which can engage supporting grooves 14, 14 formed in the vicinity of said one lateral side of the cartridge body 3. The supporting grooves 14, 14 are defined between a pair of upright ribs extending parallel to each other and to the aforementioned lateral side of the upper and lower halves 5 and 6 of the cartridge body 3. A slit 14 a is formed in the aforementioned lateral side to extend parallel to the supporting grooves 14, 14. The engaging pawls 17, 18 are formed integral with the slide portion 13 and provided with enlarged ends. It is noted that the first engaging pawl 17 is provided at the foremost part of the tongue 13 a while the second engaging pawl 18 is provided at the other end of the slide portion 13 opposite to the side thereof provided with the tongue 13 a . Referring to Figures 6 and 7, the slide portion 13 is supported with its inner lateral side substantially in contact with the lateral side of the cartridge body 3 by introducing the engaging pawls 17 and 18 into the cartridge body 3 by means of the slit 14 a and by engaging the enlarged ends of the engaging pawls 17, 18 in the supporting grooves 14, 14. Since the engaging pawls 17, 18 may be slid along the supporting grooves 14, 14 the slide portion 13 may be slid along said one lateral side of the cartridge body 3. By having its slide portion 13 supported by said one lateral side of the cartridge body 3, the shutter member 10 is supported by the cartridge body 3, with the shutter portions 11 and 12 lying along the upper and lower major surfaces 5 a and 6 a , respectively. Also, by having its slide portion 13 slidable with respect to the cartridge body 3, the shutter member 10 may be slid with respect to the cartridge body 3, as shown in Figures 4 and 5, so that the shutter portions 11 and 12 are moved along the upper and lower major surfaces 5 a and 6 a , respectively. By sliding the shutter member 10 with respect to the cartridge body 3, the upper shutter portion 11 is slid between the first position of closing the upper recording/reproducing aperture 7 as shown in Figure 4 and the second position of opening the aperture 7 as shown in Figure 5. Similarly to the upper shutter portion 11, the lower shutter portion 12 is slid, by sliding the shutter member 10 with respect to the cartridge body 3, between the first position of closing the lower recording/reproducing aperture 8 and the second position of opening the aperture 8. These first and second positions are so oriented relative to each other that, when the shutter portions 11, 12 are in the aforementioned second position, the first position is situated towards the side of the cartridge body corresponding to the direction of extension of the tongue 13 a . First and second shutter guide recesses 15 and 16 are formed in the portions of the major surfaces 5 a and 6 a of the cartridge body 3 corresponding to the travel passage of the shutter portions 11 and 12 of the shutter member 10. The first shutter guide recess 15, provided in the upper major surface 5 a , is formed in an area to be traversed by the upper shutter portion 11 as it is moved from the first position to the second position, and is of a depth from the upper major surface 5 a of approximately 0.3mm, for example, corresponding to the thickness of the upper shutter portion 11. In this manner, the upper surface of the upper shutter portion 11 is substantially flush with the upper surface 5 a throughout the stroke of movement of the shutter member 10 between the first and second positions. The second shutter guide recess 16 in the lower major surface 6 a is formed in an area to be traversed by the lower shutter portion 12 as it is moved from the first position to the second position, and is of a depth from the lower major surfaces 6 a of approximately 0.3mm, for example, corresponding to the thickness of the lower shutter portion 12. In this manner, the lower surface of the lower shutter portion 12 is substantially flush with the lower surface 6 a throughout the stroke of movement of the shutter member 10 between the aforementioned first and second positions. With the above described disc cartridge 1 the shutter portions 11 and 12 of the shutter member 10 are in the aforementioned first position, during non-use time, in which they close the recording/reproducing apertures 7 and 8 to prevent dust and dirt or the user's fingers from intruding into the inside of the cartridge body 3 by means of the recording/reproducing apertures 7 and 8. In use, the disc cartridge 1 is loaded onto disc recording/reproducing apparatus causing the shutter member 10 to be moved, by opening means of the disc recording and/or reproducing apparatus, from the aforementioned first position to the second position of the shutter portions 11 and 12, as indicated by arrow C in Figure 5. When in the second position, the shutter portions 11 and 12 open the recording/ reproducing apertures 7 and 8 to permit information signals to be recorded or reproduced on or from the disc 2 by means of the recording/ reproducing apertures 7 and 8. With the above described shutter member 10 of the disc cartridge 1, since the slide portion 13 is formed with the tongue 13 a the sliding length of the slide portion 13 and the tongue 13 a along the lateral side of the cartridge body 3, shown by a double-headed arrow D in Figure 4, is longer than the sliding length of the shutter portions 11 and 12 along the aforementioned lateral side as indicated by a double-headed A in Figure 4. The result is that, when the shutter member 10 is slid by the slide portion 13 being acted upon by the disc recording and/or reproducing apparatus, the shutter member 10 is prevented from being tilted relative to the sliding direction due to friction between the shutter portions 11 and 12 and the cartridge body 3. If the length of the slide portion 13 and the tongue 13 a as indicated by double-headed arrow D in Figure 4, is selected to be longer than the length of the shutter portions 11 and 12 in the direction normal to the sliding direction, as indicated by a double-headed arrow B shown therein, the shutter member 10 may be protected more effectively from being tilted with respect to the sliding direction in the course of sliding of the shutter member 10. Since the shutter member 10 can be formed of a material exhibiting satisfactory temperature and humidity characteristics, such as polyacetal resin, it is unlikely to be deformed with changes in temperature or humidity. If the shutter member 10 is formed of a material exhibiting so-called self-wetting characteristics, such as the above mentioned polyacetal resin, it is not subject to so-called powder debris, that is the phenomenon of fragments of material being rubbed off as powders due to friction between the shutter member and the cartridge body 3. As shown in to Figure 8, the shutter member 10 can be provided not only with a tongue 13 a extending in one longitudinal direction but also with a second tongue 13 b extending in the opposite longitudinal direction. Similarly to the tongue 13 a , the second tongue 13 b is formed as a rectangular plate having a width and a thickness equal to those of the slide portion 13 interconnecting the shutter portions 11 and 12. The second tongue 13 b extends beyond the respective lateral side of the shutter member 10. When the first and second tongue 13 a and 13 b are formed in this manner with the slide portion 13 of the shutter member 10, the second engaging pawl 18 may be provided on the second tongue 13 b . Such a shutter member 10 may similarly be prevented from being tilted relative to its sliding direction due to the force of friction between the shutter portions 11, 12 and the cartridge body 3 even if the shutter member 13 is acted upon by the disc recording and/or reproducing apparatus as described above. With the above described disc cartridge 1, the supporting grooves 14, 14 are formed by gaps defined between the opposite parallel ribs. As shown in Figure 9, the supporting grooves 14, 14 can be replaced by supporting slits 19, 20 formed on the inner surfaces of the upper and lower halves 5 and 6. The enlarged ends of the engaging pawls 17 and 18 are engaged in the supporting slits 19, 20, as in the supporting grooves 14, 14, slidably to support the slide portion 13 of the shutter member 10. As described above the shutter portions 11 and 12 need be strong enough not to be deformed on repeated sliding movements of the shutter member 10 with respect to the cartridge body. That is, if the strength of the shutter portions 11 and 12 was insufficient, the shutter portions 11 and 12 would be deformed, so that not only the apertures 7 and 8 of the cartridge body 3 could not be opened or closed, but also the loading or unloading operation of the disc cartridge into or out of the disc recording and/or reproducing apparatus could not be performed. Above all, if the shutter member 10 is formed of synthetic resin, the shutter portions 11 and 12 tend to be deformed with changes in the operating environmental temperature. The above mentioned problem is felt most keenly when the shutter member 10 is reduced in thickness. Referring to Figures 10 to 14, a shutter member for a disc cartridge according to the invention is shown. In the following description, the parts or components which are the same as those described with reference to Figures 1 to 9 are not explained for simplicity. A shutter member 210 for the disc cartridge 1 shown in Figure 10 is used for opening and closing the recording/reproducing apertures 7 and 8. The shutter member 210, formed integrally of a synthetic resin, such as polyacetal resin, comprises upper and lower shutter portions 211 and 212, lying oppositely to each other, and a connecting portion 213 interconnecting the shutter portions 211 and 212. Each of the shutter portions 211 and 212 is in the form of a rectangle slightly larger in size than the apertures 7 and 8 so as completely to close the apertures 7 and 8. When seen in cross-section, the shutter member 210 is in the form of a letter U with the connecting portion 213 forming a web substantially equal to the thickness of the cartridge body 3 and the shutter portions 211, 212 forming the sides of the letter U, respectively. The shutter portions 211, 212 are of a predetermined uniform thickness, for example, 0.3mm. The shutter member 210 is formed integrally with a tongue 213 a extending in the sliding direction to stabilise the sliding movement of the shutter member 210 with respect to the cartridge body 3. On a surface of the upper shutter portion 211 of the shutter member 210 facing the lower shutter portion 212, first and second ribs 211 a and 211 b are formed integrally. Similarly, on a surface of the lower shutter portion 212 of the shutter member 210, facing the upper shutter portion 211, first and second ribs 212 a and 212 b are formed integrally. The first rib 211 a of the upper shutter portion 211 is formed on the free end of the upper portion 211 to extend along the free end from one lateral side to the other lateral side of the upper shutter portions 211. Similarly to the first rib 211 a of the upper shutter portion 211, the first rib 212 a of the lower shutter portion 212 is formed on the free end of the lower shutter portion 212 to extend along the free end from one lateral side to the other lateral side of the lower shutter portion 212. The first ribs 211 a , 212 a run parallel to and face each other and project a predetermined distance of, for example, 0.3mm, from the shutter portions 211, 212, respectively. The second rib 211 b of the upper shutter portion 211 is provided on one lateral side of the upper shutter portion 211 to extend along this lateral side from the proximal end to the free end of the shutter portion 211. Thus the second rib 211 b is contiguous to the first rib 211 a at the free end of the upper shutter portion 211. Similarly to the second rib 211 b of the upper shutter portion 211, the second rib 212 b of the lower shutter portion 212 is provided on one lateral side of the lower shutter portion 212 to extend along this lateral side from the proximal end to the free end of the shutter portion 212. Thus the second rib 212 b is contiguous to the first rib 212 a at the free end of the lower shutter portion 212. The first ribs 211 b , 212 b run parallel to and face each other and project a predetermined distance of, for example, 0.3mm, from the shutter portions 211, 212, respectively. The inner surface of the connecting portion 213 towards the proximal end of the shutter portions 211, 212 is formed with an engaging pawl 217 to engage with the supporting groove 14 formed in said one lateral side of the cartridge body 3. The inner surface of the tongue 213 a is also provided with an engaging pawl 218 to engage with the supporting groove 14. The engaging groove 14 is provided on said one lateral side of the cartridge body 3 mating with the sides of the major surfaces 5 a , 6 a , in the vicinity of the recording/reproducing apertures 7 and 8. The shutter member 210 is supported by the cartridge body 3 by having the engaging pawls 217, 218 of the connecting portion 213 engaged in the supporting groove 14 so that the upper shutter portion 211 extends along the upper major surface 5 a and the lower shutter portion 212 extends along the lower major surface 6 a , with the distal ends being the free ends. With the engaging pawls 217, 218 being supported for sliding along the supporting grooves 14, the shutter member 210 may be slid relative to the cartridge body 3, so that the upper shutter portion 211 is slid along the upper major surface 5 a and the lower shutter portion 212 is slid along the lower major surface 6 a . By sliding the shutter member 210 relative to the cartridge body 3, the upper shutter portion 211 is slid between the first position in which it closes the upper recording/reproducing aperture 7 as shown in Figure 12 and the second position in which it opens the aperture 7 as shown in Figure 13. Similarly to the upper shutter portion 211, the lower shutter portion 212 is slid, by sliding the shutter member 210 with respect to the cartridge body 3, between the first position in which it closes the lower recording/reproducing aperture 8 and the second position in which it opens the aperture 8. These first and second positions are so oriented relative to each other that, when the shutter portions 211, 212 are in the aforementioned second position, the first position is situated towards the lateral side of the cartridge body associated with the second ribs 211 b , 212 b of the shutter portions 211, 212. With the shutter member 210, the first ribs 211 a , 212 a extend along the sliding direction of the shutter member 210 with respect to the shutter member 210, while the second ribs 211 b , 212 b extend in a direction normal to the sliding direction of the shutter member 210 with respect to the cartridge body 3. The first and second shutter guide recesses 15 and 16 are formed in those portions of the major surfaces 4 a and 5 a of the cartridge body 3 through which the shutter member 210 is moved. The first shutter guide recess 15 in the upper major surface 5 a is formed in an area to be traversed by the upper shutter portion 211 as it is moved from the first position to the second position, and is of a depth from the upper major surface 5 a of approximately, for example, 0.33mm, corresponding to the thickness of the upper shutter portion 211. Within an area of the first shutter member guide recess 15 to be traversed by the first and second ribs 211 a , 211 b of the shutter portion 211 in the course of movement of the shutter member 210 from the first position to the second position, there is formed a rib guide recess 15 a which is of a predetermined depth from the upper major surface 5 a of, for example, approximately 0.6mm, corresponding to the thickness of the ribs 211 a , 211 b of the shutter portion 211. This rib guide recess 15 a is provided in the vicinity of the upper recording/reproducing aperture 7 and of the periphery of the first shutter guide recess 15 corresponding to the mid region of the upper major surface 5 a . In this manner, the upper surface of the upper shutter portion 211 is substantially flush with the upper surface section 5 a throughout the stroke of movement of the shutter member 210 between the aforementioned first and second positions. The second shutter guide recess 16 in the lower major surface 6 a is formed in an area to be traversed by the lower shutter portion 212 as it is moved from the first position to the second position, and is of a depth from the upper major surface 6 a of approximately, for example, 0.3mm, corresponding to the thickness of the lower shutter portion 211. Within an area of the second shutter guide recess 16 to be traversed by the first and second ribs 212 a , 212 b of the lower shutter portions 212 in the course of movement of the shutter member 210 from the first position to the second position, there is formed a rib guide recess 16 a which is of a predetermined depth from the lower major surface 6 a of, for example, approximately 0.6mm, corresponding to the thickness of the ribs 212 a , 212 b of the shutter portion 212. This rib guide recess 16 a is provided within the second shutter guide recess 16 in the vicinity of the upper recording/reproducing aperture 7 and of the periphery of the second shutter guide recess 16 corresponding to the mid region of the lower major surface 6 a . In this manner, the lower surface of the lower shutter portion 212 is substantially flush with the lower surface section 6 a throughout the stroke of movement of the shutter member 210 between the aforementioned first and second positions. With the above described disc cartridge 1, the shutter portions 211, 212 of the shutter member 219 are kept during non-use time in the aforementioned first position of closing the recording/reproducing apertures 7 and 8 to prevent dust and dirt or the user's fingers from intruding into the inside of the cartridge body 3 by means of the recording/reproducing apertures 7 and 8. On the other hand, when the disc cartridge 1 is in use, the shutter portions 211, 212 of the shutter member 210 are brought to the aforementioned second position of opening the apertures 7 and 8 to permit information signals to be written or read on or from the disc 2 by means of the recording/reproducing apertures 7 and 8. With the shutter portions 211, 212 of the shutter portion 210, the in-plane curvature is reinforced by the first ribs 211 a 211 b running at right angles to the second ribs 212 a , 212 b . Meanwhile, since the shutter member 210 is formed of a material exhibiting satisfactory temperature and humidity characteristics, such as polyacetal resin, it is unlikely to be deformed with changes in temperature or humidity. Since the shutter member 210 is formed of a material exhibiting so-called self-wetting characteristics, such as the above mentioned polyacetal resin, it is not subject to so-called powder debris, that is the phenomenon of fragments of material being rubbed off as powders due to friction between the shutter member and the cartridge body 3. By adjusting the protuberance of the first ribs 211 a , 212 a and the depth of the portions of the rib guide recesses 15 a , 16 a mating with these ribs, it becomes possible to prevent sliding contact between the surfaces of the shutter portions 211, 212 and the cartridge body 3 in the course of the sliding movement of the shutter member 20. In this manner, the aforementioned powder debris may be prevented more effectively. It is noted that the invention is not limited to a disc cartridge in which the recording/reproducing apertures are formed in both of its major surfaces, but may also be applied to a disc cartridge in which the recording/reproducing aperture is formed in only one of its major surfaces. In this case, the shutter member is provided with a sole shutter portion in association with the sole recording/reproducing aperture. It is also noted that the invention is not limited to a disc cartridge for accommodating an optical disc or a magneto-optical disc, but may also be applied to a disc cartridge for accommodating a magnetic disc, such as a so-called floppy disc.

Claims: A disc cartridge comprising: a cartridge body (3) which can expose a portion of a disc (2) accommodated therein to outside by means of an aperture (7, 8); a shutter (210) integrally formed of synthetic resin with a slide portion (213) slidably mounted on the cartridge body (3) by being engaged with a groove (14) formed in one lateral side of the cartridge body (3), and a shutter portion (211, 212) to open or close the aperture (7, 8), the shutter (210) being formed of a synthetic material and being slidable between a first position in which the aperture (7, 8) is closed by the shutter portion (211, 212) and a second position in which the aperture (7, 8) is open; the slide portion (213) being formed with a tongue (213 a ) extended along said one lateral side of the cartridge body (3) so that the length of the slide portion (213) in the sliding direction of the shutter (210) is longer than the length of the shutter portion (211, 212) in the sliding direction, the tongue (213 a ) being formed with an engaging portion (217) engaged with the groove (7, 8); characterised in that the shutter portion (211, 212) is provided on its surface facing the cartridge body (3) with reinforcement means (211 a , 211 b , 212 a , 212 b ) to reinforce the shutter portion, the reinforcement means including a first rib (211 a , 212 a ) extending in the sliding direction of the shutter and provided on a surface of the shutter portion (211, 212) facing the cartridge body (3) and a second rib (212 a , 212 b ) provided on a surface of the shutter portion (211, 212) facing the cartridge body (3) and extending on a lateral side of the shutter portion as considered in the sliding direction. A disc cartridge according to claim 1, wherein the shutter portion (211, 212) of the shutter (210) is substantially L-shaped relative to the slide portion (213) and wherein the shutter (210) is provided with an engaging section (218) engaged with the groove (14).

Inventors: FUJISAWA HIROTOSHI, FUJISAWA, HIROTOSHI
Applicants: SONY CORP, SONY CORPORATION
Application year: 1992
Main classification: G11B23
IPC codes: G11B23