Disc cartridge

Abstract: A disc cartridge has a cartridge body (2) formed with an aperture (6) for exposing at least a part of the signal recording area of an accommodated disc (1), and a shutter (9) slidably mounted on the cartridge body (2) to open or close the aperture (6). The cartridge body (2) is provided with a shutter opening groove (18) extending along the sliding direction of the shutter (9) which is parallel to the direction (L) of insertion of the disc cartridge (2) into a recording and/or reproducing apparatus to record and/or reproduce information signals on or from the disc, and a mistaken insertion inhibiting groove (19) extending parallel to the shutter opening groove (18) and having a length (G) shorter than the length (F) of the shutter opening groove (18). Mistaken insertion of the disc cartridge may be inhibited by mistaken insertion inhibiting pins (52, 53) provided in the recording and/or reproducing apparatus for mating with each of the grooves (18, 19).

Description: The invention relates to a disc cartridge. Such a disc cartridge may have, 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. There has previously been proposed a disc for recording and/or reproducing information signals, such as a magneto-optical disc or an optical disc, comprising a disc-shaped base plate and a recording layer formed on at least one major surface of the base plate. A central portion of the disc is formed as a clamping portion which is retained by a disc driving unit of a recording and/or reproducing apparatus to record and/or reproduce information signals on or from the disc. The portion of the disc lying around the clamping portion is reserved as a signal recording area on or from which the information signals are written or read. Referring to Figures 1 and 2 of the accompanying drawings, there has hitherto been proposed a disc cartridge comprising a cartridge body 102 and a shutter member 104 which is accommodated within the cartridge body to prevent deposition of dust and dirt on a disc 101 or damage thereto due to contact, especially with fingers, as well as to facilitate handling of the disc 101. The disc 101 accommodated within the cartridge body 102 may be rotated therein by disc rotating means. Referring to Figure 2, one major surface of the cartridge body 102 is formed with an aperture 103 by means of which at least a part of the signal recording surface of the disc may be exposed to outside between its inner and outer peripheries. Information signals may be recorded and/or reproduced on or from the signal recording area by means of disc recording and/or reproducing apparatus through the aperture 103. The shutter member 104 closes the aperture 103 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 102. The shutter member 104 is provided with a shutter portion 105 of a size large enough to close the aperture 103. The shutter portion 105 is formed with a through-hole 106 corresponding in size and shape to the aperture 103. The shutter member 104 is mounted to slide along one lateral side of the cartridge body 102 by having a proximal end face 108 thereof supported by said one lateral side of the cartridge body 102. The shutter member 104 is supported for sliding between a first position in which the aperture 103 is closed by the shutter portion 105 as shown in Figure 1 and a second position in which the aperture 103 is open with the through-hole 106 in register with the aperture 103 as shown in Figure 2. The shutter member 104 can be formed by bending a substantially rectangular metallic plate. The shutter member 104 may alternatively be formed by bending a plate of synthetic resin or by integral moulding of synthetic resin. A recess 107 to guide the shutter portion 105 is formed on the major surface of the cartridge body 102 in an area thereof corresponding to the travel path of the shutter portion 105. The recess 107 is of a depth corresponding to the thickness of the shutter portion 105. Thus the upper surface of the shutter portion 105 is substantially flush with the major surface of the cartridge body 102 for the entire sliding stroke of the shutter member with respect to the cartridge body 102. When loaded on disc recording and/or reproducing apparatus, the disc cartridge is introduced at an entrance opening provided in the disc recording and/or reproducing apparatus with a direction normal to the sliding direction of the shutter member 104 as the inserting direction as shown by an arrow d in Figure 1. The shutter member 104 can be slid by a shutter member opening device, not shown, provided in the recording and/or reproducing apparatus, in a direction of opening the aperture 103, as indicated by an arrow c in Figure 2. With the above described disc cartridge, if the disc cartridge is inserted at the entrance opening in an erroneous direction, there arises a risk that portions of the cartridge body 102 not provided with the aperture 103 will be abutted by a magnetic device or an optical head device provided in the disc recording and/or reproducing apparatus, possibly causing damage to or destruction of the magnetic device, optical head device or the cartridge body 102. With a conventional disc cartridge, the length of a side of the cartridge body 102 parallel to its inserting direction and shown by arrow a in Figure 1, that is the side corresponding to a lateral side of the cartridge body 102, is selected to be longer than that of a side thereof normal to the inserting direction shown by arrow b in Figure 1, that is a side corresponding to the forward side of the cartridge body 102. In such case, a mistaken operation of introducing the cartridge body 102 into the entrance opening in a direction normal to the proper inserting direction may be prevented by selecting the length of the entrance opening to be approximately equal to the length of the side of the cartridge body 102 normal to the proper inserting direction. However, with such disc cartridges, since it is necessary to select the lengths of the lateral sides of the cartridge body 102 as described above, it becomes necessary to increase the size of the cartridge body beyond the minimum size required for accommodating the disc 101. On the other hand, even if the length of the lateral side of the cartridge body 102 is selected to differ from that of its forward side, it is impossible to prevent mistaken inserting operations of inserting the disc cartridge at the entrance opening with the rear side of the cartridge body as the leading end or of inserting the disc cartridge body in a topsy-turvy position. First and second mistaken insertion inhibiting grooves 111, 113 can be provided on the lateral sides of the cartridge body 102, as shown in Figures 3 and 4, thereby preventing the disc cartridge from being introduced in the direction normal to the proper inserting direction without the necessity of enlarging the length of the lateral side of the cartridge body 102 shown by arrow a in Figure 4. The first mistaken insertion inhibiting groove 111 is formed on the bottom surface of the cartridge body 102 to extend from the forward side towards the rear side of the cartridge body 102 when looking in its inserting direction shown by arrow d in Figure 4. The second mistaken insertion inhibiting groove 113 is formed on the lateral side of the cartridge body 102 to extend from the leading side towards the trailing side of the cartridge body 102 when looking in its inserting direction shown by arrow d in Figure 4. The distance between the grooves 111 and 113, indicated by double-headed arrow b in Figure 4, is selected to be shorter than the length of the lateral side of the cartridge body 102 shown by double-headed arrow a in Figure 4. In this manner, if lugs or the like mating with these grooves 111, 113 are provided in the vicinity of the entrance opening provided in the disc recording and/or reproducing apparatus, the cartridge body 102 may be positively prevented from being introduced into the entrance opening in the direction normal to its proper inserting direction. However, there are occasions wherein indicating holes or grooves are formed on the outer lateral side of the cartridge body 102 to indicate disc types, such as a disc in which information signals may be recorded and reproduced, eg a magneto-optical disc, a disc in which information signals may be recorded and reproduced but from which information signals, once recorded, cannot be erased, or a disc from which information signals can only be reproduced, eg an optical disc. With the above described disc recording and/or reproducing apparatus, it is necessary to adjust or switch the intensities of the magnetic field generating device, operating or non-operating states or the light output of the optical pickup device, depending on the disc types. For this reason, microswitches or the like are provided in the disc recording and/or reproducing apparatus to detect the presence or absence of these indicating holes or grooves to perform the adjusting or switching operations. If the mistaken insertion preventing grooves are provided in a cartridge body already provided with these indicating holes or grooves, there arises a risk that the cartridge body becomes inferior in mechanical strength such that the disc 101 cannot be protected positively. On the other hand, if the mistaken insertion inhibiting grooves are provided in the cartridge body, the area on the lateral side thereof to be reserved for the indicating holes or grooves becomes narrow so that the disc cartridge needs to be enlarged in size for providing these indicating holes or grooves. Patent Specification EP-A-205 074 discloses a combination of a disc cartridge case and a play back device, the case having grooves in two of the side faces thereof in one of which a shutter opening lever is located and in the other of which a rack is provided for cooperation with a feed motor driven pinion. To prevent erroneous insertion, front corners of the case are rounded and one is provided with a recess with a step therein. In the event of erroneous insertion, spring loaded blocking members are engaged by the step or by square rear end corners of the case to stop insertion. Patent Specification EP-A-195 535 discloses a disk cassette with a shutter rectilinearly slidable thereon and having a groove in the cassette to receive a shutter opening member. According to the invention there is provided a disc cartridge comprising: a rectangular cartridge main body containing a disc-shaped recording medium and having a first aperture formed in at least one major surface thereof to extend from an inner peripheral region of the disc-shaped recording medium to an outer peripheral region of the disc-shaped recording medium, a second aperture circularly formed in the same surface as the first aperture and a shutter opening groove to receive an external shutter opening member and formed in a lateral side of the cartridge main body extending parallel to the inserting direction of the disc cartridge, the shutter opening groove having an upstream, considered in the inserting direction of the disc cartridge, open end to receive the external shutter opening member and a downstream, considered in the inserting direction of the disc cartridge, closed end; and a shutter member movably mounted with respect to the disc cartridge main body to open and close the first aperture, characterised in that the shutter member comprises a slide portion supported by said lateral side of the cartridge main body and a shutter portion to close the first aperture and the shutter member is movable between a first position and a second position spaced apart in the inserting direction of the disc cartridge, the first aperture being closed by the shutter portion when it is positioned at the first position and being open when the shutter member is positioned at the second position, wherein a mistaken insertion inhibiting groove formed in the cartridge main body extends parallel to the shutter opening groove and is provided in the lateral side face of the cartridge main body disposed opposite to said lateral side face in which the shutter opening groove is formed, the mistaken insertion inhibiting groove having an open end provided at the same side of the main body as the open end of the shutter opening groove and the length of the mistaken insertion inhibiting groove being shorter than the length of the shutter opening groove. Such a disc cartridge can be prevented from being introduced into the recording and/or reproducing apparatus in a mistaken or incorrect manner but need not have an increased size and need not have reduced mechanical strength. The mistaken insertion inhibiting grooves of the disc cartridge may also be used for discriminating the disc types. The mistaken insertion inhibiting grooves may be divided into a plurality of regions of different depths. Since the disc cartridge is formed with a mistaken-insertion inhibiting groove extending parallel to and shorter in length than the shutter opening groove, it is possible, by providing detection pins or similar means in the recording and/or reproducing apparatus in association with the grooves, to prevent the mistaken inserting operation of inserting the disc cartridge from a mistaken inserting direction. Since the mistaken insertion inhibiting groove is shorter in length than the shutter opening groove, there is no necessity for enlarging the size of the disc cartridge for the sake of providing the mistaken insertion inhibiting groove. By dividing the mistaken insertion inhibiting groove into a plurality of regions of different depths, it is possible to discriminate the type of the disc accommodated in the disc cartridge. 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 of a previously proposed kind; Figure 2 is a plan view showing the disc cartridge of Figure 1 with a shutter member closing an aperture in the cartridge body; Figure 3 is a side view, as viewed from the front side, showing a disc cartridge of a previously proposed kind provided with a disc type indicating grooves; Figure 4 is a plan view showing the disc cartridge of Figure 3; Figure 5 is an exploded perspective view showing a disc cartridge according to a first embodiment of the invention; Figure 6 is a plan view showing the disc cartridge of Figure 5; Figure 7 is a plan view showing the disc cartridge of Figure 6, with a shutter member closing a recording/reproducing aperture; Figure 8 is a side view, as viewed from the forward side, showing the disc cartridge of Figure 6; Referring to the drawings, preferred embodiments of the invention are shown applied to a disc cartridge in which a disc accommodated therein is an optical disc to record and/or reproduce information signals by means of a laser beam radiated from a recording and/or reproducing apparatus. Referring first to Figure 5, a disc cartridge includes a disc 1 and a cartridge body 2 accommodating the disc 1. The disc 1, accommodated in the cartridge body 2, 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 1 is formed with a central disc hub 3 by means of which the disc may be clamped with respect to a disc rotating device, not shown, provided within disc recording and/or reproducing apparatus to record and/or reproduce information signals on or from the recording layer. The disc hub 3 is disc-shaped and formed of a magnetic material, such as metal. The portion of the disc 1 lying around the disc hub 3 represents a signal recording area for recording and/or reproducing information signals with the aid of the disc recording and/or reproducing apparatus. On the other hand, the cartridge body 2 is made up of an upper half 4 and a mating lower half 5 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 4 a and 5 a of the cartridge body 2 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 4 a and 5 a , that is the thickness of the cartridge body 2, is slightly thicker than the thickness of the disc hub 3. The major surfaces 4 a and 5 a of the cartridge body 2 are formed with an upper recording/reproducing aperture 6 and a lower recording/reproducing aperture 7, respectively, which are in register with each other. These recording/reproducing apertures 6 and 7 are rectangular in profile and extend from near the middle of the major surfaces 4 a and 5 a to close to one side of the surfaces 4 a and 5 a , respectively, that is, to close to one lateral side of the cartridge body, so as to be in register with each other with the disc 1 in-between. The upper aperture 6 can expose a portion of the signal recording surface of the disc 1 directed towards the upper half 4 to outside between the inner and outer peripheries of the disc. The lower aperture 7 can expose a portion of the signal recording surface of the disc 1 directed towards the lower half 5 to outside between the inner and outer peripheries of the disc. A recording and/or reproducing device of disc recording and/or reproducing apparatus, such as an optical head device, is introduced via these apertures 6 and 7 into the cartridge body 2 to record and/or reproduce information signals on or from the disc 1. If the disc 1 accommodated within the cartridge body 2 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 5 is formed with a circular chucking aperture 8 to permit the lower surface of the disc hub 3 to be exposed to outside. It is by means of this chucking aperture 8 that a chucking device of disc rotating means of the disc recording and/or reproducing apparatus, such as a disc table, is introduced into the cartridge body 2 to chuck the disc 1. A shutter member 9 to open or close the recording/reproducing apertures 6 and 7 is mounted on the cartridge body 2, as shown in Figures 5 and 6. The shutter member 9 comprises a slide portion 10, supported by a lateral side of the cartridge body 2, and upper and lower shutter portions 11 and 12, and is formed integrally from a synthetic resin, such as polyacetal resin. The slide portion 10 is in the form of an elongate plate having a width equal to the thickness of the cartridge body 2. The shutter portions 11 and 12 are in the form of rectangles larger in size than the recording/reproducing apertures 6 and 7 to close the apertures 6 and 7 and are of a predetermined thickness of, for example, approximately 0.3mm. When seen in crosssection, the shutter member 9 is in the form of a letter U having the slide portion 10 as a web and the shutter portions 11 and 12 as both sides of the letter U, so that the shutter portions face each other with a gap in-between which corresponds to the thickness of the cartridge body 2. The shutter portions 11 and 12 are formed with through-holes 13 and 14, respectively, which are substantially in register with the recording/reproducing apertures 6 and 7, respectively. The face of the slide portion 10 is formed with engaging lugs, not shown, directed towards the distal free ends of the shutter portions 11 and 12, to engage with supporting grooves 15, 15 provided in the vicinity of said one lateral side of the cartridge body 2. The supporting grooves 15, 15 are defined between a pair of ribs provided in the vicinity of said one lateral side on the facing sides of the upper and lower halves 4 and 5 extending parallel to each other and to said one lateral side. Said one lateral side of the cartridge body 2 is formed with a slit 15 a extending along the supporting grooves 15, 15. The engaging lug of the slide portion 10 is introduced via the slit 15 a into the cartridge body 2 so that the slide portion 10 is supported with the inner lateral side thereof abutted on said one lateral side of the cartridge body 2. Since the engaging lug may be slid along the supporting grooves 15, 15, the slide portion 10 may be slid along said one lateral side of the cartridge body 2. By having its slide portion 10 supported by said one lateral side of the cartridge body 2, the shutter member 9 is supported by the cartridge body 2, with the shutter portions 11 and 12 lying along the upper and lower major surfaces 4 a and 5 a , respectively. Also, by having its slide portion 10 slidable with respect to the cartridge body 2, the shutter member 9 may be slid with respect to the cartridge body 2, as shown by arrows J and K in Figure 5, so that the shutter portions 11 and 12 are moved along the upper and lower major surfaces 4 a and 5 a , respectively. With the shutter member 9 sliding in this manner with respect to the cartridge body 2, the upper shutter plate 11 may be slid between a first position in which it closes the upper recording/reproducing aperture 6, with the aperture 6 then being out of register with the through-hole 13, as shown in Figure 6, and a second position in which it opens the upper recording/reproducing aperture 6, with the aperture 6 then being in register with the through-hole 13, as shown in Figure 7. Similarly, with the shutter member 9 sliding with respect to the cartridge body 2, the lower shutter plate 11 may be slid between a first position in which it closes the lower recording/reproducing aperture 7, with the aperture 7 then being out of register with the through-hole 14, and a second position in which it opens the lower recording/reproducing aperture 7, with the aperture 7 then being in register with the through-hole 14. These first and second positions are so oriented relative to each other that the direction from the second to the first position corresponds to the inserting direction of the disc cartridge into the disc recording and/or reproducing apparatus as shown by arrow L in Figures 5 and 6. First and second shutter guide recesses 16 and 17 are formed in the portion of the major surfaces 4 a and 5 a of the cartridge body 2 corresponding to the travel path of the shutter portions 11 and 12 of the shutter member 9. The first shutter guide recess 16 in the upper major surface 4 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 4 a of, for example, approximately 0.3mm, 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 4 a throughout the stroke of movement of the shutter member 9 between the aforementioned first and second positions. The second shutter guide recess 17 in the upper major surface 5 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 surface 5 a of, for example, approximately 0.3mm, corresponding to the thickness of the lower shutter portion 12. In this manner, the upper surface of the upper shutter portion 12 is substantially flush with the lower surface 5 a throughout the stroke of movement of the shutter member 9 between the aforementioned first and second positions. The lateral sides of the cartridge body 2 are formed with a shutter opening groove 18 and a mistaken insertion inhibiting groove 19, as shown in Figures 5 to 8. The shutter opening groove 18 is formed in said one lateral side of the cartridge body 2 and extends in the direction of insertion of the disc cartridge into the disc recording and/or reproducing apparatus shown by arrow L in Figure 6, that is along the sliding direction of the shutter member 9. The shutter opening groove 18 has a length F L , indicated by arrow F in Figure 7, between the leading edge of the cartridge body 2 in the inserting direction of the disc cartridge into the disc recording and/or reproducing apparatus and the leading edge of the slide portion 10 of the shutter member 9 when the shutter member is at the second position in which the recording/reproducing apparatus 6 and 7 are open. The mistaken insertion inhibiting groove 19 is formed in the lateral side of the cartridge body 2 opposite to said one lateral side thereof provided with the shutter opening groove 18, and extends in a direction parallel to the shutter opening groove 18. The mistaken insertion inhibiting groove 19 has a length G L indicated by the arrow G in Figure 7 from the leading edge of the cartridge body, which length G L is shorter than the length F L of the shutter opening groove 18. That is, the lengths F L and G L are related to each other by an inequality G L < F L With the above described cartridge body 2, a length B L from the bottom of the shutter opening groove 18 to the bottom of the mistaken insertion inhibiting groove 19 as indicated by arrow B in Figure 6 is selected to be shorter than a length A L of the side of the cartridge body 2 along the inserting direction indicated by arrow A in Figure 6. The length B L is selected to be shorter than a length C L of the side of the cartridge body 2 normal to the inserting direction, indicated by arrow C in Figure 6. That is, these lengths are related to one another by inequalities B L < A L B L < C L With the above described cartridge body 2, a length H L from the upper sidewall portion of the mistaken insertion inhibiting groove 19 to the upper major surface 4 a as shown by arrow H in Figure 8 is different from a length I L from the lower sidewall section of the mistaken insertion inhibiting groove 19 to the lower major surface 5 a as indicated by arrow I in Figure 8. That is, these lengths are related to each other by H L ≠ I L so that the mistaken insertion inhibiting groove 19 is slightly offset in a direction along the thickness of the cartridge body 2. With the above described disc cartridge, the shutter portions 11 and 12 of the shutter member 9 are in the first position of closing the recording/reproducing apertures 6 and 7, when the disc cartridge is not in use, to prevent intrusion of dust and dirt or the user's finger into the cartridge body 2 by means of the recording/reproducing apertures 6 and 7. When the disc cartridge is in use, it is loaded in a cartridge loading unit 51 of disc recording and/or reproducing apparatus, as shown in Figure 7. A cartridge entrance opening 51 a , providing an entrance to the cartridge loading unit 51, has a width slightly larger than the thickness of the cartridge body 2 and a length E L , indicated by arrow E in Figure 7, slightly larger than the length C L of the disc cartridge 2 in the direction normal to its inserting direction shown by arrow C in Figure 6. That is, these lengths are related to each other by an inequality C L < E L The disc cartridge is introduced into the cartridge loading unit 51, by means of the cartridge entrance opening 51 a , with the side of the cartridge body normal to the shutter member side thereof as the leading inserting side. A shutter opening pin 52 is provided upright on an inner wall of the cartridge loading unit 51 facing said one side of the cartridge body provided with the shutter opening groove 18. A mistaken insertion inhibiting pin 53 is provided upright on an inner wall of the cartridge loading unit 51 corresponding to the side of the cartridge body provided with the mistaken insertion inhibiting groove 19. The distance D L between the foremost parts of these pins 52 and 53 as shown by arrow D in Figure 7 is selected to be slightly greater than the length B L between the bottom of the shutter opening groove 18 and the bottom of the mistaken insertion inhibiting groove 19 as indicated by arrow B in Figure 6. The distance D L is however selected to be shorter than the length C L along the inserting direction of the disc cartridge. In addition, the distance D L is selected to be shorter than the length A L along the inserting direction of the disc cartridge 1. That is, the above lengths are related to one another by inequalities B L < D L D L < C L D L < A L Referring to Figure 7, the shutter opening pin 52 is positioned so that, when the disc cartridge is kept in position within the cartridge loading unit 51, the pin 52 is spaced apart from the leading edge of the cartridge body 2 by a distance corresponding to the length F L of the shutter opening groove 18 shown by arrow F in Figure 7. The mistaken insertion inhibiting pin 53 is positioned so that, when the disc cartridge is kept in position within the cartridge loading unit 51, the pin 53 is spaced apart from the leading edge of the cartridge body 2 by a distance corresponding to the length G L of the mistaken insertion inhibiting groove 19 shown by arrow G in Figure 7. The mistaken insertion inhibiting pin 53 is slightly offset in the direction of the thickness of the cartridge body 2 to mate with the mistaken insertion inhibiting groove 19. When the disc cartridge has been introduced half-way in to the entrance opening 51 a in the cartridge loading unit 51, the shutter opening pin 52 intrudes into the shutter opening groove 18. The slide portion 10 of the shutter member 9 abuts against the shutter opening pin 52 when the disc cartridge is further introduced into the interior of the cartridge loading unit 51 so that the shutter member 9 is slid from the position of closing the apertures 6 and 7 by its shutter portions 11 and 12 towards the position of opening the apertures. When the disc cartridge is still further introduced into the interior of the cartridge loading unit 51, the mistaken insertion inhibiting pin 53 intrudes into the mistaken insertion inhibiting groove 19 and the shutter member 9 is further slid to bring the shutter portions 11 and 12 to the position of opening the recording/reproducing apertures 6 and 7. At this time, information signals may be recorded or reproduced on or from the disc 1 by means of the recording/reproducing apertures 6 and 7. With the above described disc cartridge, from the formulas (3), (5) and (7), the following inequality B L < D L < C L < E L holds. Therefore, even if the mistaken inserting operation of inserting the disc cartridge from its rear side first into the cartridge loading unit 51 by means of the cartridge entrance opening 51 a should be performed, the disc cartridge will abut against the mistaken insertion inhibiting pin 53 and thereby be prevented from being introduced further into the interior of the cartridge loading unit 51. On the other hand, from the formulas (2), (6) and (8), the following inequality B L < D L < A L holds. Therefore, even if the mistaken inserting operation of inserting the disc cartridge into the cartridge loading unit 51 by means of the cartridge entrance opening 51 a from the direction normal to the correct inserting direction should be performed, the disc cartridge will abut against the mistaken insertion inhibiting pin 53 and thereby be prevented from being introduced further into the interior of the cartridge loading unit 51. In addition, with the present disc cartridge, the mistaken insertion inhibiting groove 19 is shorter in length than the shutter opening groove 18, and is offset along the thickness of the cartridge body 2. Therefore, even if the mistaken inserting operation of inserting the disc cartridge into the cartridge loading unit 51 in a topsy-turvy position should be performed, the disc cartridge will abut against the mistaken insertion inhibiting pin 53 and thereby be prevented from being introduced further into the interior of the cartridge loading unit 51. Besides, with the present disc cartridge, the mistaken insertion inhibiting groove 19 is shorter in length than the shutter opening groove 18. Therefore, the present disc cartridge need not be enlarged in size beyond the size of the disc accommodated therein for the sake of providing the mistaken insertion inhibiting groove 19, so that the disc cartridge may effectively be reduced in size. The mistaken insertion inhibiting groove 19 provided in the lateral side of the cartridge body 2 as shown in Figures 6 to 8 could also be divided into a plurality of regions of different depths. The invention is not limited to a disc cartridge in both major surfaces of which the recording/reproducing apertures 6 and 7 are formed, as in the described embodiments, but is also applicable to a disc cartridge having a recording/reproducing aperture in only one of the major surfaces of the disc cartridge. In such case, the shutter member 9 is provided only with a shutter portion associated with the recording/reproducing aperture. The invention also is not limited to a disc cartridge for an optical or magneto-optical disc but may equally be applied to other recording media for other systems, such as a flexible magnetic disc.

Claims: A disc cartridge comprising: a rectangular cartridge main body (2) containing a disc-shaped recording medium (1) and having a first aperture (7) formed in at least one major surface thereof to extend from an inner peripheral region of the disc-shaped recording medium (1) to an outer peripheral region of the disc-shaped recording medium (1), a second aperture (8) circularly formed in the same surface as the first aperture (7) and a shutter opening groove (18) to receive an external shutter opening member (52) and formed in a lateral side of the cartridge main body (2) extending parallel to the inserting direction of the disc cartridge, the shutter opening groove (18) having an upstream, considered in the inserting direction of the disc cartridge, open end to receive the external shutter opening member (52) and a downstream, considered in the inserting direction of the disc cartridge, closed end; and a shutter member (9) movably mounted with respect to the disc cartridge main body (2) to open and close the first aperture (7), characterised in that the shutter member (9) comprises a slide portion (10) supported by said lateral side of the cartridge main body (2) and a shutter portion (11) to close the first aperture (7) and the shutter member (9) is movable between a first position and a second position spaced apart in the inserting direction of the disc cartridge, the first aperture (7) being closed by the shutter portion (12) when it is positioned at the first position and being open when the shutter member (9) is positioned at the second position, wherein a mistaken insertion inhibiting groove (19) formed in the cartridge main body (2) extends parallel to the shutter opening groove (18) and is provided in the lateral side face of the cartridge main body (2) disposed opposite to said lateral side face in which the shutter opening groove (18) is formed, the mistaken insertion inhibiting groove (19) having an open end provided at the same side of the main body as the open end of the shutter opening groove (18) and the length (G) of the mistaken insertion inhibiting groove (19) being shorter than the length (F) of the shutter opening groove (18). A disc cartridge according to claim 1, wherein the mistaken insertion inhibiting groove (19) is provided at a position offset in the thickness of the cartridge main body from a middle position. A disc cartridge according to claim 1, wherein the mistaken insertion inhibiting groove (19) is divided into a plurality of regions of different depths.

Inventors: FUJISAWA HIROTOSHI, FUJISAWA, HIROTOSHI, FUJISAWA, HIROTOSHI C/O PATENTS DIVISION
Applicants: SONY CORP, SONY CORPORATION
Application year: 1992
Main classification: G11B23
IPC codes: G11B23, G11B17, G11B33