Disc cartridges

Abstract: A disc cartridge having a disc-shaped recording medium, such as an optical disc or a magneto-optical disc, rotatably housed within a main cartridge body. The disc cartridge has a main cartridge body made up of an upper cartridge half and a lower cartridge half, and a disc-shaped recording medium rotatably accommodated within the main cartridge body. A recording and/or reproducing aperture is formed in at least one of major surfaces of the main cartridge body. A shutter is mounted for movement along a sidewall section of the main cartridge body between a position closing the aperture and a position opening the aperture. There is provided an inclined portion in the aperture inclined with respect to the inserting direction of the disc cartridge.

Description: This invention relates to disc cartridges having a disc-shaped recording medium, such as an optical disc or a magneto-optical disc, rotatably housed within a main cartridge body. There has hitherto been proposed a recording disc for recording desired information signals, such as an optical disc or a magneto-optical disc. Such recording disc is usually handled as a disc cartridge in which the disc is accommodated within a main cartridge body in order to facilitate handling or to prohibit dust and dirt from becoming attached to the recording medium. Such disc cartridge has a main cartridge body 103 formed by abutting an upper cartridge half 101 and a lower cartridge half 102 to each other and a recording disc 104 rotatably accommodated in the main cartridge body, as shown in Figs.1 and 2. There is formed in the main cartridge body 103 a rectangular-shaped aperture 105 for recording/reproduction which is faced by an optical pickup unit or a magnetic head. This aperture 105 is formed for extending in a direction perpendicular to the cartridge inserting direction indicated by arrow Y in Fig.1 and may be opened or closed by a shutter 106 formed e.g., from a metal sheet or the like. The aperture 105 remains closed except during recording/reproduction. The shutter 106 is opened by a shutter opening member provided in the recording/reproducing apparatus. The techniques pertinent thereto were proposed by the present Assignee in two US patent publications which matured to US Patents Nos. 5,272,693 and 5,367,422. The size of the disc cartridge is determined not only by the size of the recording disc 104 but also by the size required of the shutter 106 and by the size of the aperture 105 which in turn is determined by the range of movement of an optical pickup 107 enclosed within the recording/reproducing apparatus (the range between the inner most position of the disc X1 and the outer most position X2 of the disc). That is, the size of the disc cartridge is determined by the size of the aperture 105 and the arrangement of the shutter 106. For example, in the case of the recording disc 104 with a diameter of 120 mm, the disc cartridge has a width W1 of 130 mm and a width W2 of 135 mm in the disc inserting direction and in the direction perpendicular thereto, respectively. Once the size of the disc cartridge is determined, the size of the recording/reproducing apparatus accommodating the disc cartridge is determined unequivocally. Thus the recording/reproducing apparatus may be reduced in size by reducing the size of the disc cartridge. Although the disc cartridge may be reduced in size by arranging part of the optical pickup 107 outside of the main cartridge body 103, the recording/reproducing apparatus itself is unchanged in size and cannot be reduced in size. For reducing the size of the disc cartridge, it is necessary to attempt this in connection with the recording/reproducing apparatus. The disc cartridge is provided with a mistaken insertion prohibiting mechanism for prohibiting insertion of the disc cartridge into the recording/reproducing apparatus in case it is attempted to introduce the disc cartridge in a mistaken direction into the recording/reproducing apparatus. Such a mistaken insertion prohibiting mechanism has been proposed in which a mistaken insertion prohibitive member adapted for being engaged in one or plural grooves formed in the side wall or the bottom plate of the main cartridge body is provided in the recording/reproducing apparatus. However, if the groove(s) for prohibiting mistaken insertion is provided in the main cartridge body, a redundant space is required for providing the groove(s). Above all, in a disc cartridge required to be reduced in thickness, limitations are placed on the width or depth of the groove(s) that can be provided thus imposing strict mounting precision on mistaken insertion prohibiting components provided in the recording/reproducing apparatus. The disc cartridge tends to be poor in strength and hence cannot withstand a large external force. In addition, provision of the groove(s) occasionally leads to surface irregularities giving rise to collision with the recording/reproducing apparatus or with the disc cartridge being introduced into the apparatus. On the other hand, the disc cartridge needs to be loaded at a pre-set loading position in the recording/reproducing apparatus in connection with the facing distance or relative disposition between the recording disc on one hand and the optical pickup or the magnetic head on the other hand. To this end, the disc cartridge has a cartridge positioning hole engaged in a pair of positioning pins provided in the recording/reproducing apparatus. The positioning pins are engaged in the cartridge positioning hole for setting the fore-and-aft and left-and-right position of the disc cartridge and the height level of the disc cartridge with respect to the recording/reproducing apparatus. However, as for the reference for the height level, there is no structural difference in actual disc cartridges, although the area in which to provide the cartridge positioning hole is prescribed in the design standards. This results in limitations imposed on surface finishing inclusive of that for a positioning portion, such as satin finishing, thus rendering it difficult to perform a slip-proof knurling for a portion gripped by the user. Furthermore, the height level at which the disc cartridge is secured is also influenced by fluctuations in the outer size of the positioning pins provided in the recording/reproducing apparatus. For example, if the positioning pins are of larger or smaller diameters due to the fluctuations in the machining precision, the height level of the disc cartridge with respect to the recording/reproducing apparatus varies due to differences in contact area between the height setting pins and the disc cartridge. EP-A-0411670 discloses a disc cartridge according to the precharacterising portion of claim 1 in which the aperture is inclined at 45° to the straight line normal to the movement direction of the shutter. In one aspect, the present invention provides a disc cartridge comprising: a main cartridge body comprising an upper cartridge half and a lower cartridge half; a disc-shaped recording medium rotatably accommodated within the main cartridge body; a recording and/or reproducing aperture formed in at least one of the major surfaces of the main cartridge body; a shutter mounted for movement along a sidewall section of said main cartridge body between a position closing the aperture and a position opening the aperture; and an inclined portion in said aperture, inclined with respect to the inserting direction of the disc cartridge; characterised in that said aperture is a disc rotating means and recording and/or reproducing aperture; the angle of inclination of the aperture passing through the center of the disc-shaped recording medium with respect to a straight line normal to the movement direction of the shutter is smaller than 45°; and the shutter is matched to said disc rotating means receiving and recording and/or reproducing aperture so as to have a smaller size and displacement than a shutter matched to an aperture at an angle of 45°. The aperture may be substantially V-shaped in plan configuration. In another aspect, the present invention provides a disc cartridge comprising: a main cartridge body made up of an upper cartridge half and a lower cartridge half; a disc-shaped recording medium rotatably accommodated within the main cartridge body; a recording and/or reproducing aperture formed in at least one of the major surfaces of the main cartridge body; an inclined portion in said aperture, inclined with respect to the inserting direction of the disc cartridge; and two shutters; characterised in that said two shutters are mounted for movement along a sidewall section of said main cartridge body between a position closing the aperture and a position opening the aperture so that the amount of shutter displacement is less than that required by a single shutter; said aperture is a disc rotating means and recording and/or reproducing aperture; and the angle of inclination of the aperture passing through the center of the disc-shaped recording medium with respect to a straight line normal to the movement direction of the shutters is smaller than 45°. Both sidewall sections of the main cartridge body extending parallel to the inserting direction are preferably of different cross-sectional configurations. One of the sidewall sections may be of outwardly convexed cross-sectional configuration. The other sidewall section may be of a substantially U-shaped cross-section. The disc cartridge insertion opening of a cartridge holder or the disc cartridge insertion opening in the front surface of the apparatus may be substantially of the same cross-sectional shape as that of the disc cartridge presented in a normal inserting direction. Embodiments of the present invention provide a disc cartridge which may be reduced in size and which renders it possible to reduce the size of the recording/reproducing apparatus employing the disc cartridge. Further, embodiments of the present invention provide a disc cartridge which can be smoothly introduced into recording/reproducing apparatus in a manner free from collision without forming the groove(s) and a recording/reproducing apparatus employing such disc cartridge. Further embodiments of the present invention provide a disc cartridge which renders it possible to render the reference position for the positioning holes definite in order facilitate distinction between a metal mold portion in need of finishing machining and another metal mold portion not in need of finishing machining and the tolerance in the outer size of the positioning pins. In embodiments of the present invention, since the aperture via which the disc cartridge faces the optical pickup device is inclined with respect to the inserting direction of the disc cartridge, the aperture may be of an increased width corresponding to the inclination of the aperture, while the disc cartridge may be reduced in size. By the inclined disposition of the optical pickup device facing the aperture, the recording/reproducing apparatus may be reduced in size. In embodiments of the present invention, both the optical pickup device for recording and the optical pickup device for reproduction may be caused to face an aperture of a disc cartridge which is substantially V-shaped in planar configuration, so that information signals may be recorded on a recording disc and reproduced therefrom immediately. On the other hand, if a disc cartridge is constituted by two shutters, and if disc cartridges accommodating recording discs of different diameters are interchangeable, it is necessary to provide a large aperture in a disc cartridge accommodating a small-sized recording disc. However, by constituting the shutter as two shutters, there is no necessity of providing a larger difference in shutter displacement, while there is no risk of the shutter being moved to outside of the main cartridge body. By constituting the shutter by two shutters, information signals may be recorded or reproduced from plural sorts of disc cartridges accommodating recording discs of different diameters. The sidewall sections parallel to the inserting direction into the recording/reproducing apparatus and facing each other may be of different cross-sectional configuration, while there are formed no grooves in the main cartridge body. Thus the disc cartridge can be smoothly inserted into and detached from the recording/reproducing apparatus without collision, while mistaken insertion in the incorrect direction may be inhibited positively. Since no grooves are formed in the main cartridge body, planar portions of the main cartridge body, such as its lateral or bottom sides, may be used as a label bonding surface for improving cartridge functions. In addition, the degree of design freedom of junction portions between the upper and lower cassette halves may be increased and the metal mold designing may be facilitated resulting in cost reduction and improved mechanical strength of the main cartridge body. With the recording and/or reproducing apparatus for loading the disc cartridge, the disc cartridge inserting opening of the apparatus may be substantially of the same shape as the cross-sectional shape of the disc cartridge in its normal inserting direction, so that, if the disc cartridge is about to be inserted from a direction different from its normal inserting direction, the disc cartridge can be positively prohibited from being introduced into the disc cartridge inserting opening. In a disc cartridge embodying the present invention, toroidal-shaped grooves 17, 18 maybe formed on the outer perimeter of the disc cartridge positioning holes 14, 15 for definitely setting the position of the reference height plane and facilitating the distinction of a metal mold portion in need of precise machining and a metal mold portion not in need of precise machining as well as allowing for the tolerance of the outer shape of the positioning pin 16. Thus it is only necessary to finish the region between the cartridge positioning hole and the toroidal-shaped groove formed therearound, while the remaining portions may remain rough as to dimensional accuracy or planarity. On the other hand, the portion of the disc cartridge gripped by a user may be easily machined by e.g., knurling by way of slip-proofing. In addition, since the toroidal-shaped groove can be formed around the disc cartridge positioning hole, any fluctuations in the outer size of the positioning pin provided in the recording/reproducing apparatus may be absorbed by the toroidal-shaped groove thus allowing the disc cartridge to be positioned highly accurately at a pre-set height and a pre-set position with respect to the recording/reproducing apparatus. Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings in which: Fig.1 is a see-through view showing the state in which an optical pickup device faces an aperture of a previous disc cartridge. Fig.2 is a bottom view showing the state of shutter closure with a previous disc cartridge. Fig.3 is a plan view showing the state of shutter closure in a disc cartridge of a first embodiment of the invention. Fig.4 is a bottom view showing the state of shutter closure in a disc cartridge of the first embodiment of the invention. Fig.5 is a front view showing the state of shutter closure in a disc cartridge of the first embodiment of the invention. Fig.6 is a side view showing the state of shutter closure in a disc cartridge of a first embodiment of the invention. Fig.7 is a see-through view showing the shutter opening state for the disc cartridge of the first embodiment with the optical pickup device facing the aperture. Fig.8 is a bottom view showing the state of shutter opening in a disc cartridge of a first embodiment of the invention. Fig.9. is a schematic enlarged cross-sectional view showing the disc cartridge of the first embodiment. Figs.10A to 10C are schematic enlarged cross-sectional views showing the interengaged state between the positioning pin and the cartridge positioning hole. Fig.11 is a perspective view showing the state of introducing the disc cartridge of the first embodiment into a cartridge holder. Fig.12 is a plan view showing a disc cartridge in which the shutter is adapted for being slid in a direction perpendicular to the disc cartridge inserting direction and showing the shutter closure state of the disc cartridge of the first embodiment. Fig.13 is a bottom view showing a disc cartridge in which the shutter is adapted for being slid in a direction perpendicular to the disc cartridge inserting direction and showing the shutter closure state of the disc cartridge of the first embodiment. Fig.14 is a front view showing a disc cartridge in which the shutter is adapted for being slid in a direction perpendicular to the disc cartridge inserting direction and showing the shutter closure state of the disc cartridge of the first embodiment. Fig.15 is a bottom view showing a disc cartridge in which the shutter is adapted for being slid in a direction perpendicular to the disc cartridge inserting direction and showing the shutter closure state of the disc cartridge of the first embodiment. Fig.16 is a plan view showing the disc cartridge of a second embodiment of the invention and showing the state of shutter closure. Fig.17 is a bottom view showing the disc cartridge of a second embodiment of the invention and showing the state of shutter closure. Fig.18 is a see-through view of the disc cartridge of the second embodiment and showing the state in which the shutter is opened and an optical pickup device faces the aperture. Fig.19 is a bottom view showing the disc cartridge of a second embodiment of the invention and showing the state of shutter opening. Fig.20 is a plan view showing a disc cartridge of a third embodiment in which a disc cartridge housing a large-diameter disc and another disc cartridge housing a small-diameter disc are configured for information recording and/or reproduction using a common recording/reproducing apparatus. Fig.21 is a bottom view showing the disc cartridge of a third embodiment of the invention and showing the state of shutter closure. Fig.22 is a front view showing the disc cartridge of the third embodiment of the invention and showing the state of shutter closure. Fig.23 is a bottom view showing the disc cartridge of the third embodiment of the invention and showing the state of shutter opening. Fig.24 is a front view showing the disc cartridge of the third embodiment of the invention and showing the state of shutter opening. A disc cartridge according to a first embodiment is arranged substantially on a diagonal line of a main cartridge body. The disc cartridge has a recording disc 1, as a disc-shaped recording medium, and a main cartridge body 4 made up of an upper cartridge half 2 and a lower cartridge half 3 for rotatably accommodating the recording disc 1, as shown in Figs.3 and 6. The recording disc 1 is exemplified by an optical disc, a magneto-optical disc or a magnetic disc. Such recording disc 1 has a chuck hub 5 of a metallic material at its center, as shown in Fig.9. The chuck hub is magnetically attracted by a spindle constituting a disc rotating driving mechanism to cause the recording disc 1 to be rotated within the inside of the main cartridge body 4. The chuck hub 5 is formed in a disc shape by working a metal sheet and has a toroidally-shaped flange 6 at an upper outer rim thereof. This flange 6 is supported by a retainer 8 formed on the outer rim of a cylindrical rib 7 formed on the inner wall surface of the upper cartridge half 2 for being protruded into the inside of the main cartridge body 4. During the time other than the recording/reproducing time, the flange 6 is supported by the retainer and, during the recording/reproducing time, the recording disc 1 is lifted by the spindle to annul the state of engagement between the flange and the retainer. The recording disc 1 has a center opening 9 passed through by a centering pin, not shown, which is provided at the center of the spindle. The center opening 9 is a small-sized circular through-hole extending along the thickness of the recording disc 1. The main cartridge body 4 is made up of rectangular-shaped upper and lower cartridge halves 2 and 3 dimensioned to be large enough to rotatably accommodate the recording disc 1, as shown in Figs.5 and 6. These upper and lower cartridge halves are abutted to each other to constitute a thin casing. The major surface of the upper cartridge half 2 has a label surface 10 for printing or bonding a label, as shown in Fig.3. The major surface of the lower cartridge half 3 has an aperture 11 which is faced by disc rotating driving means and an optical pickup device, enclosed within the recording/reproducing apparatus, as shown in Fig.4. The aperture 11 is dimensioned so as to be large enough to be faced by at least the disc rotating and driving means and the optical pickup and is formed at an angle relative to the cartridge inserting direction indicated by arrow Y in Fig.3, beginning from the center of the recording disc 1. That is, the aperture 11 is passed through the center 0 of the recording disc 1 and is inclined at an angle  smaller than 45° with respect to a straight line B perpendicular to the movement direction of the shutter 12 indicated by arrow A in Fig.3. The angle of inclination  of the aperture 11 is set so as to be smaller than 45° in order to reduce the size of the disc cartridge while maintaining the maximum window opening space, as shown in Fig.3. Although inherently the angle of inclination  of 45° is most desirable, the angle less than 45° is actually desirable in view of the size and amount of displacement of the shutter 12 or the size of the optical pickup device. If the aperture 11 is inclined in this manner, the aperture 11 may be selected to be larger in an amount corresponding to the angle  than the aperture of the disc cartridge of the same shape shown in Fig.1 extending in a direction perpendicular to the cartridge inserting direction. Stated differently, the disc cartridge itself may be increased in an amount corresponding to the angle  for the same size of the aperture 11. In this case, if the optical pickup device 13 is moved between an inner most radial position X1 and an outer most radial position X2 of a recording/reproducing area in the recording disc 1, there is no risk of the optical pickup device 13 being moved to outside the main cartridge body 4. That is, the recording/reproducing apparatus as well as disc cartridge may be reduced in size. For the outer size of the disc cartridge 1 of Fig.1 of W1 = 130 mm and W2 = 135 mm, as mentioned hereinabove, the outer size of the disc cartridge of the present embodiment is W1 = 130 mm and W2 = 130 mm. That is, by employing the inclined aperture 11, the width W2 in a direction perpendicular to the cartridge inserting direction may be reduced by as much as 5 mm. The lower cartridge half 3 has a pair of disc cartridge positioning holes 14, 15 for setting the loading position of the disc cartridge with respect to the recording/reproducing apparatus, as shown in Fig.4. The disc cartridge positioning holes 14, 15 are provided towards a lateral sidewall section 4b opposite to a lateral sidewall section 4a as the disc cartridge inserting side, and are elongated and circular in shape, respectively. The holes 14, 15 are so contoured for absorbing an error between the distance between the cartridge positioning holes 14, 15 and the distance between the positioning pins of the recording/reproducing apparatus or distance errors caused by ambient temperature. These positioning holes 14, 15 are adapted for being engaged by a positioning pin 16 provided in the recording/reproducing apparatus shown in Fig.10A. The loading position of the disc cartridge with respect to the recording/reproducing apparatus is determined by the positioning pin 16 engaged in the positioning holes as shown in Fig.10B. The positioning pin 16 also performs the role of setting the height level of the disc cartridge with respect to the recording/reproducing apparatus. Thus the portion of the disc cartridge contacted with the positioning pin 16 serves as the reference height plane and hence needs to be an extremely planar surface as compared to other portions. In the present embodiment, toroidal -shaped grooves 17, 18 are formed on the outer perimeter of the disc cartridge positioning holes 14, 15 for definitely setting the position of the reference height plane and facilitating the distinction between a metal mold portion in need of precise finishing machining and a metal mold portion not in need of precise finishing machining, as well as allowing for the tolerance of the outer shape of the positioning pin 16. These grooves 17, 18 are formed at such positions in which the outer edge of the positioning pin 16 is within the range of the grooves 17, 18 both when the outer size of the positioning pin 16 is at the minimum end of dimensional tolerance, with the diameter of the pin 16 being then D1, and when the outer size of the positioning pin 16 is at the maximum end of dimensional tolerance, with the diameter of the pin 16 being then D2. That is, the positioning pin 16 is configured to be contacted only with the toroidal-shaped height reference plane between the disc cartridge positioning holes 14, 15 and the grooves 17, 18 defined around the holes 14, 15. By forming the grooves 17, 18 on an outer peripheral portion of the disc cartridge positioning holes 14, 15, the position of the reference height plane can be clearly set, while demarcation between the finishing machining for the metal mold which need to be precise and that which is not in need of being precise can be set. The result is that the portion of the metal mold corresponding to the reference height plane needs to be machined with high precision while the remaining portion needs to be machined only roughly. In addition, since the grooves 17, 18 are formed within the range of the dimensional tolerance of the outer size of the positioning pin 16, there is no risk of the positioning pin 16 being contacted with portions other than the reference height plane, thus allowing the disc cartridge to be positioned at a precisely set height position. The main cartridge body 4, made up of the upper cartridge half 2 and the lower cartridge half 3, is provided with a shutter 12 adapted for opening and closing the aperture 11. The shutter 12 is formed as a unitary body by e.g., injection molding a resin material, such as plastics, and is dimensioned to close the aperture 11 formed in the obliquely extending direction. The shutter 12 is mounted for movement along a lateral sidewall section 4c of the main cartridge body 4 extending parallel to the direction indicated by arrow A in Fig.4. That is, the shutter 12 is configured to be movable between a position of closing the aperture 11 shown in Fig.4 and a position of opening the aperture 11 for laying the recording disc 1 to outside, as shown in Fig.8. For moving the shutter 12, the shutter 12 has its one lateral side retained by a shutter retainer 19 provided in the lower cartridge half 3 in order to assure stabilized shutter movement. The disc cartridge carrying the shutter 12 is different in cross-sectional shape of the sidewall sections 4c and 4d extending parallel to the cartridge inserting direction for prohibiting insertion in the mistaken direction of the disc cartridge into the inside of the recording/reproducing apparatus. That is, the sidewall section 4c provided with the shutter 12 is of an outwardly convex arcuate form, while the opposite sidewall section 4d is of a substantially U-shaped cross-section. Correspondingly, the opening shape of a disc cartridge insertion opening 21 provided in a front panel 20 on the front side of the recording/reproducing apparatus is substantially of the same shape as the transverse cross-section of the disc cartridge in the normal inserting direction. Thus, when the disc cartridge is introduced into the disc cartridge inserting opening 21 in the normal direction, the disc cartridge is held within a cartridge holder 22 provided within the recording/reproducing apparatus. Conversely, if the disc cartridge is about to be introduced in the inverted position, the main cartridge body 4 collides against the rim of the opening edge of the disc cartridge inserting opening 21 and cannot be introduced further thus achieving the prevention of mistaken insertion. Similar effects may be achieved by providing a similarly contoured disc cartridge inserting opening in the cartridge holder 22. Since the mistaken insertion of the disc cartridge into the recording/reproducing apparatus is prohibited by the outer shape of the disc cartridge, there is no necessity of providing a groove for prevention of mistaken insertion in the sidewall section of the cartridge main body 4. This increases the degree of designing freedom for the upper and lower cartridge halves 2, 3 and facilitates metal mold designing while preventing the occurrence of troubles caused e.g. by the moving parts being caught by the grooves during the insertion of the disc cartridge. While the above description has been made of a single-sided disc, the double-sided disc may also be handled if the rectangular-shaped disc cartridge inserting opening 21 of the front panel 20 is used and a switch or a photosensor is provided at a position registering with the both sidewall sections of the disc cartridge for enabling discrimination between the front and back sides of the disc. While the foregoing description has been made of a disc cartridge in which the shutter 12 is movable in a direction parallel to the direction of insertion Y of the disc cartridge, similar effects may also be achieved by mounting the shutter 12 for movement in a direction perpendicular to the cartridge inserting direction Y. That is, as shown in Figs.12 and 15, the shutter 12 is rotated 90° towards left and the shutter 12 is configured to be slidable in a direction perpendicular to the cartridge inserting direction, that is in a direction shown by arrow A in Fig.13. The construction of the disc cartridge is otherwise the same as that of the previously described disc cartridge. A second embodiment of the disc cartridge is now explained. The disc cartridge of the present second embodiment employs a shutter which is substantially V-shaped in plan configuration. In the present disc cartridge, the parts or components which are similar to those of the first embodiment are denoted by the same numerals and the corresponding description is omitted for clarity. The present disc cartridge differs from the disc cartridge of the previous first embodiment in that, although the shape of the upper cartridge half 2 remains the same, the shape of the aperture 23 of the lower cartridge half 3 is substantially V-shaped in plan configuration, as shown in Figs.16 to 19. The apex portion of the V-shape of the aperture 23 is of a width sufficient to be faced by a spindle, while the aperture portions extending obliquely from the apex portion towards both lateral sides are formed as an aperture of a width sufficient to be faced by optical pickup devices 25, 26 moved between the inner and outer rim portions of the recording disc 1. In addition, similarly to the aperture 11 of the disc cartridge of the first embodiment, the aperture portions of the V-shaped aperture extending towards both lateral sides are passed through the center O of the recording disc 1 and inclined at an angle  smaller than 45° with respect to a straight line B perpendicular to the direction of movement of the shutter 24, as indicated by arrow A in Fig.19. The V-shaped aperture 23 is configured so that it is confronted at its one side relative to the apex portion by the recording optical pickup device 25 and at its opposite side relative to the apex portion by the reproducing optical pickup device 26, as shown in Fig.18. That is, with the present disc cartridge, information signals are recorded by the recording optical pickup device 25 and the information signals thus recorded are immediately reproduced by the reproducing optical head device 26. On the other hand, the shutter 24 for opening and closing the V-shaped aperture 23 is formed as a substantially flat V-shaped plate sized to close the aperture 23 and is configured to be movable along both sidewall sections 4c, 4d extending parallel to the disc cartridge inserting direction Y. Since the aperture 23 of the disc cartridge of the present embodiment is substantially planar in plan configuration, the disc cartridge itself may be reduced in size. In addition, the recording optical pickup device 25 and the reproducing optical pickup device 26 may be enclosed within the recording/reproducing apparatus for recording and reproducing information signals on or from the recording disc 1 substantially simultaneously. A disc cartridge of a third embodiment, which is now described, is an interchangeable disc cartridge in which recording/reproduction may be achieved with the same recording/reproducing apparatus on or from two or more disc cartridges accommodating recording discs of different diameters. With the present disc cartridge, there is provided an obliquely extending aperture which may be opened and closed by two shutters. Fig.20 shows a first disc cartridge 28 accommodating a recording disc 27 with a diameter of 120 mm and a second disc cartridge 30 accommodating another recording disc 29 with a diameter of 80 mm. The first disc cartridge 28 has an aperture 31 which is formed for extending obliquely on a substantially diagonal line of the main cartridge body under the same conditions as those of the disc cartridge of the first embodiment. The second disc cartridge 30 also has an aperture 32 of a broader width at the same position and with the same opening width as the aperture 31 of the first disc cartridge 28. If, with the second disc cartridge 30 having an outer size smaller than the first disc cartridge 28, the aperture 32 is about to be opened or closed by a sole shutter dimensioned to close the aperture 32, the amount of shutter displacement becomes larger so that the shutter is moved outside the main cartridge body. Thus the shutter is constituted by two shutters 33, 34, for prohibiting the shutter from being moved outside the main cartridge body and also for reducing the amount of shutter displacement. The first shutter 33 and the second shutter 34 are dimensioned to conjointly close the aperture 32 as shown in Figs.21 and 22 illustrating the closed state of the aperture 32. The second shutter 34 is positioned inwardly of the first shutter 33, that is towards the disc cartridge side, and is partially overlapped with the first shutter. These shutters 33, 34 have their one ends retained by a shutter retainer 36 provided on the lower cartridge half 35, while having opposite side shutter slide portions 37, 38, bent towards the sidewall section of the disc cartridge, configured for being moved along slide sections 39, 40 provided on the lower cartridge half 35, so that the shutters 33, 34 may be moved between the position of closing the aperture 32 and the position of opening the aperture 32, as shown in Fig.21. The shutters 33, 34 are provided only on the lower cartridge half 35, without being provided on the upper cartridge half 47, as shown in Fig.22. The shutter slide portion 37 of the first shutter 33 is moved along the slide section 39 provided on the sidewall section of the lower cartridge half 35 as shown in Figs.23 and 24. On the other hand, the shutter slide portion 38 of the second shutter 34 is moved along the slide section 40 of the lower cartridge half 35 provided at a position lower by one step than the slide section 39 along which the first shutter 33 is moved. When the aperture 32 is closed by the shutters 33, 34, neither the first shutter 33 nor the second shutter can be moved. That is, the first shutter 33 has a shutter lock hole 41 formed as a rectangular-shaped opening in the shutter slide section 37 so that the first shutter cannot be moved in the direction of closing the aperture 32 nor in the direction of opening the aperture 32 by a shutter lock pawl 43 of a shutter lock member 42 provided on the lower cartridge half 35 being engaged in the shutter lock hole 41. On the other hand, the second shutter 34 has a shutter lock hole 44 which is similarly formed as a rectangular hole in the slide shutter section 38, as shown in Fig.22. A shutter lock pawl 45 provided on the shutter slide section 37 of the first shutter 33 is intruded into the inside of the shutter lock hole 44 for inhibiting movement of the shutter in the direction of opening the aperture 32. As for the direction of closing the aperture 32, shown in Figs.23 and 24, the second shutter 34 is contacted with a step 46 formed on the sidewall section of the lower cartridge half 35 for inhibiting movement of the second shutter in such direction. With the above-described shutters 33, 34, when the disc cartridge is introduced into the inside of the recording/reproducing apparatus, the shutter lock member 42 locking the first shutter 33 is thrust into the inside of the main cartridge body by a shutter opening member provided in the recording/reproducing apparatus for unlocking the first shutter 33. At the same time as the first shutter 33 is moved in a direction of opening the aperture 32 by the shutter opening member, the first shutter 33 is moved as it is overlapped on the second shutter 34. Ultimately, the first shutter 33 is overlapped on the second shutter 34 for opening the aperture 32, as shown in Fig.23. When the disc cartridge is to be ejected from the recording/reproducing apparatus, a shutter closure member provided in the recording/reproducing apparatus is engaged in the shutter lock hole 41 provided in the first shutter 33, so that the first shutter 33 and the second shutter 34 are moved in a direction of closing the aperture 32. The shutter lock member 42 is engaged in the shutter lock hole 41 formed in the first shutter 33 for locking the first shutter 33. The second shutter 34 is contacted with the step 46 provided on the lower cartridge half 35 at the same time as the shutter lock pawl 45 is engaged in the shutter lock hole 44 for locking the second shutter 34. As a result, the aperture 32 is closed by the first shutter 33 and the second shutter 34. Although the present embodiment is directed to a single-sided disc cartridge, similar effects may be realized with a double-sided disc cartridge having apertures in both sides, that is in the upper and lower cartridge halves.

Claims: A disc cartridge comprising: a main cartridge body (4) comprising an upper cartridge half (2) and a lower cartridge half (3); a disc-shaped recording medium (1) rotatably accommodated within the main cartridge body (4); a recording and/or reproducing aperture (11, 23) formed in at least one of the major surfaces of the main cartridge body (4); a shutter (12, 24) mounted for movement along a sidewall section of said main cartridge body between a position closing the aperture (11, 23) and a position opening the aperture (11, 23); and an inclined portion in said aperture (11, 23), inclined with respect to the inserting direction (Y) of the disc cartridge; characterised in that said aperture (11,23) is a disc rotating means and recording and/or reproducing aperture; the angle of inclination of the aperture (11, 23) passing through the center (O) of the disc-shaped recording medium (1) with respect to a straight line normal to the movement direction (A) of the shutter (12, 24) is smaller than 45°; and the shutter is matched to said disc rotating means receiving and recording and/or reproducing aperture so as to have a smaller size and displacement than a shutter matched to an aperture at an angle of 45°. A disc cartridge as claimed in claim 1, wherein said aperture (23) is substantially V-shaped in plan configuration. A disc cartridge (30) comprising: a main cartridge body made up of an upper cartridge half and a lower cartridge half; a disc-shaped recording medium (29) rotatably accommodated within the main cartridge body; a recording and/or reproducing aperture (32) formed in at least one of the major surfaces of the main cartridge body; an inclined portion in said aperture (32), inclined with respect to the inserting direction of the disc cartridge (30); and two shutters (33, 34); characterised in that said two shutters are mounted for movement along a sidewall section of said main cartridge body between a position closing the aperture (32) and a position opening the aperture (32) so that the amount of shutter displacement is less than that required by a single shutter; said aperture (11,23) is a disc rotating means and recording and/or reproducing aperture; and the angle of inclination of the aperture (32) passing through the center (O) of the disc-shaped recording medium (29) with respect to a straight line normal to the movement direction of the shutters (33, 34) is smaller than 45°. A disc cartridge as claimed in any preceding claim wherein, both sidewall sections (4c, 4d) of said main cartridge body parallel to the inserting direction of the disc cartridge are of different cross-sectional configurations. A disc cartridge as claimed in claim 4, wherein one of said sidewall sections (4c) is of outwardly convex cross-sectional configuration. A disc cartridge as claimed in claim 5, wherein the other sidewall section (4d) is of substantially U-shaped cross-sectional configuration. Apparatus comprising a disc cartridge as claimed in any one of claims 4 to 6 and recording/reproducing apparatus therefor, wherein a disc cartridge insertion opening of a cartridge holder (22) of the recording/reproducing apparatus, or a disc cartridge insertion opening (21) in a front surface (20) of the recording/reproducing apparatus, is of substantially the same cross-sectional shape as that of the disc cartridge presented in its normal inserting direction. A disc cartridge as claimed in any one of claims 1 to 6, including a cartridge positioning hole (14, 15), formed in a surface of the main cartridge body, for engaging a positioning pin (16) of a recording/reproducing apparatus; and a toroidal-shaped groove (17, 18) formed in said surface around and spaced from the outer periphery of the positioning hole (14, 15).

Inventors: IMAIZUMI SAKAE, NAKAGAWA TOMIHIRO, TEJIMA KEISUKE, YAMASHITA KEITARO, IMAIZUMI, SAKAE, NAKAGAWA, TOMIHIRO, TEJIMA, KEISUKE, YAMASHITA, KEITARO, IMAIZUMI, SAKAE, C/O INTELLECTUAL PROP. DIV., NAKAGAWA, TOMIHIRO, C/O INTELLECTUAL PROP. DIV., TEJIMA, KEISUKE, C/O INTELLECTUAL PROP. DIV., YAMASHITA, KEITARO, C/O INTELLECTUAL PROP. DIV.
Applicants: SONY CORP, SONY CORPORATION
Application year: 1995
Main classification: G11B23
IPC codes: G11B23