Disc Cartridge

Abstract: A guide portion (G) is provided in a front edge of a disc cartridge in an insertion direction to a recording and reproducing apparatus. A slider (14) is slidingly engaged with the guide portion. A shutter (6)is fixed to the slider. Head insertion holes (5) and spindle holes (4) formed in the cartridge case are opened or closed by the shutter (6). A generation of friction or wear chips due to the sliding contact between the shutter (6) and cartridge (1) may be prevented.

Description: The present invention relates to a disc cartridge according to the preamble of claim 1. In general, a magnetic disc or an optical disc is encased in a cassette case made of two shell halves. A hole into which a spindle for rotating the disc is to be inserted is formed in a central portion of the cassette case. Head insertion holes into which a write and read head is to be inserted is formed in the cassette case so as to extend in the radial direction to traverse the recording surface of the disc. Such a disc cartridge is shown in, for example, Japanese Utility Model Unexamined Publication No. 62-168176. This cartridge has a shell for encasing the disc. A spindle hole is formed in the central portion of the shell half. A hub formed in the central portion of the disc is located in the spindle hole of each shell half. The spindle of the recording and reproducing apparatus is to be located at the hub which is sucked by a turntable. The head insertion holes are formed on an insertion side of the cartridge relative to the recording and reproducing apparatus. A write and read head (pickup head) is inserted into one of the head insertion holes. The head insertion holes are closed and opened by sliding movement of the shutter. The shutter is bent at its intermediate portion so as to extend to the top and bottom of the cartridge to cover the head insertion holes and two spindle holes. On the insertion side of the cartridge into the recording and reproducing apparatus, the shutter is slidingly moved along a guide portion of the cartridge front edge to open and close the insertion holes and the spindle holes. Also, the sliding movement of the shutter of the conventional cartridge is not smooth, which would lead non-smooth sliding contact between the shell and the shutter. EP 0 255 185 A1 discloses a disc cassette comprising an enclosure and a shutter which is uniformly and easily movable and which can easily be mounted on the enclosure. This is achieved by rigidly connecting the shutter to a slide 11 which is slidably connected to the enclosure by parallel guide means. This document further discloses an omega type spring which acts on the slide. This spring has a first straight arm connected to the tip end of the slide, and a second arm comprising a first extension portion extending substantially tangentially from the coil portion of the spring, and a second portion bent from the first extension portion, an a distal end connected to the front edge of the disc cartridge. It is the object of the invention to provide a disc cartridge which enables a smooth and reliable movement of its shutter. This object is solved by the subject matter of claim 1. In the following detailed descriptions of preferred embodiments of the invention are provided with reference to the accompanied figures, wherein Fig. 1 is a perspective view showing a disc cartridge according to the invention; Fig. 2 is a perspective view showing a shutter and a slider used in the cartridge shown in Fig. 1; Fig. 3 is a perspective view showing a guide portion shown in Fig. 1; Fig. 4 is a perspective view showing the disc cartridge from which the slider has been removed; Fig. 5 is a partial perspective view showing an end portion of the slider shown in Fig. 1; Fig. 6 is another partial perspective view showing the end portion of the slider; Fig. 7 is a partial cross-sectional view showing the end portion of the slider; Fig. 8 is a partial plan view showing a corner portion of the cartridge; Fig. 9 is a perspective view showing a return coil spring shown in Fig. 8; Fig. 10 is a side elevational view showing the received condition of the return coil spring; and Fig. 11 is a view showing the state of the return coil spring when the shutter is opened; In Fig.1, a cartridge C for an optical disc according to the invention has a cartridge case 1 which is composed of upper and lower shell halves 2 and 3 in alignment with each other. A spindle hole 4 is formed in the central portion of the case 1, the spindle hole 4 being integrally formed with a head insertion hole 5. A lower end of the shutter 6 is guided by a retainer plate 6. Double writing preventing portions 9a and 9b are provided on the right and left sides on the rear edge side in the insertion direction to the recording and reproducing apparatus for the cartridge C. A shutter 6 is bent at the front edge of the case 1 to extend to the bottom side. A return coil spring 10 is encased on the left side of the case 1, so that the shutter 6 is biased in the direction to close the holes 4 and 5. The shutter plate 6 is formed of a single metal sheet such as a stainless plate as shown in Fig. 2. A shutter 6 is provided with two planar plates 11, 11 confronted with each other and a head portion 13 defined by a connecting portion of the planar plates 11, 11. A slide portion is formed in a lower portion of each planar plate 11 so as to slidingly engage with the retainer plate 8. The head portion 13 is fixed by screws 15, 15 for covering an elongated slider 14. The screws 15, 15 are threadedly engaged with receiving holes 18, 18 of the slider 14 through openings 18, 18. An opening and closing pin receiving hole 17 into which an opening and closing pin P1 is formed on a drive side of the recording and reproducing apparatus is inserted is formed in a tail portion of the head portion 13 (Fig. 3). A receiving recess 19 is formed in the slider 14 corresponding to the opening and closing pin receiving hole 17. The opening and closing pin P1 mounted on an arm 30 as shown in Fig. 3 is engaged with the receiving recess 19. Guide grooves 21, 21 (Fig. 2 and 5) are formed in both sides of the slider 14 and are adapted to engage with guide rails 22, 22 (Fig. 2) formed in a guide portion G formed at a front edge of the cartridge C on the recording and reproducing side as shown in Fig. 3. A slanted surface 20 is formed at a front face of the slider 14. The slanted surface 20 serves to assist a smooth passage of an opening and closing pin P2 mounted on an arm 31 on the drive side of the recording and reproducing apparatus as shown in Fig. 3. When the cartridge is inserted into the recording and reproducing apparatus, one of the opening and closing pins P1 and P2 is inserted into the receiving recess 19 of the slider 14 and the receiving hole 17 of the shutter 6. When the opening and closing pin P1 moves the shutter 6 leftwardly to open the spindle holes 4 and the head insertion holes 5 as shown in Fig. 4, the other opening and closing pin P2 rides over and along the slanted surface 20 of the slider 14 so that the pins P1 and P2 cross with each other. Thus by pins P1 and P2 cross with each other. Thus, by providing the slanted surface 20 on the slider 14, a so-called disposal pin, i.e., the unnecessary opening and closing pin P2 is smoothly guided. As described above, the slider 14 is engaged with the guide portion G at the front edge of the cartridge C on the recording and reproducing apparatus side, and the shutter 6 is held to the slider 14. Therefore, when the shutter 6 is frequently moved by the opening and closing pin P1 for the opening and closing operation, the slider 14 made of plastic is engaged with a guide portion G made of plastic, so that any cut chips will not be generated by the sliding contact therebetween. Thus, there is no fear that the disc would be contaminated. Also, even if the cartridge C is protect the shutter 6. Thus, the shutter 6 is prevented effectively from being separated apart from the cartridge. At the front face of the slider 14 on which the slanted surface 20 is formed, there is formed a recess 30' as shown in Fig. 5. A slanted surface 30a is formed in an inner side of the recess 30'. A distal end 10a of the coil spring 10 is retained in a receiving portion 33 on the inner side of the slanted surface 30a. The distal end 10a of the coil spring 10 is received on the slanted surface 30a through a cutout 32 formed in a planar portion 31' of the slider 14. Also, as shown in Figs. 6 and 7, a projection 31a is formed on an inner surface of the planar portion 31' and the distal end 10a of the coil spring 10 extends through the cutout 32. The projection 31a has a slanted surface So. The projection 31a serves to smoothly guide the distal end 10a into a receiving portion 33a and simultaneously to retain the distal end 10a at the receiving portion 33a against the collision transmitted from the outside. As shown in Fig. 8, a receiving space S for the return coil spring 10 is substantially in the form of a rectangular shape. As shown in Figs. 8 and 9, the coil spring 10 is composed of a coiled elastic portion 41, and two arms 42 and 43 extending laterally from the coiled portion 41. The arm 43 is composed of a first extension portion 43a extending substantially along a peripheral wall W1 formed around a circumferential edge of the optical disc (not shown) in the case 1, and a second extension portion 43b extending from the first extension portion 43a along the front edge wall W2 of the cartridge. The second extension portion 43b is composed of a longitudinal portion 43b1, a laterally extending portion 43b2 bent from the portion 43b1 in the horizontal direction, and a retainer portion 43b3 engaged with an end portion of the slider 14 and bent at a right angle from the laterally extending portion 43b2 for guiding the shutter 6. Also, the arm 42 is composed of a third extension portion 42a extending toward the front wall of the cartridge from the coiled portion 41, and a fourth extension portion 42b extending generally in the lateral direction from the third extension portion 42a. The fourth extension portion 42b is composed of crest-shape forming portions 42b1 and 42b2 for forming the crest shape on the left side in Fig. 9 extended from the third extension portion 42a, a jump portion 42b3 extending toward the front wall W2 of the cartridge from the crest-shape forming portion 42b2, and a retainer portion 42b4 extended from the jump portion 42b3 and curved at a right angle for engaging with a end wall W3 of the cartridge. Fig. 10 is a view as viewed in the direction indicated by the arrow A in Fig. 8. In Fig. 10, the slider 14 is moved along the guide rails 22, 22 of the halves 2, 3. An opening 0 is formed in a front face of the upper and lower halves 2 and 3. The coil spring 10 is inserted from the opening 0 while the one end of the spring 10 is being engaged with the side wall W3 by the end of the slider 14 in the final step of the assembling operation. In other words, receiving portions 33, 33b for detachably receiving the spring retainer portions 42b4 and 43b3 are formed in the slider end portion and the side wall W3, respectively. When the shutter 6 opens and closes the head insertion holes 5, as shown in Fig. 11, the central portion of the coiled portion 41 of the spring 10 is reciprocatingly moved along a locus B. In other words, the coiled portion 41 is moved along the circumferential wall W1 without colliding against the latter W1. Also, since the arms 42 and 43 are bent as described above, the coiled portion 41 is swayed in the lateral direction in accordance with the leftward movement of the slider 14, so that the reduction in opening angle óo (see Fig. 8) defined by the arms 42 and 43 may be kept at a low level even if the distance of the lateral movement of the slide 14 is increased. Accordingly, there is no fear that the spring resistance would be abruptly increased in accordance with the movement of the slider 14. Thus, the smooth movement of the shutter 6 is ensured. also, because of the formation of the bent arms, even if the shutter 6 is opened to a position close to the side wall W3, there is no fear that the arm 43 would be brought into contact with the side wall W3 to hinder the movement of the slider 14. Accordingly, even if the receiving space S is relatively small, it is possible to increase the distance of the lateral movement of the shutter 6. Since the return spring 10 is structured as described above, even if the receiving space S for the return coil spring is small, it is possible to increase the movement range of the shutter, thereby making the cartridge more compact and ensuring the smooth and large opening and closing operation of the shutter. Incidentally, it is preferable that a radius r at the bent portion between the crest shaped portion 42b1 and the third extension portion 4a be in the range of 0.8 to 3 mm. When the coil spring 10 was made of SUS304WPB and the radius r was set in the above-described range, the coil spring could function normally after repeated opening and closing operations of the shutter over 100,000 times. If the radius r would be too small, the durability would be lowered, whereas if the radius r would be too large, the movement during the expansion and compression of the spring would be changed according to every spring. In the latter case, it would be difficult to control the spring property in a prescribed manner.

Claims: A disc cartridge for encasing therein a recording medium disc, said disc cartridge having a front edge to be inserted into a recording or reproducing apparatus; a shutter (6) slidably mounted on said disc cartridge for opening and closing at least one head insertion hole (5) formed in said disc cartridge, said shutter (6) including a head portion (13) slidably movable along said front edge of said disc cartridge, said head portion having opening and closing plate portions (11) extending from both sides thereof; a guide portion (G) formed in said front edge of said disc cartridge; a slider (14) slidingly guided within said guide portion (G) for supporting said shutter; and a return coil spring (10) for biasing the shutter (6) through said slider to a position where said shutter closes said head insertion hole (5); wherein said return coil spring (10) is composed of an elastic wire coiled portion (41) having two arms (42, 43) extending therefrom and is located within a corner of the disc cartridge; and wherein one of said arms (43) is composed of a first extension portion (43a) extending substantially tangentially from said coiled portion (41) and of a second extension portion (43b) bent from said first extension portion; said second extension portion (43b) comprises a longitudinal extending portion (43b1), a lateral extending portion (43b2) bent back from said longitudinal extending portion and a first retainer portion (43b3) bent in a right angle from said lateral extending portion and being connected to the tip end of the slider (14); and that the other arm (42) is composed of a third extension portion (42a) extending tangentially from said coiled portion (41) and of a fourth extension portion (42b) bent from said third extension portion, wherein the fourth extension portion comprises a distal end which is connected to the front edge of said disc cartridge. The disc cartridge according to claim 1, characterized in that the radius ( r ) of curvature of a bent portion between said third extension portion (42a) and said fourth extension portion (42b) is within a range of 0.8 to 3 mm. The disc cartridge according to claim 1 or 2, characterized in that said fourth extension portion (42b) forms a trapezoidal crest shape with the third extension portion (42a) and comprises: a jump portion (42b3) extending from the distal end of the trapezoidal crest shape, and a second retainer portion (42b4) being bent in a right angle for being connected with the front edge of the disc cartridge, wherein said second retainer portion is being extended in a direction opposite the direction of said first retainer portion (43b3) of the second extension portion. The disc cartridge according to one of claims 1 to 3, characterized in that the tip end of the slider is in the form of a projected roof (20); a guide groove (30') is formed on the under surface of the projected roof and includes a slanted surface (30a) for guiding a distal end (10a) of one arm of the return coil spring (10) to a receiving portion (33) which is located in a retraced position from the front end of the projected roof; and the distal end (10a) is received in a recess portion (33a) formed within the receiving portion (33) after being guided through a cutout (32) which is formed on the bottom wall of the slider (14). The disc cartridge according to claim 4, characterized in that a projection (31 a) is provided along the cutout (32) in the receiving portion (33) for guiding the distal end of the return coil spring (10) into the recess portion (33a) and for preventing the distal end once introduced into the recess portion from being pulled apart therefrom.

Inventors: AKIYAMA NOBORU, AKIYAMA, NOBORU
Applicants: DAINIPPON PRINTING CO LTD, DAI NIPPON INSATSU KABUSHIKI KAISHA
Application year: 1989
Main classification: G11B23
IPC codes: G11B23, G11B17