Disk cartridge

Abstract: A disk cartridge with a case comprising upper and lower shell halves (6,7) for accommodating a disk therein and a writing protection mechanism. The writing protection mechanism comprises a movable plug (311) having a main body (312) and at least one leg (313) being flush with one sliding end surface of the main body (312). A guide part (318a,318b) has a flat wall (320a,32b) and an upright wall (320a,320b) for surrounding the plug. A projection (327) cooperates with the leg (313) of the plug. A raised portion (326) of the guide part is in contact with another sliding end surface without the leg (313) of the main body (312) when the plug is properly assembled in the guide part. If the plug is inserted incorrectly, the plug stands obliquely so that the operator can detect the insertion miss of the plug.

Description: BACKGROUND OF THE INVENTION The present invention relates to a disk cartridge for encasing a recording medium such as an optical disk or a magnetic disk. In general, a magnetic disk or an optical disk is encased in a cassette case made of two shell halves. A hole into which a spindle for rotating the disk is to be inserted is formed in the center portion of the cassette case. Adjacent to the spindle hole, a head insertion hole into which a writing/reading head is to be inserted is formed in the radial direction to traverse the recording surface of the disk. The head insertion hole is opened and closed by a shutter slidingly provided on the cassette case. The front end of the cassette case has a guide portion along which is reciprocatingly moved a slider to hold the shutter for opening and closing the head insertion hole and the spindle insertion hole. The slider is in a rectangular bar-shape and holds the bent portion of the shutter. The shutter has a pair of side plate portions extending parallel to each other from the opposite sides of the bent portion thereof in order to open and close the above two holes of the cassette case. There is provided a twist coil spring between the front portion of the slider and the cassette case for urging the shutter in the direction where the two holes are closed. As mentioned above, the opposite ends of the twist coil spring are held at the front end of the slider and at the front corner of the cassette case, respectively. However, if the disk cartridge is subjected to an impact force, e.g., when it is dropped on a floor, the twist coil spring may be disconnected from the front end of the slider and the corner of the cassette case. Further, an operation for connecting the coil spring to the slider and the cassette case is troublesome, and dust may enter the cassette case when the case is dropped to move the shutter to open the two holes of the cassette case. A reading/writing device (player) for receiving the disk cartridge has a pair of drive pins for opening and closing the shutter, and, however, neither a relational movement between the drive pins and the shutter nor a charging movement of the disk cartridge into the reading/writing device is smooth. The disk is held, at its center portion, by the spindle in a floating condition in the cassette case, and, however, the disk cannot be held stably therein. Moreover, when the disk is rotationally held, the information recording surface of the disk sometimes abuts against the inner surface of the case to cause a scratch and a damage thereonto. When the disk happens to strongly abut against the edge of the head insertion hole, the information recording surface of the disk may suffer a damage. When the peripheral edge of the disk in the case strikes against the corner of a substantially circular surrounding wall, the peripheral edge thereof may suffer a damage. In addition, there is provided a writing protection mechanism in the case for preventing old information having been already recorded on the disk from being erased by recording new information onto the disk. However, there may occur a case that some parts of the writing protection mechanism are assembled upside down in the case. EP-A-0 339 651 according to the precharacterizing part of claim 1 discloses a disk cartridge having a writing protection mechanism including an erroneous-erasure prevention mechanism in form of a plug. Said plug has a block-like main body and legs extending from an end face of the main body. The case of the disk cartridge includes a guide part in which the plug can be reciprocatingly moved. A projection is provided for defining to position of the movable plug. An opening means is provided in the guide part which is opened and closed when the plug is moved from one position to the other so that a light beam can be transmitted through the opening which is detected by a sensor in order to give the information as to whether the writing on the disk should be prevented or not. SUMMARY OF THE INVENTION It is an object of this invention to provide a disk cartridge which has a writing protection mechanism capable of being easily assembled. This object is solved by the features of claim 1. Further embodiments are claimed in the sub-claims. BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings: FIG. 1 is a perspective view of a disk cartridge according to this invention; FIG. 2 is a partial perspective view of the disk cartridge when a shutter is opened; FIG. 3 is a perspective view of the disk cartridge having a writing protection mechanism; FIGS. 4(a) and (b) are two perspective views of a movable plug as viewed in two directions opposite to each other, respectively; FIGS. 5(a) and (b) are two plan views of two guide portions for the left and right plugs on the left and right sides of the lower shell half, respectively; FIG. 6 is a perspective view of the inner side of the upper shell half having two guide portions for the two protection plugs; FIG. 7 is a perspective view of the inner side of the lower shell half having two guide portions for the two protection plugs; and FIGS. 8 to 11 are four explanatory views showing a function of the writing protection mechanism, respectively. DETAILED DESCRIPTION OF THE INVENTION As shown in FIGS. 1 and 2, a disk cartridge C for encasing an optical disk, has an upper and a lower shell halves 6, 7 which are assembled in alignment with each other to form a case. The center portion of the case has a spindle insertion hole 8 and a head insertion hole 9 disposed adjacent to the spindle insertion hole 8 to receive a reading/writing head (not shown) to form an opening portion of the case. In order to open and close the opening portion, a shutter 10 is provided slidably in the left and right directions on the disk cartridge C. Reference numeral 29 indicates a writing protection mechanism. The disk cartridge C has a pair of writing protection mechanisms 29a, 29b on the right and left sides at the rear part of the cartridge C, respectively. The mechanism 29a is for an upper surface of the disk while the mechanism 29b is for a lower surface of the disk. Each of the mechanisms 29a, 29b has, as shown in FIGS. 4(a), 4(b), a movable plug 311. The plug 311 has a block-like main body and a pair of legs 313, 313 extended from one end surface of the main body in its moving direction thereof. In the two mechanisms, the same plug 311 is used in a state wherein the way of assembling them is reversed to each other. The main body 312 has two circular projections 314, 315 on its upper and lower faces. The projection 314 has a hole 316 into which a tool is inserted when the plug 311 is moved for protection of writing. The two legs 313, 313 are extended parallel to each other and have two stopping pieces 317, 317 directed outwardly at their distal ends, respectively. The writing protection mechanisms 29a, 29b have, in FIGS. 5(a), 5(b), two divided guide parts 318b, 319a for holding movably the plugs 311 on the lower shell half 7 and, in FIG. 6, two divided guide parts 319b, 318a. These guide parts are joined together to form a pair of guide parts 500, 501 (FIG. 46) in which the plugs 311 are movably held. That is, the divided guide parts 318a, 319b of the upper shell half 6 are joined together with the divided guide parts 318a, 319b, respectively, to form two rooms, one of which is composed of a pair of flat walls 320a, 320b and a pair of upright walls 322a, 322b, the other of which is composed of a pair of flat walls 321a, 321b and a pair of upright walls 323a, 323b. The upright walls 322a, 322b for one room and the upright walls 323a, 323b for the other room are opposed to each other, respectively. The upright wall 322a of the upper shell half has, at its inner surface, two projections 327, 327 for cooperating with the plug 311 for the mechanism 29b while the upright wall 323a of the lower shell half has, at its inner surface, two projections 327, 327 for cooperating with the plug 311 for the mechanism 29a. Each projection 327 has a predetermined width, and its left and right ends are engaged with the stopping projection 317 of the leg 313. That is, each plug 311 can take two positions, i.e., a non-operating position which is indicated by a solid line and an operating position which is indicated by a dotted line in FIG. 5(b). The plug 311 is selectively fixed at the two positions by the function of the two projections 317, 327 cooperating with the legs 317 of the plug 311. The flat walls 320a, 320b, 321a, 321b have four elongated openings 324a, 324b, 325a, 325b. A pair of the openings 324a, 324b of the flat walls 320a, 320b and a pair of the openings 325a, 425b of the flat walls 321a, 321b are opposed to each other, respectively, when the upper and lower shell halves 5, 7 are assembled. The two elongated openings in each pair are communicated with each other and closed to each other in response to the movement of the plugs 311. The flat wall 320b of the lower shell half 7 for the writing protection mechanism 29b and the flat wall 321b of the upper shell half 6 for the writing protection mechanism 29a are. provided with two raised portions 326, 326, respectively. In the case that each plug 311 is properly assembled in each of the mechanisms 29a, 29b, the surfaces of the main body of the plug 311, which have no legs 313 contact the flat walls 320b, 321b, respectively, and each raised portion 326 is provided on each flat wall at a position where it does not obstruct the left and right movement of each plug 311. The assembly of the writing protection mechanisms will now be explained. Before the assembly of the upper and lower shell halves 6, 7, the two plugs 311, 311 are, as shown in FIG. 8, inserted into the respective left and right divided guide parts 318b, 319a. At this time, the left movable plug 311 stands upright as shown in FIG. 8, with the projection 315 being accommodated in the opening 324b, and with the legs 313 being located over the raised portion 326. In contrast, the right movable plug 311 stands upright with the projection 314 opposite to the projection 311 being accommodated in the opening 325a and with the legs 313 being accommodated in the guiding portion 319a. At the same time, the disk is accommodated in the case. Thereafter, the upper shell half 6 is, as shown in FIG. 9, assembled onto the lower shell half 7 in such a manner that the female projections 93 of the lower shell half 7 receive the male projections 91 of the lower shell half 6, respectively (FIGS. 6 and 7). At this time, the projection 314 of the left plug 311 is received in the opening 324a of the upper shell half 6 with the legs 313 contacting the flat wall 320a while the projection 315 of the right plug 311 is received in the opening 325b with the legs 313 contacting the flat wall 321a. Thus, the writing protection mechanisms 29a, 29b are assembled. However, there is a case that the plug 311 may be inserted upside down in the guided portion 500 or 501. At that time, the legs 313 ride on the raised portion 326 of the flat wall 320b or 321b, resulting in that the plug 311 stands obliquely. If the upper shell half 6 is put on the plug 311 obliquely, the side wall 76 of the upper shell half 6 is floated from the side wall 77 of the lower shell half 77 to generate a clearance C between the two side walls 76, 77. In this manner, a worker or an operator can detect the insertion miss of the plug 311 thereby to correct the posture of the plug 311. When the two writing protection mechanisms 29a, 29b are correctly assembled, the protection mechanism 29a functions to protect writing of information onto the front surface of the disk while the mechanism 29b functions to protect it onto the back surface thereof (FIG. 3 is a perspective view of the case as viewed from the back side thereof). The plug 311 of the mechanism 29a is held in a state wherein the projection 314 having the insertion hole 316 is directed downwardly while the plug 311 of the mechanism 29b is held in a state wherein the projection 314 having the insertion hole 316 is directed upwardly (FIG. 3). When the mechanism 29b for the back surface of the disk is operated, a pin is inserted into the hole 316 of the projection 314 of the plug 311 to move the plug 311 in the left direction, as viewed in FIG. 3, while the engaging projections 317 of the legs 313 ride over the engaging projections 327. As a result, a part of the opening 325a of the upper shell half 6 is communicated with a part of the opening 325b to form a through hole into which a detection pin b provided in the player is inserted to protect its writing. The operation of the opposite mechanism 29a for the front surface of the disk surface of the disk is performed in the same manner. In this embodiment, the disk cartridge C is for a doubleside disk. However, one writing protection mechanism is used in the case of a one-side disk. The above structure of the mechanisms 29a, 29b makes it possible to easily find out the incorrect insertion of the plug by mistake.

Claims: A disk cartridge with a case (C) comprising an upper and lower shell half (6, 7) for accommodating a disk therein and a write protect mechanism for preventing new information from being recorded again onto a recorded surface of the disk onto which old information has already been recorded wherein the write protect mechanism comprises: (a) a movable plug (311) having a block-like main body (312) held movably in the case, and at least one leg (313) extending from an end face of the main body (312) in a direction where the plug (311) is moved, the leg being flush with one sliding end surface of the main body (312); (b) a guide part (318a, 318b) provided in the case for holding reciprocatingly the main body (312) of the plug (311) therein, the guide part (318a, 318b) having a flat wall (320a, 320b) and an upright wall (322a, 322b) for surrounding the plug (311), the flat wall (320a, 320b) being part of the inner wall of a shell half and surrounded by the upright wall (322a, 322b); (c) a projection (327) provided on an inner surface of the upright wall (322a, 322b) of the guide part (318a, 318b) for selectively holding the movable plug (311) at two positions while co-operating with the leg (313) of the plug (311); and (d) an opening means (324a, 324b) which is provided in the guide part (318a, 318b) so as to be opened and closed when the plug (311) is located at one position and at another position, respectively, characterised by (e) a raised portion (326) provided on one of the flat walls (320a), 320b) of the guide part (318a, 318b), the flat wall (320a, 320b) having said raised portion (326) being in contact with that end surface of the main body (312) of the plug (311) which is not flush with the leg (313) when the plug (311) is properly assembled in the guide part (318a, 318b). A disk cartridge according to claim 1 having two write protect mechanisms for preventing new information from being recorded again onto two recorded surfaces of the disk onto which old information has already been recorded, wherein the mechanisms comprise: two moveable plugs (311, 311); two guide parts (318 a, 318b; 319a, 319b) provided on left and right sides of the case; two projections (327, 327) one of which is provided on an inner surface of the upright wall of one of the upper and lower shell halves (6, 7), the other of which is provided on an inner surface of the upright wall of the other of the upper and lower shelf halves (6, 7); two opening means (324a, 324b; 325a, 325b); characterized by two raised portions (326) each provided on the flat wall (320a, 320b; 321a, 321b) of each guide part (318a, 318b; 319a, 319b), the two movable plugs (311) being accommodated in the two guide parts (318a, 318b; 319a, 319b) in a reversed manner to each other, one of the raised portions (326) being provided on the flat wall of the upper shell half (6) and the other being provided on the flat wall of the lower shell half (7). A disk cartridge according to claim 1 or 2, characterised in that the raised portion (326) has a substantially U-shaped portion having a concave portion towards a side wall of the disk cartridge and distal end portions positioned so that the legs (313) of the plug (311) are stranded on the distal end portions when the plug is improperly assembled in the guide part.

Inventors: AKIYAMA NOBORU, KAMEDA KATSUMI, AKIYAMA, NOBORU, KAMEDA, KATSUMI, AKIYAMA, NOBORU, C/O DAI NIPPON INSATSU K.K., KAMEDA, KATSUMI, C/O DAI NIPPON INSATSU K.K.
Applicants: DAINIPPON PRINTING CO LTD, DAI NIPPON INSATSU KABUSHIKI KAISHA
Application year: 1991
Main classification: G11B23
IPC codes: B29C45, G11B23