Disk cartridge

Abstract: A disk cartridge comprises: a cartridge case including an upper case, a lower case and a head inser­ tion aperture at a predetermined position; a pair of cleaning sheets respectively secured to inner surfaces of the upper and lower cases; a disk disposed rotatably between the cleaning sheets; and a resilient member disposed between at least one of the cases and associated one of the cleaning sheets, the resilient member being adapted to press a part of the cleaning sheet against a disk surface, wherein the resilient member is disposed in the vicinity of the head insertion aperture and upstream of the head inserting port in the rotating direction of the disk, thereby enhancing the effects of cleaning of the disk surfaces to be read/written by the magnetic head.

Description: BACKGROUND OF THE INVENTION The present invention relates to a disk cartridge such as a magnetic disk cartridge, an optical disk cartridge, or a magneto-optical disk cartridge, and more particularly to a disk cartridge in which an inclined portion of a resilient member is adapted to resiliently bring a part of a cleaning sheet into contact with the disk so as to clean the surface of the disk. Fig. 9 is a bottom view of an upper case with a cleaning sheet attached thereto in a conventional magnetic disk cartridge. Fig. 10 is a top plan view of a lower case with the cleaning sheet attached thereto in the magnetic disk cartridge. Fig. 11 is an enlarged cross-sectional view illustrating a state where the upper and lower cases of the magnetic disk cartridge are subjected to ultrasonic welding. Fig. 12 is an enlarged cross-sectional view of a resilient member disposed in the magnetic disk cartridge. The magnetic disk cartridge mainly comprises a cartridge case 1, a magnetic disk 2 (see Fig. 12) accommodated rotatably therein, and a shutter (not shown) supported slidably by the cartridge case 1 and adapted to open and close head insertion ports or apertures 5. The cartridge case 1 comprises an upper case 1a and a lower case 1b which are formed of a hard synthetic resin such as ABS resin. As shown in Fig. 10, an opening 4 in which a rotating and driving shaft is inserted is formed substantially in the center of the lower case 1b, and the head insertion port 5 having a rectangular shape is provided in the vicinity thereof. The upper case 1a is similarly provided with the head insertion port 5 (see Fig. 9). A plurality of protrusions 3 arranged in parallel at predetermined positions and arcuate restricting ribs 6 for restricting the accommodation position of the magnetic disk 2 are provided on an inner surface of the upper case 1a. A cleaning sheet 7 made of, for instance, a non-woven fabric formed of a mixture of rayon fibers and polyester fibers is placed in the space surrounded by the restricting ribs 6. Since the cleaning sheet 7 is thus placed, the protrusions 3 are covered with the cleaning sheet 7, and the peripheral portion of the cleaning sheet 7 is heat-bonded to the upper case 1a at a portion 9 by means of ultrasonic welding or a similar method. As shown in Figs. 10 and 12, a protruding support 10 and adhesion preventing protrusions 11 are provided on the inner surface of the lower case 1b and at a position substantially opposing the protrusions 3 of the upper case 1a. In addition, a proximal end portion 13 of a resilient member 12 formed by bending a plastic sheet into the form of a chevron is secured to the inner surface of the lower case 1b in the vicinity of the support 10 by a suitable means such as bonding or welding. The distal end portion of the resilient member 12 is provided with an inclined portion 14 which projects in such a manner as to be inclined relative to the lower case 1b. The lower case 1b is also provided with the restraining ribs 6 in the same way as the upper case 1a, and the cleaning sheet 7 is placed on the inner side thereof. Since the cleaning sheet 7 is thus placed, the resilient member 12 is covered, and most of the peripheral portion of the cleaning sheet 7 is welded or heat-bonded to the lower case 1b at the portion 9. However, a portion of the peripheral portion of the cleaning sheet 7 opposed to the opposite side ends of the resilient member 12 is not heat-bonded. As shown in Fig. 9, bosses 15 are provided in the vicinity of the four corners of the upper case 1a, and, as shown in Fig 10, cylindrical portions 16 into which the bosses 15 are inserted are provided in the vicinity of the four corners of the lower case 1b, respectively. As shown in Fig. 11, a portion 17 of allowance for welding is formed at the tip portion of each of the bosses 15, and the bosses 15 are respectively inserted into the cylindrical portions 16 with the portions 17 of allowance for fusion facing downward. Subsequently, as ultrasonic energy is supplied to contacting portions of the boss 15 and the cylindrical portion 16, the portions of allowance 17 for fusion are melted, and the tip portions of the bosses 15 are thereby bonded to the inner bottom surfaces of the cylindrical portions 16. If the disk cartridge is assembled by thus bonding together the upper case 1a and the lower case 1b as a unit, the cleaning sheet 7 on the side of the lower case 1b is partially lifted by the inclined portion 14 of the resilient member 12, as shown in Fig. 12, while a part of the cleaning sheet 7 in the upper case 1a opposed to the lifted portion is slightly pushed downwardly by the protrusions 3 provided on the upper case 1a. Consequently, the magnetic disk 2 is clamped lightly and resiliently by the upper and lower cleaning sheets 7. Then, as the magnetic disk 2 rotates, the surfaces of the disk are cleaned by the cleaning sheets 7. In cases where the resilient member 12 and the cleaning sheets 7 are used to clean the magnetic disk 2, a portion of the cleaning sheet 7 lifted most highly by the resilient member (inclined portion 14), i.e., point C in Fig. 12, has the largest cleaning effect, and this point C (which is a straight line in a plane parallel to the disk 2) is referred to as the cleaning position in this specification or description. As shown in Fig. 10, in a conventional disk cartridge, the aforementioned resilient member 12 and the like are disposed in such a manner that this cleaning point C is located in the range of 90 to 120 degrees upstream of a center line X of the head insertion port 5 in the rotating direction of the disk. With the conventional disk cartridge thus arranged, at the time when the disk cartridge is inserted into the recording and reproducing apparatus, no problem is presented when the magnetic head is brought into pressure contact with the magnetic disk 2 after the front or leading portion of the disk surface cleaned at the above-described cleaning position C has passed under the magnetic head. However, there are cases where the magnetic head is brought into pressure contact with the disk surface which has not been cleaned yet before the aforementioned cleaned front or leading portion passes below the magnetic head. If dust or the like is attached to the portion of disk surface, the dust or the like is struck against the disk surface by the colliding force of the magnetic head and consequently becomes attached more firmly thereto, making it impossible to wipe it off with the cleaning sheets 7 and resulting in a permanent error. In the case of the conventional disk cartridge, the cleaning position C is located substantially upstream of the head insertion port 5 (at a position about 90 to 120 degrees away from the center axis X of the head insertion port 5). Meanwhile, because of the simplified structure of the recording and reproducing apparatus, a recently available one is arranged such that, after insertion of the disk cartridge, the magnetic head is brought into pressure contact with the magnetic disk 2 at a relatively early timing. For that reason, if the cleaning position C is substantially separated from the head insertion port 5, it takes time until the cleaned front portion passes under the magnetic head, so that the magnetic head is brought into pressure contact with the magnetic disk 2 before that time, resulting in a fault such as the one described above. Thus, in the case of the magnetic disk cartridge, the above-described fault occurs since the magnetic head is directly brought into pressure contact with the magnetic disk 2. However, even in the case of an optical disk cartridge in which the optical head does not contact the disk, it is preferable to make the cleaned front portion of the disk pass below the optical head before the optical head accesses the disk. In addition, in the case of the conventional disk cartridge, in the state shown in Fig. 10 where it is midway in an assembly process, both portions of the cleaning sheet forwardly and rearwardly of the resilient member 12 are bonded in a state in which the cleaning sheet 7 is partially raised substantially and stretched. However, if the upper case 1a and the lower case 1b are bonded, as shown in Fig. 12, the resilient member 12 is pushed down by the protrusions 3 of the upper case 1a, so that a slacked portion is created in the cleaning sheet 7 which has been tight and creases occur. Since these creases are formed on the resilient member 12 which would have the largest cleaning effect, it is impossible to demonstrate a sufficient cleaning effect. Furthermore, if the amount of slackening of the cleaning sheet 7 is large, the state of the cleaning sheet becomes such that it is entangled in by the rotating magnetic disc 2, so that there is a drawback in that the rotational torque of the magnetic disc 2 required becomes large. Accordingly, an object of the present invention is to provide a disc cartridge which is capable of overcoming the above-described drawbacks of the prior art and demonstrating a cleaning effect positively and has high reliability in operation. Our own earlier EP-A-0 209 892 discloses a disc cartridge providing the basis for the prior art portion of claim 1. As compared therewith, the present invention, as defined in claim 1, leaves the portion of the cleaning sheet downstream of the cleaning sheet which is pushed against the disc free and unattached to the case so as to prevent the wrinkling of the sheet due to the tension in the cleaning sheet having been relaxed during assembly of the upper and lower case halves of the cartridge case. BRIEF DESCRIPTION OF THE DRAWINGS Figs. 1 to 8 illustrate a magnetic disk cartridge in accordance with an embodiment of the present invention, in which Fig. 1 is a bottom view of an upper case with a cleaning sheet attached thereto; Fig. 2 is a top plan view of a lower case with a cleaning sheet attached thereto; Fig. 3 is an enlarged to plan view of a cylindrical portion provided in a front portion of the lower case; Figs. 4 and 5 are partial cross-sectional views illustrating bonding between the cylindrical portion and a boss; Fig. 6 is an enlarged top plan view of a cylindrical portion provided in a rear portion of the lower case; Fig. 7 is a partial cross-sectional view illustrating the cylindrical portion and a boss; Fig. 8 is an enlarged cross-sectional view of a resilient member and parts adjacent thereto; Figs. 9 to 12 are diagrams illustrating a conventional disk cartridge, in which Fig. 9 is a bottom view of an upper case with a cleaning sheet attached thereto; Fig. 10 is a top plan view of a lower case with a cleaning sheet attached thereto; Fig. 11 is a partial cross-sectional view illustrating bonding between a boss and a cylindrical portion; and Fig. 12 is a cross-sectional view of a resilient member and parts adjacent thereto. DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to Figs. 1 to 8 a description will be given of an embodiment of the present invention. A magnetic disk cartridge in accordance with this embodiment differs from a conventional magnetic disk cartridge shown in Figs. 9 to 12 in the configuration of cylindrical portions 16 formed in a lower case 1b and the place of installation of a resilient member 12 and protrusions 3. First, a description will be given of the configuration of the cylindrical portions 16. As shown in Fig. 3, the cylindrical portions 16 disposed on both sides of a front portion (upper side as viewed in Fig. 2) of the lower case 1b are respectively provided with arcuate ribs 18 each disposed on the cylindrical portion 16 and having an opening angle of about 100 degrees or more toward its side opposed to an area where a magnetic disk 2 rotates. Meanwhile, as shown in Fig. 6, each of the cylindrical portions 16 disposed on both sides of a rear portion (lower side as viewed in Fig. 2) of the lower case 1b is provided with a slit 19 in a peripheral wall thereof on the side not facing the rotating area of the disk, the slit 19 being provided down to the vicinity of a foot of the peripheral wall. As shown in Figs. 4 and 7, an annular portion 17 of allowance for fusion is formed at a tip portion of each boss 15 of the upper case 1a. When the cases 1a and lb are bonded together, the front bosses 15 are respectively inserted into the corresponding front cylindrical portions 16, as showing Fig. 4, and ultrasonic energy is supplied between the boss 15 and the cylindrical portion 16 into effect bonding. At this time, however, since the upper surface of the arcuate rib 18 is brought into contact with the inner surface of the upper case 1a, as shown in Fig. 5, the air containing fine particles of resin do not flow in the direction of the rotating area of the disk, but flows to the opposite side to the rotating area of the disk, as shown in the arrow. In addition, as shown in Fig. 7, the rear boss 15 is inserted into the corresponding rear cylindrical portion 16, and ultrasonic energy is supplied between the boss 15 and the cylindrical portion 16 to effect bonding. At that time, the flowing direction of the air containing fine particles of resin is restricted to be flown through the slit 19 in such manner as to be directed to the opposite side to the rotating area of the disk, as shown by the arrow in the drawing. Referring now to Figs. 1, 2 and 8, a description will now be given of the places of installation of the resilient member 12 and protrusions 3. As shown in Fig. 2, a plurality of protrusions 11 each having a protruding length of 12.5 mm and a protruding support 10 having a protruding length of 20 mm and extending in a direction perpendicular thereto are provided on the inner surface of the lower case 1b in the vicinity of the head insertion aperture or port 5. In addition, the resilient member 12 formed by bending a plastic sheet made of a polyester sheet with a thickness of 12.5 µm into the shape of a chevron is secured to be resiliently extended at a region above the support 10 and the protrusions 11 as in the case of a conventional apparatus. A portion of a cleaning sheet 9, which is formed of a non-waven fabric of such as rayon fibers or polyester fibers and having a thickness of about 300 µm and which extends from the vicinity of the resilient member 12 to its edge opposed to the head insertion port 5 is not secured by heat bonding and is made free. For this resilient member 12, a sponge body, a metallic sheet, or the like may be used instead of a plastic sheet. In addition, as shown in Fig. 1, a plurality of the protrusions 3 each having a height of about 0.4 mm are provided on the inner surface of the upper case 1a at a position opposed to the resilient member 12, i.e., in the vicinity of the head insertion port 5. Accordingly, if the upper case 1a and the lower case 1b are bonded together to assemble a magnetic disk cartridge, the cleaning sheet 7 on the side of the lower case 1b is partially raised by the inclined portion 14 of the resilient member 12, as shown in Fig. 8. At the same time, the raised portion is slightly pushed downwardly by the protrusions 3 on the side the upper case 1a. As a result, the magnetic disk 2 is lightly and resiliently clamped by the upper and lower cleaning sheets 7, 7. As illustrated in Fig. 8, the edge portion of the cleaning sheet 7 on the side of the lower case 1b which is opposed to the head insertion port 5 is not fixed to the lower case 1b and is set free, as described above. Even if the edge portion of the cleaning sheet 7 is thus set free, since the rotating direction of the magnetic disk 2 is always the same, the edge portion of the cleaning sheet 7 does not get turned up. The cleaning position C of the disk cartridge in accordance with this embodiment is located within 60 degrees upstream of the central axis A of the head insertion port 5 in the rotating direction of the disk, as shown in Fig. 2. It would be preferable to bring the cleaning position C as close to the head insertion port 5 as possible since the probability of having cleaned the portion of the magnetic disk 2 opposed to the magnetic head becomes high before the disk cartridge is inserted in the recording and reproducing apparatus and the magnetic head comes into contact with the magnetic disk 2. However, if a part of the resilient member 12 projects from the head insertion port 5, it will undesirably serve as a hindrance at the time of recording and reproduction, so that it is necessary to bring the resilient member 12 close to the head insertion port 5 to the extent that it does not project therefrom. Hence, it suffices if the cleaning position C is designed to fall within the range of an angle ϑ, as show in Fig. 2. In the foregoing embodiment, as shown in Fig. 2, the forward edge of the resilient member 12 and the edge of the cleaning sheet 7 opposed to the head insertion port 5 are not set parallel with each other, but the forward edge of the resilient member 12 and the aforementioned edge of the cleaning sheet 7 may be set parallel by changing the layout and/or configuration of the resilient member 12. In addition, in the foregoing embodiment, although the protrusions are provided on the upper case 1a and the resilient member 12 is secured to the lower case 1b, the resilient member 12 and the protrusions may conversely be provided on the upper case 1a and the lower case 1b, respectively. In addition, the protrusions 3 may not necessarily be provided. Moreover another resilient member may be provided instead of the protrusions 3. Furthermore, in the foregoing embodiment, a description has been given of the case of a magnetic disk cartridge, the present invention is applicable to an optical disk cartridge, a magneto-optical disk cartridge, or other types of disk cartridge. Since the present invention is arranged as described above, even if a portion of the cleaning sheet lifted by a resilient member becomes slackened by bonding between the upper case and the lower case, the cleaning sheet extends to the downstream side by the slackened portion, because the portion of the cleaning sheet located downstream of the resilient member in the rotating direction of the disk is set free. Therefore the creases are not formed. Furthermore, since the resilient member is provided in the vicinity of the head insertion port, the cleaned tip portion of the disk is capable of passing below the head within a very short period of time after the disk starts rotating. for this reason, even in the case of a recording and reproducing apparatus in which the time until the disk is accessed by the head after insertion of the disk cartridge into the recording and reproducing apparatus is short, the cleaned disk surface can be made to face the head before the disk is accessed by the head. Thus, it is possible to provide a disk cartridge which is capable of demonstrating a cleaning effect positively and is highly reliable in operation.

Claims: A disc cartridge comprising: a cartridge case including an upper case (1a), a lower case (1b) and a head insertion aperture (5) at a predetermined position in each of said upper and lower cases (1a,1b); a pair of cleaning sheets (7,7) made of a non-woven fabric, one of said sheets (7,7) being secured to the inner surface of said upper case (1a), the other one of said sheets being secured to the inner surface of said lower case (1b); a disc (2) having respective surfaces disposed rotatably between said cleaning sheets (7,7); and at least one resilient member (12) disposed between a corresponding one (1b) of said cases (1a,1b) and a related one (7) of said cleaning sheets (7,7), said resilient member (12) being adapted to provide a cleaning position (C) by pressing said related cleaning sheet (7) to force said cleaning sheets (7,7) into direct contact with said surfaces of said disc (2), said resilient member (12) being positioned within 60° upstream of a central axis (X), extending radially from the centre of the case to the centre of said heat insertion aperture (5), relative to the rotating direction of said disc (2) such that said cleaning position (C) is provided by an inclined portion (14) of said resilient member (12) located within said 60°, characterised in that a portion (Figure 8) of said related cleaning sheet (7) located downstream of said resilient member (12) in the rotating direction of said disc (2) is free and non-adhesively associated with said corresponding case (1b). A disc cartridge according to claim 1, wherein said resilient member is constituted by a resilient sheet (12) including a proximal end portion (13) secured to said one case (1b) and an inclined portion (14) rising obliquely with respect to an inner surface of said one case (1b), said inclined portion (14) being arranged in a direction crossing relative to the rotating direction of said disc (2). A disc cartridge according to claim 2, wherein said resilient sheet is constituted by a plastic sheet (12), and a projection (10) is provided at a position on the inner surface of said case where said resilient sheet is secured to contact said inclined portion (14) of said resilient sheet (12), the projection pushing said inclined portion of said resilient sheet higher than said projection against the related cleaning sheet (7). A disc cartridge according to any preceding claim, wherein said resilient member (12) is secured to one of said cases (1b), a projection (3) is formed on the other said case (1a) at a position opposing said resilient member (12), said disc being clamped between said resilient member (12) and said projection (3) through said cleaning sheets (7).

Inventors: FUKUNAGA KAZUYA, KATO YOSHITAKE, YOSHIMURA HIROYUKI, FUKUNAGA, KAZUYA, KATO, YOSHITAKE, YOSHIMURA, HIROYUKI
Applicants: HITACHI MAXELL, HITACHI MAXELL LTD.
Application year: 1988
Main classification: G11B23
IPC codes: G11B23