DISC CARTRIDGE WITH A CLEANING MECHANISM

Abstract: A disc cartridge comprises an outer case formed of a top half and a bottom half assembled to the top half to provide a disc chamber for rotatably accommodating a recording disc, a pair of pressing plates each mounted in the top half and bottom half so as to oppose each other, cleaning sheets laid between the disc and the pressing plates and openings de­ fined respectively in the top half and the bottom half so as to face each of said pressing plates for pressing said pressing plates toward the disc.

Description: The present invention relates to a disc cartridge with a cleaning mechanism in a cartridge case for cleaning a recording disc. In a disc cartridge having a recording disc so called a floppy disc rotatably mounted in a cartridge case, there have been proposed various kinds of cleaning mechanism for cleaning the floppy disc. Fig. 1 shows a typical conventional disc cartridge of the above kind, wherein an outer case 3 is formed by combining a top half 1 and a bottom half 2 each made of hard plastic resin material. Head insertion windows 1a and 2a are defined on the top half 1 and bottom half 2 respectively and a drive hole 2b is defined at the center portion of the bottom half 2. A floppy disc 4 is accommodated in the space between the top and bottom halves 1 and 2 with a hub 5 of the floppy disc 4 exposed outside of the outer case 3 through the drive hole 2b so that the hub 5 and the floppy disc 4 can be rotated by a disc drive device (not shown). In the disc cartridge mentioned above, a cleaning mechanism is usually proved in such a manner as described hereinafter. A plurality of short parallel ribs 7 are formed on an inner surface of the top half 1 so as to face with a resilient plate 8a of a resilient member 8 hinged on the inner face of the bottom half 2 in a canti lever manner. An upper cleaning sheet 9 and lower cleaning sheet 10 made of non woven sheet having cleaning effect with a generally C shape are respectively provided on the inner surfaces of the top half 1 and bottom half 2 with the entire area or partial area bonded to the respective halves by adhesive agent or thermal bonding. Said disc is disposed between the upper sheet 9 and lower sheet 10 in a sandwich manner as shown in Fig. 2 so as to press the cleaning sheets 9, 10 and the disc 4 by the resilient plate 8a toward the ribs 7. By this arrangement, both of the recording surfaces of the disc 4 can be cleaned by the cleaning sheet when the disc is rotated. However, in the conventional cleaning mechanism mentioned above, the disc 4 is always subjected to the pressure, therefore in a long time storage of the disc cartridge, the disc 4 may be deformed more or less partially at the position where the resilient plate 8a is pressed. In addition foreign matters which are once caught by the cleaning sheets may be undesirably fitted on the disc 4, whereby there occurs an output fluctuation. In order to avoid the problems mentioned above, the pressure of the resilient member 8 to the cleaning sheets must be decreased, thereby resulting in a drawback of decrement of the cleaning effect. In addition in case the top half is bent, the level of the disc 4 which contacts with the ribs i.e., level of the rotational surface or the disc 4 may be displaced and an error occurs in the rotational level of the disc 4. Another conventional cleaning mechanism is shown Figs. 3 to 8, wherein the upper sheet 9 and lower sheet 10 are respectively both halves 1 and 2 similar to the cleaning sheets shown in Fig. 1. There is projected a projection 11 on the inner surface of the top half 1 at the opposite position of the head insertion window 1a of the top half 1. A through hole 12 of a square shape is defined at one corner of the bottom half 2 corresponding to the projection 11 so that a cleaning member of a generally square shape can be inserted into and removed from the disc cartridge through the through hole 12. As shown in Figs. 4 to 6, a continuous rib 14 surrounding the hole 12 is formed on the inner face of the bottom half 2 with a receiving flange 15 formed at the inner peripheries of the rib 14 so as to receive stepped peripheral edges 13a of the cleaning piece 13 of a generally T shape in cross section on the flange 15, thereby preventing the cleaning piece 13 from being removed out of the outer case 3. The disc 4 is kept between the upper and lower sheets 9 and 10 in a similar manner as mentioned in the first example. In the second example, when the cartridge is in no use, as shown in Fig. 7, the disc 14 kept between the projection 11 and cleaning piece 13 can slightly contact with the upper sheet 9 and lower sheet 10 with few pressure. However, when the cartridge is used as shown in Fig. 8, upon mounting of the cartridge on the disc drive device 20, a pressing member 16 provided in the disc drive device pushes the cleaning piece 13 upward. Then the disc 4 is pressed toward the projection 11 through the upper and lower sheets 9 and 10, whereby the disc 4 can be cleaned. The cleaning mechanism shown in the second example has a good cleaning effect and the foreign matters once caught by the upper and lower sheets 9 and 10 can not be fitted again onto the disc 4. However, such a drawback that the rotation level of the disc 4 may be changed if the top half 1 is bent can not be eliminated. As mentioned above, in the conventional cleaning mechanism, since both of the parallel rib 7 in the first example and the projection 11 in the second example are formed integral with the top half 1, contact of the recording and reproducing head of the disc drive device to the recording surface of the disc 4 i.e., so called "head touch" becomes bad by the drawback of the change of the level of the disc. Besides, in order to take the best cleaning effect by the upper and lower cleaning sheets 9 and 10, it is the best way to provide the cleaning mechanism including the ribs 7 or projection 11 at the upper stream side near the head insertion windows 1a and 2a. However, by this arrangement, undesirably effect of the change of the rotation level of the disc 4 due to the bending of the top half 1 appears directly. Accordingly, in the conventional disc cartridge, the cleaning mechanism is provided at the position apart from the head insertion windows 1a and 2a, therefore the disc 4 can contact with the magnetic head after cleaning, so that the foreign matters may fit on the cleaning sheets between the cleaning portion and the head insertion window and the cleaning effect is decreased. The precharacterizing part of claim 1 refers to a disc cartridge as disclosed in EP-A-0 126 884. The known disc cartridge comprises two opposing walls including, oppositely-aligned, movable cleaning members which operate to clean the disc's two recording surfaces. When the cartridge is inserted into the disc drive, a movable push-rod contained within the disc drive operates to push upward on one of the cleaning members. EP-A-0 126 884 refers to EP-A-0 097 221 disclosing the actual construction of the cleaning members. Each cleaning member consists of a loose rigid plastic piece being trapped in an aperture. The plastic piece carries a pad for cleaning the disc. This pad is located in the portion of the disc comprising the data tracks. The cleaning members which are movable fitted in the apertures could undesirably remove from the opening entering into the space between the recording disc and the top or bottom half of the disc cartridge. In case the member enters in said space, the recording disc could be deformed partially, resulting in harming the good recording and reproducing characteristic. DE-U-85 16 550 further discloses a disc cartridge comprising a case formed of a top half and a bottom half to provide a disc chamber for accommodating a recording disc. A cleaning sheet is laid between the top respectively the bottom half. There are provided pressing means for pressing the cleaning sheet against the disc. The pressing means are situated in parallel with the head insertion windows in an area upstream of rotation of the disc. It is the object of the present invention to provide a disc cartridge which is able to operate with high reliability preventing displacement of the cleaning piece or pressing plate for pressing the cleaning sheet to the disc. This problem is solved, according to the invention, with the features of claim 1. Fig. 1 is an exploded perspective view of an example of a conventional disc cartridge, Fig. 2 is a cross sectional view of an essential portion of the disc cartridge shown in Fig. 1, Fig. 3 is a perspective view of another example of a conventional disc cartridge, Fig. 4 is a partial plan view showing a cleaning mechanism used in the disc cartridge shown in Fig. 3, Fig. 5 is a cross sectional view taken along the lines b-b' in Fig. 4, Fig. 6 is a cross sectional view taking along the lines a-a in Fig. 4, Fig. 7 is a cross sectional view of the cleaning mechanism shown in Fig. 4 with the cleaning piece unpressed, Fig. 8 is a cross sectional view of the cleaning mechanism shown in Fig. 4 with the cleaning piece pressed, Fig. 9 is a top plan view showing an example of a disc cartridge, Fig. 10 is a cross sectional view of the disc cartridge shown in Fig. 9, Fig. 11 is a bottom plan view of the disc cartridge shown in Fig. 9, Fig. 12 is an exploded perspective view of the disc cartridge, Fig. 13 is a partial plan view of the cleaning mechanism used in the disc cartridge shown in Fig. 9, Fig. 14 is a cross sectional view of the pressing plate shown in Fig. 13, Fig. 15 is a cross sectional view of the pressing plate shown in Fig. 12, Fig. 16 is a cross sectional view of the essential portion of the cleaning mechanism used in the disc cartridge shown in Fig. 9 with the pressing plate unpressed, Fig. 17 is a cross sectional view of the cleaning mechanism used in the disc cartridge shown in Fig. 9 with the pressing plate pressed, Fig. 18 is a modification of the cleaning mechanism shown in Fig. 13, Fig. 19 is a top plan view of the embodiment of the disc cartridge according to the present invention, Fig. 20 is an outside plan view of the top half of the disc cartridge according to the present invention, Fig. 21 is an inside plan view of the top half of Fig. 20, Fig. 22 is an inside plan view of the top half of Fig. 20 with the pressing plate mounted, Fig. 23 is an inside plan view of the top half of Fig. 20 with the pressing plate and cleaning sheet mounted, Fig. 24 is an inside plan view of a bottom half, Fig. 25 is an inside plan view of a bottom half with the pressing plate mounted, Fig. 26 is an inside plan view of a bottom half with the pressing plate and cleaning sheet mounted, Fig. 27 is an outside plan view of the disc cartridge according to the present invention, Fig. 28 is a plan view of the pressing plate used in the disc cartridge shown in Fig. 19, Fig. 29 is a cross sectional view taken along the lines A-A in Fig. 28 Fig. 30 is a perspective view of an erasure preventing member used in the disc cartridge shown in Fig. 9, Fig. 31 is a plan view showing a modification of the pressing plate, Fig. 32 is a plan view showing a further modification of the pressing plate, Fig. 33 is a plan view showing a further modification of the pressing plate, Fig. 34 is a cross sectional view showing a further modification of the pressing plate, Fig. 35 is a cross sectional view taken along the lines B-B in Fig. 19, Fig. 36 is a top plan view showing a further modification of the pressing plate, and Fig. 37 is a side view of the pressing plate shown in Fig. 36. Referring to Figs. 9 to 18, the various components similar to those shown in Figs. 1 to 8 are designated by the like reference numerals and the description thereof is herein omitted. It is noted that the top half 1 and bottom half 2 are made of ABS resin material. A shutter member 6 is slidably mounted on the outer case 3 in the head insertion window side so as to open the head insertion windows 1a and 2a when the disc cartridge is in use and the head insertion windows is closed by the shutter 6 when the disc cartridge is in no use so as to prevent entrance of the foreign matters such as dust to the inside of the disc cartridge from the head insertion windows 1a and 2a. A pair of openings 17 and 17' in the shape of through holes of a generally elongated rectangular shape are defined on the top half 1 and bottom half 2 in the upper stream side with respect to the direction of rotation of the disc 4 near the head insertion windows 1a and 2a so as to extend in parallel with the head insertion windows and crossing over the recordable area R of the disc 4. A first pressing plate 18 is fitted in the opening 17 of the top half 1 so as to move between the upper cleaning sheet 9 and the top half 1. A second pressing plate 19 is fitted in the opening 17' of the bottom half 2 so as to move between the lower cleaning sheet 10 and the bottom half 2. Both of the pressing plates 18 and 19 are situated in the openings 17 and 17' not so as to press the disc 4 when the disc cartridge is in no use. Both of the pressing plates 18 and 19 are kept in the openings 17 and 17' in such a manner shown in Figs. 13 to 15. Since the pressing plate 19 is kept in the opening 17' in a similar manner as the pressing plate 18 kept in the opening 17, the explanation is made only about the pressing plate 18. The pressing plate 18 has its stepped flanges 18a detachably rested on the corresponding receiving edges 15 formed along the peripheral edges of the opening 17 and stepped downward from the inner face of the top half 1 so as to prevent the pressing plate 18 from being removed out of the top half 1 but to allow to move toward the cleaning sheet 9 and the disc 4. As shown in Figs. 13 to 15, the stepped flange 18a and the receiving edge 15 are formed at the four sides. However, it is not essential to form the stepped flanges 18a and the receiving edges 15 on the respective four sides but they may be formed only opposed two sides as shown in Figs. 36 and 37 or only one of the four sides. In the disc cartridge as mentioned above, since no force is applied to the pressing plates 18 and 19 when the disc cartridge is not used, no force is applied to the disc 4 from the pressing plates 18 and 19. When the disc cartridge is used, the disc cartridge mentioned above is inserted in the disc drive device 20 in such a manner as shown in Fig. 17. Since the disc drive device 20 comprises a projected rib 21 formed at a position corresponding to the lower part of the outer case 3 of the disc cartridge for regulating the level of the disc cartridge in the disc drive device 20 and a spring member 22 to press the pressing plate 19 above the disc cartridge, upon insertion of the disc cartridge into the disc drive device 20, the first pressing plate 18 is lifted by the projected rib 21 up to a predetermined level so as to regulate the level of the floppy disc 4 at the standard level in the disc drive device, while the second pressing plate 19 is pressed downward by the force of the spring member 22 resulting in pressing the floppy disc 4 through the upper sheet 9 toward the first pressing plate 18. Under this state, the magnetic head 23 faces to the head insertion windows 1a and 2a to scan the recording surface of the floppy disc 4, whereby recording in or reproducing from the floppy disc can be performed in the known manner. Accordingly, in the embodiment described above, the floppy disc 4 is not pressed when in no use, but is subjected to the pressure only when in use, therefore, it is possible to increase the pressure of the upper and lower cleaning sheets toward the floppy disc 4 when in use. On the other hand, in case the disc cartridge is preserved long time, there is no fear of forming trace marks in the floppy disc since the no pressure is applied to the disc cartridge. Also there is no fear of entrance of the foreign matter on the floppy disc 4. In addition, since the level of the floppy disc 4 in the disc drive device is regulated only by the height of the projected rib 21 at the position near the upstream side of the head insertion windows 1a and 2a, the level of the floppy disc 4 can be kept constant irrespective of deformation of the top half 1a, whereby the level of contact between the magnetic heads 23 and the floppy disc 4 can be kept constant to assure a good head contact. Also, the fluctuation of the floppy disc 4 in the vertical direction can be prevented to assure a stable head output. Although in the embodiment mentioned above the cleaning sheets are laid on the inner faces of the top half and bottom half so as to cover generally all area of the floppy disc, the cleaning sheets may be provided such area that covers only the pressing plates 18 and 19. As the means for applying the pressure to the upper cleaning sheet, as shown in Fig. 18, there may be laid a resilient plate 24 between the upper cleaning sheet 9 and the top half 1, having the free end of the plate 24 slightly bent toward the cleaning sheet so that the pressing force of the upper cleaning sheet 9 toward the floppy disc 4 is few when in no use but the floppy disc 4 is resiliently pressed to the upper cleaning sheet with a sufficient force when in use by the force upon lifting of the first pressing plate 18 up to the standard level and the lower cleaning sheet 10 by the projected rib 21. Said pressing plate may be disposed anywhere so long as the pressing plate is situated across the recording area of the floppy disc 4. In the embodiment of the disc cartridge mentioned above, both pressing plates 18 and 19 are movably fitted in the openings 17 and 17'. On the contrary the cleaning sheets 9 and 10 must be movable by the pressing plate, therefore at least a portion of each cleaning sheet facing to the pressing plate must be movable in the direction generally perpendicular to the surface of the floppy disc, whereby the periphery of the area of the cleaning sheet facing to the pressing plate is not bonded to the top half 1 or bottom half 2. Therefore, the pressing plate 18 or 19 may undesirably remove from the opening 17 entering into a space between the top half 1 and the upper cleaning sheet 9 or bottom half 2 and the lower cleaning sheet 10. In case the pressing plate 18 (or 19) enters in said space, the cleaning sheet is projected toward the inside of the disc cartridge, whereby the floppy disc 4 is deformed partially, resulting in harming the good recording and reproducing characteristic. In order to prevent entrance of the pressing plates into the space between the cleaning sheet and the top half or the bottom half, there may be provide ribs projected inwardly surrounding the inner periphery of the opening 17 However, since there are laid the cleaning sheets 9 and 10 in the region of rotation of the floppy disc 4 and it is required to provide a space to assure rotation of the floppy disc 4 in the disc cartridge, accordingly it is very difficult to form such ribs in the interior of disc chamber where the floppy disc 4 is rotatably accommodated. In addition, even if such ribs are formed in the disc cartridge, the height of the ribs may not be so high as to effectively prevent the entrance of the pressing plate in the space between the cleaning sheet and the outer case. The embodiment of the present invention described hereinafter is effective to eliminate the problem mentioned above. Referring to Figs. 19 to 30, the outer case 3 of the disc cartridge made of the top half 1 and bottom half 2 is formed in a similar manner as mentioned in the first embodiment and the floppy disc 4 is rotatably accommodated in the disc cartridge, being sandwiched by the upper and lower cleaning sheets 9 and 10. A pair of head insertion windows 105 of an elongated rectangular shape are defined on the region near the one of the sides of the disc cartridge, for example the front side 200 in both of the top half 1 and bottom half 2. In the central region of the bottom half 2, there is defined the circular hole 2b. In the front half region of each of the top half 1 and bottom half 2, a shallow recess 6X having a generally trapezoidal shape is defined for movably accommodating the shutter 6 and limiting the movement of the shutter 6. Said head insertion windows 105 are defined in the recesses 6X. As shown in Fig. 20, an elongated opening 107 is defined for receiving the pressing plate 113 shown in Fig. 22 so as to extend in parallel with the head insertion window 105 at the position of upper stream of the rotational direction of the disc 4 against the head insertion window 105. In the rear half region of the top half 1, a label fitting area 108 is recessed with a shallow depth for fitting a label 109 as shown in Fig. 19. As shown in Fig. 21, four ribs 111 are formed at the respective corners of the inside of the top half 1 to define a disc chamber 112 which generally corresponds to the disc rotation area. Two arcuated ribs 110 are formed in the inside of the top half 1 coaxial with each other and with the center of the circular hole 2b shown in Fig. 24 accommodated in the disc chamber 112 except for the region where the head insertion window 105 and the opening 107 are defined. The number of the ribs 110 may be more than one but preferably several. A pressing plate 113 as shown in Figs. 28 and 29 is movably fitted in the opening 107. The pressing plate 113 is made of plastic resin material and has a generally T shape made of an elongated pressing portion 114 of generally similar shape of the opening 107 and an expanding plate 117 extending both sides of the pressing portion 114. Said pressing portion 114 is surrounded by flanges 132 for engaging with the stepped shoulders 115 formed at the peripheral edges of the top half 1 defining the opening 107 (see Figs. 21 and 24). A shallow recess 129 is formed on one surface of the pressing portion 114 near the expanding plate 117 so as to face the outer peripheral portion of the disc 4. As shown in Figs. 21 and 24, engaging ribs 118 for preventing displacement of the pressing plate 113 with a generally C shape are formed in the front edge portion of both of the top half 1 and bottom half 2 respectively for surrounding the expanding plate 117. It is noted that the engaging ribs 118 are formed at the outside of the disc rotation area so as to make it possible to omit consideration of the space wherein the cleaning sheet exists and the rotation of the disc 4. Therefore it is possible to make the engaging rib having a suitable height and to assure engagement of the pressure plate 14 As shown in Figs. 22 and 25, each pressing plates 113 is fitted in the opening 107 of the top half 1 and bottom half 2 fitting the expanding plate 117 in the space surrounded by the engaging ribs 118, the pressing portion 114 is situated in the rotation area of the disc 4 and flange 132 is engaged with the stepped shoulder 115 to prevent removal of the pressing plate 113 from the opening 107. Also the pressing plate 113 can be kept in position without displacement since the expanding plate 117 is engaged with the engaging ribs 118. Fig. 35 shows a cross sectional view taken along the lines B-B in Fig. 19. Referring to Fig. 35, when the top half 1 and bottom half 2 are assembled together, both top ends of the engaging ribs 118 of the respective halves 1 and 2 abut together to provide a chamber surrounded by the engaging ribs 118 and both expanding plates 117 are accommodated in the chamber opposed each other. In assembling the disc cartridge, after putting the pressing portion 114 of the pressing plate 113 in the opening 107 with the expanding plate 117 fitting in the space surrounded by the ribs 18, there is laid in the disc chamber, the upper cleaning sheet 9 made of non woven sheet of polypropylene rayon having a generally annular shape of almost similar shape of the disc chamber 112. In the bottom half 2, the pressing plate and the cleaning sheet are arranged in the same manner as mentioned above. In this arrangement, peripheral edges of the cleaning sheets 9 and 10 are respectively bonded partially to the top half 1 and bottom half 2 by the thermal bonding. Figs. 23 and 26 show an example of a manner of boding of the cleaning sheets 9 and 10. In the example shown, the respective peripheral edges of the cleaning sheet 9 (10) defined by the lines Q and Q' are bonded along the lines inclined 45° against the line OP which passes the center O of the disc cartridge and the center of the head insertion window 105. The line Q and Q' are inclined 45° on both sides against the line OP. The shaded portions 9a in Fig. 23 and 10a in Fig. 25 show the thermally bonded area of the cleaning sheets 9 and 10. The other peripheral edges of the respective cleaning sheets 9 and 10, they are bonded to the top half 1 and bottom half 2 along the lines extending in the radial direction as shown at 9a' and 10a'. The region (shown at 9b and 10b) of the cleaning sheets 9 and 10 near the opening 107, the thermal bonding is made along the lines inclined 45° against the line OP. By bonding the cleaning sheets 9 and 10 to the upper half 1 and bottom half 2 mentioned above, each pressing plate 113 is covered by the cleaning sheet 9 (10). As shown in Figs. 24 to 26, projections 119 of mountain shape are formed in one corner of the inside of the bottom half 2 and a operation opening 120 of a rectangular shape is defined near the projections 119. A write protector 121 for preventing erasure of recorded signal is movably mounted at a space defined by the projections 19 and the operation opening 120. The write protector 121 is composed of a body 122 and legs 123 with each of the legs 123 engaged with the projections 119 resiliently and an operation tip 124 formed on the body 122 is inserted in the operation opening 120. In Fig. 26, the write protector 121 is situated at a position where write in of signal is inhibited or erasure of the signal is inhibited. Upon sliding the write protector 121 along the longitudinal direction of the operation opening 120, the ends of the legs of the write protector 121 are disengaged from the projections and the write protector can be moved to the write enable position. Reference numeral 125 shows gate marks which are formed when molding of the top half 1 and bottom half 2. It is appreciated that in the embodiment shown, one of the gate marks 125 of each of the top half 1 and bottom half 2 is formed in the area of the recess 6X. Since the thickness of the wall for defining the recess 6X is thinner than the other parts of the disc cartridge, in other words, the gap between the molding forming the wall of the recess 6X is small, if the injection gate is not provided in the region of the recess 6X, there tends to occur poor molding in the wall of the recess 6X. In order to prevent the problem mentioned above, one of the injection gates is provided at the position in the mold for the recess 6X so as to make it possible to change the injection pressure and the maintaining pressure of the gate for the recess 6X independently to improve the moldability. The position of the gate mark 125 in the recess 6X is so defined as shown in Fig. 19 that the gate mark can be covered by the shutter 6 despite that the shutter is opened or closed In case of the top half 1, two gate marks 125 are provided in the label fitting area 108 to cover the gate marks 125 by the label 109, thereby concealing the gate marks. The shutter 6 is made of plastic resin material such as polyacetal resin and polyamid resin which is slightly softer and more resilient than the disc cartridge. As shown in Fig. 19, the shutter is normally biased toward the position for closing the head insertion window 105 by a spring 126. Examples of modification of the pressing plate 113 and the engaging rib 118 is shown in Figs. 31, 32, 33 and 34. In Fig. 31, the pressing plate 113 or 114 is formed by an L shape in plan view and the engaging ribs 118 are formed so as to surround the expanding plate 117. In Fig. 32, the pressing plate 113 is formed by a generally elongated rectangular shape having its both sides cut at 127. In this case, the engaging rib may be formed in the form of projections 127 engageable with the cut portion 127. In Fig. 33, the pressing plate 113 or 114 is formed generally in T shape with an engaging hole 128 of a generally rectangular shape defined at the intermediate portion of the expanding plate so that the engaging hole 128 is engaged with an engaging rib 118 having a rectangular shape. The shape of the engaging hole 128 and the engaging rib may be selected as desired except for a circular shape for preventing rotation of the pressing plate 113. As shown Fig. 34, both upper pressing plate and lower pressing plate may be engaged each other so as to prevent position displacement. Specifically, the upper pressing plate 113a of the top half 1 and the lower pressing plate 113b of the bottom half 2 are situated so as to oppose each other. An engaging pin 130 is projected from the expanding plate 117 of the upper pressing plate 113a so that the engaging pin 130 is detachable engaged in an engaging recess 131 defined in the lower pressing plate 113b. By this engagement between the engaging pin 130 and the recess 131, displacement of the pressing plates 113a and 113b can be prevented. In the example shown in Fig. 34, one of the pressing plates 113a and 113b may be engaged with the disc cartridge so as to prevent displacement of the pressing plate. In the examples mentioned above, the engaging ribs 118 having a relatively large height are formed on the inner surface of the disc cartridge so that the expanding plate 117 can be engaged with the ribs 118, however, it is possible to make the height of the engaging ribs relatively low, making the thickness of the expanding plate 113 thick in such a range that the pressing plate is movable in the vertical direction, whereby displacement of the engaging ribs and expanding plate can be prevented by the engagement of the engaging ribs and the expanding plate. Moreover, the expanding plate may be engaged in a recess formed in the top half or bottom half in place of the engaging rib. Moreover, although in the embodiments mentioned above, the plate pressing opening 107 is formed corresponding to the position of the pressing plate, the present invention is not limited to the arrangement mentioned above it may be possible to make a part of the halves 1 or 2 thin corresponding to the pressing plate 113 for resilient deformation so that the resiliently deformed portion can press the cleaning sheet to the disc to effect the cleaning of the disc. Although in the embodiment mentioned above, the pressing plates are formed in both of the top half 1 and bottom half 2, according to the present invention, the pressing plate may be provided in only any one of the top and bottom halves 1 and 2 and a receiving projected portion having a flat end surface corresponding to the pressing plate may be formed in another half. Moreover, according to the present invention, the cleaning sheet may be formed only in a area opposing to the pressing plate in place of laying the cleaning sheet over all the recording area of the disc. Also the present invention may be used not only in the magnetic disc cartridge but in the other types of the disc cartridge such as magneto-optical disc cartridge. As mentioned above, it is one advantage of the present invention that the disc can be maintained at the standard position irrespective of the deformation of the disc with a high efficiency of the cleaning of the disc, in addition the output of the disc can be kept high and stabilized. Moreover it is further advantages of the present invention that since the pressing plate can be prevented from displacement, the pressing plate can be kept at a predetermined position always, it is possible to improve the reliability of the pressing plate. Also since means for preventing the displacement of the pressing plate is provided in position outside of the rotation area of the disc, the ribs or projections for preventing displacement of the pressing plate can be formed with relatively large height, it is possible to keep smooth rotation of the disc and the design of the disc cartridge may be easy.

Claims: A disc cartridge comprising an outer case (3) formed of a top half (1) and a bottom half (2) assembled to the top half (1) to provide a disc chamber for rotatably accommodating a recording disc (4), a pair of pressing plates (18,19) each mounted in the top half (1) and bottom half (2) so as to oppose each other, cleaning sheets (9,10) laid between the disc (4) and the pressing plates (18,19) and openings (17,17') defined respectively in the top half (1) and the bottom half (2) so as to face each of said pressing plates (18,19) for pressing said pressing plates toward the disc (4), characterized in that said disc cartridge further comprises engaging means (118) disposed in the inside of the top half (1) and bottom half (2) for engagement of the pressing plates (18,19) with the top and bottom half respectively at a position outside the area of rotation of the disc (4). The disc cartridge according to claim 1, wherein said pressing plates (18,19) are disposed near head insertion windows (1a,2a) defined in the top half (1) and bottom half (2). The disc cartridge according to claim 1 or 2, wherein said pressing plates (18,19) are situated extending across the recording area of the disc. The disc cartridge according to one of claims 1-3, wherein said pressing plates (18,19) are situated in positions upstream of rotation of the disc (4) against the head insertion window (1a,2a). The disc cartridge according to one of claims 1-4, wherein the pressing plate (18,19) is situated in parallel with the head insertion window (1a,2a). The disc cartridge according to one of claims 1-5, wherein said pressing plate (18,19) comprises a pressing plate portion (114) and an expanding plate (117) projected from the end portion of the pressing plate portion (114) and the disc cartridge is provided with engaging means (118) for engagement of the expanding plate (117). The disc cartridge according to one of claims 1-6, wherein a recess (129) is formed on the portion of the pressing plate (18,19) corresponding to the outer peripheral edge portion of the disc (4).

Inventors: FUJITA, MINORU 1468, SANORA, FURUMAGI, FUKUNAGA, KAZUYA, KATO, YOSHITAKE 1468, SANORA, FURUMAGI, NAGANAWA, NOBUHIKO 1-9-4, MATSUMAEDAI
Applicants: HITACHI MAXELL LTD.
Application year: 1986
Main classification: G11B23
IPC codes: G11B23