OPTICAL COMPACT DISC STORAGE AND LOADING CASSETTE

Abstract: A CD storage and loading cassette is made from a limited number of components most or all of which are formed by moulding. The moulded components are a tray (2), a slide cover (4), a magnetically permeable puck (8) and a lid (10), in addition to which there may be used a coil spring (6). The cassette is compatible with existing industry standard CD Readers, and its novel design permits the manufacturing and assembly costs to be substantially reduced over the corresponding costs for conventional cassettes. The cassette may be made with planar top and bottom faces to receive the maximum amount of printed information relevant to the data stored on the CD contained in the cassette.

Description: TITLE Optical Compact Disc Storage and Loading Cassette DESCRIPTION Field of the Invention The invention relates to a storage and loading cassette for optical compact discs (CDs) . Such cassettes can be used for storing a CD and, on insertion into a laser disc reader, presenting the CD to the disc drive and reading head of the disc reader without removal of the CD from the cassette. Background Art Optical CDs, originally available only as CD ROMs, are a valuable storage medium for optically encoded digital • information which can be randomly accessed by a laser reading head. They permit rapid access to vast amounts of pre-recorded information and are useful in a wide variety of computer-related applications including video games, computer databases and audio, video and audio-visual recordings. One advantage which CD ROMs have in the data retrieval field is that they cannot be over-written, so that they provide a security of recorded data as well as a vastly increased storage capacity, as compared with magnetic floppy discs for computer use. A more recent entry into the field of optical CDs is an erasible-rewritable CD which has all of the attributes of vast data storage, which is characteristic of a CD ROM, but the additional facility of the ability to erase or overwrite recorded data. One characteristic of a CD reader, or a CD reader/writer (hereinafter referred to simply as a CD Reader) for serious commercial use as opposed to domestic hi-fi music systems, is that the disc may be loaded into the CD Reader while contained in a cassette. The cassette acts as a storage case or storage for the disc while the disc is out of the CD Reader, but enables the disc to be accessed and read (data access) while in the CD Reader. There are two alternative types of storage and loading cassette currently available. In one type, the optical disc remains in the cassette during data access, with the laser reading head accessing the disc through a radial slot in the cassette. The slot is covered by a slide cover when the cassette is removed from the CD Reader. In the other type, the CD Reader includes a pincer mechanism for grasping the disc by its edges, withdrawing it from the cassette and placing it on a turntable, all automatically on loading the cassette into the CD Reader. The reverse sequence takes place automatically prior to ejection of the disc in its cassette from the CD Reader. The present invention is concerned with the former type of CD storage and loading cassette only. One such design of cassette is currently marketed under licence from Sony Corporation under the Trade Mark "CD Caddy", and comprises a tray with a radial base slot for the laser reading head, a lid for covering the disc, and a metal slide cover overlying the upper and lower surfaces of the cassette, for covering the radial base slot and protecting the disc when the cassette is removed from the CD Reader. CD Readers for such cassettes have a now standardized design that enables the CD Reader to engage and open the slide cover, raise the optical disc and lower the cassette until the disc is out of contact with the cassette, and rotate the disc at the required speed for data access, automatically on loading the cassette into the CD Reader. The CD Caddy is a design of cassette that is expensive to manufacture, in that it comprises 14 components, 7 of which are injection moulded from thermoplastics material and 7 of which are fabricated from metal. It is desirable to simplify the design and reduce the manufacturing costs by reducing the number of components and in particular the number of metal components, but the greatest obstacle to such a redesign process is the fact that any new design of CD cassette would have to be fully compatible with existing CD Readers. The external physical dimensions of the new cassette would therefore have to match precisely the expectations of the CD Readers, and all the control surfaces would have to be in exactly the right places. Objects of the Invention It is a first object of the invention to provide a CD storage and loading cassette which satisfies the above desiderata. It is a further object of the invention to produce a CD storage and loading cassette which is made wholly or substantially wholly from injection moulded components. It is a further object of the invention to provide a CD storage and loading cassette which, for both practical and aesthetic purposes, has flat planar upper and lower faces. Those faces can then be printed or can be covered by preprinted paper labels, to display information relevant to the optical CD contained in the cassette. It is a further object of the invention to provide such a CD storage and loading cassette which reduces the wear on the disc in use and which thus extends the disc life. It is a further object of the invention to provide such a CD storage and loading cassette which without major retooling can be made either as a user-openable cassette or as a sealed unit from which the CD cannot be removed except on destruction of the cassette. The Invention In a first aspect, the invention provides a CD storage and loading cassette comprising: a tray for receiving an optical compact disc, including supports moulded on the tray for defining a rest position for the disc, and a radial slot for access of the disc by an optical reading head; a lid covering the tray; and a slide cover automatically slidable, on loading the cassette into a CD Reader, from a rest position covering the radial slot to protect the disc, to an open position at one side of the slot; wherein the slide cover is located inside the cassette between the tray and the disc rest position, and comprises a moulded guide portion slidable in or around a guide portion of the tray and a moulded blade portion for covering the slot when the cassette is removed from the CD Reader. The slide cover and its moulded guide portion are preferably injection-moulded in one piece. The blade portion of the slide cover is preferably a thin plate or sheet, which if injection-moulded from a free-flowing resin for example an acetal resin such as that sold under the Trade Mark KEMATAL under carefully controlled conditions can be made to a thickness of 1 mm or less. The thermoplastics material from which the tray and the lid are moulded may be ABS or styrene, for example. The supports moulded on the tray form what is known as a "landing zone" on which the disc rests when the storage is removed from the CD Reader. Normally a disc should have stopped rotating before it contacts the landing zone, but that is not always the case. Some CD Readers may have poor synchronization of the different moving parts, and in those circumstances if the disc is still rotating as it comes into contact with the landing zone of the CD storage and loading cassette, then the disc can become scratched. The CD Caddy has a landing zone which immediately surrounds the hub of the disc, in an annular zone that is also used to record disc alignment or timing data. Therefore, such prior art CD storage and loading cassettes have an inbuilt potential for failure whenever scratching of the disc in the landing zone area makes some or all of the encoded data unreadable. On the contrary, the landing zone of a disc in a CD storage and loading cassette according to the invention is preferably arranged at the outer perimeter of the disc, which is a zone in which there is no recordal of optical information. Scratching of the disc due to poor synchronization of the CD Reader is not therefore the problem it has been in the past, and disc life is dramatically improved. The landing zone is preferably defined by a number of discrete supports extending around more than 200°, preferably more than 260° of the disc. In a second aspect, the invention comprises a CD storage and loading cassette, comprising: an injection-moulded tray defining an internal well for receiving an optical compact disc; an injection-moulded lid for covering the tray; and an injection-moulded slide cover mounted in the tray and automatically slidable, on loading the cassette into a CD Reader, between a closed position covering a radial slot in the tray and an open position exposing the slot for data access; wherein the injection-moulded tray has a planar bottom face, the internal well being defined by upstanding wall means internally of the tray, and the injection-moulded lid has a planar top face. Preferably the internal well of the tray comprises integral moulded lands for defining a landing zone around the outer periphery of the disc, exactly as described above in relation to the first aspect of the invention. Preferably, also, the slide cover slides on the inside of the tray, between the tray and the disc, as in the first aspect. The flat upper and lower faces of the tray and lid are aesthetically pleasing, but the principal advantage is not aesthetic but commercial. A CD storage and loading cassette according to this aspect of the invention has a greatly increased available area for displaying printed information, either in the form of printing directly onto the tray and lid or in the form of printed self-adhesive labels on the tray and lid. That significantly increases the usefulness of the cassette, since the user can be informed, through that printed information, far more about the nature of the data stored on the disc in the cassette. Preferably the cassette is not user-openable, but the lid is glued or welded closed with the disc inside, either before or after recording the data on the disc. It is, however, a significant advantage that the same or substantially the same tooling can be used both for a user-openable cassette and one that is sealed for life as described above. In a third aspect, the invention provides a CD storage and loading cassette in which all or substantially all the components are moulded. Such a cassette comprises a minimum of moulded components, namely a tray, a lid, a slide cover and a magnetic puck. A final component, a spring for urging the slide cover closed, may be made by injection-moulding or may be a metal coil spring. No other metal formed parts are necessary. In a fourth aspect of the invention, there is provided a CD storage and loading cassette comprising a tray and lid for receiving an optical compact disc, with a radial slot in the tray enabling a laser reader to read optically encoded information from the disc while the disc is rotated within the cassette, and a magnetically permeable puck loosely retained in the lid for gripping the CD between the puck and a magnetic ring of a disc drive unit when the cassette containing the CD is loaded into a CD Reader, Characterised in that the puck is moulded in one piece from a magnetically permeable material. Conventionally, such magnetic pucks are fabricated from moulded non-magnetic plastics material but carry as a snap fit a stamped disc of a metal of high magnetic permeability. In accordance with this fourth aspect of the invention, the magnetic puck may be made by sintering a puck pre-formed by pressing from a high permeability powdered material; or it may be made by injection-moulding from a thermoplastics material incorporating a high metal content or a high proportion by weight of pulverized ferrite. DRAWINGS The invention is illustrated by the drawings of which: Figure 1 is an exploded perspective view of a CD storage and loading cassette according to the invention, without showing the CD which in use is to be loaded therein. In the exploded view, not all parts are in the correct alignment, and some require rotation to enable them to fit together; Figure 2a is a plan view of the tray of the cassette of Figure 1; Figure 2b is a side elevation of the tray of Figure 2a; Figure 3a is a plan view from below of the lid of the cassette of Figure 1; Figure 3b is a section taken along the line 3-3 of Figure 3a; Figure 4 is a plan view of the slide cover of the cassette of Figure 1; Figure 5a is a plan view of the assembled cassette of Figure 1, with a disc in place but with the lid removed; Figure 5b is a plan view similar to that of Figure 5a but with the slide cover moved to one side to expose the disc through the radial slot in the tray, as it would be when loaded into a CD Reader; Figures 6a, 7 and 8 are sections taken along the lines 6-6, 7-7 and 8-8 of Figure 5a; Figure 6b is a section similar to that of Figure 6a but showing a modified guide portion of the slide cover; Figure 9 is a cross-section through the puck of Figure 1; Figures 10 and 11 are plan views of a modified slide cover comprising an integral spring portion, with the spring portion in its relaxed and extended conditions respectively* Figure 12 is a perspective view of a modified CD storage and loading cassette according to the invention, which represents the current best mode of putting the invention into effect. In Figure 12, a pivot lid is shown raised; Figure 13 is an exploded view of the storage and loading cassette of Figure 12; Figure 14 is another exploded view of the cassette of Figure 12, from a position more directly above; Figure 15 is a perspective view of the tray of Figure 12; Figure 16 is a detail of one corner of the tray of Figure 15; viewed from a different angle; Figure 17 is a detail of one end of the lid support, for cooperation with the corner of the tray shown in Figure 16; Figure 18 is a perspective view of the slide cover of the cassette of Figure 12; and Figure 19 is an enlarged detail taken from Figure 18. Referring first to Figure 1, the CD storage and loading cassette comprises a tray 2, a slide cover 4, a coil spring 6, a magnetically permeable puck 8 and a lid 10. The tray 2 is illustrated in more detail in Figures 2a, 2b and 7. The tray 2 has a base 12 with a flat underside, an upstanding wall 14 parallel to one edge, and four upstanding walls 16 around a central disc-receiving area. Around the inside of the walls 16 are a number of integrally moulded raised portions 17 which together form a "landing zone" on which a disc may rest. The height of the landing zone from the bottom of the well is sufficient to prevent chafing of the disc by a moulded detent 18, and sufficient to accommodate a blade portion 20 of the slide cover 4 (Figures 7 and 8) . It will be seen that the slide cover 4 (Figure 4) comprises the moulded blade portion 20 and a moulded guide portion 22, preferably moulded together in one piece. The blade portion 20 is slightly profiled with a central dished portion 24 as shown in Figure 8, to locate in a radial slot 26 in the cassette tray when the slide cover is in its rest position shown in Figure 5a. One edge portion 28 of the blade portion 20 locates beneath the moulded detent 18. The detent 18 merely serves to anchor the distal end of the blade portion 20 and hold the blade portion away from the optical disc in use. In use, when the cassette is loaded into a CD player, the player will engage a hook portion 30 of the guide portion 24 and move the guide portion laterally, physically to move the slide cover 4 to its open position against the bias of the spring 6 as shown in Figure 5b. Assembly of the tray 2, slide cover 4 and spring 6 is perfectly simple. One end of the spring 6 is placed around a post 32 integrally moulded in the tray 2 as shown in Figure 6a. The other end of the spring 6 is pressed around a similar post 34 moulded in the underside of a downwardly facing channel 36 in the guide portion 24. The spring 6 is thus contained in the channel 34, and securely anchored at its ends. Figure 6b shows how, in an alternative construction, the channel 36 may be downwardly facing so that the spring 6 is totally enclosed. The puck 8 is shown in perspective view in Figure 1 and in section in Figure 9. It may be made by sintering a pulverized metal or ferrite, by injection-moulding a thermoplastics material containing a high proportion of magnetically permeable metal or ferrite particles, or by any other moulding process. The puck 8 is retained in a rod cage 40 moulded on the underside of the lid 10 (Figures 3a and 3b) . The individual rods of the rod cage 40 have inwardly directed detent noses 42 between which the puck 8 can be pressed as a snap fit. The rod cage 40 can be made by injection-moulding using a collapsing core mould (for example a HASCO [Trade Mark] collapsing core mould) without losing the planar flat upper face of the lid 10. The lid 10 may be provided with a flexure hinge 42 (optional) near to one edge portion 44 so that if that edge portion 44 is made fast to the corresponding edge of the tray (for example by welding or adhesive) then the lid may be opened and closed to permit the CD carried by the tray to be changed. Alternatively the lid 10 may be made fast to the tray all round its periphery so that, after sealing, the disc cannot be removed or changed. The CD storage and loading cassette illustrated is of commercial utility in that it is compatible with existing CD Readers which are able to engage the hook 30 and automatically to open the slide cover 4 on loading the cassette into the CD Reader; it is formed from only four moulded parts (the tray 2, the slide cover 4, the puck 8 and the lid 10) in addition to the formed metal spring 6; and it has smooth flat planar top and_ bottom faces for the application of printed information relating to the disc contained in the cassette. If it were desired to make the cassette wholly from moulded components, then the spring 6 could be replaced by a resilient moulded coil portion 46 of the slide cover 4 as illustrated schematically in Figures 10 and 11. Figure 10 illustrates the coil portion 46 in its rest position as it would be if the slide cover 4 were closed, and Figure 11 illustrates the coil portion 46 in its extended condition as it would be when the slide cover 4 were opened by the CD Reader to expose the disc through the slot 26. Figures 12 to 19 illustrate an alternative embodiment, in which the same reference numerals have been used as those used in Figures 1 to 11, in respect of the same or similar parts. The principal difference between the cassette of Figure 1 and that of Figure 12 is that the lid 10 of Figure 12 is pivoted in side recesses 46 of the tray 2 which receive moulded lugs 48 of the lid 10. The lugs 48 are held in the recesses 46 by a front cover plate 50 which has complementary recesses 52 formed therein. Figures 16 and 17 show the detail of the complementary recesses 46 and 52. It will be appreciated that Figures 16 and 17 are not to the same scale. The moulded detent 18 of the embodiment of Figures 12 to 19 is proportioned slightly differently from that in Figures 1 to 11, having a greater dimension in the direction of sliding of the slide cover 4. The slide cover itself is constructed slightly differently, with a guide bar portion 54 receivable between two parallel walls 56 and 58 of the tray 2, and the coil spring 6 (shown only in Figure 14) located between the guide bar 54 and the inner wall 58. The inner end portion of the slide cover 4 is formed of a reduced wall thickness at 60 to accommodate the width of the detent 18. The puck of the embodiment of Figures 12 to 19 is exactly the same as that of Figures 1 to 11, and is therefore not illustrated again separately.

Claims: CLAIMS 1. A CD storage and loading cassette comprising: a tray for receiving an optical compact disc, including supports moulded on the tray for defining a rest position for the disc, and a radial slot for access of the disc by an optical reading head; a lid covering the tray; and a slide cover automatically slidable, on loading the cassette into a CD Reader, from a rest position covering the radial slot to protect the disc, to an open position at one side of the slot; wherein the slide cover is located inside the cassette between the tray and the disc rest position, and comprises a moulded guide portion slidable in or around a guide portion of the tray and a moulded blade portion for covering the slot when the cassette is removed from the CD Reader. 2. A CD cassette according to claim 1, wherein the supports moulded on the tray define a minimum spacing between a CD received in the tray and a top inner surface of the tray, and the moulded blade portion of the slide cover is of a thickness less than the said minimum spacing. 3. A CD cassette according to claim 1 or claim 2, wherein the slide cover is injection-moulded in one piece. 4. A CD cassette according to any preceding claim, wherein an edge of the blade portion of the slide cover remote from and parallel to the guide portion is slidably received beneath an overhanging projection upstanding from the inside of the tray. 5. A CD cassette according to any preceding claim, wherein the slide cover is slidable to one side only of the radial slot, to define its open position. 6. A CD cassette according to any preceding claim, wherein the slide cover is spring-biased towards its rest position. 7. A CD cassette according to claim 6, wherein the spring bias is provided by a coil spring having its opposite ends anchored to the slide cover and the tray respectively. 8. A CD cassette according to claim 7, wherein the moulded guide portion of the slide cover comprises an open channel portion defined between two walls, the guide portion of the tray comprises an interfitting open channel portion defined between two further walls and the spring is located in the innermost of the two open channel portions. 9. A CD cassette according to claim 6, wherein the spring bias is provided by an integrally moulded coiled portion of the slide cover, the coiled portion having a natural resilience to assume the tightly coiled state in which state it holds the slide cover in its rest position. 10. A CD storage and loading cassette, comprising: an injection-moulded tray defining an internal well for receiving an optical compact disc; an injection-moulded lid for covering the tray; and an injection-moulded slide cover mounted in the tray and automatically slidable, on loading the cassette into a CD Reader, between a closed position covering a radial slot in the tray and an open position exposing the slot for data access; wherein the injection-moulded tray has a planar bottom face, the internal well being defined by upstanding wall means internally of the tray, and the injection-moulded lid has a planar top face. 11. A CD cassette according to claim 10, wherein the slide cover is mounted between the tray and the lid, to cover the radial slot from a position internally of the tray. 12. A CD cassette according to claim 10 or claim 11, wherein the lid is an openable hinged lid. 13. A CD cassette according to claim 10 or claim 11, wherein the lid is a locking lid designed to secure in position an optical compact disc within the well of the tray. 14. A CD cassette according to any of claims 10 to 13, wherein integrally moulded with the tray is support means for an optical compact disc, for engaging and supporting an outer periphery of the disc when the disc is positioned in the well of the tray. 15. A CD storage and loading cassette comprising a tray and lid for receiving an optical compact disc, with a radial slot in the tray enabling a laser reader to read optically encoded information from the disc while the disc is rotated within the cassette, and a magnetically permeable puck loosely retained in the lid for gripping the CD between the puck and a magnetic ring of a disc drive unit when the cassette containing the CD is loaded into a CD Reader, Characterized in that the puck is moulded in one piece from a magnetically permeable material. 16. A CD cassette according to claim 15, wherein the puck is injection-moulded from a thermoplastic material containing a high proportion by weight of pulverized ferrite. 17. A CD cassette according to claim 15, wherein the puck is made of sintered metal. 18. A CD cassette according to any of claims 15 to 17, wherein the puck is retained in a moulded bearing recess in the lid. 19. A CD cassette according to claim 18, wherein the moulded bearing recess in the lid is one in which the puck * is receivable as a snap fit. 20. A CD cassette according to claim 19, wherein the moulded bearing recess in the lid is moulded as an open cage using a collapsing core mould.

Inventors: NEWELL TERENCE JOHN, NEWELL, TERENCE, JOHN
Applicants: DATA SPECIALISTS LTD, NEWELL TERENCE JOHN, DATA SPECIALISTS LIMITED, NEWELL, TERENCE, JOHN
Application year: 1993
Main classification: G11B23
IPC codes: G11B23