IMPROVED SLIDING SHUTTER ARRANGEMENT FOR DISK CASSETTE

Abstract: A disk cassette (1) arrangement which includes a double sided disk (2) is arranged to be used in both dual and single head disk drive units. The cassette case is comprised of upper and lower halves or shells (8,9) which are formed so that a reinforcing rib (21, 22) is defined when they are coupled to­ gether. A guide slot (14) is formed in the rib. The cassette features a shutter (5) which has a U-shaped cross-section and which is slidably disposed on the leading edge of the cassette case (1). A projection (17) which extends from the inboard edge of the shutter (5) has a barbed like arrangement which ban be inserted through a tapered section of the guide slot.

Description: The present invention relates to a disk cassette having at least one head access opening and having a slidably fixed shutter for selectively opening and closing said at least one head access opening. EP-A-0137965 discloses a disk cassette having the following features: a rotatable disk; a case in which said disk is rotatably supported, said case having two surfaces with a head access opening in at least one of said surfaces, and having four side walls including a front wall which is the side wall closest to said at least one head access opening; and a shutter slidably fixed to said case and comprising at least one flat plate-like portion for selectively opening and closing said at least one head access opening and comprising an edge portion parallel to said front wall. said front wall (12) comprising at least one guide slot (14a, 14b) extending in length direction of said front wall; and said shutter (5) comprising at least one projection (17) extending from said edge portion (15) through said at least one slot within said front wall. One of the surfaces of said cassette comprises a groove which guides a guide nose projecting from one of the flat plate-like portions of the shutter into said groove. When assembling this arrangement, it is necessary to spread the legs of the U-shaped shutter when fitting the same onto the case. This spreading results in excessive play of the shutter and improper sliding characteristics. In addition, when handling the cassette, the flat plate-like portions of the shutter may be spread to a degree that the mentioned projection is no longer guided by the relatively shallow guide groove and therefore the shutter detaches from the case. It is the object of the present invention to provide a disk cassette having a shutter which can be assembled with a case without spreading the flat plate-like portions, and which is securely fixed to said case after assembling. The disk cassette of the present invention comprises the above listed features of the prior art disk cassette, and it is characterized in that, each projection comprises a first section penetrating through the associated slot, and an end section having a width greater than that one of said guide slot, to hold said shutter fixed to said front wall and with this fixed to said case. In the disk cassette of the present invention, the guiding projection extending from the shutter is no longer provided at one of the flat plate-like portions of the shutter, but it is provided at its edge portion. Therefore, it is no longer necessary to bend the flat plate-like portions when fixing the shutter to the case. The shutter is securely fixed to the case, as its at least one projection has an end section having a larger diameter than the associated guiding slot in the front wall of the case, said end section preventing detachment of the shutter from the case. Preferably, each slot and/or each end section of a projection has tapered surfaces to facilitate insertion of the end section into the associated slot. The present invention will be understood more fully from the detailed description given herebelow and from the accompanying drawings of the preferred embodiment of the invention, which, however, should not be taken to limit the invention to the specific embodiment but are for explanation and understanding only. In the drawings: Fig. 1 is a bottom view of a disk cassette case provided with the shutter arrangement according to a preferred embodiment of the present invention; Fig. 2 is an exploded perspective view of the arrangement shown in Fig. 1; Fig. 3 is a sectional view showing the shutter mounted on the disk cassette and the construction which characterizes the embodiment of the present invention; Fig. 4 is a perspective view of a corner of the shutter as seen from a first angle; Fig. 5 is a second perspective view of a corner of the disk cassette as viewed from a second angle; and Fig. 6 is a cut-away and partially sectioned view of disk cassette and shutter in an assembled state and which highlights the sliding motion of the shutter and the attendant compression of a torsion spring which cooperates with the construction which characterizes the embodiment of the instant invention. DETAILED DESCRIPTION OF THE PREFERRED EMODIDMENTS Referring now to the drawings, particularly to Figs. 1 and 2, the preferred embodiment of a disk cassette arrangement, according to the present invention, is illustrated with a shutter arrangement for opening and closing a disk access aperture. The disk cassette 1 comprises a magnetic disc 2 as an information recording medium, a cassette casing 3 in which the disk is rotatably disposed and a shutter 5 which will be described in more detail hereinlater. The disk 2 in this instance takes the form of a thin and flexible circular member of flexible high polymer polyethylene terephthalate which has at least one surface coated with a layer of magnetizable material (or the like) in which data can be recorded. A concentric opening 6 is formed in the middle of the circular member. A center hub 7 is fixedly disposed in this opening 6 in a manner to be synchronously rotatable with the circular member or disk as it will be referred to hereinafter. The casing 3 has an essentially flat square or rectangular shaped configuration and, as shown in Fig. 2, is comparatively thin relative to its length and width dimenions. Since the shown embodiment is directed to house a double-sided disk which has both surfaces coated with a magnetizable material, head assembly access apertures 4 are formed in both of the upper and lower halves or shells 8, 9 of the casing 3 which in this instance are formed of a high polymer ABS plastic resin. Felts (not shown) for preventing abrasion and the formation of static electrical charges are disposed between each of the halves and the surfaces of the disk in a well known manner. Though the shown embodiment employs the double-side disk as the recording medium and, as a consequence, the head access apertures 4 are formed in both of upper and lower halves 8 and 9, the invention should not be appreciated to be confined to such double-side disk cassette. Namely, the present invention is also applicable for a single-side disk cassette which has a single-sided magnetic disk. In the latter case, the head access aperture may be formed in only one of the upper and lower halves opposing the surface coated by the magnetizable material. Furthermore, although the materials of the magnetic disk and the cassette casing are specified hereabove, it should be appreciated that the foregoing recitations about the materials should be mere example and non-essential feature of the present invention. Circular openings 10 are formed in essentially the middle of the upper and lower halves 8, 9 of the case 3. These openings are concentric to the hub 7 and permit a drive connection between the latter and the turntable of a drive mechanism of the disk drive (both not shown) to be established upon insertion of the disk. As seen in Fig. 1 the inwardly depending ribs of respective of upper and lower halves 8 and 9 define the front, rear and side wall sections 11 of the assembled cassette casing 3. The upper and lower halves 8, 9 of the casing 3 are also formed with ribs 21, 22 which extends substantially in parallel to the ribs 11 forming the front wall section of the assembled cassette casing 3. As clearly seen from Fig. 3, the ribs 21 and 22 are so arranged as to overlap with each other and thus serve for mutual positioning of the upper and lower halves in assembling. The ribs 21, 22 may also serve to form reinforment for the cassette casing in order to prevent the casing from deforming. The front or leading wall 12 of the cassette is slightly recessed in a manner to defined two shoulder portions 13 which project forward from the forward front corners of the arrangement. As best seen in Fig. 2 the front wall section 12 is formed with two guide slots 14a and 14b. The shutter 5 has an essentially U-shaped cross-section which defines a narrow edge portion 15 and two integral flat plate-like portions 16a and 16b which extend from the edge portion 15 to define the legs of the U-shape. First and second projections 17 are formed on the inboard surface of the edge portion 15 proximate the ends thereof. In this embodiment in order to reduce sliding friction, the shutter 5 is formed of a polyoxymethylene high polymer which exhibits excellent abrasion resistance. The flat plate-like portions 16a and 16b of the shutter 5 are formed with apertures 18a, 18b and 19a, 19b, respectively. These apertures 18a, 18b and 19a, 19b are arranged to be larger than the disk access apertures 4 formed in the upper and lower halves 8 and 9 of the casing 3, and are located so that when the shutter 5 is moved from a home position in one direction by a predetermined amount for moving the apertures 18a and 19a to locations wherein the head of the disk drive can be moved into close proximity of the disk and; when moved by essentially the same amount in the opposite direction from its home or neutral position, the apertures 18b and 19b expose the disk access apertures 4. It will be noted that it is possible to increase the number of apertures formed in the shutter and that the present invention is not limited to the use of only 4. As apparent from Figs. 3 the upper and lower halves or shells of the casing 3 are so configurated that the guide slots 14a, 14b formed in the front wall section 12 of the casing are in such configuration as to each have a wide section having a width L2 and a narrow throat-like section having a width L1. Further, as best seen in Fig. 2 the central sections of the guide slots 14a, 14b are also formed with outwardly opening tapers 23a. It should be noted however, that the location of the tapers is not necessarily limited to the illustrated position and can be formed in other positions if so desired. The projections 17 are, as shown in Figs. 3 and 4, formed with a narrow section 24 having a width x1 and a wide section 25 having a width x2. As will be appreciated from Fig. 3 these widths are selected to be just less than the corresponding widths L1 and L2. With this construction when the shutter 5 is fitted onto the casing, the barb-like or arrow head-like constructions on the ends of the projections 17 prevent the shutter from being readily removed therefrom. Tapered portions 26 are formed on each of the wide portions 25 in a manner which defines a nose-like arrangement. These nose portions cooperates with the tapers 23a formed in the guide slots 14a and 14b in a manner which facilitates the distortion of the upper and lower halves or shells 8 and 9 as the projections 17 are forced through the guide slots to assume the positions shown in Fig. 3. Therefore, upon assembling the shutter 5 onto the front wall section 12 of the cassette casing 3, the projections 17 of the shutter can easily engage with the guide slots 14a, 14b placing the wide section 25 within the wide section of the guide slots by simply pressing the shutter toward the front wall section to cause aforementioned distrotional action of the upper and lower halves for convenient and effecient assembling operation. In order to reinforce the projections 17 against distortion and possible breakage both during assembly and use, webs or ribs 28 are formed integrally with the same and are arranged to extend inwardly along the inner surface of the edge portion 15 as shown in Figs. 4, 5 and 6. A fork-like arrangement 27 is formed on laterally outboard edges of the narrow section 24 and each of the projection 17. These arrangements serve to engage the inboard legs of the torsion springs 20 which are disposed in the case 3 on either side of the shutter 5 and which bias the same to assume the above mentioned normal or home position wherein the disk access apertures 4 are closed. The outboard leg of each of the torsion springs 20 are arranged to seat in a corner section 35. The shutter further includes apertures 29 and 30. These apertures are provided at each end of the edge portion 15 (see Fig. 5) are provided to facilitate the injection moulding of the unit. Formed on the upper surface and at both ends of the edge portion 15 adjacent injection moulding facilitation apertures 29 and 30 are triangular shaped shoulder-like projections 31. These projections 31 are comprised of a two parallel triangular shaped webs or ribs 32a and 32 and an end wall 33 which is arranged normally to the just mentioned ribs. These constructions increase the rigidity of the shutter 5 and assist in preventing any distortion of the projections 17 during assembly and sliding motion against the spring force of one of the springs 20. The projection also assist in preventing the edge portion 15 of the shutter 5 from bending and thereby assist to maintain firm and dust-proofing contact between the flat plate-like portions 16a and 16b and the associated surfaces of the upper and lower halves 8, 9 of the cassette casing. They further assist in providing surfaces which cooperate with a pin (not shown) of the disk drive which engages the shutter and moves to one side in a manner which opens the disk access opening 4. The end walls 33 are arranged to abut against the inwardly depending walls (no numeral) of the shoulder 13 defined on the case 3. Although the preceeding description has related to disks which are coated with a magnetizable medium it will be understood that other types of disks which are influenced by light (lasers) or ones having an abrasive surface for head cleaning purposes may also be used without departing in any way from the scope of the present invention.

Claims: A disk cassette (1) comprising: a rotatable disk (2); a case (3) in which said disk (2) is rotatably supported, said case having two surfaces with a head access opening (4) in at least one of said surfaces, and having four side walls including a front wall (12) which is the side wall closest to said at least one head access opening; and a shutter (5) slidably fixed to said case and comprising at least one flat plate-like portion (16a, 16b) for selectively opening and closing said at least one head access opening and comprising an edge portion (15) parallel to said front wall; said front wall (12) comprising at least one guide slot (14a, 14b) extending in length direction of said front wall; and said shutter (5) comprising at least one projection (17) extending from said edge portion (15) through said at least one slot within said front wall, characterised in that each projection comprises a first section penetrating through the associated slot, and an end section (25) having a width greater than that one of said guide slot, to hold said shutter fixed to said front wall and thereby fixed to said case. A disk cassette according to claim 1, characterized in that each guide slot (14a, 14b) has outwardly opened tapered sections (23a) for facilitating insertion of the end section (25) of the associated projection (17) through said guide slot. Disk cassette according to one of the claims 1 or 2, characterized in that the end section (25) of each projection (17) is tapered (26) for facilitating insertion of said end section through the associated guide slot (14a, 14b).

Inventors: FUNAWATARI, KOUJI C/O SONY MAGNETIC PRODUCTS, INC., HARADA, MASAYUKI C/O SONY CORPORATION, NEMOTO, TSUNEO C/O SONY MAGNETIC PRODUCTS, INC.
Applicants: SONY CORPORATION
Application year: 1987
Main classification: G11B23
IPC codes: G11B23