GB2102188A - Magnetic disc cartridges - Google Patents

Abstract

A magnetic disc cartridge 1 comprises a jacket 2 which contains a rotatable magnetic disc having a hub 6 which receives a rotatable shaft which drives the disc. The jacket 2 has an opening 7 through which the rotatable drive shaft passes. When the disc is rotated, information may be recorded in a plurality of circular tracks thereon. The jacket 2 has an indicator 20 for indicating the number of tracks in which information signals have already been recorded. The indicator 20 includes a scale 28 and a rotatable member 21 having a keyhole-shaped opening 22, 23 which in operation is engaged by a shaft 30 of a recording apparatus, to be rotated by incremental angles each representing the recording of a track. The keyhole-shaped opening 23 also acts as a pointer indicating the track number. The rotatable member 21 may have teeth engaged with a resilient pawl 25 within the jacket 2, to restrain it against rotation when disengaged from the apparatus. <IMAGE>

Description

SPECIFICATION Magnetic disc cartridges This invention relates to magnetic disc cartridges.

Rotatable magnetic discs have been used for recording information in various types of devices.

For example, in computer systems and word processors, magnetic discs, sometimes known as "discettes," have been used to record information signals. Typically, such discs are housed in a jacket which serves to protect the magnetic information recording surfaces of the magnetic disc and, furthermore, to prevent the disc from being folded, crumpled or otherwise seriously damaged. Such a protective jacket is provided with a window through which one or more magnetic transducers may be inserted to contact the magnetic surface of the disc for recording or reproducing information signals. The information signals are recorded in a plurality of circular recording tracks.

In a disc of this type, there is no indication on the jacket or disc-housing apparatus for indicating to a user the number of tracks on which information signals have been recorded.

According to the present invention there is provided a magnetic disc cartridge comprising a jacket for containing a rotatable magnetic disc, said disc having a hub member for receiving a drive member to rotate said disc to record information in circular tracks on said disc, an opening in said jacket through which said hub member is accessed and indicator means on said jacket for indicating the member of tracks in which information has been recorded.

The invention will now be described by way of example with reference to the accompanying drawings, through which like references designate like elements, and in which: Figure 1 is a plan view of a cartridge containing a flexible magnetic disc, which is shown partly broken away; Figure 2 is a plan view of the cartridge of Figure 1, but as viewed from the opposite side thereof; Figure 3 is an enlarged sectional view taken along the line 3-3' in Figure 1; Figure 4 is an enlarged fragmentary top plan view of the cartridge with the top wall removed; Figure 5 is an enlarged sectional view taken along the line 5-5' in Figure 4; Figure 6 is an enlarged fragmentary top plan view of the cartridge, with the top wall removed and wherein an indicator driving pin is inserted into an aperture thereof; and Figure 7 is an enlarged sectional view taken along the line 7-7 in Figure 6; Referring initially to Figures 1, 2 and 3, it will be seen that a cartridge 1 intended for use in a flexible disc recording and/or reproducing apparatus comprises a substantially flat rectangular jacket or housing 2 which may be moulded of a suitable plastics material and has opposed walls 2a and 2b between which a flexible disc 3 of magnetic material is freely rotatable.The disc 3 is of a suitably small diameter, for example, no more than about 50 mm, so that the jacket 2 can be of correspondingly small size, for example, measuring 60 mm by 54 mm by 3 mm, for convenience of handling, storage and shipping, as by mail, and for use in a very compact recording and/or reproducing apparatus which may, for example, be part of a still picture camera which is not substantially larger than a conventional 35 mm single-lens reflex camera. The opposed wall 2a and 2b of the jacket 2 have aligned openings or windows 4 therein which extend, in the radial direction of the disc 3, at least to the inner and outer effective limits of circular recording tracks, of a recording surface 3a on the disc 3.A door member 5 straddles the disc 3 and is slidable along an edge portion of the jacket 2 with portions of the door member 5 disposed against the inner surfaces of the walls 2a and 2b for slidable movement in the direction of an arrow 5a in Figure 1 from the illustrated closed position to an opened position in which the door member 5 clears the windows 4. A tension spring Sb may be connected to the door member 5 for urging it to its closed position, and a projection 5c extends from the door member 5 and may be acted upon by a suitable member provided on the apparatus which receives the cartridge 1 in the camera (not shown) for opening the door member 5 upon the insertion of the cartridge 1 into the recording and/or reproducing apparatus.When the door member 5 is thus opened, one or more magnetic heads can extend through one of the windows 4 for magnetically recording information signals, for example, representing a still image or picture, in a selected one of concentric circular record tracks on the surface 3a (Figure 3) of the disc 3.

A hub 6 is provided at the centre of the disc 3 and has a hole 7 extending therethrough for receiving a drive shaft (not shown) of the recording and/or reproducing apparatus. The hole 7 is preferably non-circular so as to define a pair of relatively angled positioning surfaces 8 arranged tangentially to engage the circular periphery of the drive shaft for centring the disc 3 relative to the axis of the drive shaft. A resilient chordal element 9 extends across the hole 7 at the side of the hole 9 opposite to the positioning surfaces 8. The element 9 is backed up by an elongated hole 10 extending along the element 9 at the side of the element 9 opposite to a surface 9a thereof which faces towards the surfaces 8. The hub 6 can easily be moulded of suitable plastics material which further lends elasticity to the element 9.The hole 7 is dimensioned so that, when the drive shaft is inserted therein, the element 9 is flexed in the direction away from the surfaces 8 by the drive shaft, to maintain firm contact of the surfaces 8 with the outer periphery of the drive shaft.

The hub 6 is further shown to have an annular magnetic member 11 suitably mounted on its lower surface. A magnetic detecting pin 13 for use in detecting the rotational phase or position of the disc 3, and a non-magnetic balancing pin 14 of substantially the same weight as the pin 13 are embedded in the hub 6 at diametrically opposed locations. In one embodiment, at least three supports or feet 1 6 extend from the lower surface of the hub 6 at equally angularly spaced apart locations which are radially outward with respect to the annular magnetic member 11. Bottom surfaces of the feet 1 6 project slightly from the underside of the hub 6 and define a reference level with respect to the recording surface 3a of the disc 3. In another embodiment, the feet 16 are replaced by a continuous annular rim.The walls 2a and 2b of the jacket 2 have central openings 17a and 17b in which the hub 6 is loosely rotatable.

The jacket 2 of the cartridge 1 is provided with an indicator 20 which is arranged to display an indication of that portion of the capacity of the disc 3 which has been consumed or, alternatively, that portion of the capacity of the disc 3 which remains available for further recording. More particularly, the indicator 20 provides an indication of the number of tracks in which information signals have been recording on the disc 3. From Figures 1 and 2, it is seen that the indicator 20 includes a rotatable dial 21, an index scale 28 circularly arranged about the dial 21, and a pointer associated with the dial 21 and arranged to point to an indication on the index scale 28 which represents the number of tracks which have been recorded on the disc 3.

In the illustrated embodiment, the dial 21 is arranged to rotate with respect to the index scale 28. In an alternative embodiment, the index scale may be provided on the rotatable dial and, thus, may be rotatable with respect to a pointer that is fixedly disposed on the jacket 2. It is appreciated, therefore, that the dial 21 and the index scale 28 are relatively rotatable with respect to each other.

Preferably, as illustrated in Figure 1 , the index scale 28 is provided with markings or indicia which provide a numerical indication of the number of tracks which have been recorded on the disc 3. As one example, the disc 3 may be provided with a recording capacity of about 50 tracks. Hence, the index scale 28 is provided with a recording capacity of about 50 tracks. Hence, the index scale 28 is provided with numerical indications from track 1 to track 50. Suitable marks or gradations may be provided between the discrete numerals indicated in Figure 1. Such marks may represent every track, every other track, or as required.

The jacket 2 is provided with a further aperture 27 through which the dial 21, for example, may be accessed by a compatible drive mechanism, described below. The dial 21 is positioned within the space defined by the spaced apart top and bottom walls 2a and 2b, and is arranged to rotate therein. The pointer described below with respect to Figure 4 may be observed through an opening 27a in the top wall 2a, and the dial 21 itself may be driven by a suitable device which engages the dial 21 through an aperture 27b in the bottom wall 2b.

As best shown in Figures 4 and 5, the dial 21 is mechanically coupled to a gear 24 with teeth about the periphery. In the preferred embodiment, the dial 21 and the gear 24 are of unitary construction formed of a suitable plastics material.

Alternatively, the gear 24 may be coupled, as by a suitable mechanical transmission, to the dial 21.

In one embodiment wherein the dial 21 and the gear 24 are of unitary construction, the gear 24 is formed symmetrically with respect to the dial 21 such that equal portions of the dial 21 are disposed above and below the gear 24, as shown in Figure 5. The dial 21 may be thought of as the central hub of the gear 24. In the embodiment shown in Figure 5, the top and bottom surfaces of the dial 21 are stepped respectively so as to be seated within the apertures 27a and 27b of the top and bottom walls 2a and 2b, respectively. In an alternative embodiment, the stepped portions may be omitted, whereupon the upper and lower surfaces of the gear 24 seat on the inner surfaces of the top and bottom walls 2a and 2b of the jacket 2, respectively, whereupon the dial 21 is positioned within the apertures 27a and 27b.

A releasable locking device 25 co-operates with the gear 24 to lock the gear 24, and, thus, the dial 21, at the then-present position of the dial 21. As will be described, the dial 21 may be rotatably driven by a suitable drive mechanism provided in the recording and/or reproducing apparatus with which the cartridge 1 is used so as to up-date the indication provided by a pointer 23 as the number of circular tracks in which information has been already recorded increases.

The dial 21 is rotated in a step-wise manner, and the releasable locking device 25 serves to retain the dial 21 at the last position to which it has been rotated. This enables the cartridge 1 to be removed from the magnetic recording and/or reproducing apparatus while retaining the proper indication of the last track which has been recorded immediately prior to the removal thereof.

That is, the dial 21 is restrained from inadvertent rotation when the cartridge 1 is handled, stored or shipped.

In the illustrated embodiment, the releasable locking device 25 is formed of a resilient pawl 25b which terminates in a nose 25a that is insertable between adjacent teeth of the gear 24. The pawl 25b is formed of unitary construction with a mounting block 25c, the mounting block 25c and the pawl 25b being formed of a suitable plastics material. As illustrated, the pawl 25b depends from the mounting block 25c. The mounting block 25c is arranged to be mounted on the inner surface of, for example, the top wall 2a of the jacket 2. Suitable mounting elements, such as screws 26, may be used. Alternatively, mounting pins may be formed integrally with the inner surface of the top wall 2a of the jacket 2 and the mounting block 25c includes suitable apertures which register with such mounting pins such that the mounting block 25c is mounted by a pressed fit.

The resilient pawl 25b urges the nose 25a into engagement with the teeth of the gear 24. As the gear 24 is rotatably driven (to be described), the movement of the teeth thereof flexes the pawl 25b so as temporarily to remove the nose 25a from between the teeth. As will be described, the dial 21 is rotated so as correspondingly to rotate the gear 24 so one tooth passes the nose 25a.

After this passage of one tooth, the nose 25a once again is inserted between adjacent teeth of the gear 24. Thus, the dial 21 is rotatably advanced by an angular distance equal to the angular separation between adjacent teeth of the gear 24 upon the recording of a single circular track on the disc 3. After the next track is recorded, the dial 21 is driven once again to advance the gear 24 by this amount, and the pointer 23 is stepped to indicate the number of tracks in which information signals have been recorded.

As illustrated in Figure 4, an aperture 22 of the dial 21 is keyhole shaped, whereby the pointer 23 is formed by a recess or elongated notch portion of the aperture 22. That is, the pointer 23 is formed of an extension of the aperture 22, the latter being referred to herein as a recess. The purpose of this recess will best be understood by reference to Figures 6 and 7.

When the cartridge 1 is loaded into a suitable holder (which is not shown) of the magnetic recording/reproducing apparatus, a drive shaft 30 having a radial projection 31 is inserted into the aperture 22. As best shown in Figure 6, the projection 31 is received by the recess 23. The drive shaft 30 is partially surrounded by a collar or sleeve 32. The drive shaft 30, together with the projection 31,-is arranged to be moved in the axial direction thereof, or the vertical direction as viewed in Figure 7. Thus, the drive shaft 30 is movable with respect to the collar 32. As will be explained, this axial movement of the drive shaft 30 permits proper registration of the projection 31 with the recess 23.Once the proper registration has been obtained, the recording/reproducing apparatus is energized to rotate the disc 3 and record information signals in a respective track thereon through the window 4. The magnetic head of the recording/reproducing apparatus is mechanically linked to the drive shaft 30. The positioning of this magnetic head on a respective track of the disc 3 is effected when the projection 31 is inserted into the recess 23. Then, as the drive shaft 30 rotates, the mechanical linkage to the magnetic head serves radially to change the position of that head so as to record another track on the disc 3. Therefore, for proper recording, the projection 31 should engage the recess 23.

In a recording/reproducing apparatus with which the cartridge 1 is used, the drive shaft 30 normally is biased to an initial circumferential or angular position whereby the projection 31 is opposite a "0" indication on the index scale 28. If, however, one or more tracks have been recorded on the disc 3 contained within the cartridge 1 that is inserted into that recording/reproducing apparatus, the recess 23 initially would not be in registration or alignment with the projection 31 and thus, when the cartridge 1 is loaded, the dial 21 contacts the projection 31 so as to depress the drive shaft 30 within the collar 32. This depression of the drive shaft 30 serves to actuate a drive motor whereby the collar 32 is driven to rotate the drive shaft 30 and the projection 31 and also to advance the magnetic head from one track to the next along the disc 3.When the drive shaft 30 has been suitably driven so as to position the projection 31 in alignment with the recess 23, an upward spring-bias exerted on the drive shaft 30 permits the projection 31 to be inserted into the recess 23 and thus deactuate the drive motor.

Consequently, the projection 31 now is in proper driving engagement with the dial 21 and, moreover, the magnetic head is positioned opposite the proper track on the disc 3. A recording operation now may commence. At the completion of that recording operation, the collar 32 is driven by the drive motor so as to rotate the drive shaft 30 and the projection 31, thereby advancing the dial 21 such that the recess 23 now points to the number of the last track which has been recorded. Also, the magnetic head is advanced so as to be positioned to record the next track on the disc 3.

It should be recognized that the collar 32 is rotatably driven by an angular distance which corresponds to the angular separation between the adjacent teeth of the gear 24. Hence, the dial 21 is rotated by a unit increment after the track has been recorded. Preferably, this unit increment is proportional to the indication on the index scale 28 of a single track. That is, the angular distance between the angular teeth of the gear 24 is proportional to the angular distance between indications on the index scale 28, thereby providing incremental step-wise indications of the number of tracks which have been recorded.

From the foregoing description, it is recognized that the recess 23 of the dial 21 functions not only to receive the projection 31 of the drive shaft 30 but, also, to indicate the number of tracks which have been recorded on the disc 3. The dial 21 rotates in an incremental, step-wise manner by an angular distance which corresponds to an increment on the index scale 28. Moreover, the linkage between the drive shaft 30 and the magnetic head functions to prevent recording until the projection 31 is in engagement with the recess 23. This prevents the recording on the same track of new information which would destroy the information which had been recorded previously in that track. After a track has been recorded, the dial 21 is rotated so as to position the recess 23 opposite the next indication on the index scale 28. Hence, the dial 21 and the index scale 28 co-operate to display an indication of the number of tracks which have been recorded on the disc 3. Such indications may be analogous to the indications normally provided on photographic film which apprises the user of either the number of pictures which he has taken or the number of pictures which remain available on that film.

Claims (15)

1. A magnetic disc cartridge comprising a jacket for containing a rotatable magnetic disc, said disc having a hub member for receiving a drive member to rotate said disc to record information in circular tracks on said disc, an opening in said jacket through which said hub member is accessed, and indicator means on said jacket for indicating the member of tracks in which information has been recorded.

2. A cartridge according to claim 1 wherein said indicator means comprises a circular dial, a pointer associated with said dial, and an index scale for providing track member indications, said dial and said index scale being relatively movable with respect to each other.

3. A cartridge according to claim 2 wherein said dial is rotatably mounted in said jacket, and said jacket is provided with a further opening for receiving means to rotate said dial.

4. A cartridge according to claim 3 wherein said dial is provided with a recess for receiving a projection on said means to rotate said dial, such that the rotation of said projection rotatably drives said dial.

5. A cartridge according to claim 4 wherein said recess is said pointer.

6. A cartridge according to claim 3 wherein said indicator means further comprises releasable locking means provided in said jacket for releasably locking said dial at discrete rotary positions.

7. A cartridge according to claim 6 wherein said dial includes a rotatable gear having peripheral teeth, and said releasable locking means comprises resilient pawl means for insertion between adjacent teeth to lock said rotatable gear and said dial at the then-present position thereof.

8. A cartridge according to claim 7 wherein said jacket includes spaced apart top and bottom walls defining a space for said magnetic disc, and further including means for mounting said resilient pawl means on the inner surface of one of said walls.

9. A cartridge according to claim 8 wherein said resilient pawl means comprises a resilient arm having a nose portion for insertion between adjacent teeth of said rotatable gear member.

10. A cartridge according to claim 9 wherein said means for mounting said resilient pawl means comprises a mounting block mounted on said inner surface of said one wall, said mounting block and said resilient arm being of unitary construction with said resilient arm depending from said mounting block.

11. A cartridge according to claim 8 wherein said dial is formed on said rotatable gear member and is of unitary construction therewith.

12. A cartridge according to claim 11 wherein said gear is symmetrically disposed with respect to said dial, such that substantially equal portions of said dial extend above and below said gear.

13. A cartridge according to claim 7 wherein adjacent peripheral teeth of said gear are angularly spaced apart by a distance corresponding to the separation between adjacent tracks on said disc.

14. A cartridge according to claim 13 wherein said track member indications are angularly spaced apart from each other by an integral multiple of the angular separation between adjacent peripheral teeth of said gear.

15. A magnetic disc cartridge substantially as hereinbefore described with reference to the accompanying drawings.