NO821864L - MAGNETIC PLATE CARTRIDGE WITH TRACK INDICATING DEVICE. - Google Patents

Description

The invention relates to a magnetic disk cassette and more specifically such a cassette which is formed by a case or casing in which a rotatable magnetic disk or magnetic disk is placed, the cassette being used in an electronic still camera's recording/reproduction device, and where the casing has an indicator for indicating the number of still images that have been registered.

Rotatable magnetic disks or magnetic plates have been used for recording information in different types. of devices. For example, in computer systems, word processors and the like are magnetic disks, known as "diskettes",

have been used for recording information signals. Such diskettes are typically housed in a case which serves to protect the magnetic, information-recording surfaces of the magnetic disk and also to prevent the magnetic disk from being folded, creased or seriously damaged in any other way.

Such a protective case has a window through which one or more magnetic transducers can be inserted to make magnetic contact with the disc's magnetic surface for recording or reproduction of information signals on or from this. These information signals are recorded in a number of circular recording tracks.

A magnetic disk of the above type has no indication on the case or the disk recording device to inform a user of the number of tracks on which information signals have been recorded. This information is usually produced by the registration device which can keep track of the tracks that have been used as well as the tracks that are available for later registration. In most information registration systems, however, the user is not informed of this counting information and he cannot therefore be aware of the actual registration capacity that has been consumed or that remains available.

It is therefore an object of the invention to provide an improved magnetic disk cassette with an indicator arranged thereon which directly informs a user of the recording capacity of the magnetic disk which has been used up and/or which remains available for further recording.

Another object of the invention is to provide an improved magnetic disk cassette with a case on which the said indicator is arranged.

A further object of the invention is to provide a magnetic disk cassette with a case containing an indicator that directly informs a user of the number of tracks on the magnetic disk where information signals are already

they have been registered.

Yet another object of the invention is to provide a magnetic disk cassette with a case containing an indicator which has a relatively simple construction, which is easy to manufacture and which functions in a simple way to inform a user of the number of tracks on the magnetic disk where information signals have been recorded .

Various other purposes as well as advantages and special features of the invention will be clear from the following detailed description, and the new special features are specifically indicated in the subsequent patent claims.

According to the invention, a disk cassette is provided for recording a magnetic disk, where the disk is of the type which has a hub which is arranged to receive a rotatable drive shaft and thereby rotate the magnetic disk so that information signals can be recorded in individual, circular tracks. The cassette is formed by a case which surrounds and protects the magnetic plate and which comprises an opening through which the aforementioned drive shaft can pass to be received by the magnetic plate's hub. The case also has an indicator that gives a direct indication of the number of tracks in which information signals have already been registered. The indicator thus gives an indication of the recording capacity of the disc that has been consumed or that alternatively remains for further recording.

According to one aspect of the invention, the information indicator comprises a dial and an index scale, the latter having markings indicating the number of tracks that can be registered on the magnetic plate. The dial and the index scale are movable relative to each other, and the dial comprises a pointer adapted to point to successive track number markings on the index scale.

In one embodiment of the invention, the dial is rotatable and includes a recess for receiving a drive pin which belongs together with the recording and/or reproduction device in which the magnetic disc cassette is used. This recess not only serves to turn the dial when the drive pin rotates, but also acts as the aforementioned dial.

In a particular embodiment of the invention, the dial is mechanically connected to a gear element, and a releasable locking device can be inserted between adjacent teeth on the gear element, so that the dial can be releasably locked in any available angular position. The dial is released when it is driven to rotate, so that successive teeth of the gear member are allowed to pass the locking device. The releasable locking element is preferably in the form of a resilient locking hook which is attached to an inner surface of the case.

The invention will be described in more detail below with reference to the drawings, where fig. 1 shows a plan view of the case or cassette which contains a magnetic disk and is shown partly in section, fig. 2 shows a plan view of the opposite side. of the case or cassette shown in fig. 1, fig. 3 shows an enlarged cross-sectional view along the line 3 - 3' in fig. 1, fig. 4 shows an enlarged, incomplete plan of the upper side of the case where the upper wall has been removed, fig. 5 shows an enlarged cross-sectional view along the line 5-5' in fig. 4, fig. 6 shows an enlarged, incomplete plan of the upper side of the case where the upper wall has been removed and where an indicator drive pin has been inserted into an opening, and fig. 7 shows an enlarged cross-sectional view along the line 7 - 7' in fig. 6.

From fig. 1. can be molded from suitable plastic and have opposite walls 2a and 2b between which a disk. 3 of magnetic material is freely rotatable. The diskette or disk 3 has a suitably small diameter, for example no more than approx. 50 mm, so that the case 2 can have a correspondingly small size, for example measuring 60 x 54 x 3 mm, for convenient handling, storage and shipping, e.g. per post, and for the use of a very compact recording and/or reproduction device which can, for example, form part of a still image camera which is not significantly larger than a monocular 35 mm single-lens reflex camera. The case's two opposite walls 2a and 2b have mutually aligned openings or windows 4 which, in the radial direction of the plate 3, extend at least to the inner and outer effective limits of circular recording tracks on the plate's recording surface 3a. iA hatch element 5 is located on each side of the plate 3 and is displaceable along an edge part of the case 2, the parts of the hatch element 5 being arranged against the inner surfaces of the walls 2a and 2b for sliding movement in the direction of an arrow 5a in fig. 1 from the shown closed position to an open position in which the hatch element 5 clears the windows 4. A tension spring 5b may be connected to the hatch element 5 to force it to its closed position, and a projection 5c extends outwards from the hatch element 5 and can be influenced by a suitable element on the device which records the cassette 1 in the camera not shown, in order to open the hatch element 5 when the cassette 1 is introduced into the recording and/or playback apparatus. - When the hatch element 5 is thus open, one or more magnetic heads can extend through one of the windows 4 for magnetic recording of information signals which, for example, represent a still image, in a selected track of several concentric, circular recording tracks on the plate's surface 3a (fig. 3) .

A hub 6 is arranged in the center of the plate 3 and has a through hole 7 for receiving a drive shaft (not shown) in the recording and/or reproduction apparatus. The hole 7 is preferably non-circular to define two mutually angled setting surfaces "8; which are arranged to form tangential engagement with the circular circumference of the drive shaft for centering the rotatable plate 3 in relation to the central axis of the drive shaft. A resilient chord element 9 extends over the hole 7 on the side of this which lies opposite the setting floats 8. Behind this cord element 9 there is an elongated hole 10 which extends along the element 9 on the side of it which is opposite to the surface 9a of the element which faces the setting floats 8. The described hub 6 can easily be molded from suitable plastic material which further makes the springy element 9 elastic. The hole 7 is dimensioned so that the springy element 9, when the drive shaft is inserted in the hole, is bent by the shaft in a direction away from the setting floats 8, as that the surfaces 8 are kept in constant contact with the outer circumference of the drive shaft.

The hub 6 is further shown provided with a ring-shaped magnetic element 11 which is suitably mounted on the underside of the hub. A magnetic detection pin 13 for use in detecting the rotation phase of the plate 3 or

-- position, and a non-magnetic balancing pin 14 of essentially the same weight as the pin 13, is embedded in the hub 6 in

diametrically opposed positions. In one embodiment, at least three supports or feet 16 extend from the underside of the hub 6 in angularly equally spaced positions that lie radially outside the ring-shaped magnetic element 11. The bottom surfaces 16a of the supports 16 protrude somewhat from the underside of the hub 6 and form a reference level with respect to the plate 3 magnetic recording surface 3a. In another embodiment, the supports or feet 16 are replaced by a continuous ring-shaped edge. The casing's 2nd walls 2a and 2b have central openings 17a and 17b in which the hub 6 is freely rotatable.

In accordance with the invention, the cassette's

1 case 2 an indicator 20 which is designed to show an indication of the part of the plate 3's capacity that has been consumed, or alternatively of the position of the plate capacity that remains available for further registration. More specifically, the indicator 20 gives an indication of the number of tracks in which information signals have been recorded on the disc. From fig. 1 and 2, it appears that the indicator comprises a rotatable dial 21 and an index scale 28 which is arranged circularly around the dial 21, with a hand connected to the dial being arranged to point to an indication on the index scale, which indication represents the number of tracks that have been registered on plate 3.

In the embodiment shown, the dial 21 is arranged to rotate relative to the index scale 28. In a

alternative embodiment, the index scale can be arranged on the rotatable dial and thus be rotatable in relation to a pointer which is fixedly arranged on the case 2. It is thus clear that the dial 21 and the index scale 28 are rotatable

relative to. each other.

As shown in fig. 1, the index scale 28 preferably has markings or signs which give a numerical indication of the number of tracks that have been recorded on the disc. As an example, the disc 3 can have a recording capacity of the order of 50 tracks. The index scale 28 is thus provided with numerical indications from track 1 to track 50. Suitable marks or graduations may be arranged between the separate numbers indicated in fig. 1. These marks can represent every track, every second track or similar.

The case 2 has a further opening 27 through which the dial 21 can for example be reached by a suitable drive mechanism described below. The dial 21 is located in the space delimited by the separate, upper and lower walls 2a and 2b, and is arranged for turning or rotation in this. The below with reference to fig. 4 described pointers can be observed through the opening 27a in the upper wall 2a, and the pointer disk itself can be driven by a suitable device which engages with the pointer disk through an opening 27b in the lower wall 2b.

As best shown in fig. 4 and 5, the dial 21 is mechanically connected to a gear element 24 which has teeth around its circumference. In the preferred embodiment, the indicator disk 21 and the gear element 24 are a single construction formed of suitable plastic. Alternatively, the gear element 24 can be connected to the dial 21, for example by means of a suitable mechanical transmission.

In an embodiment where the dial and the gear element are a single construction, the gear element is designed symmetrically in relation to the dial, so that equal parts of the dial are located above and below the gear element, as shown in fig. 5. The dial can be regarded as the central hub of the gear element. In the one in fig. 5, the upper and lower surfaces of the dial 21 have ledges for storage in the openings 27a and 2b of the upper and lower walls 2a and 2b, respectively. 27b.. In an alternative embodiment, the ledges can be looped when the upper and lower surfaces of the gear wheel 24 lie against the inner surfaces of the upper and lower walls of the case 2, while the dial 21 is situated in the openings 27a and 27b.

A releasable locking device 25 cooperates with the gear element 24 to lock this and thus the dial 21 in the relevant position of the dial. As later described, the disk 21 can be driven to rotate by a suitable drive mechanism which is arranged in the recording and/or reproducing apparatus together with which the magnetic disk cassette is used, for updating the indication provided by the pointer 23 as the number of circular tracks in which information has already been registered, increases. The dial 21 is turned or rotated in steps, and the releasable locking device 25 serves to hold the dial in place in the last position to which it has been rotated. This makes it possible to remove the magnetic disk cassette from the magnetic recording and/or reproducing apparatus while the correct indication is retained by the last track in which recording has taken place immediately before the cassette's removal. In other words, the dial 21 is prevented from unintentional rotation when the magnetic disc cassette is handled, stored or transported.

In the embodiment shown, it is releasable. locking device 25 formed by a springy locking hook 25b which ends in a lug 25a which can be inserted between adjacent teeth of the gear element 24. The locking hook 25 is formed in one piece with a mounting block portion 25c of a suitable plastic. As shown, the catch 25b is arranged under the mounting block 25c. The mounting block is designed to be mounted on the inner surface of, for example, the upper wall 2a of the case. Suitable mounting elements, such as screws 26, can be used. Alternatively, mounting pins can be formed in one piece with the inner surface of the upper wall of the case 2 and the mounting block 2 5c have suitable openings just in front of these mounting pins, so that the mounting block is mounted by means of a press fit.

The springy or elastic detent 25b presses the pawl 25a into engagement with the teeth of the gear element 24. When the gear member is driven to rotate (as described below), the movement of the teeth deflects the detent 25b so that the lug 25a is temporarily removed from the space between the teeth. As described below, the dial 21 is turned in a similar way to turn the gear wheel 24, so that a tooth passes past the lug 25a. After a tooth has passed, the shoe 25a is re-inserted between adjacent teeth on the gear element 24. The dial 21 is thus turned forward an angle equal to the angle difference between adjacent teeth on the gear element, after the registration of a single circular track on the plate 3. When the next track has been registered, the dial 21 is driven forward once more to advance the gear element this angle, and the pointer 23 is advanced to indicate the number of tracks in which information signals have been registered.

As shown in fig. 4, the opening 22 in the pointer disk 21 is keyhole-shaped, the pointer 23 being formed by a recess or an elongated notch in this opening. The pointer 23 is included. other words formed by an extension of the opening 22, which extension is referred to here as an outlet. The purpose of this removal will be best understood with reference to fig. 6 and 7.

When the magnetic disk cassette 1 is inserted into a suitable holder (not shown) in the magnetic recording/reproducing apparatus, a drive shaft 30 with radial projection 31 is inserted into the opening 22. As shown in fig. 6, the projection 31 is occupied by the recess 2 3., 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 its axial direction or the vertical direction, as shown in fig . 7. The drive shaft 30 is thus movable in relation to the collar 32. As described below, this axial movement of the drive shaft allows a correct alignment of the projection 31 with the recess 23. As soon as the correct alignment has been achieved, the recording/reproducing apparatus is activated to rotate the disc 3 and register information signals in a special track on this through the window 4. The magnetic head of the recording/reproducing device is mechanically connected to the drive shaft 30. The setting of this magnetic head on a special track on the disc 3 is carried out when the projection 31 is inserted into the socket 23. After as the drive shaft 30 then rotates, the mechanical coupling to the magnetic head serves to radially change the position of the head for recording in another track on the disc. For correct registration, the protrusion 31 must therefore form an engagement with the recess 2 3.

In a recording/reproducing device in conjunction with which the magnetic disk cassette is used, the drive shaft 30 is normally biased to an initial angular position where the projection :31 is located just in front of a "0" indication on the index scale 28. However, if one or more tracks have been: recorded on the magnetic disk that is placed in the magnetic disk cassette inserted in the recording/reproducing device, the socket 2 3 from the beginning will not be directly in front of or be aligned with the projection 31, and when the magnetic disk cassette is inserted, the dial 21 will thus form contact with the projection 31 and depressing the drive shaft 30 in the collar 32. This depressing of the drive shaft serves to activate a drive motor, so that the collar 32 is driven to rotate the drive shaft 30 and the projection 31 and also feed forward the magnetic head. from one slot to the next along the plate 3. When the drive shaft 30 has been driven sufficiently to set the projection 31 in alignment with the recess 23, a spring bias applied to the drive shaft allows the projection to be guided into the recess and thus disable the aforesaid drive motor. The projection 31 is now consequently in the correct driving engagement with the index disc 21, and furthermore the magnetic head is set against the correct groove on the plate 3. A registration operation can now begin. At the end of this registration operation, the collar 32 is driven by the above-mentioned drive motor to rotate the drive shaft 30 and the projection 31 and thus advance the dial 21 so that the recess 23 now points to the number or figure for the last track that has been registered. The magnetic head is also moved forward to be adjusted

for registration in the next track on the magnetic plate 3.

It is realized that the collar 32 is driven rotationally at an angle which corresponds to the angle difference between adjacent teeth on the gear wheel 24. The dial 21 is thus rotated one increment unit after registration has taken place in the track. This increment unit is preferably proportional to the indication of a single track on the index scale 28. In other words, the angle between the teeth of the gear wheel 24 is proportional to the angle between the indications on the index scale 28, so that incremental step-by-step indications are provided by the number of tracks in which registration has occurred.

From the above description it appears that the dial 21's recess 23 not only serves to accommodate the drive shaft 30's projection 31, but also to indicate the number of tracks in which registration has taken place on the dial 3. The dial 21 is turned or rotated in an incremental, stepwise manner over an angle which corresponds to an increment on the index scale 28. The connection between the drive shaft 30 and the magnetic head also serves to prevent registration, until the protrusion 31 forms an engagement with the recess 23. This prevents registration on one and the same track of new information, which would destroy the information that have previously been registered in this track. After registration has taken place in a track, the dial 21 is turned to set the socket 23 just opposite the next indication on the index scale 28. The dial and the index scale thus cooperate to show an indication of the number of tracks in which registration has taken place on the magnetic plate 3. These indications can be analogous to the indications that are normally provided on photographic film, which,, indications inform the user either of the number of pictures that he has taken, or the number of pictures that remain available on the film. Expressed in another way, the outlet 2 3 cooperates with the index scale 2 8 to inform the user of the remaining capacity of the magnetic plate 3 which is available for further registration.

Claims (14)

1. Magnetic disc cassette of the type having a case for recording a rotatable magnetic disc having a hub element for recording a drive element for rotation of the disc for recording information in circular tracks on the disc, and comprising an opening through which the hub element is available, characterized by indicator bodies' on the case for indicating the number of tracks in which information has been registered. 2. Cassette according to claim 1, characterized in that the indicator means comprise a circular dial, a pointer contiguous with the dial and an index scale for providing track number indications, the dial and the index scale being movable in relation to each other. 3. Cassette according to claim 2, characterized in that the indicator disc is rotatably mounted in the case which has a further opening for accommodating organs for turning the indicator disc. 4. Cassette according to claim 3, characterized in that the dial has a recess for receiving a projection on the said device for turning the dial, so that a rotation of the projection drives the dial to rotate. 5. Cassette according to claim 4, characterized in that the take-out constitutes the aforementioned display. 6. Cassette according to claim 3, characterized in that the indicator means further comprise releasable locking means which are arranged in the case to releasably lock the dial in separate rotating positions. 7.. Cassette according to claim 6, characterized in that the dial comprises a rotatable gear element with teeth on the circumference, and that the releasable locking means comprise an elastic hook member for insertion between adjacent teeth for locking the rotatable gear element and the dial in their current position. 8. Cassette according to claim 7, characterized in that the case comprises separate upper and lower walls which delimit a space for the magnetic plate, and further comprises means for mounting the elastic hook means on the inner surface of one of the walls. 9. Cassette according to claim 8, characterized in that the elastic hook means comprises an elastic arm with a claw part for insertion between adjacent teeth on the rotatable gear element. 10. Cassette according to claim 9, characterized in that the means for mounting the elastic hook means comprise a mounting block which is mounted on the inner surface of the aforementioned one wall, the mounting block and the elastic arm being an undivided construction and the arm extending down from the mounting block. 11. Cassette according to claim 8, characterized in that the dial is formed on the rotatable gear element and is made in one piece with this. 12. Cassette according to claim 11, characterized in that the gear element is arranged symmetrically in relation to the dial, so that basically equal parts of the dial extend above and below the gear element. 13. Cassette according to claim 7, characterized in that adjacent peripheral teeth on the gear element are angularly separated by a distance that corresponds to the distance between adjacent tracks on the plate. 14. Cassette according to claim 13, characterized in that the track number indications are angularly separated from each other by an integer multiple of the angle between mutually adjacent peripheral teeth on the gear element.