GB1567818A

GB1567818A - Clamping device for disc-shaped memory sheets

Info

Publication number: GB1567818A
Application number: GB5176977A
Authority: GB
Original assignee: International Standard Electric Corp
Current assignee: International Standard Electric Corp
Priority date: 1976-12-22
Filing date: 1977-12-13
Publication date: 1980-05-21
Also published as: BR7708352A; DE2708798A1; JPS53101403A; DE2708798B2; NL7714297A; CH625360A5; IT1088779B; DE2708798C3

Abstract

The floppy disks have a central hole in the middle. By means of this hole, the disk is first of all centred and then firmly clamped by a conical clamping part (16) and a pot-shaped clamping part (12). The conical clamping part can be driven in both directions of rotation. Depending on the direction of rotation, it thereby executes a forward or rearward axial movement, for example as a nut part on a spindle. One end position is the clamping position, the other the opening position. The axial movement is derived from the rotational movement via a torque limiter. A smaller space requirement than in the case of known devices is necessary and the disk is treated gently in an optimum way during centring and clamping. According to one embodiment, the axial travel is reduced by dividing the centring operation into a coarse centring and a fine centring. The coarse centring is performed by a flat centring piece arranged eccentrically on the end face of the part, the fine centring is performed by means of the cone of the part. This cone is very short in comparison with the first embodiment. The consequence is a smaller axial travel, a flatter part and a narrower friction shoulder, and consequently an appreciably narrower clamping device in the axial direction. <IMAGE>

Description

(54) CLAMPING DEVICE FOR DISC-SHAPED MEMORY SHEETS (71) We, INTERNATIONAL STANDARD ELECTRIC CORPORATION, a Corporation organised and existing under the laws of the State of Delaware, United States of America of 320 Park Avenue, New York 22. State of New York, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to data storage disk devices.

Clamping devices are known which consist of one frusto-conical and one pot-shaped clamping member which, by being adjustable in relation to one another and by passing through a hole in the centre of a data storage disk, first serve to centre the disk and, thereafter, to clamp it firmly between them, both clamping members being rotationally mounted, and one member being capable of being driven. These are chiefly used for interchangeable data storage disks which are contained in a protective envelope, openings in the envelope providing access to the data storage disk. This kind of data storage disk has become known under the name floppy disk, and is described in detail in the US Patent No.

3,668,658.

From conventional clamping devices it is known to drive either the frusto-conical clamping member as is the case, for example, with the subject matter of the German published patent application (DT-OS) 2,330,358, or to drive the pot-shaped clamping member, as has become known, for example, from the German printed patent application (DT-AS) 2,330,818.

In both types the driven clamping member is stationary, while the other clamping member is mounted so as to be capable of being swivelled relative to is in such a way that the two clamping members may be disengaged for the purpose of inserting or removing a data storage disk. In the first-mentioned case, besides the pot-shaped clamping member, the guide shaft of the data storage disk must also be swivelled for lifting the sheet off the stationary frusto-conical clamping member.

This opening movement, in addition to the volume of the equipment, calls for a correspondingly large space. This may have a distrubing effect in equipments which are cramped for space, and an automatic interchange of the data storage disk is also rendered more difficult.

By swivelling the frusto-conical or potshaped clamping member into position, the data storage disk is centered by the cone entering into the hole in the centre. In so doing, the frusto-conical member is not rotated.

Accordingly, there is caused a static friction between the inner rim of the disk and the cone.

In conjunction with the swivel movement, this may easily cause the contours of the hole in the centre to be damaged, deformed, or subjec ted to increased wear. This has the consequence of a defective centering resulting in an out-of centre running as well as in inadmissible track deviations.

According to the present invention there is provided a centering and clamping device for a data storage disk having a hole in its centre, the device comprising one frusto-conical and one pot-shaped clamping member which, being movable in relation to one another and, in use, engaging the hole in the centre of the disk, thereby centre the disk and clamp it firmly between them, both clamping members being mounted so as to be rotatable and one member capable of being driven so as to rotate the disk clamped between the two clamping members, wherein the two clamping members are axially permanently aligned with one another, the frusto-conical clamping member being capable of being driven in either direction of rotation wherein the frusto-conical clamping member, depending on its direction of rotation, perfonns an axial movement either towards or away from the pot-shaped member to clamp or release the disk, with each of the movements ending in a limiting axial stop position. and wherein this axial movement of the frusto-conical clamping member is derived from its rotary movement via a torque limiter.

The advantages achieved by the invention are that, in particular only a sliding friction occurs between the disk and the rotating frusto-conical clamping member during the centering. The forces acting upon the rim of the disk in the course of this, are substantially smaller than in the case of a static friction.

Because of the axial displacement of the frustoconical clamping member. a mounting of the one or the other clamping member so that it can be swung away from the other is dispensed with, so that the device takes up less space in an installation. Moreover, an automatic interchange of the memory sheets can be realised in a simple way.

Embodiments of the invention are described below with reference to the accompanying drawings, in which: Figure 1 is the schematical representation of a conventional type of centering and clamping device for data storage disks; Figure 2 is the schematical representation of a first embodiment of a centering and clamping device for a data storage disk; Figure 3 shows the clamping device accord ing to Figure 2 in detail; and Figures 4 and 5 are two views of a second embodiment of a centering and clamping device for a data storage disk.

The clamping devices to be described hereinafter are particularly intended for data storage disks which, as already mentioned hereinbefore, are known as floppy disks. Since the floppy disk (also known as diskette, flexible disk or minidisk) in its protective envelope, has a lateral play of several millimeters, a proper alignment of the floppy disk cannot be effected by means of the envelope alone.

This has led to the development of devices such as that disclosed in the German printed patent application (DTAS) 2,330,818 and schematically shown in Figure 1 of the accompanying drawings. Here, a frusto-conical clamping member 5 in combination with a pot-shaped hollow, cylindrical clamping member 4 closed at one end causes the automatic centering of the floppy disk immediately prior to the disk being clamped. The pot-shaped clamping member 4 is capable of being driven in the direction as indicated by the arrow. It is mounted so as to rotate, but not to move axially, in a stationary frame member 1. A pair of guide surfaces 3 takes care of holding the inserted floppy disk firmly in position, so that it is positioned closely in front of the open end of the pot-shaped clamping member 4. For inserting or removing the floppy disk, the frusto-conical clamping member 5 is mounted so as to rotate, and to have a limited resilient axial movement against a spring 6, within a part 2 of the device which is capable of being swung around a hinge. Figure 1 shows the open position in which a space exists between the pot-shaped and the frusto-conical clamping member, permitting a floppy disk to be freely inserted or removed. In the closed condition in which the clamping member 5 engages the clamping member 4, the device has an overall width X, while the overall width Y is required in the opened state. This width Y determines the installation width, When the part 2 of the device is moved to the closed position, the frusto-conical clamping member 5 is brought into engagement with the pot-shaped clamping member 4. When the floppy disk is inserted this member 5 with its frusto-conical surface is in touch with the rim of the hole in the centre of the eccentrically displaced floppy disk. As member 2 moves to the closed position the floppy disk is shifted into the centric position by the clamping member 5 and, finally, under the pressure exerted by the spring 6, clamped between the driven clamping member 4 and a collar portion 5a of the frustoconical clamping member 5.

Figure 2, in a schematical representation, shows a centering and clamping device according to an embodiment of the present invention. In order to enable a comparison with the device according to Figure 1, the drawing has been based on the same scale proceeding from an overall width X of the device. Unlike the device shown in Figure 1, the width X determines the installation width since the side walls of the frame 10 of the device are fixed in relation to one another. A pot-shaped clamping member 12 and a frusto-conical clamping member 16 are axially aligned in relation to one another and each held in positior on opposite side walls of the frame 10 of the device. The pot-shaped clamping member 12 is mounted free to rotate on a bolt 22 while the frusto-conical clamping member 16 is mounted to rotate on a spindle, and is rotated by the action of a friction wheel 21.

For one direction of rotation of this friction wheel, the frusto-conical clamping member 16 is moved into the retracted position shown, in which a floppy disk can be inserted, while for the opposite direction of rotation the member 16 is moved by a continuous helical advance rotation, into engagement with the pot-shaped clamping member 12. A floppy disk placed therebetween, is now centered via its hole in the centre, in the most accurate way, and clamped in position in the limiting axial stop posi tion between the two clamping members 12 and 16.

Figure 3 shows, in a detailed representation, the clamping device of Figure 2 on an enlarged scale. Along a section line X-X in the axial direction, the clamping body comprising parts 16, 16a and 16b, movable in the axial direction, is divided into an upper and a lower half. The upper half is shown in the open or retracted position. The lower half shows the closed, advanced or clamping position of the two members 12 and 16, with a data storage disk 15 positioned therebetween, which is supported by means of its hole 15a in the centre, on the frusto-conical clamping member 16. This data storage disk 15 forms part of a floppy disk 14 which is retained between a pair of guide surfaces 13. A corresponding lateral guide and a supporting limit stop 10a effect an approximately centric position of the floppy disk 14 in relation to the clamping axis. Compared with this precentered position, the disk 15 may deviate by the lateral play inside the protec tive envelope of the floppy disk 14. The hole 1 5a in the centre of the disk 15 and the conical clamping member 16 are so dimensioned that, in the case of a largest possible displacement of the disk 15 with respect to the centred position, there is ensured from the beginning of the centering process a contactless engagement of the clamping member 16.

The pot-shaped clamping member 12, as already mentioned in connection with Figure 2, is mounted free to rotate on a bolt 22. For the purpose of self-centering with respect to the bolt 22, it only has a small play. This member is axially in alignment with the frustoconical clamping member 16 which, by means of a guide and threaded bushing 16b, is mounted rotatably and in an axially movable manner on a spindle 17. By means of the guide and threaded bushing 16b, the frustoconical clamping member 16 is accurately guided in a guide cylinder 1 lea forming part of a bearing bracket 11. The spindle 17 is supported at one end and, via a torque limiter, is in connection with one side wall of the frame 10 of the device. The torque limiter consists of a thrust ball bearing 18 which is fixed at one end of the spindle 17 so as to rotate therewith. The surface of this ball bearing 18 next to the spindle, is flat and in operative contact with a friction disk 19 which is slipped on to the spindle 17 in a freely rotatable manner. This friction disk 19 has an arresting arm 19a which engages in a recess 10b in the frame 10. Compression springs 20 are arranged between the bearing bracket 11 and the friction disk 19. They, on the one hand, provide the necessary friction force of the torque limiter and, on the other hand, urge the thrust ball bearing 18 against the side wall of the frame 10. The parts 18,19, and 20 together form a slipping-clutch torque limiter. Both the axial alignment and the holding in position of the spindle 17 and, consequently, of the thrust bearing 18 are effected with the aid of the guide and threaded bushing 16b.

As well as the guide and threaded bushing 16b, the frusto-conical clamping member 16 has a cylindrical collar member 16a. A friction wheel 21 is in operative contact with the outer surface of this cylindrical collar member 16a.

The width of this collar is at least equal to the largest axial movement of the clamping member 16 plus the width of the friction wheel 21. This friction wheel 21 is capable of being optionally driven in either direction of rotation.

To insert (or remove) a floppy disk 14 between (or from between) the pair of guide surfaces 13, the frusto-conical clamping member 16 must be in the retracted or open position, as shown in the upper half of Figure 3. This position is determined, for example, by the limit stop of the spindle 17 inside the threaded bore of the guide and threaded bushing 16b. If, in this open position, a floppy disk is inserted between the pair of guide surfaces 13, it will actuate a contact (not shown) on reaching the supporting limit stop 1 0a. This contact actuation sets in motion the automatic centering and clamping of the data storage disk 15. The drive to friction wheel 21 is turned on upon actuation of the contact and the friction wheel 21, as seen from the drive end of the shaft attached thereto, is driven in the anti-clockwise direction (arrow A), so that the clamping body comprising parts 16, 16a and 16b - when looked at from the same point of view - will rotate in the opposite (clockwise) direction. Since the spindle 17 is retained by the slipping-clutch torque limiter the frusto-conical damping member 16 rotates on the thread of the spindle 17, and advances into the hole 15a in the centre of the data storage disk 15. In the course of this forward movement, the data storage disk is brought into its centric position by means of the conical surface of the rotating clamping member 16. This movement is stopped as soon as the end surface of the cylindrical collar member 16a engages the data storage disk 15, and presses it against the end surface of the potshaped clamping member 12. This closed position is indicated in the lower half of Figure 3. Since no further axial movement is possible there is effected a clamping of the clamping body comprising parts 16, 16a and 16b to the spindle 17. This causes the spindle 17 to be taken along by the continuously-rotating clamping body upon overcoming the frictional forces of the slipping-clutch torque limiter. These frictional forces determine the contact pressure by which the data storage disk 15 is clamped between the two clamping members.

After information has either been written on or read from the data storage disk 15, the clamping of the disk 15 can be relieved by reversing the direction of rotation (arrow B) of the friction wheel 21. Upon the corresponding reversal of the direction of rotation of the clamping body comprising parts 16, 16a and 16b, the spindle 17 is no longer taken along therewith. Accordingly, rotation of the spindle 17 is stopped by the frictional forces, and the clamping body is retracted to its normal position. As soon as the clamping body reaches its limiting stop position on the spindle 17, the latter is taken along again by overcoming the frictional forces of the slipping-clutch torque limiter. In order to avoid unnecessary wear, a further contact may be actuated upon reaching the limiting stop position, causing the drive to be switched off.

Instead of the friction wheel drive, it is also possible to provide for a friction-belt drive. It is also possible to drive the clamping body comprising parts 16, 16a and 16b by making the cylindrical collar member 16a carry a toothed wheel portion which meshes with a toothed-wheel or toothed-belt drive.

The clamping device shown in Figure 4 differs from the embodiment of Figures 2 and 3 by having a frusto-conical clamping member 16 which, while maintaining the same conicity of the cone, is considerably reduced in length.

This reduction is made possible in that the cone of the clamping member 16 only effects a fine centering. On the end of the frusto-conical clamping member 16, for effecting the coarse or pre-centering, there is mounted an eccentrically arranged projection which, in the present example of embodiment, is a round flat stud 23. This stud 23 is arranged in such a way that it is, on the outside, flush with the edge of the frusto-conical portion 16. Its height corresponds to at least the thread pitch of a spindle 17 on which the clamping body comprising parts 16, 16a and 16b is capable of being axially readjusted by way of rotation. The clamping body comprising parts 16, 16a and 16b is driven by a friction wheel 21 I which is capable of being driven in both directions, and is in operative connection with the cylindrical attachment 1 6a of the clamping body comprising parts 16, 16a and 16b.

The frusto-conical clamping member 16 is opposed by a pot-shaped clamping member 12 which is mounted on the frame 10 of the device in a freely rotatable manner. When open, there is, between the end of this clamping member 12 and the stud 23, a space corresponding to the thickness of one floppy disk 14.

It is in alignment with lateral guides 13 into which the floppy disk 14 is inserted. According to Figure 5 this floppy disk 14 consists of a circular data storage disk 15, having a hole 15a in its centre, which is enclosed by a square protective envelope 24. This envelope, in turn, has a concentric (not shown) recess which is larger than the hole 1 5a in the centre, permitting the data storage disk 15 to be accessed from the outside. This data storage disk, inside the protective envelope 24, has a slight amount of play (back-lash) A and B about the centered position.

Because of the reduced length of the frustoconical clamping member 16 the displacement required to reach the clamping position is smaller than the displacement which is necessary in the embodiment of Figures 2 and 3. Accordingly also the width of the cylindrical attachment 1 6a can be narrower. Likewise, the pot-shaped clamping member 12 can be flatter because of the reduced depth of penetration of the frusto-conical clamping member 16 in its clamping position. Altogether the clamping device may thus be narrower by three times the amount of the axial reduction of the frustoconical clamping member 16a.

In the following, and with reference to Figure 5, the mode of operation of the described clamping device will now be explained. In the representation there is shown the arrangement according to Figure 4 in a front view as seen from the side of the disk on which the pot-shaped clamping member 1 2 is located, which member, for the sake of clarity, is not shown. The floppy disk 14 with its protective envelope 24 partly shown in a sectional representation, is laterally held in the guides 13. Supporting limit stops 10a restrict the distance of insertion. Compared with this fixing of the protective envelope 24 which is extensively centric in relation to the conical clamping member 16, the data storage disk 15 is permitted to assume the eccentric position allowed by the play A and B.

The centering of the data storage disk 15 displaced in this way in relation to the centre position, is effected in such a manner that the stud 23 on the end of the frusto-conical clamping member 16 will engage the hole 15a in the centre of the data storage disk 15 during the rotatory forward movement of the clamping body comprising parts 16, 16a and 16b at the latest after having performed one half of a rotation. In the course of completing the first rotation, the eccentrically rotating stud 23 will take the data storage disk along and bring it into a coarse or pre-centered position. This only differs from the centered position by half the diameter difference between the root and the top line of the portion of cone. In the course of this first rotation, the clamping body comprising parts 16, 16a and 16b, because of the threaded spindle bearing, has been displaced forwardly to such an extent that the short cone of the clamping member 16 will enter the area of the data storage disk 15. Because of the coarse or pre-centeringjust described, the portion of cone only has to perform the fine centering. Since, because of the pre-centering, the difference from the nominal position only amounts to some tenth of a millimeter, the portion of cone can be very short. The process of the fine centering is completed in the course of the second rotation of the clamping body comprising parts 16, 16a and 16b. The advance movement is terminated by a torque limiter as described in connection with Figures 2 and 3 upon reaching the clamping position (dashand-double-dot-line) in which the memory sheet 15 is firmly clamped in position between the ends of the cylindrical attachment 1 6a and the pot-shaped clamping member 12, and is thus caused to rotate together therewith.

In order to accelerate the pre-centering process, two studs 23 may be arranged diametrically, or three studs 23 may be arranged triangularly on the face side of the frustoconical clamping member 16 by being flush with the rim portion thereof. In this way the maximum angle of rotation, until a stud 23 is brought into engagement with the hole 1 Sa in the centre of the data storage disk 15, is reduced to one half or one third respectively.

Instead of the three studs 23, the centering piece may be a triangle whose corners are rounded and which are flush with the edges of the frusto-conical portion 16.

WHAT WE CLAIM IS: 1. A centering and clamping device for a data storage disk having a hole in its centre, the device comprising one frusto-conical and one pot-shaped clamping member which, being movable in relation to one another and, in use, engaging the hole in the centre of the disk, thereby centre the disk and clamp it firmly between them, both clamping members being mounted so as to be rotatable and one member capable of being driven so as to rotate the disk clamped betweent the two clamping members, wherein the two clamping members are axially permanently aligned with one another, the frusto-conical clamping member being capable of being driven in either direction of rotation, wherein the frusto-conical clamping member, depending on its direction of rotation, performs an axial movement either towards or away from the pot-shaped member to clamp or release the disk with eachof the movements ending in a limiting axial stop position, and wherein this axial movement of the frusto-conical clamping member is derived from its rotary movement via a torque limiter.

2. A device as claimed in claim 1 wherein the frusto-conical member is of sufficient length to perform both coarse and fine centering of the storage disk.

3. A device as claimed in claim 1, wherein the frusto-conical clamping member is only of sufficient length to effect fine centering, and carries on its end surface facing the pot-shped member at least one eccentric projection which effects the initial centering action, the height of said projection being at least equal to the axial advance movement of the frusto-conical clamping member in the course of one rotation, and said projection being flush with the conical surface of the frusto-conical member at least at one point.

4. A device according to claim 3, wherein the eccentric projection is a round, flat stud.

5. A device according to claim 4, wherein there are two studs arranged diametrically, or three studs arranged in a triangle.

6. A device according to claim 3, wherein the eccentric projections are the rounded corners of a triangle which are flush with the conical surface of the frusto-conical member, 7. A device as claimed in any preceding claim wherein the frusto-conical clamping member is mounted so as to be rotatable on a rotatable spindle, the spindle being in connection with a stationary part of the device through a slipping-clutch torque limiter, 8. A device as claimed in any preceding claim wherein the frusto-conical clamping member carries a cylindrical collar which is in a frictional or meshing connection with a driving means.

9. A centering and clamping device for a data storage disk having a hole in its centre, substantially as hereinbefore described with reference to Figures 2 and 3 or Figures 4 or 5 of the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. movement is terminated by a torque limiter as described in connection with Figures 2 and 3 upon reaching the clamping position (dashand-double-dot-line) in which the memory sheet 15 is firmly clamped in position between the ends of the cylindrical attachment 1 6a and the pot-shaped clamping member 12, and is thus caused to rotate together therewith. In order to accelerate the pre-centering process, two studs 23 may be arranged diametrically, or three studs 23 may be arranged triangularly on the face side of the frustoconical clamping member 16 by being flush with the rim portion thereof. In this way the maximum angle of rotation, until a stud 23 is brought into engagement with the hole 1 Sa in the centre of the data storage disk 15, is reduced to one half or one third respectively. Instead of the three studs 23, the centering piece may be a triangle whose corners are rounded and which are flush with the edges of the frusto-conical portion 16. WHAT WE CLAIM IS:

1. A centering and clamping device for a data storage disk having a hole in its centre, the device comprising one frusto-conical and one pot-shaped clamping member which, being movable in relation to one another and, in use, engaging the hole in the centre of the disk, thereby centre the disk and clamp it firmly between them, both clamping members being mounted so as to be rotatable and one member capable of being driven so as to rotate the disk clamped betweent the two clamping members, wherein the two clamping members are axially permanently aligned with one another, the frusto-conical clamping member being capable of being driven in either direction of rotation, wherein the frusto-conical clamping member, depending on its direction of rotation, performs an axial movement either towards or away from the pot-shaped member to clamp or release the disk with eachof the movements ending in a limiting axial stop position, and wherein this axial movement of the frusto-conical clamping member is derived from its rotary movement via a torque limiter.

6. A device according to claim 3, wherein the eccentric projections are the rounded corners of a triangle which are flush with the conical surface of the frusto-conical member,

7. A device as claimed in any preceding claim wherein the frusto-conical clamping member is mounted so as to be rotatable on a rotatable spindle, the spindle being in connection with a stationary part of the device through a slipping-clutch torque limiter,

8. A device as claimed in any preceding claim wherein the frusto-conical clamping member carries a cylindrical collar which is in a frictional or meshing connection with a driving means.