JPH03168967A - Disk clamping device - Google Patents

Abstract

PURPOSE:To obtain the disk clamping device in a simple assembly process, having a permanent magnet which can hardly fall off by attractively fixing the permanent magnet with magnetic attraction force operated between the permanent magnet and a ferromagnetic body. CONSTITUTION:A clamper 21 has an opening in both upward and downward directions, and its lower diameter is of a large and approximately bowl shape, and then a discoid steel plate 22 is bonded on an upper part of the clamper 21. A clamp pin 23 is fixed in the downward direction in the center of the steel plate 22, and the permanent magnet 24 in a cylindrical shape is inserted between the clamp pin 23 and the clamper 21, and is attractively fixed to the steel plate 22 by the magnetic attraction force. Then, when a disk D is clamped, attraction force is operated by the permanent magnet 24 between itself and a yoke 7, whereas since the permanent magnet 24 is nearer the steel plate 22 than the yoke 7, the attraction force with the steel plate 22 is far stronger, so that the permanent magnet 24 never falls away from the steel plate 22.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a disk clamping device for clamping a disk-type recording medium onto a turntable using the magnetic adsorption effect of a permanent magnet.

[Prior Art] Fig. 4 shows a cross-sectional view of a conventional disk clamp device.The disk clamp device is placed on top of the device and pressed by a clamper 2 from above. The turntable l is fixed to the base of a spindle 4 which is rotationally driven by a spindle motor 3, and a Taber cone 5 is attached to the spindle 4 so as to be slidable in the axial direction.
A compression spring 6 is interposed between the Taber cone 5 and the turntable 1. An annular yoke 7 made of a ferromagnetic material is attached around the tip of the spindle 4, and a guide hole 8 is formed in the top of the spindle 4. On the other hand, at the center of the clamper 2, a clamp bin 9 that fits into the guide hole 8 of the spindle 4 protrudes, and around the clamp bin 9, an annular permanent magnet IO that applies an attractive force to the yoke 7 is fixed by adhesive or the like. has been done.

When the disc D is placed on the turntable 1, the Taber cone 5 fits into the center hole Da of the disc D. Historically, the clamp pin 9 is inserted into the guide hole 8 at the tip of the spindle 4.
Place the clamper 2 so that it fits into the Taber cone 5.
The disk D is clamped between the clamper 2 and the turntable 1 due to the magnetic adsorption effect acting between the disk D and the yoke 7.

FIG. 5 shows a second conventional example, in which a disk D is provided with a hub Db on both the front and back sides around the center hole Da, and a steel plate Dc is attached to the surface of the hub Db. . The turntable 11 is fixed to the base of a spindle 12 that is rotationally driven by a spindle motor 3, and has a recess 1 in the center with an inner diameter larger than the outer diameter of the hub Db.
3, and an annular permanent magnet l4 is bonded around the spindle l2 protruding from the center on the bottom surface of the recess l3.

In this case, the disk D is placed on the turntable l1 so that the spindle 12 fits into the center hole Da, and the permanent magnet 14 on the turntable l and the disk D
The disk D is clamped on the turntable 1i by the magnetic adsorption effect that acts between the disk D and the steel plate Dc on the hub Db.

[Problems to be Solved by the Invention] However, in the above-mentioned first conventional example, since the permanent magnet 10 is always attracted to the yoke 7 when the disk D is clamped, the permanent magnet 10 is made of resin or a light metal such as aluminum or magnesium. There is a risk that the permanent magnet 10 may fall off due to deterioration of the adhesive to the clamper 2. Similarly, in the second conventional example shown in FIG. 5, there is a risk that the permanent magnet 14 may peel off due to deterioration of the adhesion between the permanent magnet 14 and the turntable l1 made of the same material as the damper 2. In order to prevent this, it is necessary to take measures such as thoroughly cleaning each part of the clamp unit during manufacture and making the bonding area for the permanent magnet as large as possible, which complicates the process and lowers the yield.

SUMMARY OF THE INVENTION An object of the present invention is to provide a disk clamp device that has a simple assembly process and in which permanent magnets do not easily fall off.

[Means for solving the problem] The above purpose. In order to achieve this, in the disk clamp device according to the present invention, in the disk clamp device that presses the disk against the turntable by the magnetic adsorption action of a permanent magnet fixed to the turntable or clamper, The permanent magnet is attracted and fixed to a ferromagnetic member.

[Function] The disk clamping device having the above configuration securely fixes the permanent magnet by providing a ferromagnetic material on the turntable or the clamper and fixing the permanent magnet thereon by attraction.

[Example] The present invention will be explained in detail based on the example shown in FIGS. 1 and 2. Note that the same reference numerals as in FIGS. 4 and 5 represent the same members.

FIG. 1 corresponds to the conventional example shown in FIG. 4, and the spindle motor unit comprising a turntable 11 and the like rotated by a spindle motor 3 is the same as that of the conventional example, so a description thereof will be omitted. The clamper 2l has openings in both the upper and lower directions, and is bonded to the upper part of the clamper 2l, which has a thick lower diameter. A clamp pin 23 is fixed downwardly in the center of the steel plate 22 by caulking or press-fitting, and a cylindrical permanent magnet 24 is inserted between the clamp pins 23 and the clamp 21, and a magnetic attraction force is applied to the steel plate 22. It is fixed by suction.

Generally, the attraction force F acting on a permanent magnet brought close to a fixed ferromagnetic material is inversely proportional to the square of the distance G between the two, as shown in FIG. Therefore, when the disk D is clamped, an attractive force acts between the permanent magnet 24 and the yoke 7, but since the permanent magnet 24 is closer to the steel plate 22 than the yoke 7, the attraction force between the permanent magnet 24 and the steel plate 22 is smaller. is much stronger, and the permanent magnet 24 will not fall off the steel plate 22. However, due to vibrations and shocks, the permanent magnet 2
4 may slide, so it is desirable to use adhesive as well.

FIG. 3 shows a second embodiment, which corresponds to the second conventional example shown in FIG. A recess 13 having an inner diameter larger than the outer diameter of the hub Db is provided in the center, and a disc-shaped steel plate 32 with a hole in the center is fixed to the bottom of the recess 13 by a plurality of countersunk screws 33. An annular permanent magnet 34 on a steel plate 32
is attracted and fixed by magnetic attraction force.

When the disc D is to be clamped, the spindle 12 protruding from the center of the turntable 31 is passed through the center hole Da of the disc D'. Then, the permanent magnet 34 and the steel plate D
Although the disk D is clamped onto the turntable 31 by the magnetic attraction force acting between the permanent magnet 34 and the magnet C, the permanent magnet 34 does not separate from the steel plate 32 for the same reason as in the first embodiment.

In the second embodiment, a steel plate 32 is provided in order to obtain a sufficient suction area. The permanent magnet 34 may be attracted and fixed by the countersunk screw 33.

In both the second embodiment and the second embodiment, the permanent magnet is fixed mainly by magnetic adsorption force to the steel plate, so there is no need to pay special attention to the type or amount of adhesive, and the process can be significantly simplified. This will improve the yield.

[Effects of the Invention] As explained above, the disk clamping device according to the present invention attracts and fixes the permanent magnet by the magnetic attraction force that acts between the permanent magnet and the ferromagnetic material, thereby simplifying the assembly process. , reliability can be increased.

[Brief explanation of the drawing]

Drawings 1 to 3 show an embodiment of the disk clamp device according to the present invention, in which FIG. 1 is a sectional view of the first embodiment, FIG. 2 is a graph showing the relationship between distance and attraction force, and FIG. FIG. 3 is a sectional view of the second embodiment, and FIGS. 4 and 5 are sectional views of the conventional example. Symbol l1, 31 is a turntable, 21 is a clamper, 2
2 and 32 are steel plates, 24 and 34 are permanent magnets, and 33 is a countersunk screw. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] 1. In a disk clamping device that presses a disk against a turntable by the magnetic adsorption action of a permanent magnet fixed to a turntable or clamper, the permanent magnet is attracted and fixed to a ferromagnetic member provided on the turntable or clamper. A disc clamp device featuring: