JPH08221860A - Disk clamp mechanism - Google Patents

Abstract

PURPOSE: To perform accurate rotation control by reducing the size of a permanent magnet in diameter and volume, increasing the ratio of pressing force of a clamper for holding a disk to magnetic force generated from the permanent magnet and suppressing slippage between a table and the disk. CONSTITUTION: The table 402 is formed with an annular recessed part 404 opposite and parallel to the surface of the disk 401, and the recessed part 404 has two surfaces of magnetic poles in parallel on both sides, and is joined to one pole surface of the annular permanent magnet 101 to be fixed together. Then, since the magnet 101 is coaxially formed with its inner wall surface 101a and outer wall surface 101b, which are settled to have fixed spaces from an inner wall and an outer wall of the recessed part 404 respectively, the outer wall surface 101b of the magnet 101 and the wall surface of the recessed part 404 are separated with a gap 102 of the fixed space. Then, the clamper 406 is formed with a truncated cone part 408 in the middle, and is fixed with a yoke 407 to be coaxial with the truncated cone part 408. The truncated cone part 408 formed on the clamper 406 is coaxially engaged with a cone recessed part 409 in the middle of the table 402 to hold the disk 401 between them.

Description

Detailed Description of the Invention

[0001]

[0001]

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disc clamp mechanism for holding and stably rotating a disc such as an optical disc, a magneto-optical disc, a magnetic disc or the like.

[0003]

[0002]

[0004]

2. Description of the Related Art Conventionally, there has been a disk clamp mechanism of this type shown in FIG.

FIG. 4 is a schematic sectional view of a conventional clamp mechanism using a permanent magnet, and shows a state in which the clamp mechanism clamps and holds a disk.

The outer diameter of the table 402 is the disk 401.
, And the disc 401 is placed. The table 402 is fixed to a rotary shaft 403 of a motor (not shown). Further, a ring-shaped recess 404 facing the disk 401 and parallel to the surface of the disk 401 is formed on the table 402, and a ring-shaped permanent magnet 405 having two parallel magnetic pole surfaces is fixed on the recess 404. Has been done. The clamper 406 has a yoke 407 made of a ring-shaped iron plate and a plurality of protrusions 410.
It is fitted and fixed to. The clamper 406 holds a disk 401 by engaging a truncated cone 408 formed in the center thereof with an inverted conical recess 409 formed in the center of the table 402.

Further, the table 402 and the yoke 407.
Is made of a soft magnetic material having a high magnetic permeability, the table 402 and the clamper 406 hold the table 402, the yoke 407, and the permanent magnet 4 when the disk 401 is being narrowed.
05 constitutes a magnetic loop, and the yoke 407 and the permanent magnet 4
05 attract each other due to its magnetic force, so that the disk 4
01 is crimped and clamped.

Further, since the table 402 is made of a magnetic material, the magnetic flux generated from the permanent magnet 405 is magnetically shielded so as not to leak to the outside of the table 402.

For this reason, the electromagnetic conversion mechanism of the optical pickup provided near the recording information surface of the optical disk for reading the optical disk, and the magnetic coil provided near the recording surface of the magneto-optical disk during recording of the magneto-optical disk. Does not disturb the magnetic field.

[0010]

FIG. 5 is an enlarged detailed view of the portion A shown in FIG. 4, in which the magnetic flux flow of the permanent magnet is represented by lines of magnetic force. The dotted line in the figure is the magnetic field line. Most of the magnetic flux generated from one magnetic pole surface of the permanent magnet 405 is the yoke 407.
Is drawn to the table 402 again after passing through the inside of the yoke 407, passes through the inside of the table 402, and then reaches the other magnetic pole surface of the permanent magnet 405 to draw a magnetic loop. Further, the other magnetic flux generated from one magnetic pole surface of the permanent magnet 405 does not reach the yoke 407 but directly reaches the table 402 and the magnetic short circuit loop 5 is generated.
Draw 01.

Of the magnetic flux generated from the permanent magnet 405, the magnetic flux attracted to the yoke 407 serves as a force for clamping the disk 401, and the magnetic short circuit loop does not contribute to the clamping.

[0012]

[0004]

[0013]

The clamper mechanism using the permanent magnets is used in many cases because of its relatively simple structure, but in recent years, a disk such as a CD-ROM is intermittently rotated at a high speed. A device for reading has come to be required. In such a case, if the disc is held by the conventional clamp mechanism, the table and the disc slip when the table rotates, and accurate disc rotation control and read control cannot be performed. For this reason, it is necessary to further increase the holding power of the disc. As described above, the holding force of the disk can be obtained by making the permanent magnet used in the clamper mechanism larger to increase the magnetic flux, but there is a drawback that the clamper mechanism becomes large and the manufacturing cost also increases.
Furthermore, since the magnetic flux passing through the inside of the table 402 is increased, the table 402 is magnetically saturated and a part of the magnetic flux leaks to the outside of the table 402, which is provided near the recorded information surface of the optical disc for reading the optical disc. Further, there is a drawback that the magnetic field of the electromagnetic conversion mechanism of the optical pickup or the magnetic coil provided near the recording surface of the magneto-optical disk is disturbed during recording on the magneto-optical disk.

[0014]

The present invention has been made in view of the above problems, and does not disturb the electromagnetic conversion mechanism of an optical pickup or the magnetic field of a recording magnetic coil during recording / reproduction of an optical disc, and the optical disc is intermittently operated at high speed. An object of the present invention is to provide a disc clamp mechanism capable of preventing the table and the disc from slipping even when rotated, and performing accurate rotation control and reading control of the optical disc.

[0015]

[0006]

[0016]

According to the first aspect of the present invention,
In a holding device for holding a disk by both a first holding member made of a magnetic material having a concave portion and a magnet arranged in the concave portion and a second holding member having a yoke portion, the first holding member and the magnet with respect to the disk surface. It is characterized by being isolated in a parallel direction.

According to a second aspect of the present invention, in the holding device according to the first aspect, a separating member having a low magnetic permeability is provided between the first holding member and the magnet, and the separating member serves the magnet with respect to the first holding member. Is also used as the positioning member.

According to a third aspect of the present invention, there is provided a holding device for holding a disk by a suction force between a holding member made of a magnetic material having a recess and a magnet disposed in the recess and a magnetic material provided on the disk hub. A holding device characterized in that the holding member and the magnet are arranged separately in a direction parallel to the disk surface.

[0019]

[0007]

[0020]

Since the present invention is configured as described above, it does not disturb the magnetic field of the electromagnetic conversion mechanism of the optical pickup or the magnetic coil for recording provided in the vicinity of the recorded information surface of the optical disc during recording and reproduction of the optical disc. Therefore, information on the optical disc can be accurately recorded and reproduced.

Further, even if the optical disc is intermittently rotated at a high speed, the table and the disc are prevented from slipping, so that accurate rotation control of the optical disc can be performed.

Further, since the magnet and the table are fixed coaxially, the crimping force of the clamper can be set uniformly over the entire disk mounting surface of the table.

[0023]

[0008]

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. The same parts as those of the conventional one described with reference to FIGS. There is.

FIG. 1 is a schematic sectional view of a clamp mechanism using a permanent magnet according to one embodiment of the present invention, and shows a state in which the clamp mechanism clamps and holds a disk.

In the figure, 101 is a permanent magnet and 102 is an air gap.

The table 402 has a disk 4 at the center thereof.
The disc 401 is mounted by fitting it into the center hole 01. The table 402 is coaxially fixed to a rotation shaft 403 of a motor (not shown). Further, the table 402 is formed with a ring-shaped recess 404 that is parallel to the surface of the disk 401, and has two parallel magnetic pole surfaces on the recess 404, and the ring-shaped permanent magnet 101.
One of the magnetic pole surfaces is joined and fixed. The permanent magnet 101 has an inner wall surface 101a and an outer wall surface 101b.
Are formed coaxially, and the recess 404 of the table 402 is
Since it is set at a constant distance from the inner and outer walls of
The ring-shaped outer wall surface 101b of the permanent magnet 101 and the recess 40
The wall surfaces of No. 4 are separated by air gaps 102 at regular intervals.

Further, a truncated cone 408 is formed in the center of the clamper 406, and a yoke 407 made of a ring-shaped iron plate is fixed so as to be coaxial with the truncated cone 408. A truncated cone 408 formed on the clamper 406 coaxially engages with an inverted conical recess 409 formed in the center of the table 402 to hold the disc 401. Also,
Since the table 402 and the yoke 407 are formed of a soft magnetic material having a high magnetic permeability such as iron, the table 402, the yoke 407, and the permanent magnet 101 form a magnetic loop when the table 402 and the clamper 406 are narrowing the disk 401. Since the yoke 407 and the permanent magnet 101 are attracted to each other by the magnetic force, the disk 401 is sandwiched by pressure.

[0029]

FIG. 2 is an enlarged detailed view of the portion B shown in FIG. 1, and shows the flow of the magnetic flux of the permanent magnet by the lines of magnetic force. The dotted line in the figure is the magnetic field line.

The outer wall surface of the permanent magnet 101 is the table 4
The outer diameter is set so as to be separated from the wall surface of the concave portion 404 of No. 02 by the gap 102 having a constant interval. For this reason,
Most of the magnetic flux generated from one magnetic pole surface of the permanent magnet 101 is attracted to the yoke 407 and
7 It passes through the inside and is attracted to the table 402 again,
After passing through the inside of the table 402, it reaches the other magnetic pole surface of the permanent magnet 101 to draw a magnetic loop. Therefore, the magnetic flux 10 that draws a magnetic short-circuit loop without reaching the yoke 407
The ratio of 3 is greatly reduced as compared with the magnetic short loop 501 of FIG. Therefore, as compared with the case where the outer diameter of the permanent magnet 101 is set without a gap with the wall surface of the concave portion 404 of the table 402, the volume of the permanent magnet 101 can be smaller, and the magnetic force for crimping and sandwiching the disk 401 increases. Further, when the ratio of the magnetic flux 103 that draws the magnetic short circuit loop is greatly reduced, magnetic saturation does not occur in the table 402, so that there is no magnetic leakage to the periphery of the table 402.

[0031]

Another embodiment of the present invention will be described below with reference to FIG. 3. The same parts as those of the conventional one described above with reference to FIGS. 4 to 5 are designated by the same reference numerals.

FIG. 3 is a schematic sectional view of a clamp mechanism using a permanent magnet in another embodiment of the present invention, and shows a state in which the clamp mechanism clamps and holds a disk.

On the wall surface of the recess 404 of the table 402, there is provided a concentric ring-shaped separating member 301 which is made of a non-magnetic material having a low magnetic permeability, has a constant height, and has substantially the same diameter as the wall surface of the recess 404. It is fitted and fixed. Further, the inner wall of the separating member 301 is set to have substantially the same diameter as the outer diameter of the permanent magnet 101, and one magnetic pole surface of the permanent magnet 101 is bonded and fixed onto the recess 404, so that the outer wall surface and the separating member 301 are fixed. The inner wall surfaces of are fitted and fixed to each other. For this reason, the isolation member 301 allows the permanent magnet 101 to move into the recess 4 of the table 402 when the clamp mechanism is assembled.
04 serves as a positioning member for fixing the rotating shaft 403 coaxially with the rotating shaft 403. With such a configuration, the magnetic short-circuit loop is significantly reduced and the magnetic force for holding the disk 401 by crimping is increased as compared with the conventional clamping mechanism as shown in FIG.

As described above, when the clamp mechanism is assembled and the disc 401 is clamped and sandwiched, the permanent magnet 101 and the yoke 407 are positioned coaxially with the rotating shaft 403, so that the clamper 406 has a crimping force. Table 402
It is uniform over the entire disc mounting surface.

[0035]

In the above embodiment, the disk 401 is crimped and held by using the permanent magnet 101 fixed to the table 402 and the yoke 407 fixed to the clamper 406, but as shown in FIG. When a disk having a disk hub 601 formed of a magnetic material such as an iron plate on the inner peripheral portion of the disk is clamped, the permanent magnet 101 and the disk hub 6 are used instead of the clamper 406 and the yoke 407.
You may make it hold | maintain a disk by the attraction | suction force with the magnetic body of 01.

[0036]

[0012]

[0037]

Since the present invention is constructed as described above, the outer diameter of the permanent magnet is reduced to reduce the volume thereof, and moreover, the ratio of the crimping force of the clamper holding the disk to the magnetic flux emitted from the permanent magnet is increased. Therefore, it does not disturb the magnetic field of the electromagnetic conversion mechanism of the optical pickup or the magnetic coil for recording at the time of recording / reproducing the optical disk, and also prevents the table and the disk from slipping even when the optical disk is intermittently rotated at a high speed. It is possible to realize a disc clamp mechanism capable of performing accurate rotation control and reading control of an optical disc.

Further, since the permanent magnet and the table are magnetically separated by a separating member made of a non-magnetic material having a low magnetic permeability over a fixed interval and the permanent magnet and the table are fixed coaxially, the clamper is crimped. The force can be set uniformly over the entire disk mounting surface of the table.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a clamp mechanism using a permanent magnet according to an embodiment of the present invention.

FIG. 2 is an enlarged detailed view of a portion B shown in FIG.

FIG. 3 is a schematic sectional view of a clamp mechanism using a permanent magnet according to another embodiment of the present invention.

FIG. 4 is a schematic sectional view of a conventional clamp mechanism using a permanent magnet.

5 is an enlarged detailed view of a portion A shown in FIG.

FIG. 6 is a schematic cross-sectional view of a clamp mechanism that clamps a disk having a disk hub formed thereon using a permanent magnet according to the present invention.

Claims (3)

[Claims] 1. A holding device for holding a disk by both a first holding member made of a magnetic material having a recess and a magnet disposed in the recess and a second holding member having a yoke portion, wherein the first holding member The holding device, wherein the magnets are separated in a direction parallel to the disk surface. 2. The holding device according to claim 1, wherein a separating member having a low magnetic permeability is provided between the first holding member and the magnet, and the separating member positions the magnet with respect to the first holding member. It is also characterized in that. 3. A holding device for holding a disk by a suction force between a holding member made of a magnetic material having a recess and a magnet disposed in the recess and a magnetic material provided on a disk hub, wherein the holding member and the A holding device characterized in that the magnets are arranged separately in a direction parallel to the disk surface.