JPS60247851A - Disk clamping device - Google Patents

Abstract

PURPOSE:To clamp two kinds of disks having different central hole sizes without interfering with the reproducing operation of a photosensor, by clamping the disks by putting the recessed section at the lower end of a clamping member on the projected section of the spindle shaft of a turntable facing the clamping member. CONSTITUTION:A cup-like clamping member 5 united with a clamp shaft 4 equipped with a recessed section 4a which can house the projected section 2a of a spindle shaft 2 as one body is provided, with the member 5 being faced a turntable 1. At the inside of the clamping member 5, tying members 6 and 7 respectively equipped with the 1st tapered surface 6a which is contacted with the circumference of the central hole of a disk having the smaller central hole and the 2nd tapered surface 7a which is in contact with the circumference of the central hole of a disk having the larger central hole are elastically supported by springs 8 and 9 and retaining ring 10 and the tying members 6 and 7 can slide in the vertical direction. The clamping member 5 is provided with a clamping surface 5a and flange 5b and the flange 5b is supported by a keep plate 11.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) It relates to a clamping device for a disc to a turntable in an information recording or reproducing system using a disc-shaped recording medium (disc). The present invention relates to a device that can clamp both CD type discs and laser video discs to the same turntable.

(Prior art and its problems) As a device that uses a disc-shaped information recording medium (hereinafter referred to as a disk),
udi.

[)isc) and video discs are becoming popular.

Among the DΔD, CD (Compact Qisc
) method, the audio signal is converted to a digital signal and a minute shape (
For example, depth 0.1 μm, width 0.5 μm, length 0.9~
The data is recorded as an intermittent bit string of 3.2 μm) in a spiral shape from the inner circumference to the outer circumference of the disk at a track pitch of 1.6 μm.

An aluminum reflective film is deposited on the surface of the recording surface, and a laser beam from a semiconductor is irradiated onto the bit string on the disk surface, and the presence or absence of bits is detected by a photodiode as a difference in reflectance, and D/A conversion is performed. It is played back as audio information via an electric circuit such as a device.

Since the rotational speed of the disk at this time is recorded as a constant linear velocity, the rotational speed is changed from 500 rpm (revolutions per minute) at the inner circumference of the disk to the outer circumference so that the linear velocity remains constant during playback. It decreases as it goes, reaching 200 at the outermost circumference.
The rotation speed is rpm.

On the other hand, among video discs, there are so-called laser video discs that use a laser to reproduce disc signals, but these discs have video and audio signals that are FM modulated and have minute shapes (for example, deep The data is recorded as an intermittent bit string with a length of 0.1 μm and a width of 0.4 μm in a spiral shape from the inner circumference to the outer circumference of the disk at a track pitch of 1.4 μm to 2.0 μm.

An aluminum reflective film is deposited on the surface of the recording surface, similar to a CD disk, and He-
A laser beam from a Ne gas laser tube or a semiconductor is irradiated, and the presence or absence of a bit is detected by a photodiode.
It reproduces video and audio signals through an electric circuit such as an FM demodulator.

At this time, the number of rotations of the disk is divided into two types: a disk recorded with a constant rotation speed, and a disk recorded with a constant linear velocity.
There are different types, and reproduction is performed at a rotation speed corresponding to each type. When the rotation speed is constant, the rotation speed is 1800 rpm, and when the linear speed is constant, the rotation speed is 1800+.pm to 600 rpm.

From the above explanation, the bit shapes recorded on CD discs and laser video discs are similar, and the reproduction method for both is to irradiate a bit string with a laser beam and detect the presence or absence of bits as a difference in reflectance. In the case of constant linear velocity recording, the number of rotations of the disk is continuously varied, etc.
It can be seen that many similar technologies are used for playback.

However, there is also a difference in whether the recorded information signal is an audio signal or a video signal, and dedicated players are separately prepared for playing back CD discs and laser video discs.

However, these days, it is said to be the A/V era, and audio <A)
There is a remarkable tendency for video (V) to become more complex both in terms of products and functionality. For example, converting TV broadcast audio to stereo and PCM, VTR audio to +z=i, video karaoke, still images can be recorded, and AD (Digital
With the advent of l Audio ()isc), there is a tendency for users to install a television receiver and a stereo device in the same place, and in such cases, both a CD disc player and a laser video disc player 17 are installed. Installing them separately increases the expense burden on the user side,
There are problems such as the need for extra space, and there is a desire for a shared player that can play both discs.

Recently, progress has been made in the development of semiconductor lasers that can be used to play back laser video discs and generate less noise and have a higher output, as well as signal processing ICs, but the major problem with realizing a shared player is that the dimensions of the discs are significantly different. It is one of the

The dimensions of the disks are shown in FIGS. 3A and 3B together with longitudinal cross-sectional views of the CD disk and the laser video disk, respectively. In the figure, 'I+' 2 represents the radius of the center hole of the disc, 0 represents the center of the disc, Ll and L2 represent the lead-in which is the starting position of signal recording, and dD
The diameter of the center hole of the system disc is 15 mm, and that of the laser video disc is 35 mm, which is more than double the diameter, which poses a problem in stably and reliably clamping the disc.

(Objective of the Invention) For two types of discs with different center hole sizes, such as a CD disc and a laser video disc,
It is an object of the present invention to provide a clamp device having a structure capable of stably and reliably clamping both disks together without interfering with the reproducing action of an optical sensor.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides a first tapered surface that abuts a first disk center hole having a small center hole, and a second disk having a large center hole. a second tapered surface that contacts the center hole of the second disk; an engaging member whose tapered surface is elastically supported in the same direction; a cup-shaped clamp member disposed on the outer periphery of the engaging member; and a rotation center portion. and a turntable having a recess in which the first tapered surface can be buried, and when the first disk having the small center hole is placed, the center position of the disk is determined by the first taper. When the disk is clamped by the clamp member and the second disk having the large center hole is placed, the first tapered surface is buried in the recess of the turntable, and the second disk is
The center position of the disk is determined by the tapered surface, and the disk is clamped by the clamp member, so that the clamp shaft of the clamp member is fixed regardless of whether a disk with a small center hole or a disk with a large center hole is placed. There is provided a disk clamp device characterized in that a lower end concave portion is fitted into a convex portion of an opposing spindle shaft of the turntable to clamp the first or second disk, respectively.

(Embodiment) FIG. 1 shows a longitudinal sectional view of a disk clamping device according to an embodiment of the present invention. FIG. 2 shows a longitudinal cross-sectional view of the clamped state due to differences in the disks in the embodiment shown in FIG. 1, and FIG.
The same figure (B) shows the case where the center hole of the disk is large.

In FIG. 1, a spindle shaft 2 having a hemispherical or pyramidal convex portion 2a at the tip is fixed to a turntable 1 having a flange 1a and a concave portion 1b in the center,
Furthermore, a fixed motor 3 is attached to the shaft 2.

Opposed to the turntable 1 is a cup-shaped clamp member 5 in which a convex portion 2a of a spindle shaft 2 and a clamp shaft 4 having a fittable recess 4a are integrated. On the inside of this clamp member 5, there is a first tapered surface 6a which abuts around the center hole of a disk having a small center hole with the shirt 1-4 coaxial therewith, and a first tapered surface 6a which abuts around the center hole of a disk having a large center hole. Second tapered surface 7a
The engaging members 6 and 7, respectively, are elastically supported by springs 8 and 9 and a retaining ring 10.
and 7 can each be slid in the vertical direction. The clamp member 5 has a clamp surface 5a and a flange 5b.
The flange 5b is supported by a holding plate 11.

A hard ball 12 is rotatably fitted into the recess 4b at the upper end of the clamp shaft 4 with a portion thereof exposed.

The clamp member 5 is attached to the presser plate 11 (moved in the vertical direction by the pulled rod 13, and subjected to weight).

Next, Figure 2 (△) shows the clamping operation when a disk with a small center hole is placed on the clamping device with the above configuration.
This will be explained with reference to FIG. 3(A).

A disk D1 having a small center hole with a radius r1 is placed on the turntable 1 by a loading mechanism (not shown), and the clamping member 5 and the engaging members 6 and 7 are pushed down by the rod 13 automatically or manually. When the convex portion 2a of the spindle shaft 2 and the lower end recess 4a of the clamp shaft 4 fit together, the clamp member 5 and the engaging members 6, 7 are aligned with the center of the turntable 1, and then the first tapered surface The downward force of the rod is buffered by the burr 8, and the rod 6a comes into contact with the periphery of the center hole of the radius r1 of the disk D1.
The turntable 1 is clamped by a predetermined pressure of the rod 13 by a.

After the disk D1 is clamped, an optical pickup 74 consisting of a semiconductor laser, a photodiode, etc.
The radius rf of the flange 1a of the turntable 1 is set to be smaller than the radius OL,+ so that the signal is reliably detected from the lead-in position Ll on the lower side of the disc.

Furthermore, the clamping operation when a disk having a large center hole is placed will be explained with reference to FIGS. 2(B) and 3(B).

A disk D2 having a large center hole with a radius r2 is placed on the turntable 1 by a loading mechanism (not shown), and the clamping member 5 and engaging members 6 and 7 are moved downward by a rod 13 automatically or manually. When pushed down, the convex portion 2a of the spindle shaft 2 and the lower end recess 4a of the clamp shaft 4 fit together, so that the clamp member 5 and the engaging members 6, 7 align with the center of the turntable 1, and then when the disc D2 is the first tapered surface 6a
This portion is buried in the recess 1b of the turntable 1.

On the other hand, the second tapered surface 7a is subjected to a downward force of the rod by the spring 9, and comes into contact with the periphery of the center hole of the radius r2 of the disk D2, and the center of the disk D2 is positioned, and the disk D2 is clamped. Clamping surface 5a of member 5
Accordingly, the turntable 1 is clamped with a predetermined pressure of the rod 13.

After the disk D2 is clamped, an optical pickup 14 composed of a semiconductor laser, a photodiode, etc. detects a signal from a lead-in position L2 on the lower side of the disk.

If the spring constants of springs 8 and 9 of the clamping device are 8 and 9, respectively, then Kn<K9 - and the restoring force of spring 9 is smaller than the predetermined pressure of rod 13. Spring 8 and spring 9 are set respectively.

It goes without saying that the present invention is applied to a disc in which the position of the lead-in L1 of the disc D1 is outside the center hole of the disc D2, that is, 01+>r2.

In the embodiment described above, the engaging member 6 having the first tapered surface 6a and the engaging member 7 having the second tapered surface 7a are individually slidable up and down, but the engaging members 6 and 7 are integrated. A simple mechanism in which the cover spring 8 is omitted is also conceivable.

(Effects of the Invention) As described in F (According to the present invention, disks having different center holes can be turned by an engaging member having first and second tapered surfaces with different diameters corresponding to the center holes of different disks. It is possible to accurately center and clamp the disc on the table, and since the disc is clamped on the ring surface of the turntable, there is no risk of damaging the center hole of the disc, and at the same time, the spindle shaft of the turntable and the clamp shaft are clamped. Since the inside is fitted, the clamp will be securely held even if excessive force is applied to the disc due to an external shock while the disc is rotating at high speed, and the disc will come into close contact with the turntable. Therefore, the distance from the surface of the disk to the optical pickup remains constant even when the disk is changed, and the optical pickup has the advantage of not requiring a vertical movement function.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a clamping device according to an embodiment of the present invention, and FIGS. 2(A) and 2(B) are longitudinal sectional views of the clamped state of the embodiment of FIG. 1 due to different disks. FIGS. 3(A) and 3(B) each show a schematic vertical cross-sectional view of a laser video disc, including a CD disc and an isk, and their dimensions, respectively. 1...Turntable, 1a...1 flange, 1
b...1 recess, 2... spindle shaft, 2a
... Convex portion of 2, 3... Motor, 4... Clamp shaft, 4a... Lower end recess of 4, 4b... Upper end recess of 4, 5... Clamp member, 5a... 5 clamping surface, 5b...5 flange, 6.7... engaging member,
'6a, 7a...Tapered surface, 8.9...Spring, 10
... Retaining ring, 11 ... Holding plate, 12 ... Hard ball, 1
3... Rod, 14... Optical pickup, DI, D2... Disk, rl+'2... Radius of disk center hole, 1,1
2...Lead-in position. Way) Simple 11 Outside 2 Myo (8) 3

Claims (1)

[Claims] A first tapered surface that abuts the center hole of the first disk having a small center hole and a second tapered surface that abuts the center hole of the second disk that has the large center hole make the tapered surfaces elastic in the same direction. A supported engagement member, a cup-shaped clamp member disposed around the outer periphery of the engagement member, and a turntable having a recess in the center of rotation in which the first tapered surface can be buried are provided, When a first disk having a center hole is placed, the center of the disk is determined by the first taper, the disk is clamped by the inno lamp member, and a second disk having the large center hole is placed. If the first tapered surface is buried in the recess of the turntable, the second tapered surface positions the center of the disc, and the clamping member clamps the disc,
Regardless of whether a disk having a small center hole or a disk having a large center hole is placed, the lower end concave portion of the clamp shaft of the clamp member is fitted into the convex portion of the opposing spindle shaft of the turntable, A disk clamp device characterized in that the first or second disk is clamped respectively.