JPH03178077A - Drive device for optical disk - Google Patents

Abstract

PURPOSE:To obtain a correct information signal even when generating warp in an optical disk and to simplify structure by providing a joint rod and a control part to control the move of the joint rod corresponding to the offset of a tracking error signal from a pickup to sent a laser beam to the optical disk. CONSTITUTION:A control part 15 is interposed between a pickup 3 and a joint rod 14, reciprocatively moves a rod part 29 of the joint rod 14 based on the tracking error signal from a photodetector 11 of the pickup 3 and controls the offset to be zero while inclining a chucking table 5 and an optical disk 2. When the offset is generated in the tracking error signal from the pickup 3, the control part 15 generates a move command onto the joint rod 14 side and moves the joint rod 14 in a direction so that the offset can be zero. Thus, since the correct information signal can be accessed and the structure is formed so as to be freely inclined, a drive device can be formed to be light and compact with high rigidity.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an optical disc drive device that tilts a chucking table that supports an optical disc to eliminate the influence of offset of a tracking error signal caused by warping of the optical disc. .

<Prior art> Fig. 6 shows a conventionally used drive device 1 for an optical disc 2.
The general structure of a and its pickup 3 is shown. The drive device 1a includes a magnetic hub 4 that holds the center of the optical disk 2, a chucking table 5a to which the magnetic hub 4 is fixed, a motor 6, a drive shaft 7 that connects the motor 6 and the chucking table 5a, and the like. It consists of On the other hand, the pickup 3 is a laser diode (LD) that is a laser light source.
) 8, a reflective lens 9, a focusing lens lO,
It is composed of a light receiving element 11 that receives reflected light from the tracks of the optical disc 2, and the like.

The optical disc 2 is rotationally driven by the drive device 1a as shown by arrow A, and the pickup 3 is driven by a linear motor or the like to move in the radial direction of the optical disc 2 as shown by arrow B, thereby accessing information on the optical disc 2. will be held.

When the optical disc 2 is not warped, the tracking error signal consists of a waveform with the same dimensions as A and 8 as shown in FIG.
A signal is output from the light receiving element 11.

<Problems to be Solved by the Invention> However, since the optical disc 2 is made of acrylic, polycarbonate, etc., it is likely to warp as shown in FIG. 7 due to the manufacturing process, thermal effects over time, storage conditions, etc. - Once warpage occurs, it is difficult to restore it to its original state.

When the optical disc 2 with a warp as shown in FIG. 7 is accessed by the pickup 3, the tracking error signal is A゜size B as shown in FIG.

This results in a wavy shape with different dimensions, and an offset occurs as shown in the figure. If the tracking servo is applied in this state, the position of the pickup 3 will be controlled by the amount of the offset, and it will deviate from the track center of the optical disc 2. As shown in FIG. An ID signal of the degree dimension will be emitted.

Since it is difficult to manage the optical disc 2 so that it does not warp, countermeasures against warping have been taken in the past. For example, there are those in which the carriage shaft (circle) that supports the guide of the pickup is inclined to match the warp, and the carriage shaft is fixed and the pickup itself is rotated and moved up and down. That is, conventionally, a device in which the pickup side is inclined has been adopted.

When the pickup side is provided with a rotation function, the pickup becomes complicated and increases in weight, which causes the problem of slow access time, as well as the problem of decreased rigidity and susceptibility to vibration, making it impossible to obtain highly accurate information. . Naturally, there also arises the problem of increased costs. One possible solution to the above problems is to tilt the chucking table that supports the optical disk along with the motor, but this method requires consideration of fluctuations in the rotational torque of the motor, its mass balance, etc., and the structure is Problems arise in that the device becomes complicated and the device becomes large in order to maintain high rigidity.

Even if the optical disk is warped, the present invention can obtain a correct information signal, has a simple structure, is lightweight, and small in size, has no unbalanced motor rotation, and no fluctuation in the rotation of the chucking table. An object of the present invention is to provide an optical disk drive device in which force is transmitted smoothly.

Means for Solving the Problems> In order to achieve the above objects, the present invention provides a chucking table that supports an optical disc and has a joint hole in the center thereof and a locking groove carved around the periphery of the chain hole; A joint shaft having a joint portion that rollably engages with the joint hole and a locking portion that locks in the locking groove and is connected to the motor, and an outer edge of the chucking table that is held between the inner periphery. a retaining ring having a joint portion on its outer periphery; a joint rod rotatably engaged with the joint portion of the retaining ring; The present invention constitutes an optical disc drive device including a control section for controlling movement of a joint rod.

Effect> When an offset occurs in the tracking error signal from the pickup, the control section issues a movement command to the joint rod side, and moves the joint rod in a direction to make the offset zero. That is, when the joint rod moves, the retaining ring jointed to the joint rod tilts, and the chucking table tilts accordingly. Since the chucking table is jointed to the joint shaft, the chucking table rotates and tilts around the center of the joint of the joint shaft. This causes the optical disc to tilt, and as a result, the offset is adjusted to zero.

<Example> Embodiments of the present invention will be described below based on the drawings.

As shown in FIG. 1, the drive device 1 includes a chucking table 5, a joint shaft 12 that is jointly coupled to the chucking table 5, a retaining ring 13 that holds the outer edge of the chucking table 5, and a joint shaft 12 that is jointly coupled to the retaining ring 13. It is composed of a joint rod 14, a control section 15, and the like.

As shown in FIG. 2, the chucking table 5 consists of a disc-shaped table on which a magnetic hub 4 is mounted, and a spherical hole 16 (corresponding to the joint hole) is opened at the front and back sides in the center. It is formed. In addition, locking grooves 17 and 18 are formed on the inner peripheral edge of the spherical hole 16 and are perpendicular to each other. The bottom surface of the locking groove 17° 8 is formed into a spherical surface concentric with the spherical hole 16. A protruding flange portion 19 is integrally formed on the outer periphery of the chucking table 5.

As shown in FIGS. 3 and 4, the joint shaft 12 has a spherical portion 20 (rollably engaged with the spherical hole 16).
(equivalent to the joint portion); and locking portions 21 and 22 formed protruding from the outer periphery in directions perpendicular to each other;
The rotating shaft 23 is connected to the spherical portion 20. The locking portion 21 engages with the locking groove 17, and the locking portion 22 engages with the locking groove 1.
8, respectively. Further, the rotating shaft 23 is connected to a fixed motor 6. Therefore, the rotation of the motor 6 is transmitted from the joint shaft 12 to the chucking table 5 through the engagement of the locking portions 21.22 and the locking grooves 17.18.

The retaining ring 13 is made of a ring-shaped member, and a concave groove 24 for holding the flange portion 19 of the chucking table 5 is recessed in the inner peripheral side of the retaining ring 13 . In addition, a spherical portion 25 is provided on the outer periphery.
．． 26 (corresponding to the joint portion) is formed to protrude. Note that the spherical portion 25 is arranged along the same direction as the locking groove 17 of the chucking table 5, and the spherical portion 26 is arranged in the same direction as the locking groove 18.

The joint rod 14 has ball joint portions 27, 2 forming a spherical hole that rollably engages the spherical portions 25,26.
111 and rod portions 29 and 30 connected thereto and disposed in a direction substantially parallel to the joint shaft 12.

The control unit 15 is interposed between the pickup 3 and the joint rod 14, and is
Based on the tracking error signal from 1, the rod portion 29 (30) of the joint rod 14 is moved back and forth, and the chucking table 5 and the optical disk 2 are tilted to control the offset to zero.

Next, the operation of this embodiment will be explained in more detail.

As shown in FIG. 7, when the optical disc 2 is warped and the pickup 3 moves in the direction of arrow B, an offset occurs in the tracking error signal, and an ID signal as shown in FIG. 11 is output.

To correct this, the optical disc 2 may be tilted as shown in FIG. Since the chucking table 5 is rotatably supported by a ball joint connection between its spherical hole 16 and the spherical portion 20 of the joint shaft 12, it rotates about the center of the spherical portion 20 as a reference point. In this case, the joint shaft 12 and the motor 6 connected thereto remain stationary.

On the other hand, in this embodiment, the locking grooves 17,
18 is formed and the locking portions 21 and 22 engage with the locking portions 21 and 22, so that the chucking table 5 is formed to be tiltable in two directions along the locking grooves 17 and 1g.

On the other hand, the joint rod 14 is attached to the spherical part 2 of the retaining ring 13.
5, 26 and ball joint, spherical part 25.26
are arranged in the same direction as the locking grooves 17 and 18,
By moving the joint rod 14 in the direction of arrow C, the chucking table 5 can rotate the joint shaft 12 in the plane of the paper of FIG. 1 (radial direction) and in a direction perpendicular thereto (circumferential direction). will be supported by Therefore, if the optical disc 2 is warped in the radial direction in FIG.
If there is a warp in the circumferential direction as shown in FIG. 1, move the rod 30 side of the joint rod 14 to tilt the chucking table 5. Bye. Of course, it is also possible to move both at the same time and tilt the chucking table 5 in two directions.

The retaining ring 13 functions to tilt the chucking table 5 to a correct tilted position in response to the movement of the joint rod 14.

As described above, since the structure in which the chucking table 5 side that supports the optical disk is tilted and the pickup 3 side is tilted in response to the warpage of the optical disk 2 is not adopted, it is possible to form the structure from a simple structure as described above. I can do it.

In this embodiment, the connection between the chucking table 5 and the joint shaft 12 and the connection between the retaining ring 13 and the joint rod 14 are made by spherical joint connections, but the structure is not limited to the example. Furthermore, the locking grooves 17 and 18 are not limited to two directions.

<Effect of the invention> The effects of the present invention are as follows.

1) Correct information signals can be accessed because the optical disc is tilted in response to the warpage of the optical disc and the offset of the tracking error signal is adjusted to zero.

2) Unlike the conventional technology, since the side supporting the optical disk is formed in a tiltable structure, the structure is simple, high rigidity, lightweight, and compact.

3) Since the chucking table that supports the optical disk is jointly coupled to the joint shaft, it can rotate smoothly and can accommodate minute tilt angle adjustments.

4) Since the joint shaft transmits the rotation of the motor to the chucking table via the joint, the chucking table does not undergo rotational fluctuations (jitter).

5) Since the motor only transmits rotation in a fixed state, there is no unbalanced rotation of the motor or variation in rotational torque. Therefore, smooth rotation is transmitted to the chucking table side.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram of an embodiment of the present invention, Fig. 2 is a plan view of the chucking table, Fig. 3 is a front view of the spherical part of the joint shaft, and Fig. 4 is viewed from arrow iv in Fig. 3. A plan view, FIG. 5 is an explanatory plan view for explaining the operation of this embodiment,
Figures 6 and 7 are front views of conventional drive devices, Figure 8 is a waveform diagram showing a normal tracking error signal, Figure 9 is a waveform diagram when the tracking error signal has an offset, and Figure 1O is a waveform diagram showing a normal tracking error signal. FIG. 8 is a waveform diagram showing the ID signal in the case of FIG. 8, and FIG. 11 is a waveform diagram showing the ID signal in the case of FIG. l...Drive device, 2...Optical disc, 3...
Pickup, 4... Magnetic hub, 5... Chucking table, 6... Motor, 7... Drive shaft, 8...
・Laser diode (LD), 11... Light receiving element, 1
2...Joint shaft, 13...Retaining ring,
14... Joint rod, 15... Control section, 16
... Spherical hole, 17.18 ... Locking groove, 19 ... Flange part, 20.25.26 ... Spherical part, 21, 22
... Locking part, 23 ... Rotating shaft, 24 ... Concave groove, 2
7, 28...Ball joint part, 29°30...Rod part.

Claims (1)

[Claims] A chucking table that supports an optical disk and has a joint hole in the center and a locking groove on the periphery of the hole, and a joint portion that rotatably engages with the joint hole and locks in the locking groove. a joint shaft that has a locking part and is connected to the motor; a retaining ring that clamps the outer edge of the chucking table with its inner periphery and has a joint part on its outer periphery; An optical disc drive device comprising: a joint rod that engages; and a control unit that controls movement of the joint rod in response to an offset of a tracking error signal from a pickup that sends a laser beam to the optical disc.