JPS6352338A - Disk reproducing device - Google Patents

Abstract

PURPOSE:To miniaturize and simplify a device in comparison with the device, where respective controls are performed with means independent of one another, and improve the linearly and extend the dynamic range by using one rotating body, which can be turned around the axial line and can be slided along the axial line, to control off-tracking and defocusing. CONSTITUTION:When a focus position control current is supplied to a focus control coil 18, a shaft 43 and a supporting plate 44 are moved in the direction of an arrow A, and a condenser lens 35 is moved in the direction of the arrow A in accordance with this movement, and then, the focus position is corrected. When a tracking position control current is supplied to a tracking coil 42, the shaft 43 and the supporting plate 44 are rotated in the direction of an arrow B, and the condenser lens 35 is turned in the direction orthogonal to tracks. Two coil parts facing each other of the coil 42 contribute to the driving force for turning to improve the use rate of the coil, and a turning device is miniaturized.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a playback device that optically reads recorded information from a video disc, a PCM disc, etc. This relates to a drive mechanism.

[Conventional technology]

A conventional device of this type is shown in FIG. In the figure, 1 is a laser light source such as He-Ne, 2 is a laser beam, 3 is a diffusion lens, 4 is a half mirror, 15 is a trunk tracking control mirror device, 6 is a focus control lens device, 7 is a photodetector, and 8 is a 9 is a motor, 10 is a reproduction signal processing circuit, l1 is a track tracking control circuit, 12 is a focus control circuit, and 13 is a pit.

Next, the operation will be explained. A laser beam 2 emitted from a laser light source 1 is diffused by a diffusion lens 3 and then sent to a half mirror 4.
After passing through the track tracking control mirror device 5, a condensing lens housed in the focus control lens device 6 forms a micron-order light spot (optical needle) on the disk 8. On the other hand, as shown in FIG. 6, pits 13 on the order of microns are recorded on the disk 8 as spiral or concentric trunks. This micron-order pit 13
In addition, by maintaining the light beam 2 focused on the micron order in an appropriate positional relationship, the signal is optically regenerated.

FIG. 7 is a diagram for explaining the positional relationship between the optical disk (1) and the disk, and as shown in this diagram, the light beam 2 spreads out again after being focused. In such a situation,
It is obvious that in order to perform the most efficient reproduction, it is better to reproduce near where the light is most concentrated.

However, when the disk 8 is rotated in the direction of arrow C in FIG.
Due to disturbances and the like, the recording surface of the disk 8 changes as shown in FIGS. 7a, b, and c. Similarly, regarding the relationship between the light spot and the recording track, positional deviations occur as shown in FIGS. 7d, e, and f due to meandering of the recording track, eccentricity of the disk 8, etc. Therefore, in order to always perform efficient reproduction, it is necessary for the light spot of the light beam 2 to always track the pit 13 in the focal direction and in the direction perpendicular to the trunk.

For this reason, in the conventional device, the focus control lens device 6
and a track tracking control mirror device 5 were used.

These devices each move a condenser lens up and down in the direction of arrow A perpendicular to the disk 8 (see FIG. 5), and rotate the mirror of the track tracking control mirror device 5 in the direction of arrow B.

Although a detailed explanation will be omitted here, the distance between the disk 8 and the condensing lens and the amount of deviation of the light spot from the track are extracted as electrical signals by the photodetector 7, and the focus control circuit 1
2 and the track tracking control circuit 1) to send the control signal to the focus control lens device 6 and the track tracking control mirror device 5.
, and appropriate corrections are made accordingly.

Figure 8 is a sectional view of the main parts of a conventional focus control lens device;
The figure is a conceptual diagram of the track tracking control mirror device. In FIG. 8, a coil 18 is installed in the magnetic flux formed by the yoke 16 and the magnet 17, and a control current is passed through the coil 18, so that the lens frame 2 is supported by the spring 15.
0 moves in the direction of arrow A. As this spring 15, an annular grooved plate spring or the like has been used. Note that 14 is a condenser lens, and 19 is a support frame fixed to the yoke 16.

Further, in FIG. 9, 21 is a mirror corresponding to the mirror of the truck tracking control mirror device shown in FIG. 5, and 24 is a trunk tracking control coil, each of which is fixed to the wire spring 22. The coil 24 is installed in the magnetic flux of the magnet 23, and is constrained by the coil 24? It rotates in the direction of arrow B by flowing II current.

[Problem that the invention seeks to solve]

The conventional disc playback 8 is configured as described above.
Springs 15 and 22 are used for focus control and track tracking control. However, when a spring is used to restrict the operating direction as in this conventional device, these mechanical resonances tend to occur (and have a negative effect on the characteristics of the control device).

Also, it operates against the elastic force of the spring.
Spring dynamic range (linearity of displacement-force relationship)
There is always a limit to this, which poses a problem in terms of control characteristics.

Furthermore, when attempting to simplify the mechanism by using a semiconductor laser as a laser light source, there is a problem in that it is difficult to miniaturize and simplify the overall structure by applying the conventional focal position control device and trunk tracking control device described above. Ta.

This invention was made in view of the above-mentioned drawbacks of the conventional technology, and it is possible to simplify and downsize the device without reducing the accuracy of reading signals from the disk surface, and to improve the linearity of control. It is an object of the present invention to provide a disc playback device that can expand the dynamic range of control and improve response characteristics.

[Means for solving problems]

A disc playback device according to the present invention includes a rotating body that is rotatable around a certain axis and slidable along the axis, and an optical axis of the rotating body that is located eccentrically from the axis. It consists of a condensing means supported so as to be substantially parallel to each other, an annular coil for tracking control provided on the rotating body, and magnets provided opposite to two opposing parts of the annular coil, and the above-mentioned The apparatus is provided with a rotation device that rotates the rotation body to control track deviation, and a thrust drive device that slides the rotation body along the axis to control focus deviation.

[Effect]

In this invention, since the trunk shift and focus shift are controlled using one rotating body that is rotatable around a certain axis and slidable along the axis, each control The device is smaller and simpler than the one that uses separate and independent devices, and since a spring is not used as a means for regulating the direction of movement as in the past, resonance during drive control is prevented. At the same time, linearity is improved,
And the dynamic range is expanded. Furthermore, since a circular coil and a magnet are used as the rotating device, and two opposing parts of the circular coil can contribute to the driving force, the utilization efficiency of the coil is improved and the rotating device can be further miniaturized. becomes possible.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of a main part of an embodiment of the present invention, and in the figure, the same reference numerals as in FIGS. 5 to 8 indicate the same or corresponding parts. 43 is a shaft, a part of which is connected to the yoke 16
It is supported by a slide bearing 40 provided in the body, and is slidable and rotatable. The above slide bearing 40
is made of a material with an extremely low coefficient of friction, such as Teflon. A support plate 44 is connected to the shaft 43 and constitutes a rotating body together with the shaft 43.

30 is a semiconductor laser light source, 31 is a collimating lens, 3
- 5 is a condensing lens constituting a condensing means, and this condensing lens 35 is installed in the support plate 44 so that its optical axis is parallel to the central axis at a position eccentric from the central axis of the shaft 43. is attached to.

Reference numeral 42 denotes a track tracking control coil (hereinafter referred to as a tracking coil) wound in an annular shape, and as shown in FIG. The notch is installed so that the coil 42 coincides with the central axis of the shaft 43, and its magnetic flux is perpendicular to the axis of the shaft 43.3.
Magnets 9 are provided corresponding to two opposing coil portions of the tracking coil 42 and are magnetized in opposite directions. In addition, 18 is the shaft 4
3 is a focus position control coil (hereinafter referred to as a focus control coil); 17 is a magnet provided to face the focus control coil 18;

It is.

Next, the effects will be explained.

In the device configured as described above, when a focus position control current is supplied to the focus control coil 18, the shaft 43
The support plate 44 moves in the six directions of the arrow, and the condenser lens 35 also moves in the direction of the arrow A, so that the focal position is corrected.

Further, when a track tracking position control current is supplied to the tracking coil 42, the shaft 43 and the support plate 44 rotate in the direction of arrow B, and the condenser lens 35 rotates in a direction perpendicular to the track. This is in the direction of arrow B in Figure 3, and actually draws an arc, but the track tracking control amount is 0.
．． The error is approximately 2 to 0.3x*, and if the distance between the condenser lens 35 and the central axis of the shaft 43 is set to several n or more, the error can be almost ignored. Here, in the tiger knocking coil 42 of this embodiment, the two opposing coil parts (the upper and lower parts in the figure) contribute to the driving force for rotation, and the utilization rate of the coil is improved. In other words, the driving force increases, the number of coils can be reduced, and the rotating device can be downsized.

In addition, with this configuration, the focus position control and track tracking control are realized by a device that drives one rotating body, so the entire ZW can be made smaller, and no spring is used to regulate the direction of movement. Therefore, mechanical resonance is less likely to occur, and the dynamic range (linearity of Kerr displacement) is dramatically widened.

Furthermore, since the rotation and sliding directions of the shaft are separated, there is almost no interference between them, and all directions of movement of the shaft are controlled, so there is no problem with the influence of external disturbances as long as they are within the control range.

FIG. 4 is a sectional view of another embodiment of the present invention, in which a semiconductor laser is used as the laser light source, and all optical systems are mounted on a support plate 44, where 45 is a selfoc lens. Other configurations and control operations are the same as in the above embodiment.

In such an embodiment, the optical head becomes more compact and the replaceability is improved, which is preferable in practice.

〔Effect of the invention〕

As described above, according to the disc playback device of the present invention, a rotating body that is rotatable around a certain axis and slidable along the axis is provided, and a rotating body that is eccentric from the axis of the rotating body is provided. The light condensing means is supported at a position such that its optical axis is approximately parallel to the axis, and by rotating the rotating body about the axis, track deviation is controlled, and the optical axis is moved along the axis. Since the rotating body is made to slide to control the focus shift, the optical axis of the condensing means can always be kept perpendicular to the disk surface in both cases of track shift control and focus shift control. This makes it possible to simplify and downsize the device that controls the track deviation and defocus of the focusing means without reducing the accuracy of reading signals from the disk surface. This has the effect of improving response characteristics by expanding the dynamic range of control.

Further, the device for rotating the rotating body is configured with a ring-shaped coil and magnets corresponding to two opposing coil parts of the ring-shaped coil, so that the magnetic flux at each opposing position of the ring-shaped coil can be used for driving force. Therefore, the utilization efficiency of the coil is improved and the device can be further miniaturized.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view showing the configuration of the main parts of an embodiment of the present invention, and Figures 2 (al and bl) indicate the installation state of the rotary drive coil and shaft in the embodiment shown in Figure 1. FIG. 2(b) is a cross-sectional view taken along line bb--b, FIG. 3 is a diagram showing the direction of track tracking on the disk, and FIG. 4 is a diagram showing the direction of track tracking on the disk. A sectional view of another embodiment, FIG. 5 is a sectional view showing the configuration of the main parts of a conventional optical playback device, FIG. 6 is a view showing the relationship between the disk and the track, and FIG. 7 is a view showing the relationship between the condensed light beam and A diagram for explaining the positional relationship of pits on a disk, FIG. 8 is a sectional view of a conventional focus control lens device, and FIG. 9 is a conceptual configuration diagram of a conventional trunk tracking control mirror device. 2.・Laser light, 7... Photodetector, 8... Disk, 13... Pit, 16.37... Yoke, 17
．． 39... Magnet, 18... Focal side control coil, 42... Tracking coil, 19... Support frame, 30... Semiconductor laser light source, 31... Collimating lens, 35... Collection Optical lens, 40... Slide bearing, 43... Shaft, 44... Support plate, 4
5...Selfoc lens. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] (1) Detecting the misalignment of the light spot with respect to the information track of the disc on which information is recorded and the defocus of the light spot with respect to the information recording surface of the disc, and adjusting the position of the light condensing means that forms the light spot on the said track. The information track is controlled according to the detected amount of deviation and defocus, and the information is read out optically from the information track by the light spot irradiated from the controlled condensing means, which is rotatable around a certain axis. and a rotating body that is slidable along the axis; a light condensing means supported at a position eccentric from the axis of the rotating body so that its optical axis is substantially parallel to the axis; A track tracking control coil is provided and is wound annularly so that its magnetic flux is perpendicular to the axis, and a track tracking control annular coil is provided corresponding to two opposing coil portions of the track tracking control annular coil, and is different from each other. a rotating device comprising a magnetic body having magnetic poles, which controls the track deviation by rotating the rotating body; and a thrust drive device, which controls the focal deviation by sliding the rotating body along the axis. A disc playback device comprising: