JPS58143436A - Optical information readout controller - Google Patents

Abstract

PURPOSE:To permit an optical beam to pass within the effective image circle of an objective lens without fail during tracking drive by providing a reflecting body which is displaced in one body through the operation of a tracking driving means in an oscillator and collimating the optical beam between the objective lens and an optical device. CONSTITUTION:When a disk turns with surface undulation, the lens holding part 9a of the oscillator is displayed upward and downward in parallel through the operation of a moving coil 15 for focusing according to the surface undulation to condense the beam to the recording surface of the disk 1. When the disk 1 turns with only eccentricity, the mirror holding part 9b and lens holding part 9a are driven through the operation of a moving coil 17 for tracking and the objective lens 11 is displaced left and right in parallel according to the eccentricity, thereby finely displacing the beam in a radius direction so that it scans on the track of the recording surface of the disk 1.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device that reads and partially reproduces optical information signals recorded on a disk surface using an optical beam.

When reproducing a video disc or a PCM disc on which optical information has been recorded, it is necessary to perform focusing and tracking control in order to correctly focus an optical beam for reading onto a recording track on the disc surface.

A conventional device for performing such focusing and tracking control is described in Japanese Patent Laid-Open No. 155802/1983. This first leaf spring has one end fixed to the objective lens or its holding member, the other end fixed to another supporting member, and can be bent in a direction perpendicular to the lens optical axis; Similarly, one end is fixed to the objective lens or its holding member, and the other end is fixed to the holding member on the above side,
a second leaf spring that can be deflected in the direction of the optical axis of the lens;
A two-dimensional drive device is used that moves the objective lens in the optical axis direction and in a direction perpendicular to the optical axis. However, according to this conventional example, driving means in the optical axis direction and in the direction perpendicular to the optical axis are arranged concentrically and tracking control is performed, so that only the objective lens follows the recording track on the disk surface. Since the tracking drive means is configured to operate until the image is formed on the center point of the detector that detects the focus and tracking state, the optical axis of the objective lens and the center line of the detector are not aligned. , the optical beam reflected on the recording track passes near the periphery of the effective image of the objective lens. However, in general, the effective flaw inside the objective lens used in this type of device cannot be set large, so if the disk eccentricity is large, the optical beam will pass outside the effective image circle, resulting in a serious drawback that tracking control will be impossible. had.

In view of the above-mentioned drawbacks, an object of the present invention is to provide an optical information reading control device that can always pass an optical beam within the effective image circle of an objective lens even when the tracking drive means is operated, and that does not affect focus detection. Our goal is to provide the following.

The present invention will be explained below with reference to illustrated embodiments.

FIG. 1 is a configuration diagram for explaining the present invention in detail,
A disk 1 on which information signals such as video or audio are optically recorded is rotated by a motor 2 at a predetermined speed. A beam emitted from a semiconductor laser element 4 provided in an optical device 3 passes through an intermediate lens 5 to become parallel light, and after passing through a beam splitter 6 and an information plate 7, it is reflected by a prism 8 and becomes a reading beam. It is said that This reading beam is further reflected by a reflector 10 such as a mirror disposed within the oscillator 9, focused by an objective lens 11, and reflected by the recording surface of the disk 1. The reflected beam is modulated by the recording surface and becomes a reflected beam, which passes through the optical path opposite to the above, is reflected by the beam splitter 6, passes through the condenser lens 12 and the syringe force lens 13, and is received by the detector 14. This detector 14 is a well-known photodetector having four photodetectors,
The focus is detected according to the shape of the spot of the received reflected beam, and at the same time, the reflected beam is converted into an electrical signal.

On the other hand, the oscillator 9 is moved from the lens holding part 9a on which the objective lens 11 is disposed and the mirror holding part 9b to the mirror holding part 9b located below the objective lens 11 by about 4.
A reflector lO inclined at 5@ is provided. Further, the lens holder 9 is connected to the mirror holder 9b by a plate spring or the like, and a focusing moving coil 15 is connected to the lower end of the lens holder 9a, and a permanent magnet 16a is connected to the lens holder 9a.
By applying a control current to the moving coil 15, the objective lens 11 is operated in a direction perpendicular to the disk l. In addition, the moving coil 17 for tracking the mirror is placed in the mirror holding part 9b facing the tracking drive device 18 consisting of a connecting plate, a permanent magnet 18a, and a yoke 18t), and by applying a tracking control current to the moving coil 17, the mirror can be moved. The holding part 9b is operated in the radial direction of the disk 10, and the lens holding part 9a is operated in accordance with this.

Note that the configuration is such that the mirror holding portion 9b is not operated during focus control.

Therefore, when the disk l is currently rotating with only surface wobbling, the tracking moving coil 17 is held at the neutral position because the control current is not applied, and the control current is not applied to the focusing moving coil 15. When energized, the lens holding portion 9a of the oscillator 9 is vertically displaced in parallel according to the surface wobbling of the disk 1, and the beam is focused and condensed on the recording surface of the disk 1. At this time, the lens holding section 9a is operating parallel to the optical axis, but the reflector 10 remains held at the neutral position.

Further, when the disk 1 is rotating with only eccentricity, the focusing moving coil 15 is not energized with a control current and is held at a neutral position, and the tracking moving coil 17 K is not energized with a control current. , actuates the mirror holder 9b.

At the same time, the lens holder 9a is also driven, so the objective lens 11 is displaced horizontally in parallel according to the eccentricity of the disk 1, and the beam is slightly displaced in the radial direction in order to track and scan the track on the recording surface of the disk 1. . At this time, reflector 1
The distance between 0 and the prism 8 changes at the same time, but since the beam between them is parallel, it has no effect on focus control, and only tracking control is activated, and the beam within the effective image circle of the objective lens The beam passes through.

FIG. 2 is a perspective view showing a specific embodiment of the present invention, in which the objective lens 11 is disposed above a lens holding portion 9a formed in a substantially mouth shape. This objective lens 1] is not only attached directly to the lens holding part 9a, but also arranged in the lens barrel.
The lens barrel may be held by the lens holding portion 9a.

A pair of leaf springs 19 and 19, one end of which is fixed to the mirror holding part 9b and the other end of the leaf springs 19 and 19, are respectively fixed to the upper T side of the lens holding part 9a, and are vertically displaced parallel to the optical axis of the objective lens H. The mirror holding part 9b is formed into a substantially hollow prismatic shape, and one end is supported by the other end of two parallel elastic plates 21 and 21 fixed to the frame 20, and the mirror holding part 9b is parallelly displaced in a direction perpendicular to the optical axis of the objective lens 11. do. Approximately 45 mm from the inner wall of the mirror holding portion 9b
A reflector lO is placed on the upper surface of the protruding piece 9C that protrudes at an angle of °.
is installed. The reflector 10 is inserted into the lens holder 9a so as to be aligned with the optical axis of the objective lens 11. Further, a focusing moving coil 15 is integrally fixed to the lower end of the lens holding portion 9a, and the frame 20
It faces into the gap formed by the permanent magnet 16a and the yoke 16b fixed to the yoke 16b. This gap is formed by the mirror holding part 9b.
It is wide in the direction of displacement and narrow in the perpendicular direction.

On the other hand, a coil support piece 9d is attached from the outer wall of the mirror holding part 9b.
The tracking moving coil 17 is integrally fixed to this supporting piece 91 and faces into the gap formed by the permanent magnet 18a fixed to the frame 20 and the yoke at 18°C. This gap is formed to be relatively wide in the direction of displacement of the lens holding portion 9a, and narrow in a direction perpendicular to this.

A through hole (not shown) is formed in the mirror holding portion 9b of the oscillator 9 having such a structure, and the prism 8 with one edge attached to the support frame 20a protruding from the frame 2o is inserted through the through hole. It is inserted. The center of the reflecting surface of the prism 8 coincides with the center of the reflector 10, and the beam is reflected in the direction of the beam splitter 6 via the scent plate 7. An intermediate lens 5 is placed facing the reflective side surface of the field plate 7 of the beam splitter 6, and converts the read beam from the semiconductor laser element 4 into parallel light. In addition, a reflecting prism 22 is provided on the lower surface of the beam splitter 6, and the reflected beam of parallel light is reflected, guided to a condensing lens, and condensed.
Let the light enter. Then, the same operation as described in FIG. 1 above is performed. A hole 20b formed in the frame 20 is inserted with a guide rod or a spiral rotating rod provided in a transfer device of a disk player (not shown), and this transfer device allows the above-mentioned information reading control device to move the disk. Transport according to the truck.

According to the present invention described above, at least the optical beam between the objective lens and the optical device is made into a parallel beam, and the distance between the reflector and the optical device, which are integrally displaced by the operation of the tracking drive means, is changed. Therefore, even if tracking control is performed, focus control will not be affected in any way. In addition, the center line of the objective lens and the detector can be kept in alignment by the operation of the tracking drive means, so the optical beam passes near the center of the effective scratch on the objective lens, even if the eccentricity of the disk is large. The tracking control state can always be maintained even if there is a problem. Moreover, since the oscillator can be reduced to the minimum unit of component that needs to be displaced, the response characteristics and accuracy with respect to surface runout and eccentricity of the disk can be improved.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a J factor for explaining the principle, and FIG. 2 is a partially cutaway perspective view showing a specific example. DESCRIPTION OF SYMBOLS 1... Disc 3... Optical device 9... Oscillator lO... Reflector 11... Objective lens 15... Moving coil for focus 16... Focus drive device 17... For tracking Moving coil 18...
tracking drive device

Claims (1)

[Claims] In a signal reading device that reads and reproduces information signals by relatively scanning a recording track on a disk surface with an optical beam focused by an objective lens, the objective lens disposed inside an oscillator is used to scan the recording track on the disk surface. A reflection that is displaced by a focus drive means that operates perpendicularly to the recording surface and a tracking drive means that operates in the radial direction of the disk, and that is displaced within the oscillator integrally with the operation of the tracking drive means. An optical device for emitting and receiving the light beam is fixedly arranged near the oscillator, and at least the optical beam between the objective lens and the optical device is made into parallel light. . An optical information reading control device, characterized in that the distance between the reflector and the optical device is changed by the operation of the tracking drive means.