JPH0320818B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an optical recording/reproducing device.

Conventional Structures and Problems The optical video disc and compact disc player are well known as optical recording/reproducing devices. In addition, optical recording and reproducing devices that utilize crystal changes and changes in reflectance of recording media using amorphous materials, and magneto-optical disk recording and reproducing devices that apply magneto-optical effects are well-known recording and reproducing devices. There is.

A conventional optical recording/reproducing device will be explained using FIG. 1. The light emitted from the light source 1 passes through the collimating lens 2 and the half mirror 3, is focused into a minute spot by the objective lens 4, and is reflected by the recording medium 5. This reflected light passes through the objective lens 4 and is focused by the half mirror 3. It is reflected, passes through a convex lens 6, and enters a photodetector 7. The photodetector 7 uses the reflected light from the recording medium 5 to detect a relative position detection signal between the objective lens 4 and the recording medium 5 (focus error signal) and a relative position signal between the optical spot and the signal track (tracking error signal). is obtained. The focus direction objective lens drive element 10 is driven by the output signal of the focus direction objective lens drive circuit 9 which receives the output of the phase compensation circuit 8 which receives the focus error signal as input.
to perform focusing control. The same applies to tracking control. However, the focus error signal and the tracking error signal are obtained from reflected light from the recording medium 5, and the reflected light is affected by scratches, dust, etc. on the surface of the recording medium 5 and contains a lot of noise. Therefore, if the objective lens 4 is driven using a signal containing this noise, there is a problem that the servo system becomes unstable. In addition, in Figure 1, 11
1 is a phase compensation circuit, 12 is a tracking direction objective lens drive circuit, and 13 is a tracking direction objective lens drive element.

OBJECTS OF THE INVENTION The present invention solves the above-mentioned conventional drawbacks, and an object of the present invention is to provide an optical recording/reproducing device that can suppress instability of the servo system due to noise and stabilize the servo.

Structure of the Invention In order to achieve the above object, the optical recording/reproducing apparatus of the present invention includes a light source that generates a light beam for recording/reproducing, and a light beam from the light source that is converted into a minute spot light on a recording medium. a first direction parallel to the focus direction between the objective lens and the recording medium and a second direction parallel to the recording surface and perpendicular to the track direction from the reflected light from the recording medium; a first detection means for detecting the relative position of the object lens and outputting a focus error signal and a tracking error signal; a detection light source attached to the objective lens; a two-dimensional planar optical position detection element disposed parallel to a second direction, and detects the displacement of the objective lens from the stopping position in the first direction and the second direction, and generates a focus displacement signal. a second detection means for outputting a tracking displacement signal; and a signal obtained by compensating the phase of the signal from the second detection means, and a signal from the first detection means to move the objective lens in the first direction and the second detection means. This configuration includes an objective lens drive device that drives in the second direction.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 is an overall configuration diagram of the optical recording/reproducing apparatus, and the same components as those shown in FIG. 1 are given the same reference numerals and their explanations will be omitted. In FIG. 2, 14 is a two-dimensional objective lens position detector, 16 is a phase compensation circuit, 17 is a subtracter,
18 is a phase compensation circuit, and 19 is a subtracter.

Light from a light source 1 passes through a collimating lens 2 and a half mirror 3, is focused into a minute spot by an objective lens 4, and is irradiated onto a recording medium 5. Recording medium 5
The reflected light passes through the objective lens 4, is reflected by the half mirror 3, passes through the convex lens 6, and reaches the photodetector 7.
incident on . The output signal of the phase compensation circuit 16 and the photodetector 7 receive the displacement signal output from the focus direction objective lens position detector 14 which detects the displacement of the objective lens 4 from its rest position in the focus direction.
A servo system that drives a focus direction objective lens drive element 10 with the output of a focus direction objective lens drive circuit 9 that receives a difference signal between the focus error signal and the focus error signal from the servo system to maintain a constant distance between the objective lens 4 and the recording medium 5. Configure. The same applies to tracking control. Note that a sum signal may be used instead of the difference signal between the displacement signal and the error signal.

FIG. 3 is a perspective view of a means for directly detecting the two-dimensional displacement of the objective lens 4 in the focusing direction and the tracking direction, using a two-dimensional planar optical position detecting element 24. FIG. That is, the two-dimensional plane optical position detection element 24, which is disposed facing the light source 25 attached to the objective lens 4, parallel to the focus direction and perpendicular to the signal track direction, detects the displacement in the focus direction and the surface of the recording medium. displacement in the direction perpendicular to the signal track.

Effects of the Invention As explained above, according to the present invention, focusing control and tracking control are performed using the position signal of the objective lens which is not affected by scratches, dust, etc. on the surface of the recording medium.
A stable servo system can be obtained, and recording/reproducing characteristics can be dramatically improved.

Further, by using two-dimensional plane position detection elements, position detection can be performed with a simple configuration using a small number of elements.

[Brief explanation of the drawing]

FIG. 1 is an overall configuration diagram of a conventional device, FIG. 2 is an overall configuration diagram of an optical recording/reproducing device in an embodiment of the present invention, and FIG. 3 is a perspective view of a second detection means in this embodiment. be. 1...Light source, 2...Collimating lens, 3...
Half mirror, 4...Objective lens, 5...Recording medium, 6...Convex lens, 7...Photodetector, 9...Focus direction objective lens drive circuit, 10...Focus direction objective lens drive element, 12... Tracking direction objective lens drive circuit, 13... Tracking direction objective lens drive element, 14... Two-dimensional objective lens position detector, 16, 18... Phase compensation circuit, 17, 19... Subtractor, 20, 21, 25
... Light source, 22, 23 ... Optical position detection element, 24
...Two-dimensional planar optical position detection element.

Claims (1)

[Claims] 1. A light source that generates a light beam for recording and reproduction, an objective lens that narrows the light beam from this light source into a minute spot light on a recording medium, and a light beam reflected from the recording medium that focuses on the objective lens and the recording medium. a first direction parallel to the focus direction and a second direction parallel to the recording surface and perpendicular to the track direction and output a focus error signal and a tracking error signal; It has a detection means, a detection light source attached to the objective lens, and a two-dimensional planar optical position detection element facing the detection light source and arranged parallel to the first direction and the second direction. a second detection means for detecting displacement of the objective lens from a stop position in the first direction and the second direction and outputting a focus displacement signal and a tracking displacement signal; an objective lens driving device for driving the objective lens in the first direction and the second direction using a signal obtained by compensating the phase of a signal from the means and a signal from the first detection means; playback device.