JPH011124A - optical head - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field 1] The present invention relates to an optical head, and particularly to optically writing information onto a disc-shaped information recording medium.

The present invention relates to an optical head of an optical disc device that performs reading.

[Prior Art] Conventionally, an optical head of an optical disk device or the like detects the focal deviation or tracking deviation of a light beam due to surface deflection or eccentricity of a rotating optical disk, etc., and drives an objective lens using the detected error signal. It has a focus pivot mechanism that automatically focuses on the surface of a medium such as an optical disk, and a tracking servo mechanism that makes the light beam follow the track, and the servo mechanism focuses the light beam on a predetermined track. , and is configured to write and read information.

[Problems to be Solved by the Invention] In order to satisfy the above-mentioned functions, conventionally, an objective lens of an optical head of an optical disk device, etc. is held within an actuator by a leaf spring or the like, and the entire optical head is held by a blade spring. Although it is possible to move in the radial direction of an optical disk, etc., when a light beam is focused on an arbitrary track and made to follow it, the position of the objective lens within the actuator cannot be easily detected.

An object of the present invention is to provide an optical head (2) that eliminates the above-mentioned problems.
It is about providing.

[Means for Solving the Problems] The present invention focuses light emitted from a recording/reproducing light source onto the surface of a medium such as an optical disk using an objective lens, and performs recording/reproducing in an optical head of an optical disk device or the like that records/reproduces information. a mirror fixed to the objective lens so as to reflect a part of the recording/reproducing light emitted from the optical source and incident on the objective lens in a direction including a component perpendicular to the focus direction and the track direction; An optical system comprising: a semiconductor two-dimensional position detecting element having a light detection surface that receives a part of recording and reproducing light; and a mechanism for extracting the output of the semiconductor two-dimensional position detecting element as a sum signal and a difference signal. It is the head.

[Example] Next, one embodiment of the present invention will be described using the drawings.

Figures 1 (a) and (b) are side and front views showing one embodiment of the present invention, Figure 2 is a principle diagram showing the operating principle of the present invention, and Figure 3 is a semiconductor used in the present invention. FIG. 2 is a principle diagram showing the principle of detecting the position of a light spot using a two-dimensional position detection element.

In FIGS. 1(a) and 1(b), the optical head of the present invention directs a part of the recording/reproducing light 4 emitted from the recording/reproducing light source and incident on the objective lens 2 in a direction perpendicular to the focus direction and the track direction. A semiconductor two-dimensional position detection element comprising a mirror 5 fixed to the objective lens 2 so as to reflect the light in a direction including the component, and a light detection surface that receives a part of the recording/reproducing light 4 reflected by the mirror 5. 3, and an output mechanism 8 for extracting the output of the semiconductor two-dimensional position detection element as a sum signal and a difference signal.

Recording and reproducing light 4 emitted from a recording and reproducing light source is focused by an objective lens 2 onto a predetermined track on the information recording surface of the optical disc 1, and information is recorded and reproduced.

Here, a part of the recording and reproducing light 4 is reflected by a mirror fixed to the objective lens 2 in a direction perpendicular to the focus direction Y#Y' and the track direction X#X', and this reflected light 6 is The light is made perpendicular to the detection surface of the semiconductor two-dimensional position detection element 3.

Here, to explain using FIG. 2, the objective lens 2 is equipped with two
When the mirror 5 is moved to the position ', the mirror 5 fixed to the objective lens moves to the position 5', so the reflected light 6 moves to the position 6'.

Based on the same principle, when the objective lens 2 moves in the X#X' direction in FIG. 1(b), that is, in the track direction, the reflected light 6 reflected by the mirror 5 is
It moves in the direction of the track according to the movement of U.

Here, explanation will be made using FIG. 3. Assume that the light spot 7 of the reflected light 6 reflected by the anti-reflection mirror 5 moves to the position (x, y) from the center of the semiconductor two-dimensional position detection element 3 in accordance with the movement of the objective lens 2 as described above. The moving distances X, y are determined by the outputs Y+, Y2 taken out from the electrodes in the focus direction of the semiconductor two-dimensional position detection element 3 and the outputs X1 . X2,
It is expressed by the following equation using the length 2L of one side of the photodetection surface of the semiconductor two-dimensional position detection element 3, etc.

X2 XI X Y2-Yt y Yl+Y2 L That is, the output Y1. The output mechanism 8 takes out the sum signal and difference signal of Y2 and the outputs X+ of the electrodes arranged in the track direction, the sum signal of X2, and the difference signal, and calculates the ratio of each sum signal and difference signal. The moving distance of the reflected light 6 reflected by , that is, the movement of the objective lens WIJ#, can be used to determine the position of the objective lens.

Incidentally, since the operating principle of the semiconductor two-dimensional position detection element is a well-known fact, detailed explanation will be omitted.

[Effects of the Invention] As explained above, by using the optical head of the present invention, there is an effect that position signals of the objective lens in the focus direction and the track direction can be easily obtained.

[Brief explanation of the drawing]

FIG. 1(a) is a side view showing one embodiment of the present invention, FIG. 1(b) is a front view of the same, FIG. 2 is a principle diagram showing the operating principle of the present invention, and FIG. 3 is a two-dimensional semiconductor FIG. 2 is a principle diagram showing the principle of position detection using a position detection element. 1... Optical disk 2... Objective lens 3...
・Semiconductor two-dimensional position detection element 4...Information recording/reproduction light 5...Mirror 6...Repulsion light 7...Light spot 8...Output mechanism

Claims (1)

[Claims] (1) The light emitted from the recording/reproducing light source is focused onto the surface of a medium such as an optical disk by an objective lens, and then is emitted from the recording/reproducing light source and incident on the objective lens in an optical head of an optical disk device or the like that records and/or reproduces information. a mirror fixed to the objective lens so as to reflect a portion of the recording and reproducing light in a direction including a component perpendicular to the focus direction and the track direction; and a mirror that receives a portion of the recording and reproducing light reflected by the mirror. An optical head comprising: a semiconductor two-dimensional position detecting element having a photodetecting surface; and a mechanism for extracting the output of the semiconductor two-dimensional position detecting element as a sum signal and a difference signal.