JPS62125546A - Optical recording and reproducing device - Google Patents

Abstract

PURPOSE:To control an optical axis with no malfunction by using a disk containing a specific area on its recording surface where the light reflection factor is constant on the average and also performing the control of the optical axis only when the light delivered from a light emitting element is irradiated on said specific area. CONSTITUTION:A tilt detecting area 5 where no recording is carried out with a constant light reflection factor is provided to an optical disk 1 and detects the tilt produced between the surface of the disk 1 and the optical axis of a light beam. The area 5 is retrieved by the retrieving signal (a) given from a system controller 25. While a light emitting element 4 and the light receiving elements 40 and 42 are shifted and set in the area 5. The outputs (b) and (c) of both elements 40 and 42 are unbalanced only when the tilt between the disk surface and the beam optical axis is not vertical. Then an optical axis control motor 37 is controlled by the difference signal (d). In such a way, the optical axis is controlled with no malfunction.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention provides information storage such as a video signal on a disc-shaped recording medium.
The present invention relates to an optical recording and reproducing apparatus that performs optical axis control of a light beam at a rate of 1%, with respect to an optical recording and reproducing apparatus that records or reproduces information in the form of optical characteristic changes in the medium.

[Background of the invention]

In an optical recording/reproducing device, the recording medium is generally a disk-shaped medium that is provided with a spiral or concentric guide trunk and address information for identifying each guide track so that information can be recorded at high density. (hereinafter referred to as an optical disc) is used. The light beam from the laser light source is irradiated as a light spot onto the guide track of the optical disc using well-known focus and tracking control, and during recording, the light output intensity of the laser light source is modulated by the recording signal to reduce the reflection of the light irradiation area. On the other hand, during reproduction, the optical output intensity of the laser light source is set to a constant output lower than that during recording, and the recorded information is reproduced by detecting the change in optical characteristics.

In such optical recording and reproducing devices, there is a trend toward higher densities in the future due to the economic efficiency of recording media and miniaturization of devices, and to achieve this, recording wavelengths are becoming shorter and narrower. The demand for trucks is increasing.

One of the problems that arises as the tracks of optical discs become narrower is crosstalk from adjacent tracks. Particularly, when the optical beam is no longer incident perpendicularly to the disk surface due to warping of the optical disk, the shape of the light spot changes from a circle to an oval, making it easier to detect signals from adjacent tracks.

As a method to solve the above problems, for example,
There is one described in Japanese Patent No.-16883.

In this method, the light emitted from the light emitting element 41 is reflected by the optical disk 1, and the reflected light is is detected by the two light-receiving elements 4o and 42, and the difference in the amount of reflected light is detected.The direction of the optical axis of the light beam is controlled so that the difference becomes zero, and the direction of the optical axis and the disc are adjusted so that the difference becomes zero. Make sure the surface is perpendicular. but,
Since this method uses light reflected from the disk surface, it is easily affected by the reflectance of the disk surface.

In particular, in an optical recording and reproducing device that records information by changing the reflectance of the recording material of an optical disk and then reproduces the information by detecting the change in reflectance, recorded areas and unrecorded areas are separated. When mixed optical discs were used, the following problems arose.

That is, since the reflectance of light is different between the recorded part and the unrecorded part, the output of the light receiving element 40 and the output C of the light receiving element 42 are different from each other in the unrecorded part 1a and the recorded part 1b as shown in FIG.
．． The changes shown in (2) are shown.

At this time, especially near the boundary between the unrecorded portion 1& and the recorded portion 1b, even if the optical axis of the light beam is perpendicular to the disk surface, the amount of light incident on the light receiving element 40, 42 becomes unbalanced. Therefore, when output, the value of the output C will be different, and the difference signal d will not be zero as shown in FIG. 5(3).

Therefore, the difference signal d between the outputs b=c of the light receiving elements 40 and 42
If an attempt was made to control the optical disc so that it became zero, the optical axis of the light beam would be tilted with respect to the disk surface, resulting in a problem of malfunction.

[Purpose of the invention]

The purpose of the present invention is to solve the problems of the prior art described above,
All recording is performed as changes in the reflectance of the recording medium.

In addition to detecting the change in reflectance and performing playback, it is also possible to accurately detect the inclination between the disc surface and the optical axis of the light beam, even for optical discs that have both recorded and unrecorded parts. An object of the present invention is to provide an optical recording/reproducing device that can control a beam to be irradiated perpendicularly to a disk surface.

[Summary of the invention]

Therefore, in the present invention, we have focused on the fact that the inclination of the disk surface is almost constant regardless of the radial position of the disk, and we have developed an optical disk that has a constant average reflectance of light on the inner or outer circumference of the disk surface. A disk with a defined area is used, and by detecting the tilt between the disk surface and the optical axis of the light beam in this specific area, the optical axis is controlled so that the light beam is irradiated perpendicular to the disk surface. Thereafter, normal recording/reproducing operations were started, and the optical axis control was turned off during the recording/reproducing state.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a plan view showing external demand for optical discs used in an embodiment of the present invention. On optical disc 1,
Recording area 2° in which concentric guide tracks for recording information at high density are formed Address area 6 in which address information for identifying each guide track is formed in a concave-convex phase structure. Along with a recording start position mark 4 for aligning the recording start position in the disk radial direction, there is also a tilt detection area with a constant reflectance for non-recording light in order to detect the tilt between the disk surface and the optical axis of the light beam. 5 is provided. For example, the guide track of the tilt detection area 5 is 9900.
Addresses from 0 to 99999 are assigned.

FIG. 2 is a block diagram showing the configuration of an optical recording/reproducing apparatus as an embodiment of the present invention. The output light of the semiconductor laser 6 is first converted into parallel light by a condensing lens 7, and then converted into parallel light with a roughly circular cross section by a concave-convex cylindrical lens 8.
f: passes through, enters the objective lens 13 attached to the actuator 12, and is focused on the optical disc 1 as a light spot). The reflected light from the optical disk 1 passes through an objective lens 13 and a K wavelength plate 11, is guided by a beam splitter 10 toward a convex lens 14, is split by a mirror 15, and one is incident on a two-split photodiode 16. The difference between the outputs of the photodiodes 16 is taken by a differential amplifier circuit 17, and a tracking error signal corresponding to the deviation between the guide track on the disk 1 and the optical spot is obtained. The actuator 12 is driven in the disk radial direction via the drive circuit 19, and the deviation between the guide track and the optical spot is 01-
Control is performed as follows. On the other hand, the output of the tracking drive circuit 19 is also input to the phase compensation amplifier circuit 20, which drives the carriage feed motor 22 via the drive circuit 21, and depending on the playback position of the optical disc 1, an optical block consisting of a semiconductor laser 6, etc. The carriage 24 carrying the disc 26 is moved in the radial direction of the disc. In addition, the drive circuit 21 drives the carriage feed motor 22 to move the carriage 24 in the disk radial direction at high speed to perform a well-known search operation according to a search signal a from a system control 25 composed of a microcomputer or the like. .

The other light split by the mirror 15 enters a two-split photodiode 26 placed at the focal point of the convex lens 14 . The difference between the outputs of the photodiodes 26 is taken by a differential amplifier circuit 27, and a seven-occasion error signal corresponding to the distance between the objective lens 13 and the disk 1 is obtained. The focus error signal is sent to the phase compensation amplifier circuit 28. Actuator 12'! via focus drive circuit 29! - The objective lens is controlled to maintain the focal position with an accuracy of 1 μm or less by driving in a direction perpendicular to the disk surface. On the other hand, the outputs of the photodiodes 26 for focus error detection are added by an adder circuit 30, address information provided on the optical disc 1 is demodulated by an address demodulation circuit 31, and inputted to the system control 25.

Next, the optical axis control circuit 32 according to the present invention will be explained. The optical axis control circuit 32 includes a differential amplifier circuit 33, a phase compensation amplifier circuit 34, a drive circuit 35. switch 36, optical axis control motor 67, absolute value circuit 38. It is composed of a comparator 39.

As for its operation, first, a search signal a from the system control 25 is used to perform a well-known search operation, for example, 9.
The light emitting element 41 and the light receiving element do search address 9500 and detect the inclination between the disk surface and the optical axis of the light beam. 12 moves the carriage 24 in the inner circumferential direction of the optical disc 1 so that it is located in the tilt detection area 5 of the optical disc 1.

Thereby, the light output from the light emitting element 41 is reflected by the tilt detection area 5 and enters the light receiving element 40.42. Since the reflectance in the tilt detection area 5 is constant as described above, the amount of incident light at this time becomes unbalanced only when the tilt between the disk surface and the optical axis of the light beam is not perpendicular. At this time, the outputs S and c of the light receiving elements 40 and 42 and the difference signal d(i
- Shown in Figure 3. After the absolute value of the difference signal d is taken by the absolute value circuit 38, the difference signal d is converted to the base '! by the comparator 39. IA'1jf8
It is compared with EVref. If the deviation from the vertical of the inclination between the disk surface and the optical axis of the light beam θ is more than the predetermined value θ0, and the absolute value of the difference signal d is greater than the reference voltage Vref, the comparator 39 outputs a predetermined level. The tilt detection signal θ (for example, H1gh level) is output to the system control 25. The system control 25 detects from the level of the tilt detection signal e in the tilt detection area 5 that the above-mentioned deviation from the vertical: θ is a predetermined value 00 or more, and turns on the switch 36' (ON. The difference signal d corresponding to the amount of deviation θ from
7, tilting the optical block 23 and producing a difference signal d
Control is performed so that it becomes zero. When the inclination between the optical axis of the light beam and the disk surface becomes substantially perpendicular and the absolute value of the difference signal d becomes equal to or less than the reference voltage Vref, the comparator 39
outputs a tilt detection signal θ at a predetermined level (for example, LOW level) to the system control 25. The system control 25 detects from the level of the tilt detection signal e that the deviation amount θ of the tilt from the vertical between the optical axis of the light beam and the disk surface has become less than a predetermined value 00, and turns the switch 36k OFF. Thereafter, the inclination of the optical block 26 is maintained.

FIG. 4 is a perspective view showing a specific example of the carriage 24 on which the optical block 23 shown in FIG. 2 is mounted. Optical block 23 is supported by shaft 43 and optical block 25
seems to rotate around this. Further, a rotary gear 44 is formed on the bottom surface of the optical block 25, and the shaft holes 47 of the two side plates 46 are arranged so that the rotary gear 44 meshes with the worm gear 45 of the optical axis control motor 37 installed on the carriage 241C. The shaft 43 is pushed back.

Note that 48 is the carriage feed motor 22 shown in FIG.
This is a feed screw that moves the carriage 24 in the disk radial direction.

From the outputs of the light receiving elements 4o and 42 attached to the optical block 25, a differential amplifier circuit 33 shown in FIG. A difference signal d is obtained, which is sent to the phase compensation circuit 54,
Optical axis control motor 3 via drive circuit 35 and switch 36
7 and the optical axis ↑□□□ motor 37 rotates, thereby rotating the optical block 23 and controlling the inclination between the optical axis of the light beam and the disk surface to be approximately perpendicular.

Note that the tilt detection area 5 only needs to have a constant light reflectance, and test signals may be recorded in advance on all guide tracks in the tilt detection area 5, or all guide tracks may be unassigned. It may be in a recorded state.

〔Effect of the invention〕

As explained above, since the inclination of the disk is almost constant regardless of the radial position, in the present invention, the inclination between the disk surface and the optical axis of the light beam is detected at the inner or outer circumference of the disk. To.

Is it possible to establish a specific area where the average reflectance of light is constant and control the optical axis in this area? Therefore, it is possible to always irradiate the light beam perpendicularly to the disk surface without malfunction even on a disk where recorded portions and unrecorded portions coexist.

[Brief explanation of drawings]

FIG. 1 is a plan view showing the appearance of an optical disc used in an embodiment of the present invention, FIG. 2 is a block diagram showing the configuration of an optical recording/reproducing apparatus as an embodiment of the invention, and FIG. 6 is a disc An explanatory diagram for explaining the operation of detecting the inclination between the surface and the optical axis of the light beam, FIG. 4 is a perspective view showing a specific example of the optical block and carriage in FIG. 2, and FIG. 5 is a diagram showing the disk surface. FIG. 3 is an explanatory diagram for explaining the conventional detection operation of the inclination between the optical axis of the optical beam and the optical axis of the optical beam. DESCRIPTION OF SYMBOLS 1... Optical disc, 2... Recording area, 3... Address area, 5... Tilt detection area, 6... Semiconductor laser. 12... Actuator, 13... Objective lens, 2
3... Optical block, 24... Carriage, 25...
... System control, 32... Optical axis control circuit,
36... Differential amplifier circuit, 34... Phase compensation amplifier,
35... Drive circuit, 36... Switch, 37... Optical axis control motor, 68... Absolute value circuit, 39... Comparator, 40. 42... Light receiving element, 41... Light emitting element. . Representative patent attorney Katsuo Ogawa “%1 mouth’j!r1ml’s 4th business 5 mouths

Claims (1)

[Claims] 1) A light beam is irradiated onto the recording surface of an optical disk to record information on the recording surface, or a reproduced signal is obtained by receiving reflected light from the recording surface of the irradiated light beam. an optical pickup means; a light emitting element mounted on an optical block together with the optical pickup means emits light onto the recording surface of the optical disk; the reflected light is received by a light receiving element; and the amount of light from the optical pickup means is determined by the amount of received light a detection means for detecting an inclination between the optical axis of the beam and the recording surface, and rotation for rotating the optical block in a rotational direction about an axis located in a direction perpendicular to the radial direction of the optical disk; and a transport means for transporting the optical block in the radial direction of the optical disk, the optical pickup means rotating the optical block by the rotation means in response to a detection output from the detection means. In an optical recording and reproducing apparatus that performs optical axis control so that the optical axis of a light beam from a disc is almost perpendicular to the recording surface, the optical disc has a recording surface with a constant reflectance of light on average. In addition, the optical axis control is performed only when the optical block is transferred by the transfer means and the light from the light emitting element of the detection means is irradiated onto the specific area. An optical recording/reproducing device characterized by: 2) In the optical recording/reproducing device according to claim 1, the specific area of the optical disc is an area where no information is recorded or an area where a test signal is recorded. An optical recording and reproducing device characterized by: