JPS61294643A - Optical information recording and reproducing device - Google Patents

Abstract

PURPOSE:To simplify a control mechanism and to improve its precision by providing the mirror of an electromechanical transducing element whose swing angle is controllable according to a tracking signal on the optical path of a light beam for tracking and controlling tracking operation through the oscillation of the mirror. CONSTITUTION:The mirror 1 and its base plate 2 are swung by a hinge part 14. When there is a large potential difference between the mirror 1 and base plate 2, and an N+ floating source 8, the mirror 1 is bent around the hinge part 14, and consequently incident light is reflected at an angle twice as large as the angle of deflection of the mirror 1. When the potential difference is small, on the other hand, the drawing force of 7 is small and the parts 1 and 2 are not bent. The incident light is therefore reflected without any deflection of the mirror. When this electromechanical transducing element is used as a tracking mirror 114, a tracking mirror 114 is swung on an analog basis at a faster response speed according to a tracking signal ST from a tracking detecting means, thereby simplifying the control mechanism and improving the precision.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical information recording/reproducing device, and in particular, when a light beam is irradiated onto a recording medium, various information is recorded from k, and this recorded information is The present invention relates to tracking control of an optical information recording/reproducing device used to reproduce recorded information using a light beam.

[Background of the invention]

Recording media on which information can be recorded, reproduced, and erased using a light beam include a base made of a disc-shaped glass, an F9 stick, etc., and a regular
A so-called magneto-optical disk memory comprising a perpendicularly magnetized film having a thickness of 0 to 500× is known. The perpendicularly magnetized film is made of an amorphous alloy or the like, and has the property of being magnetized in a direction perpendicular to the film surface.

To record information on such a magneto-optical disk memory, first apply a perpendicular magnetic field to the magneto-optical disk memory to align the magnetization direction of the perpendicularly magnetized film in one direction, and then digitally record information using an information signal. A modulated laser beam spot is irradiated onto the perpendicularly magnetized film to raise the temperature of the perpendicularly magnetized film at that location to more than one Curie point. Then, the magnetization direction of the part irradiated by the laser beam spot is reversed due to the influence of the surrounding magnetic field, and the logic "l'
, (or @0'') are recorded to form a recording bit.

When reading information recorded on a magneto-optical disk memory, K uses the Kerr effect, in which the perpendicularly magnetized film is irradiated with a reading radar beam spot, and the polarization direction of the reflected beam changes due to the difference in the magnetization direction of the perpendicularly magnetized film. and read.

Furthermore, when erasing information recorded on a magneto-optical disk, the perpendicularly magnetized film is irradiated with an erasing laser beam spot to bring it to a temperature above the Curie point, and a bias magnetic field is applied in the same direction as the magnetization direction of the unrecorded area. All you have to do is apply.

Now, when reading the above information, it is necessary to perform tracking control to cause the recording bit to track the light beam spot. This tracking control uses the well-known three-beam method (for example, the Japanese Patent Publication No. 53-131
(see No. 23) etc. are used. Especially in the case of magneto-optical disk memory.

Since the signal component detected using the Kerr effect is minute,
Tracking control is difficult in the far-field method used for optical discs, and the three-beam method is effective.

FIG. 4 shows an example of an optical information recording/reproducing device using a magneto-optical disk memory. As shown in FIG. 4, the magneto-optical disk 121 is connected to the motor 1 through the spindle 122.
23 at a predetermined speed. In the write system shown in the right half of the figure, a self-modulating semiconductor radar 1
The radar beam emitted from the collimator lens 10
2 and a polarizing beam splitter 10
3. The polarizing beam splitter 103 is configured to transmit P-polarized light and reflect S-polarized light. The polarization direction of the semiconductor radar 101 is arranged so as to be parallel to the plane of the paper.The beam passes through the polarizing beam smitter 103, enters the quarter-wave plate 104, becomes circularly polarized light, and is reflected. It is polarized by 90° by y-105. Furthermore, the beam enters the objective lens e106 and is imaged on the surface of the disk 1210, reversing the magnetization direction of the surface perpendicular magnetization film in that portion of the disk 121 as described above. disk 121
The reflected beam passes through a lens 106 and a mirror 105, is converted into S-polarized light by a quarter-wave plate 104, is reflected by a polarizing beam splitter 103, and enters a detector 108. The incident light is photoelectrically converted into the detector 108,
It is used as a serge signal s (autofocus) to keep the objective lens in focus at all times.

The reading system to which the 3-beam method is applied is shown in the left half of FIG. be divided. These beams pass through a half mirror 113, are reflected by a tracking mirror 114, and are imaged by an objective lens 115 on the surface of the disk 121 as three beam spots. These light beams that hit the disk 121 have their polarization directions rotated by the Kerr effect, and are rotated by the objective lens 115 . Tiger.

)-114 is reflected by a half mirror 113, further divided into two by a half mirror 116, passes through polarizing plates 117 and 118, and passes through detectors 119m and 119b.
, 119c and 1201 are photoelectrically detected. The polarizing plates 117 and 118 are arranged in advance so that the polarization direction is set at a predetermined angle (
For example, the difference is 90').

The three beam spots imaged on the surface of the disk 121 include a central spot and two beam spots that are point symmetrical with respect to the central spot.
When the center spot is correctly positioned on the recording bit string, the spots on both sides cover the recording bit string by half the diameter of the spot. Although the intensities are the same, when the central spot deviates from the recording bit string, there is a difference in the intensity of the reflected light from the spots on both sides, making it possible to detect a tracking error.

The reflected light from the center spot is a detector 119b.

The difference is extracted as an information reproduction signal sl, and a signal for 7 orcasing control (not shown) is detected by a known method.

On the other hand, the reflected light from the spots on both sides is detected by the detector 119.
a and 119c, and the difference is detected and extracted as a tracking signal ST as described above.

The tracking signal S? thus obtained? By moving the tracking mirror 114 or the objective run l''15 in the radial direction of the disk 121 based on this, tracking control or tracking is performed so that the central beam spot for recording and reproduction is always kept on the recording bit string.

An example of an actuator that performs focusing and tracking is shown in FIG.

In the figure, 31 is a base to which yokes 33 and 37 are fixed, 32 is a through hole through which the radar light passes, 34 is a magnet that forms a magnetic field to drive the lens holder 44 in the optical axis direction.
35. 36 is a coil for driving the lens holder in the horizontal direction, and a magnetic circuit is formed by a yoke 37 and a magnet 38. 39 to 42 are support springs that hold the lens holder 44 in a movable range; 43 is an interruption plate for each support spring; and 45 is a lens that focuses the laser beam onto the medium amount. , 36, the lens 45 is driven in the optical axis direction and horizontal direction by the interaction with the magnets 34 and 38, and the laser beam I
Focus control and horizontal position control of the light are performed.

However, as can be seen from the above description, the actuator shown in FIG. 5 has the disadvantage that it has a large number of parts and a complicated structure.

[Purpose of the invention]

It is an object of the present invention to eliminate the above-mentioned drawbacks, to provide an optical information recording/reproducing device that is capable of highly accurate tracking control, and has a simple and complete tracking control mechanism.

[Summary of the invention]

The above purpose is to record and/or reproduce information by irradiating a light beam onto a recording medium, and to use a tracking light in an optical information recording and reproducing apparatus having a tracking signal detection means for an optical V-mus spot. An optical information recording device comprising a shifter of an electromechanical conversion element whose swing angle can be controlled in accordance with the tracking signal in the optical path of the beam, and a tracking operation is performed by swinging the shifter. This is achieved by a playback device.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The optical information recording/reproducing apparatus of the present invention will be described below with reference to the drawings.

First, the electromechanical transducer used in the present invention, such as DW)
(Dsformable Mlrror Device
) will be explained in Fig. 2.

FIG. 2 (11) shows a cutaway view of the DMD. Reference numeral 1 denotes a mirror structure, which is made of materials such as hL and Ag, and plays a role in reflecting incident light. 2 is a substrate that supports the mirror structure of 1 and is made of Au.
It consists of etc. 3 and 4 are support members for 1 and 2, 3 is called a mirror contact, and in particular receives the hinge part that performs electromechanical operation, and 4 is ? It is an insulating material of rioxirS1. '5 is I silicon gut and F
ETMO 8) Shows the role of the run sister groups. 6
is an air gear lug, which has an air gap of 0.6 μ to several μ.

7 is 70-ting field grade, 8's N+
Turn on the transistor from the floating source,
A voltage is applied to the 70-ting field plate of 7 due to the OFF information. 9 indicates an N+ drain. This 4
M08fiFET)? The composition of the register σ plays a role.

10 is r-toxide, and 11 is a PM1 silicon substrate.

Figure 2 (b) is a perspective view from the entrance direction of Figure 2 (1).
2 is an air gap, 13 is a part of the mirror that swings electromechanically, and 14 is a bottom part. 15 is DMDI! Showing part of my mirror. The fake is manufactured using a process similar to that of IC or LSI. Figure 2 (,) shows an electrical equivalent diagram. 16 indicates the voltage vM applied to the mirror 1-92 and the support member K.

17 indicates the voltage V applied to 8. 18 shows the transistor configuration, 9 D (drain) signal, 5 G
(dirt) signal OON, OFF from K to V.

The voltage is turned on and off at 8. At this time, voltage vM is applied to 1 and 2, and a potential difference is ON between 1.2 and 8.
, will be increased or decreased by the OFF signal. At this time, a force according to the following formula is generated between 6 and 7 depending on the potential difference, FcoKVa (K: number of i, V: potential difference α: constant, F = bending force) Mirrors 1 and 2 are at hinge part 4. be swayed. Figure 2 (&
) The left figure shows a case where there is a large voltage difference between 1, 2 and 8, the mirror bends from the hinge, and due to this action the incident light is reflected at an angle twice the deflection angle of the mirror. .

On the other hand, when the voltage difference is small, as shown in the right diagram of FIG. Therefore, the incident light is reflected without touching the mirror.

The DMD element converts electrical ON/OFF into ON/OFF of mirror swing, and further converts into the deflection angle of light.

An electromechanical transducer (e.g. DM
FIG. 1 shows the case where D) is used as a tracking mirror.

In the figure, 114' is an electromechanical transducer used as a tracking mirror. With such a configuration, the tracking signal -8? from the tracking signal detecting means (corresponding to three-beam tracking in the prior art) described in the prior art section is detected. - Tracking with fast response speed according to -114' can be oscillated in an analog manner. This fast response speed is necessary for tracking following the high-speed rotation of the disk, and being able to change the inclination of the mirror surface in an analog manner is essential for tracking control. According to the present invention, it is not necessary to have an actuator with two functions of tracking operation and focus operation as shown in FIG. 5, and only the focus operation is sufficient. The structure of the 21-ta is simple.

FIG. 3 shows an example of an actuator that performs only the seven-occasion operation described above.

As shown in Figure 3, the actuator 51 has a structure in which a holder 56 to which an objective lens 51, a focus coil 55, etc. are attached is attached to a pedestal 56 around a central axis 52. Opposing magnetic poles (ferromagnetic materials) 54a and s4b provided on the holder 56 face arc-shaped permanent magnets 53m and 53b fixed to the pedestal 56. 7. The one-shot operation is performed when the holder 56 to which the objective lens 51 is attached moves in the BB' direction along the central axis 52 by electromagnetic force, and has a very simple configuration compared to the actuator 30 shown in FIG. It is.

The tracking control device of the present invention is not limited to the above-mentioned embodiments, and various applications are possible.

For example, in the explanation of FIG. 1, the tracking mirror 114 of the electromechanical transducer is used only for tracking the reproduction beam.
Although a tracking mirror 114' is used in the recording tracking beam (shown in Figure 1), a tracking mirror 114' may also be used.

Furthermore, it is clear that the electromechanical transducer used in the present invention is not limited to the DMD element, but may be any element as long as it has fast response according to the tracking signal STK and whose mirror surface changes in an analog manner. It is.

Furthermore, the present invention is applicable not only to magneto-optical disks but also to optical information recording and reproducing devices of the type that read and/or write information and track information by irradiating a light beam using other recording media. It is also obvious that the present invention can also be applied to an optical information recording/reproducing device of a type that uses transmitted light instead of reflected light of a light beam irradiated onto a recording medium.

〔Effect of the invention〕

As explained above, according to the present invention, by using an electromechanical transducer for tracking, the angle (deformation amount) of the mirror can be changed in an analog manner, and a fast response of 1 to 7n- is possible. It is now possible to change the actuator at high speed, making it possible to simplify the actuator that previously required a complicated mechanism. Therefore, the device can be made smaller and the manufacturing efficiency can be improved, and tracking operation can be prevented from having an adverse effect on the operation of the autofocus system.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram showing an optical information recording/reproducing apparatus of the present invention. FIG. 2 is a schematic diagram showing the structure of an electromechanical transducer used in the present invention. FIG. 3 is a schematic perspective view showing an actuator that performs only a focusing operation. FIG. 4 is a schematic configuration diagram showing a conventional optical information recording/reproducing device.

Claims (1)

[Claims] (1) In an optical information recording and reproducing apparatus that records and/or reproduces information by irradiating a recording medium with a light beam and has tracking signal detection means for a light beam spot, an What is claimed is: 1. An optical information recording/reproducing device comprising a mirror of an electromechanical transducer whose swing angle can be controlled in accordance with a tracking signal, and performing a tracking operation by swinging the mirror.