JPH05166222A - Separation type optical pickup device - Google Patents

Abstract

PURPOSE:To prevent the decrease in the angle change of a light beam by as much as the magnification rate of a shaping prism by the detection of the tracking position utilizing the reflected light of the incident surface of the shaping prism at the time of writing/reading out of data by simultaneous verification. CONSTITUTION:A tracking mirror 6 is disposed between a semiconductor laser 3 and the shaping prism 7 in the optical path of the exit beam from the semiconductor laser 3. A photodetector 18 is commonly used for angle detection of the tracking mirror 6 and output detection of the semiconductor laser 3 by utilizing the reflected light of the incident surface 7a of the shaping prism. As a result, the tracking control and the control for maintaining the quantity of the beam emitted from the semiconductor laser 3 constant are executed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a separation type optical pickup device comprising a fixed optical system and a moving optical system, and more particularly,
The present invention relates to a separation type optical pickup device that performs simultaneous verification.

[0002]

2. Description of the Related Art Generally, an optical pickup device is well known as a device for recording and reproducing information on an optical information recording medium such as an optical disc or a magneto-optical information recording medium such as a magneto-optical disc. Various types have been put into practical use.

In recent years, in response to the demand for high-speed access, an optical pickup device is constructed by separating it into a fixed optical system and a moving optical system, and only the moving optical system on which an objective lens is mounted is moved to perform access. A type optical pickup device has been proposed.

In such a separation type optical pickup device, since only the moving optical system is moved, the weight of the movable part can be reduced as compared with the integrated type optical pickup device, and high speed access can be realized.

In the above-mentioned separation type optical pickup device, in order to further reduce the weight of the moving optical system, the moving optical system has an objective lens, a focus actuator,
Tracking control is performed by mounting a deflection member.
A tracking optical system has been developed in which a fixed optical system is provided with a tracking mirror and this tracking mirror is used.

For example, Japanese Patent Application No. 02-203433 discloses such a separation type optical pickup device. In the separation-type optical pickup device disclosed in the publication, a tracking mirror is provided in a fixed optical system to perform tracking control by a pre-wobbling method, and the tilt angle of the tracking mirror is detected, and based on the detection result. The moving optical system is driven to correct the deviation between the optical axis of the incident light beam incident on the information recording medium and the optical axis of the return light beam reflected by the information recording medium.

In the above apparatus, the tracking mirror is arranged between the semiconductor laser and the polarization beam splitter, a part of the incident light beam is reflected by the polarization beam splitter, and the reflected light is detected to determine the tilt angle of the tracking mirror. I am trying to detect.

On the other hand, in an optical storage device such as an optical disk device, a plurality of beams are passed through an objective lens of an optical head, and for example, a write beam and a read beam are used to write data by a write beam to a certain track. , By writing information to the optical recording medium by reading the information written by the write beam by the read beam located behind the write beam in the disc rotation direction, that is, by simultaneously performing data writing and verify read. Techniques for reducing time are being researched.

For example, Japanese Unexamined Patent Publication No. 02-240838 discloses a device for simultaneous verification in which a write beam and a read beam are simultaneously emitted from one objective lens and the above-described verify read is performed simultaneously while writing data by the write beam. ing.

In the above apparatus, the separating optical system is provided with the above-mentioned simultaneous verification function, and the position of the spot for writing is controlled by the actuator of the objective lens, and the position of the spot for reading is detected by a galvano mirror. I am trying.

[0011]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
In the separation type optical pickup device disclosed by Japanese Patent No. 3433, as shown in FIG. 1 of the above publication, a polarization beam splitter for detecting the tilt angle of the tracking mirror is provided in addition to the polarization beam splitter for normal signal detection. It is arranged. For this reason, the transmission efficiency of the light beam is reduced, the amount of light emitted from the objective lens is insufficient, information cannot be accurately recorded on the information recording medium, and the number of parts of the fixed optical system increases.

Further, although there is no description of a shaping prism in the above-mentioned Japanese Patent Laid-Open No. 02-203433, generally, in an optical pickup device, shaping is performed on the objective side of a collimator lens for collimating a light beam emitted from a semiconductor laser into a parallel light beam. A prism is arranged so that the light beam from the semiconductor laser is shaped into a circle.

Therefore, in the device of the publication, a part of the light beam shaped by the shaping prism is taken out by the polarization beam splitter for detecting the tilt angle of the tracking mirror, and the tilt angle of the tracking mirror is detected. Become. However, the light beam emitted from the shaping prism has a smaller change in angle depending on the shaping magnification of the beam.

For example, as disclosed in FIG. 2 of Japanese Patent Application No. 3-193351, when the angle of the shaping prism is 39 ° and the beam expansion ratio is 2.5, the incident angle is 71.89. When the light beam is incident on the shaping prism at an angle of °, the expanded light beam is emitted perpendicularly to the emission end face of the prism.

Then, the incident angle is changed by 1 ° to reach 72.8.
When the light beam is incident on the shaping prism at 9 °, the light beam after beam expansion is emitted in the direction of 0.4 ° with respect to the vertical plane of the exit end face of the prism, and the angle change is 1/2. It becomes as small as 0.5. For this reason, there is a problem that the detection sensitivity of the tilt angle of the tracking mirror becomes low.

On the other hand, in the case of a recording / reproducing optical disk device,
Most of the semiconductor laser outputs are monitored in front, so it is necessary to consider the tracking position detection.
As shown in FIG. 5 of JP-A-02-240838, it is necessary to newly provide a light emitting portion 55, a slit 56, and a two-divided photodetector 57 of the galvano position sensor 222 in order to perform tracking error position detection. Therefore, the supporting system and the driving system provided in the vicinity of the tracking mirror are complex and large fixed optical systems.

The separation type optical pickup device of the present invention has been made in view of the above problems, and an object thereof is to utilize the reflected light of the incident surface of the shaping prism at the time of writing / reading data by the simultaneous verification. An object of the present invention is to provide a separation-type optical pickup device that prevents a change in angle on the light-receiving surface by the magnification of the shaping prism due to tracking position detection.

[0018]

In order to achieve the above object, in the separation type optical pickup device of the present invention, a movable optical system that is movable in a predetermined direction with respect to an optical recording medium and a movable optical system described above are provided. A separate optical pickup device comprising a fixed optical system fixed to the optical recording medium, a first light source for supplying a first light beam emitted to the optical recording medium, and a first light source for emitting the optical beam to the optical recording medium. A second light source for supplying two light beams, a shaping means for shaping at least a first light beam of the light beams emitted from the first and second light sources, and a first light source for emitting the first light beam. Deflecting means arranged between the first light source and the shaping means in the optical path of the first light beam; and before the first light beam enters the shaping means, By taking out a part, Detecting the deflection angle of the directing means to correct the optical axis shift and detecting the output light amount of the first light source, and the shaped light beam shaped by the shaping means, the optical recording medium. Irradiation means for irradiating the upper part,
An information signal detecting means for detecting an information signal from a return light beam from the optical recording medium, and writing data by the first beam to a predetermined track of the optical recording medium, and at the same time, The simultaneous verification of reading the information written by the first beam is performed by the separate beam.

[0019]

That is, in the separation type optical pickup device of the present invention, the first light source emits light to the optical recording medium.
When the second light beam emitted from the second light source to the optical recording medium is supplied,
And at least a first light beam of the light beams emitted from the second light source is shaped by the shaping means, and then is irradiated onto the optical recording medium by the irradiation means, and the optical signal is detected by the information signal detecting means. Information signal detection is performed based on the returning light beam from the recording medium.

Between the first light source and the shaping means in the optical path of the first light beam emitted from the first light source,
A polarizing means is arranged, a part of the first light beam is taken out before the first light beam is incident on the shaping means, and the detecting means detects the deflection angle of the deflecting means to correct the optical axis deviation. And the output light amount of the first light source is detected.

At the same time that data is written by a first beam on a predetermined track of the optical recording medium, simultaneous verification is performed to read the information written by the first beam by a second beam.

[0022]

1 is a diagram showing the configuration of a first embodiment of the present invention.

The separation type optical pickup device of this embodiment is
Moving optical system 2 capable of moving in the radial direction of the optical recording medium
And a fixed optical system 1 fixed with respect to the moving optical system 2.

The fixed optical system 1 is provided with a semiconductor laser 3 for supplying a light beam for irradiating the optical recording medium, and the light beam emitted from the semiconductor laser 3 is on the optical path. A collimator lens 4 for converting the light beam into a parallel light beam is arranged. A dichroic mirror 5 that transmits and reflects the parallel luminous flux from the collimator lens 4 is arranged on the optical path of the parallel luminous flux.

On the optical path of the transmitted light from the dichroic mirror 5, a tracking mirror 6 for deflecting the transmitted light is arranged, and on the optical path of the light beam deflected by the tracking mirror 6. , The first shaping prism 7a is arranged. A second shaping prism 7b is arranged on the optical path of the reflected light from the dichroic mirror 5.

The first shaping prism 7a and the second shaping prism 7a
The shaping prism 7b and the polarization beam splitter 8 are integrally formed by the shaping prism 7, and
Further, a dichroic mirror 7C is formed on the joint surface between the second shaping prisms 7a and 7b.

On the optical path of the return light from the moving optical system 2 reflected by the polarization beam splitter 8, a single lens 13 for condensing the light beam is arranged, and the single lens 13 collects the light beam. On the optical path of the emitted light beam,
A plane-parallel plate 14 having a dichroic mirror surface 14a is arranged on the surface thereof. Then, the parallel plane plate 1
On the optical path of the transmitted light from No. 4, the photodetector 15 for light
Is provided.

On the optical path of the reflected light from the plane-parallel plate 14, an analyzer 16 for separating the reflected light into a P-polarized component and an S-polarized component, and a P-polarized component of the analyzer 16 are provided. An optical detector 17 for detecting information that reproduces recorded information from the output difference of the S-polarized component is provided. Also, the first
A photodetector 18 for tracking error detection is provided on the optical path of the reflected light reflected by the incident end surface of the shaping prism 7a.

On the other hand, the moving optical system 2 is provided with a total reflection prism 9 which totally reflects the light beam emitted from the fixed optical system 1, and is arranged on the optical path of the reflected light of the total reflection prism 9. Is an objective lens 1 for collecting the reflected light.
0 is placed. The moving optical system 2 is movable in the radial direction of the magneto-optical disk 11. In such a configuration, λ 1 emitted from the semiconductor laser 3
The two laser beams having different wavelengths from λ2 are collimated by the collimator lens 4.

The laser beam of wavelength λ1 is transmitted through the dichroic mirror 5 arranged on the object side of the collimator lens 4, and the laser beam of wavelength λ2 is reflected by the dichroic mirror 5. In this embodiment, the laser beam having the wavelength λ1 is used as a light beam, and the wavelength λ2 is used.
Laser beam is used as a lead beam.

The light beam having the wavelength λ1 that has passed through the dichroic mirror 5 is refracted at the incident end face of the first shaping prism 7a, the elliptical beam is shaped into a circular beam, and passes through the dichroic mirror face 7c. And proceed.

On the other hand, the read beam of wavelength λ2 reflected by the dichroic mirror 5 is refracted at the incident end face of the second shaping prism 7b to be shaped into a circular beam, reflected by the dichroic mirror 7c, and reflected by the dichroic mirror 7c. Combined with light beam. Then, the combined light beam is reflected by the reflecting prism surface 7d, passes through the polarization beam splitter 8, and then enters the moving optical system 2.

The light beam incident on the moving optical system 2 is
After being totally reflected by the total reflection prism 9, the objective lens 1
It is focused on the information recording surface of the magneto-optical disk 11 which is an information recording medium via 0.

On the information recording surface of the magneto-optical disk 11,
A recording pit is formed by the field coil 12 and a light beam provided above it. When the recording pit is scanned by a light beam spot, the return light has a Kerr rotation component according to the magnetization direction of the recording pit. ..

Then, the return light from the magneto-optical disk 11 becomes a parallel light flux through the objective lens 10, is reflected again by the total reflection prism 9, and is joined to the exit end face of the combined beam of the shaping prism 7 of the fixed optical system 1. It is incident on the polarized beam splitter 8 thus converted. The return light is reflected by the polarization beam splitter 8 and then enters the plane parallel plate 14 having wavelength selectivity through the single lens 13.

A dichroic mirror surface 14a is formed on the incident surface of the plane-parallel plate 14, and the light beam reflected by the dichroic mirror surface 14a is P-polarized component and S-polarized component by the analyzer 16. After being separated into, the light is received by the photodetector 17 for detecting the information signal, and the information signal and the control signal are detected.

On the other hand, the light beam transmitted through the parallel plane plate 14 is received by the two-division photodetector 15, and based on the output of the two-division photodetector 15, the tracking mirror 6
Is controlled.

In this embodiment, the tracking mirror 6 is used.
Detection of the tilt angle of the light beam is performed by reflecting a part of the light beam incident on the first shaping prism 7a on the incident end face thereof,
The reflected light is received by the two-division photodetector 18, which is performed.

Then, the deviation of the optical axis of the light beam is corrected based on the output of the two-divided photodetector 18.
At this time, automatic output control (APC; AUTO) for keeping the amount of light emitted from the semiconductor laser for the light beam constant.
MATIC POWER CONTROL) will also be held.

The tracking control of the light beam is performed by rotating the tracking mirror 6 in the direction of arrow A by an auxiliary actuator (not shown), and the tracking control of the read beam is provided in the moving optical system 2. The movement is performed by moving a two-dimensional actuator (not shown) of the objective lens 10 in the arrow direction B. FIG. 2 is a diagram showing the configuration of the control circuit of the first embodiment.

As shown in the figure, the output signal of the photodetector 17 for detecting the information signal for performing the focus detection by the beam size method and the tracking detection by the push-pull method is the track error signal generation section 30a, the automatic gain control section ( AG
C; AUTOMATIC GAIN CONTROL) 32a, phase compensation unit 34
a, and is supplied to the two-dimensional actuator via the drive circuit 35a, and the relative position between the reproduction light spot and the track is controlled.

On the other hand, the output of the automatic gain control section 32a is supplied to a voice coil motor for driving the entire movable section through a low-pass filter 33a, a phase compensation section 34b and a drive circuit 35b, and the entire movable section is moved as the objective lens moves. It is a two-stage servo that controls the. Thus, the voice coil motor is controlled so that the read beam is located on the track.

The output signal of the photodetector 18 for tracking position detection is supplied to the tracking mirror via the tracking error generator 30b, the automatic gain controller 32b, the phase compensator 34c, the analog switch 38, and the drive circuit 35c. The relative position between the recording spot and the track is controlled.

Since the reflected light from the medium surface of the recording beam changes depending on the track position, the sum light amount is detected and the gain is controlled. Further, when the off-track occurs during recording, the recording is stopped, so that the output of the tracking error generating unit 30c from the photodetector 15 for writing is monitored, and when it is equal to or more than a predetermined value, the tracking mirror is generated. The control circuit of is turned off by the switch 38. Thus, the two-dimensional actuator is controlled so that the read beam is located on the track. The output signal of the photodetector 15 for writing is added to the adder 36 via the tracking error generation unit 30c and the low pass filter 33b.

In this way, the tracking mirror is controlled so that the light beam is positioned on the track when the output of the tracking mirror angle sensor is as close to "0" as possible. By the above-mentioned respective controls, both the read beam and the write beam are positioned on the track.

FIG. 3 is a diagram showing the configuration of the second embodiment of the present invention, FIG. 3 (a) is a diagram showing the configuration of the separation type optical pickup device of the present embodiment, and FIG. It is a figure which shows the cross section of the moving optical system seen from the arrow A shown in a).

The separation type optical pickup device of this embodiment is
Moving optical system 2 capable of moving in the radial direction of the optical recording medium
And a fixed optical system 1 fixed with respect to the moving optical system 2.

The fixed optical system 1 is provided with a semiconductor laser 3a for emitting a writing light beam (780 nm) and a semiconductor laser 3b for emitting a reading light beam (830 nm).

On the optical path of the emitted light of the semiconductor laser 3a, a collimator lens 4a for making the emitted light into a parallel luminous flux is arranged, and the semiconductor laser 3b is provided.
A collimator lens 4b for converting the emitted light into a parallel light flux is arranged on the optical path of the emitted light.

A tracking mirror 6 for deflecting the light beam, which is collimated by the collimator lens 4a, is disposed on the optical path of the light beam, and the light beam of the light beam deflected by the tracking mirror 6 is disposed. A polarization beam splitter 21a is arranged on the road.

On the optical path of the light beam which is collimated by the collimator lens 4b and reflected by the reflection surface of the total reflection prism 23, the polarization beam splitter 21b is provided.
Are arranged.

The polarization beam splitters 21a and 21b
Is provided for emitting the writing and reading light beams to the moving optical system 2. On the optical path of the transmitted light, the stray light transmitted through the polarization beam splitters 21a and 21b is blocked. A light shielding plate 22 is provided in the.

On the optical path of the return light of the writing light beam emitted to the moving optical system 2, there is provided a single lens 13a for condensing the return light.
A photodetector 15 for light is provided on the optical path of the return light condensed by 3a.

On the optical path of the return light of the read light beam emitted to the moving optical system 2, the half-wave plate 20 for rotating the deflection direction of the return light by 45 °.
And a single lens 13b for condensing the light beam whose deflection direction is rotated by 45 ° by the half-wave plate 20.

Further, on the optical path of the light beam condensed by the single lens 13b, an analyzer 16 for separating the light beam into a P-polarized component and an S-polarized component, and an output difference between the respective polarized components, An optical detector 17 for detecting information for detecting recorded information is provided. Each of the photodetectors 17 has a light receiving region divided into three parts, and also serves as a photodetection for focus and tracking control. The total reflection prism 23 and the beam splitters 21a, 21b, 1/2
The wave plate 20 and the single lenses 13a and 13b are integrally formed.

On the other hand, the moving optical system 2 is provided with a shaping prism 19 for shaping the light beam emitted from the fixed optical system 1 toward the magneto-optical disk 11. On the optical path of this reflected light, objective lenses 10a and 10b for condensing the reflected light on the information recording surface of the magneto-optical disk 11 are arranged. Further, a photodetector 18 for tracking position detection is provided on the optical path of a part of the reflected light reflected by the shaping prism 19. The moving optical system 2 is a magneto-optical disk 11
It is movable in the radial direction. In such a structure, a 780 nm semiconductor laser 3a for writing is used.
The light emitted from passes through the collimator lens 4a and becomes a parallel light flux. Then, the parallel light flux is deflected by the tracking mirror 6 rotating in the direction of arrow C about an axis XX ₁ parallel to the paper surface. The light beam deflected by the tracking mirror 6 and reflected by the tracking mirror 6 is separated into reflected light and transmitted light by the first beam splitter 21a.
Since the transmitted light leaks and becomes stray light, it is shielded by the light shielding plate 22 provided between the first and second beam splitters. The reflected light is reflected by the shaping prism 19 of the moving optical system 2 and then focused on the information recording surface of the magneto-optical disk 11 via the objective lens 10a.

A recording pit is formed on the information recording surface of the magneto-optical disk 11 by the field coil 12 provided above it and the modulated light beam. Has a Kerr rotation component according to the magnetization direction of the recording pit.

Then, the return light from the magneto-optical disk 11 is the first beam splitter 21a and the single lens 13 described above.
After being focused through a, it is received by the light detector 15 having a light receiving region divided into two.

The shaping prism 1 of the moving optical system 2 is also provided.
A part of the reflected light reflected by the incident surface of 9 is the photodetector 18
Is received, the angle of the tracking mirror 6 is detected, and the amount of light emitted from the semiconductor laser 1 is monitored.

On the other hand, the light emitted from the 830 nm semiconductor laser 3b for reading is collimated by the collimator lens 4b, reflected by the reflecting surface of the total reflection prism 23, and then reflected by the second beam splitter 21b. And transmitted light is separated.

Since the transmitted light leaks and becomes stray light, it is shielded by the light shielding plate 22, and the reflected light is beam-shaped by the shaping prism 19 of the moving optical system 2, and then the objective lens 1 is used.
It is focused on the information recording surface of the magneto-optical disk 11 via 0b.

The return light from the magneto-optical disk 11 is
The elliptical light that has passed through the objective lens 10b, becomes a parallel light flux, and is shaped by the shaping prism 19 is transmitted through the second beam splitter 21b of the fixed optical system 1 and is transmitted through the half-wave plate 20. After the polarization direction is rotated 45 degrees,
The light is focused by the single lens 13b and enters the analyzer 16.

Then, the P-polarized component and S
After being separated into the polarized light component, the read photodetector 17 detects the output difference between the P polarized light component and the S polarized light component, and the information recorded on the magneto-optical disk 11 is read. The two embodiments of the present invention have been described above.
The present invention is not limited to this.

For example, a tracking mirror is arranged between two shaping prisms shown in FIG. 1 of Japanese Patent Application No. 03-193735, and the tracking is performed by the reflected light from the incident surface of the shaping prism on the movable optical system side. The position of the mirror can be detected, and the light amount of the semiconductor laser can also be detected.

As described in detail above, according to the separation type optical pickup device of the present invention, first, by arranging the tracking mirror on the recording beam side, the optical axis shift and the output power of the semiconductor laser are kept constant. Since only one photodetector that also serves as the control can be used, the number of parts can be reduced.

Secondly, since the tracking position is detected by using the reflected light on the entrance surface of the shaping prism, it is possible to prevent the angle change of the light beam from being reduced by the enlargement ratio of the shaping prism. Then, at this time, the optical axis can be corrected by the inclination of the galvanometer mirror.

[0067]

According to the present invention, at the time of writing / reading data by the simultaneous verification, it is possible to reduce the angle change by the enlargement ratio of the shaping prism by the tracking position detection utilizing the reflected light of the shaping prism incident surface. It is possible to provide a separation-type optical pickup device that can be prevented.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a first exemplary embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a control circuit of the first embodiment.

FIG. 3 is a diagram showing a configuration of a second exemplary embodiment of the present invention.

[Explanation of symbols]

1 ... Fixed optical system, 2 ... Moving optical system, 3 ... Semiconductor laser,
4 ... Collimator lens, 5 ... Dichroic mirror, 6 ...
Tracking mirror, 7 ... Shaping prism, 8 ... Polarization beam splitter, 9 ... Total reflection prism, 10 ... Objective lens, 11 ... Magneto-optical disk, 12 ... Field coil, 13 ...
Single lens, 14 ... Parallel plane plate, 15 ... Photodetector, 16 ...
Analyzer, 17 ... Photodetector, 18 ... Photodetector, 19 ... Shaping prism, 20 ... Quarter wave plate, 21 ... Beam splitter, 22 ... Shading plate, 23 ... Total reflection prism.

Claims (1)

[Claims] 1. A separation type optical pickup device comprising a movable optical system which is movable in a predetermined direction with respect to an optical recording medium, and a fixed optical system which is fixed to the movable optical system. From a first light source for supplying a first light beam emitted to a recording medium, a second light source for supplying a second light beam emitted to the optical recording medium, and from the first and second light sources A shaping means for shaping at least the first light beam of the emitted light beam, and between the first light source and the shaping means in the optical path of the first light beam emitted from the first light source. And a deflecting means arranged at the same time, and by extracting a part of the first light beam before the first light beam enters the shaping means, the deflection angle of the deflecting means is detected to shift the optical axis. Of the first light source Detection means for detecting the amount of power light, irradiation means for irradiating the optical recording medium with the shaped light beam shaped by the shaping means, and information signal detection from the return light beam from the optical recording medium And an information signal detecting means for simultaneously writing data on a predetermined track of the optical recording medium by the first beam and simultaneously reading information written by the first beam by the second beam. A separation type optical pickup device characterized by performing verification.