JPH05151611A - Optical pickup device - Google Patents

Abstract

PURPOSE:To always enable stable recording and reproducing in/from the optical disks of a various kinds of an organic dystuff system having a wavelength dependency. CONSTITUTION:Plural semiconductor laser elements 3a, 3b and 3c outgoing laser beams having different wavelengths each other are provided on a laser beam source 2. Then, by selecting and driving one of plural semiconductor laser elements 3a, 3b and 3c in accordance with the kind of the optical disk 25 desired to record or reproduce, the outgoing luminous flux of a wavelength obtaining a track signal with sufficient intensity for a track servo of the outgoing luminous flux L1a, L1b and L1c is selected and used. Thus, the operation of the track servo is stabilized to the optical disks of a various kinds of the organic dystuff system having the wavelength dependency and recording and reproducing is always performed in a stable condition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup device for recording / reproducing information on / from an optical disk, which is an organic dye-based information recording medium, by using laser light.

[0002]

2. Description of the Related Art FIG. 2 is a diagram showing a conventional example of this type of optical pickup device, (A) is a schematic configuration diagram of a conventional optical pickup device, and (B) is a schematic of a laser light source of the optical pickup device. It is a block diagram.

As shown in FIG. 2A, the optical pickup device 11 includes a laser light source 12, a photodetector 13, a collimator lens 14, a beam splitter 15, a quarter-wave plate 16, an objective lens 17, It is configured by combining a condenser lens 18 and a cylindrical lens 19.

In the laser light source 12, as shown in FIG. 2B, one semiconductor laser element 20 which emits laser light of a constant wavelength is mounted on a heat sink 22 together with an optical output monitoring diode 21, and It is housed in a package 24 with a transparent window 23.

In the optical pickup device 11, the objective lens 17 is arranged so as to face one surface of an optical disk 25 which is an organic dye-based information recording medium, and the optical disk 25 is driven by a driving device (not shown). Move in the radial direction (arrow A).

The optical disc 25 is provided with a recording layer 26 containing an organic dye for increasing the heat absorption coefficient, and a large number of information tracks 27 and the information tracks 2 thereof.
7 guide grooves 28 are formed. This optical disc 2
5 is rotated in a predetermined direction by a drive shaft (not shown).

In the optical pickup device 11 having the above structure, the light beam L11 emitted from the semiconductor laser element 20 of the laser light source 12 in a linearly polarized state becomes a parallel light beam by the collimator lens 14 and passes through the beam splitter 15, It is circularly polarized by the quarter-wave plate 16 and is converged on the information track 27 of the optical disc 25 by the objective lens 17. At this time, when the output of the semiconductor laser device 20 is set to a high output of a certain value or higher,
The recording layer 26 of the optical disc 25 is heated and deformed. Therefore, by controlling the output of the semiconductor laser device 20 based on the input signal and switching between high output that deforms the recording layer 26 of the optical disc 25 and low output that does not deform,
Information can be recorded by forming irregularities on the recording layer 26 along the information tracks 27.

On the other hand, a part of the outgoing light flux L11 converged on the optical disc 25 is reflected by the optical disc 25. The reflected light flux L12 from the optical disk 21 is incident on the objective lens 17 again and travels backward to produce the quarter-wave plate 16
Then, it returns from circularly polarized light to linearly polarized light. Since the polarization plane of the linearly polarized reflected light flux L12 is rotated by 90 degrees from the polarization plane of the outgoing light flux L11, the reflected light flux L12 is totally reflected in the orthogonal direction by the beam splitter 15. The totally reflected reflected light flux L12 is converged through the condenser lens 18 and is further subjected to astigmatism for obtaining a focus signal by the cylindrical lens 19 to enter the photodetector 13.

Therefore, the output of the semiconductor laser device 20 is
The recording layer 26 of the optical disc 25 is set to a low output so as not to be deformed, and the reflected light flux L12 corresponding to the unevenness of the recording layer 26
By detecting the change in the light amount of the photodetector 13, the record information of the optical disc 25 recorded on the recording layer 26 along the information track 27 can be reproduced in the form of the output signal of the photodetector 13.

As described above, when information is recorded on or reproduced from the optical disc 25, the convergence position of the light beam L11 emitted from the laser light source 12 is always exactly aligned with the designated information track 27 of the rotating optical disc 25. The optical pickup device 11 must be moved so as to do so. That is, it is necessary to perform track servo. Therefore, the drive device of the optical pickup device 11 is provided with a track servo mechanism. The track servo mechanism operates on the basis of a track signal, and the track signal is a light flux L11 emitted by the guide groove 28 of the optical disc 25.
It is obtained from the diffracted light of.

[0011]

Since the organic dye-based optical disc has wavelength dependence, as shown in the characteristic diagrams of FIGS. 3 (A) and 3 (B), the laser beam necessary for recording information on the optical disc is used. Of the recording power and the intensity of the track signal for the track servo obtained from the optical disk vary depending on the wavelength (λ1, 2, 3) of the laser light used, and the degree of the wavelength dependence is Types of optical discs with different dyes (Discs 1, 2, 3)
Depends on

Therefore, the above conventional optical pickup device 1
When only the emitted light beam L11 of one wavelength is used as in No. 1, the intensity of the track signal is insufficient and the track servo operation becomes unstable depending on the type of the optical disc (Disc 1, 2, 3). As a result, the recording and reproducing operations may become unstable.

The present invention has been made in order to solve this problem, and is an optical disk which can always record and reproduce in a stable state on various kinds of optical disk of organic dye type having wavelength dependence. The purpose is to obtain a pickup device.

[0014]

In order to achieve the above object, in an optical pickup device according to the present invention, a laser light source is provided with a plurality of semiconductor laser elements for emitting laser beams having different wavelengths.

[0015]

According to the optical pickup device having the above structure, one of a plurality of semiconductor laser elements is selected and driven according to the type of the optical disc to be recorded or reproduced, so that the emitted light fluxes having different wavelengths are selected. Of these, it becomes possible to select and use the emitted light flux of the wavelength that can obtain the track signal of sufficient strength for the track servo. Therefore, the operation of the track servo is stabilized for various types of organic dye-based optical discs having wavelength dependence,
Recording and reproduction can be performed in a stable state at all times.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing an embodiment of the present invention.
Is a schematic configuration diagram of an optical pickup device according to the present invention, and (B) is a schematic configuration diagram of a laser light source of the optical pickup device. It should be noted that constituent elements in FIG. 1 which are not different from those of the conventional example shown in FIG.

As shown in FIGS. 1 (A) and 1 (B), the optical pickup device 1 according to the present invention is characterized in that a laser light source 2 is provided, and the laser light source 2 receives laser lights having different wavelengths. A plurality of semiconductor laser devices 3a, 3b, 3c for emitting light, here three semiconductor laser devices, are provided. The other configuration of the optical pickup device 1 is the same as that of the conventional example.

As shown in FIG. 1B, the laser light source 2 includes three semiconductor laser elements 3a, 3b and 3c, and light output monitor diodes 4a, 4b, and 4b corresponding to the respective elements 3a, 3b and 3c. It is mounted on a heat sink 5 together with 4c, and is further housed in a package 7 having a transparent window 6. That is, in this embodiment, the three semiconductor laser devices 3a, 3b, 3c are integrated in one package 7. As a result, the laser light source 2 including the three semiconductor laser elements 3a, 3b, 3c can be downsized and the manufacturing cost thereof can be kept low.

Each of the semiconductor laser elements 3a, 3b, 3c
The wavelengths of the emitted light beams L1a, L1b, and L1c are always stable by using any one of the emitted light beams as described below in consideration of the type of the organic dye-based optical disk 25 that may be used, that is, the wavelength dependence. It is appropriately selected so that recording and reproduction can be performed in this state. Further, the light quantities of the respective emitted light fluxes L1a, L1b, L1c are monitored by the corresponding light output monitoring diodes 4a, 4b, 4c, and controlled based on the monitoring result.

The laser light source 2 emits a luminous flux L1.
Whichever of a, L1b and L1c is used, the three semiconductor laser elements 3a, 3b and 3c are arranged in the radial direction (arrow A) of the optical disc 25 so that the emitted light flux converges on the same information track 27 of the optical disc 25. It is set to be aligned in the direction perpendicular to the track.

In the optical pickup device 1 having the above structure, one of the three semiconductor laser elements 3a, 3b, 3c is selected and driven according to the type of the optical disk 25 to be recorded or reproduced. Of the emitted light beams L1a, L1b, and L1c having different wavelengths, it is possible to select and use the emitted light beam having a wavelength at which a track signal having a strength sufficient for track servo is obtained. Therefore, it is possible to stabilize the operation of the track servo with respect to various types of organic dye-based optical discs having wavelength dependence, and perform recording and reproduction in a stable state at all times.

The outgoing luminous flux L1a selected as described above
Alternatively, the method of recording and reproducing using L1b or L1c is the same as in the conventional example. That is, the selected outgoing light flux L1a, L1b, or L1c is passed through the collimator lens 14, the beam splitter 15, the quarter-wave plate 16 and the objective lens 17 to the optical disc 25.
Information is recorded on the recording layer 26 by converging it on the information track 27 of FIG. In addition, the selected outgoing light flux L1a or L
The reflected light beam L2a, L2b, or L2c of 1b or L1c from the optical disk 25 is made to go backward, and is totally reflected in the right angle direction by the beam splitter 15, and the photodetector 1 is passed through the condenser lens 18 and the cylindrical lens 19.
By making the light incident on the optical disc 3 and detecting the change in the light amount, the recorded information of the optical disc 25 recorded on the recording layer 26 along the information track 27 is reproduced in the form of the output signal of the photodetector 13. During this reproduction, the output of the driven semiconductor laser element 3a, 3b or 3c is set to a low output that does not deform the recording layer 26 of the optical disc 25.

[0024]

As described above, according to the optical pickup device of the present invention, it is possible to always record and reproduce in a stable state on various kinds of optical disk of organic dye type having wavelength dependence. it can.

Further, by incorporating a plurality of semiconductor laser elements in a single package in an integrated state, it is possible to reduce the size of the laser light source provided with these semiconductor laser elements and to keep the manufacturing cost low. ..

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention, (A) is a schematic configuration diagram of an optical pickup device according to the present invention, and (B) is a schematic configuration diagram of a laser light source of the optical pickup device.

FIG. 2 is a diagram showing a conventional example, (A) is a schematic configuration diagram of a conventional optical pickup device, and (B) is a schematic configuration diagram of a laser light source of the optical pickup device.

3A and 3B are characteristic diagrams showing wavelength dependence of an organic dye-based optical disk.

[Explanation of symbols]

 1 Optical Pickup Device 2 Laser Light Sources 3a, 3b, 3c Semiconductor Laser Element 7 Package 13 Photodetector 25 Optical Disc

Claims (2)

[Claims] 1. A laser light source and a photodetector are provided, and a light flux emitted from the laser light source is converged on an optical disk which is an organic dye-based information recording medium to record information and is converged on the optical disk. In the optical pickup device for reproducing the recorded information of the optical disc by detecting the reflected light flux of the emitted light flux from the optical disc by the photodetector, a plurality of laser light sources having different wavelengths are emitted to the laser light source. An optical pickup device comprising a semiconductor laser element. 2. A laser light source and a photodetector are provided, and the luminous flux emitted from the laser light source is converged on an optical disk which is an organic dye-based information recording medium to record information and is converged on the optical disk. In the optical pickup device for reproducing the recorded information of the optical disc by detecting the reflected light flux of the emitted light flux from the optical disc by the photodetector, the laser light source emits a plurality of laser light beams having different wavelengths. An optical pickup device comprising a semiconductor laser element integrated in a package.