JPH01144245A - Optical head - Google Patents

Abstract

PURPOSE:To accelerate recording and to improve reliability by reproducing information by a reproducing light beam from plural other semiconductor lasers (LD) with different wavelength immediately after recording the information extending over plural tracks by the light beam from plural LDs, and checking whether or not the information is recorded correctly. CONSTITUTION:Plural light beams emitted from the plural LDs (10a-10c) in each of two pairs of LD arrays 10 and 12 with different wavelength pass collimator lenses 11 and 13, and are focused by a focusing means 14, and plural beam spots 2 and 3 are formed on an optical disk 18 via a convergence lens 17. At this time, the recording of the information is performed by a preceding beam by forming every two of beam spots 2 and 3 on adjacent tracks 1a-1c, and reproduction is performed by the next beam. In such a way, it is possible to check whether or not the information is recorded correctly immediately after recording, and to realize fast recording with high reliability.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an optical head, and particularly to an optical information recording/reproducing device that records or reproduces information by converging a light beam onto a disc-shaped recording medium. Regarding the optical head used.

[Conventional technology]

In an optical information recording/reproducing device (optical disk device) that records or reproduces information by converging a light beam onto a disk-shaped recording medium (optical disk), an optical head for recording or reproducing information is Usually one semiconductor laser (hereinafter referred to as
(hereinafter referred to as LD) is used as a light source, but in cases where the purpose is to record and reproduce information at high speed, multiple LDs are used to simultaneously record and reproduce information on multiple tracks in parallel. Some use methods. At this time, as a light source, a semiconductor laser array (hereinafter referred to as L
It is desirable to use a D array (referred to as a D array) because it has a small number of parts and is easy to adjust.

FIG. 3 is a side view of an example of a conventional optical head.

The optical head shown in FIG. 3 uses an LD array as a light source and irradiates a plurality of beams onto a plurality of adjacent tracks of an optical disk (see, for example, Japanese Patent Laid-Open No. 115033/1983).

In FIG. 3, the LD 30a of the LD array 30 of the light source,
Light beams 100a, 1 emitted from 30b and 30c
0'Ob and 100C are converted into light beams with a predetermined diameter by the collimating lens 31 and sent to the polarizing beam splitter 32.
is incident on the

When these light beams 100a, 100b, and 100c are respectively irradiated onto three adjacent tracks on the optical disk 36 for recording or reproduction in parallel, each light beam writes information to its corresponding track. Recording and reproducing operations are performed, but at this time, -
The main light beam 100c is used for servo and also for recording and reproducing information, or is used exclusively for servo, and the other two beams 100a and 100b are used exclusively for recording or reproducing.

Light beam 100a from LDs 30a, 30b and 30c
, 100b and 100c are P-polarized lights, so they travel straight without being polarized in the polarizing beam splitter 32, and are 1/1
The light passes through a four-wavelength plate 33 and is converted into circularly polarized light. Further, the light passes through a converging lens 35 attached to an actuator 34 and is focused onto an optical disk 36 .

The light beam reflected from the optical disk 36 travels along essentially the same optical path in the opposite direction and passes through the quarter-wave plate 33, where it is converted from circularly polarized light into the LD 30a.

The polarized light (SN light) becomes perpendicular to the polarization direction of the emitted light from 30b and 30c, and changes its course by 90 degrees at the polarizing beam splitter 32.

The light beams 101a, 1 which changed their course and passed through the lens 37
01b and 101c are focused at a point at approximately the same distance from the lens 37. Light beam 10 for servo
1C is separated from other light beams by a light separation element 41, such as a pinhole or a knife, arranged at a convergence position, and is incident on the detector 40. On the other hand, the other light beams 101a and 101b are incident on the optical sensors 38 and 39 arranged at convergence positions on the light separation element 41, and the three light beams 101a, 101b and 101C are detected independently. be done.

[Problem that the invention seeks to solve]

The conventional optical head described above irradiates each of a plurality of light beams onto separate adjacent tracks on an optical disk and performs recording or reproduction simultaneously with the plurality of light beams. In this case, in order to increase the reliability of recorded information, it is necessary to check whether the information has been recorded correctly immediately after writing it.

In the optical head as described above, after information is recorded on a plurality of tracks, the same track is read out again to check whether the information has been recorded accurately. That is, when recording one piece of information, it is necessary to rotate the optical disc at least twice, which poses a problem in that it takes a long time to record the information.

An object of the present invention is to provide an optical head that can perform high-speed recording by reading information using the same optical head immediately after recording information.

[Means for solving problems]

The optical head of the present invention includes a first array light source that integrates a plurality of first semiconductor lasers that oscillate at a first wavelength, and a first array light source that oscillates at a second wavelength different from the first wavelength. a second array light source that integrates the same number of second semiconductor lasers as the semiconductor lasers; An optical system that condenses and irradiates light emitted from a semiconductor laser onto a plurality of adjacent tracks of an optical recording medium, and condenses and irradiates light emitted from the second semiconductor laser onto each of the same tracks. and a photodetector that separates the reflected light from the optical recording medium into light from the first semiconductor laser and light from the second semiconductor laser, and detects the reflected light for each semiconductor laser. It consists of:

[Effect]

In the optical head of the present invention, a plurality of light beams emitted from a plurality of LDs of two sets of LD arrays having different wavelengths pass through a collimating lens, and are focused by a focusing means such as a dichroic mirror or a diffraction grating. When multiple beam spots are formed on the optical disk through a convergent lens, information is recorded with the preceding beam by forming two beam spots on each adjacent track, and then the next beam is recorded. By performing reproduction with a beam of 1, it becomes possible to check whether information has been correctly recorded immediately after recording, and it becomes possible to record information at high speed and with high reliability.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a side view of one embodiment of the present invention.

In FIG. 1, three LDl with wavelength λ1 of 830 nm
Three light beams emitted from a recording LD array 10 as a first array light source consisting of oa, 10b, and 10c are collimated by a collimating lens 11, reflected by a dichroic mirror 14, and sent to polarizing beam splitters 15 and 1. /4 wavelength plate 16 and converging lens 17
Each light beam is focused on the optical disk 18 by the following.

Also, three LDs 12a whose wavelength λ2 is 780 nm.

Three light beams emitted from the reproduction LD array 12 as a second arrayed light source consisting of 12b and 12C are collimated by the collimating lens 13, transmitted through the dichroic mirror 14, and further transmitted to the polarizing beam splitter 1.
Each light beam passes through the 5 and 1/4 wavelength plates 16 and is converged onto the optical disk 18 by the converging lens 17 .

FIG. 2 is a plan view of a main part of an optical disc showing a beam spot irradiated onto a track using the embodiment shown in FIG.

As shown in FIG. 2, the light beam spot irradiated onto the optical disk 18 rotating in the direction of arrow A is the recording beam spot 2 and the reproduction beam spot 3, both of which are located on three adjacent tracks la.

One each is placed on Ib and lc, and the recording beam spot 2 and reproduction beam spot 3 are set so as to be placed on the same track.

Again, in FIG. 1, the reflected light from the optical disk 18 passes through the converging lens 17 and 1/4 wavelength plate 16, is reflected by the polarizing beam splitter 15, and its traveling direction is changed to 9.
It is bent by 0°, focused by a lens 19, separated into a recording light beam and a reproduction beam by a dichroic mirror 20, and then sent to a recording photodetector 21 and a reproduction photodetector 2.
Each of the three optical sensors on 2 is illuminated. Note that the reflected light from the recording beam spot and the reproduction beam spot from the optical disc 18 are separated by a dichroic mirror 20 due to their different wavelengths, and the reflected light from the recording beam spot enters the recording photodetector 21. However, the reflected light from the reproduction beam spot is focused on the reproduction photodetector 22.

One or more optical sensors of the recording photodetector 21 generate focus and tracking error signals for the recording beam spot. Further, one or more optical sensors of the reproducing photodetector 22 generate focus and tracking error signals for the reproducing beam spot, and all optical sensors generate readout signals for recorded information. let

Note that the dichroic mirrors 14 and 20 have the characteristic of almost total reflection at the wavelength ^1 of the recording light beam and almost no reflection at the wavelength λ2 of the reproduction light beam.

As shown in FIG. 2 above, adjacent racks 1 to 1a
, lb, lc with the recording beam spot 2, and furthermore, the same tracks la, lb.

By irradiating the reproduction beam spot 3 onto the LC, it becomes possible to reproduce information recorded with the recording light beam in parallel on each track immediately after recording with the reproduction light beam.
It becomes possible to record information at high speed and with high reliability.

In addition, in the description of the embodiment, the number of LDs in the LD array is 3.
However, the present invention can be applied if there are two or more.

〔Effect of the invention〕

As explained above, the optical head of the present invention has a plurality of 1, D
Immediately after recording information in parallel across multiple tracks using a recording light beam emitted from the LD, the information is reproduced using a reproducing light beam emitted from other LDs with different wavelengths to ensure that the information is correctly recorded. By checking whether or not the recording is completed, it is possible to achieve faster recording and improved reliability.

[Brief explanation of the drawing]

FIG. 1 is a side view of an embodiment of the present invention, FIG. 2 is a plan view of a main part of an optical disc showing a beam spot irradiated onto a track using the embodiment of FIG. 1, and FIG. FIG. 3 is a side view of an example of an optical head. la, lb, lc...track, 2...beam spot for recording, 3...beam spot for playback, 10...
・LD array for recording, 10a, 10b, 10cm
・-LD, 11.13...Collimating lens, 12・
...LD array for playback, 12a, 12b, 12c...
・LD, 14.20... Guicroic mirror, 15
...Polarizing beam splitter, 16...1/4 wavelength plate, 17...Converging lens, 18...Optical disk, 19
... Lens, 21... Recording photodetector, 22...
Reproduction photodetector, 30-LD array, 30a, 30b
. 30c...LD, 31...Collimating lens, 32
...Polarizing beam splitter, 33...1/4 wavelength plate, 34...Actuator, 35...Converging lens,
36... Optical disc, 37... Lens, 38.39
... Optical sensor, 40 ... Detector, 41 ... Light separation element, 100a, 100b, 100c, 101a, 10
1b. 101c...Light beam.

Claims (1)

[Claims] a first array light source that integrates a plurality of first semiconductor lasers that oscillate at a first wavelength; a second array light source integrating two semiconductor lasers;
The emitted light from the first and second array light sources is focused for each semiconductor laser, and the emitted light from the first semiconductor laser is focused and irradiated onto a plurality of adjacent tracks of the optical recording medium, respectively. an optical system that condenses and irradiates the emitted light from the second semiconductor laser onto the same track as each of the tracks; and an optical system that converts the reflected light from the optical recording medium into the light from the first semiconductor laser, respectively. An optical head comprising: a photodetector that separates the light from the second semiconductor laser and detects the reflected light for each semiconductor laser.