JPS60101734A - Optical head - Google Patents

Abstract

PURPOSE:To carry out the function of reproduction, etc., accurately by detecting the irradiation position of a light beam which records and reproduces information optically by a detecting means and correcting the irradiation position of each light beam into a specific position according to the detection output. CONSTITUTION:When recording laser light W shifts in position from a Y axis toward a detector (a), comparison part 17 outputs the output signal of the detector (a). A driving circuit 19 drives a recording beam deflecting plate 10 so that its deflection angle varies according to the output signal of the detector (a). Recording laser light W and reproduced laser light W are deflected and position correction is so made that the laser light is returned to the Y axis. When the recording laser light W and reproduced laser light M shift in position from the Y axis in either direction of an X axis, a position correcting means M operates similarly and position correction is so made that the laser light beams are returned to the Y axis. This correcting means position the focus of the reproduced laser light M right behind the focus of the recording laser light W on the same circumferential track of a recording medium 1 inevitably to improve the reliability of recording, reproduction, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to an optical head for an optical disc device, and in particular to an optical head for an optical disk device, and in particular to an optical head for an optical disk device, and in particular for irradiating a recording medium with a plurality of light beams to transmit and receive information. The present invention relates to an optical head that corrects positional deviation and always illuminates a predetermined position.

(bl Prior Art and Problems) The optical heads of recent optical disk devices include a recording beam for recording information on a recording medium, and whether the recorded information is accurately recorded in order to confirm the reliability of recording. Recording and playback are performed simultaneously using a playback beam that performs a check immediately after recording.

That is, in the configuration diagram of the conventional optical head shown in FIG. 1, the recording laser beam W modulated by recording information generated by the recording laser generator 14 passes through the collimating lens 12 and is normalized by the recording beam deflection plate 1o. is deflected in the optical path direction of the polarizing beam splinter 4 on the optical path and "λ/
It reaches the objective lens 2 through the four plates 3. The objective lens 2 records the incident light, focuses the light W, and sets the focal point on the recording medium l.
information is recorded at a predetermined track position. on the other hand,
The reproduction laser beam M generated by the reproduction laser generator 13 passes through the collimating lens 11 and passes through the reproduction beam deflection plate 9.
The beam is deflected in the normal optical path direction, and reaches the objective lens 2 via the gicroic mirror 8, the polarizing beam fritter 4 and the λ/4 plate 3 on the optical path. Here, the objective lens 2 focuses the input reproduction laser beam M, sets its focus to a predetermined track position on the recording medium 1, and irradiates it. This irradiated light is modulated by the information recorded on the track, becomes reflected light 2, is deflected by 90 degrees through a λ/4 plate 3 and a deflection beam splinter 4, passes through a filter 5, and enters a condenser lens 6. The light is focused on the photodetector 7.
leading to. The reflected light 2 is converted into an electrical signal by the photodetector 7, and the information recorded on the recording medium is reproduced.

The purpose of this repeat processing is to confirm the reliability of the information recorded on the recording medium immediately after recording. Therefore, the Ff IJ beam M is placed immediately after the focus of the recording beam W on the same circumferential trunk. The focus needs to be located. Because of that,
Conventionally, when assembling the optical head, the beam position was visually confirmed through a magnifying glass, and the deflection angles of the recording beam deflection plate 1o and the reproduction beam deflection plate 9 were finely adjusted, and the positions of these eight beams were adjusted as above. The position is being adjusted so that the position is as follows. However, when positioning is performed only during assembly, the position of each beam may deviate from a predetermined position due to temperature changes, vibrations, shocks, etc. after assembly and adjustment, and the recording and reproducing functions deteriorate. There is a drawback that position correction for this cannot be performed after assembly is completed.

(C1 Object of the Invention The object of the present invention is to provide an optical head that corrects the positional deviation between the irradiation positions of a recording beam and a reproducing beam so that the irradiation positions are always at a predetermined position, thereby improving recording and reproducing functions.

(d+) According to the present invention, the structure and object of the invention is an optical head of an optical disk device that transmits and receives information to and from an optical recording medium by irradiating a plurality of light beams in the moving direction of the medium, This is achieved by an optical head characterized in that it is provided with a detection means for detecting the irradiation position of the light beam, and a means for correcting the output position of the detection means to a predetermined position.

te+ Example of invention Hereinafter, one embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 2 is a block diagram of the optical head of the present invention, and the same parts and symbols as those in FIG. 1 indicate the same parts. That is, in the optical head of the present invention, as shown in FIG. 2, the conventional optical head is equipped with a condensing lens that condenses the recording laser beam W polarized by °ζ and the reproduction laser beam M onto the polarization beam splinter 4. 15, and four detection units a, b, c, and d that detect the light intensity of the recording laser beam W and reproduction laser beam M focused by the condenser lens 15 and output focal position signals of each laser beam. a beam position detection section 1G composed of a detector (see FIG. 3); a comparison section 17 that compares the focal position signals of the recording laser beam W detected and output by the detectors a and b; Recording beam deflection plate 10 according to the output signal
A drive circuit 19 drives the deflection plate 10 so as to change the deflection angle of the detectors a and b to equalize the focal position signal outputs of the detectors a and b; A comparator 18 that compares focus position signals and a deflection angle of the reproducing beam deflection plate 9 are changed by the output signal of the comparator 18, and the deflection plate 9 is driven so as to equalize the focus position signal outputs of the detectors C and d. A drive circuit 20 is provided.

The operation is such that the recording laser beam W generated by the recording laser generator 14 is deflected in the normal optical path direction by the recording beam deflection plate 1o, and is passed through the polarizing beam splinter 4 and the λ/4 plate 3 on the optical path to the objective lens. 2 and is focused by an objective lens 2 to record information on a predetermined trunk of the recording medium 1. On the other hand, when the recording laser beam W passes through the polarization beam splinter 4, a part of it is deflected by the polarization beam splinter 4 and becomes the recording position detection optical path W1 through the condenser lens 15.
leading to. Further, the reproduction laser beam M generated by the reproduction laser generator 13 is deflected in the normal optical path direction by the reproduction beam deflection plate 9, and is transmitted to the polarization beam splinter 4 and λ on the optical path via the optical mirror 8. /4 plate 3 and reaches the objective lens 2. Here, the objective lens 2 focuses the incident reproduction laser beam M, and sets its focus immediately after the focal position of the recording beam W on the same circumferential track, and irradiates it. In this case, like the recording laser beam W, when the reproducing laser beam M passes through the polarizing beam splinter 4, a part of it is deflected by the polarizing beam splinter 4 and becomes the reproducing position detection optical path M1, reaching the condenser lens 15. The recording laser beam W and the reproduction laser beam M focused by the condensing lens 15 are directed along the X-axis and the Y-axis, as shown in the block diagram for explaining the beam position correction of the present invention in FIG. The beam is input to a beam position detection section 16 which is composed of detectors a and b and C and d arranged in a matrix. In other words, when assembling and opening the optical head, the recording laser beam W is focused on different positions on the same circumferential trunk of the recording medium.
The beam position detecting section 16 is installed so that when the reproduced laser beam M is input to the beam position detecting section 16, these laser beams are positioned on the Y axis.

Therefore, the light amounts of the recording laser beam W and the reproduction laser beam M are detected by detectors a and b and C and d that are in contact with each other on the Y axis. These detected light amounts are divided into two by the Y axis, and the detector a
The detected light quantities of and b and C and d are equal, and therefore the detection output signals are also equal. Next, the output signals of the detectors a and b and the detectors C and d are input to comparators 17 and 18 and compared.

Since the respective detection output signals input to the comparators 17 and 18 are equal, their outputs are zero. This results in
The drive circuits 19 and 20 do not operate, and the recording beam deflection plate 10 and the reproduction beam deflection plate 9, which deflect the recording laser beam W and the reproduction laser beam M driven by these drive circuits, are maintained in their current state.

Now, if a positional deviation occurs in the direction of the detector a from the recording laser beam W, /+<Y axis, the output signal of the comparator 17 is the output signal of the detector a, as explained in the above operation Ru. Therefore, the drive circuit 19 drives the recording beam deflection plate 10 to change the deflection angle in response to the output signal of the detector a, and performs position correction to deflect the recording laser beam W and return it to the Y axis.

In this way, the recording laser beam W and the reproduction laser beam M
Even if a positional deviation occurs in any direction of the X-axis from the Y-axis, the position correction means of the present invention operates as described above to correct the position so as to return it to the Y-axis.

Due to this position correction means, the focal point of the reproducing laser beam M is inevitably located immediately after the focal point of the recording laser beam W on the same circumferential track of the recording medium I.

In the above embodiments, the position correction means of the optical head that performs recording and reproduction processing has been described, but the above-mentioned recording also applies to the positional deviation of the focus of the erasing laser beam of the optical head that has been added with erasing processing to erase recorded information. Similarly to the recircling position correcting means, by providing an erasing position correcting means, the position can be automatically corrected.

(fl Effects of the Invention As is clear from the above explanation, the present invention uses a detection means to detect the irradiation position of a light beam for optically recording and reproducing information on a predetermined position of a recording medium, and detects the irradiation position from the detection output. By correcting the irradiation position of each light beam to a predetermined position by the position correcting means, functions such as recording and reproduction can be performed accurately during lightning, and the reliability of recording, recording, etc. is greatly improved.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a conventional optical head, Fig. 2 is a block diagram of an optical head of the present invention, and Fig. 3 is a block diagram of the beam position of the present invention. d
FIG. 2 is a block diagram for explaining i-positive. In the figure, 1 is the recording medium, 2 is the objective lens, and 3 is λ/
4 plates, 4 is a polarizing beam splitter, 5 is a filter, 6,
15 is a condensing lens, 7 is a photodetector, 8 is a gicroic mirror, 9 is a beam polarizing plate for reproduction, 10 is a beam polarizing plate for recording, 11.12 is a collimating lens, 13 is a laser generator for reproduction, 14 is a recording laser generator, 16 is a beam position detection section, 17.18 is a comparison section, and 19.20 is a drive circuit. Figure 1 2nd Flash

Claims (1)

[Claims] an optical head of an optical disk device that transmits and receives information about the media by irradiating a plurality of light beams in a moving direction of an optical recording medium, and a detection means for detecting the irradiation position of the light beam from the optical head; An optical head characterized in that it further comprises means for correcting the output positions of the detection means to respective predetermined positions.