JPS62202336A - Information recording and reproducing device - Google Patents

Abstract

PURPOSE:To save an optical component to synthesize/separate a light by correcting a detection signal from a photodetector so as not to cause the effect by the 2nd light and providing a correction circuit at least applying one of track shift correction and out of focus correction. CONSTITUTION:Since the ratio of luminous quantity of an erasure laser light Lb to a recording/reproducing laser light La at the erasure is constant anywhere regardless of a location irradiated on an information storage medium, the ratio of light quantity of the erasure laser light Lb to the recording/reproducing laser light La is kept always constant in out of focus detecting photodetection cells 66a, 66b. Thus, it is not required to arrange a dichroic mirror and a light shield plate for the purpose of inhibiting the laser light Lb other than the laser light La used for the detection of out of focus from being irradiated to a photodetector 14. Thus, even when the constitution is adopted that the two laser lights La, Lb are focused onto the information recording medium, the entirely same optical structure as the structure focusing one laser light is adopted, and the structure is simplified.

Description

[Detailed Description of the Invention] [Object of the Invention] [Industrial Field of Application] The present invention relates to a memory device such as an additionally recordable compact disc or a video disc, or an erasable computer output memory, or a laser card. The present invention relates to an information recording and reproducing apparatus that is applied to at least recording and reproducing information on an information storage medium using focused light.

[Conventional technology]

Conventionally, this type of information recording/reproducing apparatus includes an optical head that simultaneously irradiates two or more focused spots onto an information storage medium.

That is, a recording laser beam and a reproducing laser beam are aligned and focused along a track on an information storage medium, and the recorded content recorded by the preceding recording laser beam is read by the following reproducing laser beam, An optical head with a function to check the recording status (error rate, etc.)
An elliptical erasing laser beam and a substantially circular recording/reproducing laser beam are focused side by side along a track on an information storage medium, and pre-recorded information is erased by the preceding erasing laser beam. An optical head that has the function of re-recording with a recording/playback laser beam while recording, or reproducing prerecorded information by focusing the recording/playback laser beam onto a track. Information recording and reproducing devices equipped with the above are known.

Here, an example of the latter will be explained. In FIG. 9, a is a recording/reproducing semiconductor laser, and the recording/reproducing laser beam emitted from the recording/reproducing semiconductor laser a is a collimating lens b1 a dichroic mirror C1 a polarizing beam splitter d11/4 The light passes sequentially through a wavelength plate e and an objective lens f, and is focused onto a tracking guide (track) of an information storage medium q.
The recording/reproducing laser beam La reflected from the tracking guide is returned to the polarizing beam splitter d through the objective lens and the quarter-wave plate e, and is reflected by the polarizing beam splitter d. This reflected recording/reproducing laser beam 1-a passes through a dichroic mirror 11, a spherical lens 1, and a cylindrical lens j in order and is irradiated onto a photodetector, which allows for information reading as well as astigmatism detection. Track deviation detection and defocus detection are performed using the following methods. 2 is an erasing semiconductor laser, and the erasing laser beam Ll) emitted from this erasing semiconductor laser β is guided to a dichroic mirror h, and is reflected by this dichroic mirror h, so that the recording/reproducing laser beam The laser beam Lb is combined with the laser beam a and travels along approximately the same optical path. However, if this erasing laser beam Lb is irradiated onto the photodetector k, it will have a negative effect on defocus detection, track deviation detection, etc. The erasing laser beam 1b is separated from the recording/reproducing laser beam La by a dichroic mirror h before reaching the photodetector k.

[Problem that the invention seeks to solve]

In the configuration of the optical head, the recording/reproducing laser beam 1
Since dichroic mirrors c and h are required to combine and separate the erasing laser beam Lb from a, the optical head has a complicated structure and is large! In addition to increasing the quantity and cost, it is not possible to use a plurality of laser beams of the same wavelength in order to combine and separate the laser beams ja and lb using the dichroic mirrors c and h. Furthermore, there is a problem that the access time becomes longer due to the weight of the optical head.

Note that some optical heads use a light shielding plate as a method of separating the erasing laser beam Lt from the recording/reproducing laser beam La, but in this case, in addition to making the optical head more complicated, it also becomes difficult to assemble and adjust the optical head. There is a problem that optical axis adjustment becomes difficult.

The present invention has been made based on the above-mentioned circumstances, and its purpose is to omit optical parts for combining and separating light, thereby simplifying the structure and reducing size and weight. It is an object of the present invention to provide an information recording/reproducing device which can reduce costs and shorten access time due to weight reduction.

[Structure of the Invention] [Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention provides an information storage medium in which first and second lights emitted from a light source are tracked by an objective lens. A photodetector receives the first and second lights that are focused on the information storage medium and guided through the information storage medium, and uses this first light to detect the first and second lights on the information storage medium. It performs at least one of track deviation detection and defocus detection of a focused spot of light, and corrects the detection signal from the photodetector so that it is not influenced by the second light, and detects the detected signal after this correction. The present invention is characterized in that at least one of track deviation correction and defocus correction is performed based on the detection signal.

[Effect]

The light reflectance of the information storage medium is determined from the light intensity of the first and second lights that are incident on a certain photodetection cell of the photodetector from the information storage medium, and a correction voltage is generated accordingly, and the correction is performed. A voltage is added to the track deviation detection signal voltage or the defocus detection signal voltage.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 5.

FIG. 2 shows an information recording and reproducing device according to the present invention.
In this figure, 1 is a disk-shaped information storage medium, which is a turntable 3 that is rotationally driven by a drive shaft 2.
A U is placed on top, and is held down by a holding member 4 from above.

The information storage medium 1 has a recording area on at least one side thereof, which is provided with a recording layer on which information can be recorded, reproduced, and erased using a laser beam or the like. In this recording area, a tracking guide (track) by a pre-group is formed in a spiral shape or a concentric circle shape.

An optical head 5 is provided below the information storage medium 1, and this is attached to a sliding portion 7 provided on a fixed portion 6 so as to be slidable along the radial direction of the information storage medium 1.

For access at the start of recording, reproducing, and erasing information, the main CPU creates a program for moving the optical head 5 and operates the drive circuit 10 for moving the optical head via the D/A converter 9, thereby controlling the entire optical head 5. It is designed to move.

Also, when accessing, the number of tracking guides provided on the information storage medium 1 is counted, and this causes the optical head 5 to
The current location of is now confirmed. That is, the output signal of the track deviation detection circuit 11 is
2, and when the optical head 5 crosses one tracking guide, one pulse is generated from the binarization circuit 12, and the number of pulses is counted by the counter 13 for counting the number of tracks. It has become.

Furthermore, after the access is completed, track deviation correction is started. That is, the photodetector 1 inside the optical head 5 will be described later.
The photoelectric signals obtained from 4 are sent to preamplifier array 1, respectively.
5 and is supplied to the track deviation detection circuit 11 via the arithmetic circuit 16, whereby a track deviation detection signal is obtained.

Then, when the analog switch 17 is activated, the signal is supplied to the optical head movement drive circuit 10,
As a result, the entire optical head 5 is moved to perform track deviation correction.

An objective lens 18 is provided within the optical head 5, and this objective lens 18 is arranged in the vertical direction (
The objective lens 18 is movable only in one axial direction (in the axial direction of the objective lens 18), that is, in one axial direction toward and away from the information storage medium 1. Then, it is moved by the objective lens drive circuit 20 in response to a signal from the defocus detection circuit 19. Immediately before the focusing servo loop is closed, the analog switch 21 is switched, thereby activating the objective lens automatic retraction circuit 22 and moving the objective lens 18 to the initial position.

In addition, in the figure, 23 is a recording signal processing circuit that generates a recording signal according to information recorded on the information storage medium 1;
4 is a recording light generation circuit that amplifies the light emitting layer according to the signal from the recording signal processing circuit 23; 25 is an erasing light generation circuit that generates a predetermined erasing light; and 26 is a reproduction circuit that generates a predetermined reproduction light. 27 is an analog switch, 28 is a laser light drive circuit, 29 is an information signal reading circuit, 30 is a binarization circuit, 31 is a reproduction signal processing circuit for modulating, demodulating, and error correction of the information signal, 32 is an interface circuit.

FIG. 3 shows the movable structure of the optical head 5, and numeral 41 in this figure is a movable mechanism section. The movable mechanism section 41 includes permanent magnets 42, 42 and a yoke 43...
The fixing part 6 constitutes a magnetic circuit 46 that shares the objective lens driving magnetic circuit 44 and the optical head driving magnetic circuit 45, the head body 48, and the optical head driving coil 4.
9, objective lens 18, objective lens support spring 50. Objective lens fixing member 51 and objective lens driving coil 5
2, which slides as one when correcting access/track deviation; the objective lens 18, an objective lens fixing member 51, and an objective lens drive coil 52, which slide together when correcting defocus. The movable part 54 moves vertically with respect to the optical head driving coil 49.

That is, the slide portion 7 is provided with a head main body 48, and the optical system except the objective lens 18 is integrated into the head main body 48. Also,
The objective lens 18 is movably mounted on the head body 48. Furthermore, the information storage medium 1 is arranged above the objective lens 18, and the hole 5 of the head body 48
5 is focused by an objective lens 18 and irradiated onto the information storage medium 1.
The laser beam reflected by the laser beam passes through the objective lens 18 again and enters the head body 48 through the hole 55. The objective lens 18 is arranged in the vertical direction (Z
direction), and can correct defocus caused by warpage, surface blur, etc. of the information storage medium 1.

Further, the head body 48 is movable in the lateral direction (X direction) together with the objective lens 18, and is configured to move within the range of the recording area of the information storage medium 1 for access.

Further, regarding track deviations caused by eccentricity of the information storage medium 1, the head main body 48 and the objective lens 18 are moved together to correct the track deviations, as will be described later. Note that this track deviation correction requires a high-band response characteristic, which is made possible by increasing the driving force by increasing the strength of the magnetic field and the number of turns of the optical head driving coil 49, and by reducing the weight of the movable part.

Furthermore, since defocus correction in the Z direction and correction of access/track deviation in the X direction are performed by the same magnetic circuit 46,
The direction of the magnetic field within the gap region 56 that generates the effective magnetic field is in the Y direction.

For this reason, the permanent magnet 42 is provided in an upright state, and the yoke 43 is arranged to surround the permanent magnet 42. Note that the gap region 56 that generates this effective magnetic field has a uniform magnetic field throughout the range of movement of the accessing head body 48.

Two systems of magnetic circuits 46 are provided, which share the objective lens driving magnetic circuit 44 and the optical head driving magnetic circuit 45.
They are arranged in parallel with each other at a predetermined distance with the yoke 43 facing inside. Since the force that moves the objective lens 18 and the head body 48 is generated within the gap region 56 that generates the effective magnetic field, the objective lens 18 and the head body 48 are moved between the two systems of magnetic circuits 46, 46, that is, the two permanent magnetic circuits. It is arranged between magnets 42,42. This makes it possible to improve the efficiency with which force is transmitted during movement compared to the case where the magnetic circuits 46 and 46 are arranged outside of the two systems.

Moreover, the head main body 48 is disposed on the opposite side of the gap fI4 region 56 that generates an effective magnetic field across the yoke 43,
The head body 48 is sandwiched between the yokes 43, 43 of the two magnetic circuits 46, 46. As a result, the head body 48 is surrounded by the high magnetic permeability material forming the yoke 43, and the magnetic field from the gap region 56 is prevented from leaking and reaching the head body 48 or the objective lens 18.

Further, yokes 43.43 sandwiching the head body 48 are provided along the direction in which the optical head 5 moves for access, and these yokes 43.43 serve as guides for sliding the head body 48 and the objective lens 18. It is used for both purposes.

Further, the optical head driving coil 49 is wound so as to surround the guide yoke 43 in a direction along the same plane. Therefore, since the optical head driving coil 49 extends in two directions within the gap region 56 having an effective magnetic field in the Y direction, a force acts in the X direction when current is applied.

The head main body 48 also has an optical head drive coil 49 at a portion of its upper surface that contacts the optical head drive coil 49.
is firmly connected to. For this reason, the Gear Tsubu territory tit
! The force received by the optical head drive coil 49 within the optical head drive coil 49 is directly transmitted to the head body 48, thereby causing the head body 48 to move.

In addition, two optical head drive coils 49 are arranged so as to sandwich the objective lens 18 between them, and as a result, a stronger force is obtained during driving than when only one optical head drive coil 49 is used, and the response speed is improved. do.

The objective lens 18 is firmly connected to an objective lens driving coil 52 by an objective lens fixing member 51 at its outer circumference, so that the objective lens 18 moves in conjunction with the objective lens driving coil 52. .

Further, the objective lens driving coil 52 and the optical head driving coil 49 are connected to an objective lens supporting spring 50 made of a plate spring.
The coils 52 and 49 are connected to each other, and both coils 52 and 49 are movable independently of each other.

Further, the objective lens driving coil 52 is configured in a saddle shape, and is arranged so as to straddle the head main body 48 and the yoke 43. That is, the objective lens driving coil 52
0 The part located near the objective lens 18 is the objective lens 18.
The gap region 5 is provided along a direction perpendicular to the optical axis direction (two directions) of the objective lens 18 with the
It has a twisted relationship with the part located within 6. Therefore, a part of the objective lens drive coil 52 extends in the X direction within the gap region 56 having an effective magnetic field in the Y direction, and this allows the objective lens 18 to rotate vertically in order to correct defocus. direction).

FIG. 4 schematically shows the optical head 5. In the figure, 61
is a semiconductor laser array (light source) that includes a recording/reproducing semiconductor laser 61a that generates a recording/reproducing laser beam La and an erasing semiconductor laser 61k that generates an erasing laser beam 1b. The recording/reproducing laser beam La emitted from the recording/reproducing semiconductor laser 61a of the semiconductor laser array 61 and the erasing laser beam Lb emitted from the erasing semiconductor laser 61b are arranged to travel with a slight inclination. These records/
The reproducing laser beam 1a and the erasing laser beam Lb are converted from diverging light into substantially parallel light by passing through the light transmitting/receiving lens 62, and then enter the prism 63. The laser beam incidence surface of this prism 63 is a refracting surface 63a tilted with respect to the optical axis, so that the laser beam La
.

When lb is incident, refraction occurs, and the laser beams are emitted in the refracted direction, and the spot sizes of a and lb are changed, thereby correcting the cross-sectional shapes of the laser beams La and Lb.

Laser light incident on the refractive surface 63a of the prism 63 1. a, (-b is approximately 100% reflected by the polarized beam splitting surface 64 provided on the other surface of the prism 63,
1/4 wavelength plate 70. After passing through the objective lens 18, the light is focused on the information storage medium 1.

The laser beams la and Lb focused on the information storage medium 1 are reflected on the information storage medium 1 and are reflected again by the objective lens 18.
After passing through the quarter-wave plate 70, the light enters the prism 63 and returns to the polarized beam splitting surface 64. Here, the laser beam 1a.

By reciprocating through the 1/4 wavelength plate 70, the vibration direction of 1b is 9 compared to when it is reflected by the polarized beam split surface 64.
It becomes linearly polarized light rotated by 0 degrees. Therefore, the laser beams 1-a and Lb returned to the polarized beam split surface 64 pass through this polarized beam split surface 64, and the light separating and reflecting members 65 superimposed on the polarized beam split surface 64 are adjacent to each other with an inclination. three light separation reflective surfaces 65a,
65b.

After being reflected at 65G, the polarized beam splits into the plane 64 again.
pass through. Then, the laser beam 1a.

Ll) from the semiconductor laser array 61 to the information storage medium 1
The light beam passes through an optical path substantially similar to the optical path of the light transmitting system that it took when heading to , passes through the light transmitting/receiving lens 62 , and proceeds toward the photodetector 14 provided close to the semiconductor laser array 61 . In this case, the light separating and reflecting surfaces 65a, 65b, and 65c are provided non-parallel to the polarized beam splitting surface 64,
For this reason, the polarized beam splitting surface 64 and the photodetector 14
Alternatively, between the semiconductor laser array 61, the optical axis of the laser beams 1a and 1b of the light transmission system from the semiconductor laser array 61 to the information storage medium 1 and the light receiving system from the information storage medium 1 to the photodetector 14. The optical axes of the laser beams are tilted to each other. Here, the light separation reflection surfaces 65a, 6
5b, 65c so that the laser beam component reflected on at least one surface thereof intersects the optical axis of the laser beam of the light transmission system before reaching the photodetector 14.
.

65G direction is set. In addition, the light reflection separation surface 6
The boundary line between 5b and 650 is set to be substantially parallel to the direction in which the tracking guide of the information storage medium 1 extends or the direction in which the image of the tracking guide projected on the photodetector 14 extends.

Further, the laser beam component reflected by the light separation reflection surface 65a is used for defocus detection using the principle of the so-called knife etching method, and is used for defocus detection using the principle of the so-called knife etching method, and is used for defocus detection photodetection cell 6 on the photodetector 14.
The light is focused on 6a and 66b.

In addition, the laser beam components reflected by the light separation reflection surfaces 65b and 65C are used for tracking deviation detection using the so-called push-pull method, which detects tracking deviations using the diffraction pattern of the reflected light from the tracking guide of the focused laser beam. be done. That is, the far field pattern for the condensed spot of the information storage medium 1 is the light separating reflective surface 65b,
The light is divided by 65G, and each light is focused on photodetection cells 67a and 67b for detecting track deviation of the photodetector 14.

Furthermore, the semiconductor laser array 61 and the photodetector 14 are provided on the same mount 68. Here, the light transmitting/receiving lens 62 includes a lens for collimating the laser light of the light transmitting system emitted from the semiconductor laser array 61 and a lens for condensing the laser light of the light receiving system onto the photodetector 14. It is used for both purposes. That is, both the laser light [-a, lb of the light transmitting system and the laser light 1a, lb of the light receiving system] pass through this light transmitting/receiving lens 62. The light transmitting light receiving lens 62 and the objective lens 18
Since the laser beams 1-a and 1b are parallel beams when in focus, the laser beams La and Lb of the light receiving system when in focus.
Since the light is focused on the same plane as the light emitting point of the semiconductor laser array 61 (on the focal plane of the light transmitting/receiving lens 62), the light emitting point of the semiconductor laser array 61 and the light receiving surface of the photodetector 14 are substantially parallel to each other. are placed on the same plane.

Further, the mount table 68 is constructed by integrally connecting a semicircular columnar body 68a with a semicircular arc-shaped frame body 68b, and has a rotatable structure as a whole. In this case, the light emitting point of the semiconductor laser array 61 is located at the center of rotation of the mount 68, so that when the mount 68 rotates, the optical axes of the laser beams La and Lb of the light transmission system do not shift. ing. As shown in FIG. 5, the light detection cell 66a for defocus detection, 66b is arranged, and when adjusting the assembly of the optical head 5, the defocus detection system can be adjusted by rotating only this mount 6B.

Further, in order to enable such adjustment, a laser beam that moves on the light detection cells 66a and 66b for detecting defocus according to the direction along the circumference of the mount base 68 and the defocus on the information storage medium 1 is provided. 1-a.

The moving direction of 1b is substantially parallel to the moving direction of 1b.

Further, a photodetection cell 67a for detecting track deviation.

671) is arranged approximately along the radial (radial) direction of the mount base 68, and when the mount base 68 rotates, it emits a laser beam for detecting track misalignment. It is designed not to move on top.

Note that a photodetection cell 67a for detecting track deviation.

The prism 63.1/4 is used to adjust the unbalance of the light intensity of the laser beam La irradiated onto the 67b and to adjust the light intensity ratio of the laser beam 1a used for defocus detection and track deviation detection.
Mounting base 68 and light transmitting/receiving lens 62 for wavelength plate 65
This can be done by simultaneously moving the two in parallel.

Further, the refraction surface 63a of the prism 63 is configured so that the laser beams 1a, 1-b of the light transmitting system and the laser beams 1a, 1 of the light receiving system
However, this refractive surface 63a is used for the laser beams La and Lb of the light transmitting system, as described above.
, Lb functions as a refractive surface for correcting the cross-sectional shape. However, for the laser beams La and Lb of the light receiving system, it functions as a refractive surface for improving defocus detection sensitivity. That is, the laser beam 1a of the light receiving system is transmitted to this refracting surface 63a.

A plane including the normal line when 1b is refracted (this refracting surface 63
Laser beam 1a of the light receiving system refracted at point a.

The centers of the laser beams La and Lb move in the direction along the plane that includes both the optical axis of the incident light and the optical axis of the emitted light Lb, and on the light detection cells 66a and 66b for detecting defocus when defocus occurs. If the direction is parallel to the direction in which the laser beam is focused, the laser beam la of the light receiving system is a parallel beam when focused.

When Lb passes through the refraction surface 63a, the laser beam La,
Laser beam 1-a with varying cross-sectional dimensions of Lb.

When Lb is emitted from the prism 63 to the outside, the cross-sectional diameter becomes narrower), thereby increasing the effective imaging magnification of the condensed spot on the information storage medium 1 onto the photodetector 14, which causes defocusing. This will change (increase) the detection sensitivity.

Next, FIG. 1 shows a defocus correction circuit 81 that corrects the defocus of a focused spot on the information storage medium 1.
5. It is composed of a defocus detection circuit 19 which is a servo circuit, a gain control/phase compensation circuit (not shown), an objective lens drive circuit 20, an arithmetic circuit 16, a main CPU, etc. The preamplifier array 15 includes a preamplifier 82a that amplifies the respective outputs from the photodetection cells 67a and 67b for detecting track deviation and the photodetection cells 66a and 66b for detecting defocus.

It is composed of 82b, 83a, and 83b. The arithmetic circuit 16 includes preamplifiers 82a and 82b.

A processing circuit 84 and preamplifier 82a perform various processing based on outputs from 83a and 83b.

an adder circuit 85 that adds the outputs from the adder circuit 82b; an A/D converter 86 that converts the output from the adder circuit 85 into digital data and supplies it to the main CPU 8;
6 to the main CPU 8, and D/A converts the signal which has been subjected to predetermined processing to be described later by the main CPU 8.
It is comprised of a /A converter 87, an adder circuit 88 that adds the signal from the D/A converter 87 and the signal from the preamplifier 83a, and the like. One of the defocus detection circuits includes a subtraction circuit 89 that performs subtraction processing between the signal from the addition circuit 88 and the signal from the preamplifier 83b. Preamplifiers 82a, 82b, addition circuit 85, A/D:I inverter 86, main CPU 8, D
A correction voltage generating section 90 is configured to generate a correction voltage that is generated by the /A converter 87.

Therefore, except when erasing information on the information storage medium 1, that is, when recording or reproducing, only the recording/reproducing semiconductor laser 61a is turned on, and each cell 66a, 66 of the photodetector 14 is turned on.
On b, 67a, 67b is a recording/reproducing laser beam 1a.
This is used for defocus detection and track deviation detection.

When erasing information on the information storage medium 1, a recording/reproducing semiconductor laser 61a and an erasing semiconductor laser 61b are used.
are both turned on, and the recording/reproducing laser beam 1a and the erasing laser beam Lb are irradiated onto the photodetector 14. In this case, in the track deviation detection system, the erasing laser beam Lb is also focused on the center of the tracking guide on the information storage medium 1, similar to the recording/reproducing laser beam 1-a, and the diffraction pattern of the reflected light there Since track deviation detection is performed, the optical detection cell 67 for track deviation detection
Even if the erasing laser beam Lb is irradiated onto a and 67b, the recording/reproducing laser beam 1. Track deviation detection is performed using the difference between the detection signals of the respective photodetection cells 67a and 67b, as in the case where only the photodetection cells 67a and 67b are illuminated. On the other hand, in the defocus detection system, defocus detection is performed using the recording/reproduction laser beam 1a, so when the focus is focused, the recording/reproduction
The laser beam La for reproduction is transmitted through a light detection cell 66 for detecting defocus.
The structure is such that the boundary between a and 66b is irradiated, and therefore the erasing laser beam b is irradiated only to one defocus detection cell 66b. This erasing laser beam Lb
In order to correct the influence of
An adder circuit 88 adds the signal from the preamplifier 83a to which the signal from the preamplifier 83a is supplied. That is, the outputs of the preamplifiers 82a and 82b to which the outputs of the photodetection cells 67a and 67bhs for detecting track deviation are supplied to the adder circuit 8.
5, and the output from the adder circuit 85 is supplied to the main CPU via the A/D converter 86. This makes it possible to monitor the light reflectance of the information storage medium 1, and while monitoring the light reflectance of the information storage medium 1, the main CPU 8 detects the defocus detection light detection cell 66b.
The amount of erasing laser light Lb irradiated on the area is calculated, and a correction voltage corresponding to the calculated value is supplied to the addition circuit 88 via the D/A converter 87.

In other words, since the light intensity ratio between the erasing laser beam Lb during erasing and the recording/reproducing laser beam 1-a is constant everywhere regardless of the location on the information storage medium 1 where it is irradiated, the defocus detection light The light intensity ratio between the erasing laser beam Lb and the recording/reproducing laser beam 1a in the detection cells 66a, 66b is always kept constant. Therefore, the light reflectance of the information storage medium 1 is determined from the output of the adding circuit 85, and this reflectance and
Light intensity attenuation coefficient in the optical path and semiconductor laser for ° erasure 6
The value of the correction voltage to be applied to the adder circuit 88 is obtained by multiplying the sum of erasing laser beams Lb emitted from 1b. This correction voltage is applied to the defocus detection photodetection cell 6 that is not irradiated with the erasing laser beam Lb.
An adder circuit 88 adds the output of the preamplifier 83a to which the output of the preamplifier 6a is supplied, and the output of the adder circuit 88 and the output from the defocus detection photodetection cell 66b to which the erasing laser beam Lb is irradiated are supplied. preamplifier 83
b is subjected to subtraction processing by a subtraction circuit 89, and based on the output of this subtraction circuit 89, the objective lens 18 is driven in the optical axis direction to perform defocus correction.

According to the above configuration, there is no need to arrange a dichroic mirror, a light shielding plate, etc. to prevent the photodetector 14 from being irradiated with the laser beam 1b other than the laser beam 1a used for defocus detection. Even if the configuration is such that the beams A and Lb are focused on the information storage medium 1, the optical structure can be exactly the same as the configuration where one laser beam is focused. Therefore, the structure can be simplified and it can be provided at a very low cost. Moreover, since there is no need to use a dichroic mirror, a plurality of light sources emitting light of the same wavelength can be used.

Furthermore, the simplification of the structure makes it possible to reduce the size and weight, thereby facilitating high-speed access.

Next, other embodiments of the optical head 5 and the defocus correction circuit 81 will be described with reference to FIGS. 6 to 8. Incidentally, the same components as those in the above embodiment are denoted by the same reference numerals, and the explanation thereof will be omitted.

In FIG. 6, 101 is a light splitting member, and this light splitting member 1
01 has a structure having a light-reflecting flat surface 102 and a light-reflecting aspherical curved surface (such as a cylindrical concave lens surface) 103 slightly inclined with respect to the light-reflecting plane 102. and,
The recording/reproducing laser beam La and the erasing laser beam 1b are split by the light-reflecting plane 102 and the light-reflecting aspherical curved surface 103, respectively, and form a polarized beam split surface 6.
After passing through the light transmitting and receiving lens 62, the light beams are guided onto the photodetector 104 shown in FIG. 7, respectively.

When the objective lens 18 focuses on the information storage medium 1, the recording/reproducing laser beam La reflected by the light reflective plane 102 is focused on the boundary between the defocus detection cells 105a and 105b, and is focused on the boundary between the defocus detection cells 105a and 105b, cell 105a, 10
5b, and thereby defocus detection is performed using the so-called knife etching method. On the other hand, the light reflective aspheric curved surface 1
The recording/reproducing laser beam 1a reflected at 03 is stretched in one direction by the action of the light-reflective aspherical curved surface 103, and then reaches the track deviation detection cell 106a.

The light is focused on the track deviation detection cell 106b, but in this stretched direction, a far field pattern is formed for the information storage medium 1 when focused.
a, laser beam focused using 106b 1. Track misalignment is detected by the so-called bush-pull method, which detects track misalignment using the diffraction pattern of the reflected light from the tracking guide (a). Additionally, the light reflective plane 102
The erasing laser beam 1b reflected by the defocus detection cell 105b is irradiated onto one of the defocus detection cells 105b. On the other hand, the erasing laser beam Lb reflected by the light-reflecting aspherical curved surface 103 is not focused on the track deviation detection cells 106a and 106b, but is irradiated onto a non-sensing area outside of the cells 106a and 106b.

Further, 111 is an arithmetic circuit, and this arithmetic circuit 111 includes preamplifiers 82a, 82b, and 83a.

A processing circuit 84 performs various processing based on the output from the preamplifier 83'b, an adder circuit 112 that adds the outputs from the preamplifiers 82a and 82b, and a gain control circuit 1 that controls the gain of the output from the adder circuit 112.
13. Addition circuit 114 that adds the signal from this gain control circuit 113 and the signal from the preamplifier 83a.
It is made up of etc. And preamplifiers 82a, 82
b, addition circuit 112, gain control circuit 113,
The addition circuit 114 constitutes a correction voltage generation section 115 that generates a correction voltage.

Therefore, the photodetection cells 106a, 1 for detecting track deviation
06b is irradiated with the recording/reproducing laser beam la,
Outputs corresponding to the light intensity of the recording/reproducing laser beam la are outputted from the track deviation detection photodetection cells 106a and 106b to the preamplifiers 82a and 82b. The outputs of the preamplifiers 82a and 82b are added together by an adder circuit 112, and the output of the adder circuit 112 adds up the information storage medium 1.
The light reflectance of is monitored. Since the light intensity ratio between the recording/reproducing laser beam La and the erasing laser beam Lb is determined, the output of the adder circuit 112 is controlled by the gain control circuit 113 based on this light intensity ratio, and the erase is performed by the gain control circuit 113. A correction voltage corresponding to the amount of laser light Lb is generated.

According to such a configuration, the output gain of the gain control circuit 113 is adjusted according to the light intensity ratio of the erasing laser beam 1b and the recording/reproducing laser beam 1-a, and the optical detection cell 106a for detecting track deviation, Since the addition signal of the output of 106b is directly added to the defocus detection signal as a correction signal, calculations in the main CPU 8 can be omitted.

In the above embodiment, the defocus correction circuit 81 has been described, but the present invention is not limited to this, and the track deviation correction circuit (not shown) is also applicable. ) can also correct for extra light. In this case, the photodetection cell for defocus detection 6
6a, 66b (105a, 105b) and optical detection cells 67a, 67b (106a, 106b) for detecting track deviation.
) and reverse the electrical wiring.

[Effects of the Invention] As explained above, according to the present invention, there is a light source that generates first and second lights, and the first and second lights emitted from the light source are transferred onto an information storage medium having a track. an objective lens that receives the first and second lights guided through the information storage medium, and uses this first light to collect the first and second lights on the information storage medium. A photodetector that performs at least one of detecting a track deviation of a focused spot and detecting defocus, and a detection signal from this photodetector is corrected so as not to be affected by the second light, and the detection after this correction is performed. Since the present invention is equipped with a correction circuit that performs at least one of track deviation correction and defocus correction based on the signal, it is possible to omit optical components for combining and separating light.
By simplifying the configuration, it is possible to achieve reductions in size, weight, and cost, and the reduction in weight also provides significant effects such as shortening of access time.

[Brief explanation of drawings]

Figures 1 to 5 show one embodiment of the present invention.
The figure is a block diagram showing a semiconductor laser array, a photodetector, and a defocus correction circuit, FIG. 2 is a block diagram showing an information recording/reproducing device, FIG. 3 is a perspective view showing a movable mechanism of an optical head, and FIG. FIG. 5 is a perspective view showing a schematic configuration of an optical head, FIG. 5 is a front view showing a semiconductor laser array and a photodetector, and FIGS. 6 to 8 show other embodiments of the present invention. 7 is a perspective view showing the schematic configuration of the optical head;
The figure is a front view showing a semiconductor laser array and a photodetector, FIG. 8 is a block diagram showing a semiconductor laser array, a photodetector, and a defocus correction circuit, and FIG. 9 is a block diagram showing a conventional example. 1a... first light (recording/reproduction laser light), 1,
-b... Second light (erasing laser light), 1... Information storage medium, 18... Objective lens, 14, 104...
・Photodetector, 61...Light source (semiconductor laser array)
, 81... Defocus correction circuit, 90.115... Correction voltage generation circuit.

Claims (3)

[Claims] (1) a light source that generates first and second lights; an objective lens that focuses the first and second lights emitted from the light source onto an information storage medium having a track; The first and second lights guided through the information storage medium are received, and the first light is used to detect a track deviation and focus of the condensed spots of the first and second lights on the information storage medium. A photodetector that performs at least one of blur detection, and a detection signal from this photodetector is corrected so as not to be affected by the second light, and based on this corrected detection signal, track deviation correction and focus are performed. An information recording/reproducing apparatus comprising: a correction circuit that performs at least one of blur correction. (2) The correction circuit has a correction voltage generation section that generates a certain voltage, and adds the correction voltage obtained from this correction voltage generation section to the track deviation detection signal voltage or defocus detection signal voltage from the photodetector. An information recording and reproducing apparatus according to claim 1, characterized in that: (3) The information recording and reproducing apparatus according to claim 2, wherein the correction voltage generating section changes the correction voltage in accordance with the light reflectance of the information storage medium.