JP3214532B2 - Optical information reproducing method and apparatus therefor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information reproducing method and apparatus for reproducing information from an information recording medium having recording marks formed along a plurality of tracks.

[0002]

2. Description of the Related Art Conventionally, in an optical disk device, as disclosed in Japanese Patent Application Laid-Open No. 1-245433 and the like, light emitted from a semiconductor laser is narrowed down to one point on an optical disk medium by using an optical system and irradiated. The optical system collects the reflected light from the optical system, guides the reflected light to a light detector, captures the change in the light intensity and the polarization direction of the reflected light on the light detector, and reproduces a signal recorded at one point.

[0003] Also, High-Density Land / Grove Rexordin
g for Digital Video File System (Papers of the Japan Society of Applied Physics Jpn. J. Appl. Phys. 32 (1993) 5449-5450
As disclosed in Japanese Patent Application Laid-Open No. H11-163, a technique for suppressing crosstalk using three laser beams is known as a technique for improving track density.

That is, as shown in FIG. 2, recording pits 102 formed on a plurality of tracks of a magneto-optical disk 101
Is reproduced, three beam spots 106, 107 and 108 are irradiated by the three-beam magneto-optical head 104, and the center beam 107 of the three beams is positioned on the reproduced data track 103. The main signal and the two sub-signals obtained by these three beam spots are input to the crosstalk cancel circuit 105 to remove the crosstalk and obtain a reproduced signal.

However, in this method, although the track pitch is about 0.8 μm, the interval between the beam spots formed on the magneto-optical disk 101 by the laser beam is one.
It is at least 0 μm, which is more than 10 times the track pitch in the track direction than shown in FIG. Considering that the minimum interval between the recording pits 102 is 0.5 μm, the beam spot deviates from the minimum interval for recording by 20 times or more. That is, in the reproducing system, it is necessary to compensate for the positional deviation between the beams.

[0006]

However, as described above, since detection is performed by one detector, crosstalk from an adjacent track cannot be suppressed, and the track density cannot be improved.

Further, a method using a three-beam laser to suppress the influence of crosstalk has been proposed. However, an expensive and well-characterized laser beam having three light beams is required. A complicated reproducing circuit system for correcting a displacement of a reproduced signal due to a beam spot interval formed by the laser beams is required.

An object of the present invention is to provide an optical information reproducing method and apparatus capable of easily suppressing crosstalk from an adjacent track in view of the above problems.

[0009]

SUMMARY OF THE INVENTION In order to achieve the above object, according to the present invention, a first aspect of the present invention relates to a recording mark formed along a plurality of tracks on an information recording medium using a light beam. In an optical information reproducing method for reproducing information,
A recording mark exists on an adjacent track on the information recording medium.
Crosstalk detection area consisting of multiple types of patterns
Irradiating the crosstalk detection area with a light beam,
The light returning from the crosstalk detection area is
Is spatially divided into three in the width direction of
Each light is collected and detected by a separate detector.
Multiply each of the signals from the two regions other than the
In the output subtracted from the signal from the central region
Lost talk is minimized for each of the plurality of types of patterns.
Then, the operation coefficient is determined so as to irradiate the information recording medium with a light beam, and the light returned from the information recording medium is spatially divided into three in the track width direction. The divided light is condensed and detected by separate detectors , and signals from two areas other than the detected center area are separated.
Signal from the central area by multiplying each of the
An optical information reproducing method for reproducing the information of the recording mark by subtraction is proposed.

According to a second aspect of the present invention, in the optical information reproducing method according to the first aspect, an optical information reproducing method is proposed in which the divided area of the light corresponds to a diffracted light shape of crosstalk from an adjacent track.

According to a third aspect of the present invention, there is provided an optical information reproducing apparatus for irradiating an information recording medium with a light beam to reproduce information of a recording mark formed along a plurality of tracks on the information recording medium. a light dividing element that divides the light returned from the recording medium into three spatially in the width direction of the track, a plurality of detecting means for detecting separately the divided light by the light splitting element, said plurality of Calculating means for calculating an output signal of the detecting means , wherein the calculating means is provided in a central area.
Of detecting means for detecting light from two regions other than the region
Multiply each of the signals by an arithmetic coefficient to detect light from the central area.
The recording mark is subtracted from the output signal of the detecting means.
Has the function of reproducing the information of the
Of multiple patterns in which recording marks exist on adjacent tracks.
Cross toe provided on the information recording medium Ru down Tona
Output from the calculation means when the light beam
Crosstalk in force is caused by each of the patterns
We propose an optical information reproducing apparatus that uses an operation coefficient determined so as to minimize .

According to a fourth aspect of the present invention, in the optical information reproducing apparatus according to the third aspect, the light division area set by the light dividing element is set so as to correspond to the shape of diffracted light of crosstalk from an adjacent track. A playback device is proposed.

[0013]

According to the optical information reproducing method of the first aspect of the present invention, in order to determine the operation coefficient , the optical information reproducing medium is placed on the information recording medium.
Multiple types of patterns where recording marks exist on adjacent tracks
Crosstalk detection area is provided on the information recording medium
Irradiating the crosstalk detection area with a light beam,
The light returning from the crosstalk detection area is
Are spatially divided into three in the width direction of the workpiece. In addition,
Each split light is collected and detected by a separate detector.
You. Next, two areas other than the detected center area
Each of these signals is multiplied by a calculation coefficient, and from the central area
Crosstalk in the output subtracted from the signal of
The performance is minimized for each of multiple types of patterns.
An arithmetic coefficient is determined. Thereafter, a light beam is irradiated onto the information recording medium in order to reproduce information , and three light beams returned from the information recording medium are spatially separated in the width direction of the track.
It is divided into. Further, each of the divided lights is collected and detected by a separate detector, and the detected signals are calculated to reproduce the information of the recording mark.
In this calculation, two regions other than the detected central region
Each signal from the area is multiplied by the above calculation coefficient to obtain a central area.
The recording mark by subtracting from the signal from the
Information is reproduced. As a result, the crosstalk diffracted light from the adjacent track and the reproduction light from the recording mark of the own track are detected separately.

According to the second aspect, the light division area is made to correspond to a diffracted light shape of crosstalk from an adjacent track, and a signal component to be reproduced and a crosstalk component are separated.

According to the third aspect, the light returned from the information recording medium is spatially divided into three in the width direction of the track on the information recording medium by the light dividing element. Furthermore, it light divided into three by the optical splitter
Each is detected by a separate detection means, of the detection means
The output signal is calculated by the calculation means. For example, light is spatially divided into three parts at a portion where the signal component from the recording mark is large and at both ends in the track width direction. Is subtracted. In the above calculation, the calculation coefficient is
Of multiple patterns in which recording marks exist on adjacent tracks.
A crosstalk provided on the information recording medium comprising
Output from the calculation means when the light beam
Crosstalk in force is applied to each of the above patterns
Using the operation coefficient determined to be minimum for
Two areas other than the central area among the three areas
Each of the output signals of the detecting means for detecting light from the area
A detection method that detects light from the central area by multiplying an arithmetic coefficient
Subtracting from the output signal of the stage, the information of the recording mark is reproduced.
Be born. This suppresses effects other than noise and signal components of recording marks.

According to the fourth aspect, the light division area is made to correspond to a diffracted light shape of crosstalk from an adjacent track, and a signal component to be reproduced and a crosstalk component are separated.

[0017]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a first reference example according to the present invention. In the figure, 1 is an optical disk, 2 is an objective lens for forming a beam spot on the optical disk 1, 3 is a beam splitter for separating light, 4 is a beam splitting element composed of, for example, a mirror, 44 is a splitting element mounting section, 5 is, for example, A beam shaping unit composed of a lens, 6 is a laser, 7, 8,
9 is a condenser lens, 10, 11, and 12 are detectors, and 13 is an arithmetic circuit.

[0019] Hereinafter will be described the detailed configuration and operation of the present embodiment.

The light emitted from the laser 6 is shaped into parallel light by the beam shaping unit 5, and the parallel light passes through the beam splitter 3 and is focused on the recording layer on the optical disk 1 by the objective lens 2. . The direction of the reflected light from the recording layer can be changed by the beam splitter 3 (to change the direction, a well-known quarter-wave plate (not shown) is inserted,
S, etc.), and goes to the beam splitter 4.

FIG. 3 shows a beam splitting area in a cross section of the beam splitting element 4. As shown in the figure, the beam cross section is divided into a first area 21, a second area 22, and a third area 23 with respect to the beam traveling direction on the optical disc 1. Here, the shapes of the first area 21 and the third area 23 are made wider in the track width direction and narrower toward the center so that the high-frequency component of the reproduction signal does not decrease. still,
The first region 21 and the third region 23 may be in contact at the center.

The first area 21 and the third area 23 are part of the diffracted light areas 24 and 25 representing crosstalk from adjacent tracks, respectively. , The effect of crosstalk can be observed. Therefore, the first region 21 and the third region 21
The beam splitting element 4 is inserted into the portion of the region 23 to separate the light. As a result, the light in the second area 22 is condensed on the detector 10 by the condensing lens 7, and the light in the first area 2
The light of 1 is condensed on the detector 11 by the condensing lens 8,
The light in the third area 23 is transmitted to the detector 12 by the condenser lens 9.
Is collected. Output signals of the detectors 10 and 11 and the detector 12 are guided to an arithmetic circuit 13, and these output signals are calculated by the arithmetic circuit 13.

In the arithmetic circuit 13, the output of the detector 10 is
1, the output of the detector 11 is V2 and the output of the detector 12 is V3
Then, a calculation based on the following equation (1) is performed, and the calculation result is output as a signal O. O = V1−aV2−bV3 (1) where a and b are amplification factors, which depend on the size and shape of the beam splitting region in FIG. As a good example, when the crosstalk signal component included in the signal V1 is Vc, O <z
A is set so that V2 <2Vc. A good example of almost completely suppressing crosstalk is 0.8 V
c <aV2 <1.2Vc.

As described above, by constructing the reproducing system, a signal from a recording mark of an adjacent track on the optical disc 1 is converted into a diffracted light area 24 and a diffracted light as a parallel beam intensity distribution which is a Fourier transform surface on the optical disc 1. Light area 2
Appears growing to 5.

Therefore, the first region 21 and the third region 23
Is subtracted from the signal in the second area 22 to reproduce the signal while suppressing the influence of the recording mark on the adjacent track. Also, assuming that the noise is random and appears uniformly in the first to third regions 21, 22, 23, the signals in the first region 21 and the third region 23 are By subtracting with a signal, the effect of noise can be offset.

That is, by utilizing the Fourier transform effect of the light lens, crosstalk can be suppressed and noise can be suppressed, and recording marks on the optical disc 1 can be detected with high sensitivity. Further, since the light is condensed on the detector by the condensing lens after splitting the beam, high-speed photoelectric conversion can be performed. Further, since one light beam is used, it is not necessary to correct the positional deviation of the reproduction signal due to the beam spot interval as in the related art.

Although a focus signal and a tracking signal necessary for detecting an actual signal are detected by light separated by a beam splitter (not shown), a well-known method can be used. .

Next, a second embodiment according to the present invention will be described.

The device structure of this second reference example is first described above
The description is omitted because it is the same as the reference example . Also,
The difference between the second reference example and the first reference example is that the shape of the light beam splitting region by the beam splitting element 4 is changed.

That is, as shown in FIG. 4, the divided area of the light beam by the beam splitting element 4 in the second reference example matches the shape of the crosstalk diffracted light as compared with the divided area shown in FIG. Thus, the divided shape is a curve. In this way, signals from recording marks on adjacent tracks can be efficiently collected in the first and third areas 31, 33, and signals from minute marks can be detected efficiently. Note that the first region 31 and the third region 33 may be in contact at the center.

Next, a third embodiment according to the present invention will be described.

The apparatus configuration of the third reference example first mentioned above
The description is omitted because it is the same as the reference example . Also,
The difference between the third reference example and the first reference example is that the shape of the light beam splitting region by the beam splitting element 4 is changed.

That is, as shown in FIG. 5, the divided area of the light beam by the beam splitting element 4 in the third reference example has a straight shape as compared with the splitting element shown in FIG. This makes it possible to easily process the beam splitting element 4 and suppress the influence of tracking to efficiently detect a signal from a minute mark.

Next, a fourth embodiment according to the present invention will be described.

FIG. 6 is a block diagram showing a fourth reference example according to the present invention. In the figure, the same components as those of the above-described first reference example are denoted by the same reference numerals, and description thereof will be omitted.
The difference between the fourth reference example and the first reference example is that mirrors 571, 572, 581, and 58, which are beam splitting elements, are provided.
2 is used to split the light beam, and each of the split light beams is focused on detectors 541, 542, and 543 via the same focusing lens 53.

That is, the reflected light from the optical disk 1 reaches the split element mounting portion 55 via the objective lens 2 and the beam splitter 3, and a part of the mirror 571 and the mirror 571 mounted on the split element mounting portion 55 For example, the light is reflected in different perpendicular directions by 581. Mirror 57
A portion of the light beam not irradiated to the light beam 581 is condensed by the condenser lens 53 on the detector 542 on the substrate 54, converted into an electric signal, and input to the arithmetic circuit 56.

On the other hand, the light beam reflected by the mirror 571 is applied to the mirror 572, reflected by the mirror 572 toward the condenser lens 53, and
The light is condensed by the detector 3 on a detector 543 arranged on the substrate 54 alongside the detector 542.

Further, the light beam reflected by the mirror 581 is applied to the mirror 582, and the mirror 582
Thus, the light is reflected toward the condenser lens 53, and is condensed by the condenser lens 53 on a detector 541 arranged alongside the detector 542 on the substrate 54. These detectors 54
The electric signals obtained by the signals 1, 542, 543 are input to the arithmetic circuit 56 and subjected to arithmetic processing.

As described above, in the present embodiment , the elements to be split are changed, and the split light is compared with the first embodiment by using the same condenser lens 53 and the detector 54 on the same substrate 54.
1,542,543. With this configuration, the noise characteristics of the detectors 541, 542, 543 are made the same, and the detectors 541, 542, 5
The noise characteristics of the detectors 541 and 542.543 can be suppressed by differentially detecting the output signal of the detector 43 by the arithmetic circuit 56. Further, the head can be made compact. Here, the method of suppressing crosstalk is the first method.
This is the same as the reference example . In this case, the light may be divided as shown in FIGS. 3, 4, and 5.

Next, a fifth embodiment according to the present invention will be described.

FIG. 7 is a configuration diagram showing a fifth reference example according to the present invention. In the figure, the same components as those of the above-described first reference example are denoted by the same reference numerals, and description thereof will be omitted.
Moreover, differences from the fifth reference example of the first reference example, the fifth
In the reference example , the method of dividing is changed.

That is, in this embodiment , the polarization beam splitter 4 is replaced with the beam splitting element mounting section 44 of the first embodiment.
5 and two half-wave plates 46 are provided. This 1/2
The wave plate 46 has a shape as shown in FIGS. 3, 4 and 5 and is arranged in the reproduction beam.
After 6, a polarizing beam splitter 45 is arranged.

As a result, a part (both sides) of the reflected light from the optical disk 1 passes through the half-wave plate 46 and irradiates the polarization beam splitter 45, and the half-wave plate 4
Only the light whose polarization direction has been changed by 6 is reflected by the polarization beam splitter 45, and the other light is collected on the detector 10 by the condenser lens 7. Further, the light reflected by the polarization beam splitter 45 has two １ ／
Light is condensed on the detectors 11 and 12 by condensing lenses 8 and 9 provided corresponding to the respective wavelength plates 46.

Therefore, the light beam can be split by the half-wave plate 46 and the polarizing beam splitter 45, and the processing after the splitting is the same as in the first embodiment . Here, a light beam may be separated using a prism such as Wollaston in addition to the polarization beam splitter 45.

Similarly to the fourth embodiment , one of the separated light beams is reflected by a mirror, and the two separated light beams are separated by two detectors arranged side by side on one substrate. It can also be focused. In this case, if a prism such as Wollaston is used, there is no need to use a mirror, which is a good example. Furthermore, the light division form at this time is
What is necessary is just to carry out similarly to what was demonstrated about FIG. 3, FIG. 4, FIG.

Next, a sixth embodiment according to the present invention will be described.

The above reference examples are ROM such as CD, phase change,
Although the additional optical system has been described, in the case of magneto-optics, it can be realized as follows.

FIG. 8 is a configuration diagram showing a sixth reference example according to the present invention. In the present reference example , the steps from the point where the reproduction light is emitted from the laser 6, reflected by the optical disk 1 and directed to the splitting element mounting portion 55 are the same as in the fourth reference example shown in FIG. .

In this embodiment , the split element mounting portion 55
After that, the polarization beam splitter 71 is disposed, and the light split into three by the mirrors 571, 572, 581, and 582 of the splitting element mounting portion 55 is separated by the polarization beam splitter 71.
To further separate the light into two polarized light components. That is,
The light of one polarization component separated by the polarization beam splitter 71 passes through the polarization beam splitter 71 and travels to the condenser lens 77, and the light of the other polarization component is reflected by the polarization beam splitter 71 and travels to the condenser lens 87. Heading.

First, the light that has passed through the polarizing beam splitter 71 will be described. Here, as shown in FIG. 3, the beam cross section is
It is assumed that the area is divided into a first area 21, a second area 22, and a third area 23. Then, the first to third regions 21 and 21
Lights 2 and 23 are condensed by detectors 791, 792 and 793 arranged side by side on a substrate 79 by a condenser lens 77, and output signals K1, K2 and K of the detectors 791 to 793, respectively.
3 is input to the arithmetic circuit 78.

Next, the light that has been reflected by the polarizing beam splitter 71 and changed direction will be described. here,
As shown in FIG. 3, the beam cross section is divided into a first region 21, a second region 22, and a third region 23 with respect to the beam traveling direction on the medium. First to third regions 21,
Lights 22 and 23 are condensed by detectors 871, 892 and 893 arranged side by side on a substrate 89 by a condenser lens 87, and output signals J1, J2 and J2 of the detectors 891 to 893, respectively.
J3 is input to the arithmetic circuit 78.

The arithmetic circuit 78 includes detectors 791 to 793
And the output signals K1 to K of the detectors 891 to 893, respectively.
3, J1 to J3 are subtracted as follows: V1 = K1-J1, V2 = K2-J2, V3 = K3-J3 (2) The reproduction signal has the above value (1)
It can be obtained by substituting into the formula.

The detectors 791 to 793 and the detector 89
Signals 1 to 893 are calculated from the beginning by using the equation (1), and then the calculation results of the detectors 791 to 793 and the detector 891
The calculation results of 結果 893 may be subtracted. Further, in the present reference example , the light is first split and then split into two according to the polarization direction. However, the light may be split first into two according to the polarization direction and then split into three.

The light division mode at this time may be the same as that described with reference to FIGS. 3, 4, and 5.

The above reference examples may be performed alone or in combination.

Next, an embodiment of the present invention will be described.

FIG. 9 is a configuration diagram showing an optical disc in one embodiment of the present invention.

The configuration of this embodiment can be the same as that shown in the first to sixth embodiments , so that the description is omitted. The difference between this embodiment and the first to sixth embodiments is that a crosstalk detection area 83 is provided on an optical disc 83 and the crosstalk detection area 83 is provided.
The coefficients a and b in the above-described arithmetic processing are obtained based on the reproduction signal of the above.

That is, in the present embodiment, the coefficients a and b in the above-mentioned equation (1) are dynamically controlled in accordance with the characteristics at the time of reading the optical disk.

For example, a crosstalk detection area 83 is provided in a part of the track 82 formed on the optical disk 81, and the pattern shown in FIG. 10 is recorded in the crosstalk detection area 83. The first three recording marks 91,
Crosstalks from both sides (track n-1 and track n + 1) and the output of the own track n are detected by 92 and 93, and the next two sets of recording marks 941, 942 and 951, 952 have recording marks. If crosstalk is detected. Crosstalk from both sides (track n-1 and track n + 1) when there is a recording mark is detected by the last set of recording marks 961, 962, 963.

In these cases, the influence of the crosstalk is suppressed by controlling the coefficients a and b of the above-mentioned equation (1) by, for example, the zero focusing method or the least square error method so that the crosstalk is minimized. The reason why the crosstalk is measured even when there are recording marks other than the three recording marks 91, 92, and 93 is to realize stable crosstalk suppression even in a non-linear system.

Tracks n-1 to n + 5 continuous in FIG.
Examples of the above will be described. Here, three places where one recording mark is formed, three places where two marks are continuous, and one place where the marks are formed according to the track width method. I have. This can be realized by repeating the same pattern every three tracks. If this method is extended to three or more tracks, it can be easily realized.

[0063]

As described above, according to the optical information reproducing method of the first aspect of the present invention, the crosstalk diffracted light from the adjacent track and the reproduced light from the recording mark of the own track are detected separately. Therefore, crosstalk and noise can be suppressed, and recording marks on the information recording medium can be detected with high sensitivity.

According to the second aspect of the present invention, since the light dividing area corresponds to the diffracted light shape of the crosstalk from the adjacent track, the signal component to be reproduced and the crosstalk component are separated. By these calculations, it is possible to detect a finer recording mark signal.

According to the optical information reproducing apparatus of the third aspect, the crosstalk diffracted light from the adjacent track and the reproduced light from the recording mark of the own track are detected separately by the light splitting element. Crosstalk and noise can be suppressed, and recording marks on the information recording medium can be detected with high sensitivity.

According to the fourth aspect of the present invention, since the light division area is made to correspond to the diffracted light shape of the crosstalk from the adjacent track, the signal component to be reproduced and the crosstalk component are separated. By these calculations, it is possible to detect a finer recording mark signal.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a first reference example according to the present invention.

FIG. 2 illustrates a conventional example.

FIG. 3 is a diagram showing divided regions of a reproduction beam in a first reference example according to the present invention.

FIG. 4 is a diagram showing divided regions of a reproduction beam in a second reference example according to the present invention.

FIG. 5 is a diagram showing a divided area of a reproduction beam in a third reference example according to the present invention.

FIG. 6 is a configuration diagram showing a fourth reference example according to the present invention.

FIG. 7 is a configuration diagram showing a fifth reference example according to the present invention.

FIG. 8 is a configuration diagram showing a sixth reference example according to the present invention.

FIG. 9 is a configuration diagram showing an embodiment of the present invention.

FIG. 10 is a diagram showing an example of a recording mark for detecting crosstalk according to the present invention.

FIG. 11 is a diagram showing an example of a recording mark for detecting crosstalk according to the present invention.

[Description of Signs] 1 ... optical disk, 2 ... objective lens, 3 ... beam splitter, 4 ... beam splitting element, 44 ... splitting element mounting part, 5 ...
Beam shaping unit, 6 ... laser, 7, 8, 9 ... condenser lens,
10, 11, 12: detector, 13: arithmetic circuit, 21, 3
1, 41: first area, 22, 32, 42: second area, 23, 33, 43: third area, 45: modified beam splitter, 46: 1/2 wavelength plate, 53: condenser lens ,
54: substrate, 541 to 543: detector, 55: split element mounting part, 56: arithmetic circuit, 571, 572, 581, 5
82: mirror (beam splitting element), 71: beam splitter, 77: condenser lens, 78: arithmetic circuit, 79: substrate, 791-793 ... detector, 87: condenser lens, 89
... substrate, 891-893 ... detector, 81 ... optical disk,
82: track, 83: crosstalk detection area, 91,
92,93,941,942,951,952,96
1, 962, 963: Recording mark.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-36083 (JP, A) JP-A-1-224936 (JP, A) JP-A-62-267932 (JP, A) JP-A-2- 257474 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G11B ^7/ 00-7/013 G11B 11/105

Claims (4)

(57) [Claims] 1. An optical information reproducing method for reproducing information of a recording mark formed along a plurality of tracks on an information recording medium by using a light beam, wherein the recording mark is located on an adjacent track on the information recording medium. Existence
Crosstalk detection area consisting of multiple types of patterns
Provided, the light beam is irradiated to the crosstalk detection region, the track of the light returning from the crosstalk detection region
The light is divided spatially into three parts in the width direction of the laser beam, the divided lights are collected and detected by separate detectors, and the signals from the two areas other than the detected central area are respectively detected.
Multiply by the operation coefficient and subtract from the signal from the central area
Crosstalk in the output signal
The operation coefficient is determined to be the minimum for each of
And, thereafter, the light beam is irradiated onto the information recording medium, the light returning from the information recording medium is divided into three spatially in the width direction of the track, each condensing the divided light each of was detected in separate detectors, signals from the two regions other than the central region the detected
Multiply by the above calculation coefficient and subtract from the signal from the central area
An optical information reproducing method, wherein the information of the recording mark is reproduced by calculating . 2. The optical information reproducing method according to claim 1, wherein the divided area of the light corresponds to a diffracted light shape of crosstalk from an adjacent track. 3. An optical information reproducing apparatus for irradiating an information recording medium with a light beam to reproduce information of a recording mark formed along a plurality of tracks on the information recording medium, wherein the information recording medium returns from the information recording medium. a light dividing element that divides the light into spatially three in the width direction of the tracks, multiple detecting separately divided light by the light splitting element
The number of detecting means, provided with calculating means for calculating an output signal of said plurality of detection means, said computing means, light from the two regions other than the central region
Multiply each of the output signals of the detection means for detecting
The output signal of the detection means that detects light from the central area
The function of reproducing the information of the recording mark by subtracting
And, as the calculation coefficient, a recording mark
On the information recording medium consisting of a plurality of types of existing patterns
Light beam was irradiated to the provided crosstalk detection area
When the crosstalk in the output of the arithmetic means is
Determined to be the minimum for each of multiple types of patterns
An optical information reproducing apparatus characterized by using a calculated operation coefficient . 4. The optical information reproducing apparatus according to claim 3, wherein a light dividing area by the light dividing element is set in accordance with a shape of diffracted light of crosstalk from an adjacent track.