JPH08249664A - Data reproducing method and device using light beam - Google Patents

Abstract

(57) [Summary] [Object] To provide an optical recording / reproducing method capable of reproducing data recorded on an optical recording medium with high accuracy and high sensitivity. [Structure] The reflected light (reproduction beam) from the optical recording medium 1 is spatially divided into three in the track width direction, the three divided lights are respectively condensed and detected, and the three detected signals are calculated. Since the recorded data is reproduced by using the Fourier transform effect of the light lens, the influence of crosstalk and noise from the adjacent tracks can be suppressed, and the data on the optical recording medium 1 can be reproduced with high accuracy and high sensitivity. it can. Further, since the reproduction beam is divided into three, and these are condensed on the photodetectors 10, 11 and 12 by the condenser lenses 7, 8 and 9, it is possible to perform high-speed optical-electrical conversion and to transfer data. Higher speed can be realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data reproducing method and an apparatus for reproducing data recorded on an optical recording medium by using a light beam.

[0002]

2. Description of the Related Art Conventionally, as a method for reproducing data recorded on an optical recording medium, as shown in JP-A-1-245433, the light of a semiconductor laser is used on an optical recording medium by using an optical system. The irradiation is performed by narrowing down the irradiation to one point, collecting the reflected light from the optical system by the optical system and guiding it to the photodetector, and capturing the change in the intensity and polarization direction of the reflected light on the photodetector to reproduce the recorded data. Are known.

High-Density Land / Groove Recordi
ng for Digital Video File System (Jpn. J. Appl. Phys. 32 (1993) 5449-5450) A technique of suppressing crosstalk using a beam is known. Specifically, a main signal and two sub-signals obtained by the three light beam spots are input to a crosstalk cancel circuit to remove crosstalk and obtain a reproduced signal.

[0004]

As described above, when the reflected light from the optical recording medium is detected by one photodetector, the influence of crosstalk from adjacent tracks cannot be suppressed. In addition, a method of using three light beams to suppress the influence of crosstalk has been proposed, but it is expensive because three lasers are used to generate three light beams, and the characteristics are high. There is a problem that a uniform light beam is required and a complicated reproducing system for compensating for the positional deviation of the reproduced signal due to the spot spacing of these light beams is required.

The present invention has been made in view of the above problems, and an object thereof is a data reproducing method using a light beam capable of reproducing data recorded on an optical recording medium with high accuracy and high sensitivity. And to provide an apparatus suitable for carrying out this method.

[0006]

To achieve the above object, the invention of claim 1 is a data reproducing method for reproducing data recorded on an optical recording medium by using a light beam. A light beam onto the optical recording medium, and the reflected light from the optical recording medium is spatially divided into three in the track width direction,
Each of the three divided lights is condensed and detected, and the detected three signals are calculated to reproduce the recorded data.

According to a second aspect of the present invention, in the data reproducing method according to the first aspect, the division boundary line of the reflected light is parallel to the track direction.

According to a third aspect of the present invention, in a data reproducing method for reproducing data recorded on an optical recording medium by using a light beam, the optical beam is irradiated onto the optical recording medium, and the data from the optical recording medium is emitted. The reflected light is spatially divided into five in the track width direction and the track direction, the five divided lights are condensed and detected, and the detected five signals are calculated to reproduce the recorded data. It has a feature.

According to a fourth aspect of the present invention, in the data reproducing method according to any one of the first to third aspects, each detected signal is weighted, and the sum of the weighted signals is a reproduced signal. The feature is that

According to a fifth aspect of the invention, in the data reproducing method according to the fourth aspect, a coefficient for weighting each detected signal is obtained by previously reproducing known data on the optical recording medium. It is characterized in that it is determined based on the relationship between the reproduced signal and crosstalk.

According to a sixth aspect of the present invention, in the data reproducing method according to any one of the first to fifth aspects, the central division width in the division area is changed within the range of the light beam diameter, and the reproduction signal is reproduced for each division width. The feature is that the SN ratio is obtained and the division width is determined so that the SN ratio becomes the best.

According to a seventh aspect of the present invention, in a data reproducing apparatus for irradiating a light beam onto an optical recording medium to reproduce the data recorded on the optical recording medium, at least the reflected light from the optical recording medium is tracked. Spatially divided into n (n
Is a positive integer of 2 or more), n light condensing means for condensing the light divided into n by the light dividing means, and each of the n light converging light is detected. It is characterized by comprising n photodetector means and arithmetic means for computing signals from the n photodetector means and outputting a reproduction signal.

According to an eighth aspect of the invention, in a data reproducing apparatus for irradiating an optical recording medium with a light beam to reproduce data recorded on the optical recording medium, at least the reflected light from the optical recording medium is tracked. Spatially divided into n in the width direction (n
Is a positive integer greater than or equal to 2), and at the same time, the light dividing and condensing means for condensing these divided lights on the same plane and the n detecting parts on the same plane are divided and condensed by the light dividing and condensing means. And a light detecting means for detecting n light respectively by n detecting portions, and a calculating means for calculating n signals from the light detecting means and outputting a reproduction signal. There is.

[0014]

In the data reproducing method according to the first aspect of the present invention, the reflected light from the optical recording medium is spatially divided into three in the track width direction, and the three divided lights are respectively collected and detected. The data recorded on the optical recording medium is reproduced by calculating the three signals. In other words, the reflected light from the optical recording medium is divided into the central part of the light, which is greatly affected by the crosstalk from the adjacent tracks, and the both side parts, which are less affected, and is divided into a signal from the central part and a signal from both sides. Calculation is performed based on the above.

In the data reproducing method according to the second aspect of the present invention, the reflected light from the optical recording medium is divided into three with a division boundary line parallel to the track direction. Other functions are similar to those of the invention of claim 1.

In the data reproducing method according to the third aspect of the present invention, the reflected light from the optical recording medium is spatially divided into 5 in the track width direction and the track direction, and the 5 divided lights are respectively condensed and detected, The data recorded on the optical recording medium is reproduced by calculating the five detected signals.

In the data reproducing method according to the fourth aspect of the present invention, the detected signals are weighted, and the sum of the weighted signals becomes the reproduced signal. Other functions are similar to those of the first to third inventions.

In the data reproducing method according to the fifth aspect of the present invention, the coefficient for weighting each detected signal is:
It is determined based on the relationship with the crosstalk of the reproduction signal obtained by previously reproducing the known data on the optical recording medium. Other functions are similar to those of the invention of claim 4.

In the data reproducing method according to the present invention, the central division width in the division area is changed within the range of the light beam diameter, the SN ratio of the reproduction signal is obtained for each division width, and the SN ratio is the best. The division width is determined so that Other functions are similar to those of the first to fifth inventions.

In the data reproducing apparatus according to the seventh aspect of the present invention, the reflected light from the optical recording medium is spatially divided into at least the track width direction by the light dividing means (n is a positive integer of 2 or more), and is divided into n. The collected light is condensed by the n condensing means. The n condensed lights are detected by the n photodetectors, the signals from the n photodetectors are calculated by the calculator, and the reproduction signal is output.

In the optical recording / reproducing apparatus according to the invention of claim 8, the reflected light from the optical recording medium is spatially divided into n (n is a positive integer of 2 or more) at least in the track width direction by the light dividing and converging element. At the same time, these split lights are condensed on the same plane. The n condensed lights are detected by each of the n detectors located on the same plane of the photodetector, and the n signals from the photodetector are calculated by the calculator to output a reproduction signal.

[0022]

【Example】

[First Embodiment] A first embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a block diagram of an optical recording / reproducing apparatus. In FIG. 1, 1 is an optical recording medium such as an optical disk, 2 is an objective lens, 3 is a beam splitter, 4 is a splitting element mounting portion,
4a is a beam splitter, 5 is a beam shaping unit, 6 is a laser, 7 is a first condenser lens, 8 is a second condenser lens, and 9 is a condenser lens.
Is a third condenser lens, 10 is a first photodetector, 11 is a second photodetector, 12 is a third photodetector, and 13 is an arithmetic circuit.

The light beam emitted from the laser 6 is shaped into parallel light by the beam shaping unit 5. This parallel light beam is applied to the objective lens 2 via the beam splitter 3, and is focused on the optical recording medium 1 by the objective lens 2. Light reflected from the optical recording medium 1 (reproduction beam)
Of which the polarization direction is changed by the beam splitter 3 toward the beam splitting element 4a of the splitting element mounting portion 4.
To change the polarization direction of the reproduction beam, the known 1/4
A wave plate may be inserted or PBS may be used.

The beam splitting element 4a is composed of a streamlined mirror surrounded by two curves of the same curvature on the upper surface as shown in FIG. 2 (b), and inclined by 45 degrees on the side surface as shown in FIG. 2 (a). Are incorporated in the split element mounting portion 4.
FIG. 3 shows a division area of the reproduction beam by the beam division element 4a. The reproduction beam has a curved division boundary line in the beam traveling direction on the optical recording medium 1 according to the shape of the beam division element 4a. It is spatially divided into three parts in the track width direction into a first area 21, a second area 22, and a third area 23.

The first region 2 of the divided reproduction beam
The first light is emitted from the first light detector 1 by the first condenser lens 7.
The light of the third region 23 is condensed to 0 and is condensed to the second photodetector 11 by the second condenser lens 8. The light in the second region 22 is reflected by the beam splitting element 4a in the right angle direction in the illustrated example, and then is condensed by the third condenser lens 9 on the third photodetector 12. Each photodetector 1
The outputs of 0, 11, and 12 are guided to the arithmetic circuit 13 and operated as follows.

That is, the output of the first photodetector 10 is V1,
The output of the second photodetector 11 is V2, and the output of the third photodetector 12 is
The output (reproduction signal) O of the arithmetic circuit 13 is expressed by the following equation, where V3 is the output of O = aV1 + bV2 + cV3 (Equation 1) where a, b, and c are weighting coefficients for the three outputs V1, V2, and V3, respectively. These weighting factors a, b, and c depend on the size of the beam splitting area and the recording mark pattern of the optical recording medium 1 shown in FIG. 3, and influences other than the noise and the signal component of the recording mark are minimized. Is set to.

That is, in the above-mentioned reproducing system, the optical recording medium 1
The leak signal from the recording mark on the adjacent track above,
The intensity distribution of the parallel beam, which is the Fourier transform plane on the optical recording medium 1, appears differently in each region. Therefore, by setting the weighting coefficient b for the signals of the second area 22 including many leak signals to be smaller than the weighting coefficients a and c for the signals of the areas 21 and 23 on both sides, crosstalk from the adjacent tracks can be achieved. Can suppress the influence of. Further, this makes it possible to compensate the aberration in the track width direction and suppress the influence of off-track.

If the noise is assumed to be random and appears uniformly in each of the regions 21, 22, 23, the first
Signals of the area 21 and the third area 23 of the second area 22
The effect of noise can be canceled by subtracting with the signal of.

The focus signal and tracking signal necessary for actual signal detection are detected by the light separated by a beam splitter (not shown), but since this is a well-known method, the description thereof is omitted here.

According to this embodiment, the effect of crosstalk and noise from adjacent tracks can be suppressed by utilizing the Fourier transform effect of the light lens, and the data on the optical recording medium 1 can be accurately and highly sensitively. Can be played. Further, after dividing the reproduction beam into three, these are condensed on the photodetectors 10, 11, and 12 by the condenser lenses 7, 8, and 9.
High-speed optical-electrical conversion is possible, and high-speed data transfer can be realized.

Further, since the reproduction beam is spatially divided into three in the track width direction, the aberration in the track width direction can be compensated by adjusting the weighting coefficient for the signals in the left and right regions 21 and 23. In addition, the division boundary line of the reproduction beam separates each of the regions where the ± 1st-order diffracted light and the 0th-order diffracted light overlap, into two regions, thereby further reducing the influence of crosstalk from the adjacent track and further, The signal can also be compensated.

Furthermore, since the tracking error signal is obtained from the difference between the signals obtained by separately detecting the lights from one set of regions 21 and 22 which are symmetrical in the track width direction among the three divided lights, the tracking error signal is obtained. The optical system for obtaining the error signal can be omitted.

[Second Embodiment] A second embodiment of the present invention will be described below with reference to FIGS. 4 and 5. The difference between this embodiment and the first embodiment is the configuration of the beam splitter. The other structure of this embodiment is similar to that of the first embodiment, and therefore the description thereof will be omitted with reference to FIG.

The beam splitting element 14a is composed of a rectangular mirror on the upper surface as shown in FIG. 4 (b), and is incorporated in the splitting element mounting portion 14 with a side surface inclined by 45 degrees as shown in FIG. 4 (a). There is. FIG. 5 shows a reproduction beam division area by the beam division element 14a.
The reproduction beam has a division boundary line parallel to the track direction according to the shape of the beam division element 14a with respect to the beam traveling direction on the optical recording medium 1, and has a first region 31, a second region 32, and a second region 32 in the track width direction. It is spatially divided into three areas 33.

According to the present embodiment, since the division boundary line of the reproducing beam is parallel to the track direction, the change in signal amplitude is small with respect to off-track and off-focus, which is advantageous for off-track and off-focus. is there. Further, the beam splitting element 14a does not require complicated processing and can be easily manufactured. Other operational effects of this embodiment are similar to those of the first embodiment.

[Third Embodiment] A third embodiment of the present invention will be described below with reference to FIGS. 6 and 7. The difference between this embodiment and the first and second embodiments lies in the method of determining each weighting coefficient in the arithmetic circuit. Since the other structure of this embodiment is similar to that of the first and second embodiments, FIG.
The description thereof will be omitted with reference to FIG.

Here, a method of determining the value of α when the weighting coefficient in Equation 1 is b = α and a = c = 1 will be described.

As shown in FIG. 6, the light beam spot 42 irradiated on the target track 41a and the target track 41 are shown.
There are four patterns A, B, C and D in the recording mark M on the track a and the tracks 41b and 41c on both sides thereof.

FIG. 7 shows the results of examining the relationship between the crosstalk of the reproduction signal output from the arithmetic circuit 13 and the weighting coefficient α for these four patterns. The crosstalk characteristics differ depending on each recording mark pattern, but here, only the maximum crosstalk is extracted (the thick line portion in the figure), and the coefficient value at which the crosstalk becomes the smallest is set as the optimum weighting coefficient α.

According to the present embodiment, only the maximum crosstalk in each recording mark pattern is extracted and the value at which the crosstalk value becomes the minimum is set as the optimum weighting coefficient α, so the crosstalk is reduced most. Therefore, the weighting coefficient with which good signal quality is obtained can be accurately determined. Other operational effects of this embodiment are similar to those of the first and second embodiments.

[Fourth Embodiment] The fourth embodiment of the present invention will be described below with reference to FIG. The difference between this embodiment and the first to third embodiments is the method of determining the division width in the beam division area. Since the other structure of the present embodiment is similar to that of the first to third embodiments, the description thereof will be omitted with reference to FIGS. 1 to 7.

First, the central division width W (see FIG. 3) in the three divided areas is changed within the range of the light beam diameter, and each division width W is determined in the same manner as in the third embodiment. The crosstalk of the reproduction signal obtained from the arithmetic circuit 13 is obtained according to the weighting coefficient. Similarly, for each division width W, the amplitude of the reproduction signal obtained from the arithmetic operation circuit 13 is obtained according to the weighting coefficient determined as in the third embodiment.

FIG. 8 shows the relationship between the division width (%) thus obtained and the crosstalk and the signal amplitude. The signal amplitude here is the one when no division is performed and is standardized. As can be seen from the figure, the crosstalk decreases as the division width increases, but the signal amplitude also decreases accordingly.

Since the crosstalk is preferably -26 dB or less and the signal amplitude is preferably 0.6 or more, the division width W is 2
A range in which the two conditions are satisfied (a range sandwiched by broken lines in FIG. 8) is a good example.

According to the present embodiment, the central division width W in the three divided areas is changed within the range of the light beam diameter, and the respective division widths W are set to the weighting coefficients determined in the same manner as in the third embodiment. Similarly, the SN ratio of the reproduced signal obtained from the arithmetic circuit 13 is obtained, and the division width is determined so that the SN ratio is the best. Therefore, the optimum division width can be accurately determined, and good signal quality can be obtained. can get. Other operational effects of this embodiment are the same as those of the first to third embodiments.

[Fifth Embodiment] A fifth embodiment of the present invention will be described below with reference to FIGS.

FIG. 9 is a block diagram of an optical recording / reproducing apparatus. In FIG. 9, 51 is an optical recording medium such as an optical disk, 52 is an objective lens, 53 is a beam splitter, 54 is a splitting element mounting portion, and 55 is beam shaping. Part, 56 is a laser, 57 is a first condenser lens, 58 is a second condenser lens, and 59 is a third condenser lens.
Condenser lens, 60 is a fourth condenser lens, 61 is a fifth condenser lens, 62 is a first photodetector, 63 is a second photodetector, 64 is a third photodetector, 65 is a fourth photodetector,
Reference numeral 66 is a fifth photodetector, and 67 is an arithmetic circuit.

The focus signal and tracking signal required for actual signal detection are detected by the light separated by a beam splitter (not shown), but this is omitted because a known method may be used.

The light beam emitted from the laser 56 is shaped into parallel light by the beam shaping section 55. The parallel light beam is applied to the objective lens 52 via the beam splitter 53, and is focused on the optical recording medium 51 by the objective lens 52. The polarization direction of the reflected light (reproduction beam) from the optical recording medium 51 is changed by the beam splitter 53, and the beam splitting element 5 of the splitting element mounting portion 54.
4a (see FIG. 10). To change the polarization direction of the reproduction beam, insert a well-known quarter wave plate or PB.
You may use S etc.

The beam splitting element 54a is shown in FIG.
As shown in the side surface and the upper surface in (b), four isosceles triangular mirrors each having a 1/4 circular cutout at the apex are attached to each other.
The two notches are combined so that a circular hole is formed in the central part, and each mirror is inclined by 45 degrees toward the central hole. It is incorporated in the split element mounting portion 54 so that the direction can be changed by the mirror effect. Figure 11
Indicates a divided area of the reproducing beam by the beam dividing element 54a, and the reproducing beam has a circular and radial dividing boundary line according to the shape of the beam dividing element 54a with respect to the beam traveling direction on the optical recording medium 51. It is spatially divided into five regions in the width direction and the track direction into a first region 71, a second region 72, a third region 73, a fourth region 74 and a fifth region 75.

The first area 7 of the divided reproduction beam
The light of No. 1 is condensed on the first photodetector 62 by the first condenser lens 57, and the light of the second region 72 is condensed on the second photodetector 63 by the second condenser lens 58. The light in the third region 73 is condensed by the third condenser lens 59 on the third photodetector 64, and the light in the fourth region 74 is condensed by the first condenser lens 60 into the fourth light. Focused on the detector 65,
The light in the fifth region 75 is condensed by the fifth condenser lens 61 on the fifth photodetector 66. Each photodetector 62, 6
The outputs of 3, 64, 65 and 66 are guided to the arithmetic circuit 67 and operated as follows.

That is, the output of the first photodetector 62 is V1,
The output of the second photodetector 63 is V2, and the output of the third photodetector 64 is
Output of V3, the output of the fourth photodetector 65 is V4,
If the output of the photodetector 66 is V5, the output (reproduction signal) O of the arithmetic circuit 67 is expressed by the following equation. O = aV1 + bV2 + cV3 + dV4 + eV5 (Equation 2) where a, b, c, d, and e are five outputs V1, V2,
It is a weighting coefficient for each of V3, V4, and V5.
These weighting factors a, b, c, d and e depend on the size of the beam splitting area and the recording mark pattern of the optical recording medium 51 shown in FIG. 11, and noise and noise are generated as in the first embodiment. The influences other than the signal component of the recording mark are set to be the smallest.

That is, in the reproducing system described above, the optical recording medium 5
Signals leaking from the recording marks of the adjacent tracks on the optical recording medium 51 are the first region 71 and the third region 7 especially as the intensity distribution of the parallel beam which is the Fourier transform surface on the optical recording medium 51.
It appears differently in the third and fifth regions 75. Therefore, by setting the weighting coefficient a for the signal in the first area 71 containing many leak signals to be smaller than the weighting coefficients c, e for the signals in the areas 73 and 75 on both sides, the crosstalk from the adjacent track is obtained. Can suppress the influence of.

The signal from the recording mark on the optical recording medium 51 is mainly used as the intensity distribution of the parallel beam which is the Fourier transform surface on the optical recording medium 51, and is mainly distributed to the first area 71, the second area 72 and the second area 72. 4 area 74. Therefore, by making the weighting factors b and d for the signals of the second region 72 and the fourth region 74 larger than the weighting factors a for the signals of the first region 71, the reproduction signal of the small recording mark is emphasized. And can be played back.

According to the present embodiment, since the reproduction beam is spatially divided into five in the track width direction and the track direction, the weighting coefficient for the signals of the two regions 73 and 75 in the track width direction is adjusted. Aberrations in the track width direction can be compensated, and two areas 7 in the track direction can be used.
Aberrations in the track direction can be compensated by adjusting the weighting factors for the 2,74 signals. Therefore, it is possible to suppress the influence of tracking and efficiently detect a signal from a minute recording mark. Other operational effects of this embodiment are similar to those of the first embodiment.

The method shown in the third embodiment can be used to determine the weighting coefficient in this embodiment, and the fourth embodiment can be used to determine the center division width in the divided area. The method can be adopted.

[Sixth Embodiment] Hereinafter, FIGS. 12 to 14 will be described.
A sixth embodiment of the present invention will be described with reference to FIG. The difference between the present embodiment and the first embodiment is that the reproduction beam is divided into three by the converging light condensing element, and at the same time, these are focused on the three light receiving portions of the single photodetector. Since the other structure of this embodiment is similar to that of the first embodiment, FIG.
And omit the explanation.

The split condensing element 81 is shown in FIGS. 13 (a) and 13 (b).
As shown in the side view and the top surface, each has a different lens curved surface corresponding to the three divided regions similar to FIG. 3, and each lens curved surface divides the reproduction beam into three, and at the same time, the respective light beams are on the same plane. Can be focused at different positions.

As shown in FIG. 14, the photodetector 82 has three light receiving portions 82a, 82b and 82c on one flat surface, and these light receiving portions serve as three photodetectors. In the first, second, and third light receiving portions 82a, 82b, and 82c of the photodetector 82, the split condensing element 8 is provided.
The light divided into three by 1 is condensed respectively.

According to this embodiment, since the reproducing beam can be split and condensed by the split condensing element 81, the light condensing system can be simplified, and the light receiving parts can be arranged in the same plane, thus saving space and space. Cost reduction can be achieved. Other operational effects of this embodiment are similar to those of the first embodiment.

The split light condensing element is shown in FIG.
You may use what is shown to (b). This split condensing element 9
Reference numeral 1 has different lens curved surfaces corresponding to the three divided regions similar to FIG. 5, and each lens curved surface divides the reproduction beam into three and at the same time condenses each light at different positions on the same plane. it can.

[Seventh Embodiment] Hereinafter, FIG. 16 to FIG.
The seventh embodiment of the present invention will be described with reference to FIG. The difference between this embodiment and the fifth embodiment is that the reproducing beam is divided into five by the dividing and converging element and at the same time, these are condensed on the five light receiving portions of one photodetector. Since the other device configuration of the present embodiment is similar to that of the fifth embodiment, the description thereof will be omitted with reference to FIG.

The split condensing element 101 is shown in FIG.
As shown in the side surface and the upper surface in (b), different lens curved surfaces are provided corresponding to the divided regions similar to FIG. 11, and the reproduction beam is divided into five by each lens curved surface, and at the same time, the respective light beams are made the same. It can focus on different positions on the plane.

The photodetector 102, as shown in FIG.
Five light receiving portions 102a, 102b, 102 on a flat surface
c, 102d, and 102e, and these light receiving portions serve as five photodetectors. The first to fifth light receiving portions 102a to 102e of the photodetector 102
In this case, the light beams divided into five by the divided light condensing element 101 are condensed respectively.

According to this embodiment, since the reproducing beam can be divided and condensed by the divided condensing element 101, the light condensing system can be simplified, and the light receiving parts can be arranged in the same plane, thus saving space. And cost reduction can be achieved. Other operational effects of this embodiment are similar to those of the fifth embodiment.

[0067]

As described above in detail, according to the data reproducing method of the first aspect of the present invention, it is possible to suppress the influence of crosstalk and noise from the adjacent tracks by utilizing the Fourier transform action of the light lens. The data on the optical recording medium can be reproduced with high accuracy and high sensitivity. Further, since the reflected light from the optical recording medium is divided into three and then these are condensed and detected, high-speed optical-electrical conversion is made possible and high-speed data transfer can be realized. Furthermore, since the reflected light from the optical recording medium is spatially divided into three in the track width direction,
Aberrations in the track width direction can be compensated by calculating signals in the left and right regions.

According to the data reproducing method of the second aspect of the present invention, since the division boundary line of the reflected light is parallel to the track direction, the change in the signal amplitude is small with respect to off-track and off-focus, and the off-track and off-focus are reduced. It is advantageous for focus. The other effects are the same as those of the invention of claim 1.

According to the data reproducing method of the third aspect of the present invention, the reflected light from the optical recording medium is spatially divided into 5 in the track width direction and the track direction. Can be compensated for the aberration in the track width direction, and the aberration in the track direction can be compensated for by computing the signals of the two regions in the track direction. Therefore, it is possible to suppress the influence of tracking and efficiently detect a signal from a minute recording mark. The other effects are the same as those of the invention of claim 1.

According to the data reproducing method of the fourth aspect of the present invention, optimum weighting can be performed on each of the three detected signals, crosstalk can be most reduced, and good signal quality can be obtained. Other effects are the same as those of the inventions of claims 1 to 3.

According to the data reproducing method of the fifth aspect of the present invention, it is possible to accurately determine the weighting coefficient that can reduce crosstalk most and obtain good signal quality. The other effects are similar to those of the invention of claim 4.

According to the data reproducing method of the sixth aspect of the present invention, the reflected light from the optical recording medium can be divided with an optimum center division width, whereby good signal quality can be obtained.
Other effects are the same as those of the inventions of claims 1 to 5.

According to the data reproducing apparatus of the seventh aspect, the data reproducing methods of the first to sixth aspects can be suitably implemented.

According to the data reproducing apparatus of the eighth aspect of the present invention, the reflected light from the optical recording medium can be simultaneously divided and condensed by one split condensing means, and these lights can be detected by one photodetector. The light condensing system can be simplified, and space saving and cost reduction can be realized. Other effects are similar to those of the invention of claim 7.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an optical recording / reproducing apparatus according to a first embodiment of the present invention.

FIG. 2 is a side view and a top view of the beam splitter according to the first embodiment of the present invention.

FIG. 3 is a diagram showing divided areas of a reproduction beam according to the first embodiment of the present invention.

FIG. 4 is a side view and a top view of a beam splitter according to a second embodiment of the present invention.

FIG. 5 is a diagram showing divided areas of a reproduction beam according to a second embodiment of the present invention.

FIG. 6 is a diagram showing a relationship between a light beam spot and a recording mark according to a third embodiment of the present invention.

FIG. 7 is a diagram showing a relationship between a weighting coefficient and crosstalk according to the third embodiment of the present invention.

FIG. 8 is a diagram showing the relationship between the division width, crosstalk, and signal amplitude according to the fourth embodiment of the present invention.

FIG. 9 is a configuration diagram of an optical recording / reproducing apparatus according to a fifth embodiment of the present invention.

FIG. 10 is a side view and a top view of a beam splitter according to a fifth embodiment of the present invention.

FIG. 11 is a diagram showing divided areas of a reproduction beam according to a fifth embodiment of the present invention.

FIG. 12 is a configuration diagram of an optical recording / reproducing device according to a sixth embodiment of the present invention.

FIG. 13 is a side view and a top view of a split light collecting element according to a sixth embodiment of the present invention.

FIG. 14 is a perspective view of a photodetector according to a sixth embodiment of the present invention.

FIG. 15 is a side view and a top view of a split light collecting element according to a sixth embodiment of the present invention.

FIG. 16 is a configuration diagram of an optical recording / reproducing apparatus according to a seventh embodiment of the present invention.

FIG. 17 is a side view and a top view of a split light collecting element according to a seventh embodiment of the present invention.

FIG. 18 is a perspective view of a photodetector according to a seventh embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Optical recording medium, 2 ... Objective lens, 3 ... Beam splitter, 4 ... Splitting element mounting part, 4a ... Beam splitting element, 5 ...
Beam shaping section, 6 ... Laser, 7 ... First condenser lens, 8
2nd condensing lens, 9 ... 3rd condensing lens, 10 ... 1st photodetector, 11 ... 2nd photodetector, 12 ... 3rd photodetector, 13 ... Arithmetic circuit, 21 ... first area, 22 ... second area, 23 ... third area, 14 ... dividing element mounting portion,
14a ... Beam splitting element, 31 ... First area, 32 ... Second area, 33 ... Third area, W ... Dividing width, 41a-4
1c ... track, 42 ... light beam spot, M ... recording mark, 51 ... optical recording medium, 52 ... objective lens, 53 ... beam splitter, 54 ... splitting element mounting section, 54a ... beam splitting element, 55 ... beam shaping section, 56 ... Laser, 57
... first condensing lens, 58 ... second condensing lens, 59 ...
3rd condensing lens, 60 ... 4th condensing lens, 61 ... 5th condensing lens, 62 ... 1st photodetector, 63 ... 2nd photodetector, 64 ... 3rd photodetection , 65 ... Fourth photodetector, 66 ... Fifth photodetector, 67 ... Arithmetic circuit, 71 ... First area, 72 ... Second area, 73 ... Third area, 74
... fourth region, 75 ... fifth region, 81 ... split condensing element, 82 ... photodetector, 82a ... first light receiving portion, 82b ...
2nd light receiving part, 82c ... 3rd light receiving part, 91 ... Divided condensing element, 101 ... Divided condensing element, 102 ... Photodetector, 10
2a ... 1st light receiving part, 102b ... 2nd light receiving part, 102
c ... third light receiving portion, 102d ... fourth light receiving portion, 102e
... Fifth light receiving portion.

Claims (8)

[Claims] 1. A data reproducing method for reproducing data recorded on an optical recording medium by using a light beam, comprising irradiating a light beam on the optical recording medium, and reflecting light from the optical recording medium with a track width. A light beam characterized in that it is spatially divided into three parts in the direction, each of the three divided lights is collected and detected, and the detected three signals are calculated to reproduce the recorded data. Data playback method. 2. The data reproducing method using a light beam according to claim 1, wherein the division boundary line of the reflected light is parallel to the track direction. 3. A data reproducing method for reproducing data recorded on an optical recording medium by using a light beam, wherein a light beam is irradiated onto the optical recording medium, and reflected light from the optical recording medium is track width. A light beam characterized by spatially dividing into five directions and a track direction, condensing and detecting each of the five divided lights, computing the detected five signals, and reproducing the recorded data. A data reproduction method using. 4. The light beam according to claim 1, wherein each of the detected signals is weighted, and the sum of the weighted signals is used as a reproduced signal. The data reproduction method used. 5. A coefficient for weighting each detected signal is determined based on a relationship with a crosstalk of a reproduction signal obtained by previously reproducing known data on an optical recording medium. The data reproducing method using a light beam according to claim 4. 6. The center division width in the division area is changed within the range of the light beam diameter, the SN ratio of the reproduction signal is obtained for each division width, and the division width is determined so that the SN ratio becomes the best. 6. A data reproducing method using a light beam according to claim 1, wherein 7. A data reproducing apparatus for reproducing a data recorded on an optical recording medium by irradiating a light beam onto the optical recording medium, wherein reflected light from the optical recording medium is spatially distributed at least in a track width direction. Light splitting means for splitting into n (n is a positive integer of 2 or more), and n for collecting the light split into n by the light splitting means.
A plurality of light collecting means, n light detecting means for detecting each of the n collected light, and calculating means for calculating a signal from the n light detecting means and outputting a reproduction signal. A data reproducing apparatus using a light beam, comprising: 8. A data reproducing apparatus for reproducing a data recorded on an optical recording medium by irradiating a light beam on the optical recording medium, wherein reflected light from the optical recording medium is spatially distributed at least in a track width direction. And (n is a positive integer of 2 or more) at the same time, and at the same time, the light splitting and condensing means for condensing the respective divided lights on the same plane, and the light splitting and condensing means having n detectors on the same plane. The photodetector means detects each of the n lights divided and condensed by the n detectors, and the arithmetic means for calculating the n signals from the photodetector means and outputting the reproduction signal. A data reproducing device using a light beam characterized by the following.