JP2004111002A - Device and method for reproducing information - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To cancel crosstalk of a main beam by using a subbeam whose light intensity is weaker in reproducing multi-valued information than in recording the information. <P>SOLUTION: A plurality of beams each composed of the main beam and the subbeam are relatively moved on an information recording medium 5 with the multi-valued information recorded thereon. The main beam is emitted onto a track to be reproduced on the information recording medium 5, and the subbeam is emitted onto a track adjacent to the track with the main beam emitted thereto. An analog circuit 12 makes the number of levels for quantizing reflection light and transmission light of the subbeam smaller than the number of levels for quantizing reflection light and transmission light of the main beam, and the reflection light and the transmission light of the subbeam are used to cancel crosstalk to the reflection light and the transmission light of the main beam. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an information reproducing apparatus for canceling crosstalk from an adjacent track when reproducing multivalued information recorded on an information recording medium having a plurality of track-shaped recording areas, and an information reproducing method thereof.
[0002]
[Prior art]
When the recording density of the information recording medium is improved, the data wraparound from adjacent tracks, so-called crosstalk, increases, and the information cannot be correctly reproduced.
Therefore, conventionally, there has been an information reproducing apparatus as described below which performs crosstalk cancellation using a DPP method as a tracking method.
[0003]
By changing the size of a recording mark to two or more types in correspondence with multi-value data by irradiating a laser beam on a predetermined grid point of an optical information recording medium, recording and reproducing the grid point, An area for detecting the amount of leakage of information from the nearest two-dimensional lattice point is provided on the recording medium, and a group of marks is recorded on the lattice points in the area. Based on the detection value obtained by scanning at the spot, the amount of crosstalk from adjacent tracks and the amount of intersymbol interference between adjacent lattice points are learned, and the adjacent information is reproduced using signal processing during information reproduction. An information reproducing apparatus that reduces crosstalk from a track to be reproduced and further reduces intersymbol interference on a target track, thereby reducing leakage of information from two-dimensionally adjacent lattice points (for example, see Patent Document 1) 1).
[0004]
According to such an information reproducing apparatus, it is possible to irradiate the main beam and the sub beam at the same level (light intensity), reproduce the information of the adjacent track using the sub beam, and cancel the crosstalk from the value of the adjacent track. .
[0005]
[Patent Document 1]
JP-A-8-124167
[0006]
[Problems to be solved by the invention]
However, in the conventional information reproducing apparatus, when the main beam and the sub-beam are irradiated at different levels (light intensity), for example, the size of the spot on the recording medium is different in the information recording / reproducing apparatus which performs recording, and the reproducing condition is changed. There is a problem that crosstalk occurs.
Usually, in order to divide the light into three beams, the light emission of one LD is divided. In this case, if the conditions of the three beams are the same, the same data is recorded over three tracks.
[0007]
That is, in consideration of recording, the main beam needs higher power than the power required for recording, while the sub beam must be lower than the power at which no recording occurs. The intensity of the sub beam needs to be about 1/10 of the intensity of the main beam. Therefore, the size of the spot on the medium is different, and the reproduction condition is changed.
[0008]
SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and has as its object to cancel crosstalk of a main beam by using a sub-beam whose light intensity is lower than that at the time of recording when reproducing multi-valued information.
[0009]
[Means for Solving the Problems]
The present invention provides the following (1) to (5) information reproducing apparatuses to achieve the above object.
(1) A plurality of beams composed of a main beam and a sub beam are relatively moved on an information recording medium on which multi-valued information is recorded, and the main beam is irradiated on a track to be reproduced on the information recording medium, and the sub beam is The main beam is irradiated on a track adjacent to the irradiated track, and the reflected light or transmitted light of the sub beam is used to cancel crosstalk with respect to the reflected light or transmitted light of the main beam, and the reflection of the main beam and the sub beam is performed. In an information reproducing apparatus that reproduces multi-valued information recorded on the information recording medium using light or transmitted light, the number of levels for quantizing the reflected light or transmitted light of the sub-beam is determined by the reflected light of the main beam or An information reproducing apparatus provided with means for reducing the number of levels at which transmitted light is quantized.
[0010]
(2) In the information reproducing apparatus of (1), the predetermined value calculated based on the quantization result of the sub-beam is delayed by the number of clocks corresponding to the delay time of the plurality of beams, and the predetermined value is added to the quantization result of the main beam. An information reproducing apparatus comprising means for adding and canceling crosstalk with respect to reflected light or transmitted light of the main beam.
(3) In the information reproducing apparatus of (1), the predetermined value calculated based on the quantization result of the sub-beam is delayed by the number of clocks corresponding to the delay time of the plurality of beams, and An information reproducing apparatus comprising means for adding and canceling crosstalk with respect to reflected light or transmitted light of the main beam.
[0011]
(4) A plurality of beams composed of a main beam and a sub beam are relatively moved on an information recording medium on which multi-valued information is recorded, and the main beam is irradiated on a track to be reproduced on the information recording medium, and the sub beam is irradiated. The main beam is irradiated on a track adjacent to the irradiated track, and the reflected light or transmitted light of the sub beam is used to cancel crosstalk with respect to the reflected light or transmitted light of the main beam, and the reflection of the main beam and the sub beam is performed. In an information reproducing apparatus for reproducing multi-valued information recorded on the information recording medium by using light or transmitted light, based on a clock signal in which reflected light or transmitted light of the sub beam is synchronized with a reproduced signal of the main beam. And quantizes the main beam based on the average value of a plurality of continuous quantized levels. Information reproducing apparatus provided with means for canceling the crosstalk with respect to the light or transmitted light.
(5) The information reproducing apparatus according to (4), wherein the continuous plural quantization levels are three in total before and after the signal to be canceled.
[0012]
Further, the following (6) to (10) information reproducing methods are also provided.
(6) A plurality of beams including a main beam and a sub beam are relatively moved on an information recording medium on which multi-valued information is recorded, and the main beam is irradiated on a track to be reproduced on the information recording medium, and the sub beam is The main beam is irradiated on a track adjacent to the irradiated track, and the reflected light or transmitted light of the sub beam is used to cancel crosstalk with respect to the reflected light or transmitted light of the main beam, and the reflection of the main beam and the sub beam is performed. In an information reproducing method for reproducing multi-valued information recorded on the information recording medium using light or transmitted light, the number of levels for quantizing the reflected light or transmitted light of the sub-beam is determined by the reflected light of the main beam or An information reproducing method in which the transmitted light is quantized less than the number of levels.
[0013]
(7) A plurality of beams consisting of a main beam and a sub beam are relatively moved on an information recording medium on which multi-valued information is recorded, and the main beam is irradiated on a track to be reproduced on the information recording medium, and the sub beam is irradiated. The main beam is irradiated on a track adjacent to the irradiated track, and the reflected light or transmitted light of the sub beam is used to cancel crosstalk with respect to the reflected light or transmitted light of the main beam, and the reflection of the main beam and the sub beam is performed. In an information reproducing method for reproducing multi-valued information recorded on the information recording medium using light or transmitted light, a method for reproducing reflected light or transmitted light of the sub beam based on a clock signal synchronized with a reproduced signal of the main beam. And quantizes the main beam based on the average value of a plurality of continuous quantized levels. Information reproducing method of canceling crosstalk to light or transmitted light.
[0014]
(8) A plurality of beams consisting of a main beam and a sub beam are relatively moved on an information recording medium on which multi-valued information is recorded, and the main beam is irradiated on a track to be reproduced on the information recording medium, and the sub beam is The main beam is irradiated on a track adjacent to the irradiated track, and the reflected light or transmitted light of the sub beam is used to cancel crosstalk with respect to the reflected light or transmitted light of the main beam, and the reflection of the main beam and the sub beam is performed. In an information reproducing method for reproducing multi-valued information recorded on the information recording medium using light or transmitted light, the main beam reflected light or transmitted light obtained from a quantization result of reflected light or transmitted light of the sub-beam is used. An information reproducing method for switching the amount of crosstalk cancellation for each type of the information recording medium.
[0015]
(9) A plurality of beams consisting of a main beam and a sub beam are relatively moved on an information recording medium on which multi-valued information is recorded, and the main beam is irradiated on a track to be reproduced on the information recording medium, and the sub beam is emitted. The main beam is irradiated on a track adjacent to the irradiated track, and the reflected light or transmitted light of the sub beam is used to cancel crosstalk with respect to the reflected light or transmitted light of the main beam, and the reflection of the main beam and the sub beam is performed. In an information reproducing method for reproducing multi-valued information recorded on the information recording medium using light or transmitted light, the main beam reflected light or transmitted light obtained from a quantization result of reflected light or transmitted light of the sub-beam is used. An information reproducing method in which the amount of crosstalk cancellation is switched according to the method of creating the multi-value level of the information recording medium. .
[0016]
(10) A plurality of beams including a main beam and a sub beam are relatively moved on an information recording medium on which multi-valued information is recorded, and the main beam is irradiated on a track to be reproduced on the information recording medium, and the sub beam is The main beam is irradiated on a track adjacent to the irradiated track, and the reflected light or transmitted light of the sub beam is used to cancel crosstalk with respect to the reflected light or transmitted light of the main beam, and the reflection of the main beam and the sub beam is performed. In an information reproducing method for reproducing multi-valued information recorded on the information recording medium using light or transmitted light, the main beam reflected light or transmitted light obtained from a quantization result of reflected light or transmitted light of the sub-beam is used. An information reproducing method for switching the amount of crosstalk cancellation according to the reproducing power of the beam.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.
FIG. 1 is a block diagram showing a schematic configuration of an optical system in an optical pickup device of an optical disk device according to an embodiment of the present invention.
This optical pickup device includes a light source unit (LD) 1 having a light emitting point, a collimator lens 2, a grating 8, a beam splitter 3, an objective lens 4, a detection lens 6, and a light receiving element (PD) 7.
[0018]
A semiconductor laser chip is mounted on the light source unit 1, and a beam (light beam, laser beam) emitted from the semiconductor laser chip is converted by the collimator lens 2 into substantially parallel light. After that, the beam is separated into a main beam and a sub beam by the grating 8. These beams pass through the beam splitter 3, are condensed by an objective lens 4, and are irradiated on an information recording track of an information recording medium (optical recording medium, optical disk) 5.
[0019]
The reflected light from the information recording medium 5 reverses the optical path at the time of irradiation, and reaches the beam splitter 3 again through the objective lens 4. The reflected light is reflected by the beam splitter 3 and guided to the light receiving element 7 unlike the irradiation. The light receiving element 7 is appropriately divided according to a servo signal generation method, and the detected reflected light from the information recording medium 5 is used as a track error signal, a focus signal, a wobble signal, a reproduction signal, and a crosstalk signal for subsequent control. Output to the circuit.
[0020]
FIG. 2 is an explanatory diagram showing the positional relationship of the beam emitted from the light source unit on the information recording medium. FIG. 1 shows only necessary parts for this embodiment.
A square indicated by a broken line in FIG. 3 represents one recording unit of the multi-value information, and is hereinafter referred to as a cell.
Note that the square indicated by the broken line is a virtual one, and does not mean that there is an isolated area called a cell on the information recording medium.
[0021]
The main beam 70 is irradiated so as to be positioned on a track 80 of the information recording medium, and a sub-beam (preceding sub-beam) 71 and a sub-beam (subsequent sub-beam) 72 for canceling crosstalk are arranged on adjacent tracks 81 and 82, respectively. Irradiation. That is, a tracking signal for tracking servo may be generated from only the main beam 70. Alternatively, a tracking sub-beam may be separately used.
Marks having different sizes are recorded in the cells of the track, and multi-value information (multi-value data) is recorded by changing the amount of reflected light according to the size of the marks.
[0022]
FIG. 3 is a waveform diagram showing an example of a reproduction waveform of the multi-value information recorded on the information recording medium.
The reproduced waveform 90 shown in the upper part is an ideal value, and the one shown in the middle part is an ideal reproduced clock 91. The voltage of the reproduced waveform 90 changes to a rectangular wave at the rise of the reproduction clock 91, and the level can be determined stably at the fall of the reproduction clock 91. On the other hand, the actual reproduced waveform 92 is shown in the lower part. As shown in the figure, the actual reproduced waveform 92 leaks not only the reproduced signal of the own track but also the signal of the adjacent track. This is what is called “cross talk”.
[0023]
FIG. 4 is a block diagram showing the configuration of the optical disk device according to one embodiment of the present invention. Here, an optical disc is described as an example of the information recording medium, but the present invention does not depend on the recording method of the information recording medium.
That is, the same effect can be obtained with a magneto-optical, write-once type information recording medium, or a rewritable information recording medium. The figure mainly shows the parts related to the present invention, and shows the minimum configuration necessary for explaining the present invention.
This optical disk device (optical disk drive) includes the optical pickup device 11, an analog circuit 12, a buffer memory 13, a digital circuit 14, an interface controller 15, a spindle motor 16, a servo circuit 17, and a controller 18.
[0024]
When a command is sent from an external device (for example, a personal computer) to the optical disk device, the interface controller 15 of the optical disk device receives the command, and reports to the controller 18 that the command has been received.
The controller 18 interprets the contents of the command, causes the own device to perform an operation requested by the command, and performs a report on the operation to an external device through the interface controller 15.
[0025]
When recording multi-valued information on the information recording medium 5, the multi-valued information is temporarily stored in the buffer memory 13 from the external device via the interface controller 15 and the digital circuit 14. The digital circuit 14 performs processing such as attaching an error correction code to the multi-level information, adding a synchronization signal, and converting the multi-level information into a multi-level modulation code. As for the address on the information recording medium 5 where the multi-valued information is to be written, the address pre-written on the information recording medium 5 is read and the multi-valued information is recorded at the address specified at the time of recording.
[0026]
Next, the analog circuit 12 controls the current so that the light source unit (LD) on the optical pickup device 11 emits light at a multi-value level so that the multi-value information is recorded on the information recording medium 5 and records the multi-value information.
In addition, the optical pickup device 11 irradiates the information recording medium 5 with the light emitted from the LD, receives the reflected light by the light receiving element (PD), processes the analog circuit 12, and generates a focus error signal, a tracking error signal, and the like. Then, the focus error signal, the tracking error signal, and the like are input to the servo circuit 17, and the servo circuit 17 controls the position of the optical pickup device 11, the position of the objective lens, and the like. At this time, the information recording medium 5 usually has a spiral groove or data array. For this reason, as the time elapses (for example, the outer circumference may be changed to the inner circumference), it may move from the inner circumference to the outer circumference, exceeding the range where the tracking control can be performed. Therefore, a control called a carriage is performed so that the entire optical pickup device (PU) 11 is moved from the tracking servo signal so that the position of the objective lens or the like can be always maintained in a nearly neutral position.
[0027]
In the case of reproducing multi-valued information, the output of the optical pickup device 11 is quantized by the analog circuit 12 and clock extraction is performed using a PLL or the like, and the digital circuit 14 performs processing such as synchronization detection, demodulation, and error correction. It is stored in the buffer memory 13. After that, the multi-value information is transferred to the external device through the interface controller 15. From the signal of the optical pickup device 11, three signals of a preceding sub beam, a main beam, and a following sub beam are obtained.
[0028]
Here, if the main beam and the sub beam are demodulated and the time axis is adjusted to eliminate the influence, when recording multi-valued information, the main beam needs more power than the recording power However, at the same time, the sub-beam must be smaller than the power at which recording does not occur. As the small power, the light intensity of the sub beam needs to be about 1/10 of the intensity of the main beam. Therefore, the size of the spot on the information recording medium is also different, and the reproducing condition is changed, and the reproducing condition of the sub beam and the reproducing condition of the main beam are different. In addition, when the influence is on the adjacent track, when the mark is large, the influence is large when the reflectivity is small. If the mark is large, the crosstalk is affected by the larger mark. For this reason, it is not always necessary to accurately reproduce the sub-beams, and the sub-beams may be divided into stages having a large, small, or no effect, which is smaller than the multi-value level of the multi-value information.
[0029]
FIG. 5 is a block diagram showing an internal configuration of the analog circuit 12 according to claims 1 and 6 of the present invention.
The analog circuit 12 amplifies the RF signal from the optical pickup device 11 with a predetermined gain, shapes the signal of the preceding sub beam by an EQ circuit 20, quantizes the signal by an AD circuit 24, converts the signal into a digital signal, and delays the signal. The data is input to the determination circuit 29 via the memory 27. The waveform of the main beam signal is shaped by an EQ circuit 21, quantized by an AD circuit 25 based on a clock signal from a PLL circuit 23, converted into a digital signal, and input to a determination circuit 29 via a delay memory 28. Further, the signal of the succeeding sub-beam is shaped by the EQ circuit 22, quantized by the AD circuit 26, converted into a digital signal, and input to the determination circuit 29.
Then, at the stage of reproducing the multi-valued information, the level of the main beam may be determined by the determination circuit 29 while observing the degree of influence.
[0030]
The multi-level level determination processing in the determination circuit 29 may use a known technique.
For example, the following determination methods (1) to (4) may be used.
(1) The multivalue level of the cell of interest is determined by referring to the preceding cell preceding the cell of interest to be subjected to multilevel level determination, a continuation cell continuing to the preceding cell, or the multivalue determination values of the preceding cell and the continuation cell. judge.
(2) The multi-value level of the cell of interest is determined with reference to the multi-value level of the preceding cell preceding the cell of interest to be subjected to multi-level level determination.
(3) The multi-value level of the cell of interest is determined by referring to the multi-value level of the continuation cell that continues to the preceding cell preceding the cell of interest that is the target of multi-level level determination.
(4) The multi-value level of the cell of interest is determined by referring to the multi-value levels of the preceding cell preceding the cell of interest to be subjected to multi-level level determination and the continuation cell continuing from the preceding cell.
[0031]
In this way, the crosstalk can be canceled by using a sub-beam whose light intensity is weaker at the time of reproducing multi-valued information than at the time of recording, and the number of quantization levels of the sub-beam is smaller than that of the main beam. And low cost can be realized.
[0032]
FIG. 6 is a block diagram showing a configuration of a cancel circuit and a determination circuit according to a second embodiment of the present invention.
Further, instead of the determination circuit 29, a determination circuit 33 in which a cancel circuit including the coefficient calculation unit 30, the addition circuit 31, and the coefficient calculation unit 32 shown in FIG. The cancellation circuit calculates the main beam cancellation amount from the level of the preceding sub beam by the coefficient calculation unit 30 and the main beam cancellation amount from the level of the succeeding sub beam by the coefficient calculation unit 32. The two cancellation amounts are added and input to the determination circuit 33. The determination circuit 33 determines the multi-value level by any one of the above-described determination methods.
[0033]
Therefore, by adding a predetermined amount to the value of the main beam corresponding to the quantization level of the sub-beam at the time of this level determination, the conventional level determination can be performed using the value.
In this manner, the cancellation amount is obtained from the level of the sub beam and added to the main beam to cancel the crosstalk of the main beam, so that the crosstalk of the main beam can be eliminated with a simple circuit configuration.
[0034]
FIG. 7 is a block diagram showing a configuration of a cancel circuit and a determination circuit according to claim 3 of the present invention.
Further, instead of the determination circuit 29, a determination circuit 43 having a cancel circuit including the coefficient calculation unit 40, the multiplication circuit 41, and the coefficient calculation unit 42 shown in FIG. This cancellation circuit calculates the main beam cancellation amount from the level of the preceding sub beam by the coefficient calculation unit 40 and the main beam cancellation amount from the level of the succeeding sub beam by the coefficient calculation unit 42. The two cancellation amounts are multiplied and input to the judgment circuit 43. The determination circuit 43 determines the multi-value level by any of the determination methods described above.
[0035]
Therefore, by multiplying the value of the main beam by a predetermined multiplier corresponding to the quantization level of the sub-beam at the time of this level determination, it is possible to perform a conventional level determination using the value.
In this manner, the cancellation amount is obtained from the level of the sub beam and the main beam is multiplied to cancel the crosstalk of the main beam. Therefore, the crosstalk of the main beam can be surely removed even when there is a level change. .
[0036]
FIG. 8 is a block diagram showing a configuration of an averaging circuit according to the fourth, fifth, and seventh aspects of the present invention which is provided at a stage preceding the determination circuit 29 of FIG.
In addition, the phases of the data in the adjacent track and the track to be reproduced are not always perfectly matched. However, in the case of multi-level recording, since the crosstalk only affects at the level, even if processing is performed by averaging one clock before and after, the effect is small.
Therefore, an averaging circuit for averaging each of the preceding sub beam, the main beam, and the following sub beam is provided at a stage preceding the determination circuit 29. This averaging circuit averages the beam signal for three clocks by three registers 50, 51, and 52 that hold data at a predetermined clock, and calculates and outputs an average by an average calculator 53. Then, it is input to the determination circuit 29.
[0037]
In this way, even if the sampling clock is generated from the main signal, the influence of the asynchronous adjacent track can be canceled.
In addition, since the signal averaging can be realized by three before and after, the circuit scale can be reduced.
Furthermore, since the cancellation amount is obtained from the sub-beam level and added to cancel, it can be realized with a simple circuit configuration.
[0038]
FIG. 9 is a block diagram showing a configuration of a cancel circuit with a coefficient switching function and a determination circuit according to claim 8 of the present invention.
Further, by switching the coefficient for each type of information recording medium (for example, ROM or R medium RW medium), it becomes possible to further cancel the crosstalk of the main beam.
[0039]
The cancellation circuit with the coefficient switching function switches the coefficient by outputting a medium switching signal from the controller 18 to each of the coefficient calculating sections 60 and 62 for each type of information recording medium, and the coefficient calculating section 60 performs the preceding operation based on the switched coefficient. The coefficient calculation unit 62 calculates the main beam cancellation amount from the succeeding sub beam level based on the switched coefficient, and the coefficient calculation unit 62 calculates the main beam cancellation amount from the succeeding sub beam level based on the switched coefficient. The result is multiplied and input to the judgment circuit 63. The determination circuit 63 determines the multi-value level by any one of the above-described determination methods.
In this manner, since the cancellation amount is obtained from the type of the information recording medium, it can be applied to a plurality of types of media such as a ROM and RW / R media.
[0040]
Similarly, as the coefficient switching function according to claim 9 of the present invention, the coefficient can be switched according to the shape of the mark on the information recording medium. FIG. 2 shows an example of a crescent-shaped mark, but a circular mark can also be realized by switching coefficients.
In this manner, since the cancellation amount is obtained based on the shape of the mark for forming the multi-value level, it is possible to handle a plurality of types of media such as a crescent moon and a circle.
[0041]
In addition, the beam shape changes depending on the reproduction power, and the beam shape expands at a high power, and much crosstalk is picked up. Therefore, as a function according to claim 9 of the present invention, the coefficient may be switched with strong power.
In this manner, since the cancellation amount is obtained based on the emission power of the reproduction beam, it is possible to cope with a change in the beam shape due to power fluctuation.
[0042]
【The invention's effect】
As described above, according to the information reproducing apparatus and the information reproducing method of the present invention, it is possible to cancel the crosstalk of the main beam by using a sub-beam whose light intensity is lower than that at the time of recording when reproducing multi-valued information. .
[Brief description of the drawings]
FIG. 1 is a block diagram showing a schematic configuration of an optical system in an optical pickup device of an optical disk device according to an embodiment of the present invention.
FIG. 2 is an explanatory diagram showing a positional relationship of a beam emitted from a light source unit in FIG. 1 on an information recording medium.
FIG. 3 is a waveform diagram showing an example of a reproduction waveform of multi-valued information recorded on the information recording medium of FIG.
FIG. 4 is a block diagram illustrating a configuration of an optical disc device according to an embodiment of the present invention.
FIG. 5 is a block diagram showing an internal configuration of the analog circuit 12 of FIG. 4 according to claims 1 and 6 of the present invention;
FIG. 6 is a block diagram showing a configuration of a cancel circuit and a determination circuit according to a second embodiment of the present invention.
FIG. 7 is a block diagram showing a configuration of a cancel circuit and a determination circuit according to claim 3 of the present invention.
8 is a block diagram showing a configuration of an averaging circuit according to the fourth, fifth, and seventh aspects of the present invention provided at a stage preceding the determination circuit 29 in FIG. 5;
FIG. 9 is a block diagram showing a configuration of a cancel circuit with a coefficient switching function and a determination circuit according to claim 8 of the present invention.
[Explanation of symbols]
1: Light source unit 2: Collimating lens
3: Beam splitter 4: Objective lens
5: Information recording medium 6: Detection lens
7: Light receiving element 8: Grating
11: Optical pickup device 12: Analog circuit
13: Buffer memory 14: Digital circuit
15: Interface controller
16: Spindle motor 17: Servo circuit
18: Controller 20, 21, 22: EQ circuit
23: PLL circuit 24, 25, 26: AD circuit
27, 28: Delay memory
29, 33, 43, 63: judgment circuit
30, 32, 40, 42, 60, 62: coefficient calculation unit
31: Addition circuit 41, 61: Multiplication circuit
50, 51, 52: Register
53: Average value calculation unit 70: Main beam
71, 72: sub beam 80-82: track

Claims (10)

A plurality of beams including a main beam and a sub beam are relatively moved on an information recording medium on which multi-valued information is recorded, and the main beam is irradiated on a track to be reproduced on the information recording medium, and the sub beam is irradiated on the main beam. Is irradiated on a track adjacent to the track on which the light beam has been irradiated, and the reflected light or transmitted light of the sub beam is used to cancel crosstalk with respect to the reflected light or transmitted light of the main beam. In an information reproducing apparatus for reproducing multi-value information recorded on the information recording medium using light,
An information reproducing apparatus, comprising: means for reducing the number of levels for quantizing reflected light or transmitted light of the sub-beam than the number of levels for quantizing reflected light or transmitted light of the main beam. The information reproducing apparatus according to claim 1,
Delay by the number of clocks corresponding to the delay time of the plurality of beams,
Means for adding a predetermined value calculated based on the result of quantization of the sub beam to the result of quantization of the main beam and canceling crosstalk with respect to reflected light or transmitted light of the main beam. Playback device. The information reproducing apparatus according to claim 1,
Delay by the number of clocks corresponding to the delay time of the plurality of beams,
Means for adding a predetermined value calculated based on the result of quantization of the sub beam to the result of quantization of the main beam and canceling crosstalk with respect to reflected light or transmitted light of the main beam. Playback device. A plurality of beams including a main beam and a sub beam are relatively moved on an information recording medium on which multi-valued information is recorded, and the main beam is irradiated on a track to be reproduced on the information recording medium, and the sub beam is irradiated on the main beam. Is irradiated on a track adjacent to the track on which the light beam has been irradiated, and the reflected light or transmitted light of the sub beam is used to cancel crosstalk with respect to the reflected light or transmitted light of the main beam. In an information reproducing apparatus for reproducing multi-value information recorded on the information recording medium using light,
The reflected light or transmitted light of the sub beam is quantized based on a clock signal synchronized with the reproduction signal of the main beam, and the main beam is reflected based on an average value of a plurality of quantized continuous quantization levels. An information reproducing apparatus, comprising: means for canceling crosstalk with light or transmitted light. The information reproducing apparatus according to claim 4,
The information reproducing apparatus according to claim 1, wherein the plurality of continuous quantization levels are three in total before and after the signal to be canceled. A plurality of beams including a main beam and a sub beam are relatively moved on an information recording medium on which multi-valued information is recorded, and the main beam is irradiated on a track to be reproduced on the information recording medium, and the sub beam is irradiated on the main beam. Is irradiated on a track adjacent to the track on which the light beam has been irradiated, and the reflected light or transmitted light of the sub beam is used to cancel crosstalk with respect to the reflected light or transmitted light of the main beam, and the reflected light or transmitted light of the main beam and the sub beam is irradiated. In an information reproducing method for reproducing multi-value information recorded on the information recording medium using light,
An information reproducing method, characterized in that the number of levels for quantizing reflected light or transmitted light of the sub-beam is smaller than the number of levels for quantizing reflected light or transmitted light of the main beam. A plurality of beams including a main beam and a sub beam are relatively moved on an information recording medium on which multi-valued information is recorded, and the main beam is irradiated on a track to be reproduced on the information recording medium, and the sub beam is irradiated on the main beam. Is irradiated on a track adjacent to the track on which the light beam has been irradiated, and the reflected light or transmitted light of the sub beam is used to cancel crosstalk with respect to the reflected light or transmitted light of the main beam, and the reflected light or transmitted light of the main beam and the sub beam is irradiated. In an information reproducing method for reproducing multi-value information recorded on the information recording medium using light,
The reflected light or transmitted light of the sub beam is quantized based on a clock signal synchronized with the reproduction signal of the main beam, and the main beam is reflected based on an average value of a plurality of quantized continuous quantization levels. An information reproducing method characterized by canceling crosstalk with respect to light or transmitted light. A plurality of beams including a main beam and a sub beam are relatively moved on an information recording medium on which multi-valued information is recorded, and the main beam is irradiated on a track to be reproduced on the information recording medium, and the sub beam is irradiated on the main beam. Is irradiated on a track adjacent to the track on which the light beam has been irradiated, and the reflected light or transmitted light of the sub beam is used to cancel crosstalk with respect to the reflected light or transmitted light of the main beam, and the reflected light or transmitted light of the main beam and the sub beam is irradiated. In an information reproducing method for reproducing multi-value information recorded on the information recording medium using light,
An information reproducing method, wherein the amount of crosstalk cancellation for reflected light or transmitted light of a main beam, which is obtained from a result of quantization of reflected light or transmitted light of the sub-beam, is switched for each type of the information recording medium. A plurality of beams including a main beam and a sub beam are relatively moved on an information recording medium on which multi-valued information is recorded, and the main beam is irradiated on a track to be reproduced on the information recording medium, and the sub beam is irradiated on the main beam. Is irradiated on a track adjacent to the track on which the light beam has been irradiated, and the reflected light or transmitted light of the sub beam is used to cancel crosstalk with respect to the reflected light or transmitted light of the main beam, and the reflected light or transmitted light of the main beam and the sub beam is irradiated. In an information reproducing method for reproducing multi-value information recorded on the information recording medium using light,
Information reproduction, wherein the amount of crosstalk cancellation with respect to the reflected light or transmitted light of the main beam obtained from the quantization result of the reflected light or transmitted light of the sub-beam is switched in accordance with how to form a multi-valued level of the information recording medium. Method. A plurality of beams including a main beam and a sub beam are relatively moved on an information recording medium on which multi-valued information is recorded, and the main beam is irradiated on a track to be reproduced on the information recording medium, and the sub beam is irradiated on the main beam. Is irradiated on a track adjacent to the track on which the light beam has been irradiated, and the reflected light or transmitted light of the sub beam is used to cancel crosstalk with respect to the reflected light or transmitted light of the main beam, and the reflected light or transmitted light of the main beam and the sub beam is irradiated. In an information reproducing method for reproducing multi-value information recorded on the information recording medium using light,
An information reproducing method, characterized in that an amount of crosstalk cancellation for reflected light or transmitted light of a main beam obtained from a quantization result of reflected light or transmitted light of the sub-beam is switched in accordance with reproduction power of the beam.

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