JPH05325196A - Signal reproducing system of optical disk - Google Patents

Abstract

PURPOSE:To perform a high-density and large-capacity recording operation by a method wherein a cross talk is offset by utilizing the fact that no correlation exists between signals in adjacent tracks on a disk. CONSTITUTION:In a readout means 10a, beams of reflected light A to C in a track are photodetected by means of photodetectors 11 to 13 and amplified by means of amplifiers 21 to 23. Outputs of the amplifiers 22, 23 are delayed by means of delay devices 32, 33; read-out signals P1 to P3 from three adjacent tracks are output via A/D converters 41 to 43. The delay devices 32, 33 execute a delay operation corresponding to the difference in a readout position between spots A and B as well as that between spots A and C; the time is adjusted in such a way that the three tracks are read out simultaneously in the position of the spot A. In an operation device 50, the three tracks are read out simultaneously, a recording signal Z in the central track including cancellation coefficients x2, y3 is operated by a prescribed operation. On the other hand, in a minimum correlation-coefficient operation part 51, the prescribed number of pieces of sample information in a read-out signal is stored, respectively, the correlation coefficient between the signals P1 and P2 as well as that between P2 and P3 are found, the cancellation coefficients are changed in such a way that the correlation coefficients become minimum; they are operated repeatedly and the coefficients x2, y3 are output.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc signal reproducing system, and more particularly to an optical disc signal reproducing system for producing a reproduced signal in which crosstalk is canceled from read signals of a plurality of adjacent tracks.

[0002]

2. Description of the Related Art Conventionally, high density and large capacity recording of an optical disc has been advanced by a method of increasing the recording density of pits in the track direction, a method of narrowing a beam of a reading laser beam, a method of narrowing a track pitch, or the like. ..

In the method of narrowing the track pitch, the track pitch is limited by the diameter of the light spot focused on the disk. Therefore, if the track pitch is narrowed without changing the spot diameter, the signals of adjacent tracks are also reproduced. Therefore, there is a problem that crosstalk becomes large and a desired signal cannot be reproduced.

As a method for removing this crosstalk or intersymbol interference, etc., Japanese Patent Laid-Open No. 40225/1993 and "Nikkei Electronics" (Nikkei BP) No. 495 are available.
(1991.3.19), pp. 98-99. The technology disclosed in them is such that a plurality of light spots are irradiated onto adjacent tracks, signals are read from the tracks, signal processing is performed using the read signals, and crosstalk mixed in the read signals is performed. Is a method of offsetting. For example, as shown in FIG. 6, three adjacent tracks are irradiated with light spots A, B, and C to read signals from the respective tracks, and read signals of the adjacent tracks are processed to read signals of the central track. The crosstalk mixed in is removed.

FIG. 7 shows a schematic configuration of a conventional optical disc signal reproducing apparatus for removing crosstalk, intersymbol interference and the like. As shown in the figure, a conventional optical disc signal reproducing apparatus includes a transversal filter 101, 102, 103 including a unit delay element and an adder 104 for adding output signals of the transversal filters 101, 102, 103. , A binary decision unit 105 that makes a binary decision on the output signal A of the adder 104, an adder 106 that adds the output signal a of the binary decision unit 105 and the output signal A of the adder 104, and The transversal filters 101, 102, 1 are generated by the output signal e of the adder 106.
Filter coefficients to _{03 C -N ~C N, C '} -N ~C' N,
Coefficient calculator 107 for calculating and outputting C ″ _{-N to} C ″ _N
And are provided. The transversal filters 101, 102, and 103 are generated by a light receiving unit (not shown) that receives the reflected light of the light spots by irradiating the adjacent three tracks on the optical disk with the light spot irradiating unit (not shown). Read signals X, Y and Z are input respectively.

Generally, when a digital signal satisfying the Nyquist characteristic is converted into a signal without crosstalk through the Nyquist filter, as shown in FIG. 8, the signal level value is always "0" or "1" at the sampling point. Become. However, when there is intersymbol interference or crosstalk, an error occurs in the signal level value (point Δ) at each sample point, as shown in. Therefore, the transversal filters 101, 1 are designed to minimize the error.
It is the above-mentioned conventional optical disk signal reproducing apparatus that controls the filter coefficients 02 and 103. More specifically, the output A of the adder 104 at a certain determination
_k is

[0007]

[Equation 1]

It is represented by Then, assuming that the output of the binary determiner 105 is a _k , the output of the adder 106, that is, the error e _k is e _k = A _k −a _k . When this is adaptive equalized by the method of least squares error,
The evaluation function D is (observation period KT),

[0009]

[Equation 2]

[0010] The coefficient calculator 107 performs a calculation for obtaining the filter coefficient Cj that minimizes D.
In this calculation,

[0011]

[Equation 3]

As an alternative, the coefficient can be obtained from matrix calculation, but the amount of calculation increases. Therefore, the coefficient is obtained by the iterative method. ADA (Amplitude dependence algorithms)
) By law,

[0013]

[Equation 4]

[0014] Substituting the above equation into this,

[0015]

[Equation 5]

Therefore, the filter coefficient is

[0017]

[Equation 6]

Is calculated as follows, and the filter coefficient of the next step can be obtained from this. Here, for example, in the above equation (3)

[0019]

[Equation 7]

## EQU1 ## finds the cross-correlation between the error signal and the input signal, which gives the direction and magnitude of changing the filter coefficient Cj. As described above, conventionally, the adaptive equalization method of the digital signal is applied to the crosstalk cancellation to perform the adaptive crosstalk cancellation.

[0021]

However, the above conventional technique is effective for the digital signal satisfying the Nyquist first criterion and the partial response type code sequence signal, but it is effective for the analog signal and the RL.
There is a problem that it cannot be applied to a signal on condition that d ≧ 1 in L (Run Length Limited) code.

As shown in FIG. 9, the digital signal satisfying the Nyquist first criterion has a frequency characteristic with a level at ω = π / T of 0.5 (point S in the figure) and an attenuation characteristic of S. Since it has a characteristic that it is symmetric with respect to the point, the impulse response becomes “1” at T = 0 and becomes “0” at other sampling points. Therefore, the level at a certain sampling point does not affect the levels at the sampling points before and after it, so that the intersymbol interference becomes zero.

On the other hand, the RLL code is (d, k,
m, n), an m-bit signal is converted into n bits, and the minimum value of the continuous length of "0" at that time is d and the maximum value is k. In the case where the recording medium is changed, a high recording density can be obtained in a recording medium having a shortest recording wavelength. An example of a medium for recording an RLL-encoded signal with d ≧ 1 is shown below.・ (2,7) modulation… (2, 7,1, 2) φ130mm continuous servo system, PCM recorder ・ EFM… (2,11,8,17) CD, LD digital voice ・ 2-3 modulation… (1 , 7,2, 3) Professional recorders These codes could not be removed by the above-mentioned conventional techniques because the impulse response usually has a shape as shown in FIG. 9 and includes inter-code interference.

The present invention has been made in view of the above problems. Even if the recording signal is an analog signal, an RLL code signal, or the like, crosstalk, intersymbol interference, etc. are canceled, and high-density large-capacity recording is performed. It is an object of the present invention to provide an optical disc signal reproducing method that enables the above.

[0025]

FIG. 1 shows a flow chart for explaining the principle of the coefficient selecting means in the optical disk signal reproducing system of the present invention.

The present invention for achieving the above object is an optical disc signal reproducing system for generating a reproduced signal in which crosstalk is canceled from read signals of a plurality of adjacent signal tracks, and at least one signal track is irradiated. Reading means for receiving the reflected light of one light spot to generate read signals A, B of a plurality of signal tracks, and processing the plurality of read signals A, B by cancellation coefficients x, y to generate reproduced signals a, b. And a canceling selection means for selecting the canceling coefficients x and y from the plurality of read signals. As shown in FIG. 1, the coefficient selecting means is a read signal of the plurality of signal tracks. First sampling A and B each a predetermined number of times and storing
Step (S1) and the second step of setting the cancellation coefficient
Step (S2) and the stored read signals A and B
For each of them, a third step (S3) of creating a reproduction signal data sequence processed by the set cancellation coefficient, a fourth step (S4) of calculating a correlation coefficient between the reproduction signal data sequences, and A fifth step (S5) of determining whether the correlation coefficient is the minimum and returning to the second step and repeating the setting by returning to the second step, and the correlation coefficient in the fifth step And a sixth step (S6) of selecting the set cancellation coefficient as the cancellation coefficient to be used in the cancellation processing means when it is determined that is the minimum.

[0027]

The optical disk signal reproducing system of the present invention cancels crosstalk by utilizing the fact that signals of adjacent tracks on the disk have no correlation (small amount).

That is, when two adjacent tracks on the disk are considered, the recording signals on the two tracks are respectively a and b, and the signals traced by the optical spot and read from the respective tracks are A and B, If the read signals A and B include crosstalk from adjacent tracks, the read signals A and B of the two tracks can be written as A = a + αb B = b + βa. Here, α and β are crosstalk coefficients. Then, the signal after cancellation is a ′,
Letting b ′ and the cancellation coefficients be x and y, it can be written as a ′ = A−xB b ′ = B−yA. Therefore, if the values of the cancellation coefficients x and y can be obtained, the signals a ′ and
b'can be obtained.

In the present invention, paying attention to the fact that there is no correlation between the signals of adjacent tracks, the signal data string [A-xB]
The crosstalk canceled signal is reproduced by obtaining the cancellation coefficients x and y that minimize the correlation coefficient ρ of [B−yA] and [B−yA].

The method of obtaining the correlation coefficient ρ of two signals is A /
The two signal data strings after D conversion are X (n) = [A−x
B], Y (n) = [B−yA] and the number of data is N, the average value is

[0031]

[Equation 8]

The standard deviation is

[0033]

[Equation 9]

It becomes Use this

[0035]

[Equation 10]

Is calculated. And the correlation coefficient ρ is

[0037]

[Equation 11]

It is calculated by In the case where a plurality of tracks are affected by crosstalk from adjacent tracks on both sides, a correlation coefficient is calculated for two tracks with adjacent tracks on one side and a cancel coefficient is selected. It is possible to calculate the correlation coefficient for two tracks adjacent to the adjacent track on the side and select the cancel coefficient, and to generate a reproduction signal by using both cancel coefficients.

[0039]

Embodiments of the present invention will be described below with reference to the drawings. First Embodiment FIG. 2 shows a block diagram of a first embodiment of an optical disc signal reproducing apparatus for carrying out the present invention. The optical disc signal reproducing apparatus of the present embodiment shown in the figure has a computing unit 50 including a reading unit 10a, a minimum correlation coefficient computing unit 51 which is a coefficient selecting unit, and a cancel computing unit 52 which is a cancel processing unit.
It is configured with.

The reading means 10 is a light receiving element 11 for photoelectrically converting the reflected light from the track due to the irradiation of the light spot.
12, 13 and amplifiers 21, 22 and 23 for amplifying respective output signals of the light receiving elements 11, 12, and 13, delay devices 32 and 33 for delaying respective output signals of the amplifiers 22 and 23, and amplifiers. 21 and A / D converter 4 for digitally converting the output signals of delay devices 32 and 33
1, 42, 43, and outputs read signals P ₁ , P ₂ , P ₃ of adjacent three tracks. The calculator 50 reads the read signals P ₁ , P ₂ , P _{3 of the} three tracks.
Is input and signal processing is performed, crosstalk included in the read signal P ₂ is canceled, and a reproduction signal Z is generated and output.

In the optical disc signal reproducing apparatus of this embodiment,
As shown in FIG. 6, the three light spots A, B, and C are irradiated by the unillustrated light spot emitters to the respective three adjacent tracks of the optical disk, while the reflected light from each track is received. Elements 11, 12, 13
At, the light is received and the recording signal composed of the signal pit P is read for each track. As the arrangement of the light spot to be irradiated onto the optical disk, it is ideally preferable to arrange another light spot so as to be adjacent to the central light spot, but it is difficult due to the beam separation. Therefore, as shown in FIG. 6, the light spots A and C for reading the adjacent tracks are
It is arranged before and after the central light spot B. Therefore, there is a time difference between the read signal of the track irradiated with the light spots A and C and the read signal of the track irradiated with the central light spot B due to the difference in the read position.
Therefore, when the crosstalk component included in the read signal of the central track is canceled by the read signal of the adjacent track, it is necessary to correct the time difference between the signals caused by the difference in the read position. The correction of this time difference is
If the time difference is set to an integral multiple of the clock interval, it can be completely corrected.

In this embodiment, in order to correct the time difference, delay devices 32 and 33 for delaying the analog signal are provided. That is, the read signal by the light spot B preceding the light spot A is delayed by the delay device 32 by a time corresponding to the difference between the read positions of the light spot A and the light spot B. Further, the read signal from the preceding light spot C is delayed by the delay device 33 for a time corresponding to the difference between the read positions of the light spot A and the light spot C. As a result, the read signals P ₁ , P ₂ and P ₃ are created with time adjustment so that the three tracks are read simultaneously at the position of the light spot A. The delay device 3
2 and 33 are arranged in the front stage of the A / D converters 42 and 43, but a delay device for delaying the digital signal is arranged in the rear stage of the A / D converters 42 and 43 and similarly delayed. You may do it.

The minimum correlation coefficient calculator 51 of the calculator 50 in the above configuration calculates the minimum correlation coefficient from the input read signals P ₁ , P ₂ and P ₃ as shown in the figure. The cancellation coefficients x ₂ and y ₃ are output. The cancellation calculation unit 52 performs calculation by inputting the cancel coefficient x _2, y ₃ and read signals P _1, P _2, P _3, the central track to cancel crosstalk components included in the read signal P ₂ A reproduction signal is generated and output. The arithmetic unit 50 includes a processor such as a DSP, a memory and the like, and is configured to execute various arithmetic operations by programming. Note that a dedicated arithmetic processing circuit may be created and configured.

The signal processing in the arithmetic unit 50 will be described. In this embodiment, three adjacent tracks are read at the same time, and the read signal is processed by the arithmetic unit 50 to generate and output the reproduced signal of the central track in which crosstalk is canceled. Here, the recording signals of the three tracks irradiated with the light spots A, B, and C are a,
Given b and c, the read signal can be expressed as:

P ₁ = a + α ₁ b P ₂ = b + α ₂ a + β ₂ c P ₃ = c + β ₃ b where α ₁ , α ₂ , β ₂ and β ₃ are crosstalk coefficients. Then, if attention is paid only between each two tracks, the signal after cancellation is a ′ = P ₁ −x ₀ P ₂ b ′ = P ₂ −y ₀ P ₁ b ″ = P ₂ −x ₁ P ₃ c ″ = P It can be represented by _3- y ₁ P ₂ . From this, the recording signal Z of the center of the track can be represented by _{Z = P 2 -x 2 P 1} -y 3 P 3 ... (8). Where x ₀ , x ₁ , x ₂ ,
y ₀ , y ₁ and y ₃ are cancellation coefficients.

Since the track recording signal is represented by the read signals P ₁ , P ₂ and P ₃ as described above, crosstalk cancellation can be performed by obtaining the cancellation coefficients x ₂ and y ₃ shown in the above equation (8). The reproduced signal of the reproduced center track is obtained. In the calculator 50, the minimum correlation coefficient calculator 51
In the calculation of the correlation coefficient at, the cancellation coefficient x ₂ ,
y ₃ is calculated, and the cancel calculation section 52 calculates the above equation (8) using the cancel coefficients x ₂ and y ₃ to generate and output the reproduction signal of the central track.

The minimum correlation coefficient calculation unit 51 stores a predetermined number of sampling data of the read signals and stores the correlation coefficient between the read signals P ₁ and P ₂ and the read signals P ₂ and P ₃ . The correlation coefficient and the correlation coefficient are obtained respectively. In the calculation of the correlation coefficient, the cancellation coefficient is repeatedly calculated by changing the cancellation coefficient so as to minimize the correlation coefficient, and the cancellation coefficient having the minimum correlation coefficient is selected (x ₂ , y ₃ ). Output as.

The processing steps in the minimum correlation coefficient calculator 51 will be described in detail with reference to the flowchart shown in FIG. First, a predetermined number of sampling data of the read signals P ₁ , P ₂ and P ₃ are stored (steps S11 and S).
12, S13). Next, using the cancellation coefficients x ₀ , x ₁ , y ₀ , y ₁ that are initialized, in the relationship between the read signals P ₁ and P ₂ , the data for each sampling period gives a ₀ = P ₁ − Data strings [a ₀ ] and [b ₀ ] are created by sequentially calculating x ₀ P ₂ , b ₀ = P ₂ −y ₀ P ₁ (step S21). At the same time, regarding the relationship between the read signals P ₂ and P ₃ , similarly, b ₁ = P ₂ −x ₁ P ₃ and c ₁ = P ₃ −y ₁ P ₂ are sequentially calculated from the data for each sampling period. Data strings [b ₁ ] and [c ₁ ] are created (step S22). Then, the data strings [a ₀ ] and [b
₀ ] and the correlation coefficient ρ ₁ and the data strings [b ₁ ] and [c
_1] The correlation coefficient [rho ₂ of the determined (step S41). Then, next, it is determined whether or not the correlation coefficients ρ ₁ and ρ ₂ that have been obtained are the smallest among the correlation coefficients that have been obtained so far (steps S51 and S52).

In this determination, the correlation coefficient ρ ₁ just obtained
If is not the minimum, the cancel coefficient (x ₀ , y ₀ ) is changed in the direction in which the correlation coefficient is minimized (step S6).
1), returning to step S21, the data strings [a ₀ ], [b
₀ ] and calculation of the correlation coefficient are repeated. Similarly,
If the calculated correlation coefficient ρ ₂ is not the minimum, the cancellation coefficient (x ₁ , y ₁ ) is changed in the direction in which the correlation coefficient becomes the minimum (step S62), and the process returns to step S22 and the data string [b ₁ ], [C ₁ ] are created and the correlation coefficient is calculated. If it is determined to be minimum in step S51, the cancellation coefficient y ₀ at that time is output as x ₂ to the cancellation calculation unit 52. Similarly, in step S52
If it is determined to be the minimum in, the cancellation coefficient x ₁ at that time is output as y ₃ . When x ₂ and y ₃ are output to the cancel calculation unit 52, the next sampling data is input and the same processing is performed.

Second Embodiment Next, a second embodiment of the optical disc signal reproducing apparatus for carrying out the present invention will be described.
An example will be described. The optical disc signal reproducing apparatus according to the second embodiment shown here is different from the first embodiment described above, and as shown in FIG. 4, one optical spot 1 is formed on the signal track of the optical disc D by the optical spot emitter 200. , The read signal is stored by receiving the reflected light of the one light spot 1, and the crosstalk signal is canceled from the read signals of the adjacent three tracks to reduce the influence of the crosstalk. The read signal of the central track is reproduced and output. for that reason,
In order to simultaneously process the read signals of three adjacent tracks as in the first embodiment, the reading means 10b
The read signals of a plurality of tracks are temporarily stored and simultaneously output.

In the optical disc signal reproducing apparatus 100 of this embodiment shown in FIG. 4, only the reading means 10b is shown. The arithmetic unit is omitted since it is similar to that of the first embodiment. As shown in the figure, the reading means 10b of the present embodiment has a light receiving element 60 for receiving and photoelectrically converting the reflected light of the light spot 1, an amplifier 61 for amplifying an output signal of the light receiving element 60, and an amplifier 61 thereof. A / D converter 62 for converting the output signal of the above into a digital signal, first, second and third memories 63, 64, 65 for respectively storing read signals for one track, and a rotation synchronizing signal for the optical disc D. , A memory control circuit 66 for controlling storage and output control of output data of the A / D converter 62 to the memories 63, 64, 65 in response to the signal, and a memory according to the instruction of the memory control circuit 66. And an output switching circuit 67 for switching the outputs of 63, 64 and 64. Here, the rotation synchronization signal is a signal that is generated every time the optical disc D rotates once.

In the above configuration, the memory control circuit 66
In storing the output data of the A / D converter 62, the memory 63, 64, 65 is sequentially switched and stored every time a rotation synchronizing signal is input, that is, each time one track is read. For example, when a rotation synchronizing signal is input, an address signal is output to the first memory 53 so that the first memory 53 is sequentially stored from the head address. The output is controlled to be sequentially stored from the start address, and the control is switched to the third memory 55 by the input of the next rotation synchronization signal to sequentially store the same. Then, when the next rotation synchronization signal is input, the control is switched again to the first memory 53 and stored. In this way, the memory to be stored is sequentially switched every time one track is read, and control is performed so that read signals for three tracks are always stored.

FIG. 5 is an explanatory diagram of data storage and read control in the memories 63, 64 and 65. In the figure, the shaded area indicates an area in which data is stored, Ps indicates a storage pointer, and Pr indicates a read pointer. In the figure, the read signal of the first track is stored in the first memory 63 at addresses 0 to m, and the read signal of the next track is stored in the second memory 64 at addresses 0 to m. The read signal of the next track is stored from 0 to immediately before the address indicated by the storage pointer Ps. Read signals are sequentially stored in the third memory 65 from the address indicated by the storage pointer Ps.

The memory control circuit 66 includes the memories 63, 6
In parallel with the data storage control to 4, 65, control is performed to simultaneously read and output the storage data of each memory in the same cycle as the data storage. In this read control, assuming that the storage in the first memory 63 and the second memory 64 is completed in FIG. 5, for example, immediately after the start of data storage in the third memory 65, the same read address from each memory is started. The address data (the data indicated by the pointer Pr in the figure) is controlled to be sequentially output simultaneously. Then, the third memory 65
When the storage of data into the first memory 63 is completed and the data is switched to the first memory 63, the reading of data also ends up to the address m, but the reading is repeatedly performed from the head address of each memory.

That is, in this embodiment, the memories 63, 6
Data is temporarily stored in the memory cells 4 and 65 and read out at the same time, which is equivalent to the simultaneous reading of three adjacent tracks by detecting the reflected light of the three illuminated light spots in the first embodiment. For example, the read signals of the first tracks of the three adjacent tracks are transferred to the first memory 63,
When the read signal of the second track is stored in the second memory 64, and further the read signal of the third track is started to be stored in the third memory 65, it is as if the read signals of the three tracks were read simultaneously. It is output at the same time. In this case, the read signal of the center track becomes the output of the second memory 64, but when the read signal of the fourth track to be read subsequently is stored in the first memory 63, the read signal of the center track is read. Is the output of the third memory 65. Therefore, in the memory control circuit 66, the read signal of the central track of the three tracks which is continuously read and stored becomes the center of the output of the reading means 10b, and the outputs of the adjacent tracks are always the same positional relationship P ₁ , P. _The output control circuit 67 is controlled so as to be ₂ , P _3, and a read signal is output.

Therefore, in the optical disk signal reproducing apparatus of the present embodiment, the output of the reading means 10b is used to perform the signal processing in the arithmetic unit in the same manner as in the first embodiment to generate the reproduced signal in which the crosstalk is canceled. ..

As described above, in the present embodiment, since the read signal is temporarily stored and the read signals of the adjacent three tracks are simultaneously outputted, the reproduced signal with the crosstalk canceled can be obtained. Unlike the example, only one light spot is required to irradiate the optical disc, and it is possible to provide a reproducing system in which the optical system that is difficult to adjust is simplified.

The first and second embodiments are as follows.
The reproduction signal is generated by canceling the crosstalk from the read signals of the three tracks. However, when there is an influence of the crosstalk from only one adjacent track due to the track pitch or the irradiation state of the light spot. In the same manner, the minimum correlation coefficient is calculated from the read signal of two tracks, and the reproduction coefficient can be generated by determining the cancel coefficient.

[0059]

As described above, according to the optical disc signal reproducing method of the present invention, the correlation coefficient between the reproduced signal data strings of the adjacent tracks is calculated by paying attention to the relationship between the signals of the adjacent tracks. As a result, the cancellation coefficient is selected to generate the reproduction signal, so that the reproduction signal with reduced crosstalk is generated regardless of the signal recorded on the optical disk such as the digital signal or the analog signal. Even when a recording signal such as the above is used, it is possible to achieve high density and large capacity recording.

[Brief description of drawings]

FIG. 1 is a flowchart illustrating the principle of a coefficient selecting means of the present invention.

FIG. 2 is a configuration diagram of an optical disc signal reproducing apparatus according to a first embodiment of the present invention.

FIG. 3 is a processing flowchart of a minimum correlation coefficient calculation unit according to the embodiment of this invention.

FIG. 4 is a configuration diagram of a reading unit in the optical disc signal reproducing apparatus according to the second embodiment of the present invention.

FIG. 5 is an explanatory diagram of memory storage and reading of data in the second embodiment.

FIG. 6 is an explanatory diagram of a light spot irradiated on a track of an optical disc.

FIG. 7 is a block diagram of a conventional optical disc signal reproducing apparatus.

FIG. 8 is a waveform diagram illustrating a reproduced signal.

FIG. 9 is an explanatory diagram of signal characteristics.

[Explanation of symbols]

 1, 2, A, B, C ... Optical spots 10a, 10b ... Reading means 11, 12, 13, 60 ... Light receiving elements 21, 22, 23, 61 ... Amplifiers 32, 33 ... Delay elements 41, 42, 43, 62 ... A / D converter 50 ... calculator 51 ... minimum correlation coefficient calculator 52 ... cancel calculator 63, 64, 65 ... memory 66 ... memory control circuit 67 ... output switching circuit 100 ... optical disc signal reproducing device 200 ... optical spot Output means

Claims (3)

[Claims] 1. An optical disc signal reproducing system for generating a reproduced signal in which crosstalk is canceled from read signals of a plurality of adjacent signal tracks, wherein the reflected light of at least one light spot irradiated on the signal track is received. Reading means for generating read signals of a plurality of signal tracks, cancel processing means for processing the plurality of read signals with a cancel coefficient to generate a reproduced signal, and coefficient selecting means for selecting the cancel coefficient from the plurality of read signals. The coefficient selecting means performs a first step of sampling and storing a predetermined number of read signals of the plurality of signal tracks, a second step of setting a cancel coefficient, and the stored read signal. Reproduced signal data processed by the cancellation coefficient set above for each And a fourth step of calculating a correlation coefficient between the reproduction signal data strings, determining whether or not the correlation coefficient is the minimum, and if the correlation coefficient is not the minimum, the third step A fifth step is returned to step 2 and the setting is repeated, and the cancellation coefficient that has been set is used in the cancellation processing means when it is determined in the fifth step that the correlation coefficient is the minimum. A sixth step of selecting as a cancellation coefficient, and an optical disc signal reproducing method characterized by the following. 2. The optical disc signal reproducing method according to claim 1, wherein the reading means receives the reflected light of the light spots emitted to each of a plurality of adjacent signal tracks, and the read signal of each of the plurality of signal tracks. An optical disk signal reproducing system characterized by comprising a plurality of light receiving elements for generating. 3. The optical disc signal reproducing method according to claim 1, wherein the reading means receives the reflected light of the light spot applied to the signal track and generates a read signal of the signal track, An optical disk signal reproducing system, comprising: a signal storage unit that stores the read signals of a plurality of adjacent signal tracks and outputs the read signals at the same time.