JPH10269592A - Optical disk reproducing device and tracking error signal evaluation method and generation device for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform stable tracking control by detecting the signal phase difference of respective region signals forming added pairs from a photodetector divided into four or more regions, evaluating an offset amount produced in a tracking error signal and deciding a delay amount based on the evaluation result of the offset amount. SOLUTION: The output of the light receiving cell A of a 4division photodetector 1 is passed through the delay circuit 6 of a fixed delay amount and inputted to an adder 10 and a waveform rectifier 11. The output of a light receiving cell C is passed through a delay circuit 8 of a variable delay amount and inputted to the adder 10 and a waveform rectifier 12. The outputs of the waveform rectifiers 11 and 12 are inputted to a phase comparator 13, the outputs thereof are fed back to the delay circuit 8 and control is then performed to make the phase of the output 101 of the delay circuit 6 coincident with that of the output 103 of the delay circuit 8. The outputs of the light receiving cells B and D are also processed, the two signals 101 and 103 and the signals 102 and 104 respectively phase-coincided with each other are added by the adders 10 and 15, phase comparison is performed by a phase comparator 22 and thereby a tracking error signal without any offset is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk reproducing apparatus for reproducing an optical disk on which information data is recorded, and more particularly to a phase difference type optical disk reproducing apparatus capable of performing good tracking control by using phase pits. The present invention relates to a tracking error signal evaluation method and a tracking error signal generation device in such a device.

[0002]

2. Description of the Related Art As an information recording medium in which information data is recorded on an optical disc, for example, a compact disc (hereinafter referred to as C
D) and DVDs. These CDs and DVDs
On the recording surface, phase pits corresponding to the information are formed.To reproduce the phase pits recorded on the disk recording surface, the laser light from the optical head is focused on the disk recording surface, The intensity of the reflected light is converted into an electric signal.
At this time, it is necessary to perform focusing control for always focusing the light spot where the laser light is focused on the recording surface, and tracking control for always tracing the light spot on the phase pit row. Among them, there is a phase difference detection method as one of methods for generating a tracking error signal for performing tracking control.

This phase difference detection method has an advantage that the configuration and adjustment of an optical head are simpler than the conventional three-spot method because a tracking error signal can be generated with one beam. However, in this phase difference detection method, when the optical depth d of the phase pit and the wavelength λ of the laser are d ≠ λ / 4, if the objective lens is displaced in the disk radial direction, a tracking error signal is generated. There is a problem that an offset occurs. Therefore, when good tracking control is performed using the phase difference detection method, it is necessary to suppress the occurrence of the offset.

FIG. 2 is a block diagram showing a tracking error signal generation circuit in a conventional tracking control device. In the figure, reference numeral 1 denotes a light receiving cell (1
A, 1B, 1C, 1D) divided into four photodetectors,
2 to 5 are I / V converters, 10 and 15 are adders, 20, 2
1 is a waveform shaper, 22 is a two-input phase comparator that outputs a pulse width equal to the phase difference, 23 is a low-pass filter,
25 and 26 are delay circuits.

[0005] The operation of generating the tracking error signal whose structure has been described above will be described below.

First, when reflected light from an optical disk (not shown) enters the photodetector 1, a detection current proportional to the amount of incident light flows through each light receiving cell, and the I / V converters 2 to 5
Are converted into respective voltage signals. Light receiving cell 1A
The signal 110 (via the I / V converter 2) is directly input to the adder 10 and the (I / V)
The signal 112 (through the V converter 4) is input to the adder 10 via the delay circuit 25. Here, the delay amount of the delay circuit 25 is set to zero (0). Similarly, a signal 11 (via the I / V converter 3) from the light receiving cell 1B
1 is input to the adder 15 and (I) from the light receiving cell 1C is input.
/ V converter 4) signal 113
Is input to the adder 15 via the. Here, the delay amount of the delay circuit 26 is also set to zero (0).

That is, the adder 10 generates the sum of the signals of the light receiving cells 1A and 1C arranged on the diagonal line, and the adder 15 generates the sum of the signals of the light receiving cells 1B and 1D arranged on the other diagonal line. ing. A signal 105 from each adder,
106 is input to the waveform shapers 20 and 21, respectively, and is shaped into a rectangular wave. The output of the waveform shaper 20 is connected to the X input of the phase comparator 22, and the output of the waveform shaper 21 is connected to the Y input of the phase comparator 22. Then, the phase comparator 22 compares the X input phase with the Y input phase, and for example, X
When the input phase is advanced, a pulse having a width equal to the phase difference is output to the positive side with respect to the reference voltage. On the other hand, when the Y input phase is advanced, a pulse having a width equal to the phase difference is output to the negative side with respect to the reference voltage. The output of the phase comparator 22 is smoothed by a low-pass filter 23 to become a tracking error signal.

Next, the principle of generation of the above-mentioned offset,
The correction method will be described.

FIG. 3 shows the positional relationship between the four-divided photodetector 1 and the far-field image of the light spot incident thereon. FIG. FIG. 2B shows a positional relationship when the objective lens is displaced toward the outer peripheral side of the disk, and FIG. 3B shows a positional relationship when the objective lens is displaced toward the outer periphery of the disk.
Contrary to (2), this shows the positional relationship when the objective lens is displaced toward the inner circumference of the disk.

Next, FIG. 4 shows a case where the light spot traces the vicinity of the phase pit edge on the track center axis.
FIG. 3 shows signal waveforms at various parts in the block diagram of FIG. Note that, in the figure, (1) indicates delay circuits 25 and 26.
3 shows the signal waveforms of the respective parts when the delay amount is zero. Therefore, signals 103 and 112 and signal 104 in the figure
And 113 are handled as completely the same signal.

As shown in FIG. 4A, unless the optical depth d of the phase pit and the wavelength λ of the laser are d = λ / 4, the signal 110 from the light receiving cell 1A and the light receiving cell 1C A signal 112 has a certain time difference due to a so-called push-pull component in the tangential direction of the disk. For example, d <
When λ / 4, the falling time t13 of the signal 110
And the falling time t11 of the signal 112 (= signal 103)
Is assumed to have a time difference of Δt1. When the light spot far-field image has the positional relationship shown in FIG. 3A, the DC values of the amounts of light incident on the light receiving cells 1A and 1C are equal.
Vm = CVm and AVp = CVp. Therefore, the falling time of the waveform shaping output signal 114 after the addition of both signals is the average value t12 of t11 and t13. In exactly the same way, the signals 111 and 113 (= signal 10
Also in 4), the falling time of the waveform shaped output signal 115 after addition is t12. Therefore,
A signal having the same phase that falls at time t12 is input to the phase comparator 22, and a tracking error amount of zero, that is, a correct value is detected.

On the other hand, the far-field image of the light spot is shown in FIG.
In the positional relationship shown in (2), the DC values of the amounts of light incident on the light receiving cells 1A and 1C are not equal, and in the signal 110 and the signal 112 (= signal 103), AVm> CV
m, AVp> CVp. Accordingly, the falling time of the waveform shaping output signal 114 after the addition of the two signals tends to be dominated by t13, which is the falling time of the signal 110, and is a time t14 in the positive direction from t12. In the signal 111 and the signal 113 (= signal 104), the BV
m <DVm and BVp <DVp. Therefore, the falling time in the waveform shaping output signal 115 after the addition of the two signals tends to be dominated by t11, which is the falling time of the signal 113 (= signal 104), and is more negative than time t12.
It becomes 15.

As a result, a signal falling at time t14 is input to the X input of the phase comparator 22, and a signal falling at time t15 earlier than t14 is input to the Y input, and a tracking error in the negative direction is obtained. A signal is output. Conversely, when the light spot far-field image has the positional relationship shown in FIG. 3 (3), a detailed description is omitted, but a signal falling at time t15 is applied to the X input of the phase comparator 22 according to the same principle. A signal that falls at time t14 later than t15 is input to the Y input, and a positive tracking error signal is output. Since the light spot is originally located on the center axis of the track, the error signal in the negative or positive direction output here becomes an offset.

As described above, in the block diagram of FIG.
The operation when the delay amount setting values of the delay circuits 25 and 26 are set to zero has been described. Next, the delay circuits 25, 26
The operation in the case where the delay amount is set to an appropriate value will be described.

FIG. 4B shows a waveform when the delay amount of the delay circuits 25 and 26 is set to ΔT1. Signal 110 from light receiving cell 1A and signal 1 from light receiving cell 1C
12, a time difference ΔT1 occurs as described above. Here, the signal 112 is given a delay of ΔT1 by the delay circuit 25. As a result, the output signal 103 has a fall time of t13 as shown in FIG. As described above, if the phases of both signals before the addition are matched, in any of the cases of FIGS. 3 (1) to 3 (3), the waveform shaped output signal 11 after the addition of both the signals.
In 4, the falling time is t13, and the falling time can be kept constant without being affected by the light amount balance of the light receiving cells.

Similarly, the signal 113 is delayed by ΔT1 by the delay circuit 26, and as a result, the output signal 10
4 is a signal having the same phase as the signal 111 as shown in FIG. Thus, in any of the cases of FIGS. 3A to 3C, the falling time of the waveform shaping output signal 115 after the addition of both signals is t13. Therefore, the phase comparator 22
, A signal of the same phase that falls at the time t13 is input,
3 (1) to 3 (3), a tracking error amount of zero, that is, a correct value without offset is detected. The tracking control device described above is described in, for example, Japanese Patent Application Laid-Open No. Sho 62-165737.

However, in the above-mentioned conventional example, the method of setting the delay amount of the delay circuit is not particularly mentioned. That is, since the optimal delay amount to be set needs to be a value proportional to the scanning linear velocity of the light spot, particularly when the rotational angular velocity of the disk is constant, the set value is set according to the radial position of the disk. Although it must be changed, the above-mentioned conventional example does not mention this point at all.

Therefore, in the configuration of the above-mentioned conventional example, when the scanning linear velocity of the light spot changes, there is a problem that the tracking error signal fluctuates in the set value of the delay amount, that is, an offset occurs due to the deviation of the set value. Was.

In the above conventional example, since the delay circuit is provided only on the 1C and 1D sides of the light receiving cell, the relation between the optical depth d of the phase pit and the laser wavelength λ is d <d.
There is also a problem that the offset correction can be performed only in the case of λ / 4 or d> λ / 4.

[0020]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems in the prior art, and has no problem with changing the scanning linear velocity of a light spot during reproduction of recorded information. Provided is an optical disk reproducing apparatus capable of performing good tracking control without causing an offset in a tracking error signal even for a disk having a pit depth, and a tracking error signal evaluation method and a tracking error signal generating apparatus in such an apparatus. With the goal.

[0021]

In order to achieve the above object, according to the present invention, an optical disk reproducing apparatus for reproducing an optical disk on which phase pits are recorded concentrically or spirally is divided into at least four areas. In an error signal generation device that generates a tracking error signal by comparing the signal phases of two signals obtained by adding the respective area signals from the detected light detection means, each area signal to be an addition pair before the addition is performed. A tracking error signal evaluation method for detecting the signal phase difference of the tracking error signal and evaluating the magnitude of the offset amount generated in the tracking error signal from the detection result.

Further, according to the present invention, in an optical disk reproducing apparatus for reproducing an optical disk on which phase pits are recorded concentrically or spirally, respective area signals from at least four or more divided light detecting means are added. In an error signal generation device that generates a tracking error signal by comparing the signal phases of two obtained signals, a subtraction output of each area signal to be an addition pair before the addition is generated, and an amplitude detection of the output, or From the result of peak value detection,
Provided is a tracking error signal evaluation method for evaluating the magnitude of an offset generated in a tracking error signal.

Further, in order to achieve the above object, the present invention provides a tracking error signal generating apparatus using any one of the tracking error signal evaluation methods described above, wherein A tracking error signal generation device is provided in which at least one of them is provided with a delay means capable of setting a delay amount by a control signal, and sets the delay amount using an evaluation result of an offset amount generated in the tracking error signal. You.

Further, in order to achieve the object of the present invention,
According to the present invention, there is provided an optical disk reproducing device including the above-described tracking error signal generating device.

That is, the optical disk reproducing apparatus according to the present invention has a light source and a plurality of light receiving areas into which a light beam from the light source enters via the optical disk. Divided light detection means,
First delay means for inputting a signal from a first light receiving area of the light detecting means, second delay means for inputting a signal from a second light receiving area, and a variable delay amount; A first phase comparing means for detecting a phase difference between outputs of the delay means, and a first adding means for outputting the outputs of the first and second delay means. By feeding back the output of the first phase comparing means, the phase of the output of the first delay means and the phase of the output of the second delay means are matched.

Similarly, a third delay means for inputting a signal from a third light receiving area of the light detecting means, and a fourth delay means for inputting a signal from the fourth light receiving area and having a variable delay amount. , Second phase comparing means for detecting a phase difference between the outputs of the third and fourth delay means, and second adding means for adding the outputs of the third and fourth delay means. By feeding back the output of the second phase comparing means to the quantity control signal, the phases of the outputs of the third delay means and the fourth delay means are made to coincide.

The addition results obtained after the signal phases from the first and second light receiving areas obtained as described above are matched, that is, the output of the first adding means and the third and fourth light receiving areas. By providing a third phase comparison means for inputting the addition result after matching the signal phases of the signals, ie, the output of the second addition means, and using the output of the phase comparison means as a tracking error signal, Tracking control becomes possible.

[0028]

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

FIG. 1 is a block diagram showing an embodiment of a tracking error signal generating apparatus for generating a tracking error signal in the optical disk reproducing apparatus according to the present invention. In the figure, reference numerals 6 and 7 denote delay circuits with fixed delay amounts, 8 and 9 delay circuits capable of setting a delay amount by an external control signal, 11, 12, 16, and 17 waveform shapers,
Reference numerals 13 and 18 denote phase comparators, 14 and 19 denote low-pass filters, 24 and 25 denote sample and hold circuits, and 26 a microcomputer. In addition,
The same functional blocks as those in FIG. 2 are denoted by the same reference numerals, and description thereof is omitted here.

FIG. 5 is a characteristic diagram showing the relationship between the control signal voltages of the delay circuits 8 and 9 and the amount of delay. In this figure, the delay amount value D0 of the delay circuits 6 and 7 is set to a substantially center value between the minimum value D1 and the maximum value D2 of the delay amount setting values of the delay circuits 8 and 9.

FIG. 6 is a signal waveform diagram showing the signal input / output relationship of the phase comparators 13 and 18.

Here, in FIG.
The signal 101 output from A and passing through the I / V converter 2 and the delay circuit 6 with a fixed delay amount is input to the adder 10 and the waveform shaping circuit 12. The signal 103 output from the light receiving cell 1C and passing through the I / V converter 4 and the variable delay circuit 8 is input to the adder 10 and the waveform shaper 11. The signals input to these waveform shapers 11 and 12 are:
After the waveforms are shaped, they are connected to the X input and the Y input of the phase comparator 13, respectively (see the upper waveform in FIG. 6). The output of the phase comparator 13 is connected to the control signal input of the delay circuit 8 via the low pass filter 14 and the sample hold circuit 24. As a result, the output 101 of the delay circuit 6 and the output 103 of the delay circuit 8 are output from the low-pass filter 14.
(Refer to the lower waveform in FIG. 6). This is fed back to the delay circuit 8 so that the output 101 of the delay circuit 6 and the output 1 of the delay circuit 8 are output.
It is possible to control the amount of delay of the delay circuit 8 so that the phases of 03 are matched.

The range of the variable delay amount of the delay circuit 8 is about ± D0 with reference to the delay amount of the delay circuit 6, so that the signal phase relationship between the light receiving cells 1A and 1C is
Even if the signal from A is ahead or late,
In either case, the phases of the output 101 of the delay circuit 6 and the output 103 of the delay circuit 8 can be matched.

Similarly, the signals from the light receiving cells 1 B and 1 D located at the other diagonal of the photodetector 1 have the same signal phase in the output signals 102 and 104 of the delay circuits 7 and 9. As described above, the two signals 101 having the same signal phase
And 103, and 102 and 104 are added by the adders 10 and 15, respectively, and phase comparison is performed. As a result, a tracking error signal free from offset can be obtained as described with reference to FIG. .

Incidentally, the phase difference between the signal from the light receiving cell 1A and the signal from the light receiving cell 1C (similarly, the light receiving cell 1B
From the signal from the light receiving cell 1D)
The correlation between (1) the amount of displacement of the far-field image of the light spot incident on the quadrant photodetector 1 in the radial direction of the disc and (2) the amount of displacement of the light spot irradiated on the optical disc from the track center is: Small enough to be ignored, (1)
Regardless of (2), the phase difference amount is substantially constant.

When the light spot is located between the tracks, as compared to when the light spot traces substantially on the center of the track, the signal amplitude from each light receiving cell decreases. In 18, accurate phase comparison may not be performed. Therefore, the microcomputer 26
The on-track / off-track detection is performed by a well-known technique, and the sample and hold circuits 24 and 25 are controlled so as to be in the sample mode when on-track is detected and in the hold mode when off-track is detected. This makes it possible to stably set the delay amount of the delay circuits 8 and 9 even when the light spot crosses the track in the access operation. Note that the sample and hold circuit 24,
The above operation using 25 is not necessarily indispensable, and instead, for example, the low-pass filter 14,
If the cutoff frequency of 19 is set sufficiently lower than the frequency of track crossing, it can be omitted.

Next, FIG. 7 is a block diagram showing an example of a tracking error signal generating apparatus according to a second embodiment of the present invention. In FIG. 7, the difference from FIG. Waveform shaping circuits 16 and 17, a phase comparator 18,
The point is that the low-pass filter 19 and the sample-and-hold circuit 25 are deleted, and the output signal of the sample-and-hold circuit 24 is used as the control signal of the delay circuit 9.

As described above, the signal from the light receiving cell 1B and
The phase comparison system of the signal from the light receiving cell 1D can be omitted because the phase difference between the signal from the light receiving cell 1A and the signal from the light receiving cell 1C, the signal from the light receiving cell 1B, and the light receiving cell 1D This is because the amounts of phase difference between the signals from the first and second signals match. Further, since the delay amount to be set in the delay circuit 8 and the delay amount to be set in the delay circuit 9 are the same, the control signals of both the delay circuits 8 and 9 can be the same signal. With this configuration, the number of circuits can be significantly reduced as compared with the configuration shown in FIG.

FIG. 8 is a block diagram showing an example of a tracking error signal generating apparatus according to a third embodiment of the present invention. In the configuration shown in FIG. 8, the circuit shown in FIG. The difference between the waveform shaping circuits 11 and 1
2, the phase comparator 13 and the low-pass filter 14 are eliminated, and changeover switches 27, 28 and 29 are newly provided.

Here, in the configuration of FIG. 8 according to the other embodiment, the operation of a portion different from that of FIG. 7 will be described.

First, a switch 27 is provided in front of the waveform shaping circuit 20, and the output of the adder 10 is connected to the terminal b of the switch 27, and the output of the delay circuit 6 is connected to the terminal a thereof. A switch 28 is provided in front of the waveform shaping circuit 21. The output of the adder 15 is connected to the terminal b of the switch 28, and the output of the delay circuit 8 is connected to the terminal a of the switch 28. Further, a changeover switch 29 is provided at the output of the low-pass filter 23, and a tracking error signal output terminal 109 is connected to its b terminal side, and a sample and hold circuit 24 is connected to its a terminal side.

For example, the control signal 20 from the microcomputer 26
2, when the connection direction of these changeover switches 27, 28 and 29 is set to the terminal a, the output of the delay circuit 6 is input to the phase comparator 22 via the changeover switch 27 and the waveform shaper 20. Since the output of the delay circuit 8 is input to the phase comparator 22 via the changeover switch 28 and the waveform shaper 21, the output of the phase comparator 11 is the same as the output of the phase comparator 13 in FIG. Become. The output is input to a sample-and-hold circuit 24 via a low-pass filter 23 and a changeover switch 29.
The delay amounts of the delay circuits 8 and 9 can be set in exactly the same manner as the operation in FIG.

On the other hand, when the connection direction of the changeover switches 27, 28, 29 is set to the terminal b, the adder 10,
15 are input to the phase comparator 22 via the waveform shapers 20 and 21, respectively, so that a tracking error signal is obtained from the low-pass filter 23, and the tracking error signal output terminal 109 is provided via the changeover switch 29.
Is output to

In the above-described embodiment, since the generation of the tracking error signal and the operation of setting the delay amount of the delay circuits 8 and 9 cannot be performed at the same time, switching of the connection direction of the changeover switch is described below, for example. Like (any)
It must be done at the right time.

(1) The changeover switch is connected to the terminal a only during the period when the tracking control is off.

(2) The connection direction of the changeover switch is switched at a repetition frequency sufficiently higher than the signal band of the tracking error signal.

In the case of (1), the delay set amount cannot be updated while the tracking control is on, so that the disk rotational angular velocity for which the set amount needs to be changed according to the disk radial position is constant. Not suitable for reproduction.
In (2), the tracking error signal can be generated and the delay set amount can be updated in a time-division manner, so that good tracking control can be performed even when the disk rotation speed is constant.
As described above, according to the present embodiment, the number of circuits can be further reduced by combining the phase comparison systems into one as compared with the second embodiment.

FIG. 9 is a block diagram showing an example of a tracking error signal generator according to the fourth embodiment of the present invention. 7, the difference from FIG. 7 is that the waveform shaping circuits 11 and 12, the phase comparator 13, the low-pass filter 14, and the sample-and-hold circuit 24 are eliminated, whereas the subtractor 31 and the peak detection The difference is that a circuit 32 and an A / D converter 33 are newly provided.

FIG. 10 shows signal waveforms at various points in the block diagram of FIG. The operation of the above embodiment will be described with reference to these drawings.

The outputs 101 and 103 of the delay circuits 6 and 8 are input to the subtractor 31 to generate a differential output signal 116.
This differential output signal 116 is input to the peak detection circuit 32, and the peak value signal 117 is output. The detected peak value signal 117 is input to the microcomputer 26 via the A / D converter 33. The microcomputer 26 outputs a setting signal 120 for changing the amount of delay to the delay circuits 8 and 9. For example, the delay amount D3 is set by the setting signal 120 in the periods t21 to t22, and thereafter, similarly, in the periods t22 to t22.
23, and the delay amount D5 during the period t23 to t24.
In the period t24 to t25, and the delay amount D6 in the period t25 to t25.
The delay amount D7 is set at t26.

The peak value signal 117 is shown in FIG.
As shown in FIG. 7, since the phase difference between the signals 101 and 103 is an even function, the microcomputer 26 performs wobbling control, which is a well-known technique, on the delay circuits 8 and 9 so that the peak value signal 117 becomes an extreme value. Excitation of a minute delay amount is performed so as to include (a minimum value in this example). Note that the wobbling frequency is set to a value sufficiently lower than the frequency of the phase pit reproduction signal and sufficiently higher than the signal band of the tracking error signal. As described above, in the present embodiment, the signal phase difference between the output signal 101 of the delay circuit 6 and the output signal 103 of the delay circuit 8 is detected by replacing the signal phase with the voltage level. It is possible to detect with a small circuit.

[0052]

As described above, according to the optical disk reproducing apparatus, the tracking error signal evaluation method and the tracking error signal generating apparatus in the apparatus according to the present invention, the tracking error signal using the phase difference detection method is generated. In the block, an appropriate amount of delay correction can always be set so that the amount of offset generation becomes zero, so that tracking control can be stably performed regardless of the phase pit depth of the optical disk and speed change during reproduction. It is possible to do.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a tracking error signal generating device in an optical disc reproducing device according to the present invention.

FIG. 2 is a block diagram illustrating an example of a conventional tracking error signal generation device.

FIG. 3 is a diagram showing a positional relationship between a photodetector and a far-field image of a light spot incident on the photodetector in the conventional device.

FIG. 4 is a signal waveform diagram showing signals of respective parts of the conventional device shown in FIG. 2;

FIG. 5 is a characteristic diagram showing a relationship between a control signal voltage and a delay amount in the delay circuit of the tracking error signal generation device of the present invention shown in FIG. 1;

FIG. 6 is a signal waveform diagram showing a signal input / output relationship in the phase comparator of the tracking error signal generation device of the present invention.

FIG. 7 is a block diagram showing a second embodiment of the tracking error signal generation device according to the present invention.

FIG. 8 is a block diagram showing a tracking error signal generation device according to a third embodiment of the present invention.

FIG. 9 is a block diagram showing a fourth embodiment of the tracking error signal generation device according to the present invention.

FIG. 10 is a signal waveform diagram showing signals of various parts of the device shown in FIG. 9;

[Explanation of symbols]

 Reference Signs List 1 quadrant photodetector 6, 7 fixed delay circuit 8, 9 variable delay circuit 13, 18, 22 phase comparator 24, 25 sample and hold circuit 26 microcomputer 27, 28, 29 selector switch 32 peak detection circuit

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Koichi Hirose 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Inside the Multimedia Systems Development Division of Hitachi, Ltd. (72) Inventor Koichiro Nishimura Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa No.292 Inside Hitachi Multimedia Systems Development Division

Claims (8)

[Claims] 1. An optical disk reproducing apparatus for reproducing an optical disk on which phase pits are recorded concentrically or spirally, two signals obtained by adding respective area signals from light detecting means divided into at least four areas or more. An error signal generating apparatus that generates a tracking error signal by comparing the signal phases of the respective signals, detecting a signal phase difference of each of the area signals to be an addition pair before the addition, and generating a tracking error signal from the detection result. A tracking error signal evaluation method characterized by evaluating the magnitude of an offset amount to be performed. 2. An optical disc reproducing apparatus for reproducing an optical disc in which phase pits are recorded concentrically or spirally, two signals obtained by adding respective area signals from light detecting means divided into at least four areas or more. An error signal generation device that generates a tracking error signal by comparing the signal phases of the signals, generates a subtraction output of each area signal that is an addition pair before the addition, and performs amplitude detection or peak value detection of the output. A tracking error signal evaluation method, wherein the magnitude of an offset amount generated in a tracking error signal is evaluated based on a result obtained. 3. The tracking error signal evaluation method according to claim 1 or 2, wherein an optical signal of a phase pit formed on a disk is obtained from the signal phase difference detection result, the amplitude detection result, or the peak value detection result. Pit depth detection method characterized by detecting a typical pit depth. 4. The tracking error signal evaluation method according to claim 1, wherein the light spot is displaced from the center of the track formed by the phase pit row by at least a quarter of the track interval. A tracking error signal evaluation method, wherein evaluation of an offset amount generated in a tracking error signal is not performed. 5. A tracking error signal generation device using the tracking error signal evaluation method according to claim 1 or 2, wherein at least one of the area signals forming the addition pair has a delay amount by a control signal. A tracking error signal generating device, comprising a settable delay means, and setting the delay amount using an evaluation result of an offset amount generated in the tracking error signal. 6. The tracking error signal generating device according to claim 5, wherein a predetermined delay is given to a signal on the side where the first delay means is not provided, of the area signals to be added as a pair. A tracking error signal generation device, comprising: 7. The tracking error signal generating device according to claim 6, wherein the predetermined delay amount of the second delay means is substantially equal to a maximum value and a minimum value of the delay amount that can be set by the first delay means. A tracking error signal generation device, which is an average value. 8. An optical disk reproducing device comprising the tracking error signal generating device according to claim 5.