JPH05225585A - Optical disk device and its control method - Google Patents

Abstract

PURPOSE:To accurately detect a tracking error signal without being affected by jitters and the phase synchronism deviation, etc., of PLL. CONSTITUTION:A regenerative signal RF is differentiated by a differentiation circuit 3 and the differential output is converted to a binarization pulse signal PP by a binarization circuit 5. Further, switches 6, 7 are turned on by gate signals GTa, GTb with a wide width generated from a decoder 10 at the detective estimation timing of wobble pits Pa, Pb and the binarization pulse signal PP is made pulse signals Pa, Pb and supplied to S/H circuits 1, 2 sampling the regenerative signal RF and the sampling operation of the circuits are operated. Then the difference value of the hold values SPa, SPb of the S/H circuits 1, 2 is outputted as the tracking error signal ET.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk device which uses as an recording medium an optical disk in which servo information consisting of at least two wobble pits for detecting a tracking error is recorded on recording tracks in advance at predetermined intervals.

[0002]

2. Description of the Related Art In an optical disk such as a write-once optical disk or a magneto-optical disk, a recording track is defined which represents a data recording area, and data is recorded / reproduced / erased while following the recording track. I am trying.

There are two types of recording track structures, one having a guide groove for guiding the laser beam to the recording track and the other having no guide groove. Here, in the latter recording track, servo information for forming a tracking error is recorded in advance at a predetermined interval, and in the optical disc device, a tracking error signal representing the tracking error is formed based on the detection signal of this servo information. I am trying to do it. A tracking method in which servo information is detected to form a tracking error and the laser beam is moved in a direction to eliminate the tracking error is called a sample servo method.

For example, as shown in FIG. 5, an optical disc D
Recording tracks TK are formed concentrically at a predetermined pitch on the SC, and the recording tracks TK are formed on the recording tracks TK as shown in FIG.
As shown in (a), servo areas SBA in which servo information is recorded and data areas DTA having a predetermined length are alternately arranged. Here, the servo information is the recording track T.
An access mark representing the relative track number of K and tracking information for detecting a tracking error. Further, for example, the data length of the servo area SBA is set to 2 bytes, and the data length of the data area DTA is set to 8 bytes.

Further, the data arranged in the data area DTA is formatted into a sector composed of a header area of 24 bytes and a user data area of 584 bytes, for example, as shown in FIG. In the header area, for example, a sector mark indicating the start position of a sector and a recording track T in which each sector is arranged
K identification information (track number), its recording track TK
Identification information such as sector identification information (sector address) is placed. Further, user data in an arbitrary information format is arranged in the user data area.

Now, of the servo information arranged in the servo area SBA, an example of tracking information is shown in FIG. 7 (a).
Shown in.

This tracking information is recorded on the recording track T.
The wobble pits Pa and Pb are arranged in a zigzag pattern with the center LC of K interposed therebetween, and the clock pits Pc are arranged at the center LC of the recording track TK.

As shown in FIG. 3A, reproduction is performed when the movement locus RBa of the laser beam coincides with the center LC and when the laser beam passes over the wobble pits Pa and Pb. Level LAa appearing in the signal,
LBa (see (b) in the figure) is at the same level.

Further, as shown in FIG. 8A, when the movement locus RBb of the laser beam is displaced toward the wobble pit Pb side from the center LC, as shown in FIG. The level LAb appearing in the reproduction signal when passing over the wobble pit Pa is smaller than the level LBb appearing in the reproduction signal when the laser beam passes over the wobble pit Pb.

On the contrary, as shown in FIG. 9A, when the movement locus RBb of the laser beam is displaced to the wobble pit Pa side from the center Lc, as shown in FIG. The level LAb appearing in the reproduction signal when the laser beam passes over the wobble pit Pa is larger than the level LBb appearing in the reproduction signal when the laser beam passes over the wobble pit Pb.

Therefore, by detecting the level LA and the level LB and calculating the difference dL between them, it is possible to obtain the amount of displacement of the movement locus RB of the laser beam from the center LC, that is, the tracking error.

The clock pit Pc is used as follows. That is, when the laser beam is passing over the clock pit Pc, the peak appearing in the reproduction signal is detected, and the system clock that defines the reference timing for sampling the data appearing in the reproduction signal based on the detection timing. Control the synchronization state of. Normally, the detection signal of the clock pit Pc is set to P
By inputting to the LL (phase locked loop) circuit, the PLL
System clock output from the circuit is clock pit P
The phase is synchronized with c.

Then, the detection timing of the wobble pits Pa and Pb is formed based on this system clock, and the reproduced signal is sampled at the detected timing to detect the levels LA and LB appearing in the reproduced signal. The difference between the detected values of the levels LA and LB is calculated,
It forms the tracking error signal.

[0014]

However, the above-mentioned conventional technique has the following disadvantages.

That is, a jitter component due to noise is generated in the reproduced signal, or the phase synchronization of the PLL circuit that forms the system clock is deviated, so that FIG.
As shown in (d), the sampling timing of the levels LA and LB may be shifted by the time ZT.

Here, the levels LA and LB of the reproduced signal when the wobble pits Pa and Pb are detected change suddenly so that one peak appears at the central position of the wobble pits Pa and Pb. Therefore, as described above, when the sampling timing is shifted to the front (or the rear), the sampled values of the levels LA and LB at that time are smaller than the peak and smaller than the difference value dL.

As a result, even if the amount of positional deviation of the laser beam with respect to the center LC is the same, if the sampling timing deviates back and forth, the tracking error signal will have a smaller value than in the case of optimal sampling timing.

In this way, if the tracking error signal contains an error component, the tracking servo control for causing the laser beam to follow the center LC of the recording track cannot be operated stably. ..

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide an optical pickup device capable of accurately detecting a tracking error signal and stably performing tracking servo control, and a control method thereof. Has a purpose.

[0020]

DISCLOSURE OF THE INVENTION The present invention provides an optical disc device using as an recording medium an optical disc in which servo information consisting of at least two wobble pits for detecting a tracking error is recorded in advance on recording tracks at predetermined intervals. In the above, a timing generating means for generating a first gate signal and a second gate signal respectively representing the detection timings of the two wobble pits based on the reproduction signal from the recording medium, and a differentiating circuit for differentiating the reproduction signal. A binarization circuit that binarizes the output signal of the differentiating circuit to form a pulse signal; and a first bin that allows the pulse signal to pass during the period in which the first gate signal is being output from the timing generation means. During the period in which the second gate signal is output from the gate circuit and the timing generating means, A second gate circuit for passing the input signal, a first sample / hold circuit for sampling and holding the level of the reproduction signal at the rising edge of the output signal of the first gate circuit, and the second gate A second sample / hold circuit for sampling and holding the level of the reproduction signal at the rising edge of the output signal of the circuit, a holding output of the first sample / hold circuit and a holding of the second sample / hold circuit It is provided with a subtractor that calculates the difference between the outputs and outputs it as a tracking error signal.

Further, in an optical disc apparatus which uses as an recording medium an optical disc in which servo information consisting of at least two wobble pits for detecting a tracking error is recorded on recording tracks in advance at predetermined intervals, reproduction from the recording medium is performed. Timing generating means for generating a first gate signal and a second gate signal, which respectively represent the detection timings of the two wobble pits based on the signal, and a differentiating circuit for differentiating the reproduced signal,
A binarization circuit that binarizes the output signal of the differentiating circuit to form a pulse signal, and a first gate circuit that passes the pulse signal during a period in which the first gate signal is being output from the timing generation means. A second gate circuit that allows the pulse signal to pass through while the second gate signal is being output from the timing generation means; and the level of the reproduction signal at the rising edge of the output signal of the first gate circuit. A first sample / hold circuit for sampling and holding, a subtractor for calculating the difference between the held output of the first sample / hold circuit and the reproduced signal, and the rise of the output signal of the second gate circuit. A second sample / hold circuit for sampling and holding the output signal of the subtractor at its end and outputting the held signal as a tracking error signal It is intended.

In addition, in the control method of the optical disk device, an optical disk in which servo information including at least two wobble pits for detecting a tracking error is recorded on a recording track in advance at a predetermined interval is used as the recording medium. A first gate signal and a second gate signal which respectively represent the detection timings of the two wobble pits on the basis of the reproduction signal, and a differential pulse of the reproduction signal from the first gate signal. Difference between the level of the reproduction signal sampled at the rising edge of the differential pulse obtained at the output timing of 1 and the level of the reproduction signal sampled at the rising edge of the differential pulse obtained at the output timing of the second gate signal Form a tracking error signal based on It is obtained by way.

[0023]

Therefore, since the level of the reproduction signal can be accurately sampled at the timing when the wobble pit component appears in the reproduction signal, the tracking error signal can be formed with high accuracy and the stable tracking servo control operation can be performed. Can be done.

[0024]

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

FIG. 1 shows a tracking error signal forming circuit according to an embodiment of the present invention. It should be noted that this embodiment is applied to an optical disc device using an optical disc to which tracking information having the same configuration as that described in the section of the related art is applied as a recording medium.

In FIG. 1, a reproduction signal RF obtained from an optical pickup device (not shown) for recording / reproducing (/ erasing) data on / from an optical disc includes a sample / hold circuit 1, a sample / hold circuit 2 and a differentiating circuit. 3 and the clock pit detection circuit 4.

The differentiating circuit 3 is for differentiating the reproduction signal RF, and its output signal is added to the binarizing circuit 5. The binarization circuit 5 outputs a signal of logic H level when the level of the input signal is 0 or more, and outputs a signal of logic L level when the level of the input signal is smaller than 0.
The output signal of the binarization circuit 5 is a binarized pulse signal PP.
Is added to switches 6 and 7.

The clock pit detecting section 4 reproduces the reproduction signal RF.
The signal component of the clock pit Pc included in the reproduction signal RF is detected based on the above, and when the signal component of the clock pit Pc is detected, the clock pit pulse P
K is formed and output to the PLL circuit 8 and the counter 9. The clock pit detection unit 4 detects, for example, a sector mark component appearing in the reproduction signal RF, and a signal component of the clock pit Pc that appears periodically is peaked at a timing when a certain time has elapsed from the detection timing. It is detected using a technique such as detection.

The PLL circuit 8 uses the clock pit pulse P
It forms a system clock CKs that is phase-synchronized with K. The system clock CKs is a counter 9
Has been added to.

The counter 9 counts the system clock CKs, and based on the count value, the byte number data N indicating the byte position of the input data.
Bt and bit number data NBb representing the bit position are formed, and the byte number data NBt and the bit number data NBb are output to the decoder 10. Further, the operation of the counter 9 is based on the clock pit pulse P
It is reset at the rising edge of K.

The decoder 10 uses the byte number data NBt.
And the reproduction signal R based on the bit number data NBb
A gate signal GTa representing the detection prediction timing of the wobble pit Pa appearing in F and a reproduction signal RF
A gate signal GTb representing the detection prediction timing of the wobble pit Pb appearing in the gate signal GTa is added to the control input terminal of the switch 6, and the gate signal GTb is applied to the control input terminal of the switch 7. Added.

The switch 6 has a gate signal G at its control input terminal.
It is turned on while Ta is being added,
When the binarized pulse signal PP is added during the ON operation, the binarized pulse signal PP is converted into the wobble pit Pa.
Is applied to the control input terminal of the sample / hold circuit 1 as a pulse signal PPa representing the detection timing of.

The switch 7 has a gate signal G at its control input terminal.
It is turned on while Tb is added,
When the binarized pulse signal PP is added during the ON operation, the binarized pulse signal PP is converted into the wobble pit Pb.
Is applied to the control input terminal of the sample / hold circuit 2 as a pulse signal PPb representing the detection timing of.

The sample / hold circuit 1 receives the pulse signal PPa when the pulse signal PPa is applied to its control input terminal.
At the rising edge of Pa, the level of the input reproduction signal RF is sampled and held, and the held signal is added to the plus side input terminal of the subtractor 11 as the detection value SPa of the wobble pit Pa.

The sample / hold circuit 2 receives the pulse signal Pb when the pulse signal PPb is applied to its control input terminal.
At the rising edge of Pb, the level of the input reproduction signal RF is sampled and held, and the held signal is used as the detection value SPb of the wobble pit Pb by the subtracter 1
1 is added to the negative input terminal.

The subtractor 11 subtracts the detection value SPb applied to the minus input terminal from the detection value SPa applied to the plus input terminal, and the subtraction result is the tracking error signal ET. Is output to the next-stage device.

With the above configuration, when the reproducing operation of the optical pickup device is performed, the reproduction signal R is output from the optical pickup device.
F is output, whereby the detection operation of the clock pit detector 4 is started, and then the synchronous pull-in operation of the PLL circuit 8 is started. When the synchronization pull-in of the PLL circuit 8 is completed, the following operation is performed every time the optical pickup device detects the tracking information, and the tracking error signal ET is obtained.

That is, at this time, as shown in FIG.
As shown in (g), the decoder 10 outputs gate signals GTa and GTb having pulse widths corresponding to three channel clocks at the detection prediction timings of the wobble pits Pa and Pb (see FIG. 9A). It

On the other hand, when the optical pickup device detects the wobble pit Pa, a reproduction signal RF (see FIG. 9B).
Shows a level change that falls from the start end of the wobble pit Pa and has a peak in the center.

Due to this level change, the output signal of the differentiating circuit 3 (see (c) in the figure) changes to the minus side at the start end of the wobble pit Pa, and becomes 0 level at the timing when the central position is detected. After that, the level changes to the plus side and returns to 0 at the end end.

As a result, the binarized pulse signal PP output from the binarization circuit 5 (see (d) in the figure) changes to the logical H level from the center position detection timing of the wobble pit Pa to the end edge detection timing. The pulse signal changes.

On the other hand, at this time, since the gate signal GTa is output, the switch 6 is in the ON operation,
As a result, the binarized pulse signal PP output from the binarization circuit 5 is applied to the sample / hold circuit 1 via the switch 6 as the pulse signal PPa (see (f) in the figure).

As a result, the sample / hold circuit 1
For sampling and holding the reproduction signal RF at the peak timing of the wobble pit Pa. Therefore, the sample / hold circuit 1 holds a level corresponding to the peak value when the optical pickup device detects the wobble pit Pa, and this held level is used as a detection value SPa (see (i) in the figure) for subtraction. 11 to the positive input terminal.

When the optical pickup device detects the wobble pit Pb, the reproduction signal RF has a level change that falls from the start end of the wobble pit Pb and has a peak at the center.

Due to this level change, the output signal of the differentiating circuit 3 changes to the minus side at the start end of the wobble pit Pb, becomes 0 level at the timing when the center position is detected, and thereafter changes to the plus side. At the end, a level change that returns to 0 appears.

As a result, the binarized pulse signal PP output from the binarization circuit 5 becomes a pulse signal that changes to the logical H level from the central position detection timing of the wobble pit Pb to the end edge detection timing.

On the other hand, at this time, since the gate signal GTb is being output, the switch 7 is in the ON operation,
As a result, the binarized pulse signal PP output from the binarization circuit 5 is applied to the sample / hold circuit 2 via the switch 7 as a pulse signal PPb (see (h) in the figure).

As a result, the sample / hold circuit 2
For sampling and holding the reproduction signal RF at the peak timing of the wobble pit Pb. Therefore, the sample / hold circuit 2 holds a level corresponding to the peak value when the optical pickup device detects the wobble pit Pb, and this held level is added to the minus side input end of the subtractor 11 as the detected value SPb. Be done.

Therefore, the value of the tracking error signal ET (see (k) in the figure) output from the subtractor 11 is the wobble pits Pa and Pb of the same tracking information in the period Tb after the detection timing of the wobble pit Pb.
It corresponds to the difference value of the detection level.

In this way, in this embodiment, since the level change of the signal components of the wobble pits Pa and Pb appearing in the reproduction signal RF is detected and the reproduction signal RF is sampled based on the detection timing, the wobble is generated. The signal components of the pits Pa and Pb can be accurately sampled.

Further, the gate signals GTa and GTb can be generated with a wide pulse width corresponding to three channel clocks, and the signal components of the wobble pits Pa and Pb can be obtained even when the timing accuracy of the gate signals GTa and GTb is poor. Can be properly sampled. That is, for example, PLL
The circuit 8 may be out of phase synchronization, or the reproduction signal RF may have a jitter component caused by noise.
Even if the timing relationship between the a and GTb and the binarized pulse signal PP is slightly deviated, the pulse signals PPa and PPb can be added to the sample / hold circuits 1 and 2 at the optimum timings, so tracking without error is performed. The error signal ET can be formed.

By the way, in the above embodiment, the tracking error signal ET is detected in the period Tab from the detection of the wobble pit Pa to the detection of the wobble pit Pb.
Takes an intermediate value (see FIG. 2 (k)).

That is, in this case, even if the wobble pit Pa is detected and the detection value SPa applied to the plus side input end of the subtractor 11 is updated to the new tracking information value, the sample / hold circuit Since the value of the previous tracking information is held in 2, the period Tab corresponds to the detection value SPa corresponding to the wobble pit Pa of the new tracking information and the wobble pit Pb of the immediately previous tracking information. The tracking error signal ET corresponding to the difference value of the detected value SPb is output.

Therefore, the tracking error signal ET in this period Tab is not an appropriate value. However, in practice, when the tracking error signal ET changes in the same direction, even if the tracking error signal ET takes such an intermediate value, it has no effect on the tracking servo control. .. Further, even when the tracking error signal ET changes in different directions, such an intermediate value appears for a very short period of time, so that the influence on the tracking servo control is small and no problem occurs.

FIG. 3 shows a tracking error signal forming circuit according to another embodiment of the present invention. In this embodiment, an intermediate value is prevented from appearing in the tracking error signal ET, and the same parts as those in FIG. 1 and corresponding parts are designated by the same reference numerals.

In the figure, the detection value SPa output from the sample / hold circuit 1 is added to the plus side input end of the subtractor 15, and the reproduction signal RF is given to the minus side input end of the subtractor 15. Has been added. Subtractor 15
Is to subtract the level of the reproduction signal RF applied to the minus side input end from the detected value SPa applied to the plus side input end, and the subtraction result is the sample / hold circuit as the difference signal DS. Added to 16.

The sample / hold circuit 16 receives the pulse signal PPb output from the switch 7 at its control input terminal, and samples and holds the input differential signal DS at the rising edge of the pulse signal PPb. The holding output is the tracking error signal ET.
Is output to the next stage device.

With the above configuration, when the reproducing operation of the optical pickup device is performed, the reproduction signal R is output from the optical pickup device.
F is output, whereby the detection operation of the clock pit detector 4 is started, and then the synchronous pull-in operation of the PLL circuit 8 is started. When the synchronization pull-in of the PLL circuit 8 is completed, the following operation is performed every time the optical pickup device detects the tracking information, and the tracking error signal ET is obtained.

That is, at this time, FIG.
As shown in (g), the decoder 10 outputs gate signals GTa and GTb having pulse widths corresponding to three channel clocks at the detection prediction timings of the wobble pits Pa and Pb (see FIG. 9A). It

On the other hand, when the optical pickup device detects the wobble pit Pa, a reproduction signal RF (see FIG. 9B).
Shows a level change that falls from the start end of the wobble pit Pa and has a peak in the center.

Due to this level change, the output signal of the differentiating circuit 3 (see (c) in the figure) changes to the minus side at the start end of the wobble pit Pa, and becomes 0 level at the timing when the central position is detected. After that, the level changes to the plus side and returns to 0 at the end end.

As a result, the binarized pulse signal PP output from the binarization circuit 5 (see (d) in the figure) changes to the logical H level from the center position detection timing of the wobble pit Pa to the end edge detection timing. The pulse signal changes.

On the other hand, at this time, since the gate signal GTa is being output, the switch 6 is in the ON operation,
As a result, the binarized pulse signal PP output from the binarization circuit 5 is applied to the sample / hold circuit 1 via the switch 6 as the pulse signal PPa (see (f) in the figure).

As a result, the sample / hold circuit 1
For sampling and holding the reproduction signal RF at the peak timing of the wobble pit Pa. Therefore, the sample / hold circuit 1 holds a level corresponding to the peak value when the optical pickup device detects the wobble pit Pa, and this held level is used as a detection value SPa (see (i) in the figure) for subtraction. 15 plus input terminal.

After that, since the signal component level of the wobble pit Pa of the new tracking information is added to the plus side input terminal of the subtractor 15, the difference signal DS output from the subtractor 15 (see FIG. In j), the result of subtracting the value of the reproduction signal RF from the signal component level of the wobble pit Pa appears.

When the optical pickup device detects the wobble pit Pb, the reproduction signal RF has a level change that falls from the start end of the wobble pit Pb and has a peak at the center.

Due to this level change, the output signal of the differentiating circuit 3 changes to the minus side at the start end of the wobble pit Pb, becomes 0 level at the timing when the center position is detected, and changes to the plus side thereafter. At the end, a level change that returns to 0 appears.

As a result, the binarized pulse signal PP output from the binarization circuit 5 becomes a pulse signal that changes to the logical H level from the central position detection timing of the wobble pit Pb to the end edge detection timing.

On the other hand, at this time, since the gate signal GTb is output, the switch 7 is in the ON operation,
As a result, the binarized pulse signal PP output from the binarization circuit 5 is added to the sample / hold circuit 16 via the switch 7 as a pulse signal PPb (see (h) in the figure).

At this time, the difference signal DS output from the subtractor 15 corresponds to the difference value between the detection value SPa of the signal component level of the wobble pit Pa and the reproduction signal RF at the peak timing of the wobble pit Pb. A value appears, and this value is sampled and held in the sample / hold circuit 16.

As a result, the value of the tracking error signal ET (see (k) in the figure) output from the sample / hold circuit 16 is the wobble pit Pa of the same tracking information in the period Td after the detection timing of the wobble pit Pb. , Pb corresponding to the difference value between the detection levels.

Further, before this period Td, the value of the tracking error signal ET corresponds to the difference value between the detection levels of the wobble pits Pa and Pb in the immediately preceding tracking information.

In this way, in this embodiment, since the intermediate value does not appear in the value of the tracking error signal ET, it is not necessary to consider the influence on the tracking servo control as in the above-mentioned embodiments.

The present invention is not limited to the servo information format and the recording track format of the above-described embodiment.

[0075]

As described above, according to the present invention,
Since the level of the reproduction signal can be accurately sampled at the timing when the wobble pit component appears in the reproduction signal, the tracking error signal can be formed with high accuracy and stable tracking servo control operation can be performed. Get the effect.

[Brief description of drawings]

FIG. 1 is a block diagram showing a tracking error signal forming circuit according to an embodiment of the present invention.

FIG. 2 is an operation waveform diagram for explaining the operation of the apparatus shown in FIG.

FIG. 3 is a block diagram showing a tracking error signal forming circuit according to another embodiment of the present invention.

4 is an operation waveform diagram for explaining the operation of the apparatus shown in FIG.

FIG. 5 is a schematic view illustrating a recording track structure of an optical disc.

FIG. 6 is a schematic diagram showing an example of a relationship between a servo area and a data area and a sector format.

FIG. 7 is an explanatory diagram for explaining the principle of sampling servo.

FIG. 8 is an explanatory diagram for explaining the principle of sampling servo.

FIG. 9 is an explanatory diagram for explaining the principle of sampling servo.

FIG. 10 is an explanatory diagram for explaining inconvenience of the conventional device.

[Explanation of symbols]

 1, 2 and 16 sample / hold circuit 3 differentiating circuit 4 clock pit detecting section 5 binarizing circuit 6, 7 switch 8 PLL circuit 9 counter 10 decoder 11 and 16 subtractor

Claims (3)

[Claims] 1. An optical disc apparatus using an optical disc as a recording medium, wherein an optical disc in which servo information including at least two wobble pits for detecting a tracking error is recorded on a recording track in advance at a predetermined interval,
Timing generating means for generating a first gate signal and a second gate signal which respectively represent the detection timings of the two wobble pits based on the reproduction signal from the recording medium, and a differentiation circuit for differentiating the reproduction signal, A binarization circuit that binarizes the output signal of the differentiating circuit to form a pulse signal, and a first gate circuit that passes the pulse signal during a period in which the first gate signal is being output from the timing generation means. A second gate circuit that allows the pulse signal to pass while the second gate signal is being output from the timing generating means; and the level of the reproduction signal at the rising edge of the output signal of the first gate circuit. Of the reproduction signal at the rising edge of the output signal of the first gate / hold circuit and the second gate circuit for sampling and holding A second sample / hold circuit samples and holds the bell, the first sample /
An optical disk device comprising a subtractor for calculating a difference between a hold output of a hold circuit and a hold output of the second sample / hold circuit and outputting the difference as a tracking error signal. 2. An optical disk device using an optical disk, as a recording medium, in which servo information including at least two wobble pits for detecting a tracking error is recorded in a recording track in advance at predetermined intervals.
Timing generating means for generating a first gate signal and a second gate signal which respectively represent the detection timings of the two wobble pits based on the reproduction signal from the recording medium, and a differentiation circuit for differentiating the reproduction signal, A binarization circuit that binarizes the output signal of the differentiating circuit to form a pulse signal, and a first gate circuit that passes the pulse signal during a period in which the first gate signal is being output from the timing generation means. A second gate circuit that allows the pulse signal to pass while the second gate signal is being output from the timing generating means; and the level of the reproduction signal at the rising edge of the output signal of the first gate circuit. Sample / hold circuit for sampling and holding the signal, and the difference between the holding output of the first sample / hold circuit and the reproduction signal. And a second sample / hold circuit that samples and holds the output signal of the subtractor at the rising edge of the output signal of the second gate circuit and outputs the held signal as a tracking error signal. An optical disk device characterized by being provided. 3. A control method of an optical disk device, wherein an optical disk, in which servo information including at least two wobble pits for detecting a tracking error is recorded on a recording track in advance at a predetermined interval, is used as a recording medium. And a first gate signal and a second gate signal respectively representing the detection timings of the two wobble pits are formed based on the reproduction signal.
Of the level of the reproduction signal sampled at the rising edge of the differential pulse obtained at the output timing of the gate signal and the level of the reproduction signal sampled at the rising edge of the differential pulse obtained at the output timing of the second gate signal A method for controlling an optical disk device, wherein a tracking error signal is formed based on a level difference.