JPH11339286A - Optical disk drive method and optical disk device thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical disk drive method and an optical disk device, capable of precisely measuring a DC offset contained in a tracking error signal. SOLUTION: This optical disk drive method is c provided with a means for forming a push-pull error signal PP from the differential signal of a split light receiving part by reflected light from the optical disk of a light spot, a top hold circuit 2 for holding the top peak value of the push-pull error signal PP, a bottom hold circuit 3 for holding the bottom peak value of the push-pull error signal PP, and an arithmetic circuit 4 for calculating the average of the top and bottom values; and the balance of the optical spot can be adjusted by performing tracking servo, while the offset value K based on the average is removed from the push-pull error signal PP.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk drive method and a disk device, for example, a mini disk (MD) and a compact disk (C) as disc-shaped recording media.
D) It can be applied to a tracking servo when recording or reproducing information recorded on a digital video disk (DVD).

[0002]

2. Description of the Related Art Conventionally, in an optical disk apparatus for recording information on an optical disk or reproducing information recorded on the optical disk, an optical pickup is positioned with respect to the optical disk to reproduce the information. In this case, a tracking error signal is generated by various tracking methods separately from the reproduction signal, and the tracking error signal is used for positioning in the cross-track direction.

[0003] As a first method of the tracking method, two sides of the main spot, which are not diffracted in the cross-track direction from the reflected light of the optical spot from the optical disc, are diffracted in the cross-track direction on the outer circumference or the inner circumference, respectively. There is a three-spot method for generating a three-spot tracking error signal indicating a deviation between a main spot and a track from a spot difference signal.

[0004] As a second method of the tracking system, a PP (push-pull) error signal which indicates a deviation from a track is generated from a difference signal of one spot divided light receiving portion from a reflected light of an optical spot from an optical disk. Pull) method.

Japanese Unexamined Patent Publication No. 9-320067 discloses a technique in which a peak hold circuit detects and stores a top peak value and a bottom peak value of an error signal output from an AGC, and furthermore, stores both peak values in a step calculating circuit. There is disclosed an optical recording / reproducing apparatus for adjusting an offset value so as to eliminate the difference between the two, and a method for determining the offset value.

Japanese Patent Application Laid-Open No. Hei 6-282859 discloses that an optical detector is divided into a plurality of portions, and a position signal of an optical spot is formed from a detector light receiving output of each portion to perform accurate tracking control with one beam. A tracking servo device of an optical recording / reproducing device for performing the operation is disclosed.

[0007]

In the above-described light detecting device using the three spot method in the conventional optical disk device, a thread (feed) error signal is detected with the focus servo turned on, and this is converted into a tracking error signal. The balance adjustment of the tracking error signal was performed on the assumption that the DC offset was included. In the above-described method, the AC component included in the thread error signal increases near the turning point of the traverse signal (AC component of the reproduced RF signal) due to disk eccentricity. For this reason, in order to avoid erroneous measurement of the tracking error signal by the A / D converter or the like, the frequency of the traverse signal is increased by intentionally vibrating the two-axis actuator in the tracking direction, and exceeds a preset threshold value. Measures such as measuring only frequency components have been taken.

However, in the tracking method based on the one-spot push-pull method, since the movement of the objective lens in the tracking direction directly becomes an offset of the tracking error signal, the above-described means cannot be used. Further, since the followability of the thread servo is deteriorated, the cutoff frequency of the low-pass filter for the thread error signal cannot be extremely reduced. For this reason,
The conventional tracking method has a disadvantage that it is difficult to accurately measure a DC offset included in a tracking error signal using an A / D converter or the like.

Another problem to be solved by the optical recording / reproducing apparatus and its offset value determining method described in Japanese Patent Application Laid-Open No. 9-320067 is a focus error (or tracking error) caused by a difference in the light beam quantity. It is to remove the difference between the signal offsets. In order to achieve this, an AGC absorbs an offset difference proportional to the light amount at the time of erasing and reading, and detects and removes an offset that cannot be removed by the AGC (not proportional to the light amount). An offset value determining method is disclosed.

However, the offset itself caused by a certain amount of light generated in the tracking error signal due to the variation of the light receiving sensitivity of the photodetector, the displacement of components constituting the optical pickup, and the electrical offset generated in the amplification / arithmetic circuit. Cannot be removed,
There was a disadvantage that stable tracking servo could not be performed. SUMMARY OF THE INVENTION It is an object of the present invention to remove an offset itself that occurs in a tracking error signal and occurs at a certain light amount.

The method of the optical recording / reproducing apparatus and its offset value determining method described in Japanese Patent Application Laid-Open No. 9-320067 alternately switches the laser power to the power at the time of erasing / reading, and at this time, the signal is output from the AGC. The top and bottom peak values immediately after switching of the focus error (or tracking error) signal are detected and stored by a peak hold circuit, and the offset value is adjusted so as to eliminate the difference between the two peak values.
In other words, a transient phenomenon caused by applying a disturbance with the servo loop closed, that is, immediately after switching the laser power, the offset generated in the error signal is captured in a transient state to calculate the offset. .

However, when only the focus servo is started, the light spot is included in the tracking error signal due to the influence of the disk eccentricity.
A traverse signal that appears when the signal crosses the tracking error signal appears. However, as described above, the traverse signal in the tracking error signal may include an offset, and the tracking servo cannot be started stably as it is. In order to accurately on-track the light spot,
It is necessary to set the target value of the tracking servo at the center of the traverse signal. However, since there is no means for detecting the center position of the traverse signal modulated at a certain frequency, there is an inconvenience that stable tracking servo cannot be performed. Was. An object of the present invention is to remove an offset of a tracking error signal when a tracking servo is open.

The circuit configuration of the optical recording / reproducing apparatus and its offset value determining method described in Japanese Patent Application Laid-Open No. 9-320067 aims to normalize a focus error (or tracking error) signal with the total light amount. A peak hold circuit is connected to the AGC output, and the offset value in the laser power at the time of erase / read (this is called a top peak value and a bottom peak value).
Is detected. The difference between the offset values at this time is calculated by the next-stage difference calculation circuit, and based on this value,
The offset value is adjusted so that the difference between the top peak value and the bottom peak value at the time of reading is eliminated.

However, unless the top and bottom peak values of the traverse signal itself appearing in the tracking error signal are detected and the offset amount of the traverse signal is calculated from these two peak values, the tracking servo is started stably. There was an inconvenience that I could not do it. An object of the present invention is to perform offset adjustment of a tracking error signal by means for detecting a top peak value and a bottom peak value of a traverse signal itself, and means for calculating an offset amount of the traverse signal from two peak values. I do.

The tracking servo device of the optical recording / reproducing apparatus described in Japanese Patent Application Laid-Open No. 6-282859 cancels an offset caused by an objective lens by a one-beam push-pull tracking method. In some cases, the traverse signal in the tracking error signal includes an offset, and if this is the case, the tracking servo cannot be started stably.

The present invention has been made in view of the above points, and it is an object of the present invention to propose an optical disk drive method and an optical disk apparatus that can accurately measure a DC offset included in a tracking error signal.

[0017]

According to the present invention, there is provided an optical disk driving method for irradiating a land or a groove formed on an optical disk with an optical spot by using an optical pickup. In an optical disk drive method for recording information or performing tracking of an optical pickup for reproducing information, a deviation between the light spot and a track is indicated from a difference signal of a divided light receiving portion due to reflected light of the light spot from the optical disk. A push-pull error signal generating means for generating a push-pull error signal; a top hold means for holding a top peak value of the push-pull error signal; a bottom hold means for holding a bottom peak value of the push-pull error signal; Top peak value and above Average calculation means for calculating an average value of the tom peak value, wherein an offset based on the average value is removed from the push-pull error signal, so that the tracking servo is provided at one of the land and groove positions. Is performed to drive the optical pickup.

Further, the optical disk apparatus of the present invention irradiates a laser spot to a pit or groove formed on the optical disk by an optical pickup,
In an optical disc apparatus that reproduces information by recording information in the pits or the grooves or by performing tracking of an optical pickup for reproducing the information, a difference signal of a divided light receiving portion due to reflected light of the light spot from the optical disc. A push-pull error signal generating means for generating a tracking error signal indicating a deviation between the light spot and the track, a top-hold means for holding a top peak value of the push-pull error signal, and a bottom peak of the push-pull error signal. Bottom hold means for holding the value, average value calculation means for calculating the average value of the top peak value and the bottom peak value, and removing the offset based on the average value from the push-pull error signal, Land or groove In one position, and a driving means for driving the optical pickup so as to perform tracking servo, in which to perform the tracking of the optical pickup.

According to the optical disk device of the present invention, the following operations are performed. A laser beam is emitted from an optical pickup to an optical disk rotated by a spindle motor servo-controlled by a spindle servo system. After the focus servo controlled by the focus servo system is turned on, the drive signal from the tracking servo circuit is applied to the tracking coil of the biaxial actuator of the optical pickup, and when the actuator is moving in the track direction, the drive signal from the optical disc is The detection signal is detected from the photodetector by the reflected light.

The push-pull signal generated based on the difference between the detection signals of the divided light receiving units from the photo detector is supplied to the top hold means and the bottom hold means.
The top hold means holds the top peak value of the traverse signal included in the push-pull signal at a predetermined sampling timing. Also, the bottom hold means,
The bottom peak value of the traverse signal included in the push-pull signal is held at the same sampling timing as the above-described top hold means.

An operation of adding the top peak value held by the top hold means and the bottom peak value held by the bottom hold means to halve the addition value is performed to calculate the top peak value and the bottom peak value. Is calculated. The average value output signal is output as a DC offset signal of the traverse signal included in the push-pull signal.

Thus, when the light spot crosses the track, the top peak value and the bottom peak value of the traverse signal generated in the push-pull signal are held, and the center value of the top peak value and the bottom peak value is detected. Output.

Here, by optimizing the time constant of the sampling hold of the top hold means and the bottom hold means, the DC offset signal can be sufficiently smoothed to the extent that it can be detected by an A / D converter or the like.

Further, the offset is removed from the push-pull signal based on the offset value derived from the DC offset signal, and the push-pull signal from which the offset has been removed is supplied again to the top hold means and the bottom hold means. Output as tracking error signal.

The tracking error signal is used as a tracking actuator drive signal, and is applied to a tracking coil of a two-axis actuator of the optical pickup.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an optical disc device according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. First,
Before describing the present embodiment, a description will be given of a photodetector (PD) pattern and generation of a push-pull signal, which are presupposed.

First, the arrangement of the light receiving section of the detector of the optical disk recording / reproducing apparatus will be described with reference to FIG. In FIG. 3, a photodetector (PD) 5 includes a four-divided light receiving unit A
B and C and D are symmetrically arranged with respect to the light spot of the return light from the track center. The photodetector (PD) 5 has division surfaces in the radial direction of the disc, and receives light spots A,
The four-divided light receiving units B, C, and D are arranged so as to be shifted by a 1/4 track pitch with respect to the light spot of the return light from the track center so as to be optimal for the push-pull method.

Next, an example of generating a push-pull signal will be described with reference to FIG. In FIG. 4A, an addition signal A + B of the detection signals of A and B of the four-division light receiving unit and an addition signal C + D of the detection signals of C and D of the four-division light receiving unit are added input terminals of the arithmetic circuit 6 respectively. And a subtraction input terminal to generate a push-pull signal PP of (A + B)-(C + D). In this manner, (A + B)-(C + D), which is the difference between A + B and C + D of the detection signal of the photodetector (PD) 5, can be used as the push-pull signal PP for the tracking servo.

Next, in FIG. 4B, an addition signal A + B of the detection signals of A and B of the four-division light receiving unit and an addition signal C + D of the detection signals of C and D of the four-division light receiving unit are calculated respectively. The operation signal (A + B)-(C + D) is generated by being supplied to the addition input terminal and the subtraction input terminal of the circuit 7, and this operation signal (A + B)-(C + D) and A, B, C Signal A + B of the detection signals of D and D
+ C + D are supplied to the addition input terminal and the subtraction input terminal of the arithmetic circuit 8, respectively, to obtain ｛(A + B) − (C +
D) A push-pull signal PP of｝ / (A + B + C + D) is generated. Thus, the photodetector (P
D) The difference between A + B and C + D of the detection signal of 5 (A)
+ (B) − (C + D) divided by the total amount of light (A + B + C + D) received by the photodetector (PD) 5, thereby normalizing {(A + B) − (C + D)} / (A +).
B + C + D) can be used for the tracking servo as the push-pull signal PP.

Here, ideally, the position of the light spot of the return light from the optical disk is determined by the photo detector (PD) 5.
When the center position of A, B, C, and D of the four-divided light receiving unit is located, the output levels of A, B, C, and D of the four-divided light receiving unit of the photodetector (PD) 5 become equal.

However, actually, the photodetector (P
D) The photodetector is affected by variations in the light receiving sensitivity of A and B and C and D of the four-divided light receiving unit of 5, the displacement of components constituting the optical pickup, the influence of electrical offset generated in the amplifier circuit and the arithmetic circuit, and the like. (PD) 4 of 5
The output levels of A and B and C and D of the divided light receiving units are not equal.

Therefore, these photodetectors (PD)
A DC offset occurs in the push-pull signal PP of (A + B)-(C + D) generated by the difference between A and B and C and D of the four-divided light receiving unit of No. 5. If the push-pull signal PP is used as it is as a tracking error signal for the tracking servo, the tracking servo is started in a so-called detrack state where the light spot is not positioned at the center of the target track. Therefore, a DC offset included in the push-pull signal PP is canceled in advance by using a tracking error offset cancel circuit described later.

FIG. 1 is a block diagram showing a configuration of a tracking error offset cancel circuit applied to the optical disk recording / reproducing apparatus according to the present embodiment. A laser beam is emitted from an optical pickup to an optical disk rotated by a spindle motor servo-controlled by a spindle servo system (not shown). After turning on a focus servo controlled by a focus servo system (not shown), the drive signal from the tracking servo circuit is amplified by an amplifier and applied to the tracking coil of the biaxial actuator of the optical pickup, and the actuator moves in the track direction. In this case, a detection signal is detected from the photodetector (PD) 5 by the reflected light from the optical disk.

The photodetector (P) shown in FIG.
D) (A + B)-(C + D) generated from the difference between the detection signals of A and B and C and D of the 4-divided light receiving unit from 5
Or the push-pull signal PP of {(A + B)-(C + D)} / (A + B + C + D) shown in FIG. 4B is supplied to one addition input terminal of the arithmetic circuit 1 shown in FIG. Is done. The output signal of the arithmetic circuit 1 is supplied to the top hold circuit 2 and the bottom hold circuit 3. The top hold circuit 2 has a push-pull signal P
This circuit holds the top peak value of the traverse signal indicating the AC component included in P at a predetermined sampling timing. The bottom hold circuit 3 is a circuit that holds the bottom peak value of the traverse signal indicating the AC component included in the push-pull signal PP at the same sampling timing as the above-described top hold circuit 2. Here, the top hold circuit 2 and the bottom hold circuit 3
The sampling and holding are optimized by making it possible to adjust the time constant when sampling and holding the top peak value and the bottom peak value in.

The top peak value held by the top hold circuit 2 is supplied to one addition input terminal of the arithmetic circuit 4. The bottom peak value held by the bottom hold circuit 3 is supplied to the other addition input terminal of the arithmetic circuit 4. The arithmetic circuit 4 performs an operation of adding the top peak value and the bottom peak value to reduce the added value to 値, and performs an average value calculation of the top peak value and the bottom peak value.
The average value output signal of the arithmetic circuit 4 is a push-pull signal PP
Is output as a DC offset signal CSL of a traverse signal indicating the AC component included in the.

As described above, the tracking error offset cancel circuit shown in FIG.
This is a circuit for outputting a DC offset signal CSL of a traverse signal indicating an AC component included in the signal. According to the tracking error offset cancel circuit, when the light spot crosses the track, the top peak value and the bottom peak value of the traverse signal generated in the push-pull signal PP are held, respectively, and the top peak value and the bottom peak value are held. The center value can be detected and output.

Here, by optimizing the time constant of the sampling hold of the top hold circuit 2 and the bottom hold circuit 3, the DC offset signal CSL is set to A /
Smoothing can be performed sufficiently to the extent that it can be detected by a D converter or the like.

Further, an offset value K derived from the DC offset signal CSL is calculated by a method described later.
To the other addition input terminal, and the arithmetic circuit 1 adds the push-pull signal PP and the offset value K to remove the offset. The added output of the arithmetic circuit 1 from which the offset has been removed is again used. The signal is supplied to the top hold circuit 2 and the bottom hold circuit 3 and is output as the tracking error signal TE.

The tracking error signal TE is amplified by an amplifier to become a tracking actuator drive signal, which is applied to a tracking coil of a biaxial actuator of the optical pickup.

In the optical pickup, the objective lens is moved in a focus direction (a direction approaching or separating from the optical disk) by a biaxial actuator using electromagnetic force.
And in the tracking direction (the direction crossing the track of the optical disk) independently.

The optical pickup is sequentially moved in the outer peripheral direction of the optical disk by a slide (thread) motor (not shown) in synchronization with the rotation of the optical disk, whereby the irradiation position of the laser beam is sequentially displaced in the outer peripheral direction of the optical disk. Let it.

An RF circuit (not shown) generates a reproduced RF signal from the light reflected from the optical disk. Note that the playback R
The F signal is demodulated, an error correction code is detected and error correction is performed, then deinterleaving, EFM-P
LUS demodulation processing is performed. Then, the demodulated signal is supplied to the output amplifier. The output amplifier amplifies the signal to an outputable level and outputs the signal.

FIG. 2 is a flowchart showing an operation for canceling the DC offset of the tracking error signal according to the present embodiment. In FIG. 2, after starting, first, in step S1, a system control circuit (not shown) instructs start of focus servo and spindle servo. Specifically, a laser beam is emitted from an optical pickup to an optical disc rotated by a spindle motor servo-controlled by a spindle servo system. Further, focus servo is performed by a focus coil of a two-axis actuator controlled by a focus servo system (not shown).

In step S2, the stem control circuit measures the DC offset signal CSL shown in FIG. More specifically, the system control circuit includes a DC offset signal CSL which is an operation output of the operation circuit 4 of the tracking error offset cancellation circuit shown in FIG.
Is measured as a digital value by converting an analog value into a digital value using an A / D converter or the like.

In step S3, the stem control circuit derives an offset value K from the signal level of the DC offset signal CSL. Specifically, the stem control circuit reads and outputs an offset value K corresponding to the signal level of the DC offset signal CSL from, for example, a table stored in a memory. This offset value K is a value for removing the DC offset of the traverse signal indicating the AC component included in the push-pull signal PP from the push-pull signal PP.

In step S4, the arithmetic circuit 1 shown in FIG. 1 adds (decreases) the offset value K to the push-pull signal PP. When reading the offset value from the memory table, the system control circuit adds the push-pull signal PP and the offset value K by the arithmetic circuit 1 and reads it as a plus value when the offset value is read in advance to remove the DC offset. Then, the arithmetic circuit 1 subtracts the offset value K from the push-pull signal PP. In this way, the DC from the push-pull signal PP
Remove (cancel) the offset.

Thereafter, in step S5, the stem control circuit again executes the DC offset signal CSL shown in FIG.
When the absolute value | CSL | of the signal level of the DC offset signal CSL falls within the predetermined allowable range δ, the process proceeds to step 6, where the system control circuit starts the tracking servo by the tracking servo system. To instruct. If the signal level | CSL | of the DC offset signal CSL exceeds the predetermined allowable range δ, the process returns to step 3, and the stem control circuit returns to the signal level | CSL | of the DC offset signal CSL.
, The offset value K is derived again, and the same processing of steps S3 to S5 is repeated until the signal level | CSL | of the DC offset signal CSL falls within the predetermined allowable range δ.

As described above, in the optical disk recording / reproducing apparatus of this embodiment for recording / reproducing information on / from the optical disk, the tracking error signal TE obtained by removing (cancelling) the DC offset from the push-pull signal PP is used. By applying the tracking servo by the one spot push-pull tracking method, the balance of the light spot can be adjusted, and stable tracking servo can be applied to the target track without causing detrack.

The optical disk driving method according to the present embodiment is a method for recording information on a land or a groove or reproducing information by irradiating an optical spot with a light spot on a land or a groove formed on the optical disk. In an optical disk driving method for tracking an optical pickup, a push-pull error signal generating means for generating a push-pull error signal PP indicating a deviation between a light spot and a track from a difference signal of a divided light receiving portion due to light reflected from an optical disk. And a top hold circuit 2 as a top hold means for holding the top peak value of the push-pull error signal PP, and a bottom hold circuit 3 as a bottom hold means for holding the bottom peak value of the push-pull error signal PP
And an arithmetic circuit 4 as an average value calculating means for calculating an average value of the top peak value and the bottom peak value, and an offset value K based on the average value is calculated by the push-pull error signal P.
Since the optical pickup is driven by performing tracking servo on either one of the land and the groove by removing it from the P,
By applying tracking servo by a one-spot push-pull tracking method using a tracking error signal obtained by removing a DC offset from a push-pull signal, it is possible to adjust the balance of the light spot, without causing detracking, A stable tracking servo can be applied to the track.

Further, in the optical disk driving method according to the present embodiment, in the above-described method, the focus servo of the light spot irradiated by the optical pickup is applied to the land or the groove formed on the optical disk, and the offset based on the average value is applied. Since the value K is removed from the push-pull error signal PP, the value
Using the tracking error signal TE from which the C offset has been removed, stable tracking servo can be immediately applied, and the time required for the servo system can be reduced.

In the optical disk driving method according to the present embodiment, when the top peak value in the top hold circuit 2 as the top hold means is held and the bottom peak value in the bottom hold circuit 3 as the bottom hold means, Since the time constant of the sampling hold at the time of holding can be adjusted, the DC offset signal CSL included in the push-pull signal PP is measured with an extremely smoothed waveform by optimizing the time constant. Can be measured D
The C offset signal CSL can be directly converted into a digital value by an A / D converter or the like and provided for digital processing.

Further, the optical disk device of the present embodiment
An optical disc that reproduces information by irradiating a laser spot on a pit or groove formed on an optical disc with an optical pickup to record information on the pit or groove, or by performing tracking of an optical pickup for reproducing the information. A push-pull error signal generating means for generating a tracking error signal indicating a deviation between the light spot and the track from a difference signal of the divided light receiving portions due to the reflected light of the light spot from the optical disk; and a top peak of the push-pull error signal PP A top hold circuit 2 as a top hold means for holding a value, a bottom hold circuit 3 as a bottom hold means for holding a bottom peak value of a push-pull error signal, and an average value of the top peak value and the bottom peak value are calculated. An arithmetic circuit 4 as an average value calculating means, and an offset value K based on the average value is removed from the push-pull error signal PP so that tracking servo is performed at one of the land and groove positions. And a driving means for driving the optical pickup, and the tracking of the optical pickup is performed. Therefore, the tracking servo is applied by a one spot push-pull tracking method using a tracking error signal obtained by removing a DC offset from the push-pull signal. Thus, the light spot balance can be adjusted, detracking does not occur, and stable tracking servo is applied to the target track, so that the quality of the tracking operation can be improved. Note Or it is possible to improve the quality of the operation of the reproduction.

Further, the optical disk device of the present embodiment
In the above description, the offset value K based on the average value is removed from the push-pull error signal PP while the focus servo of the light spot irradiated by the optical pickup is performed on the land or the groove formed on the optical disk. By using the tracking error signal TE obtained by removing the DC offset from the push-pull signal PP, stable tracking servo can be immediately applied, and the operation of recording or reproducing information on or from the optical disc can be performed in a short time.

Also, the optical disk device of the present embodiment
In the above description, when the top peak value is held in the top hold circuit 2 as the top hold means, and when the bottom hold circuit 3
Since the time constant of the sampling hold when holding the bottom peak value in is made adjustable,
By optimizing this time constant, the DC offset signal CSL included in the push-pull signal PP can be measured with an extremely smoothed waveform, and the measured DC offset signal CSL can be directly measured by an A / D converter or the like. It is converted into a digital value, and an offset value K to be removed from the push-pull signal PP is set.
The offset removal processing of P can be performed, and the racking servo can be applied using the push-pull signal PP having no offset as the tracking error signal TE. Therefore, stable recording and reproduction of information can be performed.

In the above-described embodiment, only an example in which the present invention is applied to a servo signal generation device of an optical disk device is described. However, the present embodiment is applied to a servo signal generation device of another electronic device having a configuration in which an actuator is controlled by a servo signal. It goes without saying that it may be applied.

[0056]

According to the optical disk driving method of the present invention, a land or a groove formed on an optical disk is irradiated with a light spot by an optical pickup to record information on the land or the groove or reproduce information. An optical pickup driving method for tracking an optical pickup for generating a push-pull error signal indicating a deviation between the light spot and the track from a difference signal of a divided light receiving portion due to reflected light of the light spot from the optical disc. Signal generating means, top hold means for holding a top peak value of the push-pull error signal, bottom hold means for holding a bottom peak value of the push-pull error signal, and an average of the top peak value and the bottom peak value Average value to calculate the value Comprising a calculation unit, and an offset based on the average value so as to remove from the push-pull error signal, to one of positions of the land or groove, by performing the tracking servo,
Since the above-described optical pickup is driven, the balance of the light spot can be adjusted by applying tracking servo by a one-spot push-pull tracking method using a tracking error signal obtained by removing a DC offset from the push-pull signal. Thus, there is an effect that stable tracking servo can be applied to a target track without detracking.

Also, in the optical disk driving method according to the present invention, in the above-mentioned method, the land or groove formed on the optical disk is subjected to focus servo of an optical spot irradiated by the optical pickup, and the land or groove is based on the average value. The offset is removed from the push-pull error signal.
Using the tracking error signal from which the offset has been removed, stable tracking servo can be immediately applied, and the time required for the servo system can be shortened.

In the optical disk driving method of the present invention, the time constant of the sampling hold when the top hold value is held by the top hold means and when the bottom peak value is held by the bottom hold means can be adjusted. I decided to
By optimizing this time constant, the DC offset signal included in the push-pull signal can be measured with a very smoothed waveform, and the measured DC offset signal is directly converted into a digital value by an A / D converter or the like. There is an effect that the data can be converted and provided for digital processing.

Further, the optical disk apparatus of the present invention irradiates a laser spot to a pit or groove formed on the optical disk by an optical pickup.
In an optical disc apparatus that reproduces information by recording information in the pits or the grooves or by performing tracking of an optical pickup for reproducing the information, a difference signal of a divided light receiving portion due to reflected light of the light spot from the optical disc. A push-pull error signal generating means for generating a tracking error signal indicating a deviation between the light spot and the track, a top-hold means for holding a top peak value of the push-pull error signal, and a bottom peak of the push-pull error signal. Bottom hold means for holding the value, average value calculation means for calculating the average value of the top peak value and the bottom peak value, and removing the offset based on the average value from the push-pull error signal, Land or groove In one position, and a driving means for driving the optical pickup to perform the tracking servo, because to perform the tracking of the optical pickup, DC from the push-pull signal
By applying tracking servo by one-spot push-pull tracking method using the tracking error signal from which the offset has been removed, the light spot balance can be adjusted, and no detrack occurs, and the target track is stable. By applying the tracking servo described above, it is possible to improve the quality of the tracking operation and to improve the quality of the operation of recording or reproducing information on the optical disk.

Also, the optical disk apparatus of the present invention may be arranged such that the land-based or groove formed on the optical disk is subjected to the focus servo of the light spot irradiated by the optical pickup, and the offset based on the average value is pushed to the land or groove. Since the signal is removed from the pull error signal, a stable tracking servo can be immediately applied using the tracking error signal obtained by removing the DC offset from the push-pull signal, and the operation of recording or reproducing information on the optical disk in a short time. It has the effect that it can be done.

In the optical disk apparatus of the present invention, the time constant of the sampling hold at the time of holding the top peak value at the top hold means and at the time of holding the bottom peak value at the bottom hold means can be adjusted. By optimizing this time constant, the DC offset signal included in the push-pull signal can be measured with an extremely smoothed waveform, and the measured DC offset signal is directly converted into an A / D signal. The offset value to be removed from the push-pull signal is set by converting to a digital value by a converter or the like, and the offset removal process of the push-pull signal can be performed. The push-pull signal without offset is used as a tracking error signal. , Can be racking servo, It, there is an effect that it is possible to perform stable writing and reading of information.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a tracking error offset cancel circuit according to an embodiment of the present invention.

FIG. 2 is a flowchart showing an operation of offset cancellation according to the embodiment of the present invention.

FIG. 3 shows a photodetector (P) according to an embodiment of the present invention.
It is a figure which shows the pattern of D).

FIG. 4 is a diagram illustrating an example of generating a push-pull signal according to the embodiment of the present invention. FIG. 4A illustrates a photodetector (P).
D) a push-pull signal generated from the difference between the detection signals of the four-divided light receiving unit, and FIG.
D) is a push-pull signal obtained by normalizing the difference between the detection signals of the four-divided light receiving units in the total light amount.

[Explanation of symbols]

1 arithmetic circuit, 2 top hold circuit, 3 bottom hold circuit, 4 arithmetic circuit, 5 photodetector (PD), 6 arithmetic circuit, 7 arithmetic circuit, 8 arithmetic circuit
… Arithmetic circuit, PP… push-pull signal, K… offset value, TE… tracking error signal,

Claims (6)

[Claims] An optical pickup irradiates a land or a groove formed on an optical disk with a light spot to record information on the land or the groove or perform tracking of the optical pickup for reproducing the information. An optical disc driving method, comprising: a push-pull error signal generating means for generating a push-pull error signal indicating a deviation between the optical spot and the track from a difference signal of the divided light receiving portions due to the reflected light of the optical spot from the optical disc; Top hold means for holding a top peak value of an error signal, bottom hold means for holding a bottom peak value of the push-pull error signal, and average value calculation means for calculating an average value of the top peak value and the bottom peak value And the above average The optical pickup is driven by removing the offset based on the value from the push-pull error signal and performing tracking servo at one of the lands and the groove. Optical disk drive method. 2. The optical disk drive method according to claim 1, wherein the land or groove formed on the optical disk is subjected to focus servo of an optical spot irradiated by the optical pickup, and the offset is based on the average value. Is removed from the push-pull error signal. 3. The optical disc driving method according to claim 1, wherein a time constant of a sampling hold when holding a top peak value in the top hold means and a bottom peak value in the bottom hold means can be adjusted. An optical disk driving method characterized by performing the following. 4. A pit or a groove formed on an optical disk is irradiated with a laser spot by an optical pickup to record information on the pit or the groove or to track the optical pickup for reproducing the information. An optical disc device that reproduces information by means of: a push-pull error signal generating means for generating a tracking error signal indicating a deviation between the light spot and the track from a difference signal between the divided light receiving portions due to the reflected light of the light spot from the optical disc; Top hold means for holding a top peak value of the push-pull error signal; bottom hold means for holding a bottom peak value of the push-pull error signal; and calculating an average value of the top peak value and the bottom peak value. Average performance Means for removing the offset based on the average value from the push-pull error signal, and driving the optical pickup so as to perform tracking servo at one of the lands or grooves. An optical disc device, comprising: (1) and (2), wherein the optical pickup performs tracking. 5. The optical disk device according to claim 4, wherein an offset based on the average value is applied to a land or a groove formed on the optical disk while focus servo of a light spot irradiated by the optical pickup is applied to the land or groove. An optical disk device, wherein the optical disk device is removed from the push-pull error signal. 6. The optical disc device according to claim 4, wherein a time constant of a sampling hold when the top peak value is held by the top hold means and a bottom peak value is held by the bottom hold means can be adjusted. An optical disk device characterized in that: