JP2000293868A - Optical disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical disk device where a light beam is controlled to the center of a track regardless of offset of a tracking error signal in a header field or offset of the tracking error signal due to displacement of an object lens which is caused by deviation of a detector for tracking error detection or eccentricity of the disk. SOLUTION: A second TE signal is detected on the basis of the difference between the amplitude of a total reflection light quantity signal (the output of an adder 130) obtained at the time of passage of a light beam on a first pit array formed in a position deviated to a track of a disk 100 in one of orthogonal directions and that obtained at the time of passage of the light beam on a second pit array formed in a position deviated to the track in the other direction, thus correcting the TE signal (the output of a subtractor 125) based on the push-pull method. In the header field, a tracking control system is set to the holding state by an S/H circuit 850.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to tracking control of an optical disk device for recording information on a disk on which tracks are formed or reproducing information from the disk.

[0002]

2. Description of the Related Art As a conventional optical disk device, a light beam generated from a light source such as a semiconductor laser is focused and irradiated on an optical disk rotating at a predetermined number of revolutions to reproduce a signal recorded on the optical disk. There is an optical disk device. An example of the optical disk will be described with reference to FIG. 27 showing a cross section of the disk. A plurality of tracks are formed in a spiral shape on the disk, and both the concave portions and the convex portions are tracks. The track pitch is 0.74 micrometers (hereinafter referred to as μm). A recording film made of a phase change material or the like is provided on the information surface. When information is recorded on a disk, the reflectivity of the recording film is changed by changing the intensity of the light beam according to the information while performing tracking control so that the light beam is always positioned on the track. When reproducing the information on the disk, the reflected light from the optical disk is received by the photodetector while performing tracking control so that the light beam is always positioned on the track. The information is reproduced by processing the output of the photodetector.

Next, an address will be described with reference to FIG. The black portions are the convex portions. The part indicated by the pit string is the header field. The pit is
It has a convex shape. The header field is located at the beginning of each sector. The pit row is arranged at an intermediate position between the convex track and the concave track. The structure of this header field is generally CAPA (Con
elementaryAllocated Pit A
address). The header field is V
accessible Frequency Osillat
or (hereinafter referred to as VFO) and a sector address. The VFOs 1 and 2 are recorded at a single frequency, and are recorded in a Phase Locked Loop (hereinafter referred to as P
LL). Sector address 1 indicates the address of the concave sector, and sector address 2 indicates the address of the convex sector. The area other than the header field is an area where information can be rewritten. Hereinafter, it is referred to as a rewritable area.

The detection of the track deviation amount for tracking control is similarly obtained from the reflected light from the disk. A tracking error detection method generally called a push-pull method will be described. Hereinafter, the tracking error is referred to as TE. The push-pull method is a method called a far-field method. This method is a method of detecting a positional deviation between a track and a light beam from a far field pattern of reflected light or transmitted light from a disk. The push-pull method is a method of detecting a TE signal by extracting light diffracted by a guide groove on a disk as an output difference at a light receiving portion of a two-divided photodetector arranged symmetrically with respect to a track center. is there. As shown in FIG. 29, when the center of the convex portion and the concave portion of the groove coincide with each other, a symmetrical reflection / diffraction distribution is obtained. FIG. 30 shows the output difference of the two-segment photodetector when the light beam traverses the track. The TE signal becomes zero at the center of the concave portion and the convex portion. Tracking control is
This is performed by moving the light beam on the disk in a direction orthogonal to the track according to the TE signal. The movement of the light beam in the direction perpendicular to the track is performed by moving the focusing lens by the tracking actuator.

[0005] Since the pit row of the header field is arranged at an intermediate position between the track of the convex portion and the track of the concave portion, the tracking error signal does not become zero even if the light beam is at the center of the track. Therefore, if tracking control is performed based on the tracking error signal in the header field, the light beam will deviate from the center of the track.

If the optical axis of the focusing lens and the optical axis of the light beam deviate, the light beam moves on the photodetector, so that an offset occurs in the TE signal by the push-pull method. Usually, since the disc has eccentricity, the focusing lens moves so as to follow the eccentricity of the disc, and an offset occurs. Therefore, even if the tracking control is performed so that the tracking error signal becomes zero, the light beam deviates from the center of the track.

[0007]

As described above, the offset of the tracking error signal in the header field, the offset of the tracking error detecting photodetector, and the offset of the tracking error signal caused by the displacement of the focusing lens due to the eccentricity of the disk. Makes it difficult to control the light beam to the center of the track.

SUMMARY OF THE INVENTION It is an object of the present invention to accurately correct a light beam even if there is an offset of a tracking error signal in a header field, a displacement of a detector for detecting a tracking error, and an offset of a tracking error signal due to a displacement of a focusing lens. An object of the present invention is to provide an optical disk device that performs control at the center of a track.

[0009]

In order to achieve this object, an optical disk apparatus according to the present invention provides a first pit row formed at a position shifted in one direction perpendicular to a track and a track. A reproducing signal detecting means for converging and irradiating a light beam on a disc on which a second pit row formed at a position deviated in the other direction perpendicular to the other direction and detecting information recorded on the disc; First tracking error detecting means for detecting the displacement of the light beam by the push-pull method, and displacement of the light beam and the track from the reproduced signals of the first and second pit rows output from the reproduced signal detecting means. A second tracking error detecting means for detecting an error, a moving means for moving the light beam across the track, and a second tracking error detecting means based on an output of the first tracking error detecting means. Tracking control means for controlling the moving means so that the light beam is positioned on the track, and correction means for changing a target position of the tracking control means based on an output of the second tracking error detecting means. Is configured such that the tracking control means does not operate in response to the output of the first tracking error detection means when the signal passes over the first and second pit trains.

[0010] In the optical disk device of the present invention, the target position of the tracking control based on the TE signal by the push-pull method is formed at a position shifted in one direction perpendicular to the track. Pit row,
A second TE for detecting a positional shift between the light beam and the track based on a reproduction signal when the light beam passes over a second pit row formed at a position shifted in the other direction perpendicular to the track. The signal is corrected based on the signal, and when the light beam passes over the first and second pit rows, the tracking control means is not operated in accordance with the output of the first tracking error detection means. The light beam is controlled to the center of the track even if there is an offset of the tracking error signal due to the offset of the tracking error signal, the displacement of the detector for detecting the tracking error, or the displacement of the objective lens due to the eccentricity of the disk.

[0011]

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

(Embodiment 1) FIG. 1 is a block diagram of an optical disk device according to Embodiment 1 of the present invention. The disk 100 is attached to a rotating shaft 102 of a motor 101 and rotates at a predetermined rotation speed. The disk 100 has tracks formed in a spiral shape with irregularities,
The projections and the depressions are both tracks, on which information is recorded. The track pitch is 0.6 μm. In addition, the width of the projections and the depressions is about 0.6 μm.

The transfer table 115 has a laser 109, a coupling lens 108, a polarizing beam splitter 110,
/ 4 wavelength plate 107, total reflection mirror 105, photodetector 113,
The actuator 104 is attached, and the transfer table 1
Reference numeral 15 is configured to move in the radial direction of the disk 100 by the transfer motor 114.

The laser 10 mounted on the transfer table 115
9 is converted into parallel light by the coupling lens 108,
The light passes through the 10, 1/4 wavelength plate 107, is reflected by the total reflection mirror 105, is focused by the focusing lens 103 on the information surface of the disk 100, and is irradiated. The light reflected by the information surface of the disc 100 passes through the focusing lens 103, is reflected by the total reflection mirror 105, and passes through the quarter-wave plate 107, the polarizing beam splitter 110, the detection lens 111, and the cylindrical lens 112. Detector 1 consisting of four light receiving parts
13 is incident.

The focusing lens 103 includes an actuator 104
It is attached to the movable part. Note that focus control is not directly related to the present invention, and a description thereof will be partially omitted. The actuator 104 includes a focusing coil, a tracking coil, a permanent magnet for focusing, and a permanent magnet for tracking. Therefore, when a voltage is applied to the focusing coil (not shown) of the actuator 104 using the power amplifier 152, a current flows through the coil, and the coil receives a magnetic force from a focusing permanent magnet (not shown). Therefore, the focusing lens 103 moves in a direction perpendicular to the surface of the disk 100 (vertical direction in the figure). The focusing lens 103 is controlled so that the focal point of the light beam 106 is always located on the information surface of the disk 100 in accordance with a focus error signal indicating a shift between the focal point of the light beam and the information surface of the disk.

A tracking coil (not shown)
When a voltage is applied using the power amplifier 145, a current flows through the coil and receives a magnetic force from a tracking permanent magnet (not shown). Therefore, the focusing lens 103 moves in the radial direction of the disk 100, that is, across the tracks on the disk 100 (left and right in the figure).

The photodetector 113 is formed by four light receiving sections. The reflected light from the disk incident on the photodetector 113 is converted into a current, respectively, and the I / V converter 1
16, 117, 118 and 119. I / V converters 116, 117, 118, and 119 convert an input current to a voltage corresponding to the current level.

The adders 120, 121, 123, 124,
130 adds and outputs the input signals. Subtractor 12
2, 125 subtracts the input signal and outputs it.

The output of the subtractor 122 is a focus error signal indicating a deviation between the focal point of the light beam applied to the disk and the information surface of the disk 100. The focus error signal is sent to the analog / digital converter 149, the phase compensation circuit 150, the digital / analog converter 151, and the power amplifier 152. A current flows through the focusing coil of the actuator 104 by the power amplifier 152.

An analog / digital converter 149 (hereinafter, referred to as an A / D converter) converts an analog signal into a digital signal. A digital / analog converter 151 (hereinafter, referred to as a D / A converter) converts a digital signal into an analog signal.

The phase compensation circuit 150 is a digital filter and has a function of stabilizing a focus control system.
Therefore, the focusing lens 10 according to the focus error signal
3 is driven, and the focal point of the light beam is always located on the information surface.

The optical system shown in FIG. 1 constitutes a TE signal detection system generally called a push-pull method. Accordingly, the output of the subtractor 125 indicates a TE signal indicating a deviation between the light beam irradiated on the disk and the track of the disk 100. Hereinafter, the output of the subtractor 125 is referred to as the first TE
It is described as a signal. The first TE signal is connected to switch 155, A /
D converter 143, adder 142, phase compensation circuit 144,
Sample hold circuit (hereinafter referred to as S / H circuit) 85
0, sent to the D / A converter 170 and the power amplifier 145. A current flows through the tracking coil of the actuator 104 by the power amplifier 145.

The phase compensation circuit 144 is a digital filter and has a function of stabilizing a tracking control system. Therefore, the focusing lens 103 according to the first TE signal
Is driven, the light beam always follows the track.

Also, the first TE converted to digital
The signal is a low-pass filter 146, a D / A converter 147,
The signal is sent to the power amplifier 129 via the adder 148. Therefore, the transfer motor 114 is controlled according to the low frequency component of the first TE signal. In other words, in the tracking control system, the actuator
4 and the transfer motor 114 follows the disturbance of low frequency components.

The adder 130 includes an adder 123 and an adder 1
24 outputs are added. That is, the output of the adder 130 is the total amount of light received by the photodetector 113. In the following, the adder 13
The output signal of 0 is referred to as a total reflection light amount signal. Adder 130
Is sent to the address reproducing circuit 131. The address reproducing circuit 131 reproduces a sector address and sends it to a microprocessor 140 (hereinafter, referred to as a microcomputer). Also, a signal synchronized with the address is supplied to the gate generation circuit 1.
Send to 32.

The gate generation circuit 132 outputs to the switch 133 an ID signal that goes high in the address section.
Further, a pulse is output to the sample and hold circuit 136 (hereinafter, referred to as an S / H circuit) immediately after VFO1 in the address section. Hereinafter, it is referred to as a VFO1 sample signal. Further, a pulse is output to the S / H circuit 137 immediately after VFO2 in the address section. Hereinafter, it is described as a VFO2 sample signal. Further, a pulse is output to the S / H circuit 139 immediately after the VFO2 sample signal. Hereinafter, it is referred to as a data update signal.

The S / H circuit 850 has a D / A just before the ID section.
The input value of the converter 170 is sampled and held for the period of the ID section. That is, in the ID section, the tracking control system is in the hold state.

Switches 133, HPF 172, absolute value circuit 134, LPF 135, S / H circuits 136, 137,
139 and the subtractor 138 form a circuit for generating the second TE signal. The output of the S / H circuit 139 is the second
Of the TE signal.

The second TE signal is converted into a digital signal by an A / D converter 153, and is multiplied by a multiplier 156, an LPF 15
7 and to the adder 142 via the switch 154.

The multiplier 156 multiplies the input signal by a predetermined coefficient and outputs the result. The predetermined coefficient is a coefficient that makes the detection sensitivity of the first TE signal equal to the detection sensitivity of the second TE signal. Hereinafter, the output of the multiplier 156 is referred to as a normalized second TE signal.

The operation of the microcomputer 140 when operating the tracking control will be described. The microcomputer 140 in the initial state
Operates the tracking control by closing the switch 155 with the switch 154 opened. Focusing lens 104
Are driven based on the first TE signal.

The address reproducing circuit 131 reads the address and sends the address to the microcomputer 140. The address reproduction circuit 131 sends a signal synchronized with the address to the gate generation circuit 132. The gate generation circuit 132 outputs an ID signal, a VFO1 sample signal, a VFO2 sample signal, and a data update signal. Therefore, the S / H circuit 139
Outputs a second TE signal. The microcomputer 140 is
When the switch 154 is closed and the first TE signal is
The target position of the tracking control system operating based on the TE signal is corrected. The correction is performed by the adder 142 to the tracking control system based on the first TE signal.
This is performed by adding an offset corresponding to the E signal.

Hereinafter, each block will be described in detail.

First, a method for detecting the second TE signal will be described with reference to FIG. FIG. 2A is a schematic diagram illustrating a relationship between a track and a light beam, and FIG. 2B illustrates a waveform of a total reflection light amount signal output from the adder 130. FIG. 2A shows a case where the light beam moves along the center of the track of the convex portion (the portion painted black). The amount of light reflected from the disk is modulated by pits as shown in FIG. Since the distance between the pit row of VFO1 and the light beam and the distance between the pit row of VFO2 and the light beam are equal, the amplitude m1 in VFO1 and the amplitude n1 in VFO2 are equal.

FIG. 3 shows a case in which the light beam moves between the tracks. FIG. 3B shows the total reflection light amount signal. Since the distance between the pit row of VFO1 and the light beam is shorter than the distance between the pit row of VFO2 and the light beam, the amplitude m2 is larger than the amplitude n2 of VFO2. Become.

FIG. 4 shows a case where the light beam is located at an intermediate position opposite to that of FIG. FIG. 4B shows a total reflection light amount signal. Since the distance between the pit row of VFO1 and the light beam is longer than the distance between the pit row of VFO2 and the light beam, the amplitude m3 is smaller than the amplitude n3 of VFO2. Become.

As shown in FIGS. 2, 3, and 4, the VFO
By detecting the difference between the amplitudes of the total reflection light amount signals at 1 and VFO2, the deviation between the light beam and the track can be detected. FIG. 5 shows the relationship between the track deviation and the second TE signal. Note that the direction of the deviation of the VFO1 and VFO2 from the track center is opposite in the track of the convex portion and the track of the concave portion, so that the inclination of the second TE signal between the track of the convex portion and the track of the concave portion with respect to the track deviation is reversed. Become.

Next, a method of detecting the amplitude of the total reflection light amount signal at VFO1 and VFO2 will be described. FIG. 6 shows the relationship between the output signal of the gate generation circuit 132 and the output signal of the adder 130. FIG. 6A shows the relationship between the light beam and the header field, and FIG.
FIG. 6C shows an ID signal, and FIG. 6D shows VF
FIG. 6E shows the waveform of the O1 sample signal, FIG. 6E shows the waveform of the VFO2 sample signal, and FIG. 6F shows the waveform of the data update signal.

The gate generation circuit 132 outputs an ID signal, a VFO1 sample signal, a VFO2 sample signal, and a data update signal in the next sector based on the address synchronization signal in the previous sector output from the address reproduction circuit 131. Generate. The gate generation circuit 132 includes an oscillator and a counter for counting the output of the oscillator.
The counter is cleared according to the address synchronization signal, and the above-described gate signal is generated based on the counter value.

The ID signal goes high during the period from time t10 immediately before the header field to time t14 immediately after the header field. The VFO1 sample signal is a pulse signal that goes high at time t11, which is the rear end of VFO1. The VFO2 sample signal is VFO2
Is a pulse signal which becomes a high level at time t12 which is the rear end of the pulse signal. The data update signal is a pulse signal that goes high at time t13 immediately after the VFO2 signal.

When the ID signal goes high, switch 1
33 closes. Therefore, the output signal of the adder 130 is HP
The signal is input to the absolute value circuit 134 via F172. The absolute value circuit 134 outputs the absolute value of the input signal based on the zero level. The HPF 172 removes a DC component. LP
F135 removes the high frequency component of the input signal and outputs it.

The output level of the LPF 135 is a level corresponding to m and n shown in FIGS. S /
The H circuit 136 enters a sample state when the control terminal c goes high, and enters a hold state when the control terminal c goes low. The S / H circuits 137 and 139 have the same configuration.

Therefore, the output of the LPF 135 at time t10 is held and output. S / H circuit 136 at this time
Indicates the m in FIGS. 2, 3 and 4. Similarly, S /
The H circuit 137 holds and outputs the output of the LPF 135 at time t11. The output of the S / H circuit 137 at this point indicates n in FIGS.

The subtractor 138 is provided between the S / H circuit 136 and the S / H circuit 136.
The difference between the outputs of the H circuit 137 is output. That is, time t11
Subsequent outputs of the subtractor indicate the value of (mn). The S / H circuit 139 holds and outputs the output of the subtractor 138 at time t12. Therefore, the output of the S / H circuit 138 is V
The amplitude difference between the total reflection light amount signal at FO1 and the amplitude of the total reflection light amount signal at VFO2 is shown. That is, it becomes the second TE signal.

The HPF 172 and the absolute value circuit 134 will be described with reference to FIG. Capacitor 200, resistor 2
01 constitutes the HPF 172. The terminal 208 is connected to the switch 133, and the terminal 209 is connected to the LPF 135. The output of the HPF 172 is output from the amplifier 2 having a gain of 1.
03 and a gain of −1 are sent to the amplifier 204. Diodes 205 and 206 are connected to the amplifiers 203 and 204, respectively. Therefore, when the outputs of the amplifiers 203 and 204 are negative, the output becomes zero. The outputs of the amplifiers 203 and 204 are sent to an adder 207, and the output of the adder 207 is sent to a terminal 209.

FIG. 8 illustrates the operation of the circuit of FIG. 7. FIG. 8 (a) shows a signal waveform input to the terminal 208, and FIG.
8B shows an ID signal, FIG. 8C shows an output of the amplifier 203,
FIG. 8D shows the waveform of the output of the amplifier 204, and FIG. 8E shows the waveform of the output of the adder 207. The output of the adder 207 is
The waveform is converted into an absolute value with reference to the center of the amplitude of the total reflection light amount signal of the VFO unit.

The LPF 135 removes the high-frequency components generated by the pits of the signal shown in FIG. 8E which is the output signal of the absolute value circuit 134 in the above-described configuration. Therefore, L
The output of the PF 135 indicates the amplitude of the total reflection light amount signal at the VFO.

Next, a block for adding the second TE signal to the tracking control system will be described. The second TE signal is converted to a digital signal by the A / D converter 153, and then sent to the LPF 157 as a digital filter via the multiplier 156. FIG.
FIG. 9 (a) shows the gain and phase characteristics of FIG. The vertical axis represents decibels (dB), and the horizontal axis represents frequency in logarithms (Log). The characteristics are flat up to 1 Hz and become -20 dB / dec above 1 Hz.
It becomes 0 dB at 0 Hz. FIG. 9B shows the phase characteristics.
The vertical axis represents the phase in degrees, and the horizontal axis is the same as FIG. 9A.

Next, the characteristics of the tracking control system when the second TE signal is added to the tracking control system will be described. That is, the characteristic is in a state where the switch 154 is closed. FIG. 10 shows a block diagram of the output of the subtracter 125, which is the first TE signal, as P, the output of the adder 142 as Q, and the output of the S / H circuit 139, which is the second TE signal, as R. .

The signal line O indicates the position of the light beam. The signal line T indicates the position of the track. The output of the subtractor 350 indicates the deviation between the light beam and the track. The signal U is a signal indicating a true shift between the light beam and the track. Hereinafter, the signal U is referred to as a true track shift signal. The true track deviation signal U is sent to the adder 353 via the zero-order holder 354 and the LPF 351. Note that the LPF 351 corresponds to the LPF 157 which is the above-described digital filter.
The zero-order holder 354 corresponds to the fact that the second TE signal is a signal detected only in the ID part.

The signal line D indicates the offset of the first TE signal caused by the above-described positional shift of the photodetector 113 and the displacement of the focusing lens. Therefore, the output of adder 352 indicates the first TE signal.

FIG. 11 shows the transfer characteristics of the signal lines U and Q. Note that the level of the signal line D is zero. FIG.
(A) is a gain characteristic, the vertical axis is decibel (dB), and the horizontal axis is frequency in logarithm (Log). The characteristics are flat up to 1 Hz, and become -20 dB / dec above 1 Hz, and become 0 dB at 10 Hz. 0 dB above 10 Hz
become. FIG. 11B shows the phase characteristics. The vertical axis represents the phase in degrees, and the horizontal axis is the same as FIG. 11A.

In the case of a tracking control system using only the first TE signal, that is, when the switch 154 is open, the gain becomes 0 dB regardless of the frequency. Therefore, when the switch 154 is closed, the gain at 10 Hz or less increases. For frequencies below 10 Hz, the second TE
The signal becomes dominant. Since the second TE signal is a signal obtained by passing the true track shift signal through the zero-order holder, the signal line D
Is not affected. Therefore, the influence of the signal line D is reduced, and even if there is an offset (D in FIG. 10) of the first TE signal caused by the position shift of the photodetector 113 or the displacement of the focusing lens, the light beam is positioned at the track center. Follow.

Next, the operation of sampling the input value of the D / A converter 170 immediately before the ID section by the S / H circuit 850 and holding the input value while the light beam passes through the ID section will be described with reference to FIG. I do. First, during the ID section, S
The operation when the value immediately before the ID portion is not held by the / H circuit 850 will be described, and then the operation when the value is held will be described.

FIG. 12A shows the waveform of the first TE signal, FIG. 12B shows the waveform of the ID signal, and FIG. 12C shows the waveform of the second T signal.
The E signal waveform is shown. ID period is ID
This is a period in which the signal waveform is at a high level.

Since the pit train of the ID portion is arranged at a position shifted from the center of the track, the first TE signal generates an offset corresponding to the shift of the pit train as shown in FIG. . That is, the first TE signal in the ID section is
It does not correspond to the deviation of the light beam from the center of the track. Therefore, the pseudo first TE signal in the ID section is A / D1
When input to 43, the focusing lens is driven according to the signal, so that the light beam deviates from the track center. Since the second TE signal detection system detects a shift between the light beam and the track center in the ID section, an offset occurs after passing through the ID section as shown by a broken line in FIG.
After passing through the ID section, the first TE signal is an original signal indicating a deviation between the light beam and the track, so that the light beam is controlled to be positioned at the center of the track. However,
Since the level of the second TE signal is held until the next ID section, the operation is performed so that the light beam is shifted from the track center.

During the period of the ID section, the S / H circuit
The original operation of holding the value immediately before the unit will be described.
In the ID section, the drive value of the tracking actuator is held at the value immediately before the ID section by the S / H circuit 850, so that the light beam is held at the center of the track. Therefore,
The second TE signal remains at zero as shown by the solid line in FIG. Therefore, the light beam does not deviate from the center of the track due to the influence of the ID portion during the period up to the next ID portion.

Embodiment 2 Hereinafter, Embodiment 2 of the present invention will be described with reference to FIG. The same blocks as in the above-described first embodiment are denoted by the same reference numerals, and description thereof is omitted. The difference from the first embodiment is that a measurement circuit 851 and a subtractor 852 are added.

The measuring circuit 851 captures the level of the first TE signal immediately before and immediately after the ID section, and outputs the average value. The first TE signal A / D converted to the terminal a is
An ID signal is input to the terminal c. Terminal b is the output terminal. The measurement circuit 851 detects the rising edge of the signal at the terminal c and measures the signal level input to the terminal a at that time. This value is defined as E1. Further, the rising edge of the signal at the terminal c is detected and the measurement is similarly performed. This value is set to E2. (E1 + E2) / 2 after measurement
Is calculated and output to the terminal b.

The output of the measuring circuit 851 is sent to a subtractor 852. The output of the subtractor 852 is added to the tracking control system via the LPF 157, the switch 154, and the adder 142.

FIG. 14 is a schematic diagram showing the relationship between a light beam and a track. The operation of the measurement circuit 851 and the subtractor 852 when the light beam moves on the line shown in FIG. 14 will be described. FIG. 14 shows an example in which the light beam is deviated from the center of the track in the ID section due to an external shock or the like applied to the optical disk device. The operation when the light beam moves on the line shown by the arrow will be described. FIG. 15 shows a waveform when the light beam moves on the line shown in FIG. FIG.
FIG. 5A shows the first TE signal waveform. Similarly,
FIG. 15B shows the ID signal, FIG. 15C shows the normalized second TE signal, and FIG. 15D shows the output signal of the subtractor 852.

As shown in FIG. 14, when the light beam deviates from the center of the track due to an impact or the like, the first TE signal becomes
It becomes a predetermined value as shown in FIG. The value immediately before the ID portion is E3, and the value immediately after the ID portion is E4. Note that E3 = E
Assume that it is 4. The first TE signal becomes zero when no impact or the like is lost. In addition, since the period in which the impact is applied is the period of the ID section, the normalized second period as shown in FIG.
Is also E3. Therefore, the output of the subtractor 852 becomes zero. By subtracting the level of the first TE signal immediately before and immediately after the ID portion from the normalized second TE signal, even if the light beam deviates from the center of the track due to the impact or the like applied at the ID portion. 2 TE signals are not affected.

When the measuring circuit 851 and the subtractor 852 are not provided, the normalized second TE signal is output as shown in FIG.
Since E3 shown in (c) is reached, there is a problem that the light beam is shifted from the center of the track by the second TE signal during the period up to the next ID section.

Embodiment 3 Hereinafter, Embodiment 3 of the present invention will be described with reference to FIG. 16 which is a block diagram thereof. The same blocks as in the above-described first embodiment are denoted by the same reference numerals, and description thereof is omitted. The difference from the first embodiment is that an average value calculation circuit 855 and a subtractor 856 are added. The microcomputer 140 is the microcomputer 8
57.

As described above, an offset occurs in the first TE signal due to a position shift of the photodetector 113. Further, when the focusing lens 103 is displaced from the optical axis of the light beam due to the eccentricity of the disk, an offset occurs. The first TE signal and the second TE signal in the case where there is an offset due to the displacement of the photodetector 113 and the displacement of the focusing lens 103 will be described with reference to FIG. The positional deviation of the photodetector 113 is such that the deviation between the light beam and the center of the track is 0.1%.
It is assumed to be equivalent to μm.

The thick broken line in FIG.
Shows the first TE signal in the open state, and the bold solid line shows the waveform when the switch 154 is closed. FIG.
(B) shows the normalized second TE signal in a state where the switch 154 is open with a thick broken line, and the switch 15
The case where 4 is closed is indicated by a thick solid line.

In the state where the switch 154 is open, since the correction by the second TE signal does not operate, the control is performed so that the first TE signal becomes zero. Therefore, the first TE signal becomes almost zero as shown by the thick broken line in FIG. However, since an offset occurs due to the displacement of the photodetector 113 and the displacement of the focusing lens 103, the normalized second TE signal has a waveform indicated by a thick broken line in FIG. 17B. The DC component is equivalent to 0.1 μm of off-track. The AC component is a component generated by the displacement of the focusing lens 103 due to the eccentricity of the disk. Therefore, it is synchronized with the rotation of the disk.

When the switch 154 is closed in this state, the correction function based on the second TE signal operates, so that the second TE
The signal is controlled to be zero. Therefore, the normalized second TE signal becomes almost zero as shown by the thick solid line in FIG. Since the gain of the correction system based on the second TE signal is 20 dB in the low frequency range as shown in FIG. 11, the DC component of the control difference is about 0.01 μm.
A DC offset equivalent to 0.01 μm remains in the normalized second TE signal. Therefore, the first TE signal is
As shown by the thick solid line in FIG. 17A, the offset has a DC component equivalent to 0.09 μm.

In this state, the average value calculation circuit 855 adds the first TE signal of one rotation of the disk based on the one rotation signal sent from the microcomputer 857 and indicating the period of one rotation of the disk, and outputs the average value. I do. Therefore, the output of the average value calculation circuit 855 has a level equivalent to 0.09 μm, and a signal equivalent to 0.09 μm is set to the minus terminal of the subtractor 856. When the switch 154 is opened in this state, the output of the subtractor 856 becomes a signal from which the offset corresponding to 0.09 μm due to the position shift of the photodetector 113 has been removed. That is, the output of the subtractor 856 is a signal having an offset equivalent to 0.01 μm. In this state, switch 15
4 is closed, the offset equivalent to 0.01 μm described above becomes 0.001 μm by the correction function using the second TE signal.
m.

By adding the average value calculating means 855 and the subtractor 856, the deviation of the light beam from the track center due to the positional deviation of the photodetector 113 can be further reduced. By adding the first TE signal for one rotation of the disk and calculating the average value, the influence of the offset due to the displacement of the focusing lens 103 can be removed.

An operation for recording information on a track will be described. When the microcomputer 857 searches for a target sector, the microcomputer 857 controls the laser driving circuit 175 to
Is modulated according to the recording information. During recording, the normalized second TE signal is fetched, and it is checked whether or not the second TE signal is within a predetermined range. If it exceeds a predetermined range, the recording operation is stopped. Since the second TE signal is a signal that is not affected by the displacement of the photodetector 113 or the displacement of the focusing lens 103, it is possible to accurately detect that the light beam has approached an adjacent track. Therefore, the information of the adjacent track is not destroyed.

Embodiment 4 Hereinafter, Embodiment 4 of the present invention will be described with reference to the block diagram of FIG. The same blocks as those in the above-described third embodiment are denoted by the same reference numerals, and description thereof is omitted. The difference from the third embodiment is that the signal input to terminal a of average value calculation circuit 855 is changed from the first TE signal to the normalized second TE signal.

In the third embodiment, the tracking control is performed by the first TE signal, and based on the average value of the first TE signal when the target position is corrected by the second TE signal, the photodetector 113 is controlled. In this configuration, the offset according to the displacement is corrected.

In the fourth embodiment, the average value of the normalized second TE signal is measured with switch 154 open, and the value is sent to subtractor 856. Note that the photodetector 11
1 and the first T due to the displacement of the focusing lens 103.
The offset of the E signal is the same as in the third embodiment.

FIG. 19A shows the first TE signal in a state where the switch 154 is opened by a thick broken line, and a thick solid line shows a waveform when the switch 154 is closed. FIG. 19B shows the waveform of the normalized second TE signal in a state where the switch 154 is open, indicated by a thick broken line, and a thick solid line, when the switch 154 is closed.

When the switch 154 is open, the correction by the second TE signal does not operate, so that the control is performed so that the first TE signal becomes zero. Therefore, the first TE signal becomes almost zero as shown by the thick broken line in the waveform (a).
However, since the first TE signal has an offset due to the displacement of the photodetector 113 and the deviation of the focusing lens 103, the normalized second TE signal has a waveform (b).
A waveform shown by a thick broken line is shown in FIG. The DC component is equivalent to 0.1 μm of off-track. The AC component is a component generated by the displacement of the focusing lens 103 due to the eccentricity of the disk.

In this state, the average value calculation circuit 855 adds the normalized second TE signal for one rotation of the disk based on the one rotation signal sent from the microcomputer 857 and outputs the average value. As for the positional deviation of the photodetector 113, the deviation between the light beam and the center of the track is equivalent to 0.1 μm.
The level is equivalent to μm. Therefore, the output of the subtractor 856 is a signal from which the offset equivalent to 0.1 μm due to the position shift of the photodetector 113 has been removed. That is, the subtractor 85
The output of No. 6 is a signal from which the offset due to the displacement of the photodetector 113 has been removed. After the correction is completed, the switch 154 is closed to start the correction by the second TE signal.

With the above configuration, the offset of the first TE signal due to the displacement of the photodetector 113 can be removed, and the light beam accurately follows the center of the track.

Embodiment 5 Hereinafter, Embodiment 5 of the present invention will be described with reference to the block diagram of FIG. The same blocks as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted. The difference from the first embodiment is that the unevenness determination circuit 500, the inverting amplifiers 501 and 503,
That is, switches 502 and 504 are added. Another difference is that the disk 100 is changed to a disk 550.

FIG. 21 is a schematic diagram of a track formed on the disk 550. The shaded portions indicate the convex portions.
The ID part indicates an address part, and the other part is a rewritable area. The track A has a convex portion on the left side and a concave portion on the right side. The convex part and the concave part are switched at the center Q2 point. When performing tracking control so that the light beam is on the track A, it is necessary to detect the point Q2 and switch the polarity of the first TE signal.

FIG. 22A shows the state at the point Q0 in FIG.
Shows the characteristics of the first TE signal at point Q4. Since the unevenness is reversed, the polarity of the first TE signal is reversed at points Q0 and Q4. Also, the direction of the shift between VFO1 and VFO2 is reversed. Therefore, the polarity of the second TE signal is also reversed. As in the case of the first TE signal, it is necessary to detect the point Q2 and switch the polarity of the second TE signal.

The unevenness determining circuit 500 fetches the output signals of the adder 130 and the subtractor 125 and determines whether the light beam is on a concave track or a convex track. The inverting amplifiers 501 and 503 invert the input signal and output it. The switches 502 and 504 output the signal of the terminal a or the terminal b to the terminal c according to the control signal of the terminal d. An unevenness determination signal of the unevenness determination circuit 500 is input to the terminals d of the switches 502 and 504.

FIG. 23 shows a block diagram of the unevenness determination circuit 500. The terminal 900 has a subtractor 125, the terminal 908 has an adder 130, and the terminal 914 has switches 502 and 50.
4 terminals d are connected to each other. LPF901,
Reference numeral 907 outputs a low frequency component of the input signal. The comparators 903, 905, and 906 output a high level when the level of the terminal a is higher than the level of the terminal b.

The operation will be described with reference to the waveforms of FIG. FIG. 24A shows a signal input to the terminal 900. 24B shows the output of the LPF 901, FIG. 24C shows the output of the comparator 905, FIG. 24D shows the output of the comparator 903, FIG. 24E shows the output of the flip-flop, and FIG. (G) is the LPF 907
(H) shows the output of the comparator 906,
(I) shows the output of the delay circuit 915, and (j) shows the latch 91.
3 respectively.

The output of the LPF 901 is as shown in FIG. 24B due to the influence of the pits in the ID section. By setting the reference power supply 904 to E20, the output of the comparator 905 becomes as shown in FIG.
As shown in (c), it goes high at time t30. Therefore, the output of the flip-flop 912 goes low at time t30 as shown in FIG. Reference power supply 90
By setting 2 to E21, the output of the comparator 903 goes high at time t32 as shown in FIG. Therefore, the output of flip-flop 912 is at time t3
2 goes high. The output of the LPF 907 is as shown in FIG. By setting the reference power supply 909 to E22, the output of the comparator 906 goes high during the period from time t30 to t33 as shown in FIG. Therefore, the output of the delay circuit 915 has the waveform shown in FIG.

The latch 913 latches and outputs the output level of the flip-flop 912 at the falling edge of the output signal of the delay circuit 915. In this case, the output of the unevenness determination circuit 500 becomes high level. When the concavity and convexity are switched, the components of the pits shown in FIG. 24A have a negative level in the first half and a positive level in the second half. Therefore, the unevenness determination circuit 500
Output goes low.

The polarity of the first and second TE signals is switched according to the output of the unevenness determination circuit 500, and then the adder 142 is switched.
Is configured to be added. In addition, since the polarity of the second TE signal is switched before input to the LPF 157,
Even when passing through the point Q2, the output of the LPF 157 is continuous, and the tracking control is stabilized.

The operation of LPF 157 will be described with reference to FIG. FIG. 25A shows the second TE signal, and FIG.
Represents the input signal of the LPF 157, and FIG.
57 are respectively shown. The broken line shows the case where the polarity is not switched. The responsiveness after passing through the point Q2 is deteriorated by the responsiveness of the filter, and the light beam deviates from the track center for a predetermined period after passing through the point Q2. That is, the first TE
By adding the signal after switching the polarity of the signal and the second TE signal, the accuracy of the tracking control is improved at the switching point between the concave portion and the convex portion.

First T due to misalignment of photodetector 113
The correction of the offset of the E signal will be described. The offset measuring circuit 950 measures the level of the first TE signal immediately after the switching of the unevenness, and sends a level 0.5 times the level to the subtractor 856. When measuring the level,
The switch 154 is open, and the correction function based on the second TE signal is not operating.

The operation will be described with reference to FIG. FIG.
FIG. 21A shows that the light beam has an ID on the track A shown in FIG.
The characteristic of the first TE signal at the point Q1 immediately before the section is shown. FIG. 26B shows the characteristic of the first TE signal at the point Q3 immediately after the light beam on the track A at the ID section. The case where the offset of D occurs in the first TE signal due to the position shift of the photodetector 113, and the broken line shows the case where there is no offset.

When the track A passes through the convex portion, the first TE signal becomes zero level. However, the light beam is controlled at a position away from the track center by a distance L due to a position shift of the photodetector 113. In this state, when the light beam reaches the point Q3 after passing through the ID portion, the distance of the light beam from the track center is Q
Same as at two points. This is because the drive current to the tracking coil is held in the ID section. Therefore, the level of the first TE signal at the point Q3 is 2
* D. That is, the level is twice as high as the offset due to the position shift of the photodetector 113. Therefore, the offset measuring circuit 950 multiplies the measured value by 0.5 and sends the multiplied value to the subtractor 856. Therefore, the output of the subtractor 856 is
Is a signal from which the offset of the first TE signal due to the positional deviation is removed.

In the fifth embodiment, the offset measuring circuit 950 is operated while the correction by the second TE is stopped. However, when the correction by the second TE signal is operating, the light beam Passes through the center of the track, and becomes D at point Q2 and becomes -D at point Q3. Therefore, when operating the offset measuring circuit 950 in a state where the correction by the second TE signal is operating, the same effect as described above can be obtained by setting the measured value at the point Q2 to the subtractor 856. .

[0093]

As is apparent from the above description, according to the present invention, the first pit row formed at a position shifted in one direction perpendicular to the track and the other pit row perpendicular to the track. Based on a reproduction signal when the light beam passes over the second pit row formed at a position shifted in the direction,
When the light beam passes over the first and second pit rows, the correction is performed based on the second TE signal for detecting the displacement between the light beam and the track.
In this case, the tracking control means is not operated in response to the TE signal, so that the offset caused by the offset in the header field, the displacement of the detector for detecting the first TE signal, and the displacement of the focusing lens due to the eccentricity of the disc are the first. The light beam is controlled at the center of the track even if it is generated in the TE signal.

[Brief description of the drawings]

FIG. 1 is a block diagram of an optical disc device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a header field and a total reflection light amount according to the first embodiment of the present invention.

FIG. 3 is a diagram illustrating a configuration of a header field and a total reflection light amount according to the first embodiment of the present invention.

FIG. 4 is a diagram showing a configuration of a header field and a total reflection light amount according to the first embodiment of the present invention.

FIG. 5 is a waveform chart for explaining a second TE signal according to the first embodiment of the present invention.

FIG. 6 is a waveform chart for explaining a gate signal of the gate signal generation circuit according to the first embodiment of the present invention.

FIG. 7 is a block diagram of an absolute value detection circuit according to the first embodiment of the present invention.

FIG. 8 is a waveform chart for explaining the absolute value detection circuit according to the first embodiment of the present invention.

FIG. 9 is a characteristic diagram of an LPF according to the first embodiment of the present invention.

FIG. 10 is a block diagram of a tracking control system according to the first embodiment of the present invention.

FIG. 11 is a characteristic diagram of a tracking control system according to the first embodiment of the present invention.

FIG. 12 is a waveform chart for explaining an effect obtained by adding an S / H circuit according to the first embodiment of the present invention;

FIG. 13 is a block diagram of an optical disk device according to a second embodiment of the present invention.

FIG. 14 is a schematic diagram showing a relationship between a light beam and a track according to the second embodiment of the present invention.

FIG. 15 is a waveform chart for explaining an effect obtained by adding a measuring circuit according to the second embodiment of the present invention.

FIG. 16 is a block diagram of an optical disc device according to a third embodiment of the present invention.

FIG. 17 shows first and second embodiments according to the third embodiment of the present invention.
Waveform diagram showing the TE signal of FIG.

FIG. 18 is a block diagram of an optical disc device according to a fourth embodiment of the present invention.

FIG. 19 illustrates first and second embodiments according to the fourth embodiment of the present invention.
Waveform diagram showing the TE signal of FIG.

FIG. 20 is a block diagram of an optical disc device according to a fifth embodiment of the present invention.

FIG. 21 is a schematic diagram of an optical disc in Embodiment 5 of the present invention.

FIG. 22 is a diagram illustrating a relationship between a first TE signal and a track according to the fifth embodiment of the present invention.

FIG. 23 is a block diagram of an unevenness determination circuit according to a fifth embodiment of the present invention.

FIG. 24 is a waveform chart for explaining the operation of the unevenness determination circuit according to the fifth embodiment of the present invention.

FIG. 25 is a waveform chart for explaining the operation of the LPF according to the fifth embodiment of the present invention.

FIG. 26 is a diagram illustrating a relationship between a first TE signal and a track according to the fifth embodiment of the present invention.

FIG. 27 is a schematic view of a disk of a conventional optical disk device.

FIG. 28 is a schematic diagram of a header field of a conventional optical disc device.

FIG. 29 is a schematic diagram showing a TE signal detection method by a push-pull method of a conventional optical disk device.

FIG. 30 is a diagram showing a relationship between a TE signal and a track by a push-pull method of a conventional optical disc device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 disk 101 motor 103 focusing lens 104 actuator 105 total reflection mirror 106 light beam 107 波長 wavelength plate 108 coupling lens 109 laser 110 deflection beam splitter 111 detection lens 112 cylindrical lens 113 photodetector 114 transfer motor 115 transfer table 116, 117, 118, 119 I / V converters 120, 121, 123, 124, 142 Adders 122, 125 Subtractors 131 Address regeneration circuits 132 Gate generation circuits 134 Absolute value detection circuits 135, 146, 157 LPFs 136, 137, 139 , 850 S / H circuit 140 Microcomputer 143, 149, 153 A / D converter 144, 150 Phase compensation filter 145, 152 Power amplifier 147, 151 D / A converter 156 Multiplier 1 71 Motor control circuit 175 Laser drive circuit

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiroyuki Yamaguchi 1006 Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. F-term (reference) 5D118 AA13 AA18 BA01 BB02 BC08 BC09 BF02 BF03 CA13 CD03 CD11 DA35

Claims (13)

[Claims] 1. A first pit row formed at a position shifted in one direction orthogonal to a track and a second pit row formed at a position shifted in the other direction orthogonal to a track.
A reproduction signal detecting means for detecting the information recorded on the disk by converging and irradiating a light beam on the disk on which the pit rows are arranged, and a track and a light beam based on the far field pattern of the reflected light or transmitted light from the disk. A first tracking error detecting means for detecting a positional shift, and a second tracking error detecting means for detecting a positional shift between the light beam and the track from the reproduced signals of the first pit train and the second pit train outputted by the reproduced signal detecting means. Tracking error detecting means, moving means for moving the light beam across the track,
Tracking control means for controlling the moving means so that the light beam is positioned on the track based on the output of the first tracking error detection means; and the tracking control based on the output of the second tracking error detection means An optical disk device comprising: a correction unit for changing a target position of the unit; and wherein the tracking control unit is set to a hold state when a light beam passes over the first and second pit rows. 2. A first pit row formed at a position shifted in one direction orthogonal to a track and a second pit row formed at a position shifted in the other direction orthogonal to a track.
A reproduction signal detecting means for detecting the information recorded on the disk by converging and irradiating a light beam on the disk on which the pit trains are arranged; A first tracking error detecting means for detecting a positional shift, and a second tracking error detecting means for detecting a positional shift between the light beam and the track from the reproduced signals of the first pit train and the second pit train outputted by the reproduced signal detecting means. Tracking error detecting means, moving means for moving the light beam across the track,
Tracking control means for controlling the moving means so that the light beam is positioned on the track based on the output of the first tracking error detection means; and the tracking control based on the output of the second tracking error detection means Correction means for changing a target position of the means, wherein the first tracking error detection means is set to a hold state when the light beam passes over the first and second pit rows. Optical disk device. 3. A first pit row formed at a position deviated in one direction perpendicular to the track and a second pit row formed at a position deviated in the other direction perpendicular to the track.
A reproduction signal detecting means for detecting the information recorded on the disk by converging and irradiating a light beam on the disk on which the pit rows are arranged, and a track and a light beam based on the far field pattern of the reflected light or transmitted light from the disk. A first tracking error detecting means for detecting a positional shift, and a second tracking error detecting means for detecting a positional shift between the light beam and the track from the reproduced signals of the first pit train and the second pit train outputted by the reproduced signal detecting means. Tracking error detecting means;
A first correction for correcting and outputting an output signal of the second tracking error detecting means based on an output level of the first tracking error detecting means immediately before or immediately after the pit train and the second pit train. Means, moving means for moving the light beam across the track, and tracking control means for controlling the moving means so that the light beam is positioned on the track based on the output of the first tracking error detecting means. An optical disk device, comprising: a second correction unit that changes a target position of the tracking control unit based on an output of the first correction unit. 4. An output value obtained by subtracting an output value of said first tracking error detection means immediately before or immediately after a first pit row and a second pit row from an output of a second tracking error detection means. 4. The optical disk device according to claim 3, wherein said optical disk device constitutes a first correction unit. 5. A first pit row formed at a position shifted in one direction orthogonal to a track and a second pit row formed at a position shifted in the other direction orthogonal to a track.
A reproduction signal detecting means for detecting the information recorded on the disk by converging and irradiating a light beam on the disk on which the pit rows are arranged, and a track and a light beam based on the far field pattern of the reflected light or transmitted light from the disk. A first tracking error detecting means for detecting a positional shift, and a second tracking error detecting means for detecting a positional shift between the light beam and the track from the reproduced signals of the first pit train and the second pit train outputted by the reproduced signal detecting means. Tracking error detecting means, moving means for moving the light beam across the track,
Tracking control means for controlling the moving means so that the light beam is positioned on the track based on the output of the first tracking error detection means; and an average of a predetermined period of the output of the second tracking error detection means Average value calculating means for calculating a value, and adjusting means for adding an offset to the output signal of the first tracking error detecting means so that the output of the average value calculating means becomes zero. Optical disk device. 6. An adjusting means for adjusting an offset of an output signal by subtracting an output value of an average value calculating means obtained in advance from an output of a first tracking error detecting means. The optical disk device according to claim 5, wherein 7. A first pit row formed at a position shifted in one direction orthogonal to a track and a second pit row formed at a position shifted in the other direction orthogonal to a track.
A reproduction signal detecting means for detecting the information recorded on the disk by converging and irradiating a light beam on the disk on which the pit rows are arranged, and a track and a light beam based on the far field pattern of the reflected light or transmitted light from the disk. A first tracking error detecting means for detecting a positional shift, and a second tracking error detecting means for detecting a positional shift between the light beam and the track from the reproduced signals of the first pit train and the second pit train outputted by the reproduced signal detecting means. Tracking error detecting means, moving means for moving the light beam across the track,
Tracking control means for controlling the moving means so that the light beam is positioned on the track based on the output of the first tracking error detection means; and the tracking control based on the output of the second tracking error detection means Correction means for changing the target position of the means, average value calculation means for calculating an average value of the output of the first tracking error detection means for a predetermined period, and the output means of the average value calculation means being zero. An optical disk device comprising: an adjusting unit that adds an offset to an output signal of the first tracking error detecting unit. 8. The apparatus according to claim 1, wherein the adjusting means adjusts an offset of the output signal by adding an output value of the average value calculating means obtained from an output of the first tracking error detecting means. The optical disk device according to claim 7. 9. The optical disk device according to claim 5, wherein the average value calculating means is configured to set the predetermined period to an integral multiple of a period during which the disk makes one revolution. 10. A first pit row formed at a position deviated in one direction perpendicular to a track and a second pit row formed at a position deviated in another direction perpendicular to a track. A reproducing signal detecting means for converging and irradiating a light beam on the disc on which the information is recorded and detecting the information recorded on the disc; and a positional deviation between the track and the light beam based on a far field pattern of the reflected light or transmitted light from the disc. A first tracking error detecting means for detecting, and a first pit train and a second pit string outputted from the reproduction signal detecting means.
Second tracking error detecting means for detecting a displacement between the light beam and the track from the reproduced signal of the pit train, moving means for moving the light beam across the track, and an output of the first tracking error detecting means. Tracking control means for controlling the moving means so that the light beam is positioned on the track based on the following, and correction means for changing a target position of the tracking control means based on the output of the second tracking error detection means. Prepare,
An optical disc device, wherein recording of information on a disc is stopped according to the level of an output signal of the second tracking error detecting means. 11. A tracking error detecting means for detecting a positional deviation between a continuous track formed by alternately connecting concave portions and convex portions and a light beam from a far field pattern of reflected light or transmitted light from a disk, and light Moving means for moving the beam across the track; tracking control means for controlling the moving means so that the light beam is positioned on the track based on the output of the tracking error detecting means; Polarity switching means for switching the polarity of the tracking control means, and adjusting means for adjusting the offset of the output signal of the tracking error detection means based on the output value of the tracking error detection means before and after the switching point of the concave and convex parts. An optical disc device, comprising: 12. The adjustment means is configured to add an offset at a point before the detection polarity switching so that the levels of the tracking error detection means immediately before and immediately after the switching point between the concave part and the convex part become equal. The optical disk device according to claim 11, wherein: 13. A preceding first pit row formed at a position deviated in one direction perpendicular to a track and a subsequent first pit row formed at a position deviated in the other direction perpendicular to the track. A reproduction signal for detecting information recorded on a disc by irradiating a light beam convergently on a disc arranged in a position where a pit row of 2 is deviated from a track in a concave track and a track in a convex section. Detecting means; first tracking error detecting means for detecting a positional deviation between a track and a light beam from a far-field pattern of reflected light or transmitted light from a disk; and a first pit row output from the reproduction signal detecting means; Second tracking error detecting means for detecting a positional deviation between the light beam and the track from the reproduction signal of the second pit row, and the light beam crossing the track. Moving means for moving the first
Tracking control means for controlling the moving means so that the light beam is positioned on the track based on the output of the tracking error detection means, and the polarity of detection of the first tracking error detection means in the concave and convex tracks. A first polarity switching means for switching the polarity so that the two coincide with each other, and a second polarity switching means for switching the polarity so that the detection polarity of the second tracking error detection means coincides with the track of the concave part and the convex part. An optical disk device comprising: a correction unit that changes a target position of the tracking control unit based on an output of the second tracking error detection unit.