JP2650385B2 - Target position adjustment method for tracking control - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tracking control for driving a moving means in accordance with a signal from a track deviation detecting means and controlling a reproducing position to always be located on a track. In particular, the present invention relates to a target position adjustment method for tracking control.

2. Description of the Related Art Conventionally, a light beam generated from a light source is converged and irradiated on a rewritable record carrier such as a phase change optical disk or a magneto-optical disk, and tracking is performed so that the light beam on the record carrier is positioned on a track. 2. Description of the Related Art There is known an optical disk device which performs recording or reproduction of a signal while controlling (for example, Japanese Patent Application No. 55-125283).

An uneven guide groove (track) for recording a signal is provided on the record carrier in advance, and reflected light or transmitted light from the record carrier is received by a photodetector having a two-part structure. The position shift (track shift) between the light beam on the record carrier and the track is detected from the difference in the light amounts of the two.

More specifically, the photocurrents of both photodetectors are subjected to current-voltage conversion, and the difference between the voltages is obtained by a differential amplifier to obtain a track shift signal.

After this track shift signal is processed by the tracking control circuit, the light beam on the record carrier is applied to a tracking actuator that moves in a direction substantially perpendicular to the longitudinal direction of the track, and the light beam on the record carrier is positioned on the track. Tracking control.

The control target of the tracking control is a position on the track where the output of the differential amplifier for obtaining the track shift signal is a predetermined value, that is, the light amount received by both photodetectors is equal. Is controlled to always be located at

Problems to be Solved by the Invention In the above-described apparatus, it is very important to maintain compatibility because the record carriers are exchangeable. That is, when a signal recorded by another device is reproduced with high reliability, or when a signal recorded by another device is erased and a new signal is recorded, a signal recorded by another device is not erased and remains. It is necessary to erase accurately.

In order to achieve compatibility, all devices require tracking control so that the light beam on the record carrier is accurately located at a reference position of the track, for example, at the center of the track.

For this purpose, the target position of tracking control must be the same in all devices.

As described above, the tracking control is performed so that the output of the differential amplifier for obtaining the track deviation signal has a predetermined value, but the target position of the tracking control differs depending on the device.

Causes of this occurrence include, for example, a sensitivity difference between the two-split photodetectors, a difference between the conversion rates of the two I / V converters that convert the photocurrent into a voltage, and a gain difference between the differential amplifiers that obtain the track shift signal. .

Also, the aberration of the light beam on the record carrier, and the manner in which the reflected light reflected by the record carrier or the transmitted light transmitted by the optical system that guides the light to the two-segment photodetector slightly differs depending on the device. The state of the light beam on the two-segment photodetector varies. If the state of the light beam on the two-segment photodetector varies, the target position of the tracking control also varies, and the compatibility deteriorates.

As described above, the conventional apparatus does not adjust the target position of the tracking control for each apparatus, and thus varies depending on the apparatus, and as a result, compatibility between the apparatuses is poor.

SUMMARY OF THE INVENTION An object of the present invention is to provide an adjustment method that eliminates the above-mentioned drawbacks and allows a target position for tracking control to accurately match a desired target position.

Means for Solving the Problems The present invention is directed to a first method for irradiating a light beam generated from a light source onto a record carrier and detecting a positional deviation between the light beam and the track from reflected light or transmitted light from the record carrier. And a second amplifier circuit, and a differential amplifier for calculating a difference between output signals of the first and second amplifier circuits, and performs tracking control based on a signal of the differential amplifier so that a light beam is positioned on a track. In a tracking control apparatus for recording a signal on a track or reproducing a recorded signal, a deviation of a target position for tracking control is detected, and first and second amplifications are performed based on the detected target position deviation signal. The target position of the tracking control is adjusted by changing both circuit gains of the circuit, one of the circuit gains, or the differential circuit gain of the differential amplifier.

According to the above-described method, the target position of the tracking control is changed by changing the circuit gain of both the first and second amplifier circuits or one of the circuit gains or the differential circuit gain of the differential amplifier based on the target position shift signal. Is adjusted so that the target position of the tracking control is the same in all devices.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the drawings, the same numbers are used for the same numbers.

FIG. 1 shows an embodiment in which the present invention is applied to an optical recording / reproducing apparatus.

A light beam 2 generated from a light source 1 such as a semiconductor laser is
After being converted into substantially parallel light by the coupling lens 3, the light is reflected by the polarization beam splitter 4, passes through a 収束 wavelength plate, and is converged by the converging lens 6 onto the information carrier surface of the disc-shaped record carrier 7 for irradiation. .

The record carrier 7 provided with the uneven groove track is
The motor 8 is attached to a rotation shaft and is rotated at a predetermined rotation speed.

Reflected light 9 of light beam 2 reflected by record carrier 7
Is passed through a converging lens 6, a quarter-wave plate 5, and a polarizing beam splitter 4, and is irradiated onto a photodetector 10 having a two-segment structure.

The converging lens 6 is attached to a tracking actuator 11, and the tracking actuator 11 is configured to move the converging lens 6 in a radial direction of the record carrier, that is, in a width direction of a track on the record carrier 7.

A light source 1, a coupling lens 3, a polarizing beam splitter 4, a quarter-wave plate 5, a photodetector 10, and a tracking actuator 11 are fixed to a transfer table 12, and are integrated integrally by a linear motor 13 in the radial direction of the record carrier. It is configured to move.

The photodetector 10 is composed of, for example, a PIN photodiode, and a reverse bias voltage Vcc is supplied to the photodetector 10 via a signal reproducing circuit 40. Therefore, the photodetector 10
All the photocurrent passes through the signal regeneration circuit 40,
Detects a signal recorded on the record carrier 7 from the change in the photocurrent.

The respective photocurrents of the photodetector 10 are supplied to the I / V converters 14 and 1
After the current is converted into a voltage by 5, the current is input to the differential amplifier 16 and the adder circuit 17, respectively. The differential amplifier 16 outputs a signal corresponding to the difference between the two input signals, and the adder circuit 17 outputs a signal corresponding to the sum of the two input signals.

The direction of the division line of the photodetector 10 is the track direction on the irradiation surface of the reflected light 9, and the differential amplifier 16 outputs a signal corresponding to the position shift between the light beam 2 on the record carrier 7 and the track, ie, the track shift. Output a signal.

The signal of the differential amplifier 16 and the signal of the adding circuit 17 are input to the dividing circuit 18, and the dividing circuit 18 outputs a signal corresponding to a value obtained by dividing the signal of the differential amplifier 16 by the signal of the adding circuit 17. .

The addition circuit 17 adds the signals of the I / V converters 14 and 15 and outputs a signal obtained by removing a high-frequency component of the added signal, for example, a component of 50 KHz or more by a low-pass filter.
By removing the high frequency components in this manner, it is possible to remove disturbances due to noise on the record carrier, scratches or address signals of the tracks recorded in the form of irregularities on the tracks, and more stably perform the tracking control. can do.

The signal of the division circuit 18 is tracked through a phase compensation circuit 21 for compensating the phase of the tracking control system, a switch 22 for disabling the tracking control, an addition circuit 23, and a drive circuit 24 for power amplification. It is added to the actuator 11. The output signal of the switch 22 is supplied to the linear motor 13 via a drive circuit 25 for power amplification.
Has been added to

Therefore, when the switch 22 is short-circuited, the tracking actuator 11 and the linear motor 13 are driven according to the signal of the differential amplifier 16 so that the light beam 2 on the record carrier 7 is located on the track.

 The effect of the division circuit 18 will be described.

Signal output of the differential amplifier 16 for unit track deviation,
That is, the track shift detection sensitivity changes according to the light amount of the light beam 2 generated from the light source 1, the reflectance of the record carrier 7, the sensitivity of the photodetector 10, the light transmission rate of the optical system, and the like. If the track shift detection sensitivity changes, the gain of the tracking control system changes when there is no division circuit 18, so that the tracking control becomes unstable, or in some cases, oscillates and the tracking control is not applied. I will. According to the configuration of the present invention, even if the track shift detection sensitivity changes by N times for the above-described reason, the signal of the adder circuit 17 also becomes N.
Since the signal output is doubled, the signal output of the division circuit 18 with respect to the unit track deviation becomes constant, and the gain does not change, so that the tracking control can be made extremely stable.

Briefly describing the search for the desired track,
An address signal is recorded in advance on a track on the recording medium 7 in the form of irregularities, and a search is performed based on the address signal. The address is read by the address reading circuit from the signal of the signal reproducing circuit 40 or the signal of the adding circuit 17 (not shown).

The microcomputer (MPU) 26 detects the address of the track on which the light beam 2 is located on the record carrier 7 from the signal of the address reading circuit, and finds the difference from the address of the desired track. If the value is larger than the value, a rough inspection is performed. That is, a signal corresponding to the address difference is sent to the drive circuit 25 via the line 27, and the switch 22 is sent via the line 28.
A signal to release is made to disable the tracking control. When the transfer table 12 is moved in the radial direction of the record carrier 7 by the linear motor 13 and the light beam 2 comes close to the desired track, the MPU 26 stops the signal transmitted through the line 27 and switches the switch 22. The tracking control is operated by short-circuiting, and the address of the track on which the light beam 2 is located on the record carrier 7 is read. When the track is different from the desired track, an address difference from the desired track is obtained, and when this value is smaller than a predetermined value, a fine search in which one jumping is repeated a number of times corresponding to the difference is performed to perform the desired search. Search for a track. One jumping scan is MPU26
To open the switch 22 and send a signal via the line 29 to drive the tracking actuator 11 to move the light beam 2 on the record carrier 7 to the next track and short-circuit the switch 22 again.

Hereinafter, adjustment of the target position of the tracking control will be described.

The signal reproduction circuit 40 is a low-frequency component of the reproduced signal,
For example, a signal obtained by removing a component of 10 KHz or less by a high-pass filter is transmitted to the separation circuit 31.

A target position adjustment area is provided on the record carrier 7 at an outer peripheral portion or an inner peripheral portion which is not normally used. The target position adjustment region includes one adjustment circumferential track for positioning a light beam during adjustment, The first adjacent to the adjustment circumferential track
And three circumferential tracks of a second circumferential track. F1 and f2 for the first and second circumferential tracks
A single frequency signal, eg, a first circumferential track,
A signal of 1.0 MHz and a signal of 1.5 MHz are respectively recorded in advance on the second circumferential track in the form of irregularities.

One circumferential track means one concentric track when the track on the record carrier is concentric, and starts from a point A on the track when the track on the record carrier is spiral, and goes around the record carrier once. It means a track up to a point B which intersects a straight line connecting the point A and the center of the record carrier.

When adjusting the target position, the MPU 26 first searches for the adjustment circumferential track, and performs tracking control so that the light beam 2 on the record carrier 7 is located on the adjustment circumference track. When the track on the record carrier 7 is spiral, one back is made every time the record carrier 7 makes one rotation, and still control is performed so that the record carrier 7 is located on the same circumference.

The adjustment of the target position is performed by detecting signals of the frequencies f1 and f2 mixed by crosstalk in a state where the light beam 2 on the record carrier 7 is controlled to be positioned on the adjustment circumferential track.

The separation circuit 31 has a frequency f1,
The signal of f2 is separated, each signal is subjected to envelope detection, and this detected signal is sent to the differential amplifier 32. Differential amplifier 32
A / D converter 33 outputs a signal corresponding to the difference between the two input signals, and converts this signal from an analog signal to a digital signal.
Send to The A / D converter 33 converts the signal of the differential amplifier 32 into a digital signal, and sends the digital signal to the MPU 26. M
The PU 26 detects a direction in which the target position of the tracking control is deviated from the value of the A / D converter 33, and shifts the target position in the detected direction via the I / V converters 14 and 15 via a line 41. Send a signal to The I / V converters 14 and 15 are configured such that the circuit gain changes according to the signal of the MPU 26,
U26 increases the gain of the I / V converter 14 by N1 and the gain of the I / V converter 15 by 1 / N1. Therefore, the target position of the tracking control changes according to the signal of the MPU 26.

The MPU 26 changes the gain of the I / V converters 14 and 15 while checking the output of the A / D converter 33 so that the target position gradually approaches the desired position, and sets the value of the A / D converter 33 to a predetermined value. Within the range.

FIG. 2 shows the output of the differential amplifier 32 with respect to the track shift. The horizontal axis indicates the track shift and the vertical axis indicates the output of the differential amplifier 32. As can be seen from the figure, the output of the differential amplifier 32 increases in the positive direction when it deviates in one direction from the true target position, and the output of the differential amplifier 32 deviates in the opposite direction.
Output increases in the negative direction. Therefore, the deviation amount of the target position can be easily measured from the value of the A / D converter 33. That is, the MPU 26 sets the I / V with respect to the value of the A / D converter 33.
The values to be sent to the converters 14 and 15 may be stored in a table in advance. For example, when setting the gain of the I / V converter 14, a value GO corresponding to the value of the A / D
After the target position of the tracking control is shifted, the value of the A / D converter 33 is measured again, and if this value is not within a predetermined value range, the value of the A / D converter 33 is measured. The value G1 to be sent to the I / V converter 14 corresponding to the above is obtained, and the value obtained by multiplying G0 and G1 (G0 * G1) is sent to the I / V converter 14. The same applies to the value to be sent to the I / V converter 15.

The MPU 26 repeats the above until the value of the A / D converter 33 falls within a predetermined range. By doing so, the number of repetitions is reduced, and the target position can be set at high speed. In addition, the MPU 26 is an A / D converter
If the value of 33 does not fall within the predetermined range, it is regarded as abnormal and an abnormal signal is generated, and at least the recording operation is stopped. In this way, not only can the abnormality of the device be known from the outside, but also since erroneous recording is not performed, the reliability of the device can be improved.

In FIG. 1, the gains of the I / V converters 14 and 15 are changed, but one of the gains may be changed. However, when the gain is changed, the frequency characteristic also changes.Therefore, when the range of the gain to be changed is wide, if the gain of both the I / V converters 14 and 15 is changed as described above, the range of each change is narrowed. And a change in frequency characteristics can be reduced.

Also, the relationship between the value of the A / D converter 33 and the value to be sent to the I / V converters 14 and 15 is functionalized, and the value to be sent by calculation is calculated from the value of the A / D converter 33. Is also good. In this way, the memory required for the table can be omitted, and the cost can be reduced.

The separating circuit 31 will be described with reference to FIG. 3. The separating circuit 31 includes an equalizer 101, band filters 102 and 103 for extracting the signals of f1 and f2, and a band filter 10
Detection circuit 104 for envelope detection of 2,103 signals
And 105.

When reproducing the signal on the record carrier 7, the amplitude of the reproduced signal differs depending on the frequency of the recorded signal. Although it differs depending on the frequency characteristics of the photodetector 10 and the signal reproducing circuit 40, it largely depends on the spatial frequency of the signal recorded on the record carrier 7. That is, the frequency characteristics of the amplitude of the reproduced signal are substantially determined by the beam diameter of the light beam 2 on the record carrier 7 and the pit length of the signal. The equalizer 101 is provided to correct the frequency characteristics of the reproduced signal amplitude. Therefore, since the frequency characteristic is corrected by the equalizer 101, when the target position of the tracking control is at a correct position, the output of the detection circuit 104 becomes equal, and the adjustment is simplified.

The target position adjustment area provided in advance on the record carrier 7 will be described with reference to FIG.

FIG. 4 is an enlarged and exaggerated drawing of a part of the plane of the record carrier 7, wherein 111 is a first circumferential track on which a single frequency f1 is recorded, and 112 is a single circumferential track on which a single frequency f2 is recorded. The reference numeral 113 denotes a circumferential track for adjustment between the tracks 111 and 112, and the reference numeral 114 denotes a normal track for recording a signal. Track 11
1 is composed of the pit row indicated by 116, and the track 112 is composed of the pit row indicated by 117. W1 indicates the width of the tracks 113, 114 and 115, and W2 indicates the width of the tracks 111 and 112. If W1 <W2, the amount of crosstalk from the tracks 111 and 112 increases when the target position of tracking control is adjusted so that the light beam 2 is positioned on the track 113. Therefore, the bandpass filter shown in FIG. 102 and 1
The S / N ratio of the output of 03 can be improved, and more accurate adjustment can be performed.

The skew (inclination) due to the surface deflection of the record carrier 7 differs depending on the location. Generally, it is small at the inner periphery and larger at the outer periphery. Therefore, the target position adjustment area is provided in two places of the inner circumference and the outer circumference where no signal is recorded, and the value to be set in the I / V converters 14 and 15 when adjusted in the inner circumference and the outer circumference are different. The values to be set in the I / V converters 14 and 15 at the time of the adjustment are obtained, and the average value of each is set in the I / V converters 14 and 15 so that recording or reproduction is performed. Reliability can be improved.

Also, target position adjustment areas are provided at a plurality of locations, for example, at predetermined intervals, adjustment is performed in all target position adjustment areas, respective adjustment values are stored, and I / V conversion is performed depending on a track to be recorded or reproduced. If the values set in the devices 14 and 15 are changed, the reliability of the device can be further improved. In this case, an area to be recorded / reproduced is determined for one target position adjustment area using the address of the track, and is set in the I / V converters 14 and 15 when a desired track is searched. By doing so, the time required for setting can be reduced, and there is no system problem.

By pre-recording information that can be identified as the target position adjustment track on the adjustment circumferential track, it is possible to identify when the address signal cannot be read due to dropout or the like, or when the address signal is read erroneously. The processing of the apparatus can be simplified and the reliability can be improved.

When a target position adjustment area as shown in FIG. 4 is provided, when a signal is recorded on the tracks 114 and 115 adjacent to the track 111 and the track 112, or when the recorded signal is reproduced, the signal is recorded on the track 111 or the track 112. Signal may be affected. Therefore, track 114
And 115, it is desirable to manage the system so that no signal is recorded.

In order to eliminate the above-mentioned disadvantage, the target position adjustment area may be set as shown in FIG.

FIG. 5 is an enlarged and exaggerated drawing of a part of the plane of the record carrier 7 as in FIG.
Is recorded on the center of the first circumferential track, 122
Indicates the center of the second circumferential track on which the single frequency f2 is recorded, 123 indicates the sensor of the adjusting circumferential track, and 124 and 125 indicate the centers of the tracks adjacent to the target position adjustment area. P1 indicates the distance between the centers 121 and 123 and the centers 122 and 123, that is, the track pitch, and P2
Indicates the distance between the centers 121 and 124 and the centers 122 and 125, respectively. If the normal track pitch is P0,
When P1 <P0 <P2, and the light beam is located on the center 124 or 125, the influence of the crosstalk of the signals recorded on the first and second circumferential tracks is small, When it is located on a circumferential track, the influence of crosstalk is large. Therefore, the information signal can be recorded also on the track adjacent to the target position adjustment area,
A decrease in the recording capacity can be prevented.

The target position adjustment area provided on the record carrier 7 in advance may be formed as shown in FIG.

FIG. 6 is an enlarged and exaggerated drawing of a part of the plane of the record carrier 7, where 131 is a first circumferential track on which a single frequency f1 is recorded, and 132 is a single circumferential track on which a single frequency f2 is recorded. The reference numeral 133 denotes a circumferential track for adjustment located between the tracks 131 and 132, and 134 and 135 denote tracks adjacent to the target position adjusting area. When the height difference between the track 136 and the track 136, that is, the groove depth of the track is 1 / 8λ (λ is the wavelength of the light beam 2), the pits 137 formed in the tracks 131 and 132 are formed.
Has a depth of 1 / 8λ. That is, the bottom surface of the gap 136 and the bottom surface of the pit 137 are the same. In this case, the production of the record carrier becomes extremely easy.

Further, the depth of the pit 137 can be set to 1 / 4λ.
By doing so, the amplitude of the reproduced signal increases, and the S / N
Since the ratio is improved, more accurate adjustment can be performed.

Further, the target position adjustment area provided on the record carrier 7 may be formed as shown in FIG.

FIG. 7 is an enlarged and exaggerated drawing of a part of the plane of the record carrier 7, 143 is an adjusting circumferential track between the tracks 144 and 145, and 141 is recorded between the tracks 143 and 144. Pit row of single frequency f1, 142 is track 1
The pit train of single frequency f2 recorded between 43 and 145 is shown. Thus, between tracks f1, f
The signal of 2 may be recorded. In this case, in order not to adversely affect the track shift signal, it is desirable that the signal be provided in the recording material layer in the same form as the normal signal.

If the adjustment of the target position is automatically performed immediately after the power of the apparatus is turned on or immediately after the exchange of the record carrier, the reliability of the apparatus is improved.

Further, if the temperature rise of the device is detected and the adjustment is performed according to the predetermined temperature rise, the reliability of the device can be further improved.

In addition, if the adjustment is performed using the idle time of the apparatus at every predetermined time, the temperature sensor and the like become unnecessary, and the reliability of the apparatus can be improved.

Further, when the apparatus is not used, the light beam may be automatically positioned on the adjustment circumferential track, and readjustment may be performed when the target position is shifted due to temperature or the like.

Although the present invention has been described in detail, the present invention should not be limited by the examples.

For example, the form of the signal recorded on the tracks 111 and 112 in FIG. 4 may be the same as the form of the signal recorded on the record carrier 7, for example, light and shade recording. In this case, it is desirable to record the data using a reference device determined after the completion of the record carrier, and to record the same signal on all record carriers.

Also, instead of changing the gain of the I / V converters 14 and 15,
The target position of tracking control may be adjusted by moving the photodetector 10 in a direction perpendicular to the track direction on the detection surface.

Further, the output of the differential amplifier 16 is V0, the I / V converters 14 and 1
When the output signal of 5 is V1 and V2, there is a relation of V0 = G2 * V1-G3 * V2 = G2 (V1-G3 / G2V2). You may comprise so that the target position of tracking control may be adjusted. Here, G2 and G3 are coefficients.

Further, in the embodiment, the reflection optical system is used.
It may be a transmission optical system. In this case, the transmitted light transmitted through the record carrier may be received by the photodetector, and the received signal may be used in the same manner as in the embodiment shown in FIG. That is, various optical systems have been devised, but the present invention is not based on the optical system.

Further, even if the present invention is applied to an optical reproducing apparatus, the target position of tracking control is adjusted to a predetermined position,
The quality of the reproduced signal is improved, and the device can be made more reliable.

According to the present invention, since the target position of the tracking control is adjusted to a predetermined position, the compatibility between the devices is improved, the reliability of recording and reproduction is significantly improved, and the effect is extremely large. .

In particular, if the automatic adjustment is performed based on the signal provided in the target position adjustment area of the tracking control on the record carrier, all the devices are adjusted based on the record carrier to be used. , You can maintain even more compatibility.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of the apparatus of the present invention, FIG. 2 is a relationship diagram showing a relationship between a track shift and an output of a differential amplifier, FIG. 3 is a block diagram of a separation circuit, and FIG. FIGS. 5, 6, and 7 are enlarged views of the target position adjustment area in the first embodiment of the record carrier of the present invention, and FIGS. 5, 6, and 7 are enlargements of the target position adjustment area in another embodiment of the record carrier of the present invention. FIG. DESCRIPTION OF SYMBOLS 1 ... Light source, 3 ... Coupling lens, 4 ... Polarization beam splitter, 5 ... 1/4 wavelength plate, 6 ... Convergent lens, 7 ... Record carrier, 10 ... Photodetector, 12 ... Transfer table,
13 …… Linear motor, 14,15 …… I / V converter, 16,32 ……
Differential amplifier, 17,23 …… Addition circuit, 18… Division circuit, 21
…… Phase compensation circuit, 22 …… Switch, 24,25 …… Drive circuit, 26 …… Microcomputer, 31 …… Separation circuit, 33
... A / D converter, 40 ... Signal reproduction circuit.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Shinichi Yamada 1006 Kazuma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. Inside

Claims (3)

(57) [Claims] A recording medium having a guide groove is irradiated with a light beam generated from a light source to detect a positional deviation between the light beam and the track from a difference in intensity distribution of a beam pattern of reflected light or transmitted light from the guide groove. And a differential amplifier for calculating the difference between the output signals of the first and second amplifier circuits, and recording on a record carrier from reflected light or transmitted light from the record carrier. A reproducing circuit that reproduces a signal that has been recorded, and records or records a signal recorded on the guide groove while performing tracking control so that the light beam is positioned on the guide groove based on the signal of the differential amplifier. A method for adjusting a target position of a tracking control to be reproduced, wherein first and second signals arranged to be deviated left and right with respect to the center of a guide groove are reproduced by the reproduction circuit, and both reproduction signals are reproduced. Based on the difference And adjusting the target position of the tracking control by changing the circuit gain of one of the first and second amplifier circuits or one of the circuit gains. 2. A light beam generated from a light source is radiated onto a record carrier having a guide groove, and a positional deviation between the light beam and the track is detected from a difference in intensity distribution of a beam pattern of reflected light or transmitted light from the guide groove. Photodetector having at least two detection regions for detecting a difference between the two output signals (V1, V2) of the photodetector V0 = G2 * V1−G3 * V2 (where G2,
G3 is a differential amplifier for calculating a coefficient), and a reproducing circuit for reproducing a signal recorded on the record carrier from reflected light or transmitted light from the record carrier. A tracking control target position adjusting method for recording a signal on a guide groove or reproducing a recorded signal while performing tracking control so that a beam is positioned on the guide groove, wherein the target position is adjusted left and right with respect to the center of the guide groove. The first and second signals arranged in the same position are reproduced by the reproducing circuit, and the value of one or both of the coefficients G2 and G3 of the differential amplifier is changed based on the difference between the two reproduced signals. A target position adjustment method for tracking control, characterized by adjusting a target position for tracking control. 3. A record carrier having a guide groove is irradiated with a light beam generated from a light source to detect a positional deviation between the light beam and the track from a difference in intensity distribution of a beam pattern of reflected light or transmitted light from the guide groove. Photodetector provided with at least two detection areas for performing the operation, a differential amplifier for calculating a difference between both output signals of the photodetector, and a signal recorded on a record carrier from light reflected or transmitted from the record carrier. A reproducing circuit for reproducing a signal which is recorded on the guide groove while reproducing control of the light beam on the guide groove based on the signal of the differential amplifier or reproducing the signal recorded on the guide groove. A target position adjusting method for tracking control, wherein a first signal and a second signal, which are arranged to be deviated left and right with respect to the center of a guide groove, are reproduced by the reproducing circuit, and both reproduced signals are reproduced. A target position for tracking control by moving the photodetector in a direction perpendicular to the direction of the guide groove on the detection surface based on the difference between the two.