JP2009187628A - Recording and reproducing device, wobble signal extraction circuit, and wobble signal extraction method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a recording and reproducing device, a wobble signal extraction method, and a wobble signal extraction circuit capable of precisely extracting a wobble signal with a simple structure. <P>SOLUTION: The recording and reproducing device includes: a detector 104a detecting a first signal (A+D) and a second signal (B+C) from two light receiving parts bisected with a boundary in an extending direction of a track 202 of an optical disk 200, respectively; a differential operational circuit 154 obtaining the wobble signal from the difference between the first signal (A+D) and the second signal (B+C); a GCA 152 adjusting the gain of the first signal (A+D) on the basis of a comparison result between an amplitude of the wobble signal and a target value; and a GCA 156 adjusting the gain of the second signal (B+C) on the basis of the output of the GCA 152. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a recording / reproducing apparatus, a wobble signal extraction circuit, and a wobble signal extraction method.

  In general, in a recording optical disc, address information for detecting a wobble signal is formed in advance in a track. For example, in the CD-R / RW, 22.05 kHz, which is a sufficiently low frequency with respect to the basic clock 4.3218 MHz of the RF signal to be recorded, is used as the basic frequency of the wobble signal. Further, in DVD + RW, 818 kHz close to the basic clock 26.16 MHz of the RF signal is used as the wobble signal frequency band.

  In order to detect a wobble signal, the optical disc recording / reproducing apparatus includes a light receiving element that is divided into at least two in the normal direction with respect to the laser trace direction. When the reflected light from the track is detected by the light receiving element divided into two, one light receiving signal is in the opposite phase of the other, so by calculating the difference signal (push-pull signal) by calculation, the wobble signal is obtained. Obtainable.

  However, in the data recording area on the optical disc, a data signal (hereinafter referred to as an RF signal) recorded on each received light signal is detected by being superimposed on the wobble signal. This RF signal can ideally be completely removed by the subtraction operation described above. However, in actuality, a level difference occurs between the respective received light signals before subtraction due to variations in the assembly accuracy of the light receiving elements and the variation in the light receiving sensitivity distribution, or fluctuation factors such as the remaining eccentricity and offset remaining by the servo. For this reason, there is a problem that the quality of the wobble signal is deteriorated due to noise remaining after subtraction.

  Therefore, for example, as described in Patent Document 1 below, when reproducing the recording area, the amplitude of each light receiving element output signal is input to a separate AGC (Auto Gain Control) circuit, and the RF of each signal is input. There is known a method of performing a subtraction operation after aligning signal amplitudes. Further, when reproducing an unrecorded area, these AGCs are generally set to a fixed gain. Furthermore, in the prior art, the ratio of the wobble component included in the signal is different between recording and reproduction, and the wobble amplitude obtained after subtraction varies due to a plurality of factors such as media and recording power. The first AGC is provided.

JP-A-8-194969

  However, the AGC circuit has a large circuit scale, a large area in the chip, and high power consumption. For this reason, when many AGC is provided like the said patent document 1, the problem that a circuit scale will increase and power consumption will also arise arises.

  Usually, an external capacitor is required for each AGC, and three terminals for connecting these capacitors to the LSI are also required. For this reason, there arises a problem that miniaturization of the LSI and the mounting area is hindered. Further, in the configuration of the above-mentioned Patent Document 1, since a switching signal between the AGC operation and the fixed gain operation is generated at the time of reproduction, it is necessary to reliably detect the recording area and the unrecorded area. Reliable detection is difficult.

  Accordingly, the present invention has been made in view of the above problems, and an object of the present invention is to provide a new and improved recording / reproducing apparatus capable of accurately extracting a wobble signal with a simple configuration. Another object is to provide a wobble signal extraction method and a wobble signal extraction circuit.

  In order to solve the above-described problem, according to an aspect of the present invention, a first signal and a second signal from each of two light receiving units divided into two with a direction in which a track of an optical recording medium extends as a boundary. Based on the result of comparison between the signal detection unit for detecting the wobble signal, the wobble signal acquisition unit for acquiring the wobble signal from the difference between the first signal and the second signal, and the target value and the amplitude of the wobble signal A first gain adjustment unit that adjusts the gain of the first signal; a second gain adjustment unit that adjusts the gain of the second signal based on the output of the first gain adjustment unit; Is provided.

  According to the above configuration, the first signal and the second signal are detected from each of the two light receiving sections divided into two with the direction in which the track of the optical recording medium extends as a boundary, and the first signal and the second signal are detected. The wobble signal is obtained from the difference from the signal. Then, the first gain adjustment unit adjusts the gain of the first signal based on the result of comparison between the amplitude of the wobble signal and the target value, and the second signal based on the output of the first gain adjustment unit. The gain of is adjusted. Therefore, it is possible to obtain a wobble extraction circuit having a constant amplitude and excellent in-phase component removal, and it is possible to obtain a wobble signal having a desired amplitude, and to reliably prevent an interference wave with respect to a wobble signal such as an RF signal or a recording signal waveform. Can be removed.

  In addition, a third gain adjustment unit that adjusts the gain of the first signal at a stage before the first gain adjustment unit, and a gain of the second signal at a stage before the second gain adjustment unit. A fourth gain adjusting unit, and a recording timing signal indicating that data is being recorded on the optical recording medium is input to the third and fourth gain adjusting units. The fourth gain adjustment unit may adjust the gains of the first and second signals in a stage preceding the first and second gain adjustment units according to the recording timing signal. According to such a configuration, the amplitude of the signal changes during recording and during reproduction. Therefore, by adjusting the gains of the first and second signals according to the recording timing signal, the wobble at the start and end of recording is achieved. It becomes possible to acquire the signal with high accuracy.

  An A / D converter that converts the wobble signal into digital data; a controller that outputs a control signal according to a result of comparison between the amplitude of the wobble signal converted into digital data and a target value; A D / A converter that converts the control signal into analog data, and the first gain adjuster adjusts the gain of the first signal based on the output of the D / A converter. There may be. According to such a configuration, it is possible to make the wobble signal amplitude as digital data constant, and it is possible to easily perform processing such as address detection by a subsequent circuit or clock extraction synchronized with disk rotation.

  Further, a wobble signal gain adjusting unit that adjusts the gain of the wobble signal converted into digital data based on the control signal may be provided. According to this configuration, the amplitude of the wobble signal is adjusted in the analog domain by adjusting the gain of the second signal based on the output of the first gain adjustment unit, and the wobble signal gain adjustment unit adjusts the wobble signal in the digital domain. The amplitude of the signal can be adjusted.

  In order to solve the above-described problem, according to another aspect of the present invention, the first signal and the second signal from each of the two light receiving sections divided into two with the direction in which the track of the optical recording medium extends as a boundary. And a result of comparison between the wobble signal amplitude and the target value, a signal detection unit that detects the signal 2, a wobble signal acquisition unit that acquires a wobble signal from the difference between the first signal and the second signal And a second gain adjustment for adjusting the gain of the second signal based on the output of the first gain adjustment unit. And a wobble signal extraction circuit.

  According to the above configuration, the first signal and the second signal are detected from each of the two light receiving sections divided into two with the direction in which the track of the optical recording medium extends as a boundary, and the first signal and the second signal are detected. The wobble signal is obtained from the difference from the signal. Then, the first gain adjustment unit adjusts the gain of the first signal based on the result of comparison between the amplitude of the wobble signal and the target value, and the second signal based on the output of the first gain adjustment unit. The gain of is adjusted. Therefore, it is possible to obtain a wobble extraction circuit having a constant amplitude and excellent in-phase component removal, and it is possible to obtain a wobble signal having a desired amplitude, and to reliably prevent an interference wave with respect to a wobble signal such as an RF signal or a recording signal waveform. Can be removed.

  In order to solve the above-described problem, according to another aspect of the present invention, the first signal and the second signal from each of the two light receiving sections divided into two with the direction in which the track of the optical recording medium extends as a boundary. 2 based on the result of detecting the signal of 2, the step of obtaining a wobble signal from the difference between the first signal and the second signal, and the comparison between the amplitude of the wobble signal and a target value, There is provided a wobble signal extraction method comprising: adjusting a gain of a first signal; and adjusting a gain of the second signal based on the first signal with the gain adjusted.

  According to the above configuration, the first signal and the second signal are detected from each of the two light receiving sections divided into two with the direction in which the track of the optical recording medium extends as a boundary, and the first signal and the second signal are detected. The wobble signal is obtained from the difference from the first signal, the gain of the first signal is adjusted based on the comparison result between the amplitude of the wobble signal and the target value, and the first signal is adjusted based on the first signal whose gain is adjusted. The gain of the second signal is adjusted. Therefore, it is possible to obtain a wobble extraction circuit having a constant amplitude and excellent in-phase component removal, and it is possible to obtain a wobble signal having a desired amplitude, and to reliably prevent an interference wave with respect to a wobble signal such as an RF signal or a recording signal waveform. Can be removed.

  According to the present invention, it is possible to provide a recording / reproducing apparatus, a recording / reproducing method, and a wobble signal extracting circuit capable of accurately extracting a wobble signal with a simple configuration.

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

  FIG. 1 is a schematic diagram showing a configuration of an optical disc recording / reproducing apparatus 100 according to an embodiment of the present invention. In FIG. 1, an optical disk 200 is rotated by a servo circuit 102 controlled at a predetermined number of rotations. The pickup 104 is controlled by the servo circuit 102 so that recording and reproduction can be performed at a predetermined position on the optical disc 200.

  A laser is emitted from the pickup 104 toward the optical disc 200. The laser is controlled to have a predetermined power by a laser power control circuit 106. For example, the pickup 104 causes the track to meander on the optical disc 200 to read prerecorded address information as a tracking signal (PP signal), and inputs the signal to an address decoding circuit (wobble signal extraction circuit) 150. The address decoding circuit 150 decodes the address information recorded on the optical disc 200 and sends the decoded signal to the disc controller 110. Thereby, the disk controller 110 gives a control signal to the servo circuit 102 in order to control the pickup 104 to a desired position. Therefore, data can be written at a desired position on the optical disc 200, and data can be read and reproduced from a desired position on the optical disc 200.

  At the time of data recording, the recording data is sent to the modulation circuit 112. The modulation circuit 112 performs modulation processing when recording on the optical disc 200. For example, in the case of a Blu-ray disc, 17 modulations are sequentially applied. These modulated data are input to the laser power control circuit 106, the laser is modulated according to the data, and the recording data is recorded on the optical disc 200.

  When data is read from the optical disc 200 and reproduced, first, a light intensity signal (RF signal) corresponding to the recording data is read by the pickup 104 and binarized by the binarization circuit 114 after waveform shaping. , 1 data and input to the demodulation circuit 116. The binarized signal input to the demodulation circuit 116 is subjected to, for example, EFM plus demodulation and output as reproduction data.

  Next, the detector of the pickup 102 that detects the track and laser spot of the optical disc 200 and the reflected light of the laser spot will be described with reference to FIG. FIG. 2A is a schematic diagram showing a state where the optical disc 200 is viewed from the top. As shown in FIG. 2A, a track 202 is formed on the disk surface of the optical disk 200 with wobbling. The laser spot 300 is irradiated from the lower side of the paper toward the upper side of the paper and is traced in the direction of the arrow a1. The reflected light of the laser spot 300 is detected by the detector 104a on the pickup 104.

  FIG. 2B is a schematic diagram showing the detector 104a. Here, it is assumed that the detector 104a is divided into four light receiving areas A, B, C, and D. By setting A and D as a set and B and C as a set, the light receiving region can be divided into two in the normal direction to the track trace direction (arrow a1 direction).

  FIG. 3 shows a signal (A + D), a signal (B + C), and a push-pull signal (A + D) − when the track 202 is traced by the detector 104a when the track 202 straddles the unrecorded portion and the recorded portion. It is a characteristic view which shows each signal waveform of (B + C). 3A shows the signal (A + D), FIG. 3B shows the signal (B + C), and FIG. 3C shows the push-pull signal (A + D) − (B + C). Yes. Further, FIG. 3 shows signal waveforms detected when tracing a recording portion where data is written on the optical disc 200 and an unrecorded portion where data is not written. In the unrecorded portion and the recorded portion, the (A + D) signal and the (B + C) signal are opposite in phase, so that a wobble waveform (push-pull signal (A + D) − (B + C)) is obtained by performing a differential operation. Can be detected. On the other hand, since the RF signals detected in the (A + D) signal and the (B + C) signal when tracing the recording unit are in-phase signals, they are canceled out by performing a differential operation. Therefore, it is possible to remove the RF signal and extract only the wobble signal.

  As described above, the operation of the optical disc recording / reproducing apparatus 100 includes a recording operation for recording data on the optical disc 200 in addition to a reproducing operation for tracing the unrecorded portion and the recording portion of the optical disc 200. During recording of data on the optical disc 200, a signal waveform (recording signal waveform) accompanying recording is superimposed as an in-phase signal with the (A + D) signal and the (B + C) signal in the same manner as the RF signal of the recording unit. The disturbing component due to the recording signal waveform is mainly caused by the return light of the laser beam when the write pulse is emitted from the pickup 102. As for the recording signal waveform, since the (A + D) signal and the (B + C) signal are in phase, only the wobble signal can be extracted by differential calculation as in the case where the recording unit is traced.

  FIG. 4 is a schematic diagram showing a circuit configuration of the address decoding circuit 150 of the present embodiment. As described above, the detector 104a has a function of detecting a signal divided into two in the normal direction with respect to the trace direction (the direction of the arrow a1). The detector shown in FIG. 4 is divided into four parts A, B, C, and D, and signals obtained by dividing into two in the normal direction by obtaining (A + D) and (B + C) signals by calculation. Can be detected.

  The (A + D) signal and the (B + C) signal are removed from the DC component, and then the (A + D) signal is amplified by the gain control amplifier (GCA) 152 and input to the differential operation circuit 154. On the other hand, the (B + C) signal is amplified by a gain control amplifier (GCA156) and input to the differential operation circuit 154. At this time, the control circuit 158 compares the output signal of the GCA 152 and the output signal of the GCA 156, and generates a control signal so that the amplitude of the waveform output from the GCA 156 is the same as the amplitude of the waveform output from the GCA 152. , Input to GCA156. The GCA 156 adjusts the amplitude of the waveform output from the GCA 156 based on the input control signal. As a result, the amplitude of the output signal of GCA 156 follows the amplitude of the output signal of GCA 152.

  The differential operation circuit 154 performs a differential operation on the (A + D) signal and the (B + C) signal whose amplitudes are equalized by the GCAs 152 and 156, so that the RF signal when the recording unit is traced and the recording signal at the time of writing are recorded. A wobble signal is extracted by removing an in-phase component such as a waveform. Here, since the amplitude of the output signal of the GCA 156 follows the amplitude of the output signal of the GCA 152, an in-phase component such as an RF signal or a recording signal waveform is highly accurate from the wobble signal extracted by the differential arithmetic circuit 154. Has been removed. The output of the differential arithmetic circuit 154 is output to the subsequent address detection block as a wobble signal after the high frequency noise component left by the filter 160 is removed.

  Further, the output of the filter 160 is input to the controller 162. The controller 162 receives the target amplitude value of the wobble signal. The controller 162 compares the amplitude of the wobble signal output from the filter 160 with the amplitude target value, generates a control signal that matches the amplitude of the wobble signal and the amplitude target value, and inputs the control signal to the GCA 152. In this manner, the controller 162 can feed back the insufficient amplitude of the wobble signal with respect to the amplitude target value to the GCA 152.

  This makes it possible to extract a wobble signal having a desired amplitude when tracing a recorded part or an unrecorded part or when recording data on the optical disc 200. Therefore, the amplitude of the wobble signal can be adjusted so as to be suitable for the circuit at the subsequent stage. In addition, during reproduction, the amplitude of the two signals input to the differential arithmetic circuit 154 can be made uniform regardless of whether the currently traced portion on the track 202 is a recorded portion or an unrecorded portion. Therefore, there is no need for a separate circuit for detecting whether the recorded portion or the unrecorded portion is being reproduced.

  As described above, the wobble signal extraction circuit (address decoding circuit 150) according to the present embodiment compares the output of the differential arithmetic circuit 154 with the amplitude target value, and adjusts the amplitude of the output signal of the GCA 152 based on the result. At the same time, the amplitude of the output signal of the GCA 156 is made to follow the amplitude of the output signal of the GCA 152. Therefore, it is possible to obtain a wobble extraction circuit having a constant amplitude and excellent in-phase component removal, and it is possible to obtain a wobble signal having a desired amplitude, and to reliably prevent an interference wave with respect to a wobble signal such as an RF signal or a recording signal waveform. Can be removed.

  Therefore, conventionally, an AGC is required for each of the (A + D) signal and the (B + C) signal, and a third AGC is required after the differential operation circuit in order to obtain a wobble signal having a constant amplitude. On the other hand, by adopting the configuration of FIG. 4, the GCA 156 for matching the amplitude of (B + C) with the amplitude of (A + D) and the wobble amplitude after the differential operation are made constant. By using two AGC configurations by the GCA 152 that applies feedback to the amplifier, it is possible to reduce the AGC circuit that requires a large circuit area and power in the analog circuit. In addition, when a target value is set for each of the (A + D) signal and the (B + C) signal and individually controlled, each signal is not always controlled to the target value, so the wobble signal It is assumed that the detection accuracy is lowered. In the present embodiment, since the (B + C) signal follows the (A + D) signal, it is possible to suppress a decrease in the detection accuracy of the wobble signal. Furthermore, by causing the (B + C) signal to follow the (A + D) signal, the GCAs 152 and 156 are temporarily saturated during the transition period, such as when the trace area is shifted from the recorded part to the unrecorded part. Even so, it is possible to accurately detect the wobble signal.

  In the present embodiment, the configuration of matching the amplitude of the (B + C) signal with the amplitude of the (A + D) signal is shown, but the configuration of matching the amplitude of the (A + D) signal with the amplitude of the (B + C) signal is used. May be fed back to the GCA156. Further, the control time constant of the controller 158 is preferably set shorter than the control time constant of the controller 162.

  In this embodiment, the control time constant is determined by the feedback loop composed of the controller 162 and the GCA 152. Even when the control time constant is changed according to the situation, the common-mode component removal performance is affected. The setting can be changed without giving it. For example, when separate AGCs are constituted by the (A + D) signal and the (B + C) signal and are fed back to each other, the in-phase component removal performance is deteriorated due to a time difference that changes each control time constant. In the present embodiment, since the controller 162 and the GCA 152 constitute a feedback loop, such a decrease in common-mode component removal performance can be reliably prevented.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. FIG. 5 is a schematic diagram showing a circuit configuration of the address decoding circuit 150 according to the second embodiment. In the configuration of FIG. 5, a gain control amplifier (GCA) 170 is added before the GCA 152 and a gain control amplifier (GCA) 172 is added before the GCA 156 compared to the configuration of FIG. 4 of the first embodiment. Has been. The output signal of GCA 170 is input to amplifier 152, and the output signal of GCA 172 is input to amplifier 156. The other configuration of FIG. 5 is the same as that of FIG. The (A + D) signal and the (B + C) signal are removed from DC, and then gains are adjusted by gain control amplifiers 170 and 172 (hereinafter referred to as GCA).

  When data is recorded on the optical disc 200, a recording timing signal, which is a signal indicating the time of data recording, is sent to the GCA 170, 172 from the control circuit (disk controller 110) on the system side. When the GCA 170 or 172 receives the input of the recording timing signal, the GCA 170 or 172 performs control to lower the gain than usual. Therefore, the gains of the GCAs 170 and 172 can be adjusted according to the operating state of the optical disc recording / reproducing apparatus 100, and the interference wave component can be removed according to the operating state.

  According to the above configuration, since the amplitude of the signal changes between recording and reproduction, the gains of GCA 170 and 172 are preliminarily determined based on the recording timing signal with respect to signal amplitude fluctuations at the start and end of recording. Adjust. As a result, the convergence of the feedback loop formed by the controller 162 and the GCA 152 can be accelerated. Further, since the amplitude of the signal becomes larger at the time of recording than at the time of reproduction, it is possible to minimize the input range of the subsequent amplifiers GCA 152, 156, etc. by lowering the gain by GCA 170, 172 in advance. Thereby, in the amplifiers 152, 156 and the like at the subsequent stage, it is only necessary to determine the input range according to the signal when the unrecorded part or the recorded part is traced, and it becomes unnecessary to expand the input range more than necessary.

(Third embodiment)
Next, a third embodiment of the present invention will be described. FIG. 6 is a schematic diagram showing a circuit configuration of the address decoding circuit 150 according to the third embodiment. In the third embodiment, a part of the configuration of the first embodiment shown in FIG. 4 is digitized.

  As shown in FIG. 6, in the third embodiment, an A / D converter 180 is provided in the subsequent stage of the differential operation circuit 154, and the subsequent stages of the differential operation circuit 154 are digitized. The filter 182 and the controller 184 correspond to the filter 160 and the controller 162 of the first embodiment, but the output of the differential operation circuit 154 is converted into digital data by the A / D converter 180. Therefore, the filter 182 The controller 184 performs digital processing. By configuring the filter 182 as a digital filter, manufacturing cost can be reduced even when a high-order filter is used. The control value which is the output of the controller 184 is converted into an analog instruction value by the D / A converter 186, and the GCA 152 is controlled by this instruction value. The digital domain after the A / D converter 180 has a function of feeding back amplitude information to the GCA 152. An analog filter such as an anti-aliasing filter may be added between the differential arithmetic circuit 154 and the A / D converter 180.

  According to the configuration as described above, it is possible to make the wobble signal amplitude as digital data constant, and it becomes easy to extract a clock synchronized with address detection or disk rotation. Therefore, when a circuit such as a PLL is arranged at the subsequent stage of the address decoding circuit 150, a wobble signal as digital data can be input to the subsequent circuit as it is. As a result, when using a phase comparator in which the gain changes according to the amplitude, etc., it is possible to prevent the gain from being lowered by the filter in the previous stage to be inserted into the phase comparator, and it is suitable for the circuit in the subsequent stage. A wobble signal having a desired amplitude can be obtained.

  Further, when the controller 184 with amplitude detection is configured by an analog circuit, an LPF having a sufficiently low cutoff is required in order not to detect an interference signal component, or a peak hold circuit is used to grasp the outline of the amplitude. Is performed. In either case, a large external capacity may be required. According to the configuration of the present embodiment, by digitizing the controller 184, an external capacitor is not necessary, and the circuit scale can be reduced and the power consumption can be reduced.

(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described. FIG. 7 is a schematic diagram showing a circuit configuration of an address decoding circuit 150 according to the fourth embodiment. In the fourth embodiment, a GCA 188 that adjusts the amplitude of the wobble signal is provided after the A / D converter 180 in the digitized circuit of FIG. 6, and feedback by the controller 184 is divided into GCA 152 and GCA 188. is there.

  As shown in FIG. 7, the output of the A / D converter 180 is input to the GCA 188, and the output is input to the filter 182. The controller 184 generates a control signal so that the output of the filter 182 matches the amplitude target value of the wobble signal. The control signal is input to the GCA 188, and the amplitude of the wobble signal is adjusted based on the control signal.

  The control signal output from the controller 184 is converted into an analog instruction value by the D / A converter 186 and then input to the GCA 152. For example, when it is necessary to control the amplitude of the wobble signal beyond the control range of the GCA 188, the gain of the GCA 152 is increased or decreased via the D / A converter 186. Since the output amplitude of the GCA 156 follows the output amplitude of the GCA 152 by the controller 158, the amplitude of the wobble signal can be adjusted even in the analog domain.

  According to the configuration as described above, amplitude adjustment by the GCA 188 is performed on the signal digitized by the A / D converter 180, so that the amplitude adjustment of the wobble signal can be performed with higher accuracy. In the analog domain, the amplitude of the wobble signal can be adjusted by the GCA 152 and 156, and in the digital domain, the amplitude of the wobble signal can be adjusted by the GCA 188. For this reason, even when the resolution of the D / A converter 186 is relatively low, the amplitude can be accurately adjusted by the GCA 188 at the subsequent stage. Accordingly, it is possible to perform control such as adjusting the wobble signal amplitude with relatively coarse accuracy by the preceding GCAs 152 and 156 and finely adjusting the amplitude by the subsequent GCA 188, and setting the resolution of the D / A converter 186 low. Is possible. In order to perform fine amplitude adjustment in the digital domain, the time constant of the control signal from the controller 184 to the GCA 188 is set shorter than the time constant for controlling the GCA 152 from the controller 184 via the D / A converter 186. It is desirable to do.

  As a result, the GCA 152 in the analog unit can have a circuit configuration with low resolution, and in addition to the reduction in resolution of the D / A converter 186, the circuit scale can be reduced and the power consumption can be reduced. Further, since the signal amplitude input to the A / D converter 180 can be normalized to some extent in the analog domain, the quality of the extracted wobble signal can be improved even if the resolution of the A / D converter 180 is lowered. It can be secured.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the example which concerns. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

1 is a schematic diagram showing a configuration of an optical disc recording / reproducing apparatus according to an embodiment of the present invention. It is a schematic diagram showing a detector of a pickup that detects a track of an optical disc, a laser spot, and reflected light of the laser spot. It is a characteristic view which shows each signal waveform of RF signal (A + D), RF signal (B + C), push pull signal (A + D)-(B + C). It is a schematic diagram which shows the circuit structure of the address decoding circuit which concerns on 1st Embodiment. It is a schematic diagram which shows the circuit structure of the address decoding circuit which concerns on 2nd Embodiment. It is a schematic diagram which shows the circuit structure of the address decoding circuit which concerns on 3rd Embodiment. It is a schematic diagram which shows the circuit structure of the address decoding circuit which concerns on 4th Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Recording / reproducing apparatus 104a Detector 154 Differential arithmetic circuit 152,156,170,172,188 GCA
180 A / D converter 184 Controller 186 D / A converter 200 Optical disc 202 Track

Claims (6)

A signal detection unit for detecting the first signal and the second signal from each of the two light receiving units divided into two with a direction in which the track of the optical recording medium extends as a boundary;
A wobble signal acquisition unit that acquires a wobble signal from a difference between the first signal and the second signal;
A first gain adjusting unit that adjusts a gain of the first signal based on a result of comparison between an amplitude of the wobble signal and a target value;
A second gain adjusting unit that adjusts a gain of the second signal based on an output of the first gain adjusting unit;
A recording / reproducing apparatus comprising: A third gain adjusting unit that adjusts the gain of the first signal before the first gain adjusting unit;
A fourth gain adjustment unit that adjusts the gain of the second signal before the second gain adjustment unit;
A recording timing signal indicating that data is being recorded on the optical recording medium is input to the third and fourth gain adjustment units,
The third and fourth gain adjustment sections adjust the gains of the first and second signals in the previous stage of the first and second gain adjustment sections according to the recording timing signal. The recording / reproducing apparatus according to claim 1. An A / D converter for converting the wobble signal into digital data;
A controller that outputs a control signal according to a result of comparison between the amplitude of the wobble signal converted into digital data and a target value;
A D / A converter for converting the control signal into analog data,
The recording / reproducing apparatus according to claim 1, wherein the first gain adjustment unit adjusts the gain of the first signal based on an output of the D / A conversion unit.   The recording / reproducing apparatus according to claim 3, further comprising a wobble signal gain adjusting unit that adjusts a gain of the wobble signal converted into digital data based on the control signal. A signal detection unit for detecting the first signal and the second signal from each of the two light receiving units divided into two with a direction in which the track of the optical recording medium extends as a boundary;
A wobble signal acquisition unit that acquires a wobble signal from a difference between the first signal and the second signal;
A first gain adjusting unit that adjusts a gain of the first signal based on a result of comparison between an amplitude of the wobble signal and a target value;
A second gain adjusting unit that adjusts a gain of the second signal based on an output of the first gain adjusting unit;
A wobble signal extraction circuit comprising: Detecting the first signal and the second signal from each of the two light receiving sections divided into two with the direction in which the track of the optical recording medium extends as a boundary;
Obtaining a wobble signal from the difference between the first signal and the second signal;
Adjusting the gain of the first signal based on a result of comparison between the amplitude of the wobble signal and a target value;
Adjusting the gain of the second signal based on the first signal with the gain adjusted;
A wobble signal extraction method comprising:

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