JP2007035112A - Error signal generating apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an error signal generating apparatus which can generate an error signal reduced in a track crossing component when performing a middle point position servo in a track search. <P>SOLUTION: In a photodetecting part 35 for detecting reflected light from a recording plane of an optical disk DK, an MPP signal generating part 41 generates an MPP (Main Beam Push-Pull) signal based on respective phtodetecting signal output from the phtodetecting part 35 having a photo-diode divided into a plurality of parts, also a DPD (Differential Phase Detection) signal generating part 42 generates a DPD signal based on respective photodetecting signal, and an operation part 43 generates an LE (Lens Error) signal based on the MPP signal and the DPD signal. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present application generates an error signal for performing a midpoint position servo or the like when searching for a desired track on an optical recording medium in an information recording / reproducing apparatus that records or reproduces information on the optical recording medium The present invention relates to a technical field of an error signal generation apparatus.

  In an information recording / reproducing apparatus that performs recording or reproduction on an optical recording medium such as an optical disc, in order to search for a desired track on the optical disc, an objective lens that is a condensing means by a feed motor or the like is used. After the optical pickup is moved in the radial direction of the optical disk, a tracking servo pull-in operation is performed.

  When the objective lens swings in the radial direction of the optical disc during such movement, the objective lens is displaced from a preset reference position, so that the position of the objective lens is stabilized at the reference position even after the optical pickup is stopped. Until then, the pull-in operation cannot be performed stably.

  Note that the reference position is a position uniquely determined by the design of the information recording / reproducing apparatus, but is the center position of the objective lens in the tracking direction and the focusing direction, for example, as the so-called midpoint position.

  Therefore, in recent years, so-called midpoint position servo is performed in which the position of the objective lens during track search is controlled to the midpoint in order to stabilize the tracking servo pull-in operation after searching for a desired track.

  The midpoint position servo generates a LE (Lens Error) signal, which is an error signal indicating the positional deviation of the objective lens, from a signal obtained by detecting the reflected light from the optical disk by a light detection unit such as a photodiode. This is done based on the signal.

  For example, as in the midpoint servo device described in Patent Document 1, an MPP (Main Beam Push-Pull) signal generated from a light detection signal obtained by receiving reflected light from an optical disc and an SPP (Sub Beam Push) Generally, a LE (lens error) signal is generated by calculating a -Pull signal.

  Specific examples thereof will be described below. FIG. 1 is a diagram showing an example of the waveform of each signal when the LE signal is generated based on the MPP signal and the SPP signal, and (a) is a case where the objective lens is located at the midpoint. (B) is a case where the objective lens has shifted | deviated from the middle point. FIG. 2 is a diagram showing an example of the waveform of each signal when the LE signal is generated based only on the MPP signal. FIG. 2A shows the case where the objective lens is located at the middle point. ) Is when the objective lens is displaced from the midpoint.

  In the optical pickup, the light beam emitted from the laser diode is diffracted into three beams of zero-order light and ± first-order light by a grating element or the like, and then condensed on the recording surface of the optical disk by the objective lens. Then, the light beam is reflected by the recording surface of the optical disc and is applied to the light detection unit as reflected light.

  In the light detection unit, the main beam (0th-order light beam) and sub-beam (± 1st-order light beam) of the reflected light are received by photodiodes that are divided into four parts, respectively, and the amount of light received from each photodiode. A corresponding light detection signal is output.

  In the error signal generation device, an MPP signal is generated for the main beam and an SPP signal is generated for the sub beam by the push-pull method based on the light detection signal output from the light detection unit. Then, the LE signal is generated by adding the MPP signal and the SPP signal.

  During the track search, the waveforms of the MPP signal, the SPP signal, and the LE signal generated as described above are as shown in FIG.

  During track search, a DC component corresponding to a deviation from the midpoint position may appear in the MPP signal and the SPP signal (FIG. 1B), and a plurality of light beams condensed on the recording surface of the optical disk may be present. Therefore, a so-called track crossing component indicating that the track has been passed appears as waveforms of the MPP signal and the SPP signal.

Here, since the SPP signal has substantially the same waveform that is shifted in phase by π with respect to the MPP signal, by adding the MPP signal and the SPP signal as described above, the cross-track component is generated as shown in FIG. It is possible to generate an LE signal from which only the DC component corresponding to the displacement from the midpoint of the objective lens is extracted.
JP-A-11-224430

  However, the conventional error signal generating apparatus described above requires a grating element for dividing the light beam into a main beam and a sub beam, which leads to an increase in the size of the optical pickup.

  On the other hand, when the optical pickup is configured excluding the grating element, the SPP signal cannot be obtained because there is only one main beam.

  Therefore, since the LE signal is generated only from the MPP signal, the cross-track component remains in the LE signal as shown in FIG. 2, and a stable LE signal cannot be obtained.

  Therefore, the present application has been made in view of the above points. As an example of the problem, the track crossing component is reduced even with a single light beam when performing midpoint position servo during track search. An object of the present invention is to provide an error signal generation device that can generate an error signal.

  In order to solve the above problems, the invention according to claim 1 is preset for the light collecting means of the light collecting means for condensing the light beam emitted from the light source on the recording surface of the optical recording medium. In the error signal generating apparatus that generates an error signal indicating a positional deviation from a reference position, the light receiving unit that outputs the reflected light from the recording surface to each of the areas from a light detection unit that receives the reflected light from the divided areas. Push-pull signal generating means for generating a push-pull signal based on a light detection signal according to the amount, and each light detection signal based on the light detection signal output for each region from the light detection means. A phase difference signal generating means for generating a phase difference signal indicating a phase difference; and an error signal for generating the error signal based on the generated push-pull signal and the generated phase difference signal. A generation unit, characterized in that it comprises a.

  In order to solve the above problem, the invention according to claim 5 includes the push-pull signal generation means, the phase difference signal generation means, and the error signal generation means, and further, based on the generated error signal. 5. The error signal generation device according to claim 1, further comprising a control signal generation unit configured to generate a control signal for controlling the condensing unit to be positioned at the reference position. An optical pickup having the light collecting means and the light detecting means, and further having a moving means for moving the light collecting means in the radial direction based on the generated control signal. To do.

  Hereinafter, the best embodiment of the present application will be described in detail with reference to the drawings. In the embodiment described below, the present application is applied to an actuator servo circuit that generates an LE signal for performing midpoint position servo in an information recording / reproducing apparatus that records and reproduces information with respect to an optical disc. This is an embodiment.

[1] First Embodiment [1.1] Configuration of Information Recording / Reproducing Device RP First, the configuration of the information recording / reproducing device RP according to the present embodiment will be described with reference to FIGS.

  FIG. 3 is a diagram illustrating an example of a schematic configuration of the information recording / reproducing apparatus RP according to the first embodiment. FIG. 4 is a diagram showing an example of a schematic configuration of the actuator servo circuit AS according to the first embodiment.

  As shown in FIG. 3, the information recording / reproducing apparatus RP includes a control unit C, an LD drive circuit LDD, a feed motor servo circuit SS, a feed motor SM, an optical pickup PU, an actuator servo circuit AS, and an actuator drive. And a circuit AD.

  The control unit C is mainly configured by a CPU (Central Processing Unit) and controls each unit of the information recording / reproducing apparatus RP. For example, when recording data on the optical disc DK, the control unit C outputs a recording drive signal corresponding to the input data to the LD drive circuit LDD, while reproducing the data recorded on the optical disc DK. When performing, a driving signal for reproduction is output to the LD driving circuit LDD.

  The LD drive circuit LDD is mainly composed of an amplifier circuit, amplifies the drive signal input from the control unit C, and then supplies the amplified signal to a laser diode 31 (to be described later) of the optical pickup device PU.

  The feed motor servo circuit SS supplies a drive signal to the feed motor SM and counts the number of moving tracks on the basis of a light detection signal supplied from a light detection unit 35 described later, and instructs it by an instruction signal from the control unit C. The feed motor SM is controlled so that the optical pickup moves to the track.

  The actuator drive circuit AD amplifies the control signal supplied from the actuator servo circuit AS, and then supplies it to an actuator 34 (to be described later) of the optical pickup device PU.

  The feed motor SM is configured to move the optical pickup in the radial direction of the optical disc by being rotationally driven based on the drive signal supplied from the feed motor servo circuit SS.

  The optical pickup PU includes a laser diode 31, a beam splitter 32, an objective lens 33 as a condensing unit, an actuator 34, and a light detection unit 35 as a light detection unit.

  The laser diode 31 emits a light beam having a predetermined wavelength based on the drive signal supplied from the LD drive circuit LDD.

  The beam splitter 32 transmits the light beam emitted from the laser diode 31 and reflects the reflected light from the optical disk to the right side of the paper.

  The objective lens 33 condenses the light beam on the optical disc DK and transmits the reflected light from the optical disc to enter the beam splitter 32.

  The actuator 34 holds the objective lens 33 with a lens folder, a wire, and the like, and moves the objective lens 33 in the radial direction and the vertical direction of the optical disc based on a control signal supplied from the actuator drive circuit AD. Thus, tracking and focusing are realized, and midpoint position servo is realized at the time of track search.

  The light detection unit 35 includes a light receiving unit 35a including photodiodes MA, MB, MC, and MD.

  The light receiving unit 35a receives reflected light from the optical disc by the photodiodes MA, MB, MC, and MD, and outputs light detection signals Sma, Smb, Smc, and Smd corresponding to the amount of received light from each photodiode.

[1.2] Configuration of Actuator Servo Circuit AS Next, the configuration of the actuator servo circuit AS according to the present embodiment will be described.

  As shown in FIG. 4, the actuator servo circuit AS includes an MPP signal generation unit 41 as a push-pull signal generation unit, a DPD (Differential Phase Detection) signal generation unit as a phase difference signal generation unit, and an error signal generation unit. And a lens position control circuit 44.

  The MPP signal generation unit 41 includes adders 411 and 412 and a subtracter 413, and generates an MPP signal by a push-pull method based on each photodetection signal output from the photodetection unit 35. .

  The adder 411 adds the light detection signals Sma and Smd and outputs a signal Smad, and the adder 412 adds the light detection signals Smb and Smc and outputs a signal Smbc.

  The subtractor 413 generates an MPP signal by subtracting the signal Smbc from the signal Smad.

  The DPD signal generation unit 42 includes, for example, an equivalent circuit, a binarization circuit, a phase comparison circuit, and the like. Based on each photodetection signal output from the photodetection unit 35, a phase difference method (differential push) DPD signal which is a phase difference signal indicating the phase difference between the respective photodetection signals is generated.

  Specifically, for example, each photodetection signal is waveform-equivalent and binarized, and then the phase comparison between the photodetection signals Sma and Smb and the phase comparison between Smc and Smd are performed. A DPD signal is generated by adding and integrating the resulting signals.

  The calculation unit 43 is configured by, for example, an operational amplifier, a resistor, and the like, and an error signal is obtained by subtracting the MPP signal output from the MPP signal generation unit 41 and the DPD signal output from the DPD signal generation unit 42. The LE signal is generated, and this signal is supplied to the lens position control unit 44.

  The lens position control unit 44 supplies a control signal for positioning the objective lens 33 at the middle point to the actuator drive circuit AD based on the LE signal supplied from the calculation unit 43.

[1.3] Operation of Actuator Servo Circuit AS Next, the operation of the actuator servo circuit AS according to the present embodiment will be described.

  When the optical disk DK is inserted into the information recording / reproducing apparatus according to the present embodiment and the user performs an input operation for recording or reproducing information on the optical disk DK with respect to the operation unit (not shown), the optical disk The DK rotates and the track moves, for example, downward in the drawing of FIG.

  Then, the control unit C supplies a drive signal to the LD drive circuit LDD according to the input operation.

  The LD drive circuit LDD supplied with the drive signal from the control unit C outputs a predetermined drive signal to the laser diode 31.

  As a result, a light beam is emitted from the laser diode 31, passes through the beam splitter 32, and is condensed on the recording surface of the optical disk DK by the objective lens 33.

  Then, the light beam is reflected by the recording surface of the optical disc DK and is incident on the beam splitter 32 as reflected light, and is then reflected rightward on the paper surface to be condensed on the light detection unit 35.

  Here, when the control unit C supplies an instruction signal to the feed motor servo circuit SS in order to record or reproduce information on a desired track, the feed motor servo circuit SS A drive signal is supplied to the SM.

  Then, the feed motor SM moves the optical pickup PU in the radial direction of the optical disk, for example, to the right of the paper surface based on the supplied drive signal. The optical pickup PU irradiates the optical disc with a light beam while moving rightward on the paper surface.

  Reflected light from the optical disk DK is received by each photodiode of the light receiving unit 35a, and a light detection signal is output from each of them.

  The adder 411 of the MPP signal generation unit 41 adds the light detection signal output from the light detection unit 35 to Sma and Smd to generate a signal Smad, and the adder 412 outputs the light detection signal to Smb and Smc. Is added to generate the signal Smbc.

  Then, the subtractor 413 subtracts the signal Smbc from the signal Smad to generate an MPP signal.

  On the other hand, the DPD signal generation unit 42 receives each photodetection signal output from the photodetection unit 35 and generates a DPD signal.

  Then, the calculation unit 43 generates an LE signal by subtracting the MPP signal output from the MPP signal generation unit 41 and the DPD signal output from the DPD signal generation unit 42.

  Thereafter, the lens position control unit 44 generates a control signal based on the LE signal, and supplies this signal to the actuator drive circuit AD.

  Then, the control signal amplified by the actuator drive circuit AD is supplied to the actuator 34, and based on this control signal, the actuator 34 moves the objective lens 33 in the radial direction of the optical disc, thereby realizing the midpoint position servo. It will be.

[1.4] Principle of reducing the cross-track component of the LE signal Next, the principle of reducing the cross-track component of the LE signal in this embodiment will be described with reference to FIGS. 5 and 6.

  FIG. 5 is a diagram illustrating the waveform relationship between the generated MPP signal and the DPD signal in the first embodiment. FIG. 6 is a diagram showing an example of the waveform of each signal when the LE signal is generated based on the MPP signal and the DPD signal in the first embodiment. FIG. 6A shows the objective lens positioned at the midpoint. (B) shows the case where the objective lens is deviated from the middle point.

  First, the waveform of the MPP signal will be described.

  When the optical disk DK is irradiated with a light beam, the light reflected by the pits and the diffracted light interfere with each other, thereby generating a region where the light intensity is weakened in the reflected light received by the light receiving unit 35a. To do. The light intensity distribution of the reflected light changes depending on the positional relationship between the irradiated light beam and the pits.

  In the on-track state where the light beam is applied to the center of the pit, the light intensity of the reflected light received by the photodiodes MA and MD matches the light intensity of the reflected light received by the MB and MC. The level of the MPP signal generated by the MPP signal generation unit 41 is 0 (position indicated by a circle in FIG. 5).

  When the optical pickup PU moves, the light beam is shifted from the center of the pit to the right side of the drawing in FIG. 4, the light intensity of the reflected light received by the photodiodes MA and MD is MB and Since the light intensity of the reflected light received by the MC becomes stronger, the generated MPP signal exhibits positive polarity.

  In the case where the light beam is completely displaced from the center of the pit and is applied to the center of the guide groove, the light intensities of both coincide with each other, and the generated MPP signal becomes 0 level.

  Thereafter, when the light beam approaches the adjacent pit and is shifted to the left side of FIG. 4 from the pit, the light intensity of the reflected light received by the photodiodes MA and MD is MB and Since the light intensity of the reflected light received by the MC becomes weaker, the generated MPP signal exhibits negative polarity.

  When the on-track state is entered again, the MPP signal becomes 0 level.

  In this way, the track crossing component appears as the waveform of the MPP signal during the track search.

  Further, when the objective lens 33 is deviated from the middle point, even if the light beam is applied to the center of the pit, the position where the light receiving unit 35a receives the reflected light is deviated, so that the photodiodes MA and MD receive light. The light intensity of the reflected light does not match the light intensity of the reflected light received by the MB and MC. Therefore, a direct current component corresponding to this deviation appears in the MPP signal.

  Next, the waveform of the DPD signal will be described.

  When the track passes the light beam due to the rotation of the optical disk DK, the light intensity distribution of the reflected light received by the light receiving unit 35a changes, but when the track passes with a deviation from the center of the light beam. There is a difference between the phase of the light intensity distribution of the reflected light received by the photodiode MA and the phase of the light intensity distribution of the reflected light received by the MB (the same applies to the relationship between MC and MD).

  In the case of the on-track state, the phase of the reflected light received by the photodiode MA and the reflected light received by the MB match, so the DPD signal generated by the DPD signal generating unit 42 is as shown in FIG. 0 level (position indicated by a circle).

  When the optical pickup PU moves, the light beam is shifted from the center of the pit to the right side of FIG. 4, the phase of the reflected light received by the photodiode MA is reflected by the MB. Since the phase of the light advances, the generated MPP signal exhibits positive polarity.

  When the light beam is irradiated to the center of the guide groove completely deviating from the center of the pit, the phase of both coincides and the generated DPD signal becomes 0 level.

  After that, when the light beam approaches the adjacent pit and is shifted to the left side of the paper in FIG. 4 from the pit, the phase of the reflected light received by the photodiode MA is reflected by the MB. Since it lags behind the phase of light, the generated DPD signal shows negative polarity.

  When the on-track state is entered again, the DPD signal becomes 0 level.

  In this way, a track crossing component also appears in the waveform of the DPD signal during track search.

  As shown in FIG. 5, although the MPP signal and the DPD signal have different waveforms, as is clear from the above description, the phase of the cross-track component is the same, and in this embodiment, the polarities thereof also match. .

  Therefore, the cross-track component of the waveform of the LE signal generated by subtracting the DPD signal from the MPP signal is reduced compared to the waveform when the LE signal is generated from only the MPP signal shown in FIG.

  Further, although a DC component corresponding to the deviation from the middle point of the objective lens 33 appears in the MPP signal, since the DC component hardly appears in the DPD signal, subtracting the DPD signal from the MPP signal as shown in FIG. In addition, a DC component corresponding to the deviation remains.

  As described above, according to the present embodiment, the received light amount output from the light detection unit 35 that receives the reflected light from the recording surface of the optical disc DK by a plurality of divided photodiodes for each photodiode. The MPP signal generation unit 41 generates an MPP signal based on the corresponding light detection signal, and the DPD signal generation unit 42 generates a DPD signal based on each light detection signal, based on the MPP signal and the DPD signal. Since the computing unit 43 generates the LE signal, it is possible to generate the LE signal with the track crossing component reduced even with a single light beam when performing the midpoint position servo during the track search.

  Further, since the calculation unit 43 generates the LE signal by subtracting the DPD signal from the MPP signal, it is possible to generate the LE signal with the track crossing component reduced even with a single light beam with a simple configuration. .

  In this embodiment, the LE signal is generated by subtracting the DPD signal from the MPP signal. However, the LE signal may be generated by subtracting the MPP signal from the DPD signal.

[1.5] Modified Example Next, a modified example of the present embodiment will be described.

  In the present embodiment described above, the MPP signal and the DPD signal have the same polarity, but the polarity may be reversed depending on the design of the information recording / reproducing apparatus RP.

  In this case, the arithmetic unit 43 may be configured to add, not subtract, the MPP signal and the DPD signal.

  Alternatively, a polarity reversing circuit may be added as a polarity reversing unit to invert the polarity of either the MPP signal or the DPD signal, and then the subtracting may be performed by the calculation unit 43.

  As described above, according to the present modification, it is possible to generate an LE signal with a track crossing component reduced even with a single light beam with a simple configuration, and the degree of freedom in designing the information recording / reproducing apparatus RP. improves.

  Next, another modification of the present embodiment will be described.

  When the LE signal is generated based on the MPP signal and the DPD signal, the track crossing component of the signal is reduced, but an LPF (Low Pass Filter) or the like is added as a low-pass means to cut the LE signal track. You may comprise so that a component may be removed further. As a result, it is possible to generate an LE signal in which the track crossing component is further reduced.

  Further, when the LE signal is generated from only the MPP signal, the remaining track crossing component is large, so that a circuit for reducing the component becomes relatively expensive. However, according to the present embodiment, the LE signal Therefore, an inexpensive circuit or the like can be used.

[2] Second Embodiment Next, an actuator servo circuit AS2 according to a second embodiment of the present application will be described with reference to FIG.

  FIG. 7 is a diagram showing an example of a schematic configuration of the actuator servo circuit AS2 according to the second embodiment. In FIG. 7, elements similar to those in FIG. 4 are denoted by the same reference numerals.

  In the first embodiment described above, the LE signal is generated by analog processing of the MPP signal and the DPD signal. In the second embodiment described below, the LE signal is generated by digital processing. Generate a signal.

  As shown in FIG. 7, the actuator servo circuit AS2 includes an MPP signal generator 41, a DPD signal generator 42, A / D (Analog / Digital) converters 45a and 45b as digitizing means, and a DSP (Digital Signal). Processor) 46.

  The A / D converters 45a and 45b perform analog / digital conversion on the MPP signal and the DPD signal, respectively, and supply the digitized MPP signal and DPD signal to the DSP 46.

  The DSP 46 includes a calculation unit 461 as an error signal generation unit and a lens position control unit 462. The DSP 46 generates a control signal by performing digital signal calculation processing at a high speed, and sends this signal to the actuator 34. Supply.

  The computing unit 461 generates a digitized LE signal by performing computation such as addition processing on the digitized MPP signal and DPD signal supplied from the A / D converters 45a and 45b, and outputs this signal. This is supplied to the lens position control unit 462.

  The lens position control unit 462 generates a control signal by performing arithmetic processing or the like on the supplied LE signal.

  In the actuator servo circuit AS2 configured as described above, an MPP signal is generated by the MPP signal generator 41 and a DPD signal is generated by the DPD signal generator 42 as in the case of the first embodiment.

  Then, the generated MPP signal and DPD signal are digitized by the A / D converters 45a and 45b, and the digitized LE signal obtained by computing the digitized MPP signal and DPD signal by the computing unit 461 is obtained. Generated.

  During the track search, the influence of passing through the track also appears in the digitized MPP signal and DPD signal. By calculating the MPP signal and the DPD signal, the track is tracked as in the first embodiment. An LE signal with reduced crossover components is generated.

  The lens position control unit 462 generates a control signal based on the LE signal, and supplies this signal to the actuator 34, thereby realizing the midpoint position servo.

  As described above, also in the present embodiment, the reflected light from the recording surface of the optical disk DK is received by the photodiodes that are divided into a plurality of photodiodes according to the amount of light received for each photodiode. The MPP signal generator 41 generates an MPP signal based on the photodetection signal, and the DPD signal generator 42 generates a DPD signal based on each photodetection signal, and the DSP 46 based on the MPP signal and the DPD signal. Since the calculation unit 461 generates the LE signal, it is possible to generate the LE signal with the track crossing component reduced even with a single light beam when performing the midpoint position servo during the track search.

  Also, the MPP signal and the DPD signal are digitized by the A / D converters 45a and 45b, respectively, and the computing unit 461 of the DSP 46 computes the digitized MPP signal and DPD signal to generate the LE signal. The quality of the LE signal can be further improved.

It is a figure which shows an example of the waveform of each signal at the time of producing | generating LE signal based on MPP signal and SPP signal, (a) is a case where an objective lens is located in the middle point, (b) is an objective lens Is deviated from the midpoint. It is a figure which shows an example of the waveform of each signal at the time of producing | generating a LE signal based only on a MPP signal, (a) is a case where an objective lens is located in the middle point, (b) is a case where an objective lens is a middle. This is the case when the point is deviated. It is a figure which shows an example of schematic structure of the information recording / reproducing apparatus RP which concerns on 1st Embodiment. It is a figure which shows an example of schematic structure of actuator servo circuit AS which concerns on 1st Embodiment. FIG. 3 is a diagram for explaining a waveform relationship between a generated MPP signal and a DPD signal in the first embodiment. In 1st Embodiment, it is a figure which shows an example of the waveform of each signal at the time of producing | generating LE signal based on MPP signal and DPD signal, (a) is a case where the objective lens is located in the middle point, (B) is a case where the objective lens has shifted | deviated from the middle point. It is a figure which shows an example of schematic structure of actuator servo circuit AS2 which concerns on 2nd Embodiment.

Explanation of symbols

35 Photodetector 35a Light receiver 41 MPP signal generator 44 Lens position controller 31 Laser diode 32 Beam splitter 33 Objective lens 34 Actuator 42 DPD signal generator 43 Arithmetic unit 45a, 45b A / D converter 46 DSP
411, 412 Adder 413 Subtractor 461 Calculation unit 462 Lens position control unit RP Information recording / reproducing device PU Optical pickup C Control unit LDD LD drive circuit SS Feed servo circuit SM Feed motor AD Actuator drive circuit AS, AS2 Actuator servo circuit

Claims (5)

An error signal generation device for generating an error signal indicating a positional deviation of a light collecting unit for condensing a light beam emitted from a light source on a recording surface of an optical recording medium from a reference position preset for the light collecting unit. In
A push-pull signal that generates a push-pull signal based on a light detection signal corresponding to the amount of received light that is output for each region from a light detection unit that receives reflected light from the recording surface in a plurality of regions. Generating means;
A phase difference signal generating means for generating a phase difference signal indicating a phase difference between the respective light detection signals based on the light detection signals output from the light detection means for each of the regions;
Error signal generation means for generating the error signal based on the generated push-pull signal and the generated phase difference signal;
An error signal generation device comprising: The error signal generation device according to claim 1,
The error signal generating means generates the error signal by performing either one of addition or subtraction of the generated push-pull signal and the generated phase difference signal. . The error signal generation device according to claim 2,
A polarity inverting means for inverting the polarity of either the generated push-pull signal or the generated phase difference signal;
The error signal generating device generates the error signal by performing either addition or subtraction of one signal with the polarity inverted and the other signal. In the error signal generation device according to claim 2 or 3,
An error signal generating apparatus, further comprising low-pass means for passing only a low-frequency component of the error signal generated by the addition or subtraction. The push-pull signal generating means, the phase difference signal generating means, and the error signal generating means are provided, and further, based on the generated error signal, for controlling the condensing means to be positioned at the reference position. An error signal generation device according to any one of claims 1 to 4, comprising control signal generation means for generating a control signal of
An optical pickup having the light source, the light collecting means, and the light detecting means, and further having a moving means for moving the light collecting means in the radial direction based on the generated control signal;
An information recording / reproducing apparatus comprising:

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