JP2008269719A - Focus servo control method and optical disk apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a focus servo control method capable of improving stability and reliability of a focus servo drawing-in operation, and to provide an optical disk device. <P>SOLUTION: A first focus error generation part 12 is first made valid, and focus search is carried out by an astigmatism operation. In this state, a controller 23 monitors a driving signal (focus driving signal) output from a drive amplifier 15 while a focus servo is kept OFF, detects and stores the level FD1 of a driving signal of timing of detecting a FZC signal, and sets a gate within the range of ±X volts with respect to the level FD1 of the driving signal. Then, the controller 23 validates a second focus error generation part 13, and carries out focus search by a differential astigmatism method. In this case, the FZC signal is detected only within the set gate range, and the focus servo is drawn in by the same focus servo drawing-in method as that of the conventional case. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a focus servo control method capable of avoiding an erroneous focus servo pull-in operation and an optical disc apparatus to which the focus servo control method is applied.

The astigmatism method, which is known as a method for generating a focus error signal, is often used in optical disk devices such as CDs and DVDs. However, when the astigmatism method is used for an optical disk having a large push-pull modulation such as a DVD-RAM, there is a problem that the push-pull leaks into the focus error signal and the focus servo becomes unstable.
As a means for solving such a problem, a method of generating a focus error signal by a differential astigmatism method is known. The differential astigmatism method is a method of generating a focus error signal by subtracting the focus error signal generated at the side spot multiplied by a predetermined coefficient from the focus error signal generated at the main spot, and push-pull leakage. It is characterized by the fact that it can be kept small.
However, since the differential astigmatism method uses a side spot in addition to the main spot, the light of the main spot enters the detector for detecting the side spot when the focus servo is pulled in, so that the original focus error signal is not obtained. Necessary noise occurred, and focus servo pull-in sometimes failed.

FIG. 6 is a signal waveform diagram showing a conventional focus servo pull-in method.
A conventional focus servo pull-in method will be described with reference to FIG. When pulling in the focus servo, first turn on the laser and raise / lower the objective lens. At that time, a focus error signal shown in FIG. 6A and a total light quantity signal shown in FIG. 6C are obtained. Each of these signals is input to a separate comparator and converted into a digital signal. The signals output from the respective comparators are the FZC signal shown in FIG. 6B and the total light quantity detection signal shown in FIG. 6D (indicating whether or not the total light quantity of the reflected light from the optical disk has exceeded the threshold value). Signal). In order to pull in the focus servo, a microcomputer, DSP or the like monitors the FZC signal and the total light quantity detection signal, and pulls in at a predetermined timing. Specifically, at the timing when the total light quantity detection signal is at “High” level and the FZC signal falls, the focus servo is pulled in as shown in FIG.
In the differential astigmatism method, unnecessary noise may occur in the original focus error signal. As an example, a case where reflection occurs on the disk surface will be described. If the surface reflection is large, the FZC threshold is exceeded, and focus servo is applied on the surface, and focus servo is not applied on the correct signal surface.
FIG. 7 is a signal waveform diagram of each part of the focus servo system when the surface reflection of the optical disk is large.
On the other hand, if the FZC threshold value is increased, this problem can be solved, but this time, the FZC signal cannot be detected on the signal surface and the focus servo is not applied.
FIG. 8 is a signal waveform diagram of each part of the focus servo system when the FZC threshold is increased.

As a solution to this problem, focus error signal based on the astigmatism method with less noise is used at the time of focus servo pull-in, and focus error signal based on the differential astigmatism method with small push-pull leakage after focus servo pull-in is used. An optical disc apparatus that switches to the focus servo used has been proposed.
FIG. 9 is a block diagram showing the configuration of this optical disc apparatus.
FIG. 10 is an explanatory view showing an optical system of a pickup in this optical disc apparatus light.
As shown in FIG. 9, the optical disc apparatus includes an optical pickup 210, a signal generation circuit 220, an ACT drive circuit 30, an LD drive circuit 240, a motor drive circuit 250, a spindle motor 260, and a control circuit 270.
The optical pickup 210 includes a semiconductor laser that emits blue / red / infrared laser light, an optical system that guides the laser light of each wavelength to an objective lens, and an objective lens actuator that drives the objective lens in a focus direction and a tracking direction. And a photodetector for receiving reflected light from the disk and outputting an electrical signal. The photodetector has a sensor pattern for generating various signals such as an RF signal, a focus error signal, and a tracking error signal.
The signal generation circuit 220 performs arithmetic processing on the electrical signal input from the photodetector in the optical pickup 210, generates various signals such as an RF signal, a focus error signal, and a tracking error signal, and outputs them to the control circuit 270. The ACT drive circuit 230 generates a drive signal based on the focus servo signal and tracking servo signal generated in the control circuit 270 and outputs them to the objective lens actuator in the optical pickup 210.

The LD drive circuit 240 drives the semiconductor laser in the optical pickup device 210 according to the control signal input from the control circuit 270, and emits one of the blue / red / infrared laser beams from the optical pickup 210. Let
The motor drive circuit 250 drives the disk drive spindle motor 260 in accordance with a control signal input from the control circuit 270 to rotate the disk at a predetermined speed.

The control circuit 270 processes the RF signal input from the signal generation circuit 220, generates reproduction data, and outputs it to the subsequent circuit. The focus error signal and tracking error signal input from the signal generation circuit 220 are processed to generate a focus servo signal and a tracking servo signal, which are output to the ACT drive circuit 230.
Also, the wobble signal and the synchronization signal input from the signal generation circuit 220 are processed to generate a motor servo signal and output it to the motor drive circuit 250. Further, a control signal for emitting a laser beam having a wavelength corresponding to the loaded disc is output to the LD drive circuit 240.

Further, as shown in the optical system of the optical pickup 210 in FIG. 10, after the infrared wavelength laser light emitted from the infrared LD 101 is made into three beams in the diffraction grating 102, the red laser system and the infrared laser system Passes through a divergent lens 103 that adjusts the optical magnification of the light beam, and part of the light is reflected by the beam splitter 106.
The red wavelength laser light emitted from the red LD 104 is returned to three beams by the diffraction grating 1-5, and a part of the laser light passes through the beam splitter 106. These laser beams are collimated by the collimator lens 107, reflected by the polarization beam splitter 108, transmitted through the Bs 112, and incident on the expander 113.

The blue wavelength laser light emitted from the blue LD 109 is made into three beams in the diffraction grating 110, further converted into parallel light by the collimator lens 111, and incident on the BS 112. Then, it is totally reflected by the BS 112 and enters the expander 113.
The laser light of infrared, red, and blue wavelengths incident on the expander 113 in this way is reflected by the mirror 114 after the beam diffusion state or wavefront state is adjusted here, and is reflected by the λ / 4 plate 115. After being converted to polarized light, it is focused on the disk by the objective lens 116.

  The laser light of each wavelength inverted from the disk is converted into linearly polarized light orthogonal to the polarization plane at the time of incidence of the disk by the λ / 4 plate 115 and then reverses the optical path at the time of incidence of the disk, and is transmitted through BS112 and BS108. , Enters the dichroic mirror 117. The infrared and red wavelength laser beams are reflected by the dichroic mirror 117 and focused on the photodetector 119 via the focusing lens 118. The blue wavelength laser light passes through the dichroic mirror 117 and is then focused on the photodetector 121 via the focusing lens 120.

  The focusing lenses 118 and 120 introduce astigmatism into the laser light of each wavelength. The photodetectors 119 and 121 receive the main beam (0th-order light) and sub-beams (± 1st-order light) of each wavelength divided into 3 beams by the diffraction gratings 102 and 110, respectively, by corresponding 4-divided sensors. To do.

  The signal generation circuit 220 performs arithmetic processing based on the signals from the photodetectors 119 and 121 to generate two types of focus error signals. Further, a SUM signal is generated by adding signals from the four-divided sensor that receives the main beam, and this is output to the controller 270 as a reproduction RF signal. Further, a tracking error signal is generated according to a predetermined method, and is output to the controller 270.

In this optical disk apparatus, the effect of stray light on the focus error signal is effectively applied to the optical disk having a plurality of recording layers in the stacking direction while performing focus servo using the focus error signal based on the differential astigmatism method. The focus error signal based on the astigmatism method is used at the time of focus servo pull-in, and after the servo pull-in is performed, the focus servo is switched to the focus servo using the focus error signal based on the differential astigmatism method.
As a result, the focus error signal based on the astigmatism method does not appear to be affected by stray light, and the focus servo can be pulled in smoothly. By switching to use, a stable servo operation is realized (see Patent Document 1).
JP 2006-309858 A

  Therefore, in the conventional optical disk apparatus, since the method of generating the focus error signal is switched after the focus servo is pulled, in other words, the focus servo method is switched. there were.

  The present invention has been made in view of such circumstances, and it is an object of the present invention to provide a focus servo control method and an optical disc apparatus that improve the stability of the focus servo pull-in operation and improve the reliability of the focus servo. To do.

  In order to achieve the above-described object, a focus servo control method according to the present invention controls the driving of a lens for condensing a light beam on an optical recording medium based on a focus error signal, so that the recording surface of the optical recording medium is In contrast, the focus servo control method servo-controls the light beam in a focused state, and performs a focus search based on the focus error signal output from the first focus error signal generation means, and determines the timing of focus servo pull-in. Detecting, measuring and storing a focus drive voltage corresponding to the detected focus servo pull-in timing, setting a focus drive voltage gate range centered on the focus drive voltage, and the first The focus error signal generation means is connected to the second focus error. Switching to the error signal generating means, and performing a focus search based on the focus error signal output from the second focus error signal generating means, and performing the focus servo pull-in using the set focus drive voltage gate range And a step.

  In order to achieve the above object, an optical disc apparatus according to the present invention includes an objective lens driving device that drives an objective lens that focuses a light beam on an optical recording medium, and driving of the objective lens by the objective lens driving device. A focus servo control circuit that controls based on a focus error signal generated from a light reception signal output from a photodetector that receives reflected light from the optical recording medium, and records and / or records on the optical recording medium An optical disk apparatus for performing reproduction, wherein the focus servo control circuit performs a focus search based on a focus error signal output from a first focus error signal generating means and detects a focus servo pull-in timing. And a focus corresponding to the focus servo pull-in timing detected by the detecting means. A focus drive voltage measuring means for measuring a casdrive voltage; a gate range setting means for setting a focus drive voltage gate range centered on the focus drive voltage measured by the focus drive voltage measuring means; and the first focus error signal. A switching means for switching the generating means to the second focus error signal generating means, and a focus search based on the focus error signal output from the second focus error signal generating means, and the focus set by the gate range setting means Servo pull-in means for performing focus servo pull-in using the drive voltage gate range is provided.

  According to the present invention, there is an effect that it is possible to provide a focus servo control method and an optical disc apparatus that improve the stability and reliability of the focus servo pull-in operation.

FIG. 1 is a block diagram showing a focus servo system of an optical disc apparatus to which a focus servo control method according to an embodiment of the present invention is applied.
The focus servo system performs control for just-focusing the laser beam on the recording surface of the optical disk (optical recording medium) 3 that is rotationally driven by the spindle motor 4. In this focus servo system, when the optical disk 3 rotates at a constant rotational speed, the recording surface of the optical disk 3 vibrates due to distortion or disturbance of the optical disk 3, so that the focus coil 2 moves the objective lens based on the drive signal. .
The objective lens transmits laser light from the laser 6 and irradiates the recording surface of the optical disc 3, and moves so that the laser light from the laser 6 is just focused on the recording surface of the optical disc 3 by the drive signal. To do.

This focus servo system includes a focus coil (objective lens driving device) 2, a PDIC (photodetector, servo pull-in means) 11, a first focus error generation unit (first focus error signal generation means) 12, a second Focus error generation unit (second focus error signal generation unit, servo pull-in unit) 13, phase compensation unit (servo pull-in unit) 14, drive amplifier (servo pull-in unit) 15, FZC generation unit 16, total light quantity signal generation unit 21 , Comparator 22, controller (detection means, focus drive voltage measurement means, gate range setting means, switching means, servo pull-in means) 23, gate signal generation unit (servo pull-in means) 24, switching circuits (switching means) 26, 27 It is the composition which includes.
The focus coil 2 moves the objective lens based on the drive signal.
The PDIC 11 forms an image of the laser beam irradiated from the laser 6 and reflected from the recording surface of the optical disc 3, and generates a light reception signal based on the imaging result.
The first focus error generator 12 is a circuit that generates and outputs a focus error signal based on the astigmatism method based on the received light signal.
The second focus error generator 13 is a circuit that generates and outputs a focus error signal based on the differential astigmatism method based on the received light signal.
The phase compensation unit 14 is a circuit that performs phase compensation processing on the focus error signal output from the first focus error generation unit 12 or the second focus error generation unit 13.
The drive amplifier 15 is a circuit that generates a drive signal and outputs it to the focus coil 2.
The FZC generation unit 16 generates and outputs a focus zero cross signal (hereinafter referred to as an FZC signal) based on the focus error signal output from the first focus error generation unit 12 or the second focus error generation unit 13. Circuit.
The total light amount signal generation unit 21 is a circuit that generates and outputs a total light amount signal (a signal indicating the light amount of reflected light from the optical disk 3) based on the output from the PDIC 11.
The comparator 22 compares the total light amount signal output from the total light amount signal generation unit 21 with a total light amount threshold value, and outputs a total light amount detection signal.
The controller 23 is a circuit that controls each unit.
The gate signal generation unit 24 detects the focus drive voltage FD1 at the falling timing of the FZC signal based on the total light amount detection signal output from the comparator 22 and the FZC signal output from the FZC generation unit 16. This is a circuit that stores and generates and outputs an FZC gate signal that becomes a “High” level within a range of FD1 ± X volts.
The switching circuits 26 and 27 are controlled by the controller 23 and enable one of the first focus error generation unit 12 and the second focus error generation unit 13.

FIG. 2 is an explanatory diagram showing a partial internal configuration of the optical head 14.
The laser beam output from the laser 6 is reflected by the beam splitter 34 via the lens 32 and the grating 33.
The reflected light is collected by the objective lens 35 and applied to the recording surface of the optical disc 3.
Reflected light from the optical disk 3 is supplied to the PDIC 11 via the objective lens 35, the beam splitter 34, the lens 36, and the cylindrical lens 37.

Here, the astigmatism method and the differential astigmatism method will be briefly described.
The laser light emitted from the laser is divided into three beams using a diffraction grating and is applied to the optical disk. Of the reflected light from this optical disc, the reflected light for the main beam (0th order light) is received by a four-divided sensor composed of sensors A, B, C and D, and reflected for two sub beams (± first order light). Light is received by a four-divided sensor composed of sensors E, F, G, and H and a four-divided sensor composed of sensors I, J, K, and L, respectively.
These three quadrant sensors are arranged with a predetermined interval.
Output signals from sensors A, B, C, D, E, F, G, H, I, J, K, L are a, b, c, d, e, f, g, h, i, j, k. , L, the focus error signal by the differential astigmatism method is obtained from the calculation result of (a + c) − (b + d) + k {(e + g + i + k) − (f + h + j + l)}. The focus error signal by the astigmatism method is obtained from the calculation result of (a + c) − (b + d).
When the focus error signal is generated by such a differential astigmatism method, the influence of the signal component from the groove is canceled by the addition of the signal by the sub beam, that is, the addition of k {(e + g + i + k) − (f + h + j + l)}.
As a result, the shift between the zero-cross position and the on-focus position of the focus error signal can be eliminated.

Next, the operation will be described.
FIG. 3 is a signal waveform diagram of each part of the focus servo system when the first focus error generation unit 12 of the optical disk apparatus according to the present embodiment is enabled.
FIG. 4 is a signal waveform diagram of each part of the focus servo system when the second focus error generator 13 is enabled.
FIG. 5 is a flowchart showing the operation of the controller 23 for controlling the focus servo system in the present embodiment.
As shown in the flowchart of FIG. 5, the controller 23 controls the switching circuits 26 and 27 and enables either the first focus error generation unit 12 or the second focus error generation unit 13 to The point aberration method and the differential astigmatism method can be switched arbitrarily.
Then, for example, in the state of the initial setting mode that is activated when the optical disc apparatus is turned on or when the optical disc is loaded (step S1), the first focus error generator 12 is first activated (step S2), and astigmatism is achieved. A focus search is performed by the operation (step S3).
In this state, the drive signal (focus drive signal) output from the drive amplifier 15 is monitored while the focus servo is off, and the drive signal level FD1 at the timing when the FZC signal is detected is detected and stored (step S4). ), A gate is provided in the range of ± X volts with respect to the level FD1 of the drive signal (step S5).
When the normal mode for recording or reproduction after the completion of the initial setting mode is entered (step S6), the controller 23 controls the switching circuits 26 and 27 to enable the second focus error generator 13 (step S7). The focus search is performed by the differential astigmatism method.
In this case, the FZC signal is detected only within the gate, and the focus servo is pulled in by the same focus servo pull-in method as in the prior art (step S8).

(Initial setting mode)
For example, in a state of an initial setting mode that is activated when the optical disk apparatus is turned on or when an optical disk is loaded, the controller 23 controls the switching circuits 26 and 27 so that the first focus error generation unit 12 is enabled. Take control.
As a result, the first focus error generator 12 generates and outputs a focus error signal based on the astigmatism method shown in FIG. 3A based on the output of the PDIC 11.
The focus error signal based on this astigmatism method is compared with the FZC threshold value in the FZC generator 16 to generate the FZC signal shown in FIG. The FZC signal is output to the controller 23 and the gate signal generator 24.
On the other hand, the total light amount signal generation unit 21 generates a total light amount signal shown in FIG. 3C based on the output of the PDIC 11.
The total light amount signal generated by the total light amount signal generation unit 21 is compared with the total light amount threshold value by the comparator 22 to generate a total light amount detection signal shown in FIG. 3D and output to the controller 23 and the gate signal generation unit 24. Is done.

In this initial setting mode, the controller 23 monitors the drive signal output from the drive amplifier 15.
In this state, the focus error signal exceeds the FZC threshold in the signal surface reflection portion of the focus error signal shown in FIG. Therefore, as shown in FIG. 3B, the FZC signal becomes “High” level.
On the other hand, as shown in FIG. 3C, the total light amount signal generated by the total light amount signal generation unit 21 exceeds the total light amount threshold at the surface reflection portion and the signal surface reflection portion of the focus error signal.
For this reason, as shown in FIG. 3D, the total light quantity detection signal becomes “High” level in the surface reflection portion and the signal surface reflection portion of the focus error signal.
Since the controller 23 monitors the drive signal output from the drive amplifier 15, it determines the falling timing of the FZC signal shown in FIG. 3B from the “High” level to the “Low” level. The drive signal level FD1 is detected, and the ± X volt range centered on FD1 and the FD1 ± X volt range are determined and stored, and the gate signal that enables only the FZC signal in this range is the gate signal. A gate function to be output to the generation unit 24 is set.
In this initial setting mode, the focus servo remains off as shown in FIG.

(Normal mode)
Next, when in the normal mode state in which recording or reproduction is performed after the completion of the initial setting mode, the controller 23 controls the switching circuits 26 and 27 to enable the second focus error generation unit 13.
When the second focus error generation unit 13 is enabled, a focus search is performed by the conventional differential astigmatism method as shown in FIG. 6, and the focus servo is pulled in by the same focus servo pull-in method.
In this normal mode, the gate signal generation unit 24 generates the FZC gate signal shown in FIG. 4G by the gate function that validates the FZC signal in the range of FD1 ± X volts set in the initial setting mode. .
Then, the falling timing of the FZC signal during the period when the total light quantity detection signal obtained from the focus error signal due to the signal surface reflection of the optical disc 3 is at “High” level becomes effective. Further, the fall timing of the FZC signal is invalid during the period when the total light quantity detection signal obtained from the focus error signal due to the surface reflection of the optical disc 3 is at “High” level.
As shown in FIGS. 4E, 4F, and 4G, the controller 23 is in a period in which the FZC gate signal is being output, and the total light amount detection signal becomes active ("High" level). The falling timing of the FZC signal generated within a given period is made effective, the focus is turned on at this timing, the focus search is performed by the differential astigmatism method, and the focus servo is pulled in.

  As a result, even when using a focus error signal generation method that is prone to noise, such as the differential astigmatism method, the focus servo pull-in operation based on erroneous information such as surface reflection can be avoided, and the signal recording surface can be accurately Can be detected and the focus servo can be pulled in.

1 is a block diagram showing a focus servo system of an optical disc apparatus to which a focus servo control method according to an embodiment of the present invention is applied. FIG. It is explanatory drawing which shows the partial internal structure of the optical head of the optical disk apparatus in embodiment of this invention. It is a signal waveform diagram of each part of the focus servo system when the first focus error generation part of the optical disc apparatus in the embodiment of the present invention is enabled. It is a signal waveform diagram of each part of the focus servo system when the second focus error generating part of the optical disc apparatus in the embodiment of the present invention is enabled. 5 is a flowchart showing an operation of a controller that controls a focus servo system of the optical disc apparatus according to the embodiment of the present invention. It is a signal waveform diagram showing a conventional focus servo pull-in method. It is a signal waveform diagram of each part of the focus servo system when the surface reflection of the optical disc in the conventional optical disc apparatus is large. It is a signal waveform diagram of each part of the focus servo system when the FZC threshold value is increased in the conventional optical disc apparatus. It is a block diagram which shows the structure of the conventional optical disk apparatus. It is explanatory drawing which shows the optical system of the pick-up in the conventional optical disk apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 3 ... Optical disk (optical recording medium), 2 ... Focus coil (objective lens drive device), 11 ... PDIC (photodetector, servo pull-in means), 12 ... 1st focus error production | generation part (1st (Focus error signal generating means), 13... Second focus error generating section (second focus error signal generating means, servo pull-in means), 14... Phase compensation section (servo pull-in means), 15. Servo pulling means), 23... Controller (detection means, focus drive voltage measuring means, gate range setting means, switching means, servo pulling means), 24... Gate signal generator (servo pulling means), 26, 27. Switching circuit (switching means), 35... Objective lens.

Claims (8)

This is a focus servo control method in which the driving of a lens for condensing a light beam on an optical recording medium is controlled based on a focus error signal, and the light beam is servo-controlled with respect to the recording surface of the optical recording medium. And
Performing a focus search based on the focus error signal output by the first focus error signal generating means and detecting a focus servo pull-in timing;
Measuring and storing a focus drive voltage corresponding to the detected focus servo pull-in timing;
Setting a focus drive voltage gate range centered on the focus drive voltage;
Switching the first focus error signal generating means to a second focus error signal generating means;
Performing a focus search based on a focus error signal output by the second focus error signal generating means, and performing focus servo pull-in using the set focus drive voltage gate range;
A focus servo control method comprising:   2. The focus servo control method according to claim 1, wherein the focus drive voltage gate range indicates a focus drive voltage range that invalidates a false focus pull-in timing due to reflection on the surface of the optical recording medium.   The first focus error signal generation means outputs a focus error signal by the astigmatism method, and the second focus error signal generation means outputs a focus error signal by the differential astigmatism method. The focus servo control method according to claim 1.   The step of detecting the timing of the focus servo pull-in includes: a focus zero cross signal generated based on a focus error signal by the astigmatism method output by the first focus error signal generation means; and an optical recording medium The step of performing a focus search using a total light amount detection signal indicating the amount of reflected light of the light, detecting a focus servo pull-in timing, and performing a focus servo pull-in using the focus drive voltage gate range includes the steps of: A focus zero cross signal generated based on the focus error signal by the differential astigmatism method output by the focus error signal generating means of No. 2, and a total light amount detection signal indicating the amount of reflected light from the optical recording medium; Based on the set focus drive voltage gate range Focus servo control method according to claim 1, wherein the performing focus pull servo disable pull false focus by reflection of the optical recording medium surface. An objective lens driving device that drives an objective lens that condenses the light beam onto the optical recording medium, and an optical detector that receives the reflected light from the optical recording medium outputs the driving of the objective lens by the objective lens driving device. A focus servo control circuit that controls based on a focus error signal generated from the received light signal, and performs recording and / or reproduction on the optical recording medium,
The focus servo control circuit
Detecting means for performing a focus search based on the focus error signal output from the first focus error signal generating means and detecting the timing of focus servo pull-in;
A focus drive voltage measuring means for measuring a focus drive voltage corresponding to a focus servo pull-in timing detected by the detecting means;
Gate range setting means for setting a focus drive voltage gate range centered on the focus drive voltage measured by the focus drive voltage measuring means;
Switching means for switching the first focus error signal generating means to the second focus error signal generating means;
Servo pull-in means for performing a focus search based on the focus error signal output from the second focus error signal generating means and performing focus servo pull-in using the focus drive voltage gate range set by the gate range setting means; ,
An optical disc apparatus comprising:   6. The optical disc apparatus according to claim 5, wherein the focus drive voltage gate range indicates a focus drive voltage range that invalidates a false focus pull-in timing due to reflection on the surface of the optical recording medium.   The first focus error signal generating means of the focus servo control circuit outputs a focus error signal by the astigmatism method, and the second focus error signal generating means is a focus error signal by the differential astigmatism method. 6. The optical disc apparatus according to claim 5, wherein:   The detection means of the focus servo control circuit includes a focus zero cross signal generated based on a focus error signal by the astigmatism method output from the first focus error signal generation means, and a signal from the optical recording medium. A focus search is performed using a total light amount detection signal indicating the amount of reflected light to detect a focus servo pull-in timing, and the servo pull-in means outputs a differential non-output signal output from the second focus error signal generating means. A focus zero cross signal generated based on a focus error signal by the point aberration method, a total light amount detection signal indicating the amount of reflected light from the optical recording medium, and a focus drive voltage gate set by the gate range setting means Based on the range, the false focus pull-in Optical disk apparatus according to claim 5, wherein the performing focus pull servo Disable timing.

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