JP2000155961A - Focus-position adjusting device and optical disk drive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a focus-position adjusting device by which a good recording and reproducing characteristic can be obtained both in a land track and a group track. SOLUTION: On the basis of an L/G changeover signal LGS from a land group detection part 34, a focus-position coarse probing part 50 and a focus- position precise probing part 60 discriminate whether a light beam spot is situated in a land track or a group track, and it probes two new focus positions (for a land and for a group) which improve the envelope and the jitter of a bit error rate BER and a reproducing signal RF which are measured by an error-rate measuring part 33. Two control signals FBAL, FOFF which are used to change a control target to the new focus positions are output to a focus-error detection part 36.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a focus position adjusting device for adjusting a focus position of an optical disk on which recording and reproduction can be performed, and an optical disk drive device.

[0002]

2. Description of the Related Art With the spread of multimedia technology in recent years, optical disk drive devices have been widely used as large-capacity auxiliary storage devices in personal computers and audiovisual systems. The optical disk drive device uses an optical disk such as a compact disk (CD) or a digital video disk (DVD) as a recording medium, and reproduces information such as computer data and video / audio data recorded on the optical disk, and reproduces such information. Or recording on an optical disc.

In such an optical disk drive device, focus servo and tracking servo have been conventionally performed in order to correctly record and reproduce information. Here, the focus servo is to control the light beam irradiated on the optical disk to always be in a predetermined convergence state, and indicates a deviation of the position of the light beam with respect to the optical disk (hereinafter, referred to as “focus position”). This is performed based on a focus error signal (a signal generated from light reflected from a light beam spot on an optical disk). The tracking servo is control for causing a light beam to follow a spirally formed track on an optical disk.

An optical disk mounted on an optical disk drive is rotated by a spindle motor, and is irradiated with a light beam when a predetermined number of rotations is reached. Then, while the focus servo and the tracking servo are operating, reproduction of information recorded on the optical disk and recording of information on the optical disk are performed.

[0005]

However, the conventional optical disk drive for performing such focus servo and tracking servo has the following problems. First, a conventional optical disk drive device uses a single spiral land / groove format (SS-L / GFM).
Since the focus servo is performed on the optical disc T) without distinguishing between the groove track (the groove portion of the guide groove of the spirally formed track) and the land track (the portion between the grooves), particularly high density However, there is a problem that the focus servo cannot be said to be performed with sufficiently high accuracy on the optical disk. Here, SS-
In the L / GFMT optical disk, a recordable / reproducible groove track and a land track are alternately formed for each rotation of the optical disk, and the land track and the groove track are continuously recorded / recorded from the inner circumference to the outer circumference. This is an optical disk having a structure that can be reproduced.

In this type of optical disk, when the reflected light from the optical disk is diffracted by passing through the objective lens, it is affected by aberrations and the like at the objective lens, and the distribution of the diffracted light is distributed between the land track and the groove track. different. As a result, the relationship between the zero level of the focus error signal (control target position for the focus position) and the focus position differs between the land track and the groove track. That is, conventionally, in the focus servo, the focus position is controlled so as to converge to the same control target position. However, different focus positions are obtained in the land track and the groove track, and either the land track or the groove track is obtained. On the other hand, even if the focus position is adjusted so that the reproduction (including recording on a recordable optical disc) is optimized, on the other hand, the optimum reproduction (including recording on a recording optical disc) state cannot be obtained.

Further, a conventional optical disk drive device is
Since it is not considered that the zero level of the focus error signal is not always the optimal focus position,
There is a problem that a reproduction error is large. That is, the control target position corresponding to the zero level of the focus error signal, the focus position where the amplitude of the reproduction signal detected by the optical head is optimal (maximum), or the focus position where the jitter of the reproduction signal is optimal (minimum) ( This may not always coincide with the “optimal focus position”). In such a case, even if the focus servo is performed on the basis of the control target position, the reproduction error increases because the amplitude of the obtained reproduction signal is small or the reproduction jitter is large. Therefore, sufficient recording / reproducing performance is not secured.

Further, in the case of an SS-L / GFMT optical disk, even if the focus position is adjusted so that the amplitude of the reproduction signal is maximum or the reproduction jitter is minimum, the amplitude of the reproduction signal is different between the address area and the data area. Also, there is a problem that an error occurs in the adjustment of the focus position due to the difference in the magnitude of the reproduction jitter.
In an SS-L / GFMT optical disk, an address area in which a track number and a sector number for identifying the sector are recorded in advance in uneven pits is provided between the sectors in which data is recorded. Pits are formed in the address area in a manner different from that of the data area. For this purpose, a conventional method of adjusting the focus position by using the amplitude of the reproduction signal or the magnitude of the reproduction jitter as focus position information (information indicating the current focus position, that is, information indicating the state of deviation of the position of the light beam with respect to the optical disk). In this case, an adjustment error occurs because the value indicated by the focus position information differs between the data area and the address area.

While the optical disk is rotating, the optical disk is subject to surface vibration at a constant frequency. If the surface vibration is largely displaced, an error occurs in the focus position information due to the influence. As a result, there is a problem that the adjustment of the focus position with high accuracy is hindered. Further, in the SS-L / GFMT optical disk, (1) when the focus position is greatly deviated from the optimum focus position, acquisition of address information itself, which is a precondition for adjusting the focus position, is performed normally. (2) The data area of the optical disc is unrecorded at the time of shipment, but in the case of an unrecorded optical disc, focus position information cannot be obtained from the data area in the first place. (3) Therefore, a test pattern is previously recorded on the unrecorded optical disc. It is conceivable that even if an attempt is made to record, if the focus position is greatly deviated from the optimum focus position, the recording can no longer be performed normally.
For this reason, if the focus position has shifted so much that reading of the address information becomes impossible, S
The SL / GFMT optical disk has a problem that it is no longer possible to search for the optimum focus position.

In the case of an SS-L / GFMT optical disk, if the data area is unrecorded, even if an attempt is made to record a temporary test pattern on the optical disk in advance, the write-protected optical disk no longer employs this method. There is a problem that can not be. Furthermore, SS-
In the L / GFMT optical disk, even when the recording / reproducing operation is normally performed, the characteristics of the optical head change due to the influence of the environmental temperature, and the zero level of the focus error signal detected by the optical head, that is, The control target position of the focus servo may change depending on the temperature. As a result, even when the optimum focus position is searched at the start of the optical disk drive and the recording / reproducing operation is normally performed, the recording / reproducing is performed due to a change in characteristics of the optical head or the like or a change over time. If the error rate at the time exceeds the allowable value or the light beam power at the time of recording reaches the upper limit, it is no longer possible to start searching for the focus position. is there.

SUMMARY OF THE INVENTION In view of the above problems, it is a first object of the present invention to provide a focus position adjusting device and an optical disk drive capable of obtaining good recording / reproducing characteristics for both a land track and a groove track. I do. Further, a second object of the present invention is to adjust the focus position with high accuracy in consideration of the deviation even when the zero level of the focus error signal is not always the optimum focus position for recording / reproduction. It is to provide a device or the like. More specifically, it is possible to avoid a problem that a reproduction error occurs due to a loss of either the amplitude or the jitter of the reproduction signal.

Further, a third object of the present invention is to prevent the focus position information from being disturbed due to such an address area even for an optical disk having an address area in which pits are formed in a manner different from the data area. An object of the present invention is to provide a focus position adjustment device or the like that performs highly accurate focus position adjustment. A fourth object of the present invention is to provide a focus position adjusting device or the like for performing a focus position adjustment in which an adjustment error due to a surface shake of an optical disk hardly occurs.

A fifth object of the present invention is to provide a focus position adjusting device and the like which can execute a search for a focus position again even if the focus position is displaced so large that address information cannot be read. It is to provide. Further, a sixth object of the present invention is to provide a focus position adjusting device and the like which can execute an optimum focus position search even for an unrecorded and write-protected optical disk. It is.

A seventh object of the present invention is that an error rate at the time of recording / reproduction exceeds an allowable range or a light beam power at the time of recording reaches an upper limit value due to a change in a temperature characteristic or the like of an optical element. It is an object of the present invention to provide a focus position adjusting device or the like that can start searching for an optimum focus position again even when the focus position is changed.

[0015]

In order to achieve the first object, the present invention provides a focus position adjusting apparatus for an optical disk having tracks of first and second shapes, and such a focus position adjusting apparatus. An optical disk drive device having a device, wherein a focus error detecting unit that detects a convergence state of the light beam applied to the optical disk, and outputs a focus error signal indicating the convergence state, based on the focus error signal, Focus control means for changing a focus position of the light beam so that the convergence state becomes a predetermined state; and a reproduction state detection for detecting a reproduction state of the optical disk based on a reproduction signal when reading information recorded on the optical disk. Means and a light beam spot on the first and second optical discs.
Track detecting means for detecting which of the tracks is located, and outputting a track identification signal indicating the track, and a focus position search for changing the focus position of the light beam so that the reproduction state becomes better. Means for determining a first update focus position at which the reproduction state becomes better based on the reproduction state when the track identification signal indicates a track having a first shape. A focus position updating unit that determines a second updated focus position at which the reproduction state becomes better based on the reproduction state when the track identification signal indicates a track having a second shape; When the signal indicates a track of the first shape, the focus position becomes the first update focus position. Changing the focus error signal so that when the track identification signal indicates a track of a second shape, the focus error signal is changed so that the focus position becomes the second updated focus position. And a focus control unit that changes a focus position of the light beam based on a focus error signal changed by the focus error signal changing unit.

Further, in order to achieve the second object, the present invention relates to the focus position adjusting device and the like, wherein the reproduction state detecting means considers the focus error signal in addition to the reproduction signal. To detect the reproduction state.
The playback state detection means has an envelope detection unit that detects an envelope of the playback signal, and a jitter detection unit that detects jitter of the playback signal, and detects the detected envelope, jitter, and the focus error signal. The reproduction state is detected based on the reproduction state.

According to another aspect of the present invention, there is provided a focus position adjusting device for detecting whether a light beam spot is located in a data area or an address area of an optical disk. The reproduction state detection means extracts a part of the reproduction signal based on the detection by the area detection means, and detects the reproduction state from the extracted reproduction signal. Then, the reproduction state detection means detects the reproduction state only for a reproduction signal when the area detection means detects that the light beam spot is located in the data area.

In order to achieve the fourth object, the present invention relates to the focus position adjusting device and the like, further comprising: a surface wobble for removing a frequency component indicating a surface wobble of the optical disc from the focus error signal. The reproduction state detection means includes a component removal filter, and detects the reproduction state from the focus error signal from which the frequency component has been removed and the reproduction signal. Further, the focus position adjusting device further includes a sector specifying unit for specifying a sector at a position where the surface deflection acceleration of the optical disk is reduced, and the reproduction state detecting unit includes the reproduction signal obtained only from the specified sector. And the reproduction state is detected from the focus error signal.

In order to achieve the fifth object, the present invention relates to the focus position adjusting device and the like, wherein the focus position updating unit performs the reproduction when the focus position is shifted by a predetermined moving amount. The first updated focus position and the second updated focus position are determined by determining whether or not the state becomes better. Further, in order to achieve the sixth object, the present invention provides the above-mentioned focus position adjusting device and the like, wherein the test data is further stored in a test area provided in at least one of a lead-in area and a lead-out area of the optical disc. And a reproducing state detecting means for detecting the reproducing state based on a reproducing signal when the test data is read.

In order to achieve the seventh object, the present invention relates to the focus position adjusting device and the like, further comprising the step of judging whether or not the reproducing state is a defective state exceeding a predetermined allowable range. Defective state determining means for performing, when it is determined to be in the defective state, causing the focus position updating section to determine new first and second updated focus positions; Re-exploration means for changing the signal.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an optical disk drive 100 according to the present invention will be specifically described with reference to the drawings. [Entire Configuration of Optical Disk Drive Device 100] FIG.
FIG. 2 is a block diagram showing the overall configuration of the optical disc drive device 100. The optical disk drive device 100 is roughly divided into mechanisms and optical system components 1 to 13, a signal processing unit 40, an optical head control unit 20, and a drive controller 1.
4

The mechanism and optical system components are an optical disk 1, an optical head 7 (actuator 2, objective lens 3, reproduced signal detector 4, photo detector 5, leaf spring 6, optical head 7, semiconductor laser 8), optical head It comprises a support member 9, a coarse motor 10, a seek control unit 11, a spindle motor 12, and a rotation control unit 13. The signal processing unit 40 is a circuit that processes a write signal to the optical disc 1 and a read signal from the optical disc 1, and includes a laser power drive unit 41, a modulation unit 42,
It comprises an addition amplifier 43, an addition amplifier 44, a difference amplifier 45, an addition amplifier 46, and a demodulation unit 47.

The optical head control section 20 is a circuit for controlling the tracking servo and the focus servo of the optical head 7 using various control signals from the signal processing section 40. It comprises a control unit 23, an addition unit 24, a disturbance signal generation unit 25, a focus control unit 26, and a focus position adjustment unit 30.

The optical disk 1 is a rewritable information recording medium and is mounted on a spindle motor 12. The rotation control unit 13 drives and controls the spindle motor 12 under the control of the drive controller 14. The optical head support member 9 is a member that supports the optical head 7, and is slid in the radial direction of the optical disk 1 by the coarse movement motor 10. The seek control unit 11 includes a drive controller 14
The seek operation of the optical head 7 is controlled by controlling the drive of the coarse movement motor 10 under the control of.

The modulation section 42 includes a drive controller 14
A certain conversion is performed on the signal pattern sent from the controller, and the obtained signal is output to the laser power driver 41 later. The laser power driver 41 modulates the output power of the semiconductor laser 8 based on the signal from the modulator 42.
As a result, a signal pattern from the drive controller 14 is recorded on the optical disc 1.

The optical head 7 is a set of a support member 6 such as a semiconductor laser 8, an objective lens 3, a photodetector 5, a reproduced signal detector 4, an actuator 2, and a leaf spring. The light beam emitted from the semiconductor laser 8 passes through the optical system in the optical head 7, is condensed by the objective lens 3, and is irradiated on the optical disc 1. The light beam reflected by the optical disk 1 passes through the objective lens 3 and the optical system in the optical head 7, and then enters the photodetector 5, the reproduction signal detector 4, and the like.

The photodetector 5 is a four-division photodiode that indicates the focus position of the light beam irradiated on the optical disk. Each of the summing amplifiers 43 and 44 includes a photodetector 5
The focus signals VFS1 and VFS2 are output by adding and amplifying two of the four light signals from the optical signals.
These focus signals VFS1 and VFS2 are used to generate a focus error signal FES indicating a deviation of the light beam from a predetermined convergence state. That is, here, a focus error detection method based on the astigmatism method is adopted.

The reproduction signal detector 4 is a broadband two-segment photodiode that detects the amount of reflected light from the optical disk 1 and outputs two reflected light amount signals. Since information (signal pattern) is recorded on the optical disc 1 with a change in reflectance, the information recorded on the optical disc 1 can be read by these two reflected light amount signals. Difference amplifier 4
5 calculates the difference between the two reflected light amount signals from the reproduction signal detector 4 and outputs the difference to the tracking control unit 23 and the focus position adjustment unit 30 as a broadband tracking error signal RFTE. This wideband tracking error signal R
The FTE is a signal including a reproduction signal (hereinafter, referred to as an “address signal”) of an address portion formed of concave and convex pits on the optical disc 1. The address pits formed on the optical disc 1 are formed at positions shifted by 1/4 track pitch from the center of the groove track and the center of the land track, respectively. It is used for detecting an address area of the optical disk 1, detecting land tracks and groove tracks, and performing tracking servo.

The addition amplifier 46 adds the two light quantity signals from the reproduction signal detector 4 and outputs the result to the demodulation section 47 as a reproduction signal RF. This reproduction signal RF is a wideband signal indicating all information recorded on the optical disc 1. The demodulation unit 47 binarizes the reproduction signal RF from the addition amplifier 46 with a predetermined threshold value and performs an inverse conversion corresponding to the conversion in the modulation unit 42, thereby indicating information recorded on the optical disc 1. An RF pulse signal PRF is generated and sent to the focus position adjustment unit 30 and the drive controller 14.

The basic function of the focus position adjusting section 30 is to generate a focus error signal FES from the two focus signals VFS1 and VFS2. At this time, it is necessary to use various control signals RFTE, RF and PRF. Depending on the position of the light beam spot (optical disc 1
Search for the optimum focus position depending on which of the land track and the groove track is located), and the result is reflected in the focus error signal FES. Also, based on the broadband tracking error signal RFTE, a land (L) / groove (G) switching signal LGS indicating whether the current light beam spot is located on a land track or a groove track, and the light beam spot having an address. A gate signal IDGATE indicating the timing of the position in the region is generated.

The focus position search by the focus position adjustment unit 30 can be roughly divided into two types of modes, namely, a rough search performed after the optical disk 1 reaches a certain number of rotations, and a rough search performed after the rough search. There is a precision exploration conducted immediately after. And in precision exploration,
It is possible to operate two functions (optional functions) for further improving the accuracy, that is, a function of excluding a surface runout component from the focus error signal FES or a function of searching only a specific data area. These two search modes and two optional functions are selected or added under the control of the drive controller 14.

The focus driving unit 21 and the tracking driving unit 22 supply a driving current for changing the position of the objective lens 3 to the actuator 2 based on signals from the adding unit 24 and the tracking control unit 23, respectively. The actuator 2 is composed of a magnet, a coil, or the like, and moves the objective lens 3 against the reaction force of the leaf spring 6 to converge the light beam applied to the optical disk 1 (the light beam and the surface of the optical disk 1 are not converged). Relative displacement), and displacement of the light beam spot from the track)
To change.

The tracking control section 23 is a circuit for performing control for tracking servo.
5, the feedback control is performed so that the light beam follows the track on the optical disk 1 based on the wideband tracking error signal RFTE from the optical disk 1. Further, the tracking control unit 23 receives L from the focus position adjustment unit 30 according to an instruction from the drive controller 14.
Based on the / G switching signal LGS, the control is such that the light beam always follows only the land track or the groove track, that is, the light beam jumps back to the inner peripheral side of the optical disc 1 every time the optical disc 1 rotates (still jump). )
The control for making it occur is also performed.

The focus control unit 26 comprises a loop filter for phase compensation and the like.
Based on the focus error signal FES from 0, a signal is generated to make the error between the focus position indicated by the signal FES and the control target position of the focus servo zero, and the signal is output to the adder 24. Note that, based on the gate signal IDGATE sent from the focus position adjustment unit 30, the focus control unit 26 and the tracking control unit 23 operate only for the time during which the light beam converged and irradiated on the optical disc 1 is located in the address area. The output signal immediately before entering the area is held. This is because, as described above, the address pits formed on the optical disc 1 are formed at positions shifted by 1/4 track pitch from the center of the groove track and the center of the land track, respectively. This is because unnecessary areas are excluded from the focus servo and tracking servo targets.

The disturbance signal generator 25 is a signal necessary for the focus position adjuster 30 to perform a precise search for the focus position, specifically, a 1 kHz sine wave signal that changes the focus position by ± 0.4 μm. And the like to the adder 24. The adder 24 adds the signal from the focus controller 26 and the signal from the disturbance signal generator 25 under the control of the drive controller 14 (instruction of coarse search or fine search) to add the focus drive 21 Output to
Alternatively, it passes the signal from the focus control unit 26 as it is and outputs it to the focus drive unit 21.

The drive controller 14 includes a microprocessor, a ROM storing a control program, a RAM as a work area, and the like. The drive controller 14 controls the rotation controller 13, the seek controller 11, the signal processor 40, and the optical head controller 20. Control. For example, when a certain condition is detected, various conditions for a specific type of focus position search are set to the focus position adjustment unit 30 and the like, and the search is executed.

FIGS. 2A and 2B show the optical disk 1.
FIG. 2A is a schematic view of the optical disc 1 as viewed from above, and FIG.
It is an enlarged view near a switching point. This optical disc 1 is SS
-An L / GFMT optical disc. That is, both the groove (G) and the land (L) of the track formed in a spiral shape can be recorded and reproduced.
The lands and the grooves are formed alternately for each round of the above. As a result, the land and the groove can be continuously used for reproduction or recording from the inner periphery to the outer periphery.

As shown in FIG. 2A, in this optical disc 1, a land track (indicated by a white line in the figure) and a groove track (indicated by a black solid line in the figure) are connected for each rotation. Constitutes a spiral. FIG.
As shown in (b), the optical disc 1 has an address area having a concave and convex pit structure for identifying a sector between data areas. Also,
The L / G switching point exists for each round of the optical disk, and is configured so that lands and grooves are switched just in the address area. There are 17 address areas per circumference on the inner circumference side of the optical disc 1, one of which is L
/ G switching point. Then, one set of the address area and the data area constitutes a data sector. Therefore,
For example, one round (= 1 track) on the inner circumference side of the disk is divided into 17 sectors.

As shown in FIG. 2 (b), the address area of the optical disk 1 has pits complementarily arranged at the beginning of a sector at a position shifted by 1/2 track pitch from the track center in the radial direction of the optical disk 1. (Hereinafter "CAPA
(Complementary AllocatedPit Address). " )
It is composed of More specifically, at the end of the data area other than the first data sector including the L / G switching point,
1 / to the outer circumference of the optical disc 1 with respect to the groove track
The first address is arranged at a position shifted by two track pitches, and the second address is arranged at a position shifted by 1/2 track pitch inward after the first address.
On the other hand, in the first data sector including the L / G switching point, at the end of the data section located before the first data sector, the track is shifted by 1/2 track pitch toward the inner circumference of the optical disc 1 with respect to the groove track. A first address is arranged at a position, and after the first address, 1 /
The second address is arranged at a position shifted by two track pitches.

FIG. 2C is a cross-sectional view of the optical disc 1 and the objective lens 3 when a light beam is irradiated on the land of the optical disc 1 of SS-L / GFMT.
(D) is a cross-sectional view of the optical disc 1 and the objective lens 3 when a light beam is applied to a groove of the SS-L / GFMT optical disc 1. These figures 2
(C) As can be seen from D, since the land and the groove of the optical disc 1 have different shapes, when the reflected light from the optical disc 1 passes through the objective lens 3 and is diffracted by the optical head 7, the distribution of the diffracted light is obtained. Is different between land tracks and groove tracks. As a result, the relationship between the zero level of the focus error signal (control target position for the focus position) and the actual focus position differs between the land track and the groove track. For this purpose, the optical disc drive device 100 performs different focus position adjustments depending on whether the light beam is located on a land track or a groove track. That is, the control target position when the light beam is located on the land track and the control target position when it is located on the groove track are independent. [Structure of Focus Position Adjusting Unit 30] FIG. 3 is a block diagram showing a detailed structure of focus position adjusting unit 30 shown in FIG. The focus position adjustment unit 30 is roughly divided into components for searching for a coarse focus position (error rate measurement unit 33, focus position coarse detection unit 50) and components for a precision search (read gate detection unit). 32, surface runout component removing unit 35, switch 39, focus position precise search unit 60) and constituent elements common to them (address signal detecting unit 31, land / groove detecting unit 34, two switches 37, 38, focus And an error detector 36).

The land / groove detector 34 determines whether the current position of the light beam spot is on the groove or on the land based on the broadband tracking error signal RFTE output from the difference amplifier 45 of the signal processor 40. LGS switching signal LGS is generated. Specifically, the land / groove detection unit 34 binarizes a signal obtained by binarizing the peak envelope of the wideband tracking error signal RFTE (hereinafter, referred to as a “peak envelope signal PEPS”) and a bottom envelope of the wideband tracking error signal RFTE. (Hereinafter referred to as "bottom envelope signal BEPS"), and when the light beam follows the track on the optical disc 1 and passes through the address area, the bottom envelope signal changes after the logical level of the peak envelope signal PEPS changes. BEPS
Is determined to be a groove when the logical level of the bottom envelope signal BEPS changes, and conversely, a land is determined when the peak envelope signal PEPS changes after the logical level of the bottom envelope signal BEPS changes. Output as This L / G switching signal LG
S is used for distinguishing a land from a groove in the search of a focus position.
3 to make a still jump.

FIGS. 4A to 4C are diagrams showing the timing of the input / output signals RFTE and LGS of the land / groove detector 34. FIG. FIG. 4A shows an outline of a track configuration on the optical disc 1 and a trajectory of a light beam spot moving from a groove track to a land track through an L / G switching point, and FIG. FIG.
FIG. 4A shows the waveform of the broadband tracking error signal RFTE when the track follows the locus shown in FIG. 4A, and FIG. 4C shows the waveform of the L / G switching signal LGS.

As shown in FIG. 4A, the address area of the optical disc 1 is a pit (CAPA) that is complementarily arranged at a position shifted from the track center by 1/2 track pitch in the radial direction of the optical disc 1 at the head of the sector. It is composed of By forming such a CAPA, the address information formed by the pits can be reproduced by the broadband tracking error signal RFTE when the light beam passes through the address area.

Now, it is assumed that the light beam spot passes through the address area shown in FIG. 4A while following the groove track. Then, as shown on the left side of the timing chart of FIG. 4B, the wideband tracking error signal RFTE has a waveform in which an address signal first appears on the positive side and then appears on the negative side with respect to the zero level. .
Subsequently, when the light beam spot passes through the L / G switching point, as shown on the right side of the timing chart of FIG. 4B, the broadband tracking error signal RFTE first becomes negative with respect to the zero level. Appears, and then the waveform appears on the positive side. Since the land / groove detection unit 34 detects the L / G switching point from the polarity inversion order as shown in FIG. 4B, the L / G switching signal LGS (optical signal) as shown in FIG. When the beam spot is located in the groove, the signal becomes “Hi” level, and when the beam spot is located in the land, the signal becomes “Low” level.

The address signal detecting section 31 includes the signal processing section 4
It receives the wideband tracking error signal RFTE from the differential amplifier 45 of 0, outputs an address pulse signal PADR obtained by binarizing the signal RFTE with a predetermined threshold value, and indicates the timing at which the light beam spot is located in the address area. A gate signal IDGATE (a gate signal that becomes “Low” in the data area and becomes “Hi” in the address area) is output. Specifically, the peak envelope of the wideband tracking error signal RFTE is set to 2
Valued signal and wideband tracking error signal RFT
A signal is generated by inverting a signal obtained by binarizing the bottom envelope of E, and the gate signal ID is obtained by the logical sum of these two signals.
Generate GATE.

FIG. 5 is a block diagram showing a detailed configuration of the address signal detector 31. The address signal detector 31 is roughly divided into components 3101 to 3106 for generating the gate signal IDGATE and components 3107 for generating the address pulse signal PADR. The peak envelope detection unit 3101 receives the wideband tracking error signal RFT from the reproduction signal detector 4.
E) Detect the peak side envelope. The bottom envelope detector 3102 detects the bottom envelope of the wideband tracking error signal RFTE. The binarization circuit 3103 binarizes the signal (the signal indicating the peak envelope of the wideband tracking error signal RFTE) from the peak envelope detector 3101 with a predetermined threshold. The binarization circuit 3104 binarizes the signal (the signal indicating the bottom envelope of the wideband tracking error signal RFTE) from the bottom envelope detection unit 3102 with a predetermined threshold. The NOT circuit 3105 inverts the output signal from the binarization circuit 3104 and outputs the inverted signal. OR
The circuit 3106 outputs a gate signal IDGATE obtained by ORing the output signal from the binarization circuit 3103 and the output signal from the NOT circuit 3105. Binarization circuit 3
Reference numeral 107 denotes a positive threshold value which is the center of the amplitude of the address reproduction signal appearing on the positive side with respect to the zero level of the wideband tracking error signal RFTE, and the threshold value of the address reproduction signal appears on the negative side. An address pulse signal PADR obtained by binarization is output at a negative threshold value which becomes the center of the amplitude.

FIGS. 6A to 6D are timing charts showing the process of generating the gate signal IDGATE in the address signal detecting section 31, and FIG.
6B is a wide-band tracking error signal RFTE input to the address signal detection unit 31, and FIG.
6C shows the output signal of the binarization circuit 3104, and FIG. 6D shows the gate signal IDGATE output from the address signal detector 31.

When the wideband tracking error signal RFTE as shown in FIG. 6A is input to the address signal detector 31, the output of the binarization circuit 3103 is
As shown in (b), when the address signal appears on the positive side with respect to the zero level of the broadband tracking error signal RFTE, it becomes “Hi”, and at other times, it becomes “L”.
ow ". On the other hand, the binarization circuit 31
As shown in FIG. 6 (c), the output of the reference signal 04 is zero with respect to the zero level of the wideband tracking error signal RFTE.
When the address signal appears on the negative side, it becomes “Low”,
At other times, the waveform becomes “Hi”. Therefore, as shown in FIG. 6D, the output of the OR circuit 3106, that is, the gate signal IDGATE becomes "Hi" when the address signal appears in the wideband tracking error signal RFTE, and at other times, it becomes "Hi". L
ow ".

The error rate measuring unit 33 measures the evaluation information used for coarse search of the focus position, that is, the error rate of information recorded in the address area of the optical disc 1 or the error rate of information recorded in the data area. A signal (bit error rate BER) is generated. Specifically, the error rate measurement unit 33 is configured to output the address signal detection unit 3
1 to the demodulation unit 47 based on the gate signal IDGATE.
Error rate of the RF pulse signal PRF from
The number of parity bit errors of the RF pulse signal PRF per unit time) and the error rate of the address pulse signal PADR from the address signal detection unit 31 (for example,
Any one of the number of parity bit errors of the address pulse signal PADR per unit time) is selected and measured, and the result is output to the focus position coarse search unit 50 as a bit error rate BER.

FIG. 7 is a block diagram showing a detailed configuration of the error rate measuring section 33. The selection circuit 3301
An input 1 output selector, and an address signal detection unit 31
When the gate signal IDGATE is "Hi", the RF pulse signal PRF from the demodulation unit 47 is selected and output. When the gate signal IDGATE is "Low", the address pulse signal PADR from the address signal detection unit 31 is selected.
Select and output.

The parity error detector 3302 detects the occurrence of a parity error for each symbol data in the RF pulse signal PRF or the address pulse signal PADR output from the selection circuit 3301, and each time an error is detected, the “High” level is output. Is output as one pulse signal (parity error signal PE). Since the data recorded on the optical disc 1 has a parity bit added for each symbol data, the parity error detector 3302 determines, for each symbol data, the data bits contained therein and the parity bit. And a parity error is detected from

The cycle counter 3303 outputs a clock signal having a fixed cycle to the bit error detector 3304. The bit error detection unit 3304 counts the number of parity error signals PE input during one cycle of the clock signal from the cycle counter 3303, and outputs the result as a bit error rate BER. The focus error detection unit 36 includes two focus signals VFS1 and VFS input from the photodetector 5 via the addition amplifiers 43 and 44.
2, the information corresponding to the difference between them is calculated as expressed by the following equation 1, and the focus error signal FE is calculated.
As S, the focus control unit 26 and the surface shake component removing unit 35
And output to the switch 39.

FES = k1 × VFS1−k2 × VFS2 + OFFSET (Equation 1) In other words, each of the focus signals VFS1 and VFS2 is weighted with a constant value, the difference between them is calculated, and a constant offset value is added. The value is output as the focus error signal FES. At this time, the switch 37
The ratio (focus balance) of the weights (k1 and k2) is determined in accordance with the balance control signal FBAL input from the controller, and the offset value OFFSET (focus offset) is determined in accordance with the offset control signal FOFF input from the switch. As can be seen from the fact that the focus error signal FES is input to the focus control unit 26, the focus error detection unit 36
The focus error (difference between VFS1 and VFS2) is obtained by changing the focus balance and focus offset according to the two control signals FBAL and FOFF.
, That is, the control target position of the focus servo is changed (set).

FIG. 8 is a block diagram showing a detailed configuration of the focus error detector 36. A preceding stage of the focus error detection unit 36 includes a differential amplifier 3613, a feedback resistor 3612, and a focus balance circuit 36.
11 and a D / A converter 3618. The focus balance circuit 3611 includes a voltage-controlled variable resistance component (two transistors are connected in a complementary manner) and the like. This differential amplifier circuit includes a switch 37
The gain ratio (focus balance) for calculating the difference between the two input signals VFS1 and VFS2 is changed in accordance with (an analog value of) the balance control signal FBAL sent from the controller. The rear part includes three resistors 3614 to 36
16, an offset adjustment circuit including a differential amplifier 3617 and a D / A converter 3619. A constant offset value (focus offset) based on the offset control signal FOFF (analog value) sent from the switch 38 is added to the difference signal from the preceding stage.

The switches 37 and 38 are two-input and one-output selectors controlled by the drive controller 14, respectively. When the drive controller 14 receives an instruction from the drive controller 14 to perform a rough search of the focus position, , Control signal FBA from focus position coarse search unit 50
When L1 and FOFF1 are selected and output, and an instruction that precision search is being performed is received, control signals FBAL2 and FOFF2 from the focus position precision search unit 60 are selected and output.

The coarse focus position detecting section 50 is a control circuit for searching for a focus position in the initial stage of focus pull-in, that is, for performing a coarse search. In order to forcibly move the focus position by a fixed distance, two control signals FBAL1 and FOFF1 are output to the switches 37 and 38. At this time, the focus position coarse exploration unit 50 follows the procedure programmed in advance.
L / G switching signal LG from land / groove detector 34
While referring to S, different control is performed when the light beam spot is located on the land track and when it is located on the groove track. This means that, even if the focus position is adjusted so that the reproduction state is optimized for only one of the land track and the groove track, the reproduction state is not always optimal for the other track. This is due to consideration. That is, by searching for the target value of the focus control while distinguishing between the land track and the groove track, good reproduction characteristics can be obtained comprehensively (for both the land track and the groove track).

FIG. 9 is a block diagram showing a detailed configuration of the focus position coarse search unit 50. First storage unit 52
Represents a plurality of focus balance values (balance control signal F
This is a rewritable non-volatile memory having an area for recording a numerical value corresponding to the size of BAL1), and adjusting a focus position in a groove track of the optical disc 1 obtained when the optical disc drive device 100 is assembled and adjusted. One focus balance value indicating the value is stored in advance. Similarly, the second storage unit 53 stores a plurality of focus offset values (offset control signals FOFF
Is a rewritable nonvolatile memory having an area for recording a value corresponding to the size of 1), and adjusting a focus position on a land track of the optical disc 1 obtained when the optical disc drive apparatus 100 is assembled and adjusted. One focus offset value indicating the value is stored in advance.

The DSP 51 is a digital signal processor having a control program inside, and performs software processing for focus position search. Specifically, by outputting the balance control signal FBAL1 while referring to the focus balance value stored in the first storage unit 52 when the light beam spot is located on a groove track on the optical disk 1, an error can be obtained. The optimum focus balance value at which the bit error rate BER from the rate measurement unit 33 is equal to or less than a predetermined value is searched. Subsequently, the balance control signal F
When the light beam spot is positioned on the land track on the optical disc 1 while maintaining the output of BAL1, the second
By outputting the offset control signal FOFF1 while referring to the focus offset value stored in the storage unit 53, the optimum focus offset value at which the bit error rate BER from the error rate measurement unit 33 becomes equal to or less than a predetermined value is searched. .

When a more optimal focus balance value and focus offset value are obtained by such a search, the DSP 51 discriminates these values for the land track and the blue track and discriminates them between the first track and the second track.
And the control signals FBAl1 corresponding to the focus balance value and the focus offset value while distinguishing between the land track and the groove track as a new control reference position of the focus position after the search. FOFF1 switch 3
7 and 38.

The read gate detecting section 32 is a circuit which is optionally used to further improve the accuracy in performing a precise focus position search, and is designated by an address area on the optical disc 1 and by the drive controller 14 in advance. "Hi" in the data area
The gate signal RDGT is output to the focus position precise search unit 60 as follows.

More specifically, the drive controller 14
Receives the focus error signal FES in advance and
By performing the / D conversion, a surface deflection (AC signal) generated when the optical disc 1 rotates is detected, and a gate signal RDG is generated in a data area corresponding to a position where the change of the AC signal is small.
The sectors in these data areas are notified to the read gate detection unit 32 so that T becomes “Hi”. Then, the read gate detection unit 32 determines the address area and the data area (sector) from the wideband tracking error signal RFTE from the signal processing unit 40, and determines the address area and the data area (sector) specified by the drive controller 14 in advance. The gate signal R is set to “Hi”.
Generate a DGT. The gate signal RDGT is used for removing a problem that the precision of the focus control is deteriorated due to the influence of the surface shake in the precise focus position search.

FIG. 10 shows an input signal RFTE of the read gate detecting section 32 and a gate signal IDGA indicating an address area.
TE and output signal RDG from read gate detection unit 32
6 is a timing chart of T. Gate signal RDGT
Indicates an address area and a data sector (read data sector) designated in advance. In the case where high precision is not required in the precise focus position search, the drive controller 14 can stop the function by instructing the read gate detection unit 32. At this time, the read gate detector 32 always sets the gate signal RDGT to “Hi”.

The surface vibration component removing unit 35 is a circuit which is optionally used when a precise focus position search is performed. Removed, and other frequency components (disturbance signal generator 25
And a filter for passing a 1 kHz signal applied from the controller 39), and outputs the passed signal to the focus position precise search unit 60 via the switch 39. This is the same as the role of the read gate detecting unit 32, and is for performing the focus position control with higher precision by eliminating the influence of the surface shake in the precise focus position search.

The switching device 39 is a drive controller 1
4 is a two-input, one-output selector controlled by
Based on an instruction from the drive controller 14, the input / output of the surface runout component removing unit 35 is bypassed. Specifically, in the case of performing a rough search of the focus position, an output signal from the surface shake component removal unit 35 and the focus error detection unit 3 are output based on an instruction from the drive controller 14.
6 and outputs it to the focus position precise search unit 60 as the focus error signal FESS after selection. The switch 39 has a function of determining whether or not the surface shake component removing unit 35 functions in the precise search of the focus position, that is, whether to perform the fine search of the focus position with higher accuracy.

The focus position precise search section 60 is a circuit for performing control for a fine focus position search performed after the coarse focus position search by the coarse focus position search section 50 is completed. Specifically, the switch 39
Of the reproduction signal RF based on the disturbance signal component (disturbance signal output from the disturbance signal generation unit 25) included in the focus error signal FESS transmitted from the microcomputer and the reproduction signal RF transmitted from the signal processing unit 40. An optimum focus position where the envelope becomes large and the jitter of the reproduction signal RF becomes small is searched, and the two control signals FBA are maintained so that such a focus position is maintained by the focus servo by the focus control unit 26.
L2 and FOFF2 are output to the switches 37 and 38. This is because, by performing focus control in consideration of both the envelope and the jitter of the reproduction signal RF, an overall good reproduction state is obtained.

Further, the focus position precise search unit 60
Similar to the focus position coarse search unit 50, different control is performed depending on the L / G switching signal LGS from the land / groove detection unit 34 when the light beam spot is located on the land track and when it is located on the groove track. . This is because a good reproduction characteristic is obtained comprehensively (for both the land track and the groove track) by searching for the target value of the focus control while distinguishing between the land track and the groove track. [Coarse Focus Position Search] Next, the operation when the optical disc drive device 100 configured as described above performs a coarse focus position search during recording / reproduction will be described.

First, the overall operation of the optical disc drive device 100 will be described with reference to FIGS. In addition,
In the coarse focus position search, the switches 37 and 38 are controlled by the control signal FBAL from the focus position coarse search unit 50 according to an instruction from the drive controller 14.
1, FOFF1 is selected and passed, and the adder 24 allows only the signal from the focus controller 26 to pass. Therefore, components (disturbance signal generator 25, read gate detector 32, The surface shake component removing unit 35 and the focus position precise search unit 60) do not operate (not directly related).

First, the drive controller 14 issues an instruction to the rotation control unit 13 to rotate the spindle motor 12 at a constant rotational speed, and then issues an instruction to the seek control unit 11 to coarsen the coarse motion motor 10. Make a seek operation. Subsequently, the modulation unit 42 and the laser power driving unit 41
Is controlled so that the semiconductor laser 8 irradiates the optical disk 1 with a light beam.

The photodetector 5 converts the light beam reflected by the light beam spot on the optical disk 1 into an electric signal after detecting the light beam by the lens divided into four, and adds the signals to the summing amplifiers 43 and 44.
Generates two focus signals VFS1 and VFS2 used for generating the focus error signal FES by adding two of the four signals. The focus error detection unit 36 includes two focus signals VFS1, VFS
Two control signals FBA input from the focus position coarse search unit 50 via the switches 37 and 38 to FS2.
The focus error signal FES is generated by performing the calculation of Expression 1 based on L and FOFF. That is,
The zero level of the focus error, that is, the control target position of the focus servo is changed.

The focus controller 26 controls the focus error signal FES and the focus servo by moving the actuator 2 via the adder 24 and the focus driver 21 based on the focus error signal FES from the focus error detector 36. Focus servo is performed so that the difference from the target position becomes zero. With the focus servo operated, the tracking servo is started next. That is, the difference amplifier 45 generates a broadband tracking error signal RFTE indicating the positional deviation between the center of the track on the optical disc 1 and the light beam spot by taking the difference between the two signals from the reproduction signal detector 4. The tracking control unit 23 performs feedback control by moving the actuator 2 via the tracking driving unit 22 so that the light beam follows a track on the optical disc 1 based on the broadband tracking error signal RFTE.

In the state where the focus control and the tracking control are operated, the reproduction signal RF obtained from the reproduction signal detector 4 through the addition amplifier 46 has a constant amplitude with a reasonable amplitude, if not the maximum. by this,
Stable and good reproduction becomes possible. Next, the relationship between the focus position and the reproduction characteristics will be described. FIG. 11 is a general graph showing a bit error rate BER of the RF pulse signal PRF with respect to a change in the focus position. The horizontal axis indicates the focus position, and the vertical axis indicates the bit error rate BER. Now, assuming that the optimal focus position is 0 μm, the bit error rate BER at the optimal focus position is about 1e-4. As the focus position deviates from the optimum focus position, the bit error rate BER increases quadratically. When the focus position deviates from the optimum position by about ± 0.6 μm, the bit error rate BER is about 1e-3.

The focus position coarse search section 50 intentionally changes the convergence state of the light beam on the optical disk 1 by changing the focus balance or focus offset in the focus error detection section 36. That is, the focus position coarse search unit 50 determines that the error rate of the RF pulse signal PRF measured by the error rate measurement unit 33 is equal to or less than a predetermined value,
For example, by repeatedly changing the focus balance or the focus offset until the bit error rate becomes 5e-4 or less, a more optimal focus position is searched. As can be seen from FIG. 11, when the reproduction state in which the bit error rate BER is 5e-4 or less is converted into a shift of the focus position, it corresponds to a range of ± 0.3 μm with respect to the optimum focus position. That is, the focus position coarse search unit 50 corrects the two control signals FBAL1 and FOFF1 to the focus error detection unit 36 based on the bit error rate so that the deviation from the optimum focus position is equal to or less than a predetermined value.

Now, the coarse focus position search will be described in more detail. FIG. 12 is a flowchart showing a detailed operation of the focus position coarse search unit 50. Note that, as shown in FIG. 9, the focus position coarse search unit 50 is realized in software by a DSP 51 or the like having a built-in control program. The search for the coarse focus position is performed in a state where the drive controller 14 instructs the tracking control unit 23 to operate the tracking control for causing the light beam to follow a specific land track or groove track. In other words, a still jump that jumps back to the inner peripheral side of the optical disc 1 every time the optical disc 1 makes one revolution causes the following to be performed while the light beam follows a specific land track or a specific groove track on the optical disc 1. The procedure is performed.

Now, it is assumed that a reproduction error has occurred at a certain value or more, so that a coarse focus position search is required. That is, the DSP 5 of the focus position coarse search unit 50
1 outputs the focus balance value and the focus offset value previously stored in the first storage unit 52 and the second storage unit 53 to the focus error detection unit 36 as control signals FBAL1 and FOFF1, however, in this state, Assume that the bit error rate BER measured by the error rate measuring unit 33 exceeds a certain value (5e-4).

First, the rough focus position detecting section 50 receives the L / G switching signal LGS from the land / groove detecting section 34.
It is determined whether the light beam is located on the land track or the groove track according to the logical level of (step S10). Specifically, the L / G switching signal LGS is observed, and this determination is made based on whether the signal is at the “Low” level or the “Hi” level for a predetermined time or more.

As a result, when it is determined that the focus balance value is located on the groove track, the focus balance value (current FBAL value) stored in the first storage unit 52 is read, and the value is read as A (A = current FBAL value) (step S11). Next, a new focus balance value (updated FBAL value) is calculated (step S12). Specifically, the calculation shown in Expression 2 is performed with the amount of change of the FBAL value as B (focus balance value converted to a focus position, for example, 0.6 μm) and the updated FBAL value as X.

X = A + B (Expression 2) The obtained updated FBAL value (X) is converted
L1 is output to the focus error detection unit 36 via the switch 37 (step S13). This means that the focus balance in the focus error detector 36 has been changed so that the focus position changes by +0.6 μm with respect to the focus position before the change.

With the focus balance changed in this way, a bit error rate BER is received from the error rate measuring unit 33 (step S14), and it is determined whether the bit error rate BER is 5e-4 or less (step S14). S15). As a result, if the bit error rate BER is 5e-4 or less, as described above with reference to FIG. 11, the deviation between the focus position after changing the focus balance and the optimum focus position is within 0.3 μm. After the determination, the updated FBAL value (X) is stored in the first storage unit 52, and then the focus position search ends normally (step S28).

On the other hand, the bit error rate BER is 5e-
If it is greater than 4, it is determined how many times the FBAL value change process has been performed (step S16). As a result, if the number of times is the first time, the second update FBAL value is calculated (step S17). Specifically, the calculation shown in Expression 3 is performed. X = AB (Equation 3) Then, the obtained FBAL value (X) is converted to the balance control signal F.
The signal is output to the focus error detection unit 36 via the switch 37 as BAL1. This means that the focus balance in the focus error detection unit 36 has been changed so that the focus position changes by −0.6 μm with respect to the focus position before the change.

The steps S14 and S15 are repeated with the focus balance changed as described above. That is, the bit error rate BER is received from the error rate measuring unit 33 (step S14), and it is determined whether the bit error rate BER is 5e-4 or less (step S15), and the bit error rate BER is 5e-4 or less. If so, the updated FBAL value (X) is stored in the first storage unit 52, and then the focus position search ends normally (step S28).

On the other hand, the bit error rate BER is 5e-
If it is greater than 4, it is determined how many times the FBAL value change process has been performed (step S16). If the number of times has been the second time, it is considered that the focus position search could not be completed normally and the focus position search Is completed (step S29). In the determination in step S10,
When the focus position coarse search unit 50 determines that the light beam is located on the land track, the second storage unit 53
Focus offset value (current FO
FT value), and read the value as C (C = current FOFT).
(Step S21). Next, a new focus offset value (updated FOFT value) is calculated (step S22). Specifically, the calculation shown in Expression 4 is performed, where D is the change amount of the FOFT value (the focus offset value is 0.6 μm, for example, converted into a focus position), and Y is the updated FOFT value.

Y = C + D (Equation 4) Next, the obtained FOFT value (Y) is converted to an offset control signal F
OFF1 is output to the focus error detector 36 via the switch 38 (step S23). This means that the focus offset in the focus error detector 36 has been changed so that the focus position changes by +0.6 μm with respect to the focus position before the change.

With the focus offset changed in this way, the bit error rate BER is received from the error rate measurement unit 33 (step S24), and it is determined whether the bit error rate BER is 5e-4 or less (step S24). S25). As a result, if the bit error rate BER is 5e-4 or less, it is determined that the deviation between the focus position after the focus offset change and the optimal focus position is within 0.3 μm, and the FOFF value (Y) is set to the fourth position. After storage in the second storage unit 53, the focus position search is normally terminated (step S28).

On the other hand, the bit error rate BER is 5e-
If it is larger than 4, it is determined how many times the FOFF value change processing has been performed (step S26). As a result, if the number of times is the first time, the second update FOFF value is calculated (step S27). Specifically, the calculation shown in Expression 5 is performed. Y = CD (Equation 5) Then, the obtained FOFF value (Y) is converted to the balance control signal F.
OFF1 is output to the focus error detection unit 36 via the switch 37. This means that the focus offset in the focus error detection unit 36 has been changed so that the focus position changes by −0.6 μm with respect to the focus position before the change.

Then, steps S24 and S25 are repeated with the focus offset changed as described above. That is, the bit error rate BER is received from the error rate measuring unit 33 (step S24), and it is determined whether the bit error rate BER is 5e-4 or less (step S25), and the bit error rate BER is determined.
Is 5e-4 or less, the FOFF value (Y) is set to the second
After the storage in the storage unit 53, the focus position search ends normally (step S28).

On the other hand, the bit error rate BER is 5e-
If it is greater than 4, it is determined how many times the FOFF value change processing has been performed (step S26). If the number of times has been the second time, it is considered that the focus position search could not be completed normally and the focus position search was not completed. Is completed (step S29). If a new focus balance value and / or focus offset value is detected in steps S15 and S25, the focus position coarse search unit 50 continues to execute the new focus balance value until the search is executed again. Control signal FBAL1, FOFF1
To the focus error detection unit 36. That is, when the light beam spot is located on the groove track, the focus position coarse search unit 50 sets the first storage unit 5.
The balance control signal FBAL1 is output using the latest focus balance value stored in No. 2 (the offset control signal FOFF1 is output as zero). On the other hand, when the light beam spot is located on the land track, the first storage unit is used. 5
The balance control signal FBAL1 is output using the latest focus balance value stored in the second storage unit 2, and the offset control signal FOFF1 is output using the latest focus offset value stored in the second storage unit 53. As a result, the focus position search by the focus position coarse search unit 50 is reflected as a decrease in the bit error rate BER in the subsequent recording and reproduction.

The reason why the change amount of the focus position is set to 0.6 μm in the present embodiment is as follows. That is, the initial focus position of the optical disk drive device is adjusted so that an address or a signal recorded in a data area on the optical disk can be favorably reproduced during assembly adjustment. However, a read error may increase or recording characteristics may deteriorate due to a change in a focus position indicated by a focus error signal due to a temperature characteristic of the optical head, a temporal change, or the like. The temperature characteristic of the optical head is 0.011 depending on the configuration of the optical head.
It shows a change characteristic of 4 μm / ° C. That is, when the temperature around the optical head rises from 25 ° C. at the time of starting the device to 60 ° C., the focus position changes by 0.4 μm. If the optical head characteristics change over time in addition to the temperature characteristics of the optical head, it may not be possible to reproduce the address or the signal recorded in the data area on the optical disk.

In particular, in the address area, the focus position is determined by the bit error rate B of the address pulse signal.
If the focus position is shifted by ± 0.6 μm or more from the focus position where the ER is minimum, the address reading becomes poor. So, for example,
When the focus position deviates from the focus position where the bit error rate BER is minimized in the range of +0.6 μm to +1.0 μm, the focus position is forcibly set to −0.6.
If moved by μm, the focus position will be 0 μm to +0.4 μm
, The address can be read normally.
Further, for example, when the focus position is -0.6 μm to-
If the bit error rate BER deviates from the focus position in the range of 1.0 μm and the focus position is forcibly moved by +0.6 μm, the focus position becomes 0 μm.
Since the value falls within the range of m to −0.4 μm, the address can be read normally.

For the above reasons, in this embodiment,
With the change amount of the focus position set to 0.6 μm, the focus position where the bit error rate BER becomes 5e-4 or less is searched. As described above, the focus position coarse exploration unit 50 adjusts the focus balance in the focus error detection unit 36 so that the bit error rate BER is equal to or less than a certain value for only the groove track. By adjusting the focus offset in the focus error detection unit 36 so that the bit error rate BER becomes a certain value or less as a target, the zero level of the focus error, that is,
The control target of the focus servo was determined. in this way,
In the focus position coarse search in this embodiment, since the focus position is searched using both the groove track and the land track, unlike the conventional method in which the search is performed using only one of the tracks, The disadvantage that the reproduction characteristic of one track is extremely poor is avoided. That is, focus control that can obtain good reproduction characteristics for both tracks, that is, focus control that suppresses reproduction errors comprehensively, is realized.

In this embodiment, the coarse focus position detecting section 50 adjusts the focus balance only for the groove track, and then adjusts the focus offset only for the land track, so that both tracks can be adjusted. Although the optimum focus position was searched for, the present invention is not limited to such track types and procedures.

FIG. 13 shows a modification of the coarse focus position search of this embodiment. This figure shows a total of eight different search method Nos. 1 to 8 are shown, and control parameters (focus position coarse search unit 50) used for each search method are shown.
3 shows control signals FBAL1, FOFF1) output from the control unit 36 to the focus error detection unit 36. In the figure, the control parameters surrounded by squares indicate that the control parameters are targets determined by the exploration based on the procedure shown in FIG. 12, and the dotted arrows indicate that the control parameters thus determined are It means that it is used as it is as the other control parameter.

In each of these eight methods, the focus position is separately searched in consideration of both the groove track and the land track, and the search procedure is basically shown in FIG. This is the same as the flowchart (it is determined whether the bit error rate BER becomes equal to or less than a certain value). In FIG. 13, the exploration example N
o. 1 indicates the present embodiment (the procedure shown in FIG. 12). That is, when the light beam spot is located on the groove track, the focus position
And outputs only the balance control signal FBAL1 corresponding to the latest FBAL value stored in the storage section 52 of the storage section 52.
1 and the latest FOFF stored in the second storage unit 53
When the offset control signal FOFF1 corresponding to the value is output, FBAL
After the value is adjusted, the FOFF value is adjusted next for the land track while maintaining the FBAL value.

Search example No. 2 shows the present embodiment (Exploration N
o. This corresponds to the case where the types of the tracks in 1) are interchanged. Exploration example No. The method 3 uses different FBAL values (first and second FBAL values) for the groove track and the land track, and does not adjust the focus offset. That is,
When the light beam spot is located on the groove track, the focus position coarse search unit 50 outputs only the balance control signal FBAL1 corresponding to the latest first FBAL value stored in the first storage unit 52 and outputs the balance control signal FBAL1 to the land track. If it is located, the latest second stored in the first storage unit 52
When only the balance control signal FBAL1 corresponding to the FBAL value is output, the first FBAL value is adjusted for the groove track, and then the second FBAL value is adjusted for the land track.

As described above, by changing the focus control target position according to the focus balance for both the land track and the groove track, the focus position can be set without giving an offset to the target value of the focus control unit. Therefore, the problem that the dynamic range of the focus control system is narrowed by the offset is avoided. For example, when disturbance vibration is applied to the apparatus during the recording / reproducing operation, a problem occurs when the focus position is adjusted by the offset (the focus control system is likely to be saturated, and the performance of following the focus control target position is deteriorated. However, according to this method, the inconvenience can be avoided and the playability of the device can be improved.

Search example No. 4 is a different FOFF value for the groove track and the land track (first FOFF value).
And the second FOFF value), and the focus balance is not adjusted. That is, when the light beam spot is located on the groove track, the focus position coarse search unit 50 sets the offset control signal FOF corresponding to the latest first FOFF value stored in the second storage unit 53.
In the case where only F1 is output and only the offset control signal FOFF1 corresponding to the latest second FOFF value stored in the second storage unit 53 is output in the case of being located on the land track, the first FO is targeted for the groove track.
After adjusting the FF value, the second FOFF value is adjusted next for the land track.

In general, the focus offset adjustment circuit can be realized with a simpler configuration than the focus balance adjustment circuit, and the response of the focus servo due to the change in the focus balance is poorer than the response due to the change in the focus offset. Therefore, according to this search example, a simple and high-speed focus servo control circuit is realized.

Search example No. No. 5, the basic control method is the above-mentioned search example No. Same as 1. That is, when the light beam spot is located on the groove track, the focus position coarse search unit 50 determines the balance control signal FBAL1 corresponding to the latest FBAL value stored in the first storage unit 52.
And outputs an offset control signal FOFF1 corresponding to the latest FOFF value stored in the second storage unit 53 together with the balance control signal FBAL1 when it is located on the land track.

However, this search example No. In 5,
The focus position coarse search unit 50 determines the search example No. By performing the first procedure and the like, the FOFF value corresponding to the difference between the optimal focus position for the groove track and the optimal focus position for the land track, that is, substantially the same (OFF) for both the groove track and the land track An FOFF value that can obtain a focus state is obtained (it does not need to be optimal), and the FOFF value is stored in the second storage unit 53 in advance. Then, the focus position coarse search unit 50 performs the FBA on only the groove track.
Adjust the L value.

Search example No. No. 6 is the above exploration example No. 5 corresponds to the one obtained by changing the type of the track. These exploration example Nos. According to 5 and 6, it is possible to automatically obtain the optimum focus position for the other track even though the focus balance is adjusted only for one track. In other words, the focus position search in one of the groove track and the land track also optimizes the focus position of the other track, thereby shortening the focus position adjustment time.

Search example No. 7 has different FBAL values for the groove track and the land track (first
And the second FBAL value) and the common FOFF value, and the focus balance is not adjusted. That is, when the light beam spot is located on the groove track, the focus position coarse search unit 50 controls the control signals FBAL1 and FOF corresponding to the latest first FBAL value and FOFF value stored in the two storage units 52 and 53, respectively.
F1 is output, and when it is located on the land track, the first storage 52
In the case where the balance control signal FBAL1 corresponding to the latest second FBAL value stored in the search example No. is output, the focus position coarse search unit 50 first sets the search example No. By performing the procedure 3 and the like, the first FBAL is obtained such that substantially the same (non-optimal) focus state can be obtained for both the groove track and the land track.
Values and a second FBAL value are obtained, and these are stored in the first storage unit 5.
2 is stored in advance. Then, the focus position coarse search unit 50 performs FOFF for only the groove track.
Adjust the value.

Search example No. No. 8 is the above exploration example No. 7 corresponds to the one obtained by changing the type of the track. These exploration example Nos. Also in 7 and 8, if the focus position is searched for one of the groove track and the land track, the focus position of the other track is also optimized, so that the focus position adjustment time is shortened.

In this embodiment, even if the focus position at the time of reproduction is optimized because the output power of the optical head is different between the time of reproduction and the time of recording, the focus position at the time of recording may deviate from the optimum focus position. is there. In this case, the process of correcting the difference between the focus position at the time of reproduction and the focus position at the time of recording by correcting the focus position at the time of recording with respect to the focus position at the time of reproduction for both the groove track and the land track. Can be simplified.

In the present embodiment, the error rate measurement unit 33 detects a parity error. In addition to this, for example, a CRCC (Cyclic Redundancy Check Cod) is used.
A method of detecting a reproduction error using an error correction code called e) may be employed. To find the CRCC,
The data to be recorded on the optical disc 1 is divided into blocks, the data bits are represented by a polynomial, and this formula is divided by a predetermined value called a generator polynomial. The result of the division is added as a check bit after the data bit and recorded.
To detect an error during reproduction, the data including the data bits and the check bits is once again divided by a generator polynomial.
At this time, if there is no code error, the result of division and division becomes zero, and if there is a code error, the result of division is not zero and the result of division does not become zero, so that the presence or absence of an error can be determined. Therefore, the error rate measurement unit 33 can be configured by using an error detector based on CRCC instead of the parity error detector 3302 in the present embodiment.

Further, in this embodiment, as shown in FIG. 12, the focus position coarse search section 50 has two positions shifted by +0.6 μm and −0.6 μm with respect to the adjustment value stored in advance. Although the focus position search was attempted for only the focus position, the focus position change amount may be made smaller than 0.6 μm (for example, the change amount = 0.1 μm) to search for the focus position. As a result, the focus position where the bit error rate BER is minimized can be searched with higher accuracy.

Further, when the focus position search section 50 of this embodiment searches the focus position based on the RF pulse signal PRF, the focus position coarse search section 50 searches the focus position so that the error rate of the RF pulse signal PRF becomes a predetermined value or less. And
When the focus position search is performed based on the address pulse signal PADR, the focus position at which the error rate of the address pulse signal PADR is equal to or less than a predetermined value is searched. Is the maximum focus position, or the focus position where the jitter of the reproduction signal is the minimum, or the focus position between the focus position where the amplitude of the reproduction signal is the maximum and the focus position where the jitter of the reproduction signal is the minimum, or The focus position where the error rate of the reproduction signal is minimized may be searched.

For example, the address pulse signal PAD is supplied to the parity error detector 3302 of the error rate measuring section 33.
By directly inputting only R, the bit error rate BER output from the error rate measuring unit 33 is:
This indicates a bit error rate that occurs only in the address area of the optical disc 1. This makes it possible to search for a focus position based on an error rate only in the address area. For example, as in a rewritable optical disk immediately after formatting, the data area is unrecorded but information is recorded in the address area. An optical disk drive capable of performing a focus position search on a simple optical disk is realized. [Precise focus position search] Next, a detailed description will be given of related components when the optical disc drive apparatus 100 performs a precise focus position search during recording / reproduction. For convenience of explanation, first,
A case where the read gate detection unit 32 and the surface runout component removal unit 35 are not operated will be described.

For precise focus position search, the drive controller 14 first records the recording position, starts recording or stops recording in order to record a focus position search test signal in the drive test area on the optical disc 1. The test recording control signal TWCNT for controlling the
Output to 2. Then, after the recording is completed, a focus position precise search control signal FPSON for controlling start or stop of the focus position precise search is output to the focus position precise search unit 60.

Further, the drive controller 14 receives the binarized address pulse signal PADR from the address signal detecting section 31 and sends the binarized address pulse signal PADR from the optical head 7 to the optical disk 1.
The current position of the light beam convergently irradiated on the upper track can be recognized, and the address pulse signal PA
By instructing the tracking control unit 23 based on the DR, the light beam can be moved to an arbitrary track on the optical disc 1.

The reason why the focus position search test signal is recorded on the optical disk 1 before the start of the precise search of the focus position is as follows. That is, the optical disc 1 of the present embodiment is a recordable disc, and when data is not recorded, no data is recorded in a data area other than a preformat area such as an address area in which an address signal is recorded in advance. When such an optical disc 1 is mounted on the optical disc drive device 100, the focus position precise search unit 60 that performs a precise search of the focus position based on the reproduction signal RF of the data area may start the focus search. Can not. For this purpose, prior to the focus position search, a focus position search test signal is recorded in the drive test area of the unrecorded optical disc 1 in advance.

That is, prior to the focus position search, the drive controller 14 determines whether or not the optical disk 1 mounted on the optical disk drive device 100 is unrecorded. A test signal for focus position search is recorded in the test area in advance, and information for specifying (the track of) the drive test area is stored for later reuse. If it is determined that the mounted optical disk 1 has been recorded, the optical head 7 is moved to the recording position (track) by seeking to start the focus position search.

FIG. 14 is a diagram for explaining the drive test area of the optical disk 1, and shows the SS-L / GF
2 shows an information area layout of an MT optical disc 1; As shown in the figure, a sector number indicating a physical address of the optical disc 1 is assigned according to the position of the optical disc 1, and a lead-in area (sector numbers 27AB0hex to 30FFFhex) on the inner circumference of the disc has embossed data. Area (sector number 27AB0hex to 2FFFh
ex), a mirror area (an area between the embossed data area and the rewritable data area without address assignment), and a rewritable data area (sector number 300).
00hex to 30FFFFhex), and there is a drive test area in the rewritable data area. The lead-out area (sector numbers 16B480hex to 17966Fhex) on the outer periphery of the disk is a rewritable data area, and includes a drive test area. In the lead-in area and the lead-out area of the optical disc 1, there are a disc test area and a drive test area as test areas. "). As described above, the optical disk 1 of the SS-L / GFMT type has test areas in the lead-in area on the inner circumference of the disk and the lead-out area on the outer circumference of the disk.

Note that the drive controller 14 modulates the modulating section 42 so as to record the focus position search test signal in the test area before operating the focus position precision search, particularly every time the optical disk drive 100 is started.
To instruct. Also, if recording is always repeated only on the track having the same address, the recording / reproducing characteristics of the track will be significantly deteriorated. Therefore, the track to be recorded is changed randomly in the test area every time learning is performed. Also, the reproduction signal RF from the optical disk 1 necessary for the focus position precision search is:
Since it is necessary that the land track and the groove track on the optical disk 1 are each continuously recorded for one or more rotations, the drive controller 14 randomly selects the groove track from the test area on the inner circumference of the disk and the test area on the outer circumference of the disk. After the determination, the modulation unit 42 is instructed to record one track (= 1 rotation) continuously from the head address of the determined groove track and to continuously record one track (= 1 rotation) of the land track as it is.

A specific procedure for determining the test area by the drive controller 14 is as follows. Now, the start track address of the test area in the lead-in area is set to TNi.
h, if the last track address of the test area in the lead-in area is TNie, the top track address of the test area in the lead-out area is TNoh, and the last track address of the test area in the lead-out area is TNie,
Recording in the test area is performed for two tracks (= 2 rotations) from the beginning of the groove track to the end of the next land track. That is, the recording symmetry track is TNi
h to TNie-1 and TNoh to TNee-1. In terms of the actual sector number, TN
ih = 30600h, TNie-1 = 30CDDh, T
Noh = 16BE80h, TNoe-1 = 16C52F
h. The sector numbers of zero sectors included in the sector numbers 30600h to 30CDDh and 16BE80h to 16C5Fh are randomly determined.

Next, the overall operation of the optical disc drive device 100 when performing a precise focus position search will be described with reference to FIGS. Under the control of the drive controller 14, after the optical disc 1 is rotated at a predetermined rotation speed, the optical beam from the semiconductor laser 8 is irradiated on the optical disc 1. The focus error detector 36 generates and outputs a focus error signal FES from two focus signals VFS1 and VFS2 based on the light beam reflected from the optical disc 1. At this time, the focus error detection unit 36 changes the focus balance and the focus offset based on the control signals FBAL2 and FOFF2 from the focus position precise search unit 60, thereby providing a zero level of the focus error, that is, the control target position of the focus servo. To change.

The focus control unit 26 moves the actuator 2 via the addition unit 24 and the focus drive unit 21 based on the focus error signal FES from the focus error detection unit 36, and thereby the focus error signal from the focus error detection unit 36. Focus servo is performed so that the difference between the focus position corresponding to the FES and the target position for focus control becomes zero. In addition, the addition unit 24 receives an instruction from the drive controller 14 and
Only if you are conducting a precision search of the focus position,
The disturbance signal from the disturbance signal generation unit 25 and the signal from the focus control unit 26 are added, and the added signal is output to the focus drive unit 21. However, when the precision search of the focus position is not performed, the focus control The signal from the section 26 is output to the focus drive section 21 as it is.

When the focus servo is operated by the focus control unit 26, the reproduction signal detector 4 and the difference amplifier 45 obtain the wideband tracking error signal RFTE indicating the positional deviation between the track center on the optical disc 1 and the light beam. Can be The tracking control unit 23 performs feedback control based on the broadband tracking error signal RFTE so that the light beam follows a track on the optical disc 1. When the focus control and the tracking control are activated, a reproduced signal having a constant amplitude with a reasonable amplitude is obtained from the reproduced signal detector 4 if it is not the maximum.

The drive controller 14 can read, via the demodulation unit 47, the address on the optical disk 1 where the light beam is currently located, while the focus control and the tracking control are operating as described above. Then, the drive controller 14 randomly searches for a groove track in the test area on the optical disc 1. When the drive controller 14 searches for a target groove track in the test area, it is preferable that the drive controller 14 searches for a track on the inner circumferential side of one track from the target groove track, and that the light beam starts from the first sector of the target groove track. When (= sector zero) is reached, a command for generating a recording signal (hereinafter referred to as a “test recording command”) and a test signal for focus position precise search are sent to the modulation unit 42.

The modulation section 42 is provided with the drive controller 14
A test signal for focus position precise search is output to the laser power drive unit 41 based on the test recording command from the CPU. The laser power driver 41 receives the test signal from the modulator 42 and modulates the laser power with the test signal. The drive controller 14 records the test signal in two consecutive tracks from the randomly determined groove track, that is, two consecutive tracks in the order of the groove track and the land track from the inner circumference side of the optical disc 1, and ends the recording operation.

Next, the drive controller 14 moves the optical head 7 to a groove track in the test area recorded as described above. Also in this case, it is preferable to move to the inner circumferential side of one track of the target groove track, and when the light beam is positioned on the target groove track, still jump so that the light beam always follows the groove track. To the tracking control unit 23.
The tracking control unit 23 performs a still jump every rotation of the optical disc 1 and controls the tracking drive unit 22 so that the light beam always follows only one groove track of the test area randomly searched.

After the focus control and the tracking control are operated as described above, the still jump is performed for each rotation of the optical disk 1, and the light beam always follows the groove track in the test area. Generates a disturbance signal from the disturbance signal generator 25 and causes the focus control system to apply a disturbance. The focus position is forcibly changed by this application, and the focus error signal FES includes the frequency component (disturbance component) of the disturbance signal. Then, the focus position precise search unit 60 transmits light to the optical disc 1 based on the disturbance component included in the focus error signal FESS sent from the switch 39 and the envelope and jitter of the reproduction signal RF sent from the signal processing unit 40. Information indicating the deviation of the beam position, that is, focus position information FPIS is obtained, and the obtained focus position information FPI is obtained.
Based on S, the optimum focus position for both the amplitude and the jitter of the reproduction signal RF, that is, the optimum focus position is searched. Further, the focus position precise search unit 60 determines the data area or the drive controller 14 based on the gate signal IDGATE from the address signal detection unit 31 and the gate signal RDGT from the read gate detection unit 32.
By obtaining the focus position information FPIS only for the specific data area specified by
Search for the optimal focus position with higher accuracy.

FIG. 15 is a diagram for explaining the optimum focus position in the precise search of the focus position.
Envelope R of reproduction signal RF with respect to focus position
The FENV and the magnitude of the reproduction jitter are shown. As shown in the figure, with respect to the focus position (horizontal axis), the envelope has a certain focus position (−0.50 μm in the figure).
m) is a convex curve that shows the maximum, and the jitter is a concave curve that becomes the minimum at a focus position (0 μm in this figure) different from the position where the envelope becomes the maximum. In other words, the focus position (the maximum envelope position) where the envelope of the reproduction signal RF is maximum is different from the focus position (the minimum jitter position) where the jitter of the reproduction signal RF is minimum. In the present embodiment, a value obtained by multiplying the envelope and the reproduction jitter of the reproduction signal by respective coefficients and adding them (focus position information FPIS)
The optimal focus position is searched based on the. Specifically, the focus position precise search unit 60 adjusts the coefficient for multiplying the envelope and the coefficient for multiplying the jitter so that the optimum focus position is located at a predetermined position (for example, a predetermined position between the maximum envelope position and the minimum jitter position). -0.
25 μm).

FIG. 16 shows a focus position precise search unit 60.
FIG. 3 is a block diagram showing a detailed configuration of FIG. The envelope detector 61 detects the envelope of the reproduction signal RF from the signal processor 40. The first high-pass filter 63 is
The rotation frequency (for example, 39.7) of the reproduction signal envelope output from the envelope detection section 61 of the optical disc 1
The filter is a filter that blocks a frequency component equal to or lower than 8 Hz) and passes a frequency component equal to or higher than a predetermined frequency, that is, a signal component equal to or higher than the frequency (1 kHz) of the disturbance signal output from the disturbance signal generation unit 25. The first gain adjuster 66 adjusts the gain of the output signal of the first high-pass filter 63 to a predetermined value.

The jitter detector 62 binarizes the reproduction signal RF with a predetermined threshold to generate an RF pulse signal PRF, and detects jitter from the RF pulse signal PRF and the internally generated reference clock signal. The second high-pass filter 64 has the same characteristics as the first high-pass filter 63, and passes the frequency (1 kHz) component of the disturbance signal of the reproduced signal detected by the jitter detection unit 62 to pass through the optical disc 1. The component below the rotation frequency (for example, 39.78 Hz) is cut off. The second gain adjuster 67 adjusts the gain of the output signal of the second high-pass filter 64 to a predetermined value.

The subtractor 69 subtracts the output signal of the second gain adjuster 67 from the output signal of the first gain adjuster 66. This subtraction is performed when the focus position deviates from the optimum focus position, the envelope signal output from the envelope detection unit 61 decreases, and the jitter signal output from the jitter detection unit 62 increases. This is because the difference in the polarity of each signal change is considered.

The third high-pass filter 65 has the same characteristics as the first high-pass filter 63,
Of the focus error signal FESS outputted from the optical disc 1, the frequency component (1 kHz) of the disturbance signal is allowed to pass, and a component equal to or lower than the rotation frequency (for example, 39.78 Hz) of the optical disc 1 is cut off. The third gain adjuster 68 adjusts the gain of the output signal of the third high-pass filter 65 to a predetermined value. The multiplier 70 outputs the output signal from the subtractor 69 and the third signal.
Is multiplied by the output signal from the gain adjustment unit 68, and the result is used as focus position information FPIS.
Output to 1.

The third storage section 72 is a rewritable nonvolatile memory for storing the latest focus balance value obtained for the groove track in the precise search of the focus position. The fourth storage unit 73 is a rewritable nonvolatile memory for storing the latest focus offset value obtained for the land track in the precise search of the focus position.

The averaging processing section 71 includes a gate signal IDGATE sent from the address signal detection section 31 and a gate signal RDG sent from the read gate detection section 32.
Multiplier 7 for only the period specified by T
The focus position information FPIS from 0 is averaged, the obtained average value is stored, and the control signals FBAL2 and FOFF2 corresponding to the average value are output to the focus error detection unit 36 via the switches 37 and 38. At this time, as in the case of the coarse search described above, based on the L / G switching signal LGS from the land / groove detection unit 34,
The control signals FBAL2 and FOFF2 are changed while distinguishing between the groove track and the land track. In particular,
When the L / G switching signal LGS indicates a groove track, the averaging processing unit 71 performs the following based on the obtained average value.
A control signal (focus balance value) for setting a more optimal focus position is determined and stored in the third storage unit 72, and the focus balance value is stored in the control signal FBA.
When the L / G switching signal LGS indicates a land track, the averaging processing unit 71 maintains the output of the control signal FBAL2 and, based on the obtained average, obtains a more optimal signal. A control signal (focus offset value) for setting the focus position is determined and stored in the fourth storage unit 73, and the focus offset value is output as a control signal FOFF2.

FIG. 17 is a block diagram showing a detailed configuration of the averaging processing section 71. The time measuring device 7101 has a predetermined wait time (200 μs) from the rising edge of the gate signal IDGATE from the address signal detecting section 31.
Time measurement is started later, and the time for one cycle of disturbance (1 ms)
Is measured, and a timer signal TMS indicating the time during the measurement is output to the AND circuit 7109. AND circuit 7109
Takes the logical product of the timer signal TMS from the time measuring device 7101 and the gate signal RDGT from the read gate detector 32, and outputs the result as the data acquisition timing signal DGT.
The signal is output to the first and third averaging circuits 7102 and 7104 as S. That is, the gate signal RDGT
Is "Hi" and the timer signal TMS from the time measuring device 7101 is "Hi", the averaging in the first averaging circuit 7102 and the third averaging circuit 7104 is permitted.

The first selecting circuit 7106 outputs the focus position information FPIS from the multiplier 70 to the first averaging circuit 7102 when the L / G switching signal LGS is “Hi” (groove track), This is a selector that outputs to the third averaging circuit 7104 at the time of “Low” (land track). The first averaging circuit 7102 averages the focus position information FPIS from the first selection circuit 7106 during a period when the timing signal DGTS from the AND circuit 7109 is “Hi”. This is because when the read gate detection unit 32 is not operating (when the gate signal RDGT is always “Hi”), the average value of the focus position information FPIS in one cycle of the disturbance signal is calculated. Will be. The second averaging circuit 7103 includes:
A control program is included in the DSP or the like. The average value obtained by the first averaging circuit 7102 is further averaged for a predetermined number of times (for example, 24 periods of a disturbance signal),
A new focus target position M11 (focus balance value) for a groove track determined according to the average value is output. The relationship between the focus position information and the new focus target position (specific procedure for precise search) will be described later.

The third averaging circuit 7104 and the fourth averaging circuit 7105 are respectively the first averaging circuit 7102
And the same function as the second averaging circuit 7103,
They differ only in that they function when the L / G switching signal LGS is "Low" (land track). Therefore,
The fourth averaging circuit 7105 outputs a focus target position M12 (focus offset value) for the land track.

The second selection circuit 7107 selects the second averaging circuit 7103 when the L / G switching signal LGS is "Hi" (groove track), and selects the second averaging circuit 7103 when it is "Low" (land track). 4 is a selector for selecting the averaging circuit 7105 and outputting the respective output signals to the third selection circuit 7108. The third selection circuit 7108 is
When the / G switching signal LGS is "Hi", the focus target position M11 (focus balance value) in the groove track is output to the third storage unit 72, and when the L / G switching signal LGSLGS is "Low", the land track is output. Is output to the fourth storage unit 73. Further, when reproducing the signal from the groove track, the third selection circuit 7108 reads out the latest focus target position M11 (focus balance value) stored in the third storage unit 72 and reads out the signal from the land track. When a signal is reproduced, the focus target position M12 (focus offset value) in the latest land track stored in the fourth storage unit 73 is read and output to the focus error detection unit 36 via the switches 37 and 38. .

FIG. 18 shows a disturbance signal and a gate signal IDG when the read gate detector 32 is not operating.
5 is a timing chart of an ATE and a timer signal TMS. Here, since the read gate detection unit 32 is not operating (the gate signal RDGT is always “Hi”), the timer signal TMS becomes equal to the timing signal DGTS. In the figure, the gate signal ID from the address signal detector 31 is shown.
A state is shown in which the time measuring device 7101 starts measurement after a predetermined wait time (200 μs) from the falling edge of GATE and stops when the time corresponding to one cycle of the disturbance signal has elapsed. Thus, the data acquisition timing signal DGTS for averaging the focus position information FPIS for one period of the disturbance in the data area is obtained.

FIGS. 19A and 19B show the gate signal IDGATE, the data acquisition timing signal DGTS, and the gate signal in the groove and land during the precise focus position search when the read gate detector 32 is not operating.
FIG. 19A is a timing chart of the L / G switching signal LGS, and FIG.
FIG. 19B is a timing chart in the land.

The drive controller 14 controls the tracking control unit 23 to perform a still jump every one rotation of the optical disk 1 during the precise search of the focus position, so that the light beam on the optical disk 1 is always grooved. Control is performed so as to follow a track or a land track. Therefore, when the light beam on the optical disc 1 follows the groove track, L / G
The switching signal LGS is set to L as shown in FIG.
At the / G switch point, the level changes from the “Hi” level indicating the groove to the “Low” level indicating the land.
The waveform changes to the “i” level. That is, after the light beam on the optical disc 1 changes from following the groove track to following the land track,
In the data sector 1, a still jump is performed to return to the groove track that has been followed.

At this L / G switching point, the data acquisition timing signal DGTS is, as shown in FIG.
The period when the gate signal IDGATE is at the “Hi” level, before and after the period, and 1 “Low” in the data sector 0 and the data sector.
The waveform indicates the level. Data acquisition timing signal D
When the GTS indicates the “Low” level, the first averaging circuit 7102 does not acquire the focus position information FPIS from the first selection circuit 7106 (interrupts the averaging).

On the other hand, when the light beam on the optical disc 1 follows the land track, the L / G switching signal LG
The S signal changes from the “Low” level indicating the land to the “Hi” level indicating the groove at the L / G switching point as shown in FIG. Is changed to a “Low” level. That is, after the light beam on the optical disc 1 changes from following the land track to following the groove track, the data sector 1 still jumps and returns to the previously followed land track.

At this L / G switching point, the data acquisition timing signal DGTS is, as shown in FIG.
When the gate signal IDGATE is at the “Hi” level, before and after the period, and at “Low” in the data sector 0 and the data sector 1
The waveform indicates the level. Data acquisition timing signal D
When the GTS indicates the “Low” level, the third averaging circuit 7104 does not acquire the focus position information FPIS from the first selection circuit 7106 (interrupts the averaging).

As can be seen from these timing charts, the averaging processing section 71 discriminates the groove track and the land track while discarding the focus position information FPIS of the address area based on the gate signal IDGATE from the address signal detection section 31. Separately, the focus position information FPIS is averaged. That is, the focus position information FP obtained only in the data area in the groove track
The IS and the focus position information FPIS obtained only in the data area of the land track are averaged independently.

Next, the convergence operation of the focus position precision search by the focus position precision search section 60 will be described with reference to FIG. The focus position precise search unit 60 converts the control signals FBAL2 and FOFF2 corresponding to the target position of the focus control obtained by averaging the focus position information FPIS from the multiplier 70 by the averaging processing unit 71, and outputs the focus error detection unit 36. Output to At this time, ideally, if the target position of the focus control is changed by the focus position information FPIS so that the reproduction state obtained by one focus position fine search becomes optimal, the optimum focus position can always be obtained. Is preferred. If this is expressed by a mathematical expression, it becomes as shown in Expression 6.

Focus position information FPIS × K = Target position change amount (Equation 6) Here, K is a constant (hereinafter referred to as “correction gain constant”) relating the shift amount from the optimal focus position and the change amount of the control target position. "). If the target position of the focus control is changed based on Equation 6, when the correction gain constant K = 1, the focus position can be ideally set to the optimum position by one change when the correction gain constant K = 1.

However, the detection sensitivity of the envelope signal and the jitter signal which change in response to the disturbance signal from the disturbance signal generation unit 25 during the precise focus position search varies, so in this embodiment, the focus position information FPIS and the focus control The correction gain constant K relating to the target value is set to be smaller than 1, and the search of the focus position and the update of the target value of the focus control are repeated a predetermined number of times, so that the focus position becomes the optimum position of the focus control. A convergence operation is performed. Here, if the value of the correction gain constant K when the focus position precise search is caused to converge in the present embodiment is preferably set to 0.7 so that the focus position precise search is converged four times, For example, even if the deviation from the initial optimum focus position is 1 μm, the optimum focus position can be searched with an accuracy of ± 0.05 μm or less.

As described above, the focus position precise search section 6
0 obtains focus position information FPIS of only the data area in which the focus position information FPIS of the address area is discarded separately from the land track and the groove track, and determines that the focus position according to the track position of each of the land track and the groove track is optimal. A new focus target position.

Next, the jitter detector 62 will be described with reference to FIGS. 20, 21 and 22. FIG. 20 is a block diagram showing a detailed configuration of the jitter detector 62. The binarization circuit 6201 receives the reproduction signal RF from the signal processing unit 40, and outputs an RF pulse signal PRF binarized with a predetermined threshold. The phase comparison circuit 6202 detects a phase shift between the RF pulse signal PRF and the clock signal CLK output from the VCO (voltage controlled oscillator) 6205. Specifically, a pulse having a pulse width corresponding to the phase shift is output from the output terminals UP and DN depending on whether the phase of the RF pulse signal PRF is ahead or behind the phase of the clock signal CLK. . Differential circuit 620
3 calculates the difference between the pulse signals UP and DN output from the phase comparison circuit 6202 and outputs the difference to the integration circuit 6204. Integrating circuit 6204 integrates the output signal of differential circuit 6203 and outputs the result to VCO 6205. VCO6205
Outputs a clock signal CLK having a frequency corresponding to the output of the integration circuit 6204 to the phase comparison circuit 6202. The addition circuit 6206 calculates the sum of the pulse signals UP and DN output from the phase comparison circuit 6202, and
(Low-pass filter) 6207. LPF62
07 outputs a low frequency component of the output signal from the addition circuit 6206 as the pulse width variation signal PD. The pulse width variation signal PD generated in this manner represents the jitter between the RF pulse signal PRF and the clock signal CLK.

FIG. 21 is a diagram showing the timing of the RF pulse signal PRF, the clock signal CLK, and the pulse signals UP and DN output from the phase comparison circuit in the jitter detector 62. The relationship between the clock signal CLK output from the VCO 6205 and the RF pulse signal PRF is, for example, EFM
In the case of (eight to fourteen modulation) or the like, the pulse of the RF pulse signal PRF having the shortest pulse width is actually added to the clock signal CLK output from the VCO 6205.
In general, the relationship is such that three pulses enter. In this figure, it is assumed for simplicity that the pulse width of the RF pulse signal PRF is equal to the pulse width of the clock signal CLK.

Phase comparison circuit 6202, differential circuit 620
3. The integration circuit 6204 and the VCO 6205 are connected to the PLL (ph
ase locked loop). First, the phase comparison circuit 6202 generates the RF pulse signal PRF and the clock signal CL.
Pulse signals UP and DN corresponding to the phase difference between K and K are output as shown in FIG. That is, when the RF pulse signal PRF is ahead of the clock signal CLK at the rising edge and the falling edge,
A pulse signal UP having a width corresponding to the advance is output (see A in FIG. 21). On the other hand, if it is late, a pulse signal DN having a width corresponding to the delay is output (see B in FIG. 21). The phase lead / lag is determined by the differential circuit 6203.
The pulse signal becomes a positive / negative pulse signal.
04 results in a signal that is cumulatively added. VCO620
5 generates a clock signal CLK having a frequency corresponding to the voltage of the added signal, and feeds it back to the phase comparison circuit 6202. As a result, the clock signal CLK becomes
The RF pulse signal PRF is controlled such that the average of the phase difference becomes zero.

If there is no fluctuation in the pulse width, as a result of the feedback, the pulse signals UP and DN have no pulse for the phase difference (ie, remain at zero level). Here, it is assumed that the pulse width of the RF pulse signal PRF is smaller than that of the clock signal CLK (see C in FIG. 21). At this time, the pulse signal DN is generated at the rising edge of the clock signal CLK, and the RF pulse signal P
A pulse signal UP is generated at the falling edge of RF. Conversely, the RF pulse signal PRF is the clock signal C
It is assumed that the pulse width is wider than LK (see D in FIG. 21). At this time, the pulse signal UP is generated at the rising edge of the RF pulse signal PRF, and the clock signal C
A pulse signal DN is generated at the falling edge of LK.

As described above, the frequency and phase of the clock signal CLK are controlled by the PLL so that the average of the phase difference between the inputs U and V of the phase comparison circuit 6202 becomes zero. Therefore, when the pulse width of the RF pulse signal PRF changes, pulses having the same width are output as the pulse signals UP and DN. As a result, the addition circuit 620
6 outputs only the pulse width fluctuation component. LPF62
07 outputs a signal converted into a DC voltage as a pulse width fluctuation signal PD by smoothing the fluctuation component of the pulse width. Thus, the jitter detection unit 62
The pulse width fluctuation detection signal PD is used as the reproduction signal RF in the data area.
Is output as the jitter.

FIG. 22 is a block diagram showing a detailed configuration of phase comparison circuit 6202 shown in FIG. As shown in the figure, the rising edge of the RF pulse signal PRF is detected by the mono-multi 6202A. The falling edge of the RF pulse signal PRF is supplied to the inverting circuit 6202.
A rising edge is generated by C, and the rising edge is detected by the mono multi 6202B. The output of each of the mono-multis 6202A and 6202B is input to an OR circuit 6202D, and the OR circuit 6202D sends the output to the CK input of the flip-flop 6202E.
VCO6 is input to the CK input of the flip-flop 6202F.
The clock signal CLK from 205 is input. The pulse signal UP from the flip-flop 6202E and the pulse signal DN from the flip-flop 6202F are NAN.
The input to the D circuit 6202G and the NAND circuit 62
The output signal of 02G is input to the reset (R) terminal of the flip-flop 6202E and the reset (R) terminal of the flip-flop 6202F. Flip-flop 6
The D input of 202E and the D input of flip-flop 6202F are connected to power supply voltage Vcc (for example, + 5V). The phase comparison circuit 6202 thus configured is
Edge signal and clock signal C from OR circuit 6202D
The operation is such that the flip-prop is set at the earlier signal edge of the LK edges and reset at the later signal edge.

The configuration of the phase comparison circuit 6202 is different from the configuration shown in FIG.
N circuits with differential and summed outputs, ie, (U
A circuit having (P−DN) and (UP + DN) as output terminals may be used. (UP + DN) only,
For example, it can be directly realized by exclusive OR (exclusive OR). However, in order to obtain (UP-DN) and (UP + DN) with a relatively simple configuration, a circuit that can independently output the pulse signals UP and DN is preferable. The internal configuration of the phase comparison circuit 6202 is as follows:
It is only necessary to have the above-mentioned functions, and it can be realized by another circuit configuration.

The focus position precision search section 60 thus configured is connected to the disturbance signal generation section 25 via the addition section 24.
When the disturbance signal from is applied to the focus control system,
A focus target position is obtained from the jitter and envelope of the reproduction signal RF and the focus error signal FES. Control signals FBAL2, FB for changing the control target position of the focus servo based on the obtained focus target position
OFF2 is output to the focus error detection unit 36. The focus error detection unit 36 outputs the focus error signal FES by changing the focus balance and the focus offset based on the control signals FBAL2 and FOFF2 from the focus position precise search unit 60, and is output from the signal processing unit 40. The zero level of the focus error based on the focus signals VFS1 and VFS2, that is, the control target position of the focus servo is set.

Regarding the setting of the control target position, as described above in the description of the convergence operation of the focus position precise search, the correction gain constant relating the deviation amount from the optimum focus position and the change amount of the control target position is: Assuming that the gain for completely correcting the deviation from the optimum focus position in one correction operation is 1, the detection sensitivity of the envelope signal and the jitter signal of the reproduced signal that changes in response to the disturbance signal from the disturbance signal generator 25 is changed. The value is set to a value (0.7) smaller than 1 in consideration of variation. Then, the control signals FBAL2, FBAL corresponding to the average value obtained by averaging the focus position information FPIS in 24 cycles of the disturbance signal
If the correction of the focus position based on OFF2 is made one time, it is preferable to repeat the correction operation about four times to obtain a focus position at which the amplitude or jitter of the reproduction signal is optimized, that is, a deviation from the optimum focus position by a predetermined value. (For example, ± 0.05 μm in terms of focus position)
It can be: That is, by the four correction operations, it is possible to converge to the optimum focus position with an accuracy of convergence error ± 0.05 μm or less.

Next, the significance of the fact that the focus position precise search section 60 and the focus control section 26 perform processing based on the gate signal IDGATE from the address signal detection section 31 will be described. The SS-L / GFMT optical disc 1 has an address area between data sectors (see FIG. 4A). Further, as shown in the figure, a switching point between the land and the groove exists after the address area for each round of the optical disc 1. Then, as shown in the figure, the physical structure of the data area is different from the physical structure of the address area. As a result, the state of the light beam reflected from the optical disk 1 incident on the detectors 4 and 5 for detecting the focus error signal FES and the broadband tracking error signal RFTE differs between the data area and the address area. In this case, both the focus error signal FES and the broadband tracking error signal RFTE cause an offset. That is,
In the address area, both the focus position and the tracking position detected by the focus error signal FES and the broadband tracking error signal RFTE include an error.

Therefore, the focus servo for controlling the light beam irradiated on the optical disk 1 to always be in a predetermined convergence state and the tracking servo for controlling the light beam to follow the track on the optical disk 1 are operated. In this state, when the light beam spot enters the address area from the data area, disturbance occurs in both the focus servo and the tracking servo. In order to prevent this disturbance, it is necessary to prevent the focus servo and the tracking servo from following when the light beam passes through the address area. Therefore, each servo holds the servo in the address area based on the gate signal IDGATE (as shown in FIG. 6D detected by the address signal detection unit 31).

As described above, in the SS-L / GFMT optical disk 1, a single spiral is performed while the track that follows is alternately switched from a land track to a groove track or from a groove track to a land track every rotation of the optical disk 1. Recording / reproducing operation is realized. Since the tracking polarity is reversed between the land track and the groove track, it is necessary to switch the polarity. The signal used for switching the tracking polarity and following the track is an L / G switching signal LGS as shown in FIG.

In the focus position precise search in this embodiment, focus control and tracking control operate, a still jump is performed every rotation of the optical disk 1, and the light beam spot always follows the groove track. Performs a focus position precision search of the track, moves to the next land track after the groove track focus position precision search is completed, and performs a land track focus position precision search with the light beam spot always following the land track I have to do that. The focus position information FPIS for calculating the deviation of the current focus position from the optimal focus position uses the envelope and jitter of the reproduction signal. Need to be done in the area where the

Next, the relationship between the surface shake component appearing as the residual of the focus servo in the focus error signal FES, the disturbance signal from the disturbance signal generator 25, and the data sector will be described with reference to FIGS. 23 (a) to 23 (c). explain. FIG.
(A) is a waveform diagram of a surface deflection component appearing as a focus servo residual in the focus error signal FES per disk rotation. FIG. 23B shows a waveform of the disturbance signal output from the disturbance signal generator 25. FIG.
(C) is a schematic diagram of one revolution of the disc, that is, a data sector of one track (for example, the inner circumference side of the optical disc 1).

As shown in FIG. 23 (a), the surface shake component is a residual of a focus servo in synchronization with the rotation of the optical disk 1, and here, as a sinusoidal signal that changes by two cycles with one rotation of the optical disk, the focus is reduced. Error signal FES
Appears in Then, as shown in FIG. 23C, one rotation of the optical disk, that is, the number of sectors in one track is, for example, 17 sectors from data sector 0 (DS0) to data sector 16 (DS16) at the innermost circumference. Here, the rotation frequency of the optical disk 1 is 39.78 Hz at the innermost circumference of the optical disk 1, and since there are 17 data sectors in one rotation of the optical disk 1, the rotation frequency of the optical disk 1 includes the address area.
The frequency of the data sector is 676 Hz.

In the focus position precision search of this embodiment,
The focus position information FPIS of the address area is discarded based on the gate signal (gate signal IDGATE) of the address area, and the focus position information FP is stored only in the data area.
Get IS. If the focus position information FPIS is obtained only from the data area, the focus position information FPIS is obtained intermittently. Therefore, the disturbance signal applied from the disturbance signal generation unit 25 to the focus control system when the focus position precision search unit 60 performs the focus position precision search preferably includes one or more periods in the data area of one data sector. Is required.
That is, by ensuring that the disturbance signal is always included in one cycle in the data area of one data sector, the focus position information FPIS corresponding to the disturbance can be obtained in one data sector unit. Therefore, the rotation speed of the optical disc 1,
In this embodiment, in consideration of conditions such as that the number of data sectors per rotation and that a disturbance signal is included in the data area of one data sector for one cycle or more, in this embodiment, the disturbance applied to the focus control system at the time of precise focus position search is performed. Set the signal frequency to 1
It is set to kHz.

Next, FIG. 24, FIG. 25, FIG. 26, and FIG.
The principle of searching for the optimum focus position will be described with reference to FIG. FIG. 24 shows the focus position and the envelope detector 61.
FIG. 6 is a diagram showing a relationship between the envelope of the reproduction signal RF detected at step (a) and a relationship between the disturbance signal at each focus position and the envelope of the reproduction signal RF. With the focus control activated, the disturbance signal generator 25
When a disturbance signal is applied to the focus control system from the following, if the direction in which the objective lens 3 approaches the optical disc 1 is defined as the positive direction, and the direction in which the objective lens 3 is separated from the optical disk 1 is defined as the negative direction,
When the focus position is changed in the positive direction, the reproduction signal RF
The envelope of the reproduction signal RF increases when the focus position is changed in the negative direction. On the other hand, when a disturbance signal is applied with reference to the point B to change the focus position in the positive direction, the envelope of the reproduction signal RF increases, and when the focus position changes in the negative direction, the envelope of the reproduction signal RF decreases. Become.
Further, when a disturbance signal is applied with reference to the point C, that is, the maximum point of the envelope of the reproduction signal RF, the envelope of the reproduction signal RF changes so as to become smaller according to the disturbance signal regardless of whether the focus position is changed to positive or negative. I do.

As described above, when the disturbance signal from the disturbance signal generator 25 is applied to the focus control system, the focus servo changes the focus position in response to the applied disturbance signal, so that the envelope of the reproduction signal RF also changes. .
Therefore, the disturbance component of the focus error signal FES when the disturbance signal from the disturbance signal generator 25 is applied to the focus control system via the adder 24 and the envelope of the reproduction signal RF are multiplied by the amount of defocus with respect to the focus position. And focus position information FPIS indicating the deviation between the focus position and the focus optimum position.

Here, FIG. 24 and FIG. 25 show the principle that deviation from the optimum focus position is obtained from the disturbance component of the focus error signal and the envelope of the reproduction signal RF.
This will be described with reference to (a) to (c). FIG.
(C) is a disturbance signal, points A and B in FIG.
24 shows the envelope of the reproduced signal RF at each point C and the waveform obtained by multiplying the disturbance signal by the envelope of the reproduced signal RF at each of points A, B and C in FIG. For convenience of explanation, the disturbance signal and the reproduced signal R
It is assumed that the waveform obtained by multiplying the envelope of F and the disturbance signal is obtained continuously. At point A in FIG.
When a continuous sinusoidal disturbance signal as shown in (a) is applied to the focus control system, the envelope waveform of the reproduction signal RF has a phase different from that of the disturbance signal as shown in the waveform at point A in FIG. It becomes a sinusoidal waveform shifted by 180 degrees. Then, the waveform obtained by multiplying the envelope of the reproduction signal RF by the disturbance signal becomes a waveform that changes on the negative side from the zero level as shown in the waveform at point A in FIG. That is, the focus position information FPIS obtained by multiplying the envelope of the reproduction signal RF by the disturbance signal (hereinafter referred to as “focus position information FPIS by envelope”) has a waveform that always changes to the negative side with respect to the disturbance signal. Become. If the waveform of the point A shown in FIG. 25C is smoothed by a low-pass filter or the like, it is possible to obtain the shift amount and the polarity from the optimal focus position at the point A in FIG.

At the point B in FIG. 24, when a sinusoidal disturbance signal is similarly applied to the focus control system, the reproduction signal R
The envelope waveform of F becomes a sinusoidal waveform having the same phase as that of the disturbance signal, as shown in the waveform at point B in FIG. Then, the waveform obtained by multiplying the envelope of the reproduction signal RF by the disturbance signal is a waveform that changes on the positive side from the zero level, as the waveform at the point B shown in FIG. 25C. That is, the focus position information FPI by the envelope
S has a waveform that always changes to the positive side with respect to the disturbance signal. If the waveform at the point B shown in FIG. 25C is smoothed by a low-pass filter or the like, it is possible to obtain the amount of deviation and the polarity from the optimal focus position at the point B in FIG.

At point C in FIG. 24, when a sine-wave-like disturbance signal is applied to the focus control system, the reproduction signal R
The envelope waveform of F is a waveform that is turned to the negative side with respect to the zero level as shown in the waveform at point C in FIG. Then, the waveform obtained by multiplying the envelope of the reproduction signal RF by the disturbance signal is represented by C shown in FIG.
It becomes a sinusoidal waveform that is 180 degrees out of phase with the disturbance signal like a point waveform. In other words, the focus position information FPIS based on the envelope has a waveform that is inverted with respect to the disturbance signal. If the waveform at the point C shown in FIG. 25C is smoothed by a low-pass filter or the like, it is possible to obtain the shift amount and the polarity from the optimal focus position at the point C in FIG.

Next, the relationship between the focus position and the jitter of the reproduction signal RF will be described with reference to FIG. FIG.
Is the focus position and the reproduced signal R from the jitter detector 62.
FIG. 6 is a diagram illustrating a relationship between the jitter of F and the disturbance signal at each focus position and the jitter of the reproduction signal RF. When a disturbance signal is applied from the disturbance signal generator 25 to the focus control system based on the point A while the focus control is operated, the direction in which the objective lens 3 approaches the optical disc 1 is set to the positive direction, and the objective lens 3 is separated from the optical disc 1. If the direction is a negative direction, the jitter of the reproduction signal RF increases when the focus position is changed in the positive direction, and the jitter of the reproduction signal RF decreases when the focus position is changed in the negative direction. When the disturbance position is applied to the reference point B to change the focus position in the positive direction, the jitter of the reproduction signal RF decreases, and when the focus position changes in the negative direction, the jitter of the reproduction signal RF increases. When a disturbance signal is applied based on the point C, that is, the minimum point of the jitter of the reproduction signal RF, the jitter of the reproduction signal RF changes so as to increase regardless of whether the focus position is changed to positive or negative.

As described above, when the disturbance signal from the disturbance signal generator 25 is applied to the focus control system, the focus servo changes the focus position in response to the applied disturbance signal, so that the jitter of the reproduction signal RF also changes. . Therefore, when the disturbance component of the focus error signal FES when the disturbance signal from the disturbance signal generation unit 25 is applied to the focus control system via the addition unit 24 and the jitter of the reproduction signal RF are multiplied, the amount of defocus with respect to the focus position is obtained. The focus position information FPIS indicating the polarity, that is, the shift between the focus position and the optimum focus position can be obtained.

However, the envelope response characteristics of the reproduced signal RF from the envelope detector 61 to the disturbance signal and the jitter response characteristics of the reproduced signal RF from the jitter detector 62 are shown in FIG. 24 and FIG. As is clear from the jitter waveform, the response characteristics are reversed. Therefore, when the focus position precision search is performed based on the focus position information FPIS based on the envelope of the reproduction signal RF from the envelope detection unit 61 and the focus position information FPIS based on the jitter of the reproduction signal RF from the jitter detection unit 62, for example, It is necessary to match the polarity of the envelope with the polarity of the jitter, such as matching the jitter polarity with the polarity of the envelope. In this embodiment, FIG.
As shown in (2), the subtractor 69 converts the envelope signal from the first gain adjuster 66 into the second gain adjuster 6.
The polarity is adjusted by performing a difference operation on the jitter signal from. The procedure for calculating the deviation from the optimal focus position from the disturbance component of the focus error signal and the jitter of the reproduction signal RF can be obtained by the same principle as the principle of detecting the deviation from the optimal focus position using the envelope. The description of the principle of detecting the deviation from the optimum focus position is omitted.

Next, a description will be given, with reference to FIG. 27, of a deviation detection characteristic from the optimum focus position obtained by the focus position precise search section 60. FIG. 27 is a diagram illustrating the relationship between the focus position and the deviation detection value from the optimal focus position. When the focus position is searched by the focus position precise search unit 60, for example, the gain of the second gain adjustment unit 67 is set to zero, and the first gain adjustment unit 66 is appropriately adjusted to obtain only the envelope of the reproduction signal RF. If the shift from the optimum focus position is detected based on the focus position, the shift from the optimum focus position becomes zero as shown by a curve 7120 in FIG. 27 because the envelope of the reproduced signal RF has the maximum focus position (for example, −0.50 μm). When the focus position shifts in the positive direction around the focus position where the envelope becomes maximum, the shift from the optimum focus position increases in the positive direction, and when the focus position shifts in the negative direction, the shift from the optimum focus position shifts. Has a characteristic that increases in the negative direction.

On the other hand, if the gain of the first gain adjustment unit 66 is set to zero and the second gain adjustment unit 67 is appropriately adjusted to detect a deviation from the optimum focus position based only on the jitter of the reproduction signal RF, As shown by a curve 7122 shown in FIG. 27, the deviation from the optimal focus position becomes zero because the jitter is minimized at the focus position (for example, 0 μm).
m). When the focus position shifts in the positive direction to the center of the focus position where the jitter is minimized, the shift from the optimum focus position increases in the positive direction, and when the focus position shifts in the negative direction, the shift from the optimum focus position decreases. The characteristic is such that it increases in the negative direction.

Further, the gain of the first gain adjustment unit 66 is set to an appropriate coefficient, for example, α, and the second gain adjustment unit 67
If the gain is adjusted to be an appropriate coefficient, for example, β, and the sensitivity for detecting the deviation from the optimal focus position due to the envelope is equal to the sensitivity for detecting the deviation from the optimal focus position due to the jitter, then the characteristic for detecting the deviation from the optimal focus position As shown in a curve 7121 shown in FIG. 27, the deviation from the optimal focus position becomes zero because the focus position at which the envelope is maximum and the optimal focus position at which the jitter is minimum (for example,
0.25 μm). The deviation detection characteristic from the optimal focus position in this case is an intermediate characteristic between the deviation detection characteristic from the optimal focus position by the envelope and the deviation detection characteristic from the optimal focus position by the jitter. That is, if the focus position shifts in the positive direction about the center position between the focus position where the envelope is maximum and the focus position where the jitter is minimum, the shift from the optimal focus position increases in the positive direction, and the focus position becomes negative. , The deviation from the optimal focus position increases in the negative direction.

For this reason, the present embodiment employs the curve 7121 that takes into account both the envelope and the jitter of the reproduction signal RF. More specifically, the averaging processing section 71 of the focus position precise search section 60 calculates the shift amount corresponding to the focus position information obtained by the averaging as shown in FIG.
The new focus target positions Ml1 and Ml2 are obtained by shifting the current focus positions (Ml1 and Ml2) by the amount obtained from the curve 7121 shown in FIG. ing.

Next, the relationship between the convergence position error and the effect of the address area when searching for the optimum focus position by the focus position precise search section 60 will be described. In the SS-L / GFMT optical disc 1 according to the present embodiment, an address area exists between sectors. Although the focus position precise search is performed while the focus control and the tracking control are operated, as described above, the correct focus error signal FES and the wideband tracking error signal RFTE cannot be obtained in the address area. Therefore, in both the focus servo and the tracking servo, when the light beam spot passes through the address area, the focus control unit 26 and the tracking control unit 23 move on the optical disc 1 based on the gate signal IDGATE from the address signal detection unit 31. Each output signal is held immediately before the convergently irradiated light beam enters the address area. When the light beam convergently irradiated on the optical disk 1 passes through the address area and enters the data area, the hold is released based on the gate signal IDGATE from the address signal detection unit 31, and the operation of the focus servo and tracking servo is performed. Resume.

In the focus position search, when the search for the optimum focus position is performed using the focus position information FPIS including the envelope and the jitter of the reproduction signal RF acquired in the address area, the search result includes an error from the optimum position. . That is, the convergence error to the optimum focus position increases due to the influence of the address area. Therefore, in this embodiment, a disturbance signal having a frequency such that the disturbance is included in the data area of one data sector for one cycle or more is applied to the focus control system, and the address is determined based on the gate signal IDGATE from the address signal detection unit 31. The focus position information FPIS is detected only in the data area excluding the area. Thus, even for the optical disc 1 having an address area that causes a detection error in the focus position information FPIS, a highly accurate focus optimum position search that is not affected by the address area is realized.

As described above, the focus position precise search section 60 of the embodiment determines the optimum focus position by using the reproduction signal RF.
Is controlled between the maximum of the envelope and the minimum of the jitter of the reproduction signal RF. Therefore, even if the focus position is changed due to the residual error of the focus servo following the deflection of the optical disk 1 after the focus position is adjusted, the margin for defocusing. Is optimized, and good reproduction characteristics can be obtained. In other words, as shown in FIG. 15, when the focus position is adjusted to the minimum jitter position, if the focus position shifts in the positive direction, the jitter margin for defocus decreases. When the focus position is adjusted to the maximum position of the envelope of the reproduction signal RF, if the focus position shifts in the negative direction, the characteristic of the envelope of the reproduction signal RF becomes extremely small with respect to defocus, and as a result, the jitter also decreases. become worse. Therefore, since the focus optimum position is adjusted to an intermediate point between the focus position where the amplitude of the reproduction signal RF is maximum and the focus position where the jitter is minimum, the focus position where the envelope of the reproduction signal RF is maximum and the focus position of the reproduction signal RF are adjusted. When the focus position at which the jitter is minimized is different, good reproduction characteristics can be obtained even when the focus position changes due to the residual error of the focus servo following the disk surface deflection.

Although the focus position precision search section 60 of the present embodiment searched for a focus position intermediate between the focus position where the amplitude of the reproduction signal RF is maximum and the focus position where the jitter of the reproduction signal RF is minimum. , Reproduction signal R
A focus position at which the error rate of F is equal to or less than a predetermined value;
Or a focus position where the amplitude of the reproduction signal RF is maximum,
Alternatively, a focus position where the jitter of the reproduction signal RF is minimized or a focus position where the error rate of the reproduction signal RF is minimized may be searched.

In the focus position precise search of this embodiment, first, the focus position is precisely searched in a state where the light beam spot follows the groove track in a still jump, and then the land track on one track outer periphery is used. The precision search of the focus position was performed in the state of moving and still jumping. However, the procedure of the precision search of the focus position is not limited to this. May be reversed.

That is, with respect to the change of the focus control target position (focus balance value and focus offset value) in the precise search of the focus position according to the present embodiment, a modification of the coarse focus position search (the eight types of search shown in FIG. 13). Method). [Optional function for precise focus position search]
Next, two optional functions in the precise search of the focus position will be described. First, a first optional function of performing a precise search for a focus position by focusing on a specific data area of the optical disc 1, that is, a function of the read gate detection unit 32 will be described.

As described above, the read gate detecting section 32 focuses the gate signal RDGT which becomes “Hi” in the address area on the optical disk 1 and the data sector (read data sector) specified by the drive controller 14 in advance. Output to the position precision search unit 60. In the present embodiment, the drive controller 14 detects a surface shake (AC signal) generated when the optical disc 1 rotates by taking in advance the focus error signal FES and performing A / D conversion, and the change of the AC signal is small. These data sectors are designated as read data sectors so that the gate signal RDGT becomes "Hi" in the data area corresponding to the position.

Then, the focus position precise search unit 60
Is based on such a gate signal RDGT, and focus position information F is applied only to a data area specified in advance.
Acquire the PIS and perform a precise search for the focus position. The significance of operating such a first optional function is as follows. When performing the focus position precise search, the focus control unit 26 irradiates the optical disc 1 by driving the actuator 2 via the addition unit 24 and the focus drive unit 21 based on a signal from the focus error detection unit 36. The control is performed so that the light beam thus obtained always has a predetermined convergence state. However, when the surface deflection of the optical disc 1 increases, the focus error signal F
A control residual of the surface runout component of the optical disc 1 appears in the ES.
Therefore, when the surface deviation of the optical disc 1 is large, the error of the focus position detection increases unless processing such as averaging the influence of the surface deviation by continuously detecting the focus position information FPIS is performed. become. However,
In the optical disk 1 of SS-L / GFMT, since the data area is discontinuous, the focus position information FPIS is also detected discontinuously, and is easily affected by the surface shake component. Therefore, in the first optional function, the focus position information FPIS is detected in a state where the influence of the surface shake of the optical disc 1 is reduced, so that the accuracy of the focus position search is further improved.

FIGS. 28A to 28E are timing charts for explaining the function of the read gate detector 32. FIG. 28A shows the waveform of the surface deflection component of the optical disk 1, and FIG. ) Is a read data sector (hatched data sector) set in the read gate detection unit 32, FIG. 28C is a gate signal RDGT output from the read gate detection unit 32, and FIG. The timer signal TMS output from the time measuring device 7101 of the processing section 71, and FIG. 28E shows the data acquisition timing signal D output from the AND circuit 7109 of the averaging processing section 71.
Indicates GTS. Here, for convenience of description, it is assumed that the disturbance signal from the disturbance signal generation unit 25 is applied synchronously with an AC signal of one cycle per data area of one data sector.

The detection of the focus position information FPIS is most susceptible to the influence of the surface shake component of the optical disc 1 at t (0), t (1), and t shown in FIG.
(2), t (3), and t (4), that is, the vicinity where the change of the control residual of the surface runout component is maximum. Then, as shown in FIG. 28 (b), the read gate detection unit 32 determines the position of the data sector excluding the data sector located at the position where the variation of the surface runout component is small, that is, at the timing when the polarity of the surface runout component is inverted. Is designated as a read data sector. In such a designation, the read gate detection unit 32, based on an instruction from the drive controller 14, sets the gate signal RDG as shown in FIG.
T, that is, a signal that becomes “Hi” only in the address area and the read data sector is output.

The signal RDGT is supplied to the averaging processing section 71 of the focus position precise search section 60, and more specifically, to the signal RDGT shown in FIG.
7 is input to an AND circuit 7109 shown in FIG. AND
A time measuring device 7101 is connected to the other input terminal of the circuit 7109.
Is input. As shown in FIG. 18, the time measuring device 7101 starts time measurement after a predetermined wait time (200 μs) from the rising edge of the gate signal IDGATE from the address signal detecting section 31, and the time corresponding to one period of the disturbance ( Here, a time corresponding to one data sector is measured, and a timer signal TMS indicating the time during the measurement is output. Such a timer signal TMS is as shown in FIG.

The gate signal RDGT and the timer signal TMS are ANDed in the AND circuit 7109, and the result is obtained as the data acquisition timing signal DGT.
The signal is output to the first averaging circuit 7102 and the third averaging circuit 7104 as S. As shown in FIG. 28 (e), the data acquisition timing signal DGTS includes a pulse train that becomes “Hi” for one cycle of the disturbance signal only for the data area at the timing where the amount of change in the surface shake component is small. Become. The first averaging circuit 7102 and the third averaging circuit 7104 average the focus position information FPIS from the multiplier 70 while the data acquisition timing signal DGTS is “Hi”. As a result, stable data can be obtained only in the area other than the address area and in the area specified as the read data sector, that is, the address area that causes an error in the focus position information FPIS and the area in which the amount of change in the surface shake component is large. Focus position information FP for only the area
The IS is obtained, averaged, and used for the precise search of the focus position.

As described above, the first optional function realizes a precise search of a focus position with high accuracy while avoiding control disturbance due to a surface shake component. Next, a second optional function of performing a precise search of a focus position based on a focus error signal FESS obtained by directly removing a surface shake component from the focus error signal FES, that is, a function of the surface shake component removal unit 35 Will be described.

As described above, the surface vibration component removing unit 35 removes the surface vibration component of the optical disc 1 included in the focus error signal FES from the focus error detection unit 36, and removes the other frequency components (disturbance signal generation unit). The filter passes a 1 kHz signal or the like applied from the filter 25 and outputs the passed signal to the switch 39. FIG.
5 is a block diagram showing a detailed configuration of a surface shake component removing unit 35. FIG. The plane runout component removing unit 35 includes a bandpass filter 3501 that passes only a frequency band of a plane runout component that is known in advance, and a subtractor 3502. Subtractor 3
A focus error signal FES is input to a plus terminal of the bandpass filter 502, and a band-pass filter 3501 is input to a minus terminal of the bandpass filter 3501.
Is input. Therefore,
An output signal from the subtractor 3502 is a signal obtained by removing only the surface shake component from the focus error signal FES.

When the second optional function is operated, the switch 39 inputs a signal from the surface shake component removing unit 35 to the focus position precise search unit 60 according to an instruction from the drive controller 14. Switch to Therefore, the focus position precise search unit 60
Performs a precise search for the focus position based on the signal output from the surface shake component removing unit 35.

As a result, the occurrence of a detection error of the focus position information FPIS due to unnecessary disturbance such as surface deflection of the optical disk 1 is reduced. That is, in the focus position precise search unit 60, the focus error signal FESS in which the surface vibration component of the optical disc 1 has been removed from the focus error signal FES by the surface vibration component removal unit 35 and the envelope of the reproduction signal RF, and the like. The focus position information FPIS is obtained from the focus error signal FESS and the jitter of the reproduction signal RF, and the precise search of the focus position is performed based on such focus position information FPIS. Is achieved.

In addition, the surface runout component removing unit 3 in the present embodiment.
Reference numeral 5 denotes a filter for removing a surface runout component generated in the rotating optical disk 1. For example, the filter 5 may have a characteristic for removing unnecessary low-frequency signal components such as a power supply frequency. [Re-searching of focus position] Next, the timing at which the optical disc drive apparatus 100 starts searching the focus position again (coarse search and precise search) will be described separately for recording and reproduction. That is, in the optical disc drive apparatus 100, typically, at the time of startup, that is, after the rotation of the optical disc 1 is started and reaches a certain number of rotations, a rough search of the focus position and a subsequent precise search are executed. . However, these explorations are not limited to such cases. That is, the drive controller 14
In accordance with a built-in control program, even when a state where the following predetermined conditions are satisfied during recording and reproduction is detected, the focus position coarse search unit 50 and the focus position fine search unit 60 perform a focus position search (coarse). Exploration and precision exploration). Here, the conditions and operations will be described.

First, a description will be given of the conditions for starting the re-search for the focus position during recording. When recording information on the optical disk 1, the drive controller 14 controls the laser power driving unit 41 and the like so that the laser power is modulated according to the signal pattern to be recorded on the optical disk 1 and the information is recorded on the optical disk 1. I do. After the recording, a verify operation for verifying whether the desired recording has been performed is performed. The verify operation means that the optical disk 1
Immediately after recording the information above, it is reproduced and it is determined whether or not the information has been correctly recorded. As a result of the verify operation, desired recording characteristics (bit error rate BER)
Etc.) are not obtained, the recording power is increased and the recording and verify operation are performed again. In this manner, the drive controller 14 controls to increase the recording power until desired recording characteristics are obtained. However, there is an upper limit of the recording power at which the reproduction characteristics are not improved even if the recording power is increased. This upper limit of the recording power is a value determined from the power margin in recording and erasing, the performance of the semiconductor laser, and the like, even if the recording power is excessively increased so that the next erasing cannot be performed completely.

For these reasons, the upper limit of the recording power is set in the laser power drive section 41. Further, when desired recording characteristics cannot be obtained even when the recording power is increased, a case other than the recording power may be considered. Therefore, the condition for starting the re-exploration of the focus position at the time of recording is that the recording power has reached the upper limit. As a result, even if the bit error rate BER is not improved even when the recording power is increased as described above, a recording characteristic in which the bit error rate BER becomes equal to or less than a predetermined value is obtained by re-exploring the focus position. be able to.

FIG. 30 is a flowchart showing a specific procedure of such a re-search for the focus position at the time of recording. When recording information on the optical disc 1, the drive controller 14 sends a power setting value for recording and a recording signal pattern to the modulation unit 42 (step S40).
The modulation unit 42 receives the recording power set value and the recording signal pattern from the drive controller 14 and sends a signal for modulating the laser power to the laser power driving unit 41. The laser power driving unit 41 The information is recorded on the optical disc 1 by modulating the laser power on the basis of (step S41). As the normal recording power set value, a recording power obtained at the time of assembling the apparatus (hereinafter, referred to as a “recording power process value”) is used. The range of the recording power is 11 mW to 14 mW, and the normal recording power is about 12 mW. Therefore, here, when information is recorded on the optical disc 1, the drive controller 14
Sets an optical disc 1 by setting a process value of the recording power.
To record information.

After the end of the recording operation, the drive controller 14 performs verification for verifying that the recording has been correctly performed (step S42). Drive controller 14
Determines whether the verification has been completed correctly (step S43). If the verification has not been completed correctly, the recording power is increased in a predetermined unit (for example, 0.5 mW) and recording is performed again (step S44). ). However, before recording, the upper limit of the recording power is compared with the updated recording power (step S45), and if the recording power does not exceed the upper limit of the recording power, the recording operation is performed (step S41).
Verify is performed (step S42).

If the verification does not end correctly (step S43), the above operations (steps S44, S4)
5, S41 to S43) are repeated. As described above, the recording (step S41), the verification (step S42), and the increase of the recording power (steps S44 and S45) are repeated. As a result, when the recording power exceeds the upper limit (step S45), the drive controller 14 Focus position coarse search unit 50 and focus position precision search unit 60
, The focus position is re-searched (steps S46 and S47). When the re-exploration is completed, the drive controller 14 sets the process value of the recording power again (step S40), and performs the above-described recording operation and bay verify (steps S41 and S42). Then, when the verification is correctly completed (step S4)
3) The recording operation ends normally (step S49).
On the other hand, if the verification has not been properly completed (step S43), the recording power is increased (steps S44 and S44).
45), recording (step S41) and verify (step S42) are repeated.

If the recording power exceeds the upper limit (step S45) and the recording power exceeds the upper limit two or more times in succession (step S46), the recording operation does not end normally. (Step S4)
8). If the recording operation has not been completed normally, processing such as restarting the apparatus is performed. Note that the drive controller 14 stores the address of the test area used for searching the focus position at the time of startup, and refers to the address when re-searching, so that the test area used at the time of startup can be used. Track) and the focus position is re-explored.

Next, the conditions for starting the re-search for the focus position during reproduction will be described. While reproducing information already recorded on the optical disc 1, the bit error rate BE
Due to the increase in R, information recorded on the optical disc 1 may not be reproduced. This occurs when the focus position is shifted due to the temperature characteristics of the optical head even though the focus position has been searched once. When the bit error rate BER increases, the optical disk 1 reproducing apparatus retries reproduction to reproduce desired recording information. This retry of the reproduction is continuously repeated up to a predetermined number of times until the reproduction can be correctly performed. However, when the bit error rate BER is greatly increased, the reproduction may not be performed correctly even if the reproduction retry is repeated a predetermined number of times.

Therefore, another condition for starting the re-search for the focus position at the time of reproduction is that the reproduction retries occur continuously a predetermined number of times or more. Thereby, even if the reproduction is not performed even if the reproduction retry is repeated a predetermined number of times, the re-search for the focus position may enable the reproduction within the predetermined number of times at the next reproduction.

FIG. 31 is a flowchart showing a specific procedure for re-searching the focus position during such reproduction. When reproducing the signal from the optical disk 1, the drive controller 14 receives the RF pulse signal PRF from the demodulation unit 47 (Step S60), and performs a reproduction error check for every 16 sectors (Step S61). As a result of the reproduction error check, if the reproduction is not normally completed (step S62), the retry of the reproduction operation is repeated (steps S63, S60 to S62). Then, when the retry of the reproducing operation exceeds 50 times (step S63),
By instructing the focus position coarse search unit 50 and the focus position precision search unit 60, the focus position is re-searched (steps S64 and S65).

When the re-search is completed, the drive controller 14 performs the above-described reproducing operation (step S6).
0, S61). If the reproduction error check ends correctly (step S62), the reproduction operation ends normally (step S67). On the other hand, when the reproduction error check is not correctly completed (step S62), the reproduction retry is repeated (step S63, S60 to S62).

If the number of retries exceeds 50 (step S63), and if the number of consecutive reproduction retries exceeds 50 (step S64), the reproduction operation does not end normally. (Step S
66). As a process when the reproduction operation is not normally completed, a process such as restarting the apparatus is performed. In addition, the drive controller 14 stores the address of the test area used when searching for the focus position at the time of startup, moves to the address of the test area used at the time of startup, and performs the search again for the focus position.

By such a re-search for the focus position, the focus position deviates from the optimum position during the operation of the optical disk drive device even though the focus position has been searched once at the time of startup, and the recording operation or the reproducing operation is performed. Even if the state is not completed normally, the state returns to the state where normal recording operation and reproduction operation can be performed again.

Although the optical disk drive 100 according to the present invention has been described based on the embodiments, it is needless to say that the present invention is not limited to the embodiments. That is, the optical disc drive apparatus 100 of the present embodiment has two types of modes (coarse search and precise search) as a focus position search method, and further has two types of optional functions (lead gate) for precision search. Detection unit 32
However, the present invention may not have all these modes and optional functions.

For example, a simple optical disk drive having no function of performing a precise search for a focus position,
An optical disk drive device that executes only a search with a coarse focus position may be used. FIG. 32 is a block diagram showing only the components related to the focus position search of the optical disc drive device 110 that executes only the coarse position search. As can be seen from this figure, the optical disc drive device 110 includes a component 50 for performing a coarse focus position search, and a component 60 for performing a fine focus position search.
Do not have

Further, it is also possible to provide a simple optical disk drive device having no function of performing a coarse search of a focus position, that is, an optical disk drive device that executes only a fine search of a focus position. FIG. 33 shows an optical disc drive device 1 that executes only a precise search for a focus position.
20 is a block diagram showing only components related to a focus position search of No. 20; FIG. As can be seen from this figure, the optical disc drive device 120 has components 25, 600, etc., for performing a search for a precise focus position, and a component 50, etc. for performing a search for a coarse focus position. , Components 32 and 3 relating to optional functions
Does not have 5 magnitude. FIG. 34 shows the focus position precise search unit 60 of the optical disk drive device 120 shown in FIG.
17 is a block diagram illustrating a detailed configuration of the averaging processing unit 710. As can be seen from comparison with the focus position precise search unit 60 illustrated in FIG. 16, the gate signal RDGT is not input to the averaging processing unit 710. FIG. 35 is a block diagram showing a detailed configuration of averaging processing section 710 shown in FIG.
As can be seen by comparing with the averaging processing section 71 shown in FIG. 7, there is no component (AND circuit 7109 in FIG. 17) related to the gate signal RDGT.

An optical disk drive device having only the above-described first optional function (the read gate detection unit 32) and executing only a precise search for a focus position can be provided. FIG. 36 is a block diagram showing only components related to the focus position search of the optical disc drive device 130 that performs only the precise search for the focus position provided with the first optional function (the read gate detection unit 32). As can be seen from the figure, the optical disk drive device 130 includes components 25, 60, etc., for executing a precise focus position search, and a read gate detection unit 32.
, But does not include the component 50 for performing the coarse focus position search and the component 35 for the second optional function.

Further, an optical disk drive device having only the above-mentioned second optional function (surface shake component removing unit 35) and executing only a precise search for a focus position can be provided. FIG. 37 is a block diagram showing only components related to the focus position search of the optical disc drive device 140 that performs only the precise search for the focus position provided with the second optional function (the surface shake component removing unit 35). As can be seen from this figure, the optical disc drive device 140 has components 25, 60, etc. for performing a precise focus position search and a surface shake component removing unit 35, but performs a coarse focus position search. , And the component 32 relating to the first optional function.

In the coarse and fine search of the focus position in the present embodiment, focus control and tracking control are operated, and a still jump is performed for each rotation of the optical disk 1, so that the light beam spot is always changed to the groove track. (Or a land track), a coarse search and a fine search for a focus position with respect to a groove track (or a land track) were performed. However, the present invention is not limited to such a method using a still jump. Absent. For example, without causing a still jump, the focus position coarse search unit 50 (or the focus position precision search unit 60) uses the L / L in a state where the light beam spot simply follows the track continuously along the spiral.
The bit error rate BER (or focus position information FPIS) in each track is continuously measured while alternately switching the land track and the groove track every rotation based on the G switching signal LGS, and the focus control target for each track is determined. The position (the focus balance value and the focus offset value) may be constantly updated. This makes it possible to continuously repeat the coarse search (or the fine search) of the focus position without performing complicated tracking control such as a still jump.

[0206]

According to the present invention, there is provided a focus position adjusting apparatus for an optical disk having tracks of first and second shapes, and an optical disk drive having such a focus position adjusting apparatus. A focus error detecting means for detecting a convergence state of the light beam applied to the optical disk and outputting a focus error signal indicating the convergence state; and the convergence state being a predetermined state based on the focus error signal. Focus control means for changing a focus position of the light beam, reproduction state detection means for detecting a reproduction state of the optical disk based on a reproduction signal when reading information recorded on the optical disk, and a light beam spot. Which of the first and second shape tracks of the optical disc is Track detecting means for outputting a track identification signal indicating the track, and a focus position searching means for changing a focus position of the light beam so that the reproduction state becomes better, the focus position searching means comprises: Based on the reproduction state when the track identification signal indicates a track of the first shape, a first update focus position at which the reproduction state becomes better is determined, and the track identification signal has a second shape. A focus position updating unit that determines a second updated focus position at which the reproduction state becomes better based on the reproduction state when indicating a track; and when the track identification signal indicates a track having a first shape, Change the focus error signal so that the focus position becomes the first update focus position. And a focus error signal changing unit that changes the focus error signal so that the focus position becomes the second updated focus position when the track identification signal indicates a track of the second shape. The control unit changes the focus position of the light beam based on the focus error signal changed by the focus error signal changing unit.

According to this configuration, when the light beam spot is located on the track of the first shape and when it is located on the track of the second shape, it is distinguished, and independently, the reproduction state is improved. The focus positions for the new land track and the groove track are searched. And
In order for these new focus positions to become control targets,
The focus position is controlled separately for the land track and the groove track. Therefore, the conventional problem that the reproduction state is good on one of the land track and the groove track but not good on the other is avoided,
The first object is achieved.

Here, the reproduction state detection means may detect the reproduction state in consideration of the focus error signal in addition to the reproduction signal. The reproduction state detection means has an envelope detection unit that detects an envelope of the reproduction signal, and a jitter detection unit that detects jitter of the reproduction signal. The reproduction state may be detected based on the reproduction state.

According to this configuration, the reproduction information includes both the information of the envelope and the jitter of the reproduction signal, and the focus position search is performed by the focus position search means based on such a reproduction state. Focus position adjustment is realized. In other words, the problem of an increase in reproduction errors when the focus position is controlled by focusing only on the amplitude of the reproduction signal as in the related art or when the focus position is controlled by focusing only on the jitter of the reproduction signal is avoided. The second object is achieved.

[0210] The focus position adjusting device further includes an area detecting means for detecting whether the light beam spot is located in the data area or the address area of the optical disk, and wherein the reproduction state detecting means comprises the area detecting means. A part of the reproduction signal may be extracted based on the detection of the reproduction signal, and the reproduction state may be detected from the part of the extracted reproduction signal. The reproduction state detection means may detect the reproduction state only for the reproduction signal when the area detection means detects that the light beam spot is located in the data area.

According to this configuration, since the focus position is adjusted while excluding the address area of the optical disk, even if the optical disk has pits formed differently in the address area and the data area, The disturbance of the focus position adjustment based on such a difference is avoided, and the third object is realized. Further, the focus position adjusting device further includes a surface shake component removing filter for removing a frequency component indicating a surface shake of the optical disc from the focus error signal, and the reproduction state detecting means includes a focus remover that removes the frequency component. The reproduction state may be detected from an error signal and the reproduction signal.
Further, the focus position adjusting device further includes a sector specifying unit for specifying a sector at a position where the surface deflection acceleration of the optical disk is reduced, and the reproduction state detecting unit includes the reproduction signal obtained only from the specified sector. And the reproduction state may be detected from the focus error signal.

According to this configuration, a reproduction state in which the surface vibration component of the optical disk has been removed is obtained, and the focus position is adjusted based on such a reproduction state, so that it is hardly affected by the surface vibration of the optical disk. A highly accurate focus position adjustment is realized, and the fourth object is achieved. Further, the focus position updating unit determines whether the reproduction state becomes better when the focus position is shifted by a predetermined moving amount, and thereby determines whether the first update focus position and the second update focus are good. The position may be determined.

According to this configuration, the focus position searching means forcibly shifts the focus position by a predetermined fixed amount of movement, and determines a new target focus position from the reproduction state obtained as a result. Even if precise adjustment becomes impossible due to a large deviation of the focus position, the focus position can be restored so that the focus position can be adjusted again. Therefore, the fifth object is achieved.

[0214] The focus position adjusting device further includes recording means for recording test data in a test area provided in at least one of a lead-in area and a lead-out area of the optical disc. The reproduction state may be detected based on a reproduction signal when the test data is read. According to this configuration, the test data is recorded in an area that is not a target of write protection, and the focus position is adjusted using the test data. The search for the focus position can be executed even for the optical disc that has been set. Therefore, the sixth object is achieved.

Further, the focus position adjusting device further includes a defect state determining means for determining whether or not the reproduction state is a defect state exceeding a predetermined allowable range, and a method for determining whether the reproduction state is the defect state. And re-search means for causing the focus position updating unit to determine new first and second updated focus positions and causing the focus error signal changing unit to change the focus error signal.

According to this configuration, the adjustment of the focus position is started not only when the rotation of the optical disc is started but also when a certain defective state occurs. Objective is achieved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the overall configuration of an optical disk drive device 100 according to the present invention.

FIG. 2A is a schematic diagram of an optical disk 1 of SS-L / GFMT when viewed from above, and FIG.
(C) is a cross-sectional view of the optical disc 1 and the objective lens 3 when a light beam is irradiated on the land of the optical disc 1, and (d) is a groove of the optical disc 1. FIG. 3 is a cross-sectional view of the optical disc 1 and the objective lens 3 when a light beam is irradiated on the optical disk 1.

FIG. 3 is a block diagram illustrating a detailed configuration of a focus position adjustment unit 30.

4A is a schematic configuration of a track on an optical disc 1, FIG. 4B is a broadband tracking error signal RFTE, FIG.
(C) shows the L / G switching signal LGS.

FIG. 5 is a block diagram illustrating a detailed configuration of an address signal detection unit 31.

6A is a diagram illustrating a wideband tracking error signal RFTE input to an address signal detection unit 31, FIG. 6B is an output signal of a binarization circuit 3103, and FIG.
4 shows an output signal, and (d) shows a gate signal IDGATE output from the address signal detector 31.

FIG. 7 is a block diagram illustrating a detailed configuration of an error rate measurement unit 33.

FIG. 8 is a block diagram illustrating a detailed configuration of a focus error detection unit 36.

FIG. 9 is a block diagram showing a detailed configuration of a focus position coarse search unit 50;

FIG. 10 shows an input signal RFT of a read gate detection unit 32;
E shows a gate signal IDGATE indicating an address area and an output signal RDGT from the read gate detection unit 32.

FIG. 11 is a graph showing a bit error rate BER of an RF pulse signal PRF with respect to a change in a focus position.

FIG. 12 is a flowchart showing a detailed operation of a coarse focus position detection unit 50;

FIG. 13 shows a modification of the coarse focus position search of the present embodiment.

FIG. 14 shows an information area layout of the SS-L / GFMT optical disc 1;

FIG. 15 is a graph showing the relationship between the focus position and the magnitude of a reproduction signal RF envelope RFENV and reproduction jitter.

FIG. 16 is a block diagram showing a detailed configuration of a focus position precise search unit 60.

FIG. 17 is a block diagram illustrating a detailed configuration of an averaging unit 71.

FIG. 18 illustrates a disturbance signal, a gate signal IDGATE, and a timer signal TMS when the read gate detection unit 32 is not operating.

FIG. 19A is a timing chart of a gate signal IDGATE, a data acquisition timing signal DGTS, and an L / G switching signal LGS in a groove at the time of precise focus position detection when the read gate detection unit 32 is not operating. FIG. 2B is a similar view in a land.

FIG. 20 is a block diagram showing a detailed configuration of the jitter detector 62.

21 shows an RF pulse signal P in a jitter detector 62. FIG.
7 shows RF, a clock signal CLK, and pulse signals UP and DN output from a phase comparison circuit.

FIG. 22 is a block diagram showing a detailed configuration of a phase comparison circuit 6202.

FIG. 23A is a waveform per unit rotation of a disk of a surface shake component appearing as a residual of a focus servo in a focus error signal FES, and FIG.
The waveform of the disturbance signal output from the disk 5 is shown in FIG.
The outline of a data sector for one rotation (one track) is shown.

FIG. 24 shows the relationship between the focus position and the envelope of the reproduction signal RF detected by the envelope detector 61, and the disturbance signal and the reproduction signal RF at each focus position.
Shows the relationship with the envelope.

25A is a disturbance signal, FIG. 25B is a point A in FIG. 24,
24. The envelope of the reproduced signal RF at each of the points B and C. FIG. 24 (c) shows the waveform obtained by multiplying the disturbance signal by the envelope of the reproduced signal RF at each of the points A, B and C in FIG. Show.

FIG. 26 is a diagram illustrating a relationship between a focus position and a jitter of a reproduction signal RF from the jitter detection unit 62, and a relationship between a disturbance signal and a jitter of the reproduction signal RF at each focus position.

FIG. 27 is a diagram illustrating a relationship between a focus position and a deviation detection value from a focus optimum position.

FIG. 28 (a) is a waveform of a surface runout component of the optical disc 1,
(B) is a read data sector set in the read gate detection unit 32, (c) is a gate signal RDGT output from the read gate detection unit 32, and (d) is a time signal 7101 of the averaging processing unit 71. Timer signal T output
MS, (e) is the AND circuit 7109 of the averaging unit 71
5 shows a data acquisition timing signal DGTS output from the IGBT.

FIG. 29 is a block diagram illustrating a detailed configuration of a surface shake component removing unit 35.

FIG. 30 is a flowchart showing a specific procedure of re-searching for a focus position during recording.

FIG. 31 is a flowchart showing a specific procedure of re-exploration of a focus position during reproduction.

FIG. 32 is a block diagram illustrating a configuration of an optical disk drive device 110 that executes only a search with a coarse focus position.

FIG. 33 is a block diagram illustrating a configuration of an optical disc drive device 120 that executes only a precise search for a focus position.

34 is an optical disc drive device 1 shown in FIG.
20 is a block diagram illustrating a detailed configuration of a focus position precision search unit 600 of FIG.

35 is a block diagram illustrating a detailed configuration of an averaging processing section 710 illustrated in FIG.

FIG. 36 is a block diagram showing a configuration of an optical disk drive device 130 having only a first optional function (read gate detection unit 32) and executing only a precise search for a focus position.

FIG. 37 shows a second optional function (surface runout component removing unit 3).
FIG. 5 is a block diagram showing a configuration of an optical disk drive device 140 that performs only precision search of a focus position provided with 5).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical disk 2 Actuator 3 Objective lens 4 Reproduction signal detector 5 Photodetector 6 Leaf spring 7 Optical head 8 Semiconductor laser 9 Optical head support member 10 Coarse motor 11 Seek controller 12 Spindle motor 13 Rotation controller 14 Drive controller 20 Light Head control unit 21 Focus drive unit 22 Tracking drive unit 23 Tracking control unit 24 Addition unit 25 Disturbance signal generation unit 26 Focus control unit 30 Focus position adjustment unit 31 Address signal detection unit 32 Read gate detection unit 33 Error rate measurement unit 34 Land / groove Detector 35 Surface runout component remover 36 Focus error detector 37-39 Switch 40 Signal processor 41 Laser power driver 42 Modulator 43, 44 Addition amplifier 45 Difference amplifier 46 Addition amplifier 47 Demodulation unit 5 Focus position coarse search unit 51 DSP 52 First storage unit 53 Second storage unit 60 Focus position precision search unit 61 Envelope detection unit 62 Jitter detection unit 63 First high-pass filter 64 Second high-pass filter 65 Third high-pass filter 66 First gain adjustment unit 67 Second gain adjustment unit 68 Third gain adjustment unit 69 Subtractor 70 Multiplier 71 Averaging unit 72 Third storage unit 73 Fourth storage Unit 100 Optical Disk Drive Device 110 Optical Disk Drive Device 120 Optical Disk Drive Device 130 Optical Disk Drive Device 140 Optical Disk Drive Device 600 Focus Position Precision Searching Unit

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Kenji Fujiune 1006 Kadoma Kadoma, Kadoma City, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. F term (reference) 5D118 AA13 BA01 BB02 BC09 BC12 CA08 CB03 CD02 CD07 CD13

Claims (40)

[Claims] 1. A focus position adjusting apparatus for an optical disk having tracks of first and second shapes, wherein the focus position adjusting device detects a convergence state of a light beam applied to the optical disk and indicates a convergence state. A focus error detection unit that outputs an error signal; a focus control unit that changes a focus position of the light beam based on the focus error signal so that the convergence state becomes a predetermined state; and reads information recorded on the optical disc. Reproduction state detection means for detecting the reproduction state of the optical disk based on the reproduction signal when the optical disk is located; detecting which of the first and second tracks on the optical disk the light beam spot is located on; A track detecting means for outputting a track identification signal indicating that the reproduction state is better. A focus position searching means for changing a focus position of the light beam, wherein the focus position searching means is configured to perform a playback state based on the playback state when the track identification signal indicates a track having a first shape. Is determined, and based on the playback state when the track identification signal indicates a track of the second shape, a second update focus where the playback state becomes better is determined. A focus position updating unit that determines a position; and when the track identification signal indicates a track having a first shape, a change is made to the focus error signal so that the focus position becomes the first updated focus position.
A focus error signal changing unit that changes the focus error signal so that a focus position becomes the second updated focus position when the track identification signal indicates a track having a second shape; A focus position adjusting device for changing a focus position of the light beam based on a focus error signal changed by the focus error signal changing unit. 2. The method according to claim 1, wherein the focus position updating unit determines whether or not the reproduction state becomes better when the focus position is shifted by a predetermined moving amount, thereby determining the first update focus position and the second update focus position. The focus position adjusting device according to claim 1, wherein the update focus position is determined. 3. The reproduction state detection unit detects an error occurrence rate in the reproduction signal as the reproduction state, and the focus position updating unit performs the operation when the track identification signal indicates a track having a first shape. Determining a first updated focus position at which the error rate is lower, and determining a second updated focus position at which the error rate is lower when the track identification signal indicates a track having a second shape; The focus position adjusting device according to claim 2, wherein: 4. The focus position adjusting device further includes an area detecting means for detecting whether the light beam spot is located in a data area or an address area of the optical disk, and wherein the reproduction state detecting means comprises: 4. The method according to claim 3, wherein the error occurrence rate is detected only for the reproduction signal when the reproduction signal is located in the address area.
The focus position adjusting device according to any one of the preceding claims. 5. The focus position adjusting device further includes an area detecting means for detecting whether the light beam spot is located in a data area or an address area of the optical disk, and wherein the reproduction state detecting means comprises: 2. The focus position adjusting device according to claim 1, wherein a part of the reproduction signal is extracted based on the detection of the reproduction signal, and the reproduction state is detected from the extracted reproduction signal. 6. The reproduction state detection means detects the reproduction state only for a reproduction signal when the area detection means detects that the light beam spot is located in the address area. Item 6. The focus position adjusting device according to Item 5. 7. The reproduction state detection unit detects the reproduction state only for a reproduction signal when the area detection unit detects that a light beam spot is located in a data area. Item 6. The focus position adjusting device according to Item 5. 8. The focus position adjusting device according to claim 1, wherein the reproduction state detection means detects the reproduction state in consideration of the focus error signal in addition to the reproduction signal. 9. The reproduction state detection means, comprising: an envelope detection section for detecting an envelope of the reproduction signal; and a jitter detection section for detecting jitter of the reproduction signal, wherein the detected envelope, the jitter and the focus are detected. 9. The focus position adjusting device according to claim 8, wherein the reproduction state is detected based on an error signal. 10. The focus control means changes the focus position by superimposing a disturbance of a constant frequency, and the reproduction state detection means further comprises: a first filter unit for detecting the frequency component included in the envelope. A second filter unit that detects the frequency component included in the jitter, a third filter unit that detects the frequency component included in the focus error signal, the first, second, and third The focus position adjusting device according to claim 9, further comprising: a reproduction state specifying unit that specifies the reproduction state using the frequency component from the filter unit. 11. The reproduction state identification unit includes: a value obtained by multiplying a frequency component from the first filter unit by a first coefficient; and a second coefficient to the frequency component from the second filter unit. 11. The reproduction state is specified by using a calculated value obtained by adding the multiplied value and the frequency component from the third filter unit.
The focus position adjusting device according to any one of the preceding claims. 12. The reproduction state specifying unit according to claim 11, wherein the reproduction state specification unit averages the calculated values over a period equal to or longer than a rotation cycle of the optical disc, and specifies the obtained average value as the reproduction state. Focus position adjustment device. 13. The focus position adjusting device further includes an area detecting unit that detects whether the light beam spot is located in a data area or an address area of the optical disc. 13. The focus position adjusting device according to claim 12, wherein the averaging is performed excluding a period located in an address area. 14. The focus position adjusting device further includes: sector specifying means for specifying a sector at a position where the surface deflection acceleration of the optical disc is reduced, wherein the reproduction state specifying unit obtains the sector obtained only from the specified sector. 2. The method according to claim 1, wherein the calculated values are averaged.
3. The focus position adjusting device according to 3. 15. The focus position adjusting device further includes an area detecting means for detecting whether the light beam spot is located in a data area or an address area of the optical disk, and wherein the reproduction state detecting means comprises: 9. The focus position adjusting device according to claim 8, wherein the reproduction state is detected by excluding the reproduction signal and the focus error signal when located in the address area. 16. The focus position adjusting device further includes a surface shake component removing filter for removing a frequency component indicating a surface shake of the optical disc from the focus error signal, and the reproduction state detecting unit removes the frequency component. 9. The focus position adjusting device according to claim 8, wherein the reproduction state is detected from the focus error signal and the reproduction signal. 17. The focus position adjusting device further includes: sector specifying means for specifying a sector at a position where the surface deflection acceleration of the optical disk is reduced, wherein the reproduction state detecting means is obtained only from the specified sector. 10. The reproduction state is detected from the reproduction signal and the focus error signal.
The focus position adjusting device according to any one of the preceding claims. 18. The apparatus according to claim 18, wherein, when the first and second update focus positions are determined by the focus position update unit, information is recorded on the optical disk prior to the determination. It is determined whether or not the data is recorded, and when the information is recorded, the position of the light beam is moved so that the reproduction state is detected, and when not recorded, the test data is recorded by moving the light beam to a predetermined area. 9. The focus position adjusting device according to claim 8, further comprising search preparation means for controlling the test data to detect the reproduction state. 19. The balance error detecting means acquires two focus signals indicating the convergence state, calculates a difference after weighting each of the two focus signals, and adds an offset to the difference. And an offset adjustment unit that outputs the focus error signal. The focus error signal change unit includes a weighting ratio for each of the two focus signals by the balance adjustment unit and an offset amount added by the offset adjustment unit. The focus position adjusting device according to claim 2, wherein the focus error signal is changed by changing at least one of the focus error signal and the focus error signal. 20. The focus error signal changing unit,
When the track identification signal indicates a track of the first shape, the focus error signal is changed by changing a weighting ratio by the balance adjustment unit, and the track identification signal indicates a track of the second shape. 2. The method according to claim 1, wherein the focus error signal is changed by changing an offset amount added by the offset adjustment unit.
10. The focus position adjusting device according to 9. 21. The convergence state of the light beam when the track identification signal indicates a track of a first shape and the convergence state of the light beam when the track identification signal indicates a track of a second shape. An offset storage unit that stores in advance an offset amount that makes the state substantially equal to the state, and when the track identification signal indicates a track of the first shape, the weighting ratio by the balance adjustment unit is set to a new balance value. The focus error signal is changed by changing the focus error signal. When the track identification signal indicates a track having the second shape, the weighting ratio by the balance adjustment unit is changed to the new balance value, and the offset adjustment unit is changed. Is added to the offset amount stored in the offset storage unit. 20. The focus position adjusting device according to claim 19, wherein the focus error signal is changed by changing the focus error signal. 22. The convergence state of the light beam when the track identification signal indicates a track of a first shape and the convergence state of the light beam when the track identification signal indicates a track of a second shape. A balance storage unit that previously stores, as first and second balance values, weighting ratios in each case by the balance adjustment unit that make the states substantially equal to each other, wherein the track identification signal is a track having a first shape. Is indicated, the weighting ratio by the balance adjustment unit is changed to the first balance value stored in the balance storage unit, and the offset amount added by the offset adjustment unit is changed to a new offset amount. Making a change to the focus error signal, wherein the track identification signal When indicating, the weighting ratio by the balance adjustment unit is changed to the second balance value stored in the balance storage unit, and the offset amount added by the offset adjustment unit is changed to the new offset amount. 20. The focus position adjusting device according to claim 19, wherein a change is made to the focus error signal. 23. The focus error detection means acquires two focus signals indicating the convergence state, generates a signal obtained by adding an offset to a difference between the two focus signals, and outputs the signal as the focus error signal. 3. The apparatus according to claim 2, further comprising an adjusting unit.
Or the focus position adjusting device according to 8. 24. The focus error signal changing unit,
When the track identification signal indicates a track having a first shape, the focus error signal is changed by changing the offset amount added by the offset adjustment unit to a first value, and the track identification signal is changed to the first value. 24. The focus position adjustment according to claim 23, wherein when indicating a track having a shape of 2, the focus error signal is changed by changing an offset amount added by the offset adjustment unit to a second value. apparatus. 25. The apparatus according to claim 25, wherein the focus error detection means has a balance adjustment unit that acquires two focus signals indicating the convergence state, and calculates a difference after weighting each of the two focus signals. Item 9. The focus position adjusting device according to item 2 or 8. 26. The focus error signal changing unit,
When the track identification signal indicates a track having a first shape, the focus error signal is changed by changing a weighting ratio by the balance adjustment unit to a first value, and the track identification signal is changed to a second value. 26. The focus position adjustment device according to claim 25, wherein when indicating a track having a shape, the focus error signal is changed by changing a weighting ratio by the balance adjustment unit to a second value. 27. The focus position adjusting device further includes: first tracking control means for controlling the light beam spot to follow a track having the same shape; and the focus position updating section includes: the first tracking control means. The first update focus position is determined in a state where the light beam spot is made to follow the first shape track, and the light beam spot is made to follow the second shape track by the first tracking control means. 9. The focus position adjusting device according to claim 2, wherein the second update focus position is determined in a state. 28. The focus position adjusting device further includes: a second tracking control unit that controls the light beam spot to alternately follow tracks of a first shape and a second shape; Determining the first updated focus position when the light beam spot is following the track of the first shape by the second tracking control means, and determining the light beam spot by the second tracking control means. 9. The focus position adjusting device according to claim 2, wherein the second update focus position is determined when following the track having the second shape. 29. The second tracking control means,
The light beam spot is controlled so as to alternately and repeatedly follow tracks of first and second shapes, and the focus position searching means controls the focus while the control by the second tracking control means is being performed. 29. The focus position adjusting device according to claim 28, wherein the determination of the first and second update focus positions by the position update unit and the change to the focus error signal by the focus error signal change unit are repeated. 30. The focus position adjusting device further includes recording means for recording test data in a test area provided in at least one of a lead-in area and a lead-out area of the optical disc; 2. The focus position adjusting device according to claim 1, wherein the reproduction state is detected based on a reproduction signal when the test data is read. 31. The focus position adjusting apparatus according to claim 30, wherein said recording means randomly selects a track in said test area, and records said test data on said track. 32. The focus position adjusting device, further comprising: track storage means for storing a track in the test area in which the test data is recorded; and a first and second update focus again by the focus position update unit. When the position is determined, prior to the determination, a track designating unit that controls the reproduction state detection unit to detect the reproduction state using test data recorded on a track stored in the track storage unit. 31. The focus position adjusting device according to claim 30, comprising: 33. The focus position adjusting device, further comprising: a defective state determination unit configured to determine whether the reproduction state is a defective state exceeding a predetermined allowable range; 31. A re-exploring means for causing the focus position updating section to determine new first and second updated focus positions, and for causing the focus error signal changing section to change the focus error signal. The focus position adjusting device according to any one of the preceding claims. 34. The focus position according to claim 33, wherein said defective state determination means determines that said reproduction state is said defective state when the number of retries for reproduction exceeds a predetermined value. Adjustment device. 35. The focus according to claim 33, wherein said defective state determining means determines that said reproduction state is said defective state when the power of said light beam in recording exceeds a predetermined value. Position adjustment device. 36. A focus position adjusting device for an optical disc, comprising: a focus error detecting means for detecting a convergence state of a light beam applied to the optical disc and outputting a focus error signal indicating the convergence state; A focus control unit that changes a focus position of the light beam so that the convergence state becomes a predetermined state based on the focus error signal; and a test area provided in at least one of a lead-in area and a lead-out area of the optical disc. Recording means for recording test data; reproduction state detection means for detecting a reproduction state of the optical disc based on a reproduction signal when the test data is read; and focusing of the light beam so that the reproduction state becomes better. And a focus position searching means for changing the position. The focus position searching means determines an update focus position at which the reproduction state detected by the reproduction state detection means becomes better, a focus position update unit, and changes the focus error signal so that the focus position becomes the update focus position. And a focus error signal changing unit for adding the focus error signal, wherein the focus control unit changes the focus position of the light beam based on the focus error signal changed by the focus error signal changing unit. Focus position adjustment device. 37. The focus position adjusting apparatus according to claim 36, wherein said recording means randomly selects a track in said test area and records said test data on said track. 38. The focus position adjusting device further comprises: track storage means for storing track identification information for identifying a track in the test area where the test data is recorded; and a new update by the focus position update unit. When the focus position is determined, prior to the determination, the reproduction state detection means detects the reproduction state using test data recorded on a track indicated by the track identification information stored in the track storage means. 37. The focus position adjusting device according to claim 36, further comprising: a track designating unit that controls the focus position. 39. The focus position adjusting device further comprises: a defective state determination unit configured to determine whether the reproduction state is a defective state exceeding a predetermined allowable range; Causing the focus position update unit to determine a new update focus position,
37. The focus position adjusting device according to claim 36, further comprising: a re-search unit that causes the focus error signal changing unit to change the focus error signal. 40. An optical disk drive device for recording and reproducing data on and from an optical disk having tracks of first and second shapes, wherein the optical disk drive detects a convergence state of a light beam applied to the optical disk and indicates the convergence state. A focus error detection unit that outputs a focus error signal; a focus control unit that changes a focus position of the light beam based on the focus error signal so that the convergence state becomes a predetermined state; and information recorded on the optical disc. A reproduction state detecting means for detecting a reproduction state of the optical disk based on a reproduction signal at the time of reading; and detecting which of the first and second tracks of the optical disk the optical beam spot is located on. A track detecting means for outputting a track identification signal indicating a track; A focus position searching means for changing a focus position of the light beam so as to be favorable, wherein the focus position searching means is based on the reproduction state when the track identification signal indicates a track of the first shape. A first updated focus position at which the reproduction state becomes better is determined, and based on the reproduction state when the track identification signal indicates a track of the second shape, a second reproduction focus position becomes better. A focus position updating unit that determines an updated focus position of the first and second, when the track identification signal indicates a track having a first shape, a change is made to the focus error signal so that the focus position becomes the first updated focus position;
A focus error signal changing unit that changes the focus error signal so that a focus position becomes the second updated focus position when the track identification signal indicates a track having a second shape; An optical disk drive device, wherein a focus position of the light beam is changed based on a focus error signal changed by the focus error signal changing unit.