JP2002298391A - Disk drive device and information reading method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a disk drive device and an information reading method by which proper servo control of a reading means is realized in information reading from a recording medium in which a land and a groove are formed. SOLUTION: The disk drive device is provided with first and second bias resistors 63a, 63b in which a first bias value and a second bias value are preliminarily stored respectively, a land/groove detecting part 17 to detect which of the land and the groove an optical pickup 3 is scanning, a switch circuit SW2 to select the first bias value or the second bias value according to a result of detection, an adder 64 to bias a focus error signal according to the selected bias value and a driving circuit 6 to drive the optical pickup 3 according to the biased focus error signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk drive for recording and reproducing information on a disk-shaped recording medium, and to an information reading method.

[0002]

2. Description of the Related Art Conventional compact disks (CD) and D
A VD-ROM or the like is an optical disk employing a pit recording method. By scanning an optical pickup along a track on which the pits are formed and measuring reflected light,
The information recorded by the pits is reproduced. here,
The optical pickup realizes optimal information reproduction,
The distance from the optical disk is controlled according to the focus error signal.

At this time, the focus error signal is corrected according to a focus bias value (hereinafter, also simply referred to as a "bias value"), and the optical pickup is controlled so that the jitter of the obtained RF signal is minimized. .

However, when reading information from an optical disc such as a DVD-RAM on which lands and grooves (grooves) are formed, the optimum bias value differs depending on whether the reading destination is a land or a groove. However, there is a problem that the best RF signal cannot be obtained from both the land and the groove only by correcting the focus error signal with one bias value as in the related art.

The reason why the optimum bias value differs between the case where the reading destination is the land and the case where the reading destination is the groove is because the distance from the optical pickup to the land and the distance from the optical pickup to the groove are different. is there.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has been made in the art of DVD-RAM.
It is an object of the present invention to provide a disk drive device and an information reading method capable of realizing proper servo control of a reading unit in reading information from a recording medium on which lands and grooves are formed.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a first bias value which is determined according to an optimum distance when a reading means scans a land, and an optimum bias value when the reading means scans a groove. Storage means for storing in advance a second bias value determined according to the distance, detection means for detecting which of the lands or grooves the scanning means is scanning, and detection means for detecting Correction means for selecting a first bias value or a second bias value stored in advance in the storage means, and correcting a focus error signal supplied by the selected bias value; and a focus corrected by the correction means. This is achieved by providing a disk drive device including: a driving unit that drives a reading unit in accordance with an error signal to control a distance.

According to such a means, focus servo control is executed by a focus error signal optimized according to the position scanned by the reading means. Here, the accuracy of the focus servo control by the driving unit is improved by further including an average correcting unit that corrects the average value of the focus error signal according to a deviation from the initial setting value and supplies the average value to the correcting unit. be able to.

It is another object of the present invention to provide a first bias value determined according to an optimum distance between a reading unit and a recording medium when the reading unit scans a land, and a reading unit to scan a groove. A step of specifying in advance a second bias value determined according to the optimal distance, a step of detecting which of the lands and grooves the scanning means is scanning, and according to a result of the detection, Selecting a first bias value or a second bias value, and correcting a focus error signal by the selected bias value;
Controlling the distance by driving the reading means in response to the corrected focus error signal.

According to such a means, it is possible to easily realize the optimum focus servo control according to the scanning position of the reading means.

It is another object of the present invention to provide a first bias value determined according to an optimum distance between a reading unit and a recording medium when the reading unit scans a land; A step of previously identifying a second bias value determined according to the optimum distance; and correcting the average value of the average value of the focus error signal according to a deviation from the initial setting value to obtain a second focus error signal. Generating a first bias value or a second bias value according to the result of the detection, and selecting the first bias value or the second bias value according to the detection result. Correcting the second focus error signal by the value, and controlling the distance by driving the reading unit in accordance with the corrected second focus error signal It is achieved by providing information reading method having.

According to such a means, an optimized focus error signal is generated by correcting the average value of the focus error signal and applying a bias corresponding to the scanning position of the reading means, so that the accuracy is improved. High focus servo control can be easily realized.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings. The same reference numerals in the drawings indicate the same or corresponding parts. FIG. 1 is a block diagram showing an overall configuration of a disk drive device according to an embodiment of the present invention. As shown in FIG. 1, the disk drive device according to the present embodiment is a device for recording and reproducing information on and from an optical disk 1 mounted thereon, and includes a spindle motor (SPM) 2 and an optical pickup 3. , Two-axis mechanism 3a, RF amplifier 4, servo processor 5, drive circuit 6, binarization circuit 7, clock reproduction circuit 8,
A decoding circuit 9, an error correction circuit 10, a buffer memory 11, a data interface 12, a system controller 13, a RAM block 14, a header detection unit 15,
The host computer 4 includes a PID detector 16, a land / groove detector 17, an external data bus 18, a thread mechanism 19, a laser diode 30, an objective lens 34, and a photodetector 37.
It is connected to 0.

In the above, the spindle motor (SP
M) 2 controls the rotation of the turntable on which the optical disc 1 is mounted. The optical pickup 3 irradiates a laser beam to the signal surface of the optical disk 1 by the laser diode 30 and detects reflected light from the signal surface by the photodetector 37, thereby obtaining the optical disk 1.
Of the data recorded in the.

Here, the objective lens 34 constituting the optical pickup 3 condenses the laser beam emitted from the laser diode 30 and irradiates it on the signal surface of the optical disk 1. This objective lens 34 is a biaxial mechanism 3a. Thus, it is movably held in the tracking direction and the focus direction.
The optical pickup 3 can be moved in the radial direction of the optical disc 1 by a sled mechanism 19.

The reflected light detected by the optical pickup 3 as described above is supplied to an RF amplifier 4 as a current signal corresponding to the amount of light, and the RF amplifier 4 performs current / voltage conversion and matrix calculation processing. Is performed to generate a focus error signal FE and a tracking error signal TE. Further, an RF signal as reproduction information, a PI (pull-in) signal as a sum signal, and the like are generated.

The focus error signal FE and the tracking error signal TE generated by the RF amplifier 4 are supplied to a drive circuit 6 after required processes such as phase compensation and gain adjustment are performed by a servo processor 5. More specifically, the servo processor 5 generates a thread control signal SS for track jump via a built-in low-pass filter (LPF) and supplies it to the drive circuit 6, and focuses in response to an instruction from the system controller 13. A signal SF for a search operation and a signal ST for a track jump operation are supplied to the drive circuit 6.

The drive circuit 6 executes the thread servo control by outputting the track jump thread control signal SS as a thread drive signal to the thread mechanism 19, and generates a focus drive signal and a tracking drive signal. Focus servo control and tracking servo control are executed by outputting to the two-axis mechanism 3a. Thereby, focus search, track jump / access, and the like of the optical pickup 3 are realized.

On the other hand, the reproduced RF signal generated by the RF amplifier 4 is binarized by a binarization circuit 7 and is subjected to EFM.
A plus signal is generated. Then, the EFM plus signal is supplied to the clock recovery circuit 8, and a recovered clock signal CLK synchronized with the EFM plus signal is extracted and generated.
The reproduced clock signal CLK is supplied as an operation clock in various circuits including the decode circuit and the servo processor 5.

The EFM plus signal from which the clock signal has been extracted as described above is supplied to the decoding circuit 9 and demodulated, and then supplied to the error correction circuit 10. The error correction circuit 10 performs an error correction process according to, for example, the RS-PC method while using the buffer memory 11 as a work area. The error-corrected binarized data is transferred to the data interface 12. The data interface 12 is provided for communication with an external information processing device such as a host computer 40 connected via the external data bus 18, and has the binary data ( (Reproduced data) to the host computer 40.

The system controller 13 controls the entire disk drive and is constituted by a microcomputer. The system controller 13 controls the operation of each unit based on the operation status, instructions from the host computer 40, and the like.

Further, a RAM block 14 is provided corresponding to the reproduction of the DVD-RAM. Where RA
The header detector 15 included in the M block 14 detects the timing at which the trace position of the laser beam passes through the header area of the DVD-RAM. Further, the PID detection unit 16 detects a physical address PID recorded in the header area.

In the above disk drive device, when reproducing information recorded on the DVD-RAM, it is detected whether the recording area of the sector to be read is formed on the land or the groove. It is desirable to correct the focus error signal with an optimum focus bias value according to the detection result.
Here, the land / groove detecting unit 17 detects whether the read target area is a land or a groove, and
A signal SLG indicating the determination result is generated and output. Note that the push / pull signal PP generated in, for example, the RF amplifier 4 is supplied to the land / groove detection unit 17.

FIG. 2 is a block diagram showing a configuration of the focus error correction circuit 60 included in the servo processor 5 shown in FIG. As shown in FIG. 2, the focus error correction circuit 60 includes an FE average correction register 61 and adders 62 and 64, a first bias register 63a, a second bias register 63b, a register 66, a focus filter 67, and switch circuits SW1 to SW3. including.

Here, the FE average correction register 61 stores R
The focus error signal FE generated by the F amplifier 4 is supplied, and the output node of the FE average correction register 61 is connected to the switch circuit SW1. Note that the switch circuit SW
One other input is grounded. The adder 62 has R
Focus error signal F generated in F amplifier 4
E and the signal output from the switch circuit SW1 are supplied. Further, the first bias register 63a and the second bias register 63b are connected to the switch circuit SW2,
The output node of the switch circuit SW2 is connected to the switch circuit SW3.
Connected to the input node. Note that the switch circuit SW3
Other input nodes are grounded.

The signal output from the adder 62 and the signal output from the switch circuit SW3 are supplied to the adder 64. The adder 64 has a register 6
6 is connected to the register 66 and the focus filter 6
7 is connected. Then, the signal SF is generated by the focus filter 67 and supplied to the drive circuit 6. In addition,
The switch circuit SW1 is connected to the system controller 13
Switch circuit S by the control signal FLC1 supplied from the
W2 is a signal supplied from the land / groove detector 17
The switching operation of the switch circuit SW3 is controlled by the control signal FBON supplied from the system controller 13 by SLG.

The focus error correction circuit 60 having the above-described configuration is a circuit for performing a correction process on the focus error signal FE. Hereinafter, each component of the circuit will be described.

The FE average correction register 61 stores the RF amplifier 4
The focus error signal FE supplied from is sampled at a predetermined cycle, an average value of the signal is obtained, and a deviation from the set average value is calculated. Then, this shift (DC offset) is supplied to the adder 62 via the switch circuit SW1, and the shift is canceled by subtracting the DC offset from the original focus error signal FE.

Next, while changing the magnitude of the bias applied to the focus error signal FE, the measured RF
The amount of jitter of the signal is monitored, and the magnitude of the bias that minimizes the amount of jitter is specified. Then, the bias specified in this way is applied to the focus error signal FE by the adder 64, and the optimum focus error signal FE is generated.

Here, the optimum value of the bias differs depending on whether the optical pickup 3 scans a land or a groove when reproducing information. For this reason, in the disk drive device according to the present embodiment, as shown in FIG.
And a second bias register 63b for storing an optimum bias value when the optical pickup 3 scans a land and an optimum bias value when the optical pickup 3 scans a groove. When the optical pickup 3 scans a land during information reproduction, the focus error signal FE is corrected by the optimum bias value stored in the first bias register 63a, and when the optical pickup 3 scans a groove, The focus error signal FE is corrected by the optimum bias value stored in the second bias register 63a.

As described above, the optimum bias value stored in the first bias register 63a is determined by monitoring the RF signal obtained when the optical pickup 3 actually scans the land, and The optimum bias value stored in the bias register 63b is the value of R obtained when the optical pickup 3 actually scans the groove.
It is determined by monitoring the F signal.

Here, the switch circuit SW2 is connected to a land /
The optimum bias value stored in the first bias register 63a or the second bias register 63b is selected according to the signal SLG supplied from the groove detection unit 17, and is supplied to the switch circuit SW3. Also, the switch circuit SW3
Is a signal FBON supplied from the system controller 13.
Is activated, the bias value supplied from the switch SW2 is supplied to the adder 64.

The register 66 stores the supplied focus error signal FE and supplies this signal to the focus filter 67. Note that the focus filter 67 generates a signal SF by filtering the supplied signal, and supplies the signal SF to the drive circuit 6.

As described above, according to the disk drive device of the embodiment of the present invention, when the optical pickup 3 scans the lands and grooves to reproduce information, the position depends on the scanning position (land or groove). Since an optimal bias can be applied to the focus error signal FE, an accurate RF signal can be obtained. Further, as described above, since a plurality of optimum bias values can be selectively used in accordance with the scanning position of the optical pickup 3, each time the scanning position of the optical pickup 3 changes between the land and the groove, the above-described operation is performed. There is no need to reset the bias value from outside the device.

It should be noted that the disk drive device according to the present embodiment can switch the reproduction signal processing system in accordance with the type of recording medium, or change the required reproduction parameters, etc. -RO
M, or CD-DA (Digital Audio), CD-R
It can also be realized as a device for reproducing a recording medium such as an OM.

[0036]

According to the disk drive of the present invention, the focus servo control is executed by the focus error signal optimized according to the position scanned by the reading means, so that the accuracy of information reproduction can be improved. it can.

Further, according to the information reading method of the present invention, it is possible to easily realize the optimum focus servo control according to the scanning position of the reading means, so that the reliability of the information reading can be easily increased. it can.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an overall configuration of a disk drive device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a focus error correction circuit included in the servo processor shown in FIG.

[Explanation of symbols]

1 optical disk, 2 spindle motor (SPM),
Reference Signs List 3 optical pickup, 3a biaxial mechanism, 4 RF amplifier, 5 servo processor, 6 drive circuit, 7 binarization circuit, 8 clock reproduction circuit, 9 decoding circuit, 10
Error correction circuit, 11 buffer memory, 12 data interface, 13 system controller, 14
RAM block, 15 header detector, 16 PI
D detector, 17 land / groove detector, 18 external data bus, 19 thread mechanism, 30 laser diode, 34 objective lens, 37 photodetector, 4
0 host computer, 60 focus error correction circuit, 61 FE average correction register, 62, 64 adder, 63a first bias register, 63b second bias register, 66 register, 67 focus filter, SW1 to SW3 switch circuit.

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] April 17, 2001 (2001.4.1
7)

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] Fig. 1

[Correction method] Change

[Correction contents]

FIG.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kazuyuki Hayashi 134 Kobecho, Hodogaya-ku, Yokohama-shi, Kanagawa Prefecture Sony LSI Design Inc. F-term (reference) 5D118 AA13 BA01 BC09 CA08 CA11 CB03 CD02 CD11

Claims (4)

[Claims] 1. A disk drive device in which lands and grooves are formed and information is read by a reading unit from a recording medium on which information is recorded on the lands and grooves, wherein a distance between the reading unit and the recording medium is determined. A focus error signal generating means for generating a focus error signal to be controlled; a first bias value determined according to the optimum distance when the reading means scans the land; and the reading means sets the groove. Storage means for previously storing a second bias value determined according to the optimum distance when scanning, and detection means for detecting which of the lands and the grooves the reading means is scanning. The first bias value or the first bias value stored in the storage unit in advance according to a detection result by the detection unit. A correction unit for selecting the second bias value and correcting the focus error signal supplied by the selected bias value; and driving the reading unit in accordance with the focus error signal corrected by the correction unit. A disk drive device comprising: a driving unit that controls the distance. And correcting the average value of the focus error signal generated by the focus error signal generation unit according to a deviation from an initial setting value.
2. The disk drive according to claim 1, further comprising an average correcting unit that supplies the average to the correcting unit. 3. An information reading method in which a land and a groove are formed, and the information is read by a reading unit from a recording medium on which the information is recorded on the land and the groove, wherein the reading unit scans the land. A first bias value determined according to the optimal distance between the reading unit and the recording medium, and a second bias value determined according to the optimal distance when the reading unit scans the groove. Specifying a bias value in advance; generating a focus error signal for controlling a distance of the reading unit to the recording medium; and detecting which of the lands and the groove the scanning unit is scanning And selecting the first bias value or the second bias value according to the result of the detection, and selecting the selected bias. Steps and, corrected in response to said focus error signal, information reading method and a step of controlling the distance by driving the reading means for correcting the focus error signal by. 4. An information reading method in which a land and a groove are formed and information is read by a reading unit from a recording medium on which the information is recorded on the land and the groove, wherein the reading unit scans the land. A first bias value determined according to an optimum distance between the reading unit and the recording medium, and a second bias value determined according to the optimum distance when the reading unit scans the groove. And a step of generating a focus error signal for controlling the distance of the reading unit to the recording medium; and calculating the average value of the focus error signal according to a deviation from an initial setting value. Correcting to generate a second focus error signal; and wherein the reading means runs on either the land or the groove. Detecting whether the first focus value or the second bias value is selected according to a result of the detection, and correcting the second focus error signal by the selected bias value. And according to the corrected second focus error signal,
Controlling the distance by driving the reading means.