JP2003223727A - Optical disk apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical disk apparatus capable of stably reading out absolute time information and capable of recording on the whole surface of an optical disk. <P>SOLUTION: The optical disk apparatus includes a retrieval means 14b which obtains the focus bias voltage at which a tracking error signal amplitude becomes maximum when a servo processor 9 serially applies the focus bias voltage of a bias voltage table 14a and a CPU 13 which obtains an approximation expression for approximating the relationship between the optical disk radial position and the focus bias voltage, on the basis of the focus bias voltage obtained at a plurality of radial positions of the optical disk 1 by the retrieval means 14b before the recording. In the recording, the servo processor 9 adds the offset voltage obtained by the approximation expression to a focus error signal at each recording radial position to read the absolute time information of the optical disk 1. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc device for recording information on an optical disc by a pickup or reproducing information on the optical disc.

[0002]

2. Description of the Related Art A conventional recordable optical disk device will be described with reference to the drawings. FIG. 4 is a configuration diagram of a conventional optical disc device, and FIG. 5 is an explanatory diagram of a focus S-shaped signal. In FIG. 4, 1 is an optical disc on which data is recorded, 2
Is a pickup for recording and reproducing data, 3 is an objective lens for laser focusing held by an actuator in the pickup 2, and is driven by an actuator drive circuit 6 described later in the vertical and radial directions of the optical disc 1. It

Reference numeral 4 is a spindle motor, 5 is a spindle motor drive circuit, 6 is an actuator drive circuit, 7 is a laser drive circuit, 8 is a read amplifier, and 9 is a servo processor. The optical disc 1 is a spindle motor drive circuit 5
An electric current is supplied to the spindle motor 4 to rotate it. Further, the pickup 2 is supplied with a current from the laser driving circuit 7 and emits a laser with a predetermined power to the optical disk 1.
To go out. Reflected light from the optical disc 1 is received by the pickup 2, converted into an electric signal and sent to the read amplifier 8 to detect a servo error signal. The servo error signal is used as a feedback signal of the servo processor 9 to control the spindle motor drive circuit 5 and the actuator drive circuit 6.

Reference numeral 10 is an A / D converter for digitally converting the peak level, bottom level, and DC level of the RF signal detected by the read amplifier 8 and inputting it to a CPU 13, which will be described later, 11 is an encoder, 12 is a decoder, and 13 is A CPU (Central Processing Unit) that performs logical judgment and calculation, 14 is a read only memory (hereinafter, ROM) having a program storage area in which a control program and a recording / reproducing control program for an optical disk device are stored, and 15 is a control In addition to the storage area required for storage, a main memory (hereinafter abbreviated as memory) used as a storage area required for various recording and reproduction controls, 16 is a buffer memory for temporary storage, and 17 is a personal computer interface. Circuit, 18 CP
Bus for connecting U13, ROM14, memory 15, etc., 1
9 is a D / A converter.

A data signal is also detected in the read amplifier 8, and the detected data is demodulated by the decoder 12 and stored in a buffer memory 16 for temporary storage and sent to a personal computer through a personal computer interface circuit 17. In addition, at the time of recording, the personal computer interface circuit 17 receives data from the personal computer, stores it in the buffer memory 16, and then modulates it by the encoder 11.
It is input to the laser drive circuit 7 as a laser drive signal. The laser drive circuit 7 receives a laser power determination voltage from the D / A converter 19 to determine the laser drive current. The laser drive circuit 7 uses the drive signal from the encoder 11 and the voltage from the D / A converter 19 to set a predetermined laser power. It is driven by pattern and current. By switching the laser power determination voltage of the D / A converter 19 in multiple stages, the laser emission power changes in multiple stages. CPU 13 is A / D converter 10
The degree of modulation of the RF signal is calculated based on the signal of.

Focus control in the conventional optical disk device described above will be described. Focus control is an operation for keeping the distance between the objective lens 3 and the optical disc 1 constant, and is performed by controlling the focus error signal. The focus error signal is a signal indicating the amount of vertical shift between the optical spot, which is the tip of the laser light focused by the objective lens 3, and the optical disk data surface. First, the actuator drive circuit 6 operates in response to a command from the servo processor 9 to bring the objective lens 3 closer to the optical disc 1 from a position sufficiently far from the optical disc 1, and after approaching to a certain position, it moves away.
By this operation, a focus error signal having a shape as shown in FIG. 5 is obtained, and this signal is called an S-shaped signal. The voltage at the amplitude center position A of the S-shaped signal is a voltage at which the focal point position, that is, the amount of vertical deviation between the objective lens 3 and the optical disk data surface matches, and the servo processor 9 obtains the S-shaped signal, The actuator drive circuit 6 is operated so that the focus error signal is always at this reference voltage. By this focus control, the optical disk device can perform recording and reproduction while always keeping the distance between the objective lens 3 and the optical disk data surface constant. In recent years, as a method of optimizing this focus control, after obtaining the voltage at the S-shaped amplitude center position A in FIG. 5, the voltage is slightly shifted to obtain the voltage at which the tracking error signal becomes maximum, and the voltage It has been devised to perform the focus operation based on.

[0007]

When the optical disk apparatus performs recording, laser is irradiated on the guide groove formed on the optical disk 1 to form pits. The guide groove is slightly meandering, and the capacity information of the optical disc 1 and the absolute time information on the optical disc 1 are stored by modulating the meandering frequency. The optical disk device needs to record arbitrary data at an arbitrary position, and at the same time as recording, it is necessary to read the absolute time information of the optical disk 1.

In recent years, due to the increase in capacity of the optical disc 1 and the increase in recording speed, the optical disc 1 has a small guide groove having a small meandering amplitude, and the optical disc 1 in which the boundary between the guide groove and the land is not clear
However, in the conventional focus control of the optical disc device, when recording is performed on such an optical disc 1, the absolute time information cannot be read and a write error occurs. .

To address this problem, it is effective to perform focus control at a position where the tracking error signal amplitude is maximum, but with this alone, the optical disc 1 warps at the outer circumference and the tracking error signal amplitude is maximized. When the points are different on the inner and outer circumferences, or when the tracking error signal amplitude maximum point is different on the inner and outer circumferences due to the characteristics of the pickup 2 itself, the absolute time information can be read on the inner circumference of the optical disc 1, but is recorded on the outer circumference. However, there was a problem that the absolute time information gradually became unreadable and a write error occurred.

Therefore, the present invention is to solve the above-mentioned problems, and it is possible to provide a stable absolute time for an optical disk in which the guide groove has a small meandering amplitude and an optical disk in which the boundary between the guide groove and the land is unclear. An object of the present invention is to provide an optical disk device capable of reading information and recording on the entire surface of the optical disk.

[0011]

In order to solve the above-mentioned problems, the optical disk device of the present invention is such that when the control means sequentially applies the focus bias voltage of the bias voltage table,
The relationship between the optical disc radial position and the focus bias voltage is approximated based on the search means for obtaining the focus bias voltage that maximizes the tracking error signal amplitude and the focus bias voltage obtained by the search means at a plurality of radial positions of the optical disc before recording. Equipped with arithmetic means for obtaining an approximate expression
During recording, the control means reads the absolute time information of the optical disc by adding the offset voltage obtained by the approximate expression to the focus error signal at each recording radial position.

As a result, the absolute time information can be stably read out from the optical disc having a small meandering amplitude of the guide groove or the optical disc in which the boundary between the guide groove and the land is unclear, and recording can be performed on the entire surface of the optical disc. The optical disk device can be realized.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is an optical disk device for condensing a laser beam emitted from a semiconductor laser with an objective lens and recording data on an optical disk, and a multi-stage focus. A memory that stores a bias voltage table in which a bias voltage is set, a control unit that adds the focus bias voltage to the focus error signal when performing focus control, and a tracking unit that sequentially adds the focus bias voltage of the bias voltage table to the tracking unit. The relationship between the optical disc radial position and the focus bias voltage is approximated based on the search means for obtaining the focus bias voltage with the maximum error signal amplitude and the focus bias voltage obtained by the search means at a plurality of radial positions of the optical disc before recording. Equipped with a calculation method to obtain an approximate expression, The optical disc device is characterized in that the control unit reads the absolute time information of the optical disc by adding the offset voltage obtained by the approximate expression to the focus error signal at each recording radial position, and the stable recording is performed on the entire optical disc. It has the effect of being able to read the absolute time information inside.

The invention according to claim 2 of the present invention is characterized in that the plurality of radial positions are the radial positions of the inner circumference, the middle circumference, and the outer circumference of the optical disk, and the approximate expression is a quadratic function. The optical disk device according to item 1, which has an effect that the absolute time information during recording can be stably read with high accuracy on the entire surface of the optical disk by the minimum necessary measurement of the inner circumference, the middle circumference, and the outer circumference.

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a block diagram of an optical disk device according to Embodiment 1 of the present invention. The optical disk device of the first embodiment has basically the same configuration as the conventional optical disk device, and the same reference numerals indicate the same members as those of the conventional optical disk device. Hand over to.

In FIG. 1, reference numeral 1 is an optical disk on which data is recorded, 2 is a pickup for recording and reproducing data, and 3 is an objective lens provided on the pickup 2 for condensing laser light from a semiconductor laser. Reference numeral 4 is a spindle motor for rotating the optical disc 1, 5 is a spindle motor drive circuit, 6 is an actuator drive circuit, 7 is a laser drive circuit, 8 is a read amplifier, and 9 is a servo processor (control means of the present invention). Reference numeral 10 is an A / D converter for digitally converting the peak level, bottom level, and DC level of the reproduction RF signal detected by the read amplifier 8 and inputting it to the CPU 13 described later, 11 is an encoder, 12 is a decoder, 13 is a CPU, and 14 is ROM, 14a is a bias voltage table storing bias voltage values in multiple stages, 14
Reference numeral b is a search means for applying the focus bias voltage value in the bias voltage table 14a and causing the CPU 13 to perform a series of functions for obtaining the focus bias voltage value at which the amplitude of the tracking error signal is maximum, 15 is a memory, and 16 is a temporary storage. For buffer memory, 17 for personal computer interface circuit, 18 for CPU 13 and R
Bus for connecting OM14, memory 15, etc., 19 is D / A
It is a converter. The ROM 14 holds a predetermined RF modulation factor used for optimum recording laser power control (OPC: Optimum Power Control). The modulation degree of the RF signal is calculated by adding the peak level and the bottom level of the RF signal detected by the A / D converter 10 to calculate the RF amplitude level, and dividing by the RF top level obtained by adding the peak level and the DC level. By doing so, the CPU 13 calculates.
Further, the CPU 13 loads the control program from the ROM 14 and functions as a function realizing means. The above-mentioned retrieval means 14b and the arithmetic means for performing the arithmetic functions as described below are all function realizing means by the CPU 13 with the control program loaded. The same applies to the servo processor 9.

Here, the optical disk device of the first embodiment performs the following operation in order to stably read the absolute time information. First, the focus control is operated by a method similar to the conventional method. After that, before recording data, the servo processor 9 performs RO at the inner circumferential position of the optical disc 1 in advance.
The multi-stage focus bias voltage set in the bias voltage table 14a of M14 is added to the focus error signal generated by the read amplifier 8. This makes it possible to operate the focus drive section of the actuator drive circuit 6 to move the objective lens 3 in the vertical direction of the optical disc 1 in multiple stages. At this time, the tracking servo is turned off. The tracking error signal amplitude obtained at each stage of these operations is loaded into the CPU 13, and the values are compared to obtain the focus bias voltage that maximizes the tracking error signal amplitude at the inner circumferential position. Subsequently, similarly, the focus bias voltage that maximizes the tracking error signal amplitude is obtained at the middle and outer circumferences of the optical disc 1 in the radial direction, and the CPU 13 causes the radial position of the optical disc 1 and the focus bias that maximizes the tracking error signal amplitude. Calculate the relationship with the voltage,
Obtain a quadratic approximation curve. Since the focus bias voltage is obtained at three points of the inner circumference, the middle circumference, and the outer circumference, it is possible to calculate the coefficient of the quadratic term, the coefficient of the first order, and the constant of the quadratic approximation function. Then, it can be approximated by a quadratic function. During recording, recording is performed while applying an optimum focus bias voltage at each recording position based on this quadratic approximation curve. In the first embodiment, the measurement is performed at three points of the inner circumference, the middle circumference, and the outer circumference. However, in order to make a more precise approximation, the focus bias at which the tracking error signal amplitude becomes maximum at a plurality of radial positions of three or more points. The voltage can also be determined.

FIG. 2 is a flowchart of focus control when recording data on an optical disc in the optical disc device according to the first embodiment of the present invention. As shown in FIG.
Insert the optical disc 1 into the optical disc device, and step S1
The disk start-up process is performed in, and control of focus, tracking, and spindle is started. Next, in the process of step S2, move to a predetermined inner circumferential position,
In step S3, the focus bias voltage search 1 of the bias voltage table 14a is executed by the search means 14b.

In this step S3, step S3
The tracking servo is turned off in step 1, and step S32 is performed.
Bias voltage table 14a for focus error signal
The focus bias voltage search 1 is executed by successively applying the multi-stage focus bias voltage stored in the.
Next, in step S33, the CPU 13 measures the tracking error signal amplitude for each bias voltage. Further, by comparing the respective measurement results, the bias voltage that maximizes the tracking error signal amplitude is obtained, and the memory 15
To record. This completes the process of step S3.

Next, in step S4, the focus bias voltage search 2 is performed by the search means 14a by moving to a predetermined intermediate position of the optical disk 1 in step S5.
I do. Since the processing content of step S5 is exactly the same as that of S3, detailed description will be omitted.

When step S5 ends, step S6
In step S7, the focus bias voltage search 3 in step S7 is performed. The content of the processing in step S7 is also step S
Since the contents are the same as those in No. 3, detailed description will be omitted.

After the focus bias voltage at the inner circumference, the middle circumference, and the outer circumference of the optical disc 1 is obtained in this way, the CPU 13 performs arithmetic processing in step S8 to find the focus bias voltage for each radial position by an approximate expression. .

Upon completion of step S8, the optical disk device enters the standby state of step S9 and starts recording when the recording command of step S10 is issued. During recording, recording is performed while changing the focus bias voltage at each recording position according to the above-described approximate expression.

In the optical disk device of the first embodiment, the focus bias voltage is measured at the inner circumference, the middle circumference, and the outer circumference, and the approximation is performed with high accuracy. Therefore, the optical disk 1 with a small meandering amplitude of the guide groove or the guide groove and the land is small. The absolute time information can be stably read out from the optical disc 1 whose boundary is not clear according to the approximate expression, and recording can be performed on the entire surface of the optical disc 1.

(Second Embodiment) FIG. 3 is a diagram for explaining the relationship between the optimum bias value corresponding to the radial position of the optical disk and the approximate expression. As described in the first embodiment, the approximate expression approximated by the three points of the inner circumference, the middle circumference, and the outer circumference is compared with the detailed measurement value. As shown in the figure, the linear function cannot be expected to be an accurate approximation, but the quadratic function is an accurate approximation.

It is expected that more accurate approximation will be achieved by increasing the number of measurement points and obtaining a high-order approximation formula. However, increasing the number of measurement points leads to an increase in required time and an increase in calculation amount. Therefore, even in order to finish the calculation of the bias voltage approximation in a short time, an approximation equation practically sufficient can be obtained by the approximation by the quadratic equation. Needless to say, it is possible to approximate a higher-order function of a cubic function or higher and increase the number of measurement points by improving the calculation speed.

In this way, the bias voltage can be obtained in a short time by measuring the three points of the inner, middle and outer circumferences and approximating by a quadratic function rather than obtaining the bias voltage in detail at a large number of radial positions. Moreover, the approximate expression can ensure sufficient accuracy for practical use.

Therefore, it is possible to shorten the time from when the recording command is given until the actual recording is started, and it is possible to perform accurate approximation.

[0030]

As described above, the optical disc apparatus of the present invention can perform recording by applying the focus bias voltage most suitable for reading the absolute time information over the entire circumference of the optical disc, so that the small meandering amplitude of the guide groove can be applied. It is possible to realize an optical disk device capable of stably reading the absolute time information and recording on the entire surface of the optical disk for an optical disk with a small size or an optical disk in which the boundary between the guide groove and the land is unclear.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an optical disc device according to a first embodiment of the present invention.

FIG. 2 is a flowchart of focus control when recording data on an optical disc in the optical disc device according to the first embodiment of the present invention.

FIG. 3 is a diagram illustrating a relationship between an optimum bias value corresponding to a radial position of an optical disc and an approximate expression.

FIG. 4 is a block diagram of a conventional optical disc device.

FIG. 5 is an explanatory diagram of a focus S-shaped signal.

[Explanation of symbols]

1 optical disc 2 pickups 3 Objective lens 4 spindle motor 5 Spindle motor drive circuit 6 Actuator drive circuit 7 Laser drive circuit 8 lead amplifier 9 Servo processor 10 A / D converter 11 encoder 12 decoder 13 CPU 14 ROM 14a Bias voltage table 14b Search means 15 memory 16 buffer memory 17 PC interface circuit 18 bus 19 D / A converter

Claims (2)

[Claims] 1. An optical disc device for condensing a laser beam emitted from a semiconductor laser with an objective lens and recording data on an optical disc, comprising: a memory for storing a bias voltage table in which multi-stage focus bias voltages are set; A control unit that adds a focus bias voltage to a focus error signal when performing focus control, and a focus bias voltage that maximizes the tracking error signal amplitude when the control unit sequentially adds the focus bias voltage of the bias voltage table The recording means is provided with a searching means and a calculating means for calculating an approximate expression approximating the relationship between the optical disc radial position and the focus bias voltage based on the focus bias voltage obtained at the plurality of radial positions of the optical disc by the searching means before recording. The control means is Optical disc apparatus characterized by reading the absolute time information of the optical disk offset voltage Motoma' the equation in addition to the focus error signal in each recording radial position. 2. The plurality of radial positions are the inner circumference of the optical disc,
2. The optical disk device according to claim 1, wherein the approximate expression is a quadratic function at radial positions of the middle circumference and the outer circumference.