JPH10283738A - Optical disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To record data in synchronization with a zigzag signal and with a recording clock without any jitter where the mixture of an FM component contained in the zigzag signal into the recording clock is canceled. SOLUTION: When information is recorded and reproduced by focusing laser beams to the recording track of an optical disk where a spiral guide groove that meanders in radius direction is formed, a tracking error signal detection circuit 5 for extracting the zigzag signal of the guide groove, a band-pass filter 6, and a comparator 7 are provided. Also, a PLL circuit 13 for extracting the frequency modulation component of the zigzag signal and a frequency multiplication circuit 8 for generating a multiplication clock being synchronized to the zigzag signal are provided, thus correcting the frequency of the multiplication clock according to the frequency modulation component and hence generating the recording clock.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk apparatus which enables information recording / reproduction even when the rotation of the optical disk is not settled.

[0002]

2. Description of the Related Art MD (mini disc), CDR (CD-
Recordable: recordable compact disc)
A spiral guide groove is formed in a CDE (CD-Erasable: erasable compact disc) (see Japanese Patent Application Laid-Open No. Hei 6-338066).

[0003] This guide groove is formed by a CLV (Constant).
A constant spatial frequency (for example, 1) so that rotation control of Linear Velocity (constant linear velocity) is possible.
7000 Cycle / cm: 59 μm per cycle)
Meandering in the radial direction of the optical disk (for example, about 0.03 μm).

Therefore, the driving device drives the rotating motor so that the frequency of the meandering signal due to the meandering becomes constant (for example, 22.05 KHz) and becomes constant (for example, 1.3 m).
/ S) The optical disk is rotated at a linear velocity of (/ s).

[0005] In addition, the meandering signal contains address information of FM.
(Frequency modulation) and superimposed. For example, information "1" is 23.05 kHz and information "0" is 20.05 kHz
Hz, so that the number average of “1” and “0” is the same. As a result, in the actual CLV control, the mean frequency of the meandering signal is controlled to be 22.05 kHz.

On the other hand, there has been reported an optical disk device capable of reproducing data without adjusting the rotation speed of the optical disk by increasing the capture range of the reproduction phase synchronization circuit (Nikkei Electronics 1995 2.
13 no. 628 pp 111-119).

[0007]

However, in the optical disk apparatus according to the above-mentioned Japanese Patent Laid-Open Publication No. Hei 6-338066, there is a problem that data cannot be recorded until the frequency of the meandering signal becomes constant, that is, until the CLV control is settled. .

In general, the higher the linear velocity for high-speed recording, the longer it takes to adjust the number of revolutions (set the CLV), so that the access time during recording cannot be shortened.

In the optical disk apparatus reported to Nikkei Electronics, in order to shorten the access time at the time of reproduction, the capture range of the reproduction phase synchronization circuit (PLL circuit) is widened so that the data can be read even if CLV control is not settled. Although reproduction is enabled to shorten the access time during reproduction, no mention is made of recording.

In order to speed up the start of recording, the setting of the CLV control may be speeded up. However, the capacity of the rotary motor is limited, and if the control band is increased to speed up the CLV setting, the FM component of the address will be mixed into the control of the linear velocity, resulting in linear velocity jitter and accurate data. There is a problem that recording cannot be performed.

In such a case, by obtaining the recording clock from the meandering signal of the guide groove, CAV (constant angular velocity) recording can be performed, thereby reducing the load of the rotation control and increasing the access speed.

However, since the address signal is frequency-modulated in the meandering signal, an FM component is included in the recording clock, and the FM component appears as jitter during reproduction.

Therefore, at the time of reproduction, the frequency component of the reproduction signal is corrected by extracting the FM component of the guide groove.
It is possible to cancel the mixing of FM components,
Such a process is a correction performed at the time of reproduction. For this reason, it is necessary to separately provide a circuit in the reproduction device, which causes a problem of an increase in cost.

Further, since an FM component is mixed in the recording data itself, there is a problem that it is difficult to reproduce the data by a conventional general reproducing apparatus having no correction circuit.

Therefore, the present invention solves the above-mentioned problems, reduces the load on the rotation control and speeds up the access time,
Also, by making the recording clock not include the FM component,
It is an object of the present invention to provide an optical disk device capable of recording data so that a conventional reproducing device can easily reproduce the data.

[0016]

According to the first aspect of the present invention, information is recorded / reproduced by condensing a laser beam on a recording track of an optical disk having a spiral guide groove meandering in a radial direction. A meandering signal extracting means for extracting a meandering signal of the guide groove, an FM demodulating means for extracting a frequency modulation component of the meandering signal, a clock generating means for generating a multiplied clock synchronized with the meandering signal, The frequency of the multiplied clock is corrected by the component,
Frequency correction means for generating a recording clock is provided.

According to a second aspect of the present invention, the FM demodulating means includes a PLL means for synchronizing the phase with the meandering signal, and the frequency correcting means extracts a frequency control input of the first variable frequency oscillator constituting the PLL means. The frequency control input of the second variable frequency oscillator constituting the clock generating means is added or subtracted at a predetermined ratio, and the result is used as the frequency control input of the second variable frequency oscillator. And

The invention according to claim 3 is characterized in that the control gains of the first variable frequency oscillator and the second variable frequency oscillator are made substantially the same.

According to a fourth aspect of the present invention, the frequency correcting means takes out the frequency control input of the first variable frequency oscillator and adds or subtracts it to the frequency control input of the second variable frequency oscillator at a predetermined ratio. In this case, the ratio is made variable, and the ratio is automatically adjusted so that the FM component included in the recording clock is minimized.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to the drawings. The optical disc 1 is formed with a spiral guide groove in the same manner as described in the description of the prior art, and the guide groove is
LV (Constant Linear Veloci)
ty: constant spatial frequency (for example, 17000 Cycle / m: 1) so that rotation control at a constant linear velocity is possible.
It is meandering in the radial direction of the optical disc by a small amount (for example, about 0.03 μm) at 59 μm per cycle). In addition, address information is FM (frequency modulated) and superimposed on the frequency of the meandering signal (wobble signal).

FIG. 1 is a diagram showing a circuit configuration for generating a recording clock in the optical disk device according to the present embodiment. In the figure, reference numeral 2 denotes a rotation motor,
To rotate. The rotation may be either CAV (constant angular velocity) or CLV. Reference numeral 3 denotes an objective lens which collects laser light emitted from a known optical system provided in the optical head 4 and irradiates a laser spot on the recording surface of the optical disc 1.

5 is a tracking error signal detection circuit,
The reflected light detected by a known tracking error detection optical system (for example, a Push-Pull method) included in the optical head 4 is calculated to output a tracking error signal.

The tracking error signal has a positive or negative value according to the radial distance between the laser spot and the guide groove in the optical disk, and becomes zero when the laser spot is on the guide groove.

Since the guide groove meanders in the radial direction of the optical disk 1 as described above, a meandering signal is detected in accordance with the rotation of the disk.

Reference numeral 6 denotes a bandpass filter, which passes near the center frequency of the meandering signal. This serves to improve the S / N of the meandering signal. In the case of CAV rotation,
Since the frequency of the meandering signal detected varies depending on the radius position to be accessed, it is preferable that the center frequency of the pass frequency is set to be variable.

Reference numeral 7 denotes a comparator, which zero-cross-slices the output of the band-pass filter 6 and obtains a binarized meandering signal based on the output from the comparator 7.

Reference numeral 8 denotes a frequency multiplier (Frequency).
A recording clock (Write Clock) having a frequency that is a constant multiple of the meandering signal is generated by the Multiplier, and its oscillation frequency is corrected by the frequency control signal of the FLL circuit 13.

Although a detailed description of the frequency multiplying circuit 8 will be described later, it is added that it can be realized by the technology of the PLL synthesizer.

A buffer memory 11 stores data to be recorded. Reference numeral 10 denotes a modulator which takes out data to be recorded from a buffer memory 11 in synchronization with a recording clock, and records serial recording pulse train recording data (Wri).
te Data).

Numeral 9 denotes a laser driving circuit which intensifies the intensity of a laser light source provided in the optical head 4 according to recording data and emits a laser beam used for recording.

The meandering signal from the comparator 7 is output to the PLL circuit 1
3 is also input. The PLL circuit 13 generates a clock (PLL Wobble) that is phase-synchronized with the meandering signal.
Clock). The PLL circuit 13 has a voltage controlled oscillator inside, outputs a clock proportional to a frequency control signal corresponding to the output of the phase comparator, and outputs this frequency control signal as a frequency correction signal of the frequency multiplying circuit 8.

Reference numeral 12 denotes an amplifier having a variable gain, which will be described later in detail. Reference numeral 14 denotes a Takashiro filter that allows only the high-frequency component of the frequency correction signal to pass therethrough, and cuts off the FM component while setting the frequency control signal band for controlling the frequency multiplier 8 to be cut off. Is preferred.

With the above configuration, the frequency of the frequency multiplier 8 synchronized with the meandering signal is corrected by the frequency control signal of the PLL circuit 13 synchronized with the meandering signal. In the state where there is no correction due to the influence of the meandering signal being FM-modulated, the recording clock from the frequency multiplying circuit 8 is 4.5718 MHz and 3.9298 MHz as shown in FIG. Is FM-modulated.

The frequency of the frequency control signal output from the PLL circuit 13 is also FM-modulated. Therefore, when the oscillation frequency of the frequency multiplier 8 is corrected by the frequency control signal of the PLL circuit 13, the FM component included in the recording clock output from the frequency multiplier 8 can be canceled.

Here, since only the FM component is to be corrected, only the high frequency component of the original frequency control signal needs to be used. For this purpose, it is preferable to output the frequency control signal from the PLL circuit 13 to the frequency multiplying circuit 8 through the high frequency filter 14.

FIG. 2 is a detailed configuration diagram of the frequency multiplier 8 and the PLL circuit 13. In the figure, reference numeral 81 denotes a phase comparator which outputs a phase difference between the meandering signal and the output of the frequency divider 85. A low-pass filter 82 smoothes the phase difference signal output from the phase comparator 81. An amplifier 83 amplifies the smoothed phase difference signal from the low-pass filter 82 and outputs the amplified signal to a voltage controlled oscillator 84 as a frequency control signal. Also 8
Reference numeral 6 denotes a subtractor, which outputs the output signal of the amplifier 83 to the amplifier 12.
Is subtracted from the frequency control signal from the PLL circuit 13 input through the.

The voltage-controlled oscillator 84 outputs a recording clock having a frequency proportional to the frequency control signal from the subtractor 86, and the recording clock is frequency-divided by the frequency divider 85 to a frequency of 1 / N. It is preferable that N is set to a ratio (for example, 196) between the center frequency (for example, 22.05 KHz) of the meandering signal and the channel bit rate (for example, 4.3218 MHz) of the recording data.

As a result, the frequency multiplying circuit 8 outputs a recording clock having a frequency N times the frequency of the meandering signal. Here, the gain of the amplifier 83 determines the loop loop band of the frequency multiplier 8. This loop band is preferably set higher than the frequency band in which the rotation of the rotary motor fluctuates. This is because the recording data needs to be completely synchronized with the center frequency of the meandering signal. If the loop band is low, the recording clock cannot follow the rotation fluctuation component.
This is because the recorded data is completely out of synchronization.

The PLL circuit 13 has substantially the same configuration as the frequency multiplication circuit 8. 31 is a phase comparator, which is a meandering signal and an output clock (PLL W) from the voltage controlled oscillator 35.
, and outputs a phase difference. A low-pass filter 32 smoothes the phase difference signal from the phase comparator 31. An amplifier 33 amplifies the phase difference signal smoothed by the low-pass filter 32 and outputs the amplified signal as a frequency control signal of the voltage controlled oscillator 35.

The voltage controlled oscillator 35 has a clock (PLL Wobble Cl) having a frequency proportional to the frequency control signal.
ock), and the clock is divided by the frequency divider 36 into 1 / N
Frequency. N is preferably set to the ratio (for example, 196) between the center frequency of the meandering signal (for example, 22.05 KHz) and the channel bit rate of the recording data (for example, 4.3218 MHz). Here, the frequency control signal for controlling the oscillation frequency of the voltage controlled oscillator 35 is subtracted from the frequency control signal for controlling the voltage controlled oscillator 84 of the frequency multiplier 8 via the amplifier 12 and the high-pass filter 14 so as to be subtracted. 86.

The frequency multiplying circuit 8 and the PLL circuit 13 are
As described above, the multiplication PLL configuration is substantially the same. With such a configuration, the amount of extraction of the FM component from the meandering signal becomes substantially the same, and there is an advantage that the subtraction facilitates cancellation.

In particular, by setting the characteristics of the voltage controlled oscillator 84 and the voltage controlled oscillator 35, that is, the relationship between the frequency control input and the oscillation frequency to be the same, the frequency multiplying circuit 8 and the PL
The frequency control signal with the L circuit 13 can be set to substantially the same level, whereby the FM component can be canceled more reliably.

Next, a second embodiment will be described. The optical disk device according to the present embodiment is a device that varies the gain of the amplifier 12 in FIGS. 1 and 2 and adjusts the gain of the amplifier 12 so that the FM component of the recording clock output from the frequency multiplier 8 is minimized. It is. FIG.
Is a diagram showing the configuration. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

In the figure, reference numeral 21 denotes a high-frequency filter, which extracts a high-frequency component of the frequency control input Vc input to the voltage-controlled oscillator 84, that is, an FM modulation component. An absolute value circuit 22 outputs the absolute value of the extracted FM component. The absolute value is used because the FM component takes a positive or negative value, and if the averaging process is performed as it is, the value becomes zero. The band of the high-pass filter 21 is the frequency of the meandering signal FM.
A band that allows components to pass through.

A controller 23 measures the absolute value of the FM component and outputs an adjustment command GC for the amplifier 12. The controller 23 is a memory, FM
It can be realized by a general microcomputer having an A / D converter for component measurement and a D / A converter for GC output.

FIG. 4 shows an algorithm of the controller 23. Here, it is assumed that the optical disk device has already rotated the optical disk and a meandering signal has been input to the frequency multiplication circuit 8 and the FLL circuit 13. The adjustment operation may be performed before the optical disk is inserted and the actual data reproduction is started, or may be performed at all times during the actual data recording.

In step S1, the amplitude of the FM component is measured and stored in a memory each time the adjustment command GC is variously changed. In the memory, for example, a table format as shown in FIG. 6 is stored, and a numerical value is set in an arbitrary unit.

In step S2, the measurement result (that is, the table shown in FIG. 6) is searched to find an adjustment command GC that minimizes the amplitude of the FM component. In the example of FIG. 6, F is set when the adjustment command GC = 4.
The amplitude of the M component is minimized.

Of course, if the adjustment command GC is obtained by performing interpolation complementation based on an appropriate function approximation instead of such a simple method, a more accurate adjustment command GC can be obtained. Then, in step S3, the found adjustment command GC is output to the amplifier 12.

The degree to which the FM component is mixed in the recording clock differs even if the gain of the amplifier 12 is the same, due to the difference in characteristics between the frequency multiplication circuit 8 and the PLL circuit 13.

Therefore, by adjusting the gain of the amplifier 12 as described above, variations in circuit characteristics can be absorbed and inexpensive components can be used. Further, by automatically adjusting the gain, the adjustment in the manufacturing process is not required, and the cost can be reduced.

[0052]

According to the first aspect of the present invention, a meandering signal extracting means for extracting a meandering signal of the guide groove, an FM demodulating means for extracting a frequency modulation component of the meandering signal, and a multiplication synchronized with the meandering signal. A clock generating means for generating a clock, and a frequency correcting means for generating a recording clock by correcting the frequency of the multiplied clock by a frequency modulation component, so that the clock is synchronized with the meandering signal and included in the meandering signal. Data recording can be performed with a recording clock with no jitter and no jitter.

As a result, data can be recorded on the optical disk at an accurate linear density without performing precise CLV rotation control, and the recording operation can be started without waiting for the control of the rotary motor. Access time can be shortened.

Further, even if the optical disk is rotated at CAV, recording can be performed at a constant linear density, so that there is no need to shift the rotating motor in the motor control system, and cost and power consumption can be reduced.

Further, since the FM component is not mixed into the recording clock, the reproduction can be easily performed by the conventional reproducing apparatus.

According to the second aspect of the present invention, the FM demodulation means includes PLL means for phase-locking to the meandering signal, and the frequency correction means includes a frequency control input of the first variable frequency oscillator constituting the PLL means. Was taken out and added or subtracted at a predetermined ratio to the frequency control input of the second variable frequency oscillator constituting the clock generating means, and the result was used as the frequency control input of the second variable frequency oscillator.
The frequency control input of the variable frequency oscillator of the clock generating means, which is also phase-locked to the meandering signal, is corrected by the FM component accurately phase-locked by the LL means, thereby enabling more accurate removal of the FM component.

According to the third aspect of the present invention, the control gains of the first variable frequency oscillator and the second variable frequency oscillator are made substantially the same, so that the frequency control signals of both become substantially the same level, The components can be more reliably canceled.

According to the present invention, the ratio is made variable and the ratio is automatically adjusted so that the FM component included in the recording clock is minimized. Therefore, the FM component is mixed in the recording clock. The degree to which the frequency
Even if the difference is caused by the difference in the characteristics from the LL circuit, the above-described adjustment can absorb the variation in the circuit characteristics and use inexpensive components.

Further, by automatically performing the adjustment, the adjustment in the manufacturing process becomes unnecessary and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an optical disk device applied to the description of an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a main part of the optical disk device of FIG. 1;

FIG. 3 is a diagram illustrating a configuration of an adjusting unit that adjusts a gain of an amplifier.

FIG. 4 is a flowchart showing a procedure for adjusting the gain of the amplifier.

FIG. 5 is a diagram illustrating a temporal change in the frequency of a recording clock.

FIG. 6 is a diagram showing a storage configuration of a memory for storing data acquired when adjusting the gain of the amplifier.

[Explanation of symbols]

 Reference Signs List 3 Objective lens 4 Optical head 5 Tracking error signal detection circuit 6 Bandpass filter 7 Comparator 8 Frequency multiplication circuit 9 Laser drive circuit 10 Modulator 11 Buffer memory 12, 83 Amplifier 13 PLL circuit 14, 21 High-pass filter 22 Absolute value circuit 23 Controller 31, 81 Phase comparator 32, 82 Low-pass filter 35, 84 Voltage controlled oscillator 36, 85 Divider 86 Subtractor

Claims (4)

[Claims] An optical disc apparatus for recording / reproducing information by condensing a laser beam on a recording track of an optical disc on which a spiral guide groove meandering in a radial direction is formed.
Meandering signal extracting means for extracting a meandering signal of the guide groove;
FM demodulating means for extracting a frequency modulation component of the meandering signal, clock generating means for generating a multiplied clock synchronized with the meandering signal, and correcting the frequency of the multiplied clock by the frequency modulation component, thereby obtaining the recording clock. An optical disk device comprising: a frequency correction unit that generates a frequency. 2. The FM demodulation means comprises PLL means for phase-locking to the meandering signal, and the frequency correction means comprises:
The frequency control input of the first variable frequency oscillator constituting the PLL means is taken out and added or subtracted at a predetermined ratio to the frequency control input of the second variable frequency oscillator constituting the clock generating means. 2. The optical disk device according to claim 1, wherein the result is used as a frequency control input of a second variable frequency oscillator. 3. The first variable frequency oscillator and the second variable frequency oscillator
3. The optical disk apparatus according to claim 2, wherein the control gain of the variable frequency oscillator is substantially the same as that of the variable frequency oscillator. 4. The optical disk apparatus according to claim 2, wherein said ratio is variable, and said ratio is automatically adjusted so that an FM component included in said recording clock is minimized.