JPH04205725A - Optical disk driving device - Google Patents

Abstract

PURPOSE:To obtain an optimum seek characteristic and read characteristic by setting an offset value to maximum in the amplitude of tracking difference signals at the seek time and in the amplitude of tracking sum signals at read time. CONSTITUTION:A CPU 9 controls a selector 8, sets an offset value in which the amplitude of the tracking difference signals is the maximum at the seek time, and the value is outputted to a D/A converter 13. Also, the CPU 9 sets the offset value in which the amplitude of the tracking sum signals is the maximum at the red time, and the offset value is outputted to the D/A converter 13. Meantime, a subtracter 16 detects Fo errors from reflected light received at FoPD 15, and the errors are outputted to an adder 14. The adder 14 adds the Fo error signals and the offset value from the converter 13 and outputs it to a phase compensating circuit 17. Thus, an optical head is moved to the optimum position to execute seeking and reading.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical disc drive device that performs focus offset control.

[Prior art] In conventional optical disk drive devices, an optimal focus offset value (hereinafter referred to as offset value) that allows both seek and read is set, and the focus position of the optical head is set to the optimal position for seek and read. I'm trying to make it happen.

However, since the optimal offset values during seek and read normally do not match, the optimal offset value is set for each seek and read, as seen in Japanese Patent Application Laid-Open No. 64-57427.

That is, as shown in FIG. 3, in (a) the optical head 1
irradiates the optical disc 2 with a spot light, receives the reflected light from the optical disc 2, and outputs it to the focus servo control unit 3. In addition, the focus offset switching circuit 4
is the offset value Vs set for each seek and read as shown in FIG. 3(b).
, Va, and set the respective offset values V
s.

Va is output to the focus servo control section 3. here,
The offset value Vs during seek is used to set the focus position at a position where the amplitude of the difference signal of the tracking signal is maximum. Also, the offset value V when reading
In step a, the focus position is set at a position where reading can be performed optimally.

The focus servo control unit 3 obtains a focus error signal from the light reception signal of the optical head l, and based on this focus error signal and the offset value from the focus offset switching circuit 4, the focus servo control unit 3 adjusts the focus position to the optimum focus position each time a seek or read is performed. The position of the optical head 1 is controlled so that

In this way, optimal seek and read characteristics are obtained by setting the optimal offset value for each seek and read.

[Problem to be solved by the invention] However, in such an optical disk drive device, even if the offset value is set at the optimal position where both seek and read can be performed, the offset value must be changed for each seek and read. In this case, the set offset value is also a preset value.

On the other hand, optical discs loaded into optical disc drive apparatuses experience different surface runout and track runout due to warpage and waviness that occur during the molding process and eccentricity that occurs during the processing process. Therefore, even if the offset value is optimal for a certain optical disc, it is not necessarily the optimal offset value for other optical discs.

In other words, even if the offset value is once set to provide the optimal focus position for the seek and read operations of the optical disc drive device, it may not always be possible to obtain the optimal seek and read characteristics no matter what optical disc is loaded. do not have.

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical disc drive device that can always set an optimal offset value no matter what optical disc is loaded, and can always perform stable tracking and stable signal reproduction.

[Means for Solving the Problems] The present invention provides a means for receiving reflected light from an optical disk to obtain a tracking signal, a means for generating a difference signal between the tracking signals, and a focus detecting a focus error from a focus light reception signal. an error detection means; an addition means for adding the focus error and the offset value;
An optical disk drive device comprising means for controlling a servo system based on the added value, means for generating a sum signal of the tracking signals, and a switching means for outputting only one of the sum signal and the difference signal. , A/A converts the output from this switching means into a digital signal and outputs it.
D conversion means, means for detecting the maximum value and minimum value of the output from the A/D conversion-four stages;
means for obtaining the maximum amplitude from the maximum and minimum values, and D for converting the offset value indicating the maximum amplitude and any offset value into an analog signal and outputting it to the addition means.
/A conversion means.

[Operation] As a result, the offset value during seek is set so that the amplitude of the tracking difference signal is maximized, so that stable seek can be performed. Further, during reading, the offset value is set so that the tracking sum signal becomes the maximum, so that stable reading can be performed.

[Embodiments] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

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

In the same figure, TRPD5 is a tracking signal (hereinafter T
It is a photodiode that detects the R signal), and the T
The R signal adder 6 adds the TR signals detected by the TRPD 5 and outputs a TR sum signal, and the TR signal subtracter 7 subtracts the TR signals and outputs a TR difference signal.

The selector 8 sends either the TR sum signal from the TR signal adder 6 or the TR difference signal from the TR signal subtracter 7 to the A/D converter 0 in response to a control signal CNT from the control CPU 9, which will be described later. Switch to input.

The A/D converter 10 converts the input TR sum signal or TR difference signal into a digital signal and outputs it to the peak detection circuit 11 and the bottom detection circuit 12. Peak detection circuit 11
detects the maximum value of each of the TR sum signal or TR difference signal converted into a digital signal by the A/D converter 10, and the bottom detection circuit 12 detects the minimum value of each of the TR sum signal or TR difference signal. .

The control CPIJ9 performs control to switch the selector 8 to the TR difference signal side during seek and to the TR sum signal side during read. In addition, this control CPU9
is determined by the maximum value of the TR sum signal or TR difference signal detected by the peak detection circuit 11 and the minimum value thereof detected by the bottom detection circuit 12.
The maximum amplitude of each signal is detected, and the offset value at that time is output to the D/A converter 13. Further, the control CPU 9 outputs a predetermined offset value (typical value) to the 1)/A converter 13 when the power is turned on.

The D/A converter 13 converts the offset value from the control CPU 9 into an analog signal, and the offset adder 14 converts the offset value from the control CPU 9 into an analog signal.
Output to. The FOPD 15 is a photodiode that receives reflected light from the optical disc and detects a focus error (hereinafter referred to as FO error). The FO error signal subtracter 6 detects an FO error from the reflected light received by the FOPD 15 and outputs it to the offset adder 14 as an FO error signal. Offset adder 14 is D/A
The offset value output from the converter 13 and the output from the F○ error signal subtracter 16 are added, and the phase compensation circuit 1
Output to 7.

The phase compensation circuit 17 operates the power amplifier 18 based on the output from the offset adder 14.

The power amplifier 18 rotates the focus morph 19 in accordance with the phase compensation signal from the phase compensation circuit 17 and moves the optical head to an optimal position for seeking and reading.

Next, the focus offset control operation of the optical disk drive device configured as described above will be explained with reference to the flowchart shown in FIG. 2.

First, the power to the optical disc drive device is turned ON and an optical disc is loaded. Next, after moving the optical head to a predetermined track position, a tibial value of the offset value is set (process 20).

Here, the purpose of setting this tibial value is to set the lower limit of the offset value by starting from a predetermined value instead of starting from the offset value 0, and to set the optimal offset value. The purpose is to do this efficiently. This tibial value is set, for example, based on the previous optimal offset value.

Thereafter, when the focus servo is activated to obtain the optimum offset value at the time of seek (21) and the optical head is moved in the focus direction, the TR difference signal due to the eccentricity of the optical disk changes. - On the other hand, when seeking, the control CPU 9 switches the selector 8 to the TR difference signal side (process 22), and inputs this TR difference signal to the peak detection circuit 11 and bottom detection circuit 2 via the A/D converter 10.

The peak detection circuit 1 detects the peak detection circuit 1 from among the input TR difference signals.
1 to find the maximum value, and the bottom detection circuit 12 to find the minimum value and detect the amplitude of the TR difference signal (processing 2
3). This operation is performed sequentially at a predetermined timing, and the maximum amplitude of the TR difference signal is detected by comparing the previous amplitude and the current amplitude (Y in judgment 24). Then, when the focus servo operation for determining the optimal offset value stops and the detection of the amplitude of the TR difference signal is completed (determination 2
5 Y), the offset value indicating the maximum amplitude of the TR difference signal is the optimal offset value for seek. After detecting the optimal offset value for seek, turn on the TR servo to find the optimal offset value for read. If data is not recorded on the track where the optical head is currently located, the optical head is moved to a position on the predetermined track where data is recorded (process 27).

Next, the focus servo is activated at that position to move the optical head in the focus direction (processing 28), and the TRP
The TR sum signal of the TR signals obtained from D5 is changed.

On the other hand, the control CPU 9 now sets the selector 8 to TR.
Switch to the sum signal side (process 29), and convert this TR sum signal to A
The signal is inputted to a peak detection circuit 11 and a bottom detection circuit 12 via a /D converter 10. And this person was sawed T.
The maximum value is determined from the R sum signal by the peak detection circuit 11, and the minimum value is determined by the bottom detection circuit 12 to detect the amplitude of the TR sum signal (processing 30). This operation is performed sequentially at a predetermined timing, and the maximum amplitude of the TR sum signal is detected by comparing the previous amplitude and the current amplitude (Y in judgment 31). When the focus servo operation for determining the optimal offset value is stopped and the detection of the amplitude of the TR sum signal is completed (Y in judgment 32), the offset value indicating the maximum amplitude of the TR sum signal or the optimum value for reading the optical disc is determined. This is the offset value.

Then, when actually performing a seek or read, the offset adder 14 adds the optimal offset value for the seek or read detected in this way and the F○ error signal, and outputs the result to the phase compensation circuit]7. , the power amplifier 18 is activated. This allows the power amplifier 18 to rotate the focus morph 19 and move the optical head to the optimal position for seeking and reading.

Such processing is performed not only when the power is turned on but also at least once after loading the optical disc.

By doing this, even when loading an optical disc such as , it is possible to perform seek and read with the optimum offset value.

[Effects of the Invention] As explained above, according to the present invention, the offset value at the time of seek is set so that the amplitude of the tracking difference signal is maximized. Stable seeks can be performed. Further, during reading, the offset value is set so that the tracking sum signal becomes the maximum, so that stable reading can be performed.

Thereby, optimum seek characteristics and read characteristics can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of an optical disc drive device according to the present invention, FIG. 2 is a flowchart showing a focus offset control operation of the optical disc drive device, and FIG. 3 is a block diagram of a conventional optical disc drive device. 5.TRPD, 6.TR signal adder, 7.TI sentence multiplier signal subtractor 8..Selector, 9..Control C
PtJ, 10...Ha/D converter, 11 - Peak detection circuit, 12 Bottom detection circuit, 13 - D/Δ converter, 1
4...offset adder, 15...FOPD, 16...
...FO error subtractor, 17...phase compensation circuit.

Claims (1)

[Claims] means for receiving reflected light from an optical disk to obtain a tracking signal; means for generating a difference signal between the tracking signals; focus error detection means for detecting a focus error from a focus light reception signal; an addition means for adding
An optical disk drive device comprising means for controlling a servo system based on the added value, means for generating a sum signal of the tracking signals, and a switching means for outputting only one of the sum signal and the difference signal. , A/A converts the output from this switching means into a digital signal and outputs it.
D conversion means, means for detecting the maximum and minimum values of the output from the A/D conversion means, means for obtaining the maximum amplitude from the maximum and minimum values, and a focus offset value indicating the maximum amplitude. and a D/ that converts an arbitrary focus offset value into an analog signal and outputs it to the adding means.
An optical disc drive device comprising: A conversion means.