KR0176897B1 - Focus search and focus auto-gain control method of optic disk player - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a focus search and a focus auto gain control method of an optical disc player. In the related art, it is difficult to detect a phase when the surface of a disc is not clean at the time of focus search, and has a problem of inferior accuracy. Accordingly, the present invention allows the user to perform the focus search operation and the focus auto gain control at the same time, thereby increasing the accuracy of the gain control to the user and preventing the microcomputer from receiving time constraints.

Description

Focus search and auto gain control method of optical disc player

1 is an automatic gain control (AGC) circuit diagram of a conventional optical disc player.

FIG. 2 is a phase diagram showing (1-G1xG2) and (1 + G1xG2) in FIG.

3 is a signal waveform diagram during focus search in a conventional optical disc player.

4 is a process diagram showing a focus search method of a conventional optical disc player.

5 is a configuration diagram of a focus servo device of the optical disc player of the present invention.

6 is a block diagram of an automatic gain control device for an optical disc player of the present invention.

7 is a sine wave signal diagram filtered in FIG. 6 with respect to the corrected sine wave and the sine wave.

8 is a signal waveform diagram in FIG.

9 is a flowchart illustrating a method of focus search and automatic gain control of an optical disc player according to the present invention.

* Explanation of symbols for main parts of the drawings

10: band pass filter 20: maximum / minimum value detection unit

30: sine wave generator 40: maximum / minimum value and phase detector

50: gain control unit 60: compensation filter

70: digital / analog converter 80: disk system

90: analog / digital converter 100: low pass filter

110: FZC generator

The present invention is to perform an automatic gain control (AGC) and a focus search operation in an optical disc player at the same time, and in particular, when having an automatic gain control function that an analog servo of an optical disc player does not have and at the same time loading and playing a disc in a play. SUMMARY OF THE INVENTION An object of the present invention is to provide a focus search and focus auto gain control method for an optical disc player that simultaneously performs a focus search function that allows a focus servo to enter a range possible.

The automatic gain control circuit of the conventional optical disc player, as shown in FIG. 1, obtains an optical error from an output of the first adder, which adds an input reference signal and a feedback signal, and obtains the obtained error signal. And a third adder for adding an output signal of the first transmitter, an output signal of the second adder that adds an output signal and a wobbling signal, and a third adder that adds an output signal of the first transmitter. A phase detector for detecting a phase with respect to the output signal of the third adder, an average calculator for averaging the phase detected through the phase detector, and data input from the second adder and the average calculator, And a second transmitter for generating a signal to be driven and feeding it back to the first adder.

Looking at the conventional technology configured as described above are as follows.

When the reference deviation R, that is, the vertical deviation of the disk with respect to the focus servo or the light deviation with respect to the tracking servo is input to the first adder 1, a signal A obtained by adding an actuator driving signal fed back and inputted to the first adder 1 is added. Output to the 2nd and 3rd adders 3 and 4 respectively via the transmission part 2. FIG.

Then, the second adder 3 receives and adds a bubbling signal X having a reference frequency of Gain-Crossover Frequency (FGC) and outputs the added signal B to the second transmission unit 7. The third adder 4 adds the output signals of the first transmitter 2 and the second adder 3 and outputs them to the phase detector 5.

The phase detection unit 5 receives the bubbling signal X and the addition signal of the third adder 4, calculates the phases thereof, and outputs the phases to the average calculation unit 6 to calculate the average of the phases to calculate the average of the phases. 7)

Accordingly, the second transmission unit 7 generates a signal for driving the actuator using the addition output of the second adder 3 and the phase average value of the average calculating unit 6 and outputs the signal to the first adder 1.

If you do this, you get the equation

Then, the gain is set to 1 when the phase is 90 degrees using the phase detector 5.

In other words,

Calculate by putting the part to zero.

However, in the prior art as described above, when the surface of the disc is not clean, it is very difficult to detect the phase, and in accuracy, the accuracy is lowered because the calculation is made by leaving (a) to 0.

In the case of focus search, the optical disc player is driven by the driving voltage as shown in (a) of FIG. 3, and the focus error FE as in (b) occurs. The position of the focus zero cross FZC.

At this time, if the focus zero cross FZC falls to a low state as shown in FIG. 3C in the same process as in FIG. 4A, the focus servo operation is turned on by turning on the focus servo loop by a microcomputer not shown. In this case, if the focus ok signal is checked and the focus state is high, the focusing is in the correct position, and the latch is transmitted after the $ 08 shown in (a) is transmitted.

Also, as shown in (b) of FIG. 4, after the $ 08 value has been transmitted, the focus ok signal FOK becomes high, and when the focus zero cross FZC falls low, the transmitted value is latched.

The focusing search is performed in the same manner as in FIG. 4 (a) (b).

However, in the above technique, when the time interval of the S-curve becomes narrow during the focus servo operation, it is difficult to turn on the focus, and when noise is added to the S-curve, the focus zero cross (FZC) comes out of focus quickly or lately. -There is a problem such as the case that the temperature does not turn well.

Accordingly, an object of the present invention to solve the problems of the automatic gain control (AGC) and focusing search as described above, the focus servo is to perform the automatic gain control that the analog servo of the optical disc player does not have SUMMARY OF THE INVENTION An object of the present invention is to provide a focus search and a focus auto gain control method of an optical disc player capable of performing a focus search operation to enter a range.

The method of the present invention for achieving the above object, the first step of generating a sine wave of about 30Hz when the automatic gain control (AGC) command input, and after removing the compensation and noise for the sine wave generated in the first step A second step of turning on the focus servo by detecting the FZC position; a third step of generating a sine wave corresponding to the FGC at the time of focus servo-on; and a sine wave in the sine wave generated in the third step. And a fourth step of comparing the maximum / minimum values of the sine waves with the compensation and noise removed with their phases, and a fifth step of automatically adjusting the gain according to the result of the comparison in the fourth step.

As shown in FIG. 5, a focus servo device of the optical disc player of the present invention for performing the method comprising the above steps includes a sine wave generating a sine wave of about 30 Hz when transmitting an AGC command. Means, a compensation filter for filtering the sine wave generated from the sine wave generating means for compensation, digital / analog conversion means for converting a value of the sine wave compensated through the compensation filter into an analog signal, and With respect to a disk system for driving a disk by a signal transmitted from a digital / analog converting means, analog / digital converting means for converting a signal generated from the disk system into a digital value, and a signal transmitted from the analog / digital converting means. Low Pass Filter Filters to Remove Noise From Disk Systems And FZC generating means for finding the FZC position of the sine wave generated from the signal or sine wave generating means filtered through the low pass filter and turning on the focus servo at the position.

The automatic gain control device configuration of the optical disc player of the present invention, as shown in FIG. 6, includes sine wave generating means for generating a sine wave corresponding to the Gain-Crossover Frequency (FGC) of the entire system, and the servo. A correction filter for stabilizing the system, digital / analog conversion means for converting the digital value passed through the filter into an analog signal, a disk system for driving the disk by an analog signal transmitted from the conversion means, and the disk. An analog / digital conversion means for converting an analog signal generated from the system into a digital value, a selection switch for controlling and outputting an output signal of the analog / digital conversion means in accordance with a gain control signal, and filtering data transmitted from the selection switch. To remove noise generated by the disk system Depass filter, the maximum / minimum value detection means for detecting the maximum value and the minimum value of the data transmitted through the filter, and the maximum comparing the maximum / minimum value and phase of the data generated from the detection means and the sine wave generating means, respectively Control means for controlling the gain of the value transmitted from the analog / digital conversion means according to the comparison difference between the minimum value and the phase comparison means and the comparison means.

When described in detail with respect to the operation and effect of the present invention configured as described above.

When the AGC command is transmitted from the microcomputer, when the sine wave generator 30 of FIG. 5 generates a sine wave value of about 30 Hz, the correction value filtered by the compensation filter 60 is digital / The analog converter 70 converts the analog signal into an analog signal and provides it to the disk system 80.

Accordingly, the analog signal generated as the disk system is driven and driven is converted into a digital value by the analog / digital converter 90 and filtered by the low pass filter 100 to be provided to the FZC generator 110. The reason for this is to remove various noises generated in the disk system 80.

The FZC generation unit 110 finds the position of the zero point of the output signal generated by the disk system 80 and turns on the focus servo at the found position.

After doing this, if the sine wave generator 30 shown in FIG. 6 occurs in FIG. 8 (b) corresponding to the Gain-Crossover Frequency (FGC) of the entire system, the sine wave in the compensation filter 60 is generated. The filtered value is transmitted to the digital / analog converter 70 to compensate for the sine wave value to be converted into an analog signal.

The converted analog signal is selected by driving the disk system 80 and converting the analog signal having various noises as shown in (a) of FIG. 8 into a digital value through the analog / digital converter 90. Passed to switch SW.

The signal transmitted in this way is a gain OK signal, that is, if the gain generated from the sine wave generator 30 to the band pass filter does not become 1, the gain controller 50 adjusts the gain of the band pass filter to adjust the gain. Let it be 1.

In this way, the select switch sw switches to the gain control unit, and the gain control unit adjusts the gain of the output of the analog / digital converter and sends it to the compensation filter.

For example, if the gain OK signal does not come out, when the signal of the disk system 80 is transmitted to the band pass filter 10, band pass filtering is performed to remove various noises generated from the system 80. Transfer to the minimum value detector 20.

Accordingly, when the maximum / minimum value detector 20 detects the maximum value and the minimum value of the transmitted data value and transfers the maximum / minimum value and the phase comparator 40, the maximum / minimum value and the phase comparator 40 are corrected. The sine wave value and the maximum / minimum value of the sine wave value of the uncorrected sine wave generator 30 are compared with their phases, and the result of the comparison is output to the gain control unit 50.

Then, the gain controller 50 adjusts the gain so that the gain is the same when the result of the comparison between the maximum / minimum value and the phase comparator 40 is different from each other, and delivers the gain to the band pass filter 10 so that the gain is 1. To be

At this time, the closer and narrower the bandwidth of the band pass filter 10 is, the easier it is to check the maximum value and the minimum value by the maximum / minimum value detection section 20. Since the phase delay of the band pass filter 10 is known in advance, The time difference between the maximum value of the generator 30 can be obtained by the maximum / minimum value and the phase comparator 40 to obtain the phase margin at the time of FGC.

In FIG. 7, the solid line is a signal generated by the sine wave generator 30, and the dotted line is a signal passed through the band pass filter 10, and the frequency of the FGC is relatively higher than the conversion time of the analog / digital converter 90. If the noise is excessive even after passing through the band pass filter 10, the area of the sine wave of the sine wave generator 30 instead of the maximum / minimum value and the minimum value of the phase comparison unit 40, that is, hatched in FIG. 7. It can be replaced by a function of comparing the area ratio of the signal passing through the parent portion and the band pass filter 10.

In this case, the gain is determined by the gain control unit 50 so that the ratio of the area is 1 after obtaining the sum for a predetermined time.

In addition to the focus search and focus auto gain control described above, the tracking auto gain control can be used as follows.

After focus search and focus auto gain control, turn on the servo and turn the disk relatively slowly so that the disk is not affected by eccentricity during tracking auto gain control.

After this, the sine wave generator 30 generates the tracking FGC to move the tracking actuator through the compensation filter 60, the digital / analog converter 70, and the disk system 80.

The gain may be adjusted in the same manner as the focus auto gain control method after filtering the tracking error generated by the tracking actuator through the band pass filter 10.

As described in detail above, the present invention allows the user to simultaneously perform the focus search operation and the focus auto gain control, thereby increasing the accuracy of the gain control to the user and preventing the microcomputer from receiving time constraints.

Claims (2)

A first step of generating a sine wave of several tens Hz when an AGC command is input, and a second step of detecting a FZC position after removing the compensation and noise for the sine wave generated in the first step to turn on the focus servo. And a third step of generating a sine wave corresponding to the FGC at the focus servo-on in the second step, and a sine wave in which the sine wave generated by the third step is compensated for the sine wave and noise is removed. And a fifth step of comparing a minimum value with their phases, and a fifth step of automatically adjusting gains according to the result of the comparison in the fourth step. The focus search and focus auto gain control method of an optical disc player according to claim 1, characterized in that it can be used not only for focus servo but also for tracking servo.