JPH0553016B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an eccentricity correcting device for an optical disk used for recording and reproducing information.

BACKGROUND ART In recent years, in the tracking control of the optical head of an optical disk, eccentricity correction has been performed to cancel the eccentricity caused by the eccentricity of the disk itself or the center deviation when the disk is installed in the rotation system. . (For example, Japanese Unexamined Patent Publication No. 57-9442) A conventional optical disk eccentricity correcting device will be described below.

FIG. 6 is a configuration block diagram of a conventional optical disk eccentricity correction device, in which 22 is a waveform shaping circuit that shapes a tracking error signal from an optical head (however, the optical head is not shown) into a rectangular wave, and 23 is a waveform shaping circuit. A rising edge detection circuit 24 detects the rising edge of the output signal of the waveform shaping circuit 22 and generates a pulse in response to the rising edge, and 24 detects the falling edge of the output signal of the waveform shaping circuit 22 and generates a pulse in response to the falling edge. 25 is a high-pass filter for removing unnecessary signals from the reproduced signal from the optical head; 26 is an envelope detection circuit for envelope-detecting the output of the high-pass filter 25; 27 is a detection circuit for detecting the envelope of the output of the envelope detection circuit 26; A low-pass filter removes high-frequency components, 28 is a waveform circuit that shapes the output of the low-pass filter 27 into a rectangular wave, and 29 is an AND that takes the AND of the output of the rising edge detection circuit 23 and the output of the waveform shaping circuit 28. 30 is an AND circuit that ANDs the outputs of the fall detection circuit 24 and the waveform shaping circuit 28; 31 is a rotation angle detection circuit that generates a pulse according to the rotation angle of the optical disk; 32 is a rotation angle detection circuit 31; 33 is a memory circuit that stores the outputs of the AND circuits 29 and 30 at the address specified by the counter 32; 34 is the output of the memory circuit 33; 35 is a D/A converter that converts the output data of the up/down counter 34 into an analog signal; and 36 is a linear motor that moves the optical head using the output of the D/A converter 35.

FIG. 7 shows waveforms at each point in the configuration of the conventional optical data eccentricity correction device, and (e)
is the waveform of the tracking error signal from the optical head, (f) is the waveform of the output signal of the waveform shaping circuit 22, and (g) is the waveform of the tracking error signal from the optical head.
is the waveform of the output signal of the rising edge detection circuit 23, (h) is the waveform of the output signal of the falling edge detection circuit 24, (i) is the waveform of the reproduced signal of the optical head, and (j) is the waveform of the output signal of the high-pass filter 25. , (k) is the waveform of the output signal of the detection circuit 26, (l) is the waveform of the output signal of the low-pass filter 27, (m) is the waveform of the output signal of the waveform shaping path 28, and (n) is the output signal of the AND circuit 29. The waveform of (o) is
The waveform of the output signal of the AND circuit 30, (p) is the waveform of the output signal of the rotation angle detection circuit, and (Q) is the waveform of the rotation reference signal, in which one pulse is generated for one rotation of the optical disk. (R) shows the waveform of the output signal of the D/A converter 35.

The operation of the conventional optical disk eccentricity correcting device configured as described above will be described below.

First, the tracking error signal from the optical head is shaped into a rectangular wave (f) by the waveform shaping circuit 22. Next, the detection circuit 23 detects the rise of the rectangular wave (f).
Then, the falling edge is detected by the falling edge detection circuit 24,
Let the signals be (g) and (h).

Next, the reproduced signal (i) of the optical head is filtered through a high-pass filter 25 to remove unnecessary components and become a signal (j).
The detection circuit 26 performs envelope detection to obtain a signal (k), and the low-pass filter 27 converts the signal (k) into a signal (l). Next, the signal (l) is waveform-shaped into a rectangular wave by the waveform shaping circuit 28 to become a signal (m). Next, the AND circuit 29,
30, the signal (m) and the signals (g) and (h) are ANDed.
At this time, when the light spot crosses the track from the outer circumference side to the inner circumference side, the signal (n) pulses, and when the light spot crosses the track from the inner circumference side to the outer circumference side, the signal (o) pulses.
There is a pulse. Next, the rotation angle of the optical disk is detected by the rotation angle detection circuit 31, and a pulse is generated at every predetermined rotation angle as a signal (p), which is counted by the counter 32. Since the counter 32 is cleared by the rotation reference signal (Q), the counter value increases in accordance with the rotation angle of the optical disk, and the signal (n) is sent to the storage circuit 33.
and the state of signal (o) are stored. After the track crossing data for one rotation of the optical disk is stored in the storage circuit 33 as described above, the track crossing data of the storage circuit 33 specified by the output of the counter 32 is input to the up-down counter 34, and the up-down The counter value is D/A converter 35
The eccentricity correction signal (R) is output as an analog eccentricity correction signal (R) to the linear motor 36 for transporting the optical head, thereby correcting the eccentricity.

Problems to be Solved by the Invention However, in the above-mentioned conventional configuration, eccentricity is corrected by determining the direction in which the optical spot crosses the track using the reproduced waveform of the recorded optical disc, so that no recording is performed at all. However, there is a problem in that eccentricity cannot be corrected for disks that do not have the same size.

Means for Solving the Problem In order to solve this problem, the optical disk eccentricity correction method of the present invention generates a reference pulse by a pulse generating means in synchronization with the rotation of the optical disk, and The tracking error signal of the disk is made into a pulse wave by the waveform shaping means, the pulse width of the output of the waveform shaping means is detected by the pulse width detection means, the pulse width group is stored by the first storage means, and the tracking is performed by the calculation means. Calculates the eccentricity correction amount and phase of the disk from the error signal and the pulse width group, stores the calculated eccentricity correction value in a second storage means, and outputs the stored eccentricity correction value via the eccentricity correction value output means. The optical head is input to the transporting means of the optical head, and the optical head is moved in the tracking direction. If there is a phase shift in the eccentricity correction, the phase of the eccentricity correction value is shifted by 180 degrees and then stored in the second storage circuit again. It has a configuration in which eccentricity is corrected by eliminating the phase shift.

Effect With this configuration, the total amount of eccentricity of the optical disk can be obtained corresponding to the rotation angle, and the amount of eccentricity correction can be approximated by this, and if there is a phase shift in the obtained eccentricity correction value, the amount of eccentricity Since the phase of the correction value is shifted by 180° to eliminate the phase shift, eccentricity correction can be achieved even for discs on which no recording has been made. Furthermore, the eccentricity correction amount can be adjusted with any step width regardless of the track pitch size. You can make settings.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic block diagram of the configuration of an optical disk eccentricity correcting device in one embodiment of the present invention, and FIG.
3 is a detailed block diagram, FIG. 4 is a waveform diagram at each part, and FIG. 5 is a flowchart of the calculation means.

In FIG. 1, 1 is a pulse generating means that generates pulses in synchronization with the rotation of the optical disk, 2 is a waveform shaping means that shapes the tracking error signal of the optical disk into a pulse wave, and 3 is the output of the waveform shaping means 2. pulse width detection means for detecting the pulse width of 4;
5 is a calculation means for obtaining an eccentricity correction value from the tracking error signal and the pulse width group; 5 is a first storage means for storing the pulse width group; and 6 is a second memory for storing the calculated eccentricity correction value. 7 is an eccentricity correction value outputting means for outputting the eccentricity correction value from the second storage means 6 to the optical head transfer means 8; 8 is an eccentricity correction value outputting means for outputting the eccentricity correction value from the eccentricity correction value outputting means 7; This is an optical head transport means for transporting the optical head in the tracking direction. In FIGS. 2 and 3, reference numeral 9 denotes a first pulse generation circuit that generates one pulse per rotation in synchronization with the rotation of the optical disk, and 10
11 is a waveform shaping circuit that shapes the tracking error signal of the disk into a pulse wave; 11 is a monostable multivibrator that detects the rising edge of the output of the waveform shaping circuit 10 and generates a pulse of a predetermined width; 12
13 is a second pulse generation circuit that generates pulses with a constant period at sufficiently shorter intervals than the pulse interval of the output pulses of the monostable multivibrator 11; 13 is a second pulse generation circuit that generates pulses with a predetermined frequency; A frequency dividing circuit that divides the frequency into pulses outputs pulse waves of multiple different frequencies. 14 is reset by the output of the monostable multivibrator 11,
a first counter that calculates the number of pulses of a pulse wave output of a predetermined frequency from the frequency divider 13; a latch circuit 15 that holds the value of the first counter 14 at the rising timing of the output pulse of the waveform shaping circuit 10;
16 is a second counter that is reset by the output pulse of the first pulse generating circuit 9 and calculates the number of pulses of the pulse wave output of a predetermined frequency of the frequency divider 13;
17 is a microcomputer that calculates the eccentricity correction amount from the output of the latch circuit 15; 17a is a pulse detection means that detects the rise of the output pulse of the first pulse generation circuit 9 and the output pulse of the monostable multivibrator 11; and 17b is a pulse Detection means 17a
17c is an eccentricity correction value calculation means for calculating an eccentricity correction value from the data of the data storage means 17b; 17d is an eccentricity correction value calculation means 1;
7c, a data output means for outputting the eccentricity correction value calculated by 7c; 18, a data selector for outputting either the output of the second counter 16 or the output data of the microcomputer 17 according to designation; 19, the output of the data selector 18; 20 is a D/A converter that converts the digital signal in the storage circuit 19 into an analog signal; 21 is a linear motor that uses the output of the D/A converter 20 to move the optical head in the tracking direction; be.

In FIG. 4, (a) is the first pulse generating circuit 9.
(b) is the waveform of the tracking error signal which is the output of the optical head input to the waveform shaping circuit 10, (c) is the waveform of the output signal of the waveform shaping circuit 10, (d) is the waveform of the D/ It shows the waveform of the output signal of the A converter 20.

The operation of the optical disk eccentricity correcting device of this embodiment configured as described above will be described below. First, the input of the linear motor 21 which is servoed by the position sensor is kept constant, and the output signal (a) of the first pulse generating circuit 9 is detected by the pulse detecting means 1.
A pulse is detected by 7a. However, the first pulse generating circuit 9 generates one pulse per rotation of the disk. Next, the tracking error signal (b) is shaped into a pulse wave by the waveform shaping circuit 10, and the shaped signal (c) is inputted to the monostable multivibrator 11 and the latch circuit 15. The latch circuit 15 converts the output of the second pulse generation circuit 12 to the frequency divider 1.
The first counter 14 holds the value counted by the first counter 14 of the signal divided by 3 to a predetermined frequency. However, the first counter 14 is a monostable multivibrator 1.
1, the latch circuit 15 holds the number of pulses of the output signal of the frequency divider 13 corresponding to the pulse width of the tracking error signal (c). Become. A pulse is detected from the output signal of the monostable multivibrator 11 by the pulse detection means 17a of the microcomputer 17, and the data held by the latch circuit 15 is stored by the data storage means 17b. In this way, the operation of storing the number of pulses of the output signal of the frequency divider 13 between the pulse widths of the tracking error signal (c) is continued until the next pulse of the first pulse generating circuit 9 is detected. Perform one rotation.

Next, the eccentricity correction value calculation means 17c calculates the total eccentricity by multiplying the number of pulse groups representing the pulse width of the tracking error signal (c) stored in the data storage means 17b by the track pitch. Eccentricity can be approximated by a sine wave at the fundamental frequency. Therefore, by calculating the position of the output signal (a) of the first pulse generation circuit at which the minimum number of pulses is located, the phase of the approximate sine wave can be obtained, and the eccentricity correction can be performed. The value calculating means 17c calculates the phase and calculates approximate sine wave data, that is, eccentricity correction value.

Next, the eccentricity correction values for one rotation of the disk calculated as described above are sequentially stored in the storage circuit 19 via the data selector 18 by the data output means 17d. The number of data to be stored is determined by the signal frequency-divided by the frequency divider 13. Next, the second
The counter 16 specifies the memory circuit 19 via the data selector 18, and the specified eccentricity correction value is converted into an analog signal (d) by the D/A converter 20, which is output to the linear motor 21 to track the optical head. transport in the direction. Since the second counter 16 is reset by the output of the first pulse generating circuit 9, the memory circuit 19 starts outputting data from the beginning every time the disk rotates once. Therefore, the linear motor 21 continues to move the optical head in the tracking direction according to the eccentricity correction value.

Next, while the optical head is being transported by the linear motor 21 as described above, the number of pulses of the output signal of the division period 13 corresponding to one revolution of the disk is stored, and the eccentricity correction value calculation means 17c is used. The total eccentricity is determined and compared with the total eccentricity determined with the linear motor 21 fixed. If the total eccentricity is increased compared to the total eccentricity obtained with the linear motor 21 fixed, the number of pulses of the output signal of the frequency divider 13 obtained with the linear motor 21 fixed is memorized. The data in the data storage means 17b is shifted in phase by 180 degrees and sequentially stored in the storage circuit 19 via the data selector 18 by the data output means 17d. Then, the eccentricity correction value stored in the memory circuit 19 is transmitted to the linear motor 21 via the D/A converter 20.
output and transport the optical head. In this way, eccentricity can be corrected.

The operation of the microcomputer used in this embodiment will be explained below with reference to the flowchart of FIG.

First, with the linear motor fixed, a pulse is detected from the output of the first pulse generation circuit 9, then a pulse is detected from the output of the monostable multivibrator 11, and the data of the latch circuit 15 is stored (step 51). ). This is repeated until the next output pulse of the first pulse generating circuit 9 is detected, and the phase shift of the approximate sine wave is calculated from the position of the minimum data from the stored data group (step 52). The amplitude of the sine wave is calculated from the number (step 53). Next, the calculated sine wave data is stored in the storage circuit 19 (step 54) and output to the linear motor 21 via the D/A converter 20 (step 55). Next, in the same manner as above, the tracking pulse width for one rotation is memorized (step 56).
The amplitude of the sine wave is calculated from the number of tracking pulses (step 57). Next, the amplitude of the former sine wave and the amplitude of the latter sine wave are compared (step 58),
When the latter amplitude is larger, the phase is shifted by 180° (step 59), sine wave data is calculated, stored in the memory circuit 19 (step 60), and sent to the linear motor 21 via the D/A converter 20. (Step 61).

As described above, according to this embodiment, after measuring and storing the pulse width of the tracking error signal of the optical disk, the eccentricity correction value is obtained through arithmetic processing, and if there is a phase shift in the obtained eccentricity correction value, the phase is adjusted. By shifting the disc by 180° to eliminate the phase shift, it is possible to correct eccentricity even on optical discs that do not record at all, and furthermore, the amount of eccentricity correction can be set at any step width regardless of the size of the track pitch. be able to. Furthermore, by using a microcomputer, eccentricity correction can be performed with a simple configuration.

Note that the output of the memory circuit 19 is connected to the linear motor 21.
The means for outputting the signal can also be realized using a staircase wave generation circuit using an analog circuit. In this case, the circuit can be constructed at a lower cost.

Effects of the Invention The present invention measures and stores the pulse width of the tracking error signal of an optical disk, then calculates an eccentricity correction value through arithmetic processing, and if there is a phase shift in the calculated eccentricity correction value, shifts the phase by 180°. By eliminating the phase shift, it is possible to perform eccentricity correction even on optical discs that do not record anything at all.Furthermore, the eccentricity correction amount can be set at any step width regardless of the track pitch size. Accordingly, it is possible to realize an eccentricity correction device for an optical disk.

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram of the configuration of an optical disk eccentricity correcting device in one embodiment of the present invention, and FIG.
3 is a detailed block diagram of the same, FIG. 4 is a waveform diagram of output signals of each part, FIG. 5 is a flowchart of the calculation stage, and FIG. 6 is a block diagram showing the configuration of a conventional optical disk eccentricity correction device. 7 are waveform diagrams of output signals of each part. 1... Pulse generating means, 2... Waveform shaping means,
3...Pulse width detection means, 4...Calculation means, 5...
...First storage means, 6...Second storage means, 7...
...Eccentricity correction amount output means, 8...Optical head transport means.

Claims (1)

[Scope of Claims] 1. Pulse generating means for generating pulses in synchronization with the rotation of the optical disk, waveform shaping means for shaping the tracking error signal of the optical disk into a pulse wave, and pulses output from the waveform shaping means. a pulse width detection means for detecting the width; a first storage means for storing the pulse width detected by the pulse width detection means;
a calculation means for calculating the eccentricity correction amount of the disk and the phase of the output of the pulse generation means from the output of the pulse generation means and the pulse width stored in the first storage means; and a calculation means for storing the calculated eccentricity correction value. an optical head transporting means for transporting the optical head in the tracking direction in synchronization with the rotation of the optical disk using the stored eccentricity correction value; and a second storage means for storing the eccentricity correction value from the second storage means. an eccentricity correction value output means for outputting the eccentricity correction value to the optical head transfer means, and when the amount of eccentricity increases compared to before outputting the eccentricity correction value, the eccentricity correction value is outputted by shifting the phase of the eccentricity correction value by 180 degrees. An eccentricity correction device for an optical disk, characterized in that the device is stored in the second storage means. 2. The pulse width detection means includes a clock generation circuit,
2. The eccentricity correcting device for an optical disk according to claim 1, further comprising a counter for counting pulses output from said clock generating circuit, and a latch circuit for holding the value of said counter.