JP3407315B2 - Optical disk signal processing circuit and optical disk apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is mounted on an optical disk device in which a read-only optical disk or a recordable optical disk is mounted, and the servo gain of a servo system such as a tracking error servo and a focus error servo of the optical disk is obtained. The present invention relates to a signal processing circuit of an optical disk to be adjusted and an optical disk device incorporating the signal processing circuit.

[0002]

2. Description of the Related Art Generally, a disk-shaped recording medium (hereinafter referred to as "recording medium") for recording and / or reproducing an information signal through a light beam.
Examples of the optical disc) include a read-only optical disc, which is a so-called compact disc, and a recordable optical disc, which is capable of recording and erasing information signals as well as reproduction.

A read-only type optical disc has a concavo-convex pattern, that is, a track on which phase pits are formed in concentric circles or spirals on one surface based on a recorded information signal. Specifically, a synthetic resin material disk substrate such as polycarbonate or PMMA having light transmissivity, and Al, Au, etc. formed so as to cover the concavo-convex pattern formed on one surface of the disk substrate. It is formed by a reflective film made of metal and a protective layer formed so as to cover the reflective film for the purpose of protecting the reflective film.

On the other hand, as the recordable optical disk, an optical disk using a phase-change optical recording material, a magneto-optical disk using a perpendicular magnetic recording material, and the like are known. , The latter magneto-optical disk has come to practical use.

In this magneto-optical disk, a guide groove for guiding a light beam is formed on one surface, and a synthetic resin material disk substrate such as polycarbonate or PMMA having a light transmitting property is covered with the guide groove. A recording layer made of a perpendicular magnetic recording material such as Te, Fe, Co, etc., and a protective layer formed so as to cover the recording layer for the purpose of protecting the recording layer. There is.

In the case of the former read-only type optical disk, the method for reproducing these optical disks is such that the light beam from the laser light source built in the optical pickup is focused from the disk substrate side by the objective lens. Irradiate,
The reproduction signal of the information signal recorded on the reproduction-only type optical disk can be obtained by utilizing the diffraction of the light beam reflected by the reflection film of the optical disk by the phase pits of the optical disk.

In the latter case of a recordable optical disk (especially, a magneto-optical disk), a light beam from a laser light source is passed through an objective lens from the disk substrate side in the same manner as the read-only optical disk. By irradiating in a focused state and detecting the Kerr rotation angle in the light flux reflected by the recording layer of the optical disc, a reproduction signal of the information signal recorded on the magneto-optical disc can be obtained.

At the time of reproducing the information signal for the optical disk, the optical pickup generates a reproduction signal and a focus error signal and a tracking error signal associated with the reproduction signal, and these error signals are supplied to the focus servo circuit and the tracking servo circuit. Supply. And
These servo circuits drive two-dimensional actuators (focus actuators and tracking actuators) that move the objective lens of the optical pickup in the contact direction and the radial direction with respect to the optical disc based on the supplied error signal.

In this two-dimensional actuator, the objective lens is moved toward and away from the optical disk based on the drive signal supplied from the focus servo circuit to adjust the focus thereof, and the supplied tracking Based on the drive signal from the servo circuit, the objective lens is moved in the radial direction of the optical disk so that the light beam from the optical pickup can be tracked along the track center.

By the way, in order to stabilize the operation of the servo system including the optical pickup, the two-dimensional actuator, the focus servo circuit and the tracking servo circuit, that is, the focus servo and the tracking servo, the open loop gain of the servo system is used. I am trying to make adjustments. Conventionally, the open loop gain is adjusted when the optical disk device is manufactured.

[0011]

However, in the prior art, due to variations in the characteristics of the optical disk, and changes over time and temperature characteristics of the two-dimensional actuators (focus actuator and tracking actuator) built into the optical pickup, the open loop The gain may fluctuate and the operation of the servo system may become unstable.

Conventionally, various methods have been known in which a correction circuit is newly added to suppress fluctuations in gain in order to avoid the instability of the above-mentioned operation. However, there is an inconvenience that the number of wiring processes is increased and the cost is increased. In addition, variations in accuracy due to temperature changes of the added correction circuit itself may be a problem.

The present invention has been made in view of the above problems, and an object of the present invention is to eliminate the need for adding a correction circuit in order to stabilize the operation of a servo system, and to prevent a change over time and An object of the present invention is to provide a signal processing circuit for an optical disc that can perform stable gain adjustment of a servo system without being affected by temperature characteristics.

Further, according to the present invention, in order to stabilize the operation of the servo system, it is not necessary to add a correction circuit, and moreover, stable gain adjustment of the servo system is possible without being affected by a change with time or a temperature characteristic. It is an object of the present invention to provide an optical disk device capable of performing the above-mentioned operation, reducing the manufacturing cost, and improving the reliability.

[0015]

A signal processing circuit for an optical disk according to the present invention, which is proposed to achieve the above object, includes a first storage section in which sine wave data sin (n) is written. The sampling signal Ps is generated every predetermined sampling period T, and the sampling signal Ps is generated.
In the first storage unit, a sampling timer that generates an interrupt signal Pi after a certain period of s has elapsed, and one servo error signal (Dyf, Dyt) obtained at a sampling time point according to the sampling signal Ps output from the sampling timer. 1 of the written sine wave data sin (n)
One value is added at a predetermined number (N) of sampling points, and the servo error signal (Dxf, Dxt) after addition and the servo error signal (Dyf, Dyt) before addition are calculated to obtain a gain signal βf. , Βt, and a correction unit for correcting the servo error signal (Dyf, Dyt) before addition based on the gain signals βf, βt calculated by the calculation unit. Then, when the interrupt signal Pi is input from the sampling timer and the recording / reproducing operation is not performed, the arithmetic means stores the servo error signal (Dxf, Dxt) after the addition in the second storage unit and the second storage unit. Servo error signal (Dx
f, Dxt), the servo error signal after addition (Dxf, Dxt) stored in the second storage unit and the servo error signal before addition (Dyf, Dyf, Dyt) and gain signal βf,
Calculate βt.

In the signal processing circuit according to the present invention, the computing means adds the sine wave data sin (n) to the servo error signal value (Dxf, Dxt) and the sine wave data sin.
Servo error signal value (Dyf, D before adding (n)
yt) and the division value (Dyf / Dxf, Dy
t / Dxt) Fourier transform. Further, the storage unit is configured to store sine wave data sin (n) near the cutoff frequency of the servo system.

Further, the present invention is an optical disk device having a signal processing unit for digitally processing a signal read from an optical disk, and the signal processing unit of this optical disk device is
A first storage unit in which sinusoidal data sin (n) is written, and sampling for generating a sampling signal Ps at every predetermined sampling period T and for generating an interrupt signal Pi after a lapse of a certain period of the sampling signal Ps. 1 of the timer and one servo error signal (Dyf, Dyt) obtained at the sampling time point corresponding to the sampling signal Ps output from the sampling timer and the sine wave data sin (n) written in the first storage unit. One value is added at a predetermined number (N) of sampling points, and the servo error signal (Dxf, Dxt) after addition and the servo error signal (Dyf, Dyt) before addition are calculated to obtain a gain signal βf. , Βt, and a servo error signal before addition based on the gain signals βf, βt obtained by the calculating means. Comprising (Dyf, DYT) and a correction means for correcting the. Then, when the interrupt signal Pi is input from the sampling timer and the recording / reproducing operation is not performed, the arithmetic means stores the servo error signal (Dxf, Dxt) after the addition in the second storage unit and the second storage unit. Servo error signal (Dx
f, Dxt), the servo error signal after addition (Dxf, Dxt) stored in the second storage unit and the servo error signal before addition (Dyf, Dyf, Dyt) and gain signal βf,
Calculate βt.

[0018]

The operation of the signal processing circuit of the optical disk according to the present invention when the gain of the servo system is adjusted will be described. First, the interrupt signal P from the sampling timer
When i is input and the recording / reproducing operation is not performed, the calculating means calculates the servo error signal (Dxf, Dx) after addition.
t) is stored in the second storage unit.

The servo error after addition stored in the second storage section is stored in the second storage section during the idle time of the operation means after the servo error signal (Dxf, Dxt) after addition is stored in the second storage section. The signals (Dxf, Dxt) and the servo error signals (Dyf, Dyt) before addition are calculated to obtain gain signals βf, βt. The obtained gain signals βf and βt
The gain is adjusted by integrating the reciprocals 1 / βf and 1 / βt of the servo error signal (Dyf, Dyt) after phase compensation.

Then, the calculation by the calculation means is performed by, for example, R
It becomes possible to carry out according to the algorithm registered in the OM, and the gain adjustment can be executed with the servo loop closed. That is, the gain can be adjusted during the operation of the optical disc device. Therefore, for example, by calculating the gain at the cutoff frequency every predetermined time, the gain can be set according to the secular change or the temperature characteristic. Further, when the interrupt signal Pi is input from the sampling timer and the recording / reproducing operation is not performed, one servo error signal (Dyf, Dyt) obtained at the time of sampling and the sine wave written in the first storage unit Servo error signals (Dxf, Dx) after addition obtained by adding one value of the data sin (n)
Since t) is stored in the second storage unit and the gain signals βf and βt are obtained in the vacant time, high-speed processing is unnecessary. Therefore, a DSP having a general processing speed can be used.

[0021]

1 to 10, an embodiment of an optical disk device of a continuous servo system equipped with an optical disk signal processing circuit according to the present invention (hereinafter, simply referred to as an optical disk device according to the embodiment) will be described. explain.

The optical disk device according to this embodiment is shown in FIG.
As shown in FIG. 2, a spindle motor 2 for rotationally driving the loaded optical disc 1 and a slide mechanism composed of a known linear motor are used to move the loaded optical disc 1 in the radial direction and record it on the optical disc 1. The optical pickup 3 comprises an optical pickup 3 for reading the stored information signal through a light beam, and a signal processing circuit 4 according to the present embodiment for digitally processing a reproduced signal from the optical pickup 3 to control a servo system. There is.

The optical pickup 3 has a laser light source, which is a light source of a light beam, an objective lens for condensing the light beam from the laser light source on the optical disk, and light for detecting return light reflected by the optical disk. It comprises a detector and a two-dimensional actuator mainly composed of a magnetic circuit composed of a focus coil, a tracking coil and a magnet.

The signal processing circuit 4 has a servo error generating circuit 5 for calculating a reproduction signal Se output from the optical pickup 3 from the photodetector to generate a necessary servo error signal. In this case, the servo error generation circuit 5 generates two types of servo error signals, a focus error signal Sf and a tracking error signal St.

In the subsequent stage of the servo error generation circuit 5,
An A / D converter 6 for converting the analog servo error signals Sf and St from the servo error generation circuit 5 into digital servo error data Dyf and Dyt is connected.

Further, the signal processing circuit 4 binarizes the information signal Si reproduced from the optical disk 1 by the optical pickup 3 and, at the same time, reproduces a clock signal from the RF circuit 7 and a signal processing system in the subsequent stage. In order to record the supplied recording signal on the optical disc 1, it has a composite circuit 8 in which an encoder for modulating the recording signal and an APC circuit for controlling the emission power of the laser light source in the optical pickup 3 are incorporated.

A decoder 9 for demodulating the binarized information signal Sd from the RF circuit 7 and extracting address information from the information signal Sd is connected to the subsequent stage of the RF circuit 7. The servo error data Dyf, Dyt from the A / D converter 6 and the address information data Da from the decoder 9 are supplied to a DSP (digital signal processing circuit) 11 via a DSP data bus 10.
The demodulated data Dd from the decoder 9 is the DSP 11
It is supplied to the controller 12 that exchanges various commands and statuses with the.

The DSP 11 performs known phase compensation on the servo error data Dyf and Dyt from the A / D converter 6, and further, the phase compensated servo error data Dy.
The gain adjustment according to the present invention described below is applied to f and Dyt,
The servo correction data Dhf and Dht are output. Further, the DSP 11 controls the composite circuit 8 of the encoder and the APC circuit according to operations such as recording, reproduction and erasing. The address information data Da supplied from the decoder 9 is referred to when controlling the optical pickup 3, for example, at the time of seek operation.

The controller 12 is, for example, a SCSI (Sm
It is connected to a host computer (not shown) by an interface such as all computer system interface). Then, the demodulated data Dd from the decoder 9 is SC
The recording data supplied from the host computer to the host computer via the SCSI bus 13 is supplied to the composite circuit 8 via the SI bus 13. Also, the decoder 9 and the composite circuit 8 are controlled by generating necessary timing signals according to operations such as recording, reproduction and erasing.

In addition to the above circuits, the data bus 10 stores a program RAM 14 in which programs in which various algorithms are written and servo correction data Dhf and Dht from the DSP 11 are converted into analog servo correction signals Shf and Sht. D / A converter 15 for converting to
As shown in FIG. 5, by counting the system clock from SP11, a timer circuit 16 for generating a sampling signal Ps at a certain fixed sampling cycle is connected. The timer circuit 16 also causes the DSP 11 to generate an interrupt signal Pi after a fixed period of time of the generated sampling signal Ps.

The A / D converter 6 receives the servo error signal S based on the sampling signal Ps from the timer circuit 16.
f and St are sampled and converted into digital servo error data Dyf and Dyt, respectively. The interrupt signal Pi is set to be generated when the A / D conversion by the A / D converter 6 is completed. The program is written in a ROM incorporated in the controller 12, and the program is read from the ROM when the optical disk device is started (power is turned on), and the program R is read via the DSP 11.
Transferred to AM14.

On the other hand, the servo correction signals Shf and Sht from the D / A converter 15 drive a two-dimensional actuator built in the optical pickup 3 and a linear motor for moving the optical pickup 3 in the radial direction of the optical disc 1. Is supplied to the drive circuit 17. A PWM (pulse width modulation) driver may be used instead of the D / A converter 15.

Here, an outline of a general servo system is shown in FIG.
It can be represented by a block diagram as shown in FIG. In FIG. 2, G (s) indicates the transfer function of the phase compensation portion, and H (s) indicates the transfer function including the two-dimensional actuator, the optical disk, the actuator driver and the like. The open loop characteristic (open-loop transfer function) in this case is G
(S) · H (s). With this open loop characteristic, the gain must be 0 dB at the cutoff frequency required from the performance of the optical disc device. Therefore, when the transfer function H (s) fluctuates, the gain at the cutoff frequency also fluctuates, and the necessary servo band cannot be obtained.

Therefore, in the signal processing circuit 4 of the present embodiment, in order to avoid the above-mentioned inconvenience, the transfer function G (s)
Change the gain of and set the gain at the cutoff frequency to 0.
Correct to dB. In this case, it is necessary to find the gain at the cutoff frequency. In the present embodiment, in order to obtain the gain at this cutoff frequency, as shown in FIG. 3, a sine wave having the same frequency as the cutoff frequency is injected as a disturbance into the servo loop, and signals Vy and signals before and after that are injected. The division Vy / Vx of Vx is executed, and the value is Fourier transformed to obtain the gain at the cutoff frequency.

Procedure for obtaining this gain (algorithm)
Is registered in the program stored in the program RAM 14, and this program is, as shown in FIG. 5, the first program activated by the interrupt signal Pi and the second program activated in the idle time of the DSP 11. It consists of

Next, the signal processing by the first and second programs will be sequentially described with reference to the flowcharts of FIGS. 6 to 9 and the timing chart of FIG.

First, the routine shown in FIG. 6 and FIG.
5 shows the processing routine by the program of FIG. 5, and as shown in FIG.
It is activated by the DSP 11 based on i. In addition, the sine wave data sin (n) shown in FIG. 4 is sequentially stored in the data area referred to by the first program and the second program. This sine wave data sin
(N) is normally written in the ROM of the controller 12 together with the above program, and is transferred to the program RAM 14 together with the above program when the power is turned on.

Further, at the time of manufacturing this optical disk device, the open loop gain of the servo system is set so that the focus servo and the tracking servo are stable, and the set gain is the RO of the controller 12.
It is registered as an initial value in the gain data area in M. The gain data in the gain data setting area is also transferred to the data area in the program RAM 14 together with the sine wave data sin (n).

The sine wave data sin (n) stored in this data area is, as shown in FIG. 4, the amplitude value of the sine wave having the same frequency as the cutoff frequency separated in the address sequence. There is. This sine wave data sin
The resolution (number of addresses) of (n) is represented by the ratio fs / fc = N of the sampling frequency fs and the frequency fc of the sine wave. Then, when the value of the sampling counter CNT updated every sampling cycle T of the A / D converter 6 becomes the same as the ratio N on the program, the gain correction is performed.

Here, the processing of the first program shown in FIGS. 6 and 7 will be sequentially described in detail. First, D
By inputting the interrupt signal Pi to SP11, step S1 is executed, and the work data area (D
Focus error data Dy to the internal RAM of SP11)
f and the tracking error data Dyt are fetched. Next, in step S2, it is determined whether the seek operation is currently being performed. This determination is made by the controller 12 from the DSP 11 by an internal interrupt due to the start of operations such as a seek operation and a user data recording / reproducing operation.
This is performed by discriminating the flag information taken into the internal RAM of the.

In step S2, if the seek operation is not in progress, the process proceeds to the next step S3. If the seek operation is in progress, the process proceeds to step S15 to perform a known seek operation process, and then to step S11 shown in FIG. jump. That is, the execution of the first program is interrupted during the seek operation. This is because the sine wave injected as a disturbance affects the seek operation.

Next, in step S3, it is determined whether or not the user data recording / reproducing operation is currently being performed. This judgment is made by judging the flag information as in the judgment of the seek operation. In step S3, if recording / reproducing is not in progress, the process proceeds to the next step S4, and if recording / reproducing is in progress, the process jumps to step S9 shown in FIG. That is, also in this case, as in the case of the seek operation, the sine wave injected as the disturbance affects the recording / reproducing operation, so that the execution of the first program is interrupted.

Next, in step S4, it is judged whether the sampling counter CNT is equal to the value N of the ratio. If the sampling counter CNT is different from the ratio value N (that is, smaller than the ratio value N), the process proceeds to step S5, and if the same, the process jumps to step S9 shown in FIG.

Next, in step S5, the sampling counter CNT is updated (+1). Thereafter, in step S1, the focus error data Dyf and tracking error data Dyt fetched in the work data area are respectively stored in the focus error data storage area and the tracking error data storage area in the data RAM of the DSP 11 as sampling counters CN.
Addresses are sequentially stored using T as an index (step S6). Next, using the sampling counter CNT as an index, the corresponding sine wave data sin (CNT) is read from the data area in the program RAM 14 (step S7).

Next, the focus error data Dyf in the work data area and the above sine wave data sin (CNT).
And are added to create focus addition data Dxf,
Furthermore, tracking error data D in the work data area
The yt and the sine wave data sin (CNT) are added to create tracking addition data Dxt. Then, each of the created addition data Dxf and Dxt is
The sampling counter CNT is stored in the focus addition data storage area and the tracking addition data storage area in the data RAM in order of address as an index (step S8).

Next, in step S9 of FIG. 7, phase compensation is performed on the tracking error data Dyt. Then, in the next step S10, the program RAM
Gain data βt is read from the data area in 14
The reciprocal 1 / βt of the gain data βt and the tracking error data Dyt after the phase compensation are integrated to obtain the tracking servo correction data Dht. As a result, the gain of the tracking error signal St has been corrected.

Next, in step S11, the tracking servo correction data Dht is supplied to the D / A converter 15 via the data bus 10 and supplied as an analog tracking correction signal Sht to the tracking coil of the two-dimensional actuator. To do. During the seek operation, the address information data D supplied to the DSP 11
Based on a and seek destination address information, a drive signal is supplied to the linear motor to move the optical pickup 3 itself in the radial direction of the optical disc 1.

Next, in step S12, phase compensation is performed on the focus error data Dyf. Then, in the next step S13, the program RAM 1
The gain data βf is read from the data area in 4, and the reciprocal 1 / βf of the gain data βf and the focus error data Dyf after the phase compensation are integrated to obtain the focus servo correction data Dhf. As a result, the gain is corrected with respect to the focus error signal.

Next, in step S14, the focus servo correction data Dhf is supplied to the D / A converter 15 via the data bus 10 and is supplied to the focus coil of the two-dimensional actuator as the analog focus correction signal Shf. Then, the processing by this first program is completed.

Next, the processing of the second program will be sequentially described. The process by the second program, that is, the Fourier transform process is performed in the idle time when the first program is not executed, and is performed by the time-sharing method. In this case, high speed processing is not required.

Here, the Fourier transform of discrete values is generally expressed by the following equation 1.

[0052]

[Equation 1]

However, N = fs / fc (fs: sampling frequency, fc: frequency of sine wave) k = 0, 1, 2, ..., N-1 T = 1 / fs.

The gain at the frequency fc of the sine wave, that is, the cutoff frequency, is k = 1 in the above equation 1,
The value of Vy / Vx in consecutive N samplings may be set to x (nT). Therefore, if the gain is β, the following equation 2 is derived.

[0055]

[Equation 2]

However, (Vy / Vx) _n is the n-th Vy
The value of / Vx is shown. Further, the value of cos (2πn / N) can be obtained from sine wave data.

Specifically, referring to the flow charts shown in FIGS. 8 and 9, first, when the DSP 11 is activated, step S21 is executed to judge whether the sampling counter CNT is equal to the value N of the ratio. To be done. When the sampling counters CNT are the same, the process proceeds to step S22, and when the values are different (that is, smaller than the ratio value N), the process ends.

Step S22 and subsequent steps are routines showing the Fourier transform processing. First, the gain of the focus servo system is determined, and then the gain of the tracking servo system is determined.

First, in step S22, the index parameter n and the value Af of the added value storage area are initialized (zero is stored). Next, in step S23, the focus error data Dyf and the focus addition data Dxf are read from the focus error data storage area and the focus addition data storage area in the data RAM of the DSP 11, respectively, using the parameter n as an index.

Next, in step S24, the division Dyf / Dxf of the focus error data Dyf and the focus addition data Dxf is executed. Next, step S25.
At, the value of cos (2πn / N) is programmed RA
The sine wave data sin (n) in M14 is read from the data area and is multiplied by the division value Dyf / Dxf. This multiplication result is added to the value Af in the added value storage area, and this added value Af is stored again in the added value storage area.

Next, in step S26, the parameter n is updated (+1). Next, in step S27, it is determined whether or not all calculations relating to the focus servo system have been completed. This determination is made based on whether or not the value of the index parameter n is equal to or greater than the value N of the ratio. If n <N, the process returns to step S23 and the subsequent steps to calculate the addition value Af based on the next focus error data Dyf and the focus addition data Dxf and store it in the addition value storage area.

On the other hand, when the index parameter n becomes equal to or more than the value N of the above ratio, the process proceeds to step S28, the Fourier transform shown in the following equation 3 is calculated, and the gain βf at the cutoff frequency of the focus servo system is calculated. Ask for.

[0063]

[Formula 3] βf = T · Af

Next, in step S29, the gain βf of the focus servo system obtained as described above is stored in the data area in the program RAM 14. This completes the processing of the focus servo system.

Next, in step S30 of FIG. 9, the index parameter n and the value At of the added value storage area are initialized (zero is stored). Next, in step S31, the DSP 1
The tracking error data Dyt and the tracking addition data Dxt are read from the tracking error data storage area and the tracking addition data storage area in the No. 1 data RAM, respectively.

Next, in step S32, the tracking error data Dyt and the tracking addition data Dx
Perform division Dyt / Dxt of t. Next, step S
In 33, the value of cos (2πn / N) is read from the data area in the program RAM 14 in which the sine wave data sin (n) is stored, and the division value Dyt / Dx is obtained.
Multiply with t. This multiplication result is used as the value A in the added value storage area.
t is added, and the added value At is stored again in the added value storage area.

Next, in step S34, the index parameter n is updated (+1). Next, in step S35, it is determined whether or not all calculations relating to the tracking servo system have been completed. This determination is made based on whether or not the index parameter n becomes equal to or greater than the value N of the above ratio. If n <N, the processing returns to step S31 and subsequent steps, and the next tracking error data Dyt
And the addition value A based on the tracking addition data Dxt
t is calculated and stored in the added value storage area.

On the other hand, when the index parameter n is equal to or more than the value N of the above ratio, the process proceeds to step S36, the Fourier transform shown in the following equation 4 is calculated, and the gain βt at the cutoff frequency of the tracking servo system is calculated. Ask for.

[0069]

[Formula 4] βt = T · At

Next, in step S37, the gain βt of the tracking servo system obtained as described above is stored in the data area in the program RAM 14. Then, in step S38, the sampling counter C
This NT is initialized (zero is stored in the counter CNT), and this second program ends.

As described above, the focus error data Dyf and the tracking error data Dyt are activated by activating the first program on the basis of the interrupt signal Pi from the time circuit 16 every sampling cycle of the A / D converter 6. And the focus addition data Dxf and the tracking addition data Dxt are stored, and the second program is started in the vacant time to obtain the gains βf and βt of the focus servo system and the tracking servo system. Unnecessary processing becomes unnecessary. Therefore, the DSP 11 having a general processing speed can be used, and the DSP 11 can be executed in combination with the phase compensation processing of the servo system.

Further, since the phase compensation part of the servo system of the optical disk device is usually constituted by an analog circuit, its servo loop characteristic is measured by a measuring instrument such as an FFT analyzer and the characteristic is determined. It was necessary to adjust the analog circuit to fit the range,
In the optical disk device according to the present embodiment, as described above, since the program started by the DSP 11 includes the function of measuring and adjusting the servo loop characteristic, the DSP 11 performs the phase compensation and adjustment of the servo system. be able to.

Moreover, since this function is executed with the servo loop closed, phase compensation and adjustment of the servo system can be performed during normal operation of the optical disk device. As a result, fluctuations in the transfer function H (s) due to temperature characteristics and changes with time can be absorbed during the operation of the optical disk device, and a stable servo system can be always realized.

Further, in this embodiment, since the measurement and the adjustment of the gain from the generation of the sine wave are all performed by software, the correction circuit as in the prior art is not required. Moreover, since it is software, it is not affected by changes over time or temperature characteristics. Therefore, in the optical disk device equipped with the signal processing circuit 4 according to this embodiment, stable gain adjustment of the servo system can be performed without being affected by changes over time and temperature characteristics, and the manufacturing cost can be reduced. It is possible to improve reliability.

The determination of the gains βf and βt of each servo system is performed by the first program in the focus error data Dyf and the tracking error data D.
The storage of yt and the storage of focus addition data Dxf and tracking addition data Dxt are repeated N times, and the second
In the program, the gains βf and β of each servo system
It is also possible to adopt a method in which a series of processes of performing the process of obtaining t once is defined as one step, and this step is repeated several times to obtain the average thereof.

In the above embodiment, the DSP 11 handles not only the servo signal processing but also the system control of the optical disk device.
May be dedicated only to servo signal processing, and a microcomputer (hereinafter simply referred to as a microcomputer) may be used for other system control.

The circuit configuration of this example is shown in FIG. In this figure, parts corresponding to those in FIG. 1 are designated by the same reference numerals, and duplicated description thereof will be omitted.

A signal processing circuit 31 according to another embodiment.
Is a DSP data bus 10 to which servo error data (Dyf, Dyt) and servo correction data (Dhy, Dht) and the like, and a CP to which reproduction data Da from the decoder 9 and recording data from the controller 12 are supplied.
It has a U data bus 32. The former DSP data bus 1
0 is a series of circuits for processing servo signals, that is, DS
The P11, the A / D converter 6, the D / A converter 15, the timer circuit 16 and the program RAM 14 are connected. The latter CPU data bus 32 has a series of circuits for system control, that is, a decoder 9, an encoder and an AP.
The composite circuit 8 with the C circuit, the microcomputer 33, the ROM 34, and the interface circuit 35 are connected.

Here, in the ROM 34, a microcomputer program and a DSP program are written,
The program for the microcomputer is transferred to the microcomputer 33 via the CPU data bus 32. The DSP program is transferred to the DSP 11 via the DSP data bus 10. The interface circuit 35 is the controller 12
For exchanging commands and statuses between the microcomputer 33 and the microcomputer 33. And in this case, DSP1
The processing by the first and second programs may be executed by the CPU 1, but as another example, the processing by the first program may be executed by the DSP 11 and the processing by the second program may be executed by the microcomputer 33. Can be executed.

The embodiment shown in FIG. 1 and this FIG.
In the other embodiment shown by 0, the example applied to the continuous servo type optical disc device is shown, but it can also be applied to the sample servo type optical disc device. in this case,
The processing by the first and second programs can be executed in exactly the same manner as in the case of the continuous servo system, and the servo system can be stabilized.

[0081]

As described above, the signal processing circuit of the optical disk according to the present invention is the first in which the sine wave data is written.
, A sampling timer that generates a sampling signal at every predetermined sampling period and an interrupt signal after a fixed period of this sampling signal, and a sampling time that corresponds to the sampling signal output from the sampling timer. One servo error signal generated and one value of the sine wave data written in the first storage unit are added at a predetermined number of sampling points, and the servo error signal after addition and the servo error before addition are added. And a correction means for correcting the servo error signal before addition based on the gain signal obtained by the calculation means, and the interrupt signal is input from the sampling timer and recorded. When the reproducing operation is not performed, the calculating means outputs the servo error signal after the addition to the second value. The servo error signal after addition, which is stored in the storage unit and is stored in the second storage unit during the idle time of the operation means after the servo error signal after addition is stored in the second storage unit. Since the gain signal is calculated by calculating the gain error signal and the servo error signal before addition, it is not necessary to add a correction circuit in order to stabilize the operation of the servo system. It is possible to perform stable servo system gain adjustment without being affected. Further, when the interrupt signal is input from the sampling timer and the recording / reproducing operation is not performed, the calculating means stores the servo error signal after the addition in the second storage unit, and after the addition, stores the servo error signal in the second storage unit. The servo error signal after addition and the servo error signal before addition, which are stored in the second storage unit, are calculated in the idle time of the operation means after the servo error signal is stored to obtain the gain signal. Since it is calculated, high-speed processing is unnecessary. Therefore, a DSP having a general processing speed can be used.

Further, the optical disk device according to the present invention calculates the servo error signal of the signal read from the optical disk based on the predetermined sine wave data, and based on the calculation result, the gain of the servo system is calculated. Since adjustment is performed, it is not necessary to add a correction circuit in order to stabilize the operation of the servo system, and moreover, stable gain adjustment of the servo system is performed without being affected by changes over time and temperature characteristics. Therefore, the manufacturing cost can be reduced and the reliability can be improved.

[Brief description of drawings]

FIG. 1 is an embodiment of an optical disk device of a continuous servo system equipped with an optical disk signal processing circuit according to the present invention (hereinafter,
FIG. 3 is a block diagram showing a circuit configuration of an optical disc device according to an embodiment).

FIG. 2 is a block diagram showing an outline of a general servo system in an optical disk device.

FIG. 3 is a block diagram showing an outline of a servo system in the optical disc device according to the present embodiment.

FIG. 4 is a waveform diagram of sine wave data referred to by a first program and a second program.

FIG. 5 is a timing chart showing start timings of a first program and a second program.

FIG. 6 is a flowchart showing a processing routine of a first program (No. 1).

FIG. 7 is a flowchart showing a processing routine of a first program (No. 2).

FIG. 8 is a flowchart showing a processing routine of a second program (No. 1).

FIG. 9 is a flowchart showing a processing routine of a second program (No. 2).

FIG. 10 is a block diagram showing a circuit configuration of an optical disc device according to another embodiment.

[Explanation of symbols]

1 optical disc 2 spindle motor 3 Optical pickup 4 Signal processing circuit 5 Servo error generation circuit 6 A / D converter 7 RF circuit 8 Composite circuit (encoder + APC circuit) 9 decoder 10 DSP data bus 11 DSP 12 Controller 14 Program RAM 15 D / A converter 16 timer circuit

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Claims (4)

(57) [Claims] 1. A first storage unit in which sine wave data is written, a sampling timer which generates a sampling signal at every predetermined sampling period, and generates an interrupt signal after a lapse of a predetermined period of the sampling signal, One servo error obtained at the sampling time according to the sampling signal output from the sampling timer
Signal and the sine wave data written in the first storage section.
Data with one value at a given number of samples
And a servo error signal after the addition and a servo error signal before the addition are calculated to obtain a gain signal, and the servo error signal before the addition is corrected based on the gain signal obtained by the computation means. When the interrupt signal is input from the sampling timer and the recording / reproducing operation is not performed, the arithmetic means stores the servo error signal after the addition in the second storage section. In the idle time of the operation means after the servo error signal after the addition is stored in the second storage unit, the second
The signal processing circuit of the optical disc for calculating the gain signal by calculating the servo error signal after addition and the servo error signal before addition which are stored in the storage section of. 2. The calculating means calculates the gain signal, the servo error signal value after the addition and the servo error signal value before the addition.
2. The signal processing circuit for an optical disk according to claim 1 , wherein the servo error signal value of 1 is divided, and the Fourier transform of the divided value is executed. 3. The signal processing circuit for an optical disk according to claim 1, wherein the first storage section stores sine wave data in the vicinity of the cutoff frequency of the servo system. 4. An optical disc apparatus having a signal processing unit for digitally processing a signal read from an optical disc, wherein the signal processing unit comprises: a first storage unit in which sine wave data is written; and a predetermined sampling period. A sampling timer that generates a sampling signal and generates an interrupt signal after a lapse of a certain period of this sampling signal, and one servo error obtained at the sampling time point according to the sampling signal output from the sampling timer.
Signal and the sine wave data written in the first storage section.
Data with one value at a given number of samples
And a servo error signal after the addition and a servo error signal before the addition are calculated to obtain a gain signal, and the servo error signal before the addition is corrected based on the gain signal obtained by the computation device. When the interrupt signal is input from the sampling timer and the recording / reproducing operation is not performed, the calculating means stores the servo error signal after the addition in the second storage section. In the idle time of the operation means after the servo error signal after the addition is stored in the second storage unit, the second
An optical disk device for calculating a gain signal by calculating a servo error signal after addition and a servo error signal before addition stored in a storage unit of the above.