JP2000251284A - Device and method for adjusting digital servo of optical disk device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid such troubles as sound jump and the requirement of much time for track search by reducing the level of a tracking error signal at a fixed rate according to a signal for adjusting tracking balance. SOLUTION: A tracking servo is turned off, a laser beam is reciprocated in the radial direction of an MD, and a tracking error signal TE with a fixed frequency is generated. A switch signal Ts is sent, switching elements S1 and S2 are turned on, and the level of E and F signals being inputted to variable amplifiers 31 and 32 is reduced, for example, by 4-6 dB. Then, tracking balance signals TBAL1 and TBAL2 are outputted for adjusting tracking balance so that the center potential of a tracking error signal TE coincides with preset reference potential. In the case of coincidence, the amplification factor of the variable amplifiers 31 and 32 is fixed. The switch signal Ts is cancelled for setting the level of the tracking error signal to an original one again, and the tracking servo is turned on.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an MD (Mini Disk)
The present invention relates to a digital servo adjustment device and a digital servo adjustment method for an optical disk device that reads data from a disk using an optical pickup such as a CD (Compact Disk) and the like, and particularly to a digital servo adjustment device and a digital servo adjustment for adjusting a tracking balance. About the method.

[0002]

2. Description of the Related Art Data such as music is recorded in a spiral or concentric manner by extremely small magnetic domains or pits on a disk surface in an MD, a CD or the like. 2. Description of the Related Art In an optical disc device such as an MD player and a CD player, a laser beam emitted from an optical pickup is focused on a signal surface of a disc and a magnetic domain row or a pit row (hereinafter, referred to as a track).
And data is read by detecting the reflected light from the signal surface with an optical pickup.

[0003] The signal surface of the disk is constantly displaced due to surface deflection when the disk is rotating, and the track is also constantly displaced due to core deflection when the disk is rotating. For this reason, disk drives such as MD players and CD players have a focus servo and a tracking servo in order to keep the laser beam always in focus on the signal surface and to enable the laser beam to track the track. Is equipped.

In order to read a recording signal from a disk without error, it is necessary to adjust the servo characteristics of the pickup servo to an optimum state. For the pickup servo,
There are an analog servo circuit formed by an analog circuit and a digital servo circuit formed by a digital circuit. In the case of an analog servo circuit, a semi-fixed resistor for adjusting the servo characteristics is provided on the substrate, and the manufacturer adjusts the resistance value before shipping the product to optimize the servo characteristics.

However, in the analog servo circuit, the servo characteristics change when the optical characteristics, actuator characteristics, circuit coefficients, etc. of the pickup change due to long-term use or environmental changes (temperature changes, etc.). There is a disadvantage that. In a state where the servo characteristics are poor, out-of-focus and out-of-tracking are likely to occur due to vibration, scratches on the disk, and the like, which causes sound skipping. In particular, in the case of an in-vehicle audio device, since vibration is severe, skipping frequently occurs if the servo characteristics are poor.

In recent years, digitalization of electronic circuits of audio devices has been advanced, and digital servo circuits have been widely used as pickup servos for MD players. In recent MD players, the pickup servo is automatically adjusted when the power is turned on or when a disc is loaded. For example, conventionally, tracking balance is performed by the following method. That is, when adjusting the tracking balance, the tracking servo is turned off, and the tracking actuator is driven to reciprocate the laser beam emitted from the optical pickup in the radial direction of the disk. The light reflected on the signal surface of the disk is received by an optical pickup, converted into an electric signal, and input to an RF amplifier. In the RF amplifier, a track error signal having a substantially constant frequency is generated based on a signal input from the optical pickup.

FIG. 7A is a diagram showing an example of a tracking error signal output from the RF amplifier at the time of tracking balance adjustment, with time being plotted on the horizontal axis and potential being plotted on the vertical axis. The tracking error signal output from the RF amplifier is input to a servo signal processor (SSP). In the servo signal processor, the tracking circuit in the RF amplifier is adjusted so that the central potential of the tracking error signal (shown by a broken line in FIG. 7A) coincides with a reference potential (a predetermined constant potential). . FIG.
(B) is a diagram showing a tracking error signal after tracking balance adjustment. As described above, when the center potential of the tracking error signal matches the reference potential, the servo characteristics of the tracking servo become the best.

[0008]

However, the conventional tracking balance adjustment method described above has the following problems. The tracking error signal output from the RF amplifier is converted into a digital signal by an A / D (analog / digital) converter in the servo signal processor. In order to increase the conversion accuracy of the A / D conversion, it is preferable that the signal level of the tracking error signal is large.

However, if the center potential of the tracking error signal deviates greatly from the reference potential in the initial state, the waveform may be clipped as shown in FIG. In this state, if the tracking balance is adjusted so that the center potential of the tracking error signal matches the reference potential, the waveform of the tracking error signal becomes higher or lower than the reference voltage (upper side in the figure) as shown in FIG. ). As a result, skipping is likely to occur during reproduction of music or the like, and it takes time to search for a track.

Accordingly, an object of the present invention is to provide a digital servo adjustment device and a digital servo adjustment device for an optical disk device which can always adjust the tracking balance in an optimum state and can avoid problems such as skipping of sound and time-consuming track search. It is to provide a servo adjustment method.

[0011]

SUMMARY OF THE INVENTION The above object is achieved by a tracking error signal generating means for generating a tracking error signal from an output of an optical pickup, and a central potential of the tracking error signal output from the tracking error signal generating means. A digital servo adjustment device for an optical disk device having signal control means for adjusting the tracking balance by controlling the tracking error signal generation means so as to match a preset reference potential, wherein the tracking error signal generation means comprises: A digital servo adjusting device for an optical disc, characterized by having a level decreasing means for decreasing a signal level of the tracking error signal at a constant rate in accordance with a signal from a signal control means.

Further, the above-mentioned problem is solved by a tracking error signal generating means for generating a tracking error signal from an output of an optical pickup, and detecting the presence or absence of a clip of the tracking error signal output from the tracking error signal generating means. When a clip is detected, the tracking error signal adjusting means for reducing the signal level of the tracking error signal, and the tracking error signal generating means are controlled so that the central potential of the tracking error signal matches a preset reference potential. And a signal control means for adjusting the tracking balance.

[0013] Further, the above-mentioned problem is caused by reducing the signal level of the tracking error signal when adjusting the tracking balance, and adjusting the tracking balance so that the center potential of the tracking error signal is constant with a preset reference potential. Thereafter, the signal level of the tracking error signal is returned, and the problem is solved by a digital servo adjustment method for an optical disk device.

Still another object of the present invention is to detect the presence or absence of a clip of a tracking error signal when adjusting the tracking balance, and reduce the signal level of the tracking error signal when detecting the clip of the tracking error signal. The problem is solved by a digital servo adjustment method for an optical disk device, wherein a tracking balance is adjusted so that a central potential of an error signal is constant with a reference potential, and thereafter, a signal level of the tracking error signal is returned.

Hereinafter, the operation of the present invention will be described. In the present invention, the tracking balance is adjusted by reducing the signal level of the tracking error signal output from the tracking signal generating means. As a result, clipping of the tracking error signal is avoided, and the servo characteristics of the tracking servo become the best. After that, the signal level of the tracking error signal is restored. As a result, problems such as skipping of sound and time required for track search are avoided.

A tracking error signal adjusting means for detecting whether or not a clip has occurred in the tracking error signal and reducing the signal level of the tracking error signal only when the clip has occurred may be provided. In this case, when the center potential of the tracking error signal does not significantly deviate from the reference potential so that clipping occurs, the tracking balance can be adjusted while the signal level of the tracking error signal is high.

[0017]

Embodiments of the present invention will be described below with reference to the accompanying drawings. (First Embodiment) FIG. 1 is a block diagram showing a configuration of an MD player having a digital servo adjustment device according to a first embodiment of the present invention.

Reference numeral 11 denotes a recording / reproducing MD. 12 is MD
A spindle motor 13 rotates the MD 11 at a predetermined constant linear speed. A laser beam 13 irradiates the MD 11 with laser light, detects data recorded on the MD 11 by reflected light, and cures the recording surface of the MD 11 by the laser light irradiation. This is an optical pickup in which the temperature is raised as described above and magneto-optical recording is enabled by a recording head 15 described later. 14 is a feed motor for feeding the optical pickup 13 in the radial direction of the MD 11, 15 is a recording head for generating a magnetic field according to data during recording, 16
Is a head driver for supplying data to the recording head 15.

From the optical pickup 13, four signals (A signal, B signal, C signal and D signal) obtained from the main spot of the laser beam, and two signals (E signal and F signal) obtained from the side spots Is output. 1
Reference numeral 7 denotes an RF signal from the signal output from the optical pickup 13.
(Radio Frequency) signal and EFM (Eight to Fourt)
een Modulation) signal, focus error signal, tracking error signal and CLV (Constant Linear Veloci)
ty) An RF amplifier (tracking signal generating means) for generating a control signal. An address decoder 18 demodulates address data recorded by wobbling of the pre-group from the RF signal.

Reference numeral 20 denotes a servo signal processor (signal control means). This servo signal processor 20
Generates a focus control signal, a tracking control signal, a feed control signal, and a rotation control signal based on the focus error signal and the tracking error signal output from the RF amplifier 17. 24 is a servo drive circuit. The servo drive circuit 24 includes the servo signal processor 2
Drive control of the focus actuator of the optical pickup 13 is performed by a focus control signal output from 0, drive control of the tracking actuator of the optical pickup 13 is performed by a tracking error signal, drive control of the feed motor 14 by a feed control signal, and rotation control signal. Drives the spindle motor 12.

Reference numeral 19 denotes a digital signal processing circuit. The digital signal processing circuit 19 transmits the address data input from the address decoder 18 to a control unit 25 which will be described later, EFM modulates the compressed data at the time of recording and outputs it to the head driver 16, and at the time of reproduction, the RF amplifier 1
7 is demodulated and output as compressed data.

Reference numeral 23 denotes D for storing compressed data for a predetermined time.
Seismic memory with RAM configuration, 21 is a memory controller for earthquake, 22 is ATRAC (Adaptive Transform Acour)
sticCoding) An encoder / decoder. The seismic memory controller 21 writes the compressed data input from the ATRAC encoder / decoder 22 to the seismic memory 23 continuously and at a normal speed during recording, while performing predetermined communication with the control unit 25. In parallel with this, compressed data is read out intermittently and at high speed from the seismic memory 23 and output to the digital signal processing circuit 19. Also,
At the time of reproduction, the memory controller 21 writes the compressed data input from the digital signal processing circuit 19 intermittently and at high speed into the memory 23 for seismic operation. Reads the compressed data, and reads the ATRAC encoder / decoder 22
Output to

At the time of recording, the ATRAC encoder / decoder 22 compresses music data input from an A / D converter (not shown) into compressed data, and outputs the compressed data to the memory controller 21 for earthquake resistance. The compressed data input from the memory controller 21 for earthquake resistance is decompressed and converted into music data, and is converted into a D / A converter (not shown).
Output to

Reference numeral 25 denotes a control unit constituted by a microcomputer, which controls the servo signal processor 20 and the digital signal processing circuit 19 according to a predetermined program.
And the memory controller 21 for earthquake resistance. Reference numeral 26 denotes a key operation unit for performing operations such as power on / off, playback, recording, editing, and ejection, and the like. PLAY key, next song seek key, previous song seek key, REC key, track recording key, STOP key, edit key, and the like. Is provided.
Reference numeral 27 denotes a display section for displaying a track number, a performance elapsed time and the like.

FIG. 2 is a circuit diagram showing a tracking circuit in the RF amplifier 17. E signal output from the optical pickup 13 is inputted to the variable amplifier 31 via the resistor R _11. Between the ground and the input of the variable amplifier 31, resistor R ₁₂ and the switch element S ₁ is connected in series. When the switch element S ₁ is turned on, the variable amplifier 3
The level of the E signal input to 1 is reduced by a certain ratio determined by the ratio of the resistance values of the resistors R ₁₁ and R ₁₂ .

The output from the optical pickup 13
The F signal is a resistor R_{twenty one}Is input to the variable amplifier 32 through
You. A resistor is provided between the input terminal of the variable amplifier 32 and the ground.
Anti-R _{twenty two}And switch element S_TwoAre connected in series.
Switch element S_TwoTurns on, enters the variable amplifier 32.
The level of the input E signal is the resistance R_{twenty one}, R_{twenty two}Resistance ratio
By a certain percentage determined by

[0027] These switching elements S _1, S ₂ is turned on by the switch signal T _s that is output from the servo signal processor 20 - off. In addition, the variable amplifiers 31, 3
The amplification factor of each of the servo signal processors 20
Tracking balance signals T _BAL1 , T output from
_Varies with _BAL2 . The output of the variable amplifier 31 is input to the non-inverting input terminal (+) of the differential amplifier 33,
2 is input to the inverting input terminal (-) of the differential amplifier 33. The differential amplifier 33 includes the variable amplifiers 31, 3
2 is output as the tracking error signal TE.

FIG. 3 is a flowchart showing a tracking balance adjusting method according to the present embodiment. First, in step S11, the servo signal processor 20
Turns off the tracking servo based on a signal from the control unit 25. In addition, the servo signal processor 2
0 indicates that the tracking control signal is sent to the servo drive circuit 24 and the laser light output from the optical pickup 13 is MD
11 is reciprocated in the radial direction. The light reflected by the MD 11 is received by the optical pickup 13 and converted into an electric signal. The RF amplifier 17 generates a tracking error signal TE having a substantially constant frequency based on a signal output from the optical pickup 13.

Next, the process proceeds to step S12, sends a switch signal T _s to the RF amplifier 17 from the servo signal processor 20, turn on both the switch devices S _1, S _2, E is input to the variable amplifier 31 The levels of the signal and the F signal are reduced by, for example, 4 to 6 dB. Rate of decrease in signal level, the resistor R _11, R _12, because that is determined by the resistance value of R _21, R _22, advance the resistors _{R 11, R 12, R 21} , R
It is necessary to set the resistance value of ₂₂ appropriately. Thus, for example, as shown in FIG. 4A, even if the center potential of the tracking error signal TE greatly deviates from a preset reference potential and the output of the differential amplifier 33 (the tracking error signal TE) is clipped. 4B, clipping is avoided.

Next, the process proceeds to step S13, where the servo signal processor 20 sets the center potential of the tracking error signal TE so as to match the preset reference potential.
The tracking balance is adjusted by outputting the tracking balance signals T _BAL1 and T _BAL2 . When the center potential of the tracking error signal matches the reference voltage, the servo signal processor 20 fixes the amplification factors of the variable amplifiers 31 and 32. Then, the process proceeds to step S14, and releases the switch signal T _s, undo the level of the tracking error signal TE. Thereafter, the process shifts to step S15 to turn on the tracking servo. Thereby, the adjustment of the tracking balance is completed.

According to the present embodiment, even if the tracking balance is largely deviated in the initial state, since the level of the tracking error signal TE is lowered before the tracking balance adjustment, the waveform is not clipped and the adjustment can be performed in a good state. Done. Further, since the tracking level is returned to the original level after the adjustment, it is possible to avoid problems such as skipping of a sound and a long time for a track search.

(Second Embodiment) FIG. 5 shows a second embodiment of the present invention.
FIG. 10 is a diagram illustrating an example in which the digital servo adjustment device according to the embodiment is applied to an MD player. This embodiment is different from the first embodiment in that the tracking error signal adjustment for reducing the signal level of the tracking error signal input to the servo signal processor when the tracking error signal clip is detected during the tracking balance adjustment. Since a circuit (tracking error signal adjusting means) is provided, a description of a portion overlapping with the first embodiment will be omitted.

In this embodiment, the RF amplifier 17
Between the servo signal processor 20 and the
An error signal adjustment circuit 40 is provided. This tiger
The locking error signal adjusting circuit 40 includes a clip detecting circuit.
41 and the resistance R_Three, R_Four, R _FiveAnd the switch element S_ThreeWhen
It consists of. The clip detection circuit 41
Based on the signal from the signal processor 20.
Output from RF amplifier 17 during King balance adjustment
Detects the presence or absence of clipping of the tracking error signal TE
You. This clip detection circuit 41 has a resistor R_FiveSui through
Switch S_ThreeConnected to the
Ki switch element S_ThreeOn, and no clips are detected.
Switch element S_ThreeIs turned off.

The resistor R ₃ is connected between the RF amplifier 17 and the servo signal processor 20, between the ground and the servo signal processor 20 and the resistor R ₄ and the switch element S ₃ is connected in series I have. In the present embodiment, at the time of tracking balance adjustment, first, the servo signal processor 20 turns off the tracking servo based on a signal from the control unit, and the servo drive circuit 24
The laser light output from the optical pickup 13 via the optical disc is reciprocated in the radial direction of the MD 11. This gives R
In the F-amplifier 17, a tracking error signal T of a constant frequency is generated based on a signal output from the optical pickup 13.
E is generated.

The clip detection circuit 41 generates a servo signal
Based on the signal from the processor 20, the RF amplifier 17
Of tracking error signal TE output from
Is detected. And if no clip is detected
Ki switch element S_ThreeOff and the clip is detected
Switch element S_ThreeTurn on. Switch element
S_ThreeIs off, the signal output from the RF amplifier 17 is
The servo error occurs without changing the level of the locking error signal TE.
The signal is input to the signal processor 20. On the other hand, switch element
Child S_ThreeIs on, the tracking error signal TE
Is the resistance R_Three, R _FourWith an attenuation rate determined by the ratio of the resistance values of
Attenuated and input to the servo signal processor 20
You. Switch element S_ThreeIs about 4 to 6 dB when
The resistance is adjusted so that the racking error signal TE is attenuated.
R_Three, R_FourIs preferably set.

The servo signal processor 20 determines the gain of the variable amplifier in the RF amplifier 17 so that the center potential of the input tracking error signal TE matches the reference potential. Then, the servo signal processor 20
Sends a predetermined signal to the clip detection circuit 41, switching off of the switching element S _3. Thereby, the adjustment of the tracking balance is completed.

In this embodiment, the RF amplifier 17
Is clipped in the tracking error signal TE output from the
, The tracking balance can be adjusted to the best condition. (Third Embodiment) FIG. 6 is a diagram showing an example in which a digital servo adjustment device according to a third embodiment of the present invention is applied to an MD player. The present embodiment also differs from the first embodiment in that a clip detection circuit for detecting the presence or absence of a clip of the tracking error signal TE at the time of tracking balance adjustment is different from that of the first embodiment. Description is omitted.

In this embodiment, a clip detection circuit 42 is provided, and the clip detection circuit 42 detects whether the tracking error signal TE input from the RF amplifier 17 to the servo signal processor 20 is clipped. are doing. When the clip detection circuit detects a clip of the tracking error signal TE, the clip detection signal is sent from the clip detection circuit to the control unit 25.

The RF amplifier 17 is provided with the tracking circuit shown in FIG. Control unit 25, tracking when the clip detector circuit 42 at the time of balance adjustment clip detection signal is input, sends a switch signal T _S to the RF amplifier 17 to the signal level of the tracking error signal TE for example 4~6dB reduced. The servo signal processor 20 adjusts the tracking balance so that the center potential of the tracking error signal TE matches the reference potential, and when the adjustment of the tracking balance is completed, the control unit 2.
Notify 5 As a result, the control unit 25 releases the switch signal T _S and restores the level of the tracking error signal TE.

In this embodiment, as in the first embodiment, even if the tracking balance is largely shifted in the initial state, the waveform is clipped because the level of the tracking error signal is lowered before the tracking balance is adjusted. Adjustment is performed in a good condition. Further, since the tracking level is returned to the original level after the adjustment, it is possible to avoid problems such as a skipping sound and a long time for a track search.

[0041]

As described above, according to the present invention,
When the tracking balance is adjusted, the signal level of the tracking signal is reduced, the tracking balance is adjusted so that the center potential of the tracking error signal matches the reference potential, and then the signal level of the tracking error signal is returned. Even if there is a deviation, the waveform of the tracking error signal does not clip, and the tracking balance can be adjusted in a good state.
As a result, problems such as skipping of sound and time required for track search are avoided.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an MD player having a digital servo adjustment device according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram showing a tracking circuit in the RF amplifier of the MD player.

FIG. 3 is a flowchart illustrating a tracking balance adjustment method according to the first embodiment.

4A is a waveform diagram showing a tracking error signal before the signal level is reduced, and FIG. 4B is a waveform diagram showing a tracking error signal after the signal level is reduced.

FIG. 5 is a diagram illustrating an example in which a digital servo adjustment device according to a second embodiment of the present invention is applied to an MD player.

FIG. 6 is a diagram illustrating an example in which a digital servo adjustment device according to a third embodiment of the present invention is applied to an MD player.

7A and 7B are diagrams showing a tracking balance adjustment method. FIG. 7A is a waveform diagram showing a tracking error signal before the tracking balance adjustment, and FIG. 7B is a tracking error after the tracking balance adjustment. FIG. 4 is a waveform chart showing signals.

FIG. 8 is a diagram showing a conventional problem, and FIG.
8A is a diagram illustrating a tracking error signal in which a clip has occurred, and FIG. 8B is a waveform diagram of the tracking error signal after adjusting the tracking balance in a state in which the clip has occurred.

[Explanation of symbols]

 11 MD, 12 spindle motor, 13 optical pickup, 14 feed motor, 15 recording head, 16 head driver, 17 RF amplifier, 18 address decoder, 19 digital signal processing circuit, 20 servo signal processor (SSP), 21 memory controller for earthquake resistance , 22 ATRAC encoder / decoder, 23 seismic memory, 24 servo drive circuit, 25 control unit, 26 display unit, 27 key operation unit, 31, 32 variable amplifier, 33 differential amplifier, 40 tracking error signal adjustment circuit, 41, 42 Clip detection circuit.

Claims (4)

[Claims] 1. A tracking error signal generating means for generating a tracking error signal from an output of an optical pickup, and a center potential of the tracking error signal output from the tracking error signal generating means coincides with a preset reference potential. A signal control means for controlling the tracking error signal generation means to adjust the tracking balance as described above, wherein the tracking error signal generation means responds to a signal from the signal control means. A digital servo adjusting device for an optical disk, comprising a level reducing means for reducing a signal level of the tracking error signal at a constant rate. 2. A tracking error signal generating means for generating a tracking error signal from an output of an optical pickup, and detecting presence or absence of a clip of the tracking error signal output from the tracking error signal generating means.
A tracking error signal adjusting unit for reducing a signal level of the tracking error signal when a clip is detected; and controlling the tracking error signal generating unit such that a center potential of the tracking error signal matches a preset reference potential. A digital servo adjustment device for an optical disc, comprising: 3. When the tracking balance is adjusted, the signal level of the tracking error signal is reduced, and the tracking balance is adjusted so that the center potential of the tracking error signal is constant with a preset reference potential. A digital servo adjustment method for an optical disk device, comprising returning a signal level of an error signal. 4. A method for detecting the presence or absence of a clip of a tracking error signal when adjusting a tracking balance, and reducing the signal level of the tracking error signal when detecting the clip of the tracking error signal. A digital servo adjustment method for an optical disk device, comprising: adjusting a tracking balance so as to be constant with a reference potential; and thereafter returning a signal level of the tracking error signal.