JPH0536102A - Optical information processor - Google Patents

Abstract

PURPOSE:To allow the always stable lock in of tracking servo. CONSTITUTION:An eccentricity detecting circuit 31 detects the eccentric quantity of a tracking actuator 18 after the output (tracking error signal) of a subtraction circuit 11 stabilizes in the state of changing over a changeover circuit 12 to a b side in the lock in of the tracking servo. A voltage addition circuit 33 supplies the driving voltage corresponding to this eccentric quantity to an addition circuit 34 and adds this voltage to the driving voltage of the tracking actuator 18. The voltage addition circuit 33 returns the added driving voltage mentioned above to the original value after the output (tracking error signal) of the subtraction circuit 11 stabilizes in the state of changing over the changeover circuit 12 to an a side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information processing apparatus for recording / reproducing information on / from a recording medium by optical means.

[0002]

2. Description of the Related Art In an optical information processing apparatus, tracking servo is performed so that a beam spot follows a target track. FIG. 4 is a block diagram showing an example of a tracking servo circuit in a conventional optical information processing device. In the figure, reference numeral 11 is a subtraction circuit that supplies a deviation signal between the track shake amount and the actuator displacement signal from the actuator 18 to the switching circuit 12. Here, the switching circuit 12 switches the deviation signal from the subtraction circuit 11 to the amplification circuit 13 in a state where it is switched to the b side by the switching command, that is, in a state where the low frequency phase compensation is disabled and the tracking servo gain is lowered. In the state in which the signal is supplied and is switched to the side a by the switching command (original servo loop), that is, in the state where the low frequency phase compensation is enabled and the tracking servo gain is increased, the deviation signal of the subtraction circuit 11 is amplified 14 is supplied.

The amplifier circuit 13 amplifies the output (deviation signal of the subtraction circuit 11) from the switching circuit 12 and supplies it to the high frequency phase compensation circuit 16. Further, the amplifier circuit 14 is the switching circuit 1
The output from 2 (the deviation signal of the subtraction circuit 11) is amplified and supplied to the low frequency phase compensation circuit 15. The gain A of the amplifier circuit 14 is set to be larger than the gain A ′ of the amplifier circuit 13. The low-frequency phase compensation circuit 15 performs low-frequency phase compensation on the output of the amplifier circuit 14, and the high-frequency phase compensation circuit 1
Supply to 6. The high frequency phase compensation circuit 16 includes an amplifier circuit 13
Or the output of the low frequency phase compensation circuit 15 is subjected to high frequency phase compensation and supplied to the voltage / current conversion circuit 17. The voltage / current conversion circuit 17 converts the output (voltage signal) of the high frequency phase compensation circuit 16 into a current signal, and the actuator 1
It outputs to 8 as a drive current.

The tracking servo pull-in operation based on the above structure will be described. First, at the time of pulling in the tracking servo, the polarity of the tracking error is unknown. Therefore, when pulling in the tracking servo, in order to perform stable pull-in,
When the switching circuit 12 is switched to the b side to disable the low-frequency phase compensation and the tracking servo gain is lowered, the tracking error signal has a safe and sure polar region as shown in FIG. After the tracking servo system becomes stable, the switching circuit 12 is switched to the a side to enable the low frequency phase compensation and increase the tracking servo gain to restore the original tracking servo loop. In FIG. 5, the horizontal axis represents the subtraction circuit 11
Is taken as the output, and the vertical axis shows the tracking error signal.

[0005]

However, in the above-described conventional optical information processing apparatus, the following problems occur in the tracking servo pull-in in a vibrating environment or in a state where the tracking actuator is vibrating after the head is driven. There is a problem. 6A and 6B are a simplified configuration diagram of the tracking actuator and a waveform diagram of the tracking signal when the tracking actuator is hardly eccentric. Further, FIGS. 7A and 7B are a simplified configuration diagram of the tracking actuator and a waveform diagram of the tracking signal when the tracking actuator is eccentric. In these figures, 21 is an objective lens, 22 is a tracking actuator coil for driving the objective lens 21, 23 is a support spring attached to a support member 24, 25 tracking error signals, and t1.
4 is the time when the switching circuit 12 of FIG. 4 is switched to the b side, and t2 is the time when the switching circuit 12 of FIG. 4 is switched to the a side.

When the switching circuit 12 is switched to the side b at time t1, the low frequency phase compensation is disabled, and the tracking servo gain is lowered, even if the tracking servo system is stabilized, the tracking actuator operates as shown in FIG. ), The switching circuit 12 is set to t2.
At the time point, when switching to the a side to enable the low frequency phase compensation and the tracking servo gain is increased, the tracking signal 25 is shown in FIG. 6 (when the tracking actuator is almost eccentric as shown in FIG. 6A). Compared to the waveform of B), the waveform is disturbed (becomes unstable) as shown in FIG. 7B or oscillates in the worst case. Therefore, there is a problem that stable tracking servo cannot always be performed.

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical information processing apparatus which can always perform stable tracking servo pull-in even when the tracking actuator is vibrating, such as in a vibrating environment or after driving the head. It is in.

[0008]

The optical information processing apparatus of the present invention has a tracking servo circuit, and in the optical information processing apparatus for recording / reproducing information on / from a recording medium by the optical means, the tracking servo circuit is Detecting circuit for detecting eccentricity in tracking direction of tracking actuator after tracking error signal becomes stable with low frequency phase compensation disabled and tracking servo gain lowered, and eccentricity from detecting circuit Based on the above, after adding the drive voltage corresponding to the eccentricity amount to the drive voltage of the tracking actuator, the low frequency phase compensation is enabled, and the tracking servo gain is raised, and after the tracking error signal stabilizes, the addition is made. And a voltage adding circuit for returning the drive voltage to the original value. To.

[0009]

In the optical information processing apparatus having the above structure, the tracking servo circuit includes the detection circuit and the voltage adding circuit. The detection circuit detects the amount of eccentricity in the tracking direction of the tracking actuator after the tracking error signal (tracking servo) stabilizes with the low-frequency phase compensation disabled and the tracking servo gain lowered, and the eccentricity is detected. The quantity is supplied to the voltage adding circuit. The voltage adding circuit adds a drive voltage corresponding to the eccentricity amount to the drive voltage of the tracking actuator based on the eccentricity amount from the detection circuit, enables low frequency phase compensation, and raises the tracking servo gain. After the tracking error signal becomes stable, the added drive voltage is returned to the original value. As a result, even in a vibrating environment or after the head has been driven, and the tracking actuator is vibrating, the tracking servo can always be pulled in stably.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a block diagram showing an embodiment of a tracking servo circuit of an optical information processing apparatus according to the present invention. In the figure, the same reference numerals are used for the same or corresponding parts in FIG. FIG. 1 is for detecting the amount of eccentricity of the tracking actuator in the tracking direction after the tracking error signal (tracking servo) is stabilized with the low-frequency phase compensation disabled and the tracking servo gain lowered in FIG. Based on the eccentricity detection circuit 31 as the detection circuit of the present invention, and the eccentricity amount from the eccentricity detection circuit 31, a drive voltage corresponding to the eccentricity amount is added to the drive voltage of the tracking actuator, and then the low-frequency phase compensation is performed. And a voltage adding circuit 32 as a voltage adding circuit of the present invention for returning the added drive voltage to the original value after the tracking error signal becomes stable and the tracking servo gain is increased. It was added. The voltage adding circuit 32 supplies the voltage corresponding to the eccentricity amount to the adding circuit 34 based on the eccentricity amount from the eccentricity detection circuit 31, and then enables the low frequency phase compensation and raises the tracking servo gain. After the tracking error signal (tracking servo) becomes stable, the voltage adding circuit 33 for returning the voltage supplied to the adding circuit 34 to the original value, and the voltage adding circuit 3
3 is added to the output of the high frequency phase compensation circuit 16 and the added voltage is supplied to the voltage / current conversion circuit 17 as a drive voltage of the tracking actuator 18, and an adder circuit 34.

Next, the operation will be described. Switching circuit 12
Is switched to the b side by a switching command, the low frequency phase compensation is invalidated, and the tracking error signal (tracking servo) is stabilized with the tracking servo gain lowered. The displacement (the amount of eccentricity in the tracking direction) is detected and supplied to the voltage adding circuit 33. The voltage adding circuit 33 supplies the voltage corresponding to the eccentricity amount to the adding circuit 34 at a speed that does not significantly disturb the tracking servo. The adding circuit 34 adds the voltage from the voltage adding circuit 33 to the output voltage of the high frequency phase compensating circuit 16 and supplies the added voltage to the voltage / current conversion circuit 17 as a drive voltage for the tracking actuator 18. The voltage / current conversion circuit 17 converts this into a current and supplies it to the tracking actuator 18, and the tracking actuator 1
Drive eight. The voltage adding circuit 33 supplies the voltage corresponding to the eccentricity amount to the adding circuit 34, and then the switching circuit 1
2 is switched to the a side by the switching command, the low frequency phase compensation is enabled, and the tracking servo gain is raised, and the tracking error signal (tracking servo)
Is stabilized, the voltage supplied to the adding circuit 34 is returned to the original value. By doing this, the environment with vibration,
Alternatively, the tracking servo can always be pulled in stably even after the head has been driven and the tracking actuator is vibrating.

FIG. 2 shows a specific example of the tracking servo circuit shown in FIG. In FIG. 2, the same reference numerals are used for the same or corresponding parts as in FIGS. 1 and 4. In FIG. 2, reference numeral 41 is a current / voltage conversion circuit that converts the output current of the voltage / current conversion circuit 17 (drive current of the tracking actuator 18) into a voltage. Reference numeral 42 is an A / D conversion circuit that converts the output voltage of the current / voltage conversion circuit 41 into analog / digital (hereinafter abbreviated as A / D). Reference numeral 43 is a CPU, and 44 is a D / A conversion circuit for converting the voltage supplied from the CPU 43 into digital / analog (hereinafter abbreviated as D / A). An adder circuit 45 adds the voltage from the D / A conversion circuit 44 to the output voltage from the high frequency phase compensation circuit 16 and supplies the added voltage to the voltage / current conversion circuit 17 as a drive voltage for the tracking actuator 18. Is. 46 is a subtraction circuit 11
Deviation output of A / D converted and supplied to the CPU 43
It is a D conversion circuit.

Here, the CPU 43 issues a switching command to switch the switching circuit 12 to the b side to invalidate the low frequency phase compensation and reduce the tracking servo gain, and then the A / D conversion circuit. After the output (tracking error signal) of the subtraction circuit 11 supplied via 46 stabilizes, the current / voltage conversion circuit 41 and the A / D conversion circuit 42
The amount of eccentricity of the tracking actuator 18 in the tracking direction is detected from the drive current of the tracking actuator 18 supplied via the. Further, the CPU 43 applies a voltage to the adding circuit 45 via the D / A conversion circuit 44 at a speed that does not disturb the tracking servo up to a voltage equivalent to the eccentricity amount, and then issues a switching command to switch the switching circuit 12. The deviation output (tracking error signal) of the subtraction circuit 11 supplied via the A / D conversion circuit 46 is stabilized in a state where the low frequency phase compensation is enabled and the tracking servo gain is increased by switching to the a side. After that, the voltage supplied to the addition circuit 45 via the D / A conversion circuit 44 is returned to the original value (here, 0 V).

The current / voltage conversion circuit 41, the A / D conversion circuit 42, the CPU 43 and the A / D conversion circuit 46 are shown in FIG.
The eccentricity detection circuit 31 of FIG. Also, CPU 43 and D
/ A conversion circuit 44, addition circuit 45, and A / D conversion circuit 46
Constitute the voltage adding circuit 32 of FIG.

Next, the operation when the tracking servo is pulled in will be described with reference to FIG. Note that FIG. 3 is a timing chart for explaining the operation of FIG. The output current of the voltage / current conversion circuit 17 (driving current of the tracking actuator 18) is supplied to the CPU 43 via the current / voltage conversion circuit 41 and the A / D conversion circuit 42.
Here, since the drive current of the tracking actuator 18 corresponds to the eccentricity amount of the tracking actuator 18, it is used as a substitute for the eccentricity amount of the tracking actuator 18. First, the CPU 43 issues a switching command, and switches the switching circuit 12 to b at time t1 as shown in FIG.
Switch to the side to disable low-frequency compensation and lower the tracking servo gain. And CPU
43 indicates a current / current at time t2 after the output (tracking error signal) of the subtraction circuit 11 supplied via the A / D conversion circuit 46 is stabilized as shown at 51 in FIG. 3 (A).
The amount of eccentricity of the tracking actuator 18 in the tracking direction is detected from the drive current of the tracking actuator 18 supplied via the voltage conversion circuit 41 and the A / D conversion circuit 42. Then, the CPU 43 up to the detected voltage corresponding to the amount of eccentricity (voltage V1 in FIG. 3B) at a speed that does not disturb the tracking servo, and the D / A conversion circuit 44.
A voltage is applied to the adder circuit 45 via (t in FIG. 3B).
2 to t3).

Next, the CPU 43 issues a switching command at the time t3 in FIG. 3 to switch the switching circuit 12 to the side a so that the low frequency phase compensation is effective and the tracking servo gain is increased, and A / After the deviation output (tracking error signal) of the subtraction circuit 11 supplied through the D conversion circuit 46 becomes stable as shown at 52 in FIG.
The voltage supplied to the adding circuit 45 via the converting circuit 44 is
The voltage is returned to the original voltage (here, 0 V) as shown in FIG. 3B at a speed that does not disturb the tracking servo. By doing so, stable tracking servo pull-in can always be performed.

The present invention is not limited to this embodiment, and various applications and modifications are conceivable without departing from the gist of the present invention.

[0018]

As described above, according to the present invention, at the time of pulling in the tracking servo, the detection circuit disables the low-frequency phase compensation and lowers the tracking servo gain, and the tracking error signal (tracking servo ) Is stabilized, the eccentricity of the tracking actuator in the tracking direction is detected, and the voltage adding circuit
Based on the amount of eccentricity from the detection circuit, a drive voltage corresponding to the amount of eccentricity is added to the drive voltage of the tracking actuator, low-frequency phase compensation is enabled, and the tracking servo gain is raised to a tracking error signal. Since the added drive voltage is returned to the original value after the stabilization, the tracking servo is always stable even when the tracking actuator is vibrating in an environment with vibration or after the head is driven. You can pull in.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a tracking servo circuit of an optical information processing apparatus according to the present invention.

FIG. 2 is a block diagram showing a specific example of the tracking servo circuit shown in FIG.

FIG. 3 is a timing chart illustrating the operation of FIG.

FIG. 4 is a block diagram showing an example of a tracking servo circuit in a conventional optical information processing device.

5 is an explanatory diagram of the operation of FIG.

FIG. 6 is an operation explanatory diagram when the tracking actuator is hardly eccentric.

FIG. 7 is an operation explanatory diagram when the tracking actuator is eccentric.

[Explanation of symbols]

 11 adder circuit 17 voltage / current conversion circuit 18 tracking actuator 31 eccentricity detection circuit 32 voltage addition circuit

Claims (1)

Claim: What is claimed is: 1. An optical information processing apparatus having a tracking servo circuit for recording and reproducing information on a recording medium by an optical means, wherein the tracking servo circuit disables low frequency phase compensation. And, with the tracking servo gain lowered, after the tracking error signal has stabilized, a detection circuit for detecting the eccentricity amount in the tracking direction of the tracking actuator, and the eccentricity based on the eccentricity amount from the detection circuit. After adding a drive voltage corresponding to the amount to the drive voltage of the tracking actuator, the low frequency phase compensation is enabled, and the tracking servo gain is increased, and the tracking error signal is stabilized and then added. A voltage adding circuit for returning the drive voltage to the original value Optical information processing apparatus according to claim.