JPH05242498A - Optical information recording and reproducing device - Google Patents

Abstract

PURPOSE:To provide an optimum method for controlling a servo mechanism system by providing a momentum detection means detecting the amplitude, the speed and the acceleration of mechanical resonance on the momentum of an actuator integrally on the actuator. CONSTITUTION:Information from an information track recorded on a disk is read by the actuator 2 of an optical pickup 1 and the error signal of a read information signal is detected by an error detector 3. Further, the amplitude, the speed and the acceleration of the momentum of the actuator are detected by the momentum detection means 5 integrally provided in the optical pickup 1 and the detected momentum is adjusted to a prescribed level in relation to the resonance frequency fo of the actuator and the sharpness Qo of the resonance. Then, this device is constituted so that the adjusted momentum and the error signal are synthesized by a signal synthesizer circuit 7 and the synthesized signal is fed back to the actuator 2 through a driver circuit 4. Thus, the resonance frequency fo and the sharpness Qo of the resonance of the mechanical resonance are adjusted according to the momentum of the actuator.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording / reproducing apparatus for recording information on a disc-shaped recording medium with an optical pickup or reading information recorded on a disc-shaped recording medium with an optical pickup.

[0002]

2. Description of the Related Art In recent information recording / reproducing apparatuses, an optical pickup system using a laser beam using an actuator type pickup is generally used.

In order to accurately record / reproduce an information signal on / from a recording medium such as a disk by an actuator type pickup, unevenness of the surface of the recording medium, defocusing of laser light due to warpage, etc. (that is, focus error), and recording medium Track deviation due to eccentricity (that is, tracking error)
Must be constantly corrected, and it is indispensable to configure a servo mechanism for the correction in the device.

Further, since the actuator type pickup has a structure in which an actuator is built therein, mechanical vibration occurs in the pickup, and mechanical resonance frequency based on the vibration also exists. Then, in the vicinity of this resonance frequency, a phase delay occurs in the control signal phase system of the servo mechanism, and the gain margin of the control signal also decreases due to the phase delay. As a result, there is a problem in that the control stability of the servo mechanism system deteriorates.

In order to solve such a problem, conventionally,
For example, JP-A-3-113838 (G11B 7/0
In (9), the fixed end member of the support member for the optical lens mounting member of the actuator type pickup is made of a material having a large Young's modulus relative to the Young's modulus of the material forming the movable member of the support member. ,
A known technique is disclosed in which the resonance frequency of the actuator is shifted to a high frequency band to improve the stability of the servo system.

FIG. 4 is an overall gain characteristic diagram showing the relationship between frequency and gain in the tracking direction transfer characteristic of the actuator. FIG. 4a shows a general gain characteristic of a tracking servo which is generally required in the past. Also, the solid line in FIG. 4b shows the overall gain characteristic A before shifting the resonance frequency to the high band, and the broken line shows the overall gain characteristic B after shifting the resonance frequency to the high band.

Considering the above-mentioned known technique in comparison with the total gain characteristic of the tracking servo shown in FIG.
The servo gain GB of the resonance frequency fB corresponding to the resonance frequency fb of the total gain characteristic B of FIG.
Since the gain level is lower than the servo gain GA of the resonance frequency fa corresponding to the resonance frequency fa of the servo gain GA, a large gain margin of the servo signal is ensured by using the pickup according to the total gain characteristic B. It stabilizes the control of the system.

However, the total gain characteristic of the actual tracking servo is determined in consideration of various factors such as the vibration resistance characteristics of the optical pickup and the device on which the optical pickup is mounted. As described above, the amount of shift of the resonance frequency to the high range by examining the material is as small as 1.17 times to 1.9 times, and stable control of the servo mechanism system is always obtained only by changing the material. It is not always possible.

Further, in determining the total gain characteristic of the tracking servo, it is necessary to consider the relationship between the resonance frequency fo and the resonance sharpness Qo in the total gain characteristic as one of the important problems to be solved.

Of these, the resonance sharpness Qo is fo / f2
The magnitude of the resonance sharpness is expressed by the formula −f1 = Qo. Then, the respective frequencies of f2 and f1 at this time are
As shown by the overall gain characteristic in FIG. 5, the gain level is at the resonance frequency fo and the frequency is located around fo which is set by 1 / √2 of the value of the gain level.

Generally, when the resonance sharpness Qo has a large value, it becomes difficult to construct a stable servomechanism system. Since the relationship between the resonance sharpness Qo and the resonance frequency fo is not constant, the control of the servo mechanism system, which did not fluctuate even when the optical pickup was operated at room temperature, becomes unstable when it is operated at high temperature for a long time. As a result, there is a problem in that the control of the servo mechanism system fluctuates due to temperature changes and changes with time.

[0012]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and the actuator is provided with a momentum detecting means for detecting a mechanical momentum without changing the basic structure and material of the actuator type pickup.
A feedback loop is provided which optimizes the control of the servomechanism system by relating the detected momentum to the resonance frequency fo of the mechanical resonance of the actuator and the sharpness Qo of the resonance.

[0013]

To achieve the above object, the present invention provides an actuator type pickup, an error detecting means for detecting an information track scanning error due to the pickup, and a momentum of an actuator provided in the pickup. A momentum detecting means, and an adjusting means for adjusting the momentum detected by the momentum detecting means to a predetermined value,
It is characterized by further comprising a signal synthesizing means for synthesizing the momentum adjusted by the adjusting means and the error signal, and a driving means for controlling the actuator based on the output of the signal synthesizing means.

[0014]

In the present invention, the momentum of the actuator is detected by the detecting means by the detecting means for the amplitude, velocity and acceleration of the mechanical resonance, or a combination thereof. Then, the detected momentum is adjusted to a predetermined level by the level adjusting circuit in relation to the resonance frequency fo of the actuator and the sharpness Qo of the resonance, and the adjusted momentum is an error signal detected by the error detector of the optical pickup. And a combined momentum feedback loop for returning the synthesized signal to the actuator via the driving means.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing the principle configuration of the present invention applied to a servo system, for reproduction control of a tracking servo.

First, in the conventional general tracking servo configuration, in reading information from an information track recorded on a disk, a light beam driven by an actuator 2 incorporated in the optical pickup 1 scans the information track. Is done by doing. In the read information signal, an error signal based on the positional deviation of the light beam scanning with respect to the information track is detected by the error detector 3, and the error signal is supplied to the driver circuit 4 according to the detection level. A feedback loop of a tracking servo that drives the actuator 2 is configured via a circuit.

Then, the tracking error of the actuator 2 is corrected by the feedback loop, and the tracking servo of the optical pickup 1 with respect to the information track of the disc is performed.

In this embodiment, a momentum feedback loop based on the mechanical resonance of the actuator is added to the tracking servo. The momentum of the actuator driven by the driver circuit 4, that is, the mechanical resonance of the actuator 2 is detected. The actuator 2 is integrally provided with a momentum detecting means 5 for detecting the amplitude, the velocity and the acceleration by a circuit or a combination of the amplitude, the velocity and the acceleration, and detecting the detected momentum at the resonance frequency fo of the actuator. And the sharpness Qo of the resonance are adjusted by the level adjusting circuit 6 to a predetermined level.

The adjusted momentum is input to the signal synthesizing circuit 7 together with the error signal, and the signal synthesizing circuit arithmetically processes the momentum and the tracking amount.
Then, a feedback loop in which the combined signal output is supplied to the actuator 2 via the driver circuit 4 is formed.

As a result, the error signal adjusted based on the tracking error of the light beam scanning with respect to the information track and the momentum adjusted based on the mechanical resonance of the actuator are fed back to the actuator through the driver circuit, and the feedback amount is returned. Accordingly, tracking control of the light beam scanning by the actuator is performed.

Next, FIG. 2 shows the principle configuration of the present invention described with reference to FIG. 1, and shows the frequency characteristics before and after returning to the actuator with respect to the amplitude, velocity and acceleration of the mechanical resonance of the actuator. It shows the relationship of. In FIG. 2, the characteristic curve A shows the frequency characteristic before the feedback, and the characteristic curve B shows the frequency characteristic after the feedback.

FIG. 2a shows the amplitude characteristic of the mechanical resonance. The resonance frequency fo'after feeding back the amplitude amount of the mechanical resonance to the actuator is shifted to a higher range than the resonance frequency fo before the feedback. That is, the gain level of the resonance frequency fo'in the total gain characteristic of the tracking servo is set at a gain level position lower than the gain level of the resonance frequency fo before the feedback, as in the prior art, whereby the gain of the servo signal is obtained. A margin is secured and the control of the servo mechanism system is stabilized.

FIG. 2b shows the speed characteristic of mechanical resonance. The resonance sharpness Qo 'at the resonance frequency fo after the mechanical resonance speed is fed back to the actuator is the resonance sharpness at the resonance frequency fo before feedback. It decreases with respect to Qo. Further, at this time, the resonance frequency fo in the overall gain characteristic is not shifted to the high frequency range, and its frequency position is constant.

That is, f described in the above-mentioned prior art is used.
The value of resonance sharpness Qo 'represented by o / f2-f1 = Qo' becomes small, and a tracking servo with stable operation can be obtained. FIG. 2c shows the acceleration characteristic of mechanical resonance. The resonance frequency fo ″ after the mechanical resonance acceleration is fed back to the actuator is shifted to the low frequency side with respect to the resonance frequency fo before the feedback and becomes the resonance frequency fo. The frequency position that does not affect, that is, 1 / of the gain level value at the resonance frequency fo
It is set to the frequency position shifted to the low range from the frequency position set by √2.

As is apparent from the amplitude characteristic, the velocity characteristic and the acceleration characteristic of the mechanical resonance shown in FIG. 2, the actuator is adjusted based on the resonance frequency fo of the mechanical resonance and the sharpness Qo of the resonance. By returning the momentum, optimum control of the servo mechanism system for the actuator can be obtained.

FIG. 3 shows the principle configuration according to the present invention.
FIG. 9 is a circuit diagram of a main part of an embodiment in which the present invention is embodied in a CD player, regarding a speed characteristic of mechanical resonance of the actuator described in b. In the drawings, the same reference numerals as those in FIG. 1 are omitted.

The error signal detected by the error detector 3 is input to a known CD control IC, for example, an analog signal processing IC (LA9210M) as the signal synthesizing means 7.
Then, in the IC, signal processing necessary for tracking servo is performed based on the error signal, and the error signal is combined with a speed amount appropriately detected by an actuator described later, and then the CD control is performed. It is output from the IC for use.

Then, the combined signal is input to the driver circuit 4 and fed back to the actuator 2 via the driver circuit. Further, the output of the driver circuit 4 is supplied to one end of the actuator 2 formed of a coil, and the resistors R1, R3, and R2 connected to both ends of the coil of the actuator 2 are used as one side. Is supplied to the bridge circuit consisting of. Further, a capacitor C1 is connected to both ends of the resistor R1, and the high frequency inductance of the actuator 2 is corrected by the capacitor.

Further, in the present embodiment, by balancing the bridge circuit, the connection point X1 between the other end of the actuator 2 and the resistor R3, and the resistor R1 and the resistor R2.
A velocity amount signal corresponding to the velocity of the actuator 2 is detected at a connection point X2 with the.

The signals detected at the connection point A and the connection point B are passed through the DC blocking coupling circuit of the capacitors C2 and C3, and the operational amplifier OP, resistor R4, resistor R5, resistor R6, resistor R7, and After being amplified by the differential amplifier circuit including the capacitor C4, the speed characteristic of mechanical resonance is adjusted to a predetermined level by the level adjusting circuit using the adjusting volume VR based on the resonance frequency fo of the actuator and the sharpness Qo of the resonance.

The adjusted speed amount signal is the C
The control amount input to the D control IC and fed back to the actuator by the IC is combined with the error signal.

As a result, the velocity characteristic of the mechanical resonance of the actuator is properly adjusted with respect to the total gain characteristic of the tracking servo, and the adjusted momentum is fed back to the actuator 2 via the driver circuit 4.

[0033]

As described above, the optical information recording / reproducing apparatus of the present invention
According to
Vibration amplitude, velocity and acceleration respectively, or mechanical
A combination of resonance amplitude, velocity and acceleration
Motion detection means is integrated with the actuator to detect
Resonance frequency of mechanical resonance characteristic
Adjust to a certain level in relation to the number fo and the sharpness Qo of the resonance
With the adjusted momentum and the error detector of the optical pickup
Driver circuit that synthesizes the detected error signals
Since it is configured to return to the actuator via
In relation to the mechanical resonance of the actuator, the resonance frequency fo and
The sharpness Qo of the resonance is due to the optical pickup and its optical pickup.
Consider various factors such as vibration resistance of the device on which the cap is placed
Can be decided arbitrarily.

Further, since the present invention can be applied without complicating the servo mechanism of the optical pickup, the material development and the optical pickup design period for obtaining a stable servo system can be shortened, and the servo of the optical pickup can be shortened. The cost required for control can be reduced, and the effect is great.

[Brief description of drawings]

FIG. 1 is a block diagram showing a principle configuration in which the present invention is applied to a servo system for reproduction control of a tracking servo.

FIG. 2 is a mechanical resonance characteristic diagram showing the relationship between the frequency characteristics before and after returning to the actuator for each of amplitude, velocity and acceleration of mechanical resonance by the actuator in the principle configuration of the present invention. 2a shows an amplitude characteristic, FIG. 2b shows a velocity characteristic, and FIG. 2c shows an acceleration characteristic.

FIG. 3 is a circuit diagram of a main part of an embodiment in which the present invention is embodied in a CD player, regarding a velocity characteristic of mechanical resonance of the actuator described in FIG. 2b.

FIG. 4 shows a relationship between frequency and total gain characteristic for mechanical vibration of a conventional actuator, and FIG. 4a shows a generally required tracking servo total gain characteristic diagram. Also, the solid line in FIG. 4b shows the overall gain characteristic A before shifting the resonance frequency to the high band, and the broken line shows the overall gain characteristic B after shifting the resonance frequency to the high band.

FIG. 5: Conventional general resonance frequency fo and resonance sharpness Q
It is a total gain characteristic showing the relationship of o.

[Explanation of symbols]

 1 Optical pickup 2 Actuator 3 Error detector 4 Driver circuit 5 Momentum detecting means 6 Level adjusting circuit 7 Signal combining circuit

Claims (1)

[Claims] 1. An information recording / reproducing apparatus for recording / reproducing information on / from a recording medium using an optical pickup, an actuator type pickup, an error detecting means for detecting an information track scanning error by the pickup, and the pickup. And a means for detecting the momentum of the actuator, an adjusting means for adjusting the momentum detected by the momentum detecting means to a predetermined value, and a signal synthesizer for synthesizing the error signal and the momentum adjusted by the adjusting means. An optical information recording / reproducing apparatus comprising: means and a driving means for controlling the actuator based on an output of the signal synthesizing means.