JP2612556B2 - Position control device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position control device, and more particularly to a position control device having a first drive unit for performing approximate position control and a second drive unit for performing minute position control. It relates to a control device.

[Prior Art] As an example of a position control device having a first driving unit for performing approximate position control and a second driving unit for performing minute position control, a two-stage actuator including an objective lens driving unit and a head driving unit is used. There is an objective lens position control device of the optical information recording / reproducing device. Hereinafter, an objective lens position control device will be described as an example of a conventional position control device.

FIG. 4 is a block diagram of a drive control circuit of the objective lens position control device.

In FIG. 4, 1 is an adder / subtracter, 2 is a phase compensation circuit of a tracking actuator 4 as an objective lens driving means, 3 is a phase compensation circuit of a linear motor 5 as a head driving means, and 6 and 7 are tracking actuators 4 respectively. Displacement X of the objective lens and displacement x 'of the head by the linear motor 5, 8 is a displacement x "obtained by adding the displacement x and the displacement x', 23 is an adder, 19 is a track position Y with respect to a laser beam light serving as a target value. Is input terminal, and a deviation M between the track position Y and the displacement x ″ which is an output response is a so-called tracking error signal (a relative position between a laser beam irradiated on an information recording medium and the information track). Detection signal). The tracking error signal is, for example, "Optical Memory Magneto-optical Memory Integrated Technology" published by Science Forum, Inc. on October 31, 1983.
Pages 42-43, or "Introduction to Video Discs and DADs" published by Corona Co., Ltd. on November 1, 1982, pages 138-
It is detected by a well-known method as described on page 140.

Hereinafter, a position control method of the objective lens position control device having the above configuration will be described.

The objective lens is moved by moving the head to an approximate position by the linear motor 5 and minutely moving the objective lens by the tracking actuator 4. However, when the moving distance exceeds the movable range of the tracking actuator 4, the linear motor 5 5 at the same time.

In FIG. 4, the track position Y is given to the adder / subtractor 1, and the displacement x of the objective lens by the tracking actuator 4 and the displacement x 'of the head by the linear motor 5 are shown.
Is subtracted. The signal M after the subtraction is a so-called tracking error signal, which is phase-compensated by the phase compensating circuits 2 and 3 to obtain the tracking actuator 4 and the linear motor. Then, the displacement x ″ obtained by adding the displacement x of the objective lens by the tracking actuator 4 and the displacement x ′ of the head by the linear motor 5 is fed back to the adder / subtractor 1. If the signal M after the subtraction is not zero,
Further, a signal is sent to the phase compensation circuits 2 and 3 to operate the tracking actuator 4 and the linear motor 5.

[Problems to be solved by the invention] However, in the position control device for the objective lens,
Since the relative displacement between the displacement of the head by the linear motor 5 and the displacement of the objective lens by the tracking actuator 4 is not detected, the relative position control accompanying the movement of both driving means cannot be performed, and the tracking direction trace of the objective lens There was a problem that high-precision positioning at the time was not possible.

An object of the present invention is to provide a position control device that enables relative position control between a first driving unit and a second driving unit, and that can perform high-speed and high-precision positioning when tracing a position control target. I do.

[Means for Solving the Problems] That is, the above-described object is to provide a second driving unit that supports a control object so as to be relatively movable and displaces the control object minutely; A first driving unit that supports the second driving unit so as to be relatively movable and roughly displaces the control object and the second driving unit;
A drive control circuit for inputting a position control signal to the first and second drive means and for feeding back the displacement of the control object by the first and second drive means to the position control signal; In the first,
A first equivalent circuit for outputting a signal simulating the magnitude of displacement of the second driving means by the first driving means when a position control signal is input to the driving means, and the second driving means And a second equivalent circuit for outputting a signal simulating the magnitude of displacement of the control object by the second driving means when a position control signal is input to the equivalent circuit. Signal, and the signals obtained by subtracting the outputs of these equivalent circuits from each other are
The present invention is achieved by a position control device according to the present invention, wherein the position control signal is fed back to the first drive means.

[Operation] According to the position control device of the present invention, an equivalent circuit of the first drive unit for performing approximate position control and an equivalent circuit of the second drive unit for performing minute position control are provided, and these two equivalent circuits are provided. As a result, an output signal simulating the magnitude of the displacement by the first driving means and an output signal simulating the magnitude of the displacement by the second driving means are produced. By extracting the signal corresponding to the dynamic displacement and driving the first driving means by this signal and the position control signal, the relative position control by the first driving means and the second driving means can be performed at high speed and high speed. Accuracy can be achieved.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings. In the description of the position control device of the present invention, an objective lens position control device of an optical information recording / reproducing device will be used. That is, the objective lens driving means is used as the second driving means,
The first drive means corresponds to the head drive means, the control object corresponds to the objective lens, and the position control signal corresponds to the tracking error signal.

FIG. 1 is a block diagram showing a first embodiment of a drive control circuit of the objective lens position control device according to the present invention.

In FIG. 1, 1 is an adder / subtracter, 2 is a phase compensation circuit for controlling the oscillation phase of a tracking actuator 4 as an objective lens driving means and an equivalent circuit 11 of the tracking actuator 4, and 3 is a linear motor 5 as a head driving means. And a phase compensation circuit for controlling an oscillation phase of an equivalent circuit 12 of the linear motor 5 and an equivalent circuit 14 of a crosstalk 13 described later. The frequency characteristics of the equivalent circuit 11 of the tracking actuator 4 are as shown in FIG. 2 (a). The frequency characteristics of the equivalent circuit 12 of the linear motor 5 are as shown in FIG. 2 (b). Reference numeral 13 denotes crosstalk, which indicates the effect of the movement of the head by the linear motor 5 on the displacement of the objective lens. 6, 7, and 9 are the displacements of the objective lens x,
The displacement x 'of the head caused by the linear motor 5 and the displacement z caused by the crosstalk 13. The displacement z due to the crosstalk 13 is a displacement of the objective lens caused by an inertial force or the like acting on the objective lens as the head moves by the linear motor 5. As is apparent from the schematic diagram of the optical information recording / reproducing apparatus shown in FIG. 3, the tracking actuator 4 mounted on the head by the linear motor 5 is used.
Move, the displacement x ′ of the head by the linear motor 5 is also the displacement of the tracking actuator 4.
Reference numeral 10 denotes a displacement x obtained by adding the displacement x, the displacement x ', and the displacement z. 15 is the equivalent circuit of tracking actuator 4
An adder 16 adds the signals from the equivalent circuit 11 of the crosstalk 13 and the signal from the equivalent circuit 11 of the tracking actuator 4 and the equivalent circuit 14 of the crosstalk 13 from the equivalent circuit 12 of the linear motor 5. An adder / subtracter 17 for adding / subtracting a signal; 17 a high-pass filter for removing low-frequency components of the signal from the adder / subtractor 16; 18 a signal from the adder / subtractor 1 and a signal from the high-pass filter 17; An output adder 19 is an input terminal for inputting a track position Y with respect to a laser beam light serving as a target value. A deviation M between the track position Y and a displacement x which is an output response is a so-called tracking error signal. .

Here, the equivalent circuit 14 will be further described. As described above, crosstalk is the effect of the movement of the head by the linear motor 5 on the displacement of the objective lens. Therefore, if a signal input to the linear motor 5 is monitored, how the head moves according to the signal is monitored. , It is possible to predict how the objective lens is displaced by the inertial force or the like due to the movement. Therefore, a circuit that predicts the movement (crosstalk) of the objective lens from the signal input to the linear motor 5 and outputs a signal indicating the predicted movement can be provided as the equivalent circuit 14 (X _LT ′). The displacement due to the crosstalk is, for example, the tracking actuator 4
By inputting various signals to the linear motor 5 in a state where no signal is input to the linear motor 5 and detecting the movement of the objective lens at that time, it can be known.

FIG. 3 is a schematic diagram of an optical information recording / reproducing device for explaining the position control device of the present invention.

Reference numeral 20 denotes an information recording medium having a multilayer structure including a magnetic film, a reflective film, a protective film, and the like. A plurality of information tracks are formed in a row on the information recording medium surface by laser light or the like. The information tracks are arranged, for example, in a concentric or spiral manner. The scanning of the information track is performed by the tracking actuator 4 and the linear motor 5. The approximate movement of the objective lens is performed by the linear motor 5, and the minute movement is performed by the tracking actuator 4. 21 is a carriage such as a tracking actuator or a linear motor, and 22 is a spindle motor for rotating the information recording medium 20.

Next, an objective lens position control method according to the position control device of the present invention will be described.

In FIG. 1, a track position Y is given to an adder / subtractor 1, and an objective lens and a displacement x by a tracking actuator 4 and a head displacement x 'by a linear motor 5 are provided.
Displacement x obtained by adding displacement z and displacement z due to crosstalk 13
Is subtracted. The signal M after the subtraction is a so-called tracking error signal, which is input to the phase compensation circuit 2 and the adder 18. In the phase compensation circuit 2, signal phase compensation is given to prevent oscillation. The signal output from the phase compensation circuit 2 is sent to the tracking actuator 4 and an equivalent circuit 11 of the tracking actuator 4.
The adder 18 adds the tracking position control high frequency component signal from the high pass filter 17. The signal output from the adder 18 is phase-compensated by the phase compensation circuit 3 and sent to the linear motor 5, the equivalent circuit 12 of the linear motor 5, and the equivalent circuit 14 of the crosstalk 13.

The tracking actuator 4 and the linear motor 5 are operated by the outputs of the phase compensation circuits 2 and 3, and the displacement x of the objective lens by the tracking actuator 4, the displacement x ′ of the head by the linear motor 5, and the displacement z by the crosstalk 13 are added. The obtained displacement x is fed back to the adder / subtractor 1. By inputting a signal to the equivalent circuit 11 of the tracking actuator 4 having characteristics as shown in FIG. 2 (a), a signal corresponding to the response of the tracking actuator 4, that is, a displacement x of the objective lens, is created. Output to A signal corresponding to the displacement z due to the crosstalk 13 is also output from the equivalent circuit 14 of the crosstalk 13 to the adder 15. The signal added by the adder 15 is sent to the adder / subtractor 16. On the other hand, the equivalent circuit 12 of the linear motor 5 having the characteristics as shown in FIG.
From the response of the linear motor 5, that is, the displacement x 'of the head.
Are sent to the adder / subtractor 16 and subtracted. The signal after the addition / subtraction is sent to the high-pass filter 17 to extract the tracking position control high frequency component signal. The tracking position control high-frequency component signal and the signal M are added by the adder 18 to control the linear motor 5, whereby the relative displacement between the head displacement by the linear motor 5 and the objective lens displacement by the tracking actuator 4 is obtained. The displacement is simulated, and highly accurate relative position control accompanying the movement of both driving means becomes possible.

Further, by providing the equivalent circuit 14 of the crosstalk 13, the displacement of the objective lens caused by the movement of the head by the linear motor 5 can be corrected.

In the embodiment shown in FIG. 1, the equivalent circuit is taken into consideration in consideration of the crosstalk accompanying the movement of the head by the linear motor 5.
Although 14, the equivalent circuit 14 can be omitted when such crosstalk is small. Such an example is shown in FIG. Figure 5 shows crosstalk 13, equivalent circuit
Except for the addition of the adder 14 and the adder 15, it is the same as the first embodiment of FIG. 1, and the same members as those of FIG. 1 are denoted by the same reference numerals, and detailed description is omitted. The second embodiment shown in FIG. 5 operates in the same manner as the first embodiment, and can obtain the same effect.

As an equivalent circuit used in the above-described position control device of the present invention, an electric equivalent circuit, a mechanical equivalent circuit, or the like is used.

[Effects of the Invention] As described in detail above, according to the position control device of the present invention, an equivalent circuit of the first drive unit for performing approximate position control and the second drive unit for performing minute position control is provided. By driving the first driving means by the output signals from these two equivalent circuits and the position control device, the relative position control of the position control target can be performed at high speed and with high accuracy.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of a drive control circuit of an objective lens position control device by the position control device of the present invention. FIG. 2 is a characteristic diagram showing a frequency characteristic of the equivalent circuit.
(A) is a characteristic diagram of an equivalent circuit of a tracking actuator, and (b) is a characteristic diagram of an equivalent circuit of a linear motor. FIG. 3 is a schematic diagram of an optical information recording / reproducing device for explaining the position control device of the present invention. FIG. 4 is a block diagram of a drive control circuit of the objective lens position control device. FIG. 5 is a block diagram showing a second embodiment of the drive control circuit of the objective lens position control device by the position control device of the present invention. 11 Equivalent circuit of tracking actuator 12 Equivalent circuit of linear motor 13 Cross-talk 14 Equivalent circuit of cross-talk 15, 18 Adder 16 Adder-subtractor 17 High-pass filter

Claims (1)

(57) [Claims] A second drive means for supporting the control object relatively movably and displacing the control object minutely; supporting the control object and the second drive means relatively movably; A first drive unit for roughly displacing the control object and the second drive unit, and a position control signal input to the first and second drive units, and a first drive unit for the first and second drive units. A drive control circuit for feeding back the displacement of the control object to the position control signal, wherein the second drive by the first drive means when the position control signal is input to the first drive means A first equivalent circuit for outputting a signal simulating the magnitude of the displacement of the means, and the magnitude of the displacement of the control object by the second driving means when a position control signal is input to the second driving means Sa A second equivalent circuit that outputs a signal simulating the above, a position control signal is input to each of these equivalent circuits, and a signal obtained by differentiating the outputs of these equivalent circuits from each other, A position control device wherein feedback is made to a position control signal input to a first driving means.