JPS61222035A - Optical information recording and reproducing device - Google Patents

Abstract

PURPOSE:To attain stable high speed positioning of an optical head by using a difference between a speed signal of the optical head and a difference signal subject to amplitude limit so as to apply drive control to a linear motor. CONSTITUTION:A DC voltage representing an object position of the optical head at an input (a) is compared with an output voltage of a position detector 8 by a comparator 1 and its difference is fed to a limiter 3 via an equalizer 2. Then the moving speed of the motor 6 is detected by a speed detector 7. On the other hand, the motor 6 continues coasting, the output of the detector 7 is kept to a prescribed value, an output of the comparator 4 is changed in opposite direction, a voltage giving a reverse torque is outputted at the output of a drive amplifier 5 to stop the motor 6 suddenly. A limiter 3 is provided to the output of the detector 8 and the object value and a minor loop comparing the output of the limiter 3 with the output of the detector 8 is provided in this way, allowing to realize smooth acceleration/deceleration thereby applying high speed positioning of the optical head.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an apparatus for recording or reproducing various information on a rotatably driven disc-shaped record carrier (hereinafter referred to as a disk) using an optical head, and particularly for high-speed retrieval. The present invention relates to an optical information recording/reproducing device that enables operation.

Conventional disks are provided with address signals called address signals on recording tracks in order to search for, record or reproduce desired portions, and are used to search for information called random access. That is, random access is an operation of reading address signals recorded on a disk, searching for the location of desired information, and writing information at a desired location.

Since address signals are intermittently recorded on some of the tracks of the disk, if the optical head is moved at high speed in the radial direction of the disk, the address signals cannot be read with sufficient accuracy. Therefore, in order to perform random access at high speed, it is divided into a coarse search in which the optical head is moved without reading the address signal, and a fine search in which the optical head is moved while reading the address signal. Random access is performed at high speed by increasing .

An example of a conventional coarse search method will be described below with reference to the drawings. Figure 5 shows the conventional coarse search method.
In FIG. 5, 2o is an optical disk, and the optical disk 2o has an information track having an address signal called an address. A motor 21 controls the rotation of the optical disc 20 to a predetermined rotation speed. 22 is an optical head and optical disk 2
Record and reproduce information on 0. A linear motor 23 moves the optical head 22 at high speed in the radial direction of the optical disc 2o. 24 is a position sensor, and an optical head 22
The position is output as a voltage value to the terminal 24a. 25 is a differential amplifier, and 26 is a drive amplifier, which controls the movement of the linear motor 23. 29 is a target address input terminal for supplying an address signal of the information track to be searched on the optical disc 2o;
7 is a DA converter that converts the target address input value into a voltage value. The operation of the coarse search block diagram configured as described above will be described below.

(For example, Japanese Patent Application No. 57-64331) That is, when the address of the information track to be searched on the optical disk 2o is input to the target address input terminal 29, it is converted into a voltage value by the DA converter 27 and the differential amplification is performed. The voltage is input to the device 25 and compared with the voltage value of the terminal 24a indicating the position of the optical head 22, and the linear motor 23 is driven by the drive amplifier 26 so that the difference becomes 0, and the optical head 22 is moved. , ends the coarse search operation.

Problems to be Solved by the Invention However, in the above configuration, the output of the differential amplifier 25 becomes 0 only when the optical head reaches the target position. This method has the disadvantage that it takes a long time to perform a rough search because it performs an operation of reversing the target value.

In view of the above-mentioned problems, the present invention is intended to perform a coarse search operation at a higher speed.

Means for Solving the Problems In order to solve the above problems, the present invention provides a position detector for detecting the position of an optical head moved by a linear motor, a speed detector for detecting the speed, and an output of the position detector. and an output indicating a target movement value of the optical head, and outputs a difference signal; an amplitude limiting means for setting the difference signal to a constant value when the difference signal exceeds a constant value; A second comparator compares the output with the output of the speed detector and outputs a difference signal, and detects that the optical head approaches the target value before reaching the target position. The structure is such that a reverse torque is applied to the linear motor that moves the .

Effect of the Invention The present invention uses the above-described configuration to compare the voltage indicating the speed of the linear motor and the voltage indicating the position of the linear motor after passing through an amplitude limiting means, and performs feedback compensation on the amplifier that drives the linear motor. As a result, the optical head can be moved at high speed and stopped quickly at the target point.

Embodiment A block diagram of an embodiment of the present invention will be described below. FIG. 1 shows a block diagram in a first embodiment of the present invention.

In Fig. 1, a is an input signal, and the linear motor 6
2 shows a DC voltage value indicating a target position of an optical head (not shown) that can be moved.

1 is a comparator, 2 is an equalizer to optimize the response of the system, 3 is a limiter, 4 is a comparator, 6 is a drive amplifier, and the linear motor is connected to the output voltage of the drive amplifier 5. Move in response. 7 is a speed detector that detects the moving speed of the linear motor 6, and 8 is a position detector that detects the position of the linear motor 6.

The operation of the optical head position control system configured as described above will be explained below using the timing chart shown in FIG.

First, a DC voltage v2 indicating the target position of the optical head is applied to input a.
When given, the DC voltage v2 is compared with the output ■ of the position detector 8 by the comparator 1, and the difference is supplied to the limiter 3 via the equalizer 2 from time t1 to t3 shown on the time axis. operates, and the output of limiter 3 shows a constant value v3.

The moving speed of the linear motor 6 is detected by a speed detector 7,
The signal will be as shown in the waveform). That is, time t1
It increases from t2 to t2, and becomes constant from t2. Next, at time t3, when the difference between the input a and the output of the position detector 8 becomes small, the limiter 3 stops operating, so the output of the limiter 3 starts to decrease as shown in the waveform (c).

On the other hand, since the linear motor 6 continues to move due to inertia, the output of the speed detector 7 is (=cm), the output of the comparator 4 changes in the opposite direction, and the output of the drive amplifier 5 As shown in the waveform (E), a voltage value that gives reverse torque is output, and the linear motor 6 suddenly stops.In other words,
This means that a reverse torque can be applied to the linear motor 6 before the target value is reached.

As described above, according to this embodiment, by providing the limiter 3 between the target value and the output of the position detector 8, and providing a minor loop for comparing the output of the limiter 3 and the output of the speed detector 8, smooth operation can be achieved. acceleration.

This makes it possible to achieve deceleration and speed up the coarse search operation of the optical head.

Furthermore, by making the limit value 3 of the limiter 3 variable using a volume etc., it is possible to prevent the aforementioned linear Variations in the timing of applying reverse torque to the motor and variations in the high-speed movement speed of the optical head can be optimally adjusted for each individual device.

FIG. 3 shows an embodiment of the variable limiter.

In Figure 3, 9 is an operational amplifier, and equalizer 2
The output Vl is connected to a resistor 10. having resistance values R1° and R11.
11 by R11/R1° and outputs the position error signal V′. After the output signal v0 is divided by the volume 14, it is passed through a limiter composed of diodes 12 and 13.
It is fed back to the operation foot 190 inverting input side. In this embodiment, in order to stably perform the limiter operation, the resistance values of the resistor 10.11 and the volume 14 are set to R1° and R1°.
11, R14, R1°, R11) R14 holds.

With this configuration, if the volume 14 is set to the A point side, the output limit value of the position error signal v0 will be approximately ±0.7V due to the forward voltage of the diode. , the limiter stops working, and points A and B
Since a limit value can be set for each device at the midpoint between the points, the timing of the aforementioned reverse torque generation and the high-speed movement speed can be optimally adjusted.

FIG. 4 shows an embodiment in which the limit value of the limiter can be varied independently for each access direction.

Each component is the same as in FIG. 3, with the addition of a volume 15 so that the voltage supplied to the diodes 12 and 13 can be adjusted independently.

In the case of this embodiment, since the polarity output from the equalizer 2 changes depending on the direction of access (inner circumference - outer circumference, outer circumference - inner circumference), the limit value of the limiter is adjusted according to the polarity, and the diode In addition to being able to absorb variations in characteristics, it is also possible to reduce the effects of elastic loads on signal lines connected to the optical head, making it possible to achieve extremely stable access characteristics.

Furthermore, even in cases where the device must be installed at a certain degree of inclination for special purposes, the influence of gravitational acceleration due to the inclination can be reduced by adjusting the volumes 14 and 15. Furthermore, although the speed detector 7 is provided independently in this embodiment, the output of the position detector 8 may be differentiated.

Effects of the Invention As described above, the present invention provides a detector for detecting the position of the optical head when a linear motor is used to control the movement of the optical head for recording and reproducing information signals on a disc-shaped record carrier. detect the difference between the output of the device and the target position signal of the optical head, pass the difference signal through at least an amplitude limiter, detect the speed of the optical head, and compare the difference between the speed signal and the grip width limited signal. By controlling the drive of the linear motor based on the difference between the signals, it is possible to achieve extremely stable and high-speed positioning of the optical head.

In addition, by making the amplitude limiter's limit value variable, it is not only possible to achieve optimal access for each device, but also to reduce the effects of equipment tilt, optical head wiring, etc., and to increase the performance of the equipment. can be brought out to the fullest.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an optical information recording/reproducing device according to an embodiment of the present invention, FIG. 2 is a timing chart showing the operation of each part in FIG. 1, and FIGS. 3 and 4 are an embodiment of a variable limiter. FIG. 5 is a block diagram showing a conventional optical information recording/reproducing device. 1.4...Comparator, 2...Equalizer, 3...Limiter, 5...Drive amplifier, 6...Linear Motor, 7... Speed detector, 8... Position detector. Name of agent Patent attorney Toshio Nakao Other names Figure 3 Figure 4

Claims (2)

[Claims] (1) A linear motor configured to move an optical head for recording and reproducing information on a disc-shaped record carrier in the radial direction of the disc-shaped record carrier, and a position detection device that detects the position of the optical head. a first comparator that compares the output with an output representing a target position of the optical head to control the movement of the optical head, and outputs a difference signal; an amplitude limiter with a value of
a second comparator that compares the output of the amplitude limiter and the output of a speed detector that detects the moving speed of the optical head and outputs a difference signal; An optical information recording/reproducing apparatus characterized in that the linear motor is driven and controlled by a signal to perform a positioning operation of the optical head. (2) The optical information recording and reproducing apparatus according to claim 1, wherein the limit value of the amplitude limiter is variable.