JPH0467691B2 - - Google Patents

Description

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

2. Description of the Related Art Address signals called address signals are provided on recording tracks of disks in order to search for and record or reproduce desired portions, and are used for searching 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, the head movement during the coarse search is divided into coarse search, in which the optical head is moved without reading the address signal, and fine search, in which the optical head is moved while reading the address signal. By increasing the speed, random access is performed at high speed.

An example of a conventional coarse search method will be described below with reference to the drawings. FIG. 5 shows a conventional coarse search method. In FIG. 5, 20 is an optical disk, and the optical disk 20 has an information track having an address signal called an address. 21
The motor controls the rotation of the optical disk 20 to a predetermined rotation speed. Reference numeral 22 denotes an optical head for recording and reproducing information on the optical disk 20. A linear motor 23 moves the optical head 22 in the radial direction of the optical disk 20 at high speed. 24 is a position sensor;
The position of the optical head 22 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 that provides an address signal of the information track to be searched on the optical disk 20, and 27 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 explained below.
(For example, Japanese Patent Application No. 57-64331) In other words, when the address of the information track to be searched on the optical disk 20 is input to the target address input terminal 29, it is converted to a voltage value by the DA converter 27, and the address is converted to a voltage value by the differential amplifier 25. is input to the optical head 22.
The drive amplifier 26 drives the linear motor 23 to move the optical head 22 and complete the rough search operation.

Problems to be Solved by the Invention However, in the above configuration, the differential amplifier 2 is not activated until the optical head reaches the target position.
Since the output of 5 becomes 0 and the optical head moves backwards to the target value once the target position has been exceeded, the rough search time is long.

In view of the above problems, the present invention is intended to perform a faster rough search operation.

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 amplitude corresponding to the position. a first comparator that compares an output having a value in the direction and an output having a value in the amplitude direction corresponding to a movement target value of the optical head and outputs an amplitude output difference signal; and a first comparator that outputs an amplitude output difference signal; When I heard it,
A second circuit that compares the amplitude control means to a constant value with the output of the speed detector that outputs a value in the amplitude direction corresponding to the moving speed, and outputs a difference signal.
The optical head is equipped with a comparator, and is configured to detect that the optical head approaches the target value before reaching the target position, and apply a reverse torque to the linear motor that moves the optical head.

Effect 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 provide feedback compensation to the amplifier that drives the linear motor. By implementing this, 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 of a first embodiment of the present invention.

In FIG. 1, a is an input signal indicating a DC voltage value indicating a target position of an optical head (not shown) that can be moved by a linear motor 6. In FIG.
1 is a comparator, 2 is an equalizer to optimize the response of the system, 3 is a limiter, 4 is a comparator, 5 is a drive amplifier, and the linear motor responds to the output voltage of the drive amplifier 5. and move. 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 constructed as described above will be explained below using the timing chart shown in FIG.

First, the input a corresponds to the target position of the optical head.
When a DC voltage V ₂ is applied, the DC voltage V ₂ is compared with the DC voltage V ₁ corresponding to the position, which is the output of the position detector 8, by the comparator 1, and the difference is passed through the equalizer 2 to the limiter (amplitude limiter). The limiter 3 operates from time t ₁ to t ₃ shown on the time axis, and the output of the limiter 3 shows a constant value V ₃ . The moving speed of the linear motor 6 is detected by a speed detector 7, resulting in a signal as shown in waveform D. That is, it increases from time t ₁ to t ₂ and becomes constant from t ₂ . 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.
output begins to decline.

On the other hand, since the linear motor 6 continues to move due to inertia, the output of the speed detector 7 is held at a constant value, the output of the comparator 4 changes in the opposite direction, and the output of the drive amplifier 5 has a waveform. As shown in E, a voltage value giving reverse torque is output, and the linear motor 6 suddenly stops. That is, the reverse torque can be applied to the linear motor 6 before the target value.

As described above, according to this embodiment, the limiter 3 is provided between the target value and the output of the position detector 8, and a minor loop is provided to compare the output of the limiter 3 and the output of the speed detector 8, thereby achieving smooth operation. acceleration,
This makes it possible to realize speed reduction and increase the speed of the rough search operation of the optical head.

Furthermore, by making the limit value V ₃ of the limiter 3 variable using a volume etc., the speed detector 7,
The timing fluctuations in applying the reverse torque to the linear motor, which occur due to variations in the sensitivity of the position detector 8 and the thrust of the linear motor 6, and the fluctuations in the high-speed movement speed of the optical head are optimized for each individual device. can be adjusted to

FIG. 3 shows an embodiment of the variable limiter.

In FIG. 3, 9 is an operational amplifier, which multiplies the output v _i of the equalizer 2 by R ₁₁ /R ₁₀ by resistors 10 and 11 having resistance values R ₁₀ and R ₁₁ , and outputs a position error signal v _p
Output. After the output signal v _p is divided by a volume 14, it is fed back to the inverting input side of the operational amplifier 9 through a limiter composed of diodes 12 and 13. In this embodiment, in order to stably operate the limiter, the resistance values of resistors 10, 11 and volume 14 are set to R ₁₀ , R ₁₁ , and R ₁₄ .
R ₁₀ , R ₁₁ >> R ₁₄ is made to hold true.

With this configuration, if the volume 14 is set to the point A side, the output limit value of the position error signal v _p will be approximately ±0.7 V due to the forward voltage of the diode. In addition, if the limiter is set on the grounded point B side, the limiter will not operate, and the limit value can be set for each device at the midpoint between points A and B. can be optimally matched.

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 Figure 3, and the volume 1
5 is added, so that the voltage supplied to the diodes 12 and 13 can be adjusted independently.

In the case of this embodiment, the polarity output from the equalizer 2 changes depending on the access direction (inner circumference → outer circumference, outer circumference → inner circumference), so the limit value of the limiter is adjusted according to the polarity, and the diode characteristics are adjusted. Not only can variations be absorbed, but the influence of the elastic load on the signal line connected to the optical head can also be reduced, 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 effects 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 disk-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 combine the speed signal and the amplitude-limited difference signal. By driving and controlling the linear motor based on the difference between the two positions, it is possible to achieve very stable and high-speed positioning of the optical head.

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

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an optical information recording/reproducing apparatus 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 apparatus. 1, 4...Comparator, 2...Equalizer, 3...Limiter, 5...Drive amplifier, 6...Linear motor, 7...
Speed detector, 8...Position detector.

Claims (1)

[Scope of 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 linear motor configured to detect the position of the optical head. , compares the output of a position detector that outputs a value in the amplitude direction corresponding to the position with an output having a value in the amplitude direction corresponding to the target position of the optical head in order to control the movement of the optical head; a first comparator that outputs an amplitude output difference signal; an amplitude limiter that sets the amplitude output difference signal to a constant value when the amplitude exceeds a certain amplitude; and detects the output of the amplitude limiter and the moving speed of the optical head. and a second comparator that compares the output of the speed detector that outputs the value in the amplitude direction corresponding to the moving speed and outputs an amplitude output difference signal, and the output of the second comparator The above linear motor is driven and controlled by the signal,
An optical information recording/reproducing apparatus characterized in that the optical head positioning operation is performed. 2. The optical information recording and reproducing apparatus according to claim 1, wherein the limit value of the amplitude limiter is variable. 3. The optical information recording/reproducing apparatus according to claim 1, wherein the limit value of the amplitude limiter is changed depending on the access direction of the optical head.