JPH02162534A - Information reproducing device - Google Patents

Abstract

PURPOSE:To improve the stopping accuracy by setting a max. velocity with a driving means for a read means in accordance with a moving distance of a moving means. CONSTITUTION:When a moving amt. is given from a CPU 1 to an optical head 14, a max. velocity is calculated by a control part 7 for a linear motor LM in accordance with the moving amt. This max. velocity is set as a slightly slower velocity than a max. velocity at the time of controlling acceleration to be constant in the moving distance. Then, velocity reference information (VRF) is calculated according to the rest of the moving amt., and this is compared with the calculated max. velocity. In the case of the VRF being slower, the LM is driven at the calculated VRF. On the other hand, when the VRF is faster, the LM is driven at the calculated max. velocity. After the LM reaches the max. velocity, the VRF is conformed with an actual velocity VLM, and the LM is controlled at the velocity corresponding to the VRF in terms of the max. velocity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an information reproducing apparatus that reproduces information recorded on an optical disc by moving an optical head, for example.

(Prior art) For example, when recording information on an optical disc,
When reading out information, the optical head is moved to a desired position by a linear motor, and recording or reproduction is performed in this state.

Conventionally, the movement of the optical head and the control of the linear motor were performed using a speed reference stored in the linear motor control section.
This is done by referring to a table.

FIG. 4 shows a conventional speed reference table. In the figure, VRF indicates speed reference information, and VLM indicates the actual speed of the linear motor corresponding to this speed reference information VRF.

As is clear from the figure, conventionally, the speed of the linear motor is controlled using constant speed reference information VRF regardless of the moving distance of the optical head (access distance I4), and when the linear motor starts operating, the speed of the linear motor is controlled. It was giving speed reference information.

Therefore, before the actual speed VLM of the linear motor reaches the maximum speed, the linear motor decelerates and stops without following the deceleration curve of the speed reference information VRF. Therefore, the stopping accuracy was lowered.

Furthermore, when the linear motor control system operates according to the speed reference information, it is expressed as a first-order lag system, but when it does not operate according to the speed reference information, it may operate in an oscillatory manner. The stopping accuracy was further reduced.

(Problems to be Solved by the Invention) This invention solves the problem that stopping accuracy is reduced due to setting the maximum speed at the start of operation, regardless of the moving distance of the optical head. The object of the present invention is to provide an information reproducing device that can improve stopping accuracy.

[Structure of the Invention] (Means for Solving the Problems) In order to solve the above problems, the present invention provides a reading means for reading information recorded on a recording medium, and a reading means that moves the reading means along the recording medium. and a driving means for driving the moving means by setting a maximum speed according to the moving distance of the moving means.

(Operation) That is, the present invention sets the maximum speed by the driving means according to the travel distance of the moving means, and makes the time for the moving means to reach the maximum speed less than half of the entire travel time. , it is possible to improve stopping accuracy.

(Example) Hereinafter, one example of the present invention will be described with reference to the drawings.

In FIG. 1, the CPUI controls the entire device. A bus turn 2 is connected to this CPUI. The pass line 2 is connected to a memory 3 in which CPU operation programs, etc. are stored, as well as a laser control section 4, a focusing control section 5, a tracking control section 6, a linear motor control section 7, a motor control section 8, and a video controller. A signal processing section 9 is connected.

The motor control section 8 drives a motor 12 in accordance with a control signal supplied from the CPUI, and the motor 12 rotates the first disk 13 at, for example, a constant speed.

Recording and reproduction of information on the optical disc 13 is performed by an optical head 14. This optical head 14 is driven by a linear motor LM.

The linear motor control unit 7 drives and controls the linear motor LM according to a control signal supplied from the CPU 1, and stores a CPU 7A, a program for controlling the operation of the CPU 7A, speed reference information, etc. memory 7B.

It is composed of a drive circuit 7C and the like that drives the linear motor LM under the control of the CPU 7A.

A drive coil 15 is connected to this linear motor control section 7, and this drive coil 15 is fixed to a movable section (not shown) of the linear motor LM.

A permanent magnet is provided in a fixed part (not shown) of the linear motor LM, and when the drive coil 15 is excited by the linear motor control part 7, the optical head 14 is moved in the radial direction of the optical disk 13. Ru.

Further, a linear motor position detector 16 is connected to the linear motor control section 7 . This linear motor position detection:!
The V 16 is opposed to an optical scale 17 provided on the optical head 14, and supplies a position signal of the optical head 14 to the linear motor controller 7 by detecting the optical scale 17.

On the other hand, the optical head 14 is provided with a semiconductor laser 18 . This semiconductor laser 18 is connected to the laser control section 4. This control unit 4 is a CPU
The semiconductor laser 18 is driven according to a control signal supplied from the controller.

The laser light generated from this semiconductor laser 18 is transmitted through one collimator lens, a polarizing beam splitter 20, and a λ/4
The light is irradiated onto the optical disc 3 via the plate 21 and the objective lens 22, and the reflected light from the optical disc 13 is transmitted to the χ·1 object lens 22, the λ/4 plate 21, and the polarizing beam splitter 2o.
One of the lights separated by the half prism 23 is guided to a pair of trunking position sensors 25 via a condenser lens 24 .

The other light beam separated by the half prism 23 is guided to a pair of focus position sensors 28 via a condenser lens 26 and a knife lens 27 .

Further, a detector PD is provided near the semiconductor laser 18 to detect monitor light generated from the semiconductor laser 18. This detector PD is connected to the laser control section 4, and an output signal corresponding to the monitor light outputted from this detector PD is supplied to the laser control section 4.

Further, the objective lens 22 is held by a wire or a leaf spring (not shown), and the objective lens 22 is
The driving coil 29 moves the lens in the focusing direction (the optical axis direction of the lens), and the driving coil 30 allows it to move in the tracking direction (the direction orthogonal to the optical axis of the lens).

Furthermore, the output signal of the tracking position sensor 25 is
The signal is supplied to the tracking control section 6 via the differential amplifier OPI. The tracking difference signal outputted from the tracking control section 6 is supplied to the linear motor control section 7 and also to the drive coil 30 in the tracking direction via the amplifier 31, and a tracking operation is performed by the objective lens 22. be exposed.

Further, the tracking control unit 6 drives the drive coil 30 in response to a track jump signal supplied from the CPU 1, moves the objective lens 22 by one track, and moves the laser beam. The output signal of the tracking position sensor 25 is
The signal is supplied to the video signal processing section 9, and the image information and the like are reproduced in the video signal processing section 9. The reproduced image information and the like are supplied to the CPUI via the pass line 2.

Further, the focus position sensor 28 outputs a signal regarding the focus point of the laser beam, and this signal is supplied to the focusing control section 5 via the differential amplifier OP2. This focusing control section 5 controls the semiconductor laser 1 according to the output signal of the differential amplifier OP2.
The output signal of the focusing controller 5 is sent to the focusing drive coil 2 via an amplifier 32.
9. The focusing control unit 5 also has the control unit 5, for example, in the initial focusing operation
A control signal is supplied from the PUI, and according to this control signal, the laser beam is controlled so that it is always in just focus on the optical disk 13.

In the above configuration, operation control of the linear motor LM will be explained with reference to FIG. 2.

First, when the amount of movement of the optical head 14 is supplied from the CPU, the maximum speed corresponding to this amount of movement is calculated. This maximum speed is usually controlled by constant acceleration control (Ba
The speed is set to be slightly slower than the maximum speed when performing (bang control) (step 5TI). After this, speed reference information is calculated according to the remaining travel distance (step 5T2), and this calculated speed reference information is compared with the maximum speed calculated in advance (step 5T3).
).

As a result, if the calculated speed reference information is slower than the maximum speed, the linear motor LM is driven by the calculated speed reference information (step 5T4).
), if the calculated speed reference information is faster than the maximum speed, the linear motor LM is driven at the previously calculated maximum speed (step 5T5). and,
It is determined whether the movement has ended (step 5T6),
If the movement is not completed, the above operation is repeated (
Step ST6-2).

According to the above embodiment, while the optical head 14 is moving, the remaining movement distance is always calculated, speed reference information according to this remaining movement amount is calculated, and this speed reference information and the pre-calculated maximum speed are If the maximum speed is slower, the linear motor L
After the linear motor LM reaches the maximum speed by driving the speed reference information V as shown in FIG.
The RF and the actual speed VLM of the linear motor LM can be substantially matched. Therefore, the sunar motor LM
When the maximum speed is reached, the speed will be controlled according to the speed reference information, and after this,
In the deceleration operation, it is possible to decelerate according to the deceleration curve of the speed reference information, so that stopping accuracy can be improved.

Note that this invention is not limited to the above embodiments,
Of course, various modifications can be made without departing from the gist of the invention.

[Effects of the Invention] As described above in detail, according to the present invention, the driving means sets the maximum speed according to the moving distance of the moving means,
By making the time it takes for the moving means to reach its maximum speed less than half of the total moving time, it is possible to provide an information reproducing device that can improve stopping accuracy.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIGS. 2 and 3 are diagrams for explaining the invention in detail, and FIG. 4 is for explaining speed control of a conventional linear motor. FIG. 1...CPU, 7...Linear motor control unit, 7A.
...CPU, 13...optical disk, 14...optical head.

Claims (1)

[Claims] A reading means for reading information recorded on a recording medium, a moving means for moving the reading means along the recording medium, and a maximum speed set according to the moving distance of the moving means. An information reproducing device comprising: driving means for driving the moving means.