JPS62140280A - Eccentricity correcting circuit for track access - Google Patents

Abstract

PURPOSE:To improve the precision of landing at a target place and to speed up access by detecting the number of eccentric tracks of disk half rotation, and finding the eccentricity correcting value until the time when a pickup lens reaches the target place and adding it to the counted value of the number of traverse tracks. CONSTITUTION:Traverse track waveform signals from sensors 15, 19, and 20 are converted into clock signals to actuate a FF18, whose Q output goes up to 'H' through a half disk rotation; and the quantity of eccentricity of the number of tracks that the sensors cross is held in a counter 6 at the end of one turn. A microcomputer 1 calculates an eccentricity correcting value up to the target place on the basis of an input eccentricity quantity according to a track access instruction and the track conversion value obtained by adding the calculated value to the number of traverse tracks up to the target value is preset in a counter 7. Then, the pickup lens moves radially on a disk in rotation with a pickup mechanism feed signal from the microcomputer 1, the counter 7 outputs a coincidence signal when a clock equal to a track converted value is inputted, and the microcomputer 1 stops the driving of a motor 14, thereby finishing the access.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a track access eccentricity correction device, and in particular, in an optical disc player that performs optical reproduction, the present invention is used to align a pickup lens with a desired recording track during reproduction. The present invention relates to an eccentricity correction device for track access suitable for moving to a position quickly and with high precision.

[Background of the invention]

The conventional eccentricity correction device for track access is
As described in Japanese Patent No. 47491, the position of the pickup lens is maintained, and at the moment when a desired track moves due to eccentricity, track servo control is applied to make it follow the track.

However, this eccentricity correction device merely detects the center position and peak position of eccentricity, and does not take into account the amount of eccentricity.

In other words, if track access is performed without considering the amount of eccentricity, the pickup lens in an optical disc player will quickly use up the given number of tracks due to the influence of the eccentricity of the disc while moving in the radial direction of the disc. , the pickup lens lands in front of the target location. Therefore, 7':c is not possible unless the pickup lens is moved again from this landing point to the target point.

Therefore, there is a drawback that the track access accuracy is low and it takes time for the pickup lens to reach the target location.

[Purpose of the invention]

The present invention has been made to eliminate the above-mentioned drawbacks, and its purpose is to reduce the number of tracks (hereinafter referred to as
It is an object of the present invention to provide a track access eccentricity correction device that suppresses deterioration in landing accuracy at a target location caused by inability to accurately count the number of tracks crossed (referred to as the number of tracks traversed) and enables high-speed access.

[Summary of the invention]

To achieve the above object, the present invention detects the number of eccentric tracks in half a rotation of the disc, and calculates the eccentricity correction value from the current position to the target value by a pickup lens that moves in the radial direction of the disc. The present invention is characterized in that the eccentricity correction value is calculated based on the number of eccentric tracks, and this eccentricity correction value is added to the calculated value of the number of traversal tracks during the rough search, so that the rough search is performed as if in a modern state without eccentricity.

[Embodiments of the invention]

The present invention will be described in detail below with reference to the drawings. FIG. 1 is a block diagram of one embodiment of the present invention. In the figure, reference numeral 1 indicates a microcomputer (
(hereinafter abbreviated as microcomputer), which includes a disk motor servo circuit 2, a tracking servo circuit 3, a pickup mechanism feed motor servo circuit 4, and various counters 5.
~7 are connected.

A disk motor 9 is connected to the disk motor servo circuit 2 via a driver 8, and a comparator 10 for detecting the sine wave drive voltage of the disk motor 9 is connected to the input side of the counter 5. . Further, the tracking servo circuit 3 is connected to a tracking coil 12 via a driver 11.
is connected to the pickup mechanism feed motor servo circuit 4
A pickup mechanism feed motor 14 is connected via a driver 13 to the pickup mechanism feed motor 14 .

On the other hand, an amplifier 16. Comparator 17. The D terminals of the D-type flip-flop 1B are connected in series, and the output side of the comparator 17 and the input side of the counter 7 are connected. Furthermore, an amplifier 21.22 is connected to each of the two sub-sensors 19.20 for 3-spot detection, and a comparator 24 is connected to the output side of a synthesis amplifier 23 that combines the outputs of both amplifiers 21.22. There is.

The output side of the AND gate 25 to which the output side of the comparator 24 and the output terminal Q of the flip-flop 18 are connected is as follows.
It is connected to the input side of the counter 6.

Here, parts 6.15 to 250 constitute eccentric track number detection means, and parts 5,100 constitute disk rotation time detection means, respectively.

Next, the operation will be explained with reference to the signal waveform diagrams shown in FIGS. 2 and 6 and the flowchart shown in FIG. 4.

First, clear the counters (Figure 4, Step 4-2)
) After that, the microcomputer 1 outputs the tracking coil fixing signal 26 to fix the tracking coil 12 in the tracking direction (FIG. 4, step 4-6). Additionally, the microcomputer 1 outputs a drive signal 27, and the disk motor servo circuit 2. A disk motor 9 is driven via a driver 8.

At this time, the sine wave drive voltage 2B (
5) is converted into a clock wave 29 (FIG. 3b) by the comparator 10 and input to the counter 5. The time for one rotation of the disk is detected by the output of the counter 5, and a detection signal is supplied to the microcomputer 1.

On the other hand, as the disk is rotationally driven by the disk motor 9, a transverse track waveform signal 30 (α in FIG. 2) amplified by the amplifier 16 is output from the main sensor 15.
is output from the sub-sensor 19.20, and the amplifier 21.
22 and a composite (differential) amplifier 23, a cross-track waveform signal 31 (FIG. 2C) is output.

The cross track waveform signal from the main sensor 15 is
Clock waveform signal 32 (second
Figure-er). In addition, the sub-sensor 19.
The cross-track waveform signal from 20 is sent to comparator 24
is converted into a clock waveform signal 33 (FIG. 2d).

The clock waveform signal 32 is applied to the D-type flip-flop 18.
When the clock waveform signal 33 is input to the clock α terminal, the Q output level of the tiD type 7 lip-flop for one day depends on the level of the signal input to the D terminal at the rising edge of the signal input to the clock α terminal. do. That is, if the level of the signal input to the D terminal is H,
The Q output becomes H level, and conversely the D terminal input signal 7
- If the level is L, the Q output becomes L level.

As can be seen by comparing the clock waveform signals 32 and 36, the level of the clock waveform signal corresponding to the rising edge of the clock waveform signal 52 becomes H level during half a revolution of the disk, and becomes L level during the other half revolution. Therefore, the Q terminal output of the D flip-flop 18 outputs an H level signal during half a revolution of the disk, and only during this period the AND gate 2
Open 5. Therefore, at the end of one rotation of the disk, the counter 6 holds the number of tracks crossed by the sub-sensor during half a rotation of the disk, that is, the amount of eccentricity.

On the other hand, if the disk motor 9 is, for example, a DD motor and magnetized with 8 poles, the disk motor 9 makes one revolution in four cycles of the sine wave drive waveform 28 (see FIG. 3 (α)). Therefore, when four pulses are input to the counter 5, the disk rotates once. this is,
It can be seen that the output of the counter 5 becomes wl,11.

The microcomputer 1 monitors the output of the counter 5 (Fig. 4, step 4-4), and the output is "1°11".
Then, the count value of the counter 6, that is, the amount of eccentricity
(Figure 4, Step 4-5) and convert it into the internal R
Write to AM (not shown) (Figure 4, Step 4-6)
.

Next, the microcomputer 1 determines whether or not there is a track access command (FIG. 4, step 4-7), and if there is a track access command, the eccentricity correction value rLtx to the destination is calculated by the input eccentricity Calculated based on. here,
t is the absolute time required to move the pickup lens from the current location to the target location, and t is the number of rotations of the disk per unit time.

A track conversion value obtained by adding the eccentricity correction value rLtx calculated above to the number of tracks traversed to the destination known in advance is preset in the counter 7 (Fig. 4, Step 4-8).
). Note that this counter 7 is, for example, a subtraction counter, and although it is shown separately from the microcomputer 1 in the illustrated example, it may be built in the microcomputer 1.

Following the above operations, when the microcomputer 1 outputs a pickup mechanism feed signal, the pickup mechanism feed motor servo circuit 4. The pickup mechanism is sent via the driver 13 and the motor 14 is driven (Fig. 4, Step 4).
-9).

Due to this drive, the pickup lens moves in the radial direction of the rotating disk, and based on the cross track waveform signal 30 output from the main sensor 15, a clock signal 32 is sent from the comparator 17 to the counter 7.
is input. Then, the counter 7 outputs a coincidence signal 34 to the microcomputer 1 when the number of clock signals equal to the track conversion value inputted in advance is inputted.

The microcomputer 1 determines whether or not there is a coincidence signal 34 from the counter 7. When the microcomputer 1 detects the coincidence signal 34 (FIG. 4, step 4-10), it stops the drive of the pickup mechanism and the feed motor 14, and moves the truck. This ends the access operation.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, since the eccentricity correction amount is added to the calculated value of the number of tracks to be traversed and the rough search is performed in an ideal state without eccentricity, the rough search accuracy is improved. access time is reduced. In addition, the simple structure and low cost achieve the following effects.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a block diagram showing a track access eccentricity correction device according to an embodiment of the present invention, FIGS. 2 and 6 are timing diagrams showing signal waveforms at various parts in FIG. FIG. 4 is a flowchart showing the operation of the processing device. DESCRIPTION OF SYMBOLS 1...Microcomputer, 2...Disk motor servo circuit, 3...Tracking servo circuit, 4...Pickup mechanism feed motor servo circuit, 5-
7...Counter, 8,11.13...Driver, 9...Disc motor, 10,17.24...
Controller, 12...Tracking coil, 14...Pickup mechanism feed motor, 15...Main sensor, 16, 17, 21.22.23...Amplifier, 19.20...Sub sensor, 18 ...D type flip-flop, 25...and gate.

Claims (4)

[Claims] (1) Eccentric track number detection means for detecting the number of eccentric tracks in half a rotation of the disk, disk rotation time detection means for detecting the time for one rotation of the disk, and a disk rotation time detection means for detecting the number of eccentric tracks in one half rotation of the disk; Latch the number of eccentric tracks, calculate the eccentricity correction amount to the target location based on the number of eccentric tracks, add it to the calculated number of tracks to cross, and output a stop signal when the number of tracks to cross during actual access matches the added value. 1. A track access eccentricity correction device comprising: processing means for correcting track access eccentricity. (2) The eccentric track number detection means includes a 3-spot detection main sensor and two sub-sensors, a first comparator that converts the output of the main sensor into a clock waveform, and a combined output of the two sub-sensors that converts into a clock waveform. a second comparator that inputs the output of the first comparator to the D terminal, and inputs the output of the second comparator to the CK
The device comprises a D-type flip-flop input to a terminal, an AND gate inputting the output of the D-type flip-flop and the output of the second comparator, and a counter counting the output of the AND gate. A track access eccentricity correction device according to claim 1. (3) The disk rotation time detection means comprises a comparator that converts the sine wave drive voltage of the disk motor into a clock waveform, and a counter that counts the output of this comparator. The described track access eccentricity correction device. (4) The track access eccentricity correction device according to claim 1, wherein the processing means is a microcomputer.