JPS62164225A - Retrieving device for information track - Google Patents

Abstract

PURPOSE:To retrieve an information track with high accuracy and high stability by detecting the number of tracks where a light beam crossed on the signal of a means which divides the signal of a track shift detecting means by the signal corresponding to the light quantity irradiated on said shift detecting means. CONSTITUTION:A differential amplifier 14 changes its amplitude in proportion to the change of the reflected light quantity of a recording carrier 7. The output (c) of a divider 19 obtained by dividing the output (a) of the amplifier 14 by the output (b) of a synthesizing circuit 26 equivalent to the reflected light quantity is kept at a fixed level. Thus the output (c) has a fixed degree of margin to the reference level for comparison of a comparator 31 in a retrieving mode. Then the outputs of the comparator 31 and a pulse generator 32 are delivered with high stability and high accuracy against an optical beam 2 crossing a track. Therefore, the signal which detects the track cross of the light beam is kept at a fixed level despite the change of the reflected light quantity of the carrier 7. Thus it is possible to count accurately the number of tracks were the light beam crossed in a retrieving mode.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an information track retrieval device in an optical recording/reproducing device.

2. Description of the Related Art A conventional information track retrieval device is disclosed in, for example, Japanese Unexamined Patent Publication No. 165277/1983.

This will be explained below using FIG. 3.

A light beam 2 generated from a light source 1 such as a semiconductor laser passes through a coupling lens 3 and a beam splitter 4, is reflected by a reflecting mirror 6, and is focused by a converging lens 6 onto a disc-shaped record carrier 7. The record carrier 7 is attached to the rotating shaft of a motor 8 and rotates at a predetermined number of rotations.

The record carrier 7 has concentric or spiral grooves (hereinafter referred to as tracks) on a base material, and is composed of a recording material layer and a protective layer provided thereon. Sequential address signals are provided in advance from the inner circumference to the outer circumference. Light beam 2 reflected from recording medium 7
The 0 reflected light passes through the converging lens 6 again, is reflected by the reflecting mirror 6 and the beam splitter 4, and is irradiated onto the photodetector 9 having a two-split structure. The converging lens 6 is attached to the tracking element 1o, and the tracking element 1o is configured to be able to move the converging lens 6 in the radial direction of the recording phase 7, that is, in the direction substantially perpendicular to the track direction on the recording phase 7. has been done. light source 1, coupling lens 3, beam splitter 4, reflector 5, photodetector 9,
The moving parts of the tracking element 10 and speed detector 11 are attached to a transfer table 12, and are configured to move together in the radial direction of the recording medium 7 by a linear motor 13. . The speed detector 11 is composed of a moving part made of a rod-shaped magnet fixed to the moving table 12 and a fixed part made of a coil, and outputs a signal according to the moving speed of the transfer table 12.

Tracking control for controlling the light beam 2 focused on the record carrier 7 so that it is always positioned on the track will be described. Each signal of the photodetector 9 is transmitted to a differential amplifier 14.
The differential amplifier 14 outputs a difference signal between the respective signals of the photodetector 9. The direction of the dividing line of the photodetector 9 is the track direction of the track pattern included in the reflected light on the photodetector 9, and the signal from the differential amplifier 14 determines the positional relationship between the light beam 2 on the recording medium 7 and the track. The signal representing the track error signal, that is, the track deviation signal, is well known and will not be described in detail. The signal from the differential amplifier 14 is transmitted to the tracking element 1o via a switch 16, a phase compensation circuit 16 for compensating the phase of the tracking control system, and a drive circuit 18 for driving the tracking element 1o.

The tracking element 1o is controlled to move the converging lens 6 in accordance with the signal from the differential amplifier 14 so that the light beam 2 on the record carrier 7 is positioned on the track.

The number of turns that the tracking element 1o can move is 50051＼
The tracking control is on the order of -゛μm, and if the transfer table 12 moves significantly, the tracking control will be lost. In order to prevent this, the movement of the transfer table 12 is controlled by driving the linear motor 13f so that the tracking element 10 moves around its natural state, that is, so that the signal of the drive circuit 18 becomes zero level on average. are doing. To explain this transfer control, the signal of the differential amplifier 14 is passed through a switch 16, a phase compensation circuit 2o for compensating the phase of the transfer control system, a combining circuit 21, and a drive circuit 22 for driving the linear motor 13. , the linear motor 13 moves the transfer table 12 so that the tracking element 10 moves around its natural state. switch 1
Reference numeral 6 is for disabling tracking control and transfer control, and a synthesis circuit 21 is a circuit for synthesizing signals from the speed detector 11, the phase compensation circuit 2.degree., and a switch 23, which will be described in detail later. The switch 23 is open when the tracking control is in operation.

In order to make linear motor drive control more stable, a signal from a 26-peso speed detector 11 is applied to the linear motor 13 for speed control.

Recording and reproduction of signals will be explained. When recording a signal on a track on the recording medium 7, the intensity of the light beam 2 generated from the light source 1 is modulated in accordance with the recording signal while the tracking control and the transport control are operated. The recording material at the location irradiated with the intense light beam 2 changes state or shape, and a signal is recorded on the track on the record carrier 7. When reproducing a signal recorded on a track on the record carrier 7, the light beam 2 generated from the light source 1 is made to have a weak constant intensity while the tracking control and transport control are in operation, and the light beam 2 generated from the light source 1 is made to have a weak and constant intensity, and the light beam 2 that is reflected from the track is The light is received by the photodetector 9, and a composite signal of the respective signals of the photodetector 9 is obtained.

Note that in the optical recording/reproducing device, focusing is controlled so that the beam diameter of the light beam 2 irradiated onto the record carrier 7 is always constant, but since this is not directly related to the present invention, it will be described in detail. Avoid.

The search system is composed of an information processing control device 24 including a microcomputer. Enter the address A of the desired rack into the address input device 26. When input, the information processing control device f\24 reads address A of the track where the optical beam 2 is located from the signal of the combining circuit 26 that combines the respective signals of the photodetector 9, and ( Calculate A1-Ao). IA, -Aol≧N, (IA, -Aol is (A
, -Ao), where No is a positive integer.

), the information processing control device 24 presets the values of IA and -Aol in the counting circuit 2Y, and sends a moving direction signal to the signal generation [h1 path 28]. The movement direction signal is a signal that instructs whether to move the transfer stage 12 from the outer circumference of the recording medium 7 toward the inner circumference, or from the inner circumference toward the outer circumference.

Thereafter, the information processing control device 24 sends a signal to the switch 15 to open the switch 15 and disable the VC-Ll-1 lasogging control and transfer control, and switch 2
3 to short-circuit the switch 23 and transmit the signal from the signal generating circuit 28 to the combining circuit 21. Signal generating circuit 28 phantom: Outputs a signal corresponding to the counting output of the counting I+51 path 27 and corresponding to the moving direction signal from the information processing control device 24, and the linear motor 13 outputs a signal corresponding to the moving direction signal from the signal generating circuit 28. 12 in the direction where the desired l rank exists. The signal from the differential amplifier 14 is input to a track crossing detection circuit 29, and the track crossing detection circuit 29 outputs a pulse signal indicating that the light beam 2 on the recording medium 7 has crossed the l.rack.

The counting circuit 27 counts the signals from the track crossing detection circuit 29, detects that the light beam 2 has arrived on the 0th track (IAl-Ao), and sends a coincidence signal to the information processing control device 24. The information processing control device 24 sends a signal to the switch 23 to open the switch 23 to stop the linear motor 13, and also sends a signal to the switch 16 to open the switch 1.
5 is short-circuited to operate tracking control and transfer ffj control.

Thereafter, the information processing control device 24 reads the address A1 of the l-rack on the record carrier 7 where the light beam 2 is located.

9C, -7 (Hereinafter, this search will be referred to as a coarse search.) If Ao=:A, the search ends, but if lA, -Aol≧No, the above-mentioned rough search is performed again. Also IAl-Aol〈
If No, the information processing control device 24 opens the switch 16, sends a signal to the drive circuit 18, drives the tracking element 10, and shorts the switch 15 again, thereby performing one track interlacing scan (hereinafter referred to as this scan). After repeating this jumping IAl-Aol times, he reads the address A1 of the track where the light beam 2 is located (hereinafter this search will be referred to as a fine search). If Ao==A1, the search ends, but if AoNmuj (AO'iAl means that A and A7 are not equal), the above coarse search and fine search are repeated to find the desired track. search for.

FIG. 4 shows an operation flowchart of the information processing control device 24 during the above-described search.

As described above, during a search, the number of tracks crossed by the light beam on the record carrier is counted to measure the amount of movement. A method for detecting the track crossings 10, . . . -7 will now be described.

As mentioned above, the signal from the differential amplifier 14 is a signal representing the positional relationship between the light beam 2 and the track, that is, a track deviation signal, and as shown in FIG. When you move to the adjacent track 2,
The differential amplifier 14 outputs a sine wave signal with the period. Therefore, the track deviation signal is set to a certain level l.
It is detected that the signal from the differential amplifier 14 exceeds this level, thereby detecting that the light beam has crossed the track, and this is counted to calculate the amount of movement of the light beam. It is being measured.

Problems to be Solved by the Invention In the conventional search described above, the light beam
When the reflected light from the record carrier 7 changes, the output signal of the differential amplifier 14 that detects and records the crossing, that is, the track deviation signal, changes in amplitude in proportion to the change in the reflected light from the record carrier 7.

Incidentally, the reflected light from the recording medium 7 varies depending on the inner and outer circumference, recorded and unrecorded areas, and changes in the amount of light beam, and furthermore, the reflectance of the recording medium 7 varies greatly due to differences in materials, shapes, etc. There is also a recording phase, and the amplitude of the track deviation signal corresponding to the reflected light from the recording phase is not constant.

Therefore, in the above configuration, if the amplitude of the track deviation signal changes due to the above-mentioned factor 1 or the like, the margin of the amplitude with respect to the set level β for detecting the crossing of the track of the light beam will not be constant, and the search At times,
The number of tracks traversed by the light beam may be miscounted, leading to a deterioration in search accuracy.Also, when recording media with significantly different reflectances are used, it is necessary to change the set level by changing the level appropriately. necessitated adjustments or modifications to the equipment.

In view of the above problems, the present invention makes the amplitude of a signal for detecting a track traversed by a light beam approximately constant even if the amount of reflected light (or transmitted light) from a record carrier changes.
It is an object of the present invention to provide a device which greatly reduces erroneous counting of the number of traversed tracks and allows accurate retrieval regardless of the record carrier.

Means for Solving the Problems The present invention provides a converging means for converging and irradiating a light beam onto a recorded signal track or a recording medium having a track for recording a signal, and a converging means for converging and irradiating a light beam onto a recording medium having a recorded signal track or a track for recording a signal, , a trunk deviation detection means for detecting a positional deviation of a track on a record carrier from transmitted light transmitted through the record carrier, and a moving means for moving a light beam on the record carrier in a direction substantially perpendicular to the track direction. a tracking control means for driving the moving means in accordance with a signal from the track deviation detection means to control the light beam on the record carrier so that the light beam always scans the track; a dividing means for outputting a signal corresponding to a value divided by a signal corresponding to the amount of light irradiated on the deviation detecting means; and a dividing means for outputting a signal corresponding to a value divided by a signal corresponding to the amount of light irradiated on the deviation detecting means, and a dividing means for processing the signal of the side leg means so that the light beam on the record carrier is traversed. a moving amount detecting means for detecting the number of tracks;
1.

This is an information track retrieval device comprising an information track search device and a retrieval means for retrieving a desired track.

According to the present invention, with the above-described configuration, even if the signal of the track deviation detection means changes due to a change in the reflectance (or transmittance) of the record carrier or a change in the light intensity of the light beam, the light beam on the record carrier does not cross. In order to maintain a constant signal for detecting the number of tracks detected, the signal from the track deviation detection means is divided by a signal corresponding to the optical meter irradiated onto the track deviation detection means.

Therefore, since the signal after the above-mentioned division always has a constant magnitude, the circuit for this processing, that is, the structure of the movement amount detecting means for detecting the number of tracks crossed by the light beam on the record carrier, is extremely simple. A device that can perform accurate and stable searches can be provided.

Embodiment FIG. 1 is a block diagram showing the configuration of the present invention. The same parts as in the conventional search device are given the same numbers, and their explanations will be omitted. Examples 14, . . . will be described below with reference to FIG.

The output signal of the differential amplifier 14 is sent to the divider 1 via a phase compensation circuit 16 for compensating the phase of the tracking control system.
9 is input. The divider 19 divides the input signal by the signal synthesized by the synthesis circuit 26, that is, the signal equivalent to the total amount of light detected by the photodetector 9. Therefore, the output of the divider 19 remains approximately constant even if the amount of reflected light from the record carrier 7 changes and the signal detected by the photodetector 9 changes.

The output signal of this divider 19 (hereinafter referred to as a track crossing signal) is input to a track crossing detection circuit 3°. The track crossing detection circuit 3o is composed of a comparator 31 and a pulse generation circuit 32. Similar to the conventional technology, the track crossing detection circuit 3o compares the signal with a certain level and determines the magnitude of the amplitude. HIGH
Outputs a signal of status or LOW status. This output signal is input to the pulse generation circuit 32, and the controller 7'
One pulse is output in response to the rise of the output signal of the regulator 31. The pulse signal output from the pulse generating circuit 32 is input to the counting i1 path 27, and is counted as the number of tracks crossed by the light beam 2.

FIG. 2 shows a timing chart of the output signal of the differential amplifier 14, the output of the output 1 divider 19 of the synthesis circuit 26, the output of the comparator 31, and the output of the pulse generator 32.

The track crossing detection portion will be explained in more detail with reference to FIG.

The output (al) of the differential amplifier 14 changes in amplitude in proportion to the change in the amount of reflected light from the recording medium 7. Therefore,
The output (C) of the divider 19, which is obtained by dividing the output (a) of the differential amplifier 14 by the output (b) of the combining circuit 26 corresponding to the amount of reflected light, always has a substantially constant magnitude. Therefore, when searching, the output of the divider 19 (C1) across the track always has an approximately constant margin with respect to the reference level compared by the comparator 31, and the output of the comparator 31 and the output of the pulse generator 32 The output h2 is stable and accurate with respect to the crossing of the track of the optical beam 2.In comparison, when the output of the differential amplifier 14 is directly compared with the set level 11 as in a conventional search device, the signal is The margin for the amplitude setting level β1 changes, and the pulse generator 32 is unable to generate accurate pulses when the track is crossed.

If this embodiment is used as described below, even if the reflected light fi, (or the amount of transmitted light) of the recording medium changes, the thickness of the track crossing signal that detects that the light beam has crossed the track can be changed. is always approximately constant, making it possible to count the number of traversed tracks very accurately during a search. You can perform accurate and stable searches without making any modifications or adjustments.

Effects of the Invention - As explained, according to the present invention, even if the amount of light reflected from the recording medium changes and the magnitude of the signal from the rank shift detection means changes, the number of tracks crossed by the light beam can be determined. The magnitude of the signals to be detected (track lateral 17, 7 cut signals) is always approximately constant, making it possible to greatly reduce erroneous counting of the number of tracks traversed during retrieval. This makes it possible to perform accurate and stable searches regardless of the light intensity of the light beam, providing a highly reliable and practical device.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, FIG. 2 is a timing chart of signals related to the trunk crossing detection circuit in the same embodiment, and FIG. 3 is a block diagram showing the configuration of a conventional search device. , FIG. 4 is an operation flowchart of the information processing control device in FIG. 3, and FIG. 5 is a diagram showing the relationship between the position of the light beam and the tracking error signal in the conventional search device. 1...Semiconductor laser, 2...Light beam, 3...Coupling lens, 4...
Beam splitter, 5...Reflector, 6...
... Converging lens, 7... Recording phase body, 8...
...Motor, 9...Photodetector, 10...
・Tracking element, 11...Speed sensor, 1
2...187, -1 Transfer table, 13... Linear motor, 14...
...Differential amplifier, 16...Switch, 16...
... Phase compensation circuit, '18... Drive circuit,
19...Divider, 20...Phase compensation circuit, 21...Composition circuit, 22...Drive circuit, 23...Switch, 24... Information processing control device, 26... Address input device, 26.
...Synthesizing circuit, 27...Counting circuit, 28
... Signal generation circuit, 30 ... Trunk crossing detection circuit, 31 ... Comparator, 32
...Pulse generation circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 No Ωless light 432 Deba Figure 3 Figure 4

Claims (1)

[Claims] A converging means for converging and irradiating a light beam onto a record carrier having a recorded signal track or a track for recording the signal; track deviation detection means for detecting positional deviation of the record carrier; moving means for moving the light beam on the record carrier in a direction substantially perpendicular to the track direction; a tracking control means for controlling the light beam on the record carrier so that it always scans the track; and a tracking control means for controlling the light beam on the record carrier so that the light beam always scans the track; and a tracking control means for controlling the light beam on the record carrier to always scan the track; a dividing means for outputting a signal corresponding to the divided value; a movement amount detecting means for detecting the number of tracks crossed by the light beam on the record carrier based on the signal of the dividing means; 1. An information track search device comprising: a search means that is inoperative and searches for a desired track.