JPH0685220B2 - Information track search device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information track inspection apparatus in an optical recording / reproducing apparatus.

2. Description of the Related Art As a conventional information track search device, for example, Japanese Patent Laid-Open
There is one such as that shown in 59-165277.

This will be described below with reference to FIG.

A light beam 3 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 5, and is converged on a disk-shaped record carrier 7 by a converging lens 6. The record carrier 7 is attached to the rotating shaft of a motor 8 and is rotating at a predetermined rotation speed.
The record carrier 7 has concentric or spiral concave and convex grooves (hereinafter referred to as tracks) on a substrate, and is composed of a recording material layer and a protective layer provided thereon, and each track has Sequential address signals are provided in advance from the inner circumference to the outer circumference. Light beam 2 reflected from record carrier 7
The reflected light of (1) again passes through the converging lens 6, is reflected by the reflected light 5 and the beam splitter 4, and is applied to the photodetector 9 tatami having a two-divided structure. The converging lens 6 is attached to the tracking element 10 and
Is configured so that the converging lens 6 can be moved in the radial direction of the record carrier 7, that is, in the direction substantially perpendicular to the track direction on the record carrier 7. The moving part of the light source 1, the coupling lens 3, the beam splitter 4, the reflecting mirror 5, the photodetector 9, the tracking element 10 and the speed detector 11 is a transfer table 12.
And is configured to be moved integrally by the linear motor 13 in the radial direction of the record carrier 7. 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.

The 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. The respective signals of the photodetector 9 are input to the differential amplifier 14, and the differential amplifier 14 outputs the difference signal of 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 of the differential amplifier 14 is the record carrier 7.
It is known that a signal representing the positional relationship between the upper light beam 2 and the track, that is, a track shift signal, is known and will not be described in detail. The signal of the differential amplifier 14 is a switch 15, a phase compensation circuit 16 for compensating the phase of the tracking control system,
And is transmitted to the tracking element 10 via a drive circuit 18 for driving the tracking element 10.

The tracking element 10 moves the converging lens 6 according to the signal from the differential amplifier 14 and is controlled so that the light beam 2 on the record carrier 7 is positioned on the track.

The movable range of the tracking element 10 is about 500 μm, and if the transfer table 12 moves largely, the tracking control is lost. In order to prevent this, the tracking element 10 is moved around the natural state, that is, the drive circuit 18
Linear motor 13 so that the signal of
To control the movement of the transfer table 12. To explain this transfer control, the signal of the differential amplifier 14 is a switch.
15, phase compensation circuit 20 for compensating the phase of the transfer control system,
Drive circuit for driving the combination circuit 21 and the linear motor 13
Via 22, the linear motor 13 moves the transfer table 12 so that the tracking element 10 moves around the natural state. The switch 15 is for deactivating the tracking control and the transfer control, and the synthesizing circuit 21 is the speed detector 1
1, a circuit for synthesizing respective signals of the phase compensation circuit 20 and a switch 23 described in detail later. The switch 23 is open in the state where the tracking control is operating.

In order to make the linear motor drive control more stable, the signal from the speed detector 11 is added to the linear motor 13 to perform speed control.

Recording and reproduction of signals will be described. When a signal is recorded on the track on the record carrier 7, the light beam 2 generated from the light source 1 is strongly modulated according to the signal to be recorded while the tracking control and the transfer control are operated. The recording material irradiated with the strong light beam 2 changes in state or shape, and a signal is recorded on the track on the record carrier 7. When the signal recorded on the track on the record carrier 7 is reproduced, the light beam 2 generated from the light source 1 is made to have a weak constant light amount while the tracking control and the transfer control are operated, and reflected from the track. The light is received by the photodetector 9, and a composite signal of the respective signals of the photodetector 9 is obtained.

In the optical recording / reproducing apparatus, focusing control is performed so that the beam diameter of the light beam 2 irradiated on the record carrier 7 is always constant, but since it is not directly related to the present invention, it will be described in detail. Avoid the

The search system is composed of an information processing control device 24 including a microcomputer. When the address A ₀ of the desired track is input to the address input device 25, the information processing control device 24 combines the address A ₁ of the track where the light beam 2 is located with the respective signals of the photodetector 9. Read from the signal of the circuit 26 and calculate (A ₁ −A ₀ ). | A ₁ −A ₀ | ≧ N
_{If 0} (| A ₁ −A ₀ | represents the absolute value of (A ₁ −A ₀ ), and N ₀ is a positive integer), the information processing control device 24 determines that the value of | A ₁ −A ₀ | Is preset in the counting circuit 27 and a movement direction signal is sent to the signal generating circuit 28. The moving direction signal is a signal for instructing whether to move the transfer table 12 from the outer circumference of the record carrier 7 to the inner circumference direction or from the inner circumference to the outer circumference direction.

After that, the information processing control device 24 sends a signal to the switch 15 to open the switch 15 to disable the tracking control and the transfer control, and sends a signal to the switch 23 to short-circuit the switch 23 so that the signal from the signal generation circuit 28 is output. The synthesis circuit 21
To be transmitted to. The signal generating circuit 28 outputs a signal corresponding to the count output of the counting circuit 27 and a moving direction signal from the information processing control device 24, and the linear motor 13 outputs the signal generating circuit 28.
The transfer table 12 is moved in the direction in which the desired track exists in response to the signal. The signal of the differential amplifier 14 is input to the track crossing detection circuit 29, and the track crossing detection circuit 29 outputs a pulse signal indicating that the light beam 2 on the record carrier 7 has crossed the track. The counting circuit 27 counts the signals of the track crossing detection circuit 29, detects that the light beam 2 has arrived on the | A ₁ −A ₀ | th track, 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 sends a signal to the switch 15 to short-circuit the switch 15 to operate tracking control and transfer control.

After that, the information processing control device 24 reads the address A ₁ of the track where the light beam 2 on the record carrier 7 is located.

(Hereinafter, this search will be referred to as a rough search.) If A ₀ = A ₁ , the search ends, but if | A ₁ −A ₀ | ≧ N ₀ , the above-described rough search is performed again. If | A ₁ −A ₀ | <N ₀ , the information processing control device 24 opens the switch 15 and sends a signal to the drive circuit 18 to drive the tracking element 10 to restart the switch 15
To short-circuit one track to perform interlaced scanning (hereinafter, this scanning is referred to as jumping),
The jumping | A ₁ -A ₀ | reading address A ₁ of the track which the light beam 2 is located after repeating times (. Hereinafter referred to as the search and tight inspection) Kensaku If A ₀ = A ₁ is At the end, if A ₀ ≠ A ₁ (A ₀ ≠ A ₁ indicates that A ₀ and A ₁ are not equal), the above-described rough search and fine search are repeated to search for a desired track. FIG. 4 shows an operation flowchart of the information processing control device 24 at the time of searching as described above.

As described above, at the time of search, the number of tracks traversed by the light beam on the record carrier is counted and the movement amount thereof is measured. A method of detecting the track crossing will be described.

As described above, the signal of the differential amplifier 14 is a signal indicating the positional relationship between the light beam 2 and the track, that is, a track shift signal. As shown in FIG. 5, the light beam 2 is adjacent to any track 1. When moving to the track 2, the differential amplifier 14 outputs a sine wave signal of that period. Therefore, the track deviation signal is compared with a certain set level l, and it is detected that the signal of the differential amplifier 14 exceeds that level, thereby detecting that the light beam has crossed the track. This is counted and the amount of movement of the light beam is measured.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention In the above-mentioned conventional scheme, the reflected light from the record carrier 7 changes in the output signal of the differential amplifier 14 which detects that the light beam has crossed the track, that is, the track shift signal. Then, the amplitude changes in proportion to it.

Incidentally, the reflected light from the record carrier 7 changes depending on the inner circumference and the outer circumference, the recorded portion and the unrecorded portion, the change in the light amount of the light beam, and the like, and further the reflectance greatly differs due to the difference in the material and the shape. Therefore, the amplitude of the track shift signal corresponding to the reflected light from the record carrier is not constant.

Therefore, in the above-mentioned configuration, when the amplitude of the track deviation signal changes due to the above-mentioned factors, the margin of the amplitude with respect to the set level 1 for detecting the crossing of the track of the light beam is not constant, and at the time of search. At
The number of tracks traversed by the light beam may be erroneously counted, which deteriorates the search accuracy.

Further, when using a record carrier having greatly different reflectance, the set level must be changed to an appropriate level, which requires adjustment or modification of the device.

In view of the above problems, the present invention makes the amplitude of a signal for detecting a track crossed by a light beam substantially 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 capable of accurately searching regardless of the record carrier, by reducing the false count of the number of tracks traversed.

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 record carrier having a track for recording a signal, and reflected light from the record carrier, Track deviation detecting means for detecting a positional deviation of a track on the record carrier by transmitted light transmitted through the record carrier; moving means for moving the light beam on the record carrier in a direction substantially perpendicular to the track direction; Tracking control means for driving the moving means according to the signal of the track deviation detecting means and controlling so that the light beam on the record carrier always scans the track, and the signal of the track deviation detecting means for detecting the track deviation. Dividing means for outputting a signal corresponding to a value divided by a signal corresponding to the amount of light applied to the means, and processing the signal of the dividing means The information track searching device comprises a moving amount detecting means for detecting the number of tracks crossed by the light beam on the record carrier and a searching means for inactivating the tracking control and inspecting a desired track.

Operation The present invention has the above-mentioned configuration, in which the light beam on the record carrier is changed even if the signal of the track deviation detecting means changes due to the reflectance (or the change in the transmittance) of the record carrier or the change in the light amount of the light beam. In order to make the signal for detecting the number of crossed tracks constant, the signal of the track deviation detecting means is divided by the signal according to the amount of light irradiated on the track deviation detecting means.

Therefore, since the above-mentioned signal after the division is always a constant magnitude, the circuit for this processing, that is, the movement amount detecting means for detecting the number of tracks traversed by the light beam on the record carrier becomes extremely simple, accurate and stable. It is possible to provide a device capable of various inspections.

Embodiment FIG. 1 is a block diagram showing the configuration of the present invention. The same parts as those of the conventional donation device are designated by the same reference numerals, and the description thereof will be omitted. An embodiment will be described below with reference to FIG.

The output signal of the differential amplifier 14 is input to the divider 19 via the phase compensation circuit 16 for compensating the phase of the tracking control system. The divider 19 compares the input signal with the combining circuit 26.
It is divided by the signal combined in step 1, that is, the signal corresponding to all the light amounts detected by the photodetector 9. Therefore, the divider 19
The output of the photodetector 9 changes when the amount of reflected light from the record carrier 7 changes.
Even if the signal detected by is changed, it becomes almost constant.

The output signal of the divider 19 (hereinafter referred to as the track crossing signal) is input to the track crossing detection circuit 30. The track crossing detection circuit 30 is composed of a comparator 31 and a pulse generation circuit 32.The track crossing detection circuit compares the signal with a certain level and determines the magnitude of its amplitude as in the conventional technique. HIGH state or
Outputs the LOW signal. The output signal is input to the pulse generation circuit 32, and one pulse is output according to the rising edge of the output signal of the comparator 31. The pulse signal output from the pulse generation circuit 32 is input to the counting circuit 27 and is counted as the number of tracks that the light beam 2 has crossed.

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

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

The output (a) of the differential amplifier 14 changes in amplitude in proportion to the change in the amount of reflected light from the record carrier 7. Therefore, the output (c) of the divider 19 obtained by dividing the output (a) of the differential amplifier 14 by the output (b) of the combining circuit 26 corresponding to the reflected light amount.
Always has a substantially constant size. Therefore, when searching, the output of the divider 19 when crossing the track (c)
Has a substantially 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 are stable and accurate with respect to the traverse of the track of the light beam 2. To be done. On the other hand, like the conventional device, when the output of the differential amplifier 14 is directly compared with the set level l1, the margin of the amplitude of the signal with respect to the set level l1 changes, and the pulse generator 32 does not cross the track. , Can not generate accurate pulse.

As described above, according to this embodiment, even if the amount of reflected light (or the amount of transmitted light) of the record carrier changes, the magnitude of the track crossing signal for detecting that the light beam has crossed the track is always approximately constant. Therefore, the number of tracks crossed at the time of search can be made very accurate, and even if a record carrier having a large reflectance is used in this device, no modification or adjustment is required in the contribution. You can make accurate and stable searches.

As described above, according to the present invention, even if the amount of reflected light from the record carrier changes and the magnitude of the signal of the track deviation detecting means changes, a signal for detecting the number of tracks crossed by the light beam. The magnitude of the (track crossing signal) is almost constant at all times, and the false count of the number of tracks crossed at the time of search can be greatly reduced, and it is related to the reflectance (or transmittance) of the record carrier and the light amount of the light beam. Therefore, accurate and stable search can be performed, and a highly reliable and practical device can be provided.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention, FIG. 2 is a timing chart of signals relating to a track crossing detection circuit in the same embodiment, and FIG. 3 is a block diagram showing a configuration of a conventional search device. 4, FIG. 4 is an operation flowchart of the information processing control device in FIG. 3, and FIG. 5 is a relationship diagram 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 ... Record carrier, 8 ... Motor, 9
...... Photo detector, 10 ...... Tracking element, 11 ...... Speed sensor, 12 ...... Transfer base, 13 ...... Linear motor, 14 ...... Differential amplifier, 15 ...... Switch, 16 ...... Phase compensation circuit, 18 ......
Drive circuit, 19 ... Divider, 20 ... Phase compensation circuit, 21 ...
Compositing circuit, 22 ... Driving circuit, 23 ... Switch, 24 ... Information processing control device, 25 ... Address input device, 26 ... Combining circuit, 27 ... Counting circuit, 28 ... Signal generating circuit, 30 ... … Track crossing detection circuit, 31 …… Comparator, 32 …… Pulse generation circuit.

Claims (1)

[Claims] 1. A positional deviation between a track on a record carrier and a light beam is caused by a converging means for converging a light beam on a record carrier having a track, and reflected light from the record carrier or transmitted light transmitted through the record carrier. Track deviation detecting means for detecting, moving means for moving the light beam on the record carrier in a direction substantially perpendicular to the track direction, and driving the moving means in response to a signal from the track deviation detecting means for recording Tracking control means for controlling so that the light beam on the carrier always scans on the track, and division for dividing the signal of the track deviation detecting means by a signal according to the amount of light irradiated on the track deviation detecting means. Means, 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, and the tracking control means. In the work, the movement amount detecting means based on the signal to find the desired track search means and search device information tracks characterized by being configured with.