JPS5857637A - Searching system of optical disk - Google Patents

Abstract

PURPOSE:To realize the searching of an optical disk at a high speed, by shifting a pickup nearly in the radius direction of an optical disk at a speed higher than the ordinary reproduction and at the same time deflecting the light beam in the direction opposite to the shifting direction of the pickup. CONSTITUTION:When a search instruction and a search address are fed, the control signal is applied to motor control circuits 3 and 8 from a CPU9. Then a disk 1 is driven by a motor 2 so as to always secure a constant relative speed to a pickup 4, and the pickup 4 is shifted by a motor 7 to the radius direction of the disk 1 at a speed higher than the speed of a play mode. The signal given from a sawtooth wave generating circuit 14 is added to the signal from a tracking error detecting circuit 12 and then fed to a tracking driving circuit 13. Then the laser light is deflected to the pickup 4. Both the revolving direction of the motor 7 and the polarity of the sawtooth wave signal produced from the circuit 14 are controlled so as to decrease the difference between the read-out address and the search address. Thus the pickup 4 is moved to a desired position.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to an optical disk device, and particularly to a search method thereof.

(Prior Art) In playback with an optical disk device, tracking is performed so that the laser beam from the pickup always follows the information track on the disk.

Ichiriki recorded the audio signal I) A D (])
In the case of digital Audio Disk),
By recording the address on the disk, it is possible to accurately search for the beginning of a song. This address uses the song number and the elapsed time during the song.

When performing such a search, K simply specifies the address that the user wishes to search. In the player, the feed by the pickup moving mechanism is fast-forwarded so that the target address position is quickly reached. In this case, in order to know the positional relationship between the current location of the pickup and the target address,
Sometimes you need to read an address on disk.

To read the address, you have to turn on the racking servo (mentioned above), but the tracking servo can perform phase tracking between the track to be tracked and the pickup, but if the relative speed is large, tracking will not be possible. It becomes impossible to read the address accurately. Therefore, in the past, it was not possible to perform a high-speed search.

For this reason, other methods, such as those described in Japanese Patent Application Laid-open No. 55-62536, have been proposed to form a non-signal recording track ring between songs, but There is a problem in that the recording density of the disc is reduced.

(Object of the Invention) The present invention was made in view of the above circumstances, and an object of the present invention is to provide an optical disc search method that allows high-speed searching without reducing recording density.

(Summary of the Invention) The present invention provides an optical disc device that, when searching for a desired address, moves the pickup in the approximate radial direction of the disc at a higher speed than during normal playback, and also irradiates the disc. The optical beam is periodically deflected in a direction opposite to the direction of movement of the pickup.

As a result, the relative velocity (radial direction) between the light beam and the information track is reduced to such an extent that the tracking servo is possible, and the address on the information track can be reliably read at each periodic interval, and the search time is can be made shorter.

(Embodiment) FIG. 1 shows a block diagram of an I) AD player as an embodiment of the present invention. In the figure, 1 is a disk having a spiral information track, and the information track has P
In addition to the audio signal converted into a CM signal, the song number and the elapsed time in the song are added as addresses. 2 is a motor that rotates disk 1, 3 is motor 2
4 is a pickup that irradiates the disk 1 with a laser beam and detects the reflected light;
5 is a digital demodulation circuit that demodulates the signal of the information track read by the pickup 4, and 6 is a PC that processes the signal obtained from the demodulation circuit 5 and converts it into an audio signal.
M processing circuit; 7 is a motor for moving the pickup 4 in a substantially radial direction of the disk I; 8 is a motor control circuit that controls the motor 7; 9 is a system controller (CPU) that controls the motor control circuits 3, 8, etc. It is.

A key switch (not shown) is connected to the CPU 9. For example, when a play command (playback) is input, the CPU 9
9 outputs a control signal to the motor control units 3 and 8, and the motor 2
, 7. This causes disk 1 to rotate,
Pickup 4 moves.

At this time, the laser beam of the pickup 4 is generally controlled so as to follow the information track on the disk at a constant speed. The pickup 4 converts the reflected light from the information track into an electrical signal and outputs it to the digital demodulation circuit 5. The digital demodulation circuit 5 converts this electrical signal into binary coding and digitally demodulates it. This demodulated signal undergoes error correction, correction, etc. in the PCM processing circuit 6, and is further converted into an analog signal. This analog signal is guided to a speaker or the like (not shown).

On the other hand, in FIG. 1, a focus error detection circuit IQ focal length drive circuit 11 is provided to adjust the focus of the laser beam of the pickup 4.

A tracking error detection circuit 12 and a tracking/puffer drive circuit 13 are provided to perform tracking servo of the laser beam of the pickup 4. This tracking drive circuit 13 includes a sawtooth wave generation circuit J4.
It is also possible to add the output signal of

Figure 81!2 shows the configuration of the pickup 4. The laser beam emitted from the laser diode 40 is converted into parallel light by a collimation lens 41, and then passed through a deflection prism 4.
2. - Irradiates onto the disk 1 via the plate 431 reflecting mirror 44 and objective lens 45.

The reflected light from the disk 1 passes through the objective lens 459 and the reflecting mirror 44.
．． /[43 to reach the deflection prism 42. This reflected light passes through one plate 43 twice, so the position is 18d'
After being reflected by the deflection prism 42, the photo objective lens 45 is moved through the cylindrical lens 46. Although not shown, it is attached to a movable body made of, for example, a magnetic material, and the coils 48 and 49 are connected to each other. Wrapped perpendicularly. When a current flows through the coil 48, the distance between the objective lens 45 and the disk 1 changes, which is used for focus control.

On the other hand, when a current flows through the coil 49, the objective lens 45 moves in the radial direction of the disk 10, so that the position of the beam converged on the disk also shifts, which is used for tracking control.

The photodiode 47 that receives reflected light is divided into four parts as shown in FIG. By passing the light through the cylindrical lens 46, there are two focal points, and the photodiode 4 is placed between these two focal points. At this time,
If the laser beam is accurately focused on the disk 1, the beam on the photodiode 4 will be circular as shown in FIG. 3C, but if the distance between the disk 1 and the objective lens 45 changes, the fish collection position Because of the deviation, it changes as shown in a or b in Fig. 3. Therefore, from the 4-divided signal output,
When the calculation (2) is performed, when the focus is correct, the signal becomes 0, and when the focus is shifted, a signal with a corresponding magnitude and polarity is obtained. Focus error detection circuit 1 in Fig. 1
0 obtains such an error signal and supplies it to the focus drive circuit 11. And focus drive circuit 1
The output of 1 is supplied to the coil 48 as a focus drive signal).

On the other hand, referring to figure W14, assuming that the beam position of the photodiode 47 during correct tracking is the position shown by r, when the tracking deviates, the position f K changes as shown by p or q according to the deviation. Therefore, the tracking error detection circuit 12 supplies a signal of ■+■−■−■ from the four-divided signal output as an error signal to the dragging drive circuit 13, and the tracking control is performed by passing the output tracking drive signal to the coil 49. It is done. Note that this error signal is sent to the motor control circuit 8.
It is also supplied to the pickup 4 so that the entire pickup 4 can be moved slowly.

Referring again to FIG. 1, the search operation of this embodiment will be explained. When a search command and a search address are input using the illustrated key switch, the CPU 9 provides control signals to the motor control circuits 3 and 8. In this case, the motor control circuit 3 receives the same control signal as in the play state described above.
The disk 1 is driven by the motor 2 at a rotational speed such that the relative speed (in the track direction) with the pickup 4 is always constant. On the other hand, a control signal instructing high-speed feeding is given to the motor control circuit 8, and the pickup 4 is moved in the radial direction of the disc 1 by the motor 7 at a higher speed than in the above-described play state.

Incidentally, among the outputs of the demodulation circuit 5, the address signal is separated and supplied to the CPU 9.
9 can know the current position of the pickup 4 from this address. When a search command is issued, the current position of the pickup 4 is compared with the search address, and the direction of movement of the pickup 4 on the disk 1 can thereby be determined.

The CPU 9 also drives the sawtooth wave generation circuit 14 in response to the search command. The sawtooth wave signal generated by the circuit 14 (Fig. 5 (
a)) is added to the tracking error signal and supplied to the tracking drive circuit 13. However, coil 4 in Figure 2
A sawtooth wave current flows through the laser beam 9, and the laser beam is deflected in the radial direction of the disk 1 in a sawtooth waveform. By setting the laser beam deflection direction in this case to be opposite to the high-speed movement direction of the entire pickup 4, the relative speed (radial direction) between the laser beam and the disk 1 decreases during the deflection period.
Tracking becomes possible. Looking at this on the disk 1, when the pickup is moving at high speed, as shown in FIG. You can peer into the information trunk.

Therefore, even during a high-speed search, the CP IJ 9 constantly compares the readout address and the search address, and adjusts the rotational direction of the motor 7 and the sawtooth wave generation circuit 14 to reduce the difference between them. It can reach up to the sawtooth position. When the position of the pickup 4 approaches the target position sufficiently, the CPU 9 stops driving the circuit 14, applies a tracking error signal to the motor control circuit 8, and sets the motor control circuit 8 to a play state. Alternatively, the input can be temporarily stopped if necessary.

(Other Embodiments) FIG. 6 shows another embodiment of the present invention. The configuration shown in the figure differs from the embodiment shown in FIG. 1 in that a kick pulse generator 15 is provided.

As shown in FIG. 7(a) by the search command, after driving the sawtooth wave generating circuit 14 and starting a high-speed search, when the read address reaches the nearest stop (1) of the search address, the CPU
9 stops driving the circuit 14.

Then, the high-speed movement of the pickup 4 is also stopped, and the kick pulse generator 15 is driven instead. This kick pulse has a waveform as shown in FIG. 7(b), is added to the tracking error signal, and is supplied to the tracking drive circuit 13. This kick nozzle causes the laser beam to skip several information tracks, allowing the pickup to smoothly move away from the target position.

This is effective when the inertia of the pickup is large.

As described above, according to the present invention, even if the movement of the pickup is increased, stable tracking control can be performed when reading an address, so that accurate signal reading can be performed and the search speed can be greatly improved.

Note that if the high-speed movement speed of the pickup is not constant, the slope of the sawtooth wave may be changed depending on the speed.
The period may also be changed depending on the difference between the current position and the search address, for example. In the generation of such a sawtooth wave signal, if the address signal can already be read in the middle of the slope signal, the next new slope signal may be generated at that point. This reduces read problems and enables more detailed address reproduction. In other words, the term "periodic deflection" as used herein includes cycles of variable length, and of course the number of cycles (the number of deflections) can be changed depending on the search address.
is variable.

[Brief explanation of drawings]

FIG. 1 is a diagram showing one embodiment of the present invention, and FIGS. 2 to 5 are diagrams for explaining one embodiment of the present invention. FIG. 6 is a diagram showing another embodiment of the invention, and FIG. 7 is a diagram for explaining another embodiment of the invention. 1 - Disk 4 - Pickup 9 - CPU 12... Tracking error detection circuit 13... Tracking drive circuit 14... Sawtooth wave generation circuit 15... Kick pulse generation circuit

Claims (2)

[Claims] (1) An optical disc device includes a disc on which information including addresses is recorded on substantially concentric information tracks, and a pickup that reads out the information recorded on the information tracks with a light beam. When searching for a desired address, the optical pickup is moved at high speed substantially in the radial direction of the disk, and the optical beam is periodically deflected in a direction opposite to the moving direction of the pickup. Disk search method. (2) a disk on which information including addresses is recorded on semi-concentric information tracks; a pickup that reads out the information recorded on the information tracks with a light beam;
a tracking circuit for controlling tracking so that the light beam follows the information track; a means for inputting a search address for information to be reproduced; and responsive to the means, the pickup is moved at high speed approximately in the radial direction of the disk. a first generator that generates a sawtooth wave signal that periodically deflects the original beam in a direction opposite to the direction of movement of the pickup to the tracking circuit during a period of high-speed movement of the pickup; During the period of high-speed movement of the pickup, the previous search address is compared with the address information read from the pickup, and when the read address of the big amplifier is near the search address, the high-speed movement of the pickup is stopped. (7
and a second generator that generates a kick pulse for kicking the optical beam to the tracking circuit for a period until the read address reaches the search address.