JPH0349042A - Tracking signal measuring method in optical information recording and reproducing device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention [Industrial Application Field 1] The present invention provides an optical information recording/reproducing apparatus for recording, reproducing, or erasing information on an optical recording medium such as an optical disc or a shiny a-air disc. The present invention relates to a method of measuring a tracking signal of a medium.

[Prior Art] In optical information recording media, tracking signals have conventionally been measured in order to obtain characteristics of each medium before recording or reproducing.

To obtain this tracking signal, an optical recording medium is attached to an optical information recording/reproducing device and rotated.
This is done using a signal generated when a focused beam spot diagonally crosses a track of an optical recording medium according to the amount of eccentricity at that time.

[Problems to be Solved by the Invention] However, in the conventional example described above, the frequency of the tracking signal changes depending on the amount of eccentricity, so when the amount of eccentricity approaches 0, a signal may not be obtained. If is very large, the tracking signal will be at too high a frequency, which is an unstable method.

Another drawback is that it is not possible to attach a filter to remove noise at high frequencies.

For this reason, it has been extremely difficult to automatically and accurately measure tracking signals. This is not only a problem with measuring instruments for optical recording media, but also occurs during automatic tracking offset correction in an optical information recording/reproducing device that has an automatic tracking offset correction function.

This is also a problem when measuring tracking signals.

[Means and effects for solving the problems] The present invention, as a means for solving the above-mentioned problems, includes: irradiating an optical information recording medium with a light beam spot;
A method for measuring a tracking signal in an optical information recording/reproducing device that records and/or reproduces information.

reciprocating the light beam spot or the optical information recording medium at a predetermined period so that the light beam spot relatively crosses the track of the optical information recording medium;
The present invention provides a method for measuring a tracking signal in an optical information recording/reproducing apparatus, characterized in that the tracking signal is measured using the track crossing signal obtained thereby.

According to the present invention, the reproduction light beam spot is reciprocated a certain amount with respect to the track without rotating the recording medium, or the reproducing light beam spot is reciprocated a certain amount so that the recording medium is in the same positional relationship. By causing the reproduction light beam spot to cross the track, it is possible to obtain a stable tracking signal with a constant frequency.

[Example] (Example 1) Hereinafter, an example of the present invention will be specifically described with reference to the drawings.

FIG. 1 is a horizontal cross-sectional view of the optical information recording/reproducing apparatus of the present invention. In the apparatus of this embodiment, information is recorded by irradiating the optical recording medium l with a light beam 14 from the optical head 3. , playback is performed.

In this embodiment, the optical recording medium 1 is reciprocated along with the motor 7 in accordance with the oscillation frequency of the oscillator 6 as shown by the arrow A by the piezo vibrator 4.

By focusing the beam spot, the beam spot can be made to cross the track by a certain amount. Therefore, a tracking signal having a constant frequency and synchronized with the signal from the oscillator 6 can be obtained from the signal from the optical recording medium l obtained by this beam spot.

By adjusting the oscillation frequency of the oscillator 6, a tracking signal with a frequency most suitable for automatic measurement can be set, and measurement with good reproducibility becomes possible.

(Example 2) FIG. 2 is a diagram showing a second example of the method of the present invention. In the figure, 3 is an optical head, 2 is an objective lens, and the optical head 3 is attached to a guide rail 12. The linear motor 13 moves along the surface of the recording medium.

In this example, the recording medium is not moved as in Example 1, but the optical head 3 is provided as a feeding mechanism, or the near motor 13 is used to make it reciprocate as shown by arrow C, so that the light beam periodically traces the track. Make it cross.

FIG. 3 is a block diagram of the circuit of the optical head section of this embodiment. A signal from the oscillator 6 is input to the feed drive circuit IO, thereby driving the linear motor 13 back and forth.

In this example, since the linear motor provided as the feed mechanism is used, no additional mechanical parts are required.
There is a theory that it can be implemented only by changing the electrical circuit.

(Embodiment 3) In this embodiment, only the objective lens 2 shown in FIG. 2 is moved back and forth so that the light beam periodically crosses the track. In this case, as shown in FIG. 4, by inputting a signal from the oscillator 6 to the objective lens tracking drive circuit 1, an objective lens drive means (not shown) is driven, and the objective lens 2 is caused to reciprocate. in this way,
Since the weight 1 of the moving part is the smallest, it has the advantage of being able to move at high speed.

[Effects of the Invention] As explained above, by using the method of the present invention, it is possible to generate a stable tracking signal at a preset constant frequency, without depending on the amount of eccentricity due to rotation of the recording medium, as in the conventional method. Good reproduction (obtained).

Also, since the high frequency No. 19 does not occur, a noise filter can be installed.

Furthermore, in the conventional method, what could only be measured as a tracking signal for a -round, but with the present invention, even a very narrow part of the tracking signal can be measured by one stop. However, even objects that cannot be rotated can be measured.

It is also an innovative measurement method because it does not rotate, so there is no effect of surface runout.

Figure 3

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view and a circuit block diagram of an optical information recording/reproducing apparatus embodying the present invention. FIG. 2 is a plan view for explaining the optical head of Example 2.3. FIG. 3 is a block diagram of the circuit of the optical head section of the second embodiment. FIG. 4 is a block diagram of the circuit of the optical head section of the third embodiment. Figure 4/1 1 is an optical recording medium, 2 is an objective lens, 3 is an optical head, 4 is a piezo vibrator, 5 is a piezo drive unit, 6
1 is an oscillator, 7 is a motor, 8 is a turntable, 9 is a clamp, 10 is a feed drive circuit, 1 is an objective lens tracking drive circuit, 12 is a guide rail, and 13 is a near motor.

Claims (3)

[Claims] (1) A method for measuring a tracking signal in an optical information recording/reproducing apparatus that records and/or reproduces information by irradiating an optical information recording medium with a light beam spot, wherein the light beam spot is the optical information recording medium. reciprocating the light beam spot or the optical information recording medium at a predetermined period so as to relatively cross the tracks of the recording medium;
A method for measuring a tracking signal in an optical information recording/reproducing device, characterized in that a tracking signal is measured using a track crossing signal obtained thereby. (2) The optical information recording and reproducing device includes a periodic signal oscillation means for generating a periodic signal of the reciprocating motion, and a reciprocating motion for reciprocating an optical head or an objective lens in the optical head using the signal from the oscillation means. The optical head or the objective lens is driven back and forth to cause the light beam spot to move back and forth, and a tracking signal is measured based on a track crossing signal of the light beam spot. A method for measuring a tracking signal in an optical information recording/reproducing apparatus according to claim 1. (3) The method for measuring a tracking signal in an optical information recording/reproducing apparatus according to claim 1, wherein the tracking signal is measured without rotating the optical information recording medium.