JPS6387623A - Servo system for optical disk recording and reproducing device - Google Patents

Abstract

PURPOSE:To stably operate focusing and tracking servo control by outputting a control signal based on a focusing error signal and a tracking error signal in the reproduced level of a modulated signal. CONSTITUTION:A focusing S/H circuit 12a holds the focusing error signal, which is sampled by the reproduced level, at the rise timing of a pulse signal when a pit is recorded on an optical disk 1, and it is held until recording of this pit is terminated. A focusing phase control part 12 outputs the control signal to a focusing driving part 9 on the basis of this focusing error signal. A tracking S/H circuit 13a is operated similarly to the focusing S/H circuit 12a. Thus, focusing and tracking servo control is stably performed at the time of recording operation. Further, detecting parts are easily adjusted and servo circuits are easily adjusted at the time of recording and reproducing.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] This invention relates to a servo system for a focus and tracking mechanism used in an optical disc recording/reproducing device.

[Conventional Examples] Conventionally, this type of optical disc recording and reproducing apparatus has been designed to accurately record information on an optical disc, or to accurately record information even if vibration or eccentricity occurs during rotation due to the chucking state of the optical disc. A servo circuit (shown in FIG. 3) is provided for controlling the focus and tracking of the objective lens of the optical head on the μ order so that the data can be reproduced with good readability.

In FIG. 3, a laser beam from a laser diode LD is spot irradiated onto an optical disc 1 via a collimator lens L1 and an objective lens L2, and is further reflected by this optical disc 1, and is further reflected by an objective lens L2) a beam splitter 2) a critical angle prism 3. is guided to the detection section 4 via. For example, as shown in FIG. 4, this detection unit 4 is a four-part detector consisting of four parts A, B, C, and D. The distribution is detected and the detected values a, b, c, and d are output to the focus error signal detection section 5 and the tracking error signal detection section 6, respectively. For example, the focus error signal detection unit 5 (a
+ c) - (b + d) is calculated, and a focus error signal is output to the focus phase control section 7 based on the value. Further, the tracking error signal detection section 6 may be configured such that, for example, (a
+b)-(c+d) is calculated, and a tracking error signal is output to the tracking phase control section 8 based on the value. The focus phase control unit 7 controls the actuator 9 of the objective lens L2 to maintain a constant distance between the optical disc 1 and the objective lens L2 based on the focus error signal.
Drive a (control in the direction perpendicular to the surface of the optical disc 1)
A control signal for this purpose is output to the focus drive unit 9.

On the other hand, the tracking phase control unit 8 controls the actuator 10a of the objective lens L2 so that the spot of the laser beam accurately follows the track (or guide in the case of a writable optical disc) of the optical disc 1 based on the tracking error signal. A control signal for (radial direction control of the optical disc 1) is output to the tracking drive section 10.

The above-described focus and tracking servo control allows the optical disc recording/reproducing apparatus to accurately record information and accurately read (reproduce) information.

[Problems to be Solved by the Invention] However, the focus and tracking servo control of the above-mentioned optical disc recording and reproducing apparatus has the following problems.

(1) Focus and tracking servo control during recording by the optical disc recording/reproducing device is unstable. This is because the output power of the laser diode changes drastically depending on the modulation signal from the modulator 11 during recording operation, and especially when recording the smallest pits continuously, the change is even more drastic. This is because the responses of the 4-division detector and the servo circuit become unstable.

(2) The detection part depends on the output power of the laser diode. Therefore, since the output power level of the laser diode differs during recording and playback, the detector needs to be adjusted to accurately detect the intensity distribution of the reflected light according to the level, and the detector is divided into four parts. For the detector of
- Considering cases with different levels, it was difficult to adjust to the same characteristics.

(3) During recording operation of the optical disc recording/playback device, playback =
4~ It was difficult to adjust the servo circuit during operation.

In other words, the gain of the servo circuit is switched between, for example, recording and reproducing operations, and difficult circuit adjustments must be made to enable focus and tracking servo control during this switching as well. There wasn't.

This invention was made in view of the above problems, and its purpose is to provide an optical disc recording in which focus and tracking servo circuits and reflected laser beam detectors can be easily adjusted, and focus and tracking servo control operate stably. The purpose of the present invention is to provide a servo system for a playback device.

[Means for Solving the Problems] In order to achieve the above object, the servo system of the optical disc recording and reproducing apparatus of the present invention uses a spot-shaped beam reflected by the optical disc through the objective lens of the optical head of the optical disc recording and reproducing apparatus. a detector that detects the intensity distribution of laser light; a focus error signal detection section that outputs a focus error signal based on the detection signal; and a tracking error detection signal section that outputs a tracking error signal; a focus phase control unit that outputs a control signal to control the distance between the optical disk and the objective lens; and a track king phase control unit that outputs a control signal to control the deviation between the track of the optical disk and the laser beam based on the tracking error signal. and a control unit;
In a servo circuit of an optical disc recording and reproducing apparatus that drives and controls an actuator of the objective lens using the control signal, during a recording operation of the optical disc recording and reproducing apparatus, the focus phase control section and the tracking phase control section control the laser beam. The control signal is output based on a focus error signal and a tracking error signal at the reproduction level of a modulation signal that modulates and drives.

[Function] During the recording operation of the optical disk recording/reproducing device, a control signal is obtained to control the actuator of the objective lens of the optical head based on the focus error signal and tracking error signal at the reproduction level of the modulation signal. . The focus error signal and tracking error signal are sampled at the reproduction level of the modulation signal and held at the recording timing of the modulation signal. Furthermore, the focus error signal and the tracking error signal are folded until information to be recorded on the optical disc, for example, one pit, is formed.

[Embodiments] Hereinafter, embodiments of the present invention will be described based on the drawings. FIG. 1 is a schematic block diagram of a servo mechanism for explaining the servo system of the optical disc recording/reproducing apparatus of the present invention. In addition, in the figure, the same parts as in Fig. 3 are given the same reference numerals.
Omit duplicate explanations.

In the figure, the focus phase control section 12 is provided with a focus S/H (sampling/hold) circuit 12a that samples the focus error signal and holds it at -, and similarly, the tracking phase control section 13 is provided with a focus S/H (sampling/hold) circuit 12a that samples the focus error signal and holds it at -. Tracking S/H (sampling/hold) that samples and holds at -
A circuit 13a is provided. A focus error signal from the focus error signal detection section 5 and a modulation signal (pulse signal) from the modulation section 11 are input to the focus S/8 circuit 12a. Further, a tracking error signal and a modulation signal are input to the focus S/I-1 circuit 12a to the tracking S/H circuit 13a.

Note that this modulation signal is a signal for recording information (pits) on the optical disc 1.

Next, the operation of the servo system of the optical disc recording/reproducing apparatus of the present invention will be explained.

First, when the optical disc recording/reproducing apparatus is in a recording operation, a modulation signal is output from the modulation section 11 to the drive section of the laser diode LD, and a pulse signal corresponding to the modulation signal shown in FIG. 2(a) is sent to the focus S. /8 circuit 1.2a and tracking S/H circuit 13a. Then, the laser diode LD outputs a laser beam according to the drive signal shown in FIG.
The spora 1 laser beam reflected by the laser beam (shown in FIG. 2(c)) is incident with an intensity varying according to the modulation signal. Then, based on the detection value of the detection unit 4, the focus error signal is output from the focus error signal detection unit S to the focus S/
The tracking error signal is output from the tracking error signal detection section 6 to the tracking S/H circuit 13a. As a result, the focus S/8 circuit 12a samples and holds the focus error signal at the reproduction level (shown in FIG. 2(a)).

Based on this focus error signal, a control signal for controlling the distance between the objective lens L2 and the optical disk 1 (driving the actuator 9a) is output to the focus drive unit 9. In addition, the tracking S/H circuit 13a also controls the playback level (
2(a)), and based on this tracking error signal, the tracks (guide grooves in the case of a writable optical disc) of the optical disc 1 are accurately followed (the actuator 10
The tracking drive unit 1 sends a control signal for driving
Output to 0.

Here, when pits are recorded on the optical disc 1, the focus S/8 circuit 12a holds the focus error signal sampled at the playback level at the falling timing of the pulse signal (pit recording) shown in FIG. death,
And it is held until the recording of that pit is completed (time t shown in FIG. 2).

Based on this focus error signal, the focus phase control section 12 outputs a control signal to the focus drive section 10. That is, when recording pits, the focus phase control section 12 outputs a control signal only based on the focus error signal at the reproduction level, without using the focus error signal at the recording level. Further, the tracking S/H circuit 13a operates in exactly the same way as the focus S/H circuit 12a. Therefore, the tracking S/H circuit 13a samples the tracking error signal at the reproduction level and holds it at the falling timing of the pulse signal shown in FIG. This hold is performed until, for example, the recording of pits is completed, as shown in FIG. As a result, the tracking phase control section 13 can control the 1-
A control signal is output to the tracking drive section 10 based on the racking error signal.

=11- As described above, in the servo system of the present invention, when the optical disc recording/reproducing apparatus is in the recording operation, the optical head is adjusted using the focus and tracking error signals at the same reproduction level as when the optical disc recording/reproducing apparatus is in the reproducing operation. The focus and tracking mechanism can be controlled. Note that when the optical disc recording/reproducing apparatus is in a reproducing operation, the focus and tracking error signals are at the reproducing level as in the conventional case.

[Effects of the Invention] As explained above, according to the servo system of the optical disc recording and reproducing apparatus of the present invention, only focus and tracking error signals at the reproduction level are used during the recording operation of the optical disc recording and reproducing apparatus. Therefore, focus and i~racking servo control during recording operation can be performed stably, and the detection section can be easily adjusted, and furthermore, the servo circuit can be easily adjusted during recording and playback operations. There is an effect.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a servo mechanism to which the servo system of the optical disc recording/reproducing apparatus of the present invention is applied, Fig. 2 is a time chart diagram for explaining the servo system of the optical disc recording/reproducing apparatus, and Fig. 3 is a conventional optical disc. FIG. 4, a block diagram of the servo mechanism of the recording/reproducing apparatus, is a diagram for explaining a four-part detector that detects reflected laser light from an optical disk. In the figure, 1 is an optical disk, 4 is a detection unit (four-division detector),
5 is a focus error signal detection section, 6 is a tracking error signal detection section, 7 is a focus phase control section, 8 is a tracking phase control section, and 9a. 10a is an actuator, 12 is a focus phase control unit, and 12a is a focus S/H (sampling/halt)
circuit, 13 is a tracking phase control section, 13a is a tracking S/H (sampling/halt) circuit, L2
is the objective lens.

Claims (2)

[Claims] (1) A detection section that detects the intensity distribution of laser light of an optical disk recording/reproducing device, a focus error signal detection section that outputs a focus error signal based on the detection signal, and a tracking error signal detection section that outputs a tracking error signal. , a focus phase control unit that outputs a control signal for controlling the distance between the optical disc and the objective lens based on the focus error signal; and a control that controls a deviation between a track of the optical disc and the laser beam based on the tracking error signal. In a servo circuit of an optical disc recording and reproducing apparatus, the servo circuit of an optical disc recording and reproducing apparatus has a track king phase control section that outputs a signal, and drives and controls an actuator of the objective lens according to the control signal, during a recording operation of the optical disc recording and reproducing apparatus, The optical disc is characterized in that the focus phase control section and the tracking phase control section output the control signals based on a focus error signal and a tracking error signal at a reproduction level of a modulation signal for modulating and driving the laser beam. Servo system for recording/playback equipment. (2) In claim (1), the focus phase control section and the track king phase control section each sample a focus error signal and a tracking error signal at the reproduction level, and the recording level of the modulation signal is sampled. A servo system for an optical disc recording and reproducing device characterized by being provided with a sampling hold circuit that holds the data for a certain period of time.