JPH0770087B2 - Servo device in recording disk reproducing device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a servo device in a recording disk reproducing device.

BACKGROUND ART In a disc reproducing apparatus that optically reproduces record information of a recording disc (hereinafter, simply referred to as a disc) such as a digital audio disc or a video disc, the spindle servo device controls the rotation drive of the disc. The recording information is read by a pickup that is movable in the radial direction.

Further, in such a disc reproducing apparatus, a focus servo device for controlling the information detection light spot by the pickup so as to be correctly converged on the recording surface of the disc, and the light spot is formed on the recording surface of the disc, for example, in a spiral shape. Various servo devices such as a tracking servo device that controls so as to accurately track a recording track and a time axis servo device that controls to correct a time base (time base) fluctuation of a reproduction signal are indispensable.

In a conventional device including these various servo devices, signal processing such as equalizing for an error signal obtained in each servo system is performed by a signal processing circuit provided for each servo system, so that the circuit elements are There are drawbacks that the number becomes huge, the circuit configuration becomes complicated, and the cost becomes high.

SUMMARY OF THE INVENTION The present invention has been made in order to eliminate the above-mentioned drawbacks of the conventional one, and by performing signal processing of each error signal digitally in a time division manner, a signal processing circuit is made common and a circuit is provided. It is an object of the present invention to provide a servo device in a recording disk reproducing device that can simplify the configuration and reduce the cost.

A servo apparatus according to the present invention is a servo apparatus in a recording disk reproducing apparatus having a plurality of servo systems including at least a time axis servo system, and is an integer of a synchronization signal included in a read signal read from a recording disk. A timing controller for generating a sampling signal having a double frequency, a first switching means for sequentially and alternately capturing each servo error signal of each servo system for each sampling signal, and a first switching means for capturing the same. Arithmetic processing means for sequentially performing a predetermined arithmetic processing on each of the servo error signals thus obtained to obtain an arithmetic servo error signal, and alternatively, supplying the arithmetic servo error signal to each controlled part of each servo system. And a second switching means, which corresponds to the time axis servo system in each of the servo error signals. Wherein the capture servo error signal that in synchronism with the generation timing of the synchronization signal.

Example Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention.
In the figure, the switching circuit 1 for selectively outputting a plurality of inputs includes, for example, error signals of three types of servo systems, that is, a time axis servo system, a focus servo system, and a tracking servo system, that is, a time axis error signal. , A focus error signal and a tracking error signal are input. The switching circuit 1 is composed of, for example, three analog switches provided corresponding to each servo system.

In the time axis servo system, when the recording disc is a video disc, the read RF (high frequency) read from the disc.
A signal corresponding to the phase difference between the horizontal synchronization signal separated and extracted from the signal and the reference horizontal synchronization signal is used as the time axis error signal. Therefore, the time axis error signal is derived every time the horizontal synchronizing signal is generated. On the other hand, the focus error signal is a well-known detection method such as an astigmatism method, a critical angle detection method or a knife edge method, and the tracking error signal is a three-beam method, a push-pull method, a heterodyne method or a time difference detection method. It is generated by a known detection method.

When each analog error signal of the time axis, focus and tracking is input, the switching circuit 1 sequentially outputs each unlogged error signal in time division in synchronization with the timing pulse generated from the timing controller 2. For example,
Since the time-axis error signal is derived each time the horizontal synchronization signal is generated, the time-axis error signal is output every 1H (H is a horizontal scanning period), and the focus error signal and the tracking error signal are output at an appropriate timing within this 1H period. Output each king error signal. Regarding the tracking error signal, the focus error signal is output once in the period of 1H, whereas it is generated twice, for example. Thereby, from the switching circuit 1, for example, in the 1 / 4H cycle, the time axis error signal, the tracking error signal, the focus error signal, the tracking error signal, the time axis error signal,
The analog error signals are sequentially output in time sequence in the order of.

These analog error signals are supplied to the sample hold circuit 3 and sampled and held at each of the above timings.
That is, the time axis error signal and the focus error signal are sampled at a cycle of 1H, and the tracking error signal is sampled at a cycle of 1 / 2H. This sample-hold output is converted into a digital error signal by the A / D (analog / digital) converter 4 and then the CPU (central processing circuit)
And the like are supplied to the arithmetic processing circuit 5. The arithmetic processing circuit 5 performs arithmetic processing such as predetermined equalizing on each digital error signal. The processed digital error signal is D / A (digital / analog) 6
After being converted into an analog error signal by, it is supplied to the switching circuit 7. The switching circuit 7 distributes the serially supplied analog error signals at the previous sampling timing and supplies the analog error signals to the controlled unit of each servo system.

In the time axis servo system, for example, a CCD (charge coupled device), which is a variable delay element that is inserted in the signal line of the reproduction processing system of the read RF signal and whose delay amount changes according to the signal level of the time axis error signal, In the servo system, the focus actuator that drives the objective lens that forms a part of the optical system of the pickup in the optical axis direction thereof, and in the tracking servo, the docking actuator that swings the optical system of the pickup becomes the driven part. .

In such a configuration, as shown in FIG. 2, the timing controller 2 synchronizes with the reproduction horizontal synchronization pulse (a) for each servo system, for example, with a phase difference of 1 / 4H from each other, for 1H period (b). , 1 / 2H period (c) and 1H period (d) timing pulses are generated, respectively. The switching circuit 1 responds to these timing pulses (b) to (d) by, for example, time axis error signal, tracking error signal, focus error signal, tracking error signal, time axis error signal, ... The switching control is performed so as to sequentially output in a time division manner. The time-divided error signals are sample-held in the sample-hold circuit 3 in synchronism with the timing pulses (b) to (d) and A / D converted. Then, as shown in FIG. 8E, digital equalization and the like are sequentially performed, and
After D / A conversion, the switching circuit 7 distributes each system in synchronization with each of the timing pulses (b) to (d), and the corresponding controlled parts, that is, the tracking actuator, the focus actuator, and the CCD described above. Is supplied to each. In FIG. 2 (e), the shaded portion is a blank period, and the other portion is a processing period of each servo system.

Here, the sampling cycle of the focus error signal is set to be twice as long as that of the tracking error signal. This is because the mass of the actuator to be controlled is larger in the focus servo system than in the tracking servo system. Since it is poor in performance and the tolerance of residual error is large,
This is because even if the sampling cycle is set large, it can be sufficiently controlled. In other words, by increasing the sampling cycle of the focus error signal, the sampling cycle of the tracking error signal can be shortened, so that the tracking accuracy can be improved accordingly.

The sampling cycle is not limited to double, but an integer multiple of two or more is a preferable value.
In this way, by setting the sampling period in synchronization with the horizontal synchronizing pulse and setting it to an integral multiple thereof, the arithmetic processing of each servo system can be regularly performed, so that the arithmetic processing circuit 5 and the like can be efficiently utilized. become.

In the above embodiment, the tracking servo system,
In the focus servo system and the time axis servo system, the case where the signal processing of each error signal is digitally performed in a time division is explained, but the spindle servo system and the slider servo system are also digitally performed in a time division manner. It is also possible to perform signal processing.

Here, in a time axis servo system or a spindle servo system, an oscillator that generates a reference horizontal synchronizing pulse for generating an error signal is indispensable, but the oscillator is a reference oscillator for generating a timing pulse in the timing controller 2. Can also be used as As a result, the circuit configuration of the timing controller 2 can be simplified.

As described above, according to the present invention, the signal processing from the A / D converter to the D / A converter is performed by time-divisionally performing the signal processing of each error signal of various servo systems. Since the circuit can be used in common for each servo system,
For example, it is possible to reduce the circuit scale and reduce the cost associated with the IC (integrated circuit).

In addition, by setting the sampling frequency based on the frequency of the reference signal included in the read signal from the disk, if a servo system that generates an error signal based on the reference signal is included, the error is generated at the error signal generation timing. Since you can reliably sample the signal,
Even with signal processing by time division, it is possible to surely control each servo system.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a timing chart showing operation timing of the circuit of FIG. Explanation of symbols of main parts 1,7 ...... Switching circuit 2 ...... Timing controller 3 ...... Sample and hold circuit 5 ...... Arithmetic processing circuit

Claims (1)

[Claims] 1. A servo device in a recording disk reproducing device having a plurality of servo systems including at least a time axis servo system, wherein the servo device has an integral multiple of a synchronization signal included in a read signal read from the recording disk. A timing controller that generates a sampling signal of a frequency, a first switching unit that sequentially takes in each servo error signal of each servo system for each sampling signal, and a first switching unit that takes in the servo error signal. Arithmetic processing means for sequentially performing a predetermined arithmetic processing on each of the servo error signals to obtain an arithmetic servo error signal; and a means for selectively supplying the arithmetic servo error signal to each controlled part of each servo system. 2 switching means, wherein the first switching means is a servo corresponding to the time axis servo system in each of the servo error signals. The servo device error signal in the recording disk reproducing apparatus characterized by incorporating in synchronism with the generation timing of the synchronization signal.