JPH0632466B2 - Information recording / reproducing apparatus tansen salvo signal generator - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tangential servo signal generator for a recorded information reproducing apparatus, and more specifically, for moving a reading pickup in a track tangential direction of a recording disk in the information reproducing apparatus. The present invention relates to a tangential servo control signal generator for controlling.

[Background of the Invention]

Various servo devices are indispensable for obtaining good reproduction information, for example, a reproduced image, in a reproducing device for recorded information. One of them is a so-called tangential servo control device as a time axis correction of a reproduction signal. The reproduced color burst signal is output while the phase of the horizontal synchronizing signal is inverted every other cycle to detect a predetermined timing on the output, and a tangential servo signal is generated according to the phase difference between the generation timing and the reference signal. Regarding the conventional device described above, Japanese Patent Laid-Open No.
It is disclosed in No. 6-84091. The reading means can forcibly change a predetermined portion of the output waveform, the generation timing of which should be detected, in response to a command signal instructing the recording track to jump over. However, during special playback, no particular consideration is given to playback modes that do not have an appropriate jump signal such as search and scan.
There is a case where a predetermined position of the color burst signal cannot be detected during the special reproduction. Further, since the low-level / high-level output of the FF4 shown in FIG. 1 of the above-mentioned conventional example is defined by the power-on timing etc. regardless of the phase relation of the reproduced color verse, always detect a specific position of the color verse. It is difficult. When a reproduced color burst at a position deviated from the specific position of the reproduced color burst is sampled using a ramp waveform (trapezoidal wave etc.), the sampling voltage value has a DC offset as compared with the case of detecting the specific position. This is equivalent to the occurrence of a shift. Therefore, when the object to be tangentially controlled is driven by DC using the sampling signal, even if the DC voltage of the trapezoidal wave is held down to almost 0 when the phase of the horizontal reference signal is locked with respect to the specific timing of the color burst, the search is performed. If a special reproduction such as a scan is performed or the power is turned on again, a DC offset voltage is generated in the voltage sampled on the trapezoidal wave for the above reason. Therefore, when the tangential control target is DC-driven by the voltage sampled on the trapezoidal wave, control is performed with the 0 voltage of this signal as a target, and the phase difference between the reference horizontal synchronization signal and the reproduction horizontal synchronization signal is shifted. There was a drawback that I could go.

[Object of the Invention]

The present invention has been made in order to eliminate the above-mentioned drawbacks of the prior art. Therefore, the object of the present invention is to make the reference horizontal synchronizing signal and the reproducing horizontal synchronizing signal stationary even if the position where the reproduced color burst is detected is deviated. It is an object of the present invention to provide a tangential servo signal generator for an information recording / reproducing apparatus which can satisfactorily perform tangential servo up to the DC region without causing any phase difference.

[Outline of Invention]

When the tangential control target is driven by DC, and when it is deviated from a predetermined color burst detection position for some reason, the voltage sampled and held on the slope waveform is changed by the DC offset and the positions of the reproduction horizontal synchronization signal and the reference horizontal synchronization signal are changed. The phase difference shifts. As a method of removing this offset variation, a phase comparator for the reference horizontal synchronizing signal and the reproduced horizontal synchronizing signal is provided, this phase detection error is injected into the trapezoidal wave generation circuit, and the start position of the trapezoidal wave is controlled.
The voltage sampled on the trapezoidal wave is changed so that the phase error between the horizontal synchronizing signals becomes zero.

Example of Invention

An embodiment of the present invention will be described below with reference to FIG. 1 (block diagram). The horizontal phase comparator 18 receives the reference horizontal synchronizing signal B obtained from the reference horizontal synchronizing signal generating circuit 6 as one input, and reproduces the horizontal synchronizing signal C obtained from the horizontal synchronizing separating circuit.
Is used as the other input to generate a two-input phase error. This output is applied to the trapezoidal wave generating circuit through an integrating circuit 19 having a cutoff frequency sufficiently lower than the cutoff frequency of the APC of the television monitor. The output of the integrating circuit 19 is directly connected to a circuit for starting the inclination of the trapezoidal wave inside the trapezoidal wave generating circuit 12, and the start position of the trapezoidal wave is the phase difference between the reference horizontal synchronizing signal B and the reproduced horizontal synchronizing signal C. The start position of the trapezoidal wave is controlled so that becomes 0.
The operation of this portion will be further described in detail with reference to FIG. 2 (signal waveform diagram). For some reason, a predetermined timing on the burst waveform D output from the switch 4 to be sampled.
Suppose that t ₁ is out of alignment with t ₂ . The voltage on the trapezoidal wave that causes a phase error changes by DC for the output voltage + V depending on the time from t ₁ to t _2.
DC occurs. (Fig. 2 (a) part) When the tangential actuator moves like a DC in response to this phase error, the phase difference between the reference horizontal sync signal and the reproduced horizontal sync signal is | t ₁ −t ₂ |
Only happens. (FIG. 2 (a)) This phase difference is detected by the horizontal phase comparator, and the start position of the trapezoidal wave is slowly moved by the action of the integrator 19 in the direction of canceling the phase difference of | t ₁ −t ₂ |. By moving, the voltage sampled on the trapezoidal wave gradually generates a negative voltage (Fig. 2 (c)), and the horizontal phase difference gradually decreases accordingly and stabilizes at | t ₁ −t ₂ | = 0. . (FIG. 2 (D) part) According to the present embodiment, even if the burst detection timing is deviated for some reason, the phase difference between the reference horizontal sync signal and the reproduced horizontal sync signal, which is a steady point, can be suppressed to almost zero. There is an effect to obtain.

A trapezoidal wave was obtained from the reference horizontal synchronizing signal, but it is sufficient to obtain a signal waveform having a slope. Further, the moving speed of the start position of the above-mentioned inclination of the trapezoidal wave is slow and does not affect the TV monitor.

〔The invention's effect〕

According to the present invention, even if there is a phase difference between the reference horizontal synchronizing signal and the reproduced horizontal synchronizing signal due to the deviation of the predetermined detection timing after a special play such as a search / scan or for some other reason, the phase difference is returned to 0 again. There is an effect that the obtained tangential servo signal of the information recording / reproducing apparatus can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG.
It is a signal waveform diagram of each part when the burst detection timing in the circuit of the figure is shifted. Explanation of symbols 1 ... Color burst separation circuit, 6 ... Reference horizontal synchronization signal generation circuit, 8 ... Horizontal synchronization separation circuit, 12 ... Trapezoidal wave generation circuit, 13 ... Sample hold circuit, 18 ... Horizontal synchronization phase Comparison circuit, 19 ... Integrating circuit.

Continuation of the front page (72) Inventor Akio Nakajima 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa, Japan (56) References JP-A-56-84091 (JP, A) JP-A-59-140785 (JP, A) JP 60-249496 (JP, A) JP 59-94985 (JP, A) Actual development Sho 58-155668 (JP, U)

Claims (1)

[Claims] 1. A reproduction color burst generating means for outputting the reproduction color burst signal by the reading means while inverting the phase every other cycle of the reproduction horizontal synchronizing signal, and a predetermined portion of the horizontal cycle on the output waveform of the reproduction color burst generating means. Means for generating a reproduction phase signal by detecting the generation timing of, a means for generating a ramp wave shape signal using a reference signal arriving at a horizontal synchronization cycle, and a level of the ramp wave shape signal by the reproduction phase signal. In a tangential servo signal generator of an information recording / reproducing apparatus including a sampling means, a phase difference detecting means for detecting a phase difference between the reference signal and a horizontal synchronizing portion of the reproduced horizontal synchronizing signal, and the phase difference detecting means. Depending on the output of
A tangential servo signal for an information recording / reproducing apparatus, comprising means for moving a start position, and changing the level of a signal on a sloped waveform corresponding to a predetermined position on the output waveform of the reproduction color burst generation means. Generator.