JP2565251B2 - Automatic tracking controller - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an automatic tracking control device suitable for use in a helical scanning type video tape recorder that performs tracking control using a control signal.

[Outline of Invention]

The present invention provides a control signal (hereinafter referred to as a CTL signal) obtained in correspondence with a recording track in an automatic tracking control device suitable for use in a helical scanning video tape recorder that performs tracking control using a control signal, Tracking control is performed by the phase servo means according to the phase difference with the pulse signal (hereinafter referred to as PG signal) obtained corresponding to the rotational position of the reproducing head on the recording track, and the phase difference between the CTL signal and the PG signal is The circuit provided with the microcomputer automatically controls the high-frequency envelope output of the reproduction signal of the recording track to the maximum value, so that the tracking control is automatically performed well.

[Conventional technology]

Conventionally, a helical scanning type video tape recorder performs tracking adjustment so that a reproducing head accurately traces a recording track of a video signal in a so-called just tracking state as shown in Japanese Patent Publication No. 61-2521. There was a need. This tracking adjustment is performed by the phase servo system circuit (1) as shown in FIG. 4, for example. That is, the phase servo system circuit (1) is supplied to the input terminal (2), which is a PG signal which is a rotational position detection signal of the head drum having the reproducing head attached thereto, and the input terminal (3).
The phase difference with the CTL signal reproduced from the video tape supplied to the video tape is detected, and a tracking control signal is output from the output terminal (4) according to the phase difference. By supplying this tracking control signal to, for example, a capstan motor, tracking control is performed. The phase servo system circuit (1) has a variable resistor (5) whose one end is connected to the reference potential source (6) and whose other end is grounded, and an adjustment signal input terminal (1
a) is connected. For example, the operation of the variable resistor (5) delays the CTL signal and changes the phase difference between the CTL signal and the PG signal, which makes it possible to adjust the tracking control signal. ing.

With such a configuration, the operator can perform good tracking adjustment by operating and adjusting the variable resistor (5) so that the reproduced image by the reproduced signal of the recording track becomes the best. Has become.

[Problems to be solved by the invention]

However, there is a disadvantage in that it is difficult for a general user to perform such tracking adjustment favorably so that it is always in an optimum state. Further, if adjustment is possible using a variable resistor, it is necessary to attach an adjusting knob or the like to the front panel or the like of this video tape recorder, and the number of components is increased accordingly.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an automatic tracking control device that does not require manual adjustment.

[Means for solving problems]

The automatic tracking control device of the present invention, for example, as shown in FIG. 1, determines the phase difference between the CTL signal obtained corresponding to the recording track and the PG signal obtained corresponding to the rotational position of the reproducing head of the recording track. According to the phase servo means (1)
An envelope detection circuit (8) for performing tracking control by a high-speed envelope detection of a reproduction signal, a count means for counting a predetermined number, and first and second storage means for storing the count value of the count means. A microcomputer (10) having a third storage means for storing the detection value of the envelope detection circuit, and the count value when the control signal and the pulse signal start counting in advance and then become in phase again. The count value stored in the first storage means is counted up to the count value stored in the first storage means, and when the detection value of the envelope detection circuit is the maximum after the count of the counting means is started, the count value is stored together with the count value. The envelope detection values are stored in the second and third storage means, respectively, When the count value of the first storage means is completed, an adjustment signal corresponding to the count value stored in the second storage means is supplied from the microcomputer to the phase servo means (1) so that the CTL signal and the PG signal are supplied. The phase difference is controlled by the phase control means (10) to a value at which the high frequency envelope output of the reproduction signal of the recording track is maximized.

[Work]

In the automatic tracking control device of the present invention, the reproduction signal level of the recording track is maximized in the just tracking state of the reproduction head, so that the phase control means (10) controls the high frequency envelope output of the reproduction signal to be the maximum value. By doing so, the tracking is automatically adjusted to the optimally controlled state.

〔Example〕

An embodiment of the automatic tracking control device of the present invention will be described below with reference to FIGS. 1 and 2. This first
In FIGS. 2 and 2, parts corresponding to those in FIG. 4 are designated by the same reference numerals, and detailed description thereof will be omitted.

The automatic tracking control device of this example is configured as shown in FIG. In FIG. 1, (7) shows a reproduction signal input terminal to which a reproduction signal of a recording track of a video tape as a recording medium is supplied. The reproduction signal obtained at this reproduction signal input terminal (7) is detected by an envelope detection circuit. The signal is supplied to (8) and the envelope detection circuit (8) performs high frequency (RF) envelope detection of the reproduced signal. Then, the RF envelope detection signal output from the envelope detection circuit (8) is converted into an analog / digital converter (9).
After being converted into a digital signal by the microcomputer (1
Supply to 0). And this microcomputer (1
0) outputs a tracking adjustment signal according to the supplied RF envelope detection signal. The tracking adjustment signal output from the microcomputer (10) is supplied to the adjustment signal input terminal (1a) of the phase servo system circuit (1) via the digital-analog converter (11). And
By the tracking adjustment signal supplied to this adjustment signal input terminal (1a), CT in this phase servo system circuit (1)
The phase difference between the L signal and the PG signal is determined. Others are first
The configuration is similar to that of the tracking control device in the illustrated example.

The tracking control device of this example is configured as described above, and the tracking control operation will be described below with reference to the flowchart of FIG.

First, the microcomputer (10) outputs the adjustment signal supplied to the phase servo system circuit (1) at a predetermined value,
It is determined in the phase servo system circuit (1). CTL signal and PG
The adjustment signal is gradually changed and output so that the phase difference with the signal is gradually shifted. At this time, the count value “1” is set when the first adjustment signal is output, and the count value is advanced with each change of the adjustment signal, until the phase difference between the CTL signal and the PG signal changes to the same phase again. Proceed. in this case,
The count value when the phases are the same, that is, the maximum count value is stored in advance in the microcomputer (10).
Then, every time the adjustment signal is changed, the microcomputer (10) judges the RF envelope detection value of the reproduction signal detected by the envelope detection circuit (8), and the RF envelope detection value is the maximum value after starting counting. Sometimes, this RF envelope detection value is stored in the microcomputer (10) together with the count value at this time.

When the count value becomes maximum by operating the microcomputer (10) in this way, the count value when the RF envelope detection value becomes maximum value is stored in this microcomputer (10), After the count value reaches the maximum value, the microcomputer (10) supplies an adjustment signal corresponding to the count value when the RF envelope detection value reaches the maximum value to the phase servo system circuit (1). The state is maintained and the tracking adjustment work is completed.

By performing the tracking adjustment in this way, the adjustment signal automatically becomes the state when the RF envelope detection value of the reproduction signal becomes the maximum value. Here, when the reproducing head is tracing the recording track on the recording medium accurately, the reproduction signal level becomes the highest state.Therefore, when the RF envelope detection value of the reproduction signal is the maximum value, the tracking is optimally adjusted. It is in a broken state. Therefore, by operating the microcomputer (10) as described above, the phase servo system circuit (1) is supplied with the adjustment signal for setting the optimum phase difference, and the phase servo system circuit (1) is supplied. The tracking control is performed in the optimum state. From this, there is an advantage that the conventional manual adjustment work by a variable resistor or the like is unnecessary and the adjustment knob or the like can be omitted.

It should be noted that this adjustment work may be performed once, for example, during mute until the screen is displayed immediately after the reproduction of the recording signal of the video tape is started, or the tracking adjustment start button or the like is connected to the microcomputer (10). The adjustment work may be performed only when the lever button is operated.

In the above-described embodiment, the output signal of the microcomputer (10) is supplied to the adjustment signal input terminal (1a) of the phase servo system circuit (1). However, as shown in FIG. The CTL signal from 3) is supplied to the phase servo system circuit (1) via the programmable pulse generator (PPG) (12), and the control of this programmable pulse generator (12) is controlled by the microcomputer (10). )
You may do it in. That is, since the programmable pulse generator (12) determines the delay amount of the CTL signal supplied by the control signal supply state from the microcomputer (10), the microcomputer (10) detects the envelope detection value of the reproduction signal. By controlling this delay amount so that becomes the maximum value, the phase difference between the PG signal and the CTL signal supplied to the phase servo system circuit (1) is optimized, and by this phase servo system circuit (1) Good tracking control. In this case, the phase difference is not adjusted in the phase servo system circuit (1). According to the example of FIG. 3, the programmable pulse generator can be controlled by a digital signal, so that the digital-analog converter can be omitted. Furthermore, the present invention is not limited to the above-mentioned embodiments, and it goes without saying that various other configurations can be adopted without departing from the gist of the present invention.

〔The invention's effect〕

According to the automatic tracking control device of the present invention, there is an advantage that the tracking control can be automatically performed well.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an automatic tracking control device of the present invention, FIG. 2 is a flow chart diagram for explaining the example of FIG. 1, and FIG. 3 is a block diagram showing another embodiment of the present invention. FIG. 4 is a block diagram showing an example of a conventional tracking control device. (1) is a phase servo system circuit, (8) is an envelope detection circuit, and (10) is a microcomputer.

Claims (1)

(57) [Claims] 1. A tracking control is performed by a phase servo means according to a phase difference between a control signal obtained corresponding to a recording track and a pulse signal obtained corresponding to a rotational position of a reproducing head of the recording track, and An envelope detection circuit that performs high-frequency envelope detection of a reproduction signal, a counting unit that counts a predetermined number, and first and second storing the count value of the counting unit.
And a microcomputer having a third storage means for storing the detection value of the envelope detection circuit, and the count value when the control signal and the pulse signal are in phase again after they start counting in advance. Is stored in the first storage means, counting is performed up to the count value stored in the first storage means, and when the detection value of the envelope detection circuit is the maximum after the count of the counting means is started, The envelope detection value and the count value are stored in the second and third storage means, respectively, and the count value stored in the second storage means is stored when the count value of the first storage means is reached. A corresponding adjustment signal is supplied from the microcomputer to the phase servo means, and the control signal and The phase difference between the serial pulse signal, the automatic tracking control system RF envelope output of a reproduction signal of the recording track, characterized in that so as to control the value to be a maximum.