JPS6221114Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a color television camera device, and more particularly to a color television camera drive signal generation circuit.

Conventionally, color television cameras have used camera drive signal generating circuits as shown in FIG. 1 or 2. In the case of Figure 1,
A color subcarrier S 1 , a synchronization signal S ₂ , and horizontal and vertical drive signals S ₃ are generated by an oscillator 1 with a frequency of the color subcarrier frequency or an integral multiple thereof and a synchronization signal generator ₂ driven by it. Was.

In addition, in FIG. 2, the crystal oscillator 3 for the color subcarrier and the voltage controlled oscillator 5 of the CIOCK frequency of the synchronizing signal generator 4 are independently provided, and their frequency relationship is synchronized by the frequency dividers 6 and 7 and the phase comparator 8. let me,
It generates a constant color subcarrier and horizontal and vertical drive signals. However, the first
In both cases shown in Fig. 2 and Fig. 2, the phase relationship between the color subcarrier and the horizontal synchronizing signal is uniquely determined by the circuit, and the phase cannot be adjusted independently. Incidentally, FIG. 3 is a diagram showing signal waveforms of the main part of FIG. 2.

However, in recent years, with the development of digital technology, television signals are increasingly being digitally processed, and there is a trend toward regulating the phase relationship between the horizontal synchronizing signal of the video and the color subcarrier to a constant value. In this case, in conventional circuits, in order to specify the phase relationship by the method of the color subcarrier and chroma signal processing circuits in the color encoder, detailed constraints are placed on the delay times of the color encoder's subcarrier and chroma signal processing circuits. I needed to.

Therefore, an object of the present invention is to provide a color television camera that can accurately match the phase relationship between the horizontal synchronization signal of the output color video signal and the color subcarrier to the standard, regardless of the configuration of the signal processing system in the color encoder. An object of the present invention is to provide a drive signal generation circuit.

According to the present invention, a crystal oscillator that generates color subcarriers, a first frequency divider that divides the frequency of the color subcarriers, and a voltage controlled oscillator (VCO),
A sync signal generator that generates a sync signal and camera vertical and horizontal drive signals based on the VCO output, a second frequency divider that divides the frequency of the horizontal drive signal, and outputs of the first and second frequency dividers. Compare the phase of the
It is equipped with a phase comparator that controls the output frequency of the VCO, and a delay device that is inserted between the phase comparator and the phase comparator to delay the output of at least one of the first and second frequency dividers. By adjusting the delay time, it is possible to obtain a color television camera drive signal generation circuit that can arbitrarily set the phase between the horizontal synchronizing signal and the color subcarrier in the output video signal.

Next, the present invention will be described in detail with reference to the drawings of an embodiment of the present invention. FIG. 4 is a diagram showing an embodiment of the present invention, and the figure shows a crystal oscillator 3 that oscillates a color subcarrier frequency and a frequency divider (1/455 or 1/910, etc.) that divides the color subcarrier frequency. 6
, a delay circuit 8 that delays the output of the frequency divider 6, a voltage controlled oscillator 5 that is controlled by the output of the phase comparator 8, a synchronization signal generator 4 that operates using the output of the VCO 5 as a clock, and a drive signal. It consists of a frequency divider 7 (1/2, 1/4, etc.) that divides the frequency of the horizontal drive signal out of _S3 .

Here, the color subcarrier output is directly supplied to the color encoder. Further, the frequency of the color subcarrier is divided into 1/455 or 1/910 by a frequency divider 6. 1/45 of color subcarrier frequency
5 and 1/910 are 1/2 and 1/4 of the horizontal drive frequency, respectively. Therefore, s/455, s/910 (s: color subcarrier frequencies) must be equal. Therefore, both are input to the phase comparator 8, and the output thereof controls the oscillation frequency of the voltage controlled oscillator 5, thereby synchronizing the color subcarrier and the horizontal drive frequency. In this case, if the delay circuit 9 were not provided, the color subcarrier and horizontal drive signal would be in the same phase as shown in FIG.

In this embodiment, since the signal obtained by dividing the frequency of the color subcarrier entering the phase comparator 8 by the delay device 9 is delayed by a certain delay time, as can be seen from FIG. 5, the phase relationship between the color subcarrier and the horizontal drive signal is as follows.
By adjusting this delay time, the phase relationship between the color subcarrier and the horizontal drive signal (horizontal synchronization signal) can be arbitrarily adjusted. It goes without saying that the same effect can be obtained by inserting and adjusting a delay device on the output side of the frequency divider 7.

As described above, the present invention has the advantage that by configuring a phase comparator circuit including a delay circuit, the phase relationship between the horizontal synchronizing signal and the color subcarrier in the output video signal can be accurately set to a constant value.

[Brief explanation of the drawing]

1 and 2 are diagrams showing a conventional camera drive signal generation circuit, FIG. 3 is a diagram showing the relationship of signal waveforms in the main parts of FIG. 2, and FIG. 4 is a diagram showing an embodiment of the present invention. , FIG. 5 is a diagram showing the relationship of signal waveforms in the main parts of FIG. 4. In the figure, 1, 3...crystal oscillator, 2, 4...
...Synchronization signal generator, 5...Voltage controlled oscillator, 6,
7... Frequency divider, 8... Phase comparator, 9... Delay device.

Claims (1)

[Scope of utility model registration request] a crystal oscillator that generates color subcarriers;
a first frequency divider that divides the color subcarrier;
a voltage controlled oscillator whose frequency changes depending on the control voltage; a synchronizing signal generator that generates a synchronizing signal and vertical and horizontal drive signals based on the output of the voltage controlled oscillator; and a second frequency generator that divides the frequency of the horizontal drive signal. a phase comparator that compares the phases of the outputs of the first and second frequency dividers and uses the comparison output as the control voltage; and an output of at least one of the first and second frequency dividers. and a delay device inserted before the phase comparator to arbitrarily delay the phase comparator.