JP2504169B2 - Video phase converter - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a video phase converter, and more particularly to a video phase converter for converting the phase and frequency of a television composite signal.

[Conventional technology]

Conventionally, this type of video phase conversion apparatus has an analog / digital converter that converts an input television composite signal into a digital signal, and a data formed by the output data from the analog / digital converter from the input television composite signal. And a digital-analog converter for reading the data stored in the frame memory at a predetermined read address to produce an analog television composite signal.

According to such a video phase converter, the phase and frequency of the television composite signal can be converted.

[Problems to be Solved by the Invention]

However, in the above-mentioned video phase converter, the NTSC television composite signal has a color phase as the phase of the reference signal because the subcarrier, the horizontal sync signal phase, and the vertical sync signal phase have two frame periods. , To make the horizontal sync signal and vertical sync signal completely match
There is a drawback that the memory capacity of the frame is required and the memory capacity becomes large.

Further, in a video phase converter having only one frame memory capacity, in order to output the color phase in conformity with the reference signal, the video phase is output by being shifted by 140 [nS] with respect to the reference signal. There are drawbacks.

The present invention has been made to solve the above-mentioned drawbacks, and an object of the present invention is to provide a video phase conversion device capable of reducing the capacity of a frame memory and obtaining a television composite signal completely synchronized with a reference signal. And

[Means for solving the problem]

The video phase converter of the present invention includes an analog-digital converter that converts an input television composite signal into a digital signal, and a color frame signal superimposing circuit that superimposes a color frame signal on the digital signal from the analog-digital converter. , An input color frame detection circuit for detecting a color frame signal of an input television composite signal and giving it to a color frame signal superposition circuit, and a writing operation in which output data from the color frame signal superposition circuit is formed from the input television composite signal A frame memory that stores data based on an address, a read address generator that reads data stored in the frame memory with a read address formed from a reference signal, a chroma inversion circuit that captures the data read from the frame memory, and a frame memory Data read from Along with the capture, the output signal of the chroma inversion circuit is captured and the switcher that outputs either one, the memory output color frame detection circuit that detects the memory output color frame from the data read from the frame memory, and the color frame of the reference signal From the reference color frame detection circuit to detect, the chroma inversion control circuit that controls the switching of the switcher by comparing the output signal from the memory output color frame detection circuit with the output signal from the reference color frame detection circuit, and from the switcher Digital output that converts the output signal to an analog television composite signal
And an analog converter.

Since the video phase converter of the present invention is configured as described above, it is possible to reduce the capacity of the frame memory and perfectly synchronize it with the reference signal.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a video phase converter of the present invention. The embodiment of the video phase converter shown in FIG. 1 is connected to an analog / digital (AD) converter 1 connected to an input terminal Ti, a color frame signal superimposing circuit 2 and an input terminal Ti. Input color frame detector 3, write address generator 4 connected to input terminal Ti, 1-frame memory 5, read address generator 6, chroma inversion circuit 7, switcher 8, memory output It is composed of a color frame detection circuit 9, a reference color frame detection circuit 10, a chroma inversion control circuit 11, and a digital-analog (DA) converter 12.

The AD converter 1 is a converter that converts the television composite signal input from the input terminal Ti into a digital signal. The color frame signal superimposing circuit 2 superimposes the color frame signal CF on the digital signal from the AD converter 1. The input color frame detector 3 is a color frame signal CF of the television composite signal input from the input terminal Ti.
Is detected and supplied to the color frame signal superimposing circuit 2. The write address generator 4 can generate a write address from the input television composite signal. The frame memory 5 can store the output data from the color frame signal superimposing circuit 2 based on the write address. Read address generator 6
Can generate a read address from the reference signal BB. The data read from the frame memory 5 is configured to be supplied to the chroma inversion circuit 7, the switch 8 and the memory output color frame detection circuit 9. The chroma inversion circuit 7 can invert the phase of the data read from the frame memory 5. The switcher 8 takes in the data read from the frame memory 5 and takes in the output signal from the chroma inverting circuit 7, and can output either one. The memory output color frame detection circuit 9 is a circuit that detects a memory output color frame from the data read from the frame memory 5. The color frame of the reference signal input from the input terminal Tj can be detected. The output signal from the memory output color frame detection circuit 9 and the output signal from the reference color frame detection circuit 10 are compared in the chroma inversion control circuit 11, and the switch 8
A switch control signal Ct for controlling the switching of the switch can be generated. Digital-to-analog (DA) converter 12
Is capable of converting the output signal output from the switch 8 into an analog television composite signal and outputting the analog television composite signal from the output terminal To.

 The operation of the embodiment thus configured will be described.

FIG. 2 is a timing chart when the color flags of the input television composite signal and the reference signal coincide with each other in the embodiment. FIG. 3 shows the same embodiment as
It is a timing diagram when a color flag does not correspond with an input television composite signal and a reference signal.

The television composite signal is converted into a PCM signal by the AD converter 1. On the other hand, an address signal for writing the television composite signal converted into the PCM signal by the write address generator 4 from the synchronization signal (horizontal synchronization signal, vertical synchronization signal, burst signal) of the input television composite signal into the frame memory 5 is generated. . The input color frame detector 3 generates an input color flag CF whose polarity is inverted every frame from the horizontal synchronizing signal of the input television composite signal and the burst signal. Also, its input color flag CF
Replaces one bit of the PCM signal and superimposes it on one predetermined horizontal period (H) within one blanking.
It is the color frame signal superposition circuit 2 that does this,
The phase to be superimposed is determined by the output signal of the write address generator 4.

On the other hand, the read address generator 6 is similarly operated from the reference signal.
Then, the read address of the frame memory 5 is produced, and the reference color frame detection circuit 10 produces the color flag CFa of the reference signal.

Since the data read from the frame memory 5 includes the input color flag CFb superimposed on the input side, this is detected by the memory output color frame detection circuit 9 and given to the chroma inversion control circuit 11. In the chroma inversion control circuit 11, the color flag CFb from the memory output color frame detection circuit 9 and the reference color frame detection circuit 10
Compare with the color flag CFa from.

In this chroma inversion control circuit 11, two input signals CFa,
If the polarities of CFb are the same as shown in FIG. 2, a low level signal is output, and if the polarities of the two input signals are not the same as shown in FIG. 3, a high level signal is output.

When the output signal Ct from the chroma inversion control circuit 11 is a low level signal, the switching 8 is switched to the (a) side, and the read data from the frame memory 5 is directly applied to the DA converter 12.

Also, when the output signal Ct from the chroma inversion control circuit 11 is a high level signal, the switch 8 is switched to the (b) side, and the read data from the frame memory 5 is DA converted via the chroma inversion circuit 7. Give to vessel 12.

The data thus obtained is converted into an analog television composite signal by the DA converter 12. This signal is read out by the read address generator 6 with the horizontal synchronizing signal phase and the vertical synchronizing signal phase in agreement with the reference signal, but if the chroma is inverted, the color phase is also in agreement with the above control. Will be done.

〔The invention's effect〕

As described above, the present invention has an effect that even in a device that does not have the capacity of one frame memory, the color phase and the video phase can be perfectly matched and output with respect to the reference signal.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIGS. 2 and 3 are timing charts for explaining the operation of the embodiment. 1 ... AD converter, 2 ... Color frame signal superimposing circuit, 3 ... Input color frame detector, 4 ... Write address generator, 5 ... Frame memory, 6 ... Read address generator, 7 ... Chroma inversion circuit, 8 switch, 9 memory output color frame detection circuit, 10 standard color frame detection circuit, 11 chroma conversion control circuit, 12 DA converter.

Claims (1)

(57) [Claims] 1. An analog / digital converter for converting an input television composite signal into a digital signal, and a color frame signal superimposing circuit for superimposing a color frame signal on a digital signal from the analog / digital converter, An input color frame detection circuit for detecting a color frame signal of a television composite signal and giving it to the color frame signal superposition circuit, and output data from the color frame signal superposition circuit to a write address formed from the input television composite signal. A frame memory for storing the data on the basis of the frame memory, a read address generator for reading the data stored in the frame memory with a read address formed from a reference signal, a chroma inverting circuit for fetching the data read from the frame memory, Day read from The output signal of the chroma inversion circuit and outputs one of them, the memory output color frame detection circuit for detecting the memory output color frame from the data read from the frame memory, and the reference signal A reference color frame detection circuit for detecting a color frame, and a chroma inversion control for comparing the output signal from the memory output color frame detection circuit with the output signal from the reference color frame detection circuit to control switching of the switcher. A video phase conversion device comprising: a circuit; and a digital-analog converter that converts an output signal output from the switching device into an analog television composite signal.