JPS62120189A - Line skip type ntsc-pal converter - Google Patents

Abstract

PURPOSE:To simplify an NTSC-PAL converter by deleting a chrominance signal of a PAL signal formed in the line skip type NTSC-PAL converter every 1H period and reducing the quantity of information into half of a normal PAL signal. CONSTITUTION:A burst gate signal B of an input terminal 2 is fed to a T-FF5 and becomes a switch control signal reversing every 1H period. An NTSC type carrier chrominance signal A is inputted from an input terminal 1 and fed to the first switch 3. The signal A is separated into a burst signal and a chrominance signal by a signal B. The signal A excluding the burst signal is fed to the second switch 4 and removed every 1H period by a switch control signal of an FF5. The carrier chrominance signal every 1H period is fed to an amplifier 9 and thereafter fed to an adder 11. The burst signal is fed to the first and the second phase shifting devices 6, 7. The burst signal from the phase shifting device 6 and the burst signal from the phase shifting device 7 are alternately taken out every 1H period and fed to the adder 11.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an NTSC-to-PML conversion device for video signal processing.

2. Description of the Related Art Conventionally, the NTSC-PAL conversion device used in consumer video tape recorders demodulates the NTSC carrier color signal into a color difference signal, and modulates the color difference signal into a 1PAL carrier color signal. be.

Problems to be Solved by the Invention However, in the above configuration, the NTSC carrier color signal is fully demodulated and the signal is modulated into the IPAL carrier color signal, which requires a demodulator and a carrier signal modulator, which is extremely complicated in terms of the structure. The problem was that it was complicated and expensive.

Means for solving all problems In order to solve the above problems, the line skip method N of the present invention is used.
The TSC-PAL converter converts 1 from the burst gate signal.
A flip-flop that generates a signal that is inverted every horizontal scanning (hereinafter referred to as 1H) period, a first switch that separates the NTSC carrier color signal into a burst signal and a color signal using a burst gate signal, and a first switch that separates the burst signal from the color signal using a burst gate signal. a second switch that extracts the carrier color signal from the flip-flop output every 1H period; a first phase shifter that shifts the phase of the burst signal extracted by the first switch to +45°; and -45°. a second phase shifter that shifts the phase to a second phase shifter, a third switch that alternately takes out signals from the first phase shifter and the second phase shifter every 1H period by the flip-flop output, and a second switch. and an adder for totally synthesizing the signals taken out from the third switch.

Effect of the Invention The present invention allows an NTS (knee PAL converter) to be constructed simply and inexpensively by the above-described configuration.

Embodiments Hereinafter, embodiments of a line-skip type NTSC-PAL converter according to the present invention will be described with reference to all the drawings.

FIG. 1 is a block diagram of one embodiment of the present invention.

In FIG. 1, 1 is an NTSC carrier color signal input terminal, 2 is a burst gate input terminal, 3 is a first switch,
4 is a second switch, 5 is a T-flip-flop, 6 is a first phase shifter, 7 is a second phase shifter, 8 is a third switch, 9 is an amplifier, 10 is an attenuator, 11 is a The adder 12 is an output terminal.

In the line skip type NTSC knee PAL converter of this embodiment configured as described above, a switch control signal is generated which is sent to the T-flip-flop 5 and is inverted every 1H period.

On the other hand, the NTSC carrier color signal is input from the input terminal 1 and sent to the first switch 3. The NTSC carrier color signal sent to the first switch 3 is divided into a burst signal and a color signal by a burst gate signal inputted from the input terminal 2. The carrier color signal from which the burst signal produced by the first switch 3 has been removed is sent to the second switch 4 and is removed every 1H period by the switch control signal produced by the T-flip-flop 5. The carrier color signal generated by the second switch 4 for each 1H period is sent to the amplifier 9, amplified by 3 dB, and sent to the adder 11.

On the other hand, the burst signal taken out by the first switch 3 is sent to the first phase shifter 6 and the second phase shifter element. The burst signal sent to the first phase shifter 6 is phase-shifted by +46° and sent to the third switch 8.

Also, the burst signal sent to the second phase shifter is -450
It is phase shifted and sent to the third switch 8.

The burst signal from the first phase shifter 6 and the burst signal from the second phase shifter 7 sent to the third switch 8 are T-
The signal is alternately taken out every 1H period by the switch control signal generated by the flip-flop 5 and sent to the attenuator 1Q. The burst signal sent to the attenuator 10 is attenuated by 5t3B and sent to the adder 11. The color signal from the amplifier 9 sent to the adder 11 and the burst signal from the attenuator 10 are added together and outputted from the output terminal 12.

In an apparatus configured as described above, the phase shift of each burst signal of the NTSC carrier color signal, such as the one shown in FIG. 2, is B.
It looks like this. When this signal is supplied to the input terminal 1, a signal like C in FIG. 2 is output to the output terminal 12, and the phase shift of each burst signal becomes like D in FIG.

In this way, in the PAL signal created by a line-skipping NTSC-PAL converter, the color signal is missing every 1H period, so the amount of information is half of that of a normal PAL signal. The resulting signal is regenerated into a normal color difference signal by the color demodulation circuit of the television receiver.

Effect of the invention As described above, according to the present invention, NTSC-FAI.

The conversion device can be obtained more simply and at a lower cost than conventional ones.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a waveform diagram of the same device. 1...NTSG carrier color signal input terminal, 2...
...Burst gate signal input terminal, 3...1st
Switch, 4...Second switch, 5...
・T-flip-flop, 6...first phase shifter, 7...second phase shifter, 8...third switch, 9... ...Amplifier, 10...Attenuator, 11...Adder, 12...Output terminal.

Claims (1)

[Claims] A flip-flop that creates a signal that is inverted every horizontal scanning period from the burst gate signal, a first switch that separates the NTSC carrier color signal from the burst signal using the burst gate signal, and a first switch that separates the burst signal from the color signal; a second switch for extracting the carrier color signal by the flip-flop output every horizontal scanning period; a first phase shifter for shifting the phase of the burst signal extracted by the first switch by +45°; and -45°. a second phase shifter that shifts the phase; a third switch that alternately extracts signals from the first phase shifter and the second phase shifter every horizontal scanning period according to the output of the flip-flop; 1. A line-skipping NTSC-PAL conversion device characterized by comprising an adder for combining signals taken out from a second switch and a third switch.