JPH0723420A - Color signal processor - Google Patents

Abstract

PURPOSE:To facilitate the circuit integration by passing a signal through the same path for the reproduction of the PAL system and the MESECAM system so as to eliminate a difference between delay time between the systems. CONSTITUTION:A switch circuit 7 is made conductive state by a control signal from a control signal input terminal 8 at the reproduction of the PAL system and the frequency characteristic of the amplitude of the output from an adder 4 indicates a comb line characteristic to eliminate a crosstalk component. In the MESECAM system reproduction, the switch circuit 7 is made open state by a control signal from the control signal input terminal 8 and the frequency characteristic of the amplitude of the output of the adder 4 does not indicate any comb line characteristic. Furthermore, a variable amplifier 9 switches an amplification factor so that the output amplitude of the output terminal 6 is the same as for the reproduction by the PAL system and the reproduction of the NTSC system with the control signal from the control signal input terminal 10. Thus, at the time of signal passes through an LPF 5 at the reproduction, and at the reproduction of the NTSC system, the same delay time is obtained between the two systems.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to color signal processing in a video magnetic recording / reproducing apparatus (hereinafter abbreviated as VTR) for recording / reproducing a color video signal.

[0002]

2. Description of the Related Art In recent years, it has become indispensable to support not only the broadcasting system of the home country but also various broadcasting systems with the activation of international exchange. Especially in European countries where two types of broadcasting systems, PAL and SECAM, coexist, there is a great need.

An example of color signal processing of a VHS system video signal processing apparatus for recording and reproducing a color video signal will be described below with reference to the drawings.

The guard bandless recording method of the PAL low-frequency conversion color signal processing is one horizontal scanning period (hereinafter abbreviated as 1H) for each 90 ° phase of the carrier color signal of one track.
The crosstalk component is removed by a comb-shaped filter configured to add and record signals delayed by two horizontal scanning periods (hereinafter abbreviated as 2H) during reproduction.

On the other hand, since the color signal of the SECAM system is an FM modulation signal, the signal component will be lost if the above processing is performed. Therefore, the SECAM system color signal is processed by the PAL system low frequency conversion color signal processing and recorded / reproduced.
The SECAM method does not pass through a comb filter.

Further, as a recent technical trend, in the case of forming a comb filter, there is an increasing number of cases where a charge coupled device (hereinafter abbreviated as CCD) delay line is used instead of a glass delay line for delaying 2H.

FIG. 2 is a conventional PAL compatible with MESECAM.
FIG. 4 is a block diagram around a CCD comb filter for removing crosstalk of a reproduction signal of a VTR of a system.

The carrier color signal input from the input terminal 1 is 3
Distributed to two. One is input to the switch circuit 12. One is input to the adder 4. One is input to the CCD delay line 2, delayed, and output to the adder 4. At this time, the CCD is 1701 bits, 4.43361875M
It is driven at a clock frequency three times Hz and has a delay time of 2H. At this time, the output of the adder 4 exhibits a comb characteristic.
The output of the adder 4 is amplified by the amplifier 11 and then input to the low-pass filter 5 (hereinafter abbreviated as LPF 5) to generate CC
The unnecessary frequency component added as the D delay line passes is removed and then input to the switch circuit 12. The switch circuit 12 selects an input according to the control signal from the control signal input terminal 13 and outputs a carrier color signal from the output terminal 6.

At the time of PAL system reproduction, control signal input terminal 1
The output of LPF5 is selected by the control signal from 3 and M
The output from the input terminal 1 is selected during the ESECAM system reproduction.

[0010]

However, in the above-mentioned configuration, when the PAL system is reproduced, the LPF 5 is passed through in order to remove the unnecessary frequency component that is added as the CCD delay line is passed. The delay time causes a difference in the delay time of the color signal between the PAL system reproduction and the MESECAM system reproduction. When the delay times of the luminance signal and the chrominance signal match during PAL system reproduction, the chrominance signal advances with respect to the luminance signal during MESECAM reproduction.

The present invention is intended to solve the above-mentioned problems.
An object of the present invention is to provide a color signal processing device which does not cause a difference in delay time between the respective systems by passing the same path during the AL system reproduction and the MESECAM system reproduction and which can be easily integrated into a circuit.

[0012]

In order to achieve the above-mentioned object, the present invention uses a charge coupled device delay line for delaying two horizontal scanning periods and an output of the charge coupled device delay line as an input signal and opens it by a control signal. A switch circuit, an adder that adds the same signal as the output from the switch circuit and the input of the charge-coupled device, and an amplifier whose input signal is the output signal of the adder and whose amplification factor can be changed by a control signal, Equipped with a low-pass filter that receives the output of the amplifier as an input and removes unnecessary frequency components that are added when passing through the delay line of the charge-coupled device.By controlling the switch circuit and the amplifier with a control signal, the frequency characteristic of the output amplitude is comb-shaped. The video signal processing device is characterized in that it is possible to switch between a case where the characteristic exhibits a comb characteristic and a case where the characteristic does not exhibit the comb characteristic.

[0013]

According to the present invention, by the above-described structure, the same path is passed during the PAL system reproduction and the MESECAM system reproduction so that the delay time does not differ between the respective systems and the color signal processing which is easily integrated into a circuit is performed. A device can be provided.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Color signal processing according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a peripheral portion of a CCD comb filter for removing crosstalk of a reproduction signal of a PAL system VTR compatible with MESECAM system reproduction according to the present invention.

The carrier color signal input from the input terminal 1 is 2
Distributed to two. One is input to the adder 4. The signal is input to the CCD delay line 2 and delayed by 2H, and then input to the adder 4 via the switch circuit 7. The output of the adder 4 is amplified by the variable amplifier 9 and then output from the output terminal 6 through the LPF 5.

At the time of PAL system reproduction, the switch circuit 7 becomes conductive by the control signal from the control signal input terminal 8. At this time, the frequency characteristic of the amplitude of the output of the adder 4 shows a comb characteristic, and the crosstalk component is removed.

During reproduction by the MESECAM system, the switch circuit 7 is opened by the control signal from the control signal input terminal 8. At this time, the frequency characteristic of the output amplitude of the adder 4 does not show the comb characteristic.

The variable amplifier 9 has a control signal input terminal 1
The control signal from 0 causes the output amplitude of the output terminal 6 to be PAL.
The amplification factor is switched so that it is the same during system playback and MESECAM playback.

As described above, according to the color signal processing apparatus of this embodiment, the LPF 5 is passed in both the PAL system reproduction and the MESECAM system reproduction, so that the two systems have the same delay time.

[0021]

As described above, according to the present invention, PAL
Since the same delay time is set between the two systems during system playback and MESECAM system playback, the delay time with respect to the luminance signal does not lag due to the system differences.

Further, it is easy to form an integrated circuit.

[Brief description of drawings]

FIG. 1 is a block diagram of a color signal processing device according to an embodiment of the present invention.

FIG. 2 is a block diagram of a conventional color signal processing device.

[Explanation of symbols]

 1 Input Terminal 2 Charge Coupled Device 3 Clock Signal Input Terminal 4 Adder 5 LPF 6 Output Terminal 7 Switch Circuit 8 Control Signal Input Terminal 9 Variable Amplifier 10 Control Signal Input Terminal

Claims (1)

[Claims] 1. A color signal processing device for frequency-converting a carrier color signal to a low frequency band for recording and inverse conversion at the time of reproduction, the charge-coupled device delay line delaying for two horizontal scanning periods, and the charge-coupled device delay line. A switch circuit which is opened by a control signal with the output of the input signal as an input signal, an adder for adding the same signal as the output from the switch circuit and the input of the charge coupled device, and a control signal with the output of the adder as the input And a low pass filter for removing an unnecessary frequency component given to the output of the amplifier when the charge coupled device delay line is passed, and controls the switch circuit and the amplifier. By controlling with a signal, it is possible to switch between the case where the frequency characteristic of the output amplitude shows comb characteristics and the case where it does not show comb characteristics. Color signal processing device.