JPH05308657A - Chrominance signal processor - Google Patents

Abstract

PURPOSE:To provide the chrominance signal processor which can rationalize circuits and is easily made into an integrated circuit by sharing an inversion correcting circuit of the color array of a PAL system carrier chrominance signal for special reproducing and a conversion circuit from an NTSC system carrier chrominance signal to a PAL system carrier chrominance signal. CONSTITUTION:This chrominance signal processor is characterized by providing a switch circuit 6 which selects and outputs one of four input signals of the output signal from a first phase shifter 2, the output signal from a second phase shifter 3, the signal from an input terminal 1, and the output signal of a low pass filter 5 and switching this switch circuit 6 to perform the correction processing of the continuity of a generated color array at the time of special reproducing of a PAL system video signal and to convert an NTSC system video signal to a PAL system carrier chrominance signal at the time of reproducing of the NTSC system video signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color signal processing device in a VHS type video magnetic recording / reproducing device for recording / reproducing a color video signal.

[0002]

2. Description of the Related Art In recent years, high-quality video sources have been demanded with the increase in screen size of televisions. Also, due to the diversification of applications, high image quality is required even during special reproduction.
On the other hand, along with the borderless trend, there is an increasing need to support not only the broadcasting system of the home country but also various broadcasting systems.

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

The carrier color signal of the PAL system has its (RY) axis reversed every horizontal scanning period (hereinafter abbreviated as 1H).
In the special reproduction of the recording tape for a long time, the reversal of the (RY) axis may become discontinuous. Hereinafter, this state is referred to as color array inversion.

FIG. 2 is a block diagram of conventional video signal processing. In FIG. 2, reference numeral 13 is an input terminal, and the input signal is input to the luminance signal processing circuit 14 and the color signal processing circuit 15, respectively. Reference numeral 14 is a luminance signal processing circuit, 15 is a color signal processing circuit, 16 is a color array correction circuit for inverting and correcting the color signals from the color signal processing circuit 15, and 17 is the color signal processing circuit 1.
In the color signal from 5, the NTSC-PAL is used to convert the NTSC system carrier color signal to the PAL system carrier color signal.
A conversion circuit, 18 is a switch circuit, 19 is an adder for mixing the output of the luminance signal processing circuit 14 and the output of the switch circuit 18, and 20 is an output terminal.

As described above, conventionally, the color array correction circuit 16 and the NTSC-PAL conversion circuit 17 are separated and independent from each other.

The color array correction circuit 16 and the NTSC-P will be described below.
The AL conversion circuit 17 will be described in detail.

FIG. 3A is a block diagram of the color array correction circuit 16 in the reproduction system of the conventional VHS-PAL system color signal processing. If the color arrangement is reversed, the color demodulation circuit of the TV malfunctions and the color disappears. A case where the color array is inverted when the reproducing head moves to an adjacent track during special reproduction will be described. When a carrier color signal having an inverted color array is supplied to the input terminal 1, the control signal to the input terminal 12 causes the switch circuit 10 to change from a direct signal from the input terminal 1 to a signal from the 1H delay line 9 or 1H.
The continuity of the color array is corrected by switching the signal from the delay line 9 to the direct signal from the input terminal 1.

FIG. 3B shows a conventional VHS system color signal processing reproduction system in which the NTSC system carrier color signal is converted to PA.
NTSC-PAL conversion circuit 17 for L type carrier color signal
It is a block diagram of. NTSC input to input terminal 1
The carrier color signal of the method is divided into four. One is supplied to a terminal A of a switch circuit 6 having four inputs via a phase shifter 2 which delays the phase of the carrier color signal by 45 degrees. One is supplied to the terminal B of the switch circuit 6 via the phase shifter 3 which advances the phase of the carrier color signal by 45 degrees. One is directly supplied to the terminal C of the switch circuit 6. One is the (R
-Y) is fed to the balanced modulator 4 to invert the axis,
A low-pass filter (hereinafter L
It is supplied to the terminal D of the switch circuit 6 via the PF 5). These four signals are controlled by the control signal from the input terminal 7 so that the color burst signal during a certain period of 1H is at the terminal A.
, Select terminal C for all other cases, and then select 1H
The terminal B is selected during the period of the color burst signal in the middle, and the terminal D is selected at other times, so that the NTSC carrier color signal is set to P.
Converted to AL system carrier color signal.

[0010]

However, in the above configuration, the correction circuit for the inversion of the color array of the PAL system carrier color signal at the time of special reproduction and the NTSC system carrier color signal to the PAL system carrier color signal. However, there is a problem in that the circuit scale becomes large because a conversion circuit for converting into In addition, a 1H delay line is required, which makes it difficult to form an integrated circuit.

The present invention solves the above-mentioned problems, and a correction circuit for inverting the color array of a PAL system carrier color signal at the time of special reproduction and conversion from an NTSC system carrier color signal to a PAL system carrier color signal. It is an object of the present invention to provide a color signal processing device which can be rationalized by sharing a circuit and which can be easily integrated into a circuit.

[0012]

In order to achieve the above object, the present invention provides a first phase shifter that advances the phase of a carrier color signal by 45 degrees and a second phase shifter that delays the phase of a carrier color signal by 45 degrees. A phase shifter, a balanced modulator for inverting the phase of the (RY) axis of the carrier color signal, a low-pass filter for removing unnecessary components generated during balanced modulation, and a first phase shifter Of the output signal of, the output signal of the second phase shifter, the carrier color signal from the input terminal, and the output signal of the low-pass filter,
A switch circuit for selecting and outputting one signal from four input signals is provided, and the switch circuit is switched to correct the continuity of the color array that occurs during special reproduction of a PAL video signal. , A color signal processing device which performs a process of converting to a PAL system carrier color signal when reproducing an NTSC system video signal.

[0013]

According to the present invention, a circuit for correcting the continuity of the color array of the PAL system carrier color signal at the time of special reproduction and a conversion circuit for converting the NTSC system carrier color signal to the PAL system carrier color signal are constructed by the above construction. By sharing the circuit, it is possible to rationalize the circuit and provide a color signal processing device that can be easily integrated into a circuit.

[0014]

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

FIG. 1 is a circuit for correcting the discontinuity of the color array of a PAL system carrier color signal during special reproduction in one embodiment of the present invention and converting an NTSC system carrier color signal into a PAL system carrier color signal. It is a block diagram of a circuit. The carrier color signal input to the input terminal 1 is divided into four. One is supplied to the terminal A of the switch circuit 6 having four inputs via the phase shifter 2 which delays the phase of the carrier color signal by 45 degrees. One is a phase shifter 3 that advances the phase of the carrier color signal by 45 degrees.
And is supplied to the terminal B of the switch circuit 6. One is directly supplied to the terminal C of the switch circuit 6. One is supplied to the balanced modulator 4 to invert the (RY) axis of the carrier color signal, and is supplied to the terminal D of the switch circuit 6 via the LPF 5 to remove unnecessary components.

First, a case where the color array is reversed when the reproducing head moves to an adjacent track during special reproduction of the PAL-VHS system will be described. When a carrier color signal having an inverted color array is supplied to the input terminal 1, the control signal to the input terminal 7 causes the switch circuit 6 to change the direct signal from the input terminal 1 to the signal from the LPF 5 or the LPF 5.
The continuity of the color array is corrected by switching the signal from 5 to the direct signal from the input terminal 1.

Next, the case of reproducing an NTSC video signal will be described. The NTSC system carrier color signal input to the input terminal 1 is divided into four. One is supplied to a terminal A of a switch circuit 6 having four inputs via a phase shifter 2 which delays the phase of the carrier color signal by 45 degrees. One is supplied to the terminal B of the switch circuit 6 via the phase shifter 3 which advances the phase of the carrier color signal by 45 degrees. One is directly supplied to the terminal C of the switch circuit 6. One is (R-
The Y) axis is supplied to the balanced modulator 4 for inversion, and the switch circuit 6 is passed through the LPF 5 for removing unnecessary components.
Is supplied to the terminal D. These four signals are input terminal 7
, The terminal A is selected during the period of the color burst signal in 1H, the terminal C is selected in other periods, and the terminal B is selected during the period of the color burst signal in the next 1H. Other than NT by selecting terminal D
The SC carrier color signal can be converted into a PAL system carrier color signal.

As described above, according to the color signal processing apparatus of the embodiment of the present invention, the circuit for correcting the continuity of the color array of the PAL system carrier color signal in the special reproduction and the NTSC system carrier color signal to the PAL system are used. Can share the conversion circuit for the carrier color signal of
A 1H delay line is needed.

[0019]

As is apparent from the above embodiments, according to the present invention, the PAL-based carrier color signal continuity correction circuit and the PAL-based carrier color signal PAL system are used for special reproduction. It is possible to provide a color signal processing device in which the circuit can be rationalized by sharing the conversion circuit for converting the system to the carrier color signal and the integrated circuit can be easily performed.

[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 conventional video signal processing.

3A is a block diagram of a conventional color array discontinuity correction circuit, and FIG. 3B is a block diagram of a conventional NTSC-PAL conversion circuit.

[Explanation of symbols]

 1 Input Terminal 2-45 ° Phase Shifter 3 + 45 ° Phase Shifter 4 Balanced Modulator 5 LPF 6 Switch Circuit 7 Input Terminal 8 Output Terminal

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Hirotsugu Nakayama 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (1)

[Claims] 1. A color signal processing device for frequency-converting a carrier color signal into a low frequency band, recording the converted color signal, and inversely converting the reproduced color signal during reproduction, the first phase shifter advancing a phase of the carrier color signal by 45 degrees, and a carrier A second phase shifter that delays the phase of the color signal by 45 degrees, a balanced modulator that inverts the phase of the (RY) axis of the carrier color signal, and an unnecessary component that occurs during balanced modulation are removed. For a low pass filter, an output signal from the first phase shifter, an output signal from the second phase shifter, a carrier color signal from the input terminal, and an output signal of the low pass filter, A switch circuit for selecting and outputting one signal from four input signals is provided, and by switching the switch circuit, correction processing of the continuity of the color array that occurs during special reproduction of a PAL video signal is performed. Do and play NTSC video signals Color signal processing apparatus and performing processing for converting the carrier chrominance signal of the PAL system on.