JPS60126986A - Multi-system television receiver - Google Patents

Abstract

PURPOSE:To improve both the cross-color performance and the image resolution by cutting off a comb-line filter circuit with the PAL and SECAM systems to transmit the video signals through as they are and to secure the original performance and then actuating said filter circuit with an NTSC system. CONSTITUTION:The voltage higher than that of a system switching circuit 30 is delivered with an NTSC system and therefore a diode 29 is cut off. At the same time, differential amplifying transistors 18 and 19 constituting a comb-line filter circuit are actuated. A video signal containing only the luminance signal component is supplied from the emitter of an impedance converting transistor 24. While a video signal containing only the chroma signal component is supplied from the emitter of another impedance converting transistor 25. Both video signals are supplied to an NTSC band pass filter circuit 3. While the voltage lower than the circuit 30 is delivered in the case of a PAL or SECAM system. Thus the diode 29 is turned on with both transistors 18 and 19 turned off respectively. Thus the signals same as that supplied to the base of a transistor 11 are supplied from the emitters of transistors 24 and 25.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to the configuration of conventional systems such as NTSO, PAL, and SKOAM systems and their problems. Increasingly, standard television receivers are required. On the other hand, the NTSG system uses cross color and resolution.

The explanation will be given below with reference to all the drawings. FIG. 1 is a block diagram showing the configuration of a conventional multi-system television receiver.

The video signals input here are - one is the delay line 1. A luminance signal is taken out throughout the chroma trap circuit 5 and supplied to the video control circuit 6.

On the other hand, this video signal depends on each method.

Bandpass filter circuit 2 or N for PAL signals
Passes through bandpass filter circuit 3 for TSC signal, and P
The signal is supplied to the AL or NTSG chroma demodulation circuit 7.

Furthermore, the signal passes through a bell filter circuit 4 for the SKCAM signal on the other side and is supplied to the SE[AM chroma demodulation circuit 8.

The luminance signal that has passed through the video control circuit 6 and the chroma signal that has passed through the chroma demodulation circuit 7 or 8 depending on each system are mixed by a video amplifier circuit 9 and supplied to GRTlo.

Further, FIG. 2 is a circuit diagram of a conventional example of a comb-shaped filter circuit of a television receiver capable of receiving images only in the fiN T SC system.

Here, the input video signal passes through an impedance conversion transistor 11, and is supplied from its emitter to the collectors of v transistors 18 and 19 through a capacitor, 12, a resistor 14, and a resistor 15. On the other hand, the video signal applied from the emitter of transistor 11 to 1H delay line 13 via resistor 26 and capacitor 27 is delayed by one horizontal scanning period and is supplied to the bases of transistors 18 and 190 in opposite phases.

Thereupon, a video signal containing only the chroma signal component is generated at the collector of the transistor 18 by being mixed with the video signal supplied without delay, and is applied to the base of the impedance conversion transistor 26, and the N T S G buff )” ノ: , is supplied to the X filter circuit 3.

-1) A video signal containing only the luminance signal component is generated at the collector of the transistor 19, and is applied to the base of the impedance conversion transistor 24 and is supplied from its emitter to the delay line 1. When using the NTSC system, cross color and resolution are improved.

However, in the SICAM system, the chroma signal is FM modulated, so even if the above circuit is used, it is theoretically impossible to separate it into two video signals, one only for the chrominance signal component and the other only for the luminance signal component. In the PAL system, the interleaved position is different from the NT80 system, so N'l
'It is necessary to take a longer delay time for the video signal to be mixed than with the SG method (approximately 2 horizontal scanning periods). Therefore, in videos that include rapid color changes, discontinuity in color information components becomes noticeable and the screen returns. A significant drawback arises in that it becomes difficult to see.

Purpose of the Invention The present invention allows the NTSC system to pass through a comb-shaped filter circuit and takes advantage of its advantages, allowing PAL and 8m! :
The purpose of this invention is to provide a multi-system television receiver that can cut off this comb-shaped filter circuit in the case of the CAM system and allow the video signal to pass through as it is without passing through the comb-shaped filter circuit.

Structure of the Invention The multi-system television receiver according to the present invention has a differential amplifier to which a video signal delayed by one horizontal scanning period and having different phases is applied to each collector of the differential amplifier through a resistor. A comb-shaped filter circuit is constructed at each collector output terminal of the amplifier to take out a video signal containing only a luminance signal component and a video signal containing only a chroma signal component, and these are connected to each other through the emitter total resistance of the differential amplifier. In addition to connecting the point to ground via a diode, a switching circuit is installed at the base of the differential amplifier to operate as a differential amplifier in the case of the NTSC system, and to shut off the differential amplifier in the case of the PAL and SIIAM systems. It is connected.

When using the PAL and USE CAM systems, the conventional performance is maintained, and when using the NTSC system, it has the effect of improving cross color and resolution.

DESCRIPTION OF EMBODIMENTS A multi-system television receiver according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 3 shows a circuit diagram of a multi-system television receiver according to an embodiment of the present invention. In the figure, the same elements and circuits as in FIGS. 1 and 2 are given the same numbers.

Here, the diode 29 has its anode connected to the base of the transistor 18.19 through the resistor 16°17, and its cathode connected to the system switching circuit 30, and the diode 28 has its anode connected to the resistor 23 and its cathode connected to the base of the transistor 18.19. It is connected to ground.

In the case of the NTSC system, a high level voltage is output from the system switching circuit 30, so the diode 29 is cut off and the differential amplification transistor 1 constituting the comb filter circuit is switched off.
8 and 19 operate, the emitter of one impedance conversion transistor 24 supplies a video signal containing only a luminance signal component, and the emitter of the other impedance conversion transistor 25 supplies a video signal containing only a chroma signal component. +N'rsc bandpass filter circuit 3.

On the other hand, when using PAL or SECAM system.

Since a low level voltage is output from the system switching circuit 3o, the diode 29 is turned on, and the transistors 18 and 19 are turned on.
The same signal that was originally input to the base of transistor 11 is supplied from the emitters of transistor 24 and transistor 25 to cut off the transistor 2.
4, the luminance signal is transmitted through delay line 1 and PAL and SECAM chroma trap 6, and transistor 2.
The signal is supplied to a 5 to 14 PAL bandpass filter circuit 2 or a SECAM bell filter circuit 4.

Incidentally, the diode 28 is inserted so as to completely cut off the transistors 18 and 19 when using the PAL and SE [AM systems.

Effects of the Invention As described above, according to the present invention, when configuring a multi-system television receiver, in the case of PAL and SXCAM systems, the comb-shaped filter circuit is cut off and the video signal is passed through the frame, thereby achieving the original performance. - In the case of the NTSG system, the comb-shaped filter circuit is operated to improve cross color and resolution.

[Brief explanation of drawings]

Figure 1 is a block diagram of a conventional multi-system television receiver, Figure 2 is a circuit diagram of a comb-shaped filter circuit of a conventional television receiver that can only receive images in the NTSC system, and Figure 3 is a circuit diagram of the present invention. 1 is a circuit diagram of a multi-scheme television receiver in one embodiment; FIG. 1... Delay &, 2... PAL pantone filter 1M path, 3... NTSG pantone filter circuit, 4... SECAM bell filter circuit , 5... chroma trap circuit,
6...Video control circuit. 7...PAL and NTSC chroma demodulation circuit,
8...SICCAM chroma demodulation circuit, 9...
...Video amplifier circuit, 10...CRT, 11
．． 18.19°24.25...transistor,
12.27... Capacitor, 13...
1H daylay line, 14°16.16. ．． 17, 21
．． 22.23...Resistance. 28.29...Diode, 30...
Method switching circuit 0 Name of agent Patent attorney Toshio Nakao and 1 other person 1st
Figure 2 Figure 3 +β

Claims (1)

[Claims] A video signal with different phases delayed by one horizontal scanning period is applied to the base of the differential amplifier.Remove the resistors and add the video signal to each collector of the differential amplifier, and only the luminance signal component is applied to the output terminal of each collector of the differential amplifier. A comb-shaped filter circuit is configured to take out a video signal containing only chroma signal components and a video signal containing only chroma signal components, and the emitters of the differential amplifiers are connected to each other via a resistor, and this connection point is grounded via a diode. A multi-system television with a switching circuit connected to the base of the differential amplifier that operates as a differential amplifier in the case of the NTSO system and shuts off the differential amplifier in the case of the PAL and SICCAM systems. receiver.