JPH0246083A - Multicolor television receiver - Google Patents

Abstract

PURPOSE:To obtain the normal demodulation output of a chrominance signal inputted from an S-VHS terminal by cutting the chrominance signal of the other signal transmitting line when the chrominance signal from a prescribed signal source is loaded. CONSTITUTION:When a color picture from a VTR of S-VHS type is projected, a second input change-over switch 14 is switched to the S-VHS side, the chrominance signal from an S-VHS terminal 13 is loaded on a first signal transmitting line 5 of the same system and inputted to a first input terminal 9a of a multidecoder IC 9. At such a time, when a composite video signal of SECAM system is inputted to an AV input terminal 2, an input cut-off switch 15 is opened and an inhibiting circuit 16 operates, therefore, the chrominance signal from the AV input terminal 2 is not inputted to a second input terminal 9b of the multidecoder IC 9.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to a multicolor television receiver capable of demodulating color signals of various color television systems such as NTSC, PAL, and SECAM and projecting color images on a picture tube. It's about machines.

In general, in addition to the NTSC system used in Japan, color television systems include the PAL system and the SECAM system, and although each system is basically the same, there are some differences in the processing of the color signal. is occurring. Therefore, conventional multi-color television receivers are equipped with a multi-decoder that can demodulate color signals of any system, and demodulate the received color signals of each system to display a color image on the picture tube regardless of the system. We are making it possible to display the In addition, in addition to the color signals received by the antenna, such multicolor television receivers also receive various signals from external devices (such as VTRs, laser discs, video cameras, etc.) connected to external input terminals such as RF or AV. A color signal was supplied and similarly demodulated using a multi-decoder. Specifically, as such a multi-decoder, 2
PAL/NTSC and SECA from two signal transmission lines respectively
In order to provide M-system color signals, a multi-decoder IC is used that has an input terminal for receiving PAL/NTSC color signals and an input terminal for receiving SECAM-system color signals. The color signals obtained are demodulated by demodulation circuits provided corresponding to each system and output from a common output terminal through a common output line. At that time, for these signal transmission paths, the composite video signal received by the antenna and RF or AV
Any one of the composite video signals inputted from external input terminals such as the above is selectively inputted by the switch means, and each signal transmission path is provided with a method corresponding to each input terminal of the multi-decoder IC. A filter is provided that extracts and passes only the color signal, and the color signal from the antenna or external input terminal is passed through one of the signal transmission paths suitable for the system.

However, such conventional multicolor television receivers are not equipped with an external input terminal, that is, a 5-VH3 terminal, for receiving composite video signals from a 5-VHS type VTR. First, it was not possible to project color images from a 5-VHS type VTR onto a picture tube. Furthermore, if such a 5-VH3 terminal is provided, the PAL or NTSC color signal can be obtained from the 5-VH3 terminal separately from the video signal, so the color signal can simply be transmitted using the same method. If the signal transmission line is configured to be switched and input to the line by a switch means, the other signal transmission line will still be in a state of supplying the SECAM type color signal to the multi-decoder IC, and therefore both types of color signals will be input to the multi-decoder IC at the same time. 5-VH5
A problem has arisen in that a normal demodulated output of the color signal input from the terminal cannot be obtained.

The present invention has been made in view of the above points, and includes, for example, 5-
A new external input terminal, that is, the 5-VH3 terminal, is provided so that color signals from a VHS type VTR can be input manually, and the multi-decoder IC can output normal demodulated color signals input from the 5-VH3 terminal. An object of the present invention is to provide a multicolor television receiver that can be used in a variety of ways.

In order to solve the above-mentioned problems, the present invention is designed to provide color signals of different methods from a plurality of signal transmission lines, and demodulates the input color signals to obtain signals of each method. In a multi-color television receiver comprising a multi-decoder that outputs a color signal through a common output line, and means for placing the color signal on only one of the signal transmission lines, one of the signal transmission lines a switch means for loading a color signal of the same method from a predetermined signal source on the
and means for cutting off color signals from other signal transmission lines when a color signal from the predetermined signal source is carried.

Tatsuri: According to such a configuration, a multi-decoder IC is configured to receive PAL/NTSC and SECAM color signals from two signal transmission paths, respectively.
When the color signal from the 5-VH3 terminal is switched and inputted to the signal transmission line of the same system by the switch means, the color signal of the SECAM system from the other signal transmission line is cut off.

Forked U An embodiment of the present invention will be described below with reference to the drawings.

That is, (1) in the figure is the NTS received by the antenna.
The input terminal (2) is for inputting composite video signals (video signals and multicolor signals) of various formats such as C, PAL, and SECAM, for example, NTSC and PAL from external devices such as VTRs, laser discs, and video cameras.

AV input terminal to which the SECAM system composite video signal is input; (3) is the composite video signal received by the antenna and the AV
A first circuit that selectively supplies one of the composite video signals input from the input terminal (2) to the buffer transistor (4).
The manual changeover switches (5) and (6) are the first switch to which the composite video signal from the antenna or AV input terminal (2) is supplied from the buffer transistor (4). On the second signal transmission line, the first signal transmission line (5) detects chroma chia and switches the passband to either 3.58/4.43MH2 to extract and pass only the PAL/NTSC color signal. The second signal transmission line (6) is provided with a bell filter (8) that extracts and passes only the SECAM color signal. And (9) is the first. A multi-decoder IC having a first input terminal (9a) that receives PAL/NTSC color signals from the second signal transmission lines (5) and (6), and a second input terminal (9b) that receives SECAM color signals. The multi-decoder IC (9) demodulates the input color signals using demodulation circuits provided corresponding to each method and outputs them to common output terminals (9c) (9d).
From (9e), the common output line (10) (11) (
12). and,(
13) 5-VHS type VTR to PAL or N
The 5-VH3 terminal (14) is the 5-VH3 terminal where the TSC system composite video signal is input with the video signal and color signal separated.
a second manual changeover switch that switches and inputs the color signal input from the VH3 terminal (13) to the first signal transmission line (5) of the same type at a stage subsequent to the bandpass filter (7);
(15) is a normally closed type input cutoff switch provided on the second signal transmission line (6);
) is opened in conjunction with the second manual changeover switch (14) being switched to the 5-VH3 side. And (16) is the multi-decoder IC (9
) is a prohibition circuit connected to the control terminal (9f) of the device, and the prohibition circuit (16) is connected to the control terminal (9f) of the
When switched to the HS side, it is activated and puts the amplifier provided at the front stage of the demodulation circuit into a cut-off state, thereby cutting off the SECAM color signal input to the second input terminal (9b).

Therefore, if you want to display a color image from a 5-VHS type VTR, for example, the second manual selection switch (
14) to the 5-V)Is side, and the color signal from the 5-VH3 terminal (13) is connected to the first signal transmission line (5-V) of the same system.
) and the first input terminal (9) of the multi-decoder IC (9).
a). At this time, SE is connected to the AV input terminal (2).
When a CAM composite video signal is input, the first input selector switch (3) and buffer transistor (4)
The color signal of the SECAM system will be extracted from the bell filler (8) through the input cutoff switch (1).
5) is open and the inhibition circuit (16) is activated, the color signal from the AV input terminal (2) is transmitted to the multi-decoder I.
The multi-decoder IC (9) demodulates only the color signal from the 5-VH3 terminal (13), which is not input to the second input terminal (9b) of the C (9). , from its output terminals (9c) (9d) (9e) 5
A normal demodulated output of the color signal input from the -VH3 terminal (13) can be obtained. Here, connect the AV input terminal (
2) When a PAL or NTSC composite video signal is input, the second manual selector switch (14) is switched to the 5-VH3 side, so the 5-V
Only the color signal from the H3 terminal (13) is sent to the multi-decoder I.
There is no problem as it is input to C(9).

Although this embodiment describes the case where the input cutoff switch and the inhibition circuit are used together, it is also possible to use only one of them. In addition, in this example, 5-
The above describes the case where a PAL or NTSC composite video signal is obtained at the VH3 terminal with the video signal and color signal separated, but the SECAM format is assumed to be input after being converted to the PAL format. do. In addition, in this embodiment, the first. Although a case has been described in which the second manual changeover switch and the input cutoff switch are configured with mechanical switches, they may also be configured with electronic switches.

Furthermore, as described above, according to the present invention, for a multi-decoder that is configured to receive color signals of different systems from a plurality of signal transmission lines, it is possible to input color signals from the 5-VH3 terminal, for example. When input is enabled, the multi-decoder can reliably obtain a normal demodulated output of the color signal input from the 5-VH3 terminal.

[Brief explanation of the drawing]

The figure is a circuit diagram of a color signal processing system showing an embodiment of the present invention. (2) -=AV input terminal, (13)-...S-
VHS terminal. (15)---Input cutoff switch, (16)---Prohibition circuit. Embedded by applicant Sharp Co., Ltd.

Claims (1)

[Claims] (1) A multi-decoder that receives color signals of different methods from multiple signal transmission lines, demodulates the input color signals, and outputs the color signals of each method through a common output line. , in a multicolor television receiver having means for placing a color signal on only one of the signal transmission lines, for placing a color signal of the same type from a predetermined signal source on one of the signal transmission lines. 1. A multi-color television receiver, characterized in that it is provided with switch means, and means for cutting off color signals from other signal transmission lines when a color signal from the predetermined signal source is carried.