JPH0487479A - Input changeover circuit for television receiver - Google Patents

Abstract

PURPOSE:To surely and easily implement various operation control such as picture quality control by applying different DC voltages to each input terminal of plural input changeover ICs and selecting any of the voltages with a switching signal of a microcomputer. CONSTITUTION:While each of a video signal, an audio left signal, an audio right signal, a Y signal and a C signal is inputted to each signal input terminal of input changeover ICs 1, 2, 3, a switching signal Cx is given to each of the input changeover ICs 1, 2, 3 by a microcomputer 4 to select and output an input signal. Simultaneously, a DC voltage is fed to an idle terminal via resistors 6, 7, 8, 9, an input is selected by the switching signal Cx from the microcomputer 4 and a DC voltage corresponding to the input DC voltage is outputted to each output, the output DC voltage is compared with a reference voltage at a voltage comparator circuit 10 and a required voltage, that is, a switch signal Sw is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an input switching circuit for a television receiver that switches various signals such as video and audio signals.

[Prior Art] Fig. 4 shows a configuration diagram of an input switching circuit of a conventional television receiver.
) are input switching ICs that switch input signals.
1 (4) is a microcomputer, and each of the above input switching ICs (1)
, (2), and (3) are provided with a switching signal Cx. (5
) is a logic circuit which obtains a switch signal Sw for performing image quality control and other switching operations, for example, according to an input signal from a switching signal Cx given by the microcomputer (4).

Next, the operation of the above configuration will be explained.

Video/audio (left and right), luminance (hereinafter referred to as Y), and chroma (hereinafter referred to as C) signals are input to each signal input terminal of input switching IC (1), (2), and (3). In this state, each input switch I is controlled by the microcomputer (4).
By applying a switching signal Cx to C(1), (2), and (3), the above-mentioned input signal is selected and output. Here, for example, you can control the image quality when a TV signal consisting of video and audio is selected and output, turn off the TV signal when Y or C@ is selected and output, or perform other switching operations. To obtain a switch signal for performing this, a predetermined switch signal is obtained by inputting the switching signal Cx outputted from the microcomputer (0) to the logic circuit (5).

Further, when the switching signal Cx is serial data, a dedicated output port is provided in the microcomputer (0), and the switch signal is output from there.

[Problems to be Solved by the Invention] Since the input switching circuit of a conventional television receiver is configured as described above, it is necessary to separately provide a complicated logic circuit in order to obtain a switch signal. As the number of switching signal lines increases, the number of switching signal lines also increases, resulting in a problem that the configuration of the logic circuit becomes more complicated.

Also, if the switching signal is a serial data I'''C bus, etc., it is necessary to provide a dedicated output port on the microcontroller.
The configuration becomes increasingly complex.

This invention was made to solve the above-mentioned problems, and allows a predetermined switch signal to be output without the need for a logic circuit or a dedicated output port when the switch signal is serial data. The present invention aims to provide an input switching circuit for a television receiver that can be obtained.

[Means for Solving the Problems] The input switching circuit for a television receiver according to the present invention includes:
The present invention is characterized in that a DC voltage is applied to each input terminal of a plurality of input switching ICs, and a switch signal for external switching operation is created based on the difference in the DC voltage.

[Function] According to the present invention, by setting the DC voltages applied to each input terminal of a plurality of input switching ICs to different values, the input is selected by the switching signal of the microcomputer.
A DC voltage corresponding to each input DC voltage is output, and a predetermined switch signal can be obtained.

[Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be described based on the drawings.

FIG. 1 shows a configuration diagram of an input switching circuit of a television receiver according to an embodiment of the present invention, in which (1)
~(0 is the same as the conventional example shown in FIG. 4, so detailed explanation thereof will be omitted.

In Figure 1, (8), (7), (8),
(9) is input 1. lJm I C(+), +2)
, (3) No Sora? ! A resistor (10) is a voltage comparison circuit for obtaining an external switching operation switch signal Sv from the output DC voltage.

Next, the operation of the above configuration will be explained.
While the video/audio (left and right), Y, and C signals are being manually input to the signal input terminals C+1), (2), and +3), the microcomputer (4) switches each input
By applying the switching signal Cx to C(+), (Z), and (3), the above-mentioned human input signal is selected and output.

At the same time, the resistances (6), (7), (8), (
9), a DC voltage is applied to the vacant terminal, the input is selected by the switching signal Cx from the microcomputer (4), and a DC voltage corresponding to the human input DC voltage is output to each output, and this output DC voltage is A comparator circuit (10) compares it with a reference voltage to obtain a necessary voltage, that is, a switch signal Sw.

FIG. 2 shows a configuration diagram of an input switching circuit of a television receiver according to another embodiment of the present invention.
The difference from the embodiment shown in the figure is that the manual switching IC(1), (
2) and (3) are used as terminals to apply DC voltage via resistors (8), (7), (8), and (9), rather than empty terminals.
The only difference is that the signal input terminal is shared, and the other configurations and operations are the same as those in FIG. 1, so their explanation will be omitted.

In each of the above embodiments, the case where the switching signal Cx is two signals, low and high, has been explained, but the switching signal is I''
The same applies to serial data Cxt such as C bus, and input switching IC (1), (2
), (3) can also be used to switch input switching ICs that do not support serial data. FIG. 3 is a configuration diagram showing a specific example thereof,
In the same figure, (1), (2), (3), and (11) are 3 systems with 4 manual inputs that support serial data, and input switching IC1 (12) with 3 systems and 3 outputs is 3 systems that do not support serial data. 2-person power, 3-system l-output input switching IC, AV
The input selection IC (
2) output DC voltage is different, input switching IC (12)
This is to create the input switching voltage.

[Effects of the Invention] As described above, according to the present invention, a plurality of input switching ICs
By applying different DC voltages to each input terminal of the controller and selecting them using the microcontroller's switching signal, it is possible to generate the output DC voltage corresponding to each input DC voltage, that is, the predetermined switch signal, without using a logic circuit. you can get
Various operational controls such as image quality control can be performed reliably and easily. Further, even when the switching signal is serial data, there is no need to provide a dedicated output port in the microcomputer, and a predetermined switching signal can be obtained with a simple configuration.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an input switching circuit for a television receiver according to one embodiment of the present invention, FIGS. 2 and 3 are block diagrams showing other embodiments of the present invention, and FIG. 4 is a conventional example. FIG. (1), (2), (3) (11), (12)...Input switching IC, (4)...Microcomputer, (8), (7), (
8), (9)...Resistor, (lO)...Voltage comparison circuit. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] (1) A plurality of input switching ICs, a microcomputer that provides switching signals to these input switching ICs, means for applying DC voltage to the input terminals of each input switching IC, and a switch for external switching operation from the output DC voltage. 1. An input switching circuit for a television receiver, comprising: means for creating a signal.