JPH0416554Y2 - - Google Patents

Description

[Detailed description of the invention] (a) Industrial application field The present invention relates to a signal switching circuit that prohibits driving of an electronic device with one signal when the other signal is used to drive the electronic device. It is something.

(b) Conventional technology As a conventional signal switching circuit, for example,
No. 164380 was proposed, in which a two-contact changeover switch was used to switch a predetermined signal.

FIG. 2 is a block diagram showing a conventional signal switching circuit using the two-contact switching switch.
are input terminals into which one and the other signals are respectively input, and 3 has its a terminal connected to the input terminal 1, and its b terminal connected to the input terminal 2, and the a and b terminals are connected by a switching signal. 4 is a two-contact changeover switch that can be switched to either one of the two
This is an electronic device that is driven by one or the other signal output from the contact changeover switch 3.

(c) Problems to be solved by the invention However, in the above case, since chattering occurs when the two-contact changeover switch 3 is switched,
If the electronic device 4 malfunctions or a no-signal state occurs during switching to either terminal a or b of the two-contact changeover switch 3, the electronic device 4 may momentarily receive either one or the other signal. There were problems such as the device not being driven even when it was turned.

(d) Means for solving the problem The present invention was made to solve the above problem, and includes first and second transmitters, and the first transmitter.
A first switching signal is output when a signal from a transmitter is input, and a second switching signal different from the first switching signal is output in a no-signal state when a signal from the first transmitter is not input. a control unit that receives the first switching signal and prohibits signal input by the second transmitter and enables output of the signal by the first transmitter, and the second switching signal It consists of an AND circuit that can output a signal from the second transmitter upon input, and an electronic device is activated by one of the signals from the first and second transmitters output from the AND circuit. It is something to control.

(e) Effect According to the present invention, when the first switching signal is output from the control section, the AND circuit enables the electronic device to be driven by the first signal, and the electronic device can be driven by the second signal. When driving of the device is prohibited and the second switching signal is output from the control section, the AND circuit enables the electronic device to be driven by the second signal.

(f) Examples The details of the present invention will be explained in detail with reference to illustrated examples.

Figure 1 shows the present invention in AV (audio visual) format.
5 is a circuit block diagram showing an embodiment when used in a device, and 5 has a switch 6 interposed between the c terminal and the ground, and a high level (hereinafter referred to as "H") or a low level is output from the c terminal. level (hereinafter referred to as “L”)
AV system control that outputs a signal (referred to as ) and outputs a control signal from its d terminal;
Reference numerals 7 and 8 denote an audio device and a television receiver, respectively, which transmit and receive signals between the AV system control 5, 9 a power supply terminal to which a power supply voltage is applied, 10 a power line, and 11 a power line 1.
A resistor is connected between the 0 and c terminals, 12 is a NAND circuit whose both input terminals are connected to the c terminal, 1
3 is a NAND circuit whose one input terminal is connected to the c terminal and the other input terminal is connected to the amplifier 15, and 14 is whose one input terminal is connected to the d terminal.
terminal, and the other input terminal was connected to the output terminal of the NAND circuit 12.
NAND circuit, 16 has one input terminal as above
The NAND circuit is connected to the output terminal of the NAND circuit 13 and the other input terminal is connected to the output terminal of the NAND circuit 14,
An AND circuit is constituted by NAND circuits 12, 13, 14, and 16, 17 is a decoding circuit for decoding the output of the NAND circuit 16, and 18 is the decoding circuit 17.
19 is a system control to which the output of the decoding circuit 17 is input; 20 is the configuration of a video tape recorder as an electronic device; 20 is the video tape recorder; A remote control transmitter for AV as a first transmitter capable of driving an audio device 7 and a television receiver 8;
Reference numeral 1 designates a remote control transmitter as a second transmitter capable of driving only the video tape recorder.

When a signal is output from the remote control transmitter 20 to drive the video tape recorder, the switch 6 of the AV system control 5 is closed and an "L" signal as the first switching signal is output from the c terminal. At the same time, a control signal corresponding to the signal from the remote control transmitter 20 is output from the d terminal, and an "H" signal is output from the NAND circuits 12 and 13 in response to this signal.

Then, the control signal is input to one input terminal of the NAND circuit 14, and the control signal is input to the other input terminal.
Since the "H" signal output from the NAND circuit 12 is input, an inverted signal of the control signal is output from the NAND circuit 14, and the NAND circuit 1
Since the "H" signal output from the NAND circuit 13 is input to one input terminal of 6, and the inverted signal is input to the other input terminal,
The inversion of the inverted signal from the NAND circuit 16, that is, d
The same signal as the control signal output from the terminal is output.

From this, the signal is decoded by the decoding circuit 17,
The timer circuit 18 and the system control 19 operate based on the decoded output.

When a signal is output from the remote control transmitter 21 to drive the video tape recorder, since no signal is output from the remote control transmitter 20, the switch 6 of the AV system control 5 is opened and the second An "H" signal as a switching signal is output, and the d terminal is in a no-signal state in which no signal is output. In response to this signal, an "L" signal is output from the NAND circuit 12, and an "H" signal is input to one input terminal of the NAND circuit 13, and a remote signal amplified by the amplifier 15 is input to the other input terminal. Since the signal from the control transmitter 21 is input, the inverted signal of the output of the amplifier 15 is output from the NAND circuit 13. And NAND circuit 14
Since the "L" signal is input to the other input terminal of the NAND circuit 14, the "H" signal is output from the NAND circuit 14, and the inverted signal of the output of the amplifier 15 is input to one input terminal of the NAND circuit 16. At the same time, since an "H" signal is input to the other input terminal, the inversion of the inverted signal from the NAND circuit 16,
That is, the same signal is output from the remote control transmitter 21 that has been amplified by the amplifier 15.

From this, the signal is decoded by the decoding circuit 17,
The timer circuit 18 and the system control 19 operate based on the decoded output.

As described above, only when the video tape recorder is driven by the signal from the remote control transmitter 20, driving the video tape recorder by the signal from the remote control transmitter 21 is prohibited.

(G) Effect of the invention According to the signal switching circuit of the invention, the first and second
Since an AND circuit is used to switch the signal output from the transmitter, the chattering and no-signal state that occur with two-contact switches can be prevented, and it can also be configured using general-purpose ICs, reducing costs. The effect of

[Brief explanation of the drawing]

FIG. 1 is a circuit block diagram showing one embodiment of the signal switching circuit of the present invention, and FIG. 2 is a block diagram showing a conventional signal switching circuit. 5...AV system control, 12,1
3, 14, 16...NAND circuit, 20, 21...
...remote control transmitter.

Claims (1)

[Scope of utility model registration request] first and second transmitters, and the first transmitter outputs a first switching signal when the signal of the first transmitter is input, and in a no-signal state where the signal of the first transmitter is not input. a control unit configured to output a second switching signal different from the first switching signal; the first and second signals outputted from the AND circuit; A signal switching circuit characterized in that an electronic device is controlled by one of the signals from a transmitter.