JPH11145805A - Switching circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a switching circuit, with which plural switches can be detected with a little ports without consuming any dedicated port, even in the case of a toggle switch. SOLUTION: When a user performs the switching operation of a mode changeover switch 11, a microcomputer 15 detects the execution of mode switching operation after detecting that a prescribed voltage different from the operating time of other switches S1-S4 is not longer inputted from a ladder circuit 14. Thus, even for case of the toggle switch, the operating states of plural switches can be detected with few number of ports without consuming dedicated ports.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a switch circuit, and more particularly to a switch circuit having a toggle switch.

[0002]

2. Description of the Related Art A conventional switch circuit has a toggle switch, an input circuit for outputting a high-level or low-level voltage according to the operation state of the toggle switch, and a voltage output from the input circuit. It consists of a microcomputer, and when switching each toggle switch,
A voltage output according to the operation state of the toggle switch is detected at one port.

[0003]

In the above-described conventional switch circuit, since the voltage corresponding to the operation state of the toggle switch is individually detected using one port, a plurality of ports are provided when the number of ports is limited. In some cases, the switch could not be detected.

[0004] The present invention has been made in view of the above problems, and provides a switch circuit capable of detecting a plurality of switches with a small number of ports without consuming a dedicated port even in the case of a toggle switch. Aim.

[0005]

According to a first aspect of the present invention, there is provided a toggle switch capable of maintaining a plurality of operation states and outputting different outputs corresponding to the respective operation states. A comparison circuit for inputting an output from the toggle switch to an input and outputting a mismatch result when different from the other input, and a switching circuit for turning on / off according to the mismatch result output from the comparison circuit And the switching circuit
The voltage divider circuit that outputs a voltage corresponding to the OFF state, and the voltage divider circuit determines whether or not the voltage value output from the voltage divider circuit corresponds to the toggle switch. And a control circuit for making the other input of the circuit correspond to the one input.

According to the first aspect of the present invention, when the output is changed by changing the operation state of the toggle switch, one input is different from the other input in the comparison circuit, and a mismatch result is output. . When the switching circuit is turned on / off according to the result of the mismatch, a corresponding voltage is output from the voltage dividing circuit. Then, it is determined whether or not this voltage value corresponds to the toggle switch, and if the voltage value corresponds, the other input of the comparison circuit corresponds to one input. Accordingly, the output of the mismatch result is stopped, and the voltage corresponding to the toggle switch is not output from the voltage dividing circuit. The control circuit detects a change in the operation state of the toggle switch when the output of the voltage is stopped.

The toggle switch is not limited to a toggle switch in a narrow sense, and may be any configuration that can maintain a plurality of operation states and perform different outputs corresponding to each operation state. And those that can be switched to three or more states. The comparison circuit only needs to be able to compare one input and the other input and output a mismatch result when they are different.
The one including the R circuit is included.

The switching circuit has only to be configured so as to be turned on / off in accordance with a mismatch result output from the comparison circuit. As an example of the configuration of the switching circuit, the invention according to claim 2 is the switch circuit according to claim 1, wherein the switching circuit generates a pulse based on a mismatch result output from the comparison circuit. At the same time, the switching element is turned on / off in response to the pulse.

According to the second aspect of the present invention, when a mismatch result is input from the comparison circuit, a pulse is generated based on the mismatch result, and the switching element is turned on / off in response to the pulse. Drive off.
As another example of the configuration according to the switching circuit,
The invention according to claim 3 is the above-described claim 1 or claim 2.
In the switch circuit according to any one of the above, the switching circuit is configured to input an external pulse and drive the switching element on and off in response to the external pulse.

According to the third aspect of the present invention, when a mismatch result is input from the comparison circuit, an external pulse is input based on the mismatch result, and the switching element is switched according to the external pulse. Drive on / off. That is, a pulse generation circuit is externally connected between the comparison circuit and the switching element, and a mismatch result is input from the comparison circuit to output a corresponding ON / OFF driving instruction to the switching element.

The voltage dividing circuit only needs to be able to output a voltage corresponding to the on / off state of the switching circuit. The voltage dividing circuit forms a current path with a plurality of switches and outputs a different voltage depending on the pressing state of each switch. And a ladder circuit. The above control circuit,
Determining whether the voltage value output from the voltage dividing circuit corresponds to the toggle switch and, if the voltage value corresponds to the voltage value, causing the other input in the comparing circuit to correspond to one input; Any configuration that can detect the pressed state of another switch disposed in the voltage dividing circuit or the like when the voltage value does not correspond to the toggle switch is included.

By the way, the toggle switch only needs to be able to perform different outputs according to the operation state, and includes a switch which outputs different voltages according to the operation state. As an example of the configuration in which different voltages are output from the toggle switch, the invention according to claim 4 is as follows.
In the switch circuit according to any one of claims 1 to 3, the toggle switch can maintain two operation states and outputs different voltages of a high level and a low level corresponding to each operation state. The comparison circuit inputs the voltage output from the toggle switch to one input and outputs a mismatch result when the voltage is different from the voltage value at the other input, and the control circuit outputs the mismatch result. The voltage value of the other input is inverted based on the result of the mismatch, and the voltage value of the other input is made to correspond to the voltage value of the one input.

In the invention according to claim 4 configured as described above, the toggle switch is set to one of two operation states and the corresponding one of the high level and the low level is applied to the voltage. When output, the same voltage is input to one input of the comparison circuit, and is compared with the voltage value at the other input. The comparison circuit outputs a mismatch result when the voltage values are different, and the control circuit inverts the voltage value of the other input based on the mismatch result to correspond to the voltage value of one input.

[0014]

As described above, the present invention can provide a switch circuit capable of detecting a plurality of switches with a small number of ports without consuming a dedicated port even in the case of a toggle switch. . Claim 2
According to the invention, a pulse can be generated based on the result of the mismatch from the comparison circuit, and the switching element can be turned on / off in accordance with the pulse. Further, according to the third aspect of the present invention, it is possible to eliminate the influence of the difference in the body of the pulse generation circuit on the driving of the switching element.

Further, according to the invention according to claim 4,
The operation state of the toggle switch can be detected using the two voltage values of the high level and the low level.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a mode switching device according to an embodiment of the present invention. The mode switching device 10 includes a mode switching switch 11 that is capable of mode switching and outputs a predetermined voltage based on a mode setting state, and two input terminals A and B, and a voltage input from both terminals A and B. Switch condition determination circuit 12 that outputs a mismatch signal when the values do not match
A switching circuit 13 for grounding a ladder circuit 14, which will be described later, when a pulse signal is output based on the input of a predetermined signal; A ladder circuit 14 for outputting signals; and a microcomputer 15 for detecting the operation state of each switch and changing the output voltage to the switch condition determination circuit 12 as necessary. Is controlled.

With this configuration, when the user switches the mode, a voltage corresponding to the set mode is input to the input terminal A of the switch condition determination circuit 12. Then, the switch condition determination circuit 12 determines that this voltage is different from the voltage value at the input terminal B, and outputs a mismatch signal. When the switching circuit 13 outputs a pulse signal based on the input of the mismatch signal, the switching circuit 13 grounds the ladder circuit 14 and the ladder circuit 14
Output a predetermined voltage. The microcomputer 15 changes the output voltage to the input terminal B in the switch condition determination circuit 12 based on the predetermined voltage so as to match the voltage value at the input terminal A. The microcomputer 15 detects that the output of the mismatch signal from the switch condition determination circuit 12 is stopped and the ladder circuit 14 no longer outputs the voltage of the predetermined value, and detects that the mode has been switched. .

The mode change switch 11 includes a toggle switch that can switch between two types of modes, and a PAL / NTS
C mode switching is performed, and in the PAL mode, a voltage “H” is output to the switch condition determination circuit 12, and NTSC
In the mode, the voltage “L” is set to the switch condition determination circuit 1
Output to 2. As described above, since the toggle switch is used, there is no need to provide an LED and indicate the switching state by lighting the LED as in the case of using the tact switch.

The switch condition judging circuit 12 includes two input terminals A and B and one output terminal, and is constituted by an XOR circuit formed by an arrangement of transistors, diodes, and the like. Output a mismatch signal via the output terminal when the voltage values to be output are different,
When the voltage values match, the output of the mismatch signal is stopped. The switching circuit 13 includes a frequency dividing circuit 13a for dividing a clock signal input from an external circuit (not shown) when a predetermined signal is input and outputting a pulse signal, and a ladder circuit 14 when the pulse signal is input. And a switch S5 for grounding a terminal connected to the ladder circuit 14. When the mismatch signal is input, the clock signal is frequency-divided and a predetermined pulse signal is output to ground the ladder circuit 14.

The switching circuit 13 is constructed by incorporating a frequency dividing circuit 13a. As shown in FIG. 2, an external oscillator 16 is connected between the switch condition judging circuit 12 and the ladder circuit 14. When the clock signal is frequency-divided and the predetermined pulse signal is output to the switch S5 to ground the ladder circuit 14 when the non-coincidence signal is input, the ladder circuit 14 is not affected by the body difference of the frequency-division circuit 13a A pulse signal can be output reliably.

The ladder circuit 14 is provided with switches S1 to S4 for grounding at various points by a pressing operation, and a power supply terminal 14a for supplying power. Output. The microcomputer 15 has an input terminal B in the switch condition determination circuit 12.
And the switches S1 to S
5 is detected. Here, a procedure when the microcomputer 15 detects a switching operation of the mode switch 11 will be described with reference to FIG. It is assumed that the output voltage until this switching operation is performed is “H”.

Ladder circuit 14 via A / D input port
When a change in the voltage input from is detected (step S1)
00), it is confirmed that the input voltage is obtained by operating the switch S5 (step S110). Then
Since the current output voltage is "H", the voltage is changed to "L" and output to the switch condition determination circuit 12 (steps S120, S130). When the input voltage from the ladder circuit 14 changes to another voltage value in response to the change in the output voltage (step S150), it is detected that the mode changeover switch 11 has been switched (step S1).
60).

The frequency dividing circuit 13a includes the microcomputer 1
The clock signal is divided so that the pulse width per operation is about 2 ms so that the switch 5 can detect the switching operation of the switch S5, and the detection of the pressing operation of the other switches S1 to S4 is not hindered. 200
The pulse signal is output at an interval of about 500 ms. Accordingly, the mode changeover switch 11 that can switch between two modes and outputs the voltages “H” and “L” corresponding to each switching state constitutes a toggle switch in this sense, and has two input terminals. The switch condition determination circuit 12 that outputs a mismatch signal via an output terminal when the input voltage values are different constitutes a comparison circuit in this sense.

A ladder circuit 1 for outputting a voltage obtained by dividing a ladder resistance in accordance with the operation states of the switches S1 to S5.
4 constitutes a voltage dividing circuit in this sense. Further, it is determined whether or not the input voltage input from the ladder circuit 14 is due to the switch S5. If the input voltage is applicable, the output voltage to the switch condition determination circuit 12 is output from the mode switch 11. The microcomputer 15 that matches the voltage to be used constitutes a control circuit in this sense.

Mode switch 1 according to this embodiment
1 includes a toggle switch capable of switching between two types of modes, and a switch condition determination circuit 12 detects which of two types of input voltages corresponding to each mode is input from each input terminal. Although the mismatch signal is output when the voltages input from both input terminals do not match, the apparatus includes a mode changeover switch capable of switching to at least a plurality of modes, and determines a voltage corresponding to each mode in a switch condition determination. It suffices if the circuit can detect and determine whether the voltage values match, and the number of switchable modes and the number of corresponding voltage values are not limited.

A case in which a toggle switch capable of switching between three modes is provided will be described with reference to FIG. According to FIG.
A toggle switch capable of switching between three types of modes is provided, and outputs voltages “H”, “M”, and “L” corresponding to each mode according to the mode switching state. The switch condition determination circuit 22 is composed of a comparator having two input terminals and one output terminal, as in the case described above. When the voltage values input from both input terminals are different, the switch condition determination circuit 22 does not match via the output terminals. A signal is output, and when the voltage values match, the output of the mismatch signal is stopped. That is, it detects whether any of the three types of voltages “H”, “M”, and “L” is input from both input terminals, and controls the output of the mismatch signal.

The microcomputer 23 includes a switch condition determination circuit 2
2 is connected between the input terminal B and the ladder circuit 14 to detect the operation state of each switch. Here, when the mode changeover switch 21 switches to the mode corresponding to the voltage “L”, the microcomputer 23 sets the mode changeover switch 2
The procedure for detecting the first switching operation will be described with reference to FIG. The output voltage until this switching operation is performed is assumed to be “H” as in the case described above.

Ladder circuit 14 via A / D input port
When a change in the voltage input from is detected (step S2)
00), it is confirmed that the input voltage is obtained by operating the switch S5 (step S210). Then
Since the current output voltage is "H", the voltage is changed to "M" and output to the switch condition determination circuit 22 (steps S220, S230). At this time, since the voltage input to the switch condition determination circuit 22 does not match between “L” and “M”, the input voltage is not changed by operating the switch S5 and the voltage value does not change (step S26).
0). Then, when the output voltage is changed to "L" (step S240), the voltage input to the switch condition determination circuit 22 matches "L" and "L", and this input voltage changes to another voltage value ( Step S260). Then, the microcomputer 23 detects that the mode switch 21 has been switched (step S270).

In this case, the mode can be switched to three types of modes, and the voltages “H”, “M”,
The mode switch 21 that outputs “L” constitutes a toggle switch in this sense. As in the case described above, the switch condition determination circuit 22 that outputs a mismatch signal via the output terminal when the voltage values input from the two input terminals are different constitutes a comparison circuit in this sense. Further, it is determined whether or not the input voltage input from the ladder circuit 14 is due to the switch S5, and if the input voltage is applicable, the switch condition determination circuit 22
The microcomputer 23 that matches the output voltage of the microcomputer with the voltage output from the mode changeover switch 21 constitutes a control circuit in this sense.

Next, the operation of the mode switching device according to this embodiment will be described. When the user switches the mode switch 11 from the PAL mode to the NTSC mode, the voltage “H” that has been output to the switch condition determination circuit 12 is changed to “L”. Then, before performing this switching operation, both input terminals A,
Although the voltage “H” was input to B, since the input terminal A of the mode change switch 11 was changed to the voltage “L”,
The switch condition determination circuit 12 detects the mismatch of the input voltages and outputs a mismatch signal.

When this mismatch signal is input to the switching circuit 13, the switching circuit 13 divides the clock signal and outputs a predetermined pulse signal, grounds the ladder circuit 14, and outputs a predetermined voltage from the ladder circuit 14. Output. When detecting a change in the voltage input from the ladder circuit 14 via the A / D input port (step S100), the microcomputer 15 checks whether or not the input voltage is caused by the operation of the switch S5 (step S11).
0). When the input voltage is the input voltage obtained by operating the switch S5, the current output voltage is “H”, and the voltage is set to “L”.
And outputs it to the switch condition determination circuit 12 (steps S120 and S130). Then, both the input voltages to the switch condition determination circuit 12 become “H”, and the output of the mismatch signal is stopped. Therefore, the switch S5 is turned off, and the input voltage from the ladder circuit 14 changes to another value (step S150). The microcomputer 15 detects the change in the voltage value to detect that the mode changeover switch 11 has been switched (step S1).
60).

On the other hand, if the voltage input from the ladder circuit 14 is due to an operation other than the operation of the switch S5, it is detected which of the switches S1 to S4 is operated according to the voltage value of the input voltage ( Step S17
0). When detecting the operation of each switch, the microcomputer 15 outputs a predetermined signal to various control circuits (not shown) in order to perform an operation corresponding to each switch. in this way,
When the user performs the switching operation of the mode switching switch 11, the microcomputer 15 detects that the predetermined voltage different from that at the time of operating the other switches S1 to S4 is no longer input from the ladder circuit 14, and the mode switching operation is performed. In order to detect that there is, even in the case of a toggle switch, the operation state of a plurality of switches can be detected with a small number of ports without consuming a dedicated port.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a mode switching device according to an embodiment.

FIG. 2 is a block diagram showing a configuration when an external oscillator is applied.

FIG. 3 is a flowchart illustrating a procedure for detecting an operation state of each switch.

FIG. 4 is a block diagram illustrating a configuration of a mode switching device according to a modification.

FIG. 5 is a flowchart illustrating a procedure for detecting an operation state of each switch.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Mode switching device 11 ... Mode changeover switch 12 ... Switch condition judgment circuit 13 ... Switching circuit 13a ... Divider circuit 14 ... Ladder circuit 14a ... Power supply terminal 15 ... Microcomputer S1-S5 ... Switch

Claims (4)

[Claims] 1. A toggle switch capable of maintaining a plurality of operation states and outputting different outputs corresponding to the respective operation states, an output from the toggle switch being input to one input and being compared with the other input. A comparison circuit that outputs a mismatch result when they are different from each other; and an on / off switch according to the mismatch result output from the comparison circuit.
A switching circuit for turning off, a voltage dividing circuit for outputting a voltage corresponding to ON / OFF of the switching circuit, and determining whether a voltage value output from the voltage dividing circuit corresponds to the toggle switch. A switch circuit comprising: a control circuit that causes the other input of the comparison circuit to correspond to the one input when the voltage values correspond to each other. 2. The switch circuit according to claim 1, wherein the switching circuit generates a pulse based on a mismatch result output from the comparison circuit, and turns a switching element on and off in response to the pulse. A switch circuit characterized by being driven. 3. The switch circuit according to claim 1, wherein the switching circuit inputs an external pulse and drives a switching element on and off in response to the external pulse. A switch circuit characterized by the above-mentioned. 4. The switch circuit according to claim 1, wherein said toggle switch is capable of maintaining two operation states and has a high level and a low level corresponding to each operation state. A different voltage is output, the comparison circuit inputs the voltage output from the toggle switch to one input, and outputs a mismatch result when the voltage is different from the voltage value at the other input. A switch circuit for inverting a voltage value of the other input based on a mismatch result output from a comparison circuit to correspond to a voltage value of one input.