JPS6336323A - Key input device - Google Patents

Abstract

PURPOSE:To exactly decide ON and OFF of a key switch by updating an output signal by a result of decision of ON and OFF of the key switch, in case of coincidence of a result of sense of two times, and updating the output signal by a result of sense of total three times, in case of discrepancy. CONSTITUTION:Two pulse signals such as key sense signal 6 are supplied to a key switch 3 from a key sense signal generating circuit 2. A deciding circuit 4 checks a sense result signal 7, and when the sense result signals 7 of two times coincide, an output signal 8 is updated in accordance with the sense result signal 7. Also, when the sense result signals 7 of two times are discrepant such as '0', '1' or '1', '0', the key sense signal 6 is generated once more, and the output signal 8 is updated by a decision of majority of the sense result signals of total three times. In such a way, there is no possibility that a wrong decision is executed by a malfunction due to noise, etc.

Description

[Detailed Description of the Invention] Industrial Field of Use The present invention is applicable to manual key systems such as keyboards, etc. It is related to.

The on/off status of a key switch in a conventional key manually operated device was determined by generating a sense signal only once.

Problems to be Solved by the Invention Conventionally, the on/off status of a key switch was determined based on a single sense result, which resulted in the problem that there was a high possibility of incorrect judgments being made due to malfunctions caused by noise, etc. Ta..

Means for Solving the Problems The present invention has been made to achieve the above objects.
Generate a sense signal twice to the key switch to perform key sensing, and if the two sensing results match -
The output signal is updated based on the key switch on/off determination result, and if the two sense results do not match, one more sense signal is generated, and the output signal is updated based on the three sense results in total. This feature is characterized in that a correct on/off determination of the key switch can be made.

Embodiment FIG. 1 is a block diagram showing an embodiment of the invention.
FIG. 2 is a diagram showing the operating waveforms, and FIG. 3 is a flowchart of the control process for determining whether the key switch is on or off.

In FIG. 1, 1 is a control circuit that controls the operation of the key human power device, 2 is a key sense signal generation circuit that generates the key sense signal 6 shown in FIG. 2, and 4 is a determination circuit that determines whether the key switch 3 is on or off. It is. Reference numeral 7 indicates a signal as a result of key sensing, 8 indicates an on/off output signal of the key switch 3 determined by the determination circuit 4, and 5 indicates a control key signal for controlling the operation of the key-powered device.

The flow of control processing for determining whether the key switch is on or off is as follows. Two pulse signals such as a key sense signal 6 are applied to the key switch 3 from the key sense signal generating circuit 2.

The determination circuit 4 checks one sense result signal 7, and if the two sense result signals 7 are -&, T, output signal 8? according to the sense result signal 7? :Update. In addition, if the two sense result signals 7 are "01", "1'", or "l", "0'J", which do not match, another key sense signal 6 is generated.
The output signal 8 is updated by majority vote of the sense result signals a total of three times.

This control process is summarized as shown in Table 1.

It is also possible to determine whether a plurality of key switches 3 are on or off by time-divisionally switching the key sense signal 6 and sense result signal 7 in Table 1. Furthermore, although the key sense signal 6 is a square wave, it is clear that a triangular wave or the like would have the same effect. Q: The key switch may be a non-contact switch.

Effects of the Invention As described above, according to the present invention, it is possible to provide a key-powered device that operates stably with simple control processing.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is an operation waveform diagram thereof, and FIG. 3 is a flowchart of control processing for determining whether a key switch is on or off. 1 is a control circuit, 2 is a key sense signal generation circuit, 3 is a key switch, 4 is a judgment circuit, 5 is a control signal, 6 is a key sense signal, 7 is a sense result signal, 8 is an output signal

Claims (1)

[Claims] A key sense signal generation circuit applies two pulse signals to a key switch, and when the two sense result signals match, the output signal is updated according to the sense result signal and the two sense results are output. A key input device comprising: a determination circuit that adds another key sense signal generated when the signals do not match, and updates the output signal according to the majority sense result signal among the three sense results.