JPS63119116A - Input circuit - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] (Field of Application of P7 Industry) The invention is not invented in input circuits using switches in general electronic equipment.

[Conventional technology]

Input circuits using mechanical contact type switches are very often used, and the general circuit is switch 2 as shown in Figure 3.
0 and a resistor 2 connected to L in series with the switch and the power supply.
Consists of 1. If the switch is pressed and turned off, the output will be I-
11G I-1, and the return deviation causes the contact to close and the output to become LOW, and the output is used for various controls.

[The problem that the invention attempts to solve]

However, in the input circuit described above, when the switch is closed, current always flows through the series resistor, which wastes power. ” There was a limit to the two resistance values. The reason is that the current that flows between the contacts each time the switch is turned on or off has a cleaning effect, and if the series resistance is increased too much to reduce the current, the cleaning effect will be lost. As a result, one of the switches
．． (Since this would have an adverse effect on the period reliability, an object of the present invention is to be able to increase the value of the series resistance without impairing the cleaning effect.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention is characterized by the addition of means for detecting the on/off operation of the switch and thereafter lowering the value of the first row resistor for a certain period of time.

[April 1] The present invention increases the current flowing through the switch when the switch is turned off and off by the action of the means described in 1 above, and only a small amount of current flows through the switch when the switch is in a steady state.

〔Example〕

The present invention will be described in detail below based on Examples. FIG. 1 is a circuit diagram of an input circuit according to an embodiment of the present invention.

A switch 1 and a series resistor 2 constitute an input circuit consisting of a switch 111j, and since the series resistor 2 has a high resistance, only a small current flows. When the switch is turned off, the exclusive OR gate 8 input to the integrator circuit of the resistor 6 and capacitor 7 performs a differential operation, and a pulse is sent to the mono-multi-by-break 11 in the next stage. Output. During a time determined by the constants of resistor 9 and capacitor 10, the output of 11 generates a pulse at the LO\A7 level, causing transistor 4 to conduct through base resistor 5. 4 conducts, resistor 3 is connected in parallel to resistor 2 in series, and k>
't, the series resistance of the switch decreases, and the current flowing through switch 1 increases. Figure 2 is the first
The timing chart diagram for explaining the operation shown in the figure shows the relationship between the output of the input circuit, the output 13 of the gate 8, and the output C of the mono-multi-by-break 11. Does the output A have chattering? The waveform I3 has chattering removed, and it is also possible to use this as the output pulse of the input circuit. fμ upper and lower rows I indicate the level of current flowing through the switch, and it is at a high level when the switch is on or off, or it is a period when the switch is constantly conducting (a period when it is at A, LO, or V level). ) is a minute current value. The application of the present invention is very wide.To give an example, let us take, as an example, various input circuits mainly for disk detection of floppy disks, which require low current consumption during standby. Further, the embodiments shown in FIGS. 1 and 2 can be constructed using a monomulti, or a timer section can be constructed by counting clocks, and the entire circuit can be integrated into an IC.

〔Effect of the invention〕

As explained above, the input circuit of the present invention eliminates the quenching effect when the switch is in steady state without impairing the switch cleaning effect at all.
It is possible to reduce the It current to a medium level. There is a strong demand for low power consumption in electronic A devices, such as battery operation, and even if a large number of switches are used, there is no need to waste current around the switches, which is a big effect.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of an input circuit according to an embodiment of the present invention, FIG. 2 is a timing chart showing the operation of FIG. 1, and FIG. 3 is a circuit diagram of a conventional input circuit. 1.20...Switch, ]1...Mono multi-by-break. Figure 1 Figure 2

Claims (1)

[Claims] In an input circuit consisting of a switch having a mechanical contact and a series resistor connected to the switch, the output is a connection point between the switch and the series resistor, and a detection circuit detects a change in the switch output; An input circuit comprising: a signal generating circuit that generates a signal for a certain period of time; and a resistance value lowering means that lowers the value of the series resistor using the output of the signal generating means.