JPH0477111A - Chattering noise absorption circuit - Google Patents

Abstract

PURPOSE:To stably absorb noises even when any kind of chattering noise is generated in time width by absorbing the noises in constant time width instead of deciding time constant and hysteresis width while estimating the noise components in a certain range to absorb the noises. CONSTITUTION:When inputting an input signal (IN) including the chattering noise, a multivibrator 1 starts at the rising, and outputs the pulse signal (signal 'b') of time width T 1. On the other hand, a reversing circuit 3 outputs a logical value reversing signal (signal (a)) of the input signal (IN). A multivivibrator 2 starts at the rising of the signal (b,) only when the signal 5a) is low level, and outputs the pulse signal of time width T2 (output signal OUT). In short, the chattering noise can be eliminated by the multivibrator 1, and the pulse signal of required time width is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a chattering noise absorption circuit that removes chattering components from a pulse signal containing chattering noise.

[Conventional technology]

A conventional chattering noise absorption circuit of this type is composed of a time constant circuit and a hysteresis circuit. FIG. 3 is a circuit diagram illustrating a conventional circuit, and FIG. 4 is a signal timing diagram for explaining the operation of the circuit shown in FIG. When an input signal (IN) containing chattering noise is input, it passes through a time constant circuit of a resistor R and a capacitor C, has high frequency components removed, and is input to the hysteresis circuit 4.

Since the steresis circuit 4 has hysteresis in its input/output characteristics, it does not respond to chattering noise below a certain level, and an output signal (OUT) free of chattering components can be obtained.

[Problem to be solved by the invention]

This conventional chattering noise absorption circuit absorbs noise by setting the time constant and hysteresis width assuming noise components within a certain range, so if abnormal noise outside the expected range occurs, it cannot be absorbed completely. The problem is that it lacks stable operation.

[Means to solve the problem]

The chattering noise absorption circuit of the present invention includes a first multivibrator that is activated at the rising edge (or falling edge) of a pulse of an input pulse signal containing chattering noise and outputs a pulse signal with a preset time width; a second multivibrator that is activated at the trailing edge of the output pulse signal of the first multivibrator that is handled during the rising period (or falling period) of the pulse of and outputs a pulse signal with a preset time width; We are prepared.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a circuit diagram showing one embodiment of the present invention, and FIG. 2 is a signal timing diagram for explaining the operation of this embodiment. When an input signal (IN) containing chattering noise is input, the multivibrator 1 is activated at the rising edge of the signal and outputs a pulse signal (signal b) with a time width TI.

On the other hand, the inversion circuit 3 outputs a logical value inversion signal (signal a) of the input signal (IN). Multivibrator 2 is activated at the rising edge of signal S only when signal a is at a low level, and outputs a pulse signal with time width T2 (output signal 0UT). In other words, multivibrator 1 eliminates chattering noise. Then, the multivibrator 3 obtains a pulse signal with a desired time width.

〔Effect of the invention〕

As explained above, according to the present invention, instead of predicting noise components in a certain range and determining the time constant and hysteresis width to absorb noise, noise within a certain time width is absorbed. No matter what kind of chattering noise occurs, it can stably absorb the noise.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIG. 2 is a signal timing diagram for explaining the operation of the circuit in FIG. 1, and FIG.
The figure is a circuit diagram of a conventional circuit, and FIG. 4 is a signal timing diagram for explaining the operation of the circuit of FIG. 3. 1.2... Multivibrator, 3... Inverting circuit,
4... Hysteresis circuit, R... Resistor, C... Capacitor.

Claims (1)

[Claims] A first multivibrator that starts at the rising edge (or falling edge) of a pulse of an input pulse signal containing chattering noise and outputs a pulse signal with a preset time width; a second multivibrator that is activated at the trailing edge of the output pulse signal of the first multivibrator and outputs a pulse signal with a preset time width during a falling period). Noise absorption circuit.