JP3598989B2 - Pulse generating circuit, method for preventing malfunction thereof, and communication device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a pulse generation circuit, a malfunction prevention method thereof, and a communication device, and more particularly to a pulse generation circuit that outputs a signal of a predetermined pulse width using a monostable multivibrator (hereinafter, referred to as a monomulti), and a pulse generation circuit thereof. The present invention relates to a malfunction prevention method and a communication device.
[0002]
[Prior art]
Conventionally, when a signal having a predetermined pulse width is generated using a rising or falling edge of a certain signal as a trigger, for example, as shown in FIG. 6, a pulse is generated using only one mono-multi. In FIG. 6, the mono multi 3 connects the input terminal A to the ground, and the input terminal B connects an input signal serving as a trigger signal for operating the mono multi 3. The resistor 1 and the capacitor 2 are connected to the monomulti 3 and determine the pulse width of a signal to be output when the monomulti 3 is triggered. At this time, in an environment where noise or the like does not occur, the pulse generation circuit operates normally.
[0003]
[Problems to be solved by the invention]
In the conventional pulse generation circuit using the above-mentioned mono-multi, when noise (noise) such as static electricity occurs, the ground is unstable due to the influence of the noise if neither measures to strengthen the ground nor measures to cut off the noise are taken. Then, a trigger is activated inside the mono-multi, and as a result, a malfunction occurs easily and a pulse is output even though there is no signal at the input. Therefore, there is a problem that a pulse is output at a timing that is not originally required.
An object of the present invention is to provide a pulse generation circuit capable of preventing a pulse due to a malfunction from being output to a subsequent circuit without taking measures against ground reinforcement or noise cutoff, a malfunction prevention method therefor, and a communication device. It is in.
[0004]
[Means for Solving the Problems]
A pulse generation circuit according to the present invention receives a first monostable multivibrator that outputs a signal having a predetermined pulse width at a required timing, and inputs, differentiates, and outputs an output signal of the first monostable multivibrator. A differentiating circuit, a second monostable multivibrator that operates when a noise is generated by receiving a signal output from the differentiating circuit as an input, and a logic of a signal output from the first and second monostable multivibrators A logical product circuit for taking a product and outputting the result, and the logical product circuit may be a negative logical product circuit.
[0006]
A communication device according to the present invention includes a first monostable multivibrator that outputs a signal having a predetermined pulse width at a required timing, and a differentiation device that inputs, differentiates, and outputs an output signal of the first monostable multivibrator. Circuit, a second monostable multivibrator that operates when a signal output from the differentiating circuit is input and noise is generated, and a logical product of signals output from the first and second monostable multivibrators And a pulse generating circuit including a logical product circuit or a negative logical product circuit for taking the result. The noise is noise generated by static electricity.
[0007]
According to the method for preventing malfunction in the pulse generation circuit of the present invention, a first signal having a required pulse width is output from a first monostable multivibrator, and the first signal is input and differentiated to output a pulse having a predetermined width. When a pulse having this predetermined width is input and noise occurs, the second monostable multivibrator is operated to output a second signal, and the logical product of the first and second signals is obtained, and the result is obtained. The logical product may be a negative logical product. The noise is noise generated by static electricity.
[0008]
According to the present invention, when noise due to static electricity is generated, a signal output by a malfunction from the monopulse for normal pulse width output is masked by a signal output from the monomulti for static electricity detection, that is, by canceling out. In addition, it is possible to prevent a pulse due to a malfunction from being output to a subsequent circuit.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings.
[0010]
Referring to FIG. 1, a pulse generating circuit according to the present invention is connected to a resistor 1 and a capacitor 2 for determining a pulse width, inputs an input signal serving as a trigger, and outputs a signal having a required pulse width. An output mono-multi 3, a differentiating circuit 4 for differentiating the output signal of the mono-multi 3, a resistor 5 and a capacitor 6 for determining a pulse width are connected, and a signal from the mono-multi 3 and the differentiating circuit 4 is connected. A mono-multi 7 for detecting static electricity which operates when noise due to static electricity is generated as an input, a logical product of signals output from the mono-multi 3 and the mono-multi 7 and a logical product (AND) for outputting the result And a circuit 8.
[0011]
It has a pulse generation circuit that outputs a signal with a pulse width determined by a mono-multi. A communication device installed in a place where static electricity frequently occurs due to intense human traffic, as a specific device name , A carrier relay device, a program transmission control device, and the like. The carrier relay device is a communication device for transmitting and receiving information on the current flowing in the transmission line in order to prevent a generator or a transformer from being damaged due to a transmission line accident, and the program transmission control device controls the program. This is a device that superimposes a control signal for performing the superimposition on a video signal and an audio signal, and detects the superimposed signal. The pulse generation circuit according to the present invention can be applied not only to the above-described device but also to a general communication device.
[0012]
In FIG. 1, the mono multi 3 connects the input terminal A to the ground, and the input terminal B connects an input signal serving as a trigger signal for operating the mono multi 3. The resistor 1 and the capacitor 2 are connected to the mono multi 3 and determine the pulse width of a signal to be output when the mono multi 3 is triggered. The signal output from the mono-multi 3 is input to the differentiating circuit 4, and the differentiating circuit 4 differentiates and outputs the input signal. The signal output from the differentiating circuit 4 is connected to the input terminal B of the monomulti 7, and the input terminal A of the monomulti 7 is connected to the input signal. The mono-multi 7 outputs a signal having a pulse width determined by the resistor 5 and the capacitor 6 according to the conditions of the input signals at the input terminals A and B. The signal output from the mono multi 7 is connected to the AND circuit 8. The AND circuit 8 takes the logical product of the output signal from the mono-multi 7 and the output signal from the mono-multi 3, and outputs the result.
[0013]
Next, the operation of the embodiment of the present invention will be described with reference to FIG. 1, FIG. 2, FIG. 3, and FIG. The mono-multi in this case is of the retrigger type for convenience. The trigger is applied to the mono-multi when the signal at the input terminal A is LOW and the signal at the input terminal B rises, and when the signal at the input terminal B is HI and the signal at the input terminal A falls. .
[0014]
First, the operation in the case where the noise is not affected by static electricity will be described. The input signal to the input terminal B of the mono multi 3 is normally LOW, and changes to HI as shown in S1 of FIG. 2 when it is desired to output a signal having a required pulse width. When the input signal changes to HI, the monomulti 3 outputs from the output Q a signal that becomes HI for the pulse width determined by the resistor 1 and the capacitor 2 (S2 in FIG. 2). The signal output from the output Q is input to the differentiating circuit 4. Since the differentiating circuit 4 differentiates and outputs the input signal, it outputs a signal that becomes HI only for a very short width (S3 in FIG. 2).
[0015]
The output signal of the differentiating circuit 4 is connected to the input terminal B of the monomulti 7, and the same signal as the input signal of the monomulti 3 is connected to the input terminal A. Therefore, when the input signal to the input terminal B is HI, the input signal to the input terminal A is also HI. That is, the trigger is not applied to the mono multi 7 and the pulse signal having the determined width is not output from the output Q bar (S4 in FIG. 2).
[0016]
The AND circuit 8 outputs the logical product of the output signal from the monomulti 3 and the output signal from the monomulti 7. Since the signal from the mono-multi 7 is always HI, the signal from the mono-multi 3 is output as it is from the AND circuit 8 (S5 in FIG. 2).
[0017]
Next, the operation in the case where noise due to static electricity occurs and the mono multi 3 malfunctions will be described.
[0018]
When noise due to static electricity is generated, the ground becomes unstable due to the influence. As a result, a trigger is generated inside the mono-multi 3, and a signal that becomes HI from the output Q by the pulse width determined by the resistor 1 and the capacitor 2 is output (S7 in FIG. 3). At this time, since the input has no trigger signal, it remains LOW (S6 in FIG. 3). The differentiating circuit 4 outputs a signal which becomes HI only for a very short width in order to differentiate the signal from the mono-multi 3 (S8 in FIG. 3).
[0019]
On the other hand, since the same input signal as that of the mono multi 3 is input to the input terminal A of the mono multi 7, it remains LOW. Since a signal from the differentiating circuit 4 is input to the input terminal B, the monomulti 7 operates by using the signal as a trigger, and outputs a signal which becomes LOW by the width determined by the resistor 5 and the capacitor 6 from the output Q bar. (S9 in FIG. 3). At this time, the value of the pulse width set by the resistor 1 and the capacitor 2 is D, the value of the pulse width set by the resistor 5 and the capacitor 6 is E, and D <E is satisfied. Therefore, an HI signal having a pulse width D is output from the output Q of the monomulti 3, and a LOW signal having a pulse width E is output from the output Q bar of the monomulti 7.
[0020]
The AND circuit 8 receives the HI signal of the pulse width D output from the mono-multi 3 and the LOW signal of the pulse width E output from the mono-multi 7 and outputs a logical product of them, so that the LOW signal is always output. Is output (S10 in FIG. 3). In other words, even if noise due to static electricity occurs, the output of the mono-multi 7 cancels the pulse of the mono-multi 3, so that an erroneous pulse is not output to the subsequent circuit.
[0021]
Next, the operation in the case where noise caused by static electricity occurs and the mono-multi 3 and the mono-multi 7 simultaneously malfunction will be described.
[0022]
If the mono-multi 3 and the mono-multi 7 simultaneously malfunction, the mono-multi 3 outputs a signal (S11 in FIG. 4) which becomes HI for the pulse width determined by the resistor 1 and the capacitor 2. A signal (S12 in FIG. 4) that becomes LOW by the pulse width determined by the resistor 5 and the capacitor 6 is output. Therefore, since the AND circuit 8 is canceled by the LOW signal output from the monomulti 7, the LOW signal (S13 in FIG. 4) is output from the output. In other words, even if noises due to static electricity are generated and the monomultis 3 and 7 malfunction at the same time, an erroneous pulse is not output to the subsequent circuit.
[0023]
The present invention is not limited to the above-described circuit example. For example, as shown in FIG. 5, even when a NAND circuit 9 is used instead of the AND circuit 8 as the final gate, the same effect can be easily obtained. Obtainable. The pulse generation circuit in this case is exactly the same as the configuration shown in FIG.
[0024]
The operation of FIG. 5 is as follows. The operation up to the output of the mono-multi 3 and the mono-multi 7 is the same as the operation of FIG. 1, and the logic of the signal output from the final gate is opposite to that of FIG. Specifically, when there is no trigger signal in the mono multi 3 or when noise due to static electricity occurs, a HI level signal is output. When a trigger signal is input to the mono multi 3, a signal that becomes LOW by a pulse width determined by the resistor 1 and the capacitor 2 is output.
[0025]
【The invention's effect】
As described above, according to the present invention, a mono-multi that outputs a signal at a required timing without taking measures to strengthen the ground or block noise can convert a pulse signal output due to a malfunction of noise into a mono for noise detection. By canceling with the pulse output from the multi, it becomes possible to prevent a pulse due to a malfunction from being output to the subsequent circuit.
[Brief description of the drawings]
FIG. 1 is a diagram showing an embodiment of a signal generation circuit of the present invention.
FIG. 2 is a waveform chart for explaining the operation of the embodiment of the present invention.
FIG. 3 is a waveform chart for explaining the operation of the embodiment of the present invention.
FIG. 4 is a waveform chart for explaining an operation of the exemplary embodiment of the present invention.
FIG. 5 is a diagram showing a case where an AND circuit in the embodiment of the signal generation circuit of the present invention is replaced with a NAND circuit.
FIG. 6 is a diagram illustrating an example of a conventional signal generation circuit.
[Explanation of symbols]
1,5 resistor 2,6 capacitor 3,7 mono multi 4 differentiator 8 AND circuit 9 NAND circuit

Claims (7)

A first monostable multivibrator for outputting a signal having a predetermined pulse width at a required timing, a differentiating circuit for inputting and differentiating an output signal of the first monostable multivibrator, and a differentiating circuit. A second monostable multivibrator that operates when noise is generated with the output signal as an input, and a logical product of the signals output from the first and second monostable multivibrators, and the result is output. A pulse generation circuit, comprising: an AND circuit. 2. The pulse generation circuit according to claim 1, wherein said AND circuit is a NAND circuit. Claim 1 or 2 One A communication device comprising the pulse generation circuit according to any one of the preceding items. A first signal having a required pulse width is output from a first monostable multivibrator, and the first signal is input and differentiated to output a pulse having a predetermined width. A malfunction in the pulse generation circuit, wherein when it occurs, the second monostable multivibrator is operated to output a second signal, and the logical product of the first and second signals is taken and the result is output. Prevention method. 5. The method according to claim 4, wherein the logical product is a negative logical product. The noise according to claim 1, wherein the noise is noise generated by static electricity. One The pulse generation circuit according to the paragraph. 6. The method according to claim 4, wherein the noise is noise generated by static electricity.

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