JPS60196680A - Voltage change detection apparatus - Google Patents

Abstract

PURPOSE:To make it possible to detect a voltage rising or falling state faster than a set speed, by simple constitution such that the output of an operation amplifier acting as a differentiation amplifier is compared with that of an operation amplifier merely acting as an amplifier. CONSTITUTION:During a period showing no change in input voltage Vin or when the voltage rising ratio of input voltage Vin is smaller than a predetermined time constant and changed gently, operation amplifiers OP1, OP2 merely act as amplifiers. At this time, because the output voltage V1 of the operation amplifier OP1 becomes slightly higher than the output voltage V2 of the operation amplifier OP2, the output of a voltage comparator CMP comes to a low level. When the voltage rising ratio of the input voltage Vin is larger than a predetermined time constant, the operation amplifier OP1 acts as a differentation operator and, because the amplification degree thereof becomes larger than that of the operation amplifier OP2, the output voltage V1 becomes smaller than V2 and the output of the voltage comparator CMP comes to a high level.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD The present invention relates to a voltage change detection device that detects voltage rise and fall changes.

BACKGROUND ART Conventionally, in order to detect a change in voltage, the voltage value is measured and then the state of change is observed, and the circuit configuration for this purpose has become complicated. In addition, in some systems, it is not necessary to know the magnitude of the input voltage as part of its control, but rather it is necessary to know whether the input voltage is increasing or decreasing at a faster rate than expected. Detection may be sufficient.

■The present invention has been made in consideration of the above points, and uses a simple configuration to detect hair only when the voltage rises or falls faster than a preset speed among input voltage changes. The present invention provides a voltage change detection device that is capable of detecting voltage changes.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows a configuration example of a voltage change detection device according to the present invention when detecting a state in which a voltage rises faster than a preset rate among changes in input voltage. First operational amplifier OP forming operational amplification
I, and a second operational amplifier OP that amplifies the input voltage Vin.
2, and a voltage comparator CMP that compares the amplified output voltages VL and V2. In addition,
Among the resistors R1 to R7, those with the same number indicate those having the same resistance value.

In the configuration shown in the figure, the reference voltage +Vs is connected to the common-mode input terminal (+) side of the operational amplifier OPI with a resistor R5 and a resistor R
6, R7 is applied through the resistor R4, and the common mode input terminal (+) side of the operational amplifier ○P2 receives the voltage obtained by dividing the reference voltage +Vs by the resistors R5, R6 and the resistor R7. is applied through the resistor R4, so that the outputs of each operational amplifier OP1 and OF2 have a predetermined operating point voltage, and the output voltage v1 of the operational amplifier ○PI is higher than the output voltage V2 of the operational amplifier OP2. It is set to be slightly high.

Each operational amplifier OP1. The negative phase input circuit and feedback circuit on the input terminal (-) side of OP2 have equivalent circuit configurations in terms of direct current. Therefore, each operational amplifier OPI
As shown in FIG. 2, the static characteristics of input and output in , OP2 are almost the same (the output voltage of operational amplifier OP1 is slightly higher due to the difference in common mode input voltage), and are linear. Therefore, for a DC voltage that does not change, regardless of its level, the output voltage (■1) of the operational amplifier ○P1 has a value slightly higher than the output voltage V2 of the operational amplifier OP2.

Further, the negative phase input circuit and feedback circuit on the input terminal (-) side of each operational amplifier OPI, OP2 have different circuit configurations from each other in terms of alternating current.

In other words, operational amplifier OP2 acts as a simple amplifier, but operational amplifier OPI has a capacitor C in its anti-phase input circuit, so if the resistance value is selected so that R1>>R,3, , it operates as a differential amplifier from a time constant determined by capacitor C and resistor R1 to a time constant determined by capacitor C and resistor R3. Therefore, each operational amplifier 0'P1.
As shown in FIG. 3, the frequency characteristic of OP2 is that when the frequency of the input voltage Vin exceeds a predetermined value, the operational amplifier O
The output voltage v1 of P1 is higher than the output voltage v2 of operational amplifier OP2.

The operation of the voltage change detection device according to the present invention configured as described above will be explained with reference to an example of the state of change of the voltage waveform in each region shown in FIG. In addition, Fig. 4 (,) is a characteristic diagram when looking at the temporal change of the input voltage Vin, and Fig. 4 (b) is a characteristic diagram when looking at the temporal change of the input voltage Vin.
) is a characteristic diagram when looking at temporal changes in the output voltage v1 of the operational amplifier OP1.

Figure (c) is a characteristic diagram when looking at the temporal change in the output voltage v2 of operational amplifier OI)2, and Figure (d) is a characteristic diagram when looking at the temporal change in the output voltage VouL of the voltage comparator CMP. It is.

Now, when an input voltage Vin as shown in FIG. 4(a) is sent, there is no change in voltage at A and C.

In each period of E, each operational amplifier OPI, OT.

2 act as a simple amplifier, but in this case, as mentioned above, since the output voltage V1 of the operational amplifier OPI is slightly higher than the output voltage v2 of the operational amplifier OP2,
The output voltage Vout of the voltage comparator CMP is low level'''
It becomes L II.

Furthermore, during the period B in which the input voltage Vin increases, if the rate of voltage increase is greater than a predetermined time constant, the operational amplifier OPI acts as a differential amplifier as described above, so that the amplification degree is the same as that of the operational amplifier. The amplification degree is larger than that of OP2, as shown in Fig. 2(b).

As shown in (c), the output voltage ■1 of the operational amplifier OPI becomes smaller than the output voltage v2 of the operational amplifier OP2, and therefore the output voltage Vout of the voltage comparator CMP decreases (d
), it becomes a high level "H".

Furthermore, in the period D when the input voltage Vin decreases,
If the voltage drop rate is larger than a predetermined time constant, the operational amplifier OPI acts as a differential amplifier as described above, and its amplification degree becomes larger than that of the operational amplifier OP2, as shown in FIG. , as shown in (C), the output voltage v1 of the operational amplifier OPI becomes larger than the output voltage 2 of the operational amplifier OP2, and therefore the output voltage Vou of the voltage comparator CMP becomes low as shown in the same figure (d). level"
L”.

Therefore, from the voltage comparator CMP, the output voltage V out at a high level "'H" is obtained only during the period when the input voltage Vin increases with a voltage increase rate larger than a predetermined time constant.In this case, If the voltage increase rate of the input voltage Vin changes slowly so that it is smaller than a predetermined time constant, the operational amplifier OPI acts only as a simple amplifier, so even during the voltage increase period, the voltage The output voltage Vout of the comparator CMP is low level “L”
” becomes.

As described above, in the voltage change detection device according to the present invention,
Among the changes in the input voltage 5n, it is possible to detect only the state in which the input voltage increases at a faster rate than the time constant set in advance for the operational amplifier OPl.

Further, FIG. 5 shows a configuration example of a voltage change detection device according to the present invention in the case of detecting a state of voltage drop faster than a preset rate among changes in input voltage.

In this case, the operational amplifier OPl in FIG.

The OF2 relationships are exchanged with each other.

That is, the operational amplifier 01) 1' acts as a simple amplifier when the input voltage Vin is constant, and the input voltage ■. It acts as a simple amplifier when the input voltage Vin is constant and changes at a rate of change smaller than the time constant set in the negative phase input circuit, and acts as a differential amplifier when the input voltage Vin changes at a rate of change greater than the time constant. At the same time, when the input voltage Vin is constant, the operational amplifier OP 1
an operational amplifier OP2' set to produce an output voltage higher than ', and each of these operational amplifiers OPI, OP
and a voltage comparator CMP' which compares the two output voltages and produces a high level output when the input voltage Vin falls at a rate of change greater than the time constant.

In this case, the input/output static characteristics of each operational amplifier OPI and OP2 are shown in FIG. 6, and the input frequency characteristics thereof are shown in FIG. 7, respectively. Further, FIG. 8 shows an example of the changing state of the voltage waveform in each city. In this case, especially when the voltage fall rate exceeds a predetermined time constant and the input voltage Vin
The output voltage Vl' of the operational amplifier opt' decreases only during the period when the output voltage V2' of the operational amplifier opt
The output voltage v of the voltage comparator CMP' becomes smaller than
out' becomes high level. Even in this case, when the voltage fall rate of the input voltage Vin changes slowly so that it becomes smaller than a predetermined time constant, the operational amplifier O
Since P2' acts only as a simple amplifier, the output voltage V of voltage comparator CMP' even during the voltage drop period.
out' becomes low level.

As described above, in the voltage change detection device according to the present invention,
The operational amplifier OP2' is
It is now possible to detect only the state in which the vehicle is descending at a speed faster than the time constant set.

FIG. 9 shows an example of a system configuration when the voltage fluctuation detection device according to the present invention is actually used in an object detection system that detects obstacles when a car is running, for example. This consists of an oscillator 1 that generates a constant frequency signal, a network 2 consisting of a resistance divider circuit provided on the output side of the oscillator 1, a sensor S consisting of an electrode plate connected to the dividing point, and the network 2. A band-pass reduction amplifier 3 performs noise removal and amplification processing on the high-frequency output voltage from the sensor S, a detector 4 detects the amplified output signal, and detects the falling state of the detected voltage signal to detect the object relative to the sensor S. The voltage change detection device 5 detects the approach of O and issues an alarm command to the driver 6 using an alarm 7 if there is a voltage drop with a rate of change greater than a preset time constant. However, in such a structure, as the object O approaches the sensor S, the stray capacitance Cd between the two increases, and the output frequency signal of the material 1 and the work 2 is attenuated.
The falling state of the output voltage of the detector 4 corresponding to the attenuation is detected by the voltage change detection device 5, and if necessary, the alarm 7 is activated so that the object ○ approaches f1 at a preset speed or higher. It's trying to alert me to something.

As described above, the voltage fluctuation detection device according to the present invention can detect whether the input voltage is increasing or decreasing at a rate of change faster than a preset rate using a simple configuration. It has the excellent advantage of being easy to perform.

[Brief explanation of the drawing]

FIG. 1 is an electrical wiring diagram showing an embodiment of the voltage change detection device according to the present invention, FIG. 2 is a diagram showing the input/output static characteristics of each operational amplifier in the same embodiment, and FIG. 3 is a diagram showing the input frequency of each operational amplifier. FIG. 4 is a diagram showing characteristics, and FIG. 4 is a time chart 1 showing an example of changing states of voltage waveforms at various parts in the same embodiment. FIG. 5 is an electrical wiring diagram showing another embodiment of the present invention. FIG. A diagram showing the input/output static characteristics of each operational amplifier in the same example,
FIG. 7 is a diagram showing the input frequency characteristics, and FIG. 8 is a time chart 1-1 showing an example of the state of change in the voltage waveform of each part in the same embodiment. FIG. 9 is a diagram showing the voltage change detection device according to the present invention. FIG. 2 is a block diagram showing an example of the configuration of a system used in the present invention. OPI, OF2. ○Pi', OP2'...Operation amplifier CMP...Comparator Fig. 1 Fig. 3 Input stream Fig. 5 Fig. 4 Fig. 6 Fig. 7 Fig. 8 Fig. 9

Claims (1)

[Claims] 1. Acts as a simple amplifier when the input voltage is constant and when it changes at a rate of change smaller than the time constant set in the negative phase input circuit, and the input voltage has a rate of change greater than the time constant. a first operational amplifier that acts as a differential amplifier when the input voltage varies; and a second operational amplifier that acts as a simple amplifier configured to produce a higher output voltage than the first operational amplifier when the input voltage is constant. and a voltage comparator that compares the output voltages of the operational amplifiers 1L and 1L and generates a detection output when the input voltage rises at a rate of change greater than the time constant. 2. The first operational amplifier acts as a simple amplifier when the input voltage is constant, and the first operational amplifier acts as a simple amplifier when the input voltage is constant and changes at a rate of change smaller than the time constant set in the negative phase input circuit. a second operational amplifier configured to act as a differential amplifier when the input voltage changes at a rate of change greater than its time constant, and to produce a higher output voltage than the first when the input voltage is constant;
and a voltage comparator that compares the output voltages of each of these operational amplifiers and produces a detection output when the input voltage falls at a rate of change similar to the time constant. Device.