JPS5981561A - Input level detector - Google Patents

Abstract

PURPOSE:To put input level detecting circuits in one, to detect an AC And a DC input signal in common and to perform wide-range input level detection by converting an input signal into a pulse signal where its voltage value exceeds a reference value, and sending an on-and an off-signal according to an upper and a lower limit set value of the integral value of the pulse signal. CONSTITUTION:When an AC sine-wave input signal is applied to input terminals A and B, the level of this input signal is adjusted by external resistances R1 and R2 and the resulting signal is supplied as a voltage Vab between points (a) and (b) as input terminals of a rectifying circuit 1. This voltage Vab is rectified on full-wave basis by the rectifying circuit 1 to develop a voltage Vcd between points (c) and (d) as output terminals of the rectifying circuit 1. Then, a voltage detecting circuit 5 which uses a constant voltage element subtracts a constant refrerence voltage Vz from the voltage signal. Consequently, a current Ier corresponding to the part which exceeds the reference voltage Vz flows into a photocoupler 3. The phototransistor of the photocoupler 3 operates in a saturation region, so the output current Igh of the photocoupler becomes pulsative synchronously with the Ief.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an input level detection device used in a process input section of an industrial controller, etc. -Relating to means for outputting an off signal.

[Technical background of the invention]

Input detection circuits used in the process input section of industrial controllers, etc., can detect on/off within a certain range of input conditions in order to clearly distinguish between the on and off states of the input. is necessary. For example, when the input value is 70% or more of the rating, it is judged to be on, and the input value is 30% of the rating.
% or less, it is necessary to perform on/off detection so that it is determined to be off. However, since the characteristics of the AC signal are different from r(=Z), a signal exclusively for AC is generally manufactured separately from a signal for DC, and the two cannot be used in common. It becomes.

FIG. 1 is a block diagram showing the configuration of a conventional general AC input level detection circuit. This circuit consists of a current limiting resistor RX rectifier circuit 1, a filter circuit 2. The AC signal applied between input terminals A and B is rectified by a rectifier circuit, smoothed by a filter circuit #j2, and then supplied to a photocoupler 3. 2
8, and a signal indicating the on state of the input signal is taken out between the output terminals C and D.

Note that the constants of the filter circuit 2 are set in advance so that the photocan 3 is conductive only for input signals above a predetermined level, and the photocan 03 is conductive for input signals below the pruning level. There is.

[Problems with background technology]

Input terminal A of the AC input level detection circuit shown in FIG.
Assume that a BK DC input signal is directly applied. Then, in the case of a DC signal, the maximum value has a different property from the peak value of an AC input signal, so the detection level will be significantly different from that of an AC signal, making accurate input level detection impossible. Many. Therefore, if the input signal is DC, the first
It is necessary to replace the filter circuit 2 in the circuit shown in the figure with another circuit, and to change the constants of the filter circuit 2.

However, normally, in a monolithic device incorporating such an input level detection circuit, the input voltage range is fixed, and it is differentiated into AC and DC voltages. Therefore, many types of modules are required in order to adapt to a location where level detection of various types of input signals is required, such as a process input section of an industrial controller. Therefore, there is a problem in that not only the cost is high, but also it is not always possible to obtain a product that satisfies the requirements.

[Purpose of the launch]

The purpose of the present invention is to use a single input level detection circuit to detect differences in input voltage and to detect alternating current color intensity.ii! ! - It is an object of the present invention to provide an input level detection device capable of commonly performing level detection of an input signal regardless of the difference in type from a current signal, etc., and capable of suppressing an increase in the number of module types.

[Summary of the invention]

In order to achieve the above object, the present invention is characterized by the following configuration. That is, after rectifying the input material,
Convert that water flow output into a voltage coefficient, detect the part of this voltage signal that exceeds the level of '? J
This pulse signal is integrated, and when it exceeds the upper limit setting value, it is determined to be on, and when it is less than the lower limit setting value, the off-set,
This is the judgment! The fact that the i′1 result is configured to be output as an on/off output is defined as f:%.

Embodiment FIG. 2 is a perspective view showing the configuration of an embodiment of the present invention. The same parts as in Fig. 1 are given the same reference numerals. 4 is a current-voltage conversion circuit using a resistor, 5 is a voltage detection circuit using a constant voltage element, 6 is an integrating circuit consisting of a capacitor and a resistor, and 7 is a hysteresis characteristic having an upper limit setting value and a lower limit setting value. In the level detection circuit, R1 is an external resistor for inputting a voltage signal, and R2 is an external resistor for inputting a current signal.

FIG. 3 is a signal waveform diagram of voltage and current at each point a=1 in FIG. That is, vab is the voltage between ab in FIG. 2, and "cd is CdI'iJ1 in FIG.
Voltage, ■. , is the current between ef in FIG. 2, ■gh is the current between gh in FIG. 2, and V.

is the voltage between ij in FIG. 2, and Vkt is the voltage between 7 and 7 in FIG.

The reference value 2d shown in FIG. 3 is the sum of the voltage detected by the voltage detection circuit 5 in FIG. 2 and the -7 voltage drop in the forward direction by the photocoupler 3. Furthermore, the level detection circuit 7 in FIG. 7812 is the upper limit setting value for determining the input ON state, and VL is the lower limit setting value for the level detection circuit 7 determining the OFF state.

Incidentally, FIG. 3 shows an example in which the minimum current that is determined to be the input ON state is input as the input coefficient.

Next, the operation of this apparatus configured as described above will be explained. A sine wave alternating current signal is added to input terminals A and B, and the signal to this input is externally supplied. This voltage vab is applied to the rectifier circuit 1 as a full wave (no. A current of 7 J flows into the part where the photocoupler 3 is operated in the saturation region, so the output current gb of the photocoupler 3 is ■.

It is a pulse-like thing synchronized with. Pulse i in this case
Since M fl, ■2 is constant, the waveform V is obtained by full-wave rectification of the AC input signal of the input signal Pel. dl.

Vcd2. Corresponding to vcd3, a current signal Ighl has a pulse width corresponding to a period during which the reference value V2 is reached.

Igh2. ■gh3 is obtained. Ig□1~
(2) The pulse width of gh3 has a length corresponding to the level of the input signal. For example, the waveform V has a crest factor that is four times the reference value V2. d2, that is, a waveform V whose effective value is V2.

d2 is detected as /4'rus Igh2 with r-neity 50%. Therefore, the level of the AC effective value can be detected depending on whether the data of the nosolized signal is 50% or more or 50% or less.

In addition, for blood flow input signals, the standard value for level detection ■
2, the data is simply detected as either 10()% or 0%.

The explanation returns to FIG. 3. The output current GH of the photocoupler 3 shown in FIG. 3 corresponds to GH2 in FIG. This current Ig is divided into 81 parts by the integrating circuit 6, and an output voltage Vlj shown in FIG. 3 appears at the output terminal jj of the integrating circuit 6. This output 'voltage V, j&': J, in the level detection circuit 7, the upper limit setting I [(1, i.e., the on-state detection voltage VH and the lower limit type H, the two false values, respectively, the off-state detection voltage v
By comparing it with L, you can determine whether the Irukai Yugo is on or off. That is, as shown in FIG. 3, Vij is at time 1.
When the on-state lateral specific pressure VHK reaches the on-state specific pressure VHK, the output voltage Vkt of the level detection circuit turns on, and an output signal indicating the on-state name is output from the output terminals 7C and D. Then, when the input coefficient is Itlr, Vlj becomes OFF state detection voltage V1. When it goes below , 7 is off in ■, and the main state coefficient is output.

Therefore, the rising time constant and falling crystal redundancy of the integrating circuit 6, and the on-state detection voltage VH and off-state detection voltage ttEEv of the level detection circuit 7 are set to appropriate values.
It is possible to detect the same level as the Yamaryu envelope even when using a commercial AC input signal with a wave number of 50 Hz or 60 Hz.

5(a) and 5(b) show the integration constants of the integrating circuit 6 in FIG. 2, that is, the 9 time constant for rising and the 9 time constant for falling, and the on-state detection box of the level detection circuit 7.

This is a specific example when the off-state detection voltage vL is selected as a generally easy-to-use candy, and Figure (a) shows that the input color depth is set to the reference value V2 as in the case of Figure 3. This is the case of a 50 Hz sine wave information having an equal effective value, and (b) of the same figure shows a case of a 60 Hz sine wave information whose input coefficient also has an effective value equal to the reference value ■2.
This is the case for a sine wave signal of Hz. The rising or falling time constant of the integrating circuit 6 is 6 ms, and the falling time constant is 9 ms.The on-state detection voltage Vi1 of the level detection circuit 7 is 70% of the maximum voltage of the circuit 6, and the off-state detection voltage vL is the integrating circuit. 6 is selected to be 30% of the maximum voltage.

The following table shows the output voltage V1 of the integrating circuit 6 under these conditions.
3 is a table showing values of each peak value P1 to P9 of No. 3.

As can be seen from the above table, the AC input with the effective value corresponding to the minimum number 11+i input that turns on the input is 4t.
When the AC input signal is turned on, the ON state of the AC input signal is detected at a predetermined time point.

Figures 6(a) and 6(b) show the input level detecting device shown in Figure 2. 6(a) is a diagram illustrating another actual Mtj example of the present invention packaged as input voltage detection monoles Ml and M2; FIG. 6(a) is a configuration when used for voltage input; FIG. b) is a configuration example when used for current input.

In FIGS. 6(a) and 6(b), R1 and R2 are input level detection circuits M1. V is a resistor for introducing an input signal connected to each input terminal of M2, and V is an input level detection module M1. Internal voltage drop of M2, V
2 is external power supply voltage, I is external current, ■1 is input current, ■
2 is a bypass current.

In FIG. 6(a), the input current Il is I,=V,g
2Vl (vl=constant) 1, so depending on the external power supply voltage V2, the external resistor R
If the input current II is adjusted to 1, the input current II will be at a continuous level.

In FIG. 6(b), 1=I 1 +12 1 2 =□ 2 , so the input current Il is 1 11=I−Ti (V uniform constant). Therefore, by adjusting the external resistor R2 according to the value of the external current regulator, the input current Il will be at an appropriate power level.

As shown in FIGS. 6(a) and 6(b), an external resistor R1 is provided at the input end of the input level detection module M1- or M2.
Furthermore, by forming R2 into a W chisel shape, it is possible to adapt the input level to a wide range of input levels, whether the input signal 8 is a low pressure signal or a current signal. As an application example 7 of Figure 6<a) and (b), consider using the same hVC for the external resistor R1 in Figure 6(a) and the external resistor R2 in Figure 6(b). It will be done. In this way, the input level detection module can be used even if the input voltage is manually applied or has a relatively high level. Also, the resistors RJ and R2, which generate most of the heat, are monoyl Ml.

Since it is configured to be attached to the outside of M2, it is ideal for small packaged monols.

[Efficacy of invention]

According to the present invention, a portion of the voltage value of an input signal that exceeds a reference value is detected, the portion of the exceeded partial tone is converted into a pulse signal having an A' pulse width corresponding to the level, and this pulse signal is integrated. The structure is configured so that an off signal is sent when the integral value exceeds the upper limit setting value, and an off signal is sent when the integral value is below the lower limit setting value, so it was conventionally used separately for AC and DC applications. It is a general-purpose input that can combine two input level detection circuits into one circuit, commonly detect the level of AC and DC input signals, and can detect a wide range of input levels by simply selecting an external resistor. A level detection device can be provided.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a conventional AC input level detection circuit, and FIGS. 2 to 5 are diagrams showing an embodiment of the present invention.
The figure is a block diagram showing the configuration, Figure 3 is a waveform diagram showing voltage and current waveforms at each point in Figure 2, Figure 4 is a waveform diagram showing the principle of input level detection, Figure 5 (a) (b) ll'i
A waveform diagram showing the input and output voltages of the level detection circuit when specific constants are set, and FIG. , (a) is a block diagram showing the configuration when used for voltage input, and (b) is a block diagram showing the configuration when used for current input. 1... Rectifier) path, 2... Filter [p', l path, 3
・ Photocoupler, 4... Current-voltage conversion circuit, 5...
Voltage detection circuit, 6 Integration circuit, 7...Level detection circuit,
A, B...input terminal, C, D...output terminal, R...
Current limiting resistor, R1, R2...external resistor, Ml. M2...Input level detection module. Application fee] M So (patent attorney Takehiko Suzue Figure 4 Figure 5 (a) (b)

Claims (3)

[Claims] (1) A rectifier circuit that rectifies an input signal, a current-voltage converter circuit that converts the output of this rectifier circuit into a voltage signal, and a portion of the voltage signal output from this current-voltage converter circuit that exceeds a reference value. a voltage detection circuit that outputs the voltage, a photocoupler that converts the detection output of this voltage detection circuit into a pulse with a width corresponding to the level of this output and outputs it to IJ-1, and an integration circuit that integrates all the output pulses of this photocoupler. and a level detection circuit that outputs an on signal when the output integrated by the integrating circuit exceeds the upper limit setting value and outputs an off signal when the output falls below the lower limit setting value. Direct to the equipment. (2) The input level detection device according to claim (1), wherein the rectifier circuit, the photocoupler, the filter, and the level detection circuit are input level detection modules made into personal computers. (3) The input level detection device as set forth in claim (2), wherein the input level detection monole is provided with an external resistor for introducing an input signal at the input end.