JPH0237044Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention is an open collector output type comparator that inputs a differential voltage from opposing points of a sensing circuit consisting of a bridge-type resistor connection network, and has a voltage feedback between the output terminal and the non-inverting input terminal. In a control device that connects a circuit to perform a Schmitt-trigger operation, even if the output terminal is connected to an unregulated power supply via a load, the input differential voltage, that is, the differential differential differential, is used to perform the specified ON/OFF operation even if the output terminal is connected to an unregulated power supply via a load. This is a control device that causes almost no fluctuation in the serial voltage. As shown in FIG. 1, a conventional device of this kind consists of opposing points 11 and 12 of a sensing circuit 1 consisting of a bridge-type resistor connection network including a sensor S whose equivalent resistance value changes depending on temperature, pressure, humidity, light, etc. are connected to the inverting input terminal 31 and non-inverting input terminal 32 of a comparator 3 having an open collector terminal 30 connected to a load 2 such as a relay, and a resistor 4 is connected between the output terminal 30 and the non-inverting input terminal 32. perform voltage feedback to configure a Schmitt trigger circuit,
This was to obtain an ON/OFF differential differential voltage, but according to this configuration, the circuit power supply 5
If it is powered by a commercial power supply or storage battery that does not take measures against voltage fluctuations, the voltage feedback amount will fluctuate significantly, and the ON/OFF differential amount will also change as the power supply voltage 5 fluctuates. It was big.

Generally, it is possible to stabilize voltage fluctuations in a small current load circuit at a low cost, but stabilizing voltage fluctuations in a large current load circuit is not only expensive, but also increases heat generation and layout area. It is not a special measure.

Therefore, it is preferable to obtain the voltage supplied to the sensing circuit through the small Sienar diode 60 and the series resistor 61 in order to ensure the stability of the entire device, but it is preferable to stabilize the entire circuit. That is a disadvantage.

As shown in FIG. 2, the present invention includes a diode 41 connected in series with a resistor 40 between an open collector terminal 30 connected to a load 2 such as a relay and a non-inverting input terminal 32, with the cathode side connected to the output terminal 30.
A further feature is that the anode side is connected to correspond to the non-inverting input terminal 32 side.

To explain the operation of the present invention, when the output terminal 30 of the comparator 3 is at a high voltage, the diode 41 is reverse-biased so that no voltage feedback is performed, and the diode 41's order is reversed only at the ground level, which is a low voltage. Since voltage feedback is performed by bias, the ON/OFF differential voltage no longer depends on the amount of high voltage feedback, which is most affected by power supply voltage fluctuations. Therefore, when the voltage supplied to the sensing circuit has only a small amount of voltage fluctuation, only voltage feedback at the ground level is effective, so even if there are voltage fluctuations in the circuit power supply, extremely stable ON/OFF operation can be achieved. It is possible to secure an OFF differential differential voltage.

According to the present invention, the disadvantages of conventional devices can be overcome by adding one inexpensive small diode without requiring voltage stabilization of the entire circuit including the output circuit, which is expensive.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing the configuration of a control device using a conventional comparator, and FIG. 2 is a circuit diagram showing the configuration of a control device using a comparator according to the present invention. 1... Sensing circuit. 2...Load. 3... Comparator. 30...Output terminal. 32...Non-inverting input terminal. 40...Resistor. 41...Diode. 5...Unregulated power supply.

Claims (1)

[Scope of utility model registration request] A voltage feedback circuit is connected between an open collector output type comparator 3 that inputs a differential voltage from opposite points of a sensing circuit 1 consisting of a bridge type resistor connection network, and an output terminal 30 and a non-inverting input terminal 32 of the comparator 3. In a control device that performs a shutter trigger operation, the output terminal 30 is connected to the load 2.
A voltage feedback circuit consisting of a resistor 40 connected in series with a diode 41 is connected to the unregulated power supply 5 through A control device using a comparator, which is characterized in that it is connected to the comparator.