JPH0524221Y2 - - Google Patents

Description

[Detailed Description of the Invention] Technical Field The present invention relates to a load detection device that can be suitably used to confirm whether or not a load is energized.

BACKGROUND ART In a load energized by a relatively high voltage, such as 100 volts AC or 28 volts DC, circuit elements forming a load detection device for detecting and confirming the operating state of the load are required. withstand voltage,
They must increase depending on the voltage applied to their loads. Therefore, it is desirable to reduce the withstand voltage of these circuit elements.

Purpose The purpose of the present invention is to provide a load detection device for remotely detecting whether or not a load voltage is applied to a load by connecting it to a processing circuit realized by a microcomputer or the like. The present invention is to provide a circuit composed of circuit elements with reduced voltage.

Configuration In the present invention, the power supplied to the loads 13 and 23 is given to the noise absorption circuit 40 in which the first resistor R1 and the first capacitor C1 are connected in series, and the power is supplied from both ends of the first capacitor C1. A full-wave rectifier circuit 41 to which power is applied; a second capacitor C2 connected to the output side of the full-wave rectifier circuit 41; a second resistor R2 whose one end is commonly connected to one end of the second capacitor C2; A third resistor R3 is connected in parallel with the first capacitor C1, one end is connected to the other end of the second resistor, and the other end is connected to the second resistor R3.
A light emitting element 43 is commonly connected to the other end of the capacitor C2, and a light receiving element 44, which is electrically insulated from the light emitting element 43 and receives light from the light emitting element 43, is connected in parallel to the output side of the light receiving element 44. 3rd to be done
A series circuit consisting of a capacitor C3, a fourth and a fifth resistor R4 and R5 that divide the output from both ends of the third capacitor C3, and a transistor 45 driven by the divided voltage output from both ends of the fifth resistor R5. The load detection device is characterized in that the resistance value of the first resistor R1 is set larger than the resistance value of the second resistor R2.

Embodiment FIG. 1 shows a load detection device 1 according to an embodiment of the present invention.
FIG. A control signal from a processing circuit 30 realized by a personal computer or the like controls AC or DC relays 12 and 22 from a bus 31 via decoders 11 and 21, thereby controlling AC load 13 and DC load 23. is controlled. Examples of the AC load 13 include a motor and a detection element, and examples of the DC load 23 include a solenoid, a valve, and a detection element. load 13,
Whether or not 23 is energized is detected by the load detection device 10, 20 according to the invention and provided from the bus 31 to the processing circuit 30 via the multiplexers 14, 24.

FIG. 2 is an electrical circuit diagram showing a specific configuration of the load detection device 10. As shown in FIG. The power supplied to the AC load 13 is also applied to terminals 1,2. Noise is absorbed from this power by a noise absorption circuit 40 consisting of a resistor R1 which is a first resistor and a capacitor C1 which is a first capacitor, and the noise is absorbed by a full wave rectifier circuit 40.
Full-wave rectification is performed by 1. A resistor R3, which is a third resistor for discharging the capacitor C1, is connected in parallel to the capacitor C1. The output from the full-wave rectifier circuit 41 is smoothed by a smoothing circuit 42 including a second resistor R2 and a second capacitor C2, and is applied to a light emitting element 43 such as a light emitting diode. Light from the light emitting element 43 is received by the light receiving element 44. The output from this light receiving element 44 is a resistor R4 which is a fourth resistor, a resistor R5 which is a fifth resistor, a resistor R6 and a capacitor C which is a third capacitor.
3 to the base of transistor 45 through a circuit including 3. The collector and emitter of transistor 45 are connected to terminals 4 and 5, respectively, and the collector is connected to terminal 3 via resistor R7. Power supply voltage Vcc is applied to terminal 3, and terminal 5 is grounded. The load detection signal from terminal 4 is applied to multiplexer 14 .

When the load 13 is energized, the light emitting element 43
emits light. This makes the light receiving element 44 conductive. Therefore, the transistor 45 becomes conductive, and the terminal 4
is at the same low level as terminal 5. When the load 13 is deenergized, the light emitting element 43 is deenergized. Therefore, the light receiving element 44 and the transistor 45 are cut off. Therefore, terminal 4
is set to the same high level as terminal 3 by resistor R7.

Resistor R1 has a larger resistance value than resistor R2. This increases the voltage drop across resistor R1. Therefore, capacitor C1, resistor R
3. It becomes possible to lower the withstand voltage of circuit elements subsequent to the resistor R1, such as the full-wave rectifier circuit 41. The capacitor C1 slows down the rise of the surge, allowing circuit elements with low surge performance to be used thereafter. Resistance R4, R
5 and capacitor C3 absorb noise applied to the base of transistor 44.

Effects As described above, according to the present invention, loads 13, 23
The power supplied to the light emitting element 43 is divided by first and second resistors R1 and R2 that are interposed in series with the light emitting element 43. Since the resistance value of the first resistor R1 on the input side is set to be larger than the resistance value of the second resistor R2, the voltage drop due to the first resistor R1 is increased and the withstand voltage of subsequent circuit elements is reduced. becomes possible.

The light emitting element 43 is energized by the power that has been full wave rectified by the full wave rectifier circuit 41, smoothed by the second capacitor C2 and the second resistor R2, and converted into direct current. can generate light in a stable state with little noise.

Further, since the light emitting element 43 and the light receiving element 44 are electrically insulated, noise generated due to the operation of the loads 13 and 23 is unlikely to enter the light receiving element 44 or the circuit on the transistor 45 side.

Further, a third capacitor C3 is connected in parallel to the output side of the light-receiving element 44, and the transistor 45 receives the outputs from both ends of the third capacitor C3.
Since a divided voltage output is provided by the resistors R4 and R5, noise in the signal driving the transistor 45 can be reduced. The transistor 45 driven in this way is used for loads 13 and 2 that use large load currents, such as relays.
It is also possible to drive 3 directly.

Furthermore, by making the first resistor R1 larger than the second resistor R2, the withstand voltage of the circuit element can be lower, so the circuit can be constructed from small parts and can be integrated into one package as an integrated circuit. It is also easy to store. The second resistor R2 is the light emitting element 4
Since the current of 3 is limited, the load can be detected over a wide range of voltages of the power supplied to the loads 13 and 23.

[Brief explanation of drawings]

FIG. 1 shows a load detection device 1 according to an embodiment of the present invention.
FIG. 2 is an electrical circuit diagram of an embodiment of the present invention. R1-R7...Resistor, C1-C3...Capacitor, 10,20...Load detection device, 40,41...
...Full wave rectifier circuit, 43... Light emitting element, 44... Light receiving element, 45... Transistor.

Claims (1)

[Claims for Utility Model Registration] The power supplied to the loads 13 and 23 is given to a noise absorption circuit 40 in which a first resistor R1 and a first capacitor C1 are connected in series. A full-wave rectifier circuit 41 to which power is applied from both ends, a second capacitor C2 connected to the output side of the full-wave rectifier circuit 41, and a second resistor R2 whose one end is commonly connected to one end of the second capacitor C2. , a third resistor R3 connected in parallel with the first capacitor C1, one end of which is connected to the other end of the second resistor, and the other end of which is connected to the second resistor.
A light emitting element 43 is commonly connected to the other end of the capacitor C2, and a light receiving element 44, which is electrically insulated from the light emitting element 43 and receives light from the light emitting element 43, is connected in parallel to the output side of the light receiving element 44. 3rd to be done
A series circuit consisting of a capacitor C3, a fourth and a fifth resistor R4 and R5 that divide the output from both ends of the third capacitor C3, and a transistor 45 driven by the divided voltage output from both ends of the fifth resistor R5. A load detection device characterized in that the resistance value of the first resistor R1 is set larger than the resistance value of the second resistor R2.