JPH0476249B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to an integrated circuit for a non-contact detection switch such as a photoelectric switch incorporating a non-contact detection circuit.

Such integrated circuits are desired to operate at high speed and with low current consumption depending on their intended use, such as a DC three-wire system or an AC two-wire system.

Here, in the AC two-wire system, a load is connected in series between a power supply terminal and a power supply, and power is supplied to the detection circuit via the load. Therefore, the operating current during detection standby must be sufficiently small so that the load does not operate. On the other hand, regarding the response speed, since the load itself is slow (a load with a slow response speed is used so as not to operate due to ripples on the commercial frequency), a speed that follows this may be sufficient. On the other hand, in the DC three-wire system, the load is connected to an output-only terminal prepared independently of the power supply terminal, so power is supplied to the detection circuit separately from the load. For this reason,
The operating current during detection standby does not necessarily have to be small; rather, it is necessary to supply sufficient current to the detection circuit in order to operate the load at high speed.

[Prior art and its problems]

In this type of non-contact detection switch, before integration (IC) was implemented, most circuits were constructed using individual elements, selecting elements according to the application, so there were demands for operating speed and current consumption. I was able to meet the requirements. In recent years, the demand for smaller detection switches has increased, and the need for ICs has arisen.
Since developing an IC requires a huge amount of cost and time, if one type of IC can be used for both DC 3-wire and AC 2-wire systems, an inexpensive detection switch can be provided.

However, in a bipolar integrated circuit suitable for a detection circuit, higher speed and lower current consumption are contradictory demands and have been considered difficult in principle. Therefore, in conventional AC two-wire applications, current consumption is reduced by not supplying power to circuits that are only necessary for the DC circuit, such as power transistor drive circuits, and by not allowing unnecessary current to flow. However, since it is not possible to reduce the current in the part necessary for detection, there is a limitation in increasing the functionality of the circuit, and there is a drawback that sufficient functionality cannot be provided.

[Purpose of the invention]

The purpose of this invention is to solve the above problems,
Achieves higher speed or lower current consumption depending on the application,
It is an object of the present invention to provide an integrated circuit for a non-contact detection switch that can be applied to either a DC 3-wire type or an AC 2-wire type.

[Key points of the invention]

The present invention includes a power supply circuit 3 connected to power supply terminals 101 and 103, and an input to an output drive input terminal 105.
an output circuit 4 connected to the base of an output transistor 5 whose output is connected to an output terminal 102; and a detection circuit 2 having an output terminal 104;
It has an integrated circuit including a current consumption switching circuit 11 whose input is connected to a power supply circuit output terminal 106 and a detection circuit power supply terminal 107 and whose output is connected to the detection circuit 2, and the current consumption switching circuit 11 is connected to the power supply circuit 3. The present invention is characterized in that the current supplied to the detection circuit 2 is switched in accordance with the input voltage of the detection circuit 2.

[Embodiment of the Invention] FIG. 1 shows an embodiment of the invention, which is applied to a photoelectric switch. As shown in FIG. 1, the integrated circuit 1 includes a detection circuit 2, a power supply circuit 3, an output drive circuit 4, an output transistor 5, and a current consumption switching circuit 11. Power supply terminal 1 of integrated circuit 1
A power supply is connected to 03 and 101, a constant voltage suitable for detection is generated by power supply circuit 3, and this constant voltage is supplied to detection circuit 2 via terminals 106 and 107. The current consumption switching circuit 11 controls the current consumption of the detection circuit 2 from both terminals 106 and 107. FIG. 3 shows an example in which the injector current of the I ² L type transistor included in the detection circuit 2 is switched by the consumption current switching circuit 11.

In the configuration shown in FIG. 1, when a voltage from a power source is applied to power supply terminals 103 and 101, power supply circuit 3 applies a stable voltage suitable for detection by detection circuit 2 to terminal 106. The terminal 106 is connected to a terminal 107 outside the integrated circuit 1, and the voltage from the power supply circuit 3 is supplied to the detection circuit 2, and at the same time, the power supply circuit 3 serves as a power source for the light receiving section consisting of the phototransistor 10 and the resistor 9. .

The detection circuit 2 applies a pulse signal from an internal pulse generation circuit to the base of the transistor 6 through a terminal 108. Transistor 6 is connected to power supply terminal 103
It receives a power supply voltage from the detector circuit 2, and upon receiving a pulse signal from the detection circuit 2, applies a light emitting pulse current to the LED 8 via a resistor 7. The LED 8 converts the emitted light pulse current into light. The light from the LED 8 is received by a phototransistor 10, and the light reception signal from the phototransistor 10 is input to the detection circuit 2, where the connection between the LED 8 and the phototransistor 10 is interrupted by something. It is determined whether or not the signal has been detected, and the result is outputted to the terminal 104 as a detection output.
Terminals 104 and 105 are connected by an external circuit. The detection output from the detection circuit 2 is at the terminal 104.
and 105 to the output drive circuit 4, and the output transistor 5 is controlled by the output drive circuit 4. The current consumption switching circuit 11 has a configuration as shown in FIG.
6 are connected to the detection circuit 2 through resistors 111 and 112, respectively. In the example shown in FIG. 3, part or all of the detection circuit 2 is composed of an I ₂ L type transistor, and the injector current of this transistor is supplied from the power supply circuit 3 through resistors 111 and 112.

In an I ₂ L-type transistor, part of the injector current provides the base current of the transistor, and if the injector current is large, stray capacitance, junction capacitance, etc. can be charged quickly, so the operation transfer time of the transistor is Becomes shorter. Therefore, in the embodiment of FIG. 1, since the injector current is supplied to the transistor from both terminals 107 and 106, the detection circuit 2 can operate at high speed in response to photodetection.

FIG. 2 shows an example in which the integrated circuit 1 of FIG. 1 is applied to an AC two-wire photoelectric switch. In Figure 2,
Since the terminal 103 is not connected, the power supply circuit 3 (not shown) in the integrated circuit 1 does not generate an output and the terminal 1
Another power supply circuit having a transistor 16, a resistor 17, and a Zener diode 18 is supplied as power to the detection circuit 2 through 07. capacitor 19
is for taking ripples from the power supply. The AC side of the rectifier bridge 12 has terminals 201 and 202 to which the series circuit of AC power supply and load is connected.
It is connected to the. Further, on the DC output side of the rectifier bridge 12, the power supply circuit and a series circuit of a thyristor 13 and a Zener diode 14 are connected in parallel. The gate of the thyristor 13 is connected to the detection output terminal 104 of the detection circuit 2, and the thyristor 13 is turned on when there is a detection output.

In such a configuration, since there is no output from the power supply circuit 3, the injector current is supplied to the detection circuit 2 only through the terminal 107 and the resistor 111.
Therefore, in this example, since the injector current is small, the light detection response speed of the detection circuit 2 is slow.
However, since the power consumption of the detection circuit 2 is kept low, the current flowing through the load when the thyristor 13 is off (no detection output from the detection circuit 2) is sufficient compared to the operating current of the load. It can be set to a small value.

〔Effect of the invention〕

As described above, according to the present invention, the power supply circuit 3 is connected to the power supply terminals 101 and 103, and the output transistor 5 whose input is connected to the output drive input terminal 105 and whose output is connected to the output terminal 102.
Output circuit 4 connected to the base of
04, and a current consumption switching circuit 11 whose input is connected to the power supply circuit output terminal 106 and the detection circuit power supply terminal 107 and whose output is connected to the detection circuit 2. The current switching circuit 11 switches the current supplied to the detection circuit 2 in response to the input voltage of the power supply circuit 3, so that the current consumption and operating speed can be freely selected to create integrated circuits for switches with different characteristics. As a result, the same IC can be used for circuit configurations depending on the application, such as a DC 3-wire system or an AC 2-wire system.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing a DC 3-wire photoelectric switch as an embodiment of the present invention, FIG. 2 is a circuit diagram showing an AC 2-wire photoelectric switch as another embodiment of the invention, and FIG. The figure shows a detection circuit using an I ² L type transistor. DESCRIPTION OF SYMBOLS 1... Integrated circuit for detection switch, 2... Detection circuit, 3... Power supply circuit, 4... Output drive circuit, 5...
...Output transistor, 6...Transistor, 7...
...Resistor, 8...LED, 9...Resistor, 10...Phototransistor, 11...Current consumption switching circuit,
11... Rectifier bridge, 13... Thyristor, 1
4...Zue diode, 15...Resistor, 16...
...Transistor, 17...Resistor, 18...Zener diode, 19...Capacitor, 101,1
02... Integrated circuit power supply terminal, 103... Integrated circuit output terminal, 104... Integrated circuit detection circuit output terminal, 105... Integrated circuit output drive input terminal, 10
6...Integrated circuit power supply circuit output terminal, 107...Integrated circuit detection circuit power supply terminal, 108...Integrated circuit pulse output terminal, 109...Integrated circuit light receiving input terminal, 201, 202...AC two-wire photoelectric switch terminal.

Claims (1)

[Claims] 1 a power supply circuit 3 connected to power supply terminals 101 and 103; an output circuit 4 connected to the base of an output transistor 5 whose input is connected to the output drive input terminal 105 and whose output is connected to the output terminal 102;
A detection circuit 2 having an output terminal 104, whose inputs are a power supply circuit output terminal 106 and a detection circuit power supply terminal 107.
The current consumption switching circuit 11 has a current consumption switching circuit 11 connected to the power supply circuit 3 and having an output connected to the detection circuit 2. An integrated circuit for a non-contact detection switch, characterized in that the supplied current is switched.