JPS5875724A - Electronic device with input stage having binary output coupled to relay circuit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a binary output coupled to a relay control circuit that deenergizes the relay during one state of the output signal and energizes the relay during the other state of the output signal. The present invention relates to an electronic device comprising an input stage having an input stage.

It is already known to operate relays directly with the effective supply voltage. However, from the table, the maximum voltage tolerance is at most about ±20q6, and voltages smaller than this voltage tolerance will not drive the relay, and voltages that exceed the tolerance range will cause problems such as thermal overload. There is.

Relays were also operated via voltage regulators with large tolerances. However, these known circuits
If the fluctuation range of the power supply voltage is wide, the power loss caused by the voltage regulator becomes extremely large, which is completely uneconomical. By way of example, this power loss can reach up to about 5.5 WtfC, which is no longer acceptable for the small device for which the invention is primarily intended here.

It is also already known to connect a relay to a mains voltage having a wide range of tolerances via a switching and regulating power supply. However, this type of circuit has a poor space factor and is expensive, making it unusable for very small devices.

The electronic device to which the invention is particularly directed is, by way of example, a compact light barrier device, which itself can activate a monitoring relay depending on whether the light beam is interrupted or not. An existing one that generates an output signal or 0t as controlled by the output signal may be used.

The present invention provides a low-loss relay control device for a wide DC power supply voltage range, for example from 55V to 370V. Therefore, the AC voltage required for this purpose varies from 42V-20% of AC to 24V prior to rectification.
It is within the range up to 0V+1on.

Therefore, the basic main objective of the present invention is to provide a relay with minimal power consumption and small space occupancy, without the risk of overloading or dropping out of the relay.
It is an object of the present invention to provide an electronic device that can handle a very wide range of power supply voltages.

In order to satisfy this purpose, the original F! A#'i, the output of the input stage is coupled via an electronic threshold switch to the control electrode of a semiconductor switching element, in particular a transistor, which determines the current flowing through the relay, the threshold switch being dependent on the current flowing through the relay; is periodically switched such that the semiconductor switching element is alternately conductive and non-conductive such that the relay is periodically energized with a continuously increasing current from zero. It is intended to be cut off every time a given current of , . . .

This arrangement preferably provides that a voltage corresponding to the current flowing through the relay is tapped off by a resistor in the energizing circuit of the relay;
Start by making sure that it is sent to the input of the threshold switch.

The output of the input stage is coupled to the input of the threshold switch via a second resistor. The capacitor and this second resistor are RCN
form a road. The input voltage of the threshold switch is set before the average value of the current flowing through the relay falls below the holding current value.
The capacitor and resistor time constants are selected so that the switching threshold is also reduced.

The diode is coupled in parallel to the relay in a direction opposite to the forward direction of the semiconductor switching element.

After the relay is disconnected from the power supply voltage, the energy stored in the relay's magnetic field flows through the diode. In this way, the average value of the current flowing through the relay is buffered so that it does not fall below the holding current.

The threshold switch used by the invention is preferably a Schmitt trigger circuit.

- A separate diode is coupled to a line extending from the resistor to carry the relay current and has a polarity such that current can flow from the resistor to the input of the threshold switch and/or the charging capacitor. There is.

The transistor is typically a 32% transistor.

A first practical embodiment is such that the semiconductor switching element is coupled in series with a relay, the relay being arranged between the collector of the transistor as the semiconductor switching element and the high voltage. In this configuration, a resistor through which relay current flows is coupled between the emitter of the semiconductor switching element and ground.

Another embodiment is that the emitter of the semiconductor switching element is grounded, the collector is coupled to the high voltage via a voltage divider, and the relay is coupled to the high voltage via a transistor of the opposite conductivity type, i.e. p%p. , p? It is assumed that the base of the lp transistor is at the dividing point of the voltage divider.

According to the invention, the energizing current of the relay is switched on and off periodically via the transistor 10, so that the relay is always kept in operation but never overloaded.

Embodiments of the present invention will be described below with reference to the accompanying drawings.

The known four input stages /1 can be, for example, optical barrier devices or optocouplers. The input stage l/ can be formed using MOB technology and has low power consumption as is well known, so that it can be used by dropping a high supply voltage using a dropping resistor.

As shown in Figure 1, either signal 0 or signal 0 is
For example, it appears at the output IP of the input stage depending on whether the disturbance is to the rays in the light barrier or not. The output /f can be either grounded as shown or coupled to a voltage derived from the supply voltage and regulated through a resistor and a Zener diode. It can be equally parsimoniously shown as one pole of a combinable switch arm 3.

Input of Schmitt trigger circuit/co/r is resistor -/l
- coupled to the output via λO. The output of the Schmitt trigger circuit is applied through another resistor 26 to the npn transistor ≠ pace. The transistor is inserted into the energizing circuit of relay/j, which is coupled at one end to a DC power supply voltage, for example from 35v to 570v. relay/
The other pole of j is coupled to the collector of transistor /44. The emitter of transistor≠ is grounded via resistor 16. The connection point between the emitter of transistor q and resistor 16 is connected to a capacitor ! which is grounded at its other terminal. ? -/717) One terminal is coupled to the input/r of the Schmitt trigger circuit l via a diode with the polarity shown. A DC power supply voltage of 55V to 570V is provided by an input rectifier core to which AC voltages of 42V-201 to 240V+20- can be applied. One output terminal of the rectifier core is grounded in the manner shown. The capacitor t between the DC power supply voltage and the ground is for smoothing. The operation of the first illustrated circuit is as follows.

When the light beam of the light barrier device is not interrupted, the switch arm 3 at the output of the input stage of the electronic device of the invention is equivalently shown to be in the upper switching position as shown. In this case, a positive voltage is coupled through resistor 20 to the input /r of the Schmitt trigger circuit /co. This causes the Schmitt trigger circuit to be in the lower switch position, non-conducting through the transistor /<4t'' pace/3f, and presenting a sufficiently low voltage at its output that no current flows through the relay is. , when the switch arm 3 of the input stage /l is equivalently in the upper switching position, relay /j enters the dropout state when an obstacle of 4.6 degrees enters the light beam of the optical barrier device. The switch arm 3 is equivalent to being switched to the lower position shown in the figure, and the output 15' of the input stage /1 becomes the ground potential.The input /1 of the Schmitt trigger circuit /1
As a result of the sudden change in voltage thus occurring at is sent, switching transistor /V into a conductive state. Along with this, the transistor main current also increases continuously and flows through relay /j and resistor /6.

The current flowing through resistor 16 creates an increasing voltage across this resistor, which is then applied to the capacitor via the diode.
7t-Charge. As a result, the voltage at the input /l of the Schmitt trigger circuit /l increases continuously until it exceeds the switching threshold of the Schmitt trigger circuit /l. Eventually, the output of the Schmidt trigger circuit switches from a high state to a low state, but the switch arm 23 is still maintained equivalently at ground. Transistor/Hiro is cut off due to the output reversal of circuit l, and relay/j and resistor 1
6 is interrupted. However, at this time, a back electromotive force is generated in relay /j, and relay l! A magnetic field is maintained through the diode for a specified period of time so as to maintain the device in operation.

At this time, the time constant of the resistor 16 and the capacitor 17 is the same as that of the relay/! when the current flowing through the resistor 16 is interrupted.
The voltage at the input −/≠−/l of the Schmitt trigger circuit 1 falls below the switching threshold of the Schmitt trigger circuit 1 before the current flowing through the circuit falls below a predetermined average value. In this way, current flows through transistor /4C again, and relay /j#'J is eventually maintained in the operating state.

In other words, the capacitor /7 discharges through the resistor λ01 switch arm = 3 in the event of a current interruption, but the discharge occurs quickly enough to prevent an actual dropout of the relay /j. .

In this way, as a result of the automatic regulation of the current flowing through the relay /j according to the invention, the relay does not cause either overload or dropout when the switch arm 3 is grounded, and the relay can be adjusted in eg 10 steps. It can be operated at voltages ranging from 55V to 570V. Even if the power supply voltage is large,
This circuit arrangement automatically disconnects the relay from the supply voltage when the current flow reaches a predetermined magnitude. The subsequent interruption is so short that the relay is forced to
It remained operational during this time. The above-described sequence of operations is repeated continuously.

During the switching interval, relay lj is kept active with the magnetic energy stored by the current.

The period during which the transistor l≠ is active therefore depends, inter alia, on the inductivity of the relay /r and on the instantaneously propagating operating voltage. The duration of current flow is determined by a constant preselected time constant of capacitor /7 and resistor -0.

The switching interval may be constant because, similar to the inductive nature of the relay, the peak current of the relay remains constant for any drive voltage.

Another aspect of holding the effective relay drive current constant for different drive voltages is shown in FIG. 2, in which like numerals indicate parts corresponding to corresponding parts of FIG. .

In FIG. 2, the circuit has a transistor stator whose emitter is coupled to a high drive voltage. Relay lj with parallel-coupled diode tf, transistor? is coupled to the collector of , and grounded via resistor /6. The collector of the switching transistor /4I is coupled to a high voltage via a voltage divider consisting of a resistor 30,3/, and the emitter of the switching transistor is grounded.

The connection point between resistors 3θ, 3/ is 'I)nT) ) Langistacho? Combined with the pace of.

In this way, a continuously rising and falling voltage appears across the sensor resistor 16 depending on the duty cycle of the switching transistor /l.

The rising voltage corresponds to the phase of current flow due to the conducting state of the transistor l≠, and the falling voltage corresponds to the blocking state of the transistor /4<. The current flowing through the free-running diode is again an important factor.

It is also possible to replace the circuit/co with a trigger circuit having two inverting inputs in the AND logic circuit, in which case the feedback voltage is applied to the two inputs of the trigger circuit, and the switching voltage is transferred via the diode coco of the trigger circuit. If the hysteresis of this trigger circuit is selected so that the lowest voltage across resistor 16 turns off the transistor string and the lowest voltage across resistor 76 turns on the transistor string again. , Similarly, the average current flowing through the relay can be held constant regardless of the driving voltage. The switching frequency is determined by the inductance of the relay/j and the instantaneously propagating operating voltage.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a first embodiment of the electronic device of the present invention, and FIG. 2 is a circuit diagram of another embodiment.
l is the Schmitt trigger circuit, lv is the outer P? l) transistor, ij is a relay, /6. -〇 is the resistor, /7 is the capacitor, lr is the input of the Schmitt trigger circuit, /P is the output of the input stage, col, here is the diode, and bump is the put
) transistor, 30. J/ indicates the resistor of the voltage divider. Continued from page 1 Priority claim @February 8, 1982 ■West Germany (DE)
■P 3204234.5 @Inventor Hartmut Knappeduis Federal Republic of Germany 7830 Emmendingen Biesenstrasse 124 109-

Claims (1)

Claims: (1) A binary input stage output coupled to a relay control circuit that deenergizes the relay in one output signal state and energizes the relay in another output signal state. In an electronic device comprising an input stage with an output. The output of the spinning input stage is coupled via an electronic threshold switch to a control electrode of a semiconductor switching element that determines the current flow through the relay. The threshold switch is periodically switched depending on the current flowing through the relay, whereby the semiconductor switching element becomes alternately conductive and non-conductive, thus causing the relay to become conductive and non-conductive. It is characterized in that it is energized periodically with a continuously increasing current from zero, is cut off every time a predetermined current is reached, and is energized again with an increasing current shortly before cord dropout. electronic device. (2. The electronic device according to claim 1, wherein a voltage corresponding to the current passing through the relay is tapped off by a resistor in the energizing circuit of the relay and sent to the input of the threshold switch. (3) The electronic device according to claim 1 or 2, wherein the output of the input stage is connected to the input of the threshold switch via a second resistor. (4) The electronic device according to claim 5, wherein a capacitor is coupled to the second resistor to form an RC circuit. (5) An electronic device according to claim 4, characterized in that the capacitor is connected such that the voltage at the input of the threshold switch falls below the switching threshold before dropout of the relay. and a resistor. (6) In the electronic device according to any one of claims 1 to 5, the diode is , an electronic device characterized in that it is coupled in parallel to a relay in a direction opposite to the forward direction of a semiconductor switching element. In an electronic device, the threshold switch is
An electronic device characterized in that it is a Schmitt trigger circuit. (8) In the electronic device according to any one of claims 2 to 7, the polarity is such that a laminar flow can flow from the first resistor to the input of the threshold switch and/or the capacitor. and a second diode is disposed in a line from the first resistor that holds a relay current. (9) Any one of claims 1 to 8. An electronic device according to one item, in which the transistor has %p
%) An electronic device characterized by being a transistor. (g) In the electronic device according to any one of claims 1 to 9, the semiconductor switching element is coupled in series with a relay, and the relay is connected to the collector of the semiconductor switching element in series. An electronic device characterized in that it is disposed between a voltage. al. In the electronic device according to any one of claims 2 to 10, the first resistor for holding the relay current is disposed between the emitter of the semiconductor switching element and ground. An electronic device featuring: (6) In the electronic device according to any one of claims 1 to 8, the emitter of the semiconductor switching element is grounded, and the collector is j − coupled to a high voltage via a voltage divider. , the relay is coupled to a high voltage through a semiconductor switching element of opposite conductivity type. An electronic device characterized in that a separate semiconductor switching element is located at a dividing point of the voltage divider.