JP2003016898A - Relay drive circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a relay drive circuit, capable of applying a starting voltage to a relay using an inexpensive power source with small capacity and minimizing the heating loss. SOLUTION: In this relay drive circuit, a coil RY 1 of the relay is excited/ non-excited by turning on/off of a first switching element 27 connected serially to the coil RY1. This circuit comprises a serial circuit of a capacitor 25 and resistor 26 connected, in parallel with the serial circuit of the coil RY1 and the first switching element 27; a diode 24 normally connected in series with both the serial circuits; and a second switching element 22 for turning on/off between the anode of the diode 24 and the cathode of the capacitor 25. The second switching element 22 is turned ON, simultaneously with the turning on of the first switching element 27, whereby the discharge voltage of the capacitor 25 is applied to the driving voltage of the coil RY1 of the relay.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a relay drive circuit for energizing / de-energizing a relay coil by turning on / off a switching element connected in series to the relay coil.

[0002]

2. Description of the Related Art FIG. 9 is a circuit diagram showing a configuration of a "relay drive circuit" disclosed in Japanese Patent Laid-Open No. 61-259426. The drive circuit of this relay includes a series circuit of a coil 2 of the relay and an NPN transistor 3, an electrolytic capacitor 8 connected in parallel to the series circuit, a diode 7 reversely connected in parallel to the coil 2, and a transistor 3. A resistor 6 connected between the base and the emitter, a resistor 9 connected between the anode of the electrolytic capacitor 8 and the anode of the DC power supply 1, a resistor 5 having one terminal connected to the base of the transistor 3, and a resistor 5 And a switch 4 having one terminal connected to the other terminal, the other terminal of the switch 4 is connected to the anode of the DC power supply 1, and the emitter of the transistor 3 and the cathode of the electrolytic capacitor 8 are the cathode of the DC power supply 1. It is connected to the.

In the relay drive circuit having such a configuration,
When the switch 4 is off, the electrolytic capacitor 8 is charged by the current i ₂ from the DC power source 1 through the resistor 9. When the switch 4 is turned on, the DC power supply 1
Is divided, and the transistor 3 is turned on by the divided voltage. When the transistor 3 is turned on, a relatively large discharge current i ₃ flows from the electrolytic capacitor 8 to the coil 2 to excite the coil 2 and activate the relay.

When the discharge current i ₃ flows from the electrolytic capacitor 8 and the discharge voltage becomes lower than the voltage of the DC power source 1,
A relatively small current from the DC power supply 1 limited by the resistor 9 flows through the coil 2, but after the relay is activated,
Since the driving state is maintained with a relatively small current, the resistance 9
The relay can be started and the drive state can be maintained with a relatively small current limited by, and power consumption can be reduced.

FIG. 10 is a circuit diagram showing a configuration of a "relay drive device" disclosed in Japanese Patent Laid-Open No. 61-93530. This relay drive device includes a relay coil 1
3, the parallel circuit of the capacitor 15 and the resistor 14, the switch 12, and the DC power supply 11 are connected in series.

In the relay drive device having such a configuration, when the switch 12 is turned on, a relatively large charging current of the DC power source 11 for the capacitor 15 flows through the coil 13,
The coil 13 is excited to activate the relay. Capacitor 1
5 is fully charged, the DC power supply 1
A relatively small current due to 1 flows through the coil 13 to maintain the drive state of the relay. When the switch 12 is turned off,
The current stops flowing in the coil 13, and the coil 13 is de-excited. The charge accumulated in the capacitor 15 is stored in the resistor 14
Is gradually discharged through. As a result, the relay can be driven by the DC power supply and the switch having a small current capacity.

[0007]

In the conventional relay drive circuit and relay drive device as described above, it is necessary to provide a power source that outputs a voltage higher than the starting voltage at which the coil is excited and the relay can be started. Even if the voltage from the commercial power supply drops a little, the power supply needs to have the starting voltage of the relay, so there is a margin in the capacity, which causes heat loss from parts at rated input. There was a problem. The present invention has been made in view of the circumstances as described above, and an object thereof is to provide a relay drive circuit that can apply a starting voltage of a relay with a small-capacity and inexpensive power supply circuit and has a small heat generation loss. And

[0008]

A relay drive circuit according to the present invention is a relay drive circuit for turning on / off a first switching element connected in series to a coil of a relay to turn the coil on / off. In, a series circuit including a capacitor and a resistor connected in parallel to a series circuit including the coil and the first switching element, a diode connected in series to both series circuits in series, and an anode of the diode and a cathode of the capacitor are connected. A second switching element to be turned on / off is provided, and when the first switching element is turned on, the second switching element is turned on at the same time, so that the discharge voltage of the capacitor is added to the drive voltage of the coil. It is characterized by being added.

In this relay drive circuit, the relay coil is energized / de-energized by turning on / off the first switching element connected in series to the relay coil. A series circuit including a capacitor and a resistor is connected in parallel to a series circuit including the coil and the first switching element,
A diode is connected in series to both of these series circuits, and a second switching element turns on / off between the anode of the diode and the cathode of the capacitor. When the first switching element is turned on, the second switching element is simultaneously turned on to add the discharge voltage of the capacitor to the drive voltage of the coil. This makes it possible to apply the starting voltage of the relay with a small-capacity inexpensive power supply circuit, and to realize a relay drive circuit with a small heat generation loss.

The relay drive circuit according to the present invention further comprises a third switching element for turning on / off the second switching element, and connecting the control terminals of the first switching element and the third switching element to each other. It is characterized by being present.

In this relay drive circuit, the third switching element turns on / off the second switching element, and the control terminals of the first switching element and the third switching element are connected to each other. The power supply circuit can apply the starting voltage of the relay, and it is possible to realize a relay drive circuit with little heat loss.

The relay drive circuit according to the present invention is further characterized by further comprising a switching circuit for switching whether or not to operate the second switching element.

In this relay drive circuit, the switching circuit can switch whether or not to operate the second switching element. Therefore, when the frequency of the commercial power supply is 50 Hz, which is apt to cause a voltage shortage, the coil drive voltage is reduced. Can be switched so as to apply the discharge voltage of the capacitor to the relay drive circuit, which can apply the starting voltage of the relay with a small-capacity inexpensive power supply circuit, and realize a relay drive circuit with a small heat generation loss.

In the relay drive circuit according to the present invention, the detection means for detecting the drive voltage and the time for turning off the second switching element and charging the capacitor according to the drive voltage detected by the detection means. Is further provided, and the means is adapted to increase or decrease the discharge voltage by increasing or decreasing the time.

In this relay drive circuit, the increasing / decreasing means increases or decreases the time for turning off the second switching element and charging the capacitor in accordance with the drive voltage detected by the detecting means, and by increasing or decreasing the time, the capacitor is increased or decreased. Since the discharge voltage of the relay is raised or lowered, the relay drive voltage can be applied without increasing the discharge voltage of the capacitor more than necessary, and the start voltage of the relay can be applied with a small-capacity, inexpensive power supply circuit, and heat loss is small. Can be realized.

The relay drive circuit according to the present invention is a relay drive circuit for energizing / de-energizing a coil by turning on / off a first switching element connected in series to a coil of the relay. And the first
A second series circuit to be turned on / off between a series circuit including a capacitor and a resistor connected in parallel to a series circuit including a switching element, a diode connected in series to both series circuits, and an anode of the diode and a cathode of the capacitor. A switching element, the first switching element and a second
A means for simultaneously turning on the switching elements, a detection means for detecting the drive voltage of the coil, and a means for determining the level of the drive voltage detected by the detection means and the predetermined voltage, the means being provided If it is determined that it is lower,
It is characterized in that the discharge voltage of the capacitor is added to the drive voltage of the coil by simultaneously turning on the first switching element and the second switching element.

In this relay drive circuit, the relay coil is energized / de-energized by turning on / off the first switching element connected in series to the relay coil. A series circuit including a capacitor and a resistor is connected in parallel to a series circuit including the coil and the first switching element,
Diodes are connected in series in both series circuits.
The means for the second switching element to turn on / off between the anode of the diode and the cathode of the capacitor to turn on is
The first switching element and the second switching element are simultaneously turned on. The detecting means detects the drive voltage of the coil, and the determining means determines the level of the detected drive voltage and the predetermined voltage. When the determining means determines that the drive voltage is lower, the first switching element and the second switching element
By simultaneously turning on the switching elements, the discharge voltage of the capacitor is added to the drive voltage of the coil.

This prevents unnecessary current from flowing and also
It is possible to apply a starting voltage of a relay with a small-capacity inexpensive power supply circuit and realize a relay drive circuit with a small heat generation loss.

Further, the relay drive circuit according to the present invention is characterized by further comprising means for turning on the second switching element periodically or at any time when the first switching element is turned on.

In this relay drive circuit, when the first switching element is on, the means for turning it on is the second
Since the switching element is turned on periodically or at any time,
Even if the drive voltage drops after the relay has started, and the relay cannot be held and goes into a non-drive state, the relay can be restarted and restored, and a small-capacity inexpensive power supply circuit It is possible to apply the starting voltage of the relay, and it is possible to realize a relay drive circuit with little heat loss.

Further, the relay drive circuit according to the present invention is characterized in that the resistance also serves as a bleeder resistance for suppressing a voltage rise when the coil is not excited.

In this relay drive circuit, the resistance also serves as a bleeder resistance for suppressing the voltage rise when the coil of the relay is de-excited, so that the voltage rise is suppressed when the coil is de-energized. In addition, it is possible to apply the starting voltage of the relay with a small-capacity and inexpensive power supply circuit, and it is possible to realize a relay drive circuit with a small heat generation loss.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings showing the embodiments thereof. Embodiment 1. Figure 1
FIG. 1 is a circuit diagram showing a configuration of a first embodiment of a relay drive circuit according to the present invention. In this relay drive circuit, the collector of an NPN transistor 27 (first switching element) is connected to one terminal of a coil RY1 of a relay having a relay contact ry1, and the emitter of the transistor 27 is connected to the cathode terminal of a DC power supply circuit 21. Has been done. A resistor 40 is connected between the base and the emitter of the transistor 27. The other terminal of the coil RY1 is connected to the anode terminal of the DC power supply circuit 21 through the diode 24 which is connected in the forward direction.

The cathode of the diode 24 is connected to the anode of the electrolytic capacitor 25 (capacitor), and the cathode of the electrolytic capacitor 25 is connected to the DC power supply circuit 2 through the resistor 26.
1 is connected to the cathode terminal. The emitter of the PNP transistor 22 (second switching element) is connected to the anode of the diode 24, and the collector of the transistor 22 is connected to the cathode of the electrolytic capacitor 25. A resistor 41 is connected between the emitter and the base of the transistor 22, and the base of the transistor 22 is connected to the collector of the NPN transistor 23 (third switching element) through the resistor 42. The transistor 23 is provided to convert the output voltage of the DC power supply circuit 21 into the operating voltage of the transistor 22.

The emitter of the transistor 23 is connected to the cathode terminal of the DC power supply circuit 21, and the resistor 44 is connected between the base and the emitter of the transistor 23. The base of the transistor 23 is connected to one terminal of the switch 28 (switching circuit) through the resistor 43, the other terminal of the switch 28 is connected to the base of the transistor 27 through the resistor 39, and the other terminal of the switch 28. Is supplied with a control signal of the coil RY1.

The DC power supply circuit 21 is composed of AC 100V, 50
A commercial power supply 30 of Hz or 60 Hz is supplied to the diode bridge 32 through the capacitor 31. The commercial power supply 30 supplied to the diode bridge 32 is rectified, smoothed by the smoothing capacitor 29, and output from between the anode terminal and the cathode terminal.

The operation of the relay drive circuit having such a configuration will be described below. When switch 28 is on, when transistor 27 is off, coil RY1 is also de-energized, transistor 23 is off, and transistor 22 is off. At this time, the diode 24
Also, the electrolytic capacitor 25 is charged through the charging resistor 26.

When an ON signal is applied to the bases of the transistors 27 and 23 as a control signal,
The transistor 27 and the transistor 23 are turned on, and the transistor 22 is also turned on.
The anode voltage of 1 is applied to the cathode terminal of the electrolytic capacitor 25, and the electrolytic capacitor 25 is rapidly discharged through the coil RY1 and the transistor 27. At this time, the discharge voltage of the electrolytic capacitor 25 is added to the anode voltage of the DC power supply circuit 21, which is the drive voltage of the coil RY1, so that the anode voltage of the DC power supply circuit 21 becomes the starting voltage at which the relay of the coil RY1 can be started. The relay of coil RY1 can be activated even if it is lower.

After the electrolytic capacitor 25 is discharged, the anode voltage of the DC power supply circuit 21 passes through the diode 24,
It is applied to coil RY1 and its relay is held. The holding voltage after the relay is activated may be significantly lower than the activation voltage. When the transistor 27 is turned off, the coil RY1 is also de-energized, the transistor 23 is also turned off, and the transistor 22 is also turned off. At this time, the electrolytic capacitor 25 is charged through the diode 24 and the charging resistor 26.

The anode voltage of the DC power supply circuit 21 is the coil RY.
A voltage shortage that is lower than the starting voltage of the relay of No. 1 is likely to occur when the frequency of the commercial power source 30 is 50 Hz, so in an area where the frequency of the commercial power source 30 is 50 Hz,
If the switch 28 is turned on, the relay of the coil RY1 can be activated even when the commercial power supply has insufficient voltage. In an area where the frequency of the commercial power source 30 is 60 Hz, by turning off the switch 28, it is possible to prevent unnecessary current from flowing.

Embodiment 2. FIG. 2 is a circuit diagram showing the configuration of the second embodiment of the relay drive circuit according to the present invention.
In this relay drive circuit, a voltage dividing circuit (detection means) made up of resistors 35 and 36 is connected between an anode terminal and a cathode terminal of the DC power supply circuit 21, and this voltage division corresponds to that of a microcomputer constituting a control unit 37. , Analog voltage read port provided.

The control section 37 is a control section of the electric equipment in which the relay drive circuit is incorporated, and the operation section 3 of the electric equipment.
8 is connected, and an operation signal from the operation unit 38 is given. The control unit 37 is connected to the bases of the transistor 27 and the transistor 23 through the resistors 39 and 43, respectively, and supplies the control signals to the transistors 27 and 23, respectively. Other configurations are
Configuration of the relay drive circuit described in the first embodiment (FIG. 1)
Therefore, the same reference numerals are given to the same portions and the description thereof will be omitted.

The operation of the relay drive circuit will be described below with reference to the flowchart of FIG. 3 showing the operation. For example, when the operation unit 38 is operated and the relay of the coil RY1 is activated in response to the operation of the operation unit 38, the control unit 37:
First, the divided voltage of the voltage dividing circuits 35 and 36 is read (S
2) It is determined whether the read voltage is lower than a predetermined voltage (S4). The predetermined voltage described here is a voltage obtained by multiplying the predetermined voltage described in the claims by the voltage division ratio of the voltage dividing circuits 35 and 36, whereby the drive voltage of the coil RY1 (the DC power supply circuit 21 It is possible to determine whether or not the output voltage) is lower than the predetermined voltage described in the claims. This predetermined voltage is set to be equal to or slightly higher than the starting voltage capable of starting the relay of the coil RY1.

When the read voltage is lower than the predetermined voltage (S4), the control section 37 simultaneously turns on the transistor 27 (first switching element) and the transistor 22 (second switching element) (S6). To return. The transistor 22 is the transistor 23 (third
It can be turned on / off by turning on / off the switching element). As a result, the coil RY
When the drive voltage applied to 1 is lower than the predetermined voltage,
The discharge voltage of the electrolytic capacitor 25 can be added to the drive voltage to activate the relay of the coil RY1. The holding voltage after the relay of the coil RY1 is activated may be considerably lower than the activation voltage.

When the read voltage is not lower than the predetermined voltage (S4), the controller 37 turns on only the transistor 27 (first switching element) (S8) and returns. As a result, when the drive voltage applied to the coil RY1 is not lower than the predetermined voltage, the relay of the coil RY1 can be activated only by the drive voltage. Other operations are the same as the operations of the relay drive circuit described in the first embodiment, and therefore the description thereof will be omitted.

The frequency of the commercial power source 30 is taken into the control unit 37 to determine whether the frequency is 50 Hz or 60 Hz. If the frequency is 50 Hz, the transistor 23 is activated to change the frequency. 60Hz
If it is, it is possible to make the transistor 23 inoperative. Further, the above-described operation (flowchart in FIG. 3) can be performed by hardware using the voltage detection element without using the control unit 37 (microcomputer).

Embodiment 3. FIG. 4 is a circuit diagram showing the configuration of the third embodiment of the relay drive circuit according to the present invention.
In this relay drive circuit, a voltage dividing circuit composed of resistors 35 and 36 is connected between the anode terminal and the cathode terminal of the DC power supply circuit 21a, and this voltage division corresponds to the analog voltage of the microcomputer constituting the control unit 37. Given to read port. The control unit 37 is a control unit of an electric device in which the relay drive circuit is incorporated, is connected to an operation unit 38 and a display unit 47 of the electric device, receives an operation signal from the operation unit 38, and responds to the operation. The displayed information is displayed on the display unit 47.

The control section 37 is connected to the bases of the transistor 27, the transistor 23 and the NPN type transistor 34 through a resistor 39, a resistor 43 and a resistor 45, respectively, and supplies control signals to the transistors 27, 23 and 34, respectively. . The coil RY2 of the relay having the relay contact ry2 is connected between the collector of the transistor 34 and the cathode of the diode 24, the emitter of the transistor 34 is connected to the cathode terminal of the DC power supply circuit 21a, and between the base and the emitter of the transistor 34. The resistor 46 is connected.

The DC power supply circuit 21a has AC 100V, 5
A commercial power supply 30 of 0 Hz or 60 Hz is converted into a low voltage by a transformer 33 and given to a diode bridge 32. The low voltage applied to the diode bridge 32 is
After being rectified, it is smoothed by the smoothing capacitor 29 and output from between the anode terminal and the cathode terminal. Other configurations are
Configuration of the relay drive circuit described in the first embodiment (FIG. 1)
Therefore, the same reference numerals are given to the same portions and the description thereof will be omitted.

The operation of the relay drive circuit will be described below with reference to the flowchart of FIG. 3 showing the operation. The flowchart of FIG. 3 is similar to the operation of the relay drive circuit according to the second embodiment. One DC power supply circuit 2
When driving the coils RY1 and RY2 of a plurality of relays that operate independently by 1a, as shown in the waveform diagram of FIG. 5A, the drive voltage (DC Output voltage of the power supply circuit 21a) decreases,
It may be lower than the relay activation voltage at which the relay can activate.

For example, when the control section 37 operates the operation section 38 to start the display corresponding to the operation on the display section 47 and then activates the relay of one coil RY1 (the same applies to the coil RY2) accordingly. First, the voltage dividing circuit 3
The divided voltages of 5 and 36 are read (S2 in FIG. 3), and it is determined whether the read divided voltage is lower than a predetermined voltage (S4).
The predetermined voltage described here is the same as the predetermined voltage described in the second embodiment.

When the read voltage is not lower than the predetermined voltage (S4), the control section 37 turns on only the transistor 27 (first switching element, hereinafter the same for the transistor 34) (S8) and returns. As a result, when the drive voltage applied to the coil RY1 is not lower than the predetermined voltage, the relay of the coil RY1 can be activated only by the drive voltage.

As shown in FIG. 5B, the control unit 37 controls the read voltage (driving voltage) to be one coil RY1.
When (the same applies to the coil RY2) is being driven and is lower than the predetermined voltage (relay start voltage) (S4), the transistor 34 (the same applies to the first switching element and the transistor 27) and the transistor 22 (the second switching element) are connected. They are simultaneously turned on (S6) and the process returns. As a result, the other coil RY2 (same for the coil RY1)
When the drive voltage applied to the coil is lower than the predetermined voltage, the discharge voltage of the electrolytic capacitor 25 is added to the drive voltage to activate the relay of the other coil RY2, as shown in FIG. 5 (b). Can be done. The holding voltage of the relays of the coils RY1 and RY2 after the relay of the coil RY2 is activated may be considerably lower than the activation voltage.

FIG. 5 (c) is an enlarged waveform diagram showing the waveform obtained by adding the discharge voltage of the electrolytic capacitor 25 to the drive voltage. The discharge voltage of the electrolytic capacitor 25 is set so that the voltage after being added to the drive voltage exceeds the starting voltage for a starting time or more required to start the relays of the coils RY1 and RY2.

Fourth Embodiment FIG. 6 is a flowchart showing the operation of the fourth embodiment of the relay drive circuit according to the present invention. Since the configuration of the fourth embodiment of the relay drive circuit according to the present invention is the same as the configuration of the third embodiment of the relay drive circuit according to the present invention, the description thereof will be omitted. Here, when the coil RY1 (the same applies to the coil RY2) is driven as shown in the timing chart of FIG. 7A, the transistor 22 (first switching element) is changed to the coil RY1.
If it is turned on for a long time in accordance with the above, the resistor 26 becomes a load of the DC power supply circuit 21a and wastes power,
As shown in the timing chart of FIG. 7B, it is better to turn on the transistor 22 only during the activation time of the relay of the coil RY1.

On the contrary, since the power supply load is small and the power supply voltage rises during standby, the charging resistor 26 also serves as a bleeder resistor, and as shown in the timing chart of FIG. Before starting the relay, turn off the transistor 22 and set the electrolytic capacitor 25.
It is good to charge to. Further, since the discharge voltage of the electrolytic capacitor 25 that must be added to the drive voltage differs depending on the level of the drive voltage, the time for charging the electrolytic capacitor 25 is adjusted according to the level of the drive voltage so that the drive voltage after addition is Don't overdo it. As described above, the on / off control of the transistor 22 is performed, for example, as shown in the timing chart of FIG.

The operation of the relay drive circuit will be described below with reference to the flowchart of FIG. Control unit 3
7, for example, after the operation unit 38 is operated and the display corresponding to the operation is started on the display unit 47, the coil RY is correspondingly displayed.
When activating the first relay or the relay of the coil RY2, first, the divided voltage of the voltage dividing circuits 35 and 36 is read (S10 in FIG. 6). Next, the control unit 37 turns off the transistor 23 and turns off the transistor 22 (second switching element) for a time period corresponding to the read voltage (S1).
2) During that time, the electrolytic capacitor 25 is charged.

Next, the control section 37 turns on the transistor 27 or the transistor 34 (first switching element) and the transistor 22 (second switching element) simultaneously (S14), and then the relay activation time elapses. Then (S16), the transistor 23 is turned off and the transistor 22 (second switching element) is turned off (S18).
To return. As a result, as shown in the timing chart of FIG. 7D and the waveform chart of FIG.
When activating the relay of Y1 or the relay of coil RY2, the electrolytic capacitor 25 can be charged for a time corresponding to the level of the detected drive voltage prior to that, and at the time of activation of the relay of coil RY1 or the relay of coil RY2. , The starting voltage required for it can be obtained without making it excessive.

FIG. 8 is a flowchart showing the operation during driving of the relay of this relay drive circuit. The operation will be described below with reference to this flowchart.
The control unit 37 includes a transistor 27 and a transistor 34.
When either or both of the (first switching elements) are on (which does not mean that the relays of the coils RY1 and RY2 are held) (S20), each time a predetermined time elapses (S22), the voltage dividing circuit The voltage for 35 and 36 is read (S24). The control unit 37 then turns off the transistor 23 and turns off the transistor 22 (second switching element) for a time period corresponding to the read voltage (S2).
6) During that time, the electrolytic capacitor 25 is charged.

The control section 37 then turns on the transistor 23 to turn on the transistor 22 (second switching element).
After the relay is turned on (S28) and the relay activation time has elapsed (S30), the transistor 23 is turned off and the transistor 22 (second switching element) is turned off (S3).
2) Return. If neither the transistor 27 nor the transistor 34 (first switching element) is on (S20), the controller 37 returns as it is. As a result, the transistor 23 and the transistor 22 are turned on periodically or at any time. Therefore, after either or both of the relay of the coil RY1 and the relay of the coil RY2 are activated, the driving voltage is lowered and the relay cannot be held. Even in the non-driving state, the driving voltage can be raised to the starting voltage, and the apparatus can be restarted and restored.

[0051]

According to the relay drive circuit of the present invention,
It is possible to apply a starting voltage of a relay with a small-capacity inexpensive power supply circuit and realize a relay drive circuit with a small heat generation loss.

Further, according to the relay drive circuit of the present invention, it is possible to apply the starting voltage of the relay with a small-capacity and inexpensive power supply circuit, and to realize a relay drive circuit with a small heat generation loss.

Further, according to the relay drive circuit of the present invention, when the frequency of the commercial power source is 50 Hz, which is apt to cause a voltage shortage, it is possible to switch the drive voltage of the coil to the discharge voltage of the capacitor. It is possible to apply a starting voltage of a relay with a small-capacity inexpensive power supply circuit and realize a relay drive circuit with a small heat generation loss.

Further, according to the relay drive circuit of the present invention, the starting voltage of the relay can be applied without increasing the discharge voltage of the capacitor more than necessary and with a small-capacity inexpensive power supply circuit. It is possible to realize a relay drive circuit with little heat loss.

Further, according to the relay drive circuit of the present invention, a relay drive circuit can be applied in which a useless current does not flow, and a relay power-up voltage can be applied by a small-capacity and inexpensive power supply circuit, and heat loss is small. A circuit can be realized.

Further, according to the relay drive circuit of the present invention, even if the drive voltage of the relay is reduced after the relay is activated and the relay cannot be held and is in the non-drive state, the relay is activated again. It is possible to recover by using a small-capacity, inexpensive power supply circuit to apply the starting voltage of the relay.
It is possible to realize a relay drive circuit with little heat loss.

Further, according to the relay drive circuit of the present invention, it is possible to suppress the voltage rise when the coil is de-energized, and to apply the starting voltage of the relay with the small capacity and inexpensive power supply circuit. Therefore, it is possible to realize a relay drive circuit with little heat loss.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a configuration of an embodiment of a relay drive circuit according to the present invention.

FIG. 2 is a circuit diagram showing a configuration of an embodiment of a relay drive circuit according to the present invention.

FIG. 3 is a flowchart showing an operation of the embodiment of the relay drive circuit according to the present invention.

FIG. 4 is a circuit diagram showing a configuration of an embodiment of a relay drive circuit according to the present invention.

FIG. 5 is a waveform diagram showing an operation of the embodiment of the relay drive circuit according to the present invention.

FIG. 6 is a flowchart showing an operation of the embodiment of the relay drive circuit according to the present invention.

FIG. 7 is a timing chart and waveform chart showing the operation of the embodiment of the relay drive circuit according to the present invention.

FIG. 8 is a flowchart showing an operation of the embodiment of the relay drive circuit according to the present invention.

FIG. 9 is a circuit diagram showing a configuration example of a conventional relay drive circuit.

FIG. 10 is a circuit diagram showing a configuration example of a conventional relay drive circuit.

[Explanation of symbols]

21, 21a DC power supply circuit 22 PNP type transistor (second switching element) 23 NPN type transistor (third switching element) 24 Diode 25 Electrolytic capacitor (capacitor) 26 Resistor 27, 34 NPN type transistor (first switching element) 28 Switch (Switching circuit) 35, 36 Resistance (detection means) 37 Control section 38 Operation section RY1, RY2 Coil

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 5G057 AA01 KK02 KK12 RR01 RS01                 5J055 AX00 AX08 AX39 AX53 BX16                       CX21 DX04 DX65 EX06 EY01                       EY03 EY10 EY12 EY17 EZ15                       EZ20 EZ42 EZ66 FX18 FX32                       GX01 GX02 GX03 GX04 GX05

Claims (7)

[Claims] 1. A relay drive circuit for energizing / de-energizing the coil by turning on / off a first switching element connected in series to a coil of the relay, wherein a series circuit including the coil and the first switching element is provided. A series circuit with capacitors and resistors connected in parallel,
A diode connected in series to both of the series circuits; and a second switching element that should be turned on / off between the anode of the diode and the cathode of the capacitor.
A relay drive circuit, wherein when the switching element is turned on, the second switching element is simultaneously turned on to add the discharge voltage of the capacitor to the drive voltage of the coil. 2. The relay drive according to claim 1, further comprising a third switching element for turning on / off the second switching element, and connecting respective control terminals of the first switching element and the third switching element to each other. circuit. 3. The relay drive circuit according to claim 1, further comprising switching means for switching whether or not to operate the second switching element. 4. Further comprising: detection means for detecting the drive voltage, and means for increasing or decreasing the time for charging the capacitor by turning off the second switching element according to the drive voltage detected by the detection means. The relay drive circuit according to any one of claims 1 to 3, wherein the means increases or decreases the discharge voltage by increasing or decreasing the time. 5. A relay drive circuit for energizing / de-energizing the coil by turning on / off a first switching element connected in series to a coil of the relay, wherein a series circuit including the coil and the first switching element is provided. A series circuit with capacitors and resistors connected in parallel,
A diode connected in series to both of the series circuits, a second switching element to be turned on / off between an anode of the diode and a cathode of the capacitor, and the first switching element and the second switching element simultaneously. A means for turning on, a detection means for detecting the drive voltage of the coil, and a means for determining the level of the drive voltage detected by the detection means and the predetermined voltage are provided, and the means determines that the drive voltage is lower. In this case, the first switching element and the second
A relay drive circuit, wherein a switching element is simultaneously turned on to add a discharge voltage of the capacitor to a drive voltage of the coil. 6. The relay drive circuit according to claim 1, further comprising means for turning on the second switching element periodically or at any time when the first switching element is turned on. 7. The relay drive circuit according to claim 1, wherein the resistor also serves as a bleeder resistor for suppressing a voltage rise when the coil is not excited.