JP2743874B2 - Solid state relay - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid state relay, and more particularly to a field effect transistor (MOSFET).
The present invention relates to operation control of a solid state relay having a terminal as an output terminal.

[0002]

2. Description of the Related Art Conventionally, in a solid state relay of this type, various circuits for the purpose of operating stability and controlling a response waveform have been used.

FIG. 8 is a circuit diagram of a solid state relay showing an example of the prior art (for example, see Japanese Patent Application Laid-Open No. 63-242).

As shown in FIG. 8, such a solid state relay comprises a light emitting diode (hereinafter referred to as an LED) 3 connected between input terminals 1 and 2 and a photovoltaic diode array optically coupled to the LED 3. 4 and a field effect transistor (hereinafter referred to as MOS) as a switching element for opening and closing between output terminals 9 and 10 of the solid state relay.
FET 8), thyristor 7 for controlling the on / off operation of MOSFET 8, and diodes 5 and 6.

The operation of this solid state relay is such that the LED 3 emits light in response to an input signal supplied between the input terminals 1 and 2, and the photovoltaic diode array 4 receiving this light.
Generates photovoltaic power. This photovoltaic voltage is applied between the gate and the source of the MOSFET 8 via the diodes 5 and 6, and charges the gate parasitic capacitance of the MOSFET 8. Here, when the potential of the gate of MOSFET 8 exceeds a threshold voltage (hereinafter abbreviated as Vth),
The transition between the drain and the source of the FET 8 changes to a conductive state,
Finally, the solid state relay is turned on. At this time, since a forward voltage drop occurs in the diodes 5 and 6, the respective gates of the thyristor 7, that is, the N-pole gate 7b and the P-pole gate 7c are in a reverse bias state, and the thyristor 7 is forcibly turned off. That is, the conduction between the anode 7a and the cathode 7d becomes non-conductive, so that the solid state relay maintains a stable ON state.

On the other hand, when the input current disappears, the LED 3 is turned off, and the self-discharge in the photovoltaic diode array 4 causes the photovoltage (hereinafter referred to as V0) between the anode and the cathode of the photovoltaic diode array 4 to gradually decrease. To decline. In this state, when the potential difference between V0 and the gate of the MOSFET 8 becomes about 0.6 V, the forward bias is applied between the anode 7a of the thyristor 7 and the N-pole gate 7b, and the thyristor 7 is turned on. Thereafter, the charge stored in the gate parasitic capacitance of the MOSFET 8 is rapidly discharged by the self-amplifying action of the thyristor 7, and the solid state relay is quickly turned off.

Here, in the operation of the solid state relay, the operation time of the ON operation is determined substantially in proportion to the photovoltaic power (photocurrent) generated in the photovoltaic diode array 4, and the OFF operation is performed. , The unique recovery time is determined by the efficiency of the thyristor 7.

FIG. 9 is a circuit diagram of a solid state relay showing another example of the prior art (for example, Japanese Patent Laid-Open No. 4-4001).
No. 3).

As shown in FIG. 9, this solid-state relay controls the slope of a response waveform appearing between output terminals when the relay is turned off in the conventional example of FIG. In short, in the conventional example of FIG. 8, when the solid state relay is turned off, the discharge current discharged from the gate parasitic capacitance of the MOSFET 8 flows on the path, that is, the cathode 7d electrode of the thyristor 7 and the MOSFE
A control resistor 29 for controlling a discharge current is connected between the source electrodes of T8.

When the solid state relay is turned on, the LED 3 emits light when an input signal is inputted, and the photovoltaic diode array 4 receiving the light, similarly to the ON operation of the conventional example shown in FIG. The MOSFET 8 is turned on by the photovoltaic power generated in step (1).

On the other hand, when there is no input signal, the voltage between the anode and the cathode of the photovoltaic diode array 4 decreases due to self-discharge of the photovoltaic diode array 4, and the voltage between the anode 7a of the thyristor 7 and the N-pole gate 7b is reduced. Becomes a forward bias, and the thyristor 7 is turned on. Therefore, the charge stored in the gate parasitic capacitance of the MOSFET 8 is discharged. At this time, the discharge current is controlled by the control resistor 29.
, The current flowing therethrough is limited, and as a result, the OFF operation of the relay is delayed. That is, the output terminal 9,
The slope of the response waveform obtained between 10 becomes gentle.

As described above, the control resistor 29 is added to the solid state relay, and an arbitrary response waveform can be obtained by the resistance value.

FIG. 10 is a circuit diagram of another conventional solid-state relay. This solid state relay has a function of controlling the slope of a response waveform appearing between output terminals during the ON operation in the conventional example of FIG. 9 described above.

As shown in FIG. 10, such a solid-state relay has the circuit configuration of FIG. 9 on a path to which photovoltaic power is supplied when the relay is turned on, that is, the anode of the photovoltaic diode array 4 and the diode 5 And a control resistor 30 for controlling a photocurrent is connected between the anodes of the two.

When the solid state relay is turned off, the discharge current is controlled by the control resistor 29 as in the conventional example shown in FIG.

On the other hand, in the ON operation, when an input signal is supplied, the LED 3 emits light and the photovoltaic diode array 4 generates photovoltaic power. This photovoltaic (photocurrent)
MOSFET through control resistor 30 and diode 5
8 to charge the gate parasitic capacitance. At this time, the control resistor 30
Limits the photocurrent, so that the ON operation of the relay is delayed. That is, even during the ON operation, the output terminals 9 and
The slope of the response waveform between 10 is made gentle.

As described above, an arbitrary response waveform can be obtained by the resistance values of the control resistors 29 and 30.

FIG. 11 is a timing chart showing input signals and response waveforms of the relay circuit shown in FIGS. FIG.
As shown in FIG. 8, when the input signal 15 is supplied between the input terminals 1 and 2, the response waveform 31 obtained between the output terminals 9 and 10 in the circuit of FIG. The slope is steep. On the other hand, the response waveform 32 obtained between the output terminals 9 and 10 in the circuit of FIG.
9, the inclination at the time of off can be changed gently.

[0019]

However, the above-mentioned conventional solid-state relay has the following disadvantages.

First, in the solid state relay of FIG. 8, the response waveform at the time of the OFF operation is uniquely determined by the efficiency of the discharge circuit (thyristor), so that a sudden fluctuation is given to the connected circuit to generate noise. There is a disadvantage that it is easy.

Next, in the solid state relays shown in FIGS. 9 and 10, in order to solve such a noise problem, a control resistor is connected on a path through which a discharge current and a photocurrent flow to delay a response waveform. I'm trying. However, since the resistance value of the control resistor is determined at the manufacturing stage, there is a drawback that it is difficult to use each solid state relay with an arbitrary response waveform (particularly at the time of off operation).

Further, in the conventional examples shown in FIGS. 8 to 10, when a photovoltage of 0.6 V or more is generated in the photovoltaic diode array even if the input signal is very small, the solid state relay is turned on. I will. For this reason, there is also a problem that the solid state relay malfunctions when noise occurs in the input signal.

A first object of the present invention is to provide a solid state relay whose operation characteristics (response waveform) can be arbitrarily controlled from the outside.

It is a second object of the present invention to provide a solid-state relay whose operation sensitivity can be arbitrarily controlled from the outside.

[0025]

According to the present invention, there is provided a solid state relay connected between signal input terminals and emitting light according to an input signal, and a photovoltaic element receiving light from the light emitting element and generating photovoltaic power. A power diode array, a source and a drain connected between output terminals, and a gate, wherein the photovoltaic power generated by the photovoltaic diode array is provided.
As a switching element driven by being supplied
And an anode and an anode for forming a discharge circuit for turning off the field-effect transistors.
And the cathode, respectively, of the field effect transistor.
And a control N-pole gate,
P-pole gates are respectively connected to the photovoltaic diode array.
Anode, a thyristor connected to the cathode, the photoelectromotive
The output of the power diode array is connected to the field effect transistor.
A diode means for supplying the thyristor with an anode and a thyristor.
And between the gate of the field effect transistor
Both are equipped with a control signal input terminal, allowing external control signals
An operation control circuit that controls a charge / discharge current to a gate parasitic capacitance of the field effect transistor by changing a resistance value of the field effect transistor, wherein the operation control circuit is connected between the control signal input terminals.
And another light-emitting element different from the light-emitting element
The thyristor anode and the field effect transistor
Connected between the gates of the transistors and said another light emitting element
Light receiving element that receives the light from the
And a control resistance element to be connected .

[0026]

The solid state relay according to the present invention is provided with an operation control circuit which can be adjusted by an external control signal, and the ON / OFF operation or ON / OFF operation of the relay is individually controlled by the control signal. And realize any operation waveform. Further, by using a bidirectional thyristor or a triac for the operation control circuit, the operation sensitivity of the solid state relay can be arbitrarily adjusted.

[0027]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a circuit diagram of a solid state relay showing a basic configuration of the present invention. As shown in FIG. 1, this solid state relay has an L terminal connected between input terminals 1 and 2.
ED3, a photovoltaic diode array 4 driven by receiving light of the LED 3, a thyristor 7 for forming diodes 5, 6 and a discharge circuit, and an output terminal 9,
MOSF as a switching element connected between 10
In addition to the ET 8, an operation control circuit 11 for controlling a charge / discharge current to the gate parasitic capacitance of the MOSFET 8 is provided. The operation control circuit 11 includes control signal input terminals 11a and 11b for supplying an external control signal,
A control terminal 11 for supplying a control output based on the control signal
c and 11d, and these control terminals 11c and 11d are connected to the anode of the thyristor 7 and the MOSFET 8 respectively.
Connected to the gate electrode.

FIG. 2 is an operation control circuit diagram used for a solid-state relay for explaining a first embodiment of the present invention. As shown in FIG. 2, the operation control circuit 11 according to the present embodiment is connected between control signal input terminals 11a and 11b and emits light by a control signal supplied thereto in order to control the gate charge / discharge current of the MOSFET 8. And a phototransistor 13 connected between the control terminals 11c and 11d and optically coupled to the LED 12, and a control resistor 14 connected in parallel to the phototransistor 13.

The operation of the solid state relay using the operation control circuit 11 will be described with reference to FIG.

FIG. 3 is a timing chart showing input signals, control signals, and response waveforms in FIG. As shown in FIG. 3, when the input signal 15 is input at the time t0, the LED 3 emits light and the photovoltaic diode array 4 generates photovoltaic power. This photoelectromotive force (photocurrent) is supplied to the diode 5 and the control terminals 11 c and 11 d of the operation control circuit 11.
, And charges the gate parasitic capacitance of the MOSFET 8.
At this time, when the control signal 16 is not input to the operation control circuit 11, the phototransistor 13 is turned off, so that the photocurrent from the photovoltaic diode array 4 flows through the control resistor 14. For this reason, the photocurrent is limited by the control resistor 14, and the solid state relay smoothly transitions to the ON state.

Next, when the control signal 16 is inputted from the terminals 11a and 11b at time t1, the phototransistor 13 is turned on, and the emitter and the collector thereof are electrically connected. At this time, the control terminals 11c, 11
Since the photocurrent flowing between d flows between the emitter and the collector of the phototransistor 13, the limitation by the resistor 14 is eliminated, and the ON state of the solid state relay is speeded up.

Subsequently, when the control signal 16 disappears at time t2, the phototransistor 13 is turned off, and the photocurrent flows again through the resistor 14, so that the on-operation of the solid state relay is delayed.

On the other hand, when the input signal 15 disappears at time t3, the photovoltaic power in the photovoltaic diode array 4 gradually decreases, and the potential difference between the anode of the photovoltaic diode array 4 and the gate of the MOSFET 8 becomes zero. When the voltage exceeds 0.6 V, the thyristor 7 is turned on. Therefore, the charge stored in the gate parasitic capacitance of the MOSFET 8 is discharged through the control resistor 14 of the operation control circuit 11 and the thyristor 7. At this time, since the discharge current is limited by the resistor 14, the OFF operation waveform of the solid state relay is gentle.

Next, at time t4, the control signal 16
Is input, the phototransistor 13 is turned on again, and the discharge current flows between the collector and the emitter of the phototransistor 13, so that the discharge current is not limited by the resistor 14. Therefore, MOSFET
The charge stored in the gate parasitic capacitance of No. 8 is rapidly discharged, and the solid state relay is immediately turned off.

FIG. 4 is an operation control circuit diagram used for a solid state relay for explaining a second embodiment of the present invention. As shown in FIG. 4, the operation control circuit 11 of the present embodiment includes an LED 12 that emits light by input of an input signal and a photoconductive cell including a CdS or the like optically coupled to the LED 12 in order to control a charging / discharging current. 18. Other configurations are the same as those in FIG. 1 described above.

The operation of the relay is such that charge and discharge of the charge to the gate parasitic capacitance of the MOSFET 8 are performed via the photoconductive cell 18 during the ON / OFF operation. Here, since the resistance value of the photoconductive cell 18 decreases in inverse proportion to the light amount from the LED 12, the waveform control during the on / off operation of the solid state relay can be arbitrarily adjusted from the outside by the control signal 16 supplied to the LED 12. it can.

FIG. 5 is an operation control circuit diagram used for a solid state relay for explaining a third embodiment of the present invention. As shown in FIG. 5, the operation control circuit 11 of this embodiment includes an LED 12 and a photovoltaic diode array 19 that receives light from the LED 12 and generates photovoltaic power.
, Depletion type MOSFETs 23 and 24, thyristor 22 for controlling the operation of these MOSFETs 23 and 24, diodes 20 and 21, and control resistor 14. That is, in the present embodiment, the phototransistor 13 of FIG. 2 is replaced by a circuit including the LED 12, the photovoltaic diode array 19, the thyristor 22, and the depletion-mode MOSFETs 23 and 24.

Here, in the solid state relay of the first embodiment described above, the control resistor 14 is bypassed by the phototransistor 13 by the input of the control signal 16, whereas in the present embodiment, the control signal is When the input is not input, the control resistor 14 is bypassed because the drains of the depletion-type MOSFETs 23 and 24 to which the sources are connected are in a conductive state. Conversely, when a control signal is input, the depletion type MOSFETs 23 and 24 are turned off, and the drain-drain of the depletion type MOSFETs 25 and 26 are turned off.
The charge / discharge current for the gate 8 flows through the control resistor 14.

FIG. 6 is an operation control circuit diagram used for a solid state relay for explaining a fourth embodiment of the present invention. As shown in FIG. 6, the operation control circuit 11 of the present embodiment includes a bidirectional thyristor 25 instead of the control resistor 14 of FIG. 2 described above, and is connected in parallel to the bidirectional thyristor 25 to bypass the discharge current. It is connected to a diode 26 to be used. Hereinafter, the operation of the solid state relay using the operation control circuit 11 will be described.

First, when a small signal (about 0.5 mA or less) such as noise is input when the solid state relay is off, a photovoltaic voltage is applied to the photovoltaic diode array 4 with the emission of the LED 3 in FIG. Occurs. At this time, if the bidirectional thyristor 25 in FIG. 6 has a withstand voltage between the first anode and the second anode of about 5 to 7 V, a light voltage (2. (About 5 to 4 V), the photovoltaic voltage cannot flow between the first anode and the second anode of the bidirectional thyristor 25, so that the solid state relay maintains the off state. This prevents a malfunction caused by noise or the like when the solid state relay is turned off.

Next, when a sufficient input signal is input between the input terminals 1 and 2, a higher optical voltage (about 8 V or more in 16 stages) is generated in the photovoltaic diode array 4. When this light voltage exceeds the withstand voltage between the first anode and the second anode of the bidirectional thyristor 25, the bidirectional thyristor 25 is turned on, photovoltaic voltage is applied to the gate of the MOSFET 8, and the solid state relay is turned on. . At this time, since the voltage drop in the on state of the bidirectional thyristor 25 is as low as about 1 V, a voltage sufficient to turn on the MOSFET 8 is applied.

Subsequently, when there is no input signal, the optical voltage decreases as the photovoltaic diode array 4 decreases, and the MO voltage decreases.
The charge stored in the gate parasitic capacitance of the SFET 8 starts to be discharged. This discharge current flows between the control terminals 11c and 11d via the diode 26 provided for bypass, and when the potential difference between the gate of the MOSFET 8 and the anode of the photovoltaic diode array 4 becomes about 1.2 V or more,
The thyristor 7 is turned on, and the solid state relay is immediately turned off.

Here, while the relay in the present embodiment is in the off state to the on state, the control signal is applied to the control inputs 11a and 1a.
When the voltage is input between 1b, the phototransistor 13 is turned on, so that the bidirectional thyristor 25 is bypassed, and the off-state operation characteristics are almost the same as those of the solid state relay of FIG. That is, when the solid state relay is used with a small input signal, by supplying a control signal from the outside, it is possible to use the solid state relay under almost the same conditions as the conventional solid state relay.

FIG. 7 is an operation control circuit diagram used for a solid-state relay for explaining a fifth embodiment of the present invention. As shown in FIG. 7, the operation control circuit 11 of the present embodiment includes an LED 12, a photovoltaic diode 27 optically coupled to the LED 12, a triac 28, and a bypass diode 26 during a relay-off operation. You. In this case, when a photovoltage is generated by the LED 12 according to the control signal supplied between the control input terminals 11a and 11b, the photovoltaic power generated by the photovoltaic diode 27 is supplied to the gate of the triac 28.

The basic operation of the solid state relay using the operation control circuit 11 is almost the same as that of the fourth embodiment. The difference is that the first anode and the second anode of the bidirectional thyristor 25 in the fourth embodiment are different.
While the operating sensitivity of the relay was univocal due to the withstand voltage between the anodes, in the present embodiment, the triac 2
In other words, the gate voltage of the triac 28, that is, the photocurrent of the photovoltaic diode 27, is reduced in proportion to the anode breakdown voltage of the triac. For this reason, in this embodiment, any operational sensitivity of the solid state relay can be obtained.

In short, since the photocurrent of the photovoltaic diode 27 increases and decreases in direct proportion to the amount of light emitted from the LED 12, the operating sensitivity of the solid state relay becomes more sensitive as the control signal (control input current) increases. Become something.

[0047]

As described above, in the solid state relay of the present invention, the operation control circuit for controlling the charging / discharging current by an external control signal includes the gate of the MOSFET as a switching element and the thyristor as a discharging circuit. There is an effect that an arbitrary ON operation and OFF operation can be realized by connecting between the anode and the anode.

The solid state relay of the present invention also has the effect that the operation sensitivity can be arbitrarily controlled externally by using a bidirectional thyristor, a triac, or the like for the operation control circuit.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a solid state relay showing a basic configuration of the present invention.

FIG. 2 is an operation control circuit diagram for explaining a first embodiment of the present invention.

FIG. 3 is a timing chart showing an input signal, a control signal, and a response waveform in FIG. 1;

FIG. 4 is an operation control circuit diagram for explaining a second embodiment of the present invention.

FIG. 5 is an operation control circuit diagram for explaining a third embodiment of the present invention.

FIG. 6 is an operation control circuit diagram for explaining a fourth embodiment of the present invention.

FIG. 7 is an operation control circuit diagram for explaining a fifth embodiment of the present invention.

FIG. 8 is a circuit diagram of a solid-state relay showing an example of the related art.

FIG. 9 is a circuit diagram of another conventional solid state relay.

FIG. 10 is a circuit diagram of a solid state relay showing another example of the related art.

FIG. 11 is a timing chart showing input signals and response waveforms of the relay circuit shown in FIGS. 8 and 9;

[Description of Signs] 1, 2 input terminal 3, 12 light emitting diode 4, 19 photovoltaic diode array 5, 6, 20, 21, 26 diode 7, 22 thyristor 7a anode 7b N pole gate 7c P pole gate 7d cathode 8 MOSFET 9,10 Output terminal 11 Operation control circuit 11a, 11b Control signal input terminal 11c, 11d Control terminal 13 Phototransistor 14 Resistor 18 Photoconductive cell 23,24 Depletion type MOSFET 25 Bidirectional thyristor 27 Photovoltaic diode 28 Triac

Continuation of the front page (56) References JP-A-6-77798 (JP, A) JP-A-3-116452 (JP, A) JP-A-4-40013 (JP, A) JP-A-61-245617 (JP) JP-A-58-501395 (JP, A) JP-A-6-29815 (JP, A) JP-A-61-251227 (JP, A) JP-A-5-227000 (JP, A) 1-63229 (JP, U)

Claims (5)

(57) [Claims] 1. A light emitting element connected between signal input terminals for emitting light according to an input signal, a photovoltaic diode array for receiving light from the light emitting element and generating photovoltaic power, and a source and a drain between output terminals. The photovoltaic power generated by the photovoltaic diode array at the gate
And a switching element driven by being supplied with
A field-effect transistor, and an anode for forming a discharge circuit for turning off the field-effect transistor.
And the cathode of the field-effect transistor, respectively.
Port and source, and control N-pole gate
And P-pole gates are connected to the photovoltaic diode arrays, respectively.
A thyristor connected anode of Lee, a cathode, the
The output of the photovoltaic diode array is
A solid state relay comprising: a diode means for supplying a thyristor;
And the gate of the field effect transistor.
A control signal input terminal, and an operation control circuit for controlling a charge / discharge current to a gate parasitic capacitance of the field effect transistor by changing a resistance value by an external control signal, and the operation control circuit , The control signal input terminal
Another light emitting device connected between the light emitting devices and different from the light emitting device
Device, anode of the thyristor and the field effect
Another light emitting element connected between the gates of the transistors and
Light receiving element for receiving light from
And a control resistor element connected to the solid state relay. 2. The light-receiving element of the operation control circuit ,
2. The solid state relay according to claim 1 , wherein a phototransistor is used . 3. The light receiving element of the operation control circuit ,
The control resistance element uses an integrated photoconductive cell,
Light from another light-emitting element is received, and the light intensity
2. The solid state relay according to claim 1, wherein the value is changed . 4. The operation control circuit according to claim 1, wherein the control resistance element is
Instead of a two-terminal bidirectional thyristor and a diode element
The solid state relay according to claim 1, wherein a child is used . 5. An operation control circuit, comprising:
An electromotive force diode, and the control resistance element
Using triacs and diode elements instead of
Controlling the triac with the output of a photovoltaic diode
The solid state relay according to claim 1, wherein: