JPH05206508A - Solid state relay - Google Patents

Abstract

PURPOSE:To provide a solid state relay in which make-before-break contact point functions by an inner circuit. CONSTITUTION:A photovoltaic element 2a, which will be light-coupled to a light-emitting element 1a, is provided. The photovoltaic element 2a is connected between the source and the gate of a switching element consisting of an enhancement type MOSFET. Also, the drain and source of a switching element 5a, consisting of a the gate type MOSFET, are connected between the gate and the source of the switching element. A biasing resistor 6a is connected between the gate and the source of the switching element 5a. An aluminum light-shielding pattern 12 is laminated on the pattern of the biasing resistor 6a, and the light- shielding pattern 12 is electrically connected to the drain of the switching element 5a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention optically couples a light emitting element and a photovoltaic element, and outputs a MOSF by the output of the photovoltaic element.
The present invention relates to a solid-state relay that turns on / off a switching element composed of ET.

[0002]

2. Description of the Related Art Conventionally, as a solid-state relay of this type, as shown in FIG. 5, light-emitting elements 1a and 1b formed of light-emitting diodes which blink by a control input and each light-emitting element 1 are provided.
Photovoltaic elements 2a and 2b such as solar cells optically coupled to a and 1b, and switching elements 3a and 3b formed of MOSFETs that are turned on and off by the output of each photovoltaic element 2a and 2b, respectively. Things are offered. One of the switching elements 3a is an enhancement type and is turned off when the light emitting element 1a is turned off, and is generated when the light emitting element 1a is turned on.
Inverted by the output of. That is, the switching element 3a functions as a normally open contact. The other switching element 3b is a depletion type, and the light emitting element 1
When the light emitting element 1b is turned off, it is turned on, and is turned off by the output of the photovoltaic element 2b generated when the light emitting element 1b is turned on. That is, the switching element 3b functions as a normally closed contact.

By the way, when the light emitting elements 1a and 1b are turned off from the lit state, the switching element 3a is turned off and the switching element 3b is turned on.
Since there is residual charge due to the capacitive component inside the switching elements 3a and 3b, which is ET, it cannot be instantaneously inverted. That is, the switching elements 3a and 3b
The residual charges of the photovoltaic elements 2a and 2b try to discharge through the photovoltaic elements 2a and 2b, but due to the non-linearity,
Since b has a relatively high resistance, it takes a long time to discharge the residual charges. After all, the switching element 3a,
3b immediately responds to the lighting of the light emitting elements 1a and 1b, but has a problem that the response is delayed when the light emitting elements 1a and 1b are turned off.

Therefore, driving circuits 4a and 4b are provided between the gates and the sources of the switching elements 3a and 3b so that the residual charges can be instantaneously discharged. Drive circuits 4a, 4
b is a switching element 5a, 5b formed of a depletion type MOSFET in which a drain and a source are respectively connected between the gate and the source of the respective switching elements 3a and 3b.
And bias resistors 6a and 6b connected between the gate and source of the switch elements 5a and 5b. If such drive circuits 4a and 4b are provided, the switch elements 5a and 5b are provided when the light emitting elements 1a and 1b are extinguished from the lit state.
Is discharged through the bias resistors 6a and 6b, the switch elements 5a and 5b are turned on, and the residual charges of the switching elements 3 and 3b are changed to the switch elements 5a and 5b.
It will be discharged through b. Thus, by providing the drive circuits 4a and 4b, the off time can be shortened.

As shown in FIG. 6, the solid-state relay having such a structure includes photovoltaic elements 2a and 2b, switching elements 3a and 3b, drive circuits 4a and 4b, and circuits corresponding to the respective switching elements 3a and 3b. Each chip is usually integrated into one chip 10. Also, the chip 10
The light emitting element 1 is attached to the bias resistors 6a and 6b formed above.
Since a leak current is generated when the light from a and 1b is incident, the light shielding pattern 12 is formed facing the bias resistors 6a and 6b. The light-shielding pattern 12 is usually formed of aluminum similarly to the electrode pad 11.

By the way, since the circuit shown in FIG. 5 has a normally open contact and a normally closed contact, both contacts are used to form a make-before-break contact (MBB contact). You may want to. In order to meet such a requirement, a configuration as shown in FIG. 7 can be considered. In FIG. 7, FIG.
The solid state relay A having the above structure is symbolically described as a combination of the light emitting elements 1a and 1b and the contacts 7a and 7b. That is, this circuit is a make-before-
In order to operate as a break contact, a control circuit is provided outside the solid state relay A, and the control circuit is a resistor R for current limiting connected in series to each light emitting element 1a, 1b.
a and Rb, a capacitor C connected in parallel to the series circuit of the light emitting element 1a corresponding to the normally open contact 7a and the resistor Ra, and a backflow blocking resistor inserted between the resistor Rb and the capacitor C. And a diode D.

Therefore, at time t ₁ as shown in FIG.
When the control signal becomes H level and the transistor Q is turned on, the both light emitting elements 1a and 1b are energized, as shown in FIG.
As shown in Fig. 8 (b), the contact 7a is turned on.
Flips off almost simultaneously. On the other hand, if the control signal becomes L level and the transistor Q is turned off at time t ₂ ,
Since the light emitting element 1b is immediately turned off, the contact 7b is returned to the on state in a short time, but since the current due to the charge charged in the capacitor C flows through the light emitting element 1a, the light emitting element 1b is turned off with a delay. That is, as shown in FIG. 8 (c), the contact point 7b is restored later than the contact point 7b. in short,
By turning off the light emitting element 1a later than the light emitting element 1b, the normally open contact is restored and turned on, and then the normally open contact is restored and turned off.
It can operate as a make-before-break contact.

[0008]

According to the above structure, a control circuit having a capacitor C and a diode D is added as an external circuit to the outside of the solid state relay A in order to operate as a make-before-break contact. However, there is a problem in that the number of parts during mounting increases and the mounting area increases.

The present invention is intended to solve the above-mentioned problems, and enables a make-before-break contact to be formed without using an external circuit, whereby the number of external parts is increased. The present invention aims to provide a solid state relay having a smaller mounting area by reducing the number of elements than the conventional configuration.

[0010]

The present invention provides a light emitting element which is turned on and off by a control input, a first photovoltaic element and a second photovoltaic element which are arranged so as to be optically coupled to the light emitting element. , An enhancement type MOSF which is turned on by the output of the first photovoltaic element when the light emitting element is turned on
A first switching element composed of ET, a second switching element composed of a depletion type MOSFET which is turned off by the output of the second photovoltaic element when the light emitting element is turned on, and a gate-source of each switching element A solid-state relay having a switch element composed of a depletion type MOSFET having a drain-source connected between them and a drive circuit composed of a bias resistor connected between the gate and source of the switch element as a common configuration There is.

In order to achieve the above object, at least a photovoltaic element and a driving circuit are integrated on one chip, and light is emitted in a form facing a bias resistor pattern of the driving circuit. A light shielding pattern for shielding light from the element is laminated, a light shielding pattern provided on a bias resistor corresponding to the first switching element is formed of a conductive material, and is electrically connected to the drain of the switch element.

According to the second aspect of the invention, the area of the drain electrode pattern in the switch element corresponding to the first switching element is made larger than the area of the source electrode pattern.

[0013]

According to the structure of the present invention, the light-shielding pattern provided for shielding the bias resistor pattern used in the drive circuit is formed of a conductive material, and the light-shielding pattern is the drain of the switch element constituting the drive circuit. The presence of the light-shielding pattern increases the capacitance between the gate and the drain of the switch element, since it is electrically connected to the switch element. In other words, it is equivalent to connecting a capacitor between both ends of the photovoltaic element, and when the light emitting element is turned off, the electric charge stored in this capacitor is discharged through the bias resistor to bias the switch element. As a result, the switch element continues to be in the off state, and as a result, the discharge time of the residual charge of the first switching element becomes long, and as a result, the first switching element is turned off after the second switching element is turned on. Will behave. In short, the second
After the switching element of (1) is turned on (make), the first switching element is turned off (break), and the first switching element operates as a make-before-break contact. In this way, the internal configuration of the solid-state relay enables operation as a make-before-break contact, so there is no need to add components outside the solid-state relay, reducing the number of mounted components and the mounting area. It leads to.

According to the second aspect of the invention, the area of the drain electrode pattern in the switch element of the drive circuit is made larger than the area of the source electrode pattern. The capacitance between the gate and drain in the element will increase.
Therefore, similar to the structure of claim 1, it is equivalent to connecting a capacitor between both ends of the photovoltaic element, and the presence of this capacitor causes the make-before-
It can operate as a break contact.

[0015]

(Embodiment 1) Since the basic structure of the present invention is the same as the conventional structure shown in FIGS. 5 and 6, only the differences will be described. That is, the light shielding pattern 12 is laminated on the pattern of the bias resistors 6a and 6b formed on the chip 10 as described above.
Since the light shielding pattern 12 is made of aluminum, in this embodiment, as shown in FIG. 1B, it is connected to the drain of the switch element 5a corresponding to the switching element 3a which is an enhancement type MOSFET. The light shielding pattern 12 is extended so that the light shielding pattern 12 is electrically connected to the electrode pad 11.

According to this structure, as shown in FIG. 1A, the light shielding pattern 12 facing the bias resistor 6a corresponding to the enhancement type switching element 3a.
Is electrically connected to the drain of the switch element 5a, and the bias resistor 6a and the light shielding pattern 12 are electrically insulated from each other. Therefore, as shown in FIG. This is equivalent to connecting the capacitor 9 between the source and drain of the switch element 5a.

When such a capacitor 9 is connected, the electric charge charged in the capacitor 9 when the light emitting element 1a is turned on is discharged from the capacitor 9 through the bias resistor 6a when the light emitting element 1a is turned off, and the capacitor 9 is discharged. During the discharge of the electric charge of 9, the switch element 5a is biased and the switch element 5a remains off. Therefore, the discharge time of the residual charge of the enhancement type switching element 3a becomes long, and as a result, the switching element 3a is turned off after the switching element 3b is turned on. That is, FIG.
Similarly to the operation of, the switching element 3a that functions as a normally-closed contact is turned on before the switching element 3a that functions as a normally-open contact is turned off. Therefore, it is necessary to operate as a make-before-break contact. Become.

According to the above structure, since the internal circuit of the solid state relay can operate as a make-before-break contact, it is not necessary to add an external circuit to the solid state relay as in the conventional configuration, and the solid state relay does not need to be added. The relay itself can operate as a make-before-break contact, reducing the number of components during mounting and reducing the mounting area. Although two light emitting elements 1a and 1b are provided here, one photovoltaic element may be shared by both photovoltaic elements 2a and 2b.

(Embodiment 2) In this embodiment, as shown in FIG. 3A, the drain electrode pattern 13 of the switch element 5a of the drive circuit 4a corresponding to the switching element 3a which is an enhancement type MOSFET is formed. The area is set larger than the area of the source electrode pattern 14. That is, the switch element 5a is a MOS
It is a FET and the electrode pattern 1 of the drain and the source
Each of the electrodes 3 and 14 is usually formed in a comb shape, and has a shape in which the comb teeth of the electrode patterns 13 and 14 are inserted into each other. The gate electrode pattern 15 is the drain and source electrode pattern 1.
Formed around 3,14. Here, in the conventional configuration,
The electrode patterns 13 and 14 of the drain and the source are shown in FIG.
As shown in FIG. 3, although they are formed to have substantially the same area, in this embodiment, the drain electrode pattern 13 is set to be larger than the source electrode pattern 14 as shown in FIG.

According to the above structure, a large capacitance can be secured between the drain electrode pattern 13 and the gate electrode pattern 15, and as a result, FIG.
As shown in (b), it is equivalent to connecting a capacitor 9 between the drain and source of the switch element 5a. As a result, similarly to the first embodiment, it is possible to lengthen the time until the switch element 5a is turned on after the light emitting element 1a is turned off, and delay the time until the switching element 3a is turned off. Can be done. That is, when used in combination with the switching element 3b, the solid state relay alone can operate as a make-before-break contact. Other configurations and operations are similar to those of the first embodiment.

[0021]

According to the present invention, the light-shielding pattern provided for shielding the bias resistance pattern used in the drive circuit is formed of a conductive material, and the light-shielding pattern is the drain of the switch element constituting the drive circuit. , It is equivalent to connecting a capacitor between both ends of the photovoltaic element, and delays the time until the first switching element is turned off after the light emitting element is turned off. It can be done. That is, since the first switching element is turned off after the second switching element is turned on, the first switching element operates as a make-before-break contact. In this way, the internal circuit of the solid-state relay enables operation as a make-before-break contact, so there is no need to add an external circuit to the solid-state relay, leading to a reduction in the number of mounting parts and a mounting area. Has the advantage.

According to the second aspect of the present invention, the area of the drain electrode pattern in the switch element of the drive circuit is made larger than the area of the source electrode pattern. The capacitance between the gate and the drain increases, which is equivalent to connecting a capacitor between both ends of the photovoltaic element. As a result, the solid-state relay alone can operate as a make-before-break contact.

[Brief description of drawings]

FIG. 1 shows the first embodiment, (a) is a circuit diagram of a main part,
(B) is a plan view of a main part.

FIG. 2 is an equivalent circuit diagram of the first embodiment.

FIG. 3 shows the second embodiment, (a) is a plan view of the main part,
(B) is a circuit diagram of a main part.

FIG. 4 is a plan view of a comparative example with respect to Example 2.

FIG. 5 is a basic circuit diagram of a solid state relay according to the present invention.

FIG. 6 is a plan view of a solid state relay according to the present invention.

FIG. 7 is a circuit diagram showing a conventional example.

FIG. 8 is an operation explanatory diagram of a conventional example.

[Explanation of symbols]

 1a Light emitting element 1b Light emitting element 2a Photovoltaic element 2b Photovoltaic element 3a Switching element 3b Switching element 4a Driving circuit 4b Driving circuit 5a Switching element 5b Switching element 6a Bias resistance 6b Bias resistance 12 Light-shielding pattern 13 Drain electrode pattern 14 Source electrode pattern

Claims (2)

[Claims] 1. A light emitting element which is turned on / off by a control input, a first photovoltaic element and a second photovoltaic element which are arranged to be optically coupled to the light emitting element, and a first photovoltaic element when the light emitting element is turned on. A first switching element composed of an enhancement type MOSFET which is turned on by the output of the first photovoltaic element, and a depletion type MO which is turned off by the output of the second photovoltaic element when the light emitting element is turned on.
A second switching element composed of an SFET, a switch element composed of a depletion type MOSFET in which a drain and a source are respectively connected between the gate and the source of each switching element, and a bias connected between the gate and the source of the switch element. In a solid-state relay having a drive circuit composed of a resistor for driving, at least the photovoltaic element and the drive circuit are integrated on one chip, and the light from the light emitting element is opposed to the pattern of the bias resistor of the drive circuit. A solid-state relay in which a light-shielding pattern for shielding light is laminated, a light-shielding pattern provided on a bias resistor corresponding to the first switching element is formed of a conductive material, and is electrically connected to a drain of a switch element. 2. A light emitting element which is turned on and off by a control input, a first photovoltaic element and a second photovoltaic element which are arranged so as to be optically coupled to the light emitting element, and a first photovoltaic element when the light emitting element is turned on. A first switching element composed of an enhancement type MOSFET which is turned on by the output of the first photovoltaic element, and a depletion type MO which is turned off by the output of the second photovoltaic element when the light emitting element is turned on.
A second switching element composed of an SFET, a switch element composed of a depletion type MOSFET in which a drain and a source are respectively connected between the gate and the source of each switching element, and a bias connected between the gate and the source of the switch element. A solid-state relay including a drive circuit including a resistance for use, wherein the area of the drain electrode pattern in the switch element corresponding to the first switching element is larger than the area of the source electrode pattern.