JPH0634435A - Pyroelectric infrared detector - Google Patents

Abstract

PURPOSE:To enable an infrared detector to make self-judgment by providing a pyroelectric photoreceptor element which is positioned on the substrate of a molded interconnected device (MID) so that the central part of the element can float from the substrate and connected to an electrode for connecting earth and making the element to generate heat by conducting the electrode. CONSTITUTION:A recessed section 3a is formed at the center on the upper surface of an MID substrate 3 and element supporting sections 3b and 3c which supports both ends of a pyroelectric photoreceptor element 2 so that the central part of the element 2 can float from the substrate 3 are formed on both sides of the section 3a. When the title detector makes self-judgment, a pulsative voltage is applied across a voltage applying pin 8b. As a result, an electric current flows through an electrode pattern 4a between the pin 8b and grounding pin 8c and the pattern 4a generates heat. Therefore, the pyroelectric substance of the element 2 is heated and generates electric charges as polarization advances. Namely, when the pulsative voltage is applied across the pin 8b, the pseudoexecution of the same state as that produced when infrared detectors receive infrared rays can be carried out and the detector can make the self- judgment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pyroelectric infrared detector having a self-diagnosis function.

[0002]

2. Description of the Related Art An infrared detector that detects the presence or passage of an object by detecting infrared rays emitted from the object is widely used, and one of them is a pyroelectric infrared detector using a pyroelectric body. Has been. The pyroelectric light receiving element (ceramic material)
Pyroelectric infrared detectors use this element because it has the property that polarization progresses and charges are generated due to temperature rise. And heat to generate an electric charge,
The electromotive force detects infrared rays.

Since the pyroelectric body is inherently susceptible to the temperature, in order to improve the accuracy of the infrared detector using the pyroelectric body light receiving element, the pyroelectric body light receiving element is heated from the parts which may generate heat. Need to be separated. Therefore, among conventional infrared detectors, there are some infrared detectors in which the both ends of the pyroelectric light receiving element are supported by pillows so that the central portion is floated from the substrate so that heat from other components is not easily transmitted through the substrate. Also,
In Japanese Patent Application No. 1-125568, when the pyroelectric light receiving element is mounted on the substrate, the surface of the substrate is shaped so that the central part of the pyroelectric light receiving element is floated to support both ends, and other elements are also passed through the substrate. A method has been proposed in which heat from the components is hard to be conducted.

By the way, since the pyroelectric infrared detector remains in the same state for a long time after being attached, it is necessary to confirm whether or not the pyroelectric infrared detector normally operates after the attachment. A method is used in which a person walks in front and confirms whether or not infrared rays can be detected. With this method, it is not possible to check whether the pyroelectric infrared detector installed in a place where people rarely pass or does not always operate normally, and it is too primitive as a method of confirming operation. is there.

Therefore, recently, a pyroelectric infrared detector having a self-diagnosis function has been provided in which a circuit or an element therefor is incorporated in a detector so that it can be confirmed whether or not the detector operates normally when necessary. Vessels have been proposed. For example, actual development 6
In 2-62278, an infrared transmitter for self-diagnosis is provided in the detector, and infrared rays emitted from the infrared transmitter propagate in the air to heat a pyroelectric light-receiving element and generate electric charges from the pyroelectric body. It has been proposed that the self-diagnosis is performed by doing so.

[0006] As another example, the actual Kaihei 2-105.
Like No. 131, a self-diagnosis is performed by embedding a heater material for self-diagnosis in a pyroelectric light receiving element and heating the pyroelectric material by heating the pyroelectric light receiving element to generate electric charges from the pyroelectric material. Those that do are proposed.

[0007]

In the former infrared detector having an infrared transmitter for self-diagnosis, a separate part called an infrared transmitter is required, which causes a cost increase. Further, when this method is applied to a dual type pyroelectric light receiving element having two pyroelectric bodies, the position where the infrared transmitter is attached in the detector is restricted, and the shape and structure of the detector are restricted. It In addition, the method using an infrared transmitter has a problem that the efficiency is poor and the power consumption increases because radiant heat is used.

On the other hand, in the latter one in which the heater substance for self-diagnosis is embedded in the pyroelectric light receiving element, a foreign substance called a heater substance is embedded in the pyroelectric light receiving element, so that the heat of the pyroelectric light receiving element is increased. The balance of conduction may be lost, and the accuracy as an infrared detector may be impaired.

The present invention has been made in view of the above points, and an object thereof is to provide a pyroelectric infrared detector having an accurate self-diagnosis function at low cost without increasing the number of parts.

[0010]

In order to achieve the above object, the present invention provides a MID substrate having on its surface an electrode for connection with an external circuit including an electrode for ground connection, and the electrode on the MID substrate. A pyroelectric light receiving element which is electrically connected to and is arranged so that the center thereof floats, and a terminal for energizing the ground connection electrode, and at least the ground connection electrode is made of a heat-generating material. Then, the self-diagnosis is performed by energizing the ground connection electrode through the terminal to generate heat. The MID substrate mentioned here is a molded interconnect device (molded interposer).
-Connection) or a circuit molded product substrate, the part on the substrate where the electrode pattern is to be attached is first molded with a resin that can be metal plated, and then the part that does not require an electrode pattern is molded with a resin that cannot be metal plated. After that, a method of plating with a metal for electrodes is manufactured by a method called a two-color molding method or a two-shot molding method.

[0011]

According to the present invention having the above structure, when the ground connection electrode formed on the MID substrate is energized through the newly provided terminal for self-diagnosis, the electrode generates heat and heats the pyroelectric light receiving element. . The heat transmitted to the pyroelectric light receiving element due to this heating raises the temperature of the pyroelectric element, and electric charges are generated in the pyroelectric element in the same manner as when the pyroelectric light receiving element is irradiated with infrared rays, and self-diagnosis can be performed. .

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

FIG. 1 shows an exploded perspective view of an embodiment of a pyroelectric infrared detector according to the present invention using a dual type pyroelectric light receiving element. A dual-type pyroelectric light receiving element is a device in which two pyroelectric elements are connected in series with opposite polarities, and when the temperature of the entire pyroelectric light receiving element rises, the charges generated from the two pyroelectric elements are generated. By canceling each other, it is possible to prevent erroneous detection of infrared rays due to heat generation of other components instead of infrared rays from the detection target.

In the figure, 2 is a pyroelectric light receiving element, 3 is M
A recess 3a is formed in the center of the upper surface of the ID substrate, and element support portions 3b and 3c are formed on both sides of the recess 3a for supporting both ends of the pyroelectric light receiving element 2 and for floating the central portion from the substrate. On the surface of the substrate 3, from the concave portion 3a to the element supporting portion 3
The electrode pattern 4a is formed so as to extend over
An electrode pattern 4b is formed over the element supporting portion 3c, and electrode patterns 4c and 4d are formed in the recess 3a. 5 is an FET used in the source follower, 6 is FE
A resistor connected between the gate of T5 and the ground, 7 is an infrared transmission filter attached to the upper surface of the case 10 for passing only infrared rays emitted from the detection target,
8a is a drain pin connected to the drain terminal of the FET 5, 8b is a voltage applying pin for applying a voltage for self-diagnosis, 8c is a GND pin connected to ground, and 8d is FE.
Source pin connected to the source terminal of T5, 9 is MID
A base 10 for mounting the substrate 3 is a case having an infrared transmitting filter 7 and enclosing the MID substrate 3 and the elements mounted thereon. Hereinafter, in all the drawings, the same reference numerals as those in FIG. 1 indicate the same constituent members.

FIG. 2 is a plan view of the electrode pattern of the pyroelectric infrared detector shown in FIG.

The electrode pattern 4a is an electrode for ground connection, and the electrode pattern 4a has a GND pin 8c and a voltage application pin 8b serving as a current-carrying terminal for self-diagnosis.
The resistor 6 is electrically connected to the electrode pattern 4b.
Is connected to the gate terminal of the FET 5 and the resistor 6, and the electrode pattern 4c is connected to the drain pin 8a and the FE.
The drain terminal of T5 is connected. The electrode pattern 4d connects the source pin 8d to the source terminal of the FET 5. The material of the electrode pattern 4a is a resistor such as ruthenium oxide, and the material of the electrode patterns 4b, 4c and 4d is silver or the like as in the conventional case.

FIG. 3 shows an electrode pattern of a conventional pyroelectric infrared detector. In the figure, the same components as those in FIG. 2 are shown with the same reference numerals.

As can be seen by comparing this figure with FIG. 2 showing the electrode pattern of the pyroelectric infrared detector according to the present invention,
The two are different in that a voltage application pin 8b for electrically connecting to the electrode pattern 4a and applying a voltage for self-diagnosis is provided, and the material of the electrode pattern 4a is a resistor.

FIG. 4 is a sectional view showing a pyroelectric light receiving element mounted on the MID substrate.

As shown in the figure, the pyroelectric light receiving element 2 is
Both ends are supported by the supporting portions 3b and 3c of the ID substrate 3, and the central portion is floated. The electrode patterns 4a and 4b are provided.
Is in contact with the pyroelectric light receiving element 2, and the electrode pattern 4a
It is arranged so that the heat generated in the above can be directly transmitted to the pyroelectric light receiving element 2.

FIG. 5 is an electrical connection diagram of the pyroelectric infrared detector according to the present invention.

In the figure, 2a is a pyroelectric material embedded in the pyroelectric light receiving element 2, which is an electrode pattern 4 made of a resistor.
The resistance value of a extends over the entire area between the GND pin 8c and the voltage application pin 8b (the portion surrounded by the alternate long and short dash line in the figure), but is represented by the resistance R as a representative in FIG.

When the pyroelectric infrared detector 1 is to be self-diagnosed, a pulse voltage is applied to the voltage applying pin 8b, which is an energizing terminal. As a result, the voltage applying pin 8b and the GN
A current flows through the electrode pattern 4a between the D pin 8c and the pin to generate heat, and the heat heats the pyroelectric light receiving element 2 (see FIG. 4), whereby the pyroelectric body 2a is heated, and as a result, the pyroelectric body 2a is heated. In the electric body 2a, polarization progresses and charges are generated. That is, by applying the pulse voltage to the voltage applying pin 8b,
The same state as when the infrared detector receives infrared light can be artificially created, and the self-diagnosis of the pyroelectric infrared detector can be performed.

In this embodiment, only the material of the electrode pattern 4a is used as the resistor, but the electrode patterns 4a, 4b, 4c,
All the materials of 4d may be used as the resistor.

[0025]

As described above, according to the present invention,
A new voltage application pin for applying the voltage for self-diagnosis is newly provided, and the material of the electrode pattern extending over the voltage application pin and the GND pin is made to be a resistor, and the self-diagnosis function is achieved without increasing the number of other parts. Can be given.

Further, according to the present invention, since the electrode pattern generates heat only by applying the voltage for self-diagnosis to the voltage applying pin and the heat is directly transmitted to the pyroelectric light receiving element, an infrared transmitter is used. The power consumption can be reduced as compared with the conventional method of transmitting heat to the pyroelectric light receiving element by radiant heat.

Further, since it is not necessary to modify the pyroelectric light receiving element itself, the pyroelectric light receiving element can be maintained to be bilaterally symmetrical, so that the heat conduction balance in the pyroelectric light receiving element is disturbed. Infrared can be detected accurately.
Furthermore, according to the present invention, in the case of a dual type pyroelectric light receiving element, the electrode pattern formed of resistors for self-diagnosis is preheated to correct the sensitivity balance of the pyroelectric light receiving element. You can Moreover, according to the present invention, it is possible to provide a smaller infrared detector as compared with the infrared detector incorporating the infrared transmitter.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of an embodiment of a pyroelectric infrared detector according to the present invention using a dual type pyroelectric light receiving element.

FIG. 2 is a plan view showing an electrode pattern of the pyroelectric infrared detector according to the present invention shown in FIG.

FIG. 3 is a plan view showing an electrode pattern of a conventional pyroelectric infrared detector.

FIG. 4 is a cross-sectional view showing a state in which a pyroelectric light receiving element is mounted on a MID substrate.

FIG. 5 is an electrical connection diagram of the pyroelectric infrared detector according to the present invention.

[Explanation of symbols]

 2 Pyroelectric light receiving element 2a Pyroelectric body 3 MID substrate 3a Recessed portion 3b, 3c Element support portion 4a Electrode pattern 8b Voltage application pin 8c GND pin

Claims (3)

[Claims] 1. A MID substrate having on its surface an electrode for connection to an external circuit including an electrode for grounding connection, and a focal point arranged on the MID substrate so as to be electrically connected to the electrode and to float in the center. An electric light receiving element and a terminal for energizing the electrode for earth connection, at least the electrode for earth connection is formed of a heat-generating material, and the electrode for earth connection is formed through the terminal. A pyroelectric infrared detector characterized in that self-diagnosis is performed by energizing it to generate heat. 2. The pyroelectric infrared detector according to claim 1, wherein the exothermic material is ruthenium oxide. 3. The pyroelectric infrared detector according to claim 1, wherein the pyroelectric light receiving element is composed of two pyroelectric bodies connected in series with mutually opposite polarities.