JPH0460426A - Heat coil sensor and method for diagnosing the same - Google Patents

Abstract

PURPOSE:To easily verify operation of a pyroelectric element with a simple structure and low power consumption by making luminous a light emitting element which is placed in the vicinity of the pyroelectric element at predetermined frequencies and detecting existence of an output of the pyroelectric element synchronously with the light emission. CONSTITUTION:When operation of a pyroelectric element 2 is to be verified, a diagnosis apparatus 11 is connected to a heat coil sensor. The diagnosis apparatus 11 supplies pulses 12 at predetermined frequencies to an LED 10, also takes an output of a source of a FET 1 via an amplifier 13, senses whether or not the outputs of the FET 1 can be obtained synchronously with the pulses 12 and outputs the results. That is, since the LED 10 flashes with frequencies of the pulses 12, if the outputs can be obtained from the FET 1 synchronously with the flashing of the LED 10, normal operation of the pyroelectric element 2 can be verified. An output of the diagnosis results can be done by means of lamp indication or an output by a printer, etc. Thus easy verification of pyroelectric element operation is possible with a simple structure and low power consumption.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a heat ray sensor and a diagnostic method thereof.

[Prior Art] Conventionally, in alarm systems and the like, heat rays emitted from the human body using a pyroelectric element are used as sensors to detect the human body.
That is, heat ray sensors that detect changes in the amount of incident far infrared rays are known.

An example of its configuration is shown in FIG. FIG. 3(a) is a diagram showing the circuit configuration of a conventional heat ray sensor, and FIG. 3(b) is a sectional view of the heat ray sensor.

As shown in FIG. 3(a), the drain and source of a field effect transistor (hereinafter referred to as FET) 1 are connected to a terminal TIIT2, respectively, and the gate of FET1 is connected to a parallel circuit consisting of a pyroelectric element 2 and a resistor 3. One end of the parallel circuit is connected, and the other end of the parallel circuit is connected to the terminal Ts.

These FET 1, pyroelectric element 2 and resistor 3 are shown in Figure 3 (b
), the terminals T+ and T2 are connected on the board 4.
．． Ts is connected to pin 7. In addition, Fig. 3(b)
Although the resistor 3 is omitted and only two pins 7 are shown, the other pins are omitted.

The substrate 4 on which the FET 1, pyroelectric element 2, and resistor 3 are mounted is sealed with a metal can 6 provided with a window 5 formed of a filter that transmits only far infrared rays with a wavelength of about 7 μm to 5 μm. ing. Since the pyroelectric element 2 has sensitivity from far infrared to near infrared to the visible range, window 5 is provided to transmit only far infrared rays of the desired wavelength to be detected. be.

By the way, in a heat ray detector equipped with a heat ray sensor, the pyroelectric element 2 may not operate normally due to external factors or lifespan, so the pyroelectric element 2 may not operate normally after the heat ray detector is installed. It is necessary to check whether
To this end, conventional methods have been used in which a person crosses the viewing angle of the heat ray sensor to cause a temperature change, and the amount of far infrared rays incident on the pyroelectric element 2 is changed to check the operation, or as shown in Fig. 4. As shown, a method is adopted in which a resistor 8 made of carbon resistor or the like is placed within the viewing angle of the heat ray sensor, and a current is supplied to the resistor 8 to cause it to emit far-infrared rays to check the operation of the pyroelectric element 2. has been done.

[Problems to be Solved by the Invention] However, the above two methods for checking the operation of the pyroelectric element have the following problems. In other words, in the former method, the structure is simple because there is no need to perform any processing on the heat ray sensor itself, but when a person actually crosses within the viewing angle of the heat ray sensor, In the latter method, the resistor 8 is placed within the viewing angle of the heat ray sensor, and a current is applied to the resistor 8. In this case, the current supplied to resistor 8 must be large to be effective.
This not only complicates the structure such as insulation, but also poses problems in terms of power consumption.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a heat ray sensor that has a simple structure, low power consumption, and can easily check the operation of a pyroelectric element, and a method for diagnosing the same. It is something to do.

[Means for Solving the Problems] In order to achieve the above object, the heat ray sensor of the present invention has the following features:
A heat ray sensor including a pyroelectric element is characterized in that a light emitting element is disposed near the pyroelectric element, and a diagnostic method for a heat ray sensor of the present invention includes a pyroelectric element and a light emitting element disposed near the pyroelectric element. A method for diagnosing a heat ray sensor equipped with a light emitting element, characterized by causing the light emitting element to emit light at a predetermined period, and detecting the presence or absence of an output from the pyroelectric element in synchronization with the light emitting element.

[Operations and Effects of the Invention] The present invention has a simple configuration in which a light emitting element is placed near the pyroelectric element, and the operation of the pyroelectric element can be checked by checking the operation of the light emitting element at a predetermined period under normal usage conditions. This can be done easily by blinking the pyroelectric element and checking the presence or absence of the output from the pyroelectric element in synchronization with the flashing.

Furthermore, since a low current is sufficient to be supplied to the light emitting element, the structure is simple.

[Example] Examples will be described below with reference to the drawings.

FIG. 1 is a diagram showing the configuration of an embodiment of the hot ray sensor according to the present invention, FIG. 1(a) shows the circuit configuration of the hot ray sensor, and FIG. 1(b) shows a cross-sectional view of the hot ray sensor. . Components that are the same as those in FIG. 3 are given the same numbers.

In FIG. 1(a), the drain and source of FET2 are connected to terminals T+ and Ti, respectively, and the gate of FET1 is connected to a part of a parallel circuit consisting of a pyroelectric element 2 and a resistor 3, and other parts of the parallel circuit are connected to the gate of FET1. The end is connected to terminal T. In addition, a light emitting diode (hereinafter referred to as
10 (referred to as LED) are connected.

Then, as shown in FIG. 1(b), the FETI, the pyroelectric element 2, and the resistor 3 are connected on the substrate 4, and the terminals T1.
T e and T a are connected to pin 7, and in addition, LEDIO is located near the pyroelectric element 2 and placed in a position where the emitted light can enter the pyroelectric element 2. Terminal T4 is connected to pin 7. The light emitted by the LEDIO is usually in the infrared or visible range, but as mentioned above, the pyroelectric element 2 has sensitivity from the far infrared to the visible range, so the LEDIO emits light in the visible range. The pyroelectric element 2 can detect it even if it is an object. Note that the resistor 3 is omitted in FIG. 1(b). Also,
Only two pins 7 are shown, but the other pins are omitted.

Then, FET1, pyroelectric element 2, resistor 3 and LEDIO
The board on which is mounted is sealed with a metal can 6 in which a window 5 is formed. The window 5 has a wavelength of 7 μm as described above.
It is formed of a filter that transmits only far infrared rays of about 15 μm.

Next, a method for checking the operation of the pyroelectric element in the heat ray sensor according to the present invention shown in FIG. 1 will be described. When checking the operation of the pyroelectric element 2, as shown in Fig. 2,
Connect the diagnostic device W11 to the heat ray sensor. diagnostic equipment full
supplies pulse 12 of a predetermined period to LEDIO, captures the output of the FETI source via amplifier 13, detects whether or not the FETI output is obtained in synchronization with pulse 12, and outputs the result. do. That is, LEDI
Since O blinks at a period of pulse 12, if an output is obtained from FETI in synchronization with the blinking of LEDlo, pyroelectric element 2
It can be confirmed that it is working properly. The diagnostic results can be output by displaying a lamp or using a printer.

Although not shown in FIG. 2, it is a matter of course that a predetermined voltage is applied to T and T in FIG.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible. For example, in the above embodiment, an LED is arranged, but it is clear that any light emitting element that emits light within the range to which the pyroelectric element is sensitive can be used. Further, the configuration shown in FIG. 2 is merely an example, and any configuration that can detect the output in synchronization with the light emission of the light emitting element may be used.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of an embodiment of the heat ray sensor according to the present invention, FIG. 2 is a diagram showing the configuration of an embodiment of the heat ray sensor diagnostic method according to the present invention, and FIG. 3 is a diagram showing the configuration of an embodiment of the heat ray sensor diagnostic method according to the present invention. FIG. 4 is a diagram showing an example of the configuration of a sensor, and FIG. 4 is a diagram showing an example of a conventional method for diagnosing a heat ray sensor. 1...FET12...Pyroelectric element, 3...Resistor, 4
... Board, 5... Window, 6... Metal can, 7...
・Pin, 8...Resistance, 10...LED, 11...
Diagnostic equipment. Applicant Atsumi Electric Co., Ltd.

Claims (2)

[Claims] (1) A heat ray sensor including a pyroelectric element, characterized in that a light emitting element is disposed near the pyroelectric element. (2) A method for diagnosing a heat ray sensor comprising a pyroelectric element and a light emitting element disposed near the pyroelectric element, in which the light emitting element is caused to emit light at a predetermined period, and in synchronization therewith, the pyroelectric element is activated. A diagnostic method for a heat ray sensor, characterized by detecting the presence or absence of an output.