JPH053346A - Pyroelectric array sensor - Google Patents

Abstract

PURPOSE:To provide a simple and inexpensive array sensor for radiant temperature distribution measuring instruments. CONSTITUTION:This pyroelectric array sensor is constituted in such a way that a plurality of electrode pairs, each of which is composed of a light receiving electrode 20 and compensating electrode 21, is arranged on the surface of a pyroelectric substrate 10 and paired electrodes 30 and 31 are provided at positions corresponding to the electrode pairs on the rear surface of the substrate 10. In addition the electrodes 20 are irradiated with infrared rays and the electrodes 21 are not irradiated with the infrared rays.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pyroelectric array sensor for detecting infrared rays, especially heat rays.

[0002]

2. Description of the Related Art Conventionally, pyroelectric sensors for detecting infrared rays, particularly heat rays, are provided by providing electrodes on both sides of a base material having a pyroelectric effect and detecting by utilizing a change in potential between the electrodes due to infrared irradiation. Is. Ferroelectric materials such as glycine sulfate-based, polyvinylidene fluoride-based, LiTaO ₃ and PbTiO ₃ are used as the material, glycine sulfate-based material is used as the base material, and crystalline materials are used as LiTaO _{3 and the} like, and PbTi is used.
Since it is difficult to form crystals in the O ₃ system, it is common to use a sintered ceramic or a thin film formed by a thin film technique.

[0003]

Although the thin film sensor has high sensitivity, it has problems in cost and reliability. On the contrary,
The crystal body and the ceramic body are characterized in that they are excellent in productivity and reliability. When the crystal body or ceramic body is thinned by cutting / polishing, and electrodes are formed on the outer substrate to form an array sensor in which sensor elements are arranged in a line, the output is sensitive to the temperature change and vibration of the substrate. There was a problem that the voltage changed.

The present invention has been tried in view of the above-mentioned problems, and provides a low cost and highly reliable array sensor using a crystal body or a ceramic body.

[0005]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides an infrared ray receiving electrode on the surface of a crystal or ceramic body having a pyroelectric effect and a compensation for electrically contacting the electrode. A plurality of electrode pairs, each of which is a pair of electrodes for electrodes, are arranged in a line at predetermined intervals, and counter electrodes are provided on the back surface of the substrate at positions facing the electrode pairs, and electrodes from the counter electrodes to an external electric circuit are provided. It is characterized in that each of the lead-out portions is provided, a light-receiving window is provided in the infrared light-receiving portion electrode so that the infrared light is irradiated, and the compensating electrode is in the infrared light-shielding state.

[0006]

According to the present invention, with the above-described configuration, the output of each sensor is not affected by the temperature change and vibration of the base material.
This makes it possible to accurately measure the amount of incident infrared rays (heat amount).

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1, FIG. 2 and FIG. 3 show a schematic structure of a pyroelectric part for explaining an embodiment of the present invention. As shown in FIG. A plurality of light receiving electrodes 20 and compensating electrodes 21 are provided on the surface of the pyroelectric substrate 10 made of PbTiO ₃ or the like by vapor deposition or sputtering, and the electrodes are electrically connected by electrode connecting portions 22. . Further, on the back surface of the pyroelectric substrate 10, a counter electrode 30 for the light receiving electrode and a counter electrode 31 for the compensation electrode are provided at positions facing the light receiving electrode 20 and the compensation electrode 21, respectively, by an evaporation method or a sputtering method, and each is connected to an external circuit. An electrode lead-out portion 32 for connection is formed. Each electrode pattern may be formed by a metal mask method or photolithography. At this time, the distance between adjacent light receiving electrodes is 10 to 200 μm, the distance between the light receiving electrode 20 and the compensating electrode 21,
That is, the length of the electrode connecting portion 22 is from 500 μm to 2 m.
m is good. Further, it is desirable that the light receiving electrode and the compensation electrode have the same area. The line width at the electrode connection portion and the electrode lead-out portion is preferably 20-100 μm.

Next, as shown in FIG. 2, an infrared selective transmission substrate 40 having an infrared selective transmission window 41 is arranged on the front surface of the light receiving surface of the pyroelectric substrate 10 so that the light receiving electrode 2
The infrared ray 50 is irradiated only on 0, and the compensation electrode 2
The light-shielding state is set to 1.

FIG. 3 shows the relative positions of the infrared transmission lens 60 and the chopper 70 for focusing infrared rays on the pyroelectric substrate 10, the infrared selective transmission substrate 40, and the light receiving electrode 20. As a matter of course, the infrared rays after focusing are not irradiated to the compensation electrode 21 side by the infrared selective transmission substrate 40, but to the light receiving electrode 20 side only. Also,
The infrared ray 50 is intermittently incident by the chopper 70 to obtain a pyroelectric output.

The infrared selective transmission substrate 40 is preferably made of a metal material having an electromagnetic wave shielding effect, and the infrared selective transmission window 41 may be covered with a silicon thin plate. The infrared selective transmission substrate 40 is preferably provided in the middle of the infrared transmission lens 60 and the pyroelectric substrate 10.
It is preferable to fix the pyroelectric substrate 10 at a position of several mm or less.

FIG. 4 shows a principle diagram of an equivalent circuit of one light receiving portion. R1, R2, and R3 represent resistances, 60 is an amplifier circuit, and the light receiving portion 25 is formed by the light receiving electrode 20 and the light receiving electrode counter electrode 30 through the pyroelectric substrate 10, and is compensated. The portion 26 is formed of the compensation electrode 21 and the compensation electrode counter electrode 31 with the pyroelectric substrate 10 interposed therebetween.

In FIG. 4, the surface charge (pyroelectric output) of the pyroelectric substrate generally fluctuates due to the temperature change and vibration of the pyroelectric body, or the adsorbed gas species. The capacitance drift of both terminals is VOUT
It is difficult to accurately detect the energy change of the incident infrared ray 50 which is detected as the output. However, by providing the compensation electrode section 26, the fluctuation components due to the above-mentioned factors cancel each other out, the capacitive drift of the output terminal does not occur, and occurs only when the light receiving section 25 is irradiated with infrared rays, The change in the surface charge of the light receiving portion 25 can be amplified and detected as VOUT.

Although the amount of change is slightly different depending on the ambient temperature, an accurate infrared energy change can be measured by monitoring the temperature of the pyroelectric part and making a field back.

Actually, ten light-receiving electrodes and compensating electrodes were formed in an array on the same pyroelectric substrate and measured using an infrared lens system having an angle of view of 80 °. It was possible to accurately measure the dimensional temperature distribution with an accuracy of ± 0.2 ° C. and a spatial resolution of 10 (8 degrees).

Next, the pyroelectric substrate 10, the infrared selective transmission substrate 40, the infrared transmission lens 60, and the chopper 70 are integrated as a rotating portion, and the rotating portion is mechanically connected to a stepping motor to form an array of light receiving electrodes. Direction (long axis direction)
The temperature distribution was measured while the direction in which the sensor and the lens faced was scanned left and right by driving the stepping motor while chopping, and rotating the rotating part intermittently in the horizontal direction with the vertical direction as the vertical direction. . After the measurement, a vertical two-dimensional temperature distribution in each direction was obtained by connecting the vertical temperature distributions in each direction by electric signal processing.
The lateral (left and right) spatial resolution is 1 for stepping motors.
For example, when a signal is input every 3.6 ° rotation and a total of 180 ° rotation is performed, the spatial resolution in the horizontal direction is 50 and the spatial resolution in the vertical direction is as described above. As described above, the temperature distribution can be measured with a spatial resolution of 10 × 50 with an accuracy of ± 0.2 ° C. in a space of 80 ° vertically and 180 ° horizontally as seen from the sensor position.

As described above, by using the sensor of the present invention,
The dimensional temperature distribution measurement can be achieved. The shape of the light receiving electrode is determined by the resolution of the incident field angle, and in the above case, it is preferable that the array direction (vertical): horizontal direction = 5: 1.

Regarding the shape of the pyroelectric electrode described in Embodiment 1, as shown in FIG. 5, the counter electrode for the compensation electrode formed on the back surface of the pyroelectric substrate is one wide electrode and the common electrode 33 for the compensation electrode.
And At this time, the common electrode for the compensation electrode is arranged so as to face all the compensation electrodes 21 formed on the surface of the pyroelectric substrate. With the above configuration, the number of the electrode lead-out portions 32 of the compensation electrode is one, and the wiring from the pyroelectric substrate to the external electric circuit can be extremely simple and simple.

FIG. 6 shows an example of the electrode pattern formed on the pyroelectric substrate. Pyroelectric substrate surface 1 as shown
1 includes a light receiving electrode 20, an electrode connecting portion 22, and a compensating electrode 2.
Two rows of electrode groups consisting of 1 were provided. At this time, the adjacent distance between the columns was set to 10 to 200 μm between the light receiving electrodes. On the back surface 12 of the pyroelectric substrate, a light-receiving electrode counter electrode 30 and a compensation electrode counter electrode 31 are provided at positions facing the light-receiving electrode walking focus electrode. Reference numeral 32 is an electrode lead-out portion for connecting each electrode to an external electric circuit. The size of each electrode is the same as that of the first embodiment.

Actually, 10 rows of light-receiving electrodes and compensating electrodes are formed in two rows on the same pyroelectric substrate in the form of an array, and only the light-receiving electrodes have an infrared selective transmission substrate on the top that allows infrared irradiation. As a result of measurement using an infrared lens system having an angle of view of 80 degrees, the two-dimensional temperature distribution is ± 0.
It was possible to accurately measure with a spatial resolution of 2 × 10 at an accuracy of 2 ° C.

Next, as in the first embodiment, the pyroelectric substrate, the infrared selective transmission substrate, the infrared transmission lens and the chopper are integrated as a rotating portion, and the rotating portion is mechanically connected to a stepping motor to receive light. The direction in which the sensor and the lens are facing is left or right by driving the stepping motor while intermittently rotating the rotating part while chopping with the electrode array direction (long axis direction) as the vertical direction. The temperature distribution was measured while being scanned. After the measurement, a vertical two-dimensional temperature distribution in each direction was obtained by connecting the vertical temperature distributions in each direction by electric signal processing. The spatial resolution in the lateral (left-right) direction depends on the rotation angle of the stepping motor once. For example, when a signal is input at every step of rotation of 3.6 degrees and the total rotation is 180 degrees, The spatial resolution in the vertical direction is 100, and the spatial resolution in the vertical direction is 10 as described above, so a space of 80 degrees in the vertical direction and 180 degrees in the horizontal direction is ± 0.
The temperature distribution could be measured with an accuracy of 2 ° C. and a spatial resolution of 10 * 100.

As described above, by using the sensor of the present invention,
When measuring the dimensional temperature distribution, the resolution could be improved by a factor of two compared to Example 1. Further, if the resolution is the same, the scanning time could be reduced by half.

FIG. 7 shows the confronting state of the light receiving electrode and the compensating electrode with each counter electrode. The malfunction can be minimized by designing the extraction electrode and the electrode connecting portion so as not to confront each other as much as possible. it can.

Further, it is preferable that the light receiving electrode and the compensating electrode have the same shape, but in some cases, if the light receiving electrode and the compensating electrode have the same area as in the embodiment shown in FIG.
The shapes may be different, and by doing so, it becomes easy to separate the electrode lead-out portions on the back surface 32 of the pyroelectric substrate, and the electrodes can be led out from both sides. Also,
For the purpose of reducing the number of lead-out electrode portions, as shown in FIG. 9, the compensating electrode counter electrode formed on the back surface of the pyroelectric substrate is a wide electrode to form the compensating electrode common electrode 33. At this time, the common electrode for compensation electrodes is arranged so as to face all the compensation electrodes 21 formed on the surface of the pyroelectric substrate. With the above structure, the electrode lead-out portion 3 of the compensation electrode is formed.
Since there are two, the wiring from the pyroelectric substrate to the external electric circuit can be extremely simple and simplified.

[0024]

As described above, the array sensor for detecting infrared rays according to the present invention has the following effects. (1) A change in the temperature of the base material and a change in the charge density on the surface of the pyroelectric body caused by vibration are canceled by the compensation electrode on the electric circuit, and the amount of incident infrared light (heat amount) irradiated to the light receiving electrode
It is possible to measure accurately. (2) By forming the light-receiving part in two rows so that the extraction electrodes and electrode connection parts do not face each other, it is possible to create a sensor that is two-dimensional and minimizes malfunctions that are not affected by temperature changes or vibrations. .

[Brief description of drawings]

FIG. 1 is a schematic view of a pyroelectric body portion of a pyroelectric sensor according to an embodiment of the present invention.

FIG. 2 is a relative positional relationship diagram between a pyroelectric substrate and an infrared selective transmission substrate in the same pyroelectric sensor.

FIG. 3 is a conceptual diagram of a measuring device having the same pyroelectric sensor as a constituent element.

FIG. 4 is an electric circuit diagram of the measuring device.

FIG. 5 is a schematic view of a pyroelectric part according to another embodiment of the present invention.

FIG. 6 is a schematic view of a specific electrode pattern in the pyroelectric sensor.

FIG. 7 is a schematic view of a specific electrode pattern in the pyroelectric sensor.

FIG. 8 is a schematic view of a specific electrode pattern in the pyroelectric sensor.

FIG. 9 is a schematic view of a specific electrode pattern in the pyroelectric sensor.

[Explanation of symbols]

10 Pyroelectric substrate 11 Pyroelectric substrate surface 12 Back side of pyroelectric substrate 20 Light receiving electrode 21 Compensation electrode 22 Electrode connection part 25 Light receiving part 26 Compensation Department 30 Counter electrode for light receiving electrode 31 Counter electrode for compensation electrode 32 Electrode extraction part 33 Common counter electrode for compensation electrode 40 Infrared selective transmission substrate 41 Infrared selective transmission window 50 infrared 60 infrared transparent lens 70 chopper 80 amplifier circuit

Claims (3)

[Claims] 1. A plurality of electrode pairs, each of which has a pair of an infrared ray receiving electrode and a compensating electrode electrically contacting the electrode through an electrode connecting portion, are formed on a surface of a substrate having a pyroelectric effect at predetermined intervals in a line form. Arranged, on the back surface of the substrate, a counter electrode is provided at a position facing the electrode pair, respectively, an extraction electrode lead-out portion from the counter electrode to an external electric circuit is provided, and the infrared light receiving electrode is set to an infrared irradiation state. A pyroelectric array sensor characterized by comprising an infrared selective transmission substrate which makes a compensation electrode in a state of blocking infrared rays. 2. A plurality of electrode pairs arranged in a line at predetermined intervals.
Arranged in rows, a counter electrode is provided on the back surface of the substrate at a position facing the electrode pair, and an electrode lead-out portion for extracting from the counter electrode to an external electric circuit is provided in a state not facing the electrode connection portion formed on the surface of the substrate. The pyroelectric array sensor according to claim 1, wherein 3. A back electrode of a substrate having a pyroelectric effect is provided with a counter electrode at a position facing a light receiving electrode, and a common electrode having a wide electrode is provided at a position facing a compensation electrode. The pyroelectric array sensor according to claim 1 or 2.