JPH0666630A - Pyroelectric array sensor - Google Patents

Abstract

(57) [Summary] [Purpose] Simple, low cost, temperature change of the base material,
Provided is an array sensor for a radiation temperature distribution measuring device, which is not affected by vibration. A plurality of electrode pairs having a pair of a light receiving electrode 20 and a compensating electrode 22 are arranged on the surface of a pyroelectric substrate 10, lead portions 21 and 23 of each electrode are provided, and an electrode pair is provided on the back surface of the substrate 10. Opposing electrodes 24 are provided at positions facing each other, and an infrared selective transmission substrate 40 is provided on the pyroelectric substrate 10 so that the light receiving electrode 20 is in a state for infrared irradiation and the compensation electrode 22 is in an infrared shielding state. .

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the shape of a pyroelectric 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, LiTaO3 and PbTiO3 are used as the material, the glycine sulfate-based material is used as the base material, and a crystalline material is used as LiTaO3 and the like, and PbTi is used.
Since it is difficult to form crystals in the O3 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 electrode pair in which an infrared ray receiving electrode and a compensating electrode are paired on the surface of a crystal or ceramic body having a pyroelectric effect. Arrange multiple lines at regular intervals,
Leads from the light receiving electrode and the compensating electrode to the external electric circuit are provided respectively, and a counter electrode is provided on the back surface of the substrate at a position facing the electrode pair, and the light receiving electrode is irradiated with infrared rays. This is characterized in that a light receiving window is provided so as to be in such a state, and the compensation electrode is in an infrared ray 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). Furthermore, by providing the lead portion of each electrode on the surface of the pyroelectric substrate, the assembly of the sensor element is facilitated.

[0007]

【Example】

(Embodiment 1) FIGS. 1 and 2 show a schematic structure of a pyroelectric part for explaining an embodiment of the present invention. As shown in FIG. 1, a thin plate is formed by cutting and polishing. PbT
A plurality of light receiving electrodes 20 and compensating electrodes 22 are provided on the surface of the pyroelectric substrate 10 made of iO3 or the like by vapor deposition or sputtering, and at the same time, the electrodes are each the light receiving electrode lead portion 21.
And a compensation electrode lead portion 23 are provided. Further, on the back surface of the pyroelectric substrate 10, by vapor deposition or sputtering method,
A counter electrode 24 is formed at a position facing the light receiving electrode 20 and the compensation electrode 22, respectively. 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, and the distance between the light receiving electrode 20 and the compensation electrode 22 is 500 μm to 2 mm.
Is good. Further, it is desirable that the light receiving electrode and the compensation electrode have the same area. The wire width at the lead of each electrode is 20-
100 μm is good.

Next, as shown in FIG. 1, the pyroelectric substrate 10 is used.
By disposing the infrared selective transmission substrate 40 having the infrared selective transmission window 41 on the front surface of the light receiving surface, the infrared ray 50 is irradiated only to the light receiving electrode 20 and the compensation electrode 22 is shielded.

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 22 side by the infrared selective transmission substrate 40, but are irradiated only to the light receiving electrode 20 side. Further, the infrared rays 50 are 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 between the infrared transmission lens 60 and the pyroelectric substrate 10, and is preferably fixed at a position of several mm or less on the pyroelectric substrate 10.

FIG. 4 shows a principle diagram of an equivalent circuit of one light receiving portion. R1, R2 and R3 represent resistors, 80 is an amplifier circuit, and the light receiving portion 25 is formed by the light receiving electrode 20 and the counter electrode 24 below the light receiving electrode via the pyroelectric substrate 10. The compensating portion 26 is formed of the compensating electrode 22 and the counter electrode 24 below the compensating electrode via the pyroelectric substrate 10.

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.

Now, as shown in FIG. 5, the pyroelectric substrate 10 is mounted on a circuit board 30 having a concave portion on the substrate, and as shown in FIG. 6, each electrode lead portion and the extraction electrode 3 on the circuit board.
By electrically connecting 1 and 1 with the conductive paste 32, the thinned pyroelectric substrate can be stably held, and the connection of the lead portion for signal extraction can be achieved by a highly reliable method. A ceramic substrate, a glass epoxy substrate, a polyimide substrate, or the like can be used as the circuit substrate.

Actually, ten light-receiving electrodes and compensating electrodes were formed in an array on the same pyroelectric substrate, and measurement was performed using an infrared lens system having an angle of view of 80 degrees. 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 motor to form an array of light receiving electrodes. The motor is driven while chopping with the shape direction (long axis direction) as the vertical direction.
The temperature distribution was measured while rotating the rotating part intermittently in the lateral direction so that the direction in which the sensor and the lens face were rotated to the left and right. After measurement, the vertical temperature distributions in each direction are connected by electrical signal processing,
A dimensional inversion temperature distribution was obtained. The spatial resolution in the lateral (left and right) direction depends on the rotation angle of the motor for each chopping time. For example, when a signal is input every 3.6 degrees rotation and a total of 180 degrees rotation is performed, The spatial resolution in the horizontal direction is 50, and the spatial resolution in the vertical direction is 10 as described above. Therefore, when viewed from the sensor position, the vertical 80 degrees and the horizontal 1
Spatial resolution of 10 * 5 with an accuracy of ± 0.2 ° C in a space of 80 degrees
The temperature distribution could be measured with a resolution of 0.

As described above, 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.

(Embodiment 2) Regarding the shape of the pyroelectric electrode described in Embodiment 1, as shown in FIG. 7A, the compensating electrode formed on the surface of the pyroelectric substrate is one wide common electrode and the compensating electrode 27. And At this time, the counter electrode 24 is arranged so as to face the compensation electrode 27 as shown in FIG.

With the above construction, the lead portion 23 of the compensation electrode is one, and the wiring from the pyroelectric substrate to the external electric circuit can be extremely simple and simplified.

Further, as shown in FIG. 7C, the counter electrode is not particularly limited in shape as long as it covers the facing portion of the light receiving electrode and the compensating electrode.

(Embodiment 3) FIGS. 8 and 9 show an example of an electrode pattern of another embodiment formed on a pyroelectric substrate.

As shown in the figure, two rows of electrode groups consisting of the light receiving electrodes 20 and the compensation electrodes 23 are provided on the surface 11 of the pyroelectric substrate. At this time, the adjacent distance between the rows is 10-
It was set to 200 μm. Reference numerals 21 and 22 are lead portions for connecting each electrode to an external electric circuit. Back side of pyroelectric substrate 1
2 is provided with a counter electrode 24 at a position facing the light receiving electrode and the compensation electrode, respectively. The size of each electrode is the same as that of the first embodiment. Note that in FIG. 9, the compensation electrode is shared.

Actually, 10 rows of light-receiving electrodes and compensation electrodes are formed in two rows on the same pyroelectric substrate in an array form, 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 measure accurately with a spatial resolution of 2 * 10 with 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 motor to receive light. With the array direction of the electrodes (longitudinal direction) as the vertical direction, the motor is driven while the chopping is applied, and the rotating part is rotated in the horizontal direction to scan the direction in which the sensor and the lens face left and right. , The temperature distribution was measured. 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 and right) direction depends on the rotation angle of chopping for each time. For example, when a signal is input at every step of rotation of 3.6 degrees and a total of 180 degrees is rotated. , The horizontal spatial resolution is 100, and the vertical spatial resolution is 10 as described above. Therefore, when viewed from the sensor position, the vertical is 80 degrees and the horizontal is 1
Spatial resolution of 10 * 1 with an accuracy of ± 0.2 ° C in a space of 80 degrees
The temperature distribution could be measured with a resolution of 00.

As described above, 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.

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, the lead portions can be easily pulled apart, and the electrodes can be pulled out from both sides. Further, for the purpose of reducing the lead portion, as shown in FIG. 9, the compensation electrode formed on the surface of the pyroelectric substrate is used as a common electrode with one wide electrode. At this time, all the counter electrodes formed on the back surface of the pyroelectric substrate are arranged so as to face the compensation electrodes. With the above configuration, the number of lead portions 23 of the compensation electrode is two, and the wiring from the pyroelectric substrate to the external electric circuit can be extremely simple and simplified.

(Embodiment 4) FIGS. 10 and 11 show another embodiment in which a pyroelectric substrate is installed on a circuit board. In the figure, the circuit board 30 is provided with an opening slightly smaller than the pyroelectric substrate, and the pyroelectric substrate is placed on the opening. Then, the lead portion and the take-out electrode 31 are electrically conductive paste 3
Connect with 1. Since the pyroelectric substrate has a thickness of several tens of μm, the electrodes can be easily taken out.

In the first embodiment, the example of embedding in the circuit board is shown, but as long as the electrode forming portion of the pyroelectric board does not directly contact the circuit board to conduct heat, it is as described above. It may be installed on the circuit board. In addition, the circuit board may be provided with a slight protrusion to float the pyroelectric substrate. For example, as shown in FIGS. 12 and 13, it is preferable to use the thickness of the extraction electrode 31 and place the pyroelectric substrate 10 on the electrode to form a gap between the circuit substrate and the pyroelectric substrate.

[0029]

As is apparent from the above description, the present invention provides an array sensor for detecting infrared rays, which includes an infrared ray receiving electrode and a compensating electrode on the surface of a crystal or ceramic body having a pyroelectric effect. A plurality of electrode pairs including a pair of electrodes are arranged in a line at regular intervals, and electrode lead-out portions from the light receiving electrode and the compensation electrode to an external electric circuit are provided respectively, and the back surface of the substrate faces the electrode pairs. The structure is such that counter electrodes are provided at respective positions, the infrared receiving electrode is provided with a light receiving window so as to be in an infrared irradiating state, and the compensating electrode is provided with an infrared light shielding state. From (1) the temperature change of the base material and the charge density change of the pyroelectric surface caused by vibration are canceled by the compensation electrode on the electric circuit, and the incident infrared ray amount (heat amount) irradiated to the light receiving electrode can be accurately measured. It is possible to measure.

Further, the light receiving portions are arranged in two rows so that the respective extraction electrodes and the electrode connecting portions do not face each other. (2) A malfunction which is two-dimensional and is not affected by temperature change or vibration is minimized. (3) By providing the lead portion on the surface of the pyroelectric substrate, the sensor element can be easily assembled.

[Brief description of drawings]

FIG. 1 is a perspective view showing a relative positional relationship between a pyroelectric substrate and an infrared selective transmission substrate in a pyroelectric array sensor according to an embodiment of the present invention.

FIG. 2 is a schematic view showing a specific electrode pattern in the pyroelectric array sensor of the example of the present invention.

FIG. 3 is a conceptual diagram of a measuring device according to an embodiment of the present invention.

FIG. 4 is a circuit diagram for explaining a pyroelectric electric circuit according to an embodiment of the present invention.

FIG. 5 is an exploded perspective view showing how the pyroelectric body portion of the pyroelectric array sensor of the embodiment of the present invention is attached to the circuit board.

FIG. 6 is a perspective view showing an assembled state of the embodiment.

FIG. 7 is a schematic view showing an electrode pattern in the pyroelectric array sensor of the example of the present invention.

FIG. 8 is a schematic view showing an electrode pattern in the pyroelectric array sensor of the example of the present invention.

FIG. 9 is a schematic view showing an electrode pattern in the pyroelectric array sensor of the example of the present invention.

FIG. 10 is an exploded perspective view showing how the pyroelectric body portion of the pyroelectric array sensor of the embodiment of the present invention is attached to the circuit board.

FIG. 11 is a perspective view showing an assembled state of the embodiment.

FIG. 12 is an exploded perspective view showing how the pyroelectric body portion of the pyroelectric array sensor of the embodiment of the present invention is attached to the circuit board.

FIG. 13 is a perspective view showing an assembled state of the embodiment.

[Explanation of symbols]

 10 Pyroelectric Substrate 11 Pyroelectric Substrate Front Surface 12 Pyroelectric Substrate Rear Surface 20 Light-Receiving Electrode 21 Light-Receiving Electrode Lead 22 Compensation Electrode 23 Compensation Electrode Lead 24 Counter Electrode 25 Light-Receiving 26 Compensation 27 Common Compensation Electrode 30 Circuit Board 31 Extraction electrode 32 Conductive paste 40 Infrared selective transmission substrate 41 Infrared selective transmission window 50 Infrared 60 Infrared transmission lens 70 Chopper 80 Amplification circuit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tomohiro Tsuruta 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (6)

[Claims] 1. A plurality of electrode pairs, each of which includes an infrared light receiving electrode and a compensating electrode, are arranged in a line at regular intervals on the surface of a pyroelectric substrate, and the light receiving electrode and the compensating electrode are connected to an external electric circuit. Each of the lead portions is provided, a counter electrode is provided on a back surface of the pyroelectric substrate at a position facing the electrode pair, and the light receiving electrode is in a state for infrared irradiation on the pyroelectric substrate, and The pyroelectric array sensor characterized in that the compensating electrode is provided with an infrared selective transmission substrate for blocking the infrared rays. 2. A plurality of electrode pairs, each of which includes an infrared light receiving electrode and a compensating electrode, are arranged in a line in two rows at regular intervals on the surface of a pyroelectric substrate, and the light receiving electrode and the compensating electrode form an external electric circuit. And a counter electrode is provided on the back surface of the pyroelectric substrate at a position facing the electrode pair so that the counter electrode does not face the lead part formed on the substrate surface as much as possible. The pyroelectric array sensor according to claim 1, wherein: 3. The pyroelectric array sensor according to claim 1, wherein the compensation electrode is a common electrode for one wide electrode. 4. A concave portion corresponding to the size of the pyroelectric substrate is provided on the external electrode circuit board, the pyroelectric substrate is installed in the concave portion, and the lead portion and the external electric circuit are electrically connected. The pyroelectric array sensor according to claim 1 or 2, characterized in that: 5. The pyroelectric array sensor according to claim 1, wherein the counter electrode forming portion of the pyroelectric substrate is not in contact with the external circuit substrate. 6. The method according to claim 1, wherein a gap is provided between the pyroelectric substrate and the circuit board, and at least the counter electrode forming portion of the pyroelectric substrate is not in contact with the circuit board. Pyroelectric array sensor.