JPH0652193B2 - Infrared detector - Google Patents

Description

TECHNICAL FIELD The present invention relates to an infrared detection element used for infrared detection such as temperature distribution measurement, earth resource observation, crime prevention / disaster prevention monitoring, and heat management.

2. Description of the Related Art There is a thermistor type infrared detector with an immersion lens that improves the infrared detection performance by directly adhering an infrared detection element to a condensing lens and increasing the condensing efficiency. (Electronic Technology Research Institute Survey Report No. 177 PP
65-66) This thermistor type infrared detecting element collects infrared rays emitted by an object together with heat and detects infrared rays by the change in resistance value of the thermistor caused by the infrared rays.
An example of the structure is shown in (a) and (b). A thermistor element 2 is adhered to the immersion type germanium lens 1, and electrodes 3, 4 for taking out signals and lead wires 5, 6 are attached.

Problems to be Solved by the Invention A drawback of the thermistor type infrared detection element is that it has lower sensitivity than a current collection type infrared detection element. In order to improve this drawback, a combination with an immersion lens for condensing has been considered, but in the case of a thermistor type infrared detection element, the terminal for reading the resistance change can be taken out from the side surface of the element. It is possible, and even if the element is closely attached to the immersion lens, there is no structural problem. However, when applying the immersion lens to the pyroelectric infrared detection element, it is indispensable to form an electrode on the infrared incident surface, that is, the contact surface with the infrared condensing lens and the surface opposite to it, that is, the back side of the infrared incident surface. Moreover, since the pyroelectric element itself is processed to be extremely thin in order to increase the element capacity for increasing the infrared sensitivity, it is impossible to take out the electrode terminal from the side surface of the element like the thermistor type. In addition, it is desirable that the thin plate of the pyroelectric element is as close as possible to the condenser lens and is in contact with the parallel lens with good parallelism in order to improve the condenser efficiency. The present invention solves the above problems and provides a pyroelectric infrared detection element with a condenser lens that is easy to manufacture and has high sensitivity.

MEANS FOR SOLVING THE PROBLEMS The present invention makes a groove for taking out the first electrode lead wire (infrared incident surface) of the pyroelectric element on the attachment surface of the immersion lens of the immersion lens, and utilizes the groove. The lead wire is taken out.

Operation The present invention minimizes the gap between the immersion lens and the pyroelectric element by utilizing the groove provided in the immersion lens for taking out the lead wire of the first electrode of the pyroelectric element,
In addition, by placing them in parallel with each other with good parallelism, it is possible for the pyroelectric element to absorb the condensed infrared rays as efficiently as possible.

EXAMPLE FIG. 1 shows the structure of a pyroelectric infrared detection element with a condenser lens in an example of the present invention. In FIG. 1, 7 is an immersion lens, 10 is a pyroelectric element, 9 is a first electrode (ground electrode), 12 is a second electrode (signal extraction electrode), 13
Is an AI pad for taking out a lead wire, and 8 and 11 are lead wires.

In the above configuration, the infrared condenser lens has a specific resistance of 1
A hemispherical germanium lens having a diameter of 0 Ω-cm, a diameter of 3 mm and a radius of curvature of 1.5 mm was used. Hemispherical germanium lens 7
A zinc sulfide film having a thickness of 0.15 μm was formed by vapor deposition on the infrared incident side curved surface of (1), and an antireflection film having a central wavelength of 10 μm was used to minimize the loss due to reflection. The hemispherical germanium lens 7 has a flat surface with a depth of 50 μm and a width of 10
A groove 14 of 0 μm was formed. The position of the groove 14 is extended with the first electrode 9 of the pyroelectric element having electrical continuity.
It is located at a position corresponding to the bonding pad 13 of the vapor deposition film. The pyroelectric element 10 has a thickness of 10 μm and a side of 1 m.
The first electrode 9 serving as an infrared absorption electrode is provided in the central portion of one surface by using a fine thin piece of lead titanate ceramic that is polished and molded into an m-square.
As Nichrome with a sheet resistance of 400 Ωcm ^□ by vapor deposition, and the first surface is formed in the center of the other surface.
The second as a signal extraction electrode so as to face the electrode 9
The electrode 12 was formed by aluminum vapor deposition to have a thickness of 1 μm. An aluminum pad 13 for taking out the lead wire 8 by bonding was vapor-deposited on a part of the first electrode 9 of the pyroelectric element 9. After the lead wires 8 and 11 are taken out by bonding a gold wire of φ30 μm to both electrodes 9 and 12 of the pyroelectric element 10, they are aligned with the groove 14 at the bottom of the immersion lens, and an adhesive (epoxy resin-Epotek H54) is used. The four corners of the pyroelectric element 10 were adhesively fixed.

When the voltage sensitivity of the infrared detection element with an immersion lens manufactured as described above was measured, an output voltage about 9 times higher than the voltage sensitivity when the element with the same shape was not combined with the immersion lens 7. Was obtained. Further, the pyroelectric element 10 is adhered and fixed to the bottom surface of the immersion lens 7 without grooving, and the voltage sensitivity is improved in a state where the lead take-out portion from the first electrode 9 is inclined to the one side by the thickness of the gold wire diameter of 30 μm. When measured, it is 15% compared to the case of the above groove cutting
The decrease in voltage sensitivity was observed.

As described above, according to the present invention, when the pyroelectric infrared detection element is coupled with the condenser lens, the lead is taken out from the infrared absorption electrode (first electrode) and the bottom surface of the condenser lens is grooved. By eliminating the inclination of the pyroelectric element due to the thickness of the lead wire and fixing the bottom surface of the condenser lens and the pyroelectric element with good parallelism, defocusing is eliminated and a pyroelectric infrared detector with high sensitivity is provided. It can be provided.

[Brief description of drawings]

1 (a) and 1 (b) are a side view and a bottom view showing the structure of a pyroelectric infrared detecting element with a condenser lens according to the present invention, and FIG. 2 is a structure of a conventional thermistor with an infrared condenser lens. It is a side view and a bottom view showing. 7 ... Infrared focusing lens, 8, 11 ... Lead wire, 9 ...
First electrode, 10 ... Pyroelectric infrared detection element, 12 ... Second
Electrode, 13 ... Al pad.

Claims (1)

[Claims] 1. A pyroelectric element in which a cut groove is formed on a flat surface of a hemispherical infrared condensing lens and electrodes are formed on both surfaces of the lens is adhered to the flat surface to remove the electrode from one electrode of the pyroelectric element. An infrared detecting element, characterized in that a lead wire is inserted into the groove and taken out.