JPH0363535A - Infrared sensor - Google Patents

Abstract

PURPOSE:To increase the sensitivity of a temperature detecting means and to accurately detect the temperature of a body to be detected and its temperature variation by reflecting and converging infrared rays by the concave surface of a main reflecting mirror which has a light through hole in the center. CONSTITUTION:The infrared rays 16 emitted by the body to be detected pass through an infrared-ray transmission window 9 and reflected and converged by the concave surface of the main reflection mirror L1 which has the light through hole 15 at the center part. The converged infrared rays 16 are reflected and converged by the convex surface of a 2nd reflection mirror L2. The converged infrared rays 16 pass through the light through hole 15 of the main reflection mirror L1 and are photodetected by a heat reception part 14 to raise the temperature of the outer peripheral part from the center part, so that the sensitivity of the temperature detecting means 6 arranged closely at the outer peripheral part of the heat reception part 14 is increased. Consequently, the termperature detecting means 6 accurately detects the temperature of the body to be detected and its temperature variation.

Description

[Detailed Description of the Invention] [Abstract] The infrared sensor of the present invention reflects and condenses infrared rays on the concave surface of a main reflecting mirror having a light passing hole in the center, and directs the condensed infrared rays to the convex surface of a second reflecting mirror. A Cassegrain condensing system consisting of two specular reflection mirrors is used, and the infrared rays reflected and condensed by the convex surface of the second reflection mirror are transmitted to the rear center outer periphery through the light passing hole of the main reflection mirror. The temperature of the object to be detected and the temperature change are detected by receiving the temperature at the provided heat receiving section and detecting the temperature using a temperature sensor located near the heat receiving section.

[Industrial application field]

The present invention relates to an infrared sensor with a Cassegrain focusing system that accurately detects the temperature and temperature changes of an object to be detected.

[Conventional technology]

In a conventional infrared sensor, a Fresnel lens (telescope type) shown in Figure 4 is installed in the front part of a sensor container provided with an infrared transmission window, and the infrared rays 16 that pass through the infrared transmission window are focused on the serrated surface (in the center) of the Fresnel lens. Grooveup type (Grooveup type) which transmits light from the surface of the Fresnel lens and collects light (Gr.

ova down type), and a heat receiving part is provided near the focal point F when the glove up type is used or the focal point F' when the glove down type is used, and the temperature and temperature change of this heat receiving part are calculated as the temperature near the heat receiving part. The temperature of the object to be detected is detected by the detection means.

It is configured to be able to detect temperature changes.

[Problem to be solved by the invention]

In the conventional example above, since a Fresnel lens is used, the material or thickness of the Fresnel lens absorbs infrared rays, and as a result, a specific wavelength of infrared rays is absorbed, and the temperature of the object to be measured and the light received by the heat receiving part are Not only is there a problem that it is difficult to achieve the required performance because there is a risk that the correlation with the dose will deteriorate and the sensitivity of the temperature detection means will decrease, making it impossible to accurately detect the temperature of the object to be detected and temperature changes. Since it is a lens system, it is not possible to select a wide range of viewing angles, making it difficult to obtain various variations.
Another problem is that the lens structure is complicated and expensive.

[Purpose of the invention]

The first object of the present invention is to avoid absorption of infrared rays by using a Cassegrain condensing system consisting of two specular reflection mirrors without using a Fresnel lens, and to prevent a reduction in the amount of infrared rays to the heat receiving part. An object of the present invention is to provide an infrared sensor capable of accurately detecting the temperature of an object to be detected and temperature changes by increasing the temperature of the object and substantially improving the sensitivity of a temperature detecting means.

A second object of the present invention is to use a spherical mirror without paraxial ray aberration correction as the reflecting mirror, and use a temperature detector consisting of a large number of thermocouples integrated in a ring or polygon shape as a hot junction in the heat receiving part. An object of the present invention is to provide an infrared sensor with greatly improved measurement sensitivity.

[Means to achieve the purpose]

In order to achieve the above-mentioned first object, the first infrared sensor of the present invention has an infrared ray 16 that passes through the infrared ray transmitting window 9 on a concave surface of the rear part of the sensor container 12 provided with the infrared ray transmitting window 9 as shown in the first figure. reflects and focuses the light.

A main reflecting mirror having a light passing hole 15 in the center is provided, and a second reflecting mirror L2 that reflects and condenses the infrared rays 16 reflected by the main reflecting mirror Ll on a convex surface is provided at the front center of the sensor container 12. The infrared rays 16 reflected by this second reflecting mirror L2
The heat receiving part 14 receives the heat through the light passing hole 15 of the main reflecting mirror Ll.
is provided at the rear center of the sensor container 12, and a temperature detecting means 6 for detecting the temperature and temperature change of the heat receiving section 14 is provided close to the outer periphery of the heat receiving section 14.

The second infrared sensor of the present invention is the first infrared sensor described above. In order to achieve the second objective, the reflecting mirror in the first infrared sensor is a spherical mirror without paraxial ray aberration correction, and the temperature detector is made of a large number of thermocouples whose hot junctions are integrated in an annular or polygonal shape. The structure is as follows.

[For production]

Infrared rays 16 emitted from an object to be detected in the first infrared sensor are transmitted through an infrared transmitting window 9, reflected and condensed by the concave surface of a main reflecting mirror Ll having a light passing hole 15 in the center. This focused infrared light 16 is reflected and focused by the convex surface of the second reflecting mirror L2. This focused infrared light 16 is reflected by the main reflecting mirror L.
The light passes through the light passing hole 15 of 1 and is received by the heat receiving section 14, and the temperature of the outer circumference is increased from that of the center, and the sensitivity of the temperature detecting means 6 placed close to the outer circumference of the heat receiving section 14 is substantially increased to detect the temperature. By means of the means 6, the temperature and temperature change of the object to be detected can be accurately detected.

In the second infrared sensor, since a reflecting mirror without paraxial ray aberration correction was used, except that it had the same effect as the first infrared sensor, the focal image was ring-shaped, and the focal image was formed on the hot junction of a large number of integrated thermocouples. Because it forms an image, measurement efficiency is high and sensitivity is significantly improved.

C Example] The present invention will be explained in detail below with reference to the drawings.

FIG. 1 is a half-sectional view showing the structure of an embodiment of the infrared sensor of the present invention, and FIG. 2 is a front view of the front frame to which the second reflecting mirror of the present invention is attached.

First, its configuration will be explained.

In FIG. 1, reference numeral 2 denotes a lens barrel, on the front of which a front frame 1 and an infrared transmitting window 9 which also serves as a dust cap are attached, and on the rear thereof a main lens frame 3 and a rear frame 4 are attached. Front frame l, lens barrel 2. The main lens frame 3 and the rear frame 4 constitute a sensor container 12. The center of the front frame 1 is made of aluminum and copper on a base material such as acrylic resin.

A second spherical reflector is attached with gold, silver, etc. to give a reflectance of 80 or more, and the main mirror frame 3 has a light passing hole 15 in the center, and is made of aluminum, acrylic resin, etc. as a base material. copper.

Spherical main reflecting mirror L with gold, silver, etc. attached to it and a reflectance of 80 or more
1 is attached by being pressed from the convex side by a mirror holder 8.

The main reflecting mirror Ll is a spherical mirror that is not corrected for paraxial ray aberration.

The front small-diameter cylindrical portion 4a of the rear frame 4 has a light passing hole 15 in the main reflecting mirror.
It has a hood 5 in front of it, and a large diameter cylindrical part 4c is connected to the front small diameter cylindrical part 4a via a stepped part 4b.

A temperature detecting means 6 is mounted in contact with the stepped portion 4b and the large diameter cylindrical portion 4c of the rear frame 4, and a heat receiving portion 14 is installed inside the temperature detecting means 6 at the sensor seat 7. It is attached with a sensor holder 10. 11 is a fixing screw.

FIG. 3(A) is a cross-sectional view showing an example of a temperature detector comprising a temperature detecting means and a heat receiving section according to the present invention. This temperature sensor 18 is a polymer thin film 1 such as a polyester film.
All black (Au Black) formed by vapor deposition on the back surface of 7
It is composed of the heat receiving section 14 (k) and a thermocouple 6 provided on the other surface.

FIG. 3(B) shows a plan view of the thermocouple side of the temperature detector 18 constructed in this manner. As can be seen from this figure, a large number of thermocouples 6 are integrated so as to surround the heat receiving section 14, and a positive lead 19 and a negative lead 20 are connected to the thermocouple 6.

On the other hand, in the heat receiving part 14, one metal forming the thermocouple is provided as a rectangular heat receiving piece 14a, 25 pieces per side, as shown in the figure, and 100 pieces are provided on all four sides.

FIG. 3(C) is a partially enlarged view showing a corner of the temperature detector 18 constructed in this manner.

Each thermocouple 6 is formed by connecting one metal 23 and another metal 24, the hot junction 21 is arranged in an annular or polygonal shape around the heat receiving piece 14a, and the cold junction 22 is arranged around the heat receiving piece 14a. provided. The thermocouple 6 is, for example, antimony (chemical symbol,
Sb) 23 and bismuth (chemical symbol Bi) 24.

FIG. 3(D) shows a circuit diagram of the thermocouple 6 constructed in this manner. In the figure, antimony (chemical symbol, S
b) 23 and bismuth (chemical symbol: Bi) 24 are joined at junctions 21 and 22 to form a total of 100 pairs in series.

By the way, a thermocouple has a circuit made of two types of metals.
This utilizes the Seebeck effect, in which thermoelectromotive force is generated when the temperatures at two junctions are different, causing current to flow. Therefore, as described above, by connecting the thermocouples 6 in series, the minute potential is amplified.

The thermocouple 6 of this temperature detector 18 measures the temperature of the heat receiving section 14.

It detects temperature changes and thereby detects the temperature of the object to be detected and the temperature changes.

Next, its effect will be explained.

In the first infrared sensor, infrared rays 16 emitted from an object to be detected are transmitted through an infrared transmitting window 9, reflected and condensed by the concave surface of a main reflecting mirror L+ having a light passing hole 15 in the center. This focused infrared ray 16 is reflected and focused by the convex surface of the second reflecting mirror. This focused infrared light 16 is transmitted to the hood 5,
The light passes through the light passing hole 15 of the main reflecting mirror Ll (the small diameter cylindrical part 4a of the rear frame 4) and is received by the heat receiving part 14, and the temperature of the hot junction 21 of the thermocouple arranged in an annular or polygonal shape is increased. An output corresponding to the amount of infrared rays received by 14 is obtained.

Furthermore, when a thermocouple is used as the temperature detector 6, when the thermocouple 6 is brought into contact with the rear frame 4 that constitutes the sensor container 12 made of a thermally conductive member, the hot junction 21 and the cold junction 22 of the thermocouple 6 are connected. This prevents delays in temperature rise during this period, and reduces erroneous measurements.

〔Effect of the invention〕

As described above, according to the present invention, the infrared rays 16 are reflected and focused on the concave surface of the main reflecting mirror L+ having the light passing hole 15 in the center, and the focused infrared rays 16 are reflected on the convex surface of the second reflecting mirror L2. By using a Gussegrain condensing system consisting of two specular reflecting mirrors that reflect and condense light at the
The temperature of the object to be detected and temperature changes can be accurately detected by increasing the temperature of the object to be detected and substantially improving the sensitivity of the temperature detection means 6.

In addition, since a spherical mirror without correction of paraxial ray aberration is used as a reflecting mirror, the focal image is formed into a ring shape, and the image is formed on the hot junction of the thermocouple arranged in an annular or polygonal shape, so the temperature sensing speed is reduced. A fast, highly sensitive, and highly practical infrared sensor can be obtained.

[Brief explanation of drawings]

FIG. 1 is a half-sectional view showing the configuration of an embodiment of the infrared sensor of the present invention, FIG. 2 is a front view of the front frame to which the second reflecting mirror of the present invention is attached, and FIG. 3(A) is the temperature sensor of the present invention. A sectional view showing an example of a temperature detector comprising a detection means and a heat receiving part, FIG. 3(B) is a plan view of the temperature detector in the present invention,
FIG. 3(C) is a partially enlarged view showing a corner of the temperature detector, FIG. 3(D) is a circuit diagram of a thermocouple in the present invention, and FIG. 4 is a collection using a Fresnel lens in a conventional infrared sensor. It is an explanatory diagram of an optical system. 6...Temperature detection means (thermocouple), 9...
・Infrared transmission window (dust cap), Ll...(
Spherical) main reflecting mirror, L2... (spherical) second reflecting mirror, 12... sensor container, 14... heat receiving section, 14a... heat receiving piece , 15... Light passing hole, 16... Infrared rays.

Claims (2)

[Claims] (1) Sensor container (12) equipped with an infrared transmission window (9)
An infrared ray (1
6) is reflected by the concave surface and focused, there is a light passing hole (15) in the center.
) is provided, and this main reflecting mirror L_1
A second reflecting mirror L_2 that reflects and condenses the infrared rays reflected by the second reflecting mirror L_2 on its convex surface is placed in the center of the front part of the sensor container (12), and the infrared rays (16) reflected by this second reflecting mirror L_2 are mainly reflected. A heat receiving part (14) that receives heat through the light passing hole (15) of the mirror L_1 is provided at the rear center of the sensor container (12), and a temperature detector (6) that detects the temperature of this heat receiving part (14) and temperature changes is provided. Infrared sensor installed. (2) The infrared rays according to claim 1, wherein the main reflecting mirror L_1 is a spherical mirror without paraxial ray aberration correction, and the temperature detector is composed of a large number of thermocouples whose hot junctions are integrated in an annular or polygonal shape. sensor.