JPH11248530A - Infrared image sensing element and infrared sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an infrared image sensing element in which temperature control is unnecessary. SOLUTION: An infrared image sensing element using a metal bolometer 7 consists of two struts 8 which are fixed on a substrate 9 and made of the same material as the metal bolometer 7, the metal bolometer 7 retained in the air at two points by the struts 8, and a resistor 10 which is made of the same material as the metal bolometer 7 and is buried in the substrate 9. The quotient or resistance values or the metal bolometer 7 and the resistor 10 is outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an infrared imaging device for detecting infrared rays and an infrared sensor.

[0002]

2. Description of the Related Art FIG. 5 is a view showing a configuration of a conventional infrared imaging device using a semiconductor bolometer, 1 is a semiconductor bolometer, 2 is a conductor support for supporting the semiconductor bolometer 1 at two points in the air, and 3 is a support 2 A substrate which fixes the ends not connected to the semiconductor bolometer 2 respectively, 4 is a resistor connected in series with the semiconductor bolometer, 5 is a thermometer for measuring the temperature of the substrate 3, and 6 is a regulator for adjusting the temperature of the substrate 3. It is a Peltier device.

FIG. 6 is a schematic diagram of a driving circuit for driving a conventional infrared imaging device. The resistance of the semiconductor bolometer 1 is Rf, the resistance of the resistor 4 is Rs, the bias voltage is V, and the output voltage is Vout. When the semiconductor bolometer 1 receives infrared radiation, the temperature changes, and accordingly, the resistance value Rf also changes. The change in Rf is Vout = Rf × V / (Rf +
Rs). Assuming that Rs is constant, the change in Vout is the semiconductor bolometer 1
Is a monovalent function for the infrared radiation received by
By monitoring out, the amount of infrared radiation can be detected. It is assumed that Rs is constant. This is because the temperature change of the substrate is constantly monitored by the thermometer 5, the temperature is compared with the voltage Vt corresponding to the reference temperature, and the difference is fed back to the Peltier element 6, so that a certain error can be obtained. It is realized by holding it within the range.

[0004]

In the conventional infrared imaging device, an electronic cooler such as a Peltier device is used to keep the temperature of the substrate 3 constant. However, these electronic coolings generally consume a very large amount of power. Therefore, long-term operation with a battery or the like outdoors is impossible.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and an object of the present invention is to provide an infrared imaging device and an infrared sensor which can be used for a long time outdoors or the like without requiring temperature control of the substrate. And

[0006]

According to the first aspect of the present invention, there is provided an infrared imaging device which uses a metal bolometer at a portion receiving infrared radiation and uses two columns made of the same metal as the metal bolometer to form the metal bolometer. Support in the air with point support.
By outputting the quotient of the resistance value of the metal bolometer at this time and the same metal as the metal bolometer and the resistance value of the resistor embedded in the substrate, an infrared imaging device that does not require temperature control is obtained. Things.

According to a second aspect of the present invention, there is provided an infrared imaging device according to the first aspect, wherein the metal bolometer and the resistor are used as a feedback resistor and an input resistor of an operational amplifier to constitute an inverting amplifier. By extracting the ratio in the form of a voltage, an infrared imaging device that does not require temperature control is realized.

The infrared imaging device according to a third aspect of the present invention is the infrared imaging device according to the first aspect, wherein the metal bolometer and the resistor are simultaneously formed by a thin film forming technique to form an inherent difference between the physical properties of the metal bolometer and the resistor. By suppressing. An object of the present invention is to improve the accuracy of infrared imaging and obtain an infrared imaging device that does not require temperature control.

According to a fourth aspect of the present invention, there is provided an infrared sensor for obtaining an infrared image by arranging a plurality of one-dimensional or two-dimensional infrared imaging devices according to the first invention.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a view showing a first embodiment of the present invention, in which 7 is a metal bolometer, and 8 is a metal bolometer.
Are two columns made of the same material as the metal bolometer that supports the metal bolometer 7 in a hollow state, 9 is a substrate for fixing one end of the column 8, and 10 is an electrical contact with the metal bolometer and embedded in the substrate 9. This is a resistor made of the same material as the metal bolometer.

When the metal bolometer 7 receives infrared radiation, its temperature changes, and accordingly, the resistance value Rf changes. Due to the nature of metals, the temperature dependence of resistance is Rf = Rf
It is represented by oxexp (kf · T). Here, Rfo is a constant determined by the shape of the bolometer. Further, kf is a temperature resistance coefficient, and in the case of metal, it is constant depending on the type. The same can be said for the resistance value Rs of the resistor 10,
s = Rso × exp (ks · T). Ideally, kf and ks are the same.

When the temperature of the metal bolometer 7 is T1, the breakdown is the sum of the temperature rise ΔT caused by receiving the infrared radiation and the substrate temperature T2 (T1 = ΔT + T).
2). Therefore, the resistance value at this time is Rf = Rfo × e
xp (kf (ΔT + T2)). At this time, the temperature T2 of the substrate 9 is not a constant value due to an influence of a peripheral temperature change or the like. At this time, the resistance value Rs of the resistor 10 is Rso × exp.
(Ks · T2). Therefore, the quotient of the resistance values of the metal bolometer 7 and the resistor 10 is Rf / Rs = (Rfo / Rs
o) × exp (kf (ΔT + T2) −ks · T2)). Since the same metal is used, in principle, kf
= Ks, the above equation gives Rf / Rs = (Rfo / R
so) × exp (kf · ΔT), which is a formula that does not depend on the temperature change T2 of the substrate.

Further, even if the same metal is selected for the metal bolometer 7 and the resistor 10 in a practical case, δk = kf−ks
And therefore Rf / Rs = (Rfo / Rso)
× exp (kf · ΔT) × exp (δk · T2). To cope with this, by simultaneously forming the metal bolometer 7 and the resistor 10 by a thin film manufacturing process, the physical properties are made uniform, δk ≒ 0 is realized, and a countermeasure is made so as not to cause a substantial error.

As described above, by monitoring Rf / Rs, only the influence of infrared radiation can be taken out purely without performing temperature control, so that an infrared imaging device that does not require substrate temperature control can be obtained.

Embodiment 2 FIG. 2 is a diagram showing a second embodiment of the present invention. In the drawing, Rf and Rs denote metal bolometer 7 and resistor 10 by symbols, respectively.
Reference numeral 1 denotes an operational amplifier (operational amplifier). Note that a power supply, a bypass capacitor, and the like necessary for driving the operational amplifier 11 are omitted.

A bias voltage Vin (constant value) is input to an operational amplifier 11. The operational amplifier 11 forms an inverting amplifier with Rf and Rs, and the operational amplifier output Vou
t is Vout = −Rf / Rs × Vin = − (Rfo ·
Vin / Rso) × exp (kf · ΔT). With the above circuit, the amount of infrared radiation from the bolometer can be extracted in principle in the form of a voltage.

Further, even if the same metal is selected for the metal bolometer 7 and the resistor 10 in a practical case, δk = kf−ks
≠ 0, and therefore Vout = − (Rfo · Vin
/ Rso) × exp (kf · ΔT) × exp (δk · T
2). To cope with this, by simultaneously forming the metal bolometer 7 and the resistor 10 by a thin film manufacturing process, the physical properties are made uniform, δk ≒ 0 is realized, and a countermeasure is made so as not to cause a substantial error.

As described above, by monitoring Vout, only the influence of infrared radiation can be taken out purely without performing temperature control, so that an infrared imaging device that does not require substrate temperature control can be obtained.

Embodiment 3 FIG. 3 is a view showing a third embodiment of the present invention, in which 12 is an infrared imaging element unit of the first or second embodiment, and 13 is an infrared sensor in which the infrared imaging element 12 is arranged on a two-dimensional plane. FIG. 4 shows a mode of operation of the infrared sensor 13, reference numeral 14 denotes an infrared lens for forming an infrared image on the infrared sensor 13, and reference numeral 15 denotes a drive circuit for driving the infrared sensor 13.

An infrared image from the outside is transmitted through an infrared lens 1
By 4, an image is formed on the infrared sensor 13, and the temperature of each infrared imaging element 12 is increased. The drive circuit 15 applies Vin to each infrared imaging element unit 12 on the infrared sensor 13 in the determined order, and sequentially measures Vout at that time.

As described above, in a state where the temperature control is not performed,
Infrared images can be obtained. In this example, the infrared imaging element alone is arranged two-dimensionally, but this may be one-dimensional.

[0022]

According to the first aspect of the present invention, it is possible to obtain an infrared imaging device which does not depend on a change in the temperature of the substrate in principle, and to realize a constant power consumption of the infrared imaging device.

According to the second aspect of the present invention, it is possible to obtain an infrared imaging device which does not depend on a change in the temperature of the substrate in principle, thereby realizing constant power consumption of the infrared imaging device.

According to the third aspect, an infrared image which is independent of a change in the temperature of the substrate can be obtained, and constant power consumption of the infrared imaging device can be realized.

According to the fourth aspect, an infrared image can be obtained by arranging a plurality of one-dimensional or two-dimensional infrared imaging devices according to the first aspect of the invention.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a first embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a second embodiment of the present invention.

FIG. 3 is a diagram showing a configuration of a third embodiment of the present invention.

FIG. 4 is a diagram illustrating a mode of operation according to a third embodiment of the present invention.

FIG. 5 is a diagram illustrating a configuration of a conventional infrared imaging device.

FIG. 6 is a diagram illustrating a driving method of a conventional infrared imaging element.

[Explanation of symbols]

1 semiconductor bolometer, 2 conductor support, 3 substrate, 4
Resistor, 5 thermometer, 6 Peltier element, 7 metal bolometer, 8 2 columns, 9 substrate, 10 resistor, 1
1 operational amplifier, 12 infrared imaging element alone, 13 infrared sensor, 14 infrared lens, 15 drive circuit.

Claims (4)

[Claims] 1. An infrared imaging device for detecting infrared rays, a metal bolometer for detecting infrared rays, two columns of the same material as the metal bolometer for supporting the metal bolometer in the air at two points, and the two bolometers. Substrates for fixing the ends of the columns not in contact with the metal bolometer, respectively;
A resistor made of the same material as the metal bolometer embedded in the substrate and electrically connected to one of the two pillars at a fixed point of the substrate, and a resistance value of the metal bolometer and the resistance A read-out circuit for outputting a quotient of a resistance value of a body; 2. The infrared imaging device according to claim 1, wherein the readout circuit is configured by connecting the metal bolometer and the resistor to a feedback resistor and an input resistor of an operational amplifier, respectively. 3. The infrared imaging device according to claim 1, wherein the metal bolometer, the two columns, and the resistor are formed simultaneously by a thin film forming technique. 4. An infrared sensor having a function of measuring an infrared image by arranging a plurality of the infrared imaging elements according to claim 1 in one or two dimensions.