JPH0694533A - Thermal image detector - Google Patents

Abstract

PURPOSE:To obtain a compact and simple-structured/constituted system for detecting a two-dimensional thermal image without contact using an infrared sensor comprising pyroelectric type film heat detecting elements. CONSTITUTION:By placing an infrared ray transmitting type protection cover 6 in front of movable parts such as an infrared ray sensor 1, an infrared ray transmitting lens 2 and a chopper 3, reliability and safety of the system is improved. Influence of the protection cover is corrected by temperatures detected at a cover temperature detecting part 7 and a reference temperature detecting part 4 to allow accurate temperature measurement.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to radiation temperature detection and human body behavior detection by a thermal image such as temperature distribution in a living room at home and human body behavior detection.

[0002]

2. Description of the Related Art Conventionally, there have been a quantum infrared sensor and a thermal infrared sensor as methods for non-contact temperature measurement. The quantum infrared sensor has high sensitivity and quick response, but requires cooling, and is not suitable for consumer use. On the other hand, the thermal infrared sensor has a relatively low sensitivity and a low response speed, but since it does not require cooling, it has been put to practical use in the consumer market.

Among thermal infrared sensors, a pyroelectric infrared sensor utilizing the pyroelectric effect is often used. The pyroelectric infrared sensor has a differential change output characteristic and generates an output only when the incident temperature changes. For example, when a human body passes in front of the pyroelectric infrared sensor, the radiation temperature of the human body is input to the pyroelectric infrared sensor as a time input of appearance, disappearance, appearance, disappearance, .... Therefore, the pyroelectric infrared sensor is output in synchronization with this time change. There is also a point temperature sensor that uses a ceramic pyroelectric infrared sensor and a chopper, but this also has low sensitivity and very slow response speed, so it detects dozens of temperature data in 1 to 2 seconds. I couldn't.

Further, as a means for obtaining a two-dimensional thermal image, a method of arranging a pyroelectric infrared sensor in two dimensions has been considered.

[0005]

If the pyroelectric infrared sensor is arranged two-dimensionally, the system becomes complicated.

Further, in the case of constructing a system by a method of scanning the pyroelectric type heat detecting element group arranged on a straight line, if the optical system is outside the heat detecting element group, the optical system covers the entire scanning range. Since it has to be large, it must be large, and even if it covers the entire scanning range, there is a problem that the sensitivity of the entire field of view is not uniform due to the deviation of the optical axis.

Further, when the pyroelectric infrared sensor, the infrared transmissive lens and the like are directly exposed to the outside, the reliability is deteriorated due to the adhesion of dust and the like, and the safety problem due to the moving parts being exposed is There was a cosmetic problem.

Further, when an infrared transmission type protective cover is attached in front of the pyroelectric infrared sensor and the infrared transmission type lens, the infrared rays emitted from the object are partially absorbed by the infrared transmission type cover. Then, a part of the infrared rays due to the temperature of the infrared transmissive cover enters the pyroelectric infrared sensor, and the detected thermal image is out of the actual thermal image.

The present invention provides a thermal image detecting device having a higher precision and reliability, which is a system having a small size and a relatively simple structure and structure using an infrared sensor composed of a pyroelectric heat detecting element group. It is a thing.

[0010]

In order to solve the above problems, the present invention provides a pyroelectric heat detecting element group arranged on a linear axis and an infrared ray integrated with the pyroelectric heat detecting element group. A movable part constituted by a transmission lens, a chopper for opening and closing a path of infrared rays incident on the pyroelectric heat detection element group through the infrared transmission lens, and a reference temperature detection means for detecting the temperature of the chopper, and Rotating means for rotating the pyroelectric thin film heat detecting element group about the rotation axis having a rotation axis in which the movable section is parallel to the linear axis or inclined by a constant angle, and in front of the movable section. A two-dimensional two-dimensional structure is provided by driving and controlling the arranged infrared transmission type protective cover, the chopper and the rotating means, and inputting the output signal of the pyroelectric heat detecting element group and the detection signal from the reference temperature detecting means. Calculate to thermal image signal It has an arithmetic control unit for management for and to obtain a two-dimensional thermal image signal.

Further, according to the present invention, the arithmetic control section is provided with a correcting means for performing arithmetic correction using the contribution rate of infrared rays incident on the pyroelectric heat detecting element group by the protective cover.

According to the present invention, the infrared transparent protective cover arranged in front of the movable portion is provided with a cover temperature detecting portion for detecting the temperature of the protective cover, and an output signal of the pyroelectric thermal detecting element group is provided. Further, it has a calculation control unit for inputting the detection signals from the two temperature detecting means and performing a calculation process into a two-dimensional thermal image signal, and obtains a two-dimensional thermal image signal.

Further, according to the present invention, a thermistor is used as the cover temperature detecting section.

According to the present invention, the reference temperature detecting means is also a thermistor, and the resistance value and the B constant are substantially the same as those of the cover temperature detecting section.

Further, according to the present invention, the contribution rate of infrared rays incident on the pyroelectric heat detecting element group by the protective cover, the reference temperature obtained by the reference temperature detecting means, and the protective cover temperature detecting means are obtained. The arithmetic control section is provided with a correcting means for performing arithmetic correction using the protective cover temperature.

[0016]

The present invention provides a two-dimensional thermal image detection system having a small size and a simple structure by rotating a movable part which is integrated with a pyroelectric type heat detection element group arranged on a linear axis and an optical system. To do. Further, by providing a protective cover in front of the movable part, the optical system and the pyroelectric heat detecting element group are not directly exposed to the outside, and the optical system and the pyroelectric heat detecting element group are protected from dust and dust. It will not adhere and the reliability will be improved. Further, since the movable part is not exposed to the outside, safety and appearance are improved. Further, the temperature of the protective cover is detected by the protective cover temperature detection unit, and the calculation correction is performed, whereby a more accurate thermal image is detected.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A two-dimensional thermal image detecting device according to an embodiment of the present invention will be described with reference to FIGS.

In FIG. 1, reference numeral 1 denotes an infrared sensor composed of a pyroelectric heat detecting element group, for example, 1a to 1 in FIG.
As shown by e, five pyroelectric thin film heat detecting elements are arranged on a linear axis and are responsible for dividing the viewing angle into five in the vertical direction. Reference numeral 2 denotes an infrared transmission lens arranged so as to connect a thermal image to each of the pyroelectric thin film heat detecting elements. The infrared ray transmitting lens passes through the center of a plurality of pyroelectric thin film heat detecting elements to transmit infrared light. The lens 2 and the infrared sensor 1 are integrated. Reference numeral 3 is a chopper that uses a shutter that does not transmit light and infrared rays, and 4 is a reference temperature detector that detects the temperature of the chopper 3. Reference numeral 5 is a horizontal drive unit,
It is integrated with the components of ~ 4. Reference numeral 6 is an infrared transparent protective cover arranged so as to cover the components 1 to 5. The protective cover 6 is made of a material which transmits almost no visible light but transmits infrared light so as not to impair the appearance. In the embodiment, polyethylene is used, and a small amount of pigment is mixed in so that the movable part inside the protective cover cannot be seen from the outside. Further, the shape of the protective cover is spherical so that refraction of incident infrared light by the protective cover does not occur. Reference numeral 7 denotes a cover temperature detection unit that detects the temperature of the protective cover 6 described above. Reference numeral 8 denotes a band amplification unit that band-amplifies the minute voltage output from the infrared sensor 1 in accordance with the opening / closing operation of the chop 3, and is provided corresponding to each pyroelectric thin film heat detection element. Reference numeral 9 is an arithmetic control for inputting the output from the infrared sensor 1 and the detection signals from the reference temperature detecting unit 4 and the cover temperature detecting unit 7 which are band-amplified by the band amplifying unit 8 and arithmetically processing the two-dimensional thermal image signal It is a department.

A mechanism for obtaining a two-dimensional thermal image from the pyroelectric thin film thermal detection elements arranged in a line in the vertical direction as shown in FIG. 2 will be described with reference to FIG. 3A shows the stereoscopic viewing angle of the thermal image to be detected, and FIG. 3B shows the detected thermal image. The infrared sensor 1 including a pyroelectric heat detecting element group has a narrow viewing angle in the horizontal direction, and the horizontal driving unit 5 rotates to sequentially move the horizontal viewing angle. Further, the two-dimensional thermal image shown in FIG. 3B is obtained by continuously repeating the opening and closing of the shutter in the chopper 3 so that the infrared sensor 1 sequentially measures the temperature in the vertical direction in synchronization with the rotation in the horizontal direction. can get.

In FIG. 1, the reference temperature detecting section 4 and the cover temperature detecting section 7 both use a thermistor as the temperature detecting means, and the same resistance value and B constant are used, so that the calculation control section takes in them. Temperature conversion is simplified.

The process of obtaining temperature data in the arithmetic control unit 9 will be described with reference to the flowchart of FIG. In step 401, the output signal V of the pyroelectric thin film heat detection element group that has been band-amplified by the band amplification unit 8, the detected value Vc obtained by the reference temperature detection unit 4, and the cover temperature detection unit 7.
The detected value Vp obtained in step A is A / D converted. Next, in step 402, the output signal V of the pyroelectric thin-film thermal detection element group V
Difference temperature data D that is the basis of the difference between the
Calculate T1.

Here, when the temperature of the object is detected by the thermal image detecting device of FIG. 1, the temperature of the protective cover 6 has an influence. If the infrared transmittance of this protective cover 6 is N,
The amount of infrared rays reaching the infrared sensor from the subject is only N, and the temperature of the protective cover 6 is detected for the remaining (1-N). Here, Tp: protective cover temperature Tc: reference temperature Ta: subject temperature DT ': protective power x (Tp-Tc) (1) Therefore, the true differential temperature DT (= Ta-Tc) is transformed from the above equation. Then, it is obtained by the following formula. DT = (Ta−Tc) = DT ′ / N− (Tp−Tc) × (1−N) / N (2) Therefore, the gain of the band amplification unit is set to compensate the transmittance of the protective cover (1 / DT) times, (DT '/ N) becomes an AD input signal from the infrared sensor, and the true temperature difference DT can be easily obtained by the above equation. In step 403, the true temperature difference DT is calculated using the equation (2) from the temperature difference data DT1 obtained in step 402, the protective cover temperature Tp, and the reference temperature Tc. Next, in step 404, the reference temperature Tc
The subject temperature is obtained by adding to.

[0023]

As is apparent from the above description, the present invention has the following advantages.
By rotating the one-dimensionally arranged pyroelectric thin film heat detection element group and the optical system as a unit, a thermal image can be detected with a small and simple configuration.

Further, by covering a movable part including the infrared sensor and the optical system with a protective cover, it is possible to prevent deterioration of reliability due to adhesion of dust and the like, and to improve safety and appearance.

Further, the protective cover temperature detecting section detects the temperature of the protective cover and corrects the influence of the infrared rays emitted from the protective cover by calculation, whereby a more accurate thermal image can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is a configuration diagram of an infrared sensor according to the same embodiment.

FIG. 3 is an explanatory diagram of a mechanism for obtaining the same thermal image.

FIG. 4 is a flowchart for explaining the operation of the arithmetic control unit in the embodiment.

[Explanation of symbols]

 1 infrared sensor 2 infrared transmission lens 3 chopper 4 reference temperature detection unit 5 horizontal drive unit 6 protective cover 7 cover temperature detection unit 8 band amplification unit 9 arithmetic control unit

Continuation of front page (51) Int.Cl. ⁵ Identification number Internal reference number FI Technical indication location H04N 5/33 (72) Inventor Nakayama Morihiro 1006 Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (6)

[Claims] 1. A pyroelectric thermal detection element group arranged on a linear axis, an infrared transmission lens integrated with the pyroelectric thermal detection element group, and the pyroelectric thermal detection element through the infrared transmission lens. A movable part configured by a chopper that opens and closes a path of infrared rays incident on the detection element group, a reference temperature detection part that detects the temperature of the chopper, and the movable part that is parallel to the linear axis or is inclined at a constant angle. Rotating means for rotating the pyroelectric heat detecting element group around the rotating shaft, an infrared transparent protective cover arranged in front of the movable part, the chopper and rotating means. Of the pyroelectric thermal detection element group and the detection signal from the reference temperature detection means, and inputs the detection signal from the pyroelectric thermal detection element group into a two-dimensional thermal image signal for arithmetic processing. Image detection device. 2. The thermal image according to claim 1, wherein the arithmetic control section is provided with a correcting means for performing arithmetic correction using a contribution rate of infrared rays incident on the pyroelectric heat detecting element group by the protective cover. Detection device. 3. A pyroelectric heat detecting element group arranged on a linear axis, an infrared transmitting lens integrated with the pyroelectric heat detecting element group, and the pyroelectric heat detecting element through the infrared transmitting lens. A movable part configured by a chopper that opens and closes a path of infrared rays incident on the detection element group, a reference temperature detection part that detects the temperature of the chopper, and the movable part that is parallel to the linear axis or is inclined at a constant angle. A rotation means having a rotation axis for rotating the pyroelectric heat detection element group about the rotation axis, an infrared transparent protection cover arranged in front of the movable part, and a temperature of the protection cover. For detecting the temperature of the cover, the chopper and the rotating means, and inputting the output signals of the pyroelectric heat detecting element group and the detection signals from the two temperature detecting means to input two-dimensional heat. Image signal processing That thermal image detecting apparatus constituted by an arithmetic and control unit. 4. The thermal image detecting device according to claim 3, wherein a thermistor is used as the cover temperature detecting portion. 5. The reference temperature detecting means is also a thermistor,
The thermal image detection device according to claim 4, wherein the resistance value and the B constant are substantially the same as those of the cover temperature detection unit. 6. A contribution rate of infrared rays incident on the pyroelectric heat detecting element group by the protective cover, a reference temperature obtained by the reference temperature detecting means, and a protective cover temperature obtained by the protective cover temperature detecting means. 4. The thermal image detecting device according to claim 3, wherein the arithmetic control section is provided with a correcting means for performing arithmetic correction using the.