JPH03274971A - Infrared ray image pickup device - Google Patents

Abstract

PURPOSE:To pick up dose of an infrared ray radiating from the surface of an object accurately by subtracting a sun-ray detection signal from an infrared ray detection signal at a subtractor circuit so as to eliminate the effect of the infrared ray in the sun-ray reflected in the surface of the object onto the pickup. CONSTITUTION:The quantity of an infrared ray radiating from the surface of an object 1 is detected by an infrared ray image pickup element 3 and the result is outputted as an infrared ray detection signal. A infrared ray image pickup element drive circuit 4 outputs the infrared ray detection signal for each minute picture element of a 2-dimension picture whose image is formed on the pickup element 3 sequentially. The infrared ray detection signal from the element 3 is outputted to a subtractor circuit 11 via an infrared ray detection signal amplifier circuit 5. On the other hand, a reflected sun-ray coming from the surface of the object 1 is formed on a sun-ray image pickup element 8 by a spectroscope 7 and a sun-ray detection signal is outputted. A sun-ray image pickup element drive circuit 9 outputs the sun-ray detection signal for each minute picture element on the pickup element 3 sequentially to the subtractor circuit 11, which subtracts the sun-ray detection signal from the infrared ray detection signal and the result is outputted from an output circuit 6.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an infrared imaging device that detects infrared rays emitted from a subject and images the detected infrared rays.

[Conventional technology]

FIG. 3 is a diagram showing a conventional infrared imaging device of this type. In Figure 3, (1) is the subject, (2) is the optical system that images the infrared rays emitted from the surface of the subject (1) on the imaging surface, and (3) is the image formed by the optical system (2). An infrared imaging element that converts the amount of infrared light received by the subject f1+ into an electrical signal and outputs it as an infrared detection signal.

(4) is a drive circuit for driving the infrared imaging device (3).

(5) is an amplifier circuit that amplifies the infrared detection signal output by the infrared imaging device (3), and (6) is an output circuit that outputs the infrared detection signal amplified by the amplifier circuit (5) to the outside.

Next, the operation will be explained.

In a conventional infrared imaging device, first, the infrared rays emitted from the surface of the subject fl) are imaged on the imaging surface by the optical system (2), and the amount of infrared light received by the nine-dimensionally imaged subject +11 is transferred to the infrared imaging element (3). ) is converted into an electrical signal and output as an infrared detection signal. The drive circuit (4) is a circuit that regards the two-dimensional image formed on the infrared imaging device (3) as a collection of minute pixels and outputs infrared detection signals for each minute pixel in a predetermined order. Infrared imaging device (
The infrared detection signal outputted by 3) is amplified by an amplifier circuit (5) and further output to the outside by an output circuit (6). Usually, the output of the output circuit (6) is used by being connected to a display device such as a TV monitor. Conventionally, infrared imaging devices that use image pickup tubes and devices that scan and detect single elements or one-dimensional arrays have been put into practical use, but in recent years, solid-state imaging devices with two-dimensional arrays have been put into practical use. The ones used are also beginning to be put into practical use. A drive circuit for outputting infrared detection signals for each minute pixel in a predetermined order can be constructed purely electronically if the infrared imaging device is a tube or a two-dimensional array element, but it can be constructed purely electronically. In the case of elements or one-dimensional array elements, part or all of the scanning function is often performed mechanically.

[Problem to be solved by the invention]

The infrared imaging device configured as described above has the following secondary problems. That is, when capturing an image of an outdoor scene on a clear day, there is a problem in that the amount of infrared rays emitted from the surface of the subject cannot be accurately captured due to the influence of reflected sunlight. Particularly in the near-infrared region, which is close to the visible region, the amount of infrared rays contained in sunlight enters, but on the other hand, the amount of infrared rays emitted by the subject is small, so the amount of infrared rays contained in sunlight reflected from the surface of the subject is small. However, the amount of infrared rays emitted by the subject is much larger, which poses a big problem if you want to capture only the amount of infrared rays emitted by the subject.

This invention was made to solve the above problems, and provides an infrared imaging device that can remove the influence of reflected infrared light contained in sunlight and accurately capture the amount of infrared rays emitted from the surface of an object. It is intended to provide.

[Means to solve the problem]

The infrared imaging device according to the present invention includes a sunlight imaging device that detects the amount of sunlight reflected on the surface of a subject, and a sunlight imaging device for the purpose of removing the influence of infrared rays contained in sunlight reflected on the surface of the subject. An amplifier circuit that amplifies the sunlight detection signal output by the element.

and a subtraction circuit for subtracting the sunlight detection signal from the infrared detection signal.

[Effect]

In this invention, the subtraction circuit subtracts the sunlight detection signal from the infrared detection signal to remove the influence of infrared rays contained in sunlight reflected on the surface of the subject. It is possible to accurately image the amount of infrared radiation emitted from the surface.

〔Example〕

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

(1) is the subject, (2) is an optical system that images the infrared rays emitted from the surface of the subject (1) on the imaging surface, and (3) is the subject (11 infrared rays) imaged by the optical system (2). An infrared image sensor that converts the amount of received light into an electrical signal and outputs it as an infrared detection signal, (4) an infrared image sensor drive circuit for driving the infrared image sensor (3), and (5) an infrared image sensor that drives the infrared image sensor (3). An infrared detection signal amplification circuit (7) for amplifying the output infrared detection signal is provided in the middle of the optical path created by the optical system (2), and is used to amplify part or all of the sunlight reflected from the surface of the subject (1). A spectrometer (8) forms an image on another imaging surface, and a solar imaging device (8) converts the amount of sunlight received by the subject (1) imaged by the spectrometer (7) into an electrical signal and outputs it as a sunlight detection signal. (9) is a solar image sensor driving circuit for driving the solar image sensor (8);
α・ is a sunlight detection signal amplification circuit that amplifies the sunlight detection signal output by the sunlight image sensor (8).

aD is a subtraction circuit that subtracts the sunlight detection signal amplified by the sunlight detection signal amplification circuit a1 from the infrared detection signal amplified by the infrared detection signal amplification circuit (5);
6) is an output circuit that outputs the subtraction result signal of the subtraction circuit αυ to the outside. (1) to (6) are almost the same as the conventional device.

The operation will be explained.

First, the infrared rays emitted from the surface of the object (1) are imaged on the imaging surface by the optical system (2). It is converted into a signal and output as an infrared detection signal. The infrared image sensor driving circuit (4) is an infrared image sensor (
3) A circuit that regards the two-dimensional image formed above as a collection of minute pixels and outputs infrared detection signals for each minute pixel in a predetermined order.

The infrared detection signal output from the infrared imaging device (3) is amplified by the infrared detection signal amplification circuit (5) and input to the subtraction circuit α. On the other hand, part or all of the sunlight reflected from the surface of the subject Tl) by the spectrometer (7) provided in the middle of the optical path created by the optical system (2).

The image is formed on the sunlight image sensor (8), and the image is formed on the sunlight image sensor (8).
8) converts the amount of sunlight received by the imaged subject (1) into an electrical signal and outputs it as a sunlight detection signal. Like the infrared image sensor drive circuit (4), the sunlight image sensor drive circuit (9) regards the two-dimensional image formed on the sunlight image sensor (8) as a collection of minute pixels, and separates each minute pixel. This is a circuit for outputting sunlight detection signals in a predetermined order. The sunlight detection signal output by the sunlight image sensor (8) is amplified by the sunlight detection signal amplification circuit α, and the sunlight detection signal is amplified by the sunlight detection signal amplification circuit α.
is input. The infrared detection signal is subtracted from the sunlight detection signal by a subtraction circuit (fil), and further output by an output circuit (6).
is output to the outside by Infrared detection signal amplification circuit (
5) and the amplification factor of the sunlight detection signal amplification circuit Ql are adjusted to be optimal according to the sensitivity of each image sensor and the intensity of infrared rays and sunlight in the wavelength range detected by each image sensor. . In this embodiment, the optical system (2) is configured to have a wavelength band of 2 to 5 μm as a passband, the infrared imaging device (3) is configured to have a wavelength band of 3 to 5 μm, and the sunlight imaging device (8) is configured to have a wavelength band of 3 to 5 μm. It was configured to detect a wavelength band of 2 to 3 μm. In this case, the wavelength band of harmful infrared rays contained in sunlight reflected on the surface of the subject is 3 to 5 μm, but the wavelength of the sunlight component with a wavelength of 2 to 3 μm, which is an adjacent wavelength band, is 3 to 5 μm in wavelength. There is almost no practical problem even if it is assumed that the amount is the same as the sunlight component. Therefore, depending on the subtraction circuit αυ, 2~3μ
By subtracting the sunlight component signal with a wavelength of m from the infrared detection signal with a wavelength band of 3 to 5 μm, it becomes possible to accurately image the amount of infrared rays emitted from the surface of the subject. By the way, in principle, the wavelength band of 2 to 3 μm also includes infrared components emitted from the surface of the subject, so when the sunlight component of the wavelength of 2 to 3 μm is subtracted using the subtraction circuit (υ), There is a concern that the infrared component emitted from the surface of the subject will also be subtracted, but generally speaking, the shorter the wavelength, the larger the component of sunlight, and the smaller the infrared component emitted from the surface of the subject, so it is not practical. There is almost no problem.The detection wavelength band of the solar image sensor (8) is not 2 to 3 μm.

It goes without saying that by using a wavelength band on the shorter wavelength side, it becomes possible to more accurately image the amount of infrared rays emitted from the surface of the object. It is also possible to add a function to bypass the subtraction circuit αυ at night or on cloudy days; however, even in this case, the gist of the invention is not impaired in the slightest.

Now, FIG. 2 is a diagram showing another embodiment of the present invention.

In the figure, (1) is the subject, (2) is the optical system that images the infrared rays emitted from the surface of the subject (1) on the imaging surface, and (3) is the subject ( 1
(4) is a composite infrared image sensor that converts the amount of infrared light received by 1 and the amount of sunlight received reflected from the surface of the subject fil into electrical signals and outputs it as an infrared detection signal and a sunlight detection signal; ); (5) is an infrared detection signal amplification circuit that amplifies the infrared detection signal output by the composite infrared imaging device (3);
The α value is the sunlight detection signal amplification circuit that amplifies the sunlight detection signal output by the composite infrared image sensor (3), and αυ is the sunlight detection signal amplification from the infrared detection signal amplified by the infrared detection signal amplification circuit (5). A subtraction circuit that subtracts the sunlight detection signal amplified by the circuit αl, and (6) an output circuit that outputs the subtraction result signal of the subtraction circuit υ to the outside. Items (1) to (6) are substantially the same as the conventional device and the embodiment shown in FIG.

Next, the operation will be explained.

This embodiment differs from the embodiment shown in FIG.

The infrared imaging element is configured so that the amount of infrared light received and the amount of sunlight received can be output from the same element as an infrared detection signal and a sunlight detection signal.

In this example, an element array that detects infrared rays in a wavelength band of 3 to 5 μm and an element array that detects infrared rays in a wavelength band of 2 to 3 μm are arranged alternately on a two-dimensional solid-state image sensor, and the former The detection signal was configured to output a sunlight detection signal from the latter. By making it possible to detect infrared rays in two different wavelength bands with the same imaging device.

Not only can the drive circuit of the image sensor be used also, but the optical system can be simplified, and the effort of adjusting the optical axis can be saved.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to provide an infrared imaging device that can remove the influence of reflected infrared light contained in sunlight and accurately image the amount of infrared rays emitted from the surface of a subject. .

[Brief explanation of drawings]

FIG. 1 is a block diagram of an infrared imaging device showing one embodiment of the present invention, FIG. 2 is a diagram showing another embodiment of the invention, and FIG. 3 is a diagram showing a conventional infrared imaging device. In the figure, (1) is the subject, (2) is the optical system, and (3)
is an infrared image sensor, (4) is an infrared image sensor drive circuit,
(5) is an infrared detection signal amplification circuit, (6) is an output circuit,
(7) is a spectrometer, (8) is a sunlight imaging device, (9) is a sunlight imaging device drive circuit, α[ is a sunlight detection signal amplification circuit, and αυ is a subtraction circuit. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (2)

[Claims] (1) An optical system that images infrared rays emitted from the surface of a subject onto an imaging surface, and an infrared ray that converts the amount of infrared light received from the surface of the subject imaged by the optical system into an electrical signal. an infrared imaging device that outputs a detection signal; an infrared imaging device drive circuit that drives the infrared imaging device; an infrared detection signal amplification circuit that amplifies the infrared detection signal that the infrared imaging device outputs; and the optical system. a spectroscope that is installed in the middle of the optical path created by the subject and focuses part or all of the sunlight reflected from the surface of the subject onto another imaging plane; A sunlight imaging device that converts the amount of sunlight received into an electrical signal and outputs it as a sunlight detection signal, a sunlight imaging device drive circuit for driving the sunlight imaging device, and an electrical signal that the sunlight imaging device outputs. a sunlight detection signal amplification circuit that amplifies the sunlight detection signal; and a sunlight detection signal that is amplified by the sunlight detection signal amplification circuit from the infrared detection signal amplified by the infrared detection signal amplification circuit. An infrared imaging device comprising: a subtraction circuit that subtracts a signal; and an output circuit that outputs a subtraction result signal of the subtraction circuit to the outside. (2) an optical system that images infrared rays emitted from the surface of a subject and sunlight reflected from the surface of the subject on an imaging surface; converts the amount of infrared light received into an electrical signal,
A composite infrared imaging device that outputs an infrared detection signal and also converts the amount of sunlight received reflected from the surface of the subject into an electrical signal and outputs it as a sunlight detection signal, and a drive circuit for driving the composite infrared imaging device. an infrared detection signal amplification circuit that amplifies the infrared detection signal outputted by the composite infrared imaging device; a sunlight detection signal amplification circuit that amplifies the sunlight detection signal outputted by the composite infrared imaging device; a subtraction circuit that subtracts the sunlight detection signal amplified by the sunlight detection signal amplification circuit from the infrared detection signal amplified by the detection signal amplification circuit; and a subtraction circuit that outputs a subtraction result signal of the subtraction circuit to the outside. An infrared imaging device comprising an output circuit for outputting.