JPS5915379A - Heat infrared image pickup camera - Google Patents

Abstract

PURPOSE:To obtain a compact and light-weight heat infrared image pickup device which works on the normal temperature with a long lifetime and an easy operation, by combining a row of pyroelectric infrared detecting elements with a one-dimensional scanning mirror. CONSTITUTION:The output of a linear array 41 in which pyroelectric infrared detecting elements are set in a row is supplied to an output system after undergoing a prescribed signal process such as an integrating process, etc. through a signal processing part 48. At the same time, a part of the output of the part 48 is applied to a light emitting diode row 46 to blink the row 46. This blinking light is reflected by the rear side of a scanning mirror 43 which revolves round a rotary shaft to perform the one-dimensional panning scan. Then the reflected light is displayed on a screen 47 in the form of a visible image. The panning scan is performed in a direction rectangular to the arranging direction of the array 41. That is, it is possible to observe the infrared radiation distribution in a viewfield 45 in the form of a visible optical image.

Description

[Detailed Description of the Invention] There are two types of thermal infrared imaging cameras: a vacuum tube type and a type using a solid-state infrared detection element, and the latter has a longer lifespan and is more durable. The latter include: ■ A method in which infrared detection elements mechanically scan the mirror in two-dimensional directions using a point sensor; ■ A method in which multiple infrared detection elements are lined up in a row and the mirror is scanned one-dimensionally in a direction perpendicular to the element row. ■With only two-dimensionally arranged infrared detection elements,
There is a method that does not use a mechanical scanning mirror. On the other hand, solid-state infrared detection elements include a semiconductor type that detects infrared rays as photons and a thermal type that absorbs the infrared rays as heat and converts the temperature change of the element into an electrical signal by some method. The former has high sensitivity and quick response, so it has been developed as a so-called thermography device by combining it with a two-dimensional scanning mirror, but this semiconductor type element cannot detect infrared rays in the 10 μm band at room temperature.
It must be cooled with liquid nitrogen, etc. The latter type of thermal element has a slow response, but since it operates at room temperature, it can be assembled into a relatively simple device and has the advantage of being easy to use. Among thermal elements, pyroelectric elements have relatively high sensitivity and can be used for high-speed response. However, since the pyroelectric element generates an electric signal tJi -J- that is proportional to the rate of temperature change, it is necessary to modulate the incident infrared rays in order to detect the infrared rays.

As described above, the conventional thermal infrared imaging camera system of Izu 71 has both advantages and disadvantages.

The present invention solves the above problems all at once by combining pyroelectric infrared detection elements arranged in a row with an illumination mirror, and creates a compact and lightweight product with a long life and normal temperature operation. The present invention provides a thermal infrared imaging device that is easy to operate.

As mentioned above, the pyroelectric element outputs an electric signal in proportion to the rate of change in the amount of incident infrared rays, so it requires a -dimensional scanning mirror, a large number of pyroelectric elements arranged in a direction perpendicular to its scanning direction, and imaging optics. When the lenses are fitted together, the infrared light that enters the pyroelectric element becomes the amount of infrared light from the part that scans the two-dimensional field of view.

Figure 1 shows this situation. In the figure, 1 is a near array of multiple pyroelectric infrared detection elements arranged in a line, 2 is an optical lens for infrared light imaging made of germanium, etc., and 3 is rotated in place of rotation @ 4 to be one-dimensional. The panning scanning direction is perpendicular to the arrangement direction of the linear array 1. 5 indicates the field of view to be imaged. 1
, considering that the reflecting mirror 3 is stationary at the position shown in the figure, a two-dimensional image from the field of view 5 enters the reflecting mirror 3, passes through the optical lens 2, and enters the pyroelectric infrared detecting element linear array 1. incident. However, since the near array 1 is arranged one-dimensionally, it cannot receive all two-dimensional images, but only one-dimensional images, for example, one-dimensional image 6 at the left end portion of field of view 5. At the same time, when the reflecting mirror 3 is slightly rotated about the rotation axis 4 in the direction of the arrow a in the figure, the image of the field of view 5 received by the linear array 1 becomes a one-dimensional image that has moved slightly to the right in the figure. Therefore, if the reflecting mirror 3 continues to rotate further in the direction of the arrow a, a two-dimensional image of the entire field of view 5 will be scanned and received by the linear array 1.

FIG. 2 shows the relationship between the infrared radiation distribution in the field of view 5 in FIG. 1 and the output signal of the near array 1. If the infrared radiation distribution meter on line A-A in Figure 1 is as shown in Figure 2(a),
From the corresponding pyroelectric element of the linear array 1, a differential signal of the infrared radiation distribution as shown in FIG. 2 (1) is taken out as an output signal in accordance with the scanning of the reflecting mirror 3. Differential signals of the infrared radiation distribution in the field of view 5 are similarly extracted from other parts of the linear array 1 as the reflecting mirror 3 scans.

Since this signal d corresponds to the visual field direction from each element, it is processed by the signal processing section and integrated by 1jl.
If i, the value of the two-dimensional infrared radiation temperature distribution becomes 8.
This means that the first side can do it. FIG. 3 shows the state of the output signal after the integral processing corresponding to the negative element.

In principle, such a function can be achieved with a combination of a single pyroelectric element and a two-dimensional scanning mirror, but since the pyroelectric element is a thermal infrared detection element, it does not have the same high-speed response characteristics as a semiconductor element. This is not good and the characteristics are extremely poor. However, in -dimensional scanning, if you divide by the role of obtaining one image per second, for example, if the extra-spatial M function is 100 in the scanning direction, then 1
A response of 0m5ec is a good value, and a response characteristic of this level is on the same order as the thermal time constant of the pyroelectric element, so it is possible to make the optimal setting a1 without impairing the sensitivity of the pyroelectric element.
It is possible to create a highly sensitive thermal infrared imaging camera that fully utilizes the characteristics of the pyroelectric element.

On the other hand, the method of arranging pyroelectric elements two-dimensionally and not performing mechanical scanning requires modulation of infrared rays as long as pyroelectric elements are used. will not be taken advantage of. Therefore, the combination of a -dimensional array and a one-dimensional scanning reflector is optimal.

As described above, the combination of the one-dimensional array of pyroelectric elements and the one-dimensional scanning mirror according to the present invention is a method that matches the characteristics of the pyroelectric infrared detection element, has a long life, operates at room temperature, is small and lightweight, and is easy to operate. It is possible to provide a simple and highly sensitive thermal infrared imaging camera.

Incidentally, germanium or silicon semiconductor materials are generally used as the optical lens 2, but since both do not transmit visible light, it is quite difficult to adjust the optical system.

To adjust the optical system, move the optical lens to Z n S
e, KRS E5, Ca F 21 B a
F2.

If it is manufactured from a material that also transmits visible light, such as Zaphire (Aa2o3 crystal), alignment adjustment can be performed using visible light. However, since the refractive index for infrared wavelengths is different from that for visible light, the imaging characteristics cannot be determined with certainty. Therefore, the optical axis alignment is limited to using a laser beam to pass visible light through the center of the lens, but this makes the adjustment very easy.

FIG. 4 shows another embodiment of the present invention, in which a plurality of optical lenses are used and a scanning mirror is placed in the middle of the lens system. In the figure, 41 is a linear array of pyroelectric infrared detection elements, 42, 44 is an optical sensor, 43 is a one-dimensional scanning mirror,
46 is a field of view.

The configuration here is the same as the configuration in FIG. 1 except for the insertion of the optical lens 44. 46 is a −-dimensional array of light emitting diodes, 47 is a screen, and 48 is a signal processing unit for the output signal of the pyroelectric element 41.

The output of the linear array 41 is subjected to predetermined signal processing such as integration processing in the signal processing section 4 and is supplied to an output system (not shown). Further, a part of the output of the signal processing unit 48 is applied to the light emitting diode example 46 to cause the light emitting diode array 46 to blink. This blinking light is reflected by the back surface of the scanning mirror 43 and displayed as a visible image on the screen 47. i.e. field of view 46
The infrared radiation distribution of can be observed as a visible light image.

FIG. 6 shows a specific example of a thermal infrared imaging camera constructed based on the configuration shown in FIG. In Figure 4, Runs 44 is R11 = 73 ± 1 mm, R12 = 120 + 1 mm.
.

The second lens 42 has R21=58±IM, R22=
171Hmm.

A meniscus-type convex lens made of KH2-5 is used, and the scanning mirror 43 is placed at a position 12 from the second lens 42.
It is installed at a position of 2 to 16 degrees (focused at infinity), and the distance between the second lens 42 and the pyroelectric element 41 is 35 degrees. This optical system has a focal length of 50 mm and a viewing angle of 16° x 1
6°, spatial resolution 0.15°.

We have realized a thermal infrared imaging camera with a temperature resolution of 0.6°C.

As described above, the present invention includes a plurality of pyroelectric infrared detection elements arranged in a line or a near array, an infrared lens optical system, and an infrared image scanning reflecting mirror, and the reflecting mirrors are arranged in a linear array. This is a thermal infrared imaging camera that performs panning and scanning in a direction perpendicular to the direction of the camera, and operates at room temperature, so there is no need for a cooling device, no infrared modulation means such as a chopper, and it is a high-performance thermal infrared imaging camera that is easy to operate. You can get a camera.

[Brief explanation of drawings]

Fig. 1 is a conceptual diagram showing the basic structure of a thermal infrared imaging camera according to the present invention, and Fig. 2 a) and (b) are shown in Fig. 1.
Figure 3 is a waveform diagram showing the infrared radiation distribution of the object in the thermal infrared imaging camera and the corresponding output signal of the pyroelectric element. FIG. 4 is a conceptual diagram showing another embodiment of the thermal infrared imaging camera according to the present invention, and FIG. 5 is a conceptual diagram showing a specific embodiment of the thermal infrared imaging camera according to the present invention. 1.41...Pyroelectric element linear array, 2,42
゜44...Optical lens, 3,43...
Reflector, 4°46...Field of view, 46...
Light emitting diode array, 47...Signal processing section, 48
······screen. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 A-A' Figure 3 Time opening Figure 4 Figure 6 46/ 5th ('nu 1 4〆

Claims (3)

[Claims] (1) A plurality of pyroelectric infrared detection elements arranged in a line or a near array, an infrared optical system, and an infrared image scanning reflector are provided, and panning scanning is performed in a direction perpendicular to the scanning linear array. Features: A thermal infrared imaging camera. (2) The thermal infrared imaging camera according to claim 1, wherein a reflecting mirror is installed in the middle of the infrared optical system. (3) The thermal infrared imaging camera according to claim 1, wherein the infrared optical system is formed of an optical material transparent to infrared light and visible light.