JPH10111921A - Infrared image pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately detect the center position of the object video area of a scanner mirror by a small-sized device and to minimize the blur of a display image by arranging a light receiving element so that when the light from a light emitting element is detected with maximum level when the center video of the object image area is inputted to a detector. SOLUTION: The light emitting element 5 is arranged between an objective system 1 and the scanner mirror 2 and off an infrared-ray optical path, and at a center position in plane above the optical path. The light receiving element 6 is arranged in the detector 4 and its position is on the same line with a video detecting element array 4a and off the infrared-ray optical path. At this time, the optical axes of the video detecting element array 4a, light emitting element 5, and light receiving element 6 are aligned with one another in plane, and the light emitting element 5 and light receiving element 6 are arranged in such position relation that when the scanner mirror 2 has its object video center directed to the video detecting element array 4a, the emitted light of the light emitting element 5 which is reflected by the scanner mirror 2 is received by the light receiving element 6 with its maximum level.

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an infrared imaging apparatus, and more particularly, to changing an optical path incident on an objective lens system by a scanner mirror and sending the same to a one-dimensional element array detector via an imaging lens system to generate a video signal. The present invention relates to an infrared imaging device that performs

In recent years, there has been remarkable progress in technology in infrared imaging devices. In particular, the two-dimensional detection element greatly contributes to the reduction in size and weight of the device.

However, for the current two-dimensional element in the 8 to 12 μm band, the detection element of 256 × 256 elements is the subject of research and development, and for a while, a scanner mirror for scanning an image and a one-dimensional array of detection elements are used. By doing so, a high-definition two-dimensional image is obtained.

Most of the conventional infrared imaging devices are mounted on a vehicle, a ship or the like, and there is no need to reduce the size and weight.

Therefore, an optical system in this type of apparatus is designed to separate a horizontal scanning mirror and a vertical scanning (interlacing) mirror to scan an image, and to use a position detecting device ( By mounting a resolver or the like, it was possible to perform precise position detection.

[0005] Assuming that horizontal scanning operates stably, the conventional video data acquisition method acquires video data a fixed time after the center position detection signal is generated, and outputs the data as it is to the screen. Was.

In the case where, for example, 120 elements are used as the one-dimensionally arranged detection elements, an image pickup apparatus having 240 pixels in the vertical direction and 427 samples in the horizontal direction has been put to practical use by performing interlaced scanning.

However, in recent years, the demand for portable infrared imaging devices has been growing, and it has become essential to reduce the size and weight of the optical system, which is the heaviest component.

The reduction of the vertical scanning mirror has already been realized by driving the horizontal scanning mirror in two axes by scanning the horizontal scanning mirror itself in the vertical direction also outside the video data acquisition period.

However, the mechanical vibration caused by the vertical scanning affects the stability of the horizontal scanning, and the amplitude, frequency,
If the effective video data start time is a certain time after the center position detection time because the phase is unstable, the angle at which the video data is captured differs for each scan, and as a result, it appears as image jitter (jitter). .

Therefore, in order to reduce the size and weight of the apparatus, it is necessary to make the position detecting mechanism accurate and simple, and to remove image blur.

[0011]

2. Description of the Related Art The following techniques are known as techniques for solving the above-mentioned problems. (A) In Japanese Patent Application No. 2-068889 or the like, as shown in FIG. 6, first, a scanner mirror 2 which changes an optical path to which an objective lens system 1 is inputted and sends it to a detector 4 via an imaging lens system 3.
There is also proposed an apparatus for detecting a scanning position by changing the optical path from the light emitting element 5 to the mirror surface and sending the light to the light receiving element 6 with a mirror surface. (B) There is also proposed an apparatus for detecting a scanning position by attaching a metal piece to the rotation axis of the scanner mirror 2 and detecting a timing at which the metal piece interrupts the optical path of the position detecting photointerrupter.

The prior art for solving the above problems is as follows: (c) The angle of the scanner is constantly monitored by a resolver attached to the rotating shaft of the scanner mirror, and image data of the angle to be imaged is sequentially taken into the memory. A device that eliminates blurring of a video by displaying it on an image has been put to practical use.

[0013]

However, since the position detecting mechanisms (a) and (b) require a place for arranging a dedicated optical system, there is a limit to downsizing.

Usually, when a person observes an image, he / she is particularly attracted to the vicinity of the center of the screen (target image area). Therefore, accurate center position detection is required in order to prevent image blurring near the center of the screen, but there is still a limit to miniaturization of the apparatus using the resolver or the like described in (c) above.

Accordingly, the present invention relates to (1) an infrared imaging apparatus which changes the optical path of infrared light incident on an objective lens system by a scanner mirror and sends it to a one-dimensional element array detector via an imaging lens system to generate a video signal. It is another object of the present invention to accurately detect the center position of a target video area using a small device, and to further minimize (2) blurring of a display image caused by blurring of scanner mirror scanning.

[0016]

[Means for Solving the Problems]

[1] In order to achieve the object of the above (1), an infrared imaging apparatus according to the present invention comprises a light emitting element disposed between an objective lens system and a scanner mirror and outside the optical path of the objective lens system; A light receiving element arranged to receive light from the element at a maximum level when the central image of the target image area of the scanner mirror is input to the detector.

That is, according to the present invention, when the light emitted from the light emitting element is reflected by the scanner mirror and sent to the light receiving element via the imaging lens system, the light receiving level is determined by the center image of the target image area. It becomes maximum when input to the one-dimensional element array detector.

Therefore, the time when the light receiving element receives the light at the maximum level is the time when the image at the center position of the target image area is detected.

In this case, the position detecting optical system formed by the light emitting element and the light receiving element can use the same reflection surface as the image optical system with respect to the scanner mirror, and the apparatus can be downsized.

[2] In the present invention, in the above [1],
Even if the light emitting element and the light receiving element are exchanged, the same optical system is obtained, and the position detecting optical system formed by the light emitting element and the light receiving element can be overlapped on the same side of the scanner mirror as the image optical system. Can be reduced in size.

[3] In the present invention, the light-emitting element and the light-receiving element provided behind the imaging lens system are arranged so as to always form a constant angle with the mirror surface of the scanner mirror. (1) a position detecting mirror surface for reflecting light to the light receiving element so that light is received at a maximum level when a central image of a target image area of the scanner mirror is input to the detector. It is possible to achieve the purpose.

That is, according to the present invention, when the light emitted from the light emitting element is reflected by the scanner mirror via the imaging lens system and sent to the light receiving element, the light receiving level is such that the central image of the target image area is a one-dimensional element. It becomes maximum when input to the array detector.

Accordingly, also in this case, the time when the light receiving element receives light at the maximum level is the time when the image at the center position of the target image area is detected, as in the case of the above [1].

As in the case of the above [1], the position detecting optical system uses the same reflecting surface as the image forming optical system with respect to the scanner mirror, and both the light emitting element and the light receiving element are on the same detector side. The provision of the device makes it possible to further reduce the size of the device.

[4] In the present invention, the light emitting element and the light receiving element are provided between the objective lens system and the scanner mirror in the above [3] instead of being provided behind the imaging lens system of the detector. Alternatively, the center position can be detected in the same manner as in [3], and the device can be downsized.

[5] Further, according to the present invention, the scanner mirror has a position detecting mirror surface which always forms a constant angle with the mirror surface, and is arranged on the element array line of the detector to reduce cold power caused by cooling of the element. A center position detecting element arranged to receive the cold power emitted and reflected by the position detecting mirror surface at a minimum level when the center image of the target image area of the scanner mirror is input to the detector. The above object (1) can also be achieved by providing a mirror cold shield which is arranged so as to relatively reduce the cold power of the position detecting element.

That is, according to the present invention, the center position of an image can be detected by detecting the cold power emitted from the center position detecting element itself reflected from the position detecting mirror surface formed on the scanner mirror. Becomes

At this time, the cold power emitted from elements other than the center position detecting element is shielded by a mirror cold shield, so that the level of the radiation of the room temperature environment reflecting the mirror surface of the cold shield and the radiation of the center position detecting element is reflected. By increasing the difference, the center position detection accuracy of the center position detecting element can be improved in the same manner as in the above [1] to [4].

Then, as in the case of the above [3], the size of the apparatus can be reduced.

[6] In the present invention, the above [1] to [4]
In any one of the above, the light emitting element can pass through the infrared optical system and emit light having a wavelength not detected by the detector.

As a result, mutual interference between the position detecting optical system and the image optical system can be eliminated.

[7] Further, according to the present invention, in order to achieve the above object (2), an analog / digital converter for converting an analog infrared video signal into a digital video signal, and a frame storage for storing the digital video signal. Unit, a write address generation unit and a read address generation unit for respectively specifying a write address and a read address of the frame storage unit, and a write address when a center position detection signal of the target video area is received as a center sample address. A central sample address storage unit for storing as an address, and an arithmetic unit for calculating an initial address obtained by subtracting an address for half of the number of samples to be displayed from the central sample address. It is characterized in that read addresses for the number of samplings for displaying the video are generated.

That is, in the present invention, when writing video data to the frame storage unit, the sampling number (or corresponding write address) of the timing of the center position detection signal is first written to the center sample address storage unit.

When the video data is read from the frame storage unit for displaying the video, the sampling number (or the corresponding write address) of the center position detection signal is changed from a sampling value (or a corresponding write address) to a fixed value (half of the number of horizontal samples to be displayed, or The address corresponding to the sampling number obtained by subtracting the address corresponding to half of the sample number) is read out and set as the head of the address, and the data is sequentially read out.

As a result, the video data read into the frame storage unit at the timing when the center position detection signal is received is always read as video data displayed at the center of the image, and the image data at the center of the image caused by the blurring of the scanner mirror. And it is possible to suppress blurring of the entire display image.

[0036]

FIG. 1 shows an embodiment (1) of an infrared imaging apparatus according to the present invention. The difference from the conventional example shown in FIG. 6 is that the light emitting element 5 includes an objective lens system 1 and a scanner mirror 2. And outside the infrared light path and above the light path, in a planar manner at the center position;
Is arranged on the detector 4, and its position is on the same line as the image detecting element array 4a as a one-dimensional element array detector and outside the infrared light path.

At this time, the image optical system (image detecting element array 4a) and the position detecting optical system (light emitting element 5 and light receiving element 6)
The optical axis of the scanner mirror 2
Is at an angle at which the center of the target image is directed to the image sensing element array 4a, the light emitted from the light emitting element 5 reflected by the scanner mirror 2 is received by the light receiving element 6 at the maximum level and received by the light emitting element 5 The element 6 is arranged.

The light-emitting element 5 and the light-receiving element 6 are not limited to the above-described arrangement relationship, and light from the light-emitting element 5 is input to the image detection element array 4a with the central image of the target image area of the scanner mirror 2. At this time, any device may be used as long as it is arranged so that the light receiving element 6 receives light at the maximum level.

The light emitted from the light emitting element 5 passes through the imaging lens system 3 and has a wavelength outside the sensitivity range of the image sensing element array 4a. For example, when the material of the lens is Ge, the light emitting element 5 is made of PbSnTe and has a wavelength of 6 μm.
Use those.

Therefore, as the light receiving element 6, an element made of HgCdTe which can receive the light having the above-mentioned wavelength of 6 μm is exemplified.

In operation, light having a wavelength of about 6 μm emitted from the light emitting element 5 is transmitted to the scanner mirror 2 of the infrared imaging optical system.
Then, the light reaches the light receiving element 4a having sensitivity at a wavelength of about 6 μm in the detector 4 via the imaging lens system 3.

At this time, the light from the light emitting element 5 to the scanner mirror 2
The light having a wavelength of about 6 μm that reaches the image sensing element array 4a via the imaging lens system 3 is not detected by the image sensing element array 4a because the wavelength is different.

When the scanner mirror 2 is directed to the center of the target image, the light emitted from the light emitting element 5 input to the light receiving element 6 has the maximum level, is photoelectrically converted by the light receiving element 6, and is output as a center position detection signal. .

Here, the distance between the image sensing element array 4a and the light receiving element 6 may be determined in consideration of the directivity of the light emitting element 5.

As a result, it is possible to reduce the size of the apparatus by superimposing the image optical system and the position detection optical system, and to obtain a highly accurate center position detection signal.

The above center position detection signal can be obtained in the same manner by exchanging the arrangement of the light emitting element 5 and the light receiving element 6.

FIG. 2 shows an embodiment (2) of the infrared imaging apparatus according to the present invention. The difference from the embodiment (1) of FIG. Above, and on the same line as the image sensing element array 4a, and because the emitted light of the light emitting element 5 is reflected at the maximum level to the light receiving element 6 and received when the scanner mirror 2 is directed to the center of the target image. A mirror 7 for position detection which is inclined 45 ° with respect to the plane of the scanner mirror 2 outside the range of the infrared light path and is parallel to the rotation axis 2a.

Therefore, when the scanner mirror 2 is directed to the center of the target image, the horizontal path of the infrared light is changed by 90 ° by the scanner mirror 2 so that the image detecting element array 4a detects the center of the target image. The sensing element array 4a is arranged.

The light emitting element 5 and the light receiving element 6 use the same material as in the embodiment (1).

In operation, when the scanner mirror 2 is directed to the center of the target image, the light emitted from the light emitting element 5 is provided on the scanner mirror 2 via the imaging lens system 3 which is the same optical system as the infrared light. The light reaches the detection mirror 7, is reflected by the position detection mirror 7, returns almost in the same optical path, reaches the light receiving element 6 in the detector 4, is photoelectrically converted by the receiving element 6, and becomes a center position detection signal. Is output.

As a result, as in the case of the embodiment (1), it is possible to reduce the size of the apparatus and obtain a highly accurate center position detection signal.

The center position detection signal can also be obtained by disposing the light emitting element 5 and the light receiving element 6 between the objective lens system 1 and the scanner mirror 2.

Further, although the mirror 7 for position detection is inclined at 45 ° with respect to the plane of the scanner mirror 2, the present invention is not limited to this. Any arrangement is possible as long as the light receiving element 6 can receive light at the maximum level when the central image of the area is input to the image detecting element array 4a.

FIG. 3 shows an embodiment (3) of an infrared imaging apparatus according to the present invention. The difference from the embodiment (2) of FIG. 2 is that a detector 4 is used instead of the light emitting element 5 and the light receiving element 6.
On the same line as the image sensing element array 4a of FIG.
The infrared detecting element 6 serving as the center position detecting element cooled to 0 ° C. is provided, and the mirror cold shield 8 is provided so as to relatively reduce the cold power of the center position detecting element 6. That is. Although the cold shield 8 is provided in the vicinity of the detection element 6 in the horizontal direction as shown in the figure, the cold shield 8 is not limited to this and may be provided in the vicinity in all directions.

Further, when the scanner mirror 2 is directed to the center of the target image, the detection element 6 and the position detection are performed so that the cold power as the radiation light of the detection element 6 is reflected by the position detection mirror surface 7 and returns to the detection element 6 itself. The positional relationship with the mirror surface 7 is set.

In operation, when the scanner mirror 2 is directed at the center of the target image, the cold power radiated by the detecting element 6 reaches the position detecting mirror surface 7 and is reflected, returns to the same optical path and returns to itself.

At this time, since the detection element 6 is cooled to a very low temperature, the output signal at the time of photoelectric conversion is low.

On the other hand, as the scanner mirror 2 directs an image away from the center of the target image, radiation from the room temperature environment is reflected by the mirror cold shield 8 and is input to the detecting element 7. As a result, the level of the output signal obtained by the photoelectric conversion becomes high.

That is, the detecting element 6 is connected to the scanner mirror 2
When the camera directs an image away from the center of the target image, the minimum light receiving level is reached. Otherwise, the light is received at a high level. If this is inverted and used as the center position detection signal, the low-temperature energy emitted by itself can be reliably captured. And can be used as an accurate center position detection signal.

The center position detection signal can also be obtained by arranging the detection element 6 between the objective lens system 1 and the scanner mirror 2.

Further, although the position detecting mirror surface 7 is inclined at 45 ° with respect to the plane of the scanner mirror 2, the present invention is not limited to this. Any arrangement may be used as long as the detection element 6 can receive the minimum level when the center image of the area is input to the image detection element array 4a.

FIG. 4 shows the configuration of an embodiment (4) of an infrared imaging apparatus according to the present invention. An analog infrared video signal is input to an analog / digital conversion section 9, sampled and converted into a digital video signal. Then, the data is stored in one of the frame memories 10a to 10c in the frame storage unit 10 designated by the write address generation unit 12 for each video screen during a write cycle.

The frame memories 10a to 10c store video data of an area wider than the video area to be displayed on the screen. For example, in the case of a device in which the stored n-sampling video data is displayed on the screen, , M including the video data before and after this n sampling (where m
> N) Store sampling video data.

On the other hand, at the timing when the center position detection signal is input, the center sample address storage unit 14 stores the center image of the target image range with the sampling number k corresponding to the address specified by the write address generation unit 12. Store as an address.

The center sample address storage unit 14 stores addresses at which three center images corresponding to the frame memories 10a to 10c for storing respective image screens are stored.

The calculation unit 16 calculates the sampling number (k− (n / 2)) from the sampling number k stored in the center sample address storage unit 14 and the sampling number n / 2 specified by the video range setting unit 15, for example. The operation is performed and given to the read address generation unit 13.

The read address generation unit 13 determines the read start address in response to the operation result, and in the read cycle, converts the address of the video data at the end of the display image stored in the frame memory 10a into the read start address. , And sequentially output to the frame storage unit 10 for the number of n samplings.

Upon receiving this output, the frame memory 10a sequentially outputs digital video data of the designated read address, and the digital video data is converted into a TV video signal by the digital / analog converter 11.

That is, image data for n samplings is output from the frame memory 10a as video data in which the center video data of the target video area sampled at the k-th sampling number is displayed at the center of the display screen.

In other words, the image blur is corrected by adjusting the temporal variation of the center position detection signal caused by the blurring of the scanner mirror operation to the reading of the frame memory in accordance with the variation of the center position detection signal.

Similarly, the frame memories 10b, 10b
The video data stored in c is also displayed with the screen blurring suppressed.

The timing generation circuit 17 supplies a timing signal to the analog / digital conversion section 9, write address generation section 12, read address generation section 13, and digital / analog conversion section 11 for executing the above operation. Is given.

FIG. 5 is a time chart showing the operation of the embodiment (4) shown in FIG. Hereinafter, the operation will be described more specifically with reference to the above embodiments (1) to (3).

FIG. 5A shows the timing at which the video data of the video area is obtained. The odd area shows the first video data acquisition cycle, and the even area shows the next video data acquisition cycle. Thereafter, the odd area and the even area are alternately repeated.

That is, in order to increase the resolution of the video data of the target video area, the infrared imaging apparatus according to the present invention scans the scanner mirror 2 in the horizontal direction to obtain odd video data and then detects video in the vertical direction. Element array 4
a, and scans the target video area in the horizontal direction (interlaced scanning) to obtain even-numbered video data at the intermediate position obtained in the previous horizontal scan. The scanning is returned to the initial state, and the same operation is repeated thereafter.

FIG. 2B shows a center position detection signal as a timing signal when the light receiving element or the center position detection element 6 acquires video data at the center position of the target image area. ) Occur at substantially the middle of the timing of acquiring the video data of the odd-numbered area and the even-numbered area.

FIGS. 3 (3) to 5 (5) show a write cycle and a read cycle of video data of the frame memories 10a to 10b in the frame storage unit 10, respectively.

First, an odd area of the video area is written to the frame memory 10a in a write cycle. Subsequently, even and odd areas of the video area are sequentially stored in the frame memory 10b in a write cycle and a write cycle.
And the frame memory 10c is written to the address specified by the write address generator 12 (see FIG. 4).

Then, the video data written in the frame memories 10a to 10c are sequentially read from the address designated by the read address generator 13 (see FIG. 4) in the read cycle and displayed on the screen.

FIGS. 6 (6) to 9 (9) specifically show the center position detection signal and, for example, the write cycle and the read address cycle of the frame memory 10a.
In the write cycle, the video data in the odd video area is sequentially written to the addresses corresponding to the sampling numbers 1 to m in the frame memory 10a.

In the middle of this writing operation, FIG.
T1 when the center position detection signal shown in FIG.
At this point, the central sample address storage unit 14 stores the write sampling number k.

Subsequently, in the write cycle shown in FIG. 9 (9), the video data of the even video area is
Data is sequentially written to addresses corresponding to sampling numbers 1 ^{* to} m ^* of 0b.

In the course of this write operation, FIG.
T2 when the center position detection signal shown in FIG.
At this point, the central sample address storage unit 14 stores the write sampling number k ^* .

Further, in the read cycle shown in FIG. 7 (7), the video data stored in the frame memory 10a uses the address corresponding to the sampling number (k- (n / 2)) as the read start address and the sampling number ( k
After a total of n pieces of data up to the address corresponding to + (n / 2)) have been read, they are displayed at the positions on the display screen corresponding to the odd-numbered video areas.

As a result, the sampling number k is at the center position (position) of all the n sampling numbers, and the video data corresponding to this sampling number k is output to the center of the display screen.

Subsequently, in the read cycle shown in FIG. 9 (9), the video data stored in the frame memory 10b is sampled by setting the address corresponding to the sampling number (k ^* -(n / 2)) as the read start address. After a total of n pieces of data up to the address corresponding to the number (k ^* + (n / 2)) have been read, the display corresponding to the even-numbered image area complements the position of the display screen corresponding to the odd-numbered image area. Displayed at the screen position.

Then, as in the case of the read cycle of FIG.
^* Is in the center of all the n sampling numbers, and the video data corresponding to this sampling number k ^* is output to the center of the display screen.

In this embodiment, the center sample address storage unit 14 stores the sampling number corresponding to the address where the center image is stored, but may store the storage address itself.

Further, the center position detection signal is obtained in the embodiment (1).
It is not necessary to limit the signal to the signals acquired in (3). For example, a center position detection signal or the like obtained by the conventional position detection device shown in FIG. 6 may be used.

[0090]

As described above, according to the infrared imaging apparatus of the present invention, the light (or cold power) from the light emitting element (or the center position detecting element) is used as the scanner mirror (or the position detecting mirror surface). When the image is given to the light receiving element (or the center position detecting element) via the above, the central image of the target image area of the scanner mirror is arranged to be at the maximum level when input to the one-dimensional element array detector. The light emitting element and the light receiving element can be provided on the same side of the scanner mirror as the image optical system, and the center position of the target image area can be accurately detected by a small device.

Further, according to the present invention, the write address at the time of receiving the center position detection signal of the target video area is stored as the center sample address, and the address corresponding to half of the number of samples to be displayed is stored in the center sample address. By calculating the initial address subtracted from the above and generating read addresses for the number of samplings for displaying the video from the initial address, it is possible to minimize the blur of the displayed image due to the blur of the scanning of the scanner mirror. Becomes possible.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a center position detecting mechanism in an embodiment (1) of an infrared imaging apparatus according to the present invention.

FIG. 2 is a perspective view showing a center position detection mechanism in an embodiment (2) of the infrared imaging device according to the present invention.

FIG. 3 is a perspective view showing a center position detecting mechanism in an embodiment (3) of the infrared imaging apparatus according to the present invention.

FIG. 4 is a block diagram of an anti-shake circuit in an embodiment (4) of the infrared imaging apparatus according to the present invention.

FIG. 5 is a time chart illustrating an operation of a memory control unit in an embodiment (4) of the infrared imaging device according to the present invention.

FIG. 6 is a plan view showing a configuration example of a center position detection mechanism in a conventional infrared imaging device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Objective lens system 2 Scanner mirror 2a Rotation axis 3 Imaging lens system 4 Detector 4a Image sensing element array (one-dimensional element array detector) 5 Light emitting element (center position detecting element) 6 Light receiving element (center position detecting element) 7 Mirror surface for position detection 8 Cold shield 9 Analog / digital conversion unit 10 Digital / analog conversion unit 11 Frame storage unit 11a, 11b, 11c Frame memory 12 Write address generation unit 13 Read address generation unit 14 Center sample address storage unit 15 Image range Setting unit 16 Operation unit 17 Timing generation circuit In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (7)

[Claims] 1. An infrared imaging apparatus for changing an optical path of infrared light incident on an objective lens system by a scanner mirror and sending the image signal to a one-dimensional element array detector via an imaging lens system to generate a video signal. A light-emitting element disposed between the scanner mirror and outside the optical path of the objective lens system, and light from the light-emitting element is input to the detector when a central image of a target image area of the scanner mirror is input to the detector. An infrared imaging device, comprising: a light receiving element arranged to receive light at a maximum level. 2. An infrared imaging apparatus according to claim 1, wherein said light emitting element and said light receiving element are interchanged. 3. An infrared imaging apparatus which changes an optical path of infrared light incident on an objective lens system by a scanner mirror and sends the image signal to a one-dimensional element array detector via an imaging lens system to generate a video signal. The light-emitting element and the light-receiving element provided at the rear of the scanner mirror are arranged so as to always form a fixed angle with the mirror surface of the scanner mirror, and the light from the light-emitting element is used as the central image of the target image area of the scanner mirror. An infrared imaging device, comprising: a mirror for position detection reflecting on the light receiving element so as to receive light at a maximum level when input to the detector. 4. An infrared ray according to claim 3, wherein said light emitting element and said light receiving element are provided between said objective lens system and said scanner mirror instead of being provided behind said imaging lens system. Imaging device. 5. An infrared imaging apparatus for changing the optical path of infrared light incident on an objective lens system by a scanner mirror and sending the infrared light to a one-dimensional element array detector via an imaging lens system to generate a video signal, wherein the scanner mirror is It has a mirror for position detection that always forms a constant angle with the mirror, and furthermore, it is arranged on the element array line of the detector, emits cold power due to cooling of the element, and is reflected by the mirror for position detection. The cold power is a relative value between the center position detecting element arranged to receive the minimum image when the center image of the target image area of the scanner mirror is input to the detector and the cold power of the position detecting element. An infrared imaging device, comprising: a mirror cold shield arranged so as to reduce the number of the mirrors. 6. An infrared imaging apparatus according to claim 1, wherein said light emitting element transmits light through an infrared optical system, and emits light having a wavelength not detected by said detector. 7. An analog / digital converter for converting an analog infrared video signal into a digital video signal, a frame storage for storing the digital video signal, and a write address and a read address of the frame storage. A write address generation unit and a read address generation unit; a center sample address storage unit that stores a write address when the center position detection signal of the target video area is received as a center sample address; And an arithmetic unit for calculating an initial address obtained by subtracting the address from the center sample address, wherein the read address generating unit generates read addresses for the number of samples to be displayed on the video from the initial address. Infrared imaging device.