JPH09119862A - Infrared imaging device - Google Patents

Abstract

The present invention relates to an infrared imager, which enables rationalization and real-time correction of sensitivity and defect pixel correction of input infrared data, and appropriate display gain / level adjustment of an area to be observed. The task is to In an infrared imaging device having an optical system composed of a plurality of optical lenses, a reference heat source section arranged near an actual image forming surface inside the optical system and outside a visual field to be imaged, and an observation object. And an infrared detection unit that detects infrared rays emitted from the reference heat source unit and outputs an electrical detection signal, and a reference data acquisition unit that obtains only the detection signal corresponding to the infrared rays emitted from the reference heat source unit. It is characterized by including.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an infrared imager, and more particularly to an infrared imager having sensitivity correction using a reference heat source, defective pixel correction, and automatic gain / auto level adjustment functions.

[0002]

2. Description of the Related Art A conventional infrared imager is provided with a plurality of infrared sensors arranged in a straight line, and an infrared ray from a subject is electrically scanned by scanning within a predetermined visual field. The image is formed by converting it into an analog signal. However, since there are variations in performance such as sensitivity and output characteristics of each infrared sensor, when the output signal obtained from each infrared sensor is directly used as an image, horizontal lines (sensitivity unevenness) occur in the scanning direction. Therefore, in the conventional device, a device having a reference heat source set in advance to a constant temperature is separately prepared, and infrared rays emitted from this reference heat source are received prior to observation to obtain reference data in advance, A video signal obtained from an actual subject is corrected in advance with this reference data.

FIG. 15 shows an example of a conventional apparatus configuration diagram for obtaining reference data. The infrared imager is composed of an infrared camera section 8 and an infrared control section 7. In order to acquire reference data,
A reference heat source plate 1, a controller 2 for adjusting its temperature, and a computer 5 for acquiring data are required. Further, the infrared control unit 7 is provided with a computer interface board 3 for connecting the computer 5 and a computer port 4, and the computer 5 has software 6 for data acquisition incorporated therein.

The reference heat source plate 1 is composed of a plurality of reference heat sources, and the temperature of each of them is individually adjusted by a temperature adjusting circuit inside the controller 2. The infrared camera unit 8
Like a video camera, it is composed of a plurality of lenses, a zoom optical system including a motor for controlling three elements of zoom, focus, and tracking, and a detector for detecting infrared rays collected by the zoom optical system. It The detector is composed of n infrared sensors aligned in the vertical direction so as to correspond to n scan channels in the vertical direction of the display screen, and the infrared signal is converted into an electrical analog signal.

The infrared control section 7 includes an A / D conversion section for converting an analog signal obtained from the detector into a digital signal, a sensitivity correction section for correcting a variation in accuracy of each infrared sensor, an automatic gain adjustment section, and a defective pixel correction. It is composed of parts.

Here, the analog signal output from the detector is separated into an offset component called dark current and a signal component that truly contributes to the image of the subject. Since the infrared sensors constituting the detector have different performances, even if infrared rays emitted from the reference heat source of the same temperature are detected, the signal components do not always have the same level. Sensitivity correction is to make the level of the signal component of each infrared sensor uniform and to correct the variation among the infrared sensors.

In FIG. 15, the reference heat source adjusted to a constant temperature is photographed, and the level value of the signal component obtained by each infrared sensor is recorded by the data acquisition computer. Also, from the level values of these signal components,
By calculating the difference or ratio, the reference data for sensitivity correction is obtained and stored in the ROM. When shooting an actual subject, this R
The sensitivity is corrected by incorporating the OM into the infrared control unit 9 and comparing the level value of the actually measured signal component with the reference data stored in the ROM.

However, the conventional sensitivity correction has the following problems. (1-1) It is necessary to prepare a reference heat source separately from the infrared imaging device. (1-2) Place the reference heat source in front of the infrared camera,
In addition, a dedicated device (a computer for data acquisition, an I / O interface board such as software) for acquiring the reference data for sensitivity correction is prepared separately, and adjustment and ROM production are performed prior to actual photographing of the subject. is required. (1-3) When data of a plurality of reference temperatures are required as the reference data for sensitivity correction, the temperature of the reference heat source may be changed, but the offset component may change due to the temperature change. Yes, it is difficult to obtain accurate reference data. (1-4) The offset component and the sensitivity of the infrared sensor may change between the time of acquiring the reference data and the time of actual photographing, which may cause inaccurate correction. . (1-5) Each reference heat source is controlled by a separate temperature adjustment circuit, but if the difference between the set temperature of the reference heat source and the ambient temperature at the time of measurement is large, the current consumption for temperature control of the reference heat source is large. Become.

Looking at the conventional infrared imager from another point of view, it has the following defective pixel correction function.
A detector is typically several hundred infrared sensors arranged in rows and each sensor is inspected for defects before shipping. Depending on the resolution of the infrared image, if there are one or two defective infrared sensors, a linear stripe may appear on the image at the defective sensor position. However, in normal images, the brightness of adjacent pixels does not differ so much, so even if the same value as the output value of the sensor before and after the defect sensor is adopted, the image quality deteriorates so much to the human eye. I can't feel it. Therefore, the output of the defective infrared sensor is replaced with the output of a normal infrared sensor located before and after the defective infrared sensor.

Conventionally, in order to perform such defective pixel correction, defective pixel correction data has been acquired in an inspection process step by using a special configuration as shown in FIG. FIG.
The signal component of the image data when the reference heat source shown in (4) is set to a relatively high temperature and the signal component of the image data when it is set to a low temperature are stored for each infrared sensor, and preset by the comparator for each temperature. Compare with the set value.
Then, as a result of the comparison, if the predetermined condition is satisfied, the infrared sensor is determined to be normal, but if the condition is not satisfied, it is determined to be abnormal, and the infrared sensor should be replaced together with the address indicating the position of the infrared sensor. The address of the infrared sensor is stored in the address conversion table. This address conversion table is written in a ROM for use as defective pixel correction data, and this ROM is used for the infrared control unit 7.
The defective pixel correction is performed by being incorporated in.

However, the conventional defective pixel correction using such a ROM has the following problems. (2-1) It is necessary to prepare one defective pixel correction ROM for each manufactured detector at the inspection process stage. (2-2) When the infrared imaging device has been used for many years, the created ROM may not be able to cope with characteristic changes due to aging. For example, if the defective pixels increase due to long-term use, the created ROM cannot handle it, and the ROM must be recreated.

Next, looking at the conventional infrared imager from another point of view, it has the following gain / level adjusting function. The conventional infrared control unit 7 includes a gain / level adjustment circuit similar to that of a video camera, and measures the maximum value, the minimum value, and the average value of the signal components of the image data of the entire imaged display area. Then, in the gain adjustment, the signal level difference between the maximum value and the minimum value is adjusted so as to match the dynamic range of the infrared imaging device, and in the level adjustment, the average value is adjusted to be the intermediate color of the display area. . However, if there are high and low temperature parts with a considerable temperature difference in the photographed subject, the high temperature part can be seen well, but the low temperature part is hidden in the background even if the gain / level is adjusted. Since it was not visible, it was difficult to optimally adjust the gain / level so that the target low-temperature observation object could be easily seen.

Next, looking at the infrared imager from another point of view, it has the following zoom optical system. Normal FIG.
As shown in FIG. 7, a plurality of lenses are driven by different motors M for zooming, focusing and tracking, respectively. However, the focus command, zoom command and tracking command input by a volume or switch are different from each other. After being converted into an analog signal by the D / A converter, the signal is amplified by an amplifier, further feedback-controlled, and given to the motor as a drive signal.

Further, an overcurrent detection circuit is provided in order to prevent an abnormality from occurring in the motor drive control due to an overcurrent flowing in the signal for driving the motor. The overcurrent detection circuit shuts down the motor by cutting off the drive current with a switch or the like when the peak value of the current actually flowing in the circuit for driving the motor exceeds a predetermined value.

However, the conventional zoom optical system has the following problems. (3-1) The circuit scale is large because separate signal conversion circuits are provided for controlling the zoom, focus, and tracking motors. (3-2) Since the overcurrent is detected only by the magnitude of the current value of the motor drive circuit, the motor is stopped even by the overcurrent generated for a very short time despite the normal operation.

The present invention has been made in consideration of the above circumstances, and provides an infrared imaging device intended to solve the following problems. (1) To rationalize the device and work for sensitivity correction and realize more accurate real-time sensitivity correction. (2) Rationalization of the device and work for defective pixel correction,
To be able to respond to aging of detectors. (3) It is possible to appropriately adjust the display gain and level of the region to be observed in the captured image. (4) To rationalize an optical control circuit that generates a signal used for controlling the zoom optical system and perform appropriate overcurrent detection corresponding to the actual situation.

[0017]

According to a first aspect of the present invention, in an infrared imager having an optical system composed of a plurality of optical lenses, the present invention captures an image near an actual image forming plane inside the optical system. A reference heat source unit arranged outside the field of view, an infrared detection unit that detects an infrared ray emitted from the observation object and the reference heat source unit, and outputs an electrical detection signal, and the reference heat source unit emits the infrared ray. An infrared imaging device, comprising: a reference data acquisition unit that acquires only a detection signal corresponding to infrared rays.

Here, the reference heat source part may be only one reference heat source plate that can be controlled to a predetermined temperature, or a plurality of reference heat source plates that can be controlled to different predetermined temperatures. Good. Further, in the infrared imaging device of the present invention, the infrared detection unit is composed of a plurality of infrared sensors, the detection signal of the observed object output by each infrared sensor is the reference acquired by the reference data acquisition unit You may make it further provide the sensitivity correction part which correct | amends by a detection signal.

Further, in a second aspect, the present invention provides
In an infrared imaging device having an optical system including a plurality of optical lenses, a reference heat source unit disposed near an actual image forming surface inside the optical system and outside a field of view to be imaged, an observation object, and the reference heat source. With an infrared detection unit that detects an infrared ray emitted from the unit and outputs an electrical detection signal, the infrared detection unit is composed of a plurality of infrared sensors, and corresponds to the infrared ray emitted from the reference heat source unit. If the detection signal output by a certain infrared sensor satisfies the defect determination condition, it is determined that the infrared sensor is a defective element. An infrared imaging device further comprising a defective pixel determination unit.
Here, the defective pixel determination unit further includes a defective pixel correction unit that replaces a detection signal output by an infrared sensor that is determined to be a defective pixel with a detection signal output by an infrared sensor near the infrared sensor. You may do it.

In a third aspect, the present invention is an infrared imager having an optical system composed of a plurality of optical lenses, which detects infrared rays emitted from an observation object and outputs an electrical detection signal. A frame designating section for designating a desired video area in the captured infrared image, a designated frame signal obtaining section for obtaining only the detection signal in the video area designated by the frame designating section, and the designated frame signal An infrared image device, comprising: an adjusting unit that automatically adjusts the gain and level of an image in the image area by using only the detection signal obtained by the obtaining unit.

Further, in a fourth aspect, the present invention provides
In an infrared image device having an optical system composed of a plurality of optical lenses, an optical control unit for controlling zooming, focusing and tracking of an infrared image captured by adjusting the position of the optical lens is provided, and the optical control unit, An input unit for inputting control amounts of zoom, focus and tracking, a time division multiplexing unit for time-division multiplexing these input control amounts at a predetermined timing, and a time-division multiplexed control amount for the predetermined amount. The present invention provides an infrared imaging device, characterized in that the infrared imaging device is provided with a driving unit that takes out separately at the same timing as the timing and changes the position of the optical lens.

The reference heat source portion constituting the above infrared imager of the present invention may be an element whose surface is kept at a predetermined temperature by passing a constant current, for example, a Peltier element is used. .

The infrared detecting section is composed of a so-called infrared sensor. An infrared sensor is a kind of photoelectric conversion element that outputs an electrical detection signal according to its intensity when infrared rays are applied to its surface. Here, it is preferable that the infrared sensor can mainly detect infrared rays in the 8 to 12 μm band and the 3 to 5 μm band. Further, the infrared detecting section may have a structure in which hundreds of such infrared sensors are aligned in the vertical direction, or may have a structure in which several infrared sensors are aligned in the horizontal direction. For example, 240 infrared sensors in the vertical direction and two rows of infrared sensors in the horizontal direction can be arranged. Here, the infrared sensor in the top row is called the infrared sensor of channel 1, and the infrared sensor in the bottom row is called the infrared sensor of channel 240.

Since the reference data acquisition unit sequentially stores the detection signals output from the infrared detection unit, it is preferable that the reference data acquisition unit includes a rewritable memory such as a RAM. When the reference heat source portion is composed of a plurality of reference heat source plates, for example, a bar-shaped reference heat source plate that is long in the vertical direction may be arranged in the horizontal direction by a predetermined number. The sensitivity correction unit is for eliminating variations in the detection signal of the observation object output by each infrared sensor and making it uniform, and for obtaining a coefficient of sensitivity correction, an averager, subtractor, and multiplier of the detection signals are used. It is configured by combining logic circuits such as a container. Further, the reference detection signal acquired by the reference data acquisition unit is used as the data that is the basis of the equalization.

In the defective pixel determination section, it is preferable to use a detection signal corresponding to infrared rays emitted from the reference heat source section as an input signal for determining the quality of the infrared sensor. The defective pixel determination unit can be configured by a comparison circuit composed of various logic elements, but it is configured to compare a predetermined set value for performing defect determination with an input detection signal or an average value of the detection signals. May be. For example,
The output value of the detection signal that should be output by the infrared rays emitted from the reference heat source that is kept at a predetermined temperature is set in advance as a judgment condition, and the output value of the detection signal actually output from the infrared sensor is set. If the output value of the specified judgment condition is equal to or more than that, the infrared sensor is normal,
If it is below or considerably below the infrared sensor, it may be determined that the infrared sensor is a defective element.

The defective pixel correction unit is a kind of address replacement circuit for an infrared sensor, and is composed of a logic circuit such as a buffer, a comparator and a flip-flop. That is, a process of replacing the address of the infrared sensor determined to be defective with the address of the infrared sensor near the infrared sensor is performed, and the image data of the image display position in charge of the infrared sensor determined to be defective is The image data output by the infrared sensor near the infrared sensor is replaced. Here, the vicinity means, for example, an infrared sensor immediately above the infrared sensor determined to be defective, or an infrared sensor immediately below the infrared sensor, but is not limited to this.

The frame designating section is composed of a ROM or a RAM. The information about the desired image area input by the observer is converted into address data that specifies the image area by using the frame data stored in the ROM or the like. The designated frame signal acquisition unit is composed of a buffer, a comparator and the like, and acquires only the video data of the address that matches the address data. The adjusting unit for adjusting the gain and level of the image can be configured in the same manner as the conventional circuit by combining logic circuits such as an averaging unit, a subtracter, a multiplier, and an inverse number generator of the input signal.

The optical control unit is composed of an A / D converter, a signal multiplexing / demultiplexing circuit, an adder, etc., and has a structure capable of time-division multiplexing and demultiplexing a plurality of digitized signals. Here, in the infrared imaging device, the controlled amount includes three elements of zoom, focus, and tracking, but is not limited to this. If these three elements are used, zoom, focus, and tracking 3
One control amount is time-division multiplexed, but in general, when there are n elements to be controlled, n control amounts may be time-division multiplexed. As the drive unit, for example, a motor that rotates or moves the lens is used. When adjusting the three elements of zoom, focus, and tracking, independent drive motors may be provided.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below based on the embodiments shown in the drawings. The present invention is not limited by this. FIG. 1 shows a block diagram of an embodiment of an infrared imaging device of the present invention. Here, an infrared imaging device provided with all of a reference heat source, a sensitivity correction unit, a defective pixel correction unit, an automatic gain / level adjustment unit, and an optical system control unit, which characterize the present invention, is shown. A part of the configuration of the device may be replaced with the components of the present invention, or a combination of some required components may be used. Reference numeral 114 denotes a zoom optical system including a plurality of lenses 115, a reference heat source 105, and motors 116, 117, and 118 for controlling zoom, focus, and tracking, respectively, and a signal for driving the motor for zoom, focus, and tracking. Is the optical system control unit 104
Given by

Reference numeral 110 is an infrared detector. Infrared rays emitted from the subject are condensed by the lens 115, are horizontally scanned by a scanning mirror (not shown), and are applied to the detector. The detector 110 may be the same as that used conventionally, but may be, for example, one in which several hundred infrared sensors arranged in a direction perpendicular to the scanning direction (that is, in the vertical direction) are arranged in a row. Can be used. The infrared rays with which the detector 110 is irradiated are converted into an electrical analog signal according to the intensity thereof and given to the A / D converter 111.

The A / D converter 111 converts the analog signal obtained by the detector 110 into a digital signal having several level values. Further, this digital signal is converted into a television signal via a sensitivity correction unit 101, a defective pixel correction unit 102, an automatic gain / level adjustment unit 103, a DSC (Digital Scan Converter) processing unit 112, and a D / A conversion unit 113. It is given to a display device such as a CRT. Here, the DSC processing unit 112 reads 1 read by the infrared sensor.
Scan conversion processing is performed to write video data for a screen in a memory and read it as horizontal data that can be displayed on a display device.

The reference heat source 1 which is a feature of the present invention will be described below.
05, the sensitivity correction unit 101, the defective pixel correction unit 102, the automatic gain / level adjustment unit 103, and the optical system control unit 104 will be described.

1. Reference Heat Source In the present invention, a reference heat source 105 for obtaining data (hereinafter referred to as reference data) serving as a reference for sensitivity correction and the like is provided in a so-called field stop. FIG. 2 shows an explanatory view of the arrangement of the reference heat source 105. The field stop means, as shown in FIGS. 1 and 2, a plate provided in one position outside the visual field of the photographing range, in the vicinity of the image plane on which the photographed image is once focused and imaged. To do. The reference heat source 105 is a field stop formed of one plate and has a rod-shaped Peltier element attached in the vertical direction on the surface of the detector side thereof. This Peltier element is connected to a constant current control circuit and controlled so that it is always maintained at a predetermined temperature.

Assuming that the scanning by the scanning mirror starts from below the image plane as shown in the top view of FIG. 2A, the image data at the bottom of the field of view is stored as the first sample data in each infrared sensor of the detector. Then, the data above the image plane is sequentially captured by scanning. Usually, after imaging data of 430 samples is captured up to the top of the field of view, infrared data emitted from the reference heat source on the field stop above it is captured by each infrared sensor.

If the reference heat source 105 is provided at such a position, the conventional apparatus and work for acquiring the reference data are not required. Further, by using the circuit configuration as described below, the reference data can always be acquired in real time by the infrared image device alone, and more accurate sensitivity correction or the like can be performed.

FIG. 3 shows an example of a circuit for acquiring reference data from the reference heat source 105 of the present invention. This acquisition circuit is provided at the input portion of the sensitivity correction unit 101. A /
As described above, the D conversion unit 111 converts the analog signal of each infrared sensor obtained by the detector into a digital signal, which corresponds to the obtained image data and the first position of scanning by the scanning mirror. A control signal (also referred to as a head data timing signal) indicating the timing at which the video data is output from the infrared sensor and an address signal for storing the video data (including the reference data) are output. Although not shown, this address signal indicates the address of the memory (RAM) 31.

The control signal and video data output from the A / D converter 111 are input to the capture signal generator 32,
A reference data acquisition timing signal is generated. Since the position of the field stop is fixed here,
The time (one scanning time) from the input of the control signal indicating the beginning of the scan to the input of the reference data obtained by scanning the reference heat source 105 on the field stop is constant. Therefore, the reference data acquisition timing signal may be output after counting one scanning time after the control signal indicating the head is input.

The capture signal generator 32 can be constructed using, for example, a logic element such as a counter or a flip prop. Then, the timing signal for fetching the reference data is input to the memory (RAM) 31 as a write control signal, and the video data is input at the same input timing as the timing signal, that is, the reference heat source 10.
The reference data obtained by 5 is written in the memory (RAM).

FIG. 4 is a schematic diagram showing the acquisition timing of such reference data. The scanning pattern shown in the upper part of the figure shows the scanning position on the image plane of FIG. 2 and is drawn by extending it in the horizontal time axis.
That is, the scanning pattern is the timing for capturing the video data in sample 1, and 430 in the figure is the timing for capturing the video data in sample 430. The image data is a signal detected by the detector, and indicates that the reference data from the reference heat source is output immediately after the data of the sample 430.

Further, the reference data fetch timing signal is output at the same time as the timing of the reference data as shown in FIG. 4 at a predetermined time after one scanning period has elapsed since the video data of the sample 1 was input. Sample 1
Since the video data from the sample to the sample 430 are obtained from the infrared sensors arranged in the vertical direction, the data for each sample on the screen of the display device corresponds to the video signal in the vertical direction. In this way, it becomes possible to always take in the image data within the normal visual field as well as the reference data used for sensitivity correction and the like at fixed scanning timings.

In the above, the embodiment in which one reference data is taken into the field stop by using the reference heat source kept at only one set temperature has been described. However, the reference data corresponding to a plurality of set temperatures is shown. An example is shown below in which a plurality of data are captured. In this case, a plurality of reference heat sources may be provided on the field stop.

FIG. 5 is an explanatory view of the arrangement of the reference heat source in the case of this embodiment. 5A and 5B are a top view and a side view, respectively, and the reference heat source is provided at the same position as in FIG. FIG. 5C is an enlarged view of the field stop having a plurality of reference heat sources. As shown in FIG. 5C, a plurality of slits (n channels) are provided on the surface of the field stop on the detector side. Each slit has a rod shape that is long in the vertical direction, and may be formed to have a width of about several mm. Then, the same number of reference heat sources (for example, Peltier elements) are bonded behind each slit.

These reference heat sources may be adjusted to their respective preset temperatures by using a temperature adjusting circuit as in the conventional case. However, if the number of reference heat sources increases, the current consumption increases as the number of reference heat sources increases, which is not preferable because the infrared imager consumes more power. Therefore, the difference between the temperature set for each reference heat source and the current ambient temperature is always stored, and the control amount for setting the reference heat source to the current ambient temperature and the control amount corresponding to this temperature difference are digitally stored. Add or subtract in the value state.

Then, the digital value after addition and subtraction is converted into an analog signal so that each reference heat source can be changed to its respective predetermined temperature, so that it is always necessary to control the temperature by the difference from the current ambient temperature. Therefore, the current consumption can be suppressed as compared with the conventional case, and the control of the reference heat source with high power efficiency becomes possible. FIG. 8 shows an example of a circuit configuration diagram for controlling the temperature of the reference heat source as described above.

FIG. 6 shows a reference data acquisition circuit in the case where the field stop shown in FIG. 5C is used, and FIG. 7 shows a schematic diagram of the reference data acquisition timing. Here, FIG. 6 corresponds to FIG.
It corresponds to an acquisition circuit when n reference heat sources are used, and one acquisition signal generator 32 and n memories (RAM)
31-1, 31-2 ..., 31-n, and n comparators, decoders, and selectors (SEL). Reference data corresponding to n reference heat sources are stored in each memory. Each comparator compares the input video data with each reference data stored in the memory (RAM), the output is selected by the decoder, and the reference data most suitable for the input video data is the selector ( SEL).

Further, FIG. 7 corresponds to FIG. 4, and shows that reference data 1, 2, ... N respectively corresponding to n reference heat sources are obtained in the same manner. Here, from the capture signal generator 32, the timings at which the respective reference data 1, 2, ... N can be acquired from the control signal indicating the beginning of scanning are separately generated.

As described above, by providing a plurality of slits in the field stop and attaching the reference heat source corresponding to the slits, it becomes possible to simultaneously obtain reference data for a plurality of temperatures. Therefore, since a plurality of pieces of reference data can be acquired at the same time, it is possible to prevent an error due to a change in the offset component that occurs when a plurality of pieces of reference data are conventionally acquired with a time difference. Further, for this reason, the sensitivity can be corrected with higher accuracy.

2. Sensitivity Correction Next, an example of the sensitivity correction unit 101 that performs sensitivity correction based on the reference data thus obtained will be described. FIG. 9 shows an example of a sensitivity correction circuit configuration diagram of the present invention. Although an example in which one reference heat source is provided is shown here, when a plurality of reference heat sources are provided, a plurality of similar circuits may be provided in accordance with this. In the figure, 31 is the memory (RAM) shown in FIG. The memory 31 is divided into two areas, the area of the reference data A stores the reference data by the reference heat source obtained as shown in FIG. 3, and the area of the reference data B is the reference for the lowest temperature. The value of zero as data is stored.

The reference data A stores reference data for samples 1 to n (for example, 430) of the detector. The data averaging units 33 and 33 'calculate the average value of these reference data. It Reference numeral 35 denotes a subtracter, which compares the reference data for each sample and outputs the difference (AB) to the next reciprocal table 34. In the reciprocal table 34, the reciprocal of the difference value (AB) of the reference data is calculated and output.

Reference numeral 36 is also a subtracter, and the reference data A and B
The difference between the respective average values of is calculated. This subtractor 36
Output becomes a coefficient value for sensitivity correction for each infrared sensor corresponding to each channel. This coefficient value is for equalizing the signal components of all channels. That is, the image data output from the infrared sensor that outputs a signal component lower than the average is multiplied by a high coefficient value, and the image data output from the infrared sensor that outputs a signal component higher than the average has a low coefficient value. Is multiplied. Thereafter, the multiplier 37 outputs the output of the reciprocal table 34 and the subtractor 3
The output of 6 is multiplied. The multiplier 38 multiplies the data of the actually shot video output from the A / D converter 111 by the coefficient value of this correction.

As described above, in order to correct the variation in the performance of each infrared sensor, the averaged coefficient value of the sensitivity correction is obtained, and this is multiplied by the actual image data to perform the sensitivity correction in real time. To be done. Therefore, in the past, when the sensitivity of the detector changed with the passage of time, there were times when accurate sensitivity correction could not be performed.
If the sensitivity correction unit as in the present invention is provided, it is possible to perform accurate sensitivity correction that follows changes in sensitivity over time.

3. Defective Pixel Correction Here, the circuit configuration and operation of the defective pixel correction unit 102 shown in FIG. 1 will be described. With the configuration as described below, it is not necessary to acquire the data for defective pixel correction in advance, and defective pixel correction can be performed in real time.

FIG. 10 shows a defective pixel correction unit 10 of the present invention.
2 shows an example of a circuit configuration diagram of No. 2. Here, the S / H unit 41
Is a so-called sample hold circuit, which latches each video data detected by each infrared sensor and digitized by the A / D converter 111. Averaging unit 42
The video data provided from the A / D converter 111 is collected for each infrared sensor for one scanning period to obtain an average value thereof. The multiplier 43 multiplies the calculated average value by a preset defect determination reference value. This multiplier 4
The output of 3 is a reference level value for determining the infrared sensor as a defective pixel. The comparator 44 compares the image data of each infrared sensor output from the S / H unit 41 with the defective pixel determination reference value output from the multiplier 43. Here, if the image data of each infrared sensor is lower than the defective pixel determination reference value, the infrared sensor is determined to be defective, and if it is high, it is determined to be normal,
As an output of the comparator 44, a signal indicating normality / defectiveness (good / bad signal) is output.

The replacement data generator 45 replaces the address of the infrared sensor given from the A / D converter based on the signal indicating normality / failure. That is, when the address of a certain infrared sensor is input and the signal indicating normality is input, the replacement data generation unit 45 does not perform the replacement and outputs the address as it is. When a signal indicating a defect is input when the address of a certain infrared sensor is input, the address before or after the address of the infrared sensor is output. The replacement data generation unit 45 can be composed of logical circuits such as AND, OR and registers.

The comparator 47 includes a DSC processor 112.
The vertical direction (V direction) address given by the above is compared with the address output from the replacement data generation unit 45.
As a result of this comparison, when both addresses match, the address is output as it is to the DSC processing unit 112 as a pixel address signal. If the two addresses are different, the address output from the replacement data generation unit 45 is output to the DSC processing unit 112, and the DSC processing unit 112 converts the data at the position of the V direction address on the display screen to the replacement data generation unit 45. The data at the position indicated by the address output from is replaced.

The quality signal is also input to the defective pixel monitoring section 46. The defective pixel monitoring unit 46 counts the number of signals indicating defects among the quality signals, compares the number with a predetermined threshold value set by the setting unit 48, and when the count value exceeds this threshold value, Is to send an alarm signal to the D / A converter. That is, when the number of infrared sensors determined to be defective elements exceeds a predetermined number, an alarm is displayed to notify an external observer that the detector has failed. The alarm signal is converted by the D / A conversion unit and displayed as a warning by voice or characters / symbols. Alternatively, a display stop process or the like may be triggered by an alarm signal.

The defective pixel monitoring unit 46 can be composed of a logic element such as a counter, a comparator, a flip-flop, or the like. The setting unit 48 can use a RAM, a register, or a DIP switch. It should be noted that the threshold value set in the setting unit 48 may be set to a value such that about several percent of the total number of pixels on the display screen becomes defective and it may be difficult to check the subject by looking at the display screen. Good.

As described above, by providing the defective pixel correction circuit, it is possible to provide a device for acquiring the defective pixel correction data, which has been conventionally performed, and it is not necessary to perform the acquisition work in advance, so that the normal photographing is performed. It is possible to perform defective pixel correction in real time while executing further,
Since it is constantly monitored whether or not defective pixels occur, it is possible to cope with characteristic changes due to aging of the detector.

4. Automatic Gain / Level Adjustment Here, an example will be described in which a frame for designating a certain area of the display screen is provided and the gain / level of the area is automatically adjusted. FIG. 11 shows an example of a block diagram of the automatic gain / level adjustment circuit of the present invention. Here, the feature of this automatic gain / level adjustment circuit is that it is provided with a frame designation ROM 51 and a detection data fetching section 52. The frame designation ROM 51 is a table for determining the address of the designated frame from the input pixel address and frame variable data. Here, the observer looks at the display screen and
Perform the operation to specify the area where you want to adjust the level.

For example, an address (pixel address) at the upper left position of the frame and frame variable data (frame size: vertical and horizontal lengths) are input from a keyboard or the like. Based on the input pixel address and the size of the frame, the frame designation table is referred to, and the leading address and the ending address of the area where the gain / level is to be adjusted are given to the detection data fetching section 52. This operation is executed by a hardware logic circuit or a CPU (not shown). The detection data fetching unit 52 sequentially fetches only the video data within the given region among the video data sent from the sensitivity correction unit 101. The detection data acquisition unit 52 can be configured by a combination of logic circuits such as a counter, a buffer, and a flip-flop.

Next, for the captured video data,
The gain / level is adjusted in the same manner as before, and the video data is output. That is, the maximum value and the average value of the video data respectively taken in by the maximum value detection unit 53 and the average value detection unit 54 are obtained, and the subtractor 55 calculates "maximum value-average value", and then the reciprocal thereof is obtained, Further, the multiplier 57 multiplies the reciprocal by the actual video data. This allows
The average value of the data in the designated frame is adjusted to the middle level of the display dynamic range. This means that the brightness of the video data within the designated frame is adjusted.

Further, the subtracter 58 subtracts the average value obtained by the average value detecting section 54 from the image data after the brightness adjustment. As a result, the level of the video data in the frame has been adjusted. Thereafter, the video data whose automatic gain / level is adjusted is output to the DSC processing unit 112. By doing so, the gain / level adjustment is automatically performed only for the image data within the frame designated by the observer, so that the display gain and display level for the image within the frame can be optimized.

5. Zoom Optical System Control An embodiment will be described in which control signals for driving the zoom, focus, and tracking motors are given in a time division manner to control the respective motors. FIG. 12 shows an example of a configuration diagram of the optical system control unit 104 of the present invention. Latches 61 and 6
Reference numerals 2 and 63 are for fetching the focus command at the fall of the focus control signal, for fetching the zoom command at the fall of the zoom control signal, and for fetching the tracking command at the fall of the tracking control signal. D
The / A units 64, 65, 66 convert the focus, zoom, and tracking drive signals from digital to analog, respectively. This conversion is triggered by the rise of focus, zoom, and tracking processing signals. The three PAs are motor drive amplifiers that amplify the analogized drive signals.

The positions of the plurality of lenses in the zoom optical system are adjusted by the focus, zoom, and tracking motors, and the current control amounts can be detected by the rotation amount of each motor. The three potentiometers P generate signals indicating respective control amounts of focus, zoom and tracking, and the amplifier A amplifies these signals. A / D section 67, 68, 6
A digitizes a signal (referred to as a position detection signal) indicating each control amount of focus, zoom and tracking.
/ D converter. The digitization of this signal is also performed by using each control signal as a trigger.

The adder 70 multiplies the signal A after multiplexing the focus command, the zoom command, and the tracking command, which are time-divided and fetched by the latch, and three A / Ds.
This is to add a signal B after multiplexing signals indicating respective control amounts output from the unit. Further, the focus command, the zoom command, and the tracking command are, for example,
It is a digital signal after A / D conversion of an analog signal generated by an observer operating a volume or a switch.

The focus control signal, the zoom control signal, and the tracking control signal are signals for synchronizing the reading of the above three digital signals, and are generated by the CPU controlling the digital circuit portion. . In order to control each motor in a time-division manner, these three control signals are generated at a timing shifted by a predetermined time. For example, each control signal is (1/6
It is sequentially output in time division for a time of 0) × (1/3) seconds.

Next, the operation of controlling the motor drive signal in a time division manner will be described. FIG. 13 shows a timing chart of the time division control. As shown in the figure, the focus control signal, the zoom control signal, and the tracking control signal are given as low active signals for a predetermined period in this order. The repeating cycle of these three control signals may be equal to the D / A conversion rate (1/60 seconds) used in the conventional motor control.

The three command signals (FCMD0, ZCMD0, TCMD0) fetched by the latches 61, 62, 63 at the falling timing of each control signal are time-division multiplexed and input to the adder 70 ( (A timing in the figure). Further, each position detection signal generated by each potentiometer P and amplified by the amplifier A is taken in as a digital signal by each A / D section 67, 68, 69 at the falling timing of each control signal. The digitized position detection signals (FTP0, ZPT0, TPT0) thus fetched are time-division multiplexed at the same timing as A timing and input to the adder 70 (B timing in the figure).

In the adder 70, these two timing signals A and B are added, but as shown in the figure, signals (FDR0, ZDR0, TDR) whose timings are slightly delayed are added.
0) is output (timing C in the figure). next,
The C timing signal is taken into the D / A sections 64, 65, 66 at the rising timing of each control signal and converted into an analog signal. For example, FDR0 is taken into the D / A section 64 at the falling timing of the focus control signal and output as an analog signal (timing D in the figure). Similarly, the zoom control signal causes Z / D0 to be taken into the D / A unit 65 (timing E in the figure), and the tracking control signal causes T / D0 to be taken in the D / A unit 66 (timing F in the figure). Then, the analog signals output from the respective D / A units 64, 65, 66 are amplified by the respective motor drive amplifiers, and motor drive control is performed.

As described above, since three different commands are time-division multiplexed at the digital signal level and used as the motor drive signal, common parts can be used and adjustment parts such as resistors in the analog circuit part can be reduced. . In addition, miniaturization is possible by modularizing the digital circuit portion. Further, in addition to these three commands, when another command is added to control the motor drive, the other commands only need to be time-division multiplexed, so that the number of circuit components can be slightly increased.

An overcurrent detection circuit for preventing an overcurrent from flowing in the analog signal (motor drive signal) output from each D / A section 65, 65, 66 is usually provided.
Like the overcurrent detection circuit shown in FIG. 14, a timer circuit is provided after the overcurrent determination, and a certain time or more (for example, 1 second)
The switch for cutting off the current may be activated when it is detected that the overcurrent continues. It should be noted that the timer circuit includes a buffer that stores the overcurrent determination result, a timer that starts counting for a fixed time when it is determined that the current is an overcurrent, and a result that the content of the buffer is determined to be an overcurrent when the timer counts In some cases, a flip-flop that outputs a switch control signal or a logical circuit such as AND and OR can be used.

[0072]

According to the present invention, since the reference heat source section is provided inside the optical system, it becomes possible to easily obtain the reference data used for sensitivity correction and the like in real time. Therefore, the work of acquiring the reference data before the observation becomes unnecessary. In addition, during normal observation, real-time sensitivity correction corresponding to the sensitivity change of the detector becomes possible. Further, according to the present invention, since the defective pixel correction is performed based on the reference data obtained from the reference heat source provided inside the optical system, it is not necessary to obtain the defective pixel correction data as in the prior art. Becomes Also, during normal observation,
It is possible to correct defective pixels in real time, and it is possible to appropriately deal with characteristic changes due to aging of the infrared detector.

Further, according to the present invention, a desired area of the infrared image to be photographed is designated as a frame, and the gain / level of the area is automatically adjusted. Can be displayed properly. Further, according to the present invention, since the control amount of the optical system is time-division multiplexed to adjust the position of the optical lens, the circuit of the optical system control section can be rationalized.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an infrared imaging device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of an arrangement of reference heat sources used in the present invention.

FIG. 3 is a configuration diagram of a reference data acquisition circuit according to an embodiment of the present invention.

FIG. 4 is an explanatory diagram of reference data acquisition timing in the embodiment of the present invention.

FIG. 5 is an explanatory diagram of a plurality of reference heat sources in the embodiment of the present invention.

FIG. 6 is a configuration diagram of a reference data acquisition circuit according to an embodiment of the present invention.

FIG. 7 is an explanatory diagram of reference data acquisition timings when a plurality of reference heat sources are used in the embodiment of the present invention.

FIG. 8 is an example of a circuit configuration diagram for controlling the temperature of the reference heat source of the present invention.

FIG. 9 is a circuit configuration diagram of a sensitivity correction unit in the embodiment of the present invention.

FIG. 10 is a circuit configuration diagram of a defective pixel correction unit in the embodiment of the present invention.

FIG. 11 is a circuit configuration diagram of an automatic gain / level adjustment unit in the embodiment of the present invention.

FIG. 12 is a circuit configuration diagram of an optical system controller in the embodiment of the present invention.

FIG. 13 is a timing chart of time division control in the embodiment of the present invention.

FIG. 14 is a configuration diagram of an overcurrent detection circuit according to an embodiment of the present invention.

FIG. 15 is a block diagram of a conventional device for acquiring reference data.

FIG. 16 is a configuration diagram of a conventional ROM manufacturing circuit for defective pixel correction.

FIG. 17 is a circuit configuration diagram of a conventional optical system controller.

[Explanation of symbols]

 101 Sensitivity Correction Section 102 Defective Pixel Correction Section 103 Automatic Gain / Level Adjustment Section 104 Optical System Control Section 105 Reference Heat Source 110 Detector 111 A / D Conversion Section 112 DSC Processing Section 113 D / A Conversion Section 114 Zoom Optical System 115 Lens 116 Zoom motor 117 Focus motor 118 Truckin motor

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsuya Kawashita 2-2-6 Jomi, Chuo-ku, Osaka City, Osaka Prefecture Fujitsu Kansai Digital Technology Stock Company In-house (72) Inventor Atsushi Yamaji Chuo-ku, Osaka City, Osaka Prefecture 2-26, Jomi Digital Kansai Digital Technology Stock Company, In-house (72) Inventor Kenichi Tokuda 2-26, Jomi Digital Technology Stock Company, Chuo-ku, Osaka, Osaka (72) Inventor Yukinoki Hideki 1015 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Prefecture, Fujitsu Limited (72) Inventor, Matsushi Hoshi Matsumoto, Takahara, Nakahara-ku, Kawasaki City, Kanagawa 1015, Fujitsu Limited (72) Inventor, Mikiyasu Okamoto Kawasaki, Kanagawa 1015 Kamiodanaka, Nakahara-ku, Fujitsu Limited

Claims (8)

[Claims] 1. An infrared imager having an optical system composed of a plurality of optical lenses, comprising: a reference heat source section arranged in the vicinity of an actual image forming surface inside the optical system and outside a field of view to be imaged; An infrared detection unit that detects an infrared ray emitted from an object and the reference heat source unit and outputs an electrical detection signal, and a reference data acquisition unit that obtains only a detection signal corresponding to the infrared ray emitted from the reference heat source unit An infrared imaging device comprising: 2. The infrared imaging device according to claim 1, wherein the reference heat source unit is composed of only one reference heat source plate that can be controlled to a predetermined temperature. 3. The infrared imaging device according to claim 1, wherein the reference heat source unit is composed of a plurality of reference heat source plates that can be controlled to different predetermined temperatures. 4. The infrared detection section is composed of a plurality of infrared sensors, and the detection signal of the observed object output by each infrared sensor is corrected by the reference detection signal acquired by the reference data acquisition section. The infrared imaging device according to claim 2 or 3, further comprising a sensitivity correction unit that operates. 5. The infrared detecting section is composed of a plurality of infrared sensors, and it is determined whether or not a detection signal corresponding to infrared rays emitted from the reference heat source section satisfies a predetermined defect determination condition,
The defective pixel determination unit for determining that the infrared sensor is a defective element when the detection signal output by a certain infrared sensor satisfies the defect determination condition is further provided. Infrared imager. 6. When the defective pixel determination unit determines that an infrared sensor of the plurality of infrared sensors is a defective pixel, a detection signal output by the infrared sensor is output in the vicinity of the infrared sensor. The infrared imaging device according to claim 5, further comprising a defective pixel correction unit that replaces a detection signal output by the infrared sensor. 7. An infrared imager having an optical system composed of a plurality of optical lenses, the infrared detector detecting infrared rays emitted from an observation object and outputting an electrical detection signal, and the infrared imager of the captured infrared image. A frame designating section that designates a desired video area, a designated frame signal obtaining section that obtains only the detection signal in the video area designated by the frame designating section, and a detection signal obtained by this designated frame signal obtaining section An infrared image device, comprising: an adjusting unit that automatically adjusts the gain and level of an image in the image area by using only the above. 8. An infrared imaging device having an optical system composed of a plurality of optical lenses, comprising an optical control unit for controlling zooming, focusing and tracking of an infrared video imaged by adjusting the position of the optical lens. The optical control unit is time-division multiplexed with an input unit for inputting control amounts of zoom, focus, and tracking, a time-division multiplexing unit for time-division multiplexing these input control amounts at a predetermined timing. An infrared imaging device comprising: a drive unit that changes a position of an optical lens by separately taking out a control amount at the same timing as the predetermined timing.