JP2012213130A - Infrared imaging apparatus and infrared temperature measuring apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an infrared imaging apparatus comprising common correction means adaptable to specifications of various image correction systems and detectors which can be applied to the infrared imaging apparatus.SOLUTION: In a product inspection of the infrared imaging apparatus, according to the specifications of the image correction systems and detectors to be applied to the infrared imaging apparatus, a combination of the luminance value of a taken image inputted pixel by pixel from the detectors to a signal processing circuit and an imaging luminance value outputted from the signal processing circuit is obtained as a lookup table value and stored in a lookup table. In operation of the infrared imaging apparatus, a luminance conversion part refers to the lookup table value stored in the lookup table and thereby performs luminance conversion corresponding to the specifications of the image correction systems and detectors to be applied to the infrared imaging apparatus.

Description

  The present invention relates to an infrared imaging device and an infrared temperature measuring device that measures the temperature of a subject imaged by the infrared imaging device.

In most cases, infrared imaging devices have sensitivity variations in the detector elements. Therefore, the infrared imaging device is equipped with an image correction circuit to uniformly correct the sensitivity variations for each pixel of the detector, and the output variations for each pixel are uniform. A captured image corrected to the above is provided.
An image correction circuit of an infrared imaging device reads a memory for storing sensitivity correction data for uniformly correcting sensitivity variations for each pixel, and sensitivity correction data stored in the memory, and for correcting the data uniformly. It is comprised from the correction circuit which performs a predetermined calculation (for example, refer patent document 1, 2).

An image correction circuit described in Patent Literature 1 has two reference temperatures at a high temperature and a low temperature, and stores sensitivity correction data obtained from two temperature sources at a predetermined high temperature and low temperature. And correcting the sensitivity of the imaging signal when an arbitrary target is imaged based on the sensitivity correction data stored in the memory. For example, the luminance level of the output of each pixel is corrected on the basis of an average value obtained by summing up and averaging the differences in luminance level between the high temperature and low temperature of each pixel.
In addition, the image correction circuit described in Patent Document 2 sets a plurality of target temperatures for imaging by the infrared imaging device and environmental temperatures for the infrared imaging device before the product of the infrared imaging device is shipped. Observe the signal luminance and the average signal luminance of one screen. Using this observation result, correction coefficient data that is converted so that the signal luminance for each pixel matches the average luminance value of one screen is calculated. A memory for storing the correction coefficient data is provided, and a predetermined correction calculation is performed to linearly approximate the average luminance value of one screen with respect to the signal luminance of the imaging signal of each pixel.

  On the other hand, in the infrared temperature measuring device, only the object to be measured is obtained unless the influence of the temperature of the infrared detector itself on the output of the infrared detector, in other words, the influence of the environmental temperature, is removed from the amount of infrared energy received by the detector element. Temperature measurement based on infrared radiation cannot be performed, and the influence of environmental temperature can cause measurement errors of the measurement object. For example, Patent Documents 3 and 4 can be cited as methods for removing the influence of environmental temperature.

The method for removing the influence of the environmental temperature described in Patent Document 3 is an arithmetic processing device that maintains a variation characteristic of the temperature to be measured specified by the combination of the environmental temperature detector and the detector, and calculates a difference amount from the reference temperature. This is a method of measuring temperature and measuring temperature. Since this method does not consider the influence of the sensitivity output variation for each pixel of the detector, there is a problem that accurate temperature measurement for each pixel of the detector cannot be expected, and a desired temperature measurement process is performed by the arithmetic processing unit. Therefore, there is a problem that the temperature measurement process takes time depending on the processing performance of the arithmetic processing unit.
On the other hand, the method for removing the influence of the environmental temperature described in Patent Document 4 is simply implemented using an analog circuit (amplifier, adder, or subtractor) instead of the arithmetic processing device in Patent Document 3. And In this method, most of the arithmetic processing devices are operated by an analog circuit without imposing a load, so that the problem of time-consuming temperature measurement processing can be avoided, but the processing itself is analog because of the analog processing. There was a problem that temperature measurement accuracy deteriorated due to the influence of noise and analog circuit performance.

Japanese Patent Laying-Open No. 2005-337772 (FIG. 1) JP 2010-216817 A (FIG. 1) JP 2001-004451 A (FIG. 1) JP 2006-053098 A (FIG. 1)

As described above, the image correction circuit of the conventional infrared imaging device reads out the correction data stored in the memory for storing the correction data for uniformly correcting the sensitivity variation for each pixel, and the correction data. It was composed of an arithmetic circuit for performing an arithmetic operation. For this reason, there is a problem in that it is necessary to prepare a corresponding memory and a correction circuit for storing correction data in accordance with various image correction calculation methods to be applied.
Further, when the image correction method of the infrared imaging device is changed, there is a problem that a correction circuit must be newly designed.
Also, depending on the specifications of the detector applied to the so-called infrared imaging device, such as the number of pixels constituting the infrared detector and the bit width of image data for performing image correction, the corresponding correction data storage memory and correction circuit There was a problem that it was necessary to prepare.

  Further, in the conventional infrared temperature measuring device, there is a problem that accurate temperature measurement for each pixel of the detector is difficult, and that the temperature measurement process takes time.

  The present invention has been made to solve such problems, and can correct variations in sensitivity of each pixel without designing a new image correction circuit for various image correction methods and detector specifications. It is an object to provide a simple infrared imaging device.

  An infrared imaging device according to the present invention is an infrared imaging device that performs imaging by detecting infrared rays, has a plurality of infrared detection pixels, detects infrared rays, and has a brightness value for each of the infrared detection pixels. An infrared detection unit that outputs a signal, and a lookup table (Lookup) that stores, for each of the infrared detection pixels, a luminance value after conversion for correcting an output variation for each luminance value output by the infrared detection pixel. Table) and a luminance conversion unit that refers to the lookup table and corrects output variations of luminance values output from the infrared detection pixels. The lookup table includes an address unit and a memory unit. Is assigned with the address of the infrared detection pixel and the luminance value of the infrared detection pixel as an address. The brightness value after the conversion is assigned in association with the memory part, and the brightness conversion part is associated with the brightness value output by the infrared detection pixel for each infrared detection pixel using the address of the lookup table. The converted luminance value is extracted from the memory unit, and the converted luminance value is output as a luminance value after output variation correction.

  ADVANTAGE OF THE INVENTION According to this invention, it can correct | amend for every pixel, without designing an image correction circuit newly with respect to the various image correction system applied to an infrared imaging device, and the specification of a detector, and an infrared imaging device The cost can be reduced.

1 is a block diagram illustrating a configuration of an infrared imaging device according to Embodiment 1. FIG. 3 is a diagram illustrating an example of a configuration of a lookup table of the infrared imaging device according to Embodiment 1. FIG. 6 is a diagram illustrating an example of assignment of stored data in a lookup table of the infrared imaging device according to Embodiment 1. FIG. 6 is a block diagram illustrating a configuration of an infrared imaging device according to Embodiment 2. FIG. 6 is a diagram illustrating an example of assignment of stored data in a lookup table of an infrared imaging device according to Embodiment 2. FIG. 6 is a block diagram illustrating a configuration of an infrared imaging device according to Embodiment 3. FIG. FIG. 10 is a diagram illustrating an example of allocation of stored data in a lookup table of an infrared imaging device according to Embodiment 3. It is a block diagram which shows the structure of the infrared temperature measuring apparatus which concerns on Embodiment 4. FIG. FIG. 10 is a diagram illustrating an example of storage data allocation in a lookup table according to Embodiment 4; It is a figure explaining the relationship between absolute temperature and spectral radiance at the time of fixing the wavelength in Planck's law. It is a figure explaining the concept of the temperature conversion of the infrared temperature measuring apparatus which concerns on Embodiment 5. FIG. FIG. 10 is a block diagram illustrating an infrared temperature measurement device according to a fifth embodiment. FIG. 20 is a diagram illustrating an example of storage data allocation in a lookup table according to Embodiment 5. It is a block diagram explaining the infrared temperature measuring apparatus which concerns on Embodiment 6. FIG. FIG. 20 is a diagram for explaining an example of allocation of stored data in a memory according to the sixth embodiment.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing a configuration of an infrared imaging device 1a according to the first embodiment.
The infrared imaging device 1 includes an infrared lens 2 that collects infrared rays from a target, an infrared detector 3 that detects the collected infrared rays and electrically converts it into a captured image signal (hereinafter simply referred to as a detector 3), and a detection It comprises a signal processing circuit 5a that uniformly corrects the output variation of each infrared detection pixel (hereinafter also simply referred to as a pixel) of the captured image signal output from the device 3 and outputs the corrected video signal to the outside. .

The signal processing circuit 5 includes a luminance conversion unit 6a and a look-up table (Lookup Table; hereinafter, also simply referred to as LUT) 7a.
In the LUT 7a, in order to uniformly correct the output variation for each pixel of the captured image signal output from the detector 3, signal processing is performed in advance on the luminance value of the captured image signal for each pixel input to the signal processing circuit 5a. The brightness value obtained by obtaining the brightness value of the captured image signal for each pixel output from the circuit 5 is stored.
The luminance conversion unit 6a (hereinafter, also referred to as a signal correction unit 6a) refers to the luminance value of the captured image signal input to the signal processing circuit 5a with reference to the luminance value stored in the LUT 7a. And output.

Next, the correction operation of the infrared imaging device 1a according to the first embodiment will be described.
Here, an operation for uniformly correcting the output variation for each pixel of the captured image signal output from the detector 3 will be described.

The LUT 7a is compatible with the specifications of various detectors, so that the address portion (memory address) corresponding to the bit width of the maximum captured image data that can be taken by the detector 3 and the imaging corresponding to the maximum bit width. It consists of image data and a memory unit (memory data) that stores the maximum total number of pixels. FIG. 2 shows an example of the configuration of the LUT 7.
The address portion (memory address) of the LUT 7a is assigned with the pixel address of the detector 3 and the captured image luminance value input to the signal processing circuit 5 with respect to the pixel at the pixel address.
Also, the luminance value of the captured image output from the signal processing circuit 5 is assigned to the memory unit (memory data) of the LUT 7 in correspondence with the luminance value of the input captured image for each pixel of the pixel address.

  As described above, the LUT 7 includes, for each pixel of the detector 3, a combination of the luminance value of the captured image input to the signal processing circuit 5 and the luminance value of the captured image output by the signal processing circuit 5 (hereinafter referred to as a lookup table value). Is stored).

  FIG. 3 is a diagram illustrating an example of allocation of storage data in the LUT 7. For example, the maximum bit width of the captured image data of the detector 3 is 12 bits, and the maximum total number of pixels of the detector 3 is 162144 (horizontal pixels 512, This is a storage area in the memory of the lookup data value for each pixel in the case of the vertical pixel 512). Depending on the image correction method applied by the infrared imaging device 1, it is necessary to store a predetermined type of data in addition to the lookup table value.

In the lookup table of FIG. 3, “reserved” indicates a reserved area for storing the maximum amount of this predetermined type of data setting. At this time, since the memory capacity is about 1100 Tbytes, the LUT 7 is configured by using a plurality of NAND ROMs (FLASHROMs) capable of storing a large amount of data, for example.
The lookup table value for each pixel stored in the LUT 7 is obtained by a predetermined calculation according to the image correction method applied by the infrared imaging device 1 at the inspection stage before product shipment of the infrared imaging device 1a, and is stored in the LUT 7a. .

Hereinafter, a method according to the image correction calculation method described in Patent Document 1 will be described as an example of a lookup table value calculation method.
First, difference temperature data when a high temperature and low temperature source is imaged for each pixel is calculated by the following calculation formula.

Here, l is the number of horizontal pixels of the detector 3, m is the number of vertical pixels of the detector 3 (in this case, the total number of pixels of the detector 3 is l * m), T1 is a high temperature side temperature, and T2 is a low temperature. Side temperature, ΔT is the difference temperature, and Sij (T1), Sij (T2), and Sij (ΔT) are the horizontal pixel position i (1 ≦ i ≦ l) and the vertical pixel position j (1 ≦ j ≦ m), respectively. High temperature data, low temperature data and differential temperature data.
Next, the average value S (ΔT) of the difference temperature data obtained by (Expression 1-11) to (Expression 1-1m) is determined by the following expression (Expression 2).

  Here, n is the total number of pixels. Temperature correction coefficients k (11) to k (lm) for each detection element from the difference temperature data obtained by (Equation 1-11) to (Equation 1-lm) and the average value of the difference temperature data obtained by (Equation 2). Is obtained by the following calculation formula.

  The temperature correction coefficients k (11) to k (lm) obtained by the above (Expression 3-11) to (Expression 3-lm) are subjected to sensitivity correction with respect to the imaging signal luminance: SIij input to the signal processing circuit 5. Output data: SOij is obtained.

In Expression (4-11), SI11 is the luminance value of the captured image signal input to the signal processing circuit 5 of the pixel 1, and SO11 is the luminance value of the captured image signal output from the signal processing circuit 5.
Here, b is the image data bit width of the detector 3, and the luminance values of the captured image signals input to the signal processing circuit 5 of the pixel 1 are sequentially set to 0, 1,..., 2 ^b −1. A lookup table value is obtained by calculating each SO11. Note that b, l, and m are determined by the specifications of the detector applied to the infrared imaging device 1.

In the same manner as described above, a lookup table value to be stored in the pixel 2 to pixel 1 × m area of the LUT 7a is obtained. For storing in the LUT 7a, the luminance value of the captured image signal input to the signal processing circuit 5 is output from the signal processing circuit 5 to the address portion (memory address) of the LUT 7a and the luminance value of the captured image signal input to the signal processing circuit 5. The brightness value of the captured image signal is stored in association with the memory address.
By the above procedure, the lookup table value obtained by calculation according to the image correction method and detector specifications applied to the infrared imaging device 1 is stored in the LUT 7a.

The luminance conversion unit 6a in the signal processing circuit 5a performs a count-up operation every time the captured image luminance data output from the detector 3 is input to the signal processing circuit 5a, and outputs the count value from the detector 3. It is detected as a pixel address of image brightness.
The output captured image brightness value at the memory address of the LUT 7a corresponding to the captured pixel brightness value of the pixel address of the detector 3 is read from the captured image brightness value of each pixel input to the brightness conversion unit 6a, and the input captured image brightness value is output. The brightness value of the captured image is converted.

As described above, the signal processing circuit 5a of the infrared imaging device according to the first embodiment includes the luminance conversion unit 6a and the LUT 7a, and the LUT 7a includes the luminance value of the captured image signal for each pixel input to the signal processing circuit 5a ( Corresponding to (input luminance value), the luminance value (output luminance value) of the captured image signal for each pixel output from the signal processing circuit 5a, which is obtained in advance, is stored.
The luminance conversion unit 6a refers to the LUT 7a with respect to the input luminance value for each pixel, and can directly acquire the corrected output luminance value without performing the calculation. The output variation for each pixel of the picked-up image signal output from the detector 3 according to the specifications of the correct detector and the image correction method can be corrected uniformly.

Embodiment 2. FIG.
When the temperature of the environment in which the infrared imaging device is used changes during operation, monitor the environment temperature and apply an image correction method that uniformly corrects output variations for each pixel, taking into account the effects of the temperature of the environment. This is desirable from the viewpoint of correction accuracy.
In the second embodiment, the temperature sensor 4 (environment) is compared to the first embodiment so as to correspond to an image correction method that monitors the temperature of the environment in which the infrared imaging device 1 is used and uniformly corrects output variations for each pixel. A temperature measuring unit) is added.

FIG. 4 is a block diagram showing the configuration of the infrared imaging device 1b according to the second embodiment.
In the data stored in the LUT 7b in the second embodiment, the reading value of the lens temperature in the temperature sensor 4 is further added to the LUT 7a in the first embodiment.

FIG. 5 is a diagram showing an example of allocation of stored data of the LUT 7b to the memory when the maximum movable range that can be read by the temperature sensor 4 is 0 to 2 ¹⁰ −1.

  Hereinafter, as an example of calculation of the lookup table value, a calculation method according to an image correction method that monitors the use environment temperature described in Patent Document 2 and uniformly corrects output variation for each pixel will be described.

Here, three known imaging temperature sources and lens temperatures are set to three known temperatures for each pixel using the face black body, and the luminance of the captured image signal input to the signal processing circuit 5 at that time and 1 Observe the screen average signal luminance.
Using the observed value, a correction coefficient in each pixel is obtained, a correction operation is performed to linearly approximate the average luminance value of one screen, and Xj is input to the signal processing circuit 5 in the pixel j. The lookup table value stored in the LUT 7b is calculated by associating the lens temperature signal input to the signal processing circuit 5 and the captured image signal luminance output from the signal processing circuit 5 in the pixel j with XCj (the following equation 5) , See formula (6).
Similarly to the first embodiment, the total number of pixels and the image data width stored in the LUT 7b are set according to the specifications of the detector 3 to which the infrared imaging device 1b is applied.

  When operating the infrared imaging device 1b, as in the first embodiment, the luminance conversion unit 6b of the signal processing circuit 5b is measured by a captured image luminance value for each pixel input to the luminance conversion unit 6b and a temperature sensor. The look-up table value stored in the LUT 7b is read from the lens temperature value. Then, the ambient temperature is monitored and converted to a brightness value of an output captured image that matches the image correction method for uniform correction and the specifications of the detector.

As described above, the infrared imaging device according to the second embodiment includes the temperature sensor 4 that monitors the use environment temperature. Further, data corresponding to the use environment temperature is allocated to the address part (memory address) of the LUT 7b, and the data is stored.
Since the luminance conversion unit 6 can directly obtain the corrected output luminance value without performing the calculation by referring to the lookup table value with respect to the input luminance value and the use environment temperature for each pixel. The output variation for each pixel of the captured image signal output from the detector 3 according to the specifications of the various detectors that the imaging apparatus 1 can take and the image correction method can be corrected uniformly.

Embodiment 3 FIG.
The detector 3 of the infrared imaging device may have a defective pixel in which a pixel to be referenced outputs an abnormal luminance value due to adhesion of foreign matters in the manufacturing process. In this case, an output failure occurs in the output of the pixel output from the detector 3, and as a result, the pixel is output as noise or image unevenness in the pixel of the video output.
In the third embodiment, even when the detector 3 has the defective pixel, the output variation for each pixel output from the infrared imaging device is uniformly corrected.

FIG. 6 is a block diagram showing the configuration of the infrared imaging device 1c according to the third embodiment, and defective pixel information is added to the LUT 7a or the LUT 7b in the signal processing circuit 5a or the signal processing circuit 5b in the first or second embodiment. Further, the luminance conversion unit 6a is configured by adding exception processing for the defective pixel address.
Defect information is stored for a pixel address having a defective pixel.

  In the data stored in the LUT 7c according to the third embodiment, defective pixel information is further added to the data according to the first or second embodiment. Then, in addition to the look-up table value in the first or second embodiment, defect information is stored for a pixel address having a defective pixel on the basis of the pixel address of the detector 3 detected by the luminance conversion unit 6c. To do.

  FIG. 7 is a diagram showing an example of defect information stored in the LUT 7c when the total number of pixels of the detector 3 is 262144 (horizontal pixel 512, vertical pixel 512).

  The luminance conversion unit 6a according to the third embodiment obtains the pixel address of the detector 3 detected by the luminance conversion unit 6a and the defective pixel information using the LUT 7c for each captured image data input for each pixel from the detector 3. Referring to this, when the pixel address of the detector 3 is equal to the pixel address with a defective pixel, it is determined that the input captured image data is captured image data with a defective pixel. Then, the luminance conversion unit 6a performs an exception process to replace sound image data that is not defective pixels at the pixel addresses before and after the defective pixel address in order to avoid the influence of the abnormal luminance of the pixel. Output as an image.

As described above, the infrared imaging apparatus according to Embodiment 3 has defective pixel information as data stored in the LUT 7.
Thus, even when there is a defective pixel in the detector 3, the output variation for each pixel output from the infrared imaging device can be uniformly corrected by performing an appropriate process.

Embodiment 4 FIG.
FIG. 8 is a block diagram illustrating a configuration of an infrared temperature measurement apparatus 100d according to the fourth embodiment.
The infrared temperature measuring device 100d includes an infrared lens 2 that collects infrared rays from a target, a detector 3 (infrared detector) that detects the collected infrared rays and electrically converts it into a captured image signal, and the environment of the infrared temperature measuring device 1. It is composed of a temperature sensor 4 for measuring temperature and a signal processing circuit 5d.
The signal processing circuit 5d corresponds to any detector specification and image correction method to which the infrared temperature measuring apparatus 1 can be applied, and removes both the influence of the output variation for each pixel of the detector 3 and the influence of the environmental temperature. . Specifically, the signal processing circuit 5d performs a luminance conversion unit 6d that performs luminance conversion so as to uniformly correct the output variation of each infrared detection pixel (hereinafter simply referred to as a pixel) of the captured image signal output from the detector 3. A lookup table 7d storing a lookup table value for luminance conversion used in the luminance conversion unit 6d, a temperature measurement unit 8d for converting the luminance value for each pixel after correction into a temperature corresponding to the temperature of the subject, And a temperature measurement memory 9d for storing temperature measurement coefficients.
Here, the luminance conversion unit 6d and the temperature measurement unit 8d use an FPGA (Field Programmable Gate Array) capable of synchronous processing with a high-speed clock without using an arithmetic processing unit.

The look-up table 7d has the same configuration as the look-up table described in the first embodiment, and the maximum possible value of the detector 3 so as to be compatible with the detector specifications applied by the infrared temperature measuring device 100d. The memory is configured to store the address depth of the memory address corresponding to the bit width of the captured image data, the captured image data corresponding to the maximum bit width, and the maximum total number of pixels.
FIG. 9 is a diagram illustrating a storage area of the luminance conversion lookup data value for each pixel in the memory. As an example, the maximum bit width of the captured image data of the detector 3 is 12 bits, the maximum total number of pixels of the detector 3 is 262144 (the number of horizontal pixels 512, the number of vertical pixels 512), and the maximum movable that the temperature sensor 4 can read. An example of the storage area when the range is, for example, 0 to 2 ¹⁰ −1 is shown. In this manner, the lookup table 7d stores combinations of captured image luminance values input to the luminance conversion unit 6d and captured image luminance values output from the luminance conversion unit 6d for each pixel. Since the memory capacity of the lookup table 7d is expected to be several thousand [Tbytes], the lookup table 7d is configured by using a plurality of NAND type FLASHROMs capable of storing a large amount of data.
Note that the brightness conversion lookup table value stored in the lookup table 7d is predetermined according to the detector output variation correction method applied by the infrared temperature measurement device 100d before the infrared temperature measurement device 100d is shipped from the factory. And is stored in the lookup table 7d.

  For example, as described in the second embodiment, the lookup table value is calculated according to an image correction method that monitors the use environment temperature described in Patent Document 2 and uniformly corrects output variation for each pixel. .

When operating the infrared temperature measuring apparatus 100d, the luminance converting unit 6d reads the captured image luminance value for each pixel input to the luminance converting unit 6d and the lens temperature value measured by the temperature sensor 4 from the lookup table reading destination. As the memory address, the luminance conversion lookup table value stored in the lookup table 7d is read out.
In this way, the luminance conversion unit 6d converts the input luminance signal into a luminance signal of an output captured image corresponding to the output variation correction method applied by the infrared temperature measurement device 100d and the specifications of the detector, and outputs the luminance signal. To do.

  Next, an operation in which the temperature measurement unit 8d measures the temperature corresponding to the temperature of the subject based on the luminance signal after luminance conversion output from the luminance conversion unit 6d will be described.

The temperature measurement memory 9d stores in advance the value of the coefficient of the temperature conversion formula obtained by the method described later when the infrared temperature measurement device 100d is shipped from the factory.
The temperature conversion from the luminance signal after the luminance conversion to the target temperature in the luminance converting unit 6d is equivalent to obtaining the temperature from the luminance in Planck's law shown in Equation 7.
Since the wavelength band of infrared rays received by the detector 3 is fixed as in the 3 to 5 μm band, if the wavelength band is fixed in Planck's law, the relationship between temperature and luminance is approximately linear as shown in FIG. 10, for example. Become a relationship.

Therefore, the temperature conversion from the luminance signal after the luminance conversion in the luminance converting unit 6d to the target temperature can be expressed in the line form shown in Equation 8.
The lens temperature is set in advance by three known imaging temperature sources using a black body and the installation of the infrared temperature measuring device 100d in the thermostatic bath and the temperature setting in the bath. The one-screen average signal luminance input to the luminance conversion unit 6d at that time is observed, and the temperature conversion coefficient in Equation 8 is calculated using those observed values.
Formula 9 shows a formula for calculating the temperature conversion coefficient in the temperature conversion formula. FIG. 11 shows the concept of the temperature conversion type of the infrared temperature measuring device.

  When the infrared temperature measuring device 100d is operated, the temperature measuring unit 8d uses the captured image luminance value output from the luminance converting unit 6d for each pixel and the temperature measuring coefficient read from the temperature measuring memory 9d, based on Equation 8. By performing the calculation, temperature information that is converted into a temperature corresponding to the temperature of the subject is output for each pixel.

As described above, the infrared temperature measurement device 100d according to the fourth embodiment uses the common signal processing circuit 5d, and the detector output variation correction method applied by the infrared temperature measurement device 1 and the specifications of the detector 3. Accordingly, both the influence of the output variation for each pixel of the detector 3 and the influence of the environmental temperature can be removed, and the detector output variation for each pixel can be uniformly corrected.
Furthermore, temperature measurement corresponding to the brightness value of the captured image can be performed for each pixel of the detector on the corrected captured image.

Embodiment 5 FIG.
In the detector 3, a defective pixel in which a pixel to be referenced outputs an abnormal luminance value may occur due to adhesion of foreign matters in the manufacturing process. In this case, an output failure occurs in the output of the pixel output by the detector 3, and as a result, noise and image unevenness are output in the pixel of the video output.
The infrared temperature measurement device 100e according to Embodiment 5 evenly corrects the output variation for each pixel output from the infrared temperature measurement device even when the detector 3 has the above defective pixel, and the temperature at the pixel is This is intended to be able to measure the above.

  FIG. 12 is a block diagram illustrating a configuration of an infrared temperature measurement apparatus 100e according to the fifth embodiment. In the fifth embodiment, defect coordinates are added to the lookup table 7 described in the fourth embodiment, and exception processing for the defective pixel address is added in the luminance conversion unit 6e.

In the lookup table 7e, before the infrared temperature measurement device 100e is shipped from the factory, in addition to the luminance conversion lookup table value in the fourth embodiment, the pixel address of the detector 3 detected by the luminance conversion unit 6e is used as a reference. Defect information is stored for a pixel address having a defective pixel.
FIG. 13 is an example of defect information stored in the defective pixel address storage unit when the total number of pixels of the detector 3 is 262144.
In the luminance conversion unit 6e, the pixel address of the detector 3 detected by the luminance conversion unit 6e and the look-up table 7e for each captured image data input for each pixel from the detector 3 in the fourth embodiment. The defective pixel information is referred to.
If the pixel address of the detector 3 is equal to the pixel address with the defective pixel, the input captured image data is assumed to be captured image data of the defective pixel and is not affected by the abnormal luminance of the pixel. Therefore, the brightness conversion unit 6e does not perform brightness conversion of the captured image shown in the fourth embodiment, performs exception processing to replace sound image data that is not defective pixels at pixel addresses before and after the defective pixel address, and outputs the captured image. Output as.
As a result, even when there is a defective pixel in the detector 3, the output variation for each pixel output from the infrared temperature measuring device 100e can be corrected uniformly, and the temperature can be measured at the pixel.

Embodiment 6 FIG.
When imaging a high temperature target, the amount of infrared rays emitted by the target increases, but on the other hand, the amount of infrared rays received and converted by an infrared detector is saturated. For this reason, the problem that the correct temperature of a high temperature target cannot be measured arises.
In order to solve this problem, the infrared temperature measurement apparatus 100f according to the sixth embodiment is mounted with the filter changer 10 including the optical attenuation filter on the front surface of the detector 3 in advance and images a high temperature target. The filter changer 10 is driven so that the optical attenuation filter is in front of the detector 3, and the amount of infrared rays received by the detector 3 is attenuated by the attenuation action of the optical attenuation filter.
As a result, the temperature range of the imaging target can be expanded and the temperature measurement corresponding to the temperature range of the imaging target can be performed without saturating the amount of infrared rays radiated by the high-temperature target and performing electrical conversion in the detector 3. It is characterized by doing effectively.
The number of optical attenuating filters may be mounted on the filter changer 10 as many as the required number that can be mounted on the filter changer 10 in correspondence with the temperature range of the imaging target.

FIG. 14 is a functional block diagram of an infrared temperature measuring apparatus 100f showing the sixth embodiment.
As compared with the infrared temperature measuring apparatus 100e of the fifth embodiment, a filter drive unit 11 and a filter changer 10 are added to the front surface of the detector 3 in the signal processing circuit 4, and an optical attenuation filter is added to the filter changer 10 in advance. This is an example in which a sheet is mounted.

Next, the operation will be described. In response to an external filter position command, the filter drive unit 11 transmits a filter position control signal to the filter changer 10. As a result, the filter changer 10 is set so that the position where the optical attenuation filter is located is the front surface of the detector 3. Driven.
In the temperature measurement memory 9f, before the infrared temperature measurement device 100f is shipped from the factory, in addition to the temperature measurement coefficient in the fourth or fifth embodiment, the temperature measurement when the optical attenuation filter is arranged on the front surface of the detector 3 is performed. Additional coefficients are stored. The data to be additionally stored is stored by dividing the address of the memory storage destination. An example of allocation of stored data in the memory is shown in FIG.

Next, a method for calculating the temperature measurement coefficient when the optical attenuation filter is arranged on the front surface of the detector 3 will be described.
Before the factory shipment of the infrared temperature measuring device 100f, the calculation method is the same as that in the case where the optical attenuation filter is not disposed on the front surface of the detector 3 (hereinafter, this state is referred to as a dummy filter to distinguish this state from the optical attenuation filter). An optical attenuation filter is disposed in front of the detector 3 in advance, and in that state, the infrared temperature measuring device 100f in the black body and the thermostat, the three known imaging temperature sources by the temperature setting, and the lens temperature are known. The one-screen average signal luminance input to the luminance conversion unit 6f at that time is observed, and the optical attenuation filter is arranged on the front surface of the detector 3 according to Equation 9 using the observed values. Calculate the hourly temperature conversion coefficient.

In the temperature measurement unit 8f, when the infrared temperature measurement device 100f is operated, the optical attenuation read out from the temperature measurement memory 9f in accordance with the captured image luminance value for each pixel output from the luminance conversion unit 6f and the filter position command from the outside. Using the filter temperature measurement coefficient or the dummy filter temperature measurement coefficient, the calculation based on Equation 8 is performed, so that each pixel is matched with the filter state arranged on the front surface of the detector 3, and the temperature of the subject is adjusted. Outputs temperature information to convert to the appropriate temperature.
As a result, even when a high temperature target is imaged and the target emits a large amount of infrared light, saturation of the amount of infrared light received and converted by the infrared detector can be prevented, and the correct temperature of the high temperature target can be measured. .

  As described above, at the time of high-temperature target imaging, the temperature range of the imaging target that can be measured can be expanded, and temperature measurement corresponding to the temperature range of the imaging target can be effectively performed.

1a to 1d Infrared imaging device, 2 Infrared lens, 3 Detector, 4 Temperature sensor, 5a to 5f Signal processing circuit, 6a to 6f Luminance conversion unit (signal correction unit), 7a to 7f Look-up table, 8d to 8f Temperature measurement Part, 9d-9f memory for temperature measurement, 10 filter, 11 filter drive part, 100d-100f Infrared temperature measuring device.

Claims (6)

An infrared imaging device that senses and captures infrared rays,
An infrared detection unit that has a plurality of infrared detection pixels, detects infrared rays, and outputs a captured image signal that is a luminance value for each of the infrared detection pixels;
For each of the infrared detection pixels, a lookup table (Lookup Table) in which converted luminance values for correcting output variations are stored for each of the luminance values output by the infrared detection pixels;
A luminance converter that refers to the lookup table and corrects output variations in luminance values output by the infrared detection pixels; and
With
The look-up table includes an address part and a memory part. The address part is assigned with an address of the infrared detection pixel and a luminance value of the infrared detection pixel as an address, and the memory part has an address of the infrared detection pixel. The brightness value after the conversion is assigned in association with the address part composed of the brightness value of the infrared detection pixel,
The luminance conversion unit extracts, from the memory unit, the converted luminance value associated with the luminance value output from the infrared detection pixel for each infrared detection pixel using the address of the lookup table, An infrared imaging apparatus that outputs a luminance value after conversion as a luminance value after output variation correction. It has a temperature sensor that measures the ambient temperature,
An environmental temperature is additionally assigned to the address portion, and the converted luminance value is associated with the address portion including the address of the infrared detection pixel, the luminance of the infrared detection pixel, and the environmental temperature in the memory portion. The infrared imaging device according to claim 1, wherein The look-up table includes defective pixel information associated with the address portion and indicating whether each of the infrared detection pixels is a defective pixel;
When the defective pixel information is information indicating a defective pixel, the luminance conversion unit has a luminance value of the infrared detection pixel indicated as a defect around the infrared detection pixel indicated as the defect and is not defective. The infrared imaging apparatus according to claim 1, wherein the infrared imaging device is repaired using a luminance value of the infrared detection pixel. An infrared imaging device that senses infrared rays from a target and performs imaging,
An infrared detection unit that has a plurality of infrared detection pixels, detects infrared rays, and outputs a captured image signal that is a luminance value for each of the infrared detection pixels;
For each of the infrared detection pixels, for each luminance value output from the infrared detection pixel, a lookup table (Lookup Table) in which converted luminance values for correcting output variations are stored, and the lookup table The brightness conversion unit that corrects the output variation of the brightness value output by the infrared detection pixel, the temperature measurement memory that stores the temperature measurement coefficient that converts the brightness value into the temperature value, and the temperature based on the brightness value A temperature measuring unit for measuring the signal processing circuit,
With
The look-up table includes an address part and a memory part. The address part is assigned with an address of the infrared detection pixel and a luminance value of the infrared detection pixel as an address, and the memory part has an address of the infrared detection pixel. The brightness value after the conversion is assigned in association with the address part composed of the brightness value of the infrared detection pixel,
The luminance conversion unit extracts, from the memory unit, the converted luminance value associated with the luminance value output from the infrared detection pixel for each infrared detection pixel using the address of the lookup table, Output the brightness value after conversion as the brightness value after output variation correction,
The temperature measuring unit extracts the temperature measurement coefficient from the temperature measurement memory, and measures the temperature of the target based on the temperature measurement coefficient and the converted luminance value. Temperature measuring device. The look-up table includes defective pixel information associated with the address portion and indicating whether each of the infrared detection pixels is a defective pixel;
When the defective pixel information is information indicating a defective pixel, the luminance conversion unit has a luminance value of the infrared detection pixel indicated as a defect around the infrared detection pixel indicated as the defect and is not defective. The infrared temperature measuring device according to claim 4, wherein the infrared temperature measuring device is repaired by using a luminance value of the infrared detection pixel. A filter changer for inserting an optical attenuation filter in front of the infrared detection unit, and a filter driving unit for driving the filter changer,
6. The infrared temperature measuring apparatus according to claim 4, wherein the temperature measuring unit measures the temperature of the target according to an attenuation amount of an optical attenuation filter inserted in front of the infrared detecting unit. .

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