The present disclosure relates to a temperature measuring device and a temperature measuring method.
A thermal image correcting device that is an example of a temperature measuring device and is described in Patent Literature 1 acquires a temperature distribution of an observation target from a thermal image of the observation target captured by a camera.
According to the above thermal image correcting device, using for the above camera a low-cost lens such as a lens whose cost of a material or number of lenses is reduced expands the above thermal image. As a result, there has been a problem that the accuracy of the temperature distribution of the observation target to be acquired deteriorates.
An object of the present disclosure is to provide a temperature measuring device and a temperature measuring method that improve accuracy of temperatures of measurement targets.
To solve the above problem, a temperature measuring device according to the present disclosure includes: processing circuitry: to irradiate with thermal infrared light a target whose temperature needs to be measured; to acquire a thermal infrared illumination image including an image of the target irradiated with the thermal infrared light; to acquire a thermal infrared image including the image of the target; to acquire a visible light image including the image of the target; to calculate an image expansion amount of the image of the target based on the image of the target in the acquired visible light image and the image of the target in the acquired thermal infrared illumination image; to add the calculated image expansion amount in the acquired thermal infrared image to luminance of the image of the target; and to measure a temperature of the target based on the image of the target to which the image expansion amount has been added.
The temperature measuring device according to the present disclosure can improve accuracy of temperatures of measurement targets.
Embodiments of a temperature measuring device according to the present disclosure will be described.
The temperature measuring device according to Embodiment 1 will be described.
As illustrated in
The IR image acquiring unit 1 corresponds to a “thermal infrared image acquiring unit” and a “thermal infrared illumination image acquiring unit”, the IR illuminating unit 2 corresponds to a “thermal infrared illumination unit”, the visible light image acquiring unit 3 corresponds to a “visible light image acquiring unit”, the processing unit 4 corresponds to a “calculating unit” and an “adding unit”, and the measuring unit 5 corresponds to a “measuring unit”.
In this regard, “IR” means InfraRed.
The following description assumes the followings for ease of description and understanding.
The IR image acquiring unit 1 acquires an IR image IRG of the persons JB1 and JB2 by receiving IR light IRK. The IR image acquiring unit 1 includes an IR camera (not illustrated) that has sensitivity that comes to a peak in, for example, a mid-infrared wavelength range (3 to 5 μm) and a far-infrared wavelength range (8 to 15 μm), and a wavelength selection device (e.g., a narrow band bandpass filter whose wavelength is 10 μm).
When acquiring an IR illumination image IRSG, the IR image acquiring unit 1 selectively receives IR illumination light IRSK using the above wavelength selection device, and thereby eliminates light other than the IR illumination light IRSK such as most of the IR light IRK that is reflected by the persons JB1 and JB2 and influenced by temperatures of the persons JB1 and JB2.
The IR illuminating unit 2 radiates the IR illumination light IRSK that is infrared light (e.g., above 10 μm) in a wavelength range for which the IR image acquiring unit 1 has the sensitivity. The IR illuminating unit 2 includes, for example, a halogen lamp, a mid-infrared fiber laser, and a quantum cascade laser.
The IR illuminating unit 2 irradiates the persons JB1 and JB2 with the IR illumination light IRSK, and the IR image acquiring unit 1 acquires the IR illumination image IRSG of the persons JB1 and JB2 by receiving the IR illumination light IRSK reflected by the persons JB1 and JB2.
The visible light image acquiring unit 3 acquires a visible light image KG of the persons JB1 and JB2. The visible light image acquiring unit 3 includes, for example, a visible camera that has sensitivity whose peak comes in a visible light range.
<Visible Light Image KG>
In a front image of the visible light image KG, the person JB1 is captured larger than the person JB2 as illustrated in
As for the intensity of visible light KK on a broken line part HS in the front image illustrated in
<IR Image IRG>
By contrast with the front image of the visible light image KG illustrated in
As for the intensity of the IR light IRK on the broken line part HS in the front image illustrated in
<IR Illumination Image IRSG>
Similar to the IR image IRG illustrated in
On the other hand, unlike the visible light image KG illustrated in
Pr∝P0×exp(−2αL)×R/L2 Equation (1)
In this regard, P0 represents power of IR illumination light radiated by the IR illuminating unit 2, α represents an attenuation coefficient, R represents reflectivities of the persons JB1 and JB2, and L represents distances (corresponding to above L1 and L2) to the persons JB1 and JB2.
P0 and α are known, and the reflectivities R of the persons JB1 and JB2 are mutually the same. Consequently, it is possible to obtain the distances L1 and L2 to the persons JB1 and JB2 according to the above equation (1).
The power P0 of the IR illumination light IRSK radiated by the IR illuminating unit 2 is set to such a magnitude that the IR illumination light IRSK can reach the IR image acquiring unit 1 after being reflected by the persons JB1 and JB2 taking an attenuation amount during propagation of the IR illumination light IRSK into account.
Instead of eliminating the IR light IRK using the wavelength selection device, then receiving the IR illumination light IRSK, and acquiring the IR illumination image IRSG in advance as described above, for example, the IR image acquiring unit 1 may receive the IR light IRK and the IR illumination light IRSK without using the wavelength selection device, acquire the IR illumination image IRSG, then calculate a difference between the IR illumination image IRSG and the IR image IRG, and thereby eliminate an influence of the IR light IRK later.
Back to
The processing unit 4 adds the image expansion amount ZHR to the images GZ1 and GZ2 of the persons JB1 and JB2 in the IR image IRG (illustrated in
The measuring unit 5 measures the temperatures of the persons JB1 and JB2 based on the images GZ1 and GZ2 of the persons JB1 and JB2 to which the image expansion amount ZHR has been added in the IR image IRG (illustrated in
The temperature measuring device TMD according to Embodiment 1 includes an input unit NY, a processor PC, an output unit SY, a memory MM, and a storage medium KB as illustrated in
The input unit NY includes, for example, a camera, a microphone, a keyboard, a mouse, and a touch panel. The processor PC is a well-known core of a computer that causes hardware to operate according to software. The output unit SY includes, for example, a liquid crystal monitor, a printer, and a touch panel. The memory MM includes, for example, a Dynamic Random Access Memory (DRAM) and a Static Random Access Memory (SRAM). The storage medium KB includes, for example, a Hard Disk Drive (HDD), a Solid State Drive (SSD), and a Read Only Memory (ROM).
The storage medium KB stores a program PR. The program PR is an instruction set that defines contents of processing that the processor PC needs to execute.
As for a relationship between the function and the configuration of the temperature measuring device TMD, the processor PC executes the program PR stored in the storage medium KB on the memory MM of the hardware, control operations of the input unit NY and the output unit SY as needed, and thereby implements the function of each unit from the IR image acquiring unit 1 to the measuring unit 5.
Step ST11: The IR image acquiring unit 1 (illustrated in
Step ST12: As illustrated in
Step ST13: As illustrated in
Step ST14: The processing unit 4 compares the IR illumination image IRSG (illustrated in
Step ST15: As illustrated in
The image expansion ZH (illustrated in
Step ST16: The processing unit 4 adds the luminance of the image expansion amount ZHR to luminances of the images GZ1 and GZ2 of the persons JB1 and JB2 on the IR image IRG, and thereby corrects the luminances of the images GZ1 and GZ2 of the persons JB1 and JB2.
Step ST17: The measuring unit 5 estimates the temperatures of the persons JB1 and JB2 based on the corrected luminances of the images GZ1 and GZ2 of the persons JB1 and JB2, that is, measures the temperatures of the persons JB1 and JB2.
As described above, the temperature measuring device TMD according to Embodiment 1 acquires the outer shapes GK1 and GK2 of the images GZ1 and GZ2 of the persons JB1 and JB2 from the visible light image KG, calculates the image expansion amount ZHR by comparing the IR illumination image IRSG with the visible light image KG, adds the image expansion amount ZHR to the images GZ1 and GZ2 of the persons JB1 and JB2 on the IR image IRG, and thereby corrects the luminances of the images GZ1 and GZ2 of the persons JB1 and JB2 on the IR image IRG. The temperatures of the persons JB1 and JB2 are measured based on the corrected luminances of the images GZ1 and GZ2 of the persons JB1 and JB2, that is, by taking the image expansion amount ZHR into account, so that it is possible to more accurately measure the temperatures of the persons JB1 and JB2 than the conventional technique that does not take the image expansion ZH into account at all.
The temperature measuring device TMD according to Embodiment 1 acquires the distances L1 and L2 to the persons JB1 to JB2. Consequently, in addition to the above effect, the temperature measuring device TMD according to Embodiment 1 can separate the images GZ1 and GZ2 of the persons JB1 and JB2 from each other using the above outer shapes GK1 and GK2 of the images GZ1 and GZ2 of the persons JB1 and JB2 and distances L1 and L2 to the persons JB1 and JB2.
A temperature measuring device according to Embodiment 2 will be described.
Similar to the temperature measuring device TMD according to Embodiment 1, as illustrated in
Functions of the IR image acquiring unit 1, the IR illuminating unit 2, the processing unit 4, and the measuring unit 5 according to Embodiment 2 are the same as the functions of the IR image acquiring unit 1, the IR illuminating unit 2, the processing unit 4, and the measuring unit 5 according to Embodiment 1.
The distance image acquiring unit 6 receives near infrared light NK, and thereby acquires an image (hereinafter, referred to as a “distance image DG”) showing distances L1 and L2 to persons JB1 and JB2.
The near infrared light illuminating unit 7 irradiates targets to measure such as the persons JB1 and JB2 with the near infrared light NK (whose wavelength range is 1 to 2 μm) to enable the distance image acquiring unit 6 to acquire the distance image DG.
The distance image acquiring unit 6 and the near infrared light illuminating unit 7 adopt, for example, Light Detection and Ranging (LiDAR). The distance image acquiring unit 6 and the near infrared light illuminating unit 7 may use, for example, visible light or ultraviolet light instead of the above near infrared light NK.
The distance image acquiring unit 6 corresponds to a “distance image acquiring unit”, the near infrared light illuminating unit 7 corresponds to a “distance measurement illuminating unit”, and the near infrared light NK corresponds to “distance measurement illumination light”.
The processing unit 4 corresponds to a “first acquiring unit” and a “second acquiring unit” in addition to the correspondence in Embodiment 1.
Similar to the visible light image KG (illustrated in 2A), as illustrated in
Similar to the IR illumination image IRSG (illustrated in
A configuration of the temperature measuring device TMD according to Embodiment 2 is the same as the configuration (illustrated in
Step ST21: Similar to step ST11 in Embodiment 1, the IR image acquiring unit 1 acquires the IR image IRG (illustrated in
Step ST22: Unlike step ST12 in Embodiment 1, as illustrated in
Step ST23: Unlike step ST13 in Embodiment 1, as illustrated in
Step ST24: Unlike step ST14 in Embodiment 1, the processing unit 4 compares the IR illumination image IRSG (illustrated in
Step ST25: Similar to step ST15 in Embodiment 1, the processing unit 4 calculates the image expansion amount ZHR.
Step ST26: Similar to step ST16 in Embodiment 1, the processing unit 4 corrects luminances of the images GZ1 and GZ2 of the persons JB1 and JB2.
Step ST27: Since power P0 of the IR illumination light IRSK, the distances L1 and L2, and an intensity Pr of the IR illumination image IRSG are known, the processing unit 4 calculates, that is, acquires reflectivities R1 and R2 of the persons JB1 and JB2, respectively, according to the above equation (1).
When transmittance is 0, the following equation (2) holds according to the Kirchhoff's Law.
Emissivity ε+Reflectivity R=1 Equation (2)
Hence, calculating the above reflectivities R1 and R2 of the persons JB1 and JB1 is the same as deriving emissivities ε1 and ε2 of the persons JB1 and JB2. The size of the IR light IRK received by the IR image acquiring unit 1 is proportional to the emissivities ε1 and ε2.
Step ST28: The measuring unit 5 estimates the temperatures of the persons JB1 and JB2 based on the corrected luminances of the images GZ1 and GZ2 of the persons JB1 and JB2 similar to step ST17 in Embodiment 1 by taking the emissivities ε1 and ε2 of the persons JB1 and JB2 into account unlike step ST17 in Embodiment 1, that is, measures the temperatures of the persons JB1 and JB2.
As described above, in the temperature measuring device TMD according to Embodiment 2, the distance image acquiring unit 6 acquires the distance image DG, and thereby acquires the reflectivities R1 and R2 of the persons JB1 and JB2, in other words, acquires the emissivities ε1 and ε2 of the persons JB1 and JB2. Thus, unlike Embodiment 1 where only the image expansion amount ZHR is taken into account, the temperatures of the persons JB1 and JB2 are measured by taking the emissivities ε1 and ε2 into account in addition to an image expansion amount ZHR. As a result, it is possible to more accurately measure the temperatures of the persons JB1 and JB2 than the temperature measuring device TMD according to Embodiment 1.
A temperature measuring device according to Embodiment 3 will be described.
As illustrated in
The functions of the IR image acquiring unit 1, the IR illuminating unit 2, the visible light image acquiring unit 3, the processing unit 4, the measuring unit 5, the distance image acquiring unit 6, and the near infrared light illuminating unit 7 according to Embodiment 3 are the same as the functions of the IR image acquiring unit 1, the IR illuminating unit 2, the visible light image acquiring unit 3, the processing unit 4, the measuring unit 5, the distance image acquiring unit 6, and the near infrared light illuminating unit 7 according to Embodiments 1 and 2.
The configuration of the temperature measuring device TMD according to Embodiment 3 is the same as the configuration (illustrated in
Steps ST31 to ST36: Similar to steps ST11 to ST16 in Embodiment 1 and steps ST21 to ST26 in Embodiment 2, the processing unit 4 acquires distances L1 and L2 to persons JB1 and JB2, outer shapes GK1 and GK2, an image expansion range ZHH, and an image expansion amount ZHR, and corrects luminances of images GZ1 and GZ2 of the persons JB1 and JB2.
Step ST37: Similar to step ST27 in Embodiment 2, the processing unit 4 calculates reflectivities R1 and R2 of the persons JB1 and JB1, that is, calculates emissivities ε1 and ε2 of the persons JB1 and JB2.
Step ST38: Similar to step ST17 in Embodiment 1 and step ST28 in Embodiment 2, the measuring unit 5 measures the temperatures of the persons JB1 and JB2.
As described above, the temperature measuring device TMD according to Embodiment 3 employs the configuration obtained by combining the temperature measuring device TMD according to Embodiment 1 and the temperature measuring device TMD according to Embodiment 2, and consequently can obtain the effect of the temperature measuring device TMD according to Embodiment 1 and the effect of the temperature measuring device TMD according to Embodiment 2.
The temperature measuring device TMD according to Embodiment 3 uses a distance image DG obtained by the distance image acquiring unit 6 and consequently can improve robustness against environment where temperatures are measured in addition to the above effects even under, for example, environment in which a flare, a ghost, and the like appear in a visible camera included in the visible light image acquiring unit 3, and even under dim environment.
The above-described embodiments may be combined without departing from the gist of the present disclosure, and the components in each embodiment may be deleted or changed, or other components may be added as appropriate.
The temperature measuring device according to the present disclosure can be used to measure, for example, temperatures of persons.
1: IR image acquiring unit, 2: IR illuminating unit, 3: visible light image acquiring unit, 4: processing unit, 5: measuring unit, 6: distance image acquiring unit, 7: near infrared light illuminating unit, DG: distance image, GK1: outer shape, GK2: outer shape, GZ1: image, GZ2: image, HS: broken line portion, IRG: IR image, IRG: IR image, IRK: IR light, IRSG: IR illumination image, IRSK: IR illumination light, JB1: person, JB2: person, KB: storage medium, KG: visible light image, KK: visible light, L1: distance, L2: distance, MM: memory, NK: near infrared light, NY: input unit, P0: power, PC: processor, Pr: intensity, PR: program, R: reflectivity, R1: reflectivity, R2: reflectivity, SY: output unit, TMD: temperature measuring device, ZH: image expansion, ZHH: image expansion range, ZHR: image expansion amount, ε1: emissivity, ε2: emissivity
This application is a Continuation of PCT International Application No. PCT/JP2021/021110 filed on Jun. 3, 2021, which is hereby expressly incorporated by reference into the present application.
Number | Date | Country | |
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Parent | PCT/JP2021/021110 | Jun 2021 | US |
Child | 18367554 | US |