WO2016185698A1 - Infrared imaging device - Google Patents

Abstract

[Problem] To correct, with a high degree of accuracy, values that contribute to infrared light radiated from an infrared imaging device body and infrared shielding body, from pixel signals output by an infrared sensor (3), when an effective region (A) in which infrared light is incident, and a reference region (B) upon which infrared light is not incident, are formed by an infrared shielding body, in an infrared imaging device (1). [Solution] This infrared imaging device (1) comprises: an imaging optical system (2) which images infrared light; an infrared sensor (3) which is positioned on the imaging plane (30) of the imaging optical system (2), has a detection region (31) in which a plurality of pixels that are thermocouple elements are arranged in an array, and a pixel signal based on the infrared light incident from the imaging optical system is output to each pixel; and an infrared shielding body (9) that is thermally bonded to the infrared imaging device body (12) and which is provided, within a detection region (31), with an effective region (A) upon which infrared light from the imaging optical system (2) is incident, and a reference region (B) upon which infrared light is not incident, by partially blocking infrared light between the imaging optical system (2) and the imaging plane (30).

Description

Infrared imaging device

The present invention relates to an imaging device that captures an infrared image, and more particularly to an infrared imaging device that corrects fluctuations in the value of a pixel signal output from an infrared sensor.

An infrared imaging device that captures an infrared image by detecting infrared rays emitted from a subject such as an object or a person with an infrared sensor is known. It is generally known that a subject whose temperature is higher than absolute zero emits infrared light, and that the higher the temperature of the subject, the more infrared light with a shorter wavelength, and the lower the temperature of the subject, the less infrared light with a longer wavelength. When a subject is imaged by an infrared imaging device, the captured image is displayed white at a high temperature and black at a low temperature. However, when a temperature change occurs in the vicinity of the infrared imaging device or the like, the detection signal detected by the infrared sensor changes due to the temperature change, and noise is generated in the captured subject image.

Therefore, in Patent Document 1, among detection regions in which pixels that are thermal infrared imaging elements are two-dimensionally arranged, pixels in a region where infrared rays are incident are effective pixels, and pixels in a region where infrared rays are not incident are reference pixels. An infrared imaging device is disclosed in which, when a temperature rise occurs in a region where a reference pixel is located, the fluctuation of the detection signal of the infrared sensor due to the temperature rise is suppressed by reducing the bias current flowing to the effective pixel. ing. In Patent Document 1, a ridge that covers the periphery of the detection region, that is, an infrared shielding body is provided inside the infrared sensor, and the infrared shielding body shields infrared light incident on the infrared sensor, thereby generating a region where no infrared light is incident. I am letting.

Japanese Patent Laid-Open No. 2004-245692

Generally, infrared rays emitted from a subject and infrared rays emitted from an infrared imaging device main body are incident on the infrared sensor. When the temperature of the infrared imaging device main body rises, the amount of infrared rays emitted from the infrared imaging device main body increases, so that the entire captured image becomes whitish. For example, when a high-temperature object or the like is placed on the right side of the infrared imaging apparatus main body, the captured infrared image is generally whitish on the right side. Therefore, it is desired to perform correction for offsetting fluctuations of infrared rays radiated from the infrared imaging device main body from pixel signals output from the infrared sensor.

In the infrared sensor described in Patent Document 1, the infrared shielding body 99 is provided inside the infrared sensor 3 as shown in FIG. When such an infrared shielding body 99 is used, it has been found that the following problems occur due to the incidence of infrared rays contributing to the infrared shielding body 99 on the reference pixels. FIG. 22 is a diagram illustrating an example of the difference in the amount of infrared depending on the presence or absence of the infrared shielding body 99 in the infrared sensor. In FIG. 21, an effective area where infrared rays from a subject are incident is indicated by A, and a reference area where infrared rays from a subject are not incident is indicated by B, among detection areas of the infrared sensor. When the infrared shield 99 is not provided, as shown in the left diagram of FIG. 22, the infrared rays radiated from the imaging device main body 12 are added to the infrared rays radiated from the subject (indicated by a solid line in the figure). As indicated by the dotted line in the figure, the amount of infrared radiation in the entire detection area of the infrared sensor 3 increases, so that the increased infrared radiation can be easily offset-corrected. However, when the infrared shielding body 99 is provided, the temperature of the infrared shielding body 99 does not increase immediately even if the temperature of the imaging apparatus body 12 rises. Infrared rays radiated from the infrared shielding body 99 having a lower temperature are added, and as shown in the right diagram of FIG. 22, the amount of infrared radiation that increases between the effective region A and the reference region B is different. It becomes difficult to accurately perform offset correction.

The present invention has been made in view of such a problem, and an infrared imaging device main body that enters an effective region and a reference region, respectively, when an effective region where infrared rays are incident and a reference region where no infrared rays are incident are formed by an infrared shield. In addition, the difference in the amount of infrared radiation from the infrared shielding body can be reduced, and the value that contributes to the infrared radiation emitted from the infrared imaging device main body and the infrared shielding body can be accurately corrected from the pixel signal output by the infrared sensor. An object of the present invention is to provide an infrared imaging device.

An infrared imaging device of the present invention includes an imaging optical system that forms an infrared image,
It has a detection region located on the imaging surface of the imaging optical system and in which a plurality of pixels that are thermoelectric conversion elements are arranged, and outputs a pixel signal based on infrared rays incident from the imaging optical system for each pixel. An infrared sensor;
By shielding a part of infrared rays between the imaging optical system and the imaging plane, the infrared region from the imaging optical system does not enter the effective region where the infrared rays from the imaging optical system enter the detection region. A reference region, and an infrared shielding body thermally coupled to the infrared imaging device main body.

Here, in the present invention, “infrared rays” includes all of near infrared rays, middle infrared rays, and far infrared rays.

In the present invention, the “effective region where infrared rays from the imaging optical system are incident” means a region where infrared rays incident from the imaging optical system reach in the detection region, and the connection between the detection region and the imaging optical system. It means an area where image areas overlap. The “reference region where the infrared rays from the imaging optical system are not incident” means a region where the infrared rays incident from the imaging optical system do not reach in the detection region, and means a region where the detection region and the imaging region do not overlap. The “reference area” means an area that is not an effective area among the detection areas.

Further, in the present invention, “thermally coupled” means that thermal energy is movably coupled in a direction in which there is no temperature difference between the infrared imaging device main body and the infrared shielding body.

In the infrared imaging device of the present invention, the infrared shielding body may be formed of a shielding plate extending from the infrared imaging device main body toward the inside of the infrared imaging device main body.

In the infrared imaging device of the present invention, the infrared shielding body includes a plate-like member having an opening, and a support member that supports the plate-like member by thermally coupling the plate-like member and the infrared imaging device main body. Good.

The infrared imaging device of the present invention includes a signal correction unit that performs correction processing on the value of the pixel signal output from the infrared sensor,
The signal correction unit corrects the value of the pixel signal of the effective pixel that is the pixel in the effective area by using the value of the pixel signal of the reference pixel that is the pixel in the reference area, thereby correcting the value of the pixel signal due to the temperature change. It is preferable to correct the variation.

In the infrared imaging device of the present invention, the signal correction unit may perform offset correction by subtracting the average value of the pixel signal value of the reference pixel from the value of the pixel signal of the effective pixel.

The infrared imaging device of the present invention is provided with two or more reference regions in the detection region,
The signal correction unit performs offset correction by subtracting the average value of the pixel signals of the reference pixels in at least one reference region of the two or more reference regions from the value of the pixel signal of the effective pixel. Also good.

The infrared imaging device of the present invention is provided with two or more reference regions in the detection region,
The signal correction unit calculates the average value of the pixel signals of the reference pixels in at least two reference areas among the two or more reference areas, and uses the calculated at least two average values to obtain the pixel signal of the effective pixel Shading correction may be performed on the value of.

In the present invention, “shading correction” refers to non-uniformity of incident infrared rays generated on the imaging surface of a two-dimensional infrared detection element such as a reduction in the amount of infrared rays at the periphery of an image circle caused by the imaging optical system, or a circuit board Means a correction for reducing non-uniformity of infrared rays caused by non-uniformity of infrared rays generated from the circuit board and non-uniformity of external heat from the lens, the main body of the infrared imaging device, and the like.

In the infrared imaging device of the present invention, the reference area may be provided at the upper and lower ends of the detection area.

In the infrared imaging device of the present invention, the reference area may be provided at the left and right ends of the detection area.

The infrared imaging device of the present invention is provided with a frame-shaped reference region in which a plurality of reference pixels are arranged at an edge in a detection region, and the frame-shaped reference region is divided into a plurality of regions.
The signal correction unit calculates the average value of the pixel signal values of the reference pixels located in the plurality of regions for each of the plurality of regions, and uses the calculated average value to calculate the pixel signal value of the effective pixel. On the other hand, shading correction may be performed.

The infrared imaging device of the present invention is provided with at least one temperature sensor in the infrared imaging device body,
The signal correction unit may perform offset correction by calculating a value corresponding to the value of the output signal from the temperature sensor to the value of the pixel signal of the effective pixel.

Here, in the present invention, the “value according to the value of the output signal from the temperature sensor” is a value set in advance for each type of infrared imaging device. For example, for each type of infrared imaging device, A table corresponding to the value of the output signal is created in advance, and a value based on this table can be used.

In the infrared imaging device of the present invention, the temperature sensor can be provided inside the infrared imaging device body.

In the infrared imaging device of the present invention, the temperature sensor can be provided on the infrared shielding body.

In the infrared imaging device of the present invention, it is preferable to provide a temperature sensor at a position facing the imaging optical system.

According to the infrared imaging device of the present invention, an effective region in which infrared rays from the imaging optical system enter the detection region by shielding a part of infrared rays between the imaging optical system and the imaging plane. Since the infrared imaging device main body and the infrared shielding body that is thermally coupled are provided to provide a reference region where infrared rays from the imaging optical system are not incident, the temperature difference between the infrared imaging device main body and the infrared shielding body is reduced. Therefore, the difference between the amount of infrared rays emitted from the infrared imaging device main body and the amount of radiation emitted from the infrared shielding body can be reduced. As a result, the difference in the amount of infrared radiation from the infrared imaging device main body and the infrared shielding body incident on the effective area and the reference area can be reduced, so that the difference in the correction amount to be offset between the effective area and the reference area is small. It becomes small and can correct | amend the value which contributes to the infrared rays radiated | emitted from an infrared imaging device main body and an infrared shielding body from the pixel signal which an infrared sensor outputs accurately.

1 is a schematic cross-sectional view illustrating a configuration of an infrared imaging device according to an embodiment of the present invention. 1 is a schematic block diagram illustrating a configuration of an infrared imaging device according to an embodiment of the present invention. The figure which shows an example of the infrared shielding body which shields infrared rays (the 1) The figure which shows an example of the infrared shielding body which shields infrared rays (the 2) The figure which shows an example of the infrared shielding body which shields infrared rays (the 3) Flowchart of a series of processes of the infrared imaging device of the present embodiment Flowchart of the first correction process of the signal correction unit Flowchart of second correction process of signal correction unit The figure explaining the correction method when a reference field is frame shape The figure explaining the calculation method of the correction value of the shading correction when a reference area is frame shape The figure which shows an example of the correction value of shading correction when a reference area is frame shape Schematic sectional drawing explaining the structure of the infrared imaging device which concerns on the 2nd Embodiment of this invention. Flowchart of third correction process of signal correction unit The figure which shows the relationship between the value of the output signal from the temperature sensor and the calculated value according to this value Flowchart of fourth correction process of signal correction unit Schematic sectional drawing explaining the structure of the infrared imaging device which concerns on the 3rd Embodiment of this invention. Schematic sectional drawing explaining the structure of the infrared imaging device which concerns on the 4th Embodiment of this invention FIG. 1 is a diagram showing an example of an infrared shielding method by masking the back of a lens (part 1). Figure 2 shows an example of infrared shielding method by masking the back of the lens FIG. 3 is a diagram showing an example of an infrared shielding method by masking the back of the lens (part 3). Schematic cross-sectional view illustrating the configuration of a conventional infrared imaging device The figure explaining the difference in the amount of infrared rays by the presence or absence of a shield in the infrared imaging device of FIG.

Hereinafter, an embodiment of an infrared imaging device according to the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic cross-sectional view illustrating the configuration of an infrared imaging device according to an embodiment of the present invention, and FIG. 2 is a schematic block diagram illustrating the configuration of an infrared imaging device 1 according to an embodiment of the present invention. . As shown in FIG. 1, the infrared imaging device 1 according to the present embodiment is installed in an infrared imaging device main body 12 including a first main body portion 10 and a second main body portion 11, and the first main body portion 10. An imaging optical system 2 capable of imaging infrared rays emitted from a subject on the imaging plane 30 and a second main body 11, located on the imaging plane 30 of the imaging optical system 2, An infrared sensor 3 having a detection region 31 in which a plurality of pixels as conversion elements are arranged and outputting pixel signals based on infrared rays incident from the imaging optical system 2 is provided for each pixel.

The infrared imaging device body 12 is made of a metal material such as aluminum or stainless steel or a resin material such as plastic, but is preferably formed of a material having a higher thermal conductivity than aluminum or stainless steel. The imaging device body 12 is made of copper. The internal structure of the infrared imaging device body 12 will be described later in detail.

The imaging optical system 2 is a lens group composed of one or more lenses. The lenses are held by a holding frame, and the holding frame is fixed to the first main body 10. In the present embodiment, the imaging optical system 2 is described as a fixed focus optical system, but the present invention is not limited to this, and may be a variable focus optical system.

As shown in FIG. 1, the infrared sensor 3 is installed so that the region C of the detection region 31 is located in the imaging region of the imaging optical system 2, that is, the region D of the image circle. The object image that is driven by the unit and imaged on the detection area 31 is captured as an infrared image, converted into a pixel signal, and output. The infrared sensor 3 outputs a pixel signal by sequentially transferring charges accumulated in each pixel and converting them into an electrical signal.

Here, what is characteristic in the present invention is that, as shown in FIG. 1, a part of infrared rays is shielded between the imaging optical system 2 and the imaging surface 30 and is thermally coupled to the infrared imaging device main body 12. The infrared shielding body 9 is provided. The infrared shield 9 is thermally coupled to the infrared imaging device body 12 and after a certain time has elapsed, the maximum temperature difference between the infrared shielding body 9 and the infrared imaging device body 12 is within ± 1 degree. The shield plate extends from the inner wall surface of the infrared imaging device main body 12 toward the optical axis 0. In this embodiment, the infrared shielding body 9 is made of copper. In this embodiment, the infrared shielding body 9 is made of copper. However, the present invention is not limited to this, and the material for forming the infrared shielding body 9 is the size of the infrared imaging device main body 12 and the like. As appropriate. The infrared shielding body 9 is preferably formed of, for example, a material having a thermal conductivity of aluminum or higher, that is, a material having a thermal conductivity of 236 W / mk or higher.

The infrared imaging device main body 12 and the infrared shielding body 9 are integrally coupled so that thermal energy can move in a direction in which there is no temperature difference. That is, when the temperature around the infrared imaging device body 12 rises and the temperature of the infrared imaging device body 12 rises, the temperature of the infrared shielding body 9 is reduced so that there is no temperature difference between the infrared imaging device body 12 and the infrared shielding body 9. The temperature will also rise.

As shown in FIG. 1, the infrared shielding body 9 shields a part of infrared rays incident from the imaging optical system 2 and forms a reference region B that is a region where infrared rays are not incident in the region C of the detection region 31. To do. Of the region C of the detection region 31, the region where the infrared rays incident from the imaging optical system 2 reach, that is, the region where the region C of the detection region 31 and the imaging region of the imaging optical system 2 overlap each other is the effective region A. A region where the infrared rays incident from the system 2 do not reach, that is, a region where the imaging region of the imaging optical system 2 does not overlap with the region C of the detection region 31 is defined as a reference region B.

Here, FIGS. 3 to 4 show examples of the infrared shielding body 9 that shields infrared rays. 3 to 4 are schematic diagrams for explaining the shielding of infrared rays by the infrared shielding body 9, and the size of each part is different from the actual one. When the infrared shielding body 9 is constituted by a shielding plate extending from the upper wall inner surface and the lower wall inner surface of the infrared imaging device main body 12 toward the optical axis 0, as shown in the upper diagram of FIG. The infrared rays incident from the imaging optical system 2 are shielded at the upper and lower end portions of the region C, and the reference region B1 is provided at each of the upper and lower end portions of the region C of the detection region 31 as shown in the lower diagram of FIG. , B2, and an effective area A is formed between the areas excluding the reference areas B1, B2, that is, the reference areas B1, B2.

On the other hand, when the infrared shielding body 9 is constituted by a shielding plate extending from the left wall inner surface and the right wall inner surface of the infrared imaging device main body 12 toward the optical axis 0, as shown in the upper diagram of FIG. Infrared rays incident from the imaging optical system 2 are shielded at the left and right ends of the region C of the area 31, and as shown in the lower diagram of FIG. Regions B3 and B4 are formed, and an effective region A is formed between the regions other than the reference regions B3 and B4, that is, between the reference regions B3 and B4.

Further, when the infrared shielding body 9 is constituted by a shielding plate extending toward the optical axis 0 from the upper wall inner surface, the lower wall inner surface, the left wall inner surface and the right wall inner surface of the infrared imaging device main body 12, that is, the infrared shielding body 9 is In the case of a plate member having an opening 9c in the center, as shown in the upper diagram of FIG. 5, the upper and lower ends and the left and right ends of the region C of the detection region 31 are separated from the imaging optical system 2. As shown in the lower diagram of FIG. 5, a frame-like reference region B is formed around the region C of the detection region 31 and is surrounded by the region excluding the reference region B, that is, the reference region B. An effective area A is formed in the center area.

The effective pixels in the effective area A and the reference pixels in the reference area B are infrared detection elements (infrared detectors) capable of detecting infrared rays (wavelength 0.7 μm to 1 mm), and particularly far infrared rays (wavelength 8 μm). Infrared detecting element capable of detecting (˜15 μm). For example, a microbolometer-type or SOI (Silicon-on-Insulator) diode-type infrared detection element can be used as the infrared detection element used as the effective pixel and the reference pixel. Further, in each embodiment of the present invention described below, the same structure is used not by a method of changing the presence or absence of the detection region 31 for detecting infrared rays or the structure of the detection region 31, but by a method of changing the presence or absence of incidence of infrared rays. Is used as an effective pixel with infrared incidence or a reference pixel without infrared incidence.

Next, the configuration of the infrared imaging device 1 will be described. As shown in FIG. 2, the infrared imaging device 1 includes the imaging optical system 2, the infrared sensor 3, an analog signal processing unit 4 that performs various analog signal processing such as amplifying an output signal from the infrared sensor 3, and the like. A / D conversion (Analog-to-Digital conversion) unit 5 for converting the analog image signal processed by the analog signal processing unit 4 into digital image data, and the digital image data converted by the A / D conversion unit 5 A digital signal processing unit 6 that performs various signal processing, a storage unit 7 that stores information associated with various digital signal processing, and an output that outputs an infrared image subjected to the digital signal to the storage unit 7 or a display unit (not shown). Part 8.

The storage unit 7 stores various types of information used in the digital signal processing unit 6, infrared images subjected to various digital signal processing, and the like as necessary, and a volatile memory such as a DRAM (Dynamic Random Access Memory). A non-volatile memory such as a flash memory is included. In the present embodiment, the storage unit 7 is provided separately from the digital signal processing unit 6, but the present invention is not limited to this, and the storage unit 7 is provided in the digital signal processing unit 6. Also good.

The output unit 8 outputs an infrared image subjected to various digital signal processing to the storage unit 7, a display unit (not shown), or a storage unit outside the apparatus by wireless or wired communication.

The digital signal processing unit 6 includes a signal correction unit 61 that performs correction processing on the value of the pixel signal output from the infrared sensor 3. Normally, when the temperature of the infrared imaging device main body 12 or the infrared shielding body 9 rises, the amount of infrared radiation emitted from the infrared imaging device main body 12 or the infrared shielding body 9 increases, so that the entire captured infrared image becomes whitish. End up. Therefore, the signal correction unit 61 of the present embodiment performs a correction to offset the value that contributes to the infrared rays radiated from the infrared imaging device main body 12 and the infrared shielding body 9 from the pixel signal output from the infrared sensor 3. The value of the pixel signal of the reference pixel that is the pixel in B is used to correct the value of the pixel signal of the effective pixel that is the pixel in the effective area A.

Here, a correction method by the signal correction unit 61 will be described with reference to a flowchart. FIG. 6 shows a flowchart of a series of processes of the infrared imaging apparatus 1 of the present embodiment.

As shown in FIG. 6, the infrared imaging device 1 of the present embodiment first images a subject (S1), and the infrared sensor 3 analogally outputs pixel signals based on infrared rays incident from the imaging optical system 2 for each pixel. Output to the signal processing unit 4, the analog signal processing unit 4 performs various analog signal processing such as amplifying the detection signal from the infrared sensor 3, and the A / D conversion unit 5 converts the processed analog image signal into digital image data. The digital signal processing unit 6 performs various signal processing on the digital image data converted by the A / D conversion unit 5, and stores the image data subjected to the various signal processing in the storage unit 7 (S2). ).

Next, the signal correction unit 61 reads the image data stored in the storage unit 7 and performs a correction process on the image data (S3). Here, the first correction processing by the signal correction unit 61 will be described in detail. FIG. 7 is a flowchart of the first correction process of the signal correction unit 61 of this embodiment.

The signal correction unit 61 calculates an average value of pixel signal values of reference pixels that are pixels in the reference region B (S11). As shown in FIG. 3, when the reference area B is provided at the upper and lower ends of the detection area C, the reference pixels in the reference area B1 at the upper end and the reference pixels in the reference area B2 at the lower end are displayed. An average value M of the values of both pixel signals is calculated. If the number of reference pixels in the reference region B1 at the upper end is i and the number of reference pixels in the reference region B2 at the lower end is j, the average value M can be calculated by the following equation (1).
M = (B1 ₁ + B1 ₂ +,..., + B1 _i + B2 ₁ + B2 ₂ +,... + B2 _j ) / (i + j) (1)
Here, B1 _1, ..., B1 _i indicate the value of the pixel signal of each reference pixel in the reference area B1, and B2 _1, ... B2 _j indicate the value of the pixel signal of each reference pixel in the reference area B2.

In addition, as a calculation method of the average value, after adding all the pixel signal values of the reference pixels in both the reference area B1 and the reference area B2 as in the above formula (1), the average value may be divided by the number of pixels. Then, an average value may be calculated for each of the reference regions B1 and B2, and a value obtained by adding the two calculated average values and dividing by two may be used as the average value. That is, the average value M may be calculated by the following formula (2).
M = ((B1 ₁ + B1 ₂ +,..., + B1 _i ) / i + (B2 ₁ + B2 ₂ +,..., + B2 _j ) / j) / 2 (2)

As shown in FIG. 4, when the reference area B is provided at the left and right ends of the detection area C, as in the case where the reference area B is provided at the upper and lower ends of the detection area C, An average value M of pixel signal values of both the reference pixel in the reference region B3 at the left end and the reference pixel in the reference region B4 at the right end is calculated. If the number of reference pixels in the left end reference area B3 is i and the number of reference pixels in the right end reference area B4 is j, the average value M can be calculated by the following equation (3).
M = (B3 ₁ + B3 ₂ +,..., + B3 _i + B4 ₁ + B4 ₂ +,... + B4 _j ) / (i + j) (3)
Here, B3 _1, ..., B3 _i indicate the pixel signal value of each reference pixel in the reference area B3, and B4 _1, ... B4 _j indicate the value of the pixel signal of each reference pixel in the reference area B4.

Further, when the reference area B is provided in a frame shape at the edge of the detection area C as shown in FIG. 5, the average value of the pixel signal values of the reference pixels in the frame-shaped reference area B is calculated. calculate. When the number of reference pixels in the reference region B is i, the average value M can be calculated by the following equation (4).
M = (B ₁ + B ₂ +,... + B _i ) / i (4)
Here, B _1, ... B _i indicate pixel signal values of the respective reference pixels in the reference region B.

Then, the signal correction unit 61 subtracts the value of the calculated average value M from each of the pixel signal values of the effective pixels in the effective region A to offset the value of the image signal, as shown in FIG. Correction is performed (S12).

Next, as shown in FIG. 6, the signal correction unit 61 stores the value of the pixel signal subjected to the correction process in the storage unit 7 (S4). The image data stored in the storage unit 7 is appropriately output by the output unit 8 to an external storage unit or a display unit (not shown). The corrected image data may be appropriately subjected to other necessary correction processing by the digital signal processing unit 6 of the infrared imaging device 1.

As described above, in the infrared imaging device 1 of the present embodiment, an image is formed in the region C of the detection region 31 by shielding a part of infrared rays between the imaging optical system 2 and the imaging surface 30. Since the infrared shielding body 9 is provided to provide the effective area A in which infrared rays from the optical system 2 are incident and the reference area B in which infrared rays from the imaging optical system 2 are not incident, the effective area A emits infrared radiation from the subject. The reference area B can capture only infrared radiation from the infrared imaging device main body 12 and the infrared shielding body 9 at the same timing as capturing. Therefore, the average value M calculated above is a value that contributes to infrared radiation from the infrared imaging device main body 12 and the infrared shielding body 9.

In the conventional infrared imaging device 100 shown in FIG. 21, even if the temperature of the imaging device main body 12 rises, the temperature of the infrared shield 99 does not rise immediately. Infrared rays emitted from the infrared shielding member 99 having a low temperature are added. Accordingly, the amount of incident infrared rays differs between the effective area A and the reference area B, and the correction amount to be offset differs between the effective area A and the reference area B. Therefore, the pixel signal of the effective pixel in the effective area A In the offset correction in which the average value M is subtracted from each of the values, it is difficult to perform correction with high accuracy.

However, in the infrared imaging device 1 of the present embodiment, the infrared imaging device main body 12 and the infrared shielding body 9 are thermally coupled, so that the temperature difference between the infrared imaging device main body 12 and the infrared shielding body 9 is reduced. The difference between the amount of infrared rays emitted from the infrared imaging device main body 12 and the amount of radiation emitted from the infrared shielding body 9 can be reduced. As a result, the difference in the amount of infrared radiation from the infrared imaging device main body 12 and the infrared shielding body 9 incident on the effective area A and the reference area B can be reduced, so that the effective area A and the reference area B are offset. The difference in power correction amount becomes smaller. Therefore, by performing offset correction that subtracts the value of the average value M from each of the pixel signal values of the effective pixels in the effective area A, the infrared imaging device main body 12 and the infrared shielding body 9 from the pixel signal output from the infrared sensor 3. Thus, it is possible to accurately perform correction for offsetting a value that contributes to infrared rays emitted from.

When performing offset correction using the average value M of the pixel signals of both the reference pixel in the reference region B1 at the upper end and the reference pixel in the reference region B2 at the lower end as shown in FIG. The influence of the temperature difference that occurs in the vertical direction of the infrared imaging device main body 12 can be reduced. In addition, when the offset correction is performed using the average value M of the pixel signals of both the reference pixel in the reference region B3 at the left end and the reference pixel in the reference region B4 at the right end as shown in FIG. The influence of the temperature difference that occurs in the left-right direction of the imaging device body 12 can be reduced. Further, when the offset correction is performed using the average value M of the pixel signal values of the reference pixels in the frame-like reference region B as shown in FIG. 5, the influence of the temperature difference generated around the infrared imaging device main body 12. Can be reduced.

In this embodiment, the average values of the pixel signals of the reference pixels in the reference regions B1 and B2 at the upper and lower end portions in FIG. 3 and the reference regions B3 and B4 at the left and right end portions in FIG. Although the present invention is used, the present invention is not limited to this. For example, in FIG. 3, the average value of the pixel signal values of the reference pixels only in the reference region B1 at the upper end may be used, or the reference region at the lower end. You may use the average value of the pixel signal value of the reference pixel of only B2. In FIG. 4, the average value of the pixel signals of the reference pixels only in the reference region B3 at the left end may be used, or the average value of the pixel signals of the reference pixels in the reference region B4 at the right end is used. It may be changed as appropriate.

Next, the second correction processing by the signal correction unit 61 of this embodiment will be described in detail. Here, FIG. 8 is a flowchart of the correction process of the second embodiment of the signal correction unit 61 of the present embodiment, FIG. 9 is a diagram for explaining a correction method when the reference area is frame-shaped, and FIG. FIG. 11 is a diagram illustrating a method for calculating a correction value for shading correction when the frame is in a frame shape, and FIG. 11 is a diagram illustrating an example of a correction value for shading correction when the reference region is frame-shaped.

As shown in FIG. 8, the signal correction unit 61 first calculates an average value of pixel signal values of reference pixels that are pixels in the reference region B (S21). As shown in FIG. 3, when the reference area B is provided at the upper and lower ends of the detection area C, the average value M1 and the lower end of the pixel signal values of the reference pixels in the reference area B1 at the upper end An average value M2 of the pixel signal values of the reference pixels in the reference region B2 of the part is calculated. If the number of reference pixels in the reference region B1 at the upper end is i and the number of reference pixels in the reference region B2 at the lower end is j, the average values M1 and M2 can be calculated by the following equations (5) and (6), respectively. .
M1 = (B1 ₁ + B1 ₂ +,... + B1 _i ) / i (5)
M2 = (B2 ₁ + B2 ₂ +,... + B2 _j ) / j (6)
Here, B1 _1, ..., B1 _i indicate the value of the pixel signal of each reference pixel in the reference area B1, and B2 _1, ... B2 _j indicate the value of the pixel signal of each reference pixel in the reference area B2.

As shown in FIG. 4, when the reference area B is provided at the left and right ends of the detection area C, as in the case where the reference area B is provided at the upper and lower ends of the detection area C, An average value M3 of pixel signal values of the reference pixels in the reference region B3 at the left end portion and an average value M4 of pixel signal values of the reference pixels in the reference region B4 at the right end portion are calculated. If the number of reference pixels in the reference region B3 at the left end is i and the number of reference pixels in the reference region B4 at the right end is j, the average values M3 and M4 can be calculated by the following equations (7) and (8).
M3 = (B3 ₁ + B3 ₂ +,... + B3 _i ) / i (7)
M4 = (B4 ₁ + B4 ₂ +,... + B4 _j ) / j (8)
Here, B3 _1, ..., B3 _i indicate the pixel signal value of each reference pixel in the reference area B3, and B4 _1, ... B4 _j indicate the value of the pixel signal of each reference pixel in the reference area B4.

Further, when the reference area B is provided in a frame shape at the edge of the detection area C as shown in FIG. 5, the frame-shaped reference area B is divided into a plurality of reference areas. In the present embodiment, as shown in FIG. 9, the upper row and the lower row are each divided into five divided reference regions B11 to B15 and B51 to B55, and the remaining reference regions, that is, divided reference regions B11 to B15, B51 to The left column and the right column, which are reference regions excluding B55, are divided into three divided reference regions B21 to B41 and B25 to B45, respectively, to create a total of 16 divided reference regions B11 to B55.

Next, average values M11 to M55 of the pixel signal values of the reference pixels in the divided reference areas B11 to B55 are calculated for each of the 16 divided reference areas B11 to B55 created. If the number of reference pixels in the reference area B11 is i, the average value M11 can be calculated by the following equation (9).
M11 = (B ₁ + B ₂ +,... + B _i ) / i (9)
Here, B _1, ... B _i indicate pixel signal values of the respective reference pixels in the reference region B.
The average values M12 to M55 of the remaining reference areas B12 to B55 can be calculated in the same manner as the reference area B11.

Next, as shown in FIG. 8, the signal correction unit 61 performs shading correction on the value of the pixel signal of the effective pixel in the effective area A. As shown in FIG. 3, when the reference area B is provided at the upper and lower ends of the detection area C, the calculated average value M1 of the pixel signals of the reference pixels in the reference area B1 at the upper end. And the average value M2 of the pixel signal values of the reference pixels in the reference region B2 at the lower end are calculated to calculate the shading amount S of each effective pixel in the effective region A, and the calculated shading amount S Shading correction is performed by calculating the value of the pixel signal of the effective pixel in the effective area A (S22).

For example, when a high-temperature object or the like is placed on the right side of the infrared imaging apparatus main body 12, the captured infrared image is generally whitish on the right side. That is, the density of the infrared image captured by the temperature difference around the infrared imaging device body 12 is uneven. When performing shading correction using the average values M1 and M2 of the pixel signals of the reference pixels in the reference region B1 at the upper end and the reference pixels in the reference region B2 at the lower end as shown in FIG. Since the shading amount S in the vertical direction of the image can be acquired in detail, the unevenness in the vertical direction of the infrared image can be accurately corrected.

Further, when the reference area B is provided at the left and right ends of the detection area C as shown in FIG. 4, it is the same as when the reference area B is provided at the upper and lower ends of the detection area C. Further, linear interpolation is performed using the calculated step difference between the average value M3 of the pixel signal values of the reference pixels in the reference region B3 at the left end portion and the average value M4 of the pixel signal values of the reference pixels in the reference region B4 at the right end portion. To calculate the shading amount S of the effective pixels in the effective area A, and the shading correction is performed by calculating the calculated shading amount S to the pixel signal value of the effective pixels in the effective area A.

When performing shading correction using the average values M3 and M4 of the pixel signals of the reference pixel in the reference region B3 at the left end and the reference pixel in the reference region B4 at the right end as shown in FIG. Since the shading amount S in the left-right direction of the image can be acquired in detail, unevenness in the left-right direction of the infrared image can be accurately corrected.

Further, when the reference area B is provided in a frame shape at the edge of the detection area C as shown in FIG. 5, the calculation is performed for each of the 16 divided reference areas B11 to B55 created above. The shading amount S is calculated using the average values M11 to M55 of the pixel signal values of the reference pixels in the divided reference regions B11 to B55. The shading amount S can be calculated using, for example, pixel signal values of surrounding pixels. Here, a method for calculating the shading amount S will be described in detail.

As shown in FIG. 10, assuming that the average values of the pixel signals of the reference pixels in the divided reference regions B11 to B55 are Z11 to Z55, respectively, the shading amount in the upper left effective pixel Z22 in the effective region A is expressed by the following formula ( 10).
Z22 = (Z12−Z11) + (Z21−Z11) + Z11
= Z12 + Z21-Z11 (10)

Further, the shading amount at the upper right effective pixel Z24 in the effective area A can be calculated by the following equation (11).
Z24 = (Z14−Z15) + (Z25−Z15) + Z15
= Z14 + Z25-Z15 (11)

That is, the effective area A is divided into four areas each divided at the center in the horizontal direction and the vertical direction, and the effective pixel T1 positioned in the upper left area with respect to the center of the effective area A is above the effective pixel T1. The average value M or effective pixel value of the divided reference region B adjacent to the left is added, and the average value M or effective pixel value of the divided reference region B adjacent to the upper left of the effective pixel T1 is added from the added value. By subtracting, the shading amount S at the effective pixel T is calculated. For the effective pixel T2 located in the lower left area with respect to the center of the effective area A, the average value M or the effective pixel value of the divided reference area B adjacent to the lower and left sides of the effective pixel T2 is added. The shading amount S in the effective pixel T2 is calculated by subtracting the average value M or the value of the effective pixel of the divided reference region B adjacent to the lower left of the effective pixel T2 from the added value.

Similarly, for the effective pixel T3 located in the upper right region with respect to the center of the effective region A, the average value M or the value of the effective pixel of the divided reference region B adjacent to the upper and right sides of the effective pixel T3 is added. Then, the shading amount S in the effective pixel T3 is calculated by subtracting the average value M or the value of the effective pixel in the divided reference region B adjacent to the upper right of the effective pixel T3 from the added value. For the effective pixel T4 located in the lower right region with respect to the center of the effective region A, the average value M or the value of the effective pixel of the divided reference region B adjacent to the lower and right sides of the effective pixel T4 is added. Then, the shading amount S in the effective pixel T4 is calculated by subtracting the average value M or the effective pixel value of the divided reference region B adjacent to the lower left of the effective pixel T4 from the added value.

As described above, the shading amount is calculated for each effective pixel in the effective region A by calculating the shading amount from the effective pixel farthest from the center of the effective region A. For example, the effective pixel Z23 in FIG. 10 is a pixel located at the center in the horizontal direction of the effective area A. In the present embodiment, the average value Z13 above the effective pixel Z23, the left effective pixel Z22, and the diagonal left However, the shading amount may be calculated using the average value Z13 above the effective pixel Z23, the right effective pixel Z24, and the diagonally right average value Z14. The value of the shading amount calculated previously in the surrounding pixels can be used. The pixel located in the center in the vertical direction of the effective area A can be calculated in the same manner. Further, when the effective pixel is located in the center of the effective area A, the value of the shading amount calculated in any of the surrounding pixels may be used or can be selected as appropriate.

Next, an example of the correction value of the shading correction calculated by the above-described shading amount calculation method will be described. When the average values Z11 to Z55 of the pixel signals of the reference pixels in the divided reference areas B11 to B55 calculated in step S21 in FIG. 8 are substituted into the formula shown in the effective area A in FIG. The shading amount shown in FIG. 11 is calculated for each of the effective pixels.

Then, the signal correcting unit 61 calculates the value of the calculated shading amount for each effective pixel from each of the pixel signal values of the effective pixels in the effective region A, and performs shading correction on the value of the pixel signal. To do. As shown in FIG. 11, the value of the shading amount calculated for each pixel may include a positive value and a negative value. When the value of the shading amount is a negative value, the absolute value of this shading amount value is added to the value of the pixel signal of the effective pixel in the effective area A. When the value of the shading amount is positive, The value of the shading amount is subtracted from the value of the pixel signal of the effective pixel in the effective area A.

As shown in FIG. 5, the shading correction is performed using the average values M11 to M55 of the pixel signal values of the reference pixels in the 16 divided reference regions B11 to B55 provided in a frame shape at the edge of the detection region C. When performing, since the shading amount S in the vertical direction and the horizontal direction of the infrared image due to the temperature difference around the infrared imaging device main body 12 can be acquired in detail, the unevenness of the entire infrared image can be accurately corrected.

Also in the second correction method, as in the first correction method described above, the infrared imaging device main body 12 and the infrared shielding body 9 are thermally coupled, so the infrared imaging device main body 12 and the infrared shielding body. 9 can be reduced, and the difference between the amount of infrared radiation emitted from the infrared imaging device main body 12 and the amount of radiation emitted from the infrared shielding body 9 can be reduced. As a result, the difference in the amount of infrared radiation from the infrared imaging device main body 12 and the infrared shielding body 9 incident on the effective area A and the reference area B can be reduced, so that the effective area A and the reference area B are offset. The difference in power correction amount becomes smaller. Accordingly, the value of the pixel signal is corrected by calculating the value of the calculated shading amount S for each effective pixel from each of the pixel signal values of the effective pixels in the effective area A, thereby correcting the value of the pixel signal. 3 can be corrected with high accuracy by offsetting the shading amount S that contributes to the infrared rays emitted from the infrared imaging device main body 12 and the infrared shielding body 9 from the pixel signals output by the infrared ray 3.

In the present embodiment, the above-described interpolation method is used to calculate the shading amount S. However, the present invention is not limited to this, and a known method such as linear interpolation or nonlinear interpolation can be used. .

Next, an infrared imaging device according to a second embodiment of the present invention will be described. FIG. 12 is a schematic cross-sectional view illustrating the configuration of an infrared imaging device according to the second embodiment of the present invention. Note that the infrared imaging device of the second embodiment has a configuration in which a temperature sensor, which will be described later, is provided in the infrared imaging device 1 of the above-described embodiment, and therefore, the description of the configuration in FIG. Hereinafter, only the temperature sensor 13 and the correction method using the output signal from the temperature sensor 13 by the signal correction unit 61 will be described in detail.

In the infrared imaging apparatus main body 12 of the present embodiment, a temperature sensor 13 is provided at a position facing the imaging optical system 2 in the infrared shielding body 9. As the temperature sensor 13, a known one such as a thermistor, a thermocouple, or a resistance temperature detector can be used. The output signal from the temperature sensor 13 is sent to the signal correction unit 61 by wired or wireless communication (not shown).

Next, a correction method by the signal correction unit 61 of the infrared imaging device of the present embodiment will be described with reference to a flowchart. FIG. 13 is a flowchart of the third correction process of the signal correction unit 61. Note that a series of processing of the infrared imaging apparatus of the present embodiment is the same as the processing of the flowchart of FIG. 6 of the above-described embodiment, and thus description thereof is omitted here, and only correction processing by the signal correction unit 61 is described. To do. In FIG. 13, the same processing as in FIG. 7 is denoted by the same step number, and detailed description thereof is omitted.

As shown in FIG. 13, the signal correction unit 61 calculates an average value M of pixel signal values of reference pixels, which are pixels in the reference region B, in step S11, and in step S12, the valid value in the effective region A. Offset correction is performed by subtracting the average value M from the pixel signal value of each pixel.

Next, the signal correction unit 61 detects an output signal from the temperature sensor 13 and calculates a value corresponding to the detected value of the output signal (step S13). FIG. 14 shows a relationship between the value of the output signal from the temperature sensor 13 and the calculated value corresponding to this value.

The calculation value corresponding to the value of the output signal from the temperature sensor 13 is set in advance for each type of the infrared imaging device 1, and corresponds to the value of the output signal from the temperature sensor 13, for example, as shown in FIG. A table of calculation values is stored in the storage unit 7. In this table, the amount of infrared rays emitted for each temperature of the infrared shielding body 9 is detected, and a value based on the amount of infrared rays emitted is set as a calculation value. Specifically, for example, in a state where the infrared imaging device 1 is placed in a thermostat and the temperatures of the infrared imaging device 1 and the infrared shield 9 are set to be constant, a reference heat source whose absolute temperature is known by the infrared imaging device 1 is photographed. Then, the value of the pixel signal of the effective pixel is detected. Next, the temperature of the infrared imaging device 1, that is, the infrared shield 9 is changed to detect the value of the output signal from the temperature sensor 13 and the value of the pixel signal of the effective pixel, and the value of the pixel signal of the detected effective pixel. And the value of the pixel signal value of the effective pixel detected above is calculated. Similarly, the temperature of the infrared shielding body 9 is changed stepwise, and the value of the output signal from the temperature sensor 13 at each temperature and the difference are calculated. In FIG. 14, the value of the output signal from the temperature sensor 13 output when the temperature of the infrared shielding body 9 is changed is set as the value N of the output signal from the temperature sensor of FIG. The difference value is the calculated value in FIG. The table of FIG. 14 is set in advance at the design stage or manufacturing stage of the infrared imaging device 1. The signal correction unit 61 refers to the table stored in the storage unit 7 to calculate a calculation value corresponding to the value of the output signal from the temperature sensor 13.

Next, the signal correction unit 61 calculates a calculation value corresponding to the value of the output signal of the temperature sensor 13 calculated in step S13 to the value after the offset correction in step S12, and further performs offset correction (step) S14). In FIG. 14, for example, when the calculated value M4 when the value of the output signal from the temperature sensor 13 is N4 is 0, the infrared image indicated by the value after offset correction is stored in the storage unit 7 in step S12. Is done.

On the other hand, if the values of the calculated values M1 to M3 when the value of the output signal from the temperature sensor 13 is any of N1 to N3 are positive values, the calculated values M1 to M3 are offset in step S12. The value of the pixel signal is further offset-corrected by subtracting from the corrected value. If the value after the calculated value M5 when the value of the output signal from the temperature sensor 13 is any value after N5 is a negative value, the absolute value of the value after the calculated value M5 is obtained in step S12. The value of the pixel signal is further offset corrected by adding to the value after the offset correction.

Generally, infrared rays emitted from the subject and infrared rays emitted from the infrared imaging device main body 12 and the infrared shielding body 9 are incident on the infrared sensor 3. In this embodiment, since the infrared imaging device body 12 and the infrared shielding body 9 are thermally coupled, the temperature difference between the infrared imaging device body 12 and the infrared shielding body 9 is small. That is, the difference between the amount of infrared rays emitted from the infrared imaging device main body 12 and the amount of infrared rays emitted from the infrared shielding body 9 is small. Therefore, as described above, the value of the output signal from the temperature sensor 13, that is, the calculated value that is a value based on the amount of infrared rays emitted from the infrared shielding body 9 is based on the amount of infrared rays emitted from the infrared imaging device body 12. It is also a value. Therefore, by calculating the calculation value, which is a value based on the value of the output signal from the temperature sensor 13, to the value of the pixel signal after the offset correction, the infrared shielding body 9 and the infrared imaging among the infrared rays incident on the infrared sensor 3. Since the value due to the infrared ray radiated from the apparatus main body 12 can be offset, it is possible to obtain a highly accurate image signal value based on the infrared ray radiated from the subject, and to obtain an accuracy based on the absolute temperature of the subject. A high infrared image can be acquired.

Next, another correction method by the signal correction unit 61 of the infrared imaging device of the present embodiment will be described with reference to a flowchart. FIG. 15 is a flowchart of the correction process of the signal correction unit 61 according to the fourth embodiment. Note that a series of processing of the infrared imaging apparatus of the present embodiment is the same as the processing of the flowchart of FIG. 6 of the above-described embodiment, and thus description thereof is omitted here, and only correction processing by the signal correction unit 61 is described. To do. In FIG. 15, the same processes as those in FIG. 8 are denoted by the same step numbers, and detailed description thereof is omitted.

As shown in FIG. 15, the signal correction unit 61 calculates an average value M of pixel signal values of reference pixels, which are pixels in each reference area B, in step S21, and in the effective area A in step S22. Shading correction is performed on the value of the pixel signal of the effective pixel.

Next, the signal correction unit 61 detects an output signal from the temperature sensor 13 and calculates a value corresponding to the detected value of the output signal (step S23). Here, since the process of step S23 is the same as the process of step 13 of FIG. 13, description here is abbreviate | omitted.

Next, the signal correction unit 61 performs an offset correction by calculating a calculation value corresponding to the value of the output signal of the temperature sensor 13 calculated in step S23 to the value after the shading correction in step S22 (step S24). ). In FIG. 14, for example, when the calculated value M4 when the value of the output signal from the temperature sensor 13 is N4 is 0, the infrared image indicated by the value after shading correction is stored in the storage unit 7 in step S22. The

On the other hand, if the values of the calculated values M1 to M3 when the value of the output signal from the temperature sensor 13 is any of N1 to N3 are positive values, the calculated values M1 to M3 are shaded in step S22. The value of the pixel signal is offset-corrected by subtracting from the corrected value. If the value after the calculated value M5 when the value of the output signal from the temperature sensor 13 is any value after N5 is a negative value, the absolute value of the value after the calculated value M5 is determined in step S22. The value of the pixel signal is offset corrected by adding to the value after the shading correction.

Generally, infrared rays emitted from the subject and infrared rays emitted from the infrared imaging device main body 12 and the infrared shielding body 9 are incident on the infrared sensor 3. In this embodiment, since the infrared imaging device body 12 and the infrared shielding body 9 are thermally coupled, the temperature difference between the infrared imaging device body 12 and the infrared shielding body 9 is small. That is, the difference between the amount of infrared rays emitted from the infrared imaging device main body 12 and the amount of infrared rays emitted from the infrared shielding body 9 is small. Therefore, as described above, the value of the output signal from the temperature sensor 13, that is, the calculated value that is a value based on the amount of infrared rays emitted from the infrared shielding body 9 is based on the amount of infrared rays emitted from the infrared imaging device body 12. It is also a value. Therefore, by calculating the calculated value based on the value of the output signal from the temperature sensor 13 to the value of the pixel signal after shading correction, among the infrared rays incident on the infrared sensor 3, the infrared shield 9 and the infrared ray Since the value due to the infrared rays radiated from the imaging device body 12 can be offset, it is possible to acquire a highly accurate image signal value based on the infrared rays radiated from the subject, and the accuracy based on the absolute temperature of the subject. High infrared image can be acquired.

In the above-described embodiment, the temperature sensor 13 is provided at a position facing the imaging optical system 2 in the infrared shielding body 9, but the present invention is not limited to this. In the present invention, since the infrared imaging device body 12 and the infrared shielding body 9 are thermally coupled, the infrared imaging device body 12 and the infrared shielding body 9 are at the same temperature. Therefore, the temperature sensor 13 may be provided anywhere on the infrared imaging device 12 and the infrared shielding body 9. For example, the temperature sensor 13 may be provided on the opposite side of the infrared shielding body 9 with respect to the temperature sensor 13 in FIG. The first main body 10 or the second main body 11 inside the infrared imaging device main body 12 may be provided on the wall surface constituting the first main body 10 or the second main body 11, or the first main body 10 or the second main body outside the infrared imaging device main body 12. You may provide in the wall surface which comprises the part 11, and can change suitably. When the temperature sensor 13 is provided inside the infrared imaging device main body 12, the temperature of the wall located in the space where the infrared sensor 3 is installed is measured, and the temperature of the wall that radiates infrared rays to the infrared sensor 3. Therefore, the correction accuracy can be improved. Further, when the infrared sensor 3 is provided at a position corresponding to the imaging optical system 2 in the infrared imaging apparatus main body 12, the temperature of the wall that emits infrared rays to the infrared sensor 3 can be measured. Further improvement can be achieved. In the present embodiment, one temperature sensor 13 is provided, but a plurality of temperature sensors 13 may be provided at different positions. When a plurality of temperature sensors 13 are provided, the average value of the output signals from each temperature sensor 13 can be used.

Next, an infrared imaging device according to a third embodiment of the present invention will be described. FIG. 16 is a schematic cross-sectional view illustrating the configuration of an infrared imaging device according to the third embodiment of the present invention. The infrared imaging apparatus of the third embodiment has the same configuration as the infrared imaging apparatus 1 of the second embodiment shown in FIG. 12 except for the structure of the infrared shield 91 shown in FIG. The same reference numerals are assigned to the same parts as those in FIG. 1, and the description thereof is omitted. Hereinafter, only the infrared shield 91 will be described. Note that the correction method of the infrared imaging apparatus 1 of the second embodiment can also be used for the correction method using the output signal from the temperature sensor 13 by the signal correction unit 61.

The infrared shield 91 includes a plate-shaped member 91b having an opening 91a disposed between the imaging optical system 2 and the infrared sensor 3 in parallel with the imaging surface 30 of the infrared sensor 3, and infrared imaging from the plate-shaped member 91b. A support member 91c is provided that extends toward the apparatus main body 12 and supports the plate member 91b by thermally connecting the plate-shaped member 91b and the infrared imaging apparatus main body 12 to each other. The plate-like member 91b is formed of a material that shields infrared rays, is formed of a single plate, and has a rectangular opening 91a at the center thereof. As shown in FIG. 5, infrared rays are incident from the openings 91 a of the plate-like member 91 b and are blocked by the plate-like members 91 b, so that an effective region A and a reference region B are included in the region C of the detection region 31. Can be provided. The support member 91c and the plate-like member 91b may be formed integrally or may be formed separately. If formed separately, they may be formed of different materials as long as they are thermally coupled.

In the above embodiment, the number of the plate-shaped members 91b is one, but the present invention is not limited to this, and a configuration using two plate-shaped members 91b may be used. When two plate members 91b are used, a support member 91c is provided on each plate member 91b. When the two plate-like members 91b are arranged vertically with a gap therebetween, this gap forms an opening 91a, and as shown in FIG. 3, the upper and lower ends in the area C of the detection area 31 are formed. A reference region B can be formed. Further, when the two plate-like members 91b are arranged on the left and right sides with an interval between them, this interval forms an opening 91a, and the left and right end portions in the region C of the detection region 31 as shown in FIG. The reference region B can be formed.

Next, an infrared imaging device according to a fourth embodiment of the present invention will be described. FIG. 17 is a schematic cross-sectional view for explaining the configuration of an infrared imaging device according to the fourth embodiment of the present invention. FIGS. 18 to 20 are diagrams showing an example of an infrared shielding method by masking the back of the lens. Note that the infrared imaging apparatus of the fourth embodiment has the same configuration as the infrared imaging apparatus 1 of the second embodiment shown in FIG. 12 except for the structure of the infrared shield 92 shown in FIG. The same reference numerals are assigned to the same parts as in FIG. 1, and the description thereof is omitted. Hereinafter, only the infrared shielding body 92 will be described. Note that the correction method of the infrared imaging apparatus 1 of the second embodiment can also be used for the correction method using the output signal from the temperature sensor 13 by the signal correction unit 61.

The infrared shield 92 is made of a material that shields infrared rays, and is made of a member that masks the surface of the imaging optical system 2 that is closest to the infrared sensor 3. The masking member is more preferably formed of a material having a higher thermal conductivity than aluminum or stainless steel, and in this embodiment, the member is formed of copper. The infrared shield 92 and the infrared imaging device main body 12 are thermally coupled by the connection body 93. The connection body 93 is formed of a heat conductive material, and the infrared shield 92 and the infrared imaging apparatus main body 12 are configured such that thermal energy can move in a direction in which there is no temperature difference.

As shown in FIG. 18, the infrared shield 92 has a rectangular opening 9a at the center thereof. The opening 9a is formed to be smaller than the region C of the detection region 31, and infrared rays are incident from the opening 9a of the plate-like member 91b, and the infrared rays are blocked by the infrared shielding body 92, whereby the region C of the detection region 31 is formed. An effective area A and a reference area B can be provided inside.

In the above embodiment, the number of the infrared shields 92 is one. However, the present invention is not limited to this, and two infrared shields 92 may be used. When two infrared shielding bodies 92 are used, a connection body 93 is provided on each infrared shielding body 92. When two infrared shields 92 are arranged above and below at intervals, that is, when masking the upper and lower surfaces of the lens of the imaging optical system 2 closest to the infrared sensor 3 side, as shown in FIG. A region that is not masked forms the opening 9b, and the reference region B can be formed at the upper and lower end portions in the region C of the detection region 31. When two infrared shields 92 are arranged on the left and right sides with a space therebetween, that is, when the left and right sides of the surface of the imaging optical system 2 closest to the infrared sensor 3 are masked, as shown in FIG. The region not masked forms the opening 9c, and the reference region B can be formed at the left and right end portions in the region C of the detection region 31.

As in the infrared imaging device of the fourth embodiment, by using a method of shielding infrared by masking the back of the lens of the imaging optical system 2, openings 9a, 9b, Since the reference pixel B can be provided in the detection region 31 only by making the size of 9c smaller than the region C of the detection region 31 of the infrared sensor 3, it is possible to reduce the cost required for manufacturing the infrared imaging device. it can. In addition, resolution performance can be enhanced by capturing an infrared image at the center of the lens. As for the effect of the shape of the reference region B, the same effect as the effect described with reference to FIGS. 3 to 5 of the above-described embodiment can be obtained, and thus the description thereof is omitted here.

According to each embodiment of the present invention, each effect described above can be suitably obtained with respect to offset fluctuation of a detection signal generated in a thermal detection element such as a microbolometer type or an SOI (Silicon on Insulator) diode type. Although an infrared sensor that detects far infrared rays (wavelength of 8 μm to 15 μm) is used, the present invention is not limited to this, and an infrared sensor that detects middle infrared rays and near infrared rays may be used.

Moreover, the infrared imaging device 1 according to each embodiment of the present invention can be suitably applied to a security imaging device, an in-vehicle imaging device, and the like, and may be configured as a single imaging device that captures an infrared image. It may be configured to be incorporated in an imaging system having an infrared image capturing function.

The infrared imaging device of the present invention is not limited to the above embodiment, and can be appropriately changed without departing from the spirit of the invention.

DESCRIPTION OF SYMBOLS 1 Infrared imaging device 12 Infrared imaging device main body 13 Temperature sensor 2 Imaging optical system 3 Infrared sensor 4 Analog signal processing part 5 A / D conversion part 6 Digital signal processing part 61 Signal correction part 7 Storage part 8 Output part 30 Imaging surface 31 Detection areas 9, 91, 92 Infrared shield 91a Opening 91b Plate member 91c Support member A Effective area B Reference area C Detection area O Optical axis

Claims (14)

An imaging optical system for imaging infrared rays;
A pixel signal based on infrared rays incident from the imaging optical system is provided for each pixel, having a detection region located on the imaging surface of the imaging optical system and having a plurality of pixels as thermoelectric conversion elements arranged. An infrared sensor that outputs each;
By shielding a part of the infrared rays between the imaging optical system and the imaging plane, an effective region where the infrared rays from the imaging optical system enter the detection region and the imaging optical system An infrared imaging device comprising an infrared imaging device main body and an infrared shield thermally coupled to provide a reference region in which no infrared rays are incident. The infrared imaging device according to claim 1, wherein the infrared shielding body is constituted by a shielding plate extending from the infrared imaging device main body toward the inside of the main body. The said infrared shielding body is provided with the plate-shaped member which has opening, and the supporting member which couple | bonds this plate-shaped member and the said infrared imaging device main body thermally, and supports the said plate-shaped member. Infrared imaging device. A signal correction unit that performs correction processing on the value of the pixel signal output by the infrared sensor;
The signal correction unit corrects the value of the pixel signal of the effective pixel that is the pixel in the effective region by using the value of the pixel signal of the reference pixel that is the pixel in the reference region. The infrared imaging device according to any one of claims 1 to 3, wherein fluctuations in the value of the pixel signal are corrected. The infrared imaging device according to claim 4, wherein the signal correction unit performs offset correction by subtracting an average value of pixel signals of the reference pixels from a value of a pixel signal of the effective pixels. Two or more reference areas are provided in the detection area,
The signal correction unit subtracts an average value of pixel signals of the reference pixels in at least one of the reference regions of the two or more reference regions from a value of the pixel signal of the effective pixel, and the offset. The infrared imaging device according to claim 5 which performs correction. Two or more reference areas are provided in the detection area,
The signal correction unit calculates an average value of pixel signals of the reference pixels in at least two of the reference regions out of the two or more reference regions, and uses the calculated at least two average values, The infrared imaging device according to claim 4, wherein shading correction is performed on a value of a pixel signal of the effective pixel. The infrared imaging device according to claim 6 or 7, wherein the reference area is provided at each of upper and lower ends of the detection area. The infrared imaging device according to claim 6 or 7, wherein the reference area is provided at each of left and right ends of the detection area. Providing a frame-shaped reference region in which a plurality of the reference pixels are arranged at an edge in the detection region, dividing the frame-shaped reference region into a plurality of regions;
The signal correction unit calculates, for each of the plurality of regions, an average value of pixel signals of reference pixels located in the plurality of regions, and uses each of the calculated average values to calculate the effective pixel. The infrared imaging device according to claim 4, wherein shading correction is performed on the value of the pixel signal. Providing at least one temperature sensor in the infrared imaging device body;
The infrared ray according to any one of claims 4 to 10, wherein the signal correction unit performs offset correction by calculating a value corresponding to a value of an output signal from the temperature sensor to a value of a pixel signal of the effective pixel. Imaging device. The infrared imaging device according to claim 11, wherein the temperature sensor is provided inside the infrared imaging device main body. The infrared imaging device according to claim 12, wherein the temperature sensor is provided on the infrared shielding body. The infrared imaging device according to claim 13, wherein the temperature sensor is provided at a position facing the imaging optical system.

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