Forehead temperature measuring system for compensating and measuring forehead temperature

Abstract

A forehead temperature measuring system includes an image sensor, a temperature sensor, and a processor. The image sensor is used for outputting an image frame. The temperature sensor is used for outputting a thermal image. The processor is used for determining a forehead area in the image frame, mapping the forehead area to the thermal image and judging the forehead temperature according to a forehead mapping area in the thermal image. The processor also corrects or compensates the forehead temperature according to the area of the forehead region.

Description

[0001] This application is a divisional application of the Chinese invention patent application with application number 202110929948.5, application date August 13, 2021, and name “High-precision Forehead Temperature Measurement System”. Technical Field

[0002] The present invention relates to a remote forehead temperature measurement, and more particularly to a forehead temperature measurement system for improving the measurement accuracy by compensating or correcting the forehead temperature measured by a temperature sensor. Background Art

[0003] Setting up automatic forehead temperature measurement systems at stores and building entrances has gradually become the new normal. However, unlike forehead thermometers, since the distance between the person being measured and the automatic forehead temperature measurement system is not fixed and the system's field of view usually includes environmental objects, it will affect the measurement accuracy. Furthermore, the changing ambient temperature is also one of the parameters that affect the measured temperature. Therefore, the current automatic forehead temperature measurement system has a large deviation range for the measured temperature, and misjudgment often occurs when compared with the temperature threshold.

[0004] In view of this, the present invention provides a forehead temperature measurement system and a temperature measurement method thereof which can compensate or correct the temperature deviation caused by the distance of the measured person and the change of the ambient temperature. Summary of the invention

[0005] The invention provides a forehead temperature measuring system comprising an image sensor and a temperature sensor, so as to utilize the image sensor to confirm the temperature measuring range of the temperature sensor.

[0006] The present invention also provides a forehead temperature measurement system with two sets of viewing angles, so as to improve the temperature measurement accuracy by selecting a smaller viewing angle when the person being measured is far away.

[0007] The present invention also provides a forehead temperature measurement system for correcting and measuring forehead temperature according to the ratio of the key pixels of the forehead area in the thermal image.

[0008] The present invention also provides a forehead temperature measuring system for calibrating and measuring forehead temperature according to forehead area and ambient temperature.

[0009] The present invention also provides a forehead temperature measurement system comprising a first image sensor, a second image sensor, a first temperature sensor and a processor. The first image sensor is used to output a first image frame. The first temperature sensor is used to output a first thermal image. The processor is coupled to the image sensor, the second image sensor and the first temperature sensor, and is used to identify a first forehead region and calculate the forehead area according to the first image frame, when the forehead area is greater than an area threshold, the first forehead region is imaged to the first thermal image and the forehead temperature is measured accordingly, and when the forehead area is less than the area threshold, the second image sensor is controlled to obtain a second image frame, wherein the second occupied area of ​​the forehead area in the second image frame is larger than the first occupied area in the first image frame, so as to improve the measurement accuracy.

[0010] The present invention also provides a forehead temperature measurement system including a first image sensor, a first temperature sensor and a processor. The first image sensor is used to output a first image frame. The first temperature sensor is used to output a first thermal image. The processor is coupled to the first image sensor and the first temperature sensor, and is used to identify a forehead area according to the first image frame, image the forehead area to the first thermal image to determine an image area, determine the ambient temperature according to the temperature outside the image area, find the key pixel with the highest temperature in the image area and identify the ratio of the forehead area to the area corresponding to the key pixel in the first image frame, and when the ratio is lower than a ratio threshold, calculate and measure the forehead temperature according to a first product of the ratio of the highest temperature to the forehead area and a second product of the ratio of the ambient temperature to the non-forehead area.

[0011] The present invention also provides a forehead temperature measurement system including an image sensor, a temperature sensor and a processor. The image sensor is used to output an image frame. The temperature sensor is used to output a thermal image. The processor is coupled to the image sensor and the temperature sensor, and is used to identify a forehead area according to the image frame, image the forehead area to the thermal image to determine an image area, use the highest temperature in the image area as the measured forehead temperature, and correct the measured forehead temperature according to the uniformity of the temperature difference between the measured forehead temperature and the adjacent temperatures of the measured forehead temperature, wherein when the uniformity is low, the correction amount is large, and when the uniformity is high, the correction amount is small.

[0012] In order to make the above and other purposes, features and advantages of the present invention more obvious, the following will be described in detail with reference to the accompanying drawings. In addition, in the description of the present invention, the same components are represented by the same symbols, which are hereby described together. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1is a schematic diagram of the operation of the forehead temperature measurement system according to an embodiment of the present invention;

[0014] Figure 2 is a block diagram of a forehead temperature measurement system according to an embodiment of the present invention;

[0015] Figure 3 is a schematic diagram of temperature measurement of a forehead temperature measurement system according to an embodiment of the present invention;

[0016] Figure 4 is another schematic diagram of temperature measurement of the forehead temperature measurement system according to an embodiment of the present invention;

[0017] Figure 5 is a flow chart of a temperature measurement method of a forehead temperature measurement system according to an embodiment of the present invention;

[0018] Figure 6 is a schematic diagram of temperature compensation of a forehead temperature measurement system according to an embodiment of the present invention;

[0019] Figure 7 is a schematic diagram of temperature compensation of a forehead temperature measurement system according to another embodiment of the present invention; and

[0020] FIG. 8A to FIG. 8C yes Figure 7 Schematic diagram of temperature compensation.

[0021] Description of Reference Numerals

[0022] 100 Forehead temperature measurement system

[0023] 11 Sensor Chip

[0024] 13 Lens

[0025] 21.21' Image Sensor

[0026] 23.23' Temperature sensor

[0027] 25 Processor

[0028] FOV DETAILED DESCRIPTION

[0029] The forehead temperature measurement system of the embodiment of the present invention first determines the forehead area by using image recognition according to the image frame acquired by the image sensor, and then determines the forehead temperature to be measured according to the image area corresponding to the forehead area in the thermal image acquired by the temperature sensor. In addition, the forehead temperature measurement system of the embodiment of the present invention also compensates or corrects the measured forehead temperature according to the area of ​​the forehead area to improve the measurement accuracy.

[0030] Please refer to Figure 1 and Figure 2 As shown, Figure 1Schematic diagram of the operation of the forehead temperature measurement system 100 according to an embodiment of the present invention; Figure 2 Schematic diagram of a forehead temperature measurement system 100 according to an embodiment of the present invention.

[0031] The forehead temperature measurement system 100 includes a detection chip 11 and a lens 13 , wherein the lens 13 is disposed on the light receiving side of the detection chip 11 to adjust the optical path and the viewing angle FOV.

[0032] The detection chip 11 includes an image sensor 21, a temperature sensor 23 and a processor 25. The image sensor 21 and the temperature sensor 23 both receive light energy through the lens 13. The detection chip 11 is disposed on a substrate and coupled to external components through the substrate.

[0033] The image sensor 21 (and 21', if included) is, for example, a CCD image sensor or a CMOS image sensor, and is used to output image frames IF at a predetermined frequency. Figure 2 The displayed image frame IF includes a face image. The temperature sensor 23 (and 23', if included) is, for example, a far infrared (FIR) sensor, which is used to detect far infrared rays of a human body and output a thermal image IT corresponding to the acquisition of the image frame IF.

[0034] In one embodiment, the image sensor 21 and the temperature sensor 23 have the same FOV to receive light energy in the same space, but the present invention is not limited thereto. In another embodiment, the FOV of the image sensor 21 is greater than or less than that of the temperature sensor 23 .

[0035] In one embodiment, the number of pixels of the image frame IF is higher than the number of pixels of the thermal image IT. The image frame IF, for example, includes 240×240 pixels to have sufficient details or features for the processor 25 to perform image recognition, such as face recognition and forehead area recognition. The thermal image IT, for example, includes 8×8 pixels to detect the temperature of 64 points within the field of view FOV.

[0036] The processor 25 is coupled to the image sensor 21 and the temperature sensor 23 to receive the image frame IF and the thermal image IT respectively. The processor 25 is, for example, a digital processor (DSP), an application specific integrated circuit (ASIC) or a programmable logic circuit (FPGA), and its functions are implemented by hardware and / or firmware, for example, including identifying the forehead region FH according to the image frame IF and calculating the forehead area, mapping the forehead region FH to the thermal image IT to determine the image region A. map , according to the image area A map The temperature inside the body determines the forehead temperature to be measured and compensated or corrected using the method described below.

[0037] The imaging method of the forehead area FH is described below with examples.

[0038] In one embodiment, the thermal image IT may be interpolated to form an interpolated thermal image having the same pixels as the image frame IF, and by overlapping the image frame IF with the interpolated thermal image, an image region A may be correspondingly obtained in the interpolated thermal image. map .

[0039] In another embodiment, a pixel of the thermal image IT (eg Figure 2 A rectangular area in the thermal image IT corresponds to a plurality of pixels of the image frame IF. For example, if one pixel of the thermal image IT corresponds to 30×30 pixels of the image frame IF according to the above assumption, the image area A can also be corresponding to the thermal image IT. map According to this assumption, if the image area A map One pixel of the thermal image IT covers 30×30 pixels corresponding to the image frame IF, and so on.

[0040] In one embodiment, the forehead temperature is measured as the image area A of the thermal image IT map In other embodiments, the forehead temperature is measured in the image area A of the thermal image IT. map The average value of multiple detected temperature values. One pixel of the thermal image IT obtains one detected temperature value.

[0041] In order to improve the detection accuracy, the forehead temperature measurement system 100 of the present invention also performs temperature correction or compensation on the measured forehead temperature. map The detected temperature values ​​of pixels other than those are not used as the measured forehead temperature, but are used to compensate or correct the measured forehead temperature.

[0042] Please refer to Figure 3 , which is a schematic diagram of temperature measurement of the forehead temperature measurement system 100 according to an embodiment of the present invention. In this embodiment, in addition to the image sensor (or referred to as the first image sensor) 21 and the temperature sensor (or referred to as the first temperature sensor) 23, the forehead temperature measurement system 100 further includes an image sensor (or referred to as the second image sensor) 21' and a temperature sensor (or referred to as the second temperature sensor) 23', wherein the second image sensor 21' and the second temperature sensor 23' are also coupled to the processor 25.

[0043] It must be pointed out that Figure 3 Although two processors 25 are shown, they are only used to illustrate the operation in two conditions (or modes). The forehead temperature measurement system 100 can process all functions using one processor 25 .

[0044] In one embodiment, the first image sensor 21 and the first temperature sensor 23 have a first viewing angle, for example, FOV1=60; the second image sensor 21 ′ and the second temperature sensor 23 ′ have a second viewing angle smaller than the first viewing angle, for example, FOV2=30.

[0045] The first image sensor 21 is used to output a first image frame IF1, for example, represented by a face image with FOV1=60. The first temperature sensor 23 is used to output a first thermal image IT1, for example, displaying a pixel array containing 8×8 pixels. The second image sensor 21' is used to output a second image frame IF2, for example, represented by a face image with FOV2=30. The second temperature sensor 23' is used to output a second thermal image IT2, for example, displaying a pixel array containing 8×8 pixels. Figure 3 The overlapping of the first image frame IF1 and the first thermal image IT1 and the overlapping of the second image frame IF2 and the second thermal image IT2 are displayed, which is executed by the processor 25 .

[0046] More specifically, the processor 25 identifies the first forehead region (refer to Figure 2 When the forehead area is greater than the area threshold (e.g., recorded in the memory), the processor 25 maps the first forehead region FH to the first thermal image IT1 and determines to measure the forehead temperature accordingly, including mapping the first forehead region FH to the first thermal image IT1 to determine the first image region A. map1 And according to the first image area A map1 As mentioned above, the forehead temperature is the temperature of the first image area A. map1 The maximum or average temperature within.

[0047] When the forehead area is smaller than the area threshold, the processor 25 controls the second image sensor 21' to obtain the second image frame IF2, identifies the second forehead area according to the second image frame IF2, and maps the second forehead area to the second thermal image IT2 obtained by the second temperature sensor 23' to determine the second image area A. map2 , and according to the second image area A map2 The temperature inside the body determines the measured forehead temperature.

[0048] Figure 3 The processor 25 generates a first image region A according to the first image region A. map1 Or the second image area A map2 How to obtain forehead temperature measurement Figure 2 The same is only calculated based on different sets of sensors. Figure 3In the embodiment, when the face image in the first image frame IF1 is too small (for example, the forehead area is less than the area threshold), the second image sensor 21' and the second temperature sensor 23' are used to determine the forehead temperature. Because the second image sensor 21' and the second temperature sensor 23' have a smaller viewing angle, the face can occupy a larger area in the viewing angle range to improve the measurement accuracy. For example, the processor 25 can be configured to not process the first thermal image IT1 when the forehead area is less than the area threshold, and only when the forehead area is greater than or equal to the area threshold, the forehead temperature is determined based on the first image frame IF1 and the first thermal image IT1.

[0049] If the processor 25 needs to use the following method to calibrate the measured forehead temperature calculated based on the second image frame IF2 and the second thermal image IT2, the processor 25 also calculates the forehead area based on the second image frame IF2 and calculates the ambient temperature based on the second image frame IF2.

[0050] Please refer to Figure 4 As shown, it is another schematic diagram of the temperature measurement of the forehead temperature measurement system 100 according to an embodiment of the present invention. Figure 2 After receiving the image frame IF and the thermal image IT, the processor 25 identifies the forehead region FH according to the image frame IF and maps the forehead region FH to the thermal image IT to determine the image region A. map , according to the image area A map Temperatures other than Figure 4 pixA) determines the ambient temperature and finds the image area A map The highest temperature of the key pixel within Figure 4 pixB) and identify the ratio of the forehead area FH of the area corresponding to the key pixel pixB in the image frame IF (for example Figure 4 Displayed as 50% is forehead and 50% is not forehead) and when the ratio is lower than a ratio threshold (e.g. 90% to 95%, which is recorded in storage), the measured forehead temperature is calculated based on the maximum temperature, the ratio and the ambient temperature.

[0051] In one embodiment, the ambient temperature is the temperature in the thermal image IT that is different from the maximum temperature (eg Figure 4 The detected temperature value of the adjacent pixel pixA of the key pixel pixB is shown as 28°C, for example Figure 4Displayed as 20°C. The processor 25 can, for example, identify the ratio of the forehead area and the non-forehead area in the pixel area (for example, including 30×30 pixels) of the image frame IF corresponding to the key pixel pixB. For example, the measured forehead temperature is set to X, and the equation X×50%+20×50%=28 is used to obtain the measured forehead temperature X=36°C. That is, when the area ratio of the forehead area and the non-forehead area, the ambient temperature and the maximum temperature are calculated, the corresponding measured forehead temperature can be calculated. In an embodiment of the present invention, the measured forehead temperature is not directly equal to the detected temperature value of the key pixel.

[0052] It is understood that the ambient temperature is not limited to Figure 4 The detected temperature value of the pixel pixA is not the detected temperature value of the pixel pixA, but the detected temperature value of other pixels outside the image area.

[0053] However, when the ratio is higher than the ratio range, it can be considered that the influence of the ambient temperature can be ignored, and the processor 25 uses the maximum temperature of the key pixel pixB as the measured forehead temperature.

[0054] also, Figure 4 The temperature measurement can be combined with Figure 3 That is, the processor 25 first measures the temperature of the first image frame ( Figure 3 IF1) calculates the forehead area. When the forehead area is greater than the area threshold, Figure 4 The first thermal image ( Figure 3 When the forehead area is less than the area threshold, the processor 25 controls the second image sensor 21' to obtain the second image frame ( Figure 3 IF2) to replace the first image frame IF1 and control the second temperature sensor 23' to obtain a second thermal image ( Figure 3 IT2) to replace the first thermal image IT1, and then based on Figure 4 The description uses the second image frame IF2 and the second thermal image IT2 to calculate and measure the forehead temperature.

[0055] Please refer to Figure 5 , which is a flow chart of the temperature measurement method of the forehead temperature measurement system 100 according to an embodiment of the present invention, comprising the following steps: measuring the forehead area with an image sensor (step S51); measuring the forehead temperature and the ambient temperature with a temperature sensor (step S53); and correcting the forehead temperature according to the forehead area and the ambient temperature (step S55).

[0056] Please also refer to Figure 2 , then an implementation method of the temperature measurement method is described.

[0057] Step S51: After receiving the image frame IF, the processor 25 identifies the forehead region FH in the image frame IF and calculates the forehead area of ​​the forehead region FH. The processor 25, for example, has a built-in image recognition algorithm (which is, for example, a model established using an artificial intelligence algorithm, but not limited to) to identify the forehead region FH. The processor 25 can also calculate the number of pixels occupied by the forehead region FH in the image frame IF as the forehead area.

[0058] Step S53: After receiving the thermal image IT, the processor 25 then maps the forehead area FH to the thermal image IT to determine the image area A in the thermal image IT. map , the image area A map The highest temperature or average temperature within the range is taken as the forehead temperature, and the image area A map Temperatures other than those in the image region A map The detected temperature value of one adjacent pixel or the average detected temperature value of multiple adjacent pixels) is used as the ambient temperature.

[0059] Step S55: Finally, the processor 25 corrects the measured forehead temperature according to the forehead area and the ambient temperature. For example, when the forehead area is smaller, the correction amount for correcting the measured forehead temperature is larger. For example, when the ambient temperature is lower, the correction amount for correcting the measured forehead temperature is larger. The correction amount is, for example, the temperature increase amount, so that the corrected forehead temperature is higher than the measured forehead temperature. In one embodiment, when the forehead area is greater than or equal to a predetermined area, the correction amount related to the forehead area is reduced to 0. In another embodiment, when the ambient temperature is greater than or equal to a predetermined temperature, the correction amount related to the ambient temperature is reduced to 0.

[0060] Therefore, the forehead temperature measurement system 100 of the present invention further includes a storage device for pre-storing the correspondence between the forehead area and the ambient temperature and the correction amount for correcting the measured forehead temperature, so that the processor 25 can determine the current correction amount based on the correspondence according to the current forehead area and the current ambient temperature. The processor 25 then adds the current correction amount to the current measured forehead temperature to obtain the corrected forehead temperature.

[0061] In one embodiment, the forehead temperature measurement system 100 can be used to measure the user before the forehead temperature measurement system 100 leaves the factory to calculate the measured forehead temperature under different forehead areas (e.g., corresponding to different distances) and different ambient temperatures. At the same time, a more accurate thermometer (e.g., a forehead temperature gun or a contact thermometer) can be used to obtain the reference temperature of the same user under the same conditions. Then, the forehead area and the ambient temperature can be used as variables to fit the measured forehead temperature to the reference temperature using a fitting method, so as to obtain a fitting equation and record it in the storage as the corresponding relationship.

[0062] The corresponding relationship is not limited to being obtained using a fitting method. As long as the recorded relationship is able to correct the measured forehead temperature corresponding to different forehead areas and ambient temperatures to be close to or equal to the reference temperature (i.e., obtaining the correction amount corresponding to different forehead areas and ambient temperatures), any method is acceptable without specific limitations.

[0063] Similarly, Figure 5 The embodiments can also be used with Figure 3 In combination with the embodiment of the present invention, when the processor 25 determines that the forehead area is less than the area threshold, a group of sensors with a smaller viewing angle is controlled to measure the forehead temperature. When the processor 25 determines that the forehead area is greater than or equal to the area threshold, a group of sensors with a larger viewing angle is controlled to measure the forehead temperature.

[0064] For example, refer to Figure 6 As shown, it shows the correction amount relative to different forehead areas and ambient temperatures, and the vertical axis unit is, for example, ° C. When the ambient temperature (for example, 15°C, 20°C, 25°C, 30°C and 35°C are displayed, but not limited to this), the corresponding forehead area (for example, 50, 100, 150, 200, 250 and 300 are displayed, but not limited to this) needs to be compensated with a larger correction amount for the currently measured forehead temperature.

[0065] Please refer to Figure 7 , which is a schematic diagram of a temperature measurement method of a forehead temperature measurement system 100 according to another embodiment of the present invention. The temperature measurement method comprises the following steps: measuring the forehead area with an image sensor; measuring the forehead temperature and the adjacent temperature with a temperature sensor; and correcting the forehead temperature according to the measured forehead temperature and the adjacent temperature.

[0066] Please also refer to Figure 2 , then an implementation method of the temperature compensation method is described.

[0067] After receiving the image frame IF, the processor 25 identifies the forehead region FH in the image frame IF and calculates the forehead area of ​​the forehead region FH. The processor 25, for example, has a built-in image recognition algorithm (which is, for example, a model established using an artificial intelligence algorithm, but not limited to) to identify the forehead region FH. The processor 25 can also calculate the number of pixels occupied by the forehead region FH in the image frame IF as the forehead area.

[0068] After receiving the thermal image IT, the processor 25 then maps the forehead area FH to the thermal image IT to determine the image area A in the thermal image IT. map , the image area A map The highest temperature within the range is taken as the measured forehead temperature, and the temperature of the adjacent pixel of the pixel corresponding to the measured forehead temperature is taken as the adjacent temperature. Figure 7 As shown, assuming that the image area A mapIt includes 3 pixels (or 3 pixel regions, each pixel region includes multiple pixels), and the middle pixel (for example, marked as ②) outputs the measured forehead temperature and the adjacent pixels (for example, marked as ①, ③) output the adjacent temperatures. It can be understood that the image area A map It is not limited to only 3 pixels or pixel areas.

[0069] In one embodiment, the temperature correction of this embodiment is performed only when the processor 25 determines that the forehead area is less than the preset area threshold. When the forehead area is greater than or equal to the preset area threshold, the measured forehead temperature is directly used as the output temperature without compensation.

[0070] Finally, the processor 25 corrects the measured forehead temperature according to the measured forehead temperature and the adjacent temperatures. map In an embodiment including 3 pixels, the processor 25 first calculates the first temperature difference and the second temperature difference between the measured forehead temperature and two adjacent temperatures (for example, including the first adjacent temperature and the second adjacent temperature), and then corrects the measured forehead temperature based on the uniformity of the first temperature difference and the second temperature difference.

[0071] Please also refer to Figure 7 and Fig. 8A As shown, in Example 1, the measured forehead temperature is T_2, the first adjacent temperature is T_1, and the second adjacent temperature is T_3. Fig. 8A In the figure, the forehead area mainly corresponds to the pixels of T_1 and T_2, and T_1 and T_2 are roughly the same, and the pixel of T_3 is outside the forehead area and has the lowest temperature. At this time, the first temperature difference (T_2-T_1) is roughly 0 and the second temperature difference (T_2-T_3) is relatively large and has low uniformity, so the processor 25 determines a larger correction amount.

[0072] Please also refer to Figure 7 and Figure 8B As shown, in Example 2, the pixel corresponding to T_2 occupies the largest forehead area (e.g., 60%), and the pixel corresponding to T_3 occupies the smallest forehead area (e.g., 10%). At this time, the first temperature difference is smaller than the second temperature difference, which is smaller than Fig. 8A Therefore, the uniformity of Example 2 is higher than that of Example 1, and thus the processor 25 determines a smaller correction amount than that of Example 1.

[0073] Please also refer to Figure 7 and Figure 8C As shown, in Example 3, the pixels corresponding to T_2 occupy the largest forehead area (e.g., 70%), and the pixels corresponding to T_1 and T_3 occupy smaller and substantially equal forehead areas (e.g., 15%). At this time, the first temperature difference is substantially equal to the second temperature difference and is highly uniform, so the processor 25 determines a smaller correction amount.

[0074] In other words, the lower the uniformity (such as Example 1), the larger the correction amount (ie, measuring the forehead temperature plus more temperature); conversely, the higher the uniformity (such as Example 3), the smaller the correction amount (ie, measuring the forehead temperature plus less temperature).

[0075] The forehead temperature measurement system 100 of the present invention further includes a storage device for pre-storing the correspondence between the uniformity and the correction amount for correcting the measured forehead temperature, so that the processor 25 can determine the current correction amount based on the measured forehead temperature and the adjacent temperature. The processor 25 then adds the current correction amount to the current measured forehead temperature to obtain the corrected forehead temperature.

[0076] In one embodiment, the forehead temperature measurement system 100 can be used to measure the user before the forehead temperature measurement system 100 leaves the factory to calculate the uniformity of different measured forehead temperatures and adjacent temperatures. At the same time, a more accurate thermometer (such as a forehead temperature gun or a contact thermometer) is used to obtain the reference temperature of the same user under the same conditions. Then, the measured forehead temperature and the adjacent temperature are used as variables to fit the measured forehead temperature to the reference temperature using a fitting method, so as to obtain a fitting equation and record it as the corresponding relationship in the storage.

[0077] The corresponding relationship is not limited to being obtained using a fitting method. As long as the recorded relationship is able to correct the measured forehead temperatures corresponding to different measured forehead temperatures and adjacent temperatures (or uniformities) to be close to or equal to the reference temperature (i.e., obtaining the correction amount corresponding to different uniformities), any method is acceptable without specific limitations.

[0078] Similarly, Figure 7 The embodiments can also be used with Figure 3 In combination with the embodiment of the present invention, when the processor 25 determines that the forehead area is less than the area threshold, a group of sensors with a smaller viewing angle is controlled to measure the forehead temperature. When the processor 25 determines that the forehead area is greater than or equal to the area threshold, a group of sensors with a larger viewing angle is controlled to measure the forehead temperature.

[0079] also, Figure 7 The embodiments can also be used with Figure 5 That is, the processor 25 can be combined with the embodiment of the present invention according to the forehead area, the ambient temperature and the image area A. map The adjacent temperature distribution (e.g. uniformity) is used to compensate the measured forehead temperature.

[0080] In the present invention, the measured forehead temperature or the corrected forehead temperature can be output to a display for display and / or compared with a temperature threshold to determine whether to issue an alarm. For example, the forehead temperature measurement system 100 can be configured to directly output the measured forehead temperature or the corrected forehead temperature, or only output a flag signal (for example, outputting a digital value of 1 when the forehead temperature exceeds 38°C, but not limited to) to indicate that the body temperature is too high.

[0081] It must be noted that the numerical values ​​in the above embodiments and diagrams, such as temperature values, viewing angles, area ratios, number of pixels, etc., are only used for illustration and are not used to limit the present invention.

[0082] The forehead area in the description of the present invention may be, for example, the length of the forehead region FH, the width of the forehead region FH, or the length×width of the forehead region FH.

[0083] It should be noted that, although the above embodiment is described by taking the example of the processor 25 calculating the forehead area according to the image frame IF, such as the number of pixels in the forehead region FH in the image frame IF, the present invention is not limited thereto. map Calculate forehead area, such as image area A in thermal image IT map The number of pixels.

[0084] In summary, the conventional automatic forehead temperature measurement system may produce temperature deviation due to the distance between the measured person and the ambient temperature. Therefore, the present invention further provides a forehead temperature measurement system that can calibrate or compensate the measured forehead temperature (refer to Figures 1 to 4 ) and its temperature measurement method (refer to Figure 5 ), which first confirms the forehead area by using the image frame, and then determines the forehead temperature to be measured according to the area corresponding to the forehead area in the thermal image. Finally, the measured forehead temperature can also be compensated or corrected according to the forehead area of ​​the forehead area to improve the measurement accuracy.

[0085] Although the present invention has been disclosed through the above examples, they are not intended to limit the present invention. Any person skilled in the art with ordinary knowledge in the art to which the present invention belongs can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the appended claims.

Claims

1. A forehead temperature measurement system, comprising: A first image sensor, the first image sensor is used to output a first image frame; a second image sensor; a first temperature sensor configured to output a first thermal image; and a processor coupled to the first image sensor, the second image sensor, and the first temperature sensor, and configured to: Identify a first forehead region according to the first image frame and calculate the forehead area, When the forehead area is greater than the area threshold, the first forehead area is mapped to the first thermal image and the forehead temperature is measured accordingly; and When the forehead area is smaller than the area threshold, the second image sensor is controlled to acquire a second image frame, wherein: A second occupied area of ​​the forehead area in the second image frame is larger than a first occupied area in the first image frame, so as to improve measurement accuracy.

2. The forehead temperature measurement system according to claim 1, wherein: The second viewing angle of the second image sensor is smaller than the first viewing angle of the first image sensor.

3. The forehead temperature measurement system according to claim 1, wherein: When the forehead area is greater than the area threshold, the processor is used to Mapping the first forehead area to the first thermal image to determine a first imaging area, and The measured forehead temperature is determined according to the temperature in the first image area.

4. The forehead temperature measurement system according to claim 1 further comprises a second temperature sensor for outputting a second thermal image, wherein: The second viewing angle of the second temperature sensor is smaller than the first viewing angle of the first temperature sensor.

5. The forehead temperature measurement system according to claim 4, wherein: When the forehead area is smaller than the area threshold, the processor is further configured to: identifying a second forehead area according to the second image frame, mapping the second forehead area to the second thermal image to determine a second imaging area, and The measured forehead temperature is determined according to the temperature in the second image area.

6. The forehead temperature measurement system according to claim 1, wherein: When the forehead area is greater than the area threshold, the processor is used to determining the ambient temperature based on the temperature outside the first image area in the first thermal image, and Correcting the measured forehead temperature according to the forehead area and the ambient temperature, Wherein, when the forehead area is smaller, the correction amount of the measured forehead temperature is larger, and When the forehead area is greater than or equal to the predetermined area, the correction amount is reduced to 0.

7. The forehead temperature measurement system according to claim 1, wherein: The measured forehead temperature is the highest temperature in the first image area in the first thermal image.

8. A forehead temperature measurement system, comprising: A first image sensor, the first image sensor is used to output a first image frame; a first temperature sensor configured to output a first thermal image; and a processor coupled to the first image sensor and the first temperature sensor and configured to: identifying a forehead area according to the first image frame, Mapping the forehead area to the first thermal image to determine the imaging area, Determine the ambient temperature based on the temperature outside the image area, Finding the key pixel with the highest temperature in the image area and identifying the proportion of the forehead area corresponding to the key pixel in the first image frame, and When the ratio is lower than a ratio threshold, the forehead temperature is calculated based on a first product of the ratio of the maximum temperature to the forehead area and a second product of the ratio of the ambient temperature to the non-forehead area.

9. The forehead temperature measurement system according to claim 8, wherein: The ambient temperature is a detected temperature value of pixels adjacent to the key pixel of the highest temperature in the first thermal image.

10. The forehead temperature measurement system according to claim 8, wherein: When the ratio is higher than the ratio threshold, the processor uses the highest temperature as the measured forehead temperature.

11. The forehead temperature measurement system according to claim 8, further comprising a second image sensor and a second temperature sensor, wherein the processor is further configured to calculating the forehead area according to the first image frame, and When the forehead area is smaller than the area threshold, the second image sensor is controlled to acquire a second image frame to replace the first image frame, and the second temperature sensor is controlled to acquire a second thermal image to replace the first thermal image.

12. The forehead temperature measurement system according to claim 11, wherein: The first image sensor and the first temperature sensor have a first viewing angle, and The second image sensor and the second temperature sensor have a second viewing angle smaller than the first viewing angle.

13. A forehead temperature measurement system, comprising: An image sensor, the image sensor being used to output an image frame; a temperature sensor for outputting a thermal image; and A processor coupled to the image sensor and the temperature sensor and configured to: identifying a forehead area according to the image frame, Mapping the forehead area to the thermal image to determine the imaging area, The highest temperature in the image area is taken as the measured forehead temperature, and Correcting the measured forehead temperature according to the uniformity of the temperature difference between the measured forehead temperature and the adjacent temperatures of the measured forehead temperature, in, When the uniformity is low, the correction amount is large, and when the uniformity is high, the correction amount is small.

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