Non-contact human infrared thermometer for optical positioning and distance measurement

Abstract

The present application relates to a kind of optical positioning and distance non-contact human infrared thermometer, the thermometer includes optical positioning distance component, circuit board, forehead temperature head soft glue body, forehead temperature head body, infrared sensor assembly, sensor coupling line, touch pressure button, plastic measurement button, liquid crystal display screen support, liquid crystal display screen, back light plate, conductive strip, plastic memory button, plastic on / off button etc..Forehead temperature head soft glue body is connected as a whole with forehead temperature head body by the way of secondary encapsulation, infrared sensor assembly is installed in forehead temperature head body, tail end is connected with circuit board by sensor coupling line, the plastic measurement button, plastic memory button and plastic on / off button are connected as a whole with upper shell by the way of secondary encapsulation, panel is fixed on upper shell by double-sided adhesive.The technical scheme overcomes the deficiency of prior art in positioning, distance, provides a kind of simple and effective optical positioning and distance non-contact human infrared thermometer.

Description

Technical Field

[0001] This invention relates to a thermometer, specifically to a non-contact infrared thermometer with optical positioning and distance measurement, belonging to the field of medical device technology. Background Technology

[0002] Clinically, body temperature usually refers to the core temperature of the human body. The human body maintains a constant temperature throughout the body primarily through the central nervous system and blood circulation, reflecting this temperature on the body surface. Body temperature measurement involves measuring the temperature at points close to the core temperature. Traditionally, temperature is measured in natural cavities or acupoints, such as the mouth, armpit, and rectum. While the rectum, being an internal organ, best represents the true core temperature and is relatively stable, it is inconvenient and time-consuming to measure, making it unsuitable as a primary measurement method. This is especially true for active infants and young children, where prolonged measurement can affect the continuity and stability of contact between the thermometer and the measurement site, leading to inaccurate or unstable readings. Infrared thermometers, due to their short measurement time and ease of use, have gradually become an important method for measuring body temperature. Non-contact infrared thermometers, in particular, are widely used because they avoid direct contact with the subject, preventing cross-infection. Especially during the pandemic, such products have become the primary way for families, hospitals, communities, enterprises, institutions and other public places to measure body temperature.

[0003] For all non-contact infrared thermometers, accurate positioning and distance from the measurement site are crucial for ensuring measurement accuracy. Excessive measurement distance or incorrect positioning will lead to inaccurate temperature readings. This invention relates to a method and structure for positioning and distance measurement of a non-contact infrared thermometer, applicable to various types of infrared thermometers that measure human body temperature non-contactly. Since the forehead (between the eyebrows) is supplied with blood by the superficial temporal artery originating from the common carotid artery, and is not only close to the heart but also has superficially distributed blood vessels, the temperature at the forehead (between the eyebrows) is relatively close to the body's core temperature, making it an important site for temperature measurement. A non-contact infrared forehead thermometer measures body temperature by sensing the infrared radiation energy emitted from the forehead (between the eyebrows) using an infrared sensor. This invention further elaborates on this non-contact infrared forehead thermometer as an example.

[0004] Currently, there are two distance measurement methods for non-contact infrared thermometers on the market: one is to measure distance using infrared ranging, which increases the complexity of the product and the cost, and can only measure distance but not position; the other is to directly illuminate the thermometer with an LED light, which has poor distance measurement effect and is very unstable. Therefore, there is an urgent need for a new solution to solve the above technical problems. Summary of the Invention

[0005] This invention addresses the problems existing in the prior art by providing a non-contact infrared thermometer for human body with optical positioning and distance determination. This solution overcomes the shortcomings of the prior art in terms of positioning and distance determination.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows: a non-contact infrared thermometer with optical positioning and distance measurement, comprising an optical positioning and distance measurement component, a circuit board, a forehead thermometer soft gel body, a forehead thermometer body, an infrared sensor component, a sensor connecting line, a touch button, a plastic measurement button, an LCD display bracket, an LCD display, a backlight panel, a conductive strip, a plastic memory button, a plastic on / off button, a panel, an upper shell, a lower shell, screws, a battery positive spring, a battery cover, a battery, and a battery negative spring. The forehead thermometer soft gel body is integrated with the forehead thermometer body through a secondary encapsulation method. The infrared sensor component is installed in the forehead thermometer body, and its tail end is connected to the circuit board through a sensor connecting line. The plastic measurement button, the plastic memory button, and the plastic on / off button are integrated with the upper shell through a secondary encapsulation method. The panel is fixed to the upper shell with double-sided adhesive. The LCD display and the backlight panel are installed in the LCD display bracket, and the LCD display bracket is fixed to the circuit board by screws and a hook structure on the bracket. A conductive strip is installed in the LCD screen bracket to achieve electrical conductivity between the LCD screen and the circuit board. Touch buttons are soldered onto the circuit board. The circuit board is secured to the lower casing with screws. The lower ends of the battery positive and negative springs are installed in the battery slots of the lower casing, with the other ends soldered to the circuit board. The battery is installed in the battery slots of the lower casing, with its two ends in contact with the battery positive and negative springs, respectively. The upper and lower casings are fixedly connected by a hook structure and screws. The optical positioning and distance-fixing assembly includes a condenser lens (with a built-in scale), a reflector, a light source, a light source fixing structure, and a light source connecting wire. The reflector is a parabolic mirror with a parabolic inner surface; the light source is positioned by the fixing structure so that the light-emitting center of the light source is exactly at the focal point of the parabola. According to the principle of light reflection, the light emitted by the light source, after being reflected by the parabolic mirror, becomes parallel light parallel to the principal axis of the parabola, thus enhancing the intensity of the light parallel to the principal axis. A condenser lens is provided in front of the reflector, coaxial with the reflector. The condenser lens is equipped with a scale for positioning and distance determination. The scale is set in a cross shape, and the center of the cross is used to determine the measurement position during measurement.

[0007] Furthermore, according to the principle of light refraction and the laws of lens imaging, parallel light rays reflected from a parabolic mirror, parallel to the principal axis, are refracted when passing through a condenser lens and converge at a single point, namely the focal point of the condenser lens. The distance between the focal point and the center of the condenser lens is the focal length of the condenser lens. The scale forms images of different directions and sizes at different distances from the focal point, perpendicular to the principal axis: between the focal point and the condenser lens, an upright image is formed, and the closer to the focal point, the smaller the image; at the focal point, no image is formed, i.e., the shape of the scale is not visible; at positions greater than the focal length of the condenser lens, the scale image is inverted, and the greater the distance from the focal point, the larger the image. The following is the formula for calculating the focal length of a condenser lens:

[0008] 1 / f=(n-1)[1 / R1-1 / R2+(n-1)d / nR1R2]

[0009] In the formula: f is the focal length.

[0010] n is the refractive index of the lens material.

[0011] R1 is the radius of curvature of the first surface of the lens.

[0012] R2 is the radius of curvature of the second surface of the lens.

[0013] d is the thickness at the center of the lens.

[0014] As can be seen from the above formula, the smaller the refractive index n of the lens material, the larger the focal length of the lens.

[0015] If the first surface of the lens is convex, then the value of R1 is positive; if it is concave, then R1 is negative. If the second surface of the lens is concave, then R2 is positive; if it is convex, then R2 is negative.

[0016] As an improvement of the present invention, in the above-mentioned optical positioning and distance-fixing component, the focusing lens is a biconvex lens, or a plano-convex lens, or a concave-convex lens, which is selected and determined according to the size of the product structure space.

[0017] As an improvement of the present invention, in the above-mentioned optical positioning and distance-fixing component, the scale is attached (printed, pasted or affixed) to either the front or rear mirror surface of the condenser lens, or is located in front of or behind the condenser lens, without contacting the condenser lens.

[0018] As an improvement of the present invention, in the above-mentioned optical positioning and distance-determining components, the shape of the scale used for positioning and distance-determining is either orthogonal, oblique, or other that can generate an intersection point.

[0019] As an improvement of the present invention, the scale built into the condenser lens for positioning and distance determination will form an image in front of the condenser lens.

[0020] A design method for a non-contact infrared thermometer with optical positioning and distance determination is disclosed. The method is as follows: In the design of the non-contact infrared thermometer, a calibrated distance is established between the infrared sensor and the measured area. In the optical components, the focal length of the condenser lens is equal to this calibrated distance, and the light source is installed at the focal point of the parabolic mirror. When the infrared thermometer is powered on and enters the temperature measurement state, pressing and holding the plastic measurement button activates the light source. The light is reflected by the parabolic mirror and shines parallel onto the condenser lens. After refraction by the condenser lens, the light converges at the focal point on the other side of the condenser lens. Simultaneously, a scale used for positioning and distance determination forms an image in front of the condenser lens. The intersection point of the scale image is aligned with the forehead of the person being measured. The thermometer is moved towards the forehead, and the scale image gradually decreases in size until it disappears. Continuing to move the thermometer towards the forehead causes the scale image to reappear. During the aforementioned movement, when the scale image disappears, it indicates that the area of ​​the forehead being measured is precisely at the focal point of the condenser lens. In other words, the actual distance between the infrared thermometer sensor and the area of ​​the forehead being measured is exactly equal to the designed calibration distance. At this point, releasing the plastic measurement button initiates automatic temperature measurement, and the thermometer displays the result on the LCD screen. In the aforementioned optical positioning and distance-setting component, the focal length of the condenser lens is the correct measurement distance. Its size is determined by the refractive index n of the lens material, the radius of curvature R1 of the first mirror surface, the radius of curvature R2 of the second mirror surface, and the thickness at the center of the lens. This is selected and determined during the design process based on the product's structural space, material requirements, and other specifications.

[0021] Compared with existing technologies, this invention has the following advantages: 1) This technical solution applies the principles of light reflection and refraction, utilizes the law of reflection of light by a mirror, and the focusing characteristics and imaging laws of a condensing lens, and through precise calculation, not only can the distance between the non-contact infrared thermometer and the measurement site be determined (i.e., distance determination), but also the measurement position can be effectively determined (i.e., positioning), thereby improving the accuracy of infrared thermometer measurement; 2) This invention has a simple structure, is intuitive and easy to operate; 3) This invention is 10% to 15% cheaper than the distance determination method of infrared ranging used in the market, saving costs while ensuring product accuracy, thus enhancing the product's competitive advantage in quality and cost. Attached Figure Description

[0022] Figure 1 Appearance of a non-contact infrared forehead thermometer;

[0023] Figure 2 Cross-sectional view of the assembly of a non-contact infrared forehead thermometer;

[0024] Figure 3 Schematic diagram of a biconvex lens;

[0025] Figure 4 Schematic diagram of a plano-convex lens;

[0026] Figure 5 Schematic diagram of a concave-convex lens;

[0027] Figure 6 Schematic diagram of the optical positioning and ranging component;

[0028] In the diagram: 1. Condensing lens (with scale), 2. Reflector, 3. Light source, 4. Light source mounting junction, 5. Light source connecting wire, 6. Circuit board, 7. Forehead thermometer soft rubber body, 8. Forehead thermometer body, 9. Infrared sensor assembly, 10. Sensor connecting wire, 11, 18, 20. Touch buttons, 12. Plastic measurement button, 13. LCD screen bracket, 14. LCD screen, 15. Backlight panel, 16. Conductive strip, 17. Plastic memory button, 19. Plastic on / off button, 21. Panel, 22. Top 23. Lower shell, 24. Screw, 25. Battery positive terminal spring, 26. Battery cover, 27. Battery, 28. Battery negative terminal spring, 29. Parabolic mirror, 30. Parabolic mirror principal axis, 31. Parabolic mirror focal point, 32. Distance between the parabolic mirror focal point and the center of the condenser lens, 33. Condenser lens focal length, 34. Condenser lens focal point, 35. First curved surface of the condenser lens, 36. Second curved surface of the condenser lens, 37. Condenser lens center thickness, 38. Scale, 39. Upright image of the scale, 40. Inverted image of the scale. Detailed Implementation

[0029] To enhance understanding of the present invention, the embodiments will be described in detail below with reference to the accompanying drawings.

[0030] Example 1: See Figures 1-6A non-contact infrared thermometer with optical positioning and ranging capabilities is disclosed. The thermometer includes an optical positioning and ranging component, a circuit board 6, a forehead thermometer soft gel body 7, a forehead thermometer body 8, an infrared sensor assembly 9, a sensor connection cable 10, touch buttons 11, 18, and 20, a plastic measurement button 12, an LCD screen bracket 13, an LCD screen 14, a backlight panel 15, a conductive strip 16, a plastic memory button 17, a plastic on / off button 19, a panel 21, an upper shell 22, a lower shell 23, screws 24, a battery positive terminal spring 25, a battery cover 26, a battery 27, and a battery negative terminal spring 28. The forehead thermometer soft gel body 7 is integrated with the forehead thermometer body 8 through a secondary encapsulation method. The infrared sensor assembly 9 is installed in the forehead thermometer body, and its tail end is connected to the circuit board 6 via the sensor connection cable 10. The plastic measuring button 12, plastic memory button 17, and plastic on / off button 19 are integrated with the upper shell 22 through a secondary encapsulation process. The panel 21 is fixed to the upper shell 22 with double-sided adhesive. The LCD screen 14 and backlight panel 15 are installed in the LCD screen bracket 13, which is fixed to the circuit board 6 by screws and hooks. The conductive strip 16 is installed in the LCD screen bracket 13 to enable electrical conduction between the LCD screen 14 and the circuit board 6. The touch buttons 11, 18, and 20 are soldered to the circuit board 6. The circuit board 6 is screwed to the lower shell 23. The lower part of the battery positive spring 25 and battery negative spring 28 are installed in the battery slot of the lower shell 23, and the other end is soldered to the circuit board 6. The battery is installed in the battery slot of the lower shell 23, with both ends in contact with the battery positive spring 25 and battery negative spring 28, respectively. The upper shell 22 and the lower shell 23 are fixedly connected by hooks and screws 24. The optical positioning and distance-determining assembly includes a condenser lens (with scale) 1, a reflector 2, a light source 3, a light source fixing structure 4, and a light source connecting line 5. The reflector 2 is a parabolic mirror 29 with a parabolic inner surface. The light source 3 is positioned by the fixing structure 4, ensuring that the light-emitting center of the light source 3 is precisely at the focal point 31 of the parabolic surface. According to the principle of light reflection, the light emitted by the light source 3, after reflection by the parabolic mirror 29, becomes parallel light parallel to the principal axis 30 of the parabolic surface, thus enhancing the intensity of light parallel to the principal axis. A condenser lens 1 is positioned in front of the reflector 2 and is coaxial with it. The condenser lens 1 has a scale 38 for positioning and distance determination. The scale is arranged in a cross shape, and its intersection center is used to determine the measurement position during measurement.

[0031] Furthermore, according to the principle of light refraction and the laws of lens imaging, parallel light rays reflected from the parabolic mirror and parallel to the principal axis 30 are refracted and converge at a single point when passing through the condenser lens 1, namely the focal point 34 of the condenser lens. The distance 33 between the focal point 34 and the center of the condenser lens is the focal length of the condenser lens. The scale forms images of different directions and sizes at different distances from the focal point 34 of the condenser lens, perpendicular to the principal axis 30: between the focal point 34 and the condenser lens 1, an upright image is formed (as shown in the attached diagram). Figure 6 The closer the image is to the focal point of the condenser lens (point 34 in the attached diagram), the smaller the image; at the focal point, no image is formed, meaning the shape of the scale is not visible; at positions greater than the focal length of the condenser lens (33), the image of the scale is inverted, and the greater the distance from the focal point, the larger the image. The following is the formula for calculating the focal length of the condenser lens:

[0032] 1 / f=(n-1)[1 / R1-1 / R2+(n-1)d / nR1R2]

[0033] In the formula: f is the focal length;

[0034] n is the refractive index of the lens material;

[0035] R1 is the radius of curvature of the first surface of the lens;

[0036] R2 is the radius of curvature of the second surface of the lens;

[0037] d is the thickness at the center of the lens.

[0038] As can be seen from the above formula, the smaller the refractive index n of the lens material, the larger the focal length of the lens.

[0039] If the first surface of the lens is convex (see 35 in the attached figure), the value of R1 is positive; if it is concave, the value of R1 is negative. If the second surface of the lens (36 in the attached figure) is concave, the value of R2 is positive; if it is convex, the value of R2 is negative.

[0040] In the aforementioned optical positioning and ranging components, the condenser lens 1 can be a biconvex lens (with attachment). Figure 3 (As shown), a plano-convex lens can also be used (attached). Figure 4 (as shown), or use concave and convex lenses (attached) Figure 5 As shown in the figure, the specific selection and determination depend on the size of the product structure space. In the above-mentioned optical positioning and distance-determining components, the scale (38 in the figure) can be attached (printed, pasted or affixed) to either the front or rear mirror surface of the condenser lens 1 (35 or 36 in the figure), or it can be located on either side of the condenser lens without contacting the condenser lens.

[0041] In the aforementioned optical positioning and distance-measuring components, the shape of the scale used for positioning and distance measurement can be orthogonal, oblique, or any other shape that produces an intersection point. The scale used for positioning and distance measurement (such as...) Figure 6 (38) will form an upright image 39 within the focal length 33 of the condenser lens 1, and an inverted image 40 outside the focal length 33. Example 2: See Example 2. Figures 1-6 A design method for a non-contact infrared thermometer with optical positioning and distance determination is disclosed. The method is as follows: In the design of the non-contact infrared forehead thermometer, a calibrated distance is established between the infrared sensor and the measured area. The focal length 33 of the condenser lens in the aforementioned optical components is equal to this calibrated distance, and the light source 3 is installed at the focal point of the parabolic mirror 29. When the infrared thermometer is powered on and enters the temperature measurement state, the plastic measurement button 12 is pressed and held. The light source 3 is powered on and emits light. The light is reflected by the parabolic mirror 29 and shines parallel onto the condenser lens 1. After refraction by the condenser lens 1, the light converges at the focal point 34 of the condenser lens on the other side. Simultaneously, the scale 38 used for positioning and distance determination during measurement will form an inverted image 40 on the other side of the condenser lens 1. Moving the thermometer towards the forehead, keeping the intersection of the inverted image 40 aligned with the forehead of the person being measured, the inverted image 40 will gradually decrease in size until it disappears. Continuing to move the thermometer towards the forehead, the scale image reappears, this time as a gradually enlarging upright image 39. During this movement, when the scale image disappears, it indicates that the forehead being measured is precisely at the focal point of the condenser lens 1 (point 34 in the attached figure). This means the actual distance between the infrared thermometer sensor and the forehead being measured is exactly equal to the designed calibration distance. Releasing the plastic measurement button 12, the thermometer automatically begins measuring body temperature and displays the result on the volume display screen 14. In the aforementioned optical positioning and distance-setting assembly, the focal length 33 of the condenser lens 1 represents the correct measurement distance. Its size is determined by the lens's refractive index n, the radius R1 of the first mirror surface (point 35 in the attached figure), the radius R2 of the first mirror surface (point 36 in the attached figure), and the thickness of the lens center (point 37 in the attached figure). During the design process, this is selected and determined based on the product's structural space, material requirements, and other factors. Furthermore, the scale can also be placed on either the front or rear surface of the condenser lens (35 or 36 in the attached diagram), or located in front of or behind the lens without contacting it, depending on the actual needs. In this embodiment, the scale is on the original product ( Figure 2 1) is included by default.

[0042] Working principle and process: refer to Figure 1 — Figure 6 A non-contact infrared thermometer for human body with optical positioning and distance measurement. The working principle of the infrared thermometer is as follows.

[0043] All matter in nature with a temperature above absolute zero (-273.15℃) continuously radiates electromagnetic waves, including those in the infrared band, into the surrounding space due to the thermal motion of its molecules. The relationship between the energy density of this radiation and the object's temperature conforms to the law of radiation. According to Stefan and Boltzmann's law of infrared radiation, and considering the influence of the ambient temperature: E = σε(T 4 -T0 4 ).

[0044] In the formula: E is the radiative exit measure, in W / m 2 ;

[0045] σ is the Stefan-Boltzmann constant, 5.67 × 10⁻⁶. -8 W / (m 2 .K);

[0046] ε is the emissivity of the object;

[0047] T is the temperature of the object, in K;

[0048] T0 is the ambient temperature around the object, measured in Kelvin (K).

[0049] By measuring the emitted energy E, the temperature value T can be obtained.

[0050] The human body mainly radiates infrared rays with wavelengths between 9 and 10 μm. Infrared thermometers accurately measure the surface temperature of the human body by measuring the infrared energy radiated by the human body itself.

[0051] Infrared thermometers use infrared sensors to detect infrared radiation energy. The infrared sensor has two components: a thermopile and a thermistor with a negative temperature coefficient. The thermopile has two junctions, a hot junction and a cold junction. The infrared radiation energy sensed at the hot junction creates a voltage difference between the hot and cold junctions; the stronger the infrared radiation, the greater the voltage difference. The thermistor is placed in close contact with the cold junction to measure its temperature.

[0052] The higher the temperature, the stronger the infrared radiation energy. The voltage difference generated by the infrared radiation energy sensed by the thermopile is converted into a corresponding temperature. Then, the resistance value of the negative temperature coefficient thermistor is converted into a temperature value, thus obtaining the temperature of the thermopile's hot-cold junction. The temperature of the hot-cold junction plus the temperature converted from the voltage at the hot-cold junction is the temperature of the object sensed by the thermopile. Infrared thermometers sense the surface temperature of the human body and correct it using data obtained from human clinical trials to finally obtain the human body temperature value.

[0053] It should be noted that the above embodiments are not intended to limit the scope of protection of the present invention. Equivalent transformations or substitutions made based on the above technical solutions all fall within the scope of protection of the claims of the present invention.

Claims

1. A non-contact infrared thermometer for human body with optical positioning and distance measurement, characterized in that, The thermometer includes an optical positioning and ranging component, a circuit board, a forehead thermometer soft gel body, a forehead thermometer body, an infrared sensor component, a sensor connecting wire, a touch button, a plastic measurement button, an LCD screen bracket, an LCD screen, a backlight panel, a conductive strip, a plastic memory button, a plastic on / off button, a panel, an upper shell, a lower shell, screws, a battery positive spring, a battery cover, a battery, and a battery negative spring. The forehead thermometer soft gel body is integrated with the forehead thermometer body through a secondary encapsulation method. The infrared sensor component is installed in the forehead thermometer body, and its tail end is connected to the circuit board through the sensor connecting wire. The plastic measurement button, plastic memory button, and plastic on / off button are integrated with the upper shell through a secondary encapsulation method. The panel is fixed to the upper shell with double-sided tape. The LCD screen and backlight panel are mounted on the LCD screen. In the display stand, the LCD screen bracket is fixed to the circuit board by screws and hooks on the bracket. The conductive strip is installed in the LCD screen bracket to achieve electrical conduction between the LCD screen and the circuit board. The touch button is soldered to the circuit board, which is locked to the lower shell by screws. The lower parts of the battery positive and negative springs are installed in the battery slot of the lower shell, and the other ends are soldered to the circuit board. The battery is installed in the battery slot of the lower shell, with its two ends in contact with the battery positive and negative springs respectively. The upper and lower shells are fixedly connected by hooks and screws. The optical positioning and distance fixing component includes a condenser lens, a scale, a reflector, a light source, a light source fixing structure, and a light source connecting wire. The condenser lens is installed in front of the reflector inside the forehead thermometer body, and the light source is installed at the curved opening of the reflector. The light source is fixed by a fixing structure, and its tail is connected to the circuit board via a light source connection line. The reflector is a parabolic mirror with a parabolic inner surface. The light source is positioned by the fixing structure so that the light-emitting center of the light source is exactly at the focal point of the parabolic mirror. According to the principle of light reflection, the light emitted by the light source is reflected by the parabolic surface and becomes parallel light parallel to the principal axis of the parabola, thus enhancing the intensity of the light parallel to the principal axis. A condensing lens is provided in front of the reflector and is coaxial with the reflector. The condensing lens is a biconvex lens or a plano-convex lens or a concave-convex lens. In a direction perpendicular to the axis of the condenser lens, there is a scale for positioning and distance determination. The scale is set in a cross shape, and its intersection center is used to determine the specific measurement position during measurement. The scale is attached to either the front or rear mirror surface of the condenser lens, or located on either side of the condenser lens, without contacting the condenser lens. In the aforementioned optical positioning and distance-measuring components, the scales used for positioning and distance-measuring are either orthogonally or obliquely intersecting. These scales will be imaged in front of the condenser lens. In the design of non-contact infrared forehead thermometers, there is a calibrated distance between the infrared sensor and the part of the body being measured. This distance ensures that the focal length of the condenser lens in the aforementioned optical components is equal to this calibrated distance. The light source is installed at the focal point of the parabolic mirror. When the infrared thermometer is powered on and enters the temperature measurement state, pressing and holding the plastic measurement button activates the light source. The light is reflected by the parabolic mirror and then shines parallel onto the condenser lens. After refraction by the condenser lens, the light converges at its focal point on the other side of the lens, keeping the intersection of the scale image aligned with the subject's forehead. Position the thermometer at the center of your forehead and move it towards your forehead. You will see an inverted scale image gradually decrease in size until it disappears. Continue moving the thermometer towards your forehead, and an upright image will gradually increase in size. During this process, when the scale image disappears, it indicates that the area of ​​your forehead being measured is exactly at the focal point of the focusing lens. In other words, the actual distance between the infrared thermometer sensor and the area of ​​your forehead being measured is equal to the designed calibration distance. At this point, release the plastic measurement button, and the thermometer will automatically measure your body temperature and display the measurement result on the LCD screen.

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