Forehead temperature gun

Abstract

The utility model relates to non -contact infrared temperature measurement technical field discloses a kind of forehead temperature gun, including projection light path component and body temperature measurement component, projection light path component includes sequentially arranged point light source, optical image, plano-convex lens and double convex lens from inside to outside, point light source, optical image, plano-convex lens and double convex lens coaxial arrangement, the plane of plano-convex lens is towards point light source arrangement;The divergent light emitted by point light source is collimated as approximately parallel light by plano-convex lens, then double convex lens is used to focus and / or enlarge parallel light, the symmetric structure of double convex lens balances light path, and the overall aberration of projection light path component is reduced in cooperation with plano-convex lens, to further improve the definition and stability of imaging surface;Projection light path component and body temperature measurement component are arranged at an angle, and the projection positioning area of projection light path component and temperature measurement area are overlapped. Stable optical positioning, accurate control measurement distance and optimization aberration can be realized.

Description

Technical Field

[0001] This utility model relates to the field of non-contact infrared temperature measurement technology, and in particular, to a forehead thermometer. Background Technology

[0002] A thermometer is a medical instrument used to measure human body temperature. Traditional mercury thermometers use the principle of mercury expansion when heated to measure temperature. However, because mercury is toxic, improper use or damage may cause harm to human health and the environment. Therefore, they have been gradually replaced by electronic thermometers.

[0003] Electronic thermometers typically use infrared sensors to detect infrared signals emitted by the human body. They offer advantages such as rapid temperature measurement, digital display, and durability. Among them, non-contact infrared thermometers are widely used in medical and public places due to their ease of use and ability to avoid cross-infection.

[0004] However, existing non-contact infrared thermometers still have the following technical problems:

[0005] 1. Measurement accuracy is affected by distance: Non-contact measurement requires maintaining a suitable detection distance, but it is difficult for users to intuitively judge the best measurement position. Too close or too far a distance will lead to increased temperature measurement error and affect the reliability of the measurement results.

[0006] 2. Insufficient stability of the optical system: Some thermometers use parabolic mirrors to focus infrared light, but the processing and assembly precision of parabolic mirrors are high, the focusing effect is easily affected by assembly and adjustment deviations, and the fixed structure of the light source is unstable, which can easily lead to an increase in the production defect rate.

[0007] 3. Poor aberration control: Some solutions use lens combinations, but due to unreasonable lens arrangement, the image plane curvature is aggravated, especially at the edge of the field of view, resulting in a mismatch between the image plane and the sensor plane, which in turn reduces the temperature measurement accuracy. Utility Model Content

[0008] This invention provides a forehead thermometer that can achieve stable optical positioning, precise control of measurement distance, and optimization of aberrations, thereby solving the technical problems of large measurement errors, complex assembly, and insufficient stability of the optical system in the prior art.

[0009] This utility model provides a forehead thermometer, including a projection optical path assembly and a body temperature measurement assembly. The projection optical path assembly includes a point light source, an optical image, a plano-convex lens, and a biconvex lens arranged sequentially from the inside out. The point light source, optical image, plano-convex lens, and biconvex lens are coaxially arranged, with the plane of the plano-convex lens facing the point light source. The plano-convex lens collimates the diverging light emitted from the point light source into approximately parallel light, and the biconvex lens focuses and / or amplifies the parallel light. The symmetrical structure of the biconvex lens balances the light path, and works in conjunction with the plano-convex lens to reduce the overall aberration of the projection optical path assembly, thereby improving the clarity and stability of the imaging surface. The projection optical path assembly and the body temperature measurement assembly are arranged at an angle, and the projection positioning area of ​​the projection optical path assembly overlaps with the temperature measurement area.

[0010] Furthermore, the angle C between the central axis of the projection optical path assembly and the central axis of the body temperature measurement assembly is 10°-20°.

[0011] Furthermore, the distance 'a' between the center of the convex surface of the biconvex lens facing the plano-convex lens and the center of the convex surface of the plano-convex lens is 5 mm to 10 mm.

[0012] Furthermore, the distance b from the light-emitting center of the point light source to the center of the plano-convex lens plane is 15 mm to 20 mm.

[0013] Furthermore, the outer diameter of the biconvex lens is 6mm-8mm, and / or the outer diameter of the planoconvex lens is 7mm-9mm.

[0014] Furthermore, the projection optical path assembly also includes a lens sleeve, a lens bracket, and a light-shielding bracket; the biconvex lens, the lens sleeve, and the plano-convex lens are sequentially installed into the lens bracket from the outside to the inside; the optical image is attached to the light-shielding bracket, and the light source emitted by the point light source is wrapped by the light-shielding bracket, so that the light source can only be incident on the plano-convex lens after passing through the optical image.

[0015] Furthermore, the body temperature measurement component includes a temperature probe, a probe bracket, and a control board; the temperature probe is connected to the projection optical path component through the probe bracket, the temperature probe is electrically connected to the control board, and the point light source is arranged on the control board and electrically connected to the control board.

[0016] Furthermore, the forehead thermometer also includes a back cover, a front cover, and a battery door; the projection light path assembly and the body temperature measurement assembly are assembled inside the front cover, and a light-transmitting window is provided on the front cover corresponding to the projection light path assembly, and a detection window is provided on the front cover corresponding to the body temperature measurement assembly.

[0017] Furthermore, the rear cover is equipped with a display screen and buttons. The display screen is electrically connected to the control board, and the buttons are mounted on the control board. The battery is located in the area enclosed by the rear cover and the front cover and is sealed through the battery door.

[0018] Furthermore, the display lens and back cover are molded into an integral structure through secondary injection molding or two-color injection molding.

[0019] This utility model has the following beneficial effects:

[0020] 1. By forming a clear projection positioning spot through the projection optical path component, the projection positioning area overlaps with the temperature measurement area, allowing users to intuitively judge the optimal measurement distance and avoid temperature measurement errors caused by distance deviation, thereby solving the problem of "users having difficulty judging the detection distance" in the background technology.

[0021] 2. A combination structure of plano-convex lens and biconvex lens with the plane facing the point light source is adopted. The plano-convex lens is responsible for collimating and diffusing light, while the biconvex lens is responsible for focusing / magnifying. The two work together to reduce aberrations such as spherical aberration and coma, ensuring the sharpness of the edge of the projected light spot and avoiding the problem of "image plane curvature causing sensor plane mismatch" in the background technology.

[0022] 3. The combination of plano-convex lens and biconvex lens makes the processing and assembly easier and the light source fixing structure more stable, thereby reducing the production defect rate and solving the defects of "complex assembly of parabolic mirror and unstable fixing of light source" in the background technology.

[0023] In addition to the objectives, features, and advantages described above, this utility model has other objectives, features, and advantages. The present utility model will now be described in further detail with reference to the figures. Attached Figure Description

[0024] The accompanying drawings, which form part of this utility model, are used to provide a further understanding of the utility model. The illustrative embodiments of the utility model and their descriptions are used to explain the utility model and do not constitute an undue limitation of the utility model. In the drawings:

[0025] Figure 1 This is a schematic diagram of the projection optical path assembly and body temperature measurement assembly of the forehead thermometer according to a preferred embodiment of the present invention;

[0026] Figure 2 This is a cross-sectional structural diagram of a forehead thermometer according to a preferred embodiment of the present invention;

[0027] Figure 3 This is a schematic diagram of the optical positioning and ranging component of a preferred embodiment of the present invention.

[0028] Figure 4 This is a schematic diagram showing the relationship between the projection optical path component, the body temperature measurement component, and the temperature measurement distance in a preferred embodiment of this utility model.

[0029] Legend:

[0030] 100. Projection optical path assembly; 101. Point light source; 102. Optical image; 103. Plano-convex lens; 104. Biconvex lens; 105. Lens sleeve; 106. Lens bracket; 107. Light-shielding bracket; 200. Body temperature measurement assembly; 201. Temperature probe; 202. Probe bracket; 203. Control board; 300. Rear cover; 301. Display screen; 3011. Lens; 302. Button; 400. Front cover; 401. Light-transmitting window; 402. Detection window; 500. Battery door; 600. Battery. Detailed Implementation

[0031] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the present invention can be implemented in many different ways as defined and covered below.

[0032] Figure 1 This is a schematic diagram of the projection optical path assembly and body temperature measurement assembly of the forehead thermometer according to a preferred embodiment of the present invention; Figure 2 This is a cross-sectional structural diagram of a forehead thermometer according to a preferred embodiment of the present invention; Figure 3 This is a schematic diagram of the optical positioning and ranging component of a preferred embodiment of the present invention. Figure 4 This is a schematic diagram showing the relationship between the projection optical path component, the body temperature measurement component, and the temperature measurement distance in a preferred embodiment of this utility model.

[0033] like Figure 1 and Figure 2As shown, the forehead thermometer of this embodiment includes a projection optical path assembly 100 and a body temperature measurement assembly 200. The projection optical path assembly 100 includes a point light source 101, an optical image 102, a plano-convex lens 103, and a biconvex lens 104 arranged sequentially from the inside to the outside. The point light source 101, the optical image 102, the plano-convex lens 103, and the biconvex lens 104 are arranged coaxially, with the plane of the plano-convex lens 103 facing the point light source 101. The plano-convex lens 103 collimates the diverging light emitted by the point light source 101 into approximately parallel light, and the biconvex lens 104 focuses and / or magnifies the parallel light. The symmetrical structure of the biconvex lens 104 balances the light path and works in conjunction with the plano-convex lens 103 to reduce the overall aberration of the projection optical path assembly 100, thereby improving the clarity and stability of the imaging surface. The projection optical path assembly 100 and the body temperature measurement assembly 200 are arranged at an angle, and the projection positioning area of ​​the projection optical path assembly 100 overlaps with the temperature measurement area. This invention relates to a forehead thermometer. Through a projection optical path assembly 100 (i.e., a point light source 101, an optical image 102, a plano-convex lens 103, a biconvex lens 104, and an output lens arranged sequentially), a clear projection positioning spot is formed, causing the projection positioning area to overlap with the temperature measurement area. This allows the user to intuitively determine the optimal measurement distance, avoiding temperature measurement errors caused by distance deviations, thus solving the problem of "users having difficulty judging the detection distance" in the prior art. The thermometer employs a combination structure of a plano-convex lens 103 and a biconvex lens 104, with the plano-convex lens 103 collimating the diverging light to approximately parallel or parallel light, and the biconvex lens 104... Lens 104 is responsible for focusing / magnifying parallel light. Together, they reduce aberrations such as spherical aberration and coma, ensuring the sharpness of the projected light spot edge and avoiding the problem of "image plane curvature causing sensor plane mismatch" in the background technology. The use of a plano-convex lens 103 and a biconvex lens 104 in a coordinated combination structure makes the processing and assembly more difficult and the light source fixing structure more stable, thereby reducing the production defect rate and solving the defects of "complex assembly of parabolic mirror and unstable light source fixing" in the background technology. While ensuring temperature measurement accuracy, it also takes into account the stability of the optical system and the convenience of user operation, meeting the requirements of high precision and ease of use of non-contact thermometers.

[0034] Aberration compensation mechanism: When collimated, a plano-convex lens will introduce a large spherical aberration because the plane faces the light source; the symmetrical refraction of a biconvex lens can make the focal point of the peripheral rays closer to that of the central ray, indirectly compensating for the aberrations of the previous stage; if the distance between the two lenses meets the confocal condition (such as the image-side focal point of the plano-convex lens coincides with the object-side focal point of the biconvex lens), the aberration can be further optimized.

[0035] Sharpness mechanism: The symmetry of the biconvex lens can reduce spot distortion, astigmatism and field curvature, thereby improving sharpness.

[0036] Stability mechanism: The collimated parallel light is less sensitive to the positional shift of the biconvex lens (compared to divergent light), thereby reducing the impact of assembly tolerances on the optical path and improving stability.

[0037] like Figure 1 and Figure 2 As shown, in this embodiment, the angle C between the central axis of the projection optical path assembly 100 and the central axis of the body temperature measurement assembly 200 is 10°-20°. Optimizing the overlap between the projection and temperature measurement areas, by reasonably controlling the angle C between the optical axes of the two components (10°-20°), ensures that the positioning light spot projected by the projection optical path assembly 100 and the infrared temperature measurement area of ​​the body temperature measurement assembly 200 precisely overlap at the target distance (e.g., 1cm-5cm). This avoids projection offset, temperature measurement deviation, or temperature measurement blind zone caused by excessively high or low parallelism of the optical path, improving the intuitiveness of user alignment and measurement reliability. Reducing optical interference, the angle design avoids cross-reflection between the projection optical path and the infrared temperature measurement optical path at internal optical elements or the inner wall of the lens barrel, reducing stray light interference to the infrared sensor, thereby improving the purity and accuracy of the temperature measurement signal. Ergonomically designed with an angle of 10°-20°, this handheld forehead thermometer aligns with the natural usage angle of the device. Users can easily position the temperature sensor directly on their forehead without significantly adjusting their wrist, while visually observing the projected light spot, thus improving operational comfort and measurement efficiency. The angle design strikes a balance between optical performance and user experience, ensuring both accurate projection positioning and temperature measurement while avoiding optical path interference and operational inconvenience.

[0038] like Figure 2As shown, in this embodiment, the distance 'a' from the center of the convex surface of the biconvex lens 104 facing the plano-convex lens 103 to the center of the convex surface of the plano-convex lens 103 is 5 mm to 10 mm. Controlling the distance 'a' within the range of 5 mm to 10 mm ensures that the approximately parallel light collimated by the plano-convex lens 103 obtains the optimal incident angle on the biconvex lens 104, allowing the light to form a clear and stable focused spot after passing through the biconvex lens 104. Too small a distance will cause excessive light convergence, increasing spherical aberration; too large a distance will reduce light energy utilization and affect projection brightness. When the distance 'a' is controlled within the range of 5 mm to 10 mm, the plano-convex lens 103 and the biconvex lens 104 can produce a synergistic effect, effectively compensating for each other's aberrations. The spherical aberration characteristics of the plano-convex lens 103 and the symmetrical refractive characteristics of the biconvex lens 104 work together to reduce the overall spherical aberration and coma of the system, improving the sharpness of the projection edges. By controlling the distance 'a' within the range of 5mm-10mm, the miniaturization of the projection optical path assembly 100 is achieved while ensuring optical performance. This keeps the overall structure of the forehead thermometer compact and easy to handle. It avoids the increased size of the thermometer caused by excessively large optical element spacing, while also preventing assembly difficulties and optical path interference problems caused by excessively small spacing. Controlling the distance 'a' within the range of 5mm-10mm provides sufficient operating space for lens fixing and adjustment, reducing production assembly difficulty, improving product yield and consistency, and ensuring the stability of the optical system.

[0039] like Figure 2 As shown, in this embodiment, the distance b from the light-emitting center of the point light source 101 to the center of the plane of the plano-convex lens 103 is 15mm-20mm. This distance ensures that the point light source 101 is within the effective collimation working distance of the plano-convex lens 103, allowing the diverging light to form a high-quality, nearly parallel beam after passing through the plano-convex lens 103. Too close a distance would result in an excessively large beam divergence angle, reducing the collimation effect; too far a distance would decrease light energy utilization, affecting projection brightness. With a distance of 15mm-20mm, the plano-convex lens 103 can achieve optimal shape control of the light emitted from the point light source 101, forming a clear-edged, uniformly bright central optical path, providing ideal optical input conditions for the subsequent focusing / magnification of the biconvex lens 104. The design of a distance b of 15mm-20mm ensures sufficient assembly tolerances while avoiding lens edge effects caused by improper distance, allowing the optical system to maintain stable performance under conditions such as temperature changes or mechanical vibrations. The distance b is 15mm-20mm, which achieves the best balance between light energy collection efficiency and optical performance, making full use of the radiation energy of the point light source 101 while avoiding thermal interference caused by excessively close distance.

[0040] like Figure 2As shown, in this embodiment, the outer diameter of the biconvex lens 104 is 6 mm-8 mm, and / or the outer diameter of the plano-convex lens 103 is 7 mm-9 mm. The outer diameter of the plano-convex lens 103 is designed to be 7-9 mm, and the outer diameter of the biconvex lens 104 is designed to be 6-8 mm. This ensures that the lens has sufficient light-passing aperture, which can effectively collect and transmit light energy while maintaining a reasonable edge thickness. An outer diameter that is too small will limit the light flux and reduce the projection brightness; an outer diameter that is too large will result in the lens edge being too thin, affecting the structural strength. This allows the lens to effectively control the incident angle of edge light while maintaining an appropriate aperture, thereby suppressing aberrations such as spherical aberration and coma, and improving the overall quality of the projection spot. A balance is achieved between optical performance and structural compactness, ensuring sufficient optical performance while allowing the entire projection optical path assembly 100 to be integrated into the limited space of the forehead thermometer, facilitating the miniaturization of the product. It conforms to the processing standards of conventional optical lenses, avoiding increased processing difficulty due to excessively small size and material waste due to excessively large size, which helps control production costs and ensure product consistency.

[0041] like Figure 1 and Figure 2As shown, in this embodiment, the projection optical path assembly 100 further includes a lens sleeve 105, a lens bracket 106, and a light-shielding bracket 107. The biconvex lens 104, lens sleeve 105, and plano-convex lens 103 are sequentially installed into the lens bracket 106 from the outside in. The optical image 102 is attached to the light-shielding bracket 107, which encloses the light source emitted by the point light source 101, ensuring that the light source can only pass through the optical image 102 and then enter the plano-convex lens 103. Through the precise fit between the lens sleeve 105 and the lens bracket 106, strict coaxiality and spacing accuracy (distance a controlled within 5mm-10mm) are ensured between the biconvex lens 104 and the plano-convex lens 103, avoiding optical path offset due to assembly deviations and guaranteeing the positioning accuracy of the projection spot. The light-shielding bracket 107 completely encloses the point light source 101, forming a closed optical path structure. This effectively blocks direct leakage of light from the light source or stray light reflected from the inner wall of the lens barrel, ensuring that light can only enter the lens system after passing through the optical image 102, significantly improving projection contrast and signal-to-noise ratio. The layered assembly of the lens sleeve 105 and lens bracket 106, along with the modular design of the light-shielding bracket 107, enables precise positioning and convenient assembly of optical components, reducing production and debugging difficulties. The stepped structure of the lens bracket 106 provides respective positioning reference surfaces for the biconvex lens 104 and the plano lens 103, ensuring a controllable distance tolerance of 5mm-10mm. The light source encapsulation structure of the light-shielding bracket 107 also provides thermal insulation, preventing the heat from the point light source 101 from being directly conducted to the lens group, avoiding lens deformation or refractive index changes caused by temperature variations, and maintaining the stability of the optical system during long-term use. The multi-layered bracket structure forms a physical barrier, preventing external dust from entering the optical channel and adhering to the lens surface, maintaining consistent optical performance over long-term use.

[0042] like Figure 1 and Figure 2As shown, in this embodiment, the body temperature measurement component 200 includes a temperature probe 201, a probe bracket 202, and a control board 203. The temperature probe 201 is connected to the projection optical path component 100 via the probe bracket 202, and is electrically connected to the control board 203. The point light source 101 is mounted on the control board 203 and electrically connected to it. The temperature probe 201 and the projection optical path component 100 are rigidly connected via the probe bracket 202, ensuring that their central axes maintain a fixed angle of 10°-20°, thus achieving mechanical overlap between the projection positioning area and the temperature measurement area. The control board 203 integrates the circuitry of both the point light source 101 and the temperature probe 201, reducing cable crossover interference and improving signal transmission stability. The temperature probe 201 (such as an infrared sensor) and the point light source 101 (such as an LED) are arranged in sections on the control board 203. Heat diffusion is achieved through the copper layer of the circuit board to avoid local overheating affecting the sensor accuracy. The physical isolation of the probe bracket 202 can block the heat conduction from the light source to the temperature probe 201, reducing the impact of thermal noise on the infrared signal. Optionally, the temperature probe 201, point light source 101, etc. are connected to the control board 203 through sockets or pads, which supports quick replacement of faulty components, reduces maintenance costs, and keeps the original calibration parameters of the optical components unchanged.

[0043] like Figure 2As shown, in this embodiment, the forehead thermometer also includes a rear cover 300, a front cover 400, and a battery door 500. The projection light path assembly 100 and the body temperature measurement assembly 200 are assembled inside the front cover 400, and a light-transmitting window 401 is provided on the front cover 400 corresponding to the projection light path assembly 100, and a detection window 402 is provided on the front cover 400 corresponding to the body temperature measurement assembly 200. The front cover 400 houses the projection light path assembly 100 and the body temperature measurement assembly 200, preventing external dust, moisture, or physical collisions from damaging the precision optical components and sensors. The light-transmitting window 401 (corresponding to the projection light path) and the detection window 402 (corresponding to the temperature probe 201) are made of high-transmittance materials (such as optical-grade acrylic or coated glass), forming a sealed barrier while ensuring functionality and improving the overall protection level of the device. Optionally, the light-transmitting window 401 and the detection window 402 can also be an integrated window. The aperture and position of the light-transmitting window 401 are precisely matched to the emission angle of the projection optical path assembly 100 to avoid light obstruction or stray reflections introduced by the window edge. The detection window 402 optimizes the transmittance for the infrared temperature measurement band and filters out visible light interference, ensuring that the temperature probe 201 receives a pure infrared radiation signal. The physical separation design of the light-transmitting window 401 and the detection window 402 intuitively guides the user to the correspondence between the projection positioning area and the temperature measurement area. Combined with the 10°-20° optical axis angle, it naturally guides the user to maintain the correct measurement posture (such as aligning the detection window 402 with the forehead while observing the position of the projected light spot). The front cover 400 and the rear cover 300 are fastened together to form a closed cavity, which can buffer the impact of sudden changes in ambient temperature on internal components and avoid drift errors of the temperature probe 201 caused by rapid heat absorption / release of the shell. The independent design of the battery door 500 isolates the conduction interference of the battery 600's heat to the optical components, and also facilitates the replacement or removal of the battery 600 for charging. The front cover 400 and rear cover 300 are designed to be detachable and separate, which facilitates the calibration of the optical path and probe during assembly. At the same time, it supports quick replacement of damaged light-transmitting window 401 or detection window 402 or internal components, reducing maintenance costs.

[0044] like Figure 2As shown, in this embodiment, the rear cover 300 is equipped with a display screen 301 and buttons 302. The display screen 301 is electrically connected to the control board 203, and the buttons 302 are mounted on the control board 203. The battery 600 is located in the area enclosed by the rear cover 300 and the front cover 400 and is sealed by the battery door 500. The display screen 301 (such as OLED or LCD) and the buttons 302 (mechanical or touch-sensitive) are centrally arranged on the rear cover 300, forming an ergonomic operating interface. Users can complete power-on, mode switching, and data viewing with one hand. The display screen 301 displays the temperature value and measurement status (such as distance prompts) in real time, and the buttons 302 perform their functions through the control board 203, reducing the probability of misoperation. The battery 600 is placed in an independent cavity formed by the rear cover 300 and the front cover 400, and is physically isolated by the battery door 500. This avoids the battery 600 heating up (such as lithium battery charging and discharging) from directly affecting the accuracy of the temperature probe 201, and also utilizes the space of the rear cover 300 to disperse the heat source. The short wiring between the control board 203 and the display screen 301 reduces signal attenuation and electromagnetic interference. The battery 600 (such as a CR2032 button cell battery or AA battery) connects to the control board 203 via the flexible contacts of the battery door 500, ensuring stable power supply. The snap-fit ​​or threaded sealing design of the battery door 500 prevents the battery 600 from loosening and falling out, while also meeting the need for quick replacement and extending the device's battery life. The enclosing structure of the back cover 300 and the front cover 400 forms an integral rigid support, protecting the internal optical and electronic components from compression and deformation. The display screen 301 is embedded in the recess of the back cover 300, and the buttons 302 adopt a recessed or flush design, jointly reducing the risk of damage during transportation or drops. The travel and damping coefficient of the buttons 302 are optimized (e.g., actuation force of 0.5-1N) to avoid accidental triggering and power consumption in a pocket.

[0045] like Figure 2 As shown, in this embodiment, the lens 3011 of the display screen 301 and the back cover 300 are integrally formed by secondary injection molding or two-color injection molding. This one-piece molding process eliminates the seams and gaps of traditional assembled lenses, completely preventing moisture and dust from seeping into the internal circuitry from the edge of the display screen, thus avoiding short circuits in the control board 203 or fogging and malfunction of the display screen 301 due to ambient humidity. The integral load-bearing structure formed by secondary injection molding or two-color injection molding of the lens 3011 and the back cover 300 improves impact resistance and prevents the lens from breaking or falling off under pressure.

[0046] In practice, a non-contact infrared thermometer with light projection positioning for optimal measurement is provided to address the pain point that users cannot clearly understand the detection range of the infrared sensor when using a thermometer. This not only improves detection accuracy but also makes operation very convenient.

[0047] The forehead thermometer includes: a lens holder 106, a temperature probe 201, a biconvex lens 104, a lens sleeve 105, a plano-convex lens 103, a lens sealing ring, a projection film (optical image 102), a light-shielding bracket 107, a surface-mount LED (point light source 101), a control board 203, a probe holder 202, a front cover 400, a rear cover 300, a battery door 500, and a battery 600. Other components include a mute button (button 302), a mute button control board (electrically connected to control board 203), a backlight panel, an LCD (display screen 301), an LCD mounting bracket, a conductive strip, a negative electrode spring, positive and negative electrode springs, a positive electrode spring, a button silicone sealing ring, a speaker, a lens 3011, and a measurement button (button 302).

[0048] like Figure 1 and Figure 2 As shown, one side of the plano-convex lens 103 is a flat surface, and the other side is an outwardly convex spherical surface. When the plano-convex lens 103 focuses light, the flat side faces the incident direction of the light, and the convex side faces the refraction direction of the light. The plano-convex lens 103 is used to collimate the light emitted from the point light source 101 into parallel light. Through the plano-convex lens 103, an inverted image is formed at the same size. In practical applications, due to the special properties of the plano-convex lens 103, the spherical shape of the plano-convex lens 103 will inevitably cause the focal positions of the peripheral rays and paraxial rays to be different, resulting in blurred images. Therefore, a biconvex lens 104 is needed to correct aberrations and optimize imaging.

[0049] Both surfaces of the biconvex lens 104 are outwardly convex spherical surfaces. When light passes through the biconvex lens 104, it is refracted towards the central axis. When light rays parallel to the principal axis are incident on the biconvex lens 104, after two refractions, the light rays converge at the focal point on the other side of the biconvex lens 104. Due to the symmetry of the biconvex lens 104, the spherical aberration caused by the plano-convex lens 103 is reduced, resulting in a clearer and more stable image.

[0050] By using a combination of plano-convex lens 103 and biconvex lens 104, the plano-convex lens 103 first collimates the point light emitted by the patch LED (point light source 101) into parallel light, and then the biconvex lens 104 refracts and magnifies the parallel light onto the imaging surface.

[0051] This invention relates to a forehead thermometer. First, a plano-convex lens 103 collimates the point light emitted by the patch LED (point light source 101) into parallel light. Then, a biconvex lens 104 refracts and magnifies the parallel light onto the imaging surface. By utilizing the collimating light source property of the plano-convex lens 103 and the symmetry with the biconvex lens 104, the spherical aberration caused by the plano-convex lens 103 is reduced, resulting in a clearer and more stable image.

[0052] The diverging light is collimated into approximately parallel light by a plano-convex lens 103 (with its plane facing the point light source 101), and then the parallel light is focused or magnified by a biconvex lens 104. The symmetrical structure of the biconvex lens 104 can balance the light path and work in conjunction with the plano-convex lens 103 to reduce the overall aberrations of the system (such as spherical aberration and coma), thereby improving the sharpness and stability of the imaging plane.

[0053] Aberration compensation mechanism:

[0054] 1. When collimating, the plano-convex lens 103 will introduce a large spherical aberration because its plane faces the light source; the symmetrical refraction of the biconvex lens 104 can make the focal point of the peripheral rays and the central rays closer, indirectly compensating for the aberration of the previous stage.

[0055] 2. If the distance between the two lenses meets the confocal condition (e.g., the image-side focal point of the plano-convex lens 103 coincides with the object-side focal point of the biconvex lens 104), the aberration can be further optimized.

[0056] Sources of clarity and stability:

[0057] 1. Sharpness: The symmetry of the biconvex lens 104 reduces spot distortion, astigmatism, and field curvature.

[0058] 2. Stability: The collimated parallel light is not sensitive to the positional deviation of the biconvex lens 104 (compared to divergent light), reducing the impact of assembly tolerances on the system.

[0059] This utility model of a forehead thermometer, by placing a patch LED (point light source 101) on a circuit board (control board 203), and fastening the projection light path assembly 100 between a lens bracket 106 and a light shield bracket 107, with the lens bracket 106 positioned to the front cover 400 by screws and the light shield bracket 107 positioned to the circuit board (control board 203) by screws, and setting a lens sleeve 105 to fix two lenses (plano-convex lens 103 and biconvex lens 104), the multi-layered tight fixing position can significantly improve the system reliability of the patch LED (point light source 101) and the projection light path assembly 100.

[0060] Working principle: such as Figure 3 As shown, when the non-contact infrared thermometer (forehead thermometer) is working, the LCD display screen (display screen 301) is electrically connected to the main control circuit board (control board 203). The display screen 301 displays the body temperature value detected by the infrared sensor. At the same time, the surface-mount LED emits light to project the circular pattern on the projection film onto the surface of the object being measured (the surface of the target object) through the plano-convex lens 103 and the biconvex lens 104. At this time, a clear and magnified projected circular pattern is displayed, and the measurement distance of the thermometer is optimal.

[0061] Infrared temperature measurement and projection positioning structure, such as Figure 2As shown, the temperature probe 201 is fixed to the lens bracket 106 by screws on the probe bracket 202, and the lens bracket 106 is fixed to the front cover 400 by screws on the probe bracket 202. The projection optical path assembly 100 is installed inside the housing of the infrared thermometer (forehead thermometer) and is tilted at a certain angle to the temperature probe 201, so that the temperature measuring area of ​​the probe and the projection positioning area overlap. The projection optical path assembly 100 is sequentially installed into the lens bracket 106 via a biconvex lens 104, a lens sleeve 105, and a plano-convex lens 103. The lens is then secured with a lens sealing ring. The projection film is attached to a light-shielding bracket 107, which encloses the light source emitted by the surface-mount LEDs on the control board 203, ensuring that the light source can only be amplified and scattered in parallel through the projection film, plano-convex lens 103, and biconvex lens 104. The control board 203 is fixed to the front cover 400 with screws. The projection pattern is determined by the pattern on the projection film. When the body temperature measurement distance is 5cm, the projection pattern is magnified 4 times, and the projection effect is clear. When the measurement distance is greater than 5cm, the projection pattern is blurry, indicating to the user that the measurement is outside the range.

[0062] like Figure 2 As shown, the angle C between the projection optical path assembly 100 and the central axis of the temperature probe 201 is within the range of 15±5 degrees for optimal projection effect. 'a' represents the distance from the center of the convex surface of the biconvex lens 104 to the center of the convex surface of the plano-convex lens 103, and 'b' represents the distance from the light-emitting center of the SMD LED to the center of the plane of the plano-convex lens 103. The optimal range for 'a' is 5mm to 10mm, and the optimal range for 'b' is 15mm to 20mm. The outer diameter of the biconvex lens 104 ranges from 6mm to 8mm, and the outer diameter of the plano-convex lens 103 ranges from 7mm to 9mm. In this embodiment, the focal length of the biconvex lens 104 is 8mm to 15mm. Preferably, the focal length of the biconvex lens 104 is 11mm.

[0063] The optimal temperature measurement distance for non-contact infrared thermometers (forehead thermometers) is 1 cm to 5 cm. Figure 3 and Figure 4 The display shows that when the temperature measurement distance is 5 cm, the projection area of ​​the projected light overlaps with the measurement area of ​​the temperature probe 201, which indicates that the projection light source can better locate the temperature and improve the measurement accuracy. Among them, 7 is the projection film, and the five small circles in the middle are the projection pattern.

[0064] Any matters not covered in this utility model are common knowledge.

[0065] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0066] The embodiments described above are merely illustrative of several implementations of this utility model, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the utility model. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the appended claims.

[0067] The above description is merely a preferred embodiment of this utility model and is not intended to limit the scope of this utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A forehead thermometer, comprising a projection optical path assembly (100) and a body temperature measurement assembly (200), characterized in that, The projection optical path assembly (100) includes a point light source (101), an optical image (102), a plano-convex lens (103), and a biconvex lens (104) arranged sequentially from the inside to the outside. The point light source (101), the optical image (102), the plano-convex lens (103), and the biconvex lens (104) are arranged coaxially, and the plane of the plano-convex lens (103) is arranged facing the point light source (101). The divergent light emitted from the point light source (101) is collimated into approximately parallel light by a plano-convex lens (103), and then the parallel light is focused and / or magnified by a biconvex lens (104). The symmetrical structure of the biconvex lens (104) balances the light path and works in conjunction with the plano-convex lens (103) to reduce the overall aberration of the projection light path assembly (100), thereby improving the clarity and stability of the imaging surface. The projection optical path assembly (100) and the body temperature measurement assembly (200) are arranged at an angle, and the projection positioning area of ​​the projection optical path assembly (100) overlaps with the temperature measurement area.

2. The forehead thermometer according to claim 1, characterized in that, The angle C between the central axis of the projection optical path assembly (100) and the central axis of the body temperature measurement assembly (200) is 10°-20°.

3. The forehead thermometer according to claim 1, characterized in that, The distance a from the center of the convex surface of the biconvex lens (104) facing the plano-convex lens (103) to the center of the convex surface of the plano-convex lens (103) is 5 mm to 10 mm.

4. The forehead thermometer according to claim 3, characterized in that, The distance b from the light-emitting center of the point light source (101) to the center of the plane of the plano-convex lens (103) is 15 mm to 20 mm.

5. The forehead thermometer according to claim 4, characterized in that, The outer diameter of the biconvex lens (104) is 6-8 mm, and / or the outer diameter of the plano-convex lens (103) is 7-9 mm.

6. The forehead thermometer according to any one of claims 1 to 5, characterized in that, The projection optical path assembly (100) also includes a lens sleeve (105), a lens bracket (106), and a light shield bracket (107). The biconvex lens (104), lens sleeve (105) and plano-convex lens (103) are sequentially installed into the lens holder (106) from the outside to the inside. The optical image (102) is attached to the light-shielding bracket (107), and the light source emitted by the point light source (101) is wrapped by the light-shielding bracket (107), so that the light source can only be incident on the plano-convex lens (103) after passing through the optical image (102).

7. The forehead thermometer according to any one of claims 1 to 5, characterized in that, The body temperature measurement assembly (200) includes a temperature probe (201), a probe holder (202), and a control board (203); The temperature probe (201) is connected to the projection optical path assembly (100) through the probe bracket (202), the temperature probe (201) is electrically connected to the control board (203), and the point light source (101) is arranged on the control board (203) and electrically connected to the control board (203).

8. The forehead thermometer according to claim 7, characterized in that, The forehead thermometer also includes a back cover (300), a front cover (400), and a battery door (500). The projection light path assembly (100) and the body temperature measurement assembly (200) are assembled inside the front cover (400), and the front cover (400) is provided with a light-transmitting window (401) at the part corresponding to the projection light path assembly (100), and a detection window (402) is provided at the part corresponding to the body temperature measurement assembly (200).

9. The forehead thermometer according to claim 8, characterized in that, The rear cover (300) is equipped with a display screen (301) and buttons (302). The display screen (301) is electrically connected to the control board (203), and the buttons (302) are mounted on the control board (203). The battery (600) is located in the area enclosed by the rear cover (300) and the front cover (400) and is sealed by the battery door (500).

10. The forehead thermometer according to claim 9, characterized in that, The lens (3011) of the display screen (301) and the back cover (300) are integrally formed by secondary injection molding or two-color injection molding.

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