Condensation Fresnel lens and preparation method thereof

Abstract

The invention relates to the field of illumination, and discloses a condensation Fresnel lens, a preparation method thereof and a mirror surface base. Convex lenses are symmetrically arranged on the central axis of the top of the mirror surface base, and a plurality of Fresnel convex teeth are sequentially arranged on the peripheries of the convex lenses; each Fresnel convex tooth comprises an extreme value surface close to the central shaft and a light emitting surface far away from the central shaft; the extreme value surface and the light emitting surface are sequentially connected end to end; the extreme value surface is a plane, and second refracted light rays taking the intersection point of the extreme value surface and the light emitting surface as a second refracting point coincide with the extreme value surface; and due to the slope of each point of the light-emitting surface, each beam of light is refracted by the condensing Fresnel lens and then is emitted in parallel to the central axis. For a scene with long-distance illumination, a traditional flashlight or searchlight can cause the problems of high power consumption and overlarge size, the LED lamp has the advantages of light weight, thin thickness and the like, the overall thickness is uniform, the production cycle is greatly shortened, the reject ratio is greatly reduced, and meanwhile light convergence is greatly improved.

Description

Technical field:

[0001] The present invention relates to the field of portable flashlights, and in particular to a focusing Fresnel lens and a preparation method thereof. Background technology:

[0002] Most of the flashlights on the market currently use traditional convex lenses. For scenes with long-distance lighting, such as mountaineering and nighttime search, traditional flashlights or searchlights use stacked light sources or adjusted reflectors, which results in high power consumption and excessive volume. Traditional convex lens products are heavy, have a long production cycle, use a lot of materials, and are not easy to carry. However, the meter-counting devices on the market still have the following problems:

[0003] 1. Because the lens is produced by die-casting, and because traditional lenses are thick in the middle and thin on both sides, during die-casting, the material in the middle part takes longer to cool and solidify than the material at the edge, and the overall production cycle is long.

[0004] 2. Traditional convex lens flashlights or searchlights use stacked light sources or adjusted reflectors, which will lead to high power consumption, large size, and unfocused light sources.

[0005] 3. The traditional Fresnel lens directly pushes the mirror body at the top of the convex surface to the bottom, which will cause a gap in the originally continuous mirror body at the top. The light emitted from the gap will be offset to form stray light, and the vertical light effect cannot be achieved; at the same time, too many Fresnel convex teeth will also lead to lower production accuracy, thereby affecting the output accuracy of light.

[0006] For example, the patent publication number is CN105090886A, and the disclosed "A lens and lens system and its use" includes: the lens includes a front surface, a rear surface, and a side surface extending between the front surface and the rear surface; the lens is an axisymmetric body, which defines a central axis; the lens is combined with an LED light source or a similar light source placed on the central axis and movable in the cavity to form a lens system, achieving high utilization of the light emitted by the light source, as well as collimation and focusing functions for the incident light. The thickness of the lens design of this invention varies greatly, and the cooling time is relatively long during industrial processing, which increases the production cycle.

[0007] For example, the patent publication number is CN108826230A, and the disclosed "Flashlight Lens and Illuminating Device" includes: a bottom surface, a top surface and a side surface; the bottom surface is provided with a light entrance cavity, and the surface of the light entrance cavity is a refracting light entrance surface; the top surface is a refracting light exit surface; the side surface is located between the bottom surface and the top surface, and the side surface is a reflecting surface, and the side surface is used to reflect the light entering the lens body from the light entrance surface, so that the reflected light is perpendicular to the light exit surface and is emitted from the light exit surface. The lens of this invention is thicker, which increases the production cycle as a whole, and the lens design does not concentrate the light.

[0008] At the same time, compared with the prior patent of a focusing Fresnel lens and a preparation method thereof (publication number CN118328331A), the present invention clarifies the conditions for calculating the connection points of the Fresnel teeth and improves the yield rate of the Fresnel teeth. Summary of the invention:

[0009] The present invention aims at solving the deficiencies of the prior art and provides a Doppler laser metering device.

[0010] The present invention is based on the Fresnel lens and reduces the use of production materials and improves the degree of light gathering according to the calculation design of the Fresnel convex teeth.

[0011] The technical solutions adopted are as follows:

[0012] A focusing Fresnel lens comprises a mirror base; a convex lens is symmetrically arranged about the central axis of the top of the mirror base, and a plurality of Fresnel convex teeth are sequentially arranged around the periphery of the convex lens; each of the Fresnel convex teeth comprises an extreme value surface close to the central axis and a light-emitting surface far from the central axis; the extreme value surface and the light-emitting surface are sequentially connected end to end; the extreme value surface is a plane, and a second refracted light ray with the intersection of the extreme value surface and the light-emitting surface as the second refraction point coincides with the extreme value surface; the slope of each point of the light-emitting surface enables each beam of light to be emitted parallel to the central axis after being refracted by the focusing Fresnel lens; the light-emitting surface is topologically composed of a plurality of connection points, and any connection point is composed of the intersection of a tangent of a previous connection point and a light ray emitted from a light source and refracted through the light-emitting surface.

[0013] The thickness of the Fresnel teeth increases gradually from the convex lens to the outside.

[0014] The mirror base has a protruding structure at the outer edge away from the central axis compared to the Fresnel convex teeth, so as to facilitate the fixing of the focusing Fresnel lens.

[0015] The mirror base, the Fresnel convex teeth and the convex lens are made of the same material and are integrally die-cast.

[0016] A method for preparing a focusing Fresnel lens, comprising:

[0017] S1, taking the cross section of the focusing Fresnel lens as the plane, initializing the focusing Fresnel lens information;

[0018] The light source is located on the central axis of the bottom of the mirror base; the incident light is the light emitted directly from the light source; the light emitted by the incident light into the focusing Fresnel lens after refraction is the first refracted light, and the incident point is the first refraction point; the light emitted by the first refracted light out of the focusing Fresnel lens after secondary refraction is the second refracted light, and the exit point is the second refraction point;

[0019] S2, allocate and calculate incident light: take the light source 8 as the center, the area formed by the incident light along the central axis 2 and the second refraction point 72 as the intersection point between the light emitting surface of the Fresnel convex tooth adjacent to the convex structure and the convex structure is the incident light area, and divide the incident light in the incident light area into a plurality of calculated incident light beams, and the angles between adjacent calculated incident light beams are equal;

[0020] The total number of Fresnel teeth is preset, and the same number of calculated incident rays are allocated to each Fresnel tooth, and the calculated incident rays are allocated in proportion to the radius of one Fresnel tooth for the convex lens;

[0021] The calculated incident light includes a starting calculated incident light and a terminal calculated incident light, wherein the starting calculated incident light is an extreme calculated incident light of the Fresnel convex tooth away from the light source 8, and the terminal calculated incident light is an extreme calculated incident light of the Fresnel convex tooth close to the light source 8;

[0022] S3, taking the second refraction point of the incident light calculated at the beginning as the starting connection point, setting the intersection of the tangent of the second refraction point of the previous calculated incident light and the second refraction ray of the next calculated incident light as the next connection point of the light-emitting surface of the Fresnel convex tooth, and then setting the tangent slope of the connection point of the light-emitting surface of the Fresnel convex tooth according to Snell's refraction law; repeating the above steps to set each connection point of the light-emitting surface of the Fresnel convex tooth until the incident light calculated at the connection point is the incident light calculated at the end of the Fresnel convex tooth;

[0023] Each connection point of the light-emitting surface of the Fresnel convex tooth is connected with the tangent slope of the point to form the light-emitting surface of the Fresnel convex tooth; the first refraction point and the second refraction point of the incident light calculated at the end of the Fresnel convex tooth are connected to form the extreme value surface of the Fresnel convex tooth, and the first refraction point is used as the starting point for setting the next Fresnel convex tooth;

[0024] The tangent line slope is the slope of the second refraction point that makes the second refracted light parallel to the central axis;

[0025] S4. Form a convex lens using the method of S3.

[0026] In step S2, the incident light within the angle is divided into a number of beams to calculate the incident light, and the specific number is adjusted according to the radius of the focusing Fresnel lens to ensure that the actual error deviation angle of the second refracted light is less than 1°.

[0027] It also has the following beneficial effects:

[0028] 1. The present invention is based on a Fresnel lens, and has the advantages of light weight, thin thickness, and uniform overall thickness. Compared with the traditional convex lens which requires more materials and cooling time, the production cycle of the present invention is significantly shortened.

[0029] 2. The present invention adjusts the Fresnel lens to ensure that the light emitted from the light source can be emitted from the lens in the direction pointed by the flashlight.

[0030] 3. By iteratively calculating the position of each connection point, it is ensured that the incident light can accurately exit the vertical tangent line after refraction, reducing the spot deviation and aberration. At the same time, the tangent and normal directions of each connection point are precisely controlled to optimize the light intensity distribution on the light output surface, improve the uniformity and efficiency of light collection, and greatly reduce the defect rate. Description of the drawings:

[0031] In order to more clearly illustrate the scheme in the present application, a brief introduction is given below to the drawings required for use in the description of the embodiments of the present application. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0032] Figure 1 The figure is a schematic structural diagram of a focusing Fresnel lens according to an embodiment of the present invention.

[0033] Figure 2 The figure is a light schematic diagram of a focusing Fresnel lens according to an embodiment of the present invention.

[0034] Figure 3 Schematic diagram of a light scale of a focusing Fresnel lens described in an embodiment of the present invention.

[0035] Figure 4 The figure is a schematic diagram of calculating incident light for a focusing Fresnel lens described in an embodiment of the present invention.

[0036] The marks in the accompanying drawings are: 1-mirror base, 2-central axis, 3-convex lens, 4-Fresnel convex tooth, 41-Fresnel convex tooth extreme surface, 42-Fresnel convex tooth light exit surface, 5-convex structure, incident light ray 6, first refracted light ray 61, second refracted light ray 62, first refraction point 71, second refraction point 72, light source 8, 9-incident light area, 91-calculated incident light ray at the beginning, 92-calculated incident light ray at the end, normal line of the second refraction point 10, tangent line of the second refraction point 11. Specific implementation method:

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used in the specification of the application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0038] like Figure 1 As shown, this embodiment 1 discloses a focusing Fresnel lens and a method for preparing the same;

[0039] A focusing Fresnel lens comprises a mirror base 1; a convex lens 3 is symmetrically arranged on the central axis 2 at the top of the mirror base, and a plurality of Fresnel convex teeth 4 are sequentially arranged on the periphery of the convex lens; each of the Fresnel convex teeth comprises an extreme value surface 41 close to the central axis 2 and a light-emitting surface 42 away from the central axis 2; the extreme value surface 41 and the light-emitting surface 42 are sequentially connected end to end; the extreme value surface 41 is a plane, and a second refracted light 62 with the intersection of the extreme value surface 41 and the light-emitting surface 42 as the second refraction point 72 coincides with the extreme value surface 41; the slope of each point of the light-emitting surface 42 makes each beam of light emitted parallel to the central axis 2 after being refracted by the focusing Fresnel lens; the light-emitting surface 42 is topologically composed of a plurality of connection points, and any connection point is composed of the intersection of the tangent of the previous connection point and the light emitted from the light source and refracted through the light-emitting surface 42.

[0040] The thickness of the Fresnel teeth increases gradually from the convex lens 3 to the outside.

[0041] The mirror base has a protruding structure 5 on the outer edge away from the central axis 2 compared to the Fresnel protruding teeth, so as to facilitate fixing the focusing Fresnel lens.

[0042] The mirror base, the Fresnel convex teeth and the convex lens are made of the same material and are integrally die-cast.

[0043] A method for preparing a focusing Fresnel lens, comprising:

[0044] S1, taking the cross section of the focusing Fresnel lens as a plane, initializing the focusing Fresnel lens information; the focusing Fresnel lens information includes the thickness and width of the mirror base, the radius of the focusing Fresnel lens, the vertical distance between the light source and the mirror base, the refractive index n of the focusing Fresnel lens, and the width of the Fresnel convex teeth;

[0045] The light source 8 is located on the central axis 2 at the bottom of the mirror base, and the incident light is the light emitted directly from the light source 8; the light emitted by the incident light into the focusing Fresnel lens after refraction is the first refracted light 61, and the incident point is the first refraction point 71; the light emitted by the first refracted light 61 from the focusing Fresnel lens after secondary refraction is the second refracted light 62, and the exit point is the second refraction point 72;

[0046] S2, allocate and calculate incident light: take the light source 8 as the center, the area formed by the incident light along the central axis 2 and the second refraction point 72 as the intersection point between the light emitting surface of the Fresnel convex tooth adjacent to the convex structure and the convex structure is the incident light area, and divide the incident light in the incident light area into a plurality of calculated incident light beams, and the angles between adjacent calculated incident light beams are equal;

[0047] The total number of Fresnel teeth is preset, and the same number of calculated incident rays are allocated to each Fresnel tooth, and the calculated incident rays are allocated in proportion to the radius of one Fresnel tooth for the convex lens;

[0048] like Figure 4 The calculated incident light includes the starting calculated incident light and the ending calculated incident light, wherein the starting calculated incident light is the extreme calculated incident light of the Fresnel convex tooth away from the light source 8, and the ending calculated incident light is the extreme calculated incident light of the Fresnel convex tooth close to the light source 8;

[0049] S3, taking the second refraction point 72 of the incident light calculated at the beginning as the starting connection point, setting the intersection of the tangent of the second refraction point 72 of the previous incident light calculated and the second refraction ray 62 of the next incident light calculated as the next connection point of the light-emitting surface 42 of the Fresnel convex tooth, and then setting the tangent slope of the connection point of the light-emitting surface 42 of the Fresnel convex tooth according to the Snell refraction law; repeating the above steps to set each connection point of the light-emitting surface 42 of the Fresnel convex tooth until the incident light calculated at the connection point is the incident light calculated at the end of the Fresnel convex tooth;

[0050] Each connection point of the Fresnel tooth light-emitting surface 42 is connected with the tangent slope of the point to form the Fresnel tooth light-emitting surface 42; the first refraction point 71 and the second refraction point 72 of the incident light calculated at the end of the Fresnel tooth are connected to form the extreme value surface 41 of the Fresnel tooth, and the first refraction point 71 is used as the starting point for setting the next Fresnel tooth;

[0051] The tangent line slope is the slope that makes the second refracted light 62 parallel to the second refraction point 72 of the central axis 2;

[0052] The tangent slope of the connection point of the Fresnel tooth light-emitting surface 42 is set according to the Snell refraction law as follows:

[0053] like Figure 2 and Figure 3 Since each Fresnel tooth 4 is assigned a fixed number of incident light rays, and the angles of the incident light rays are the same, it can be seen that the slope of the first refracted light ray is k1, the incident angle is θ1, the refraction angle is θ2, and the refractive index of the Fresnel lens is n. Now the tangent slope k at the refraction point is required. t :

[0054] Tangent slope k t With normal slope k n Satisfy vertical relationship: According to Snell's law of refraction Using the geometric relationship between slope and angle, the slopes of the two straight lines are k1 and k n When , the tangent of the angle is:

[0055]

[0056] Convert Snell's law of refraction into tangent expression, combining trigonometric identities get

[0057]

[0058] Substitute the tangent slope formula and finally get the tangent slope:

[0059] S4. Form a convex lens using the method of S3.

[0060] During the production process, the tip of the Fresnel tooth cannot reach the ideal angle completely due to processing problems, and a certain curvature will appear. Therefore, in the actual processing, the more Fresnel teeth, the better. They need to be in appropriate proportion to the area occupied by the convex lens. According to the actual processing effect, the width of the convex lens is equal to the width of the entire Fresnel tooth part, and the light gathering effect is best.

[0061] The method of using the intersection of the light and the tangent of the connection point as the next connection point is to adopt the calculus method. The more connection points there are, the more the slope of the tangent of each connection point is in line with making the second refracted light parallel to the central axis 2, but it is not necessary to infinitely increase the calculated incident light. As long as the calculated number of incident light reaches a critical point, the actual error deviation angle of the second refracted light has basically no effect on actual use. According to the actual industrial processing effect, the incident light in the incident light area in step S2 is divided into 2000-4000 beams to calculate the incident light, the radius of the focusing Fresnel lens is 10-15cm, and the ratio of the convex lens to the radius of a Fresnel convex tooth is 1:2, then the actual error deviation angle of the second refracted light is less than 1°.

Claims

1. A focusing Fresnel lens, comprising a mirror base; a convex lens is symmetrically arranged on the central axis of the top of the mirror base, and a plurality of Fresnel convex teeth are arranged in sequence on the periphery of the convex lens; each of the Fresnel convex teeth comprises an extreme value surface close to the central axis and a light-emitting surface away from the central axis; the extreme value surface and the light-emitting surface are connected end to end in sequence; characterized in that: The extreme surface is a plane, and the second refracted light with the intersection of the extreme surface and the light-emitting surface as the second refraction point coincides with the extreme surface; the slope of each point on the light-emitting surface makes each beam of light be emitted parallel to the central axis after being refracted by the focusing Fresnel lens; the light-emitting surface is topologically composed of a plurality of connection points, and any connection point is composed of the intersection of the tangent of the previous connection point and the light refracted from the light source through the light-emitting surface.

2. The focusing Fresnel lens according to claim 1, characterized in that: The mirror base has a protruding structure at the outer edge away from the central axis compared to the Fresnel convex teeth, so as to facilitate the fixing of the focusing Fresnel lens.

3. The focusing Fresnel lens according to claim 1, characterized in that: The thickness of the Fresnel teeth increases gradually from the convex lens to the outside.

4. The focusing Fresnel lens according to claim 1, characterized in that: The mirror base, the Fresnel convex teeth and the convex lens are made of the same material and are integrally die-cast.

5. A method for preparing a focusing Fresnel lens according to any one of claims 1 to 3, characterized in that: include: S1, taking the cross section of the focusing Fresnel lens as the plane, initialize the focusing Fresnel lens information; The light source is located on the central axis of the bottom of the mirror base; the incident light is the light emitted directly from the light source; the light emitted by the incident light into the focusing Fresnel lens after refraction is the first refracted light, and the incident point is the first refraction point; the light emitted by the first refracted light out of the focusing Fresnel lens after secondary refraction is the second refracted light, and the exit point is the second refraction point; S2, allocating and calculating incident light: the area formed by the light emitted from the light source along the central axis and the incident light whose second refraction point is the intersection point between the light-emitting surface of the Fresnel convex tooth adjacent to the convex structure and the convex structure is the incident light area, and the incident light in the incident light area is evenly divided into a plurality of calculated incident light beams, and the angles between adjacent calculated incident light beams are equal; The total number of Fresnel teeth is preset, and the same number of calculated incident rays are allocated to each Fresnel tooth, and the calculated incident rays are allocated in proportion to the radius of one Fresnel tooth for the convex lens; The calculated incident light includes a starting calculated incident light and a terminal calculated incident light, wherein the starting calculated incident light is an extreme calculated incident light of the Fresnel convex tooth away from the light source, and the terminal calculated incident light is an extreme calculated incident light of the Fresnel convex tooth close to the light source; S3, taking the second refraction point of the incident light calculated at the beginning as the starting connection point, setting the intersection of the tangent of the second refraction point of the previous calculated incident light and the second refraction ray of the next calculated incident light as the next connection point of the light-emitting surface of the Fresnel convex tooth, and then setting the tangent slope of the connection point of the light-emitting surface of the Fresnel convex tooth according to Snell's refraction law; repeating the above steps to set each connection point of the light-emitting surface of the Fresnel convex tooth until the incident light calculated at the connection point is the incident light calculated at the end of the Fresnel convex tooth; Each connection point of the light-emitting surface of the Fresnel convex tooth is connected with the tangent slope of the point to form the light-emitting surface of the Fresnel convex tooth; the first refraction point and the second refraction point of the incident light calculated at the end of the Fresnel convex tooth are connected to form the extreme value surface of the Fresnel convex tooth, and the first refraction point is used as the starting point for setting the next Fresnel convex tooth; The tangent line slope is the slope of the second refraction point that makes the second refracted light parallel to the central axis; S4. Form a convex lens using the method of S3.

6. The method for preparing a focusing Fresnel lens according to claim 3, characterized in that: In step S2, the incident light within the angle is divided into a number of beams to calculate the incident light, and the specific number is adjusted according to the radius of the focusing Fresnel lens to ensure that the actual error deviation angle of the second refracted light is less than 1°.

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