Surface light emitting module for vehicle

Abstract

The invention relates to the technical field of vehicle surface light sources, in particular to a surface light-emitting module for a vehicle. A surface light-emitting module used for a vehicle comprises a shell, a PCBA board integrated with an LED, a flat light guide body, a reflecting layer and an optical film layer, the PCBA board integrated with the LED, the flat light guide body, the reflecting layer and the optical film layer are installed in the shell, the PCBA board integrated with the LED is horizontally arranged on the inner bottom face of the shell, the flat light guide body is vertically arranged above the PCBA board, the bottom of the narrow face of the flat light guide body is provided with a collimator used for being coupled into LED light, and the opposite flat face serves as a light transmission channel. A micro-structure array is arranged on the inclined surface, facing the reflecting layer, of the flat light guide body, and the height of the micro-structure array is in exponential distribution along the light propagation direction; the reflecting layer and the optical film layer are located on the rear side and the front side of the flat light guide body respectively. The PCBA board, the flat light guide body, the reflecting layer and the optical film layer form a layer type compact structure, all the components are attached in a face shape to achieve flat installation, light emitting uniformity is improved, and bright and dark stripes are eliminated. And the light utilization rate is improved by utilizing the rear side reflecting layer and a multi-reflection mechanism.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle surface light sources, and in particular to a surface light-emitting module for vehicles. Background Art

[0002] In the existing surface light source optical system, the following three methods are mainly used: The first is Mini LED technology, which offers excellent uniformity and can enable animation editing and human-computer interaction through electronic programming. However, due to its high cost, its application in low-end vehicles is extremely limited.

[0003] The second option is OLED technology. This system, as a surface light source solution, can provide uniform lighting and dynamic flowing light effects without overly complex vehicle lighting designs. However, OLED technology faces challenges such as high cost per unit area and a relatively short lifespan, and is currently limited to a few high-end brands.

[0004] The third optical system uses LEDs and a light guide plate. Specifically, a row of LEDs is mounted on a PCB, with light directed by the light guide plate and emitted from the front side. A white bracket supports the rear side. This configuration achieves relatively uniform lighting under conventional headlight styling conditions and supports dynamic flowing water effects. However, ensuring uniform lighting requires a large number of LEDs and a large PCB area, resulting in high costs.

[0005] A fourth approach has recently emerged on the market, improving upon the third. It utilizes a black front frame, light guide plate, white bracket, and a combined light guide and LED light source. The light guide replaces linearly arranged LEDs, reducing the number of LEDs. Furthermore, the light guide is integrally molded with the light guide plate, minimizing space requirements. However, due to the limited etendue of the light guide plate system, this solution cannot be applied to signal lights with higher brightness requirements, such as brake lights and turn signals.

[0006] As surface light sources become an industry trend, and the automotive market urgently needs to reduce costs, existing solutions are limited in adoption by many mid- and low-end brands due to cost issues. Therefore, developing a high-brightness surface light source that reduces LED usage is particularly important. Summary of the Invention

[0007] The technical problem to be solved by the present invention is: in order to solve the problem that in the lighting system using a light guide plate as the core component of the prior art in the above-mentioned background technology, the optical expansion of light during propagation such as absorption and scattering causes low overall luminous efficiency of the system, resulting in insufficient light brightness, a surface light-emitting module for vehicles is provided, which can effectively improve the light guide efficiency, achieve uniform light output and have a compact structure.

[0008] The technical solution adopted by the present invention to solve the technical problem is: a surface light-emitting module for a vehicle, comprising a housing and a device installed in the housing: The PCBA board with integrated LED is horizontally arranged on the bottom surface of the housing; The flat light guide is vertically arranged above the PCBA board. A collimator is provided at the bottom of its narrow surface for coupling LED light. The opposite flat surface serves as a light transmission channel. A microstructure array is provided on the inclined surface of the flat light guide facing the reflective layer. The height of the microstructure array is exponentially distributed along the direction of light propagation to compensate for light energy attenuation and ensure uniform light output. A reflective layer, located on the rear side of the flat light guide, for reflecting the light scattered backwards; The optical film layer is located on the front side of the flat light guide, and is used to control the angle of the emitted light and return the light that does not meet the angle requirements back to the flat light guide; The PCBA board, flat light guide, reflective layer and optical film layer form a layered compact structure, and the components are abutted against each other in a planar manner to achieve flat installation.

[0009] The PCBA is arranged parallel to the bottom of the surface-emitting module, and the flat light guide is installed vertically, forming a stacked structure of PCBA, flat light guide, reflective layer, and film layer. The thickness is determined solely by the stacking of the various layers, achieving ultra-thinness and suitable for the confined installation space of a vehicle. The collimator directly couples the LED light, avoiding the coupling loss caused by traditional end-face light input and improving light efficiency. The microstructure array on the inclined surface compensates for light transmission attenuation through exponential height distribution, significantly reducing the difference in brightness between the edge and center. The optical film layer filters the output angle. Light exceeding the specified angle is fully reflected back to the light guide, and then reflected again by the reflective layer or microstructure array, resulting in a high recycling rate.

[0010] According to one embodiment of the present invention, the microstructure array includes a first array and a second array arranged adjacent to each other, the first array is composed of a plurality of micro-optical elements with continuous concave-convex distribution, and the second array has the same structure as the first array with the concave-convex parts staggered.

[0011] The staggered design of the first and second arrays reduces the streaking effect caused by the contrast between the normal reflective surface and the concentrated reflection of certain microstructures between the reflective structures, thereby improving the uniformity index. The staggered structure produces multi-directional scattering, meeting the wide-angle lighting requirements of vehicles.

[0012] According to one embodiment of the present invention, the cross-section of the micro-optical element is triangular or rectangular. The triangle realizes high directivity reflection, and the vertical sidewalls of the rectangle generate multiple total reflections, thereby improving axial brightness.

[0013] According to one embodiment of the present invention, the height of the microstructure array satisfies the following relationship: , in, is the height of the microstructure array at a distance from the LED x; is the height of the microstructure array (30) at the initial position; α is the growth coefficient based on the optimization of light loss rate and uniformity; and x is the distance along the light propagation direction.

[0014] Exponential distribution can be achieved through CNC machining or mold etching.

[0015] According to one embodiment of the present invention, the inclination angle of the inclined surface of the flat light guide is It increases with the height of the microstructure array and satisfies the following relationship: .

[0016] Dynamic tilt avoids edge light leakage caused by traditional fixed tilt.

[0017] According to one embodiment of the present invention, the reflectivity of the microstructure array changes with the incident angle. The function of change, for unpolarized light, satisfies: , in, is the refractive index of the microstructure array; is the refractive index of the external medium; is the angle of refraction, and .

[0018] According to one embodiment of the present invention, the flat light guide is an integrally formed plastic transparent member made of polymethyl methacrylate or polycarbonate, and a collimator is provided at the bottom thereof in one-to-one correspondence with the LEDs.

[0019] One-piece molding eliminates Fresnel loss at the splicing interface, and both polymethyl methacrylate and polycarbonate materials offer stable performance.

[0020] According to one embodiment of the present invention, the surface of the PCBA board facing the flat light guide is coated with a light-colored high-reflectivity paint, or covered with a metal coating or a high-reflective plastic film. White paint is more conducive to uniform light feedback to the light guide.

[0021] According to one embodiment of the present invention, the reflective layer is a metal coating or a white diffuse reflective film.

[0022] According to one embodiment of the present invention, the shell includes a shell frame and a shell cover covering the shell frame, which are connected by screws. A mounting hole is provided on the inner side wall of the shell frame, and locking parts that cooperate with the mounting hole are provided on both sides of the flat light guide.

[0023] The interference fit between the engaging piece and the mounting hole can withstand large mechanical impacts, and the screw connection is firm.

[0024] Beneficial effects of the present invention: (1) The miniaturization and flattening design of the lighting device is realized, which is suitable for embedding in the narrow space of the vehicle: a laminated structure with a PCBA board, a flat light guide, a reflective layer, and an optical film layer tightly fitted together is adopted. The overall thickness is determined by the superposition of each layer of materials. The vertical layout of the flat light guide is combined with the bottom LED coupling design to avoid the traditional L-shaped light guide structure's dependence on deep space; (2) Improved the light guiding efficiency of surface-emitting light sources, with higher surface brightness: the collimator directly couples the LED light, reducing the coupling loss of the end-face light, and the index height distribution of the microstructure array dynamically compensates for the light transmission attenuation, thereby improving the axial brightness; the optical film layer screens the effective output angle, and the light exceeding the specified angle is fully reflected back to the light guide for recycling, greatly improving the light utilization rate; (3) Improved light uniformity and eliminated bright and dark stripes: The first array and the second array are misaligned, which weakens the sense of bright stripes caused by the contrast between the concentrated reflection of certain microstructure angles between the reflective structures and the normal reflective surface, and the uniformity index is significantly improved; (4) Compatible with various light source types and strong scalability: supports single-color / multi-color LEDs, PCBA boards can integrate drive circuits, and achieve dynamic color switching through PWM dimming; (5) The rear reflective layer and multiple reflection mechanism are used to improve light utilization: the reflective layer efficiently reflects the escaping light back to the light guide, and combined with the tilt angle optimization of the microstructure array, the invalid light recycling rate reaches 90%; (6) It can be applied to various automotive lighting scenarios such as taillights, daytime running lights, and interior ambient lights. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention will be further described below with reference to the accompanying drawings and examples.

[0026] Figure 1 It is a schematic diagram of the explosion structure of the present invention.

[0027] Figure 2 It is a cross-sectional view of the present invention.

[0028] Figure 3 It is a structural schematic diagram of the flat light guide in the present invention.

[0029] Figure 4 yes Figure 3 rear view.

[0030] Figure 5 yes Figure 3 A partial enlarged view of the inclined surface of the flat light guide.

[0031] Figure 6 yes Figure 5 Schematic diagram of the enlarged structure at point I.

[0032] Figure 7 It is the optical path diagram of the present invention.

[0033] In the figure: 1. Shell cover; 2. Reflective layer; 3. Flat light guide; 30. Microstructure array; 31. Collimator; 32. Clamping part; 300. Micro-optical component; 301. First array; 302. Second array; 4. PCBA board; 5. Optical film layer; 6. Shell frame; 61. Mounting hole; 7. Screw. DETAILED DESCRIPTION

[0034] The present invention will now be described in further detail with reference to the accompanying drawings, which are simplified schematic diagrams that illustrate the basic structure of the present invention in a schematic manner.

[0035] Example 1 like Figure 1 and Figure 2 As shown, a surface light-emitting module for a vehicle includes a shell cover 1, a reflective layer 2, a PCBA board 4 with integrated LEDs, a flat light guide 3, an optical film layer 5 and a shell frame 6. The shell frame 6 and the shell cover 1 are connected by screws 7. A mounting hole 61 is provided on the inner side wall of the shell frame 6. Both sides of the flat light guide 3 are provided with engaging parts 32 that cooperate with the mounting holes 61. The PCBA board 4, the flat light guide 3, the reflective layer 2 and the optical film layer 5 constitute a layered compact structure. Each component is installed in a planar manner in the shell formed by the shell frame 6 and the shell cover 1 to achieve flat installation.

[0036] The PCBA board 4, which integrates the LEDs, is horizontally arranged on the inner bottom surface of the housing. The flat light guide 3 is vertically positioned above the PCBA board 4. A collimator 31 is installed at the bottom of its narrow surface to couple the LED light. The opposing flat surface serves as a light transmission channel. A microstructure array 30 is installed on the inclined surface of the flat light guide 3 facing the reflective layer 2. The height of the microstructure array 30 is exponentially distributed along the light propagation direction to compensate for light energy attenuation and ensure uniform light output. The reflective layer 2 is located behind the flat light guide 3 and reflects backscattered light. The optical film 5 is located in front of the flat light guide 3 to control the output light angle and redirect light that does not meet the required angle back to the flat light guide 3. The flat light guide 3 is a one-piece transparent plastic component made of polymethyl methacrylate or polycarbonate. The collimators 31 are located at the bottom of the PCBA board 4, corresponding to the LEDs. The surface of the PCBA board 4 facing the flat light guide 3 is coated with a light-colored, high-reflectivity paint, or covered with a metal coating or a highly reflective plastic film. The reflective layer 2 is a metal coating or a white diffuse reflective film.

[0037] The surface light-emitting module for a vehicle can be easily installed in an opening in the vehicle body. The PCBA board 4 with integrated LEDs is arranged horizontally on the bottom surface of the housing. This advantageously realizes a layered structure of a flat component including the PCBA board 4, and the overall thickness is determined by the stacking of the various layers of material.

[0038] like Figures 3 to 5 As shown, the microstructure array 30 includes a first array 301 and a second array 302 arranged adjacent to each other. The first array 301 is composed of a plurality of micro-optical elements 300 with a continuous concave-convex distribution. The second array 302 has the same structure as the first array 301, but the concave-convex portions are arranged in a staggered manner. The cross-section of the micro-optical element 300 can be triangular or rectangular.

[0039] The flat light guide 3 is arranged vertically, unlike traditional L-shaped light guides. This vertical placement reduces module thickness, while the bottom collimator 31 directly couples LED light, increasing coupling efficiency to over 85%. The beveled microstructure array 30 dynamically compensates for light transmission attenuation through an exponential height distribution, ensuring a brightness difference of less than 5% between the edge and center within a 10cm length. The reflective layer 2 efficiently reflects escaping light back into the light guide, achieving a light utilization rate of 90%. The optical film 5 filters the exit angle, fully reflecting light above a specified angle back into the light guide for recycling. The PCBA board 4, flat light guide 3, reflective layer 2, and optical film 5 are laminated flatly, seamlessly stacked, with the total thickness determined solely by the material stacking. The overall module thickness is less than 15mm, enabling easy installation in vehicle body openings. The combination of direct collimator coupling, microstructure array compensation, and light recycling achieves a system light efficiency of 0.36. The staggered microstructure array eliminates streaking, achieving a uniformity index of over 0.9.

[0040] Traditional light guide plate systems have difficulty balancing high brightness and uniformity due to optical extension limitations. The surface light-emitting module for vehicles in this embodiment effectively resolves this contradiction through the exponential height distribution of the microstructure array and the angle screening of the optical film layer. Through innovative structural design, optimization of the microstructure array, efficient optical recycling mechanism and improvement of material processing, the goals of low cost and miniaturization are achieved while improving light efficiency, uniformity and mechanical stability. The synergistic integration of these technologies provides an efficient, compact and economical technical solution for the field of vehicle surface light sources.

[0041] Example 2 The design method of the surface light-emitting module for a vehicle achieves effective reflection and uniform light emission of the propagating light by setting a microstructure array with specific geometric features on the inclined surface of the flat light guide 3. Specifically, the height of the microstructure array 30 is first set to satisfy the following relationship: , Among them, such as Figure 3 As shown, is the height of the microstructure array 30 at a distance from the LED x; is the height of the microstructure array 30 at the initial position (near the LED); x is the distance along the light propagation direction. Preferably, the sub-arrays in the microstructure array 30 are staggered to uniformly illuminate the stripes.

[0042] α is a growth coefficient based on the optimization of light loss rate and uniformity, which controls the rate of microstructure growth. Specifically, α is a design parameter. It is not a physical constant that can be directly measured (such as the speed of light), but its value is determined by the physical process. It represents the "speed" of microstructure height growth and its unit is 1 / length (for example, mm). -1 or cm -1 ), because the exponential part of the exponential function must be dimensionless ( is dimensionless).

[0043] The core physical principle of this relationship is that when light is transmitted in a light guide, its intensity It will decay exponentially due to material absorption and scattering, which is a basic law in optics, that is, ,in, is the light intensity at position x, The initial light intensity at the light source (x=0), β is the attenuation coefficient, the unit is 1 / length, which is determined by the material properties. In order to obtain uniform light output, the luminous flux (or brightness) coupled out from the light output surface needs to be constant in the x direction. This means that as x increases, If the microstructure is reduced, the "extraction efficiency" of the microstructure must be increased to compensate. The most direct way is to increase the "density" or "size" of the microstructure. In this embodiment, the height is increased. , first assume that the local extraction efficiency of the microstructure With its height is proportional to , which is a reasonable engineering approximation. The greater the height, the greater the disturbance and the more extraction. Then, in order to offset The exponential decay of Growing exponentially, Approximately a constant C, that is: ; Substitution and The expression of , can be sorted out as: ;make (This is a constant representing the equivalent height when x=0), , and finally get: The optimal value of α is theoretically equal to the light attenuation coefficient β. Therefore, this exponential function is the optimal solution derived to accurately compensate for the exponential attenuation of light intensity, thereby achieving the core goal of uniform light output. Therefore, α should be optimized to be close to the material's attenuation coefficient β.

[0044] At the same time, the inclined surface of the microstructure array 30 is an inclined tooth-like structure, and its inclination angle is It increases with the height to compensate for the energy attenuation of light during transmission and maintain the reflection conditions. The specific relationship is as follows: .

[0045] The inclined surface of the microstructure array 30 is an inclined tooth-like structure, which means that its side surface is an inclined surface, such as Figure 5 As shown, the inclination angle of this slope is , is mathematically defined as the angle between the inclined plane and the horizontal reference plane (i.e. the bottom surface of the light guide, in the x-axis direction). In calculus, a curve The slope at point x is its derivative, that is, , this slope is equal to the tangent of the angle θ between the tangent line at that point and the x-axis, that is, (Taking the absolute value is because the angle is positive); the height of the microstructure As a function of position x , then, at position x, the slope of the microstructure slope is , so the inclination angle of the slope Expressed as: ,calculate : Known , taking the derivative with respect to x, we get: , substitute into the formula , we can get .

[0046] is the geometric definition of the tilt angle, which is directly derived from the height function of the microstructure array 30 The mathematical form of is as x increases, It grows faster and faster (because it is an exponential function), so It is also getting bigger, resulting in The microstructure becomes steeper and steeper.

[0047] Secondly, the LED light is emitted from the bottom collimator 31, reflected forward by the microstructure array 30, and then directedly output after passing through the front optical film layer 5; the optical film layer 5 has the function of controlling the size of the output angle. For example, the microprism structure is used to screen the output angle within the range of ±30°. After passing through the optical film layer 5, the light that does not meet the output angle requirement will be folded back and enter the internal circulation path of the flat light guide 3, and then reflected by the reflective layer 2 again to the microstructure array 30 for integration until the output angle requirement is met. Figure 7 shown.

[0048] Then, a reflective layer 2 with high reflectivity is set on the back side of the flat light guide 3. The light that does not meet the emission angle requirements re-enters the flat light guide 3 after reflection, forming multiple rounds of reflection and integration process, and finally outputs light that meets the target viewing angle requirements, thereby improving the overall light output efficiency.

[0049] Finally, consider the refractive index of the material of the flat light guide 3 and the refractive index of the external medium , by optimizing the microstructure tilt angle , so that the effective light guide efficiency is close to the maximum value. For unpolarized light, the reflectivity can be approximately expressed as: , in, is the refractive index of the microstructure array 30; is the refractive index of the external medium; is the angle of refraction, and .

[0050] like Figure 6 As shown, is the angle of incidence, which is the angle between the incident ray and the surface normal at the point of incidence. It is used to calculate the given incident angle Under this condition, how much proportion of light will be reflected back into the flat light guide 3? Reflecting the light back into the flat light guide 3 can give it the opportunity to be reflected again by other microstructure arrays 30 or finally coupled forward, and cooperate with the high reflectivity reflective layer 2 at the rear to form a recycling integration mechanism to improve the light efficiency. The value of , for example, for unpolarized light, when When approaching Brewster's angle, the reflectivity will have a minimum value; when At angles close to 90° (grazing incidence), the reflectivity approaches 100%.

[0051] The height of the microstructure array 30 is dynamically increased based on the light propagation distance to compensate for the inherent absorption loss of the flat light guide 3 material (such as PMMA). When α = 0.035 / mm, the brightness difference between the edge and center of the 10cm flat light guide 3 is less than 3%. , microstructure array 30 tilt angle As the height increases, it increases, maintaining the best match between the light reflection angle and the optical film layer 5, avoiding edge light leakage caused by the traditional fixed tilt angle. The prism structure of the optical film layer 5 screens the effective output angle within ±30°, and the super-angle light is fully reflected back to the flat light guide 3, with a light recycling rate of 90%. The high reflectivity design of the reflective layer 2 recycles the backscattered light and re-passes through the flat light guide 3, and the light efficiency is increased to 0.36. Through the formula Optimize the microstructure inclination angle to minimize the interface reflection loss. For example, when the interface between PMMA (n1=1.49) and air (n2=1.0), θ i =55°, 80% of the light is transmitted into the microstructure array 30, of which 60% is guided to the light-emitting surface by total internal reflection; and of the 20% of the interface reflected light, 10% is recycled and reused by the reflective layer 2.

[0052] With the above-described preferred embodiments of the present invention as a guide, and with reference to the above description, relevant personnel are fully capable of making various changes and modifications without departing from the technical scope of this invention. The technical scope of this invention is not limited to the contents of the specification and must be determined according to the scope of the claims.

Claims

1. A surface light-emitting module for a vehicle, characterized in that: Including the housing and installed in the housing: A PCBA board (4) with integrated LEDs is arranged horizontally on the inner bottom surface of the housing; A flat light guide (3) is vertically arranged above the PCBA board (4), and a collimator (31) for coupling LED light is provided at the bottom of its narrow surface. The opposite flat surface serves as a light transmission channel. A microstructure array (30) is provided on the inclined surface of the flat light guide (3) facing the reflective layer (2). The height of the microstructure array (30) is exponentially distributed along the light propagation direction, and is used to compensate for light energy attenuation and uniformly emit light. A reflective layer (2), located on the rear side of the flat light guide (3), for reflecting light scattered backwards; An optical film layer (5) is located on the front side of the flat light guide (3) and is used to control the angle of the emitted light and to reflect light that does not meet the angle requirement back to the flat light guide (3); The PCBA board (4), the flat light guide (3), the reflective layer (2), and the optical film layer (5) form a layered compact structure, and the components are flatly attached to each other to achieve flat installation.

2. The surface light-emitting module for a vehicle according to claim 1, characterized in that: The microstructure array (30) comprises a first array (301) and a second array (302) arranged adjacent to each other, wherein the first array (301) is composed of a plurality of micro-optical elements (300) with continuous concave-convex distributions, and the second array (302) has the same structure as the first array (301), with the concave-convex portions being arranged in a staggered manner.

3. The surface light-emitting module for a vehicle according to claim 2, characterized in that: The cross section of the micro-optical component (300) is triangular or rectangular.

4. The surface light-emitting module for a vehicle according to claim 2, characterized in that: The height of the microstructure array (30) satisfies the following relationship: ， in, is the height of the microstructure array (30) at a distance from the LED x; is the height of the microstructure array (30) at the initial position; α is the growth coefficient based on the optimization of light loss rate and uniformity; and x is the distance along the light propagation direction.

5. The surface light-emitting module for a vehicle according to claim 4, characterized in that: The inclination angle of the inclined surface of the flat light guide (3) As the height of the microstructure array (30) increases, the following relationship is satisfied: 。 6. The surface light-emitting module for a vehicle according to claim 3, characterized in that: The reflectivity of the microstructure array (30) varies with the incident angle The function of change, for unpolarized light, satisfies: ， in, is the refractive index of the microstructure array (30); is the refractive index of the external medium; is the angle of refraction, and .

7. The surface light-emitting module for a vehicle according to claim 1, characterized in that: The flat light guide (3) is an integrally formed transparent plastic part made of polymethyl methacrylate or polycarbonate, and a collimator (31) is provided at its bottom, corresponding one-to-one with the LEDs.

8. The surface light-emitting module for a vehicle according to claim 1, characterized in that: The surface of the PCBA board (4) facing the flat light guide (3) is coated with a light-colored high-reflectivity paint, or is covered with a metal coating or a high-reflection plastic film.

9. The surface light-emitting module for a vehicle according to claim 1, characterized in that: The reflective layer (2) is a metal coating or a white diffuse reflective film.

10. The surface light-emitting module for a vehicle according to claim 1, characterized in that: The housing comprises a housing frame (6) and a housing cover (1) covering the housing frame, the two being connected by screws, a mounting hole (61) being provided on the inner side wall of the housing frame (6), and engaging parts (32) cooperating with the mounting hole (61) being provided on both sides of the flat light guide (3).

Images