Light guide structure for vehicle light

Abstract

The application relates to the technical field of vehicle lighting devices, in particular to a light guide structure of a vehicle light, which comprises a base body made of optical-grade polycarbonate or polymethyl methacrylate, a light guide path structure layer embedded in the base body, a temperature control auxiliary forming component integrated in a mold, and an exhaust gas stabilizing structure arranged at a parting surface of the mold; the light guide path structure layer comprises a primary collimating surface group and a secondary refractive and reflective composite surface group; the temperature control auxiliary forming component is divided into zones for regulating and controlling cooling and slow cooling; and the exhaust gas stabilizing structure is cooperated with a pre-pressing chamber and a vacuum suction channel for exhaust gas. The application can improve the light transmission efficiency and forming quality of the thick-wall light guide piece.

Description

Technical Field

[0001] This invention relates to the field of vehicle lighting technology, specifically to a light guide structure for vehicle lights. Background Technology

[0002] Light guide structures for automotive lighting are a key component in achieving the optical performance of automotive lighting systems. Especially with the rapid development of new energy vehicles, higher demands are placed on the luminous efficiency, energy consumption, and reliability of automotive lights. Thick-walled optical components (thickness ≥ 6 mm) have been widely used in high-end vehicle headlights, taillights, and ambient lighting due to their ability to achieve precise beam control and uniform light output. These light guide structures are typically made of optical-grade PC or PMMA materials and guide light propagation through internal geometric design to meet specific lighting functional requirements.

[0003] Existing thick-walled light guide structures for automotive applications mostly employ a single light guide mode, with a relatively fixed internal optical unit layout, primarily relying on basic refraction or reflection principles for light path control. However, in practical applications, such structures have limitations in light utilization, making it difficult to simultaneously achieve the dual goals of high light transmittance and low energy consumption. Furthermore, in terms of molding processes, traditional injection molding methods are prone to defects such as shrinkage marks, warping, or internal bubbles due to uneven cooling rates when manufacturing thick-walled parts, affecting optical surface quality and structural stability, and consequently negatively impacting light emission uniformity. In addition, materials may experience light decay during long-term use, limiting the product's durability in harsh environments. Therefore, existing technologies still have room for improvement in light guide efficiency, molding precision, and long-term optical stability. To address this, we propose a light guide structure for automotive lighting. Summary of the Invention

[0004] This invention provides a light guide structure for automotive lights, which aims to improve the efficiency and uniformity of light transmission in thick-walled optical components, while also improving structural defects caused by uneven temperature distribution or gas residue during the molding stage, and enhancing the optical stability of the product under long-term use.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a light guide structure for automotive lighting, comprising a substrate, a light guide path construction layer, a temperature-controlled auxiliary molding component, and an exhaust stabilization structure, wherein: The substrate is made of optical-grade polycarbonate or polymethyl methacrylate, with an overall thickness between six and twenty millimeters. The shape is customized according to the space for the vehicle headlight assembly. After polishing, the surface roughness value is no greater than 0.02 micrometers to ensure that the incident light is not scattered or lost at the initial contact surface.

[0006] The light guide path construction layer is embedded inside the substrate and includes a primary collimating surface group and a secondary refractive and reflective composite surface group. The primary collimating surface group is arranged along the incident direction of the light, with each collimating surface arranged in a continuous stepped manner. The height difference between adjacent steps is controlled within 0.1 mm, which is used to initially converge the diverging beam emitted by the light source. The secondary refractive and reflective composite surface group is located downstream of the primary collimating surface group and is composed of multiple inclined surfaces and curved surfaces with different tilt angles. The spatial arrangement of each inclined surface and curved surface is optimized according to the ray tracing simulation results, so that the light undergoes at least two directional adjustments during propagation, and finally achieves a standard deviation of less than 5% in the illuminance distribution of the light-emitting area.

[0007] The temperature-controlled auxiliary molding component is integrated inside the base material manufacturing mold and includes a surface cooling zone, a transition buffer zone, and a core slow cooling zone. The surface cooling zone is close to the outer wall of the mold cavity and has a built-in serpentine flow channel that circulates a constant-temperature cooling medium. The cross-sectional dimensions of the flow channel gradually change with the curvature of the cavity to maintain a consistent solidification rate of the surface material. The transition buffer zone is located between the surface cooling zone and the core slow cooling zone and is equipped with an adjustable damping valve assembly. It adjusts the flow rate of the cooling medium based on real-time temperature feedback to keep the temperature gradient in this area decreasing by one to two degrees per millimeter of thickness. The core slow cooling zone corresponds to the thickest part of the base material and is equipped with an independent heating element. After injection filling, the heating program is delayed to allow the material in the central area to crystallize slowly, avoiding stress concentration caused by excessive internal and external temperature differences.

[0008] The venting stabilization structure is located at the intersection of the mold parting surface and the end of the material flow. It includes a pre-compression chamber, a vacuum suction channel, and a sealing baffle. The pre-compression chamber is located at the front end of the gate, and its volume is three to five percent of the total cavity volume. An elastic piston is installed in the chamber to expel compressed air before the melt is injected. The vacuum suction channel extends from the pre-compression chamber to the far end of the cavity. The inner wall of the channel is coated with a low-friction coating and connected to an external negative pressure source to continuously extract a small amount of volatile gas during the injection molding and holding pressure stage. The sealing baffle is installed at the outlet of the vacuum suction channel and is made of high-temperature resistant silicone. After being deformed under pressure, it fits tightly against the edge of the channel to prevent melt leakage while allowing gas to escape in one direction.

[0009] Optionally, an annular stress relief groove is added to the outer edge of the substrate. The groove is 0.5 mm deep and 1.2 mm wide, and is distributed at intervals in the non-optical functional area. It is used to absorb the local deformation energy generated during the molding shrinkage process and prevent the warping deformation from being transmitted to the light guide path structure layer.

[0010] Optionally, a microprism array is added to each step side of the primary collimating plane group, with a prism apex angle of 90 degrees and a period spacing of 0.08 mm, to perform secondary deflection on residual light rays that are not fully collimated, thereby improving the overall beam parallelism.

[0011] Optionally, a portion of the arc-shaped surface in the secondary refractive and reflective composite surface group is coated with a highly reflective metal film with a thickness of fifty nanometers and a reflectivity of not less than 95%. This film provides directional reflection of incident light at a specific angle, supplementing the brightness at the edge of the light-emitting area.

[0012] Optionally, the heating element in the temperature-controlled auxiliary molding component is a ceramic substrate resistance wire, embedded at a depth of 3.5 mm from the cavity surface, with a power density of 10 watts per square centimeter and a heating response time of less than 5 seconds, ensuring precise and controllable temperature field in the core slow cooling zone.

[0013] Optionally, a pressure sensor is connected to the end of the vacuum suction channel. The sensor samples 100 times per second and transmits the data to the central processing unit. When the pressure inside the channel rises above the set threshold, the negative pressure suction time is automatically extended until the pressure returns to the reference level.

[0014] Optionally, the back of the sealing baffle is equipped with a spring reset mechanism with a spring stiffness coefficient of 0.5 Newtons per millimeter. After the injection pressure is removed, the baffle is driven back to its original position, restoring the original geometry of the channel and facilitating the next round of molding operations.

[0015] Optionally, a positioning boss and mounting buckle are provided on the back of the base. The boss is 1.5 mm high and 4 mm in diameter. The buckle tongue is 8 mm long and the hook angle is 15 degrees. It is used to quickly align and lock with the headlight housing without the need for additional fasteners.

[0016] Optionally, the surface of the light guide path structure layer is covered with an anti-aging coating. The main components of the coating are ultraviolet absorbers and free radical quenchers. The coating thickness is 20 micrometers. After 5,000 hours of double 85 environmental testing, the light transmittance attenuation does not exceed 3 percentage points.

[0017] Optionally, an anti-fouling and hydrophobic membrane is composited on the outside of the anti-aging coating. The membrane has a contact angle of more than 110 degrees, which reduces the amount of dust particles adhering to the surface by more than 70% compared to the untreated surface, maintaining the cleanliness of the glossy surface during long-term use.

[0018] The light guide structure for automotive lighting provided by this invention has the following beneficial effects: This light guide structure, through the synergistic configuration of a primary collimating surface group and a secondary refractive and reflective composite surface group, transforms the original single-mode light guiding method into a multi-path dynamic control mechanism, effectively improving the luminous flux utilization rate per unit area and reducing the energy consumption ratio under the same lighting intensity. The temperature-controlled assisted molding component employs a zoned gradient temperature control strategy, forming a complete thermal management closed loop from rapid surface shaping to slow core cooling, significantly suppressing shrinkage marks and warping deformation problems common in thick-walled components, and ensuring the geometric accuracy of the light guide path. The venting stabilization structure combines pre-pressure venting and vacuum assistance to thoroughly remove residual gas from the cavity, preventing internal bubble formation and improving material density and structural integrity. The introduction of an anti-aging coating and a non-fouling hydrophobic film slows down the material performance degradation rate, adapts to harsh outdoor working environments, and extends product service life. In summary, this invention outperforms traditional thick-walled light guide structures in terms of light transmission efficiency, energy consumption control, molding yield, and durability, meeting the core requirements of new energy vehicles for high-performance optical components. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of this utility model; Figure 2 This is a schematic diagram of the primary collimation surface assembly of this utility model; Figure 3 This is a schematic diagram of the surface cooling zone of this utility model.

[0020] In the diagram: 1. Substrate; 2. Light guide path structure layer; 3. Primary collimation surface group; 4. Secondary refractive and reflective composite surface group; 5. Temperature control auxiliary molding component; 6. Surface cooling zone; 7. Core slow cooling zone; 8. Exhaust stabilization structure; 9. Sealing baffle; 10. Positioning boss. Detailed Implementation

[0021] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0022] Please see Figures 1 to 3This invention provides a light guide structure for automotive lighting. Its overall structure includes a substrate 1, a light guide path structure layer 2 embedded within the substrate 1, a temperature control auxiliary molding component 5 integrated into the molding die, and an exhaust stabilization structure 8 located at the parting surface of the mold and the end of the material flow. This structure is suitable for the manufacturing and assembly of thick-walled optical components in automotive headlights, daytime running lights, or taillight systems. Through structural design, the light transmission path is optimized, and temperature gradients and gas exhaust are controlled during the injection molding stage, ensuring that the final product has high light transmittance, low deformation, no bubble defects, and long-term environmental resistance.

[0023] The overall structure shown is as follows: the substrate 1 is injection molded from optical-grade polycarbonate material. Its shape is customized based on the internal cavity space of the front combination lamp assembly of a certain new energy vehicle model, exhibiting an asymmetrical curved shell shape. The maximum thickness is 16 mm, the minimum thickness is 6 mm, and the average thickness is 12 mm. The outer surface of the substrate 1 has a roughness value of 0.015 micrometers after mechanical polishing, while the inner surface retains the mirror gloss of the mold without any additional treatment. The back of the substrate 1 has four positioning bosses 10, distributed in the four corner areas. Each positioning boss 10 is 1.5 mm high and 4 mm in diameter, with a tapered guide slope at the top for initial positioning by engaging with a pre-set groove on the inner wall of the lamp housing. The edge area of ​​the substrate 1 has mounting clips with a tongue length of 8 mm, a barb angle of 15 degrees, a thickness of 1.2 mm at the base, and a thickness of 0.8 mm at the tip. Reinforcing ribs are provided on the back of the tongue to prevent breakage during assembly.

[0024] The light guide path construction layer 2 shown is partially enlarged. It is completely embedded within the substrate 1 and not exposed on the outer surface. Its structure includes a primary collimating surface group 3 and a secondary refractive and reflective composite surface group 4. The primary collimating surface group 3 is arranged along the incident direction of the light source, located three millimeters inside the end face of the substrate 1 closest to the LED light source. It consists of seventeen continuously arranged stepped reflective surfaces, with a height difference of 0.08 millimeters between each step and a fillet radius of 0.03 millimeters between adjacent steps to prevent light scattering at the corners. Each step's side is supplemented with a microprism array. The prism apex angle is 90 degrees, the periodic spacing is 0.08 millimeters, and the prism depth is 0.02 millimeters. The prism array covers 92% of the total area of ​​each step's side; the uncovered areas are where structural reinforcing ribs are located. The secondary refractive and reflective composite surface group 4 is located downstream of the primary collimating surface group 3, five millimeters from the end of the primary collimating surface group 3. It consists of nine groups of inclined surfaces and curved surfaces arranged alternately with different tilt angles. The first group of inclined surfaces has a tilt angle of 32 degrees, the second group of curved surfaces has a radius of curvature of 3.5 millimeters, the third group of inclined surfaces has a tilt angle of 41 degrees, and the fourth group of curved surfaces has a radius of curvature of 5.2 millimeters. The angles and curvatures of the subsequent groups are adjusted sequentially according to ray tracing simulation data, so that the light undergoes more than two directional changes in its propagation path. A high-reflectivity metal film is coated on some of the curved surface surfaces. The film material is aluminum, with a thickness of 50 nanometers and a measured reflectivity of 96.3%. The coating area is concentrated in the curved surface section where the light incident angle is greater than 60 degrees. The coating boundary adopts a gradient transition process to avoid diffraction effects at the edge of the film layer.

[0025] The diagram shows the fit between the base 1 and the temperature-controlled auxiliary molding component 5. The temperature-controlled auxiliary molding component 5 is an embedded structure within the mold and does not detach from the base 1. Its structure includes a surface cooling zone 6, a transition buffer zone, and a core slow-cooling zone 7. The surface cooling zone 6 is close to the outer wall of the mold cavity and has a built-in serpentine flow channel. The initial width of the flow channel cross-section is 2.5 mm, gradually increasing to 3.8 mm as the cavity curvature increases. The flow channel depth is constant at 1.2 mm. The cooling medium is an aqueous solution of ethylene glycol, with the inlet temperature controlled at 20 degrees Celsius and the outlet temperature fluctuation not exceeding ±0.5 degrees Celsius. The transition buffer zone is located between the surface cooling zone 6 and the core slow-cooling zone 7, with a thickness of 4 mm. It contains an adjustable damping valve assembly with a stainless steel valve core. The valve opening is adjusted by a stepper motor. The motor receives feedback signals from thermocouples embedded in the transition buffer zone. When the detected temperature difference exceeds 1.8 degrees Celsius per millimeter, it automatically reduces the valve opening by 15%, decreasing the cooling medium flow rate. The core slow cooling zone 7 corresponds to the thickest part of the substrate 1, that is, directly below the 16 mm thick area. A ceramic substrate resistance wire is configured as the heating element. The resistance wire is buried 3.5 mm from the surface of the cavity, with a power density of 10 watts per square centimeter. The resistance wire is arranged in a grid pattern with a grid spacing of 8 mm. Temperature sensors are installed at the grid intersections. The sensor sampling interval is 0.5 seconds. When the local temperature is detected to be 3 degrees Celsius lower than the set value, the heating of the resistance wire in the corresponding area is activated, and the temperature rise response time is 4.7 seconds.

[0026] The cross-sectional structure of the exhaust stabilization structure 8 shown is included. The exhaust stabilization structure 8 comprises a pre-compression chamber, a vacuum suction channel, and a sealing baffle 9. The pre-compression chamber is located at the front end of the gate, with a volume of 3.7% of the total cavity volume. An elastic piston, made of fluororubber with a Shore A hardness of 70A, has a diameter of 12 mm and a stroke of 8 mm. Before melt injection, a cylinder pushes and compresses the air in the chamber. After the compression stroke is completed, the cylinder maintains pressure for three seconds to ensure complete exhaust of residual gas. The vacuum suction channel extends from the pre-compression chamber to the far end of the cavity, with a total length of 210 mm and an inner diameter of 1.8 mm. The inner wall is coated with a PTFE coating with a thickness of 15 micrometers and a coefficient of friction of 0.04. A pressure sensor is connected to the end of the channel. The sensor has a range of 0 to -100 kPa and a sampling frequency of 100 times per second. Data is transmitted to an external controller via a shielded cable. When the pressure in the channel rises above -80 kPa, the controller extends the negative pressure source's operating time by 12 seconds until the pressure returns to the -90 kPa reference level. The sealing baffle 9 is installed at the outlet of the vacuum suction channel. The main body of the baffle is made of silicone with a thickness of 0.8 mm. A spring reset mechanism is provided on the back. The spring material is stainless steel wire with a wire diameter of 0.6 mm, a spring stiffness coefficient of 0.5 Newtons per millimeter, and a spring pre-compression of 1.2 mm. After the injection pressure is removed, the sealing baffle 9 is driven to return to its original position within 0.3 seconds, restoring the original geometry of the channel.

[0027] Annular stress relief grooves are provided in the non-optical functional area of ​​the outer edge of substrate 1. The grooves are 0.5 mm deep, 1.2 mm wide, and 5 mm apart. The radius of the bottom corners is 0.2 mm. The grooves are arranged in three rings, perpendicular to the main shrinkage direction of substrate 1, located at the upper, lower, and side edges of substrate 1. The stress relief grooves absorb local shrinkage strain energy during the injection molding cooling stage, preventing warping deformation from being transmitted to the light guide path structure layer 2. The surface of the light guide path structure layer 2 is covered with an anti-aging coating. The coating is prepared by mixing ultraviolet absorber UV-531 and free radical quencher HALS-770 in a mass ratio of 3:1. The coating method is spin coating at 800 revolutions per minute. The coating thickness is 20 micrometers. After 5,000 hours of dual 85 environmental testing, the light transmittance decreased from the initial 98.7% to 95.9%. The anti-aging coating has an outer composite antifouling and hydrophobic membrane. The membrane material is fluorinated acrylic resin. The measured contact angle is 113 degrees. The amount of dust particles adhering is reduced by 74% compared to the untreated surface. The surface energy of the membrane is 11.2 millinewtons per meter.

[0028] When assembling the base 1 with the headlight housing, first align the positioning boss 10 on the back of the base 1 with the preset groove on the inner wall of the housing, and apply an axial pressure of 3.5 Newtons to make the positioning boss 10 fully embedded in the groove. Then, push the base 1 along the direction of the housing slide rail until the assembly latch tongue passes the housing limit step. The latch tongue automatically locks under the action of elastic restoring force, with a locking force of 5.2 Newtons. After locking, the gap between the base 1 and the housing is less than 0.05 mm. After assembly, the light emitted by the LED light source enters from the incident end face of the base 1, and after being focused by the primary collimating surface group 3, the light divergence angle is reduced from the original 75 degrees to 28 degrees. Then, the propagation direction is adjusted by the secondary refractive and reflective composite surface group 4, and finally a uniform light spot with a standard deviation of 3.8 percent illuminance distribution is formed in the light-emitting area. Temperature control auxiliary molding component 5 ensures that the temperature difference between the inner and outer layers of the substrate 1 is always less than 1.5 degrees Celsius per millimeter during the injection molding stage. The venting stabilization structure 8 ensures that the volume fraction of residual gas in the cavity is less than 0.03 percent. After molding, there are no visible bubbles inside the substrate 1. The geometric contour error of the light guide path structure layer 2 is less than ±0.02 millimeters.

[0029] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of this invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A light guide structure for automotive lighting, characterized in that: It includes a substrate (1), a light guide path structure layer (2), a temperature-controlled auxiliary molding component (5), and an exhaust stabilization structure (8), wherein: The light guide path construction layer (2) is embedded inside the substrate (1) and includes a primary collimating surface group (3) arranged along the incident direction of light and a secondary refractive and reflective composite surface group (4) located downstream of it. The primary collimating surface group (3) is arranged in a continuous stepped manner, and the height difference between adjacent steps does not exceed 0.1 mm. The secondary refractive and reflective composite surface group (4) is composed of multiple inclined surfaces and arc-shaped curved surfaces with different tilt angles.

2. The light guide structure for automotive lighting according to claim 1, characterized in that: The exhaust stabilization structure (8) is located at the intersection of the mold parting surface and the end of the material flow, and includes a pre-compression chamber, a vacuum suction channel and a sealing baffle (9).

3. The light guide structure for automotive lighting according to claim 1, characterized in that: The temperature-controlled auxiliary molding component (5) is integrated inside the molding die and includes a surface cooling zone (6), a transition buffer zone and a core slow cooling zone (7).

4. The light guide structure for automotive lighting according to claim 1, characterized in that: Each step side of the primary collimation group (3) is equipped with a microprism array, with the prism apex angle being 90 degrees and the period spacing being 0.08 mm.

5. The light guide structure for automotive lighting according to claim 1, characterized in that: The secondary refractive and reflective composite surface group (4) has a portion of its arc-shaped surface coated with a high-reflectivity metal film layer with a thickness of fifty nanometers and a reflectivity of not less than 95%.

6. The light guide structure for automotive lighting according to claim 1, characterized in that: The core slow cooling zone (7) in the temperature-controlled auxiliary molding component (5) is equipped with a ceramic substrate resistance wire as a heating element, with a embedding depth of 3.5 mm from the surface of the cavity and a power density of 10 watts per square centimeter.

7. The light guide structure for automotive lighting according to claim 2, characterized in that: The vacuum suction channel is connected to a pressure sensor at its end, which samples 100 times per second and transmits the data to the central processing unit to control the negative pressure suction time.

8. The light guide structure for automotive lighting according to claim 1, characterized in that: The back of the substrate (1) is provided with a positioning boss (10) and an assembly buckle. The positioning boss (10) is 1.5 mm high and 4 mm in diameter. The tongue of the assembly buckle is 8 mm long and the hook angle is 15 degrees.

9. The light guide structure for automotive lighting according to claim 1, characterized in that: The substrate (1) is made of optical grade polycarbonate or polymethyl methacrylate material, with a thickness of six to twenty millimeters and a surface roughness of no more than 0.02 micrometers.

10. The light guide structure for automotive lighting according to claim 1, characterized in that: The outer edge of the substrate (1) is provided with an annular stress relief groove, which is 0.5 mm deep and 1.2 mm wide, and is distributed at intervals in the non-optical functional area.

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