A multi-reflection structure LED automobile low beam lamp

Abstract

The present invention discloses a multi-reflection structure LED automobile low beam lamp, which includes a light source with the normal direction of the light-emitting surface facing the projection area, an ellipsoidal reflector located obliquely above the light source, a first parabolic reflector located below the light source, and a second parabolic reflector located below the first parabolic reflector; the ellipsoidal reflector includes an ellipsoidal first focus and an ellipsoidal second focus, the focus of the first parabolic reflector overlaps with the first focus of the ellipsoidal reflector, and the focus of the second parabolic reflector overlaps with the second focus of the ellipsoidal reflector; an cut-off structure for allowing the projected light to form a light spot with a clear cut-off line between light and darkness is formed at the bottom of the ellipsoidal reflector. Through the system composed of the ellipsoidal reflector, the first parabolic reflector and the second parabolic reflector, the projected light spot has a clear cut-off line between light and darkness. The ellipsoidal reflector acts as both a reflector and a baffle, greatly improving the light energy utilization rate.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle lamp illumination, and particularly to a multiple reflection structure LED automotive low beam lamp. Background Art

[0002] With the development of social economy, automobiles have become an indispensable means of transportation in human society. In today's world, safety, environmental protection, and energy conservation have become the three major issues in the development of automobiles. The headlamp is the main lamp for illuminating the road ahead during night driving of an automobile and is an important component for ensuring the safe operation of the automobile. With the continuous improvement of the requirements for driving safety, correspondingly, it is required that the headlamp has performances such as a long illumination distance, good light distribution performance, and high luminous efficiency. According to the world automobile safety accident statistics, the probability of traffic accidents occurring at night is three times that during the day, and the accident rate in poor lighting conditions is three times that in good lighting conditions. It can be seen that good automobile lighting is of great significance for reducing traffic accidents and improving travel safety.

[0003] Traditional halogen light sources have advantages such as low cost and mature technology. However, the problem with halogen light sources is relatively high power consumption. In terms of energy conservation and emission reduction, LED light sources have high luminous efficiency, and their power consumption is only about one-third of that of halogen light sources. LED light sources have obvious advantages. With the continuous development of light source technology, LED light sources have become the first choice for a new generation of automotive light sources due to their advantages such as low energy consumption, long lifespan, good light quality, and fast startup time. Currently, LED light sources have been widely used in automotive brake lights, daytime running lights, and dashboard signal lights, etc. The white light of LED light sources is close to sunlight and is more suitable for the vision of drivers. With the improvement of the luminous efficiency and brightness of LED light sources, it becomes possible to replace traditional halogen light sources, etc. Therefore, LED headlamps will surely have a broad application prospect.

[0004] Automobile lamps can be divided into two major categories according to their functions, namely lighting lamps and signal lamps. Among them, the function of lighting lamps is to illuminate the road surface in front of the automobile in a dark environment, including headlamps, fog lamps, etc. The function of signal lamps is to indicate the presence of the vehicle itself to other road users, as well as that the vehicle is about to turn in a certain direction or is braking and decelerating, etc., to prompt other road users. Signal lamps mainly include turn indicator lamps, brake lamps, and position lamps, etc.

[0005] Automobile headlamps are the components with the highest requirements, the most complex structure, and the greatest difficulty in design and manufacture among all vehicle lamps. Its basic function is to illuminate the road surface in front, mainly including two types: high beam lamps and low beam lamps. High beam lamps are long-distance lighting lamps used when there are no other road users in front of the vehicle; while low beam lamps are short-distance lighting lamps used when there are other road users in front of the vehicle to avoid dazzling or discomfort to the other party. Compared with high beam lamps, the light distribution design of low beam lamps is much more complex.

[0006] Existing automotive headlights mainly include projection - type low - beam headlights and reflector - type low - beam headlights.

[0007] Common projection - type low - beam headlights mainly consist of an ellipsoidal reflector, a light shield, and a lens. Since the elliptical curve has the property of concentrating light, that is, the light emitted from the first focus of the ellipse will surely converge at the other focus of the ellipse after being reflected by the ellipse. Using this feature, in the projection system, the light source and the light shield are respectively placed at the first focus and the second focus of the ellipsoid, and the focus of the lens coincides with the second focus of the ellipsoid. These three optical devices together form a co - axial optical system of projection type. After being refracted by the lens, the diverging light beam is converged towards the center, forming an effective illumination light pattern, thus meeting the requirements of the low - beam headlight regulations. However, the biggest drawback of the projection - type low - beam headlight is that: most of the light is blocked by the light shield, resulting in a low light utilization rate of the entire system.

[0008] In the development of the entire electric light source, reflector - type low - beam headlights basically use a parabolic reflector. The basic surface shape of the reflector of this structure is formed by rotating a parabola around its axis. The center of the light source is at the focus of the reflector. After the reflector collects the light beam, it emits the light beam as parallel light, which is refracted by the light distribution lens and then output. The light distribution lens usually uses prisms and cylindrical patterns to refract the parallel light into the required light pattern. At the same time of forming refraction, a part of the light will also be scattered. Therefore, the light energy utilization rate of this structure is only about 55%. The rest of the light is reflected upward like the high - beam light, forming a dazzling light that is not allowed by the regulations. For this reason, a light shield must be added to form the cut - off line of light and darkness required by the regulations. Summary of the Invention

[0009] In view of this, the purpose of the present invention is to overcome the deficiencies of the prior art and provide a multi - reflection - structure LED automotive low - beam headlight with a simple structure, high light energy utilization rate, and capable of forming a light spot with an obvious cut - off line of light and darkness.

[0010] To solve the above - mentioned technical problems, the present invention is implemented as follows:

[0011] A multi-reflection structure LED automotive low beam headlight, comprising a light source whose normal direction of the light-emitting surface faces the projection area (regarding the light source as a light-emitting point, its light-emitting range can be approximately regarded as 180°, and the light intensity in the normal direction is the largest), an ellipsoidal reflector located obliquely above the light source (the ellipsoidal reflector is obtained by rotating an ellipse around its major axis), a first parabolic reflector located below the light source, and a second parabolic reflector located below the first parabolic reflector (the parabolic reflector is obtained by rotating a parabola around its axis of symmetry); the ellipsoidal reflector includes an ellipsoidal first focus and an ellipsoidal second focus, the focus of the first parabolic reflector overlaps with the first focus of the ellipsoidal reflector, and the focus of the second parabolic reflector overlaps with the second focus of the ellipsoidal reflector; an cut-off structure for making the projected light form a light spot with a cut-off line of light and dark is formed at the bottom of the ellipsoidal reflector.

[0012] For a traditional projection-type structure low beam headlight, the ellipsoidal reflector mainly receives light from the light source and focuses it near the second focus, and the light shield is mainly used to block the light that is likely to form glare at the lower part of the reflector; for the light passing through the light shield, if there is no secondary focusing by the lens, it will diverge rapidly. Therefore, the focus of the lens is set near the second focus of the ellipsoid. After refraction by the lens, the diverging light beam is converged towards the center to form an effective lighting pattern. As described in the technical background, the projection-type structure low beam headlight has a low light utilization rate of the entire system because the light shield blocks most of the light. Moreover, since it requires a lens for focusing, the design of the headlight becomes complicated because the spherical lens has spherical aberration and its optical quality is low. The radius of curvature of the aspherical lens changes along the central axis, basically eliminating the spherical aberration generated by the spherical lens. However, it is difficult to obtain a continuous curvature by adjusting the surface constant and the aspherical coefficient to meet the requirements of automotive headlamps, and the probability of errors is also relatively high.

[0013] In this application, the ellipsoidal mirror acts as both a reflector and a baffle. The baffle function of the ellipsoidal mirror does not block the light emitted by the light source, but reflects this part of the light to the second parabolic mirror, which is then reflected by the second parabolic mirror to the illumination area. The light passing through the light and dark cut-off structure forms a light spot with a clear light and dark cut-off line in the illumination area. Therefore, this application can achieve the purpose of forming a light spot with a clear light and dark cut-off line and greatly improving the light utilization rate. Further, in order to eliminate the disadvantages brought by setting up complex lenses, in this application, a first parabolic mirror is arranged below the light source to reflect the light emitted by the light source obliquely downward to the front. In traditional parabolic low-beam headlights, the light emitted by the light source needs to be refracted by the light distribution mirror before output. This process not only has scattering, but also requires an additional light shield to form a light and dark cut-off line, and its light energy utilization rate is also not high. In this application, due to the presence of the ellipsoidal mirror, the first parabolic mirror does not need to refract the light above the optical axis through the light distribution mirror. Moreover, because the ellipsoidal mirror has a structure for forming a light spot with a light and dark cut-off line, the first parabolic mirror does not need to add an additional light shield. For the second parabolic mirror, which is located below the first parabolic mirror, the light it reflects can effectively superimpose and enhance the effect below the light and dark cut-off line of the projected light spot, making the light color more uniform and improving driving safety.

[0014] As described above, this application forms a light spot with an obvious light and dark cut-off line in the illumination area through the above structure, preventing glare to the drivers of oncoming vehicles. In order to ensure sufficient road lighting when the vehicle is driving, the bottom of the ellipsoidal mirror described in this application extends downward so that it is sufficient to reflect the light emitted by the light source in the normal direction to the second parabolic mirror. The second parabolic mirror projects the light in an almost parallel manner to the illumination area, making the light spot in the area below the light and dark cut-off line have uniform color mixing.

[0015] The light emission of the light source can be regarded as 180°. Since in this application, the normal direction of the light source's light emission is towards the illumination area, an ellipsoidal mirror is arranged obliquely above it to reflect the light emitted by the light source obliquely upward to the second parabolic surface. In order to improve the utilization rate of the light source, the top of the ellipsoidal mirror extends upward so that it is sufficient to reflect the light emitted by the light source upward to the second parabolic mirror. Through the above design, the light energy at the edge of the light source is fully utilized, further improving the utilization rate of the light source.

[0016] Further, the present application provides another solution. The bottom of the ellipsoidal mirror extends downward such that it is sufficient to reflect a part of the light rays below the normal direction of the light source to the second parabolic mirror. Since the light intensity in the normal direction of the light source is the maximum, the light rays near the normal direction of the light source are reflected to the second parabolic mirror, and the second parabolic mirror then projects the light rays to the illumination area, so that in the formed light spot, the color mixing in the area below the light and dark cut-off line is uniform, meeting the lighting requirements of the headlamp.

[0017] On traditional vehicle lamps, to form a relatively clear light and dark cut-off line, corresponding settings need to be made to the light shield. The function of the light shield is to block a part of the projected light rays to form the light and dark cut-off line. In the present application, a light and dark cut-off structure is directly provided on the ellipsoidal mirror. The light and dark cut-off structure includes a protruding part at the bottom of the ellipsoidal mirror, an inclined part adjacent to the protruding part, and a horizontal part adjacent to the inclined part, without the need to set an additional structure to form the light and dark cut-off line, making the entire system structure simpler.

[0018] Generally, the low beam light pattern required for driving on the road is an asymmetric light pattern with a relatively wide beam illumination range in the horizontal direction and a relatively narrow beam illumination range in the vertical direction. In the present application, through the settings of the first parabolic mirror and the second parabolic mirror, the light distribution of the low beam light pattern is satisfied. Moreover, by extending the first parabolic mirror towards the normal direction of the light source, the light rays below the normal direction of the light source are directed towards the illumination area and the first parabolic mirror. Part of the light rays emitted by the light source obliquely downward are directly projected onto the illumination area, achieving an effective superposition with the light rays projected by the first parabolic mirror and the second parabolic mirror, making the light spot more uniform and the lighting effect better. At the same time, through such a design, the structure of the lamp can be minimized, without causing the vehicle lamp to be too long axially and occupying too much space of the vehicle.

[0019] As described above, the light distribution of the low beam light pattern is an asymmetric light pattern with a relatively wide beam illumination range in the horizontal direction and a relatively narrow beam illumination range in the vertical direction. Therefore, in the present application, in the first parabolic mirror, the distance from the focus to the directrix of the parabola is P1, and in the second parabolic mirror, the distance from the focus to the directrix of the parabola is P2, and P1 < P2. That is, the second parabolic mirror is smaller than the first parabolic mirror. After the light rays reflected by the second parabolic mirror are effectively superposed with the light rays reflected by the first parabolic mirror, the projected light spot is arc-shaped below, and the light illumination is uniform, without making the brightness within 25 meters in front of the vehicle too large, preventing the driver from feeling uncomfortable due to too large a difference in illuminance from other road surfaces.

[0020] Through a large number of tests by the inventor, the size parameters of each component are determined. In the ellipsoidal mirror, the minor axis a is 32.15 - 43.67, and the major axis b is 55.62 - 82.54; in the first parabolic mirror, its parabola P1 is 4.85 - 11.25, and in the second parabolic mirror, its parabola P2 is 4.14 - 9.38. The structural sizes of the ellipsoidal mirror, the first parabolic mirror, and the second parabolic mirror are coordinated to make the structure fit properly and achieve the best light reflection effect.

[0021] Furthermore, in order to project to the front of the vehicle at an appropriate distance, with the normal direction of the light source as the reference, the angle between the major axis of the ellipsoidal mirror and the normal is 40 - 50°, the angle between the symmetry axis of the first parabolic mirror and the normal is 1 - 4°, and the angle between the symmetry axis of the second parabolic mirror and the normal is 1 - 4°.

[0022] Preferably, the light source is an LED light source.

[0023] Compared with the prior art, the present invention has the following beneficial effects: In this application, a multi-reflection structure LED automobile low beam lamp is composed of an ellipsoidal mirror, a first parabolic mirror, and a second parabolic mirror, so that the projected light spot has a clear cut-off line between light and dark. The ellipsoidal mirror acts as both a reflector and a baffle, greatly improving the light energy utilization rate. Through the first parabolic mirror and the second parabolic mirror, the illumination area below the cut-off line between light and dark has uniform mixed light, preventing visual discomfort to the driver. Description of the Drawings

[0024] Figure 1 It is a schematic structural diagram of a multi-reflection structure LED automobile low beam lamp;

[0025] Figure 2 It is a cross-sectional view of a multi-reflection structure LED automobile low beam lamp;

[0026] Figure 3 It is a side view of a multi-reflection structure LED automobile low beam lamp (from the optical axis to the reflector);

[0027] Figure 4 It is a schematic diagram of the normal direction of the light source;

[0028] Figure 5 It is an optical schematic diagram of the embodiment;

[0029] Figure 6 It is a schematic diagram of the light spot. Detailed Embodiments

[0030] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described below with reference to the accompanying drawings. Embodiment

[0031] As Figures 1 - 6 , a multiple - reflection - structure LED automotive low - beam headlight, which includes an LED light source 400 with the normal direction of its light - emitting surface facing the projection area, an ellipsoidal reflector 100 located obliquely above the LED light source 400, a first parabolic reflector 300 located below the LED light source 400, and a second parabolic reflector 200 located below the first parabolic reflector 300; the ellipsoidal reflector 100 includes an ellipsoidal first focus and an ellipsoidal second focus, the focus of the first parabolic reflector 300 overlaps with the ellipsoidal first focus, and the focus of the second parabolic reflector 200 overlaps with the ellipsoidal second focus; a cut - off structure for forming a light spot with a cut - off line of light and dark is formed at the bottom of the ellipsoidal reflector 100, and the cut - off structure includes a protrusion 130 located at the bottom of the ellipsoidal reflector 100, an inclined - angle part 120 adjacent to the protrusion 130, and a horizontal part 110 adjacent to the inclined - angle part 120.

[0032] Among them, the bottom of the ellipsoidal reflector 100 extends downward so that it is sufficient to reflect the light emitted by the LED light source 400 in the normal direction to the second parabolic reflector 200. The top of the ellipsoidal reflector 100 extends upward so that it is sufficient to reflect the light emitted by the LED light source upward to the second parabolic reflector 200. The first parabolic reflector 300 extends in the normal direction of the LED light source 400 so that the light located below the normal direction of the LED light source 400 is directed to the illumination area and the first parabolic reflector 300.

[0033] In the first parabolic reflector 300, the distance from the focus to the directrix of its parabola is P1, and in the second parabolic reflector 200, the distance from the focus to the directrix of the parabola is P2, and P1 < P2.

[0034] As Figure 5 shown, the ellipsoidal reflector is composed of GHIJK, the GH segment is the effective part of the reflected - light entity, and the rest of the dotted lines are schematic diagrams for principle and for optical - design assistance. The first parabolic reflector is composed of AHBCD, the CD segment is the effective part of the reflected - light entity, and the rest of the dotted lines are schematic diagrams for principle and for optical - design assistance. The second parabolic reflector is composed of LMNOP, the MNOP segment is the effective part of the reflected - light entity, and the rest of the dotted lines are schematic diagrams for principle and for optical - design assistance.

[0035] As Figure 6As shown, the multi-reflection structure LED automotive low beam projects light, forming a receiving light spot at 25 meters, meeting the requirements for the low beam part of automotive headlamps. It has an obvious horizontal light and dark cut-off line 530, a conversion part light and dark cut-off line 520, and a prominent light part light and dark cut-off line 510. Below the horizontal line at 25 meters is a semi-elliptical light spot. Among them, the light and dark cut-off structure includes a protruding part 130, an inclined angle part 120, and a horizontal part 110. The corresponding part of the receiving light spot is the horizontal light and dark cut-off line 530, the conversion part light and dark cut-off line 520, and the prominent light part light and dark cut-off line 510. The semi-elliptical light spot below the horizontal line is formed by the control of the first parabolic mirror and the second parabolic mirror.

[0036] The above embodiments are only specific implementation manners of the present invention, and the description thereof is relatively specific and detailed, but it should not be construed as a limitation on the scope of the present invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can be made, and these obvious replacement forms all belong to the protection scope of the present invention.

Claims

1. A multi-reflection structure LED automotive low beam headlight, characterized in that, A light source with the normal direction of the light-emitting surface facing the projection area, an ellipsoidal reflector located obliquely above the light source, a first parabolic reflector located below the light source, and a second parabolic reflector located below the first parabolic reflector; The ellipsoidal reflector includes an ellipsoidal first focus and an ellipsoidal second focus. The focus of the first parabolic reflector overlaps with the first focus of the ellipsoidal reflector, and the focus of the second parabolic reflector overlaps with the second focus of the ellipsoidal reflector; An intensity cutoff structure for allowing the projected light to form a light spot with an intensity cutoff line is formed at the bottom of the ellipsoidal reflector.

2. The multi-reflection structure LED low beam headlamp for vehicle according to claim 1, wherein, The bottom of the ellipsoidal reflector extends downward so that it is sufficient to reflect the light emitted by the light source in the normal direction to the second parabolic reflector.

3. The multi-reflection structure LED automotive low beam lamp according to claim 1 or 2, characterized in that, The top of the ellipsoidal reflector extends upward so that it is sufficient to reflect the light emitted by the light source upward to the second parabolic reflector.

4. The multi-reflection structure LED automotive low beam lamp according to claim 1, wherein, The bottom of the ellipsoidal reflector extends downward so that it is sufficient to reflect a part of the light below the normal direction of the light source to the second parabolic reflector.

5. The multi-reflection structure LED automotive low beam lamp according to claim 1, wherein, The intensity cutoff structure includes a protrusion at the bottom of the ellipsoidal reflector, an inclined angle part adjacent to the protrusion, and a horizontal part adjacent to the inclined angle part.

6. The multi-reflection structure LED automotive low beam headlamp according to claim 1, wherein, The first parabolic reflector extends in the normal direction of the light source so that the light below the normal direction of the light source is projected onto the illumination area and the first parabolic reflector.

7. The multi-reflection structure LED automotive low beam lamp according to claim 1, characterized in that, In the first parabolic reflector, the distance from the focus to the directrix of the parabola is P1, and in the second parabolic reflector, the distance from the focus to the directrix of the parabola is P2, and P1 < P2.

8. The multi-reflection structure LED automotive low beam lamp according to claim 1, characterized in that In the ellipsoidal reflector, the minor axis a is 32.15 mm to 43.67 mm, and the major axis b is 55.62 mm to 82.54 mm; In the first parabolic reflector, its parabola P1 is 4.85 mm to 11.25 mm, and in the second parabolic reflector, its parabola P2 is 4.14 mm to 9.38 mm, and P1 < P2.

9. The multi-reflection structure LED automotive low beam headlamp according to claim 1, wherein, Based on the normal direction of the light source, the angle between the major axis of the ellipsoidal reflector and the normal is 40 to 50°, the angle between the symmetry axis of the first parabolic reflector and the normal is 1 to 4°, and the angle between the symmetry axis of the second parabolic reflector and the normal is 1 to 4°.

10. The multi-reflection structure LED automotive low beam headlamp according to claim 1, characterized in that, The light source is an LED light source.

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