Multicolor vehicle lamp and primary optical element for the lamp

Abstract

Multicolor vehicle lamp (1) and a primary optical element (3) for the lamp (1). The lamp (1) has at least two light sources (2) of different color, a primary optical element (3), and a secondary optical element (4). The primary optical element (3) comprises at least two parts (5), each part (5) comprising an input surface (6) and a corresponding output surface (7), wherein some light source (2) corresponds to each part (5) and is directed towards the input surface (6) of the corresponding part (5). Each part (5) is individually shaped for receiving and processing light of given wavelength from the corresponding light source (2) and directing the light towards the same area of the secondary optical element (4) as all the other parts (5). Both the optical elements then provide an output light beam (8) of the same shape and direction regardless of which of the at least two light sources (2) is turned on.

Description

Technical field

[0001] The present invention relates to vehicle illumination. More specifically, it relates to a vehicle lamp which can provide light of different colors from separate light sources. Such lamp can especially be used to switch illumination into a turquoise color when the vehicle is in an autonomous driving mode, while maintaining a required illumination pattern.Background of the Invention

[0002] Multicolor vehicle lamps are known in the state of the art. Typically, such a lamp can be used to emit orange light for turning indication as a first colored light and white or red light as a second colored light, depending on whether it is a front or rear lamp. Example of such a lamp is described in document EP1710487B1. This lamp includes multiple light sources of different colors and optical elements which are separate for each of the light sources. One lamp can thus provide different colors, but its construction is more complex since each light source has its own optical components.

[0003] Multicolor LEDs can be used in some applications to provide different colors of light using the same optical elements. However, multicolor LEDs of sufficient intensity are not available in all colors, so this approach is not always sufficient. For example, a sufficiently strong multicolor LED which could produce turquoise light is not currently available. Turquoise light could in future be universally used for indicating to other drivers that an autonomous driving mode is on, e.g., in daytime running lights or in low beam lights. Turquoise color nowadays needs to be provided by a separate light source. The two light sources needed to provide the at least two different colors of the multicolor lamp are thus different LEDs, which can be carried by the same PCB but have to be at least slightly spaced apart for construction and heat dissipation reasons. This spacing-apart prevents the use of one standard optical element for both light sources, because input angles of light are different from the different light sources and outputted light would have significantly different parameters (homogeneity, beam angle, distribution (i.e., what pattern is shown on the ground) etc.).

[0004] Turquoise illumination for autonomous driving mode is described for example in document US2021094585A1. The lamps used in this document for indication of the autonomous driving are however not multicolor.

[0005] The fact that different colors of light, i.e., different wavelengths, behave differently when processed by optical elements further complicates constructing multicolor lamps, because even if the different colors of light could be provided to the same optical element from the same direction, the outputted light would be different for different colors due to differences in reflection of different colors.

[0006] It would therefore be desirable to provide a way for constructing multicolor vehicle lamps which would provide substantially the same illumination pattern regardless of which color they output, and which would preferably have less complicated construction or smaller manufacturing cost.Summary of the Invention

[0007] The shortcomings of the solutions known in the prior art are to some extent eliminated by a multicolor vehicle lamp comprising at least two light sources, a primary optical element, and a secondary optical element. At least one light source has a different wavelength (i.e. color) of outputted light than another light source. There can thus be some light sources with the same color, but at least one light source has a different color. The colors are preferably chosen from colors commonly used and / or approved for different vehicle illumination and signal functions. E.g. one color can be orange and another color can be white.

[0008] Each of the at least two light sources is directed towards the primary optical element. The primary optical element thus receives and processes light from the light sources, at least one of which is of a different color. The primary optical element can thus process different colors / wavelengths of light, and preferably has its shape adapted to the specific color it is intended to be used with. E.g., the primary optical element is designed, especially by a computer modeling software, to process orange light and white light, with their specific wavelengths or combinations of wavelengths.

[0009] The primary optical element comprises at least two parts, each part comprising an input surface and a corresponding output surface. At least one of the light sources corresponds to each part and is directed towards the input surface of the corresponding part. Each part thus has at least one light source which illuminates its input surface, and its output surface then outputs the light, processed by the part, towards further optical components of the lamp. The lamp can also comprise further light sources than the ones corresponding to the input surfaces of the individual parts. The parts are preferably from a single piece of material, such as glass, polycarbonate or PMMA.

[0010] Each part is individually shaped for receiving and processing light of given wavelength from the corresponding light source and for directing the processed light towards the same area of the secondary optical element as all the other parts of the primary optical element. Each part thus receives the light from corresponding light sources, and outputs it towards the secondary optical element, such that the secondary optical element receives substantially the same light distribution from each part. In other words, the secondary optical element does not differentiate between the different colors of light, it processes and outputs them all the same, and the individual parts are thus configured such that they all output light having the same distribution. The distribution of light can encompass especially the shape of illumination pattern, i.e., what pattern shows on a surface illuminated by the part, and also homogeneity, output beam angle, intensity etc.

[0011] The shape of the parts, especially of its input surface, output surface and amount of material between them (i.e., the length of the part), can be given by a computer simulation, based on provided parameters, and then manufactured, e.g., by injection molding. The parameters include especially the type of respective light source (color, output beam angle, position relative to the input surface, homogeneity etc.) and requirements on the outputted light (homogeneity, presence of cutoff line, prescribed relationship between distance from the vehicle and illumination intensity etc.).

[0012] The input and / or output surface of each part can have any suitable shape and size, e.g., it can be spherical or parabolical, it can be freeform, it can include optical elements, especially micro-optical elements, which ensure the required processing of light, it can be divided into multiple subsurfaces, etc. Each part can have the same type of input and output surface, e.g., there can be micro-optical elements on each part, but the parts can also have different types of surfaces, e.g., some parts have micro-optical elements, other parts are substantially flat without such elements, etc.

[0013] The primary optical element and the secondary optical element are arranged for providing an output light beam of the same shape and direction regardless of which of the at least two light sources is turned on. The arrangement is ensured especially by the shape of the primary optical element. It can be further provided by shape of the secondary optical element and by position of the secondary optical element relative to the primary optical element. The secondary optical element can e.g., direct the light towards the required area on the road, improve homogeneity etc.

[0014] The secondary optical element has the same input surface for light from any of the at least two light sources. It can thus be made as known in the art, and only the primary optical element can then ensure the advantageous functioning of the invention. The secondary optical element can however also be shaped to ensure that the light from different light sources really has the same distribution when it leaves the lamp.

[0015] The present invention thus allows for switching between different colors of illumination, without affecting the final shape and distribution of light, as it appears to outside viewers. If the lamp is a headlight or a part thereof, the illumination is thus a projection on the road and around it, which e.g. illuminates the road ahead as far as required, does not blind oncoming drivers, illuminates traffic signs, informs other drivers about state of the vehicle carrying the lamp etc. For a taillight, the lamp especially makes the vehicle visible to other drivers, signals turning or braking, etc. The lamp can also be a decorative light, such as an illuminated emblem or a front grille and it can also be an interior vehicle light. Applications to headlights and taillights, however, are the most advantageous, because these lights have the strictest requirements on homogeneity and light distribution, which should not be deteriorated by changing color of illumination.

[0016] The construction of the lamp, especially the number of lamp components, is not significantly more complex than in a single-color lamp, since the optical elements are common for all the colors. Light sources of different colors are added, and the primary optical element has multiple parts, but the size of the lamp can be substantially the same as if it had only one color.

[0017] In the lamp according to the invention, the light from different light sources is thus processed into the same shape and distribution by a common optical element(s). The parts of the primary optical element do not influence each other significantly, there can be some parasitical light passing between the parts, e.g., a part with turned-off light source will not be completely dark, but this parasitical light does not significantly affect the overall outputted light, most of it gets absorbed by the lamp's casing. Preferably, the at least one light source of a different color than some other light source has sufficiently different color to clearly signal a different function to other drivers. Different colors usable for different functions have their prescribed values by laws in various countries, and such prescribed values can be used to choose the colors of the light sources for the lamp. A color-space metric can also be used to uniformly distinguish between the colors. E.g., the different colors preferably have a delta-e distance of at least 50 calculated by Cie76 algorithm to allow viewers a safe recognition of the different colors.

[0018] The at least two input surfaces of the primary optical element are preferably adjacent to each other, and the different corresponding light sources are preferably placed in the same plane, e.g., on the same PCB, to simplify assembly of the lamp. The different-color light sources can be turned on at the same time, to provide a mixed color, and / or can be turned on individually, to switch the illumination between their respective colors. The illumination pattern outputted from the lamp remains substantially the same in all these variants, only its intensity will be higher if more light sources are on at once.

[0019] At least one of the at least two light sources is preferably a turquoise light source and at least one of the at least two light sources is a white and / or orange light source. Turquoise color (e.g., hex code #30D5C8) can be used as an indication of an autonomous driving. The white and / or orange can be provided by an LED chip which can produce both colors, so that this white / orange light source can be used for daytime running lights or low beam or high beam etc., and can be used for turn signals. Orange or amber (e.g., hex code #FFC000) are commonly used in vehicle illumination for turn signals.

[0020] Each input surface and / or each output surface preferably comprises micro-optical elements for processing light. Micro-optical elements, e.g. with length and / or width of each element less than 1 mm, preferably less than 0.5 mm, can be effectively used to direct light individually by each of the elements, and can be designed by known computer programs. These elements can thus be used to process the light on each input surface and / or output surface such that the resulting light beam has the same shape regardless of which of the light sources is used.

[0021] The lamp preferably further comprises a control unit configured to control the light sources and to turn on light sources of a predetermined color when the vehicle is in an autonomous driving mode. The control unit can be unit corresponding to this lamp only but can also be a control unit for multiple lamps, or a control unit of the whole vehicle. The control unit can especially be configured to switch between white light and turquoise light, e.g., on a low beam or daytime running light, depending on whether the autonomous mode is on. The control unit can further be configured to switch the white / turquoise light for orange when a turn signal is on, such that there are three possible colors, and max one of them is outputted at once.

[0022] The configuration of the control unit can be provided by program instructions stored in a memory of the unit, which provide for the described functionality.

[0023] Each part of the primary optical element can form a lens with a focus and have one corresponding light source, wherein each light source is located in a focus of the corresponding part. Multi-color LED can have multiple semiconductor components which individually output light of different colors, but these components can be so close together, that they are both substantially in the focus and form one light source. Different light sources, however, such as a turquoise LED and white / orange / red LED, cannot be close enough to be both substantially in the focus, and thus need to have different corresponding parts of the primary optical elements.

[0024] The two light sources corresponding to two different parts of the primary optical element are preferably spaced apart at least 0.5 mm, preferably at least 1 mm, more preferably at least 2 mm or at least 5 mm. This distance is so large, that the light sources cannot use the same input surface if the output beam needs to have the same shape for both of them, so using the invention with multi-part primary optical element is especially advantageous. The distance between the light source can be even larger, and can depend especially on construction requirements and on providing a sufficient cooling of the light sources.

[0025] The two light sources corresponding to two different parts of the primary optical element can have a different output beam angle and / or homogeneity. This is often the case for LEDs of different colors, especially for colors not very commonly used in all today's vehicles, such as turquoise color. For these colors, LEDs suitable for vehicle illumination might not be available on the marked in sufficient variety, so it might be necessary to shape the primary optical element (one of its parts) according to a specific light source, instead of choosing a light source which has similar output parameters as another (e.g., white / orange) light source.

[0026] The shortcomings of the solutions known in the prior art are to some extent also eliminated by a primary optical element for processing light from at least two different light sources of different colors for use in the multicolor vehicle lamp according to the invention. The primary optical element comprises at least two parts, each part comprising an input surface for receiving light from at least one of the light sources which corresponds to the part, and each part further comprising an output surface. Each part is individually shaped, i.e., its shape is not necessarily influenced by shape of other parts, for receiving and processing light of given wavelength from the corresponding light source and directing the processed light towards the same area of a secondary optical element as all the other parts of the primary optical element. The primary optical element is shaped for providing a beam of light to the secondary optical element, wherein the beam has the same shape and distribution of light regardless of which of the input surfaces is illuminated by a corresponding light source.

[0027] After the primary optical element is mounted into a lamp, each part thus provides the same shape and homogeneity of illumination to the same area of the secondary part, as mentioned above for the lamp. Further details of the primary optical element were also described above, as were the advantages it can provide.Description of drawings

[0028] A summary of the invention is further described by means of exemplary embodiments thereof, which are described with reference to the accompanying drawings, in which: Fig 1.Shows a drawing of a side view of a vehicle lamp according to a first embodiment of the invention, where a primary optical element of the lamp has four parts for independent processing of light and four corresponding light sources. Fig 2.Shows a detailed front view of the primary optical element. Fig 3.Shows a schematical sideview of the lamp from fig. 1 and its main components. Fig 4.Shows a schematical drawing representing illumination of the lamp from fig. 3 when two upper light sources are turned on. Fig 5.Shows a schematical drawing representing illumination of the lamp from fig. 3 when two lower light sources are turned on, wherein the illumination pattern projected on the road has the same shape as in fig. 4 but is formed by light of a different color. Fig 6.Shows a perspective view of the primary optical element from fig. 2. Fig 7.Schematically shows a front view of a primary optical element from a second embodiment of the invention. Fig 8.Schematically shows a front view of a primary optical element from a third embodiment of the invention. Exemplary Embodiments of the Invention

[0029] The invention will be further described by means of exemplary embodiments with reference to the respective drawings.

[0030] A first embodiment of the invention is shown in figs. 1-6. This embodiment is a multicolor vehicle lamp 1 which is a low beam module for automobile headlight. The lamp 1 comprises four light sources 2, two white ones and two turquoise ones. It further comprises a primary optical element 3 and a secondary optical element 4, control unit 10 for controlling the light sources 2, and a casing and further standard optical, electronical and mechanical components of vehicle headlight modules, such as wiring, heat sinks, PCB for carrying all the light sources 2, sensors and actuators etc.

[0031] The light sources 2 are attached to the casing via the PCB (not shown) placed on the heat sink (not shown). The primary optical element 3 is in front of the light sources 2 and the secondary optical element 4 is in front of the primary optical element 3 and outputs light from the module. The light sources 2 are LEDs, and the secondary optical element 4 is made from PMMA and has homogenization pillow-shaped optical elements on its input surfaces 6 and output surfaces 7.

[0032] The primary optical element 3 is segmented into four parts 5, one for each of the light sources 2. There are thus two parts 5 for white light (upper parts 5 on fig. 2, above the dashed line) and two parts 5 for turquoise light (lower parts 5). The vertical distance between the light sources 2 is 10 mm in this embodiment, which is needed for sufficient cooling of the LEDs, but prevents using a single part 5 for both colors. Each color has a pair of corresponding parts 5 to increase intensity of the outputted light, but other than that, the parts 5 are independent of each other. The control unit 10 controls the light sources 2 based on information from the automobile's ECU such that only the white LEDs or only the turquoise LEDs can be turned on, and the turquoise LEDs are used whenever the automobile is in an autonomous driving mode. Both colors of light thus provide the same basic illumination function - low beam function, but the light is white standardly and turquoise when the driver is not actively driving.

[0033] Each part 5 of the primary optical element 3 has an input surface 6 and an output surface 7. The input surface 6 is substantially planar but is covered by micro-optical elements 9 in the form small sub-surfaces. The sub-surfaces have an area size of at most 0.5 mm 2< , and each has its own shape, inclination and potential curvature. Each of the sub-surfaces is individually designed (calculated) by a computer simulation such that it receives some light from the respective light source 2 and sends it towards an appropriate area of the output surface 7 such that a desired output light pattern is provided by the primary optical element 3.

[0034] The output surface 7 is curved, bulged outwards, but also has micro-optical elements 9 in the form of sub-surfaces, which are designed and shaped analogously to the input surface 6. The computer simulation providing these shapes is used to create a mold for injection molding which is used for creating these primary optical elements 3. The design takes into consideration the wavelength(s) of light provided by the corresponding light source 2, i.e., the parts 5 have different shape of micro-optical elements 9 and of the surfaces even though they provide the same illumination pattern and distribution. The design also takes into consideration parameters of the respective LED, its position relative to the input surface 6, relative position between the primary and secondary optical elements 4 and of course the desired outputted low beam distribution (e.g., a presence of a cut-off line) and position of the module in the final headlight. The LEDs have not only different color, but also different size of the output area, and different beam angles, which is all taken into consideration by the simulation during design and is thus reflected in the shape of the primary optical element 3.

[0035] Each part 5 thus has a corresponding light source 2 which illuminates the input surface 6. The light source 2 is located in the focus 11 of the corresponding part 5, i.e., the part 5 serves as a complex freeform lens (the light sources 2 and foci 11 in fig. 1 are only shown schematically by intersecting orthogonal dashed lines). The part 5 then processes the light into the low-beam pattern by both its surfaces and illuminates the input surface 6 of the secondary optical element 4. The same area of the secondary optical element 4 is illuminated by each of the parts 5, so the secondary optical part 5 does not "take notice" of which light sources 2 are currently on, it processes the light the same. The secondary optical element 4 does not change the overall illumination pattern or its shape, but it directs the light beam 8 carrying the pattern appropriately to a correct position on the road and it smooths out small inhomogeneities of the light from the primary optical element 3.

[0036] The control unit 10 can thus switch the colors without affecting other parameters of the low beam function. The secondary optical element 4 is illuminated substantially the same by each part 5 (see fig. 1 with the lines between the optical elements marking main output directions of the parts 5 meeting at the secondary optical element 4 and see figs. 4 and 5 schematically showing light rays from the white color parts 5 (fig. 4) and turquoise color parts 5 (fig. 5) - the light rays are directed differently but the resulting pattern on the road is the same and beam 8 outputted from the secondary optical element 4 has the same angle and light distribution). There can be some minor differences between the light distribution of different colors, but the difference is not perceivable by other drivers and does not impact conformity with legal requirements on low beams.

[0037] A second exemplary embodiment of the invention is shown in fig. 7. Construction of the lamp 1 in this embodiment is analogous to the first embodiment, except that there are only three parts 5 of the primary optical element 3 shown in fig. 7 and thus there are only three LED light sources 2 on the lamp's 1 PCB. Two parts 5 of the primary optical element 3 are next to each other (upper parts 5 on fig. 7) and the third part 5 is below both of them. The two upper parts 5 are for turquoise illumination, while the third part 5 below them is for white illumination.

[0038] The upper parts 5 have analogous construction to the first embodiment - they have substantially flat input surfaces 6 with micro-optical elements 9 and curved output surfaces 7 with micro-optical elements 9. The lower, third part 5 is sectionally curved, but the curvature is broken into several sections forming Fresnel-like lens, which are further divided by the micro-optical elements 9, as in the first embodiment. The primary optical element 3 is again designed by a computer simulation based on the color of the light, the desired output beam 8 shape etc.

[0039] The light of both colors in this embodiment thus provides the same function - low beam function. The white LED has a higher output intensity so that the illumination by both colors has substantially the same light distribution and intensity. Other features of the second embodiment are the same as in the first embodiment.

[0040] A third exemplary embodiment is shown in fig. 8. This embodiment differs from the second embodiment only in the shape of the third, lower part 5 of the primary optical element 3. The broken output surface 7 of the part 5 again forms a number of sections, but the break lines between them are circular.

[0041] A fourth exemplary embodiment is the primary optical element 3 from the lamp 1 from the first embodiment, as shown in figs. 2 and 6. The element is as described above and can be mounted into a low beam module with appropriate light sources 2 to provide the multicolor illumination. Alternatively, the individual primary optical elements 3 from the second and third embodiments can also represent further alternative embodiments of the invention.

[0042] A fifth embodiment of the invention has the same main features as the first embodiment, except that the module is a daytime running light module. The shape of the optical element is thus different, to provide the daytime running light function, but the main features, especially the division of the primary optical element 3 into parts 5, is analogous. The white LEDs are white / orange LED chips, known in the art. The light can thus be used for daytime illumination, in white or turquoise, and can also be used as a turn signal. The module can e.g., be a part 5 of an illuminated front grille, where the grille has two such modules, each adjacent to one headlight.

[0043] Further adaptations and modifications of the embodiments described above may be accomplished by one of ordinary skill in the art without departing from the scope of the present invention.

[0044] For example, in further alternative embodiments, different illumination functions, such as brake light, tail light, high beam, or fog light, as well as any of the functions mentioned above, can be used in any combination as the function(s) provided by the lamp 1. Different number of light sources 2, or of parts 5 of the primary optical element 3 can be used. Different types of micro-optical elements 9 can be used. In some embodiment, the micro-optical elements 9 are present on only the input surface 6 or only the output surface 7. In some embodiment, the surfaces can both be without any micro-optical elements 9. In some embodiments, one or more of the parts 5 can be provided with multiple light sources 2. The input surfaces 6 and / or output surfaces 7 can be substantially planar, curved, broken into section or a combination of these options.Reference list

[0045] 1.Lamp 2.Light source 3.Primary optical element 4.Secondary optical element 5.Part 6.Input surface 7.Output surface 8.Beam 9.Micro-optical element 10.Control unit 11.Focus

Claims

1. Multicolor vehicle lamp (1) comprising at least two light sources (2), a primary optical element (3), and a secondary optical element (4), wherein • at least one light source (2) has a different wavelength of outputted light than another light source (2), and • each of the at least two light sources (2) is directed towards the primary optical element (3), characterized in that • the primary optical element (3) comprises at least two parts (5), each part (5) comprising an input surface (6) and a corresponding output surface (7), wherein • at least one of the light sources (2) corresponds to each part (5) and is directed towards the input surface (6) of the corresponding part (5), wherein • each part (5) is individually shaped for receiving and processing light of given wavelength from the corresponding light source (2) and directing the processed light towards the same area of the secondary optical element (4) as all the other parts (5) of the primary optical element (3), wherein • the primary optical element (3) and the secondary optical element (4) are arranged for providing an output light beam (8) of the same shape and direction regardless of which of the at least two light sources (2) is turned on.

2. The multicolor vehicle lamp (1) according to claim 1 wherein at least one of the at least two light sources (2) is a turquoise light source (2) and at least one of the at least two light sources (2) is a white and / or orange light source (2).

3. The multicolor vehicle lamp (1) according to any preceding claim wherein each input surface (6) and / or each output surface (7) comprises micro-optical elements (9) for processing light.

4. The multicolor vehicle lamp (1) according to any preceding claim wherein the lamp (1) further comprises a control unit (10) configured to control the light sources (2) and to turn on light sources (2) of a predetermined color when the vehicle is in an autonomous driving mode.

5. The multicolor vehicle lamp (1) according to any preceding claim wherein each part (5) of the primary optical element (3) forms a lens with a focus (11) and has one corresponding light source (2), wherein each light source (2) is located in a focus (11) of the corresponding part (5).

6. The multicolor vehicle lamp (1) according to any preceding claim wherein two light sources (2) corresponding to two different parts (5) of the primary optical element (3) are spaced apart at least 0.5 mm.

7. The multicolor vehicle lamp (1) according to any preceding claim wherein two light sources (2) corresponding to two different parts (5) of the primary optical element (3) have a different output beam angle and / or homogeneity.

8. Primary optical element (3) for processing light from at least two different light sources (2) of different colors for use in a multicolor vehicle lamp (1) according to any preceding claim, characterized in that • the primary optical element (3) comprises at least two parts (5), each part (5) comprising an input surface (6) for receiving light from at least one of the light sources (2) which corresponds to the part (5), and each part (5) further comprising an output surface (7), wherein • each part (5) is individually shaped for receiving and processing light of given wavelength from the corresponding light source (2) and directing the processed light towards the same area of a secondary optical element (4) as all the other parts (5) of the primary optical element (3), wherein • the primary optical element (3) is shaped for providing a beam (8) of light to the secondary optical element (4), wherein the beam (8) has the same shape and distribution of light regardless of which of the input surfaces (6) is illuminated by a corresponding light source (2).

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