Lamp and headlighting arrangement for obtaining a color appearance in an automotive headlight

Abstract

A lamp 10 is described which may be used in an automotive headlight 12. The lamp 10 comprises at least one filament 20 within a transparent lamp vessel 16. A color filter portion 30 is provided through which light is emitted with a color change. The lamp vessel 16 further comprises a color transparent portion, through which light is emitted without a color change. The color transparent portion is arranged such that an illumination beam of light 40 is emitted through the color transparent portion to achieve a non-colored illumination. The color filter portion 30 is arranged such that only peripheral and/or scattered portions of light are emitted through the color filter portion to achieve a color appearance of the headlight 12 in operation of the lamp 10.

Claims

1. Lamp suitable for use in an automotive headlight, comprising: at least one filament arranged within a transparent lamp vessel, and the lamp vessel being bounded at one end of a longitudinal axis of the lamp by a top end and at another end of the longitudinal axis of the lamp by a lower end portion, said lamp vessel comprising: a color filter portion through which light is emitted with a color change, said color filter portion being arranged such that a peripheral or a scattered portion of light from said filament is emitted through said color filter portion to achieve a color appearance, a color transparent portion through which light is emitted without a color change, said color transparent portion being arranged such that an illumination beam of light is emitted from said filament through said color transparent portion to achieve a non-colored illumination, said color transparent portion, at least for part of the circumference of the lamp vessel, extending between the top end and the lower end portion, and an opaque top cover covering the top end, a surface of said top cover having a color corresponding to the color of the light emitted through said color filter portion.

2. Lamp according to claim 1, wherein: at least one shield is arranged adjacent to said filament to partly block light emitted from said filament into radial directions within an angular shielded region, and at least a part said color filter portion is arranged within said angular shielded region.

3. Lamp according to claim 2, wherein said color filter portion covers, in a central plane that is perpendicular to the longitudinal axis of the lamp, an angular region that is at least as wide as the angular shielded region.

4. Lamp according to claim 3, wherein said color filter portion has an angular width which is 120-160% of the width of the angular shielded region.

5. Lamp according to claim 2, wherein said color filter portion has a longitudinal extension along the longitudinal axis of said lamp which is 50-200% of the longitudinal extension of said shield.

6. Lamp according to claim 3, wherein said color filter portion is arranged non-symmetrically relative to said shield.

7. Lamp suitable for use in an automotive headlight, comprising: at least one filament arranged within a transparent lamp vessel, and the lamp vessel being bounded at one end of a longitudinal axis of the lamp by a top end and at another end of the longitudinal axis of the lamp by a lower end portion, said lamp vessel comprising: a color filter portion through which light is emitted with a color change, said color filter portion being arranged such that a peripheral or a scattered portion of light from said filament is emitted through said color filter portion to achieve a color appearance, a color transparent portion through which light is emitted without a color change, said color transparent portion being arranged such that an illumination beam of light is emitted from said filament through said color transparent portion to achieve a non-colored illumination, wherein: said color transparent portion, at least for part of the circumference of the lamp vessel, extends between the top end and the lower end portion, and said illumination beam of light is emitted in vertical directions forming angles of at least +/30 with a central plane in which a center of the filament is arranged, the central plane being oriented perpendicular to the longitudinal axis of the lamp.

8. Lamp according to claim 1, wherein said illumination beam of light is emitted in radial directions in a plane oriented perpendicular to the longitudinal axis of said lamp over an angular range of at least 120.

9. Lamp according to claim 1, wherein a second filament is arranged within said lamp vessel for emitting a high-beam illumination beam of light into all radial directions through said color transparent portion.

10. Lamp according to claim 1, wherein said color filter portion comprises a color filter coating provided on said lamp vessel.

11. Headlighting arrangement for a motor vehicle, comprising: a lamp according to claim 1, a reflector, where said reflector reflects said illumination beam of said lamp to form a non-colored illumination beam pattern projected along an optical axis, and where said scattered or peripheral portion of light is reflected in said reflector into peripheral directions to achieve a color appearance.

12. Lamp according to claim 7, wherein at least one shield is arranged adjacent to said filament to partly Hock light emitted from said filament into radial directions within an angular shielded region, and at least a part of said color filter portion is arranged within said angular shielded region.

13. Lamp according to claim 12, wherein: said color filter portion covers, in a central plane that is perpendicular to the longitudinal axis of the lamp, an angular region that is at least as wide as the angular shielded region.

14. Lamp according to claim 13, wherein said color filter portion has an angular width which is 120-160% of the width of the angular shielded region.

15. Lamp according to claim 12, wherein said color filter portion has a longitudinal extension along a longitudinal axis of said lamp which is 50-200% of the longitudinal extension of said shield.

16. Lamp according to claim 12, wherein said color filter portion is arranged non-symmetrically relative to said shield.

17. Lamp according to claim 7, wherein the lamp vessel further comprises an opaque top cover covering the top end, a surface of said top cover having color corresponding to the color of the light emitted through said color filter portion.

18. Lamp according to claim 7, wherein aid illumination beam of light is emitted in radial directions in a plane oriented perpendicular to the longitudinal axis of said lamp over an angular range of at least 120.

19. Lamp according to claim 7, wherein a second filament is arranged within said lamp vessel for emitting a high-beam illumination beam of light into all radial directions through said color transparent portion.

20. Lamp according to claim 7, wherein said color filter portion comprises a color filter coating provided on said lamp vessel.

21. Headlighting arrangement for a motor vehicle, comprising: a lamp according to claim 7, a reflector reflecting said illumination beam of said lamp to form a non-colored illumination beam pattern projected along an optical axis, and wherein said scattered or peripheral portion of light is reflected in said reflector into peripheral directions to achieve a color appearance.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The above and other objects, features and advantages of the present invention will become apparent from the following description of preferred embodiments, in which:

(2) FIG. 1 shows a side view of a first embodiment of a lamp;

(3) FIG. 2 shows a sectional view of the lamp of FIG. 1 with the section along line A . . . A;

(4) FIG. 3 shows a schematic side view of the lamp of FIG. 1, FIG. 2 arranged in a reflector;

(5) FIG. 4 shows in a top view a partly schematic representation of a motor vehicle with a headlight of FIG. 3;

(6) FIG. 5 shows a side view of a second embodiment of a lamp;

(7) FIG. 6 shows a side view of a third embodiment of a lamp.

(8) FIGS. 1 and 2 show a first embodiment of a halogen lamp 10 suited for use in a reflector 14 of a motor vehicle headlight 12 as schematically shown in FIG. 3.

DETAILED DESCRIPTION OF EMBODIMENTS

(9) The lamp 10 shown in the example of FIG. 1, FIG. 2 is a double filament halogen lamp. A glass vessel 16 which is transparent but has an opaque top 38 encloses a low-beam filament 20 and a high-beam filament 18, electrically connected and mechanically mounted to mounting wires. The lamp vessel 16 is sealed at a pinch portion 17, and the mounting wires extend through the pinch seal. An optical shield 22 is also arranged within the vessel 16 at one of the mounting wires and is positioned adjacent to the low-beam filament 20, i. e. covering the low-beam filament 20 over its full longitudinal extension in the direction of the longitudinal axis L. The shield 22 is provided as a curved metal sheet. It serves to block a portion of light which is emitted from filament 20 in operation into the direction of the shield 22.

(10) As shown in the sectional view of FIG. 2, a shielded region 24 is formed in a measurement plane A, oriented perpendicularly to the longitudinal axis L and positioned at the center of the low-beam filament 20. This shielded region in the example shown covers an angular range of about 150.

(11) An illumination beam portion 40 of the light emitted from the low-beam filament 20 is used, as schematically shown in FIG. 3, to achieve a main beam of illumination 40 on the road in front of the motor vehicle. The portion which is here regarded as the illumination beam of light 40, i. e. the main portion of the luminous flux, is emitted into radial angular regions of a width of 120 as shown in FIG. 2, centered in directions opposite to the position of the shield 22. In the side view of FIG. 1, the angular region of the illumination beam of light 40 covers a range of +/30 from the central plane A. In the context of the present embodiment, the portion of light emitted from the low-beam filament 20 into the thus defined angular regions is referred to as the illumination beam of light 40, whereas portions of light emitted into angular regions outside of this range are referred to as peripheral portions of light.

(12) The above described lamp is of a lamp type known as H4. In the reflector 14 shown in FIG. 3, the light of the illumination beam 40 emitted from the lamp 10 is reflected to the front of the motor vehicle to form a low-beam light intensity distribution, i. e. an intensity distribution with a roughly horizontal bright/dark cutoff. This low-beam distribution with a horizontal bright/dark cutoff is obtained in the reflector 14, because the main illumination beam 40 emitted from the low-beam filament 20 has, due to the partial shielding by the shield 22, already a bright/dark cutoff in the intensity distribution. In contrast, if the high-beam filament 18 is operated, which has no associated shield, the resulting light intensity distribution formed by the reflector 14 has no bright/dark cutoff.

(13) The light emitted from the filament 20 is of white color. In the present context, a white color will be referred to for light fulfilling the ECE requirements in this respect, i. e. for light with color coordinates within the white field.

(14) As the light emitted from the filament 20 passes through the glass wall of the lamp vessel 16, it remains white, i. e. does not undergo a color change. According to the present embodiment, the lamp 10 comprises a color filter portion provided as a color filter coating 30 on the outside of the lamp vessel 16.

(15) There are different possible embodiments of a color filter coating 30 which serves to absorb certain wavelengths of incident light, such that a white beam of light passing through the color filter coating 30 undergoes a color change. Also, different color effects may be achieved, such that the filtered light assumes e.g. green, yellow, pink/purple, orange, or blue color.

(16) In preferred examples, coatings with different absorption properties may be provided for different colors, e.g. with about 40% absorption for green, about 10% absorption for yellow, about 60% absorption for orange and about 50% absorption for blue, and about 60% absorption for a pink/purple color filter coating 30.

(17) Further, the opaque top coating 38 is provided with the same color as achieved by the color filter coating 30.

(18) Of the light emitted from the low-beam filament 20, the illumination beam of light 40, as defined by the above angular regions, passes through a portion of the lamp vessel 16 with no color filter, which in the present context will be referred to as a color transparent portion 32 of the lamp vessel 16.

(19) As visible from FIG. 1, FIG. 2, the color filter coating 30 of the first embodiment is applied to the lamp vessel 16 as a partial ring around the circumference of the lamp vessel 16, thus forming a partial cylinder surface. In longitudinal extension, along the longitudinal axis L, the color filter coating 30 overlaps the longitudinal extension of the low-beam filament 20; the lower ends thereof coincide, whereas the longitudinal extension of the color filter coating 30 is about twice the longitudinal extension of the low beam filament 20.

(20) In the measurement plane A, the color filter coating 30 is provided over the entire angular range of the shielded region 24. However, as shown, the color filter coating 30 extends beyond the shielded region 24 on both sides and overlaps with the non-shielded region by about 30 on one side of the shield 22, and by about 5 on the other side. The color filter coating 30 is thus arranged non-symmetrically to the shield 22, with a wider first peripheral portion 26a on one side and a more narrow second peripheral portion 26b on the other.

(21) The optical effect achieved by the partial color filter coating 30 is as follows: Since the color filter coating 30 is arranged such that the above defined illumination beam of light 40 passes only through the color transparent portions 32 of the lamp vessel 16, light emitted from the lamp 10 into the directions of the illumination beam of light 40 is not affected by the color filter coating 30. Thus, the illumination beam of light 40, as reflected by the reflector 14 of the headlight 12, achieves a non-colored illumination on the road in front of a vehicle 34 (FIG. 4).

(22) However, light emitted from the filament into the peripheral regions 26a, 26b (in the central plane A, shown in FIG. 2) pass through the color filter coating 30 and undergo a color change. Thus, these portions of light emitted from the lamp 10 will be correspondingly colored light. However, since this applies only to peripheral portions 26a,26b which in the reflector 14 are reflected under larger angles with the optical axis O, these will not substantially contribute to the color of the illumination in front of the motor vehicle, but will be reflected into peripheral directions, arranged at greater angles with the optical axis O.

(23) A further portion of light which will appear colored is scattered light passing through the color filter coating 30 in the shielded region 24. While the shielded region 24 is shielded from direct light from the low-beam filament 20, there will be a certain amount of light emitted from the low-beam filament 20 which is scattered, e. g. partially reflected at the wall of the lamp vessel 16, or at the holding wires therein, etc. This scattered portion of light will have a comparatively small amount of luminous flux as composed to the illumination beam 40. However, the scattered portion of light will be emitted as colored light into directions outside of the illumination beam 40, i. e. into directions where it will be noticeable if the headlight 12 is observed not directly from the front, but under larger angles with the optical axis O.

(24) A still further portion of light which will appear colored is scattered light reflected at the surface of the opaque, colored top cover 38. This scattered light will also be emitted into different directions, also outside of the illumination beam 40.

(25) In consequence, the optical effect obtained by the described lamp is such that the illumination beam of light 40 emitted from the lamp and reflected within the headlight 12 by the reflector 14 to illuminate the road in front of the motor vehicle 34 will be white (in the sense of the ECE regulations). However, if the headlight 12 is observed from the side, the scattered portion of light passing through the color filter coating 30 in the shielded region 24, the peripheral portions 26 of light passing from the low-beam filament directly through the color filter portion 30, and any scattered light portions reflected at the colored top 38 will achieve a strongly colored appearance in the headlight.

(26) FIG. 4 shows in a top view how the illumination beam pattern 40 of the headlight 12 is reflected onto the road in front of a motor vehicle 34 under relatively small angles with the optical axis O. Under these directions, a illumination beam 40 from the lamp 10 is effective, such that this illumination beam pattern is white.

(27) However, to an observer 36 looking from the side, i. e. under greater angles with the optical axis O, the scattered and reflected light portions and peripheral light portions 26 are strongly visible, such that the headlight 12 appears colored.

(28) The lamp 10 can thus be used as a standard automotive halogen lamp, e. g. a H4 lamp, which fully conforms to all regulation and standard requirements, while at the same time a surprising coloration effect may be observed in the headlight 12.

(29) FIG. 5 shows an example of a further embodiment of a lamp 110 with a differently shaped color filter coating 130. Since the second embodiment largely corresponds to the first embodiment, like parts are designated by like reference numerals.

(30) In the example of FIG. 5, the color filter coating 130 is not provided as a partial cylinder shape, but has, in the side view shown, a lower edge that is oriented under an angle to the measurement plane. As visible, the color filter coating 130 is arranged such that the main illumination beam 40 only passes through the color transparent portion 32 and remains uncolored.

(31) FIG. 6 shows a still further embodiment of a lamp 210. Again, parts corresponding to the first and second embodiments are designated by like reference numerals.

(32) The lamp 210 of the third embodiment is a single filament lamp, where consequently no shield is provided adjacent to the filament 20. For this type of lamp, which may e.g. be a H7 lamp, a color filter coating 230 as shown may be provided in a lower portion of the lamp vessel 16. The color filter coating 230 has a cylinder shape surrounding the lamp vessel 16. In the example shown, the color filter coating 32 extends between a pinch seal portion 17 and an upper edge. The upper edge of the color filter portion 230 is arranged below the filament 20. The color transparent portion 32 of the lamp vessel 16 is arranged directly adjacent, above the color filter portion 230 and surrounds the filament 20, such that, as visible from FIG. 6, the main illumination beam 40 only passes through the color transparent portion 32. Provided above and directly adjacent to the color transparent portion 32 is an opaque top covering 38, which is colored in the same color as the color filter portion 230.

(33) In the case of the lamp 210 which does not have a shield, both the color transparent portion 32 and the color filter portion 230 are cylinder-shaped and cover all 360 of radial directions. The lamp 210 achieves, as described above for the first and second embodiments, a white main illumination beam 40. However, due to reflection at the color top cover 38 and due to peripheral light portions as well as scattered light colored by the color filter portion 230, the light emitted from the lamp 210 and from a headlightl 1 equipped with the lamp 210 is perceived as having a color appearance.

(34) The invention has been illustrated and described in detail in the drawings and foregoing description. Such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments.

(35) A skilled person will recognize that a number of modifications may be made to the above described lamp. For example, the size and position of the color filter coating 30 may vary as long as a main illumination beam 40 remains uncolored.

(36) In the claims the word comprising does not exclude other elements, and the indefinite article a or an does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims or are described above in mutually different embodiments does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.