Automotive front lighting lamp with baffle

Abstract

A lamp for automotive vehicle front lighting is described. The lamp 10 comprises a base 12 for mechanical and electrical connection to an automotive headlight 50 and a burner 14 fixed to the base 12. The burner 14 comprises an enclosed transparent vessel 22. A first and a second filament 34, 36 are arranged within the vessel 22. A baffle 40 is arranged proximate to the first filament 34 to shield the second filament 36 from the first filament 34. The baffle 40 is of concave shape and includes a bottom surface 41 and side surfaces 45 terminating in side edges 48. The baffle 40 further includes a front surface 43 arranged between the first and second filaments 34, 36 to shield the second filament 36 from light emitted from the first filament 34. The side edges 48 each comprise a central portion 54 extending, in side view, straight and in parallel to the longitudinal axis X. The straight central portions 54 have an axial length of at least 3.5 mm. An edge height H.sub.E is defined as a distance between the bottom surface 41 and the plane defined between the central portions 54 of the side edges 48. The edge height is more than 2.8 mm.

Claims

1. Lamp for automotive vehicle front lighting, comprising a base for mechanical and electrical connection to an automotive headlight, said base having a longitudinal axis, a burner fixed to said base, said burner comprising an enclosed transparent vessel, at least a first and a second filament arranged within said vessel, and a baffle arranged proximate to said first filament to partially shield light emitted from said first filament, wherein said baffle is of concave shape and includes at least a bottom surface and side surfaces, said side surfaces terminating in side edges, and wherein said baffle further includes a front surface arranged at an axial front end of said baffle, the axial front end being the axial end of said baffle closest to the second filament, where at least a part of said front surface is arranged between said first and second filaments to shield said second filament from light emitted from said first filament, wherein the front surface extends higher than the side edges of the baffle, and wherein the front surface and the side edges form a sloping transition, wherein said side edges each comprise a central portion extending, in a side view, at least straight and in parallel to said longitudinal axis, said straight central portions starting, in a side view, at a distance (a) along said longitudinal axis from said front end of no more than 2.8 mm, and wherein an edge height is defined as a distance between said bottom surface and a plane defined between said straight central portions of said side edges, where said edge height is more than 2.8 mm.

2. Lamp according to claim 1, where said straight central portions of said side edges start, in side view, at a distance parallel to said longitudinal axis within an axial range of 1.4-2.8 mm from said front end of said baffle.

3. Lamp according to claim 2, where said straight central portions start within an axial range of 1.7-2.5 mm from said first end.

4. Lamp according to claim 1, where said straight central portions extend, in side view, straight and in parallel to said longitudinal axis over an axial length of at least 3.5 mm.

5. Lamp according to claim 1, where said baffle comprises, at a back end located opposite to said front end, a flat attachment member oriented in parallel to said bottom surface, where said attachment member is arranged in a plane distant from a plane of said bottom surface by an attachment member height, where said attachment member height is less than said edge height.

6. Lamp according to claim 1, where said front surface extends up to a front height defined as a distance from said bottom surface, where said front height is more than 3.5 mm.

7. Lamp according to claim 1, where said first filament is provided as a winding structure around a first filament axis which is oriented in parallel to said longitudinal axis, where a first filament distance is defined as a distance between an upper edge of said first filament and said plane defined by said straight central portions of said side edges, where said first filament distance is less than 0.75 mm.

8. Lamp according to claim 1, where said first filament extends over a first axial filament length parallel to said longitudinal axis, where said straight central portions of said side edges are arranged over at least 70% of said first axial filament length.

9. Lamp according to claim 1, where said second filament is provided as a winding structure around a second filament axis which is oriented in parallel to said longitudinal axis, where a second filament height is defined as a distance between said second filament axis and said plane of said bottom surface of said baffle, where said second filament height is less than said edge height.

10. Lamp according to claim 1, where said base comprises a reference protrusion defining a radial reference direction, where said filaments and said baffle are symmetrical to a symmetry plane defined by said longitudinal axis and said radial reference direction.

11. Vehicle headlight comprising a reflector, and a lamp according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the drawings

(2) FIG. 1 shows a perspective view of a lamp according to an embodiment of the invention;

(3) FIG. 2 shows a side view of the lamp of FIG. 1 in the horizontal operating position;

(4) FIG. 3 shows an enlarged sectional view of a portion of the lamp of FIG. 1 with the section taken along line R in FIG. 1;

(5) FIG. 5 shows in a schematic representation a vehicle headlight with a lamp according to FIGS. 1-4

(6) FIG. 4 shows an enlarged sectional view of the baffle of FIGS. 1-3.

DETAILED DESCRIPTION OF EMBODIMENTS

(7) FIGS. 1, 2 show an automotive halogen lamp 10.

(8) The lamp 10 comprises a base 12 and a burner 14 fixed to the base 12.

(9) The base 12 comprises a positioning ring 16 which includes three positioning protrusions 18a, 18b radially protruding from the base 12 (of which only two are shown in FIG. 1).

(10) The lamp 10 may be fixed to a vehicle headlight so as symbolically shown in FIG. 5 where the exact position is determined by the protrusions 18a, 18b. The protrusion 18b serves as a reference protrusion defining the reference direction R. A reference plane for the mounting position of the lamp 10 in the reflector 46 may be defined by the upper portions of the three positioning protrusions. A lamp axis X may be defined as longitudinal axis of the lamp 10 perpendicular to this reference plane through the center of the positioning ring 16. The radial reference direction R is defined by the center of the reference protrusion 18b.

(11) The burner 14 comprises a glass vessel 22 with a central portion 24 of circular cylindrical shape. At the top, the otherwise transparent vessel 22 comprises a coated portion 26 which is opaque. At the bottom, the vessel 22 is sealed in a pinch seal 28, which is fixed to the base 12. The glass vessel 22 is arranged such that its central longitudinal axis (vessel axis) is in parallel to the lamp axis X, but arranged at an offset, i.e. a transversal distance.

(12) Projecting from the pinch seal 28 into the interior of the vessel 22 are three holding wires 30a, 30b, 30c. The holding wires 30a, 30b, 30c are further fixed by a holding bar 32 arranged distant from the pinch seal 28. Further, fixed to the holding wires 30a, 30b, 30c are arranged a first filament 34 (low-beam filament) and a second filament 36 (high-beam filament).

(13) Proximate to the first filament 34, a baffle 40 is arranged. As shown, the baffle is provided to cover the axial extent of the first filament 34 and thus partially shield light emitted from the filament 34 into radial directions. Further, a front portion 42 of the baffle 40 is arranged in between the first and second filaments 34, 36 and therefore serves to shield the filaments 34, 36 from one another.

(14) As also shown in detail in the enlarged sectional view of FIG. 3, the first, low beam filament 34 is connected at one end to a first holding wire 30a and at the other end to the baffle 40, which is fixed to the third holding wire 30c. The second, high-beam filament 36 is fixed to a second holding wire 30b and to the third holding wire 30c. By these connections, the filaments 34, 36 are both mechanically held at defined positions within the vessel 22 and are electrically connected to the holding wires 30a, 30b, 30c. The holding wires, in turn, are connected internally within the base 12 to electrical contacts 20 protruding from the lower portion of the base 12. Thus, the filaments 34, 36 are operated by supplying electrical power to the electrical contacts 20.

(15) FIG. 3 shows an enlarged sectional view of the central, circular-cylindrical portion 24 of the vessel 22, and FIG. 4 shows the baffle 40 without the filaments 34, 36. As shown in FIG. 3, the filaments 34, 36 are each provided as a single winding structure of filament wire wound around a straight filament axis.

(16) In FIG. 3, the filament axis 35 of the first filament 34 and the filament axis 37 of the second filament 36 are arranged in parallel to the longitudinal axis X of the lamp 10.

(17) The first filament 34 has an axial length L.sub.1 of 4.2 mm. The axial length L.sub.2 of the second filament 36 is 4.0 mm.

(18) The baffle 40 comprises a bottom surface 41 from which a front surface 43, a back surface 47, and side surfaces 45 extend. The side surfaces 45 terminate in side edges 48. At the back surface 47, an attachment tab 52 is integrally formed.

(19) The attachment tab 52 serves to connect the filament wire of the first filament 34 to the baffle 40. It is arranged substantially flat in a plane that is oriented horizontally in FIG. 3 at an attachment height H.sub.T of 2.6 mm above the bottom surface 41.

(20) The front surface 43 extends at a central tip 42 up to a front height H.sub.F of 4.1 mm.

(21) As shown in FIG. 4, the side edges 48 comprise a portion 54, which in a side view of FIG. 2 or in a sectional view of FIG. 3 extend straight and in parallel to the longitudinal axis X of the vessel 22. As the skilled person will appreciate, the portions 54 here referred to as extending straight in the view of FIG. 3 will not be straight as viewed from above. Thus, the optical functions and measurements of the straight portions 54 of the side edges 48 in the present description refer to the side view, as e. g. shown in FIGS. 2 and 3.

(22) The central, straight portions 54 extend (in side view) straight and in parallel to the longitudinal axis X, i.e. without a variation in height above the bottom surface 41 over a considerably long distance L.sub.E. The distance L.sub.E in the preferred embodiment is 7.2 mm. The straight portions 54 start at the front end 42 of the baffle 40 after a distance a of 2 mm and extend up to the back wall 47.

(23) Compared with prior vessel designs, the distance parameter a is relatively small, i.e. the straight portions 54 start at a very small distance along the lamp axis X from the front end 42 of the baffle 40.

(24) In the presently shown preferred embodiment, the side edges 52 within the central, straight portions 54 extendin side viewexactly straight and in parallel to the lamp axis X. For purposes of defining a suitable tolerance, the side edges may, in side view, show a certain, limited inclination relative to the lamp axis X. Such an inclination may be defined between the start of the straight portion 54 proximate to the first end 42 of the baffle 40 at the coordinate a (in the example shown as 2 mm) along the lamp axis X as a first measuring point, and a second measuring point defined at a fixed distance b of 5 mm along the lamp axis X. While in the example shown the straight portions 54 show no inclination between the two measuring points, there may be conceivable embodiments, or simply manufacturing tolerances, where a slight inclination of the side edges 48 between the above defined measuring points at coordinates a, b is equal to or below a defined tolerance of 0.2 mm, preferably 0.1 mm.

(25) The straight portions 54 of the side edges 48 are arranged at an edge height H.sub.E of 3.3 mm above the bottom surface 41. The tub-shaped baffle 44 thus has a considerably increased height as compared to some prior designs. As shown in FIG. 3, in the preferred embodiment shown the attachment tab height H.sub.T is less than the edge height H.sub.E.

(26) The second filament 36 is arranged with its filament axis 37 below the straight portions 54 of the edges 48. A distance D.sub.2 between the filament axis 37 of the second filament 36 and a plane defined by the straight portions 54 of the edges 48 is 0.3 mm.

(27) The first filament 34 is arranged partially above and partially below the edge height H.sub.E. An upper edge 53 of the first filament 34 is 0.5 mm above the plane of the straight portions 54 of the edges 48.

(28) As shown in FIGS. 3 and 4, the axial length L.sub.1 of the first filament 34 almost completely overlaps with the axial length L.sub.E of the straight portions 54 of the side edges 48. Thus, a substantial portion of light emitted from the first filament 34 is shielded at the straight portions 54 rather than at inclined portions of the edges 48, leading to a corresponding straight bright/dark cutoff.

(29) In operation of the lamp 10, if a voltage is applied to either the first filament 34 or the second filament 36, i.e. between the first holding wire 30a and the third holding wire 30c, and between the second holding wire 30b and the third holding wire 30c, the filaments 34, 36 operate to emit light. Light emitted from the second filament 36 extends freely in all radial directions, whereas light emitted from the first filament 34 is partially shaded by the baffle 40 as described, in particular at the side edges 48.

(30) FIG. 5 shows schematically a headlight 50 where the lamp 10 as described above is schematically shown arranged within a reflector 46. Light emitted from the filaments 34, 36 (not shown in FIG. 3) is reflected by the reflector 46 to form different illumination beams. Light from the second (high-beam) filament 36 is shown as a dotted line to be reflected by both the upper and lower part of the reflector 46 to form a high-beam without a bright/dark cutoff.

(31) Light emitted from the first low-beam filament 34 is shown as a dashed line to be partially shielded by the baffle 40 such that only an upper portion of the reflector 46 is illuminated. The upper portion of reflector 46 is shaped to reflect the light from the first filament 34 to form an illumination beam with a horizontal bright/dark cutoff.

(32) Arrangement of the filaments 34, 36 and of the baffle 40 is exactly symmetrical with regard to the symmetry plane defined by the axes R, X. Thus, the resulting beam patterns are symmetrical, too. In particular, the low-beam pattern will have a horizontal bright/dark cutoff.

(33) While 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 embodiment.

(34) Variations from the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure and the appended claims. In the claims the word comprising does not exclude other elements, and the indefinite articles a or an do not exclude a plurality.

(35) The mere fact that certain measures are recited in mutually different dependent claims 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.