Double-filament incandescent lamp for automotive vehicle front lighting

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. When the first filament 34 is operated at a supply voltage of 13.2 V at an electrical power greater than 35 W and less than or equal to 38 W, light with a luminous flux of 500-700 lm is emitted from the lamp 10. If the second filament 36 is operated at a supply voltage of 13.2 V at an electrical power greater than 35 W and less than or equal to 38 W, light with a luminous flux of 800-1,000 lm is emitted from the lamp 10. Both the first and the second filament wire 34, 36 are comprised of a filament wire wound in a winding structure around a filament axis, where the number of winding turns for each of first and second filaments 34, 36 is 16-23.

Claims

1. Lamp for automotive vehicle front lighting, comprising a base for mechanical and electrical connection to an automotive headlight, a burner fixed to said base, said burner comprising a sealed transparent vessel, at least a first and a second filament arranged within said vessel, a baffle arranged proximate to said first filament to shield said second filament from said first filament, where when said first filament is supplied with a supply voltage of 13.2 V it is operated at an electrical power greater than 35 W and less than or equal to 38 W, and light with a luminous flux of 500-700 lm is emitted, and where when said second filament is supplied with a supply voltage of 13.2 V it is operated at an electrical power greater than 35 W and less than or equal to 38 W, and light with a luminous flux of 800-1,000 lm is emitted, wherein each of said first and second filaments are comprised of a filament wire wound around a filament axis, where the number of winding turns for each of said first and second filaments is 16-23, wherein said base comprises a reference protrusion defining a symmetry plane (X, R), the symmetry plane including a longitudinal axis (X) of the lamp and a reference direction (R) extending radially from the longitudinal axis (X) into a direction of a center of the reference protrusion, where said filaments and said baffle are arranged symmetrical to said symmetry plane (X, R).

2. Lamp according to claim 1, wherein the diameter of said filament wire of said first and second filaments is 115-130 m.

3. Lamp according to claim 1, wherein the length of said first and second filaments along said filament axes is 3.6-4.8 mm.

4. Lamp according to claim 1, wherein an outer diameter of said first and second filaments is 0.8-1.2 mm.

5. Lamp according to claim 1, wherein said vessel is filled with a filling gas, said filling gas comprising at least one noble gas selected from the group consisting of xenon, krypton, and argon, said filling gas being provided within said vessel with a cold filling pressure of 0.4-1.2 Mpa.

6. Lamp according to claim 5, wherein said filling comprises an amount of halogen comprising at least chlorides and/or bromides.

7. Lamp according to claim 1, wherein said vessel comprises a circular cylindrical portion surrounding said filaments, where at said circular cylindrical portion said vessel has an outer diameter of 8-16 mm.

8. Lamp according to claim 1, wherein at least three holding wires are arranged within said vessel, and said filaments and said baffle are fixed to said holding wires, where said holding wires extend from a pinch seal of said vessel into the interior of said vessel, and where a holding bar is arranged distant from said pinch seal, said holding bar enclosing said holding wires.

9. Lamp according to one claim 1, wherein said base comprises three electrical contacts, and three holding wires are arranged extending from a pinch seal of said vessel into the interior of said vessel, each of said holding wires being electrically connected to one of said electrical contacts, where said first filament is electrically connected between a first and a third holding wire, and where said second filament is electrically connected between a second and said third holding wire.

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

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the drawings FIG. 1 show a perspective view of a lamp according to an embodiment of the invention.

(2) FIG. 2 shows an enlarged sectional view of a portion of the lamp of FIG. 1 with the section taken along line R;

(3) FIG. 3 shows in a schematic representation a vehicle headlight with a lamp according to FIG. 1.

DETAILED DESCRIPTION OF EMBODIMENTS

(4) FIG. 1 shows an automotive halogen lamp 10 in a perspective view.

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

(6) 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). A reference plane for the mounting position of the lamp 10 in a reflector (FIG. 3) 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.

(7) The lamp 10 may be fixed to a vehicle headlight so as shown in FIG. 3 where the protrusions 18a, 18b provide exact positioning. The protrusion 18b serves as a reference protrusion defining a radial reference direction R. A symmetry plane is positioned to include the lamp axis X and the reference direction R extending radially from the longitudinal axis X into the direction of the center of the reference protrusion 18b.

(8) 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.

(9) 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).

(10) 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.

(11) As shown in detail in the enlarged sectional view of FIG. 2, 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.

(12) FIG. 2 shows a sectional view of the central, circular-cylindrical portion 24 of the vessel 22. As shown, the filaments 34, 36 are each provided as a single winding structure of filament wire wound around a straight filament axis. Both filament axes are parallel to the longitudinal axis X of the lamp 10.

(13) The circular cylindrical portion 24 of the vessel 22 surrounding the filaments 34, 36 has an outer diameter of 12.8 mm.

(14) In the preferred embodiment, the filament wire used for the first filament 34 comprises tungsten, and may in particular be potassium doped tungsten. The wire in the example has a diameter of 122 m, wound in 20 winding turns. The outer diameter of the winding structure of the first filament 34 is 1.0 mm and the length of the winding structure is 4.2 mm.

(15) The second filament 36 has the same winding structure as the first filament 34, i.e. a single winding structure around the straight filament axis. The filament wire out of potassium doped tungsten with a diameter of 119 m is wound in 20 winding turns of an outer diameter of 1.0 mm along a length of 4.0 mm.

(16) The interior of the sealed vessel 22 is filled with a filling gas. In the preferred embodiment, the filling gas is a mixture of xenon and crypton provided at a cold filling pressure of 1 Mpa. Further, a certain quantity of a halogen, chlorides and bromides, is enclosed within the vessel 22.

(17) In operation of the lamp 10, if a nominal voltage of 13.2 V is applied to either the first filament 34 or the second filament 36, i.e. 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 first and the second filament 34, 36 each operate at an electrical power of 36-36.5 W. In operation of the first filament, the lamp emits a luminous flux of 580 lm, and in operation of the second filament 36 emits a luminous flux of 875 lm, due to partial shading at the baffle 40 and the coated portion 26.

(18) FIG. 3 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 reflected by both the upper and lower part of the reflector 46 to form a high-beam without a bright/dark cutoff.

(19) Light emitted from the first low-beam filament 34 is 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 bright/dark cutoff.

(20) 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.

(21) 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.

(22) 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.

(23) 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.