Electric lamp and discharge devices – With support and/or spacing structure for electrode and/or... – For filament
Reexamination Certificate
1999-04-23
2001-08-07
Patel, Ashok (Department: 2879)
Electric lamp and discharge devices
With support and/or spacing structure for electrode and/or...
For filament
C313S578000, C313S112000, C362S310000
Reexamination Certificate
active
06271622
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to lamp capsules for vehicle headlamps and, more particularly, to lamp capsules which have improved filament and filament support configurations.
BACKGROUND OF THE INVENTION
Vehicle headlamps commonly include a lamp capsule mounted in a reflector so that the light source is located at or near the focal point of the reflector. Light emitted by the lamp capsule is directed in a forward direction by the reflector. The lamp capsule typically includes a high beam filament from which light is directed horizontally in a high beam pattern and a low beam filament from which light is directed below horizontal in a low beam pattern. One of the problems involved in the design and construction of vehicle headlamps is to minimize uncontrolled light emission outside the desired beam patterns, particularly the low beam pattern, that may impair the ability of oncoming drivers to see the road and other vehicles. This uncontrolled light is known as glare.
The typical low beam pattern requires that little or no light be projected above the horizontal plane and requires the maximum hot spot to be projected just below the horizontal plane. Factors such as filament size and internal and external uncontrolled reflections cause the source pattern to be spread, making a sharp transition line at the horizontal plane difficult to achieve. One approach is to aim the low beam pattern slightly lower than horizontal. This reduces glare for oncoming drivers but at the expense of reducing desired illumination far down the road. Another approach is to block undesired light. However, any blockage reduces the total illumination produced by the lamp and thereby reduces the effectiveness of the lamp. There is therefore a need to improve the low beam pattern and in particular to sharpen the transition line at the horizontal plane, while minimizing the adverse impact on the total illumination.
In a two-filament lamp capsule, light from the low beam filament falls on the high beam filament at close range, causing it to appear as if the high beam filament were illuminated at low level in the direction of the low beam filament. Regions not facing the low beam filament remain dark. Light reflected from the high beam filament is then projected onto the reflector and into the field of view. The light reflected from the high beam filament is projected by the reflector as if the high beam filament were partially illuminated and produces a ghost image of the high beam filament. Thus, light is projected above the horizontal plane into the region that should not receive light when the low beam filament is illuminated. It is desirable to reduce or eliminate this ghost image of the high beam filament during low beam operation without substantially affecting lamp intensity during high beam operation.
Vehicle headlamps include a filament support structure which supports the high beam and low beam filaments in desired positions in the lamp capsule and which conducts electrical energy to the filaments. The filament support structure typically includes conductive support leads having sufficient rigidity to support the filaments under all expected environmental conditions. The filament support structure should be configured to limit blockage of light emitted by the filaments and to limit stray reflections that would adversely affect the beam pattern. Furthermore, the positions of the filaments in the lamp envelope and relative to each other have a significant impact on the beam pattern and on the overall performance and flexibility of the lamp capsule.
SUMMARY OF THE INVENTION
According to a first aspect of the invention, a lamp capsule is provided. The lamp capsule comprises a lamp envelope including a tubular portion, a dome closing one end of the tubular portion and a press seal closing the other end of the tubular portion. The lamp envelope has a central axis. First and second filaments are mounted in the lamp envelope for emitting light when energized by electrical energy. The first filament is spaced from the central axis. The second filament is mounted in spaced relation to the first filament. The first and second filaments are in a plane that passes through the central axis. The lamp capsule further comprises a support structure for supporting the first and second filaments and for supplying electrical energy through the lamp envelope to the first and second filaments.
The support structure preferably comprises first, second and third support leads having portions within the lamp envelope that are in the plane of the first and second filaments. Preferably, the plane of the first and second filaments and the support structure is parallel to the long dimension of the press seal. The support structure is configured to limit blockage of light emitted by the filaments and to limit stray reflections which would produce glare.
The first support lead may be connected to an upper filament lead of the first filament and is at least partially shadowed by the first filament when the second filament is illuminated. An upper segment of the first support lead may be angled toward the central axis to reduce stray reflections.
The second support lead may include a lower segment that is parallel to and spaced from the central axis and an upper segment that is bent toward the central axis and is attached to the lower filament leads of the first and second filaments between the filaments and the press seal.
The third support lead may include a lower segment that is parallel to and spaced from the central axis and an upper segment that is bent away from the central axis and is attached to an upper filament lead of the second filament. The upper filament lead of the second filament may be bent parallel to the central axis in the plane of the filaments and may extend toward the press seal for connection to the third support lead.
REFERENCES:
patent: 3646386 (1972-02-01), Rijnders
patent: 3736452 (1973-05-01), Rijnders
patent: 4180755 (1979-12-01), Nixon, Jr.
patent: 4801845 (1989-01-01), Kiesel
patent: 5187405 (1993-02-01), Rachel et al.
patent: 5578893 (1996-11-01), Yamamoto
patent: 5808399 (1998-09-01), Yoneyama
patent: 5856723 (1999-06-01), Rittner
patent: 1 589 412 (1970-03-01), None
patent: 25 47 164 (1976-05-01), None
patent: 0 500 340 A2 (1992-08-01), None
Abstracts of Japan, vol. 097, No. 003, Mar. 1997.
Coushaine Charles M.
English George J.
Tucker Michael D.
Osram Sylvania Inc.
Patel Ashok
Wolf Greenfield & Sacks P.C.
LandOfFree
Vehicle lamps with improved filament and filament support... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Vehicle lamps with improved filament and filament support..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Vehicle lamps with improved filament and filament support... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2508537