Flat signaling lamp with dielectrically impeded discharge

Details Flat signaling lamp with dielectrically impeded discharge Flat signaling lamp with dielectrically impeded discharge

1999-08-16

2002-02-19

Patel, Ashok (Department: 2879)

Electric lamp and discharge devices

With luminescent solid or liquid material

With gaseous discharge medium

C313S573000, C313S634000, C040S557000, C040S545000

Reexamination Certificate

active

06348760

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to the field of signal lamps of the kind used above all for traffic signals and traffic signs. In particular, it pertains to a traffic light.
The field of lamp technology includes not only manifold lighting tasks but also the field of signal lamps. The term signal lamp should be understood primarily as a lamp that makes the observer aware (informs him) about an event or situation. This information is imparted to the observer as a rule already by whether the lamp is on or off. Furthermore, the lamp can provide the observer with additional information content, for instance by way of its shape, color or captioning.
In daily life, there are many familiar applications of signal lamps, such as in road traffic and in travel by ship and railroad; for monitoring and operating technical devices of every kind; for safety-related signage in buildings or in such traffic-related, commercial or industrial systems as airports, railroad stations, motion picture theaters, and so on.
The field of signal lamps is characterized by some special requirements. These include reliability, service life, and the expense for repair and maintenance. This is due not only to safety considerations but also to the large numbers of signal lamps in use and their wide geographic distribution, with the attendant expense for maintenance and repair.
Another important aspect is that for signal lamps, certain structural forms or sizes are desired, depending on the intended application.
STATE OF THE ART
Conventionally, standard incandescent bulbs or halogen lamps are used, especially for signal lamps that have to be turned on and off in operation.
The resultant disadvantages are, first, the high vulnerability to vibration of the incandescent filament. Particularly for applications in the traffic field, this entails major restrictions. Furthermore, depending on the type of lamp and the operating voltage used, incandescent bulbs have only a relatively limited service life of a few thousand hours and must then be replaced, at sometimes considerable effort and expense, as already noted above. In the final analysis, the service life is typically short, which is just as much a disadvantage as any other vulnerability to defects.
Another aspect often arises from the special demands made of the projection characteristics of the projected radiation. In that case, the incandescent bulbs must be installed in an optical system, for instance with a mirror reflector and/or with lenses. First, this can lead to maladjustments and attendant radiant power limitations. Furthermore, such optical systems are complicated in structure and in principle are vulnerable to soiling; yet soiling, especially in the traffic field, is fundamentally unavoidable. As a result, complicated internal cleaning during regular maintenance work is necessary, but even then it is impossible to entirely restore the initial properties of the system.
In mirror reflectors, so-called phantom lights can also occur, e.g., when the sun is low in the sky, in traffic lights. Reflected sunlight makes it look as though the signal lamp is lighted when it is not.
A further disadvantage of the optical systems with reflectors or lenses that are often needed in applications using incandescent bulbs are the required structural size and shape and the attendant weight. In many cases these are highly undesirable, above all if the bulb or lamp has to be mounted in special positions, thus requiring considerable effort for installation and/or for the appropriate mounts, masts or other kinds of securing devices. Yet there is no other choice, giving the necessity of illuminating a large signalling area or of a particular projection direction specified by particular standards, for instance.
A final aspect is the development of temperature in incandescent bulbs, which is not only very great overall but also is highly localized. The resultant thermal cycles and thermal gradients put a burden on the bulb or lamp and its technological surroundings, especially in non-stationary operating states. The outcome is a relatively restricted resistance to reliability in switching.
One known possible way of overcoming some of the disadvantages discussed is to use light-emitting diodes (LEDs); however, they are often unsuitable because of their characteristics of the emitted radiation. Another disadvantage is that the color locus, which is important in many signal lamp applications and also is often standardized, is either not adjustable or, if fluorescent materials are used, cannot be adjusted permanently because of stability problems.
DESCRIPTION OF THE INVENTION
The technical problem on which the invention is based is to disclose a novel signal lamp which offers opportunities for overcoming the aforementioned difficulties.
According to the invention, this problem is solved by a gas discharge lamp having a discharge vessel which is at least partly transparent to visible radiation and is filled with a gas fill, and having a dielectric layer between at least one discharge electrode and the gas fill for a dielectrically impaired or hindered discharge in the discharge vessel, characterized in that the lamp is a signal lamp with a signal surface, and the discharge vessel has a continuous boundary surface that corresponds to the signal surface.
The invention is based on the recognition that many conventional prejudices against the use of gas discharge lamps in the field of signal lamp technology can either be overcome technologically, or else the attendant disadvantages are tolerable because of other attendant advantages. One factor arguing against the use of gas discharge lamps instead of incandescent bulbs or halogen lamps is the necessity of using expensive starting circuits or electronic ballasts. On the other hand, precisely in the field of electronic ballasts, substantial progress has been made in lowering the cost and reducing the structural size, and in the field of conventional halogen lamps as well, by use of transformers in low-voltage technology similar disadvantages are accepted.
Another aspect is the reduced resistance to repeated switching of gas discharge lamps because of the starting process. It has been found here that with gas discharge lamps with dielectrically hindered discharge, resistances to repeated switching can be attained that far exceed those of conventional incandescent bulbs and that are determined essentially only by the stability of the fluorescent materials, or mixtures thereof, that are employed. Because of the relatively insensitive electrode form compared with incandescent filaments and because there are fewer thermal cycles in operation, the resistance to repeated switching can now be assessed as an advantage of gas discharge lamps with dielectrically impaired discharge, compared with conventional incandescent bulbs. Here again, a prejudice prevailing in conventional gas discharge lamp technology has proved in this special case to be unfounded.
Another aspect that initially argues against the use of discharge lamps is associated with the widespread use of mercury in the corresponding gas fills. Mercury not only has disadvantageous environmental aspects but also leads to disadvantageous temperature properties of the bulb or lamp. Primarily, this means its instant-start properties, that is, the (lack of an) ability to emit the full light output immediately after being turned on. Furthermore, this problem also depends on outside temperatures and is accordingly especially pronounced in cold surroundings. It has now been demonstrated, however, that if a lamp with dielectrically impaired discharge is used, gas fills containing mercury are no longer necessary, and so these problems vanish completely.
One substantial advantage of this invention resides in the geometry, particularly of flat radiating discharge lamps, which is very flexibly adaptable in shape and size to individual requirements. Discharge lamps are distinguished by a largely homogeneous distribution of light generation over the discharge volume, so that often a

Affiliated with

Also associated with

Rating

Flat signaling lamp with dielectrically impeded discharge does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Flat signaling lamp with dielectrically impeded discharge, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Flat signaling lamp with dielectrically impeded discharge will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2942572