It is well known in the art to utilize PAR (parabolic aluminized reflector), ER (elliptical reflector) or R (reflector) lamps for general spot, downlighting or flood lighting applications. In particular, R, PAR, and ER lamps have been exceptionally popular for short to medium distance outdoor uses as well as indoor for display, decoration, accent, inspection in down lighting applications. Such lamps are manufactured by the assignee of the instant invention. Typically PAR lamps are of hardglass and include a medium skirt or the screw-type base at the rear thereof for connecting the lamp to the desired power source.
Lamps of the PAR variety typically include a lens that may be partially or substantially totally covered with a small semispherical protrusions which in turn may be used in combination with a stippled surface area (e.g., created by shot or sand blasting) or the stippling may be used alone. The beam produced by a PAR lamp is typically of substantially conical configuration and provides a substantially round pattern. This pattern changes to being oval or elliptical should the lamp be aimed at an acute angle with the light receiving surface.
One of the problems faced by manufacturers of reflector-type lamps has been to increase the candle power by proposing several reflector and lens designs to utilize stray light that is emitted from the particular light source utilized. "Light source" may be defined as a filament or a tungsten halogen capsule or a high intensity discharge tube. With respect to the use of an incandescent filament or lamp as the light source, there is a significant increase in stray light as the length of the coiled filament increases and less light passes through the central angular region of the reflector. The problem becomes more enhanced where higher wattages are desired, due to the fact that the overall filament length increases with wattage and mounting arrangements for such filaments become more complex making it much more difficult to control the light that passes through the central angular region. This in turn requires the design of more complex reflector and lens configurations in order to effectively reflect stray light into the main beam of the reflector-type lamp thereby trying to increase the candle power of a lamp for a particular wattage and voltage.
It is believed, therefore, that there is a need for a reflector-type lamp design that reduces focus loss and improves collection efficiency in order to increase candlepower in a lamp for a particular wattage, voltage and efficacy. The increase in collection efficiency can lead to simpler reflector and lens designs which would constitute a significant advancement in the art.