Patent Application
20080074024
For a better understanding of the present invention, together with other and further objects, advantages and capabilities thereof, reference is made to the following disclosure and appended claims taken in conjunction with the above-described drawings.
Referring now to the drawings with greater particularity, there is shown in
Lamps of this description are generally available under the designations PAR 16 or PAR 20 depending upon the major diameter of the bulb: however, such lamps have relatively poor efficiency and center beam intensity, especially with the spot beam angle. PAR 16 lamps are typically available only in flood beam angle.
To remedy this problem and provide a compact PAR lamp with an acceptable spot beam the lamp shown in
A first parabolic reflector 26 is formed within the hollow body 12 and has a wide portion 28 adjacent the open end 16 and a narrow portion 30 spaced therefrom along the longitudinal axis 14. A second reflector 32 is formed within the body 12 and extends from the narrow portion 30 into the neck end 18. A lens 34 closes the open end 16 and a base 36 is attached to and closes the neck end 18.
In a preferred embodiment of the invention the second reflector 32 is ellipsoidal; however, the second reflector also could be spherical. When the second reflector 32 is ellipsoidal the focus points of the ellipse will coincide with the first and second ends 40, 42 of the filament 38. If the second reflector 32 is spherical, the center point thereof will coincide with or be near the parabolic focal point.
The advantages of the invention will be seen from a comparison of
Optical ray trace modeling was used to estimate the effect of adding an elliptical second reflector to a PAR 20 reflector. The modeling predicted a 6% percent lumen increase and a 13% increase in center beam intensity. Additionally, a significant increase in radiated power returned to the coil was predicted and such an increase would further improve lamp efficiency.
In practice the new design incorporated into PAR 20 lamps with operating parameters of 50 W/120V, has been found to provide a 3.4% lumen increase and a 12% increase in center beam intensity, a good agreement with the ray trace mode.
When the new design is incorporated into the smaller PAR 16 lamp, the benefits are even greater, resulting in a measured 12% higher lumen output and 35% greater center beam intensity than prior art lamps with but a single parabolic reflecting surface.
Also, these benefits are achievable with PAR lamps employing arc tubes as the light source.
Such an example is shown in
In the lamps shown herein the capsule 20 is supported by a lead-in (for example, 24) that is welded or otherwise affixed to an inner tab 50 of a metal clip 52. The outer tabs 54 of the clip 52 contact the screw portion 56 of the base 36. One end of a small diameter fuse wire 58 is welded to the other lead-in (22, in this instance) and the other end of the fuse wire 58 is soldered or otherwise affixed to the center eyelet 60.
While there have been shown and described what are at present considered to be the preferred embodiments of the invention, it will be apparent to those skilled in the art that various changes and modifications can be made herein without departing from the scope of the invention as defined by the appended claims.
