Abstract:
A liquid crystal display (LCD) is provided with a source of backlighting which augments reflected incident light to provide increased contrast. A liquid crystal cell which does not contain dye, but becomes clear when a field is applied, is sandwiched in back of a liquid crystal cell with a dye and electrically connected so that when the front liquid crystal cell is turned ON to make selected portions of it transparent, the back liquid crystal cell is OFF so that corresponding portions of it are highly reflecting. No voltage is allowed to be applied across nonselected portions of the front liquid crystal and a voltage is applied across corresponding nonselected portions of the back liquid crystal making the nonselected portions of the back liquid crystal clear, producing a display of high contrast. Sandwiched to the rear of the back liquid crystal cell is a clear plastic wedge which is edge lighted. The edge lighted wedge only appears bright in the areas where the voltage on the back liquid crystal cell is OFF or not applied thereto.
Abstract:
Fused quartz containing both titanium dioxide and cerium oxide as UV absorbing dopants has been found to be particularly effective for lamp envelopes for high temperature lamps such as halogen-incandescent lamps and metal halide arc discharge lamps which emit both UV and visible light radiation. The codoped quartz transmits visible radiation and absorbs a substantial portion of the emitted UV radiation. The UV absorption is far superior at temperatures above 500.degree. C. and the codoped quartz does not react with the fill within.
Abstract:
Miniature high pressure arc lamps containing a substantial pressure of xenon, in addition to metal halide and mercury, can provide instant light at turn-on and are suitable for automotive headlamps. The high pressure of xenon aggravates convection which causes arc bowing and overheating of the envelope above the arc. By operating the lamp at high frequency within selected bands, acoustic modes are excited in the fill which straighten the arc and make the envelope more isothermal. Frequency modulation of the input can be used to broaden the band selected for acoustic operation and relax the tolerance on arc tube and circuit parameters needed for a match. Acoustic operation may also be used to effect physical displacement of the arc for beam switching.
Abstract:
A light engine comprises a plurality of light emitting diode (LED) devices arranged in a plane and a corresponding plurality of reflector cups wherein each LED device is disposed in a corresponding reflector cup and wherein the light engine does not include either a diffuser or a light mixing cavity. A directional lamp comprises the aforesaid light engine and an imaging lens arranged to generate an image of the light engine at about infinity. The directional lamp may further include a collecting reflector (for example, a conical, parabolic, or compound parabolic reflector) extending between a relatively narrower entrance aperture at which the light engine is disposed and a relatively wider exit aperture at which the imaging lens is disposed. The imaging lens may be arranged to generate a defocused image of the light engine at about infinity to soften the beam edge.
Abstract:
The invention relates to a high temperature material modified to exhibit enhanced IR emittance in the wavelength range where a black body operating at the same high temperature exhibits peak emittance, to a light-transmissive body comprising the high temperature material, to a high intensity lamp comprising the high temperature material, and to a method of preparing the same.
Abstract:
A lamp-to-light guide coupling arrangement includes an electrodeless high intensity discharge lamp comprising an arc tube with an ionizable fill, and an excitation circuit for electrically exciting the ionizable fill to induce therein a light-producing arc discharge. The coupling arrangement further includes a coupling device comprising a generally tubular, hollow body that has an inlet end for receiving light from the arc discharge and a larger, outlet end. The coupling device further comprises an interiorly directed reflector on a surface of the hollow body for reflecting visible light. Such coupling device is shaped so as to receive light at one solid angle over an area of the inlet end and to transmit light at a smaller solid angle but over a larger area of the outlet end. The coupling device is preferably formed from dielectric material. The reflector preferably comprises a refractory optical interference filter.
Abstract:
Fused quartz containing europium oxide, titanium dioxide and cerium oxide has been found to be effective for absorbing UV radiation while transmitting visible light radiation. Uses for this material include lamp envelopes and shrouds for halogen-incandescent lamps and metal halide arc discharge lamps which emit both UV and visible light radiation.
Abstract:
The subject invention, therefore, relates to a multi-layer coating for use on a thick-walled metal halide lamp which emits visible light radiation and absorbs and reflects UV radiation, and which further manages the thermal non-uniformity problems across the thickness of the arc tube to substantially eliminate devitrification problems.
Abstract:
Asymmetric discharge electrode means are provided for a metal halide lamp enabling improved operation at acoustic frequencies. A xenon-metal halide lamp employing such improved discharge electrode means is disclosed together with a reflector lamp unit employing such lamp construction for its light source.
Abstract:
This headlamp comprises a reflector and a discharge lamp comprising an inner envelope having a longitudinal axis coinciding with the optical axis of the reflector. The inner envelope includes a bulbous portion, a front leg extending along the optical axis from the bulbous portion toward the front of the headlamp, and a back leg extending along the optical axis from the bulbous portion toward the reflector. The discharge lamp further comprises a tubular shroud comprising a first hollow portion surrounding the front leg of the inner envelope, a second hollow portion surrounding the back leg of the inner envelope, and a bulbous portion between the two hollow portions. The front leg is provided with a large-diameter integral enlargement (referred to herein as a "large-diameter maria"), and the shroud is joined to the front leg by a maria seal located at the outer periphery of this maria. The shroud is joined to the back leg of the inner envelope by a low-profile seal of substantially smaller diameter than the large-diameter maria seal located much closer to the longitudinal axis of the inner envelope than is the large-diameter maria seal.The bulbous portion of the shroud has (i) a back zone facing the reflector of generally ellipsoidal configuration and (ii) a central axis upwardly offset by a small distance from the longitudinal axis of the inner envelope. This offset has been found to substantially increase the ratio of the seeing light to the glare light in the headlamp beam.