摘要:
A metal halide arc discharge lamp having a gaseous fill within the outer envelope and means for suppressing convection currents within such fill; and methods of operating and constructing such lamps. A light-transmissive sleeve or enclosure surrounding the arc tube laterally and about at least one end thereof is so shaped and mounted with respect to the arc tube as to insure that the Rayleigh Number, a quantitative measure of convective flow, in the atmosphere laterally surrounding the arc tube will be less than 5.times.10.sup.4 during operation of the lamp whereby excessive convective heat loss in such lamp will be effectively suppressed.
摘要:
A metal halide arc discharge lamp having a gaseous fill within the outer envelope and means for suppressing convection currents within such fill; and methods of operating and constructing such lamps. A light-transmissive sleeve or enclosure surrounding the arc tube laterally and about at least one end thereof is so shaped and mounted with respect to the arc tube as to insure that the Rayleigh Number, a quantitative measure of convection flow, in the atmosphere laterally surrounding the arc tube will be less than 5.times.10.sup.4 during operation of the lamp whereby excessive convective heat loss in such lamp will be effectively suppressed.
摘要:
A projection lamp comprises a single-ended metal halide arc discharge lamp disposed within a curved reflector and an interference filter disposed in front of the reflector, the filter being highly transmissive of visible light and reflective of radiation for which the metal halide, in molten salt form, is highly absorptive.
摘要:
The efficiency of a horizontally operated arc discharge lamp has been found to be substantially improved by the application of a transverse magnetic field. The magnetic field moves the arc downward, away from the upper wall of the lamp envelope. The magnetic field moves the arc so that the outer mantel that otherwise would make contact with side walls of the envelope stand away from the envelope wall. With the arc withdrawn from the wall, less energy is lost in heating the envelope, resulting in more energy be directed to the emission of light.
摘要:
This invention provides an improved method of fabricating an arc tube, particularly a miniaturized arc tube having precise geometry and requiring exact electrode alignment. The improved method divides the press sealing operation into two distinct steps. In the first or preforming step, the ends of the arc tube are heated and preformed such that the ends have a substantially elliptical cross section; in the second or pressing step, the preformed ends are heated and pressed together to form completed press seals. During each step, the viscosity of the pliable glass remains low so that internal shearing forces are substantially reduced from those experienced in the prior art methods. As a result of the low viscosity during the pressing step, electrode misalignment, tearing of molybdenum foils, and deformation of the midsection of the arc tube are virtually eliminated. An electrode and a starting probe may be inserted with ease into a preformed end because of its flattened cross section. In the absence of the preforming step, a tubular blank having a larger internal diameter might be required thereby necessitating a more bulky arc tube and greater glass consumption.
摘要:
A circuit for starting and operating a high intensity discharge (HID)lamp in a dc mode includes a pulse width modulator (PWM) coupled to first and second direct current input terminals. The PWM includes a high frequency generator driving a pair of semiconductor switches. A first transformer having primary and secondary windings is coupled to the semiconductor switches. A rectifier and voltage multiplier circuit converts the voltage across the secondary winding of the first transformer to a direct current voltage. A first energy storage circuit coupled to the rectifier and voltage multiplier circuit stores energy for generating a high voltage spike which initiates a glow condition in the lamp. A secondary energy storage circuit, which stores energy for application to the HID lamp during starting, insures proper glow-to-arc transition. The starting and operating circuit further includes a second transformer having first and second secondary windings coupled to the HID lamp and a pulse winding coupled to the first energy storage circuit. Preferably, the windings of the second transformer are adapted to apply a negative-going pulse across the lamp. The application of a negative-going pulse prevents failure of the quartz region of the glass around the lamp cathode by insuring that electrons properly migrate from the cathode to the anode. Moreover, the use of the negative-going pulse improves hot restriking.
摘要:
A ballast for starting and operating a high intensity discharge (HID) lamp in a dc mode includes an oscillator coupled to first and second direct current input terminals. The oscillator includes a high frequency generator driving a pair of semiconductor switches. A first transformer having primary and secondary windings is coupled to the semiconductor switches. A rectifier and voltage multiplier circuit converts the voltage across the secondary winding of the first transformer to a dc voltage. A first energy storage circuit coupled to the rectifier and voltage multiplier circuit stores energy for generating a negative-going, high-voltage spike sufficient for initiating a glow condition in the lamp. A second energy storage circuit, which stores energy for application to the HID lamp during starting, insures proper glow-to-arc transition. The starting and operating circuit further includes a control circuit for regulating lamp power in response to control signals received from voltage and current monitoring circuits. A portion of the ballast is adapted to permit the lamp to reach full light output in a relatively short period of time by briefly operating the lamp at an elevated power level during starting.
摘要:
An arc extinguishing means for a high intensity discharge lamp comprises a meltable fuse wire a portion of which is surrounded by a refractory hollow sleeve of larger diameter than the fuse wire. The remaining volume of the sleeve is substantially filled with a pyrophoric material which, at an operating temperature available within the lamp, will spontaneously ignite in the presence of oxygen and generate sufficient heat to melt the fuse wire and thus open the circuit, extinguishing the lamp.