Abstract: A symmetrical light intensity distribution profile is achieved by placing a pair of similar asymmetrical linear DC gas discharge lamps in parallel position but opposed in polarity. The individual asymmetrical distributions of the lamps combine in a symmetrical total intensity distribution. A desired "butterfly" or other intensity distribution profile can be achieved.

Abstract: Various sodium vapor lamp configurations are disclosed. In one, a sodium vapor discharge tube contains an excess of sodium which is condensed in predetermined locations, as for example dimples. To prevent condensation in the aperture through which light emission is desired, the discharge tube is heated at the aperture by ohmic heating of a conductive film such as tin oxide or by fine wires. In a second configuration, the discharge tube is coated on the inside with metallic sodium, the coating being internally reflective and defining an aperture, such as a slit, through which light output is directed. The aperture area is coated with a conductive coating such as tin oxide to provide ohmic heating of the aperture area so that metallic sodium condenses on the tube in areas other than the aperture. Thus, an excess of sodium is provided to control the lamp vapor pressure and also to form a light reflective coating to direct emission through the aperture.

Abstract: A technique is disclosed herein for the enhancement of efficiency, and uniformity of light emission from a DC-operated fluorescent lamp. It involves the correlation of mercury vapor pressure within the lamp (which is dependent upon the temperature of liquid mercury within the lamp) with the magnitude and polarity orientation of the DC current applied to the lamp, and an optimization of these parameters along with lamp tube diameter.

Abstract: In a sodium vapor lamp, a means for rapid warm-up and/or maintaining the temperature of the discharge tube in order to quickly achieve and maintain the sodium vapor pressure at a desired level is disclosed. The discharge tube is surrounded with a resistive conductor so as to ohmically heat the tube to a desired temperature, e.g. 270.degree.C. The heating element is a resistive tube coating.

Abstract: A technique for charging a dielectric surface by corona discharge is described in which the voltage applied to a stationary corona wire is steadily increased over an initial time period to cause the gradual increase in voltage level on the dielectric surface over the same time period. The voltage on the stationary dielectric surface increases with the wire voltage. The potential difference between wire and plate is kept below the sparking voltage, but above the corona current threshold voltage.After the initial phase, the dielectric surface is moved relative to the corona wire (e.g. a rotating xerographic drum). The corona wire can now be held at its high voltage without sparking between the wire and the dielectric surface.

Abstract: .[.A symmetrical light intensity distribution profile is achieved by placing a pair of similar asymmetrical linear DC gas discharge lamps in parallel position but opposed in polarity. The individual asymmetrical distributions of the lamps combine in a symmetrical total intensity distribution. A desired "butterfly" or other intensity distribution profile can be achieved..]. .Iadd.The invention relates to an illumination system which provides nonuniform illumination along an object plane in the dimension of an illumination source which includes two linear lamps. The lamps have their anodes and cathodes connected in reverse fashion relative to each other; each lamp provides its own asymmetrical light output distribution pattern but the resultant output of both lamps is a symmetrical pattern which provides the characteristic nonuniform illumination on the object plane. .Iaddend.