Abstract: Method and apparatus for electrostatically applying phosphor coatings to the interior surface of fluorescent lamp tubes includes equipment for applying an electrical charge of one polarity to the glass wall and electrical charge of the opposite polarity to the phosphor particles to cause the phosphor particles to adhere to the glass surface until the particles can be heated to bond them to the interior surface of the glass by lehring. By using electrostatic deposition the lehring may be done at a lower temperature than is required with conventional phosphor deposition using organic binders so that U-shaped fluorescent lamps do not experience distortion from the lehring temperature. The invention includes the fluorescent lamps provided which are devoid of residue of organic binder.

Abstract: A control circuit for supplying power to a piezoceramic coupler includes a controllable oscillator for supplying an output signal having the resonance frequency of the piezoceramic coupler and an amplitude control circuit to control the amplitude of the output signal of the piezoceramic coupler. Switching devices are also included to control interruption of the application of the drive signal to the piezoceramic coupler.

Abstract: A current-balancing transformer is provided to supply plural parallel-connected electrical loads, especially loads such as gas discharge lamps which exhibit negative impedance and/or non-linear impedance over at least a part of their normal operating range. The current-balancing transformer forces current sharing among the loads so that each of the parallel-connected loads is supplied operating current.

Abstract: In a high intensity metal halide discharge lamp, means are provided associated with the interior surface of the envelope to promote the formation and spreading of a liquid film of condensate thereon. Such a film can lower the color temperature as a result of pressure broadening and self-reversal of the sodium line, and also by acting as a color correcting filter. The film-promoting means may be a coating which imparts an irregularity to the surface such that the reduction in exposed surface area by coverage with a uniform liquid film is energetically favored. Alternatively, a chemically different surface better wetted by the metal halide dose may be used.

Abstract: Two or more fluorescent lamps having a total length of about 96 inches and each having a diameter of one and a half inches and consuming less than 10 watts power per foot of length are connected in electrical series combination, one cathode of each lamp being connected to that of another lamp. An end of each remaining cathode of the combination is respectively connected to one of a pair of input electrical power terminals for a 50 or 60 hertz a-c line voltage in the range of 200 to 300 volts, one of the latter connections being via a ballast inductor. A starter switch is connected across the other ends of the remaining cathodes, and a secondary winding on the ballast inductor is connected across the interconnected cathodes. The lamp designs are specified such that they will start and operate in the circuit from the a-c line voltage.

Abstract: A discharge lamp comprising an elongated bulb shaped so that the ends thereof are substantially closer together than if the bulb were straight and containing electrodes respectively near said ends thereof, and a starting air comprising conductive members respectively adjacent to said bulb behind the plane of each of said electrodes, and means electrically interconnecting said conductive members.

Abstract: Electrical lamp ballast system for starting and operating fluorescent lamps with improved efficiency. System includes high leakage reactance autotransformer having primary and secondary windings, and a ballast capacitor connected in series with the secondary winding and two serially connected fluorescent lamps of low starting and operating voltage, the secondary circuit being connected to a tap on the primary winding for reducing the ratio of the ballast power input to the lamp light output. The system provides for reduced lamp current crest factor, thereby improving life and operating characteristics of the lamps.