APPARATUS FOR ELECTROSTATICALLY APPLYING POWDER COATING ONTO BULBS OF ELECTRIC LAMPS Russian patent published in 2002 - IPC

FIELD: processes for electrostatically applying coatings onto inner surface of bulbs of electric lamps. SUBSTANCE: applied coating is designed for creating light-diffusion effect or for converting ultraviolet irradiation to irradiation of visual light in gas-discharge tubes. Apparatus for electrostatically applying coatings includes bulb holder, pipe for supplying powder mixture, ionization electrode with spraying nozzle, gas burner-electrode for heating bulbs. Arrangement of end of pipe for supplying powder mixture and of ionization electrode relative to spraying nozzle and bulb of electric lamp and also pressure of blown-in mixture and size of spraying nozzle are mutually related by next relations: 0,25≤L/L₁P≤0,5; 3,5≤Dh/d≤8,5; where L- spacing from ionization electrode until mostly distant inner surface of bulb, mm; L₁ - spacing from ionization electrode until nearest inner surface of bulb, mm; P - pressure of supplied powder mixture, MPa; D - diameter of pipe for supplying powder mixture, mm; d - diameter of spraying nozzle, mm; h - spacing from spraying nozzle until ionization electrode, mm. Such apparatus allows to apply powder coating of uniform thickness without agglomeration of pulverized matter at deposition onto surface of bulb as all particles of flow of air-powder mixture are passed along inner zone of ionization electrode to its outer zone. It provides unipolar charging of powder particles and eliminates clogging of surface of electrode with powder and enhances efficiency of charging powder particles. EFFECT: enhanced quality of applied coating due to uniform thickness of it for different-size bulbs, reduced consumption of powdered mixture. 2 dwg