GB887209A - Electric control devices - Google Patents

Abstract

887,209. Electrostatic switches. TANN CORPORATION. April 25, 1958 [April 29, 1957; Nov. 15, 1957], No. 13229/58. Class 38 (5). A switch includes a housing with spaced contacts therein, a ball freely movable therein to and from bridging relation with the said contacts, and electrode means for applying a charge to the ball to cause it to move within the housing to engage the contacts. In one form, Fig. 1, a ball 149 is oscillatable in an insulating tube 145 the ends of which have insulating plugs 146 supporting contacts 147 and electrodes 148, the latter being covered by insulation 150. When a high voltage is applied to the electrodes, the ball takes up the charge of the adjacent electrode and is thus repelled thereby to the opposite end of the tube, where the ball acquires the polarity of that electrode and is again repelled, and so on. The speed of the ball may be varied by altering the voltage, by a flux produced by a coil 153, which may be used to hold the ball at the centre of the tube, or by altering the inclination of the tube. Similarly, coils 156, 157 may hold the ball in engagement with the respective contacts. The ball may be of nickel-iron alloy, having a surface of greater conductivity, such as silver or silver cadmium oxide, or may be of insulating material with a conductive coating. A second ball may be used (Fig. 3, not shown) so that two circuits may be separately controlled. The balls may move from end to end together or may oscillate between the end portions and a central position where they lose their charges and are attracted back to their respective ends. An inert gas may be included in the tube, and movement of the ball may be assisted by the coil 153, or a number of such coils, the coil causing the ball to float along the tube. In a further embodiment, Fig. 5, the ball 165 may be moved from electrode 166 into bridging engagement with any of three spaced pairs of contacts 163, being guided to the appropriate pair by coils 173, 174, 175, and/or by coils 176, 177. The ball may take a spiral or helical path, and a number of balls may be moved sequentially, each under the control of a magnetic force of a different strength. The tube may be filled with a dielectric field and the ball may be stopped along the length of the tube by intermediate electrodes (Fig. 6, not shown). In this arrangement the oscillations of the ball may induce a current in a coil surrounding the tube. The ball may strike a spring or plunger of a switch in the end positions, to control the energization of the coils.