GB610407A - Control for electric circuit employing a cold-cathode gas filled valve - Google Patents

Abstract

610,407. Push-button lifts; indicators. WAYGOOD-OTIS, Ltd. April 3, 1946, No. 10350. Convention date, July 10, 1945. [Class 40 (i)] [Also in Group XL (c)] A control such as is used for operating an electric lift comprises a cold cathode gas-filled valve with a source of current for the anodecathode circuit and a source of alternating current connected between the anode-cathode circuit and earth, the control being manually operated by a person touching the tube envelope or a button connected to it. Fig. 5 shows a source of potential 80 which is sufficient to sustain operation once the coldcathode valve has fired, but is not sufficient to initiate the firing. When a person touches the glass envelope of the valve or press-button connected thereto, alternating potential from source 82 is applied across the gap between the anode 12 and the envelope of the valve and produces sufficient change in the field pattern of the valve to cause it to conduct, the source 80 maintaining the valve conductive when the press-button is no longer being touched. The voltage drop across resistor 81 is utilized for various control operations associated with the working of the lift, and for controlling indicating devices. The control is restored to normal by opening the switch contact 84. In a modification, Fig. 6 (not shown), the direct-current source and the resetting switch between the anode and cathode of the valve are replaced by an alternating current source, the valve ceasing to conduct once the press-button is no longer being touched. Fig. 4 shows a cold-cathode valve 10 mounted behind a transparent or translucent cover 43 which is illuminated when the valve is conducting. The paint on the outside of the valve envelope is removed and an area 52 on the outside near the top is covered with conducting material such as colloidal graphite, contact between this surface and the conducting press-button 47 being made by means of the screw 51 and helical spring 53. A shield 55 of conducting material isolates the valve from the outlet box and other unearthed elements and prevents unwanted firing of the valve.