GB925542A - Improvements in or relating to cathode glow indicator tubes - Google Patents

Abstract

925,542. Discharge lamps. BURROUGHS CORPORATION. May 22, 1959 [May 22, 1958], No. 17573/59. Class 39 (1). [Also in Group XXXVIII] An indicator tube has an envelope 12, filled with a gas such as neon at about 40-120 mms. pressure, and a plurality of glow cathodes 22, in the form of numbers, letters, &c. arranged in a group or groups of two sets with one of a pair of anodes 36, 40 respectively associated with each set, each of the anodes being interposed between its associated set of cathodes and the other anode whereby each of the anodes shields its associated set of cathodes from the other anode. A shield 38 can be mounted between the anodes 36 and 40 to further shield each of said sets of cathodes from the other anode. All the electrodes and the shield 38 are mounted in stacked relationship. Each cathode in one of the sets, e.g. representing the odd integers, is connected electrically to a respective cathode in the other of the sets, e.g. representing the even integers. The interconnections can be made by connecting each cathode to a pin 16 and connecting the appropriate pins together inside or outside the envelope, or leads from each two cathodes to be connected together can be secured directly to the same pin inside the envelope, or the socket to be used with the tube can be wired to provide the desired cathode pairs. A screen 42 is provided to prevent sublimation of metal from the cathodes on to the plane or curved viewing window 20. The cathodes 22 can be made from stainless steel, aluminium, nickelchromium alloys, or molybdenum by etching, stamping or formed wire and are displaced laterally with respect to each other. Each anode 36, 40 is formed of wire mesh and all the electrodes are provided with apertured tabs for mounting between insulating spacers 34 on elongated pins. The shield 38 can be at a neutral potential relative to the cathodes and anodes. A cup-shaped member 24 as described in Specification 879,033, of imperforate or mesh conductive or non-conductive material rests on a mica disc 30, and surrounds the electrodes. The cup 24 can be at a neutral potential or can be connected to the shield 38. The screen 42 can be connected to the shield 38. A binarytype decade-counter in which the tube is used is shown in Fig. 3, and includes four flip-flop circuits 50, 52, 54, 56, input pulses being fed into the first circuit 50, the output of which is connected both to the counting chain and to the anodes 36 and 40. The output lines of the circuits 52, 54 and 56 are fed into a resistor matrix 58 and the output of the matrix is applied to a particular cathode pair. In the construction shown in Fig. 4, the tube 10<SP>1</SP> comprises one group 60 of two sets of electrodes and a second group 62 which includes cathodes, anodes 36<SP>1</SP> and 401 and a shield 38<SP>1</SP>. The tube 10<SP>1</SP> can be operated so that one cathode in each group glows at the same time to achieve a two-numeral read-out.