US2009205A - Auxiliary electrode - Google Patents

Description

July 23, 1935. RANDALL r AL 2,009,205

AUXILIARY ELECTRODE Filed March 14, 1935 ATTORN EY Patented July 23, 1935 UNITED STATES PATENT OFFICE AUXILIARY ELECTRODE poration of New York Application March 14, 1935 Serial No. 11,152 In Great Britain March 14, 1934 5 Claims'.' '(Cl. 176126) This invention relates to auxiliary electrodes for facilitating the starting of an electric discharge between the main electrodes of an electric discharge device, and more particularly the in- 5 vention relates to auxiliary electrodes of the type placed in the neighbourhood of a main electrode and connected electrically either to the other main electrode or to an auxiliary electrode in the neighborhood of that other main elec- 10 trade.

Auxiliary electrodes of the type having a multiplicity of discharge supporting points directed towards the associated main electrode are long lived as the life thereof is not limited by the 15 wearing away of a single point. The object of this invention is to provide a simple and efficient electrode of this kind. Another object of the invention is to provide a method of manufacture of the electrodes of this type. Still further objects and advantages attaching to the device and to its use and operation will be apparent to those skilled in the art from the following particular description.

According to the invention an auxiliary elec- 25 trode for facilitating the starting of an electric discharge is made by winding a metal wire or filament in the form of a helix about a plurality of substantially parallel support wires, which wires are supported by a mandrel having grooves 30 therein to accommodate said support wires, fixing the turns of the helix to a support wire where they are in contact with it, preferably by welding, and then cutting the helix substantially in a plane parallel to the said support wires.

3.": Preferably the plane is equidistant from the support wires and perpendicular to the plane containing them. The result is then a pair of combs, each of which has two rows of teeth consisting of the portions of the helix fixed to one support 40 wire, the two rows being inclined to each other at an angle that is preferably acute.

The support wire is of nickel, when desired;

the helix, parts of which constitute the teeth of the double comb, is preferably of a more refrac- 45 tory metal, such as molybdenum or tungsten; the diameter of the wire of the helix is, preferably, about 0.07 mm. When desired, the support wire is also of molybdenum or tungsten. The teeth should be closely spaced, for instance 30 per 50 cm. The two rows of teeth are freed from gas, for example by treatment in a vacuum furnace, before being mounted in the discharge device; this is usually necessary in order to secure regular operation of the discharge device.

55 The auxiliary electrode thus formed has teeth a few millimeters long and is placed a few millimeters from the main electrode with its teeth turned towards that electrode. Preferably it is placed so that the plane bisecting the angle between the two rows of teeth passes through the main electrode. If the main electrode is a rod, the said plane is preferably parallel to the length of the rod.

In the drawing accompanying and forming part of this specification an embodiment of the invention is shown in which Fig. 1 is a front elevational, partly sectional view of a gaseous electric discharge lamp device having an auxiliary electrode embodying the invention,

Fig. 2 is a sectional view along the line 22 of Fig. 1,

Fig. 3 is a side elevational view of one step in the manufacture of an electrode embodying the invention, and

Fig. 4 is a sectional view along the line 4-4 of Fig. 3.

Like numbers denote like parts in all the fig- UIGS.

Referring to Figs. 1 and 2 of the drawing the gaseous electric discharge lamp device comprises an elongated, tubular, glass container l having a main discharge supporting electrode 2, 3 sealed into each end thereof. Said electrodes 2, 3 each comprise a rod or bar 2 of electron emitting material, such as an alkaline earth compound, and a metal heater filament 3, such as a tungsten filament. The longitudinal axis of each of said rods 2 is parallel with the longitudinal axis of said container l. The ends of said filament 3 are sealed into the press part of the stems of said container 1 and are connected to the current leads 4 and 5. An auxiliary electrode '1, 8 made in accordance with the present invention is also sealed into said container I. Said electrode 1, 8 con- 40 sists of a support wire I, such as a nickel wire, and a multiplicity of pointed wires 8 welded to said support wire I. Said wires 8 are arranged in two rows extending in parallel directions, said rows being at an acute angle, such as an angle of approximately 30 degrees, to each other. The support wire l is parallel to the axis of the rod 2 of said electrode 2, 3, and is sealed into the press part of the stem of the container I. Current lead I0 is connected to said support wire 1 and said lead i0 is also connected through a high resistance to a terminal of the current source for said device other than that terminal to which the main electrode 2, 3, to which said auxiliary electrode I, 8 is adjacent, is connected. Said container 1 has a gaseous atmosphere therein, such as a rare gas, a mixture of gases, a metal vapor, a mixture of metal vapors, or a mixture of gas and metal vapor. During the starting period a multiplicity of auxiliary discharges takes place between the points of said wires 8 and spots on said electrode 1, 8 which rapidly heat these members to cause a proliflc emission of electrons to facilitate the starting of the main discharge between the main electrodes I, 8.

In the manufacture of the auxiliary electrodes 1, 8 two support wires 1, such as nickel wires, are placed in grooves in opposite edges of a mandrel 9 which is a rhomboid in cross-section (Figs. 3 and 4). The sides of the mandrel 9 on either side of the grooves in said mandrel are at an angle of approximately 30 degrees to each other. A metal wire 8, such as a molybdenum wire, is then wound around said mandrel 9, the turnings of said wire 8 being approximately 30 per cm. along said wires 1. The support wires I and the wire 8 are then welded together at the points of contact therebetween. Wire 8 is then cut, as

' by grinding, along the corners of the mandrel 9 having no grooves therein. Two electrodes each having a support wire 1 and two rows of pointed wires 8 are thus manufactured. The two rows of pointed wires 8 are at an acute angle of approximately 30 degrees to each other. It will be understood, of course, that I contemplate that the steps in the above method can be varied when desired, for example, the wire 8 is first wrapped around the mandrel and the support wires 1 are then brought into contact with the wire 8 outside the turnings of said wire 8; the steps of welding and cutting are then performed as above.

The auxiliary electrode is preferably mounted in the discharge device in suchmanner that a plane bisecting the angle between the two rows of wires 8 has the longitudinal axis of the rod 2 therein and the points of wires 8 are approximately 4 mm. from the surface of the rod 2.

What we claim as new and desire to secure by Letters Patent of the United States, is:-

1. An electrode for an electric discharge device, said electrode comprising a support wire having a multiplicity of other wires projecting therefrom substantially at right angles thereto, said last named wires being in two parallel rows along said support wire, said rows being at an acute angle to each other.

2. The method of manufacturing electrodes for electric discharge devices which consists in the steps of mounting a pair of support wires in opposite parallel positions on a mandrel, wrapping another wire around said mandrel, said support wires and said wound wire being in contact at nu merous points along the length thereof, welding said wires together at the points of contact therebetween and cutting said wound wire on said mandrel in a plane perpendicular to the plane of said support wires intermediate said support wires.

3. The method of manufacturing electrodes for electric discharge devices which consists in the steps of winding a wire around a mandrel, bringing a pair of support wires into contact with said wound wire, said supportwires being in opposite parallel positions, welding said support wires and said wound wire together at the points of contact therebetween and cutting said wound wire in a plane perpendicular to the plane of said support wires and intermediate said support wires. 4. The method of manufacturing electrodes for electric discharge devices which consists in the steps coiling a wire, bringing a pair of parallel support Wires into contact with said coiled wire, welding said support wires to said coiled wire and cutting said coiled wire in a plane perpendicular to the plane of said support wires and intermediate said support wires.

5. An electric discharge device comprising a container, electrodes sealed therein, a gaseous atmosphere sealed therein, one of said electrodes being a main discharge supporting, elongated, thermionic electrode, another of said electrodes being an auxiliary electrode mounted adjacent said main electrode, said auxiliary electrode comprising a support wire having a multiplicity of other Wires projecting therefrom substantially at right angles thereto, said last named wires being in two parallel rows along said support wire, said rows being at an acuate angle to each other, said support wire being substantially parallel to said elongated, main electrode, the longitudinal aXis of said main electrode being in a plane bisecting the angle between the parallel rows of wires of said auxiliary electrode.

JOHN 'I'URTON RANDALL. NORMAN LESLIE HARRIS. JOHN WALTER RYDE.

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