US2326597A - Gaseous electric discharge device circuit - Google Patents

Description

1943- D/w. ABERNATH'Y 2,326,597

GASEOUS ELECTRIC DISCHARGE DEVICE CIRCUIT Filed April 1, 1942 FIQZ DAVID W. ABEQNATHV ATTORNEY atented Aug. 10, 143

GASEQUS Emc'rarc arsenals nnvrcn crncm'r David W. Abernathy, Chicago, Hit, assignor to Products Development, llna, @hicago, a corporation of minois This invention relates to gaseous discharge devices and more particularly to a highly simplified circuit for initiating a discharge in such devices and maintaining same.

The primary object of this invention is to provide a highly efiicient economical and simple circuit for initiating the discharge in a gaseous discharge tube and maintaining the discharge once it has commenced.

A further object of the invention is to provide a new and improved circuit for devices of the character described which will operate on direct current.

v A still further object of the invention is to provide a circuit of the character described in which no reactive elements will be used for maintaining the dischargeof the gaseous-discharge device.

Still another object of the invention is to provide a simplified circuit for a gaseous discharge device which will include only common and easily obtained electrical parts and elements.

With the foregoing and other objects in view, I

which will appear-more fully as the description proceeds, the invention consists of certain novel features of construction, arrangement and combination of parts and elements hereinafter fully described,symbolically illustrated-in the accompanying drawing and particularly pointed out in the appended claims, it being understood that various changes in the form, proportion, size, minor details and arrangements of the various elements of the-invention may be made without departing from the spirit or sacrificing any of its advantages.

Forthe purpose of facilitating an understanding of my invention, I have illustrated in the accompanying drawing a preferred embodiment thereof, an inspection of which, when considered in connection with-the following description, my invention, its mode of construction, assembly and operation and many of its advantages should be readily understood and appreciated.

Referring to the drawing in which the same characters of reference are employed to indicate corresponding or similar parts throughout the several figures of the drawing: a Y

Fig. l is a diagrammatic representation of an electrical circuit used in connection with a gaseous discharge tube and embodying my new invention.

Fig. 2 diagrammatically illustrates a modified form of the circuit. 3

The'gaseous'discharge device which is referred to herein is an envelope or tube which contains an ionizable gas which emanates light rays of various wave lengths when the gas is ionized, as, for example, by causing an electrical discharge to occur through same. The familiar types of these devices are cold-cathode ray tubes, including neon tubes, glow tubes, and the familiar fluorescent lighting tubes.

My invention is especially adapted for use with fluorescent tubes because of the simplicity of construction and the positiveness of operation of the circuit. The elements used in my circuit may be assembled to produce a compact and serviceable fixture which will therefore be easy to install and service.

As is well known, gaseous discharge tubes require potentials of the order of twice their operating voltages for starting same. Consequently .means must be provided for producing such potential and applying it across the electrodes of a tube for a suiilcient time for the tube to be fired or ignited. Means must also be provided which will serve to lower the voltage from the ignition value to operation value in order to maintain the are without destroying the fllawhich will brightly fiuoresce when rays of cer- 40f tain wave lengths impinge thereupon. The ends of said tubes are provided with filaments II which serve as hot cathodes during ignition of the tube It, Leads l2 and it from the filaments l l are connected through a thermostatically controlled starting switch which serves to complate the circuit through thefilaments II when said switch i6 is closed.

The primary I5 01 a step-up transformer 18 is connected into the lead l2 as shown, and its secondary H has one sideconnected to an end of the primary I5 and the other and connected to the lead it through-a small spark gap l8.

The transformer with which I have had success is a cheap 6-volt pilot-light transformer which had been filament transformer and a small used to convert volt alter- I I nating current to 6 volt alternating current. I

merely reversed the same using th '6 voltside as the primary. The line voltage on this arrangement was 220 volts direct current.

The leads I9 and 20 of the filaments ii are connected to a direct current line 2|, preferably through a suitable pole changing switching device 22. A current-limiting resistor 23 is inserted in the lead l9, as shown.

The device operates as follows:

with switch 22properly connecting leads l9 and 20 to the line 2|, the starter switch His momentarily closed. Current now fiows through resistor 23, which takes a good deal of the line voltage drop; through the filaments II which begin to produce clouds of electrons to facilitate ignition of the tube at a comparatively low voltage; and through the primary l5 of the transformer i6. Shortly thereafter the switch i4 is opened, automatically asin the usual circuit of this type, causing the collapse of the magnetic field set up by the-primary IS. The transient produced is magnified as a high voltage in the secondary I1, and is sufficient to cause a spark to appear at the spark gap IS. A voltage of sufficiently highmagnitude to ignite the tube is now impressed across electrodes H, switch [4 being open, and the arc across the tube is consequently struck. The moment the arc strikes, the resist ance across the tube I drops to practically noth- 0 ing so that the direct current voltage from the line 2| can maintain the arc. The line voltage being so small in comparison with the voltage needed to maintain th spark gap [8, the spark is extinguished and, the transformer is is 'cut out of the circuit.

With this condition existing the current through the tube is practically limited only by the resistance of the resistor 23. The filaments ll now act as cold cathodes between which an electrical discharge is maintained.

In Fig. 2, I have shown a slight modification of my circuit. Instead of the transformer l6 and spark gap I8 being connected across the tube In in the short circuiting branch i2|3 which contains the starting switch I4, I here connect same between leads l9 and 20. The operation of the device illustrated in Fig. 2 is exactly the same as above described with respect to Fig. 1, except that when the arc across the spark gap I8 is extinguished, the primary l of the transformer I6 is still connected into the circuit. Consequently the current flow through the tube will be limited by the direct current resistance of the primary i5 besides by the resistance of re sister 23.

It will be' seen that there are no elements used in my device which are not highly simplified in construction and easy to obtain or manufacture from cheap materials.

It will be further seen that the operation of the apparatus of my invention depends upon no mechanical, electromagnetic, or like devices liable to become jammed, misadjusted, out of alignment, etc., and hence, a fixture constructed embodying my invention will be fool-proof."

It is preferred that a switch device 22 be inserted between line 2| and leads I!) and 20. This switch device should be so operative as to alternately connect different polarities of th line voltage across the leads l9 and each time the circuit is set into operation. Since the filaments H are at different polarity while the tube I0 is in normal operation there will be a tendency for one of the electrodes to bombard the other with diagrammatically in its simplest form in Fig. 2.

It is believed that my invention, its mode of construction, arrangement, assembly of elements, the manner of operation thereof, and many of the advantages and features should be readily understood from the foregoing without further description, and it should also be manifest that while a preferred embodiment of the invention has been shown and described for illustrative purposes, the details are nevertheless capable of wide variation within thepurview of my invention as defined in the appended claims.

What I claim and desire to secure by Letters Patent of the United States is:

1. In a circuit for initiating and maintaining the 'arc in a gaseous discharge device; a direct current source connected across and adapted to supply operating potential to said device, a branch of the circuit in parallel with said device and having transient producing means for supplying an ignition voltage to said device comprising a step up transformer the secondary of which is connected across said device, means. interrupting the flow of direct current'in the primary to cause the collapse of the magnetic field set up by said primary and as a) consequence of this collapse the production of a high voltage transient in the secondary for igniting said device,

and means disconnecting said secondary from said device upon ignition thereof, said disconnecting means comprising a spark gap adapted to have an are established thereacross during the transient and prior to ignition of the device, but being incapable of maintaining said are at the low voltage resulting from ignition of said device and hence becoming extinguished upon said ignition.

2. In a circuit for initiating and maintaining the arc in a gaseous discharge device having filament electrodes, a direct current source connected across and adapted to supply operating potential to said device, a branch of the circuit in parallel with said device and having a switching device and the primary of a transient-producing transformer connected therein, a second branch of the circuit in parallel with said device and having the secondary of said transformer and a spark gap therein, said switching device serving to close the circuit to the primary of said transformer and pass direct current therethrough whileheating the filaments and then, upon opening, to interrupt the flow of direct current inthe primary of said transformer, thereby causing the collapse of the magnetic field set up by said primary andas a consequence of this collapse the production of a high potential transient in said secondary, said high potential transient being capable of jumping said gap and igniting said device.

3. In a circuit for initiating and maintaining the arc in a gaseous discharge device having filament electrodes, a direct current source connected across and adapted to supply operating potential to said device, a branch of the circuit in parallel with said device and having a switching device and the primary of a transient-producing transformer connected therein, a second branch of the circuit in parallel with said device and having the secondary of said transformer and a spark gap therein, said filament electrodes being common toboth said branch circuits, said switching device serving to close the circuit to the primary of said transformer and pass direct cur-- rent therethrough while heating the filaments, and then, upon opening, to interrupt the flow of direct current in the primary of said transformer, thereby causing the collapse of the magnetic field set up by said primary and as a consequence of this collapse the production of a high potential transient in said secondary, said high potential transient being capable of jumping said gap and igniting said device, the arc of said gap being adapted to become extinguished when said device becomes ignited and maintained in operation by said current source, thereby opening the circuit of said second branch and cutting said secondary out of the circuit.

DAVID W. ABERNATHY.

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