US2395145A - Gaseous tube - Google Patents

Description

Feb. 19, 1946.

P. K. RANNEY 2,395,145

GASEOUS TUBE Filed April 29, 1944 IN VEN TOR. figfic'll/A L /1. F4 NIVE'Y Patented Feb. 19, 1946 UNITED STATES PATENT OFFICE 6 Claims.

This invention relates to gaseous tubes,,and particularly to those known as fluorescent tubes. Heretofore, fluorescent tubes of the hot cathode type have included a cut-out switch, the operation of which has resulted in a time lag between the initial operation of the controller and the actual lighting of the tube. I have designed and used a transformer that will light a fluorescent tube instantaneously without the need for a cutout switch, but due to the higher voltage employed, the Board of Fire Underwriters has been apprehensive lest during removal of a tube it might be possible for an operator to receive a severe shock unless the primary circuit could be disconnected upon removal of a tube. If a standard socket is used and if the primary current is allowed to flow at all times through the filament, the life of the tube is shortened.

To avoid the aforesaid occurrence, I constructed a lamp holder with a shiftable current conducting member which was so arranged that the prmary circuit would be continuous whenever a tube is positioned in the holder, but would be interrupted automatically upon removal of the tube from the holder. Difiiculties arose, however, in adopting such holder commercially in that proper alignment could not be maintained satisfactorily between the parts of the holder and between the coacting holders, as a result of which the current interrupter would not always function either to break the flow of current in the primary circuit upon the removal of the tube, or properly to shunt the current in the desired manner. Additionally, the lamp holder was relatively expensive to manufacture, and was objectionable'in that it interposed a mechanically movable part in the assembly.

An object of the present invention is to permit the use of my aforesaid apparatus to effect instantaneous starting of a fluorescent tube without the necessity for any mechanically movable part in the apparatus, without shortening the life of a tube, and without necessitating the use of a special holder as aforesaid.

My invention contemplates using as a cold cathode a gaseous tube which is equipped for operation normally as a hot cathode tube, without necessitating removal of th filament therefrom. In practice, this is carried out by connecting a shunt across the members that are used for conducting current to the filament, and the shunt may be arranged either inside the tube or externally thereof, as desired. In this way, a. filament tube may be used with my aforesaid apparatus to obtain instantaneous starting without the objections incident to the continuous passage of the primary current through the filament, and without the consequent shortening of life of the tube. Moreover, if the tube should burn out, the primary current would still be 7 opened automatically, thus removing danger to anyone who may be working on the fixture for maintenance or repair purposes.

Referring now to the drawing, Fig. 1 is a perspective view of part of a fluorescent tube embodying my invention; Fig. 2 is a plan view of the shunt connector used externally on the tube shown in Fig. 1; Fig. 3 is a side'view of a tube partially broken away to show a shunt construction mounted internally or the tube, and Fig. 4 is a wiring diagram illustrating the operation of a system for lighting two fluorescent tubes.

Referring first to the wiring diagram, the load comprises gaseous tubes l and H. The tubes [0 and H have filaments l2, l3, l4 and I5 respectively, that are suitably connected through lead-in wires to connector prongs that are adapted to be inserted into a socket or holder in the usual way. In practice, the tubes are adapted to be mounted in a common fixture and are adapted to be energized, as for example, by the apparatus illustrated in Fig. 4,

In Fig. 4, one side of the current supply conductor, indicated at 20, is connected to one terminal of the filament [4, the other of which is connected to a conductor 2| to the filament l2 of the tube Ill. The other end of the filament ID is connected by a conductor 22 to a'primary coil 23 which is mounted on a transformer core 24, while the other end of the primary coil is connected to the conductor 25 to complete the primary circuit.

The transformer shown is the shell type having a central leg 26 on which the primary coil 23 aforesaid is mounted, and on which secondary coils 21 and 28 are also mounted. The primary coil is positioned between the secondary coils, the spacing being such that a magnetic shunt 29 is disposed between the coils 23 and 27, while the coil 28 is in close proximity to the coil 23'. One end of the coil 21 is connected by conductor 39 to the primary conductor 22, while the other end thereof is connected by the conductor 3| to one terminal of the filament l3 in the tube It). In a like manner, one end of the coil 28 is connected to a conductor which in turn is connected to the primary conductor 22, while the other end is connected by conductor 36 to one end of the filament l5 in the tube H. A condenser 31 is interposed in the conductor 36, and operates to impart a leading current to the tube l 1, whereas the shunt 29 operates to impart a lagging current to the tube Ill, whereby stroboscopic efiects are minimized in the operation of the tubes.

The aforesaid apparatus forms the basis of an application for Letters Patent, Serial No. 435,449,

filed March 20, 1942, by me, which issued August 1, 1944, as U. S. Patent No. 2,354,879. Such apparatus operates on suificiently high voltage that the tubes are started instantaneously upon the closing of the. primary circuit. To avoid shortening of the life of the. tubes, however, consequent upon the continuous impression of the primary current continuously upon the filament, the present invention provides a shunt in the primary circuit and said shunt may be positioned either externally or internally of the tube. For

the internal construction, the shunt embodies the arrangement illustrated in Fig. 3, where a current carrying conductor 40 is Welded across the lead-in wires 41 and 42. Normally, the shunt prevents heating of the filaments, wherefore the tube operates as a cold cathode because the voltage impressed is high enough to start the tube. If desired, however, the shunt can have sufiicient resistance to allow enough current toflow through the filament tofacilitate starting in extremely low temperatures. I haveicund for example that satisfactory results may be obtained by using a shunt having a resistance of 65 ohms in a 40 watt lamp. In such lamp the filament resistance would also be about 65 ohms.

To facilitate the use of the present invention with a tube having the standard filament contion thereon. For this purpose the diametrical distance across the space between the points on two opposing prongs is less than the diameter of theprong which is intended to be used. Strips made according to the foregoing construction may readily be carried in stock where tubes are sold, and may be applied either by the seller or the user. if the tube is intended for use with apparatus, such as that. illustrated in Fig. 4.

If, on the other hand, the. tube is intended. to be used in the normal way, such for example as with the starting switch having a time lag characteristic, then the tube can be used without the strip 60 in the normalmanner. The resistance of thestrip 69 can be predetermined, as aforesaid, so as to permit the passage of enough current through the filament to assist starting under low temperature conditions. The amount of current thus passed, however, will not have a deteriorating effect upon the life of the filament as wouldbe the case if the tubes were-used without the shunt construction aforesaid.

An important advantageof the present invention is. that instantaneous starting of fluorescent tubes is made available without the accompanying objection of shortening the tube life incident to the continuous flow of all the primary current throughv the filament. A. further advantage of the present invention is the fact that instantaneous starting may be obtained without the necessity for a special tube-receiving socket or holder which requires a mechanically actuated current conductor as apart thereof. The invention of the present application is adaptable for use either internally or externally of the tube, and in the case of external use, the invention permits the retention of tubes as at present available, with the filament therein, without necessitating the reconstruction. thereof.

I claim:

1. In a gaseous tube having a base and an electrode therein, a pair of current conducting mem-- bers' connected to the electrode and including a pair of rigid pins projecting from said base and adapted to be inserted into a socket for connection to a source of current supply and shunt means. connected across said members and embodying a part of the unitary construction of the tube itself. v

2. A- gaseous tube having a filament therein,

. and having current conducting leads attached thereto and extending through a wallof the-tube, and shunt means connected across said leads inside said tube.

3. In a gaseous tube having a base and an electrode therein and having current conducting members connected to the electrode and including a pair of rigid pins projecting from said base andadapted to be inserted into a socket for connection toa source of current supply; and shunt means connected across saidmembers outside the tube but comprising a part of the unitary construction of the tube itself.

4. In a gaseous tube having a baseand an electrode therein, a pair of current conducting mem bers connected to the electrode and including a pair of rigid pins projecting from said base and adapted to'beinserted into a socket for connection to a source of current supply, and a current conducting bridge piece carried by the members outside the base but comprising a' part of the unitary construction of the tubeitself, said bridge piece having openings therein for receiving the pins and having means thereon adjacent the openings for frictionally engaging the pins and making a current conducting contact therewith.

5. In a gaseous tube having a base and an electrode therein, a pair of current conducting members connected in the electrode and including a pair of rigid pins projecting from said base and adapted to beinserted into a socket for connection to a source of current supply, and a shunt member comprising a strip of metal having openings therein adapted to receive said pins, said member being adaptedto be pushed onto the pins by movement thereof axially of the tube, and said shunt member having flexible portions integral therewith and adapted to engage the pins and to be bent out of the plane of the strip during the application of the member to the pins, said flexible portions operating to hold the member out of the pins and to make electrical contact there'- with by the member and to comprise a unitary construction with thetube.

6. In a gaseous tube having a base and a filament therein, a pair of current conducting members connected to the electrode and including a pair of rigid pins projecting from said base and adapted to be inserted into a socket for connection to asource of electrical current supply, andshunt means connected across said members, the electrical characteristics of said shunt means being such as to permit enough current to-ficw through the filament to heat it sufliciently to start the tube under low temperature conditions.

PERCIVAL K. RANNEY.

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