US2305583A - Fluorescent lamp starter unit - Google Patents

Description

c. H. HoDGKlNs 2,305,583

FLuoREscENT LAMP STARTER UNIT Original Filed May 24, 1941 Dec. 15, 1942.

B Amm ATTORNEY meneame. 1s, 1942 FLUOBESCENT LAMP STARTER UNIT Charles H. llodglxins, Fairfield, Conn., assignor, by mesne assignments, to The Bryant Electric Company, Bridgeport, Conn., a corporation of Connecticut @riginal application 'May 24, wel, Serial No. 395,@13. Divided and this application August 2'?, i941, Seriai No. @dell d Claims.

This invention relates to automatic circuit vcontrollers, and more particularly to circuit controllers which automatically interrupt or re-establish circuit oy thermal activation and constitutes a division ci' my (co-pending application, Serial No. 395,613, iiled May 24, 1941, and assigned to the same assignee as the present invention.

Various electrical devices, such as gaseous discharge or fluorescent lamps, utilize for one purpose or another, a plurality of circuit paths and require automatic selective means for directing the current to the appropriate path under cerexisting conditions. For instance, gaseous discharge or uorescent lamps include spaced lilainentary electrodes of electron emitting character within a gas-lilled tube, and the desired main current path for securing luminosity of the lamp is by way of an arc struck along the electron path Afrom electrode to electrode. @ne of the characteristics of lamps of this type is the diculty in starting a discharge between the electrodes. The voltage necessary to strike the arc is ordinarily higher than that required to maintain the arc after it is once established, and as it is desirable to economically employ voltage of the usual domestic line potential for maintenance of the arc, starting means to initiate or strike the arc are Wil-Miti an automatic circuit controller adapted to he and which is physically associated with .a gaseous discharge lamp and adapted. to be situated ordinarily employed. For that purpose, a shunt circuit is provided across the electrodes connecting them in series, that circuit having an auton matic controller to interrupt the shunt circuitconnecting the electrodes in series, but those de` vices have been of a character necessitating phys,- ical disassocation from the lamp and have also functioned so rapidly that the circuit is opened before the electrodes have reached sufficient temperature to be effectively emissive of electrons to enable the arc to be initiated or maintained.

It is accordingly an object of the present in-` vention to utilize a combined thermal and magnetic actuationof the make and break mechanism of the automatic circuit controller which will not only obtain the desired delay in circuit interruption, but will obtain a rapid separation or break between contacts when the break starts.

A further object of the invention is to provide within the lamp base.

Another ohiect of the invention is to provide an improved automatic circuit controller having delay action .that will insure adequate electron emission to loe attained from the electrodes before opening of the shunt Vcircuit takes place.

Still further objects oi the invention will appear to those skilled in the art as the description progresses, both by direct statement thereof and by implication from the context.

In the accompanying drawing, wherein like numerals oi reference indicate similar parts throughout ,the several views and wherein the invention is disclosed in combination with a gase ous discharge or iluorescent lamp:

Figure l is a longitudinal section oi one end portion oi a lamp envelope ar :l base showing the automatic circuit controllers in edge elevation therein;

Figure 2 is a cross-sectional 4view on line iii-H. o Figure i, showing the automatic circuit controller in facial elevation;

fligure d is a sectional view on line Iii-Ill' of Figure 2, hut upon larger scale than the showing oi Figure 2; f' l Figure e is a sectional view on line V-IV oi Figure 2, showing the shunt-circuit contacts closed;` v y Figure 5 is a sectional view similar to Figure but with the shunt-circuit contacts open;

Figure 6 is a circuit diagram of the circuits involved in connection with a gaseous discharge lamp;

Figure 'l is a face view similar to Pig. 2 showing a modified construction of controller and showing wiring connection toa gaseous'discharge lamp;

Figure 8 is a. vertical central section of the controller of Figure 7;

Figure 9 is a. face view of a further modied construction of controller; and

Figure 10 is a. vertical central section thereof, and showing wiringconnection to a gaseous discharge lamp. l

In the specic embodiment of the invention illustrated in said drawing, and with attention directed initially to Figures l to 6 thereof, the reference numeral I2 designates in general a gascous discharge or fluorescent lamp having the usual transparent or translucent sealed envelope with re-entrant stems I3 at each end thereof and integrally formed therewith. Inthe process of manufacture, the envelope is evacuated and then filled with an inert or rare gas, such as argon, neon, etc., at a few millimeters pressure and with an ionizable medium such as a few drops of mercury, sodium or other readily volatile material also included in the envelope. Likewise in process of manufacture, lead-in Wires are sealed through the stems for constituting terminal connections Iii, i5 in pairs through each stem with each pair mounting a coiled iilamentary electrode in series therewith within and crosswise of the envelope. The structure accordingly provides electrodes I6, il at opposite ends of the envelope and it is between these electrodes that the desired arc for illuminating purposes is to be initiated and maintained. As is usual in such lamps, the electrodes are of a refractory metal, such as tungsten or the like and rendered copiously electron emissive by appropriate use therewith of an electron emissive material, such as an oxide of barium, strontium or the like. These structural features of the lamp likewise exist in the lamp indicated in Figures 7 and 10, except that each electrode of the lamps of Figures 6 and 7 are intended for about 40 to 50 Watt consumption whereas higher wattage may be consumed with showing of Figure l0.

As shown in Figure 6, one terminal I4 of electrode I6 is connected through a heater coil I8 hereinafter described and located and thence by an exterior conductor I9 connects through an inductance to one side of the source of supply of the customary domestic potential of 115 or 230 volts. Likewise, one terminal I4 or" the other electrode II is connected through an external switch 2l by conductor 22 to the opposite side of the domestic source of supply. Switch 2| is the one manipulated by the user for turning the lamp on or 01T. v

It is furthermore usual practice in lamps of this character to cap the envelope at each end with a metal base from each of which protrudes a pairof terminal yprongsor pins suitably insulated from each other. It is an'object of the present invention to maintain this physical aspect of the lamp that the lamp of my invention may be employed in fixtures of the prior art. Each end of the lamp of Figures l to 6 accordingly has protruding terminal prongs 23, 24 and an end base 25. It is a further object of the present `invention to include my, improved circuit controller within one of the bases. The end of the lamp having the vbase 25 including the controller is the one more particularly illustrated in the drawing.

.pansion such that a rise of temperature will result in a bending of the member, and as here shown the relation of the particular metals used will obtain a swinging of the legs of the member toward each other when the temperature is increased.

The normal relationship of contacts 26 and 21 v isJ that of physical and electrical engagement,

and to cause disengagement thereof the heretofore mentioned heater I8, such as the resistance coil shown,y is provided in proximity to the said thermal responsive member 29. Since this heater coil is in series between the source of power and the filament it begins to generate heat and continues so to do as soon as switch 2l is closed for lighting the lamp and as long as there is a current iiow either through the lamp or the shunt circuit.

The particular arrangement of parts preferably employed for compactness and for incorporating the same within the base will now be described. The metal base 25 is of collar-like construction attached 4by cement 36 or other plastic in place concentrically on the end of the envelope, a nange on said base and said cement also retaining an insulating disc 3i within the outer end of the base. On the inner side of disc 3I is a mounting piece 32 shown as a smaller and concentric reenforcing insulating disc as an internal means for mounting various parts of the controller. Extending radially inwardly from one edge of this mounting piece or disc 32 is a foot portion of a bracket 33 riveted at 34 to the discs. Said bracketbends to provide an upstand- `ing portion at right angles to the face of the disc in a direction toward the envelope and then bends again in the same general radial direction to provide an offset portion 3-5 parallel to the disc and spaced therefrom and extending far enough to be substantially over the center of the disc. One leg of the aforementioned U-shaped thermal responsive member 29 is riveted substantially above the center of the disc at 38 to this offset portion of the bracket, but extends in a different ,diametric direction and with said member armaterial which passes between the legs of said member next the U-bend thereof. On this bridge is wound the aforementioned heater coil I8 at the part of the bridge directly between the legs of the member so that heat from the heater affects a considerable portion of the U-member by its close proximity thereto. Furthermore, the parts are so arranged that one end of the bridge is mounted on the inner end of one terminal prong 23, Whereas the opposite end of the bridge is secured in place by a mounting stud 38 riveted thereto and to the mounting piece or disc 32. Terminal connection I4 to the lament is also attached to mounting stud 38 thereby placing the filament in series with the heater coil. The other end of the filament, by interposition of connection I5 which is physically attached to bracket-securing rivet 34, is in series with said bracket and U-member 29. With contact points 26, 21, closed, the circuit then is carried through a bus bar 40 to the other prong 24. That prong 24.is connected through the fixture (not shown) by aforementioned exterior conductor 28 to a prong at the other end of the envelope, its connector I5, lamentary electrode Il, to the other connector I4 and its prong and thence through switch 2| back to the source of power.

The physical disposition of the prongs and rivets. mentioned is preferably such that the prongs, in end view-are at points substantially on a diameter of the disc 32 and that diameter is diagonal with respect to another diameter substantially on which the rivets 34 and stud 38 are disc and areV thus symmetrically disposed lthe magnet.

`several important resultssituated, these latter being also attaching points for the iilament connections. said stud and rivet just mentioned are-atsubstantially equal distances from the center of the with respect to each other.

In the area adjacent the fixed contact 26 is situated a permanentmagnet 4I here shown as substantially cylindrical and axially perpendicular to the insulating discs with its outer end engaging atwise against the inner wall of outer insulating disc 3| and the adjacent cylindrical end portion located in a circular cut-out next one peripheral portion ofthe inner insulating disc 32. The magnet, however, projects above the said inner disc, and is diametrically slotted at'its prolecting end, as at 42, in juxtaposed relation to the movable contact leg of the U-shaped member so as to receive said leg in part in said slot. aforementioned bus bar 40 enters at one end of the slot nearest the center of the disc, extends along the bottom of the slot to the outer end.

thereof, and there supports the fixed contact 2t with the exposed face of the contact below the exposed end, face of the magnet.

Carried by the leg of the U-shaped member which traverses the magnet, is a cross-bar or keeper 43 of soft iron adapted to come into contact with the magnet while the contacts 26 and El are in engagement with each other, Said keeper is shown with burrs on its side tov/ard the magnet face which will prevent extensive surface contact and sticking of the keeper to Furthermore, in order that-the keeper may not act to prevent contacts 26 and 2l from engaging, the forward end oi the under leg of the U-shaped member is preferably constructed as two spring arms 4t, 45, the first above the second, with the upper one 44 longer than the under one and carrying vthe contact piece 2li next The prongs and,

out that there is a rapid loss of inuence of a magnetic eld with increase of distance from the magnet, namely the attracting force is inversely proportional to the square of the separating distance. Accordingly, while the magnet holds the keeper as tension builds up ih the thermal mem- Y ber, the moment that tension obtains the least will thus obtain a tendency for the keeper supporting spring arm 45 and movable contact supporting arm 44, to bend downward under iniiul ence of heat at the same time that the main part ci the under leg of the U-member tends to bend npwardly. By this construction I compensate for the increased ambient temperature that develops inthe space enclosed by the base with the lamp in operation. This will accordingly assure normal engagement of movable contact with the ixed contact and of keeper with magnet notwithstanding ambient ltemperature and until the heater acts upon the U-member to obtain a denite and material deection of the lower movable leg. i

The above-described structure of contacts, spring arms, thermal member and magnet obtain l the lamp will positively start on rthe rst separation of the contacts to interrupt the shunt circuit, and accordingly increases the life of the lamp. Furthermore the structure provides a contacting arrangement which is positive both in The time taken for shunt circuit.

ruption ci the inductive circuit to cause the high voltage surge across the electrodes to establish the main lamp circuit with the opening of the hagain, the structure obtains a quick closing or the contacts when the lcurrent to the lamp is discontinued, since the keeper comes into the influence of the magnet as the bimetal tension subsides, and the magnetic iniiuence becomes stronger as the bimetal thermal tension becomes weaker due to the approach of the keep- -er to the magnet. The lamp may accordingly be relit promptly after being turned off.

Referring now to the modification of Figures 'l .and 8, the same construction of envelope, electrodes and lead-in wires and terminal connections are in accordance with the preceding description, and the same reference numerals are accordingly applied. PThe controller here shown provides an insulating piece i6 on the inner face of which is mounted a permanent magnet Si shown as cylindrical with one face engaging the mounting piece dit and with its other face dia- Y metrically slotted as at 48. i coiled or other electrical resistance heater t9 passes longitudinally through the said slot free from engagement with the magnet. rlhe ends or the heater are supported at opposite sides of the magnet by supporting posts or studs 50. At right angles to the said slot is a lJ-shaped thermal responsive member 5i having a short ieg riveted at 52 to the mounting piece 4B, this leg making no contact with the magnet but extending from adjacent the periphery thereof away from the magnet, bending in U-shape upwardly away from the mounting piece so as to provide an overlying longerleg passing across the upper face of the magnet at right angles to the slot in said magnet. Where this overlying leg of the thermal member crosses the magnet, a cross bar or keeper 53 is provided as a iixed part of said leg. This keeper, as in the showing of Figure 3, provides a limited surface contact with the magnet while the supporting leg is in normal position.

At the extreme end of the overlying leg of member 5I is a movable contact point 54 normally in engagement with a fixed contact 55 carried by the mounting piece 46 as described with respectto the preceding viigures. v.The U-shaped thermal responsive member 5i is of bimetal so that the heat will exert a tension between the two metals employed and obtain a bending of the overlying leg away from the other leg and mounting piece. Accordingly, when heatbecomes effective upon the bimetal of this showing, the

contacts `54, 55 .are separated as soon as sutil-l make and Vbreak functions. It may be pointed cient tension is developed to overcome the magnetic attraction and retention of magnet 41 upon keeper 53, and the opening or separation of those` contacts is yrapidwhen once started as will be readily understood from the explanation given with respect to the preceding figures. The situation of the heater Within the slot of the magnet below the keeper, necessitates the heat to first aifect( the keeper and then aiect the bimetal by conduction from the heater thereto. Accordingly, the delay for the heat to thus develop and /become effective upon the bimetal introduces the desired delay in the opening or separation of contacts 54, 55.

The wiring of the controller of Figures 7 and 8 -is similar to the Wiring heretofore described with respect' to Figs. 1 to 6. Briefly, a connection 56 from one side of the source of domestic potential carries the current through an inductance 51 and thence to one heater post 50, through the heater 49 to the other post 50, thence to electrode connection I4 at one end of the lamp, through electrode I6 and the other electrode connection I5 therefor and back to the controller making con-` nection With the contact 55. Assuming the contacts to be closed, the current path continues through' movable contact 54, U-shaped member 5I t-o its rivet mounting 52 which has a wire connection 58, to the other end of the lamp and through the terminal connection I4 thereat, filament I1 and other terminal connection I5 to the wire 59, switch 60 and thus arrives back at the source of domestic potential.

The showing of Figures 9 and lvlikewise includes a/ mounting piece 6I carrying a permanent magnet 52 cylindrical configuration arranged endwise upon the mounting piece and secured by a metal clip 63 end portions of which project through the mounting piece next the periphery of the magnet at diametric opposite parts thereof and bend inwardly into a diametric slot across the front face of the magnet. A U-shaped bimetal thermal responsive member 64 is associated with the magnet, said member. being here shown as having one leg at the back of the mounting piece and secured in place by being brazed or otherwise secured to the said clip 63. Next to and longitudinally of the secured leg of member 64, the mounting piece is slotted, at 65, to pass the curving part and front leg of the U-shaped thermal member to the front side of the magnet.

Secured to this front leg of the U-shaped member, as by rivets 66, is a soft iron keeper 61. This keeper is a at piece of metal presenting side segments connected by a cross portion or shank 68 integral With the said 4segments and having a longth substantially equal to the width of the slot in the magnet. The segments of the keeper are provided with limited surface engagement with the face portion of the magnet on opposite sides of the slot and the shank portion B8 extends across the slot. Insulation is provided on the surface of the shank, and a heater coil 69 is wound around the insulation. One end of this heater coil is grounded to the U-shaped member as by engaging it under one of the rivets 66 connecting the keeper to the U-shaped member.

The other end of the heater wire is insulated coil moves with the leg on which the movable contact is mounted, and that heat from the coil has to be transmitted byconduction through the keeper to the bimetallic thermal responsive U- shaped member. A fixed contact 1| is`carried by the mounting piece 6I for engagement by the movable contact. The circuit through the controller enters by suitable connection 12 with the U-shaped thermal responsive' member and after passing through the heater 69, movable contact 10 and fixed contact 1I passes out of the controller through another connection 13.

While this controller is adaptable to use for breaking a shunt circuit as in the preceding instances, I am using this opportunity of illustrating applicability of my invention in any one of the forms to Yuse with a secondary delay means where greater delay is required' than will be normally obtained by my improved controller alone. Where a lamp employs electrodes of higher wattage consumption and where the lamp is accordingly of greater length and the electrodes thus further separated a greater delay in the opening of the shunt circuit is necessary in order that the electrodes may become 4sufiiciently heated and electrons profusely enough emitted to accomplish the ionization and striking of the arc between the more distant electrodes. It is accordingly feasible to combine my controller with other known or preferred control means. By way of example, I have illustrated my controller in Fig. 10 coupled in series with the elements of an auxiliary relay discharge tube 14, details of which are set forth in prior U. `S. Patent 2,200,443 of May 14, 1940, to E. C. Dench. Briefly, the showing provides a gas filled envelope having therein a bimetallic electrode 15 which is, in this case, normally open with respect to a contact 16 in the container. A cathode 11 is associated with electrode 15, and as explained in the aforementioned patent, applied-voltage obtains slow discharge and heat development which ultimately distorts the bimetamc eiectrod 15. After a triing period of no consequence to this description, sulcient glowwiischarge in the relay to cause its bimetallic electrode 15 to distort, that electrode completes its short circuiting contact with contact 16. The 12R effect in the electrode 15 keeps it hot and deflected. At such time, a suiiicient current ow takes place to heat the heater 69 of my controller and thus injects the desired initial delay of current tiow through the lamp velectrodes I6 and I1, pending separation of contacts 10, 1I of my controller. The desired additional delay is obtained by magnetically deterring the contacts in their closed relation;

In the showing of Figure 10, I have included wire connection 18 from one side of the domestic potential supply, through an Ainductance 'I9 to terminal connection I4 of the lamp, lamp electrode I6 and other terminal connection I5 to the line 19' leading to the bimetallic thermal responsive element 15 of the auxiliary relay discharge tube 14, and on the return passage from my controller through connection 13, the current passes to the other lamp lament I1 and out through switch back to the source of supply. The said relay discharge tube and my controller are normally in series and form a shunt circuit for the I main arc circuit of the lamp, with the relay operating to close this shunt circuit as a preceding step to functioning of my controller heater to introduce its delay action of opening the shunt circuit to the lamp electrodes. A capacitance 8| such as an .006 mg. condenser is preferal'ly insorted in the shunt circuit parallel to the series connected controller and auxiliary discharge tube .'ll, as an aid in producing the arc-striking surge when the shunt circuitis opened by my controller.

Obvously other detail changes and modifications may be made in the construction and use of my improved controller, and I do not wish to be understood as limiting myself to the precise showing herein made except as set forth in the 10 following claims when construed in the light of the prior art.

I claim:

1. An automatic circuit controller comprisingY a ilxed contact and a movable contact separation 15 of which interrupts the circuit controlled, means associated ltherewith tending to move the movable vcontact and separate said contacts in consequence of current flow other than through said contacts and which continues after said con- A20 tacts are separated, and magnetic means opposing separation of said contacts and delaying ult'imate separationthereof.

2. An automatic circuit controller comprising a U-shaped bimetal thermal responsive member one leg of which is movable in response to heat variation, compensating bimetl arms on the movable leg of said' member, one arm mounting a keeper and the other arm mounting a movable l contact, a vnrred contact normally in engagement n .withthe movable contact, and a magnet associated with said keeper and tending to keep the movable contact in engagement with the iixed contact in opposition to the separating tendency imposed by functioning 'of the movable bim'etal leg under influence o! rising temperature.

3. An automatic circuit controller comprising a U-shaped bimetal thermal responsive member having one leg movable in response to heat variation and having a keeper on said leg, a slotted.

magnet adjacent said leg and keeper tending to keep the movable leg drawn toward the magnet in opposition to the separating tendency imposed by functioning of the movable bimetal leg under iniluence of rising temperature. and a ilxed heater extending through the said slot of the magnet for transmitting heat to the keeper and said leg of the thermal responsive member.

4. An automatic circuit controller comprising a U-shaped bimetal thermal responsive member having one leg movablein response to heat variation and having a keeper on said leg, said keeper having a heater mounted thereon and movable therewith, and a xed magnet adjacent said u keeper and heater and functioning in .opposition to tendency of the bimetal leg to move the keeper and heater away from the magnet as heat from the heater raises the temperature of said bimetal leg.

CHARLES H. HODGKINS.

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