Патент USA US2408495код для вставки
Oct. .1, 1946. M, A, TOWNSEND I ' ‘2,408,493 STARTING CONTROL FOR ELECTRIC DISCHARGE DEVICES Filed Dec. 6, 1941 Fig.1. ‘ ' P ML ' IL ooog‘logil ' ‘ lnvenfor: Mark A. Townsend’, ' by ‘ _ ‘ .Wm His A't't'orneg'. Patented Oct. 1, 1946 2,408,493 UNITED STATES PATENT OFFICE 2,408,493 STARTING CONTROL FOR ELECTRIC DISCHARGE DEVICES Mark A. Townsend, Cleveland Heights,’ Ohio, as signor to General Electric Company, a corpo , ration of New York Application December 6, 1941, Serial No. 421,941 11 Claims. 1 (Cl. 315-100) 2 This invention relates to the control of electric and Fig. 3 is a plan or end view of the more im discharge devices, and is especially concerned with the starting of such devices. The invention portant parts shown in Fig. 2. is very useful in connection with ?uorescent tubes or lamps of the positive column discharge type, and is hereinafter explained with particular ref erence to lamps of this character and their usual starting arrangements, as exemplified in U. S. Patent 1,951,112, March 13, 1934, to Wels, or Pat additional shunting modi?cation. starting is accomplished. Through deterioration in service or as the re pressure atmosphere of starting gas, such as argon at a pressure of 2 to 5 mm. of mercury, and sult of accident, ?uorescent lamps and other dis charge devices often or eventually become in capable of starting and normal running, so that the only effect of the automatic e?orts to start such as mercury. A supply of mercury, which may bimetal or other type of switch.- of rare gas, such as neon at an absolute pressure Fig. 4 is a view similar to Fig. 2 illustrating an I will ?rst describe the portion of the circuits and apparatus shown which have heretofore been in use, and which permit the objectionable ?ash ing of a defective lamp as described above. Fig. 1 shows an ordinary fluorescent tube lamp ent 2,212,427, August 20,1940, to Peters, for in 10 L of the positive column electric discharge type stance. with a tubular envelope Ill having spaced-apart Ordinary tubular ?uorescent lamps have elec activated thermionic cathodes H, H in its ends, trical starting circuits which are energized and which may be specially heated cathodes of usual broken to start the discharge. Sometimes this coiled~ ?lament type, and are shown connected has to ‘be done several times before the discharge across a power-supply circuit P including the actually starts. For this purpose, automatic usual ballast M, which also serves as a starting means are commonly provided which will make inductance, and the manual make-and-break and break the starting circuit inde?nitely until switch I5. The envelope I0 may contain a low also a vaporizable and ionizable working substance exceed the amount that will vaporize during oper ation of the lamp L, is indicated by a drop I‘! inside such a lamp is a continual ?ashing in it that is 25 the envelope Ill, and an internal coating of ?u very- annoying to those in the area ‘that receives orescent material or phosphor l8 on the envelope the light of the ?ashing lamp, besides uselessly walls is also indicated. A starting and electrode wearing out the starter device. Usually such in heating circuit H is shown connected across the capacity for starting is dueto loss of electron circuit P through the ?lamentary cathodes I I, I I, emission from one or both electrodes of the lamp, ' with a starting switch S included therein, which which may result from dissipation or other loss may be of thermal type. of activating material on which the emission de The general mode of operation in starting the pends. The objectionable flashing of such a lamp lamp L with this circuit arrangement is that when goes on inde?nitely, until the power supply is shut the switch I5 is closed to turn on the lamp L, the off, or the lamp is removed from the circuit. ' switch device S permits ?ow of currentv through The purpose of my invention is to obviate the the circuit H and the cathode ?laments H, II in undesirable ?ashing of defective lamps without series therein for a su?icient length of time to pre interfering with repetition of the attempts to start heat the cathodes to an adequate emissive tem as long as there is any reasonable promise of suc perature, and then suddenly opens the circuit H; cess. This I accomplish by rendering the starter 40 and the resulting voltage kick across the cathodes ineffective to open the starting circuit. I have H, II sui?ces to initiate discharge between them, shownand explained the invention as ‘applied to or, in other words, starts the lamp. a closed glow-switch‘ type of starter. The glow As shown in Figs. 1 and 2, the thermal switch switch illustrated is of double bimet'al type; but S is of glow-switch type, comprising a glass en the invention is equally applicable to‘ a single velope 20 containing a low-pressure atmosphere ' .Various features and advantages‘of the inven tion will become apparent from the description of species and forms of embodiment, and from of 50 mm. of mercury. The envelope ‘20 may in clude a stem 2| through which are sealed current leads 22, 23 that are connected to opposite sides the drawing. ' 50 of the circuit H, and are provided with terminals In the drawing, Fig. 1 is a diagrammatic view orv electrodes inside the envelope between which of a fluorescent tube or lamp with circuit connec a glow discharge takes place when the switch I5 is tions including my invention; Fig. 2 is a tilted or ?rst closed. In the switch S here illustrated, both perspective view of parts of a starting switch ap these terminals or electrodes consist of slender, paratus suitable for the purposes of my invention; 55 straight approximately upright thermostatic bi-' 2,408,493 3 4 metal strip members 25, ‘26 attached to the leads 22, 23, as by welding, and coacting as both tem perature-responsive elements and contacts for the switch S, Accordingly, contact pieces 21, 2'! order to prevent continued flashing or blinking of the lamp. (as of molybdenum) are shown welded to the free A simple control for this purpose is shown in Figs. 1, 2 and 3 as comprising an additional or ex~ traneous shunting thermostatic bimetal strip Ll These members member 30 that closes the heating circuit H more 25, 25 should be identical in order that they may heat and ?ex alike, and must be slender enough to keep the glow discharge current between them or less independently of the thermostats 25, 26, so low as to assure starting of the main discharge words, the bimetal 35 when sufficiently heated shunts both the contacts 27, 21 themselves and ends of these members 25, 26. and may, as here shown, suspend their further operation when it closes said circuit. In other between the electrodes ll, ll when the contacts 27, 27 separate and break the circuit H, as ex the path of current ?ow provided by the con— ductive supporting members 25, 2E and the gase ous atmosphere in the envelope 20. This ther~ most-at 33 may conveniently (though not neces sarily) coact with the members 25, 26 rather than with their leads 22, 23, and may be arranged with its opposite ends in position to engage these members. A compact and convenient arrange ment is for the slender strip member 30 to be plained hereinafter. The general operation of such a switch S is that when the circuit H is energized as a result of closing the hand switch IS, a glow discharge takes place across the gap between the parts 25, 26, shunting their co-operating contacts 21, 21. The conducting path for this current flow, which produces heat to heat the thermostatic bimetals 25, 26, is provided by the gaseous discharge at mosphere in the envelope 20, already mentioned. The discharge heats the members 25, 26 until they bend sufficiently to bring the contacts 21, 21 together to touch one another, thus closing the circuit H and shorting out the glow discharge. bent as shown in Figs. 2 and 3 almost into an elongated loop or oval which is disposed in a horizontal plane at a level where it surrounds the region of the glow discharge, and approximately perpendicular to the approximately upright mem bers 25, 2G, with its ends adjacent the latter. The thus augmented ?ow of current in the cir cuit H continues long enough to heat the fila mentary cathodes l l, l I to an adequate electron The member 30 may be supported about at its own midlength by an upright wire standard 3| welded to the member 36 and fused to the glass emissive temperature; and by the time this has been accomplished, the thermostatic members 25, 26 cool sufficiently to open the circuit H and start the main discharge between the electrodes I I, l l, as already described. After the main discharge has started, the voltage on the device S is no longer high enough to maintain any discharge across the gap between the parts 25, 26.. If, however, the main discharge does not start on the voltage kick due to the opening of the cir cuit H by the switch S as just described, a glow 40 stem 2i, and its fixed mid-portion is preferably discharge again takes place between the parts 25, 26, and the switch S again closes and opens, just as before; and if this effort is not success ful in starting the main discharge, it is repeated, and so on. In other words, the contacts 21, 2‘! alternately engage and disengage, over and over again, at short intervals. If the main discharge cannot be started at all, the lamp L would (with the circuit arrangement and parts so far de scribed) go on to ?ash in the objectionable man ner described above. close to the zone of the gap between the members 25, 26 where the heating effect from the discharge is greatest. As shown in Figs. 2 and 3, the mem her (it has contact pieces 32, 32 (as of molyb denum) welded to its ends, both of which are free to move as the member 30 ?exes in response to temperature changes. In starting a good lamp L, the starter S func~ tions in the usual way, just as if the control ther mostat 30 were absent; 1. e., this control does not enter into the action of the starter S, even though several operating cycles of the starter S should occur before the lamp L actually starts. This is because the member 30 is heated (like = the members 25, 25) only during the glow dis charge, and is less directly exposed to the heat of the discharge than the members 25, 26 which serve as electrodes for the discharge. In the case of a defective lamp, however, the cumulation of heat in the thermostatic member 30 due to the glow discharge while the starter switch S is open (during repeated cycles or starting attempts of In accordance with my invention, means of control are provided for determining the condi the starter) causes the member 39 to ?ex more tion of the circuit H as to continuity in such a and more, until eventually one end of it (or one way that after reasonable efforts of the starter in iV! of its contacts 32, 32) engages one of the mem bers 25, 26, thus connecting it into this side of S to start the main discharge, a closed condition of circuit H that prevents flashing of the} lamp L is established and maintained, independent the glow discharge circuit. Thereafter, the glow discharge takes place between the other of the members 25, 26 and the member 38, heating the and regardless of any further action or oper ation of starter S. For this purpose, automatic 60 latter until it ?exes into engagement with the other of the members 25, 26 thus shorting out control means may be employed whose period of operation (as fixed by design and adjustment) is long enough to include whatever number of at tempts by starter S may be considered reason ably worth-while; e. g., a period of some seven to ten seconds under favorable voltage conditions, embracing some ?ve to ten attempts, say. The action of this automatic control need not be an arbitrary matter of ?xed adjustment, however, but can be made responsive to the actual attempts of starter S to start the main discharge. As already mentioned, the particular control here illustrated determines the continuity of the cir cuit H in the positive sense-by closing it—in the glow discharge, and, in effect, establishing a shunt around the glow switch S. In thus shunt ing the contacts 21, H, the thermostatic mem .' her 3!! responds to heat produced by current flow in the path afforded by the gaseous atmosphere in the envelope 20, and accumulated during suc cessive intervals or periods of such current flow, though more slowly or in a lower degree than do the bimetals 25, 25. Under this condition, the member 30 (owing to its slenderness) functions as a heating resistance and is heated by the short circuit current through it sufficiently to keep it ?exed and maintain the shunt indefinitely. Cur rent thus ?ows continuously in the circuit H, awaits 6 U without any possibility of interruption by action of starter S, and the lamp L ceases to ?ash. ‘The springs", elastic members 25, 26 yield to any pres outer corners of the members 25, 25 may be, 117 inch each at ordinary atmospheric temperature. sure of the member 30, and the member 30' also 50 mm. of mercury, and zinc-coated members 25, 26, such a glow-switch is especially well With a ?lling of neon at an absolute pressure of yields elastically under such pressure. Thus con adapted for use with a standard 100-watt ?uores cent tube of positive column type. For lamps of tact is maintained as long as current flows in the circuit H, even though the members 25, 25 may cool somewhat and tend to open. other wattages, some variations of design and of 1 the gas ?lling and its pressure may be found ad However, if the circuit H is tie-energized’ (by opening the hand switch [5, or by removing the 10 defective lamp L and replacing it with a good one), and is allowed to remain de-energized long enough for the control thermostat 30 to cool off fully, the shunt will be opened, and the starter S will again be ready to- start the lamp in the visable. In‘ particular, the zinc coating on the members 25, 25 and the nature and pressurepr the gas ?lling influence the glow voltage and the closing time of the device, and the zinc coating itself stabilizes the glow voltage and tends to Fig. 4 illustrates a glow switch device generally reduce the time of operation of the switch. Moreover, it may be desirable to place a small amount of uranium oxide (e; g, 20 mg.) on the similar to that in Figs. 2 and 3, but different as interior surface of the switch envelope 2i], at‘it's regards the arrangement and con?guration of top (as indicated at 35), in order to make the usual manner. 15 I the extraneous control thermostat 3011. Instead 20 operation of the switch independent of whether it is in darkness or exposed to the light, as set of being in a horizontal plane perpendicular to forth in applicationSerial No. 403,572, ?led July 22, 1941, by Basil N. Clack, and assigned to the the thermostatic members 25, 26, the thermo static member 3011 is arranged in a vertical plane; and in outline it is a less complete loop, of an inverted angular U-con?guration. This allows the member 30a to‘ be made longer, to surround the region of the glow discharge more completely, and to be more effectively heated by the glow dis charge. As shown, the inverted uemember 30a assignee of this application. 25 _ What I claim as new and desire to secure by Letters Patent of the United States is: 1. The combination of an electric discharge device having a starting circuit comprising aura: matic switch means responsive to energization’ of is arranged like a door frame around the mem 30 the circuit for interrupting it to start a discharge in the device, and extraneous shunting means bers 25, 26, in a plane approximating the planes also responsive to energization of the circuit for of these members, and the upper end of its sup closing the circuit independently of said switch porting wire 3| is bent over across its horizontal means and suspending further operation of the middle segment. When this thermostat 30a closes, its free ends (or their contacts 32, 32‘) en-' gage against the edges of the ?xed lower ends of the members 25, 26, which are Virtually mere ends of the leads 22, 23. In Fig. 4, various parts and features are marked with the same reference numerals as in Figs. 1-3, in order to dispense with repetitive description, a distinctive letter being added where such dis tinction appears desirable. The operation of the latter after repeated operation of the switch’ means has failed to start the discharge. , _ 2. The combination of an electric discharge device having spaced electrodes, a starting cir cuit for said device comprising automatic switch means connected across and between said elec device as shown in Fig. 4 is essentially the same as already described in connection with Figs. 2 trodes and responsive to energization of the cir cuit for interrupting it to start a discharge be tween said electrodes, and extraneous shunting means also responsive to energization of the cir cuit for closing a shunt circuit between said elec and 3. trodes around the switch means and suspending I For the convenience of those wishing to use my invention, illustrative particulars of a device S of further operation of the latter after repeated operation of the switch means has failed to start the Fig. 4 type are here given: the discharge. ‘ a The thermostatic strip members 25, 26' may be 3. The combination of an electric discharge formed of the bimetal commercially known as “Chace #3300 bimetal,” composed of laminae of Invar, an alloy of 64'per cent iron and 36 per cent nickel, and of nickel, in equal thicknesses, welded together and coated with zinc on both sides. Each of these strips 25, 26 may be 0.015 inch thick, % inch wide, and 0.43 inch long, and the normal gap between their contacts 21, 21 when device having spaced electrodes, a starting cir cuit for said device comprising automatic switch they are at ordinary atmospheric temperature may be 0.022 inch. The thermostatic strip mem ber 30a may be formed of the bimetal commer cially known as “Chace #2400 bimetal,” com posed of laminae of the Invar above mentioned and of chrome iron (which is an alloy of '75 per cent iron, 22 per cent nickel, and 3 per cent chro mium) in equal thickness, welded together but uncoated. This strip 30a may be 0.004 inch thick, T16 inch wide, and 1.18 inch long before being means connected across and between said elec-' trodes and responsive to energization of the cir " cuit for interrupting it to start a discharge be tween said electrodes, and automatically reset table extraneous shunting means also responsive to energization of the circuit for closing a shunt circuit between said electrodes around the switch means and suspending further operation of the latter after repeated operation of the switch means has failed to start the discharge, said shunting means being constructed and arranged to maintain its closed circuit position only so long as current continues to flow through it. 4. In combination, an electric discharge de vice having spaced electrodes adapted to be pre heated by current flow therethrough, a ballast for said device, means including said ballast for connecting one end of each of said electrodes with a source of current supply, and thermal switch means comprising co-operating contacts connected between the other ends of said elec trodes and including heat supplying means and bent as shown in Fig. 4. In its bent form, its parallel legs may be 0.44 inch long each, and spaced 0.30 inch apart, so that its horizontal top portion may be 0.30 inch long. The distance be tween this top portion and the upper corners of the members 25, 26 may be 0.04 inch, and the gaps between the parallel legs and the lower 75 means responsive to the heat produced by said 2,408,493 7 8 heat supplying means for alternately causing one tacts into engagement with the other contact of said contacts to engage and disengage the whereby said contacts alternately engage and other contact and thereby attempt to start the disengage each other, and extraneous shunting device, and thermostatic shunting means respon means responsive to the heat accumulated dur slve to the resulting current flow for closing a Si ing a plurality of successive intervals of current shunt circuit around the switch contacts upon flow in said path to close a shunt circuit around accumulation of heat therein during a plurality of successive attempts of the switch to start the the said contacts and thereby terminate further operation of the switch, said shunting means comprising a bimetallic strip having a resistance 5. In combination with an electric switch com 10 such that the flow of current therethrough after prising means for automatically and repeatedly it has closed the shunt circuit keeps it heated closing and opening its contacts, extraneous shunt and flexed in circuit closing position. means operable upon energization of the switch 10. A thermal switch comprising a pair of nor device. for closing a shunt circuit around the switch mally spaced co-operating contacts, conductive contacts after a predetermined period of opera 15 support members for said contacts, at least one tion of the switch. of said support members being a bimetallic strip, 6. In combination with a thermal switch com means providing a current conducting path shunt prising means for supplying heat to automati cally and repeatedly close and open its contacts, extraneous shunt means responsive to the heat produced by said heat supplying means for clos ing a shunt circuit around the switch contacts upon accumulation of heat therein during a pre determined period of operation of the switch. 'I. In combination with a thermal switch com prising means for supplying heat to automatical ly and repeatedly close and open its contacts, ex traneous shunt means responsive to the heat pro duced by said heat supplying means for closing a shunt circuit around the switch contacts upon accumulation of heat therein during a predeter mined period of operation of the switch, said shunt means being a heat-deformable member having a resistance such that the flow of current there through after it has closed the shunt circuit keeps . it heated and ?exed in circuit closing position. 8. A thermal switch comprising a pair of nor mally spaced co-operating contacts, means pro viding a current conducting path shunting said contacts, means responsive to heat produced by current in said path for moving one of said con tacts into engagement with the other contact whereby said contacts alternately engage and disengage each other, and extraneous shunting means responsive to the heat accumulated dur- 1. ing a plurality of successive intervals of current ?ow in said path to close a shunt circuit around the said contacts and thereby terminate further operation of the switch. 9. A thermal switch comprising a pair of nor mally spaced co-operatingcontacts, means pro viding a current conducting path shunting said contacts, means responsive to heat produced by current in said path for moving one of said con ing said contacts and supplying heat to said bimetallic strip to cause it to carry its contact into engagement with the other contact where by said contacts alternately engage and disen gage each other, and an extraneous shunting bi metallic strip mounted with its ends adjacent to but normally spaced from the respective contact support members, said shunting strip being re sponsive to the heat accumulated during a plu rality of successive intervals of current flow in said path to carry its ends into engagement with the respective contact support members and thereby close a shunt circuit around the contacts. 11. A thermal switch comprising a sealed en velope containing an ionizable medium, a pair of bimetallic strips ?xedly supported at one end in said envelope and carrying contacts at their free ends, said strips being spaced for a glow discharge therebetween and being arranged to flex toward each other to carry said contacts alternately into and out of engagement with each other, and another slower acting bimetallic strip supported intermediate its ends in position to be heated by said glow discharge and having its free ends adjacent to but normally out of engagement with respective ones of said pair of strips, said slower acting strip being arranged to ?ex in a direction such that its ends are carried into shunting engagement with said pair of strips upon accumulation of heat therein during a plu rality of successive intervals of current ?ow in the glow discharge, said slower acting strip hav ing a resistance such that the ?ow of current therethrough keeps it heated and ?exed in cir cuit closing position. MARK A. TOWNSEND.