US2416751A

US2416751A - Electric discharge lamp and controlling means therefor

Info

Publication number: US2416751A
Application number: US571047A
Authority: US
Inventors: Harris William James
Original assignee: Individual
Current assignee: Individual
Priority date: 1944-01-05
Filing date: 1945-01-02
Publication date: 1947-03-04
Anticipated expiration: 1964-03-04

Description

March 4, 1947. w. J. HARRIS 2,416,751

ELECTRIC DIS CHARGE LAMP AND CONTROLLING MEANS THEREFOR Filed Jan. 2,1945

If 'm m 'P m Patented Mar. 4, 1947 OFFICE ELECTRIC DISCHARGE LAlVIP AND CON- TROLLING MEANS THEREFOR William James Harris, Newport, England Application January 2, 1945, Serial No. 571,047 In Great Britain January 5, 1944 1 Claim. 1

This invention relates to electric discharge lamps, fluorescent or otherwise, and controlling means therefor, of the type in which the lamp consists of an envelope containing gas such as mercury or sodium vapour r neon, with or without a proportion of argon, into the ends of which envelope are sealed two filamentary electrodes (these latter preferably having associated alkaline earth oxides) and in which the controlling means includes an automatically operating or other starting switch which when closed and upon the mains voltage being applied to the lamp, allows current to pass to the electrodes sufiicient to raise them to incandescence and to start ionisation of the gas in their immediate vicinity, and when opened effects the breaking of the circuit through the electrodes to permit other means remaining in the circuit to give a high voltage kick or surge through the gas between the electrodes suificient to start the discharge through the lamp, and has for its object so to devise the controlling means that such lamps can be started and run with efficiency on direct current, even of comparatively low voltage.

In general, in accordance with the invention, the lamp proper is made in any usual manner and the controlling means for the lamp comprises an electromagnetic inductance co-operating with a make-and-break device. This latter forms the starting switch of the control and is connected in the circuit in the position for such switch and comprises a movable armature or its equivalent at least partly of magnetic material, whilst the inductance is such and so mounted in the circuit that it forms the means for inducing the necessary high voltage when, with the lamp connected to the mains, the starting switch is opened. In addition, the inductance and armature are so juxtaposed that when the lamp is connected to the mains the magnetic flux of the inductance is adapted to attract the armature against resilient return means to effect the opening of the starting switch, the said flux being suiiicient at all times, even after starting, to maintain the said switch open. Further, the windings of the inductance'also act as a limiting device for the current consumed by the lamp.

Preferably, the main switch between the mains and the lamp circuit is of a one-direction rotary type so that the polarity of the electrodes is reversed upon successive lightings of the lamp, to eliminate defects due to electrophoresis.

In most cases and for convenience, the control is included in the structure of the lamp, for example in a. compartment at the back of a trough- 2 like or other hood or shade of the lamp, although it may be separate from the lamp.

It will be understood that when the lamp is not connected to the mains, the make-and-break device is held by the resilient return means so that it is closed, in other words the starting switch is closed, and the armature comes at the maximum distance from the adjacent end of the inductance. As a consequence, when the mains switch is next operated, current at mains voltage passes through the two filamentary electrodes, the inductance and the make-and-break device. The electrodes come to incandescence and start the ionisation oi the gas in their immediate vicinity. Also, the magnetic flux commences to attract the armature and this latter is moved thereby to break the contact of the starting switch. This causes the voltage surge and if the partial ionisation of the gas has been adequate, then this voltage surge is sufiicient to start the discharge of the lamp. The current continues to flow through the inductance and its magnetic flux keeps the armature of the starting switch in the open position.

Should, however, the preliminary heating by the electrodes be insufiicient, then upon the openin of the starting switch and after the consequent voltage surge no current will continue to flow through the inductance, and as a consequence the armature, not beingmagnetically attracted, will again be brought by the resilient return means to contact-making position. Thus, a trembling action may take place for a short period until the starting ionisation of the gas in the neighborhood of the electrodes is sufilcient for the induced high voltage consequent upon an opening of the starting switch, to start the discharge through the lamp.

Upon moving the main switch to switch off the lamp, the magnetic flux through the inductance ceases and the armature returns to the contact-making position, in other words the starting switch is closed ready for the next operation of the main switch, and so on. If this main switch is of the one-directional rotary type, then on the next operation the polarity of the electrodes will have been reversed.

In order that the invention may be better understood, it will now be described with refer- ,ence to the accompanying drawings which are given by way of example only and in which Fig, 1 is a somewhat diagrammatic cross sectional elevation of one form of electric discharge lamp and controltherefor constructed according to the invention, assembled as a unitary structure with a trough-like reflector and shade.

Fig. 2 is a plan of Fig. 1 with parts in section.

Fig. 3 is a diagram of a lamp and control in accordance with the invention when the lamp is not connected to the mains and with the starting switch in the closed position. I

Fig. 4 isa similar view to Fig. 3 but'showing the lamp connected to the mains and with the I starting switch in the open position.

The inductance to be employed in any case, that is to say the number of turns and the gauge of the insulated wire used, depends 'upon the voltage of the supply and the wattage of the lamp. In a particular case for a-fluor'e'scenttu- Joular lamp of standard dimensions, '60" long :and 1 diameter, rated at 80 watts toloperate at substantially 230 volts, the inductance comprises six coils. Each coil is a multi-layer coil with a hollow core of desired diameter and is made up from 3283 turns of 27 gauge insulated copper wire,

the outside dimensionsofthe coil being'substantia'lly 6" long and 1 diameter.- The complete "inductance is constituted by connecting the six coils in series and'arranging them end to end in :axial alignment.

" 'In 1 the drawings; is the electric discharge lamp of--standingdimensions with two-pin *bayonet end-capstoengage the equivalent sockets wot a trough'refiecton and shade 5 in anyusuala --man-ner. Theshade at its rear has a compart- --ment1 whioh'h'ouses an inductance formed'by ksixcoils 8 connected in series and arranged end to end in axial alignment as hereinbefore described. It also houses a casing 9-in which the =rnake-and-break or starting switch is-located- I The starting switch may take man forms. 'As

-.diagrammatically shownin Fig. 2, it comprises an armature formed from a stem H! and head I I "of magnetic material, the stem entering and be-si' ing adapted to slide in the hollow core of the first call 8 of theinductance.

The head II is kept pressed outwards by a spring I2. On the side of the head remote from the spring, this head has a contact I3 which in the closed position of then? -starting switch ,is in electrical connectionwith another contact l4 carried by a fixed conducting support IS the position of which preferably is adjustable, by a screw {6. The spring l2 keeps'the contacts l3 and M in electrical connection'wheni thelamp is not lit. Any suitable connections are 3 provided so that" the contacts'l3 and M are included in the oircuitof' the starting switch.

As shown in Figs. Sand 4, thestartingswitch is comprised by a pivoted armature ll having a con-n tact I8 and a head l9 ofmagnetic material. "The contact l8' co-operate's'with'another contact 2c barri'edby afixed support 2! the position of which preferably is adjustable'bya'screw22. The coning switch and remain in this position while the lamp is alight.

Except fertile-leaders to the main switches;

all "the leads' between the parts preferably are housed in thela'mp structure and are indicated by (exterior dotted lines imFig; 1 and more fully parf ticularised in the diagrams Figs. 3 and 4.- From 'tHGS latter il'vWill be" s li'thakfi one lead 24 iS'CO nected to one end of a filamentary electrode 26 the other end of this electrode being connected to the fixed contact 20 of the starting switch. The armature IT is a conductor or has an associated 5 conductor and this is connected to one end of the other electrode 21 the other end of this lastmentioned electrode being connected to one end 1 of the inductance, the other end of the inductance being connected to the other lead 24. The firstmentioned lead 24 is connected to a contact 28 "of the main switch 25 which is a one-direction rotary starting switch and the other lead 24 to the next contact 29 of the said switch. 3% and 3| are two further contacts of the starting switch to which themains 32 for D. C. current of de- Y sired voltage (230 volts in the particular case under consideration) are connected. The starting switch is symmetrically arranged and the movable conducting parts of the switch are such that the polarity of the

contacts

28 and 29 thereof is reversed .on successivea..operations .loi the switchto bringthe lamp into the .D. .C. circuit; f-Fig- 3' shows a switched-ofhpositionsL By movement'in the direction of the arrow. 33, theswitch is brought' into the posltionlshown inFig. 4 to switch the lamp intocircuith 'By. furthermovement of 45 inthe same .directionfrom the position'shown in'Flg. 4, thelamp is again switched 'offgand so on. As each successive switching-on reverses .the polarity of .thecontacts iii and 29 o'f-the switch, thepolarity of .the electrodes 25 and ZI also is reversed. 1

Inoperation it will be understood with. the partsin the position shown in Fig. 3, that imme- -diately the current isswitched on by. the switch a 25. a circuitis completed from..the. contact .28 of the switch 25 throughthe. filament 23,.through the make-and break contacts zii. and. i8, through the armature l1, through the other filament .21, cthrough the: inductanceucomprised by the .six coils 8 .in series, back touthe contact .29 ofthe switch. Thisicircuitiremains. completed. for an -extremelyshortperiod, during whichhowever. the filaments 26r-and'21 are brought toincandescence to start ionisation of the gas in their immediate vicinity. After this hasbeen efiectechthe mag- 1 netic fiuxi of the inductance attracts. the) armature H' t'oseparate the contacts. l8 and. 20*(or I3 w 14, Fig. 2). Thisiinduces a: very highs-voltso age by thecollapse of the magnetic fieldoi; the 1 inductance coils andenables the currenti to overcome theresistance of the gases'in the-lamp to start the-discharge between therelectrodes' :25 I and 21, which latter of course are nolonger incandescent.

I The parts are now in-sthe position shown in "Fig. l-and now that the gas path is a conductor (represented-by the dotted arrows" 3 i, Fig. 4), although -the connections from the filaments to the make-and break switch are no :longer in cir- --'cuit, the vsaidgas pathcomes in series-withthe inductance; coils -8 so that the-magnetism due to the current-passing through :thesaid coils keeps the armature ll attracted, maintaining the conta'cts l8 and 2ilapart Moreover, .the; coils tisalso actas a limiting 'device forthe current consumed by the lamp. I 1

is When the switch '25 is operated to switch the la'mp'from the circuit, then. the currentthrough thegas path is broken to-cause the cessation of the illumination andno current. passes-through the coils 8, which. enables the.spring;23 to return the armature' H: to the contact-making iposition readyfor'thelampxagainto be switched: on. I Electric 'r discharge: lamps, tparticularlyi o1 isthe fluorescent type, and controls therefor, in accordance with the invention, in practice have been found highly efiicient both from the aspect of consumption and illumination. After lighting, they run without flicker and no part of the lamp or the control has a temperature greater than slightly above room temperature. One such lamp of the standard type hereinbefore mentioned operating at 230 volts on D. C. with the control according to the invention, already has had a total illuminated life of over 5,000 hours, its electrical efllciency being unimpaired whilst its luminous efliciency has fallen ofi but slightly.

The exact arrangement of the inductance for any particular case will depend upon the voltage and wattage, and further upon the housing capacity for the coils. Generally, the lower the voltage the fewer the total windings of the inductance and/or the thicker the gauge of the wire used. It is preferred to make up the inductance in separate coils such as 8 in the drawings of desired numbers of turns and of a desired gauge wire and to utilise as many of such coils as is desired in any particular case.

In connection with the make-and-break device with its armature, whatever the exact construction, in some cases a damping device may be utilised of the diaphragm or other type and operating by air or other fluid. This acts to delay the opening of the starting switch for a short period, for example a few seconds and then allows a quick break to give the necessary voltage surge.

The system according to the invention enables fluorescent or other electric discharge lamps to be satisfactorily operated either from direct current mains, or batteries, or accumulators, in fact from any D. C. supply and at any convenient voltage. As a consequence of the satisfactory operation of such lamps from D. C. sources, it is possible to utilise these fluorescent or other electric discharge lamps not only in fixed positions such as in streets and buildings, but also in vehicles such for example as trains, trams, omnibuses, motor road vehicles generally, aircraft, shipping and otherwise.

The invention is not limited to the precise forms or details of construction herein described, as

6 these may be varied to suit particular requirements.

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

A starting and operating circuit for gaseous electric discharge lamps having two filamentary electrodes sealed into the envelope of the lamp, including an automatically operating starting switch which when closed and upon the supply voltage being applied to the lamp allows current to pass through the electrodes sufiicient to raise them to incandescence and to start ionisation of the gas in their immediate vicinity and when opened eifects the breaking of the circuit through the electrodes to permit an -electro-magnetic means remaining in the circuit to give a high voltage kick through the gas between the electrodes sufficient to start the discharge through the lamp, said starting switch being formed by a make-and-break device held closed when the lamp is unlit and including a movable armature, said electro-magnetic means being formed of an electro-rnagnetic inductance comprising a coil greater in length than in diameter and having a hollow core arranged with its axis parallel to the axis of the envelope of the lamp, the armature of the starting switch extending movably into said hollow core of the electro-magnetic inductance, the parts being so relatively positioned and constructed that the armature is subject to the magnetic flux produced by the energized inductance to cause the armature to be attracted'and drawn farther into the coil to open the starting switch, and spring means for returning the armature to a position in which the latter closes the starting switch upon de-energization of said inductance.

WILLIAM JAMES HARRIS.

REFERENCES CITED UNITED STATES PATENTS Name Date Babb Apr. 25, 1939 Number