US2979637A - Fluorescent lighting circuit - Google Patents

Description

April 11, 1961 G. E. WELNA 2,979,637

FLUORESCENT LIGHTING CIRCUIT Filed Aug. 17, 1959 1 i g 1 z I l [a 9. C. fi; I IV 500205 l I g g 15 i United States Patent 2,979,637 7 FLUORESCENT LIGHTING CIRCUIT George E. Welna, Chicago, .Ill., assiguor to Nathan Bromberg and Esther Bromberg, Chicago, 111., copartners 7 Filed Aug. 17, 1959, Ser. No. 834,286

3 Claims. (Cl. 315-84) The present invention relates generally to electrical lighting and more particularly to fluorescent lighting.

It has long been recognized that relatively low temperatures adversely affect the operation of fluorescent lamps. While many expedients have been utilized to obtain satisfactory operation of such lamps in low temperature environments, none of such prior expedients have been acceptable for use in locations where there exists a relatively high humidity in addition to a relatively low temperature. For example, such conditions of relatively low temperature and high humidity are commonly found in domestic refrigerators, freezers, ice boxes, coolers, cold rooms, and the like. As a result this otherwise eflicient and economical lighting has not been generally used in such applications. In the few instances where fluorescent lighting has been used in this general type of application elaborate means have been included to preclude exposure of the lamp and its immediately adjacent circuitry to such environmental operating conditions with the attendant increased cost and efliciency loss.

Accordingly, it is the general object of the present invention to provide improved fluorescent lighting intended primarilyfor utilization in environments of relatively high humidity and low temperature yet which permits utilization of conventional fluorescent lamps and receptacles and avoids necessity for special isolating fixtures, high voltage supply, and the like.

A more particular object is to provide fluorescent lighting of the foregoing general character including a lamp and a reactor in an improved circuit which not only effects proper lamp operation but which insures instant starting notwithstanding location in an adverse err. ironment. 7

The objects of the invention thus generally set forth together with other objects and ancillary advantages are attained by the construction and arrangement shown by way of illustration in the accompanying drawing which comprises a schematic circuit diagram.

While the invention is susceptible of various modifications and alternative constructions, a preferred embodiment is diagrammatically shown in the drawing and is herein described in detail. It is to be understood, however, that it is not thereby intended to limit the invention to the specific form disclosed. On the contrary it is intended to cover all modifications and alternative constructions falling within the spirit and-scope of the invention asexpressed in the appended claims.

In the field of fluorescent lighting it has been found impractical to use the low cost, pre-heat type of fluorescent lamps with conventional ballasts, or reactors, when the operator of the lamp is in a cold atmosphere of 50 F. or lower. Under these conditions starting of these lamps is erratic and, in general, performance is unsatisfactory. Pre-heat types of lamps as well as those of the so-called cold cathode variety have been used but only with special transformers which deliver a high voltage for starting the lamps. In addition to the fact that such transformers are relatively costly to manufacture, the use of a high voltage across the lamp terminals is.

especially undesirable where condensation can be expected to occur on the lamp and lamp holders or receptacles.

In accordance with the present invention there is provided an improved fluorescent lighting circuit which obviates the aforementioned objections, is particularly well-suited for use with conventional bi-pin, pre-heat types of fluorescent lamps, and is characterized by its extreme simplicity. Thus, the circuit is not only well generally designated by numeral 10. It includes a primary winding 12, and two secondary windings 14 and l These windings are'placed upon a con- 16, respectively. ventional magnetic core 18. Preferably the wire size and turns per layer are identical. The primary winding 12 may consist, for example, of twenty layers and each of the filament windings may consist of one layer of turns which will result, it has been found, in the proper impedance for each winding. Desirably the magnetic core 18 is formed of conventional laminations of E and I form arranged to provide a fixed air gap. In this exemplary form the primary winding 12 may consist of 1064 turns of No. 28 A.W.G. plain enameled wire, and

each of the secondary windings may consist of 56 turns of No. 28 A.W.G. plain enameled wire. Such a reactor has been found satisfactory for use with a conventional fluorescent lamp, such as that indicated at 20 in the drawing, in wattage sizes of from 4m 25 watts, single lamp operation from an AC. voltage source of to v volts.

ventional bi-pin pre-heat type and includes in each end thereof an identical electrode structure 22 including a coated filament 22a. The coated filaments 22a serve as sources of electrons to assist in ionizing the included gas, such as mercury vapor, within the tube whereby to provide a conductive path between the electrodes.

As shown in the drawing, the one end of the primary winding 12 is intended for continuous connection by way of a conductor 24 to one side of the AC. source. The other end of the primary winding 12 is connected directly to one end of the secondary winding 14. By way of conductors 26 and 28 the secondary winding 14 is connected across one of the filaments 22a of the electrode 22 at one end of the lamp 20.

The secondary winding 16 is similarly connected by way of conductors 30 and 32 across the filament 22a of the electrode 22 at the opposite end of the lamp 20. The conductor 32 as shown is intended for continuous connection to the other side of the AC. source. Interposed between adjacent ends of the secondary windings 14 and 16 is a switch 34. The switch 34 may be a simple single pole, single throw, switch having open and closed positions.

With the switch 34 at its open position it will be apparent that the primary winding 12 is placed in series with the lamp 2%) and across the AC. source by way of the conductors 24 and 32. In this condition the primary winding 12 functions in the manner of a conventional reactor-ballast in series with the lamp.

When the switch 34 is closed, the primary winding 12 Patented Apr. 11, 1961 As shown in the drawing, the lamp 20 is of the con,-

and32. In this condition of operation the lamp filaments 22a,. 22a, receive a small amount of. current from the secondarywindings 14 and 16by way of the conductors 26: and 28, and 30 and 32, respectively. As a result they are warmedto a low temperature and the lamp is conditioned for immediate starting as soon as the switch 34 is returned to open condition.

.When the: switch 34 is open, the primary winding again functions as a reactor-ballast in series with the lamp across the A.C. source. As soon as'the switch 34 is again closed, the voltage across the lamp is automatically reduced and the circuit restored so as to apply the small warming current to the filaments.

It.will be at once apparent that the circuit as hereinbefore described readily permits of incorporation in a domestic refrigerator for example. It requires only that the conductors 24 and 32 be permanently connected across the ordinary two-wire supply line to the device. A switch 34 in such an application will comprise the conventional door-operated single-pole two-position on-ofi' switch so arranged that the switch is in its closed or. on

position when the refrigerator door is closed and is inits off or open position when the door is open.

Thus, it will be apparent that fluorescent lighting embodying the teachings of the present invention permits otutilization readily and economically in environments of relatively low temperature and high humidity providing for such applications the advantages attendingthis type of lighting.

I claim as my invention: 1. In an enclosure having a door, a circuit for efiecting operation from an A.C. source of a fluorescent lamp of the-type incorporating spaced electrodes, saidcircuit comprising, in combination,- a reactor including a magnetic core, a primary winding and a pair of secondary windings upon said core, said reactor having one end of said priwindings respectively across the lamp electrodes, said' 4 switch in open position placing said primary winding in series circuit relation with the lamp across the A.C. source for ballasting the same for normal lighting operation, and said switch in closed position placing all of said windings in series circuit relation and across the source in which relation the lamp electrodes are maintained in preheated condition, ready to efiect 'instant lighting of the lamp upon operation of saidswitchintoopen-position.

' tively small number of turns, all of said windings. being 2. A circuit for efiecting operation fr'om'an A.C.

source of a fluorescent lamp of. the type' incorporating.

coated filaments, said'circuit comprising, incombination, a reactor having a magnetic core and including a pnmary winding and a pair of secondary windings disposed upon said core, means for connecting said secondary windings in shunt relation respectively with the lamp electrodes, a mechanically operated switch interposed between one end of each of said secondary windings, with the opposite endofone of saidsecondary windings connected to one disposed uponsaid core, said secondary windings being adapted for connection in shunt relation with the re-' spective ones of the lamp electrodes, one end ofsaidi primary winding being connected with one end of one of 'said secondary windings, the other end of said primary windingbeing continuously connected with one side of the A.C. source, one end of the other'secondary winding being continuously connected with theother side'of'the A.C. source, and' a mechanically operated'switch connecting the other ends of said secondary'windings for alternative open circuit or closed circuit connection between the windings.

References Cited in the file of this patent UNITED STATES PATENTS 2,507,101 7 Hall May 9,. 1950 FOREIGN PATENTS:

529,119 GreatBritain Nov. 14,1940

Great Britain Mar. 21', 1945

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