DOUBLE ENDED COMPACT FLUORESCENT LAMP

Abstract: A double ended fluorescent lamp (10) having a relatively large diameter outer envelope (12) contains an assembly (18) of small diameter phosphor coated tubes (20, 22, 24) having arc directing means (26, 28) located at the ends of the tubes. Only two electrodes (38, 40) are employed, located at opposite ends of the lamp. A sinusoidal arc path is defined through the tubes and has an arc length that is greater than the length of the lamp. In the embodiment illustrated, the arc length is approximately 3 times the length of the lamp.

Description: DOUBLE ENDED COMf > flCT FLUORLSCNT LMP TECliNICNL FIELD This invention relates to fluorescent lamps and more particularly to compact version of such lamps. BACKGROUND flRT Fluorescent lamps are known light sources valued for their relatively low cost, long life, and high efficacy (light out per unit of power consumption, usually expressed as lumens per watt; i.e., LPW). Such lamps generally comprise an elongated, hermetically sealed, glass Lube containing an electrode at either end and a quantity of mercury and a starting gas, e.g., argon. The inside surface of the tube is coated with a phosphor which transduces ultraviolet radiation into uisible light. The ultraviolet radiation is derived from the mercury arc produced between the electrodes when the lanp is operating. Since the efficacy of fluorescent lamps (other things being equal) is a function of the arc length, i.e., lumens per watt, ratings of long arc length lamps are greater than the LPW ratings of short arc length lamps, it is important to provide as long an arc length as possible within a small uolume to produce an efficient lamp. Much effort has been devoted to this end in an attempt to provide a single ended fluorescent lamp suitable as a replacement for incandescent types. See, for example, U.S. Patent Nos. 4,288,239; 4,191,907; 4,142,125; 4,347,460; and Serial Nos. 4-81,204; 481,203; and 481,230 filed april 1, 1983 and assigned to the assignee of the present inuention. lloweuer, it would be an advance in the art to provide a double ended fluorescent lamp having an arc length greater than the linear length of the enuelope. DISCLOSURE OF THE INVENTION It is, therefore, an object of the invention to obviate the disbduantages of ttie prior art. It is another object of tl,c invention lo provide . n enhanced fluorescent lamp. Yet another object of the invention is an improved double ended fluorescent lamp having increased arc length. These objects are acconplished, in one aspect of the invention, by the provision of a fluorescent lamp conprised of an outer envelope having a given diameter and first and second opposed ends. An asseibly is positioned within the envelope, the assembly colnprising a plurality of phosphor coated tubes each hauing a diameter less than the diameter of the envelope. Arc directing means are associated with the ends of the tubes to form a continuous arc path therethrough. Electrodes are located at the ends of the envelope to form an arc path. An arc generating and sustaining atmoshpere is provided within the envelope and means are provided for slaking electrical connection to the electrodes. There is thus provided a double ended lamp hauing a long arc length within a much shorter linear distance. It is simple and economical to build and allows the efficacy of fluorescent technology to be employed in places whcre it would otherwise be inconvenient. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded, perspectiue view of an embodiment of the inuention; and FIG. 2 is a longitudinal sectional view thereof. BEST tM,ODE FOR CARRYING OUT THE INVENJ0 For a better understanding of the present invention, togcther with other and further objects, advantages and capabilities thereof, reference is made to the following disclosure and appended claims taken in conjunction with the above-described drawings. Referring now to the drawings with greater particularity, there is shown in FIG. 1 a compact fluorescent lamp 10 having an outer, light-transmissive, glass envelope 12 having a given diameter, say 1 1/2 inches, and a first end 14 and a second end 16, the ends being opposed to one another. Rs assembly 18 is positioned within envelope 12 and coinprises a plurality of phosphor coated tubes 20, 22 and 24 each having a diareter less than the diarieter of envelope 12. In a preferred enbodiment this latter diameter can be 5/8 inches. R first arc directing means 26 is associated with one end of the tubes and a second arc directing means 28 is associated with the second ends of the tubes. The arc directing means 26 and 28 comprise, respectively, base members 30 and 32 each provided with apertures for receiving the tubes, and arc directors 34 and 36, each in the form of a rectangular disk. The arc directing means 26 and 28 can take various forms and be formed of various materials. Suitable enbodiments are shown in the above-mentioned applications S.N. 481,204; 481,203; and 481,230; filed April 1, 1983 and assigned to the assignee of this application, and the teachings therein are herein incorporated by reference Rods 37 are affixed to and extend between the base members to hold the assembly together. fl first electrode 38 is located in first end 14 of lalnp 10 at a first end of the arc path and a second electrode 40 is located in second end 16 at a second enS of the arc path. The electrodes 38 and 40 can be conventional fluorescent lamp electrodes which can be supported between lead-in wires 42 which are held within a press 44 of flares 46. Envelope 12, which is hermetically sealed, contairs an arc generating and sustaining atmosphere of, e.g., abut 20mg of mercury and argon at a pressure of about 3 tour. This atmosphere also permeates the tubes 20, 22 and 21. The interiors of tubes 20, 22 and 24 are coated with a suitable phosphor. Electrical connection Ineans 48 are providcd for naking electrical connection to the electrodes 38 and 40 aid can be in the form of pins 50 in bases 52, as is convercional. First and second assembly positioning means 54 and 56 are associated with the ends of the outer envelope 12 and can comprise spring wires having one end affixed ii the press and the free end thereof in contact with an src directing means to center the assembly 18 within nuelope 12 and align the same with respect to the electro es. In a preferred embodiment of the invention t!3 electrodes 38 and 40 can be at least partially s rrounded by a disintegration shield 58 and 60 respectiue7 Further, each of the disintegration shields can laze a getter mounted thereon. While the electrodes 38 and 40 can be mound within the ends of the tubes, this condition is not r.cessary and, in the preferred embodiment, the electros are positioned outside the tubes as shown in the rawings. When this latter condition obtains, it is necessary that the edges 31 and 33 of base members 30 and 32 fit tightly against the inside surface of envelope 12 to prevent the arc from operating directly between electrodes 38 and 40. in operation the necessary arc will originate at one electrode, say 38, and progress up tube 20, across arc director 36, down tube 24, across arc director 34 and up tube 22 to terminate at electrode 40. It is to be understood that the terms "up," "down" and "across" refer to directions corrcspondjng to the drawings as normally viewed, and that these terms will vary depending upon the orientation of the lamp 10. There is thus provided a double-ended fluorescent lamp hauing a long arc length in a relatively short linear length. n11 of the components of the lamp can be fabricated from readily available materials, thus avoiding the use of complex and custoin Inade partitions, baffles, etc., and greatly reducing the cost. The employment of the straight tubes and arc directors, which receive the tubes in an arc tight but atmosphere permeable manner, eliminates difficult tube bending operations and multiple hermetic seals, thus further reducing the cost. Since each of the internal tubes is a separate entity, it is also possible to vary the light output of the lamp by coating each tube with a different phosphor. While there have been shown and described what are at present considered to be the preferred embodiments of the inuention, it will be apparent to those skilled in the art that various changes and modifications can be made herein without departing from the scope of the invention as defined by the appended claims.

Claims: CL.lrS 1. n fluorescent 1amp comprising: an outer enuelope hauing a given diameter and first and second opposed ends; and asscinbly within said cnuelope comprising a plurality of phosphor coated tubes each having a diameter less than said given diameter; arc directing means associated with the ends of said tubes to form a continuous arc path thertrouh; a first electrode located at said first end of said outer envelope and at a first end of said arc path; a second electrode located at said second end of said outer envelope and a second end of said arc path; an arc generating and sustaining atmosphere within said outer envelope and said tubes; and first electrical connection means at said first end of said outer envelope for making electrical connection to said first electrode, and second electrical connection means at said second end of said outer envelope for making electrical connection to said second electrode. 2. n lamp as in Claim 1 wherein first and second assembly positioning means are associated, respectively, with said first and second ends of said outer envelope. 3. Q lamp as in Claim 2 wherein said first and second assembly positioning means comprise a spring wire having a first end fixed in an end of said outer envelope and a second end in contact with said assembly. 4. n lamp as in Claim I wherein said first and second electrodes are mounted between lead-in wire supports, said supports being sealed into and projecting outside of said ends. 5. fl lamp as in Claim 2 wherein said electrodes are at least partially surrounded by a disintegration shield. 6. A lamp as in Claim S wherein said disintegration shield mounts a getter.

Inventors: MAYA, JAKOB, THIBAULT, PAUL A.
Applicants: GTE PRODUCTS CORPORATION
Application year: 1984
Main classification: H01J61
IPC codes: H01J61