US2272274A - Electric discharge lamp - Google Patents

Description

Feb. 10, I942. I A. F. PIEPER ELECTRIC DISCHARGE LAM? Filed June 5, 1940 INVENTOR.

Patented Feb. 10,

UNITED STATES PATENT OFFICE f I 2,212,274 I ELECTRIC DISCHARGE LAMP Alphonse F. Pieper, Brighton, N. Y.

Application June 5, 1940, Serial No. 338,965 (of. 240-1) 2. Claims.

This invention relates to an electric discharge lamp, with reference more particularly to a lamp of the general type including an elongated translucent container or bulb having an electrode at each end thereof, enabling the flow of current through a vacuum, gas, or vapor, from one electrode to the other, and it has for its object to eliminate, or reduce to an unobjectionable minimum, the highlyundesirable effect that results. from the flicker that is present when low frequency alternating currentsare used.

In lamps of this general character, particularly to conventional fluorescent bulbs, the effect from flicker is seriously objectionable with alternating current up to fifty cycles and intolerable at twenty-five cycles, due to the making and breaking of the circuit at the electrodes as the direction of current flow is reversed, the flicker being increasingly noticeable as the cycles are decreased in number, and it has been discovered that the flicker is most apparent at the electrode point where the circuit is opened and closed, and barely noticeable at the central part of the tube or container between the electrodes.

In fluorescent bulbs as generally constructed, the electrodes are located at the ends of a glass tube, in which case the flicker which reaches its an elongated container of translucent material,

thereto one practical embodiment of the invention;-

Fig. 2 is a sectional view taken longitudinally;

Fig. 3 is an end elevation;

Fig. 4 is a transverse sectional view showing a modified form of the invention, applied to a lamp supported in a housing with a reflecting surface, and

Fig. 5 is a same.

Referring more particularly to the drawing, in which like reference numerals refer to the same parts throughout the several views, 'I designates longitudinal sectional view of the consisting'in the structure'illustrated 'of a glass tube that is sealed at both ends, and provided with a metallic closure 2 at each end that has a periphery of slightly reduced diameter in comparison with the periphery of the glass tube,

while 3 designates the usual socket engaging contacts and 4 are the electrodes connected by a filament 5 that functions to heat the mercury maximum intensity at the points of the electrodes, is observable directly through'the portions of the glass tube directly surrounding the electrodes, and it is a purpose of this invention to obviate or lessen the flicker effect on the eye of; an observer by arranging an opaque light ob-! structing means between the electrodes and the observer, or around the points at which the circuit is opened and closed and maximum flicker occurs, leaving a light emitting area that is restricted to a zone located between the electrodes and not surrounding them, so that it is im-- pointed out in the claims following the speciflcation.

In the drawing: Fig. 1 is a view in side elevation of a convenand create the necessary vapor for conducting the flowof currentfrom an electrode at one end of thetube to an electrode at the opposite end of the tube, as usual in this type of lamp.

Owing to the cyclic variations of the current, there is aresulting flicker in the light which is more pronounced with currents of lower frequency, and is observable more noticeably in the immediate vicinity of the electrodes 4 where the circuit is broken as the current reverses. In prior lamps of this type, the light immediately around the electrodes 4 is observable from outside the glass tube 'or container and is emitted laterally through the glass tube, and it has been discovered that by concealing the electrodes or by placing a light obstructing means around the electrodes so that light cannot pass from immediately around the electrodes laterally through the glass tube, the flicker effect is almost entirely eliminated, or greatly reduced so that it is of negligible consequence.

This-result may be attained in any suitable way i tional typeof fluorescent bulb, showing applied 55 outer surface of the glass tube and aportion I or reduced diameter that embraces the reduced periphery of the metal closure 2. The sleeve or guard may be of metal or any other suitable material. and the portion 6 extends endwise of the tube i somewhat beyond the electrodes 4, as shown. preferably for a distance of approximately one-quarter oi an inch beyond the innermost extremity of the electrodes I or filament I, although this distance may vary slightly more or less as determined by the requirements of a lamp of any particular size.

.With the light obstructing sleev in position, it is impossible for light to pass directly from around the electrodes laterally through the glass tube i, and it is also impossible for an observer to see the light in the immediate vicinity of the contacts t, owing to the obstruction of the sleeve inter in such path, and consequently the flicker which occurs to a maximum extent at the contacts 4 cannot be observed.

In Figs. 4 and 5 is shown a modified arrangement applicable to constructions in which a iemp and an opening I! through which the lamp is inserted into its socket. i3 designates a wall or flange extending laterally from the base of the partition ii toward the adjacent end of the tube and acting to conceal from view the end portion of the tube behind which the electrodes are located. With this arrangement, the point of maximum flicker at the end of the tube is shut oi! from any eflect on the reflecting surface by the partition II, and from view of the observer by the wall II. The device may be held in place by any suitable instrumentalities, as for instance, by lugs it formed on the ends of the flange or wall It and adapted to be bent over the adjacent edges of the housing.

With such an arrangement, practically no flicker is noticeable through the central portion of the glass tube or the area between the light obstructing sleeves, and it is possible to use currents of sixty cycles, flity cycles. and even down to forty-five cycles without noticeable or sen-- ously objectionable flicker being observed, which has not been the case with the lamps heretofore employed where the electrodes are located within the glass tube and no guard or obstruction exists between the electrodes and the wall of the glass tube.

It. will be understood that the invention may be used in any lamp or fixture on one or more electric discharge bulbs wherever they may be employed. The invention may be carried out in ways other than those specifically disclosed herein, without departing from its essential principle, and this application is intended to cover any changes or modifications that may come within the purposes of the improvement or the scope of the following claims.

I claim:

1. The combination with an electric discharge lamp comprising an elongated translucent hollow container having an electrode at each end. thereof, of a transversely curved housing within which said lamp is supported, of opaque light obstructing means including a partition having a curved edge conforming to said curved housing and an opening to receive the lamp, said partition having a lateral wall at its base extending toward the adjacent end of the housing and overlying and concealing from view the end portion of the lamp beyond the partition.

2. The combination with an electric discharge lamp comprising an elongated translucent hollow container having an electrode at each end thereof, of a tranversely curved housing within which said lamp is supported, said housing being located above and extending downwardly on both sides of said container, opaque light-obstructing means including a partition located transversely of said housing and having a curved upper edge coniorrning to the inner surface of the housing,

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