Line source sweeping light fixture

A tubular lighting device encloses a plurality of LEDs and delivers light with uniformity, resembling the light delivered by a single linear light source. The tubular lighting device comprises a housing, a lighting chassis mounted on the housing, at least one circuit board with a plurality of LEDs mounted on the lighting chassis, each LED having a length A and two adjacent LEDs being separated by a distance L, a thin film mounted on the base and above the plurality of LEDs, the thin film being separated from the plurality of LEDs by a distance H, and a lens mounted on the lighting chassis and above the thin film.

RELATED APPLICATION

The present application is a non-provisional of U.S. Provisional Patent Application 62/786,360, for Line Source Sweeping Light Fixture, filed on Dec. 29, 2018, the specification of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to lighting technology, and more specifically, relates to lighting using LED as lighting source.

2. Description of the Related Art

The light emitting diode (LED) is becoming one of most common light sources and is used to replace many different light fixtures. When replacing traditional fluorescent light tubes, a plurality of LEDs are placed linearly on a circuit board mounted on a substrate. The physical arrangement of the LEDs resembles a fluorescent tube but the illumination effect is less than desired. The fluorescent tube emits light uniformly in all direction around the tube while the plurality of LEDs placed linearly on a circuit board emit directional light. The placement of the LEDs affects the illumination effect of these LEDs.

Furthermore, when the light from a light fixture with the plurality of LEDs is shone on a reflective surface, the individual light sources from the plurality of LEDs are readily noticed and cause a discomfort on human eye.

Therefore, there is a need for a light fixture using plurality of LEDs that provides a uniform light effect and it is to this improved light fixture the present invention is primarily directed to.

SUMMARY OF THE INVENTION

In one embodiment, the present invention is a tubular lighting device comprises a housing, a lighting chassis mounted on the housing, at least one circuit board with a plurality of LEDs mounted on the lighting chassis, each LED having a length A and two adjacent LEDs being separated by a distance L, a thin film mounted on the base and above the plurality of LEDs, the thin film being separated from the plurality of LEDs by a distance H, and a lens mounted on the lighting chassis and above the thin film. The light emitted from each LED passes through the thin film and forms an illumination cone, two adjacent illumination cones defines an overlapping cone, and the overlapping cone defines an overlapping angle θ. The relationship between the plurality of LEDs, the thin film, and the overlapping angle θ is defined by

The thin film preferably is an elliptical light diffusing film with a microstructure surface and the thin film can be either attached to the lens or separated from the lens. The housing comprises at least on side wall and at least one hook disposed away from the at least one side wall and the cover comprises at least one connecting skirt with a plurality of flanges; the connecting skirt is inserted between the at least one side wall and the hook.

The present system and methods are therefore advantageous as they enable identification of abnormal information access behaviors. Other advantages and features of the present invention will become apparent after review of the hereinafter set forth Brief Description of the Drawings, Detailed Description of the Invention, and the Claims.

DETAIL DESCRIPTION OF THE INVENTION

In this description, like numerals refer to like elements throughout the several views, and the articles “a” and “the” includes plural references, unless otherwise specified in the description. In the specification, “thin film” and “light diffusion film” are used interchangeably and “illumination cone” and “cone” are used interchangeably.

In an overview, the present invention enables a light fixture with a plurality of LED as light source to have a uniform lighting effect.FIG. 1illustrates a tubular LED lighting device100that can be used as replacement to fluorescent tubes.FIG. 2is a cross section view200of the tubular LED lighting device100andFIG. 7is an exploded view of the same tubular LED lighting device100. The tubular LED lighting device100has a housing212, a light chassis208mounted on the housing212, a circuit board214with a plurality of LEDs206mounted on the light chassis208along the length of the tubular LED lighting device100, reflector surfaces210placed on both side of the LEDs and along the length of the tubular LED lighting device100, a thin film204(aka light diffusion film) placed above the plurality of LEDs, and an asymmetric lens202. The light emitted from the plurality of LEDs passes through the thin film204and the asymmetric202is uniform and without the appearance of being shone from a plurality of discreet light sources.

FIG. 3illustrates an alternative embodiment300of a tubular LED lighting device200, in which there are two sets of LEDs placed under a cover302and these two sets of LEDs face away from each other. In this embodiment, the plurality of LEDs206on the circuit board310is mounted on the lighting chassis308. The thin film204is attached to the asymmetric lens202and placed above the LEDs206. In the asymmetric lens202, the lens can be divided into two parts304,306, each part has a unique radius R1, R2, different from each other. The effect of the asymmetric lens is to spread the light more evenly on to the cover302. The reflector surfaces210may be mounted around the plurality of LEDs206. In an alternative embodiment, the reflector surfaces210may be mounted on the circuit board310; the circuit board310, the plurality of LEDs206, and the reflector surfaces210form one single unit that slides into the lighting chassis308. The space between the thin film204, the LED206, and the reflectors210is considered to be the reflecting cavity.

FIG. 4is an alternative embodiment400of a tubular LED lighting device. In the embodiment400, the light from the plurality of LEDs206is shone directly on to the thin film204. The cover402is mounted on the lighting chassis412through a clip410on the cover402and a hook406on the lighting chassis408. There is also a plurality of flanges404on the connecting skirts408the cover402that engages to a side wall414of the lighting chassis412. The engagement of the connecting skirts408and the plurality of flanges404with the side wall414ensure tightness of the enclosure and prevents penetration of dust.

FIG. 5is an illustration500showing the illumination by the plurality of LEDs206through the thin film204. The thin film is an elliptical light diffusing film with a microstructure surface. When parallel light shines onto the microstructure surface, the light is diffused providing an appearance of a single linear lighting source instead of the plurality of LEDs. The microstructure of the thin film enables unidirectional diffusion and when the height of the reflective cavity is high enough, or the LED spacing is close enough, the thin film204functions as a normal diffusion film. Each LED shines a conical area and, because of the proximity of the LEDs, most of the thin film surface is covered by multiple conical areas.FIG. 8is an alternative embodiment of the thin film204, in which one surface has wave form while other surface is flat.

The tubular LED light fixture of the present invention emits light uniformly along its length and without the appearance of having multiple light sources and this is accomplished by spacing the adjacent LEDs and placing the thin film at a special distance above the LEDs.FIG. 6is an illustration600of the relationship between the elements of the tubular LED lighting fixture. Each LED has a length A (measured along the length of the tubular LED light fixture) and is separated at a distance L (measured between the center of the adjacent LEDs). The light emitted by a LED206forms generally an illumination cone β and two adjacent cones overlap. The overlapping cone has an angle θ. The thin film204is placed above the LEDs206at a distance H. The LEDs206are placed above the circuit board602. The relationship between the elements is expressed according to equation below.

The light-emitting surface of the plurality of LEDs should be narrower and its width should be similar to the length of the LED to maximize the scanning. Through the light distribution, the LED light-emitting area is enlarged, and a continuous light spot is formed on the surface of the lamp cover, that is, the dark area between the LED light-emitting points will disappear, and the light-emitting surface achieves a linear light source effect.

While the invention has been particularly shown and described with reference to a preferred embodiment thereof, it will be understood by those skilled in the art that various changes in form and detail may be made without departing from the spirit and scope of the present invention as set forth in the following claims. Furthermore, although elements of the invention may be described or claimed in the singular, the plural is contemplated unless limitation to the singular is explicitly stated. It is also understood that the features shown in different embodiments can be easily combined without departing from the spirit of the present invention.