Linear light fixture with diffuser

A light fixture is provided that includes a plurality of light emitting sources, such as e.g., LEDs, that are arranged along a longitudinal direction. A heat sink provides a support structure for the lights while also assisting with the dissipation of heat. A diffuser covers the light emitting sources and is also supported by the heat sink. One or more optical elements such as e.g., a reflector or internally reflecting lens may be used to help direct light rays from the light emitting sources. Certain features may be added at the ends of the light fixture for mounting upon a surface and/or for further controlling the direction of light rays projecting from the light fixture. The light fixture is suitable for a variety of applications including e.g., the illumination of products displayed on shelving for consumer viewing.

FIELD OF THE INVENTION

The subject matter of the present disclosure relates generally to a light fixture, and more particularly, to a light fixture having multiple light sources arranged in a linear or substantially linear manner.

BACKGROUND OF THE INVENTION

The illumination of items placed on a shelf or series of shelves presents certain challenges. Depending on the location of the light source, one shelf may block light from illuminating another shelf. Similarly, if a light is placed to one side, large items closest to the light may block light from illuminating other items on the same shelf.

Aesthetics can also be a concern particularly when attempting to optimize the positioning of the light source to address the above-mentioned illumination issues. For example, in a commercial setting where the items being displayed are e.g., consumer products, it is desirable to properly illuminate the consumer products without blocking the consumer's view or detracting from the presentation of the products. Additionally, variables such as the color and intensity of the lighting can be particularly important.

The use of light sources such as light emitting diodes, halogen bulbs, and others can present additional issues. For example, certain types of light sources can generate significant amounts of heat. This heat must be properly dissipated to e.g., avoid damaging the light fixture or improperly heating surfaces near the light fixture. If the application involves an environment where moisture may be present, such as e.g., a refrigerated display case, it may also be necessary to protect the light sources and/or associated electronics from exposure to such moisture.

Accordingly, a light fixture that can provide light from a linear source—i.e. a source where one or more light sources are aligned substantially along a longitudinal direction—would be particularly useful for certain applications. For example, such an arrangement could be used to provide lighting for items placed along a shelf or series of shelves. Such a light fixture that can also be used to provide e.g., the desired color and intensity of light would also be beneficial. Additionally, such a light fixture that can also be provided with features for varying the direction of the light would also be useful.

BRIEF DESCRIPTION OF THE INVENTION

The present invention provides a light fixture that includes a plurality of light emitting sources, such as e.g., LEDs, which may be arranged along a longitudinal direction. At least one heat sink provides a support structure for the light emitting sources while also assisting with the dissipation of heat. A diffuser covers the light emitting sources and is also supported by the heat sink. One or more optical elements such as e.g., a reflector or internally reflecting lens, may be used to help direct light rays from the light emitting sources. Certain features may be added at the ends of the light fixture for mounting upon a surface and/or for further controlling the direction of light rays projecting from the light fixture. The light fixture may be suitable for a variety of applications including e.g., the illumination of products displayed on shelving for consumer viewing. Additional aspects and advantages of the invention will be set forth in part in the following description, or may be apparent from the description, or may be learned through practice of the invention.

In one exemplary embodiment, the present invention provides a light fixture that includes at least one heat sink defining a longitudinal direction. At least one circuit board is attached to the heat sink. A plurality of light emitting sources are mounted to the at least one circuit board. The light emitting sources are spaced apart from each other and may be arranged along the longitudinal direction. A diffuser extends along the longitudinal direction and is attached to the heat sink. The diffuser covers the light emitting sources.

The use of the same or similar reference numerals in the figures indicates the same or similar features.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1 and 2provide a perspective view of an exemplary embodiment of a light fixture100of the present invention. A diffuser102is shown in position inFIG. 1while inFIG. 2diffuser102has been removed to reveal other components.FIG. 3provides close-up view of a first end104of fixture100.

Light fixture100includes a heat sink112that extends along longitudinal direction L between first end104and a second end106. Each end104and106includes a bracket108and110, respectively. Brackets108and110may be used to mount fixture100to a surface. Apertures114in each bracket108and110may be used along with fasteners for such mounting. Other features may be used for mounting light fixture100as well. By way of example, light fixture100could be mounted at the top and/or bottom of a refrigerated display case and used to illuminate products on shelves in the case. Light fixture100may be used in other applications as well.

Fixture100includes a plurality of light emitting sources116spaced apart from each other and arranged along longitudinal direction L as shown. Each light emitting sources116may be e.g., one or more light emitting diodes (LEDs). The density and number of LEDs along longitudinal direction L can be determined based on e.g., the application intended for fixture100. As shown inFIG. 2, light emitting sources116are positioned in a straight-line manner along the longitudinal direction. However, it should be understood that it is within the scope of the present invention for light sources116to be arranged in other manners, e.g., arranged longitudinally but not necessarily along a straight-line as shown inFIG. 2, or arranged laterally.

For this exemplary embodiment, a reflector118is provided that also extends along longitudinal direction L. Reflector118defines a plurality of cavities (or recesses)120that are also spaced apart and positioned along longitudinal direction L. More particularly, each cavity120is positioned around or otherwise contains at least one of the light emitting sources116and includes one or more light reflecting surfaces122and124for reflecting light away from light fixture100. By way of example, reflector118could be constructed from a metallized plastic so as to provide light reflective surfaces122and124. Light reflected from surfaces122and124passes through diffuser102. For this exemplary embodiment, diffuser102is constructed from a material of uniform thickness that helps control e.g., the color and/or distribution of the light.

FIG. 4provides cross-sectional view of first end104whileFIG. 5provides a perspective view of first end104with a cap134in place. Reflector118is mounted to a circuit board such as e.g., a fiberglass reinforced printed circuit board126. Reflector118can be attached using e.g., fasteners132. Other fastening mechanisms may also be used. For example, reflector118could be manufactured with pegs that provide an interference fit with holes or openings in circuit board126.

Circuit board126also extends along longitudinal direction L and is attached to heat sink112. By way of example, circuit board126could be provided with fasteners or pegs that extend into a slot128provided by heat sink112and positioned at the bottom of circuit board126. Heat sink112is constructed from one or materials that help dissipate heat created by light emitting sources116. Heat sink112also provides the structure or frame for light fixture100. By way of example, heat sink112could be constructed from anodized aluminum. For this exemplary embodiment, heat sink112is configured to resist collecting dirt and debris, to be readily cleanable by e.g., wiping, and still have substantial surface area for convective cooling.

Ends104and106each include apertures130that are oriented along longitudinal direction L. Apertures130are configured for the receipt of fasteners132that extend through apertures143(FIG. 6) in cap134to secure cap134onto end104. As shown inFIG. 5, cap134includes a peg136that extends along longitudinal direction L. Peg136is rotatably received into an aperture140defined by bracket108as shown inFIG. 6. A similar construction is used for a cap (not shown) positioned on second end106with bracket110. As such, after mounting brackets108and110, light fixture100can be rotated in the direction desired as the pegs at first end104and106rotate within brackets108and110. A fastener such as a set screw can be inserted into aperture138(FIG. 3) to apply force against peg136and fix the rotational position of light fixture100. A metal insert can be provided that is either heat-staked, ultra-sonically welded, or molded-in to allow such set screw or thumb screw.

Returning toFIG. 4, an exemplary technique for mounting diffuser102to heat sink112is shown. Heat sink112includes a pair of grooves150and152positioned on opposite sides of reflector118and the plurality of light emitting sources116. Grooves150and152extend along longitudinal direction L. Diffuser102may include a pair of opposing longitudinal edges154and156that are received in a complementary manner into grooves150and152. Diffuser102provides a spring-like force that urges edges154and156into grooves150and152to secure the attachment of diffuser102.

FIG. 7illustrates another exemplary technique for mounting diffuser102to heat sink112. More specifically, for the exemplary embodiment ofFIG. 7, heat sink112includes a pair of ribs142and144positioned on opposite sides and extending along longitudinal direction L. Ribs142and144project outwardly or face away from each other as well as light emitting sources116. Diffuser102includes a pair of grooves146and148positioned on opposite sides of diffuser102and also extending along longitudinal direction L. As shown, ribs142and144are received in a complementary manner into grooves146and148, respectively, to secure diffuser102into position.

FIG. 8provides a close up of a cavity120at first end104of light fixture100. Cavity120includes a first pair of light reflective surfaces122positioned in an opposing manner about light emitting source116. Cavity120also includes a second pair of light reflective surfaces124positioned in an opposing manner along with the first pair of light reflective surfaces122about light emitting source116.FIG. 9provides a cross-sectional view of light fixture100taken along a plane parallel to circuit board126and at a position above light emitting source116. As shown, the first pair of light reflective surfaces122having a first parabolic shape, while the second pair of light reflective surfaces124have a second parabolic shape different than the first parabolic shape. The shapes of surfaces122and124are configured as such to help direct light rays emitted from source116. In other exemplary embodiments of light fixture100, other shapes may be used for surfaces122and124in addition to that which is shown including e.g., non-parabolic shapes.

FIG. 10illustrates an end view of another exemplary embodiment of a light fixture100of the present invention (mounting features have been removed for purposes of illustrating interior components). Unlike the previously described embodiments, the light fixture100shown inFIG. 10does not include a reflector. In addition,FIG. 10illustrates another exemplary technique for mounting diffuser102to heat sink112. More specifically, for the exemplary embodiment ofFIG. 7, heat sink112includes a pair of ribs158and160positioned on opposite sides and extending along longitudinal direction L. Ribs158and160project inwardly or face towards each other as well as light emitting sources116. Diffuser102includes a pair of grooves162and164positioned on opposite sides of diffuser102and also extending along longitudinal direction L. As shown, ribs158and160are received in a complementary manner into grooves162and164, respectively, to secure diffuser102into position.

FIG. 11is a cross-sectional, end view of another exemplary light fixture100of the present invention. Unlike previous embodiments, the embodiment ofFIG. 11includes an optical element or lens166. Referring now toFIGS. 11,12, and13, lens166extends along longitudinal direction L and is positioned directly over the plurality of light emitting sources116, which are received into a channel176defined by the inside surface178of lens166. By way of example, lens166is provided with a pair of projecting inserts168and170that are received into circuit board126to secure lens166using an interference fit. Other features may be used to secure lens166as well.

Lens166includes a pair of internally reflecting surfaces172and174. For this exemplary embodiment, surfaces172and174may be arcuate in shape (and each may provide an external surface that is convex) within a plane that is orthogonal to longitudinal direction L as shown inFIG. 12. As such, some of the light rays from light sources116will enter lens166through inside surface178, reflect off of surfaces172and174, and exit lens166through outer surface180. Other shapes for surfaces172,174,178, and180may also be used in an effort to direct light rays from light emitting sources116away from light fixture100. By way of example, lens166can be manufactured from a polycarbonate or an acrylic material. Lens166may be constructed in a variety of lengths to cover one or several light emitting sources116.

Light fixture100can be constructed in a modular manner to help simplify manufacture. For example, referring toFIG. 2, a series of modules182can be installed on a heat sink112that is cut to the desired length. For example, heat sink112may be cut to a length of four feet to accept four modules182, each constructed at a one foot length. In turn, each module182could individually include e.g., a reflector118or lens166, circuit board126, and one or more light emitting sources116. Modules182can be connected electrically using e.g., connector184with wire slots188(FIG. 7), mating pin connections186(FIG. 9), or other connection mechanisms positioned at the ends of modules182.

It should be understood that for each exemplary embodiment, diffuser102may be constructed with a non-uniform shape and thickness so as to assist in directing light where desired. Additionally, the shape of e.g., diffuser102and either reflector118or lens166can be used together to minimize color separation. For example, lens166can be used to focus the light to increase flux density on the target plane while the diffuser102can un-focus the light slightly to remove color separation issues.