WO2011137361A1

WO2011137361A1 - A sealed structure of led road/street light

Info

Publication number: WO2011137361A1
Application number: PCT/US2011/034597
Authority: WO
Inventors: Heng FANG; Xiaoming Zheng
Original assignee: UNIFLUX LED Inc
Current assignee: UNIFLUX LED Inc
Priority date: 2010-04-30
Filing date: 2011-04-29
Publication date: 2011-11-03
Anticipated expiration: 2012-10-30

Abstract

A sealed lighting device for encapsulating LEDs. The lighting device includes a base and a pair of sidewalls extending perpendicularly from two opposite edges of a first face of the base; the sidewalls along with the base defines a recess. An LED module is mounted on the first face of the base. In addition, a sealant extends upwardly along the edges of the first face such that sealant is in contact with an inner surface of the sidewalls. The lighting device also includes a protective plate covering the recess such that edges of the protective plate are in contact with the sealant.

Description

A SEALED STRUCTURE OF LED ROAD/STREET LIGHT

TECHNICAL FIELD

[0001] The present disclosure relates generally to lighting devices, and more particularly to light emitting diode (LED) lighting devices.

BACKGROUND

[0002] Light emitting diodes (LEDs) are increasingly used these days to replace conventional lighting devices. Because of their small size, low power consumption, and long life, LEDs are applied as lamps or light sources to various display applications. Generally, when the LEDs are used outdoors for illumination, the LEDs are susceptible to damage, which can be caused by rain, snow, dust or other foreign articles.

[0003] To protect LEDs from environmental damage, LEDs are typically sealed in a casing. Conventionally, an LED lighting device includes one or more LEDs encapsulated between an outer case and a transparent cover. In addition, seal strips along with pressure rings are applied along the edges of the outer case and the transparent cover to seal the LEDs. But, as seal strips deteriorate over time, they do not provide complete sealing, limiting efficiency and lifetime of LEDs.

[0004] Therefore, with LEDs becoming increasingly competitive with other light sources for outdoor use and in environments with high moisture or dust contents, there is an apparent need for a cost effective method and apparatus for protecting these devices from undesired conditions.

SUMMARY

[0005] Embodiments of the present disclosure are directed to sealed lighting devices.

One such embodiment describes a lighting device includes a base and a pair of sidewalls extending perpendicularly from two opposite edges of a first face of the base. The sidewalls along with the base define a recess. An LED module is mounted on the first face of the base within the recess. In addition, a sealant extends upwardly along the edges of the first face such that sealant is in contact with an inner surface of the sidewalls. The lighting device also includes a protective plate covering the recess such that edges of the protective plate are in contact with the sealant.

[0006] Another embodiment of the present disclosure describes a sealed lighting device.

The lighting device comprises a base having a first face, a second face and a pair of sidewalls extending perpendicularly from two opposite edges of a first face of the base. The sidewalls along with the base define a recess. An LED module and an outer case are mounted on the first face and second face of the base, respectively. In addition, a sealant extends upwardly along the edges of the first face such that sealant is in contact with an inner surface of the sidewalls. The upper end of the sealant includes a step section. The lighting device also includes a protective plate covering the recess such that edges of the protective plate are in contact with the step section on the sealant. Further, conductive wires, connected to the LED module, extend out from the device through the sealant.

[0007] These and other aspects, and features of the present disclosure will become apparent from the following detailed written description of the preferred embodiments and aspects taken in conjunction with the following drawings, although variations and modifications thereto may be effected without departing from the spirit and scope of the novel concepts of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The accompanying drawings illustrate one or more embodiments and/or aspects of the disclosure and, together with the written description, serve to explain the principles of the disclosure. Wherever possible, the same reference numbers are used throughout the drawings to refer to the same or like elements of an embodiment. The drawings are illustrative in nature and are not necessarily drawn to scale.

[0009] FIG. 1 is a top view of a lighting device according to embodiments of the present disclosure.

[0010] FIG.2 is a sectional view of the lighting device illustrated in FIG. 1 taken along plane A-A' . DETAILED DESCRIPTION

[0011] To promote an understanding of the principles of the present disclosure, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will, nevertheless, be understood that no limitation of the scope of the disclosure is thereby intended; any alterations and further modifications of the described or illustrated embodiments and any further applications of the principles of the disclosure as illustrated therein are contemplated as would normally occur to one skilled in the art to which the disclosure relates. All limitations of scope should be determined in accordance with and as expressed in the claims.

[0012] As described here, the terms "bottom" and "top" imply the bottom and top portions of the described element as illustrated in the figures only. These terms do not refer to the bottom and top positions of the actual lighting device. If the device is inverted, these terms may be interchangeably used.

Overview

[0013] Embodiments of the present disclosure describe a sealed structure for LED lighting device. The lighting device includes a base having sidewalls defining a recess, one or more LEDs mounted on the base, and a protective plate covering the recess. A sealant, applied along the edges of the base, attaches the protective plate to the sidewalls. In addition, the sealant also covers the gap between the base and the protective plate to form a completely sealed enclosure for the LEDs. The sealant prevents undesired elements, such as moisture and dust, from entering the enclosure. In addition, power is supplied to the LEDs through conductive wires that extend out from the enclosure through the sealant.

Exemplary Embodiments

[0014] FIG. 1 and FIG. 2 illustrate an exemplary lighting device 100 that provides a sealed housing unit for light emitting elements. FIG. 1 is a top view of the lighting device 100 and FIG. 2 is a cross-sectional view of the lighting device 100 (FIG. 1) taken along a plan A-A' . The lighting device 100 includes multiple LED modules 102 mounted on one face of a base 104, and a protective plate 106 covering the base 104 to encapsulate the LED modules 102 using a sealant 108. The device 100 also includes an outer case 110 connected to the other face of the base 104. Further, one or more desiccants 112 are disposed within the sealed lighting device 100.

[0015] As shown in FIG. 2, the base 104 includes a main body 114 and a pair of sidewalls 116 extending perpendicularly from the main body 114. The main body 114 may be a rectangular plate having a mounting face 118 and an external face 120. The mounting face 118 provides a surface for mounting the LED modules 102, and the external face 120 is connected to the outer case 110 that allows dissipation of heat from the LED modules 102. The base 104 may be manufactured using any suitable thermally conductive material such as a metal (copper, aluminum, etc) that allow dissipation of heat from the LEDs to the outer case 110.

[0016] The sidewalls 116 may be rectangular plates extending perpendicularly from a pair of opposite edges on the main body 114. The sidewalls 116 extend upwardly from the mounting face 118 defining a recess 122 on the base 104. As shown, the main body 114 along with the sidewalls 116 defines a U-shaped base structure. The sidewalls 116 may be either part of the base 104 or may be detachably connected to the main body 114.

[0017] The protective plate 106 may be a transparent or semi-transparent plate, such as a glass plate, that allow light generated by the LED module 102 to pass through. The plate 106 may be a rectangular plate having dimensions similar to the recess 122 on the base 104 in order to cover the recess 122 and encapsulate the LED modules 102. Those skilled in the art will understand that the plate 106 may include any suitable dimension such that the edges of the plate 106 fix onto the sidewalls 116 of the base 104 using the sealant 108. Further, any suitable material such as silicon dioxide may be used to manufacture the plate 106.

[0018] The sealant 108 may be an adhesive material employed to adhesively connect the protective plate 106 and the sidewalls 116. The sealant 108 ensures no gaps or open regions exist between the sidewalls 116 and the protective plate 106, forming the desired sealed interior space for the LED modules 102. To this end, a layer of sealant 108 is applied along the edges of the mounting face 118 such that the sealant layer extends perpendicularly upward from the base 104. As shown in FIG. 1, the sealant 108 may form a frame-shaped structure having four sides; each side may be a rectangular plate of suitable thickness. The length and breadth of this frame structure may be substantially similar to the mounting face 118 and the height being equal or lesser than the sidewalls 116. As shown, a pair of opposite sides of the sealant 108 extends along the inner surface of the sidewalls 116, and the other pair defines additional sealant sidewalls for the base 104. The sealant 108 in connection with the edges of the base 104 outline a top open cuboid structure having LED modules 102 mounted on the base of the cuboid.

[0019] The top surface of the sealant 108 provides a support surface for the protective plate 106 and the adhesive characteristics of the sealant 108 glues the plate 106. To ensure no gaps exist between the protective plate 106 and the sidewalls 116, the top end of the sealant 108 may include an integrally formed step section 124 for positioning the protective plate 106 on the base 126 of the step. As shown in FIG. 2, the step section 124 may be a groove or cut out section formed at the top end of the sealant 108. The edges and the surfaces of the step may be sharp and flat, respectively, as shown in figures. Alternatively, the surfaces may be curved or non-uniform based on the shape of the protective plate 106. It should be understood that the step may be suitable shaped such that the protective plate 106 substantially fits into the step section 124. In an implementation, all the four sides of the sealant 108 may include the step section 124. Alternatively, only a pair of opposite sides, in contact with the sidewalls 116, may include the step section 124. In such a situation, the other pair of sides may extend from the base 104 until the step such that protective plate 106 may be placed on top of the step provided on two sides and top surface of the other two sides. In an embodiment of the present disclosure, the sealant 108 may not include any step section and the protective plate 106 may be positioned on top of the sealant 108.

[0020] In general, the sealant 108 may be light transmissive resin having a property of light transmission. Sealant material may be selected from one or more of a UV curable plotting compound, a gel based compound, an adhesive material, or any suitable material such as silicone, epoxy or rubber. In addition, a desiccant material may also be added to the sealant material in order to absorb moisture from the sealant.

[0021] The sealed structure provided by the sealant 108 encloses LED modules 102 connected to the mounting face 118 within the recess 122. Each LED module 102 includes multiple LEDs 128 mounted on a Printed Circuit board (PCB) 130. These LEDs 128 may be positioned on the PCB 130 in any fashion without departing from the scope of the present disclosure. For example, the LEDs 128 may be positioned in a single line, in two lines, in a particular pattern, or randomly. Moreover, the LEDs 128 of a particular module may be connected in series or in parallel. As shown in FIG. 1, multiple LED modules 102 may be mounted on the base 104. Power connections to the LED modules 102 may be supplied by an external power supply (not shown) through conductive wires 132. Each LED module 102 may be connected to an individual power supply or multiple LED modules 102 may be connected to each other and a common power supply may be utilized.

[0022] The conductive wires 132, connected to each LED or the LED module 102, may extend out from the lighting device 100 through the sealant 108. To this end, the sealant 108 may include passage holes 134 having dimensions substantially equal to that of the conductive wires 132. Wires 132 when passed through are significantly secured within the passage holes 134. The passage holes 134 are provided on one or more sealing sides that are not in contact with the sidewalls 116, avoiding formation of apertures on the sidewalls 116. In an

implementation, when the wires 132 pass through the holes 134, the sealant 108 may itself expand to snugly fit the wires 132. Additionally, fitting members (not shown), such as washers or flexible sleeves, may be added that ensure no gaps exist between the wires 132 and the sealant 108. It will be understood that other fitting means may be contemplated and those means are well within the scope of the present disclosure.

[0023] The outer case 110 absorbs heat from the LEDs 128 and dissipates this heat into the atmosphere, increasing the efficiency of the LEDs 128. As shown, the outer case 110 includes multiple cooling fins 136 extending perpendicularly from the external face 120 of the main body 114. The outer case 110 may be made of aluminum alloy or any suitable conductive material known in the art. Further, it should be understood that any heat sink may be employed in this lighting device 100 without departing from the scope of the present disclosure. For example, pin type, straight or flared fin type outer cases may be employed.

[0024] In one embodiment of the present disclosure, the desiccant 112 or other hygroscopic material may be disposed within the recess 122 defined by the sealant 108, sidewalls 116, and the base 104. In certain situations, the face of the sidewalls 116 or the base 104 facing the interior recess space can have perforations, porosities, openings or a moisture- permeable membrane through which moisture may permeate into the recess 122. As already discussed, the protective plate 106 covers the recess using the sealant 108. The desiccant 112 has a high affinity for water and as such may be used as a drying agent, absorbing any moisture that may enter the sealed recess. By using the desiccant material in the assembly, LED module 102 can be protected from residual atmospheric moisture trapped within the sealed recess at the time of manufacture. In addition, the desiccant 112 can reduce the adverse effects of moisture ingress into the sealed recess.

[0025] In the figures depicted in this disclosure, the base 104, the sidewalls 116, and the protective plate 106 are represented as generally rectangular structures. It will be understood, however, that this geometrical shape is merely exemplary and these elements may be shaped in any desired fashions without departing from the scope of the present disclosure. For example, in some embodiments, the base 104 may have a circular, triangular, polygonal, or random shape, and the protective plate 106 may be similarly shaped to encapsulate the LEDs 128. Moreover, it will be appreciated that the sealant 108 may not always be a four-sided frame structure, and its shape will vary based on that of the main body 114.

[0026] The embodiments of the present disclosure may be applicable in any lighting devices such as an LED lamp. To assemble the LED lamp, the LED modules 102 are connected to the mounting face 118 of the base 104 using known fixtures (not shown) such as screws, adhesives, or welding. In addition, to allow efficient heat dissipation from the LEDs 128, the external face 120 of the base 104 may be connected to a heat sink such as the outer case 110. Subsequently, the sealant 108 is applied along the edges of the base 104 extending

perpendicularly from the base 104 in the direction of the sidewalls 116 such that two sides of the sealant 108 are in contact with the inner surface of the sidewalls 116. The sealant 108 along with the base 104 defines the recess 122 encapsulating the LED modules 102. As discussed in connection with FIG. 2, the top end of the sealant 108 may include grooves or step section. The protective glass plate 106 is then positioned on top of the sealant 108 or the step section 124 of the sealant 108 that glues the protective plate 106. The sealant 108 not only defines the recess 122 along with the base 104, but it also acts as an adhesive that glues the plate 106 covering the recess 122. Accordingly, the LED module 102 is received in a hermetical cavity defined between the base 104, sidewalls 116, sealant 108, and the plate 106. [0027] In use, heat generated by the LED modules 102 is absorbed by the main body 114 of the base 104 and finally dispersed into ambient cool air via the fins 128 disposed at the external face 122 of the base 104. Further, the enclosed LED module 102 is protected from climatic elements that may impose a risk of damaging the LEDs 128. In an embodiment, the desiccant 112 may be disposed within the enclosure to absorb moisture that may creep in during manufacture.

[0028] The specification has set out a number of specific exemplary embodiments, but those skilled in the art will understand that variations in these embodiments will naturally occur in the course of embodying the subject matter of the disclosure in specific implementations and environments. It will further be understood that such variation and others as well, fall within the scope of the disclosure. Neither those possible variations nor the specific examples set above are set out to limit the scope of the disclosure. Rather, the scope of the present disclosure is defined solely by the claims set out below.

Claims

CLAIMS What is claimed is:

1. A lighting device comprising:

a base;

a pair of sidewalls extending perpendicularly from two opposite edges of a first face of the base, the sidewalls defining a recess;

an LED module mounted on the first face of the base;

a sealant extending upwardly along the edges of the first face, the sealant being in contact with an inner surface of the sidewalls; and

a protective plate covering the recess such that edges of the protective plate are in contact with the sealant.

2. The lighting device of claim 1 further comprising a desiccant disposed within the recess.

3. The lighting device of claim 1, wherein the sealant is an adhesive.

4. The lighting device of claim 1, wherein the sealant is a frame-shaped structure.

5. The lighting device of claim 1, wherein the top end of the sealant includes a step section.

6. The lighting device of claim 5, wherein the protective plate is positioned on the step section.

7. The lighting device of claim 1 further comprising conductive wires, coupled to the LED module, extending out from the lighting device through the sealant.

8. The lighting device of claim 7, wherein the conductive wires pass through a section of the sealant not in contact with the sidewalls.

9. The lighting device of claim 1 further comprising an outer case mounted on a second face of the base.

10. A lighting device comprising:

a base having a first face, a second face, and a pair of sidewalls extending upwardly from two opposite edges of the first face, the sidewalls defining a recess;

an LED module mounted on the first face of the base;

an outer case mounted on the second face of the base;

a sealant extending upwardly along the edges of the first face, the sealant being in contact with the inner surface of the sidewalls, the upper end of the sealant including a step section; a protective plate covering the recess such that edges of the protective plate are in contact with the step section on the sealant; and

conductive wires, connected to the LED module, extending out from the base through the sealant.

11. The lighting device of claim 10 further comprising a desiccant disposed within the recess.

12. The lighting device of claim 10, wherein the sealant is an adhesive.

13. The lighting device of claim 10, wherein the sealant is a frame-shaped structure.

14. The lighting device of claim 10, wherein the sealant includes a step section on the two sides that extend along the sidewalls.

15. The lighting device of claim 14, wherein the remaining two sides of the sealant extend from the first face until the step section.

16. The lighting device of claim 15, wherein the conductive wires pass through a section of the sealant not in contact with the sidewalls.

17. The lighting device of claim 10, wherein the LED module includes one or more LEDs mounted on one or more printed circuit boards.

18. The lighting device of claim 10, wherein the protective plate is a glass plate.

19. The lighting device of claim 10, wherein the outer case includes one or more cooling fins.