Patent Application
20110019408
The present application claims priority under 35 U.S.C. §119 to Korean Patent Application No. 10-2009-0067429, filed on Jul. 23, 2009, the entirety of which is hereby incorporated by reference.
1. Field
The present invention relates to a light emitting device including a light emitting diode.
2. Description of the Related Art
A light emitting diode (LED) may constitute a light emitting source by using a compound semiconductor material such as a GaAs based material, AlGaAs based material, GaN based material, InGaN based material, InGaAlP based material and the like.
LED is packaged and used as a light emitting device emitting various colors. There have been many active researches for utilizing the LED as a light source in the field of the lighting device.
One aspect of this invention includes a light emitting device. The light emitting device includes:
a frame having an opening; at least one light emitting diode disposed on the frame; a reflector which reflects light irradiated from the light emitting diode and emits the light through the opening; and a reflective protrusion which is formed on an inner surface of the reflector and determines an orientation angle of the light emitted through the opening.
Another aspect of this invention includes a light emitting device. The light emitting device includes: a frame having both an opening formed therein and a heat radiator formed on the outer circumference thereof; at least one light emitting diode disposed on the frame; a reflector which reflects light irradiated from the light emitting diodes and emits the light through the opening; and a reflective protrusion which is formed inside the reflector and determines an orientation angle of the light emitted through the opening.
The embodiment will be described in detail with reference to the following drawings.
a and 2b area cross sectional view of a light emitting device according to a first embodiment.
In description of an embodiment, when it is mentioned that each panel, a member, a frame, a sheet, a plate or substrate and the like are formed “on” or “under” each panel, the member, the frame, the sheet, the plate or substrate and the like, it means that the mention includes a case where each panel, a member, a frame, a sheet, a plate or substrate and the like are formed “directly” or “by interposing another layer (indirectly)”. A criterion for “on” and “under” of each component will be described based on the drawings. A size of each component of the drawings is magnified for description thereof. The size of each component does not necessarily mean its actual size.
Hereinafter, embodiments will be described in a more detailed manner with reference to the accompanying drawings.
The preferred embodiment includes a circular frame, one of ordinary skill in the art will appreciate that the frame can take on any one of a number of shapes.
Referring to
The reflective protrusion 140 can be integrally formed on the reflector 130. For another example, the reflective protrusion 140 can be manufactured to be attached to and detached from the reflector 130.
The frame 110 has a ring shape surrounding the opening 115. The frame 110 includes an upper surface 110a, a lower surface 110b, an inner lateral surface 110c surrounding the opening 115, and an outer lateral surface 110d.
The frame 110 can be attached and detached. Therefore, when the frame 110 is applied to a built-in lighting device, the frame 110 having the light emitting diode enables the built-in lighting device to be exchanged without taking out or disassembling the built-in lighting device. Therefore, since a light source is provided to the frame of the light emitting device according to the embodiment, it is possible to easily exchange the light source of the light emitting diode by detaching and attaching the frame without disassembling the entire lighting device.
The light emitting diodes 120 may be mounted on the upper surface 110a of the frame 110 separately from each other by a predetermined interval.
The light emitting diodes 120 may be arranged along the frame 110 in a line or a plurality of lines. The figures show that the light emitting diodes 120 are arranged in the form of a line.
Meanwhile, a zener diode (not shown) may be disposed on the frame 110 to protect the light emitting diode 120.
The light emitting diode 120 may emit a target light, for example, white light and create a desired light through a mixture of lights from a plurality of the light emitting diodes 120. Also, the light emitting diode 120 may generate target lights having various colors in accordance with the intention of a user.
While the light emitting diode 120 emits the light on the upper surface 110a of the frame 110, there is no limit to the light emission type of the light emitting diode 120.
The frame 110 supplies an electric power to the light emitting diode 120.
The frame 110 may function as a printed circuit board which is electrically coupled to the light emitting diodes 120.
The frame 110 may comprises a single layer substrate or a multi layer substrate. A wiring pattern may be formed on the inner surface of the frame 110 or on the lower surface of the frame 110. There is no limit to the mounting method and mounting pattern of the light emitting diode 120.
The reflector 130 is disposed in a light irradiation direction in order to reflect the light irradiated from the light emitting diode 120.
The reflector 130 may have a hemisphere shape. The reflector 130 does not necessarily have a hemisphere shape, however, various shapes such as a conical shape, a cylindrical shape, a cannon ball shape and a polygonal shape and the like can be also applied to the reflector 130 in consideration of a reflection efficiency and an optical uniformity.
The concave surface of the reflector 130 actually functions as the reflective surface 130a reflecting the light irradiated from the light emitting diode 120.
The reflective surface 130a may comprises a material having an excellent optical reflection efficiency.
The reflector 130 may be coupled to the upper surface 110a of the frame 110 where the light emitting diodes 120 are placed inside the reflector 130.
Though not shown, the reflector 130 and the frame 110 can be coupled to each other by using fastening means. The fastening means includes a fastening member or an adhesive member.
At least one reflective protrusion 140 is formed on some areas of the reflective surface 130a.
The reflective protrusion 140 is integrally formed with the reflector 130 or is adhered to some areas of the reflective surface 130a.
The surface of the reflective protrusion 140 is made of the same material as that of the reflective surface 130a.
The reflective protrusion 140 may have a conical shape.
The reflective protrusion 140 has its bottom surface contacting with the reflector 130 and has its vertex facing the opening 115.
The axis of the reflective protrusion 140 may be perpendicular to a plane formed by extending the upper surface 110a of the frame 110.
The central point of the bottom surface of the reflective protrusion 140 may be the farthest from a plane formed by extending the upper surface 110a of the frame 110 in a vertical direction to the plane.
An orientation angle of the light which is reflected by the reflective surface 130a and is emitted through the opening 115 varies according to the height “b” of the reflective protrusion 140 and the diameter “a” of the bottom surface of the reflective protrusion 140.
The aforementioned orientation angle of the light refers to a diffusion angle of light emitted through the opening 115 of the frame 110. An effective lighting area may vary according to the orientation angle of light.
For example, if the height of the reflective protrusion 140 is increased, the orientation angle of light may be increased, thus the effective lighting area may be increased. Otherwise, if the height of the reflective protrusion 140 is decreased, the orientation angle of light may be decreased and the effective lighting area may be decreased.
The height “b” of the reflective protrusion 140 from the reflector 130 may be less than a vertical height “c” from the frame 110 to the reflector 130 point which is the farthest from the frame 110.
On the other hand, the height “b” of the reflective protrusion 140 from the reflector 130 may be greater than the vertical height “c” from the frame 110 to the reflector 130 point which is the farthest from the frame 110.
Meanwhile, in
For example, it is assumed that the orientation angle of the light emitting diode 120 is 120°. Since the light emitting diode 120 irradiates light in a vertical direction, the light emitting area of the light emitting diode 120 forms an angle of 30° with the frame 110. Here, if the radius of the frame 110 is defined as “√3d”, the lengths of the sides of a triangle area 400 formed by the light emitting area and the frame are defined as “2d” and “d” respectively.
When the reflective protrusion 140 has a conical shape, it is preferable that the diameter “x” of the bottom surface of the reflective protrusion 140 is less than √3d.
Meanwhile, if the reflector 130 has a constant height “H”, it is preferable that the height of the reflective protrusion 140 is greater than a length difference between the height “H” of the reflector 130 and the vertical length “d” of the triangle area 400. That is, it is required that a relational expression of y>H−d should be satisfied. If y<H−d, a part of the light irradiated from the light emitting diode 120 is directly incident on the opposite side of the reflector without being reflected by the reflective protrusion 140 and is immediately irradiated to the outside of the frame 110. As a result, indirect lighting effect is reduced.
The height “b” of the reflective protrusion 140 may be equal to or greater than 0 mm.
The reflective protrusion 140 may be formed to be larger than bumpy patterns formed on the surface of the reflective surface 130a. The bumpy patterns are formed for scattering light.
The lighting emitting device 100 having such a structure can be used as an indirect lighting device.
The reflective protrusion 140 according to the embodiment makes it possible to obtain a desired effective lighting area by adjusting the orientation angle of light, to improve an optical uniformity and to prevent a glare phenomenon.
In addition, even if any one of the plurality of the light emitting diodes 120 is disabled, the disabled light rarely affect the entire light. Therefore, there is an effect of lengthening the time period for using the lighting device, thereby reducing the manufacturing cost.
At least any one among the surface of the reflective protrusion 140 and the reflective surface 130a of the reflector 130 may have roughness. A degree of the roughness of the reflective surface 130a and a degree of the surface roughness of the reflective protrusion 140 may be different from each other according to the characteristic and design of the lighting.
The light irradiated from the light emitting diode 120 may be scattered while reflected because of the roughness of the reflective surface 130a of the reflector 130 and the roughness of the reflective protrusion 140, so a lighting uniformity can be improved.
As a result, in the effective lighting area of the light irradiated from the light emitting device 100, a hot spot is removed and a luminance distribution of the light is improved.
Here, regarding a light emitting device 200 shown in
Referring to
The light irradiated from the light emitting diode 120 may be scattered while reflected by the bumpy patterns 210 which are formed on both the reflective surface 130a of the reflector 130 and the surface of the reflective protrusion 140.
Since the light emitting device 200 does not require a separate diffusion sheet and a separate scattering sheet and the like, it is possible to maintain the light intensity of the light emitting diode 120 of equal to or greater than 90%.
As a result, in the effective lighting area of the light irradiated from the light emitting device 200, a hot spot is removed and a luminance distribution of the light is improved.
Here, regarding a light emitting device 300 shown in
Referring to
The frame 110 includes an upper surface 110a, a lower surface 110b, an inner lateral surface 110c and an outer lateral surface 110d. The heat radiator 330 is formed to surround the lower part of the outer lateral surface 110d.
There is a difference in diameter between the heat radiator 330 and the upper surface 110a of the frame 110. The heat radiator 330 projects out from the outer lateral surface 110d.
Since the heat radiator 330 obtains an area for radiating heat, it is possible to overcome the problem of radiation heat of the light emitting diode 120 and to obtain reliability.
The frame 110 can be integrally formed with the heat radiator 330 or formed to be connected to the heat radiator 330.
The reflector 130 may have a hemisphere shape. The concave surface of the reflector 130 forms a reflective surface 130a.
The reflective protrusion 140 is formed on some areas of the reflective surface 130a. The surface of the reflective protrusion 140 is made of the same material as that of the reflective surface 130a.
The reflective protrusion 140 has a conical shape. The reflective protrusion 140 has its bottom surface contacting with the reflective surface 130a and has its vertex facing the opening 115.
The height “b” of the reflective protrusion 140 from the reflector 130 may be less than a vertical height “c” from the frame 110 to the reflector 130 point which is the farthest from the frame 110.
The reflective protrusion 140 according to the embodiment makes it possible to obtain a desired effective lighting area by adjusting the orientation angle of light, to improve an optical uniformity and to prevent a glare phenomenon.
An orientation angle of the light which is reflected by the reflective surface 130a and is emitted through the opening 115 varies according to the height “b” of the reflective protrusion 140 and the diameter “a” of the bottom surface of the reflective protrusion 140.
At least any one among the surface of the reflective protrusion 140 and the reflective surface 130a of the reflector 130 may have roughness. A degree of the roughness of the reflective surface 130a and a degree of the surface roughness of the reflective protrusion 140 may be different from each other according to the characteristic and design of the lighting.
The light irradiated from the light emitting diode 120 may be scattered while reflected because of the roughness of the reflective surface 130a of the reflector 130 and the surface roughness of the reflective protrusion 140, so a lighting uniformity can be improved.
As a result, in the effective lighting area of the light irradiated from the light emitting device 300, a hot spot can be removed and a luminance distribution of the light can be improved.
The foregoing embodiments and advantages are merely exemplary and are not to be construed as limiting the present invention. The present teaching can be readily applied to other types of apparatuses. The description of the foregoing embodiments is intended to be illustrative, and not to limit the scope of the claims. Many alternatives, modifications, and variations will be apparent to those skilled in the art. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function and not only structural equivalents but also equivalent structures. Moreover, unless the term “means” is explicitly recited in a limitation of the claims, such limitation is not intended to be interpreted under 35 USC 112(6).
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2009-0067429 | Jul 2009 | KR | national |
