# Patent

## Title
Led lighting device including limit switch

## Abstract

The lighting device includes: a first body including a first surface, a second body including a second surface, a plurality of light emitting devices disposed on the first surface and the second surface, a coupler that is disposed at least one of the ends of the first and the second bodies, and a limit switch connecting and is connecting electric power supplied to the plurality of the light emitting diodes in accordance with change of a distance between the first body and the second body.

## Background
This application is a continuation of application Ser. No. 12/805,798 filed Aug. 19, 2010 and claims the benefit of Korean Patent Application Nos. 10-2010-0028854, 10-2010-028855, 10-2010-028856, 10-2010-028857, 10-2010-028858, 10-2010-028859 all filed on Mar. 30, 2010, Korean Patent Application Nos. 10-2010-0030716 filed on Apr. 5, 2010 and Korean Patent Application No. 10-2009-0076953 filed Aug. 19, 2009 which are hereby incorporated by reference for all purposes as if fully set forth herein.


BACKGROUND OF THE INVENTION
1. Field of the Invention
This embodiment relates to a lighting device.
2. Description of the Related Art
A light emitting diode (LED) is a semiconductor element for converting electric energy into light. As compared with existing light sources such as a fluorescent lamp and an incandescent electric lamp and so on, the LED has advantages of low power consumption, a semi-permanent span of life, a rapid response speed, safety and an environment-friendliness. For this reason, many researches are devoted to substitution of the existing light sources with the LED. The LED is now increasingly used as a light source for lighting devices, for example, various lamps used interiorly and exteriorly, a liquid crystal display device, an electric sign and a street lamp and the like.
SUMMARY OF THE INVENTION
An embodiment includes a lighting device. The lighting device includes: a first body including a first surface; a second body including a second surface; a plurality of light emitting diodes disposed on the first surface and the second surface; a coupler that is disposed at at least one of the ends of the first and the second bodies; and a limit switch connecting and disconnecting electric power supplied to the plurality of the light emitting diodes in accordance with change of a distance between the first body and the second body.
An embodiment includes a lighting device. The lighting device includes: a housing; a light source unit; a coupling member being coupled to the housing and including an insertion groove; and at least one reflector placed between the housing and the coupling member, wherein the light source unit includes: a first body including a first coupling unit coupled to the coupling member and including a first inclined surface toward the reflector; a plurality of light emitting diodes disposed on the first inclined surface; a third body electrically connected to the first body; and a limit switch connecting and disconnecting electric power supplied to the plurality of the light emitting diodes in accordance with change of a distance to the first body and the third body.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a light device in accordance with an embodiment of the present invention.
FIG. 2 is an exploded perspective view of a light device in accordance with the embodiment of the present invention.
FIG. 3 is a cross sectional view of a light device in accordance with the embodiment of the present invention.
FIG. 4a is a cross sectional view of a coupling member shown in FIG. 3.
FIG. 4b is a view showing an enlarged part denoted by “A” of FIG. 3.
FIG. 4c is a view showing a light distribution angle of a light emitting diode mounted in the light emitting groove according to the embodiment of the present invention.
FIGS. 5 and 6 are perspective views of a light source unit in accordance with the embodiment of the present invention.
FIG. 7 is an exploded perspective view of a light source unit in accordance with the embodiment of the present invention.
FIG. 8 is a perspective view of a coupling of a first connection terminal and a second connection terminal of a lighting device in accordance with the embodiment of the present invention.
FIGS. 9a and 9b are plan views of a first connection terminal and a second connection terminal of a lighting device in accordance with the embodiment of the present invention.
FIGS. 10a and 10b show a coupling and separation process of a light source unit and a coupling member in accordance with the embodiment of the present invention.
FIGS. 11a and 11b show how a limit switch in accordance with the embodiment is operated.
FIGS. 12 and 13 are cross sectional views showing a light source unit and a coupling member of a lighting device in accordance with a modified embodiment.
FIG. 14 illustrates a pressing of a limit switch.



DETAILED DESCRIPTION OF EMBODIMENTS
Hereinafter, embodiments of the present invention will be described in detail with reference to accompanying drawings. However, the accompanied drawings are provided only for more easily describing the embodiments. It is easily understood by those skilled in the art that the spirit and scope of the present invention is not limited to the scope of the accompanied drawings.
FIG. 1 is a perspective view of a light device 1 in accordance with an embodiment of the present invention. FIG. 2 is an exploded perspective view of a light device 1 in accordance with the embodiment of the present invention. FIG. 4c is a view showing a light distribution angle θ of a light emitting diode 312 mounted in the light emitting groove 316 according to the embodiment of the present invention.
In FIGS. 1 to 4b, a lighting device 1 in accordance with an embodiment of the present invention includes a housing 100, a coupling member 110, a reflector 200, a light source unit 300 and a power supply unit 400.
The housing 100 has a shape of a box for accepting the housing 100, the coupling member 110, the reflector 200 and the power supply unit 400. While the shape of the housing 100 as viewed from the outside is quadrangular, the housing 100 can have various shapes without being limited to this.
The housing 100 is made of a material capable of efficiently releasing heat. For example, the housing 100 is made of a metallic material such as Al, Sn, Ni, Ag, Cu, Ti, Mo, W, Au and Pt and so on. The housing 100 may be also made of various resin materials.
A connecting groove 107 for connecting electrically the power supply unit 400 to an external power supply is formed on a lateral surface and/or an upper surface of the housing 100.
The housing 100 includes an opening 101 such that light radiated from the light source unit 300 is reflected to be emitted by the reflector 200.
Meanwhile, in order to dispose the lighting device 1 on an external support member such as a ceiling or a wall surface, an insertion unit corresponding to a shape of the lighting device 1 is formed in the external support member, and then the lighting device 1 is inserted into and fixed to the insertion unit. Here, a coupling frame 500 is coupled to the lower part of the lateral surface of the housing 100, so that the lighting device 1 can be securely coupled to the external support member.
The coupling member 110 is coupled on an inner upper surface of the housing 100. The coupling member 110 is coupled to the housing 100 by using various methods. For example, the coupling member 110 is coupled to the housing 100 by means of a coupling screw, an adhesive agent and so on.
The coupling member 110 is formed to be extended on an upper surface 102 of the housing 100 in a first direction. For example, the coupling member 110 can be extended from an inner wall surface to the opposite inner wall surface of the housing 100.
The housing 100 and the coupling member 110 are attachable to and removable form the reflector 200.
A second groove 103 is formed on the inner wall surface of the housing 100. A first side 210 of the reflector 200 is inserted into the second groove 103. It is possible to form the one second groove 103 or a plurality of the second grooves 103.
A first groove 111 is formed on an outer wall surface of the coupling member 110. The first groove 111 is formed to be extended in the first direction. A second side 220 of the reflector 200 is inserted into the first groove 111.
The housing 100 and the coupling member 110 can fix and sustain the reflector 200 by inserting the first side 210 of the reflector 200 into the second groove 103 of the housing 100 and by inserting the second side 220 of the reflector 200 into the first groove 111 of the coupling member 110.
In addition, the light source unit 300 is attachable to and removable from the coupling member 110.
An insertion groove 112 is formed in the middle part of the coupling member 110. A part of the light source unit 300 is inserted into the insertion groove 112. The insertion groove 112 can be formed to be extended in the first direction.
A third groove 113 is formed on an inner wall surface of the insertion groove 112. A projection 313 of the light source unit 300 is inserted into the third groove 113. As a result, the light source unit 300 is securely coupled to the coupling member 110 by means of the third groove 113. The coupling of the light source unit 300 and the coupling member 110 will be described later in more detail.
A first connection terminal 120 is formed in the middle part within the insertion groove 112. When the light source unit 300 is inserted into the insertion groove 112, the first connection terminal is coupled to and electrically connected to a second connection terminal 330 of the light source unit 300. When the first connection terminal 120 is connected to the second connection terminal 330, electric power and/or a driving signal can be transferred to the light source unit 300 through the first connection terminal 120 and the second connection terminal 330.
Based on a design of the light source device 1, it is possible to form the one first connection terminal 120 or a plurality of the first connection terminals 120. More detailed descriptions of the first connection terminal 120 and the second connection terminal 330 will be provided later.
The coupling member 110 performs a function of directly releasing heat generated from the light source unit 300 or transferring the heat to the housing 100.
It is desirable to form the coupling member 100 by using a material capable of efficiently releasing and/or transferring the heat. For example, the coupling member 110 is made of a metallic material such as Al, Sn, Ni, Ag, Cu, Ti, Mo, W, Au and Pt and so on.
A part of the coupling member 110 can have an uneven structure 116. The uneven structure 116 can widen the surface area of the coupling member 110 and improve a heat release effect.
The reflector 200 includes a first reflector 200a and a second reflector 200b. The first reflector 200a and the second reflector 200b are attachable to and removable from the housing 100 and the coupling member 110.
For example, as shown in FIG. 2, the second reflector 200b is coupled to the housing 100 and the coupling member 110 by inserting the second side 220 of the second reflector 200b into the first groove 111 of the coupling member 110 and by inserting the first side 210 of the second reflector 200b into the second groove 103 of the housing 100. The second side 220 of the reflector 200 can have a level difference. The first side 210 of the reflector 200 can also have a level difference. At least one insertion end 211 which is inserted into the second groove 103 is formed at the first side 210 of the reflector 200. A shape of the second groove 103 is formed to correspond to the selection end 211.
The first reflector 200a and the second reflector 200b have a parabola-shaped surface and are extended in the first direction. Therefore, the first reflector 200a and the second reflector 200b have a parabolic shape having two parabolic surfaces. Here, the shape of the reflector 200 can be variously changed according to a desired lighting.
The reflector 200 is made of a metallic material or a resin material which has a high reflection efficiency. For example, the resin material includes any one of PET, PC and PVC resin. The metallic material includes any one of Ag, alloy including Ag, Al, and alloy including Al.
The surface of the reflector 200 is coated with Ag, Al, white photo solder resist (PSR) ink, a diffusion sheet and the like. Otherwise, an oxide film is formed on the surface of the reflector 200 by an anodizing process.
Here, the material and color of the reflector 200 are not limited and are variously selected depending on a lighting generated by the lighting device 1.
When the power supply unit 400 is connected to the light source unit 300, the power supply unit 400 can supply at least one of electric power and a driving signal.
As shown in FIGS. 2 and 3, the power supply unit 400 is disposed in a space between the parabola-shaped reflector 200 and the inner surface of the housing 100. That is, due to the parabola shape of the reflector 200, an empty space is formed between the reflector 200 and a corner inside the housing 100. As a result, the power supply unit 400 is disposed in the empty space.
The power supply unit 400 converts an alternating current (AC) electric power into a direct current (DC) electric power and outputs the direct current (DC) electric power.
The power supply unit 400 is electrically connected to the light source unit 300 through a wire or a flexible printed circuit board (FPCB). For example, a wire or a FPCB is extended from the power supply unit 400 and is electrically connected to the first connection terminal 120 through the connecting groove 107 formed in the coupling member 110. The first connection terminal 120 is electrically connected to the second connection terminal 330. As a result, the power supply unit 400 is electrically connected to the light source unit 300.
FIG. 4b is a view showing an enlarged part denoted by “A” of FIG. 3. FIGS. 5 and 6 are perspective views of a light source unit 300 in accordance with an embodiment of the present invention. FIG. 7 is an exploded perspective view of a light source unit 300 in accordance with an embodiment of the present invention.
In FIGS. 4 to 7, the light source unit 300 in accordance with an embodiment of the present invention includes a first body 310a, a second body 310b, a middle body 320, a plurality of light emitting diodes (LED) 312 and a coupling cap 350. The first body, the second body 310b and the middle body 320 form a body of the light source unit 300. The light source unit 300 may be formed to be extended in the first direction, that is, in the direction of length of the reflector 200.
The lower part of the first body 310a is formed to have a first sloping surface. The first sloping surface is formed on the outer wall surface of the first body 310a. The first sloping surface is formed such that the first sloping surface faces the parabolic surface of the first reflector 200a. Here, a plurality of the sloping surfaces as well as the first sloping surface can be formed in the first body 310a. 
The lower part of the second body 310b is also formed to have a second sloping surface. The second sloping surface is formed on the outer wall surface of the second body 310b. The second sloping surface is formed such that the second sloping surface faces the parabolic surface of the second reflector 200b. Here, a plurality of the sloping surfaces as well as the second sloping surface can be formed in the second body 310b. 
A light emitting groove 316 is formed on the first and the second sloping surfaces respectively.
A substrate 311 is provided on the basal surface of the light emitting groove 316. A plurality of the light emitting diodes 312 may be provided on the substrate 311. Otherwise, a plurality of electrodes (not shown) are disposed in the light emitting grooves 316 so that a plurality of the electrodes (not shown) is electrically connected to a plurality of the light emitting diodes 312. An optical structure 318 is formed on a plurality of the light emitting diodes 312. The optical structure 318 will be described later.
The depth and width of the light emitting groove 316 can be variously adjusted according to the light distribution of a plurality of the light emitting diodes 312 disposed inside the light emitting groove 316. In other words, the lighting device 1 is able to cause the reflector 200 to provide users with light radiated from the light source unit 300 by adjusting the depth and width of the light emitting groove 316 instead of directly providing users with light radiated from the light source unit 300. As a result, it is possible to provide users with subdued light by reducing glare.
A light distribution angle of light emitted from the light emitting groove 316 is from 90° to 110°. The depth and width of the light emitting groove 316 is formed to cause light emitted from the light emitting groove 316 to be incident evenly on the entire area of the reflector 200.
Additionally, the depth and width of the light emitting groove 316 is adjusted such that a part of light radiated from a plurality of the light emitting diodes 312 is radiated to the outside through the opening 101 and the rest of the light is reflected by the reflector 200 and is radiated to the outside through the opening 101.
A plurality of the light emitting diodes 312 are determined, for example, through various combinations of red, green, blue and white light emitting diode which radiate red, green, blue and white light respectively. A plurality of the light emitting diodes 312 can be disposed in the light emitting groove 316 in the form of an array.
A plurality of the light emitting diodes 312 are controlled by electric power and/or a driving signal which are provided by the power supply unit 400, causing a plurality of the light emitting diodes 312 to selectively emit light or to adjust the luminance of light.
The optical structure 318 is disposed on a plurality of the light emitting diodes 312. The optical structure 318 functions to adjust the light distribution and the color sense of light radiated from a plurality of the light emitting diodes 312, and creates emotional lighting having various luminance and color senses if necessary.
The optical structure 318 is coupled to the light source unit 300 by inserting in a sliding way both ends of the optical structure 318 into a fourth groove formed on an inner surface of the light emitting groove 316. For example, the fourth groove is extended in the first direction and the optical structure 318 is coupled to the light source unit 300 by being inserted into the fourth groove in the first direction.
The optical structure 318 includes at least one of a lens, a diffusion sheet and a phosphor luminescent film (PLF).
The lens includes various lenses such as a concave lens, a convex lens and a condensing lens and so on according to a design of the lighting device 1.
The diffusion sheet diffuses evenly light radiated from a plurality of the light emitting diodes 312.
The phosphor luminescent film (PLF) includes fluorescent substance. Since the fluorescent substance included in the phosphor luminescent film (PLF) is excited by light radiated from a plurality of the light emitting diodes 312, the lighting device 1 can produce emotional lighting having various color senses by mixing a first light radiated from a plurality of the light emitting diodes 312 and a second light excited by the fluorescent substance.
For example, when a plurality of the light emitting diodes 312 radiate blue light and the phosphor luminescent film (PLF) includes a yellow fluorescent substance excited by blue light, the lighting device 1 radiates white light by mixing the blue light and yellow light.
The optical structure 318 is easily coupled to the fourth groove. Accordingly, a lens, a diffusion sheet and a phosphor luminescent film (PLF) can be alternately used as the optical structure 318.
Generally, the light distribution angle of the light emitted from the light emitting diode is about 120°. When the light emitting diode emits the light having such a wide light distribution angle, a part of the emitted light is reflected by the reflector 200 and is emitted to the outside through the opening 101. However, the rest of the light is directly emitted through the opening 101 to the outside, thereby enabling a user to feel glare.
To overcome such a problem, the light emitting groove 316 may be formed to block the light emitted directly from the light emitting diode 312 to the outside of the housing 100. That is, the light emitting groove 316 includes a projection part 316b formed on the basal surface thereof, thereby blocking the light emitted directly from the light emitting diode 312 to the outside of the housing 100.
As a result, due to the projection part 316b of the light emitting groove 316, the light emitted from a plurality of the light emitting diodes 312 is not directly provided to a user and is uniformly incident on the whole area of the reflector 200. Accordingly, it is possible to provide users with subdued light by reducing glare.
Furthermore, it is possible to block the direct light emitted from the light emitting diode 312 to the outside of the housing 100 by adjusting the depth and width of the light emitting groove 316, the height of the projection part 316b, the sloping angle of the basal surface 316a, the height of the housing 100 or the width of the reflector 200 and the like.
The sloping plane toward the reflector 200 is formed in the first body 310a and the second body 310b. Therefore, regarding a cross section of the light source unit 300 formed by coupling the first body 310a, the second body 310b and the middle body 320, the width of the lower part of the light source unit 300 is greater that of the upper part of the light source unit 300. For example, the cross section of the light source unit 300 can have various shapes such as a fan shape or a polygon shape and the like.
The first body 310a is formed to have a first coupling unit 315a. The first coupling unit 315a is an upper part of the first body 310a and is inserted into the insertion groove 112 of the coupling member 110.
The second body 310b is formed to have a second coupling unit 315b. The second coupling unit 315b is an upper part of the second body 310b and is inserted into the insertion groove 112 of the coupling member 110.
Due to the first coupling unit 315a and the second coupling unit 315b, the first body 310a and the second body 310b are higher than the middle body 320.
A projection 313 is formed in the upper ends of the first coupling unit 315a and the second coupling unit 315b respectively. The projection 313 has a shape in which a part of the upper end of each of the first coupling unit 315a and the second coupling unit 315b is projected outward. When the first coupling unit 315a and the second coupling unit 315b of the first body 310a and the second body 310b are inserted into the insertion groove 112 of the coupling member 110, the projection 313 is inserted into the third groove 113 formed in the insertion groove 112. As a result, the light source unit 300 is strongly coupled to the coupling member 110.
2) Middle Body 320
The middle body 320 is formed between the first body 310a and the second body 310b. Here, both inner surfaces of the first body 310a and the second body 310b are opposite to outer surfaces on which the light emitting diode 312 is mounted. A part of a lower surface of the middle body 320 can be exposed between the first body 310a and the second body 310b. 
The second connection terminal 330 is formed in the middle body 320. When the light source unit 300 is inserted into and coupled to the coupling member 110, the second connection terminal 330 is electrically connected to the first connection terminal 120 by being coupled to the first connection terminal 120 formed in the insertion groove 112 of the coupling member 110. The power supply unit 400 provides electric power and/or a driving signal to the light source unit 300 through the first connection terminal 120 and the second connection terminal 330.
On the middle body 320, a spring 340 is disposed between the first body 310a and the second body 310b. For example, as shown in FIG. 4b, the spring 340 can have a ‘ ’-shape and can be disposed contacting with the upper surface and the lateral surfaces of the first body 310a and the second body 310b. In more detail, the spring 340 is disposed contacting with the inner surfaces of the first coupling unit 315a and the second coupling unit 315b. 
The spring 340 provides an elastic force to the first body 310a and the second body 310b, coupling securely the light source unit 300 to the insertion groove 112 of the coupling member 110. The spring 340 provides the first body 310a and the second body 310b with an elastic force widening a space between the first body 310a and the second body 310b. That is, the spring 340 is disposed between the first body 310a and the second body 310b and performs a function of pushing outward the first body 310a and the second body 310b. Accordingly, when the light source unit 300 is inserted into the coupling member 110, the projections 313 formed in the upper ends of the first body 310a and the second body 310b are strongly coupled to the insertion groove 112 of the coupling member 110 by the force from the spring 340.
A sensor 321 is included in the lower part of the middle body 320. For example, the sensor 321 is exposed between the first body 310a and the second body 310b and senses various data such as an image, a voice, a pressure, a temperature and an electric wave and the like.
The lighting device 1 includes the sensor 321, thereby providing a user with various functions including light. The various data sensed by the sensor 321 is connected with the operation of a plurality of the light emitting diodes 312 and is used for driving the lighting device 1 suitably for an environment. For example, luminances and color senses of a plurality of the light emitting diodes 312 are adjusted by the data sensed by the sensor 321.
The sensor 321 includes at least one of a camera, a photo sensor, a pressure sensor, a temperature sensor, a burglarproof sensor, an electric wave sensor and the like.
A limit switch 323 is provided on both sides of the middle body 320. The limit switch 323 is in an on-state or in an off-state as the first body 310a and the second body 310b move toward the middle body 320. The limit switch is hereby configured in such a manner as to connect or disconnect the electric power supplied to a plurality of the light emitting diodes 312. The detailed description of the limit switch 323 will be described later.
Heat generated from a plurality of the light emitting diodes 312 is radiated by the body of the light source unit 300 or is transferred to the coupling member 110 and radiated. Thus, it is desirable to form the first body 310a, the second body 310b and middle body 320 with a material capable of efficiently radiating heat. For example, the first body 310a, the second body 310b and middle body 320 can be formed of a metallic material such as Al, Sn, Ni, Ag, Cu, Ti, Mo, W, Au and Pt and so on. Additionally, a part of the light source unit 300 has an uneven structure capable of efficiently radiating heat.
When the light source unit 300 is inserted into the insertion groove 112 of the coupling member 110, there is an empty space between the light source unit 300 and the insertion groove 112. Therefore, heat generated from the light source unit 300 can be effectively released through the empty space. Additionally, a part of the light source unit 300 has an uneven structure capable of efficiently radiating heat.
When the light source unit 300 is inserted into the insertion groove 112 of the coupling member 110, there is a contact area between the inner surface of the insertion groove 112 and both the first coupling unit 315a and the second coupling unit 315a. As such, one surfaces of the first coupling unit 315a and the second coupling unit 315b contact with the inner surface of the insertion groove 112, thereby forming a thermal conductivity route from the light source unit 300 to the coupling member 110. In this case, the wider the contact surface is, the more increased a radiant heat effect is. But, the heights of the first body 310a and the second body 310b are increased. Consequently, the height of the housing 100 should be increased. Therefore, it is necessary to consider a relation between the contact area and the height of the housing 100 in order that the lighting device 1 obtains an optimized radiant heat effect.
In addition, in order to improve the heat radiating effect, it is preferable that the first body 310a and the second body 310b are made of a metallic material having a high thermal conductivity, such as Al and the like. Since electrical components are mounted in the middle body 320, it is required that heat should not be transferred to the middle body 320. Accordingly, the middle body 320 may be made of a material having low thermal conductivity, for example, plastic, in order to prevent heat generated from the first and the second bodies 310a and 310b from being transferred to the middle body 320.
3) Coupling Cap 350
The first body 310a, the second body 310b and middle body 320 are coupled to each other by coupling a coupling cap 350 to one ends thereof. Here, the first body 310a, the second body 310b and middle body 320 are coupled such that they can rotate.
As shown in FIG. 7, a first groove 361a is formed on one side in the middle of the first body 310a. A second groove 361b is formed on one side in the middle of the second body 310b. A third groove 361c is formed in the middle of the middle body 320. One side of each of the first groove 361a and the second groove 361b is opened to the outside of the light source unit 300.
A fourth groove 361d is formed on the other side of the lower part the first body 310a. A fifth groove 361e is formed on the other side of the lower part of the first body 310b. The sixth groove 361f is formed in the lower part of the middle body 320.
The coupling cap 350 includes a first deterrent protrusion 351a, a second deterrent protrusion 351b, an upper part fixing protrusion 351c, a first axis protrusion 351d, a second axis protrusion 351e and a lower part fixing protrusion 351f. 
The first body 310a, the second body 310b and the middle body 320 are coupled to each other by inserting the first deterrent protrusion 351a into the first groove 361a, inserting the second deterrent protrusion 351b into the second groove 361b, inserting the upper part fixing protrusion 351c into the third groove 361c, inserting the first axis protrusion 351d into the fourth groove 361d, inserting the second axis protrusion 351e into the fifth groove 361e, and inserting the lower part fixing protrusion 351f into the third groove 361f. 
The coupling cap 350 is fixed to the middle body 320 by inserting the upper part fixing protrusion 351c and the lower part fixing protrusion 351f into the third groove 361c and the sixth groove 361f respectively.
The spring 340 retains a force pushing outward the first body 310a and the second body 310b. When the force causes a space between the first body 310a and the second body 310b to be widened to a certain extent, the space between the first body 310a and the second body 310b is not widened any more because the first body 310a and the second body 310b are fixed by the first deterrent protrusion 351a and the second deterrent protrusion 351b respectively. In this case, a maximum angle between the first body 310a and the second body 310b is formed by the first deterrent protrusion 351a and the second deterrent protrusion 351b. 
The first axis protrusion 351d is inserted into the fourth groove 361d and functions as an axis of rotation of the first body 310a. The second axis protrusion 351e is inserted into the fifth groove 361e and functions as an axis of rotation of the second body 310b. As a result, the first body 310a and the second body 310b can rotate about the first axis protrusion 351d and the second axis protrusion 351e respectively. Since one side of each of the first groove 361a and the second groove 361b is opened to the outside, the first groove 361a and the second groove 361b are separated from the first deterrent protrusion 351a and the second deterrent protrusion 351b respectively, during the rotations of the first body 310a and the second body 310b. The first axis protrusion 351d and the second axis protrusion 351e formed in the lower part of the coupling cap 350 are closely adjacent in order to function as axes of rotation.
Meanwhile, since the first body 310a and the second body 310b are formed to have the first sloping surface and the second sloping surface facing the reflector 200, with the viewpoint of a section of the light source unit 300 formed by the coupling of the first body 310a, the second body 310b and the middle body 320, the width of the lower part of the light source unit 300 is greater that of the upper part of the light source unit 300. For example, the light source unit 300 can have a fan-shaped section or a polygon-shaped section. The light source unit 300 can have various sections without being limited to this.
4) First Connection Terminal 120 and Second Connection Terminal 330
A first connection terminal 120 is provided in the middle part of the insertion grove 112 of the coupling member 110. A second connection terminal 330 is provided on the middle body 320 of the light source unit 300. The second connection terminal 330 is coupled to and electrically connected to the first connection terminal 120. Based on a design of the light source device 1, it is possible to form at least one or more the first connection terminals 120 and at least one or more the second connection terminals 330.
The first and the second connection terminals 120 and 330 may be electrically connected to each other by inserting the light source unit 300 into the insertion groove 112.
The first and the second connection terminals 120 and 330 is able to transfer electric power and/or a driving signal which are provided by the power supply unit 400 to the plurality of the light emitting diodes 312 and/or the sensor 321.
FIG. 8 is a perspective view of a coupling of a first connection terminal 120 and a second connection terminal 330 of a lighting device 1 in accordance with an embodiment of the present invention. FIGS. 9a and 9b are plan views of a first connection terminal 120 and a second connection terminal 330 of a lighting device 1 in accordance with an embodiment of the present invention.
The first connection terminal 120 includes a first female block 121a and a second female block 121b and without being limited to this, the first connection terminal 120 can include at least one pair of the female blocks.
For example, the first female block 121a includes a pair of a first terminal 123a and a second terminal 123b and another pair of a third terminal 123c and a fourth terminal 123d. The second female block 121b includes a pair of a fifth terminal 123e and a sixth terminal 123f and another pair of a seventh terminal 123g and an eighth terminal 123h. 
The first female block 121a and the second female block 121b are symmetrical to each other. That is, the first to the fourth terminals 123a to 123d and the fifth to the eighth terminals 123e to 123h are symmetrical with respect to a line between the first female block 121a and the second female block 121b. 
The second connection terminal 330 includes a first male block 331a and a second male block 331b and without being limited to this, the first connection terminal 120 can include at least one pair of the male blocks.
For example, the first male block 331a includes a pair of a first socket 333a and a second socket 333b and another pair of a third socket 333c and a fourth socket 333d. The second male block 331b includes a pair of a fifth socket 333e and a sixth socket 333f and another pair of a seventh socket 333g and an eighth socket 333h. 
The first male block 331a and the second male block 331b are symmetrical to each other. That is, the first to the fourth sockets 333a to 333d and the fifth to the eighth sockets 333e to 333h are symmetrical with respect to a line between the first male block 331a and the second male block 331b. 
A polarity of the first female block 121a and a polarity of the second female block 121b may be symmetrical to each other.
The polarities of the first and the second terminals 123a and 123b are symmetrical to the polarities of the seventh and the eighth terminals 123g and 123h. For example, if the polarities of the first and the second terminals 123a and 123b are ‘+’ and ‘−’ respectively, the polarities of the seventh and the eighth terminals 123g and 123h are ‘−’ and ‘+’ respectively. If the polarities of the first and the second terminals 123a and 123b are ‘−’ and ‘+’ respectively, the polarities of the seventh and the eighth terminals 123g and 123h are ‘+’ and ‘−’ respectively.
Additionally, the polarities of the third and the fourth terminals 123c and 123d are symmetrical to the polarities of the fifth and the sixth terminals 123e and 123f. For example, if the polarities of the third and the fourth terminals 123c and 123d are ‘+’ and ‘−’ respectively, the polarities of the fifth and the sixth terminals 123e and 123f are ‘−’ and ‘+’ respectively. If the polarities of the third and the fourth terminals 123c and 123d are ‘−’ and ‘+’ respectively, the polarities of the fifth and the sixth terminals 123e and 123f are ‘+’ and ‘−’ respectively.
The polarities of the first to the eighth sockets 333a to 333h can be various formed depending on the polarities of the first to the eighth terminals 123a to 123h. 
When the light source unit 300 is coupled to the coupling member 110 in the first direction, the first connection terminal 120 is electrically and physically connected to the second connection terminal 330 by inserting the first and the second terminals 123a and 123b into the first and the second sockets 333a and 333b, inserting the third and the fourth terminals 123c and 123d into the third and the fourth sockets 333c and 333d, inserting the fifth and the sixth terminals 123e and 123f into the fifth and the sixth sockets 333e and 333f, inserting the seventh and the eighth terminals 123g and 123h into the seventh and the eighth sockets 333g and 333h. 
In addition, when the light source unit 300 is coupled to the coupling member 110 in a second direction (that is, a reverse direction to the first direction), the first connection terminal 120 is electrically and physically connected to the second connection terminal 330 by inserting the first and the second terminals 123a and 123b into the seventh and the eighth sockets 333g and 333h, inserting the third and the fourth terminals 123c and 123d into the fifth and the sixth sockets 333e and 333f, inserting the fifth and the sixth terminals 123e and 123f into the third and the fourth sockets 333c and 333d, inserting the seventh and the eighth terminals 123g and 123h into the first and the second sockets 333a and 333b. 
As such, since the structures and polarities of the first connection terminal 120 and the second connection terminal 330 are symmetrical to each other, it is possible to connect the light source unit 300 to the coupling member 110 irrespective of the coupling direction. Accordingly, the lighting device 1 according to the embodiment makes it easier to couple the light source unit 300 to the coupling member 110, enhancing a convenience for use thereof.
In the meantime, when the light source unit 300 is coupled to the coupling member 110, the first, second, seventh and eighth terminals 123a, 123b, 123g and 123h are used as connectors for transferring electric power. The third, fourth, fifth and sixth terminals 123c, 123d, 123e and 123f are used or not used as connectors for transferring a driving signal.
On the contrary, the third, fourth, fifth and sixth terminals 123c, 123d, 123e and 123f can be used as connectors for transferring electric power. The first, second, seventh and eighth terminals 123a, 123b, 123g and 123h can be used or not used as connectors for transferring a driving signal.
FIGS. 10a and 10b show a coupling and separation process of a light source unit 300 and a coupling member 110 in accordance with an embodiment of the present invention.
First, as shown in FIG. 10a, in the light source unit 300, an angle between the first body 310a and the second body 310b is reduced by applying a first force F to the first body 310a and the second body 310b which are coupled such that they can rotate about the lower part of the light source unit 300. Here, the direction of the first force F is reverse to the directioied by the spring 340. When the lower parts of the first and the second coupling units 315a and 315b are pressed by applying the first force F, a space between the first and the second coupling units 315a and 315b is reduced, so that an angle between the first body 310a and the second body 310b is reduced.
If the first force F is not applied, a space between the first body 310a and the second body 310b is widened by the elastic force applied by the spring 340, so that it is difficult to insert the light source unit 300 into the insertion groove 112 of the coupling member 110.
As mentioned above, as a space between the first and the second coupling units 315a and 315b is reduced, the first and the second bodies 310a and 310b approach close to or come in contact with both sides of the middle body 320. Here, a limit switch 323 detects the motions of the first and the second bodies 310a and 310b and becomes in an off-state, and then disconnects the electric power supplied to the light emitting diode 312.
In general, a lighting device such as a fluorescent lamp can be replaced while the lighting device is connected to a power supply. However, when a lighting device using the light emitting diode 312 is connected to a power supply and is replaced, the light emitting diode 312 may be damaged. To overcome such a problem, through the use of the limit switch 323, the lighting device according to the embodiment recognizes an operation in which the first and the second bodies 310a and 310b move toward the middle body 320 as an operation of replacing the light source. As a result, during the operation of replacing the light source, it is possible to disconnect the electric power supplied to the light emitting diode 312.
As shown in FIG. 10b, as the first force F is applied to the first and the second bodies 310a and 310b, the light source unit 300 is inserted into the insertion groove 112 of the coupling member 110. Here, if the first force F is not applied, a space between the first and the second bodies 310a and 310b is widened again, so that the projection 313 is inserted into the third groove 113 formed on the inner surface of the insertion groove 112. As a result, the light source unit 300 can be coupled to the coupling member 110.
When the light source unit 300 is inserted into the coupling member 110, the spring 340 disposed between the first body 310a and the second body 310b pushes the first body 310a and the second body 310b, causing the projections 313 to be more securely coupled to the third groove 113.
The spring 340 gives continuously a uniform pressure to a contact surface formed by causing the first coupling unit 315a and the second coupling unit 315b to be contact with the insertion groove 112. Therefore, heat generated from the light source unit 300 can be more efficiently transferred through the contact surface mentioned above.
As described above, when the light source unit 300 is thoroughly coupled to the coupling member 110, the space between the first and the second bodies 310a and 310b is widened again by the elastic force from the spring 340. The limit switch 323 hereby recognizes that the operation of replacing the light source is completed and becomes in an off-state, and then connects again the electric power supplied to the light emitting diode 312.
When the light source unit 300 is required to repair, the light source unit 300 can be separated from the coupling member 110.
In separating the light source unit 300 from the coupling member 110, after the angle between the first body 310a and the second body 310b is reduced by applying the first force F to the first body 310a and the second body 310b, the light source unit 300 is separated from the coupling member 110.
FIG. 11a shows how a mechanical limit switch according to an embodiment is operated. FIG. 11b shows how a sensor type limit switch according to an embodiment is operated.
The limit switch according to the embodiment is able to employ a mechanical limit switch or a sensor type limit switch.
When the first force F is applied to the first and the second bodies 310a and 310b, the first and the second bodies 310a and 310b rotate in the direction of the middle body 320, so that the inner surfaces of the first and the second bodies 310a and 310b approach close to both sides of the middle body 320 respectively. When the first and the second bodies 310a and 310b approach close to both sides of the middle body 320 to a certain extent respectively, the limit switch 323 contacts with the first and the second bodies 310a and 310b, as illustrated in FIG. 14. Here, the limit switch 323 disposed on both sides of the middle body 320 is pressed through the use of button by the first and the second bodies 310a and 310b and becomes in an off-state. In this case, the limit switch 323 is capable of electrically separating the second connection terminal 330 from the light emitting diode 312.
Next, after the light source unit 300 is completely coupled to the coupling member 110, a distance between the first body 310a and the second body 310b is increased. As a result, the limit switch 323 becomes in an on-state, so that the second connection terminal 330 may be electrically connected again to the light emitting diode 312.
When the first force F is applied to the first and the second bodies 310a and 310b, the first and the second bodies 310a and 310b rotate in the direction of the middle body 320, so that the inner surfaces of the first and the second bodies 310a and 310b approach close to both sides of the middle body 320 respectively. Here, the limit switch 323 disposed on both sides of the middle body 320 detects the motions of the first and the second bodies 310a and 310b. 
There are two kinds of the aforementioned detecting method. One is a method using the intensity of pressure applied by the first and the second bodies 310a and 310b and the other is a method using a magnetic field intensity measured from the first and the second bodies 310a and 310b. 
The limit switch 323 using the intensity of pressure may include a pressure sensor. Such a limit switch 323 measures the intensity of pressure applied by the first and the second bodies 310a and 310b. If the measured intensity of pressure is greater than a predetermined intensity of pressure, the limit switch 323 becomes in an off-state. Here, the limit switch 323 recognizes that the light source is replaced and may generate a control signal for disconnecting the electric power supplied to the light source 300.
Subsequently, when the first connection terminal 120 is connected to the second connection terminal 330, the control signal generated by the limit switch 323, as shown in FIG. 11b, may be output to the power supply unit 400 through the first connection terminal 120 and the second connection terminal 330. As a result, the power supply unit 400 is hereby able to disconnect the electric power output based on the control signal.
After the light source 300 is completely coupled to the coupling member 110, as the first force F is decreased, a distance between the limit switch 323 and both the first and the second bodies 310a and 310b is increased. Since the first and the second bodies 310a and 310b are further from the limit switch 323, the intensity of pressure applied by the first and the second bodies 310a and 310b becomes lower than a predetermined intensity of pressure. In this case, the limit switch 323 becomes in an on-state, the control signal is not output. In such a case, the second connection terminal 330 may be electrically connected again to the light emitting diode 312.
The limit switch 323 using the magnetic field intensity may include a magnetic sensor. The limit switch 323 using the magnetic field intensity has the same electrical operation method as that of the limit switch 323 using the pressure sensor. However, in case of the limit switch 323 using the magnetic sensor, a magnet is provided on the inner surfaces of the first and the second bodies 310a and 310b. The position of the magnet corresponds to the position of the magnetic sensor. Accordingly, it is possible to measure the magnetic field intensity according to a distance between the middle body 320 and the first and the second bodies 310a and 310b. 
The limit switch 323 using the magnetic sensor is able to recognize the existence, approach and location of an object through a non contact method. The limit switch 323 using the non contact method may be produced by using various proximity sensors as well as the aforementioned magnetic sensor.
Meanwhile, the middle body 320 may include a separate power supply for starting and operating the limit switch 323.
According to the embodiment, when the light source unit 300 is required to be disposed or replaced for maintenance, it is possible to safely attach or remove the light source unit 300 by using the limit switch 323 even though the lighting device is in a live status.
FIGS. 12 and 13 are cross sectional views of a light source unit 300 and a coupling member 110 of a lighting device in accordance with a modified embodiment of the present invention. In description of the lighting device 1 according to a modified embodiment, repetitive descriptions thereof will be omitted.
Referring to FIGS. 12 and 13, a plurality of the third grooves 113a, 113b and 113c are formed on the inner surface of the insertion groove 112 of the coupling member 110 of the lighting device 1. While the three third grooves 113a, 113b and 113c are shown, there is no limit to the number of the third grooves.
The light source unit 300 is inserted into and coupled to the insertion groove 112. Here, the projection 313 of the upper part of the light source unit 300 is inserted into one of a plurality of the third grooves 113a, 113b and 113c, so that the light source unit 300 is strongly coupled to the coupling member 110.
As shown in FIG. 11, depths of a plurality of the third grooves 113a, 113b and 113c are different from each other, it is possible to diversely adjust the light distribution of the lighting device 1 in accordance with one of a plurality of the third grooves 113a, 113b and 113c into which the projection 313 of the light source unit 300 is inserted.
As shown in FIG. 12, the insertion groove 112 has a sloping inner surface. When a plurality of the third grooves 113a, 113b and 113c are formed on the sloping inner surface of the insertion groove 112, an angle between the first body 310a and the second body 310b of the light source unit 300 varies in accordance with one of a plurality of the third grooves 113a, 113b and 113c into which the projection 313 of the light source unit 300 is inserted. Therefore, it is possible to diversely adjust the light distribution of the lighting device 1.
As described above, it is possible to diversely adjust the light distribution of the lighting device 1 by forming a plurality of the third grooves 113a, 113b and 113c on the inner surface of the insertion groove 112. As a result, even though a width or curvature of the reflector 200 changes, it is possible to provide an efficient lighting without changing the light source unit 300.
As described above, it will be appreciated by those skilled in the art that the present invention may be embodied in other specific forms without departing from its spirit or essential characteristics.
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.

## Claims

1. A lighting device comprising:
a first body including a first surface and one or more ends;
a second body including a second surface and one or more ends;
a plurality of light emitting diodes disposed on the first surface and the second surface;
a coupler that is disposed at one or more of the ends of the first and the second bodies; and
a limit switch connecting and disconnecting electric power supplied to the plurality of the light emitting diodes in accordance with change of a distance between the first body and the second body.

2. The lighting device of claim 1, further comprising a middle body being disposed between the first body and the second body and including a connection terminal and one or more ends,
wherein at least one groove is formed at one or more ends of the first body, the second body and the middle body, respectively,
wherein the coupler includes at least three protrusions formed therein which are inserted into the grooves formed on the ends of the first body, the second body and the middle body,
wherein the one groove of the first body is coupled to one of the protrusions of the coupler,
and wherein the one groove of the second body is coupled to another of the protrusions of the coupler.

3. The lighting device of claim 2, wherein the limit switch is a mechanical switch and the limit switch electrically isolates the connection terminal from the plurality of the light emitting diodes by disconnecting the electrical connection between the middle body and the first body and the electrical connection between the middle body and the second body.

4. A lighting device comprising:
a housing;
a light source unit;
a coupling member being coupled to the housing and including an insertion groove; and
at least one reflector placed between the housing and the coupling member,
wherein the light source unit includes:
a first body including a first coupling unit coupled to the coupling member and including a first surface inclined toward the reflector;
a plurality of light emitting diodes disposed on the first surface;
a third body electrically connected to the first body; and
a limit switch connecting and disconnecting electric power supplied to the plurality of the light emitting diodes in accordance with a change in a distance between the first body and the third body.

5. The lighting device of claim 4, wherein a first connection terminal is disposed within the insertion groove,
wherein the third body comprises at least one of a second body and a middle body in which a second connection terminal electrically connected to the first connection terminal is disposed, and
wherein the second body is symmetrical to the first body.

6. The lighting device of claim 4, wherein the first coupling unit includes a projection, wherein the inner wall surface of the insertion groove has a plurality of grooves, wherein the projection is inserted into at least one of the plurality of grooves so that the light source unit is coupled to the coupling member.

7. The lighting device of claim 4, further comprising a coupler that is disposed at least one or more ends of the first body and the third body, respectively.

8. The lighting device of claim 7, wherein a first connection terminal is disposed within the insertion groove,
wherein the third body comprises a second body symmetrical to the first body and a middle body in which a second connection terminal electrically connected to the first connection terminal is disposed,
wherein at least one groove is formed at one or more ends of both ends of the first body, the second body and the middle body, respectively,
wherein the coupler includes at least three protrusions formed thereat which are inserted into the grooves formed on the ends of the first body, the second body and the middle body, respectively.

9. The lighting device of claim 8, wherein the light source unit further comprises a spring being disposed on the middle body and disposed between the first body and the second body, and providing an elastic force to the first body and the second body, wherein the elastic force widens a space between the first body and the second body.

10. The lighting device of claim 8, wherein when the first and the second bodies rotate in the direction of the middle body, so that the limit switch is pressed by the first and the second bodies, the limit switch is a mechanical switch that electrically isolates the second connection terminal from the plurality of the light emitting diodes by disconnecting the electrical connection between the middle body and the first body and the electrical connection between the middle body and the second body.

11. The lighting device of claim 4, wherein the reflector has a parabola-shaped surface.

12. The lighting device of claim 11, further comprising a power supply unit that is disposed in a space between the reflector and the housing, and supplies one or both of electric power and a driving signal to the light source unit when the light source unit is coupled to the coupling member.

13. The lighting device of claim 12, wherein the limit switch comprises a pressure sensor, and wherein if the intensity of pressure applied by the first body and the third body is greater than that of a predetermined pressure, when the light source unit is coupled to the coupling member, the pressure sensor outputs to the power supply unit a control signal for disconnecting the electric power supplied to the light source unit.

14. The lighting device of claim 12, further comprising a magnet disposed on one side of the first body, wherein the limit switch includes a magnetic sensor, wherein the magnetic sensor measures the intensity of the magnetic field generated by the magnet of the first body, and wherein if the measured intensity of the magnetic field is greater than that of a predetermined magnetic field, when the light source unit is coupled to the coupling member, the magnetic sensor outputs to the power supply unit a control signal for disconnecting the electric power supplied to the light source unit.