Patent Publication Number: US-2016230954-A1

Title: Optical device and a light source module having the same

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority under 35 U.S.C. §119 to Korean Patent Application No. 10-2015-0019466, filed on Feb. 9, 2015, in the Korean Intellectual Property Office, the disclosure of which is incorporated by reference herein in its entirety. 
     TECHNICAL FIELD 
     The present inventive concept relates to an optical device and a light source module having the same. 
     DISCUSSION OF THE RELATED ART 
     A wide-beam angle lens is a type of lens used in light emitting device packages to allow light to be widely diffused. Light incident to a central portion of the wide-beam angle lens is diffused laterally by refraction. However, in a case in which the light incident to the lens is not uniformly distributed due to various types of light sources included in light emitting device packages, a partial increase in brightness distribution may occur. As such, optical non-uniformity defects such as Mura may occur. 
     SUMMARY 
     According to an exemplary embodiment of the present inventive concept, an optical device includes a first surface including a light incident surface onto which light is incident, and a second surface which emits light passing through the light incident surface. The light incident surface includes a first curved surface and a second curved surface. The first curved surface is disposed in a recess in a central portion of the light incident surface and recessed toward the second surface, the second curved surface being connected to the first curved surface in the recess and extended from the recess. The first and second curved surfaces have an inflection point at a contact point at which the first and second curved surfaces contact each other. The second surface opposes the first surface, and the first and second surfaces form a biconvex lens structure. 
     In an exemplary embodiment of the present inventive concept, an optical axis passes through the recess. 
     In an exemplary embodiment of the present inventive concept, a shape of the light incident surface satisfies conditions 1 to 3: 
     Condition 1: dR/dθ&lt;0 for θ≦55° 
     Condition 2: dR/dθ=0 for 55°&lt;θ&lt;65° 
     Condition 3: dR/dθ&gt;0 for 65°≦θ 
     where, when an intersection point between an optical axis passing through the recess and a light emission surface of a light source is defined as a reference point “O”, “R” refers to a straight line connecting the reference point and a point of the light incident surface to each other, and “θ” refers to an angle formed by the straight line “R” with respect to the optical axis. 
     In an exemplary embodiment of the present inventive concept, the shape of the light incident surface satisfies conditions 4 to 6: 
     Condition 4: θ2/θ1&gt;1 for θ1≦55° 
     Condition 5: θ2/θ1=1 for 55°&lt;θ1&lt;65° 
     Condition 6: θ2/θ1&lt;1 for 65°≦θ1 
     where “θ1” refers to a light emission angle formed by light emitted from the light source with respect to the optical axis, and “θ2” refers to a refraction angle of the light having the light emission angle “θ1”, which is refracted from the light incident surface toward the second surface, with respect to the optical axis. 
     In an exemplary embodiment of the present inventive concept, the optical device further includes a flange portion disposed between the first surface and the second surface at an edge of the optical device, and a thickness “Tf” of the optical device measured from a bottom surface of the optical device to a center of the flange portion in a vertical direction corresponds to ⅓ to ½ of an overall thickness “Tt” of the optical device. 
     In an exemplary embodiment of the present inventive concept, when an intersection point between an optical axis passing through the recess and a light emission surface of a light source is a reference point “O”, a first ray of light emitted from “O” and having a first angle with respect to the optical axis is refracted downward by the light incident surface, and a second ray of light emitted from “O” and having a second angle with respect to the optical axis is refracted upward by the light incident surface. The first angle is smaller than the second angle. 
     In an exemplary embodiment of the present inventive concept, the second surface includes a concave portion recessed toward the recess of the first surface, and a convex portion extended from an edge of the concave portion to an edge of the optical device. 
     In an exemplary embodiment of the present inventive concept, the optical device further includes a support portion disposed on the first surface. 
     According to an exemplary embodiment of the present inventive concept, an optical device includes a first surface including a recess disposed in a central portion of the first surface, and a second surface that faces the first surface to form a biconvex lens. The recess is recessed toward the second surface and includes a light incident surface onto which light is incident. The light incident surface includes a first curved surface and a second curved surface, the first curved surface being disposed in the recess in the central portion of the first surface and recessed toward the second surface, the second curved surface being connected to the first curved surface in the recess and extended from the recess. The first and second curved surfaces have an inflection point at a contact point at which the first and second curved surfaces contact each other. 
     In an exemplary embodiment of the present inventive concept, a sidewall of the recess has an approximate S-shaped vertical cross-section. 
     According to an exemplary embodiment of the present inventive concept, a light source module includes a light source, and an optical device including a first surface and a second surface. The first surface is disposed above the light source and includes a recess formed in a central portion of the first surface and recessed toward the second surface, and the second surface opposes the first surface to form a biconvex lens. Wherein the recess includes a light incident surface onto which light from the light source is incident. The light incident surface includes a first curved surface and a second curved surface, the first curved surface being disposed in the recess in the central portion of the first surface and recessed toward the second surface, the second curved surface being connected to the first curved surface in the recess and extended from the recess. The first and second curved surfaces have an inflection point at a contact point where the first and second curved surfaces contact each other. 
     In an exemplary embodiment of the present inventive concept, a size of an opening of the recess is greater than a size of the light source. 
     In an exemplary embodiment of the present inventive concept, the light source is a light emitting diode (LED) chip or a light emitting diode package in which the light emitting diode chip is disposed. 
     In an exemplary embodiment of the present inventive concept, the light source includes an encapsulation part encapsulating the light emitting diode chip. 
     In an exemplary embodiment of the present inventive concept, the light source module further includes a substrate on which the light source and the optical device are disposed. 
     According to an exemplary embodiment of the present inventive concept, an optical device includes a first surface comprising, in cross-sectional view, a first convex portion, a second convex portion, and a first concave portion disposed therebetween, and a second surface comprising, in the cross-sectional view, a third convex portion, a fourth convex portion, and a second concave portion disposed therebetween. The first surface and the second surface face each other. The first concave portion and the second concave portion protrude toward each other. The first concave portion includes a first sidewall and a second sidewall that face each other. The first sidewall includes a first region and a second region. Light passing through the first region is refracted downward with respect to its original direction, and light passing through the second region is refracted upward with respect to its original direction. 
     In an exemplary embodiment of the present inventive concept, the first region of the first sidewall forms a bottom of a recess and the second region of the first sidewall forms an opening of the recess. 
     In an exemplary embodiment of the present inventive concept, the first surface and the second surface are connected to each other with a pair of flanges. 
     In an exemplary embodiment of the present inventive concept, light is emitted through the first surface to the second surface. 
     In an exemplary embodiment of the present inventive concept, the light is incident to the first concave portion of the first surface. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other features of the present inventive concept will become more apparent by describing in detail exemplary embodiments thereof in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a schematic perspective view of a light source module including an optical device, according to an exemplary embodiment of the present inventive concept; 
         FIG. 2  is a cross-sectional view of  FIG. 1 , according to an exemplary embodiment of the present inventive concept; 
         FIG. 3  is a cross-sectional view schematically illustrating an enlarged light incident surface of the optical device of  FIG. 2 , according to an exemplary embodiment of the present inventive concept; 
         FIG. 4  is a cross-sectional view illustrating a relationship between an angle of incidence and a refraction angle of the light incident surface of the optical device of  FIG. 3 , according to an exemplary embodiment of the present inventive concept; 
         FIG. 5  is a cross-sectional view schematically illustrating an optical path of light emitted from the light source of  FIG. 2  and passing through the optical device of  FIG. 2 , according to an exemplary embodiment of the present inventive concept; 
         FIG. 6A  is a cross-sectional view schematically illustrating an optical path of light refracted at a first surface of the optical device of  FIG. 2  and emitted externally, according to an exemplary embodiment of the present inventive concept; 
         FIG. 6B  is a cross-sectional view schematically illustrating an optical path of light refracted at a first surface of the optical device of  FIG. 2  and emitted externally, according to an exemplary embodiment of the present inventive concept; 
         FIG. 7A  is a cross-sectional view schematically illustrating a light source module, according to an exemplary embodiment of the present inventive concept; 
         FIG. 7B  is a plan view schematically illustrating the light source module of  FIG. 7A , according to an exemplary embodiment of the present inventive concept; 
         FIG. 8  is a schematic perspective view illustrating a state in which a light source and an optical device are mounted on a substrate of  FIG. 7A , according to an exemplary embodiment of the present inventive concept; 
         FIG. 9  is a cross-sectional view schematically illustrating a light source, according to an exemplary embodiment of the present inventive concept; 
         FIG. 10  illustrates a CIE 1931 chromaticity coordinates system for illustrating a wavelength conversion material employable in an exemplary embodiment of the present inventive concept; 
         FIG. 11  is a schematic diagram illustrating a cross-sectional structure of a quantum dot (QD), according to an exemplary embodiment of the present inventive concept; 
         FIG. 12  is a cross-sectional view illustrating a light emitting diode (LED) chip used as a light source, according to an exemplary embodiment of the present inventive concept; 
         FIG. 13A  is a plan view illustrating an LED chip used as a light source, according to an exemplary embodiment of the present inventive concept; 
         FIG. 13B  is a side cross-sectional view of the LED chip of  FIG. 13A , taken along line I-I′ of  FIG. 13A , according to an exemplary embodiment of the present inventive concept; 
         FIG. 14  is a cross-sectional view illustrating an LED chip used as a light source, according to an exemplary embodiment of the present inventive concept; 
         FIG. 15  is a schematic perspective view and a cross-sectional view illustrating an LED chip, according to an exemplary embodiment of the present inventive concept; 
         FIG. 16  is a schematic cross-sectional view of a lighting device, according to an exemplary embodiment of the present inventive concept; 
         FIG. 17  is a schematic exploded perspective view of a bulb-type lighting device, according to an exemplary embodiment of the present inventive concept; and 
         FIG. 18  is a schematic exploded perspective view of a bar type lighting device, according to an exemplary embodiment of the present inventive concept; 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Exemplary embodiments of the present inventive concept will now be described more fully hereinafter with reference to the accompanying drawings. The present inventive concept may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. In the drawings, the sizes and relative sizes of layers and regions may be exaggerated for clarity. 
     It will be understood that when an element or layer is referred to as being “on,” “connected to” or “coupled to” another element or layer, it can be directly on, connected, or coupled to the other element or layer, or intervening elements or layers may be present. 
     As used herein, the singular forms “a,” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. 
     With reference to  FIGS. 1 and 2 , optical light source module including an optical device according to an exemplary embodiment of the present inventive concept will be described.  FIG. 1  is a schematic perspective view of a light source module including an optical device, according to an exemplary embodiment of the present inventive concept.  FIG. 2  is a cross-sectional view of  FIG. 1 , according to an exemplary embodiment of the present inventive concept. 
     With reference to  FIGS. 1 and 2 , a light source module  1 , according to an exemplary embodiment of the present inventive concept, may include a light source  10  and an optical device  20  disposed above the optical source  10 . In addition, the light source module  1  may include a substrate  30  on which the light source  10  and the optical device  20  are mounted. 
     The light source  10  may be provided as a photoelectric device for generating light having a predetermined wavelength through externally-supplied driving power. For example, the light source  10  may include a semiconductor light emitting diode (LED) having an n-type semiconductor layer, a p-type semiconductor layer, and an active layer disposed therebetween. 
     The light source  10  may emit blue light, green light or red light, according to a material contained in the light source  10  or according to a combination of phosphor with a material contained in the light source  10 . The light source  10  may also emit white light, ultraviolet light, or the like. A detailed configuration and structure of the light source  10  will be described in detail below. 
     The optical device  20  may be disposed above the light source  10  to cover the light source  10 . The optical device  20  may adjust an angle in a spread of beams of light emitted from the light source  10 . For example, the optical device  20  may include a wide-beam angle lens implementing a wide angle in a spread of light beams by allowing beams of light emitted by the light source  10  to be widely spread. 
       FIGS. 2 to 4  illustrate the optical device  20 , according to an exemplary embodiment of the present inventive concept. As illustrated in  FIG. 2 , the optical device  20  may include a first surface  21  having a light incident surface  23  onto which light emitted from the light source  10  is incident, and a second surface  22  for emitting the light transmitted to the optical device  20  through the light incident surface  23  externally. 
     The optical device  20  may include a flange portion  25  corresponding to an outer edge of the optical device  20  between the first surface  21  and the second surface  22 . The flange portion  25  may be formed as an outermost protruding portion and may have a predetermined thickness along a circumference of the optical device  20 . The first surface  21  and the second surface  22  may include the flange portion  25  therebetween and may be separated from each other by the flange portion  25 . 
     The optical device  20  may have a substantially biconvex lens structure in which the first surface  21  facing the light source  10  protrudes in a direction toward the light source  10  in a convex manner. The second surface  22  opposing the first surface  21  protrudes in a direction opposite to a direction in which the first surface  21  protrudes, in a convex manner. In other words, the optical device  20  may have a biconvex shape along a plane that is substantially perpendicular to the optical axis Z. The biconvex shape includes the first surface  21  which is a convex surface and the second surface  22  which is also a convex surface and opposite to the first surface  21 . Light emitted from the light source  10  enters the optical device  20  through the light incident surface  23  of the first surface  21  and exits the optical device  20  through the second surface  22 . 
     The optical device  20  may have a structure in which a thickness Tf thereof, from a bottom surface of the optical device  20  to a center of the flange portion  25 , corresponds to about ⅓ to about ½ of an overall thickness Tt of the optical device  20 . 
     The first surface  21  may be a surface provided above the light source  10  to face the light source  10  and may correspond to a bottom surface of the optical device  20 . A central portion of the first surface  21  through which an optical axis Z passes may be recessed toward the second surface  22 , to form a recess portion  24  forming the light incident surface  23 . In other words, the first surface  21  is a bottom surface of the optical device  20  and faces the light source  10 . The central portion of the first surface  21 , which corresponds to the light incident surface  23 , may be partially concave and partially convex. Light emitted from the light source  10  enters the optical device  20  through the light incident surface  23 . The central portion of the first surface  21  also corresponds to the recess portion  24 . 
     The recess portion  24  may have a rotationally symmetrical structure about the optical axis Z passing through a center of the optical device  20 , and a surface of the recess portion  24  may be defined as the light incident surface  23  onto which light emitted from the light source  10  is incident. Thus, light generated by the light source  10  may pass through the light incident surface  23  to enter the interior of the optical device  20 . 
     The recess portion  24  may be formed inwardly in the optical device  20  in a direction inwardly from the first surface  21 . In an opening of the recess portion  24 , a diameter of an end portion thereof, for example, the size of a transverse cross-section thereof exposed to the first surface  21  may be greater than that of the light source  10 . In other words, the recess portion  24  may be a cavity of the optical device  20  and may have a cross-section similar to a mathematical normal distribution (e.g., a Gaussian) line. The recess portion  24  may be disposed above the light source  10 . When a circumference of the recess portion  24  is measured along a plane that is substantially perpendicular to the optical axis Z, a first circumference of the recess portion  24 , which is proximate to the light source  10 , is greater than a second circumference of the recess portion  24 , which is distant to the light source  10 . The recess portion  24  may be provided above the light source  10  to face the light source  10  and to cover the light source  10 . 
     The light incident surface  23  may include a first curved surface  23   a  and a second curved surface  23   b  and may have an inflection point A at a contact point at which the first curved surface  23   a  and the second curved surface  23   b  contact each other. The first curved surface  23   a  may be a concavely curved surface formed by allowing a center thereof through which the optical axis Z passes to be recessed concavely toward the second surface  22 . In other words, the first curved surface  23   a  is concave. The optical axis Z passes through the center of the first curved surface  23   a . The second curved surface  23   b  may be a convexly curved surface extended from an edge of the first curved surface  23   a  to be connected to the first surface  21 . 
     As illustrated in  FIG. 2 , a transverse cross-section of the light incident surface  23  may have a bilaterally symmetrical structure with respect to the optical axis Z. For example, the first curved surface  23   a  and the second curved surface  23   b  may be symmetrical with respect to the optical axis Z. A vertical cross-sectional shape of a half of the light incident surface  23  may have an “S” shape. 
       FIGS. 3 and 4  are enlarged views illustrating a portion of the light incident surface  23 .  FIG. 3  is a cross-sectional view schematically illustrating an enlarged light incident surface  23  of the optical device  20  of  FIG. 2 , according to an exemplary embodiment of the present inventive concept.  FIG. 4  is a cross-sectional view illustrating a relationship between an angle of incidence and a refraction angle of the light incident surface  23  of the optical device  20  of  FIG. 3 , according to an exemplary embodiment of the present inventive concept. 
     As illustrated in  FIG. 3 , a shape of the light incident surface  23  may have a structure satisfying the following conditions 1 to 3. 
     Condition 1: dR/dθ&lt;0 within a range of 0°≦θ≦55°. 
     Condition 2: dR/dθ=0 within a range of 55°&lt;θ&lt;65°. 
     Condition 3: dR/dθ&gt;0 within a range of 65°≦θ. 
     For example, when an intersection point between the optical axis Z and a light emission surface of the light source  10  is defined as a reference point O, “R” refers to a straight line connecting the reference point O and an arbitrary point of the light incident surface  23  to each other, and “θ” refers to an angle formed by the straight line “R” with respect to the optical axis Z. 
     Based on the case of θ=0°, a change in a length of “R” may be a negative number as θ increases within a range of about θ≦55° and may be a positive number as θ increases within a range of θ≧65°. In other words, in the range of 0°≦θ≦55°, as θ increases, the length of “R” decreases. Thus, dR/dθ&lt;0 within a range of 0°≦θ≦55°. In the range of 65°≦θ, as θ increases, the length of “R” increases. Thus, dR/dθ&gt;0 within the range of 65°≦θ. In addition, the light incident surface  23  may have a shape in which a change in the length of “R” does not occur within a range of 55°&lt;θ&lt;65°. In other words, within the range of 55°&lt;θ&lt;65°, the length of “R” does not change as θ increases. A gradient of the light incident surface  23  is reversed within the range of 55°&lt;θ&lt;65°. 
     Further, as illustrated in  FIG. 4 , a shape of the light incident surface  23  may have a structure satisfying the following conditions 4 to 6 together with the conditions 1 to 3, or the shape of the light incident surface  23  may have a structure satisfying the following conditions 4 to 6 alone. 
     Condition 4: θ2/θ1&gt;1 within a range of 0°≦θ1≦55°. 
     Condition 5: θ2/θ1=1 within a range of 55°&lt;θ1&lt;65°. 
     Condition 6: θ2/θ1&lt;1 within a range of 65°≦θ1. 
     “θ1” refers to an angle of incidence of light formed by arbitrary light L emitted from the light source  10  and incident on the light incident surface  23 , with respect to the optical axis Z, and “θ2” refers a refraction angle of light formed by the light L having the angle of incidence θ1 refracted from the light incident surface  23  toward the second surface  22 , with respect to the optical axis Z. In other words, when point O falls along the optical axis Z, the light L emitted from point O has an angle “θ1” with respect to the optical axis Z, and when the light L enters the optical device  20 , the light L refracts to have an angle “θ2” with respect to the optical axis Z. 
     Light from the light source  10  may be spread on the light incident surface  23  within a range of 0°≦θ1≦55°, and be vertically incident on the light incident surface  23  within a range of 55°&lt;θ1&lt;65°. In other words, with the range of 55°&lt;θ1&lt;65°, “θ1” and “θ2” are equal. An optical path of light collected on the light incident surface  23  may be provided within a range of 65°≦θ1. The light incident surface  23  may have a structure having a cross-section that reverses the direction in which light L emitted from the light structure  10  is refracted 
       FIGS. 5, 6A and 6B  schematically illustrate optical paths in the optical device  20 , according to exemplary embodiments of the present inventive concept.  FIG. 5  is a cross-sectional view schematically illustrating an optical path of light emitted from the light source  10  of  FIG. 2  and passing through the optical device  20  of  FIG. 2 , according to an exemplary embodiment of the present inventive concept.  FIG. 6A  is a cross-sectional view schematically illustrating an optical path of light refracted at the first surface  21  of the optical device  20  of  FIG. 2  and emitted externally, according to an exemplary embodiment of the present inventive concept.  FIG. 6B  is a cross-sectional view schematically illustrating an optical path of light refracted at the first surface  21  of the optical device  20  of  FIG. 2  and emitted externally, according to an exemplary embodiment of the present inventive concept. 
     As illustrated in  FIG. 5 , the light incident surface  23  may be located on a central portion of the first surface  21  corresponding to a bottom surface of the optical device  20 , facing the substrate  30  on which the optical device  20  is mounted, according to an exemplary embodiment of the present inventive concept. The light incident surface  23  may have the first curved surface  23   a  and the second curved surface  23   b  connected to each other through the inflection point A. A vertical cross-sectional shape of the light incident surface  23  may have an “S” shape. In the case of the light incident surface  23  described above, light emitted from the light source  10  at a small angle with respect to the optical axis Z may be diffused through the light incident surface  23 . In addition, an optical path may be provided on which light emitted at a large angle with respect to the optical axis Z is collected inwardly of the optical device  20  in a direction in which a refraction direction of light is reversed once that the light enters the optical device  20 . For example, light entering the light incident surface  23  at a first large angle with respect to the optical axis Z is refracted in a first direction once it enters the optical device  20 . In addition, light entering the same side of the light incident surface  23  at a second large angle with respect to the optical axis Z is refracted in a second direction which crosses the first direction when the light enters the optical device  20 . Thus, unlike a general diffusion lens for only allowing for a uniform diffusion direction, a section B in which a refraction direction of light is reversed may be provided. Thus, a uniformity of brightness distribution in a central region of the optical device  20  is increased. 
     In addition, as illustrated in  FIGS. 6A and 6B , since the first surface  21 , which is the bottom surface of the optical device  20 , according to an exemplary embodiment of the present inventive concept, has a convex shape in a manner similar to that of the second surface  22  corresponding to a light emission surface, a portion of light, L 2 , reflected from the second surface  22  of light L 1  emitted from the light source  10 , may not be reflected a second time from the first surface  21 , but is refracted to be directly emitted externally of the optical device  20 . Thus, light may be spread across a wide lateral region. In other words, the first surface  21  may also function as a light emission surface, and a distance between the first surface  21  and the substrate  30  on which the optical device  20  is mounted may be secured, such that brightness distribution uniformity in a central portion of the optical device  20  may be increased. 
     With reference to  FIGS. 7A and 7B , the first surface  21  may further include a support portion  26  supporting the optical device  20 . The support portion  26  may be provided in plural and the plurality of support portions  26  may be spaced apart from one another along a circumference of the recess portion  24 . The optical device  20  may be disposed, for example, on the circuit board  30  through the support portion  26 . 
     The second surface  22  may be disposed to oppose the first surface  21 . The second surface  22  may be provided as a light emission surface and correspond to an upper surface of the optical device  20 , from which light having entered the interior of the optical device  20  through the light incident surface  23  is externally emitted. 
     As illustrated in  FIG. 2 , the second surface  22  may be shaped as a dome and may extend upwardly from an edge of the first surface  21  while having a structure in which a central portion of the structure of the second surface  22  is recessed toward the recess portion  24  at a location through which the optical axis Z passes. Thus, the second surface  22  includes a concave portion at a central portion thereof where the optical axis Z passes through. In other words, with reference to  FIG. 2 , the second surface  22  may have a concave portion  22   a  being recessed toward the first surface  21  to have a concavely curved surface, and a convex portion  22   b  having a convexly curved surface continuously extended from an edge of the concave portion  22   a  to an outer edge of the optical device  20 . 
     On the second surface  22 , a plurality of concave-convex portions  22   c  may be periodically arranged in a direction from the optical axis Z to the outer edge of the optical device  20 . The plurality of concave-convex portions  22   c  may have a ring shaped structure corresponding to a transverse cross-sectional shape of the optical device  20 , and may form concentric circles with respect to the optical axis Z. In addition, the plurality of concave-convex portions  22   c  may be arranged in a radially diffused form while forming a periodical pattern along a surface of the second surface  22 , based on the optical axis Z. 
     The plurality of concave-convex portions  22   c  may be spaced apart from one another by a predetermined pitch P to form a pattern. In this case, the pitch P between the plurality of concave-convex portions  22   c  may be within a range of about 0.01 mm to about 0.04 mm. The plurality of concave-convex portions  22   c  may compensate for a difference in performance between the optical devices  20  due to minute manufacturing errors that may occur in a process of manufacturing the optical devices  20 . Accordingly, uniformity of brightness distribution may be increased. 
     The optical device  20  may be formed using a resin material having light transmissivity which, for example, may contain polycarbonate (PC), polymethyl methacrylate (PMMA), an acrylic resin, or the like. In addition, the optical device  20  may be formed of glass, but exemplary embodiments of the present inventive concept are not limited thereto. 
     The optical device  20  may contain a light dispersion material within a range of about 3% to about 15%. The light dispersion material may include, for example, SiO 2 , TiO 2  or Al 2 O 3 . In a case in which the light dispersion material is contained in a content of less than 3%, light may not be sufficiently distributed such that light dispersion effects may not be expected. In addition, in a case in which the light dispersion material is contained in a content of more than 15%, an amount of light emitted outwardly from the optical device  20  may be reduced. Thus, light extraction efficiency may be reduced. 
     The optical device  20  may be formed using a method of injecting a liquid solvent into a mold to be solidified. For example, an injection molding method, a transfer molding method, a compression molding method, or the like, may be used. 
     The substrate  30  may be provided as a general flame retardant 4 (FR4) type printed circuit board (PCB) or a flexible PCB, and may be formed using an organic resin material containing epoxy, triagine, silicon rubber, polyimide, or the like, and other organic resin materials. The substrate  30  may also be formed using a ceramic material such as silicon nitride, AlN, Al 2 O 3  or the like, or formed using a metal or a metal compound as in a metal-core printed circuit board (MCPCB), a metal copper clad laminate (MCCL), or the like. 
       FIG. 7A  is a cross-sectional view schematically illustrating a light source module, according to an exemplary embodiment of the present inventive concept.  FIG. 7B  is a plan view schematically illustrating the light source module of  FIG. 7A , according to an exemplary embodiment of the present inventive concept. As illustrated in  FIGS. 7A and 7B , the substrate  30  may have a rectangular bar type structure having a lengthwise extended form, but exemplary embodiments of the present inventive concept are not limited thereto. The substrate  30  may have a variety of structures corresponding to a structure of a product mounted thereon. For example, the substrate  30  may also have a circular shaped structure. 
       FIG. 8  is a schematic perspective view illustrating a state in which a light source  10  and an optical device  20  are mounted on a substrate  30  of  FIG. 7A , according to an exemplary embodiment of the present inventive concept. As illustrated in  FIG. 8 , fiducial marks  31  and a light source mounting region  32  may be provided on the substrate  30 . The fiducial marks  31  and the light source mounting region  32  may respectively demarcate mounting positions of the optical device  20  and the light source  10  on the substrate. For example, a plurality of the fiducial marks  31  may be disposed along a circumference of each light source mounting region  32  on the substrate  30 . 
     The light source  10  may be provided in plurality. The plurality of light sources  10  may be respectively mounted on the light source mounting regions  32 , and may be arranged in a lengthwise direction of the substrate  30 . In addition, the number of the optical devices  20  may correspond to the number of the light sources  10 , and the optical devices  20  may be mounted on the substrate  30  in a structure respectively covering the light sources  10  using the fiducial marks  31  of the respective light source mounting regions  32 . 
     With reference to  FIGS. 7A and 7B , a connector  40  for forming a connection between the plurality of light sources  10  and an external power source may be disposed on the substrate  30 . The connector  40  may be mounted on an end region of the substrate  30 . In addition, a circuit wiring, electrically connected to the light source  10 , may be provided on the substrate  30 . 
     As the light source  10 , LED chips having a variety of structures or an LED package in which the LED chips are mounted may be used. 
       FIG. 9  is a cross-sectional view schematically illustrating a light source, according to an exemplary embodiment of the present inventive concept As illustrated in  FIG. 9 , the light source  10  may include, for example, a package structure in which an LED chip  11  is mounted within a package body  12  having a reflective cup  13  therein. In addition, the LED chip  11  may be covered by an encapsulation part  14  containing phosphor. In the exemplary embodiment of the present inventive concept, the light source  10  has an LED package form. However, the present inventive concept is not limited thereto. 
     The package body  12  may be provided as a base member in which the LED chip  11  is mounted on and supported thereby. The package body  12  may be formed using a white molding compound having high light reflectivity. The white molding compound of the package body  12  can increase the amount of light that is emitted externally of the package body  12  by reflecting the light emitted from the LED chip  11 . Such a white molding compound may include a thermosetting resin-based material having high heat resistance or a silicon resin-based material. In addition, a white pigment and a filling material, a hardener, a mold release agent, an antioxidant, an adhesion improver, or the like, may be added to the thermoplastic resin-based material. In addition, the package body  12  may also be formed using FR4, composite epoxy materials 3 (CEM-3), an epoxy material, a ceramic material, or the like. The package body  12  may also be formed using a metal such as aluminum (Al). 
     The package body  12  may include a lead frame  15  for an electrical connection to an external power source. The lead frame  15  may be formed using a material having good electrical conductivity, for example, a metal such as aluminum, copper, or the like. When the package body  12  is formed using a metal, an insulation material may be interposed between the package body  12  and the lead frame  15 . 
     In the case of the reflective cup  13  provided in the package body  12 , the lead frame  15  may be exposed to a bottom surface of the reflective cup  13  on which the LED chip  11  is mounted. The LED chip  11  may be electrically connected to the exposed lead frame  15 . 
     The reflective cup  13  may have a structure in which an area of a transverse cross-section of a surface thereof exposed to an upper part of the package body  12  is greater than that of a bottom surface of the reflective cup  13 . The surface of the reflective cup  13  exposed to the upper part of the package body  12  may be defined as a light emission surface of the light source  10 . 
     The LED chip  11  may be sealed by the encapsulation part  14  formed in the reflective cup  13  of the package body  12 . The encapsulation part  14  may contain a wavelength conversion material. 
     The wavelength conversion material may include, for example, one or more phosphors which are excited by light generated by the LED chip  11 . The excited one or more phosphors emit light having a different wavelength than the wavelength of the light emitted by the LED chip  11 . The encapsulation part  14  may also include the wavelength conversion material so that light having various colors as well as white light may be emitted through control of the light emitted by the LED chip  11 . 
     For example, when the LED chip  11  emits blue light, white light may be emitted through a combination of yellow, green, red and/or orange phosphors included in the wavelength conversion material. In addition, an LED chip  11  emitting violet, blue, green, red or infrared light may be included in the light source  10 . In this case, the LED chip  11  may perform controlling of the light so that a color rendering index (CRI) of emitted light may be controlled to be within a range of about 40 to about 100. In addition, the LED chip  11  may emit various types of white light having a color temperature of about 2000K to about 20000K. In addition, color may be adjusted to be appropriate for an ambient atmosphere or for people&#39;s moods by generating visible violet, blue, green, red or orange light as well as infrared light, as needed. Further, light within a special wavelength band, capable of promoting growth of plants, may also be generated. 
       FIG. 10  illustrates a CIE 1931 chromaticity coordinates system for illustrating a wavelength conversion material employable in an exemplary embodiment of the present inventive concept. White light obtained by combining yellow, green, and red phosphors, and/or green, red, and blue LED chips may have two or more peak wavelengths. Referring to  FIG. 10 , coordinates in format (x, y) including (0.4476, 0.4074), (0.3484, 0.3516), (0.3101, 0.3162), (0.3128, 0.3292), and (0.3333, 0.3333) are located in line segments connected to one another on the CIE 1931 chromaticity coordinates system. Alternatively, the coordinates (x, y) may be located in a region surrounded by the line segments and black body radiation spectrum. A color temperature of the white light may be within a range of about 2000K to about 20000K. 
     Phosphors may be represented by the following empirical formulae and have a color as described below. 
     Oxide-based Phosphors: Yellow and green Y 3 Al 5 O 12 :Ce, Tb 3 Al 5 O 12 :Ce, Lu 3 Al 5 O 12 :Ce. 
     Silicate-based Phosphors: Yellow and green (Ba,Sr) 2 SiO 4 :Eu, Yellow and yellowish-orange (Ba,Sr) 3 SiO 5 :Ce. 
     Nitride-based Phosphors: Green β-SiAlON:Eu, yellow La 3 Si 6 N 11 :Ce, yellowish-orange α-SiAlON:Eu, red CaAlSiN 3 :Eu, Sr 2 Si 5 N 8 :Eu, SrSiAl 4 N 7 :Eu, SrLiAl 3 N 4 :Eu, Ln 4−x (Eu z M 1−z ) x Si 12−y Al y O 3+x+y N 18−x−y  (0.5≦x≦3, 0&lt;z&lt;0.3, 0&lt;y≦4) (e.g Ln is a group IIIa element or a rare-earth element, and M is Ca, Ba, Sr or Mg). 
     Fluoride-based Phosphors: KSF-based red K 2 SiF 6 :Mn 4+ , K 2 TiF 6 :Mn 4+ , NaYF 4 :Mn 4+ , NaGdF 4 :Mn 4+ . 
     A composition of phosphors should conform to stoichiometry, and respective elements may be substituted with other elements in respective groups of the periodic table of elements. For example, Sr may be substituted with Ba, Ca, Mg, or the like, of an alkaline earth group II, and Y may be substituted with lanthanum-based Tb, Lu, Sc, Gd, or the like. In addition, Eu or the like, an activator, may be substituted with Ce, Tb, Pr, Er, Yb, or the like, according to a required level of energy. Further, an activator alone, or a sub-activator or the like, may be used for modification of characteristics thereof. 
     In the case of a fluoride-based red phosphor, to increase reliability of the fluoride-based red phosphor under conditions of high temperature and high humidity, phosphors may be coated with a fluoride not containing Mn. In addition, a phosphor surface or a fluoride-coated surface of phosphors that is coated with fluoride not containing Mn may further be coated with an organic material. In the case of the fluoride-based red phosphor as described above, a narrow full width at half maximum of 40 nm or less may be obtained, unlike in the case of other phosphors. The fluoride-based red phosphors may be used in high-resolution television (TV) sets such as ultra-high-definition (UHD) TVs. 
     In the wavelength conversion material, a material such as a quantum dot (QD) may be used to substitute phosphor. In addition, a mixture of a phosphor and QD may be used in the wavelength conversion material. 
       FIG. 11  is a schematic diagram illustrating a cross-sectional structure of a QD, according to an exemplary embodiment of the present inventive concept. The QD may have a core-shell structure using a group III-V or group II-VI compound semiconductor. For example, the QD may have a core formed using CdSe, InP, or the like, and a shell formed using ZnS, ZnSe, or the like. Further, the QD may have a ligand for stabilization of the core and the shell. For example, the core may have a diameter ranging from approximately 1 nm to approximately 30 nm. In an exemplary embodiment of the present inventive concept, the core may have a diameter ranging from approximately 3 nm to approximately 10 nm. The shell may have a thickness ranging from approximately 0.1 nm to approximately 20 nm. 
     The QD may have various colors depending on the size thereof. In a case in which the QD is used as a phosphor substitute, the Qd may be used as a red or green phosphor. When using the QD, a narrow full width at half maximum of, for example, about 35 nm, may be obtained. 
     In the exemplary embodiment of the present inventive concept, the wavelength conversion material is included in the encapsulation part  14 . However, the present inventive concept is not limited thereto. For example, the wavelength conversion material may be included in a film. The film including the wavelength conversion material may be attached to a surface of the LED chip  11 . In this case, the application of the wavelength conversion material having a uniform thickness may be facilitated. 
       FIG. 12  is a cross-sectional view illustrating an LED chip used as a light source, according to an exemplary embodiment of the present inventive concept. With reference to  FIGS. 12 to 15 , various LED chips used as light sources will be described, according to exemplary embodiments of the present inventive concept. 
     With reference to  FIG. 12 , an LED chip  100  may include a growth substrate  111 , a first conductivity-type semiconductor layer  114 , an active layer  115 , and a second conductivity-type semiconductor layer  116 , sequentially stacked on the growth substrate  111 . A buffer layer  112  may be disposed between the growth substrate  111  and the first conductivity-type semiconductor layer  114 . 
     The growth substrate  111  may be provided as an insulating substrate such as a sapphire substrate, but the present inventive concept is not limited thereto. In addition, the growth substrate  111  may be provided as a conductive or semiconductor substrate. For example, the growth substrate  111  may be formed using SiC, Si, MgAl 2 O 4 , MgO, LiAlO 2 , LiGaO 2 , or GaN as well as sapphire. 
     The buffer layer  112  may be formed of In x Al y Ga 1−x−y N (0≦x≦1, 0≦y≦1, 0≦x+y≦1). For example, the buffer layer  112  may be formed using GaN, AlN, AlGaN, or InGaN. The buffer layer  112  may be formed by combining a plurality of layers or gradually changing a composition as required. 
     The first conductivity-type semiconductor layer  114  may be provided as a nitride semiconductor being an n-type semiconductor In x Al y Ga 1−x−y N (0≦x&lt;1, 0≦y&lt;1, 0≦x+y&lt;1), and an n-type impurity of the n-type semiconductor may be silicon (Si). For example, the first conductivity-type semiconductor layer  114  may contain an n-type GaN layer. 
     According to the exemplary embodiment of the present inventive concept, the first conductivity-type semiconductor layer  114  may include a first conductivity-type semiconductor contact layer  114   a  and a current diffusion layer  114   b . An impurity concentration of the first conductivity-type semiconductor contact layer  114   a  may be within a range of about 2×10 18  cm −3  to about 9×10 19  cm −3 . A thickness of the first conductivity-type semiconductor contact layer  114   a  may be within a range of about 1 μm to about 5 μm. The current diffusion layer  114   b  may have a structure in which a plurality of In x Al y Ga (1−x−y) N (0≦x, y≦1, 0≦x+y≦1) layers having different compositions or different impurity contents are repeatedly stacked. For example, the current diffusion layer  114   b  may be an n-type super-lattice layer having a structure in which an n-type GaN layer having a thickness of about 1 nm to about 500 nm and/or two or more layers formed of Al x In y Ga z N (0≦x,y,z≦1, except for x=y=z=0) and having different compositions are repeatedly stacked. An impurity concentration of the current diffusion layer  114   b  may be approximately 2×10 18  cm 3  to approximately 9×10 19  cm 3 . The current diffusion layer  114   b  may further include an insulation material layer as needed. 
     The second conductivity-type semiconductor layer  116  may be provided as a nitride semiconductor layer being a p-type semiconductor In x Al y Ga 1−x−y N (0≦x&lt;1, 0≦y&lt;1, 0≦x+y&lt;1), and a p-type impurity of the p-type semiconductor may be Mg. For example, the second conductivity-type semiconductor layer  116  may have a single layer structure, or a multilayer structure having different compositions as illustrated in the exemplary embodiment of the present inventive concept. As illustrated in  FIG. 12 , the second conductivity-type semiconductor layer  116  may include an electron blocking layer (EBL)  116   a , a low concentration p-type GaN layer  116   b , and a high concentration p-type GaN layer  116   c  provided as a contact layer. For example, the EBL  116   a  may have a structure in which a plurality of In x Al y Ga (1−x−y) N (0≦x≦1, 0≦y≦1, 0≦x+y≦1) layers having different compositions and having a thickness within a range of about 5 nm to about 100 nm are stacked, or may have a single layer formed of Al y Ga (1−y) N (0&lt;y≦1). An energy band gap of the EBL  116   a  may be reduced in a direction away from an active layer  115 . For example, a composition of A1 of the EBL  116   a  may be reduced in a direction away from the active layer  115 . 
     The active layer  115  may have a multiple quantum well (MQW) structure in which a quantum well layer and a quantum barrier layer are alternately stacked. For example, the quantum well layer and the quantum barrier layer may be In x Al y Ga 1−x−y N (0≦x≦1, 0≦y≦1, 0≦x+y≦1) layers having different compositions. For example, the quantum well layer may be an In x Ga 1−x N (0&lt;x≦1) layer, and the quantum barrier layer may be a GaN or AlGaN layer. Thicknesses of the quantum well layer and the quantum barrier layer may be respectively within a range of about 1 nm to about 50 nm. The active layer  115  is not limited to an MQW structure, but may have a single quantum well (SQW) structure. 
     The LED chip  100  may include a first electrode  119   a  disposed on the first conductivity-type semiconductor layer  114 , and an ohmic contact layer  118  and a second electrode  119   b  sequentially disposed on the second conductivity-type semiconductor layer  116 . 
     The first electrode  119   a  may contain a material such as Ag, Ni, Al, Cr, Rh, Pd, Ir, Ru, Mg, Zn, Pt, Au, and the like, but the present inventive concept is not limited thereto. The first electrode  119   a  may be formed in a single layer or in a two or more layer structure. A pad electrode layer may be further provided on the first electrode  119   a . The pad electrode layer may be a layer containing Au, Ni, Sn, or the like. 
     The ohmic contact layer  118  may be implemented in a variety of methods depending on a chip structure. For example, in the case of a flip-chip structure, the ohmic contact layer  118  may contain a metal such as Ag, Au, Al, or the like, and a transparent conductive oxide such as indium tin oxide (ITO), zinc indium oxide (ZIO), gallium indium oxide (GIO), or the like. In the case of an opposite layout structure of the flip-chip structure, the ohmic contact layer  118  may be configured as a light transmitting electrode. The light transmitting electrode may be provided as a transparent conductive oxide layer or nitride layer. For example, the light transmitting electrode may include ITO, zinc-doped indium tin oxide (ZITO), ZIO, GIO, zinc tin oxide (ZTO), fluorine-doped tin oxide (FTO), aluminum-doped zinc oxide (AZO), gallium-doped zinc oxide (GZO), In 4 Sn 3 O 12 , or Zn (1−x) Mg x O (Zinc Magnesium Oxide, 0≦x≦1). The ohmic contact layer  118  may also contain graphene, as necessary. The second electrode  119   b  may contain Al, Au, Cr, Ni, Ti, or Sn. 
       FIG. 13A  is a plan view illustrating an LED chip used as a light source, according to an exemplary embodiment of the present inventive concept.  FIG. 13B  is a side cross-sectional view of the LED chip of  FIG. 13A , taken along line I-I′ of  FIG. 13A , according to an exemplary embodiment of the present inventive concept. 
     An LED chip  200  illustrated in  FIGS. 13A and 13B  may have a large area structure for high output illumination. The LED chip  200  may have a structure for an increase in current dispersion efficiency and heat dissipation efficiency. 
     The LED chip  200  may include a light emitting laminate S, a first electrode  220 , an insulating layer  230 , a second electrode  208 , and a conductive substrate  210 . The light emitting laminate S may include a first conductivity-type semiconductor layer  204 , an active layer  205 , and a second conductivity-type semiconductor layer  206  stacked sequentially. 
     The first electrode  220  may include one or more conductive vias  280  electrically insulated from the second conductivity-type semiconductor layer  206  and the active layer  205  and extended to at least a portion of a region of the first conductivity-type semiconductor layer  204  to be electrically connected to the first conductivity-type semiconductor layer  204 . The conductive vias  280  may be extended from an interface of the first electrode  220  to an interior of the first conductivity-type semiconductor layer  204  while penetrating through the second electrode  208 , the second conductivity-type semiconductor layer  206 , and the active layer  205 . The conductive vias  280  may be formed through an etching process, for example, inductively coupled plasma reactive ion etching (ICP-RIE), or the like. 
     On the first electrode  220 , the insulating layer  230  for electrically insulating regions except for the conductive substrate  210  and the first conductivity-type semiconductor layer  204  from the first electrode  220  may be provided. As illustrated in  FIG. 13B , the insulating layer  230  may be formed on side surfaces of the conductive vias  280  as well as between the second electrode  208  and the first electrode  220 . Thus, the second electrode  208 , the second conductivity-type semiconductor layer  206 , and the active layer  205  exposed to the side surfaces of the conductive vias  280  may be insulated from the first electrode  220 . The insulating layer  230  may be formed by depositing an insulation material such as SiO 2 , SiO x N y , or Si x N y . 
     A contact region C of the first conductivity-type semiconductor layer  204  may be exposed through the conductive vias  280 , and a portion of the first electrode  220  may contact the contact region C through the conductive vias  280 . Thus, the first electrode  220  may be connected to the first conductivity-type semiconductor layer  204 . 
     The number, shape, or pitch of the conductive vias  280 , or a contact diameter or a contact area of the conductive vias  280  with the first and second conductivity-type semiconductor layers  204  and  206 , may be designed to reduce contact resistance. The conductive vias  280  may be formed to be arranged in rows and columns in various forms to increase current flow. A contact area and the number of the conductive vias  280  may be adjusted such that the area of the contact region C may be within a range of about 0.1% to about 20% of a planar area of the light emitting laminate S. According to an exemplary embodiment of the present inventive concept, the area of the contact region C may be within a range of about 0.5% to about 15% of a planar area of the light emitting laminate S. According to an exemplary embodiment of the present inventive concept, the area of the contact region C may be within a range of about 1% to about 10% of the planar area of the light emitting laminate S. In a case in which the area of the contact region C is smaller than 0.1% of a planar area of the light emitting laminate S, current dispersion may not be uniform. Thus light emission characteristics of the LED chip  200  may be reduced. In a case in which the area of the contact region C is 20% or more of the planar area of the light emitting laminate S, light emission characteristics and brightness of the light emitted from the LED chip  200  may be reduced since a light emission area of the light emitting laminate S is small. 
     A radius of the conductive vias  280  in a contact region thereof with the first conductivity-type semiconductor layer  204  may be within a range of, for example, about 1 μm to about 50 μm, and the number of the conductive vias  280  may be 1 to 48000 for each light emitting laminate S region, depending on an area of the light emitting laminate S region. Although the number of the conductive vias  280  is changed according to the area of the light emitting laminate S region, for example, 2 to 45000 conductive vias  280  may be disposed in a light emitting laminate S region. In an exemplary embodiment of the present inventive concept, 5 to 40000 conductive vias  280  may be disposed in a light emitting laminate S region. In an exemplary embodiment of the present inventive concept, 10 to 35000 conductive vias  280  may be disposed in a light emitting laminate S region. A distance between the conductive vias  280  may be within a range of about 10 μm to about 1000 μm in a matrix structure having rows and columns. In an exemplary embodiment of the present inventive concept, a distance between the conductive vias  280  may be within a range of about 50 μm to about 700 μm. In an exemplary embodiment of the present inventive concept, a distance between conductive vias  280  may be within a range of about 100 μm to about 500 μm. In an exemplary embodiment of the present inventive concept, a distance between conductive vias  280  may be within a range of 150 μm to 400 μm. 
     In a case in which a distance between the conductive vias  280  is less than 10 μm, the number of conductive vias  280  per unit area of the light emitting laminate S may increase, and a light emission area of the light emitting laminate S may be reduced. Thus, light emission efficiency of the LED chip  200  may be reduced. In a case in which a distance between the conductive vias  280  is greater than 1000 μm, current may not be evenly diffused. Thus light emission efficiency of the LED chip  200  may be reduced. A depth of the conductive vias  280  may be changed depending on thicknesses of the second conductivity-type semiconductor layer  206  and the active layer  205 , and for example, the depth of the conductive vias  280  may be within a range of about 0.1 μm to about 5.0 μm. 
     The second electrode  208  may provide an electrode formation region E extended outwardly of the light emitting laminate S to be exposed externally as illustrated in  FIG. 13B . The electrode formation region E may include an electrode pad portion  219  connecting the second electrode  208  to an external power source. Although the electrode formation region E has been illustrated as being a single region, a plurality of electrode formation regions E may be provided in the second electrode  208  as needed. The electrode formation region E may be formed in a corner of the LED chip  200  to increase a light emission area as illustrated in  FIG. 13A . 
     In the exemplary embodiment of the present inventive concept, an etching stop insulating layer  240  may be disposed around an electrode pad portion  219 . The etching stop insulating layer  240  may be formed in the electrode formation region E after the light emitting laminate S is formed and before the second electrode  208  is formed, and may serve as an etching stop portion at the time of performing an etching process to form the electrode formation region E. 
     The second electrode  208  may include a material having a high level of reflectivity. The second electrode  208  may form an ohmic contact with the second conductivity-type semiconductor layer  206 . The second electrode  208  may include the reflective material included in the second electrode  208 . 
       FIG. 14  is a side cross-sectional view illustrating an LED chip used as a light source, according to an exemplary embodiment of the present inventive concept. 
     With reference to  FIG. 14 , an LED chip  300  may include a semiconductor laminate  310  formed on a substrate  301 . The semiconductor laminate  310  may include a first conductivity-type semiconductor layer  314 , an active layer  315 , and a second conductivity-type semiconductor layer  316 . 
     The LED chip  300  may include first and second electrodes  322  and  324  respectively connected to the first and second conductivity-type semiconductor layers  314  and  316 . The first electrode  322  may include connection electrode portions  322   a  that may be conductive vias penetrating the second conductivity-type semiconductor layer  316  and the active layer  315  to be connected to the first conductivity-type semiconductor layer  314 , and a first electrode pad  322   b  connected to the connection electrode portions  322   a . The connection electrode portions  322   a  may be surrounded by an insulating portion  321  to be electrically isolated from the active layer  315  and the second conductivity-type semiconductor layer  316 . In the LED chip  300 , the connection electrode portions  322   a  may be formed in a region in which the semiconductor laminate  310  has been etched. The number, a shape, or a pitch of the connection electrode portions  322   a , or a contact area thereof with the first conductivity-type semiconductor layer  314  may be designed to reduce contact resistance. In addition, the connection electrode portions  322   a  may be arranged so that rows and columns thereof may be formed on the semiconductor laminate  310 , thereby increasing current flow. The second electrode  324  may include an ohmic contact layer  324   a  formed on the second conductivity-type semiconductor layer  316 , and a second electrode pad  324   b.    
     The connection electrode portions and the ohmic contact layers  322   a  and  324   a  may respectively have a structure in which a conductive material having an ohmic characteristic with the first and second conductivity-type semiconductor layers  314  and  316  is formed in a single layer or a multilayer structure. For example, the connection electrode portions and the ohmic contact layers  322   a  and  324   a  may be formed in a process of depositing or sputtering one or more materials such as Ag, Al, Ni, Cr, a transparent conductive oxide (TCO), and the like. 
     The first and second electrode pads  322   b  and  324   b  may be connected to the connection electrode portions and the ohmic contact layers  322   a  and  324   a , respectively, so as to function as external terminals of the LED chip  300 . For example, the first and second electrode pads  322   b  and  324   b  may be formed using Au, Ag, Al, Ti, W, Cu, Sn, Ni, Pt, Cr, NiSn, TiW, AuSn, or a eutectic metal thereof. 
     The first and second electrodes  322  and  324  may be disposed in a single direction and mounted on a lead frame, or the like, in a flip-chip form. 
     The first and second electrodes  322  and  324  may be electrically isolated from each other by the insulating portion  321 . In an exemplary embodiment of the present inventive concept, the insulating portion  321  may include any material having an electrical insulation property. In an exemplary embodiment of the present inventive concept, the insulating portion  321  may include a material having a low light absorption rate. For example, the insulating portion  321  may include a silicon oxide and a silicon nitride such as SiO 2 , SiO x N y , Si x N y , or the like. The insulating portion  321  may have a light reflective structure formed by dispersing a light reflective filler in a light transmitting material as needed. In addition, the insulating portion  321  may have a multilayer reflective structure in which a plurality of insulating films having different refractive indices are alternately stacked. For example, the multilayer reflective structure may be implemented by a distributed Bragg reflector in which a first insulating film having a first refractive index and a second insulating film having a second refractive index are alternately stacked. 
     In an exemplary embodiment of the present inventive concept, the multilayer reflective structure may include 2 to 100 insulating films having different refractive indices stacked on each other. In an exemplary embodiment of the present inventive concept, the multilayer reflective structure may include 3 to 70 insulating films having different refractive indices stacked on each other. In an exemplary embodiment of the present inventive concept, the multilayer reflective structure may include 4 to 50 insulating films having different refractive indices stacked on each other. The plurality of insulating films having the multilayer reflective structure may be respectively formed using oxide or nitride such as SiO 2 , SiN, SiO x N y , TiO 2 , Si 3 N 4 , Al 2 O 3 , TiN, AlN, ZrO 2 , TiAlN, TiSiN, or the like, or through a combination thereof. For example, when a wavelength of light generated by the active layer is defined as “k” and “n” is defined as a refractive index of a corresponding layer, the first and second insulating films may be formed to have a thickness of λ/4n, and may have a thickness of approximately 300 Å to 900 Å. In this case, a refractive index and a thickness of the first and second insulating films may be designed such that the multilayer reflective structure may have a high degree of reflectivity (e.g., 95% or higher) with respect to a wavelength of light generated by the active layer  315 . 
     The refractive index of the first insulating film and refractive index of the second insulating film may respectively be in a range of around 1.4 to around 2.5, and may respectively have values less than refractive indices of the first conductivity-type semiconductor layer  314  and the substrate  301 . In addition, the refractive index of the first insulating film and refractive index of the second insulating film may respectively have values less than the refractive index of the first conductivity-type semiconductor layer  314  but greater than the refractive index of the substrate  301 . 
       FIG. 15  is a schematic perspective view and a cross-sectional view illustrating an LED chip, according to an exemplary embodiment of the present inventive concept. 
     With reference to  FIG. 15 , an LED chip  400  may include a base layer  412  formed of a first conductivity-type semiconductor material and a plurality of light emitting nanostructures  410  disposed thereon. 
     The LED chip  400  may include a substrate  411  having an upper surface on which the base layer  412  is disposed. Concave-convex portions G may be formed on the upper surface of the substrate  411 . The concave-convex portions G may increase the quality of a grown single crystal as well as increase light extraction efficiency. The substrate  411  may be provided as an insulating substrate, a conductive substrate, or a semiconductor substrate. For example, the substrate  411  may be formed using sapphire, SiC, Si, MgAl 2 O 4 , MgO, LiAlO 2 , LiGaO 2 , or GaN. 
     The base layer  412  may include a first conductivity-type nitride semiconductor layer and may provide a growth surface of the light emitting nanostructure  410 . The base layer  412  may be provided as a nitride semiconductor satisfying In x Al y Ga 1−x−y N (0≦x&lt;1, 0≦y&lt;1, 0≦x+y&lt;1) and may be doped with an n-type impurity such as Si. For example, the base layer  412  may be formed using n-type GaN. 
     An insulating film  413  having openings for growth of the light emitting nanostructures  410 . Nanocores  404  of the light emitting nanostructures  410  may be formed on the base layer  412 . The nanocores  404  may be formed on a region of the base layer  412  exposed through the openings of insulating film  413 . The insulating film  413  may be used as a mask allowing for the growth of the nanocores  404 . For example, the insulating film  413  may be formed of an insulation material such as SiO 2  or SiN x . 
     The light emitting nanostructure  410  may include a main portion M having a hexagonal prism shaped structure and an upper end portion T disposed on the main portion M. The main portion M of the light emitting nanostructure  410  may have lateral surfaces having the same crystalline surface, and the upper end portion T of the light emitting nanostructure  410  may have a crystalline surface different from those of the lateral surfaces of the main portion M of the light emitting nanostructure  410 . The upper end portion T of the light emitting nanostructure  410  may have a hexagonal pyramid shape. Such a structural shape may be determined by the nanocore  404 . The nanocore  404  may also be divided into the main portion M and the upper end portion T. 
     The light emitting nano structure  410  may include the nanocore  404  configured as a first conductivity-type nitride semiconductor. An active layer  405  and a second conductivity-type nitride semiconductor layer  406  sequentially disposed on a surface of the nanocore  404 . 
     The LED chip  400  may include a contact electrode  416  connected to the second conductivity-type nitride semiconductor layer  406 . The contact electrode  416  employed in the exemplary embodiment of the present inventive concept may be formed using a conductive material having light transmission properties. The contact electrode  416  may cause the light emitting nanostructures  410  to emit light, for example, in a direction opposite to the substrate. The contact electrode  416  may include a transparent conductive oxide layer or a nitride layer. For example, the contact electrode  416  may be formed using ITO, ZITO, ZIO, GIO, ZTO, FTO, AZO, GZO, In 4 Sn 3 O 12 , or Zn (1−x) Mg x O (Zinc Magnesium Oxide, 0≦x≦1). In addition, the contact electrode  416  may contain graphene, as needed. 
     The contact electrode  416  is not limited to a light transmitting material. The contact electrode  416  may include a reflective electrode structure, as needed. For example, the contact electrode  416  may contain a material such as Ag, Ni, Al, Rh, Pd, Ir, Ru, Mg, Zn, Pt, Au, or the like, and may employ a two or more layer structure such as Ni/Ag, Zn/Ag, Ni/Al, Zn/Al, Pd/Ag, Pd/Al, Ir/Ag, Ir/Au, Pt/Ag, Pt/Al, Ni/Ag/Pt, or the like. A flip-chip structure may be implemented by employing the reflective electrode structure as described above. 
     An insulating protective layer  418  may be formed on the light emitting nanostructures  410 . The insulating protective layer  418  may be a passivation portion protecting the light emitting nanostructures  410 . In addition, the insulating protective layer  418  may be formed of a material having light transmission properties so that light generated in the light emitting nanostructures  410  may be extracted. In this case, the insulating protective layer  418  may be formed by selectively using a material having appropriate refractivity to increase light extraction efficiency. 
     In the exemplary embodiment of the present inventive concept, after the contact electrode  416  is formed, the insulating protective layer  418  may fill a space between the plurality of light emitting nanostructures  410 . As a material of the insulating protective layer  418 , an insulation material such as SiO 2  or SiN x  may be used. The insulating protective layer  418  may include a material such as TetraEthylOrthoSilane (TEOS), BoroPhospho Silicate Glass (BPSG), CVD-SiO 2 , Spin-on Glass (SOG), or Spin-on Dielectric (SOD). 
     The insulating protective layer  418  may be used to fill a space between the light emitting nanostructures  410 , but the present inventive concept is not limited thereto. For example, a space between the light emitting nanostructures  410  may also be filled with an electrode element such as an element of the contact electrode  416 . In addition, the space between the light emitting nanostructures  410  may be filled with a reflective electrode material described above. 
     The LED chip  400  may include first and second electrodes  419   a  and  419   b . The first electrode  419   a  may be disposed in a portion of a partially exposed region of the base layer  412 . The base layer  412  includes a first conductivity-type semiconductor. The second electrode  419   b  may be disposed in an exposed region of the contact electrode  416 . The arrangement of the first and second electrodes  419   a  and  419   b  is not limited to the illustration above described with reference to  FIG. 15 . The first and second electrodes  419   a  and  419   b  may be variously arranged depending on the use of the LED chip  400 . 
     The LED chip  400  may have a core-shell nanostructure, and may have low heat generation due to a low combination density, and may have an increased light emission area through the nanostructure to thus increase light emission efficiency. In addition, since the LED chip  400  may include a non-polar active layer, a reduction in light emission efficiency due to polarization may be prevented, and droop may be controlled. 
     In addition, the plurality of the light emitting nanostructures  410  may emit light having two or more different wavelengths by having a mask layer with a plurality of open regions having different diameters, different intervals (e.g., pitches) between the plurality of open regions of the mask layer, or a different doping concentration or a different indium (In) content mixed in the active layer  405  of the light emitting nanostructure. Thus, white light may be obtained even without using a phosphor in a single light emitting device by controlling light having different wavelengths. In addition, light having desired various colors or white light having different color temperatures may be obtained by combining the lighting device with a different LED chip or with a wavelength conversion material such as a phosphor. 
     Hereinafter, a lighting device in which a light source module is employed will be described with reference to  FIGS. 16 to 18 , according to various exemplary embodiments of the present inventive concept. 
       FIG. 16  is a schematic cross-sectional view of a lighting device, according to an exemplary embodiment of the present inventive concept. With reference to  FIG. 16 , a lighting device  1000  may have a surface light source type structure, for example, and may be provided as a direct-type backlight unit. 
     The lighting device  1000  may include an optical sheet  1040  and a light source module  1010  arranged below the optical sheet  1040 . 
     The optical sheet  1040  may include a light diffusion sheet  1041 , a prism sheet  1042 , and a protective sheet  1043 . 
     The light source module  1010  may include a PCB  1011 , a plurality of light sources  1012  mounted on an upper surface of the PCB  1011 , and a plurality of optical devices  1013  respectively disposed above the plurality of light sources  1012 . The light source module  1010 , according to the exemplary embodiment of the present inventive concept, may have a structure similar to that of the light source module  1  of  FIG. 1 . The plurality of optical devices  1013  may have a biconvex lens structure. Since a vertical cross section of a light incident surface has an “S” shape, uniformity of brightness distribution on a central portion of the optical devices  1013  may be increased. A detailed description of the respective constituent elements of the light source module  1010  can be understood with reference to the foregoing exemplary embodiments of the present inventive concept, for example, with reference to the exemplary embodiment of the present inventive concept described with reference to  FIG. 7 . 
       FIG. 17  is a schematic exploded perspective view of a bulb-type lighting device, according to an exemplary embodiment of the present inventive concept. 
     A lighting device  1100  may include a socket  1110 , a power supply unit  1120 , a heat radiating unit  1130 , a light source module  1140 , and an optical unit  1150 . 
     According to an exemplary embodiment of the present inventive concept, the light source module  1140  may include a light emitting device array, and the power supply unit  1120  may include a light emitting device driving unit. 
     The socket  1110  may be configured such that it may be mounted on an existing lighting apparatus. Power supplied to the lighting device  1100  may be applied through the socket  1110 . As illustrated, the power supply unit  1120  may include a first power supply portion  1121  and a second power supply portion  1122  separated from and coupled to each other. The heat radiating unit  1130  may include an internal heat radiating portion  1131  and an external heat radiating portion  1132 . The internal heat radiating portion  1131  may be directly connected to the light source module  1140  and/or to the power supply unit  1120 . Heat may be transferred to the external heat radiating portion  1132  by the internal heat radiating portion  1131 . The optical unit  1150  may include an internal optical portion and an external optical portion, and may be configured such that light emitted from the light source module  1140  may be uniformly dispersed. 
     The light source module  1140  may receive power from the power supply unit  1120  and emit light to the optical unit  1150 . The light source module  1140  may include one or more light sources  1141  having an optical device, a circuit board  1142 , and a controller  1143 . The controller  1143  may store driving information of the light sources  1141  therein. 
     The light source module  1140 , according to the exemplary embodiment of the present inventive concept, may have a structure similar to that of the light source module  1  of  FIG. 1 . The optical devices respectively disposed on the light sources  1141  may have a biconvex lens structure. Since a vertical cross section of a light incident surface of the optical devices has an “S” shape, uniformity of brightness distribution on a central portion thereof may be increased. A detailed description of the respective constituent elements of the light source module  1140  can be understood with reference to the foregoing exemplary embodiments of the present inventive concept, for example, with reference to the exemplary embodiment of the present inventive concept with reference to  FIG. 7 . 
       FIG. 18  is a schematic exploded perspective view of a bar type lighting device, according to an exemplary embodiment of the present inventive concept. 
     A lighting device  1200  may include a heat radiating member  1210 , a cover  1220 , a light source module  1230 , a first socket  1240 , and a second socket  1250 . A plurality of heat radiating fins  1211  and  1212  having a concave-convex surface shape may be formed on an inner surface or/and an external surface of the heat radiating member  1210 . The heat radiating fins  1211  and  1212  may be designed to have various forms and intervals therebetween. A support portion  1213  having a protruding form may be formed inwardly of the heat radiating member  1210 . The light source module  1230  may be fixed to the support portion  1213 . A stop protrusion  1214  may be formed on both ends of the heat radiating member  1210 . 
     The cover  1220  may include a stop groove  1221  formed therein. The stop groove  1221  may be coupled to the stop protrusion  1214  of the heat radiating member  1210  in a hook coupling structure. The positions in which the stop groove  1221  and the stop protrusion  1214  are formed may be changed inversely. 
     The light source module  1230  may include a light source array. The light source module  1230  may include a PCB  1231 , a light source  1232  having an optical device, and a controller  1233 . In an exemplary embodiment of the present inventive concept, the light source module  1230  includes a plurality of light source  1232 . Each of the light sources  1232  includes an optical device disposed thereon. As described above, the controller  1233  may store driving information of the light sources  1232  therein. The PCB  1231  may include circuit wirings formed therein for operating the light sources  1232 . In addition, constituent elements for operating the light sources  1232  may be provided. The light source module  1230 , according to the exemplary embodiment of the present inventive concept, may be substantially identical to the light source module of  FIG. 1 . Thus, a detailed description thereof may be omitted. 
     The first and second sockets  1240  and  1250  may be provided as a pair of sockets and may have a structure in which they are coupled to both ends of a cylindrical cover unit. The cylindrical cover unit includes the heat radiating member  1210  and the cover  1220 . The first socket  1240  may include electrode terminals  1241  and a power supply device  1242 . The second socket  1250  may include dummy terminals  1251  disposed thereon. In addition, an optical sensor and/or a communications module may be disposed on the interior one of the first socket  1240  or the second socket  1250 . For example, the optical sensor and/or the communications module may be installed in the second socket  1250  in which the dummy terminals  1251  are disposed. In another example, an optical sensor and/or a communications module may be installed in the first socket  1240  in which the dummy electrode terminals  1241  are disposed. 
     A lighting device using a light emitting device may be classified as an indoor LED lighting device and as an outdoor LED lighting device. The indoor LED lighting device may mainly be used in a bulb-type lamp, an LED-tube lamp, or a flat-type lighting device, as an existing lighting device retrofit. The outdoor LED lighting device may be used in a streetlight, a safety lighting fixture, a light transmitting lamp, a landscape lamp, a traffic light, or the like. 
     In addition, a lighting device using LEDs may be utilized as internal and external light sources in vehicles. When used as the internal light source, the lighting device using LEDs may be used as interior lights for motor vehicles, reading lamps, various types of light source for an instrument panel, and the like. When used as the external light sources in vehicles, the lighting device using LEDs may be used in all types of light sources such as headlights, brake lights, turn signal lights, fog lights, running lights for vehicles, and the like. 
     Further, an LED driving device may be used as a light source in robots or in various kinds of mechanical equipment. An LED lighting device using light within a certain wavelength band may promote the growth of a plant, may change people&#39;s moods, or may also be used therapeutically, as emotional lighting. 
     According to exemplary embodiments of the present inventive concept, an optical device including a light source module may uniformly distribute brightness and may prevent the occurrence of Mura defects. 
     While the inventive concept has been particularly shown and described with reference to exemplary embodiments thereof, it will be apparent to those of ordinary skill in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the inventive concept as defined by the following claims.