Patent Publication Number: US-10330281-B2

Title: Lighting device

Description:
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS 
     This application is a U.S. National Stage Application under 35 U.S.C. § 371 of PCT Application No. PCT/KR2015/008422, filed Aug. 12, 2015,which claims priority to Korean Patent Application No. 10-2014-0109574, filed Aug. 22, 2014, whose entire disclosures are hereby incorporated by reference. 
     TECHNICAL FIELD 
     Embodiments relate to a lighting device. 
     BACKGROUND ART 
     A fluorescent lamp, which is commonly used for a lighting device, is operated at a frequency of 60 Hz, leading to severe eye fatigue due to flickering when it is used for a long period of time. 
     Further, when the fluorescent lamp is used for a long period of time, it may increase the ambient temperature due to self-heating, and may cause high electric loss. 
     In contrast, an LED lamp has advantages in that the efficiency of conversion of electric power into light is remarkably high, it produces highly efficient intensity of illumination at low voltage, it has anti-glare properties, and the operational stability is excellent, with the result that an LED lamp has come to be widely used for lighting devices. 
     A light-emitting module, which includes a plurality of LEDs as a light source, is employed as a lighting device, in which maintenance of uniform luminance is required in order to relieve user eye fatigue. 
     DISCLOSURE 
     Technical Problem 
     Embodiments provide a lighting device capable of improving luminance uniformity and color uniformity and of preventing yield reduction. 
     Technical Solution 
     A lighting device according to an embodiment includes a housing including a lower plate and a side plate, a light-emitting module including a substrate disposed on the lower plate and light sources disposed on the substrate, and a lens array unit including lenses arranged corresponding to the light sources, in which the light sources include light sources emitting each other, and sizes of the lenses are proportional to a quantity of light from the light sources. 
     At least one of separation distances between the adjacent light sources may be different from the other separation distances. 
     A center of each of the lenses may be aligned with a center of a corresponding one of the light sources. 
     The quantity of light from the light sources may decrease moving away from a center line of the housing in a direction perpendicular to the center line of the housing. The sizes of the lenses may decrease moving away from the center line of the housing in the direction perpendicular to the center line of the housing. 
     The separation distance between adjacent light sources and the separation distance between adjacent lenses may decrease moving away from the center line of the housing in the direction perpendicular to the center line of the housing. 
     The quantity of light from the light sources may increase moving away from the center line of the housing in the direction perpendicular to the center line of the housing. 
     The sizes of the lenses may increase moving away from the center line of the housing in the direction perpendicular to the center line of the housing. 
     The separation distance between adjacent light sources and the separation distance between adjacent lenses may increase moving away from the center line of the housing in the direction perpendicular to the center line of the housing. 
     A lighting device according to another embodiment includes a housing including a lower plate and a side plate, a light-emitting module including a substrate disposed on the lower plate and light sources disposed on the substrate, and a lens array unit including lenses arranged corresponding to the light sources, in which the light sources include light sources emitting different quantities of light from each other, and an angle of beam spread of light emitted from each of the lenses is proportional to a quantity of light from a corresponding one of the light sources. 
     The quantity of light from the light sources may decrease, and the angle of beam spread of light emitted from the lenses may decrease moving away from a center line of the housing in a direction perpendicular to the center line of the housing. 
     The separation distance between adjacent light sources and the separation distance between adjacent lenses may decrease moving away from the center line of the housing in the direction perpendicular to the center line of the housing. 
     The quantity of light from the light sources may increase, and the angle of beam spread of light emitted from the lenses may increase moving away from the center line of the housing in the direction perpendicular to the center line of the housing. 
     The separation distance between adjacent light sources and the separation distance between adjacent lenses may increase moving away from the center line of the housing in the direction perpendicular to the center line of the housing. 
     The lighting device may further include an optical sheet disposed on the lens array unit. 
     The lens array unit may further include a connection portion for connecting the lenses. 
     The light sources may be arranged in a row or in a matrix form having rows and columns. 
     The connection portion may be made of the same material as the lenses and may be integrally formed with the lenses. 
     The lighting device may further include a fixing unit disposed on the substrate in order to support the lens array unit. 
     A lighting device according to a further embodiment includes a housing including a lower plate and a side plate, a light-emitting module including a substrate disposed on the lower plate and first light sources and second light sources disposed on the substrate, each of the second light sources being disposed between adjacent ones of the first light sources, a lens array unit including lenses arranged in alignment with the light sources and a connection portion for connecting the lenses, and an optical sheet disposed on the lens array unit, in which a quantity of light from the first light sources is smaller than a quantity of light from the second light sources, separation distances between the first light sources and the second light sources adjacent to each other are identical to each other, and a size of each of the first lenses is smaller than a size of each of the second lenses. 
     Advantageous Effects 
     Embodiments are capable of improving luminance uniformity and color uniformity and of preventing yield reduction. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG. 1  illustrates a plan view of a lighting device according to an embodiment. 
         FIG. 2  illustrates a sectional view taken along line I-II in the lighting device depicted in  FIG. 1 . 
         FIG. 3  illustrates luminance distribution of a lens corresponding to an A-type light source. 
         FIG. 4  illustrates luminance distribution of a lens corresponding to a C-type light source. 
         FIG. 5  illustrates luminance distribution of a lens corresponding to an E-type light source. 
         FIG. 6  illustrates a plan view of a lighting device according to another embodiment. 
         FIG. 7  illustrates a sectional view taken along line I-II in the lighting device depicted in  FIG. 6 . 
         FIG. 8  illustrates the arrangement of light sources depending on the quantity of light according to another embodiment. 
         FIG. 9  illustrates a lighting device according to another embodiment. 
         FIG. 10  illustrates a lighting device according to another embodiment. 
         FIG. 11  illustrates the arrangement of light sources and lenses and the sizes of the lenses in a lighting device according to a comparative example. 
         FIG. 12  illustrates luminance distribution of the lighting device depicted in  FIG. 11 . 
         FIG. 13  illustrates the arrangement of light sources and lenses and the sizes of the lenses in the lighting device according to the embodiment. 
         FIG. 14  illustrates luminance distribution of the lighting device depicted in  FIG. 13 . 
     
    
    
     BEST MODE 
     Hereinafter, embodiments will be clearly understood from the attached drawings and the description associated with the embodiments. In the description of the embodiments, it will be understood that when an element, such as a layer (film), a region, a pattern or a structure, is referred to as being “on” or “under” another element, such as a substrate, a layer (film), a region, a pad or a pattern, the term “on” or “under” means that the element can be “directly” on or under another element or can be “indirectly” formed such that an intervening element may also be present. In addition, it will also be understood that criteria of on or under is on the basis of the drawings. 
     In the drawings, dimensions are exaggerated, omitted or schematically illustrated for description convenience and clarity. In addition, dimensions of constituent elements do not entirely reflect actual dimensions. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. Hereinafter, a lighting device according to an embodiment will be described with reference to the accompanying drawings. 
       FIG. 1  illustrates a plan view of a lighting device  100  according to an embodiment, and  FIG. 2  illustrates a sectional view taken along line I-II in the lighting device  100  depicted in  FIG. 1 . 
     Referring to  FIGS. 1 and 2 , a lighting device  100  comprises a housing  10 , a light-emitting module  20 , a lens array unit (or a lens array bar)  30 , a fixing unit  38 , a power supply unit  40 , and an optical sheet  50 . 
     The light-emitting module  20  and the lens array unit  30  may compose a light source unit. 
     The housing  10  accommodates the light source unit, which includes the light-emitting module  20  and the lens array unit  30 . 
     Further, the housing  10  may reflect light emitted from the light-emitting module  20 . 
     The housing  10  may include a lower plate  12 , on which the light-emitting module  20  is disposed, and a side plate  14 , which surrounds the light-emitting module  20 . The side plate  14  may be connected to an edge portion of the lower plate  12 , and may be inclined at a constant angle relative to the lower plate  12 . 
     Although it is illustrated in  FIG. 2  that the angle between the side plate  14  and the lower plate  12  is a right angle, the embodiment is not limited thereto, and the angle between the side plate  14  and the lower plate  12  may be an obtuse angle in another embodiment. 
     That is, the angle between the lower plate  12  and the side plate  14  of the housing  10  may be larger than or equal to 90° and may be smaller than 180°. As an example, the longitudinal-sectional shape of the housing  10  may be a rectangular shape, a square shape or a trapezoidal shape. 
     The housing  10  may have a polygonal shape, for example, a quadrangular shape, when viewed from above. 
     For instance, when viewed from above, the housing  10  may have a rectangular shape in which the horizontal length is longer than the vertical length; however, the embodiment is not limited thereto, and the housing  10  may be formed in various other shapes depending on the application to which the lighting device is applied. 
     The light-emitting module  20  may include a substrate  22 , which is disposed on the lower plate  12  of the housing  10 , and a light source array  24 , which is disposed on the substrate  22 . The light source array  24  may include a plurality of light sources  24 C,  24 L 1  to  24 L 4  and  24 R 1  to  24 R 4 , which are disposed on the substrate  22  such that they are spaced apart from each other. 
     The substrate  22  may be a printed circuit board (PCB), and the plurality of light sources  24 C,  24 L 1  to  24 L 4  and  24 R 1  to  24 R 4  may include light-emitting diodes (LEDs). As an example, each of the light sources  24 C,  24 L 1  to  24 L 4  and  24 R 1  to  24 R 4  may be an LED chip or an LED package; however, the embodiment is not limited thereto. 
     The plurality of light sources  24 C,  24 L 1  to  24 L 4  and  24 R 1  to  24 R 4  are disposed on the substrate  22 . For instance, the plurality of light sources  24 C,  24 L 1  to  24 L 4  and  24 R 1  to  24 R 4  may be arranged in a row while being spaced apart from each other, or may be arranged in a matrix form while being spaced apart from each other on the substrate  22 ; however, the embodiment is not limited thereto, and the plurality of light sources may be arranged in contact with each other in another embodiment. 
     Although it is illustrated in  FIG. 1  that the plurality of light sources  24 C,  24 L 1  to  24 L 4  and  24 R 1  to  24 R 4  are arranged in a row in the horizontal direction, the plurality of light sources may be arranged in a matrix form, which has a dimension of multiple rows×multiple columns, in another embodiment. 
     The substrate  22  may include a wiring pattern for the supply of power and the transmission of control signals. 
     The substrate  22  may be secured to the lower plate  12  of the housing  10  by means of an adhesive member. 
     Alternatively, at least one of the lower plate  12  and the side plate  14  of the housing  10  may have a recess portion (not shown) therein, into which the substrate  22  of the light-emitting module  20  is inserted, with the result that the substrate  22  may be secured to the housing  10  by being inserted into the recess portion. 
     At least one of the plurality of light sources  24 C,  24 L 1  to  24 L 4  and  24 R 1  to  24 R 4  may emit a different quantity of light from the others. As an example, each of the plurality of light sources  24 C,  24 L 1  to  24 L 4  and  24 R 1  to  24 R 4  may emit a different quantity of light from the others. 
     The plurality of light sources  24 C,  24 L 1  to  24 L 4  and  24 R 1  to  24 R 4  may include light sources emitting different quantities of light from each other. 
     The plurality of light sources  24 L 1  to  24 L 4  and  24 R 1  to  24 R 4  may be arranged symmetrically with each other on the basis of a reference line  101 . 
     The plurality of light sources  24 C,  24 L 1  to  24 L 4  and  24 R 1  to  24 R 4  may be arranged such that a separation distance between two adjacent light sources is different from a separation distance between two other adjacent light sources. 
     At least one of the separation distances between the adjacent light sources may be different from the other separation distances. As an example, each of the separation distances between the adjacent light sources may be different from the others. 
     As an example, the separation distance may be a pitch between two adjacent light sources. Here, the pitch may be a separation distance between the centers of the two adjacent light sources. 
     The plurality of light sources  24 C,  24 L 1  to  24 L 4  and  24 R 1  to  24 R 4  may be classified into an A-type to an E-type based on the value or the level of quantity of light. The value of quantity of light may be as follows: A-type &gt;B-type &gt;C-type &gt;D-type &gt;E-type. 
     As an example, when the quantity of light from the A-type is defined as 100%, the quantity of light from the B-type may be 96%, the quantity of light from the C-type may be 90%, the quantity of light from the D-type may be 82%, and the quantity of light from the E-type may be 70%; however, this classification is merely exemplary, and the plurality of light sources  24 C,  24 L 1  to  24 L 4  and  24 R 1  to  24 R 4  may be classified into various other categories depending on the quantity of light. 
     The plurality of light sources  24 C,  24 L 1  to  24 L 4  and  24 R 1  to  24 R 4  are classified into five types depending on the quantity of light; however, the embodiment is not limited thereto, and the plurality of light sources may be classified into two or more types. 
     The quantity of light from the light sources, which are disposed on the substrate  22 , may increase or decrease in a first direction. The first direction may be a direction that is parallel to the direction in which the light sources are arranged. In the case in which the light sources are arranged in a matrix form, the first direction may be a row direction or a column direction. 
     Further, the quantity of light from the arranged light sources may increase or decrease in a second direction on the basis of the reference line  101 . Here, the second direction may be a lateral direction on the basis of the reference line  101 . 
     In the embodiment in  FIG. 2 , the quantity of light from the light-emitting element  24 C that is aligned with the reference line  101  is the largest, and the quantity of light from the light sources decreases moving away from the reference line  101  in the second direction. In the embodiment in  FIG. 7 , which will be described later, the quantity of light from the light-emitting element  24 C that is aligned with the reference line  101  is the smallest, and the quantity of light from the light sources  24 C′,  24 L 1 ′ to  24 L 4 ′ and  24 R 1  to  24 R 4 ′ may increase moving away from the reference line in the second direction. 
     Further, in the embodiment ( 24 C,  24 L 1  to  24 L 4  and  24 R 1  to  24 R 4 ) in  FIG. 2 , the quantity of light from the light sources may be bilaterally symmetrical on the basis of the reference line  101  in the second direction; however, the embodiment is not limited thereto. 
     Here, the reference line  101  may be a center line, which extends between the middle of one end of the housing  10  and the middle of the other end of the housing  10 . Further, the reference line  101  may be a center line, which extends between the middle of one end of the substrate  22  and the middle of the other end of the substrate  22 . As an example, the light source that is located at the center position of the arranged light sources  24 C,  24 L 1  to  24 L 4  and  24 R 1  to  24 R 4  may be aligned with the reference line  101 . 
     The first light source  24 C, which is aligned with the reference line  101 , may be of an A-type, and may emit the largest quantity of light, and the quantity of light from the light sources may decrease moving away from the reference line  101 . 
     As an example, the quantity of light from the light sources  24 C,  24 L 1  to  24 L 4  and  24 R 1  to  24 R 4  may decrease moving away from the center line of the housing  10  in the direction perpendicular to the center line of the housing  10 . 
     As an example, the B-type light source  24 L 1 , the C-type light source  24 L 2 , the D-type light source  24 L 3 , and the E-type light source  24 L 4  may be arranged sequentially to the left from the reference line  101  or from the first light source  24 C. 
     The B-type light source  24 R 1 , the C-type light source  24 R 2 , the D-type light source  24 R 3 , and the E-type light source  24 R 4  may be arranged sequentially to the right from the reference line  101  or from the first light source  24 C. 
     Further, the separation distances between the adjacent light sources, for example, the pitches a, b, c and d, may decrease (a&gt;b&gt;c&gt;d) moving away from the reference line  101  or the first light source  24 C in the second direction. 
     The lens array unit (or the lens array bar)  30  may include a plurality of lenses  32 C,  32 L 1  to  32 L 4  and  32 R 1  to  32 R 4 , which are arranged so as to be spaced apart from each other, and a connection portion  34  for connecting the plurality of lenses  32 C,  32 L 1  to  32 L 4  and  32 R 1  to  32 R 4 . 
     The plurality of lenses  32 C,  32 L 1  to  32 L 4  and  32 R 1  to  32 R 4  may be formed to protrude from the top surface of the connection portion  34  in the vertical direction, for example, in the upward direction. 
     Each of the plurality of lenses  32 C,  32 L 1  to  32 L 4  and  32 R 1  to  32 R 4  may be arranged so as to correspond to or to be aligned with a respective one of the plurality of light sources  24 C,  24 L 1  to  24 L 4  and  24 R 1  to  24 R 4 . 
     As an example, the center of each of the plurality of lenses  32 C,  32 L 1  to  32 L 4  and  32 R 1  to  32 R 4  may be aligned with the center of a corresponding one of the plurality of light sources  24 C,  24 L 1  to  24 L 4  and  24 R 1  to  24 R 4  in the vertical direction. Here, the vertical direction may be a direction that is perpendicular to the top surface of the substrate  22  and is oriented toward the lens array unit  30  from the substrate  22 . 
     The separation distance between two adjacent lenses may be equal to the separation distance between two adjacent light sources that correspond to the two adjacent lenses. 
     The separation distance between two adjacent lenses may decrease moving away from the reference line  101  in the second direction. Further, the separation distance between two adjacent lenses may be bilaterally symmetrical on the basis of the reference line  101 . 
     As an example, the separation distance between two adjacent light sources and the separation distance between two adjacent lenses may decrease moving away from the center line of the housing  10  in the direction perpendicular to the center line of the housing  10 . 
     The size of each of the plurality of lenses  32 C,  32 L 1  to  32 L 4  and  32 R 1  to  32 R 4  may be proportional to the quantity of light from a corresponding one of the light sources  24 C,  24 L 1  to  24 L 4  and  24 R 1  to  24 R 4 . 
     As an example, the greater the quantity of light from the light source, the larger the size of the corresponding lens, and, on the other hand, the lower the quantity of light from the light source, the smaller the size of the corresponding lens. 
     The sizes of the lenses  32 C,  32 L 1  to  32 L 4  and  32 R 1  to  32 R 4  may decrease moving away from the center line of the housing  10  in the direction perpendicular to the center line of the housing  10 . 
     The first lens  32 C, which is aligned with the reference line  101 , may have the largest size, and the sizes of the arranged lenses may decrease moving away from the first lens  32 C. Here, the size of the lens may be the diameter of the lens. 
     As an example, the second lens  32 L 1 , the third lens  32 L 2 , the fourth lens  32 L 3 , and the fifth lens  32 L 4  may be arranged sequentially to the left from the reference line  101  or from the first lens  32 C, and the sizes of the lenses may be as follows: first lens  32 C &gt;second lens  32 L 1  &gt;third lens  32 L 2  &gt;fourth lens  32 L 3  &gt;fifth lens  32 L 4 . 
     The second lens  32 R 1 , the third lens  32 R 2 , the fourth lens  32 R 3 , and the fifth lens  32 R 4  may be arranged sequentially to the right from the reference line  101  or from the first lens  32 C, and the sizes of the lenses may be as follows: first lens  32 C &gt;second lens  32 R 1  &gt;third lens  32 R 2  &gt;fourth lens  32 R 3  &gt;fifth lens  32 R 4 . 
     The light beams emitted from the plurality of lenses  32 C,  32 L 1  to  32 L 4  and  32 R 1  to  32 R 4  may have luminance distributions having different sizes in the optical sheet  50 . 
     The angle of beam spread of the light emitted from each of the plurality of lenses  32 C,  32 L 1  to  32 L 4  and  32 R 1  to  32 R 4  may be proportional to the quantity of light from a corresponding one of the light sources  24 C,  24 L 1  to  24 L 4  and  24 R 1  to  24 R 4 . 
     The quantity of light from the light sources  24 C,  24 L 1  to  24 L 4  and  24 R 1  to  24 R 4  may decrease, and the angle of beam spread of the light emitted from the corresponding lenses  32 C,  32 L 1  to  32 L 4  and  32 R 1  to  32 R 4  may decrease moving away from the center line of the housing  10  in the direction perpendicular to the center line of the housing  10 . 
     As an example, the quantity of light from the light sources  24 C,  24 L 1  to  24 L 4  and  24 R 1  to  24 R 4  may decrease, and the angle of beam spread of the light emitted from the corresponding lenses  32 C,  32 L 1  to  32 L 4  and  32 R 1  to  32 R 4  may decrease moving away from the reference line  101  in the second direction. 
       FIG. 3  illustrates the luminance distribution of a lens corresponding to the A-type light source,  FIG. 4  illustrates the luminance distribution of a lens corresponding to the C-type light source, and  FIG. 5  illustrates the luminance distribution of a lens corresponding to the E-type light source. 
     The light emitted from the first lens  32 C, which corresponds to the first light source  24 C, which is of an A-type, may have the largest luminance distribution, and the size of the luminance distribution may decrease moving away from the reference line  101  or the first lens  32 C. 
     Referring to  FIG. 3 , as an example, the diameter of the luminance distribution of the light emitted from the first lens  32 C, which corresponds to the first light source  24 C, which is of an A-type, may be equal to a first separation distance a. 
     The first separation distance a may be a separation distance between the first light source  24 C and the second light source  24 L 1  and  24 R 1  or a separation distance between the first lens  32 C and the second lens  34 L 1  and  34 R 1 . 
     Referring to  FIG. 4 , as an example, the diameter of the luminance distribution of the light emitted from the third lens  32 L 1  and  32 R 1 , which corresponds to the third light source  24 L 2  and  24 R 2 , which is of a C-type, may be equal to a value obtained by dividing the sum of a second separation distance b and a third separation distance c by 2 ((b+c)/2). 
     The second separation distance b may be a separation distance between the second light source  24 L 1  and  24 R 1  and the third light source  24 L 2  and  24 R 2  or a separation distance between the second lens  34 L 1  and  34 R 1  and the third lens  34 L 2  and  34 R 2 . 
     The third separation distance c may be a separation distance between the third light source  24 L 2  and  24 R 2  and the fourth light source  24 L 3  and  24 R 3  or a separation distance between the third lens  34 L 2  and  34 R 2  and the fourth lens  34 L 3  and  34 R 3 . 
     Referring to  FIG. 5 , the diameter of the luminance distribution of the light emitted from the fifth lens  32 L 4  and  32 R 4 , which corresponds to the fifth light source  24 L 4  and  24 R 4 , which is of an E-type, may be equal to a fourth separation distance d. 
     The fourth separation distance d may be a separation distance between the fourth light source  24 L 3  and  24 R 3  and the fifth light source  24 L 4  and  24 R 4  or a separation distance between the fourth lens  34 L 3  and  34 R 3  and the fifth lens  34 L 4  and  34 R 4 . 
     It can be seen that the diameter of the luminance distribution of the light emitted from the light sources decreases moving away from the reference line  101  or the first lens  32 C. 
     The connection portion  34  may be configured as a plate, which is connected with the plurality of lenses  32 C,  32 L 1  to  32 L 4  and  32 R 1  to  32 R 4 . The connection portion  34  may be made of the same material as the plurality of lenses  32 C,  32 L 1  to  32 L 4  and  32 R 1  to  32 R 4 , and may be integrally formed with the lenses; however, the embodiment is not limited thereto. 
     The fixing unit  38  may be disposed on the substrate  22  in order to secure the lens array unit  30  to the substrate  22 , and may support the lens array unit  30 . As an example, the fixing unit  38  may secure the connection portion  340  of the lens array unit  30  to the substrate  220 . 
     As an example, one end of the fixing unit  38  may be connected to the bottom surface of the connection portion  340  of the lens array unit  30 , and the other end of the fixing unit  38  may be connected to the top surface of the substrate  22  using a fastening means such as a bolt, a screw, an adhesive agent, etc. 
     The fixing unit  38  may be made of the same material as the lens array unit  30  and may be integrally formed with the lens array unit  30 ; however, the embodiment is not limited thereto, and the fixing unit  38  may be made of a material different from that of the lens array unit  30 , and may be formed separately from the lens array unit  30 . 
     The power supply unit  40  supplies power to the light-emitting module  20  via a connector (not shown). As an example, the power supply unit  40  may convert commonly-used alternating-current power (AC 110V or 220V) into direct-current voltage (e.g. DC 3.3V), which is LED driving power, and may supply the converted direct-current voltage to the light-emitting module  20 . 
     The optical sheet  50  may be disposed on the lens array unit  30 , and may function to diffuse the light emitted from the lens array unit  30  by refraction and scattering or to disperse the light in a constant direction. 
     The optical sheet  50  may be supported by the housing  10 . 
     As an example, the upper end of the side plate  14  of the housing  10  may be provided with a stepped portion  14   a , and the optical sheet  50  may be supported by the stepped portion  14   a.    
     The optical sheet  50  may include at least one of a diffusion sheet, a prism sheet and a micro lens array. 
     As an example, the diffusion sheet may be formed of a polyester or polycarbonate-based material, and may increase the projection angle of light by refraction and scattering. 
     The prism sheet may include at least one of a first prism sheet and a second prism sheet. 
     As an example, each of the first prism sheet and the second prism sheet may be formed by applying a light-transmitting and elastic polymer to a surface of a support film, and the polymer may have a prism layer in which a plurality of 3D structures is repeatedly formed. Here, the plurality of structures may be provided as a stripe pattern in which ridges and valleys are repeatedly formed. In addition, the direction of the ridges and valleys in the second prism sheet may be perpendicular to the direction of the ridges and valleys in the first prism sheet. 
     Although the light sources are manufactured through the same process, there may be a difference in the values of quantity of light from the light sources, and in the case in which light sources emitting different quantities of light from each other are used for flat lighting devices or backlight units, the luminance uniformity and the color uniformity may be degraded, and yield reduction may even occur because the light sources cannot be used when there is a large difference in the values of quantity of light. 
     Meanwhile, according to the embodiment  100 , the sizes of the lenses are proportional to the quantity of light from the light sources  24 C,  24 L 1  to  24 L 4  and  24 R 1  to  24 R 4 , and the separation distance between two adjacent light sources and the separation distance between two adjacent lenses are adjusted in consideration of the quantity of light, thereby improving the luminance uniformity and the color uniformity and preventing yield reduction. 
       FIG. 6  illustrates a plan view of a lighting device  200  according to another embodiment, and  FIG. 7  illustrates a sectional view taken along line I-II in the lighting device  200  depicted in  FIG. 6 . Reference numerals the same as those in  FIGS. 1 and 2  designate the same components, and an explanation thereof will be made briefly or omitted. 
     Referring to  FIGS. 6 and 7 , a lighting device  200  comprises a housing  10 , a light-emitting module  20 - 1 , a lens array unit  30 - 1 , a fixing unit  38 , a power supply unit  40 , and an optical sheet  50 . 
     The light-emitting module  20 - 1  may include a substrate  22 , and a light source array  24 ′, which includes a plurality of light sources  24 - 1 ,  24 C′,  24 L 1 ′ to  24 L 4 ′ and  24 R 1  to  24 R 4 ′, which are disposed on the substrate while being spaced apart from each other. 
     The lens array unit  30 - 1  may include a plurality of lenses  32 C′,  32 L 1 ′ to  32 L 4 ′ and  32 R 1 ′ to  32 R 4 ′, which are arranged so as to be spaced apart from each other, and a connection portion  34  for connecting the plurality of lenses  32 C′,  32 L 1 ′ to  32 L 4 ′ and  32 R 1 ′ to  32 R 4 ′. 
     The arrangement of the plurality of light sources  24 C′,  24 L 1 ′ to  24 L 4 ′ and  24 R 1  to  24 R 4 ′, which are classified into an A-type to an E-type based on the quantity of light, on the substrate  22  and the arrangement of the lenses  32 C′,  32 L 1 ′ to  32 L 4 ′ and  32 R 1 ′ to  32 R 4 ′, corresponding to the plurality of light sources  24 C′,  24 L 1 ′ to  24 L 4 ′ and  24 R 1  to  24 R 4 ′ in the embodiment  200 , are different from those in the embodiment  100  depicted in  FIGS. 1 and 2 . 
     The quantity of light from the light sources  24 C′,  24 L 1 ′ to  24 L 4 ′ and  24 R 1  to  24 R 4 ′ may increase moving away from a center line of the housing  10  in the direction perpendicular to the center line of the housing  10 . Here, the center line may be the same as that described above with reference to  FIGS. 1 and 2 . 
     The first light source  24 C′, which is aligned with the reference line  101 , may be of an E-type and may emit the smallest quantity of light, and the quantity of light from the light sources  24 L 1 ′ to  24 L 4 ′ and  24 R 1  to  24 R 4 ′ may increase moving away from the reference line  101  or the first light source  24 C′. 
     As an example, the D-type light source  24 L 1 ′, the C-type light source  24 L 2 ′, the B-type light source  24 L 3 ′, and the A-type light source  24 L 4 ′ may be arranged sequentially to the left from the reference line  101  or from the first light source  24 C′. 
     The D-type light source  24 R 1 ′, the C-type light source  24 R 2 ′, the B-type light source  24 R 3 ′, and the A-type light source  24 R 4 ′ may be arranged sequentially to the right from the reference line  101  or from the first light source  24 C′. 
     Further, the separation distances between the adjacent light sources, for example, the pitches a′, b′, c′ and d′, may increase (a′&lt;b′&lt;c′&lt;d′) moving away from the reference line  101  or the first light source  24 C′. 
     Each of the plurality of lenses  32 C′,  32 L 1 ′ to  32 L 4 ′ and  32 R 1 ′ to  32 R 4 ′ may be arranged so as to correspond to or to be aligned with a respective one of the plurality of light sources  24 C′,  24 L 1 ′ to  24 L 4 ′ and  24 R 1 ′ to  24 R 4 ′. 
     As an example, the center of each of the plurality of lenses  32 C′,  32 L 1 ′ to  32 L 4 ′ and  32 R 1 ′ to  32 R 4 ′ may be aligned with the center of a corresponding one of the plurality of light sources  24 C′,  24 L 1 ′ to  24 L 4 ′ and  24 R 1 ′ to  24 R 4 ′ in the vertical direction. Here, the vertical direction may be a direction that is perpendicular to the top surface of the substrate  22  and is oriented toward the lens array unit  30  from the substrate  22 . 
     The separation distance between two adjacent lenses may be equal to the separation distance between two adjacent light sources that correspond to the two adjacent lenses. 
     The separation distance between two adjacent lenses may increase moving away from the reference line  101  in the second direction. 
     The separation distance between two adjacent light sources and the separation distance between two adjacent lenses may increase moving away from the center line of the housing  10  in the direction perpendicular to the center line of the housing  10 . 
     The size of each of the plurality of lenses  32 C′,  32 L 1 ′ to  32 L 4 ′ and  32 R 1 ′ to  32 R 4 ′ may be proportional to the quantity of light from a corresponding one of the light sources  24 C′,  24 L 1 ′ to  24 L 4 ′ and  24 R 1 ′ to  24 R 4 ′. 
     The sizes of the lenses  32 C′,  32 L 1 ′ to  32 L 4 ′ and  32 R 1 ′ to  32 R 4 ′ may increase moving away from the center line of the housing  10  in the direction perpendicular to the center line of the housing  10 . 
     The first lens  32 C′, which is aligned with the reference line  101 , may have the smallest size, and the sizes of the arranged lenses  32 L 1 ′ to  32 L 4 ′ and  32 R 1 ′ to  32 R 4 ′ may increase moving away from the reference line  101  or the first lens  32 C′. 
     As an example, the second lens  32 L 1 ′, the third lens  32 L 2 ′, the fourth lens  32 L 3 ′, and the fifth lens  32 L 4 ′ may be arranged sequentially to the left from the reference line  101  or from the first lens  32 C′, and the sizes of the lenses may be as follows: first lens  32 C′&lt;second lens  32 L 1 ′&lt;third lens  32 L 2 ′&lt;fourth lens  32 L 3 ′&lt;fifth lens  32 L 4 ′. 
     The second lens  32 R 1 ′, the third lens  32 R 2 ′, the fourth lens  32 R 3 ′, and the fifth lens  32 R 4 ′ may be arranged sequentially to the right from the reference line  101  or from the first lens  32 C′, and the sizes of the lenses may be as follows: first lens  32 C′&lt;second lens  32 R 1 ′&lt;third lens  32 R 2 ′&lt;fourth lens  32 R 3 ′&lt;fifth lens  32 R 4 ′. 
     The light beams emitted from the plurality of lenses  32 C′,  32 L 1 ′ to  32 L 4 ′ and  32 R 1 ′ to  32 R 4 ′ may have luminance distributions having different sizes in the optical sheet  50 . 
     As an example, the light emitted from the first lens  32 C′, which corresponds to the first light source  24 C′, which is of an E-type, may have the smallest luminance distribution, and the size of the luminance distribution may increase moving away from the first lens  32 C′. 
     Further, as an example, the diameter of the luminance distribution of the light emitted from the first lens  32 C′, which corresponds to the first light source  24 C′, which is of an E-type, may be equal to a separation distance a′ between the first light source  24 C′ and the second light source  24 L 1 ′ and  24 R 1 ′ or a separation distance between the first lens  32 C′ and the second lens  34 L 1 ′ and  34 R 1 ′. 
     Further, as an example, the diameter of the luminance distribution of the light emitted from the third lens  32 L 2 ′ and  32 R 2 ′, which corresponds to the third light source  24 L 2 ′ and  24 R 2 ′, which is of a C-type, may be equal to a value obtained by dividing the sum of a separation distance b′ and a separation distance c′ by 2′ ((b′+c′)/2). 
     The separation distance b′ may be a separation distance between the second light source  24 L 1 ′ and  24 R 1 ′ and the third light source  24 L 2 ′ and  24 R 2 ′ or a separation distance between the second lens  34 L 1 ′ and  34 R 1 ′ and the third lens  34 L 2 ′ and  34 R 2 ′. 
     The separation distance c may be a separation distance between the third light source  24 L 2 ′ and  24 R 2 ′ and the fourth light source  24 L 3 ′ and  24 R 3 ′ or a separation distance between the third lens  34 L 2 ′ and  34 R 2 ′ and the fourth lens  34 L 3 ′ and  34 R 3 ′. 
     The diameter of the luminance distribution of the light emitted from the fifth lens  32 L 4 ′ and  32 R 4 ′, which corresponds to the fifth light source  24 L 4 ′ and  24 R 4 ′, which is an A-type, may be equal to a separation distance d′. 
     The separation distance d′ may be a separation distance between the fourth light source  24 L 3 ′ and  24 R 3 ′ and the fifth light source  24 L 4 ′ and  24 R 4 ′ or a separation distance between the fourth lens  34 L 3 ′ and  34 R 3 ′ and the fifth lens  34 L 4 ′ and  34 R 4 ′. 
     The angle of beam spread of the light emitted from each of the plurality of lenses  32 C′,  32 L 1 ′ to  32 L 4 ′ and  32 R 1 ′ to  32 R 4 ′ may be proportional to the quantity of light from a corresponding one of the light sources  24 C′,  24 L 1 ′ to  24 L 4 ′ and  24 R 1 ′ to  24 R 4 ′. 
     The quantity of light from the light sources  24 C′,  24 L 1 ′ to  24 L 4 ′ and  24 R 1 ′ to  24 R 4 ′ may increase, and the angle of beam spread of the light emitted from the corresponding lenses  32 C′,  32 L 1 ′ to  32 L 4 ′ and  32 R 1 ′ to  32 R 4 ′ may increase moving away from the center line of the housing  10  in the direction perpendicular to the center line of the housing  10 . 
     As an example, the quantity of light from the light sources  24 C′,  24 L 1 ′ to  24 L 4 ′ and  24 R 1 ′ to  24 R 4 ′ may increase, and the angle of beam spread of the light emitted from the corresponding lenses  32 C′,  32 L 1 ′ to  32 L 4 ′ and  32 R 1 ′ to  32 R 4 ′ may increase moving away from the reference line  101  in the second direction. 
     According to the embodiment  200 , the sizes of the lenses  32 C′,  32 L 1 ′ to  32 L 4 ′ and  32 R 1 ′ to  32 R 4 ′ are proportional to the quantity of light from the light sources  24 C′,  24 L 1 ′ to  24 L 4 ′ and  24 R 1 ′ to  24 R 4 ′, and the separation distance between two adjacent light sources and the separation distance between two adjacent lenses are adjusted in consideration of the quantity of light, thereby improving the luminance uniformity and the color uniformity and preventing yield reduction. 
       FIG. 8  illustrates the arrangement of the light sources depending on the quantity of light according to another embodiment. 
     Referring to  FIG. 8 , another embodiment may comprise a light-emitting module, which includes a substrate  22  and first light sources  24   a   1  to  24   a   4  and second light sources  24   b   1  to  24   b   3  disposed on the substrate  22  while being spaced apart from each other. 
     Each of the second light sources  24   b   1  to  24   b   3  may be disposed between two adjacent corresponding first light sources  24   a   1  and  24   a   2 ,  24   a   2  and  24   a   3 , and  24   a   3  and  24   a   4 . 
     The first light sources  24   a   1  to  24   a   4  may emit the same quantity of light as each other, and the second light sources  24   b   1  to  24   b   3  may emit the same quantity of light as each other. Further, the quantity of light from the first light sources  24   a   1  to  24   a   4  may be different from the quantity of light from the second light sources  24   b   1  to  24   b   3 . 
     As an example, each of the first light sources  24   a   1  to  24   a   4  may be a B-type light source, and each of the second light sources  24   b   1  to  24   b   3  may be an A-type light source. That is, the quantity of light from each of the first light sources  24   a   1  to  24   a   4  may be smaller than the quantity of light from each of the second light sources  24   b   1  to  24   b   3 . 
     Another embodiment may include first lenses  32   a   1  to  32   a   4 , which correspond to the first light sources  24   a   1  to  24   a   4 , and second lenses  32   b   1  to  32   b   3 , which correspond to the second light sources  24   b   1  to  24   b   3 . 
     The separation distances between the first light sources and the second light sources adjacent to each other may be the same as each other, and the separation distances between the first lenses and the second lenses adjacent to each other may also be the same as each other. 
     The size R 1  of each of the first lenses  32   a   1  to  32   a   4  may be smaller than the size R 2  of each of the second lenses  32   b   1  to  32   b   3  (R 1 &lt;R 2 ). 
       FIG. 9  illustrates a lighting device  300  according to another embodiment. 
     Referring to  FIG. 9 , a lighting device  300  may comprise a housing  10 - 1 , a plurality of light source units  301  to  303 , a power supply unit (not shown), and an optical sheet (not shown). Although not illustrated in  FIG. 9 , the power supply unit and the optical sheet may be the same as those described above with reference to  FIGS. 1 and 2 . 
     The embodiment illustrated in  FIGS. 1 and 2  includes a single light source unit  20  and  30 ; however, the embodiment  300  illustrated in  FIG. 9  includes a plurality of light source units  301  to  303 . 
     Each of the plurality of light source units  301  to  303  may be embodied as any one of the light source units  24  and  24 ′, which are included in the embodiments in  FIGS. 1, 7 and 8 . 
     The embodiment illustrated in  FIG. 9  may be used for flat lighting devices or backlight units. 
       FIG. 10  illustrates a lighting device  400  according to another embodiment. 
     Referring to  FIG. 10 , a lighting device  400  comprises a light-emitting module, which includes a substrate  22   a  and light sources (not shown) disposed on the substrate  22   a , and a lens array unit  30 - 2 , which is disposed on the light-emitting module. The lens array unit  30 - 2  may include a plurality of lenses  32 - 1 ,  32   a   1  to  32   a   3  and  32   b   1  to  32   b   3 , which are arranged so as to be spaced apart from each other, and a connection portion  34  for connecting the plurality of lenses  32 - 1 ,  32   a   1  to  32   a   3  and  32   b   1  to  32   b   3 . 
     When compared to  FIGS. 1 and 2 , the embodiment may have a structure in which the substrate  22   a  of the light-emitting module and the connection portion  34  of the lens array unit  30 - 2  are formed to have stepped portions so as to correspond to the shape of the application in which the lighting device is disposed. 
     The lighting device  400  depicted in  FIG. 10  may be used for headlamps for vehicles or curved display apparatuses. 
     As described above with reference to  FIGS. 2, 7 and 8 , the values of quantity of light from the light sources may be different from each other, and the separation distances between the light sources may be different from each other based on the different values of the quantity of light. 
     The sizes of the lenses  32 - 1 ,  32   a   1  to  32   a   3  and  32   b   1  to  32   b   3 , which correspond to the respective light sources, may be different from each other. Each of the lenses  32 - 1 ,  32   a   1  to  32   a   3  and  32   b   1  to  32   b   3  may be arranged so as to correspond to or to be aligned with a respective one of the light sources. The size of each of the lenses  32 - 1 ,  32   a   1  to  32   a   3  and  32   b   1  to  32   b   3  may be proportional to the quantity of light from a corresponding one of the light sources. 
     The separation distance between the lenses, the separation distance between the light sources, the sizes of the lenses, and the quantity of light from the light sources, which have been described above with reference to  FIGS. 2 and 7 , may be identically applied to the embodiment illustrated in  FIG. 10 . The lighting device  400  may further comprise a housing, a power supply unit, and an optical sheet, which have been described above with reference to  FIGS. 1 and 2 . 
       FIG. 11  illustrates the arrangement of light sources and lenses and the sizes of the lenses in a lighting device according to a comparative example, and  FIG. 12  illustrates the luminance distribution of the lighting device depicted in  FIG. 11 . 
     Referring to  FIGS. 11 and 12 , in the comparative example, light sources (not shown) and lenses  510 - 1  to  510 - 3  aligned with the light sources may be arranged in a matrix form, which includes rows and columns. 
     The quantity of light from the light sources may decrease moving away from the reference line  101  in the horizontal direction. As an example, the quantity of light from the first light source, which is the closest to the center line  101 , may be 130 [lm], the quantity of light from the third light source, which is the farthest from the reference line  101 , may be 90 [lm], and the quantity of light from the second light source, which is disposed between the first light source and the third light source, may be 110 [lm]. 
     The separation distances between the adjacent light sources may be the same as each other, and the separation distances between the adjacent lenses may be the same as each other. Further, the sizes of the lenses may all be the same regardless of the quantity of light from the light sources. 
     It can be seen from  FIG. 12  that the luminance uniformity of the lighting device depicted in  FIG. 11  is about 75%. 
       FIG. 13  illustrates the arrangement of light sources and lenses and the sizes of the lenses in the lighting device according to the embodiment, and  FIG. 14  illustrates the luminance distribution of the lighting device depicted in  FIG. 13 . 
     The embodiment illustrated in  FIG. 13  may have a configuration similar to that of the lighting device  400  depicted in  FIG. 9 . Light sources (not shown) and lenses  610   a   1  to  610   a   3  and  610   b   1  to  610   b   3  aligned with the light sources, which are included in the lighting device depicted in  FIG. 13 , may be arranged in a matrix form, which includes rows and columns. 
     The quantity of light from the light sources may decrease moving away from the reference line  101  in the horizontal direction. As an example, the quantity of light from the first light source, which is the closest to the reference line  101 , may be 130 [lm], the quantity of light from the third light source, which is the farthest from the reference line  101 , may be 90 [lm], and the quantity of light from the second light source, which is disposed between the first light source and the third light source, may be 110 [lm]. 
     The separation distances between the adjacent light sources may be the same as each other, and the separation distances between the adjacent lenses may be the same as each other. 
     The difference from the comparative example is that the sizes of the lenses  610   a   1  to  610   a   3  and  610   b   1  to  610   b   3  depicted in  FIG. 13  may be different from each other in consideration of the quantity of light from the light sources. 
     As an example, the sizes of the lenses  610   a   1  to  610   a   3  and  610   b   1  to  610   b   3  may decrease moving away from the reference line  101  in the horizontal direction. Here, the horizontal direction may be the direction perpendicular to the reference line  101 . 
     It can be seen from  FIG. 14  that the luminance uniformity of the lighting device depicted in  FIG. 13  is about 90%. 
     In the comparative example, while the quantity of light from the light sources decreases moving away from the reference line  101  in the horizontal direction, the lenses  510 - 1 ,  510 - 2  and  510 - 3  have the same size, which causes a lack of quantity of light in the edge portion of the lighting device and degraded luminance uniformity of the lighting device. 
     Meanwhile, according to the embodiment, the sizes of the lenses  610   a   1  to  610   a   3  and  610   b   1  to  610   b   3  decrease moving away from the reference line  101  in the horizontal direction in consideration of the configuration in which the quantity of light from the light sources decreases moving away from the reference line  101  in the horizontal direction, thereby improving the luminance uniformity of the lighting device. 
     Features, structures and effects and the like described in association with the embodiments above are incorporated into at least one embodiment of the present disclosure, but are not limited only to one embodiment. Furthermore, features, structures and effects and the like exemplified in association with respective embodiments can be implemented in other embodiments through combination or modification by those skilled in the art. Therefore, contents related to such combinations and modifications should be construed as falling within the scope of the present disclosure. 
     INDUSTRIAL APPLICABILITY 
     The embodiments may be used for lighting devices.