Abstract:
A luminous flux control member ( 120 ) has: a light input surface ( 121 ) having inputted thereto light that has been outputted from a light emitting element ( 110 ); a total reflecting surface ( 122 ) which totally reflects a part of the light inputted from the light input surface ( 121 ); and a light output surface ( 123 ), which outputs a part of the light inputted from the light input surface ( 121 ), and the light reflected by the total reflecting surface ( 122 ). The light output surface ( 123 ) of the luminous flux control member ( 120 ) has a substantially toroidal shape or a saddle-like shape.

Description:
TECHNICAL FIELD 
     The present invention relates to a light flux controlling member that controls a distribution of light emitted from a light emitting element. In addition, the present invention relates to a light emitting device having the light flux controlling member, and a lighting apparatus having the light emitting device. 
     BACKGROUND ART 
     An internal illumination signboard is a signboard in which a light source is disposed such that the signboard itself emits light. Because of their excellent advertising effect, internal illumination signboards are used in various places. 
     In recent years, light-emitting diodes (LEDs) have been increasingly used as the light source of internal illumination signboards. Light-emitting diodes have excellent characteristics such as their small size, good power efficiency, capability of emitting light of brilliant colors, reduced risk of blowout, excellent initial drive characteristics, invulnerability to vibration, and invulnerability to repetitive switching between on and off. 
     The direction of the light emitted from a light-emitting diode is not controlled, and therefore, when the light emitted from the light-emitting diode is used as it is, the light is expanded and cannot efficiently illuminate the surface to be illuminated. For the purpose of controlling the direction of the light emitted from a light-emitting diode, a light source including the combination of a light-emitting diode and a lens has been proposed (see, for example, PTLs 1 and 2). 
     PTL 1 discloses a lens for a light-emitting diode that has an emission surface rotationally symmetrical (circularly symmetrical) about the optical axis of the light-emitting diode. PTL 2 discloses a lens for a light-emitting diode that has an emission surface of a substantially cylindrical form (which has a curvature on the first side thereof, and has no curvature on the second side orthogonal to the first side). 
     CITATION LIST 
     Patent Literature 
     PTL 1 
     
         
         Japanese Patent Application Laid-Open No. 2005-268166
 
PTL 2
 
         Japanese Design Registration No. 1271799 
       
    
     SUMMARY OF INVENTION 
     Technical Problem 
     From the perspective of arrangement of light sources, internal illumination signboards can be roughly categorized into the direct-type and the edge-lit type.  FIG. 1A  is a perspective view illustrating an exemplary direct-type internal illumination signboard, and  FIG. 1B  is a perspective view illustrating an exemplary edge-lit type hollow internal illumination signboard. As illustrated in  FIG. 1A , in the case of the direct type, light emitting devices  20  (light source) are disposed on the rear side of illumination surface (display surface)  10 . On the other hand, as illustrated in  FIG. 1B , in the case of the edge-lit type, light emitting devices  20  are disposed at outer periphery portions of a signboard. The edge-lit type hollow internal illumination signboards are superior to the direct-type internal illumination signboards in that the structure can be simplified. 
       FIG. 2  is a perspective view illustrating an exemplary edge-lit type hollow internal illumination signboard. A plurality of light emitting devices  20  are disposed on base plate  30  so as to be aligned with a straight line in parallel with illumination surface  10 . In  FIG. 2 , the x axis is an axis along which light emitting devices  20  are arranged. The y axis is an axis in parallel with base plate  30  and perpendicular to the x axis. The z axis is an axis perpendicular to base plate  30  and in parallel with the central axis of light emitting device  20 . Illumination surface  10  is in parallel with the xz plane. 
     In the case of the edge-lit type hollow internal illumination signboard illustrated in  FIG. 2 , when a light emitting device composed of a combination of a light-emitting diode and an existing lens for a light-emitting diode is used as a light source, uneven illuminance is easily caused on the illuminated surface. 
     For example, in a light emitting device including a lens having an emission surface rotationally symmetrical (circularly symmetrical) about the optical axis of the light-emitting diode as disclosed in PTL 1, the light-collecting power is the same in all 360 degrees about central axis CA of the light emitting device. For this reason, even when the light-collecting power in the y-axis direction illustrated in  FIG. 2  is appropriate, the light-collecting power in the x-axis direction may be excessively strong in some cases. In such case, as illustrated in  FIG. 3A , bright site  40  (bright region) is formed on the illuminated surface at a position near the light emitting device in the z-axis direction, and near central axis CA of the light emitting device in the x-axis direction. It is to be noted that, in  FIG. 3A  and in  FIG. 3B , regions illuminated by light are illustrated in white to black, and regions that appear bright because the amount of light applied thereto is particularly larger than the other regions are illustrated in black. 
     On the other hand, in the case of a light emitting device having a lens having an emission surface of a substantially cylindrical form as disclosed in PTL 2, when the unit is disposed in such a manner that a direction of an emission surface which has no curvature is in parallel with the x axis (surface to be illuminated), light can be expanded in the x-axis direction to prevent a dark site from being formed on the illuminated surface. The lens having the emission surface of the substantially cylindrical form, however, cannot control the light distribution in the x-axis direction in accordance with the interval between light emitting devices. For this reason, as illustrated in  FIG. 3B , shining site  50  (excessively bright region) is easily formed on illumination surface  10  in regions between light emitting devices  20 . 
     As described, there has been a problem that when a light emitting device having a light emitting element (light-emitting diode) and an existing light flux controlling member (lens) is used as a light source of an edge-lit type hollow internal illumination signboard, uneven illuminance is easily caused on the illuminated surface. 
     An object of the present invention is to provide a light flux controlling member used in a light emitting device, which light flux controlling member has different light-collecting powers which differ depending on the directions about the central axis (optical axis) of the light emitting device so that a surface to be illuminated disposed substantially in parallel with the central axis (optical axis) of the light emitting device can be uniformly illuminated. Another object of the present invention is to provide a light emitting device having the light flux controlling member, and a lighting apparatus having the light emitting device. 
     Solution to Problem 
     A light flux controlling member according to an embodiment of the present invention controls a distribution of light emitted from a light emitting element, and includes: an incidence surface on which light emitted from the light emitting element is incident; a total reflection surface that totally reflects part of the light incident on the incidence surface; and an emission surface that emits the part of the light incident on the incidence surface and the light reflected by the total reflection surface, wherein the incidence surface is so formed as to face the light emitting element and to intersect with a central axis of the light flux controlling member, the emission surface is so formed as to face away from the incidence surface and to intersect with the central axis of the light flux controlling member, the total reflection surface is so formed as to surround the central axis of the light flux controlling member and to have a diameter that gradually increases from a side of the incidence surface toward a side of the emission surface, and, when the light flux controlling member is disposed in a three-dimensional orthogonal coordinate system in such a manner that a light emission center of the light emitting element is located at an origin, that the central axis of the light flux controlling member corresponds to a z axis, and that a direction in which light travels from the light emission center of the light emitting element toward the emission surface is a forward direction of the z axis, the emission surface satisfies the following Expression (1) and Expression (2)
 
Δ Z   1   &gt;ΔZ   2   (1)
 
Δ Z   2 ≠0  (2)
 
where ΔZ 1  represents a value obtained by subtracting a z-coordinate value of a point which has a maximum y-coordinate value on the emission surface from a z-coordinate value of an intersection of the central axis of the light flux controlling member with the emission surface, and ΔZ 2  represents a value obtained by subtracting a z-coordinate value of a point which has a maximum x-coordinate value on the emission surface from the z-coordinate value of the intersection of the central axis of the light flux controlling member with the emission surface, the light flux controlling member being disposed in the three-dimensional orthogonal coordinate system in such a manner that ΔZ 2  has a minimum value.
 
     A light emitting device according to an embodiment of the present invention includes: the light flux controlling member; and a light emitting element, wherein the light flux controlling member is disposed in such a manner that a central axis of the light flux controlling member matches an optical axis of the light emitting element. 
     A lighting apparatus according to an embodiment of the present invention includes: the light emitting device; and a planar surface to be illuminated by light from the light emitting device, wherein the light emitting device is disposed in such a manner that the x axis in the three-dimensional orthogonal coordinate system is in parallel with the planar surface to be illuminated. 
     Advantageous Effects of Invention 
     The light emitting device having the light flux controlling member of the embodiment of the present invention can more uniformly illuminate a surface to be illuminated in comparison with existing light emitting devices. In addition, the lighting apparatus of the embodiment of the present invention can more uniformly illuminate a surface to be illuminated in comparison with existing lighting apparatuses. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1A  is a perspective view illustrating an exemplary direct-type internal illumination signboard, and  FIG. 1B  is a perspective view illustrating an exemplary edge-lit type hollow internal illumination signboard; 
         FIG. 2  is a perspective view illustrating an exemplary edge-lit type hollow internal illumination signboard which has a plurality of light emitting devices; 
         FIG. 3A  is a front view illustrating a surface to be illuminated of an edge-lit type hollow internal illumination signboard which has a light emitting device including a light flux controlling member having a rotationally symmetrical emission surface, and  FIG. 3B  is a front view illustrating a surface to be illuminated of an edge-lit type hollow internal illumination signboard which has a light emitting device including a light flux controlling member having an emission surface of a substantially cylindrical form; 
         FIG. 4  is a perspective view of a light emitting device of Embodiment 1; 
         FIG. 5A  is a front view of the light emitting device of Embodiment 1, and  FIG. 5B  is a side view of the light emitting device of Embodiment 1; 
         FIG. 6A  is a plan view of the light emitting device of Embodiment 1, and  FIG. 6B  is a bottom view of the light emitting device of Embodiment 1; 
         FIG. 7A  is a sectional view taken along the line A-A of  FIG. 5A , and  FIG. 7B  is a sectional view taken along the line B-B of  FIG. 5B ; 
         FIG. 8A  is a perspective view of the light emitting device of Embodiment 1 for illustrating a generatrix of an emission surface, and  FIG. 8B  is a schematic view for illustrating a toroidal form in a narrow sense; 
         FIG. 9  is a schematic view for illustrating a toroidal form in a broad sense; 
         FIG. 10A  is a perspective view of a light flux controlling member having a rotationally symmetrical emission surface, and  FIG. 10B  is a perspective view of a light flux controlling member having an emission surface of a substantially cylindrical form; 
         FIG. 11  is a schematic view for describing a light emission angle in a simulation; 
         FIG. 12  is a schematic view for describing a positional relationship between a light emitting device and a surface to be illuminated in a simulation; 
         FIG. 13A  and  FIG. 13B  each illustrate intersections of light beams with an emission surface in the case of a light flux controlling member having a rotationally symmetrical emission surface; 
         FIG. 14  is a front view illustrating an illuminated surface of an edge-lit type hollow internal illumination signboard which has the light emitting device of Embodiment 1; 
         FIG. 15  is a perspective view of the lighting apparatus of Embodiment 1; 
         FIG. 16  is an enlarged plan view illustrating a part of the lighting apparatus of Embodiment 1; 
         FIG. 17A  is a sectional view illustrating an exemplary double-side type internal illumination lighting apparatus,  FIG. 17B  is a sectional view illustrating an exemplary one-side type internal illumination lighting apparatus, and  FIG. 17C  is a sectional view illustrating an exemplary externally illuminating lighting apparatus; 
         FIG. 18  is a perspective view of a light emitting device of Embodiment 2; 
         FIG. 19A  is a front view of the light emitting device of Embodiment 2, and  FIG. 19B  is a side view of the light emitting device of Embodiment 2; 
         FIG. 20A  is a plan view of the light emitting device of Embodiment 2, and  FIG. 20B  is a bottom view of the light emitting device of Embodiment 2; 
         FIG. 21A  is a sectional view taken along the line A-A of  FIG. 19A , and  FIG. 21B  is a sectional view taken along the line B-B of  FIG. 19B ; 
         FIG. 22  is a perspective view of a light emitting device of Embodiment 3; 
         FIG. 23A  is a front view of the light emitting device of Embodiment 3, and  FIG. 23B  is a back view of the light emitting device of Embodiment 3, and  FIG. 23C  is a side view of the light emitting device of Embodiment 3; 
         FIG. 24A  is a plan view of the light emitting device of Embodiment 3, and  FIG. 24B  is a bottom view of the light emitting device of Embodiment 3; and 
         FIG. 25  is a sectional view taken along the line A-A of  FIG. 23C . 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Now, embodiments of the present invention will be described in detail with reference to the accompanying drawings. 
     Embodiment 1 
     [Configuration of Light Emitting Device] 
       FIGS. 4 to 7  illustrate the configuration of a light emitting device of Embodiment 1 of the present invention.  FIG. 4  is a perspective view of the light emitting device of Embodiment 1.  FIG. 5A  is a front view of the light emitting device of Embodiment 1, and  FIG. 5B  is a side view of the light emitting device of Embodiment 1.  FIG. 6A  is a plan view of the light emitting device of Embodiment 1, and  FIG. 6B  is a bottom view of the light emitting device of Embodiment 1.  FIG. 7A  is a sectional view taken along the line A-A of  FIG. 5A , and  FIG. 7B  is a sectional view taken along the line B-B of  FIG. 5B . 
     Here, as illustrated in  FIG. 4 , light flux controlling member  120  will be described on the assumption that light flux controlling member  120  is disposed in a three-dimensional orthogonal coordinate system in such a manner that the light emission center of light emitting element  110  is located at the origin, and central axis CA of light flux controlling member  120  extends along the z axis. The light axis direction of light emitting element  110  (the direction towards emission surface  123  of light flux controlling member  120  from the light emission center of light emitting element  110 ) corresponds to the forward direction of the z axis. It is to be noted that the description will be made on the assumption that light flux controlling member  120  is disposed in the three-dimensional orthogonal coordinate system in such a manner that ΔZ 2  described later has the minimum value. 
     As illustrated in  FIGS. 4 to 7 , light emitting device  100  of Embodiment 1 includes light emitting element  110  and light flux controlling member  120 . Light flux controlling member  120  is formed by integral molding. The material of light flux controlling member  120  is not specifically limited as long as light having desired wavelengths can pass through light flux controlling member  120 . Examples of the material of light flux controlling member  120  include light transmissive resins such as polymethylmethacrylate (PMMA), polycarbonate (PC), and epoxy resin (EP), and glass. 
     Light emitting element  110  is a light source of light emitting device  100 . Light emitting element  110  is composed of a light-emitting diode (LED) such as a white light-emitting diode, for example. Light emitting element  110  is disposed in recess  124  formed on the bottom side of light flux controlling member  120  (see  FIG. 7A  and  FIG. 7B ). 
     Light flux controlling member  120  controls the travelling direction of light emitted from light emitting element  110 . Light flux controlling member  120  is disposed in such a manner that central axis CA thereof matches the optical axis of light emitting element  110  (see  FIG. 7A  and  FIG. 7B ). 
     As illustrated in  FIG. 7A  and  FIG. 7B , light flux controlling member  120  includes incidence surface  121  on which light emitted from light emitting element  110  is incident, total reflection surface  122  that totally reflects part of light incident on incidence surface  121 , and emission surface  123  that emits part of light incident on incidence surface  121  and light reflected by total reflection surface  122 . 
     Incidence surface  121  is an internal surface of recess  124  formed on the bottom side of light flux controlling member  120 . Incidence surface  121  is so formed as to face light emitting element  110  and to intersect with central axis CA of light flux controlling member  120 . Incidence surface  121  is a rotationally symmetrical surface formed about central axis CA. Incidence surface  121  includes internal top surface  121   a  composing the top surface of recess  124 , and tapered internal surface  121   b  composing the side surfaces of recess  124 . The internal diameter of internal surface  121   b  is gradually increased from internal top surface  121   a  side toward the opening edge side so that the internal diameter of the opening edge is greater than that of internal top surface  121   a.    
     Total reflection surface  122  is a surface that extends from the outer edge of the bottom of light flux controlling member  120  to the outer edge of emission surface  123 . A flange may be provided between the outer edge of total reflection surface  122  and the outer edge of emission surface  123 . Total reflection surface  122  is a rotationally symmetrical surface that is so formed as to surround central axis CA of light flux controlling member  120 . The diameter of total reflection surface  122  gradually increases from incidence surface  121  side (bottom side) toward emission surface  123  side. The generatrix of total reflection surface  122  is an arc-like curve protruding outward (away from central axis CA) (see  FIG. 7A  and  FIG. 7B ). 
     Emission surface  123  is located on the side opposite to incidence surface  121  (bottom) in light flux controlling member  120 , and is so formed as to intersect with central axis CA of light flux controlling member  120 . As illustrated in  FIG. 4 , emission surface  123  is plane-symmetrical to the xz plane. 
     Light flux controlling member  120  of Embodiment 1 is mainly characterized in that the form of emission surface  123  satisfies the following Expression (1) and Expression (2).
 
Δ Z   1   &gt;ΔZ   2   (1)
 
Δ Z   2 ≠0  (2)
 
     In Expression (1) and Expression (2), ΔZ 1  represents a value obtained by subtracting the z-coordinate value of the point which has the maximum y-coordinate value on emission surface  123 , from the z-coordinate value of the intersection (the vertex of emission surface  123 ) of central axis CA (the z axis) with emission surface  123  of light flux controlling member  120 . In other words, as illustrated in  FIG. 4  and  FIG. 5B , ΔZ 1  represents a variation of the z-coordinate on emission surface  123  relative to the y-axis direction. In light flux controlling member  120  of Embodiment 1, emission surface  123  has a convex form, and therefore ΔZ 1  is a positive value. 
     In addition, in Expression (1) and Expression (2), ΔZ 2  represents a value obtained by subtracting the z-coordinate value of the point which has the maximum x-coordinate value on emission surface  123 , from the z-coordinate value of the intersection (the vertex of emission surface  123 ) of central axis CA (the z axis) with emission surface  123  of light flux controlling member  120 . In other words, as illustrated in  FIG. 4  and  FIG. 5B , ΔZ 2  represents a variation of the z-coordinate on emission surface  123  relative to the x-axis direction. In light flux controlling member  120  of Embodiment 1, emission surface  123  has a convex form, and therefore ΔZ 2  is a positive value. As described above, light flux controlling member  120  disposed in the three-dimensional orthogonal coordinate system in such a manner that ΔZ 2  has the minimum value (see  FIG. 4 ). 
     Expression (2) means that emission surface  123  has a curvature in a cross-section (the xz plane) at y=0 (see  FIG. 5A ). In the case of a light flux controlling member having an emission surface of a substantially cylindrical form, ΔZ 2 =0 is satisfied. Accordingly, when Expression (2) is satisfied, emission surface  123  of light flux controlling member  120  does not have a substantially cylindrical form. 
     In addition, Expression (1) means that the curvature of emission surface  123  in the cross-section (the yz plane) at x=0 differs from the curvature of emission surface  123  in the cross-section (the xz plane) at y=0 (see and compare  FIG. 5A  with  FIG. 5B ). In the case of the light flux controlling member having a rotationally symmetrical emission surface, ΔZ 1 =ΔZ 2  is satisfied. Accordingly, when Expression (1) is satisfied, emission surface  123  of light flux controlling member  120  does not have a rotationally symmetrical form. 
     Emission surface  123  of light flux controlling member  120  has a substantially toroidal form. The “substantially toroidal form” herein is a form which has a ridgeline on the xz plane, has a curvature in any cross-section in parallel with the xz plane, and satisfies R 1 =R 2  in any cross-section in parallel with the xz plane, where R 1  represents a curvature radius of the emission surface of x=0, and R 2  represents a curvature radius of the emission surface at any point of x≠0. 
     For example, the form of emission surface  123  of light flux controlling member  120  is a toroidal form in a narrow sense. Here the “toroidal form in a narrow sense” is a form which satisfies x 1 =x 2 =0 and z 1 =z 2 , where, in the three-dimensional orthogonal coordinate system, the coordinate of curvature center O 1  of emission surface  123  in a cross-section in parallel with the xz plane at y=0 is represented by (x 1 , y 1 , z 1 ) (y 1 =0), and the coordinate of curvature center O 2  of emission surface  123  in a cross-section in parallel with the xz plane at y≠0 is represented by (x 2 , y 2 , z 2 ). 
     With reference to  FIG. 8A  and  FIG. 8B , the toroidal form in a narrow sense will be described. As illustrated in  FIG. 8A , the intersection line of emission surface  123  with the yz plane is generatrix G. In this case, as illustrated in  FIG. 8B , the form of emission surface  123  matches a part (a part cut out along the maximum diameter (outer edge) of emission surface  123 ) of the form obtained by rotating generatrix G about linear rotational axis A. That is, the curvature radius of emission surface  123  in the cross-section in parallel with the xz plane which passes through points on generatrix G of emission surface  123  differs from cross-section to another (Ra≠Rb≠Rc), and the curvature center of emission surface  123  of each of the cross-sections is located on a straight line in parallel with the y axis (a straight line obtained by translating the y axis in the z-axis direction). 
     In addition, the form of emission surface  123  of light flux controlling member  120  may also be a toroidal form in a broad sense. Here, the “toroidal form in a broad sense” means a form which satisfies x 1 =x 2 =0 and z 1 ≠z 2 , where, in the three-dimensional orthogonal coordinate system, the coordinate of curvature center O 1  of emission surface  123  in a cross-section in parallel with the xz plane at y=0 is represented by (x 1 , y 1 , z 1 ), and the coordinate of curvature center O 2  of emission surface  123  in a cross-section in parallel with the xz plane at y≠0 is represented by (x 2 , y 2 , z 2 ). 
     With reference to  FIG. 8A  and  FIG. 9 , the toroidal form in a broad sense will be described. As illustrated in  FIG. 8A , the intersection line of emission surface  123  with the yz plane is generatrix G. In this case, as illustrated in  FIG. 9 , the form of emission surface  123  is obtained by rotating generatrix G about rotational axis A in a form of a curved line. That is, the curvature radius of emission surface  123  in the cross-section in parallel with the xz plane which passes through points on generatrix G of emission surface  123  differs from cross-section to another (or may be Ra=Rb=Rc depending on the curve of the rotational axis), and the curvature center of emission surface  123  of each of the cross-sections is located on an arbitrary curve on the yz plane. It is to be noted that the straight line and the curve shown by the broken line in  FIG. 9  are the linear rotational axis and generatrix G obtained by rotating generatrix G about the linear rotational axis by 90°, in  FIG. 8B . As is clear from the comparison between the solid line and the broken line, the form of emission surface  123  differs between the toroidal form in a narrow sense and the toroidal form in a broad sense. 
     In both of the case where the form of emission surface  123  is the toroidal form in a narrow sense and the case where the form of emission surface  123  is the toroidal form in a broad sense, the distributions of light in the x-axis direction and the y-axis direction can be precisely controlled by individually adjusting the curvature radiuses Ra, Rb and Re in accordance with the positional relationship between light emitting device  100  and the surface to be illuminated. 
     [Simulation of Light Distribution Characteristics of Light Flux Controlling Member] 
     The light distribution characteristics of light flux controlling member  120  of Embodiment 1 illustrated in  FIGS. 4 to 7  was simulated. Emission surface  123  had the toroidal form in a narrow sense. For comparison, the light distribution characteristics of the light flux controlling member having the rotationally symmetrical emission surface, and a light flux controlling member having the emission surface of a substantially cylindrical form illustrated in  FIG. 10A  and  FIG. 10B  were also simulated. In this simulation, as illustrated in  FIG. 11 , light paths of light emitted from the light emission center (origin) of a light emitting element at the angle of (θ, γ) were calculated. The light flux controlling members had substantially the same size, and the outer edge of the emission surface passes through x=±8.0 and y=±8.0 (see  FIG. 13 ). As illustrated in  FIG. 12 , it was assumed that illumination surface  220  is disposed at a position of y=−20.0 in such a manner as to be in parallel with the xz plane of the light flux controlling member. 
     Table 1 to Table 3 show results of the simulation of light paths of emission light of γ=180° (light that travels in a direction perpendicular to the surface to be illuminated in plan view). Table 1 to Table 3 show coordinates of the points where light beams intersect with the surfaces of the light flux controlling member (incidence surface, total reflection surface and emission surface) and the illuminated surface. As an example,  FIG. 13A  illustrates positions of intersections of light beams in plan view of the emission surface of the light flux controlling member having the rotationally symmetrical emission surface (see  FIG. 10A ). In  FIG. 13A , the quadrangular marker represents the light emitted at γ=180° and θ=40°, the round marker the light emitted at γ=180° and θ=60°, and the triangular marker the light emitted at γ=180° and θ=70°. 
     
       
         
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 Light Path of Light Emitted at γ = 180° and θ = 40° 
               
             
          
           
               
                   
                 Light emitting 
                 Incidence 
                 Total Reflection 
                 Emission 
                 Illuminated 
               
               
                   
                 element 
                 Surface 
                 Surface 
                 Surface 
                 Surface 
               
               
                   
                   
               
             
          
           
               
                 Toroidal Form 
                 x 
                 0.0 
                 0.0 
                 0.0 
                 0.0 
                 0.0 
               
               
                 (FIGS. 4 to 7) 
                 y 
                 0.0 
                 −2.0 
                 −6.1 
                 −6.4 
                 −20.0 
               
               
                   
                 z 
                 0.0 
                 2.4 
                 5.1 
                 7.8 
                 14921.0 
               
               
                 Rotationally 
                 x 
                 0.0 
                 0.0 
                 0.0 
                 0.0 
                 0.0 
               
               
                 Symmetrical Form 
                 y 
                 0.0 
                 −2.0 
                 −6.1 
                 −6.4 
                 −20.0 
               
               
                 (FIG. 10A) 
                 z 
                 0.0 
                 2.4 
                 5.1 
                 7.8 
                 14921.0 
               
               
                 Cylindrical Form 
                 x 
                 0.0 
                 0.0 
                 0.0 
                 0.0 
                 0.0 
               
               
                 (FIG. 10B) 
                 y 
                 0.0 
                 −2.0 
                 −6.1 
                 −6.4 
                 −20.0 
               
               
                   
                 z 
                 0.0 
                 2.4 
                 5.1 
                 7.8 
                 14921.0 
               
               
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
               
             
           
               
                 TABLE 2 
               
             
             
               
                   
               
               
                 Light Path of Light Emitted at γ = 180° and θ = 60° 
               
             
          
           
               
                   
                 Light emitting 
                 Incidence 
                 Total Reflection 
                 Emission 
                 Illuminated 
               
               
                   
                 element 
                 Surface 
                 Surface 
                 Surface 
                 Surface 
               
               
                   
                   
               
             
          
           
               
                 Toroidal Form 
                 x 
                 0.0 
                 0.0 
                 0.0 
                 0.0 
                 0.0 
               
               
                 (FIGS. 4 to 7) 
                 y 
                 0.0 
                 −2.1 
                 −4.0 
                 −4.7 
                 −20.0 
               
               
                   
                 z 
                 0.0 
                 1.2 
                 2.0 
                 8.4 
                 136200.0 
               
               
                 Rotationally 
                 x 
                 0.0 
                 0.0 
                 0.0 
                 0.0 
                 0.0 
               
               
                 Symmetrical Form 
                 y 
                 0.0 
                 −2.1 
                 −4.0 
                 −4.7 
                 −20.0 
               
               
                 (FIG. 10A) 
                 z 
                 0.0 
                 1.2 
                 2.0 
                 8.4 
                 136200.0 
               
               
                 Cylindrical Form 
                 x 
                 0.0 
                 0.0 
                 0.0 
                 0.0 
                 0.0 
               
               
                 (FIG. 10B) 
                 y 
                 0.0 
                 −2.1 
                 −4.0 
                 −4.7 
                 −20.0 
               
               
                   
                 z 
                 0.0 
                 1.2 
                 2.0 
                 8.4 
                 136200.0 
               
               
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
             
           
               
                 TABLE 3 
               
             
             
               
                   
               
               
                 Light Path of Light Emitted at γ = 180° and θ = 70° 
               
             
          
           
               
                   
                   
                 Light emitting 
                 Incidence 
                 Total Reflection 
                 Emission 
                 Illuminated 
               
               
                   
                   
                 element 
                 Surface 
                 Surface 
                 Surface 
                 Surface 
               
               
                   
               
             
          
           
               
                 Toroidal Form 
                 x 
                 0.0 
                 0.0 
                 0.0 
                 0.0 
                 0.0 
               
               
                 (FIGS. 4 to 7) 
                 y 
                 0.0 
                 −2.2 
                 −3.3 
                 −4.2 
                 −20.0 
               
               
                   
                 z 
                 0.0 
                 0.8 
                 1.1 
                 8.6 
                 27275.0 
               
               
                 Rotationally 
                 x 
                 0.0 
                 0.0 
                 0.0 
                 0.0 
                 0.0 
               
               
                 Symmetrical Form 
                 y 
                 0.0 
                 −2.2 
                 −3.3 
                 −4.2 
                 −20.0 
               
               
                 (FIG. 10A) 
                 z 
                 0.0 
                 0.8 
                 1.1 
                 8.6 
                 27275.0 
               
               
                 Cylindrical Form 
                 x 
                 0.0 
                 0.0 
                 0.0 
                 0.0 
                 0.0 
               
               
                 (FIG. 10B) 
                 y 
                 0.0 
                 −2.2 
                 −3.3 
                 −4.2 
                 −20.0 
               
               
                   
                 z 
                 0.0 
                 0.8 
                 1.1 
                 8.6 
                 27275.0 
               
               
                   
               
             
          
         
       
     
     Table 1 to Table 3 suggest that the greater the value of θ, the more the emitted light reaches the upper region of the illuminated surface (the region having greater z values). As shown in Table 1 to Table 3, regarding the direction of γ=180°, there was no difference in light distribution characteristics among the light flux controlling member having the emission surface of the toroidal form (see  FIGS. 4 to 7 ), the light flux controlling member having the rotationally symmetrical emission surface (see  FIG. 10A ), and the light flux controlling member having the emission surface of the substantially cylindrical form (see  FIG. 10B ). In other words, there was no difference in y-directional light distribution characteristics among the light flux controlling members. 
     Table 4 to Table 6 show results of the simulation of light paths of emission light of γ≠180° (light that travels in a direction oblique to the surface to be illuminated in plan view). Table 4 to Table 6 show coordinates of the points where light beams intersect with the surfaces of the light flux controlling member (incidence surface, total reflection surface and emission surface) and the illuminated surface. As an example,  FIG. 13B  illustrates positions of intersections of light beams in plan view of the emission surface of the light flux controlling member having the rotationally symmetrical emission surface (see  FIG. 10A ). In  FIG. 13B , the quadrangular marker represents the light emitted at γ=50° and θ=82°, the round marker the light emitted at γ=30° and θ=85°, and the triangular marker the light emitted at γ=20° and θ=87°. 
     
       
         
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
               
             
           
               
                 TABLE 4 
               
             
             
               
                   
               
               
                 Light Path of Light Emitted at γ = 50° and θ = 82° 
               
             
          
           
               
                   
                 Light emitting 
                 Incidence 
                 Total Reflection 
                 Emission 
                 Illuminated 
               
               
                   
                 element 
                 surface 
                 Surface 
                 Surface 
                 Surface 
               
               
                   
                   
               
             
          
           
               
                 Toroidal Form 
                 x 
                 0.0 
                 1.7 
                 2.0 
                 2.8 
                 34.5 
               
               
                 (FIGS. 4 to 7) 
                 y 
                 0.0 
                 1.4 
                 1.7 
                 2.3 
                 −20.0 
               
               
                   
                 z 
                 0.0 
                 0.3 
                 0.3 
                 9.2 
                 380.2 
               
               
                 Rotationally 
                 x 
                 0.0 
                 1.7 
                 2.0 
                 2.7 
                 −23.5 
               
               
                 Symmetrical Form 
                 y 
                 0.0 
                 1.4 
                 1.7 
                 2.3 
                 −20.0 
               
               
                 (FIG. 10A) 
                 z 
                 0.0 
                 0.3 
                 0.3 
                 8.8 
                 21194.0 
               
               
                 Cylindrical Form 
                 x 
                 0.0 
                 1.7 
                 2.0 
                 2.8 
                 50.8 
               
               
                 (FIG. 10B) 
                 y 
                 0.0 
                 1.4 
                 1.7 
                 2.3 
                 −20.0 
               
               
                   
                 z 
                 0.0 
                 0.3 
                 0.3 
                 9.3 
                 372.1 
               
               
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
             
           
               
                 TABLE 5 
               
             
             
               
                   
               
               
                 Light Path of Light Emitted at γ = 30° and θ = 85° 
               
             
          
           
               
                   
                   
                 Light emitting 
                 Incidence 
                 Total Reflection 
                 Emission 
                 Illuminated 
               
               
                   
                   
                 element 
                 surface 
                 Surface 
                 Surface 
                 Surface 
               
               
                   
               
             
          
           
               
                 Toroidal Form 
                 x 
                 0.0 
                 1.1 
                 1.2 
                 1.7 
                 55.9 
               
               
                 (FIGS. 4 to 7) 
                 y 
                 0.0 
                 1.9 
                 2.1 
                 3.0 
                 −20.0 
               
               
                   
                 z 
                 0.0 
                 0.2 
                 0.2 
                 9.1 
                 969.9 
               
               
                 Rotationally 
                 x 
                 0.0 
                 1.1 
                 1.2 
                 1.7 
                 −11.4 
               
               
                 Symmetrical Form 
                 y 
                 0.0 
                 1.9 
                 2.1 
                 3.0 
                 −20.0 
               
               
                 (FIG. 10A) 
                 z 
                 0.0 
                 0.2 
                 0.2 
                 8.9 
                 17576.0 
               
               
                 Cylindrical Form 
                 x 
                 0.0 
                 1.1 
                 1.2 
                 1.7 
                 82.2 
               
               
                 (FIG. 10B) 
                 y 
                 0.0 
                 1.9 
                 2.1 
                 3.0 
                 −20.0 
               
               
                   
                 z 
                 0.0 
                 0.2 
                 0.2 
                 9.0 
                 951.5 
               
               
                   
               
             
          
         
       
     
     
       
         
               
             
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
             
           
               
                 TABLE 6 
               
             
             
               
                   
               
               
                 Light Path of Light Emitted at γ = 20° and θ = 87° 
               
             
          
           
               
                   
                   
                 Light emitting 
                 Incidence 
                 Total Reflection 
                 Emission 
                 Illuminated 
               
               
                   
                   
                 element 
                 Surface 
                 Surface 
                 Surface 
                 Surface 
               
               
                   
               
             
          
           
               
                 Toroidal Form 
                 x 
                 0.0 
                 0.8 
                 0.8 
                 1.2 
                 81.9 
               
               
                 (FIGS. 4 to 7) 
                 y 
                 0.0 
                 2.1 
                 2.2 
                 3.2 
                 −20.0 
               
               
                   
                 z 
                 0.0 
                 0.1 
                 0.1 
                 9.0 
                 2080.2 
               
               
                 Rotationally 
                 x 
                 0.0 
                 0.8 
                 0.8 
                 1.1 
                 −7.2 
               
               
                 Symmetrical Form 
                 y 
                 0.0 
                 2.1 
                 2.2 
                 3.2 
                 −20.0 
               
               
                 (FIG. 10A) 
                 z 
                 0.0 
                 0.1 
                 0.1 
                 8.9 
                 23291.0 
               
               
                 Cylindrical Form 
                 x 
                 0.0 
                 0.8 
                 0.8 
                 1.1 
                 119.8 
               
               
                 (FIG. 10B) 
                 y 
                 0.0 
                 2.1 
                 2.2 
                 3.2 
                 −20.0 
               
               
                   
                 z 
                 0.0 
                 0.1 
                 0.1 
                 9.0 
                 2045.0 
               
               
                   
               
             
          
         
       
     
     Table 4 to Table 6 suggest that the light flux controlling member having the rotationally symmetrical emission surface (see  FIG. 10A ) has small x values and great z values, and therefore has extremely strong light-collecting power. When a light emitting device including such a light flux controlling member having excessively strong light-collecting power is employed in the internal illumination signboard having illumination surface  220  in parallel with the xz plane, the amount of light for illuminating parts of the surface to be illuminated which correspond to the regions between the adjacent light emitting devices is insufficient, and thus bright sites  40  corresponding to the positions of the light emitting devices undesirably stand out (see  FIG. 3A ). In other words, dark sites are easily formed between adjacent bright sites  40 . 
     Table 4 to Table 6 also suggest that, in comparison with the light flux controlling member having the rotationally symmetrical emission surface, the light flux controlling member having the emission surface of the substantially cylindrical form (see  FIG. 10B ) can expand light in the x-axis direction (or has greater x values). However, the light flux controlling member having the emission surface of the substantially cylindrical form cannot adjust the x-directional curvature of the emission surface, and therefore cannot adjust the expansion of emitted light in accordance with the intervals of the light emitting devices. For this reason, when the light emitting device including the light flux controlling member having the emission surface of the substantially cylindrical form is used in the internal illumination signboard, shining sites  50  are easily formed between the light emitting devices (see  FIG. 3B ). 
     On the other hand, as with the light flux controlling member having the emission surface of the substantially cylindrical form, light flux controlling member  120  having the emission surface of the toroidal form (see  FIGS. 4 to 7 ) can expand light in the x-axis direction (or has great x values). Further, light flux controlling member  120  having the emission surface of the toroidal form can adjust the x-directional curvature, and therefore can adjust the expansion of emitted light in the x-axis direction in accordance with the intervals of light emitting devices  100 . Actually, in Table 4 to Table 6, light flux controlling member  120  having the emission surface of the toroidal form has smaller x values in comparison with the light flux controlling member having the emission surface of the substantially cylindrical form. For this reason, when light emitting device  100  including light flux controlling member  120  having the emission surface of the toroidal form is used in an internal illumination signboard, bright site  40  and shining site  50  are not easily formed between light emitting devices  100  illustrated in  FIG. 14 . 
     [Configuration of Lighting Apparatus] 
     Next, a lighting apparatus including light emitting device  100  of Embodiment 1 will be described. Here, as a typical example of the lighting apparatus of the embodiment of the present invention, an internal illumination type lighting apparatus (e.g., an internal illumination signboard) will be described. 
       FIG. 15  is a perspective view of lighting apparatus  200  of Embodiment 1.  FIG. 16  is a partially enlarged plan view of lighting apparatus  200  of Embodiment 1. It is to be noted that top plate  230  is omitted in  FIG. 16 . 
     As illustrated in  FIG. 15  and  FIG. 16 , lighting apparatus  200  includes base plate  210 , a plurality of light emitting devices  100 , two illumination surfaces  220   a , and  220   b , and top plate  230 . 
     Base plate  210  is a rectangular plate composing the bottom face of lighting apparatus  200 . On the other hand, top plate  230  is a rectangular plate composing the top face of lighting apparatus  200 . Base plate  210  and top plate  230  reflect the light emitted from light emitting device  100  to thereby improve the brightness and illuminance distribution in lighting apparatus  200 . 
     Light emitting devices  100  are disposed on base plate  210  in such a manner as to be aligned with a straight line in parallel with illumination surfaces  220   a  and  220   b . Normally, light emitting devices  100  are disposed in such a manner that center-to-center distances P of light emitting devices  100  have the same value (see  FIG. 16 ). Light emitting devices  100  are each disposed in such a manner that the xz plane in the three-dimensional orthogonal coordinate system is in parallel with illumination surfaces  220   a  and  220   b.    
     Illumination surfaces  220   a  and  220   b  are rectangular plates composing the side faces of lighting apparatus  200 . Illumination surfaces  220   a  and  220   b  are disposed facing each other in parallel with the xz plane of light emitting device  100 . For example, advertisement characters and advertisement illustrations and the like are drawn on illumination surfaces  220   a  and  220   b.    
     Lighting apparatus  200  is used by illuminating illumination surfaces  220   a  and  220   b  with light emitted from light emitting devices  100  disposed in lighting apparatus  200 . 
     [Effect] 
     In light emitting device  100  of Embodiment 1, the distributions of light in the x-axis direction and the y-axis direction can be individually controlled by individually adjusting the x-directional curvature and the y-directional curvature of emission surface  123  in accordance with center-to-center distance P of light emitting devices  100  (see  FIG. 16 ) and the distance between light emitting device  100  and the surface to be illuminated. Thus, in lighting apparatus  200  including light emitting device  100 , illumination surfaces  220   a  and  220   b  can be uniformly illuminated, while almost no bright site  40  and shining site  50  (see  FIG. 14 ). 
     It is to be noted that, while an exemplary internal illumination lighting apparatus having two illumination surfaces  220   a  and  220   b  has been described in the above description, the lighting apparatus of the embodiment of the present invention is not limited to this. The lighting apparatus of the embodiment of the present invention may be a double-side type internal illumination lighting apparatus having two illumination surfaces  220   a  and  220   b  illustrated in  FIG. 17A , or a one-side type internal illumination lighting apparatus having one illumination surface  220  illustrated in  FIG. 17B . In the latter case, the surface facing illumination surface  220  is preferably reflecting surface  240 . Further, the lighting apparatus of the embodiment of the present invention may be an externally illuminating lighting apparatus illustrated in  FIG. 17C . In any of the modes, light emitting device  100  is disposed in such a manner that the x axis of the three-dimensional orthogonal coordinate system is in parallel with illumination surface  220 . 
     Embodiment 2 
     [Configuration of Light Emitting Device] 
       FIGS. 18 to 21  each illustrate the configuration of a light emitting device of Embodiment 2 of the present invention.  FIG. 18  is a perspective view of the light emitting device of Embodiment 2.  FIG. 19A  is a front view of the light emitting device of Embodiment 2 and  FIG. 19B  is a side view of the light emitting device of Embodiment 2.  FIG. 20A  is a plan view of the light emitting device of Embodiment 2 and  FIG. 20B  is a bottom view of the light emitting device of Embodiment 2.  FIG. 21A  is a sectional view taken along the line A-A of  FIG. 19A  and  FIG. 21B  is a sectional view taken along the line B-B of  FIG. 19B . It is to be noted that the same components as those of light emitting device  100  of Embodiment 1 illustrated in  FIGS. 4 to 7  will be denoted by the same reference numerals and description thereof will be omitted. 
     As illustrated in  FIGS. 18 to 21 , light emitting device  300  of Embodiment 2 includes light emitting element  110  and light flux controlling member  310 . Light flux controlling member  310  is disposed in such a manner that central axis CA thereof matches the optical axis of light emitting element  110 . The following description will be made on the assumption that light flux controlling member  310  is disposed in a three-dimensional orthogonal coordinate system, as in Embodiment 1. 
     As illustrated in  FIGS. 21A and 21B , light flux controlling member  310  includes incidence surface  121  on which light emitted from light emitting element  110  in incident, total reflection surface  122  that totally reflects part of light incident on incidence surface  121 , and emission surface  311  that emits part of light incident on incidence surface  121  and light reflected by total reflection surface  122 . Light flux controlling member  310  of Embodiment 2 differs from light emitting device  100  of Embodiment 1 in only the form of emission surface  311 . Therefore the form of emission surface  311  will be described with reference to  FIGS. 18 to 21B . 
     In light flux controlling member  310  of Embodiment 2, emission surface  311  has a saddle-like form (saddle form). As with light flux controlling member  110  of Embodiment 1, in light flux controlling member  310  of Embodiment 2, the form of emission surface  311  satisfies the following Expression (1) and Expression (2).
 
Δ Z   1   &gt;ΔZ   2   (1)
 
Δ Z   2 ≠0  (2)
 
     In Expression (1) and Expression (2), ΔZ 1  represents a value obtained by subtracting the z-coordinate value of the point which has the maximum y-coordinate value on emission surface  311 , from the z-coordinate value of the intersection of central axis CA (the z axis) of light flux controlling member  310  with emission surface  311 . In other words, as illustrated in  FIG. 18  and  FIG. 19B , ΔZ 1  represents a variation of the z-coordinate on emission surface  311  relative to the y-axis direction. In light flux controlling member  310  of Embodiment 2, ΔZ 1  is a positive value. 
     In addition, in Expression (1) and Expression (2), ΔZ 2  represents a value obtained by subtracting the z-coordinate value of the point which has the maximum x-coordinate value on emission surface  311 , from the z-coordinate value of the intersection (the vertex of emission surface  311 ) of central axis CA (the z axis) of light flux controlling member  310  with emission surface  311 . In other words, as illustrated in  FIG. 18  and  FIG. 19A , ΔZ 2  represents a variation of the z-coordinate on emission surface  311  relative to the x-axis direction. In light flux controlling member  310  of Embodiment 2, emission surface  311  has a saddle form, and therefore ΔZ 2  is a negative value. As described above, light flux controlling member  310  is disposed in the three-dimensional orthogonal coordinate system in such a manner that ΔZ 2  has the minimum value (see  FIG. 18 ). 
     Expression (2) means that emission surface  311  has a curvature in a cross-section (the xz plane) at y=0 (see  FIG. 19A ). In the case of a light flux controlling member having an emission surface of a substantially cylindrical form, ΔZ 2 =0 is satisfied. Accordingly, when Expression (2) is satisfied, emission surface  311  of light flux controlling member  310  does not have a substantially cylindrical form. 
     In addition, Expression (1) means that the curvature of emission surface  311  in the cross-section (the yz plane) at x=0 differs from the curvature of emission surface  311  in the cross-section (the xz plane) at y=0 (see and compare  FIG. 19A  with  FIG. 19B ). In the case of the light flux controlling member having a rotationally symmetrical emission surface, ΔZ 1 =ΔZ 2  is satisfied. Accordingly, when Expression (2) is satisfied, emission surface  311  of light flux controlling member  310  does not have a rotationally symmetrical form. 
     As illustrated in  FIG. 18 , emission surface  311  of light flux controlling member  310  has a saddle form. The “saddle form” herein is a form which is plane-symmetrical to the xz plane and has a curvature in both of the x-axis direction and the y-axis direction, wherein the curvature center of the x-directional curvature is located on the positive side of the z axis relative to emission surface  311  whereas the curvature center of the y-directional curvature is located on the negative side of the z axis relative to emission surface  311 . 
     When R a  represents the curvature radius of emission surface  311  in the cross-section (the xz plane) at y=0, and R b  represents the curvature radius of emission surface  311  in the cross-section (any plane in parallel with the xz plane) at y≠0, R a  and R b  may either be the same value, or different values. In both cases, the distributions of light in the x-axis direction and the y-axis direction can be precisely controlled by individually adjusting the curvature radiuses R a  and R b  in accordance with the positional relationship between light emitting device  300  and the surface to be illuminated. 
     [Effect] 
     As with light emitting device  100  of Embodiment 1, light emitting device  300  of Embodiment 2 can control the distributions of light in the x-axis direction and the y-axis direction to thereby uniformly illuminate the surface to be illuminated. Thus, the lighting apparatus including light emitting device  300  can make the illuminance distribution on the illuminated surface more uniform. 
     Embodiment 3 
     [Configuration of Light Emitting Device] 
       FIGS. 22 to 25  illustrate the configuration of a light emitting device of Embodiment 3 of the present invention.  FIG. 22  is a perspective view of the light emitting device of Embodiment 3.  FIG. 23A  is a front view of the light emitting device of Embodiment 3,  FIG. 23B  is a back view of the light emitting device of Embodiment 3 and  FIG. 23C  is a side view of the light emitting device of Embodiment 3.  FIG. 24A  is a plan view of the light emitting device of Embodiment 3 and  FIG. 24B  is a bottom view of the light emitting device of Embodiment 3.  FIG. 25  is a sectional view taken along the line A-A of  FIG. 23C . It is to be noted that the same components as those of light emitting device  100  of Embodiment 1 illustrated in  FIGS. 4 to 7B  and light emitting device  300  of Embodiment 2 illustrated in  FIGS. 18 to 21  are denoted by the same reference numerals and the descriptions thereof are omitted. 
     As illustrated in  FIGS. 22 to 25 , light emitting device  400  of Embodiment 3 includes light emitting element  110  and light flux controlling member  410 . Light flux controlling member  410  is disposed in such a manner that central axis CA thereof matches the optical axis of light emitting element  110 . As in Embodiments 1 and 2, the following descriptions will be made on the assumption that light flux controlling member  410  is disposed in a three-dimensional orthogonal coordinate system. 
     As illustrated in  FIGS. 22 and 25 , light flux controlling member  410  includes incidence surface  121  on which light emitted from light emitting element  110  is incident, total reflection surface  122  that totally reflects part of light incident on incidence surface  121 , and emission surface  411  that emits part of light incident on incidence surface  121  and light reflected by total reflection surface  122 . Light flux controlling member  410  of Embodiment 3 differs from light emitting device  100  of Embodiment 1 and light emitting device  300  of Embodiment 2 in only the form of emission surface  311 . Therefore the form of emission surface  411  will be described with reference to  FIGS. 22 to 25 . 
     In light flux controlling member  410  of Embodiment 3, emission surface  411  includes two emission surfaces (first emission surface  411   a  and second emission surface  411   b ) which have different forms. First emission surface  411   a  has a form (saddle foHn) same as a part of emission surface  311  of light flux controlling member  310  of Embodiment 2. Accordingly, first emission surface  411   a  satisfies the following Expression (1) and Expression (2) as with emission surface  311 .
 
Δ Z   1   &gt;ΔZ   2   (1)
 
Δ Z   2 ≠0  (2)
 
     On the other hand, second emission surface  411   b  is a part of a conical surface formed by rotating the generatrix about central axis CA of light flux controlling member  410  as the rotational axis. 
     As illustrated in  FIG. 22 , in emission surface  414 , second emission surface  411   b  corresponds to a part or all of the region included in the space of y&lt;0 in the three-dimensional orthogonal coordinate system. On the other hand, in emission surface  411 , first emission surface  411   a  corresponds to all the regions included in the space of y≧0 in the three-dimensional orthogonal coordinate system. Accordingly, in emission surface  411 , the site having the maximum y-coordinate value and the site having the maximum x-coordinate value are both located in first emission surface  411   a . As described above, first emission surface  411   a  satisfies Expression (1) and Expression (2), and thus, emission surface  411  in its entirety satisfies Expression (1) and Expression (2). 
     It is to be noted that, in a plan view of light flux controlling member  410 , angle θ, relative to central axis CA of light flux controlling member  410 , in which second emission surface  411   b  is defined (see  FIG. 24A ) is not specifically limited as long as angle θ falls within the range 0°&lt;θ&lt;180°. In the example illustrated in  FIG. 24A , angle θ is θ≈180° (θ&lt;180°), but angle θ may be, for example, θ=90°. 
     [Effect] 
     In light flux controlling member  410  of Embodiment 3, first emission surface  411   a  expands light in the x-axis direction and the y-axis direction, and second emission surface  411   b  collects light. Thus, light flux controlling member  410  of Embodiment 3 can adjust the balance between wide distribution of light and light collection by adjusting the ratio of second emission surface  411   b  in emission surface  411 . Thus, a lighting apparatus having light flux controlling member  410  can make the illuminance distribution on the illuminated surface more uniform. 
     This application is entitled to and claims the benefit of Japanese Patent Application No. 2011-237174 filed on Oct. 28, 2011, and Japanese Patent Application No. 2012-063533 filed on Mar. 21, 2012, the disclosure each of which including the specification, drawings and abstract is incorporated herein by reference in its entirety. 
     INDUSTRIAL APPLICABILITY 
     The light emitting device and lighting apparatus according to the embodiments of the present invention are applicable to internal illumination signboards, externally illuminating signboards, and indirect lighting apparatuses, for example. 
     REFERENCE SIGNS LIST 
     
         
           10  Illumination Surface 
           20  Light emitting device 
           30  Base plate 
           40  Bright site 
           50  Shining site 
           100 ,  300 ,  400  Light emitting device 
           110  Light emitting element 
           120 ,  310 ,  410  Light flux controlling member 
           121  Incidence surface 
           121   a  Internal top surface 
           121   b  Internal surface 
           122  Total reflection surface 
           123 ,  311 ,  411  Emission surface 
           124  Recess 
           200  Lighting apparatus 
           210  Base plate 
           220 ,  220   a ,  220   b  Illumination surface 
           230  Top plate 
           240  Reflecting surface 
           411   a  First emission surface 
           411   b  Second emission surface 
         CA Central axis