Luminous flux control member, light emitting apparatus, and illuminating apparatus

A luminous flux control member (200) of the present invention has: a light input surface (210); total reflection surfaces (220), which are formed at positions facing a light emitting element with the light input surface (210) therebetween; two light guide sections (230), which are formed such that respective cross-sectional areas thereof are reduced in the direction to be away from the light input surface (210) and the total reflection surface (220), said light guide sections being formed at facing positions with the light input surface (210) and the total reflection surface (220) therebetween; and two light output surfaces (240), which are formed on the outer surfaces of the two light guide sections (230), respectively.

TECHNICAL FIELD

The present invention relates to a light flux controlling member that controls the travelling direction of light emitted from a light emitting element, a light-emitting device including the light flux controlling member, and an illumination apparatus including the light-emitting device.

BACKGROUND ART

In recent years, in view of energy saving and environmental conservation, illumination apparatus (such as LED bulbs and LED fluorescent tubes) using a light-emitting diode (hereinafter also referred to as “LED”) as a light source have been increasingly replacing electric light bulbs and fluorescent tubes. In generally used LED fluorescent tubes, a plurality of LEDs are disposed on a substrate at a predetermined interval, and a cover is disposed so as to cover the LEDs (see, for example, PTL 1).

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

However, the conventional LED fluorescent tubes have a problem that bright spots corresponding to LEDs are seen through the cover, and the luminance unevenness is significant. It is conceivable to increase the number of LEDs or reduce the light transmittance of the cover in order to make the bright spots less noticeable; however, such solutions to the problem are not preferable in view of energy saving.

An object of the present invention is to provide a light flux controlling member that can control the distribution of light emitted from light emitting elements such that, when the light is applied to an illumination apparatus (for example, an LED fluorescent tube) having light emitting elements and a cover, the cover can be uniformly irradiated with light from a small number of light emitting elements.

In addition, another object of the present invention is to provide a light-emitting device including the light flux controlling member, and an illumination apparatus including the light-emitting device.

Solution to Problem

A light flux controlling member of an embodiment of the present invention is configured to control a distribution of light emitted from a light emitting element, and the light flux controlling member includes: an incidence surface on which at least part of light emitted from a light emitting element is incident; a total reflection surface formed at a position facing the light emitting element with the incidence surface therebetween, the total reflection surface being configured to reflect part of light incident on the incidence surface in two opposite directions substantially perpendicular to an optical axis of the light emitting element; two light guiding sections formed at positions facing each other with the incidence surface and the total reflection surface therebetween, the two light guiding sections being configured to guide part of light incident on the incidence surface and light reflected by the total reflection surface in a direction away from the incidence surface and the total reflection surface; and two emission surfaces formed on respective external surfaces of the two light guiding sections, the two emission surfaces being configured to output light guided by the light guiding sections.

A light-emitting device of an embodiment of the present invention includes: the light flux controlling member of the embodiment of the present invention; and a light emitting element disposed at a position facing the incidence surface.

An illumination apparatus of an embodiment of the present invention includes: the light-emitting device of the embodiment of the present invention; and a cover that is disposed in such a manner as to cover the light-emitting device with an air layer interposed between the light-emitting device and the cover.

Advantageous Effects of Invention

According to the present invention, an illumination apparatus (for example, an LED fluorescent tube) with high energy efficiency and small luminance unevenness can be provided.

DESCRIPTION OF EMBODIMENTS

In the following, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following description explains an illumination apparatus which can be used in place of fluorescent tubes, as a typical example of the illumination apparatus of the embodiments of the present invention.

FIGS. 1A to 2Cillustrate a configuration of illumination apparatus100of Embodiment 1 of the present invention.FIG. 1Ais a plan view of illumination apparatus100,FIG. 1Bis a front view of illumination apparatus100, andFIG. 1Cis a side view of illumination apparatus100.FIG. 2Ais a sectional view taken along line A-A ofFIG. 1A,FIG. 2Bis a sectional view taken along line B-B ofFIG. 2A, andFIG. 2Cis a partially enlarged sectional view of a region surrounded by a broken line inFIG. 2A.

As illustrated inFIGS. 1A to 2C, illumination apparatus100includes frame (housing)110, substrate120, a plurality of light emitting elements130, a plurality of light flux controlling members200and cover140. A pair of light emitting element130and light flux controlling member200functions as a light-emitting device. In the example illustrated inFIGS. 1A to 2C, illumination apparatus100includes three light-emitting devices.

Light emitting elements130are a light source of illumination apparatus100, which are disposed in a line on substrate120attached on frame110(seeFIG. 2C). In the example illustrated inFIG. 2A, three light emitting elements130are disposed in a line on substrate120. Each light emitting element130is disposed at a position that faces incidence surface210(described later) of light flux controlling member200. Light emitting element130is, for example, a light-emitting diode (LED) such as a white light-emitting diode. Frame110and substrate120are made of, for example, a metal having a high thermal conductivity such as aluminum and copper. When substrate120is not need to have high thermal conductivity, substrate120may be composed of a resin substrate having glass nonwoven fabric impregnated with epoxy resin.

Light flux controlling members200are disposed in a line on substrate120such that light flux controlling members200are paired with respective light emitting elements130(seeFIG. 2A). Light flux controlling member200controls the distribution of light emitted from light emitting element130. Light flux controlling member200is formed by integral molding. The material of light flux controlling member200is not particularly limited as long as light having a desired wavelength can pass therethrough. Examples of the material of light flux controlling member200include: light transmissive resins such as polymethylmethacrylate (PMMA), polycarbonate (PC), and epoxy resin (EP); or light transmissive glass. In addition, a light diffusing member such as beads may be dispersed in light flux controlling member200.

Illumination apparatus100of the present invention has the main feature in the form of light flux controlling member200. Therefore, the form of light flux controlling member200will be described in detail separately.

By cover140, the light emitted from light flux controlling member200is transmitted to the outside while being diffused. Cover140is disposed in such a manner as to cover all light-emitting devices (light emitting element130and light flux controlling member200) with an air layer interposed between each light-emitting device and cover140. The external surface of cover140serves as an effective light emission region.

The shape of cover140is not particularly limited as long as it can cover the light-emitting devices, with the air layer interposed between each light-emitting device and the cover140. While cover140has a cylindrical form that is partially cut out in the example illustrated inFIG. 2B, cover140may have a cylindrical form.

The material of cover140is not particularly limited as long as the material has light transmissivity. Examples of the material of cover140include light transmissive resins such as polymethylmethacrylate (PMMA), polycarbonate (PC), polystyrene (PS), and styrene methyl methacrylate copolymerization resin (MS), and light transmissive glasses. In addition, the method for providing cover140with a light diffusing function is not particularly limited. For example, a light diffusing treatment (for example, roughening treatment) may be performed on the internal surface or external surface of cover140, or a diffusing member such as beads may be dispersed in the light transmissive resins.

(Form of Light Flux Controlling Member)

FIGS. 3A to 3Gillustrate a configuration of light flux controlling member200of Embodiment 1 of the present invention.FIG. 3Ais a front view of light flux controlling member200,FIG. 3Bis a plan view of light flux controlling member200,FIG. 3Cis a bottom view of light flux controlling member200,FIG. 3Dis a side view of light flux controlling member200,FIG. 3Eis a sectional view taken along line C-C ofFIG. 3B,FIG. 3Fis a sectional view taken along line D-D ofFIG. 3B, andFIG. 3Gis a sectional view taken along line E-E ofFIG. 3B.

As illustrated inFIGS. 3A to 3G, light flux controlling member200includes: incidence surface210on which light emitted from light emitting element130is incident; total reflection surface220configured to reflect part of light incident on incidence surface210in a predetermined direction; two light guiding sections230configured to guide the part of light incident on incidence surface210and light reflected by total reflection surface220; and two emission surfaces240configured to output light that travels in light guiding section230and is incident on the inside at an angle not larger than a critical angle.

On incidence surface210, light emitted from light emitting element130is incident. Light emitting element130is a dot light source such as an LED. Incidence surface210is an internal surface of recess250that is formed at a center portion of the bottom surface (the surface located on light emitting element130side) of light flux controlling member200. In the example illustrated inFIGS. 3A to 3G, recess250has a hemispherical form or a hemiellipsoidal form, and incidence surface210is composed of an edgeless curved surface. While the form of incidence surface210is not particularly limited, an edgeless curved surface is preferable as described later with reference toFIGS. 5A to 6B.

Total reflection surface220is formed at a position that faces light emitting element130with incidence surface210therebetween, and is formed plane-symmetrically about a virtual plane which is perpendicular to substrate120and includes optical axis LA (seeFIG. 2C) of the light emitting element. Total reflection surface220reflects part of light incident on incidence surface210in opposite two directions (the directions of two light guiding sections230) which are substantially perpendicular to optical axis LA of the light emitting element and the virtual plane. That is, total reflection surface220reflects light that reaches total reflection surface220toward two light guiding sections230. It is to be noted that, as used herein, “optical axis of light emitting element” is the travelling direction of light at the center of a stereoscopic light flux from the light emitting element. In addition, total reflection surface220is designed for light emitted from a center portion on the light emitting surface of light emitting element130.

With reference toFIGS. 4A to 4E, the form of total reflection surface220will be described.FIG. 4AandFIG. 4Billustrate a configuration of light flux controlling member10that includes a light emitting element as a light source and is used for a spotlight.FIG. 4Ais a perspective view of light flux controlling member10, andFIG. 4Bis a sectional view of light flux controlling member10. As illustrated inFIG. 4AandFIG. 4B, light flux controlling member10includes: incidence surface12on which light emitted from light emitting element is incident; total reflection surface14that totally reflects part of light incident on incidence surface12; and emission surface16from which light part of light incident on incidence surface12and light reflected by total reflection surface14are emitted. Incidence surface12is an internal surface of a truncated cone shaped recess that is formed at a bottom of light flux controlling member10. Total reflection surface14is a surface extending from the outer edge of the bottom of light flux controlling member10to the outer edge of emission surface16, and is a rotationally symmetrical surface formed in such a manner as to surround the central axis of light flux controlling member10. The diameter of total reflection surface14gradually increases from incidence surface12side (bottom side) toward emission surface16side. The generatrix of total reflection surface14is an arc-like curve protruding outward. Emission surface16is a planar surface located at a position opposite to incidence surface12(bottom) in light flux controlling member10.

FIG. 4Cillustrates light paths in the case where light flux controlling member10is used. As illustrated inFIG. 4C, light emitted from a dot light source disposed at a predetermined position enters light flux controlling member10from incidence surface12. Part of light having entered light flux controlling member10is output from emission surface16without being reflected by total reflection surface14. The remaining part of the light having entered light flux controlling member10is reflected by total reflection surface14toward emission surface16, and output from emission surface16. In this manner, the distribution of light emitted from the dot light source is controlled and the light is output from emission surface16.

When light flux controlling member10is divided into two parts along line F-F ofFIG. 4Band the bottoms of the two parts are connected, light flux controlling member10′ illustrated inFIG. 4Dis obtained. As illustrated inFIG. 4E, in light flux controlling member10′ thus obtained, light emitted from the dot light source is reflected by two total reflection surfaces14and becomes two beams of light travelling in opposite directions. The form of total reflection surface220of light flux controlling member200of the present embodiment is basically the same as the form of total reflection surface14of light flux controlling member10′ illustrated inFIG. 4D. In the following description, the portion denoted by the reference sign “18” in the proximity of the boundary line of two total reflection surfaces14inFIG. 4DandFIG. 4Eis sometimes referred to as “connecting section of total reflection surface.”

Two light guiding sections230are rod-like members formed (plane-symmetrically about the virtual plane which includes optical axis LA of the light emitting element and is perpendicular to substrate120) at opposing positions with incidence surface210and total reflection surface220therebetween. Two light guiding sections230are each connected to emission surface16of light flux controlling member10′ illustrated inFIG. 4D. Light guiding section230guide part of light incident on incidence surface210and light reflected by total reflection surface220in the direction away from incidence surface210and total reflection surface220, while outputting the part of light incident on incidence surface210and the light reflected by total reflection surface220little by little. Thus, the external surface of light guiding section230functions as emission surface240that outputs light guided by light guiding section230.

Light guiding section230totally reflects the incident light on the surface of light guiding section230, thereby guiding the incident light in a direction away from incidence surface210and total reflection surface220. Meanwhile, light guiding section230outputs the incident light from the surface of light guiding section230(emission surface240). In order to achieve both the guiding and outputting, light guiding section230is so formed that its cross-sectional area decreases as the distance from incidence surface210and total reflection surface220increases. While the cross-sectional area of light guiding section230is controlled by adjusting both the thickness and width in the example illustrated inFIGS. 3A to 3G, the cross-sectional area of light guiding section230may be controlled by adjusting either of the thickness or width. The cross-sectional form of light guiding section230in the minor axis direction is not particularly limited, and may be appropriately selected in accordance with the desired light distribution. In the example illustrated inFIGS. 3A to 3G, the cross-sectional form of light guiding section230in the minor axis direction is a semicircular form. In light flux controlling member200of Embodiment 1, the entirety of light guiding section230is formed as a cross-sectional area changing section.

In view of uniformizing the amount of light emitted from emission surface240, a diffusing member such as beads is preferably dispersed in light guiding section230. In addition, a light diffusing treatment (for example, roughening process) may be performed on emission surface240.

FIGS. 5A to 6Bare schematic views illustrating light paths in light flux controlling member200in the region illustrated inFIG. 2C.FIGS. 5A and 5Billustrate light paths in the case where incidence surface210includes an edge (when recess250has a form which is obtained by connecting two half truncated cones; seeFIG. 4D), andFIGS. 6A and 6Billustrate light paths in the case where incidence surface210has no edge (when recess250has a substantially hemispherical form). In addition, while connecting section222of the total reflection surface is not chamfered in light flux controlling member200illustrated inFIGS. 5A and 5B, connecting section222of the total reflection surface is chamfered into a round form in light flux controlling member200illustrated inFIGS. 6A and 6B. It is to be noted thatFIG. 5AandFIG. 6Aare front views, andFIG. 5BandFIG. 6Bare bottom views. InFIGS. 5A to 6B, light flux controlling member200produced by using a light transmissive resin containing no diffusing member is simulated.

As illustrated inFIGS. 5A to 6B, light emitted from light emitting element130enters light flux controlling member200from incidence surface210. Part of light having entered light flux controlling member200(light emitted at a large angle with respect to optical axis LA of light emitting element130) directly reaches light guiding section230without being reflected by total reflection surface220. On the other hand, part of light having entered light flux controlling member200(light emitted at a small angle with respect to optical axis LA of light emitting element130) is reflected by total reflection surface220toward light guiding section230. As a result, upward light (in the direction of optical axis LA of light emitting element130) emitted from light emitting element130becomes light directed in the lateral direction (in substantially the vertical direction with respect to optical axis LA of light emitting element130), and is incident on either of two light guiding sections230. Light incident on light guiding section230is guided toward the end portion of light guiding section230while being output little by little from emission surface240. As a result, light is substantially uniformly output from the entirety of the external surface of light guiding section230(the entirety of emission surface240). Light emitted from emission surface240of light flux controlling member200is transmitted through the air layer and reaches the internal surface of cover140. The light having reached the internal surface of cover140is transmitted through cover140while being diffused. As a result, the light is substantially uniformly emitted from the entirety of the exterior surface of cover140. In this manner, light emitted from light emitting element130that is a dot light source can be converted to linear light by light flux controlling member200.

As illustrated inFIGS. 5A and 5B, when incidence surface210includes an edge and connecting section222of the total reflection surface is not chamfered, most of the light having entered from incidence surface210and reached total reflection surface220is reflected toward light guiding section230. Therefore, when light flux controlling member200illustrated inFIGS. 5A and 5Bis used, the region around total reflection surface220may be darkened. On the other hand, when incidence surface210has no edge and connecting section222of the total reflection surface is chamfered as illustrated in6A and6B, part of light having entered from incidence surface210and reached total reflection surface220is not reflected by total reflection surface220, and is output from total reflection surface220. Therefore, in order to prevent the region around total reflection surface220from being darkened, the form of incidence surface210is preferably an edgeless form, and connecting section222of the total reflection surface is preferably chamfered.

(Simulation of Illuminance Distribution of Illumination Apparatus)

Three light emitting elements130(white LEDs) are disposed on substrate120in a line with a center-to-center distance of 100 mm therebetween, and light flux controlling member200having a length of 100 mm is disposed on each light emitting element130.

Three light flux controlling members200are disposed such that their major axes are aligned along one line. The total length of illumination apparatus100is 330 mm, and the outer diameter of cover140is 26 mm.

FIG. 7is a graph illustrating results of a simulation of the illuminance distribution in the case where illumination apparatus100is observed from the front (observed as inFIG. 1B). The abscissa represents the position of illumination apparatus100in the major axis direction (D; mm), and the center point where light emitting element130is disposed is “0.” The ordinate represents the illuminance (I; lux) at each point on the external surface (exterior surface) of cover140. That is,FIG. 7illustrates the brightness distribution of illumination apparatus100itself. The arrows represent the positions of light emitting elements130.

As illustrated inFIG. 7, although only three light emitting elements130are provided in illumination apparatus100of Embodiment 1, the luminance unevenness was small. These results indicate that light flux controlling member200of Embodiment 1 can appropriately control the distribution of light emitted from light emitting element130.

Illumination apparatus100of Embodiment 1 can substantially uniformly irradiate cover140with light with a small number of light emitting elements130, and therefore can achieve high energy efficiency and small luminance unevenness.

FIGS. 8A to 8Care partial sectional views illustrating a configuration of illumination apparatus300of Embodiment 2 of the present invention.FIG. 8Ais a plan view of illumination apparatus300in which a part of cover140is removed,FIG. 8Bis a front view of illumination apparatus300in which a part of cover140is removed so that the inside thereof can be observed, andFIG. 8Cis an enlarged view of a region surrounded by a broken line inFIG. 8B.

As illustrated inFIGS. 8A to 8C, illumination apparatus300includes frame110, substrate120, a plurality of light emitting elements130, a plurality of light flux controlling members400and cover140. A pair of light emitting element130and light flux controlling member400functions as a light-emitting device. Illumination apparatus300of Embodiment 2 is different from illumination apparatus100of Embodiment 1 in the form of light flux controlling member400. Here, the same components as those of illumination apparatus100of Embodiment 1 are denoted by the same reference numerals, and the descriptions thereof are omitted.

(Form of Light Flux Controlling Member)

FIGS. 9A to 9Gillustrate a configuration of light flux controlling member400of Embodiment 2 of the present invention.FIG. 9Ais a front view of light flux controlling member400,FIG. 9Bis a plan view of light flux controlling member400,FIG. 9Cis a bottom view of light flux controlling member400,FIG. 9Dis a side view of light flux controlling member400,FIG. 9Eis a sectional view taken along line G-G ofFIG. 9B,FIG. 9Fis a sectional view taken along line H-H ofFIG. 9B, andFIG. 9Gis a sectional view taken along line I-I ofFIG. 9B.

Light flux controlling member400of Embodiment 2 has a form which is obtained by cutting out a part of the side surface around the center portion of light flux controlling member200of Embodiment 1. Thus, light flux controlling member400of Embodiment2includes additional emission surface410at a location around the center portion of the side surface. In addition, light flux controlling member400of Embodiment 2 includes additional emission surface420having a substantially cylindrical form at a center portion on a lower side of the side surface. Therefore, in light flux controlling member400of Embodiment 2, the area of total reflection surface220is small in comparison with light flux controlling member200of Embodiment 1.

By additional emission surfaces410and420, part of light incident on incidence surface210is output from the region around total reflection surface220. Thus, in light flux controlling member400of Embodiment 2, the amount of light output from the region around total reflection surface220is large in comparison with light flux controlling member200of Embodiment 1.

In addition, light flux controlling member400of Embodiment 2 includes two legs430for fixing light flux controlling member400to substrate120, and two reinforcement plates440for increasing the strength of light flux controlling member400.

FIGS. 10A and 10Bare schematic views illustrating light paths in light flux controlling member400in the region illustrated inFIG. 8C.FIG. 10Ais a front view, andFIG. 10Bis a bottom view.

As illustrated inFIGS. 10A and 10B, light emitted from light emitting element130enters light flux controlling member400from incidence surface210. Part of light having entered light flux controlling member400(light emitted at a large angle with respect to optical axis LA of light emitting element130) directly reaches light guiding section230without being reflected by total reflection surface220, or is output from emission surfaces410and420as it is. On the other hand, part of light having entered light flux controlling member400(light emitted at a small angle with respect to optical axis LA of light emitting element130) is reflected by total reflection surface220toward light guiding section230. Light having entered guiding section230is output from emission surface410as it is, or guided toward the end portion of light guiding section230while being output from emission surface240little by little. As a result, the light is substantially uniformly emitted from the entirety of the exterior surface (emission surfaces240and410) of light guiding section230. Light emitted from emission surface240of light flux controlling member200is transmitted through the air layer and reaches the internal surface of cover140. The light having reached the internal surface of cover140is transmitted through cover140while being diffused. As a result, the light is substantially uniformly emitted from the entirety of the exterior surface of cover140.

As illustrated inFIGS. 10A and 10B, in light flux controlling member400of Embodiment 2, part of light incident on incidence surface210does not reach total reflection surface220and is not guided in light guiding section230, but is output from emission surfaces410and420located in the vicinity of total reflection surface220. Thus, in light flux controlling member400of Embodiment 2, the amount of light emitted from the region around total reflection surface220is great in comparison with light flux controlling member200of Embodiment 1.

(Simulation of Illuminance Distribution of Illumination Apparatus)

The illuminance distribution of illumination apparatus300of Embodiment 2 illustrated inFIGS. 8A to 8Cwas simulated.FIG. 11is a graph illustrating results of a simulation of the illuminance distribution in the case where illumination apparatus300is observed from the front (observed as inFIG. 8B). The abscissa represents the position of illumination apparatus300in the major axis direction (D; mm), and the center point where light emitting element130is disposed is “0.” The ordinate represents the illuminance (I; lux) at each point on the external surface (exterior surface) of cover140.

As illustrated by arrows inFIG. 7, in illumination apparatus100of Embodiment 1, slight decrease in illuminance was caused at the positions of light emitting elements130. This is because almost no light is emitted from the region around total reflection surface220. In contrast, since light is emitted also from the region around total reflection surface220in illumination apparatus300of Embodiment 2, the amount of decrease in illuminance was only small even at the positions of light emitting elements130as illustrated inFIG. 11.

In addition to the effect of illumination apparatus100of Embodiment 1, illumination apparatus300of Embodiment 2 has an effect in which luminance unevenness in the effective light emission region can be limited, since the amount of light emitted from the region around total reflection surface220is great.

FIGS. 12A to 13Eillustrate a configuration of illumination apparatus500and light flux controlling member600of Embodiment 3.FIG. 12Ais a front view of illumination apparatus500in which a part of cover140is removed so that the inside thereof can be observed,FIG. 12Bis a front view of light flux controlling member600,FIG. 12Cis a plan view of light flux controlling member600,FIG. 12Dis a bottom view of light flux controlling member600, andFIG. 12Eis a sectional view taken along line J-J ofFIG. 12C.FIG. 13Ais a left side view of light flux controlling member600,FIG. 13Bis a right side view of light flux controlling member600,FIG. 13Cis a sectional view taken along line K-K ofFIG. 12C,FIG. 13Dis a sectional view taken along line L-L ofFIG. 12C, andFIG. 13Eis a sectional view taken along line M-M ofFIG. 12C.

As illustrated inFIG. 12A, illumination apparatus500includes frame110, substrate120, a plurality of light emitting elements130, a plurality of light flux controlling members600and cover140. A pair of light emitting element130and light flux controlling member600functions as a light-emitting device. Illumination apparatus500of Embodiment 3 is different from illumination apparatus100of Embodiment 1 in the form of light flux controlling member600. Here, the same components as those of illumination apparatus100of Embodiment 1 are denoted by the same reference numerals, and the descriptions thereof are omitted.

(Form of Light Flux Controlling Member)

As illustrated inFIGS. 12B to 13E, light guiding section630of light flux controlling member600of Embodiment 3 includes a region which is formed at a portion distant from light emitting element130(incidence surface210) and whose cross-sectional area does not change, and a cross-sectional area changing section which is formed on the side nearer to light emitting element130(incidence surface210) and whose cross-sectional area changes. The height of light guiding section630from substrate120is the same between the portion on the light emitting element130side and the portion distant from the light emitting element. In addition, light flux controlling member600includes a pair of positioning protrusions620and a pair of reinforcement members640.

Positioning protrusion620sets the position of light flux controlling member600with respect to substrate120. Positioning protrusion620is formed in a substantially cylindrical form. Positioning protrusion620is disposed on the rear surface of light guiding section630.

Reinforcement member640increases the strength of light flux controlling member600. The position and form of reinforcement member640are not particularly limited as long as the function of total reflection surface220of light flux controlling member600is not significantly blocked and the strength of light flux controlling member600can be increased. In the present embodiment, reinforcement member640is disposed on the bottom surface of light flux controlling member600(surface on light emitting element130side), thus joining the end surfaces of light guiding section630.

In addition, although not illustrated in the drawings, also in light flux controlling member600of Embodiment 3, light emitted from light emitting element130is controlled as with the case where light flux controlling member200of Embodiment 1 is used. It is to be noted that the light component which is output while being not totally reflected by total reflection surface220increases as the size of the light emitting surface of light emitting element130increases. In such a case, even in a state where incidence surface210includes an edge and the entirety of incidence surface210is not composed of a curved surface as in the case of light flux controlling member600, light output from total reflection surface220is generated. Therefore, it is only necessary to determine whether to provide an edge such that a bright-dark point with strong contrast which degrades the light emission quality is not caused on cover140of illumination apparatus500, in consideration of the balance between totally reflected light and output light.

Illumination apparatus500of Embodiment 3 has the same effect as that of illumination apparatus100of Embodiment 1.

FIGS. 14A to 15Dillustrate configurations of illumination apparatus700, light flux controlling member800and diffusing member820of Embodiment 4.FIG. 14Ais a front view of illumination apparatus700in which a part of cover140is removed so that the inside thereof can be observed,FIG. 14Bis a front view of light flux controlling member800,FIG. 14Cis a plan view of light flux controlling member800, andFIG. 14Dis a sectional view taken along line N-N ofFIG. 14C.FIG. 15Ais a front view of diffusing member820,FIG. 15Bis a plan view of diffusing member820,FIG. 15Cis a bottom view of diffusing member820, andFIG. 15Dis a side view of diffusing member820.

As illustrated inFIG. 14A, illumination apparatus700includes frame110, substrate120, a plurality of light emitting elements130, a plurality of light flux controlling members800and cover140. A pair of light emitting element130and light flux controlling member800functions as a light-emitting device. Illumination apparatus700of Embodiment 4 is different from illumination apparatus700of Embodiment 3 in the configuration of light flux controlling member800. Here, the same components as those of illumination apparatus700of Embodiment 3 are denoted by the same reference numerals, and the descriptions thereof are omitted.

(Form of Light Flux Controlling Member)

As illustrated inFIGS. 14B to 15D, light flux controlling member800of Embodiment 4 includes diffusing member820in addition to light flux controlling member600(light flux controlling member main body) of Embodiment 3.

As described above, total reflection surface220reflects part of light incident on incidence surface210in directions in which two light guiding sections630extend. In addition, total reflection surface220is designed for light emitted from a center portion of the light emitting surface of light emitting element130. Therefore, part of light emitted from portions other than the center portion of the light emitting surface of light emitting element130(for example, outer periphery portions of the light emitting surface) may be output from total reflection surface220without being reflected by total reflection surface220. The light emitted from total reflection surface220results in a bright point formed in a region immediately above total reflection surface220(light emitting element130). Consequently, luminance unevenness may be caused in illumination apparatus700. Diffusing member820limits the formation of a bright point at a portion immediately above total reflection surface220by diffusing (reflecting or refractively transmitting) the light undesirably output from total reflection surface220.

As illustrated inFIGS. 15A to 15D, diffusing member820is fainted in a substantially half cylindrical form, and includes a plurality of prism rows822. As used herein, the substantially half cylindrical form may include a half cylinder form, and may have a side wall coupled to a side edge of the half cylinder. That is, diffusing member820has a temple-bell-like form (inverted U-form) as viewed in cross-section taken along a direction orthogonal to the axis direction. The axis of diffusing member820is, for example, the axis line of the half cylinder portion. Diffusing member820may have a half cylindrical form, for example. Diffusing member820is disposed in the vicinity of a region immediately above total reflection surface220. It is to be noted that the position where diffusing member820is disposed will be described later.

Prism rows822are disposed on the internal surface of diffusing member820, along a direction orthogonal to the axis direction of diffusing member820. That is, prism rows822are disposed on the internal surface of the half cylinder portion in a semicircular form, and are linearly disposed on the internal surface of the side wall. The cross-sectional form of each prism row822is a triangular shape. Each prism row822includes first plane824and second plane826. First plane824and second plane826are alternately and continuously disposed.

Prism rows822may have the same form, or different forms. In diffusing member820illustrated inFIGS. 15A to 15D, prism rows822have the same form. The inclination angles of first inclined surface824and second inclined surface826with respect to optical axis LA are not particularly limited as long as a bright point can be prevented from being formed in the region immediately above total reflection surface220(light emitting element130).

FIGS. 16A to 16Care views for describing the position where diffusing member820is disposed.FIG. 16Aillustrates an emission range (θ1) of light emitted from one end portion of the light emitting surface of light emitting element130and transmitted through total reflection surface220in a cross-section of light flux controlling member in the major axis direction including optical axis,FIG. 16Billustrates an emission range (θ2) of light emitted from total reflection surface220, andFIG. 16Cillustrates an emission range (θ3) of light controlled by diffusing member820.FIG. 17is a sectional view illustrating light paths in the case where light flux controlling member800is used.

As described above, since total reflection surface220of light flux controlling member800is designed for light emitted from the center portion of the light emitting surface of light emitting element130, most of the light emitted from center portion of the light emitting surface of light emitting element130is reflected by total reflection surface220toward light guiding section630. On the other hand, light emitted from portion other than the center portion of the light emitting surface is not reflected by light total reflection surface220, and may possibly be transmitted therethrough. Therefore, in a cross-section including optical axis LA and taken along the major axis of light flux controlling member800, light paths of light emitted from an end portion of light emitting surface of light emitting element130were simulated. As a result, as illustrated inFIG. 16A, it was confirmed that, of the light emitted from an end portion of the light emitting surface of light emitting element130, light having angles in a certain range is transmitted through total reflection surface220.

As illustrated inFIG. 16AandFIG. 17, it was confirmed that, of light emitted from an end portion of light emitting surface of light emitting element130, light that passes an end portion of the light emitting surface, and is output at angle (θ1) of 5 to 15 degrees with respect to line LA′ in parallel with optical axis LA toward the center of the light emitting surface is transmitted without being reflected by total reflection surface220, in the cross-section taken along the major axis and including the optical axis of flux controlling member800. Also in light emitted from light emission points other than the center portion and the end portion of the light emitting surface, there is an angle range in which light is transmitted through total reflection surface220without being reflected by total reflection surface220.

A simulation was performed on the distribution of light emitted from total reflection surface220, with light that is not reflected by total reflection surface220and is transmitted therethrough in a case where light emitted from the entirety of the light emitting surface of light emitting element130was caused to incident on light flux controlling member800. In this case, emission surface240of light flux controlling member800was shielded from light, and only light emitted from total reflection surface220was used for the simulation.

As a result, as illustrated inFIG. 16BandFIG. 17, in a cross-section including the optical axis and taken along the major axis of light flux controlling member800, light L1emitted from total reflection surface220has its brightness peak at an angle of about 35 degrees in both the left and right sides when optical axis LA is set at 0 degree.

Given the above, when the above-described diffusing member820is disposed in a region immediately above light emitting element130in such a manner as to cover light at least in a range up to 35 degrees with respect to optical axis LA, the travelling direction of light emitted at the highest luminous intensity in 35-degree direction can be disturbed, and the possibility of formation of a bright point in the region immediately above total reflection surface220can be reduced. It is to be noted that the peak angle changes depending on the size of light emitting element130, the light distribution, and the forms of incidence surface210and total reflection surface220of light flux controlling member800. Therefore, it is only necessary to confirm the peak angle by a simulation or measurement, and to determine the cover range of diffusing member820such that light in the confirmed direction is emitted through diffusing member820.

Next, a simulation was performed on light paths of light in a case where diffusing member820is disposed in a region immediately above total reflection surface220in such a manner as to cover at least a range up to 35 degrees with respect to optical axis LA. It is to be noted that, since light travelled to light guiding section630is shielded, light output from light guiding section630was not taken into consideration.

As illustrated inFIG. 16CandFIG. 17, in the cross-section taken along the major axis of light flux controlling member800and including the optical axis, when diffusing member820is disposed in a region immediately above total reflection surface220in such a manner as to cover at least a range up to about 35 degrees with respect to optical axis LA, light emitted from emission surface of diffusing member820has its brightness peak at an angle of about 60 degrees in both the left and right sides when optical axis LA is set at 0 degree.

That is, in the cross-section taken along the major axis of light flux controlling member800and including the optical axis, the peak angle of light emitted from total reflection surface220is expanded by diffusing member820from 35 degrees to 60 degrees when optical axis LA is set at 0 degree. In addition, the distance of light transmitted through diffusing member820from cover140is increased in association with the increase of the peak angle of the light. Thus, a bright point is not easily formed on cover140.

As described, diffusing member820diffuses light emitted from total reflection surface220, thereby eliminating a bright point that may be formed in a region immediately above light emitting element130. However, when the wavelength of light emitted from the light flux controlling member main body (light flux controlling member600of Embodiment 3) including incidence surface210, total reflection surface220, two light guiding sections630and two emission surfaces240, and the wavelength of light emitted from diffusing member820are different from each other, color unevenness is caused in light flux controlling member800. Accordingly, diffusing member820preferably outputs light having a wavelength characteristic which is approximately equal to that of light from the light flux controlling member main body in the visible light region. In view of this, the material of the light flux controlling member main body and the material of diffusing member820preferably have a transmittance difference (ΔT) of 15% or lower for the light having wavelengths of 400 to 800 nm. The transmittance difference (ΔT) is obtained as follows.

(Method for Obtaining Transmittance Difference (ΔT))

Each material in a form of a plate having a thickness of 1 mm is irradiated with light having wavelengths of 400 to 800 nm, which fall within the visible light region, to obtain light transmittances for respective wavelengths. For each material, the minimum value (Tmin) of the transmittances is subtracted from the maximum value (Tmax) of the transmittances to obtain transmittance difference (ΔT).

The material of the light flux controlling member main body and the material of diffusing member820may be the same or different as long as the above-described condition is satisfied. Examples of the material that satisfy the above-described condition of transmittance difference (ΔT) include light transmissive resins such as polymethylmethacrylate (PMMA), polycarbonate (PC), polystyrene (PS), and styrene methyl methacrylate copolymerization resin (MS), and light transmissive glasses. As described, by setting the transmittance difference of the material of the light flux controlling member main body and the material of diffusing member820at 15% or lower, light emitted from the light flux controlling member main body and diffusing member820can be set to have the same color appearance.

As described above, since light flux controlling member800includes diffusing member820in illumination apparatus700of Embodiment 4, formation of a bright point in a region immediately above light emitting element130can be prevented. That is, since light can be uniformly emitted from the entirety of the light emission region of illumination apparatus700, high energy efficiency and small luminance unevenness can be achieved. In addition, when the transmittance difference in the material composing light flux controlling member800is set to 15% or lower, formation of color unevenness can be limited.

FIGS. 18A to 18Dillustrate a configuration of diffusing member820aof a first modification of Embodiment 4.FIG. 18Ais a front view of diffusing member820a,FIG. 18Bis a plan view of diffusing member820a,FIG. 18Cis a bottom view of diffusing member820a, andFIG. 18Dis a side view of diffusing member820a.

As illustrated inFIGS. 18A to 18D, the light flux controlling member of the first modification of Embodiment 4 is different from light flux controlling member800of Embodiment 4 in the form of diffusing member820a. Therefore, the same components as those of light flux controlling member800of Embodiment 4 are denoted by the same reference numerals, and the descriptions thereof are omitted.

Diffusing member820aof the first modification of Embodiment 4 includes a plurality of prism rows822a. Prism rows822aare disposed only on the internal surface of diffusing member820a(substantially half cylinder portion), and each prism row822aincludes first inclined surface824and second inclined surface826. Prism rows822aare disposed in parallel with the axis of diffusing member820a. It is to be noted that prism rows822aare not disposed on the internal surface of the side wall in consideration of the undercut at the time of molding. In addition, the forms of prism rows822aare not the same in consideration of the undercut.

FIGS. 19A to 19Dillustrate a configuration of diffusing member820bof a second modification of Embodiment 4.FIG. 19Ais a front view of diffusing member820b,FIG. 19Bis a plan view of diffusing member820b,FIG. 19Cis a bottom view of diffusing member820b, andFIG. 19Dis a side view of diffusing member820b.

As illustrated inFIGS. 19A to 19D, diffusing member820bof the second modification of Embodiment 4 is different from light flux controlling member800of Embodiment 4 in form of diffusing member820b. Therefore, the same components as those of light flux controlling member800of Embodiment 4 are denoted by the same reference numerals, and the descriptions thereof are omitted.

Diffusing member820bof the second modification of Embodiment 4 includes a plurality of prism rows822b. Prism rows822bare disposed on the outer peripheral surface of diffusing member820b(substantially half cylinder portion), and each prism row822aincludes first inclined surface824and second inclined surface826. Prism rows822bare disposed in parallel with the axis of diffusing member820b.

The illumination apparatuses including the light flux controlling members of the first and second modifications of Embodiment 4 have the same effect as illumination apparatus700of Embodiment 4. Although not illustrated in the drawings, the prism rows may be disposed on the external surface of the diffusing member (substantially cylinder portion) along a direction orthogonal to the axis of the diffusing member.

It is to be noted that, while the diffusing member includes a plurality of prism rows822,822aand822bin Embodiment 4 and the modifications of Embodiment 4, a plurality of square pyramids may be disposed in place of prism rows822,822aand822b.In this case, the square pyramids are disposed on the external surface or internal surface of the diffusing member (substantially cylinder portion). The disposing manner of the square pyramids is not particularly limited. For example, the square pyramids may be disposed such that one side on the bottom surface of the square pyramid is in parallel with the axis of the diffusing member, or one side on the bottom surface of the square pyramid is inclined (at 45 degrees for example) with respect to the axis of the diffusing member.

FIGS. 20A to 21Eillustrate a configuration of illumination apparatus900and light flux controlling member1000of Embodiment 5.FIG. 20Ais a sectional view of illumination apparatus900,FIG. 20Bis a front view of light flux controlling member1000,FIG. 20Cis a plan view of light flux controlling member1000,FIG. 20Dis a bottom view of light flux controlling member1000, andFIG. 20Eis a sectional view taken along line O-O ofFIG. 20C.FIG. 21Ais a left side view of light flux controlling member1000,FIG. 21Bis a right side view of light flux controlling member1000,FIG. 21Cis a sectional view taken along line P-P ofFIG. 20C,FIG. 21Dis a sectional view taken along line Q-Q ofFIG. 20C, andFIG. 21Eis a sectional view taken along line R-R ofFIG. 20C. It is to be noted that diffusing member820is omitted inFIGS. 20B to 20EandFIGS. 21A to 21E.

As illustrated inFIG. 20A, illumination apparatus900includes frame110, substrate120, a plurality of light emitting elements130, a plurality of light flux controlling members1000and cover14. A pair of light emitting element130and light flux controlling member1000functions as a light-emitting device. Illumination apparatus900of Embodiment 5 is different from illumination apparatus700of Embodiment 4 in the form of light flux controlling member1000. Therefore, the same components as those of illumination apparatus700of Embodiment 4 are denoted by the same reference numerals, and the descriptions thereof are omitted.

(Form of Light Flux Controlling Member)

As illustrated inFIGS. 20B to 21E, light flux controlling member1000of Embodiment 5 does not include a step part for attaching diffusing member820. Thus, total reflection surface220and light guiding section1030are smoothly connected.

The cross-sectional form of reinforcement member1040taken along the minor axis of light flux controlling member1000and including optical axis LA is an L shape. In the major axis direction of light flux controlling member1000including optical axis LA, reinforcement member1040is extended to the both side surfaces of a pair of cross-sectional area changing sections that are so formed as to sandwich incidence surface210, and thus reinforcement member1040joins light guiding sections630.

Light flux controlling member1000of Embodiment 5 may also include any of diffusing member820of Embodiment 4 and diffusing members820aand820bof the first and second modifications of Embodiment 4. In addition, the cover ranges of diffusing members820,820aand820bare also as described above.

As described above, since total reflection surface220and light guiding section1030(emission surface240) are smoothly connected with each other in illumination apparatus900of Embodiment 5, the size of total reflection surface220can be increased, and discontinuity of brightness in association with the step part can be eliminated. In addition, since reinforcement member1040is extended to the side surfaces of light guiding section1030, the strength can further be increased.

It is to be noted that light guiding section230,630or1030may be divided in a plane including connecting section222of the total reflection surface. In this case, light guiding sections230,630or1030are preferably connected together by a reinforcement member.

FIGS. 22A to 26illustrate a configuration of illumination apparatus1100, light flux controlling member1200and diffusing member1220of Embodiment 6.FIG. 22Ais a sectional view of illumination apparatus1100as viewed from a front surface,FIG. 22Bis a sectional view taken along line S-S ofFIG. 22A, andFIG. 22Cis a sectional view taken along line T-T ofFIG. 22A.FIG. 23Ais a front view of light flux controlling member1200,FIG. 23Bis a plan view of light flux controlling member1200,FIG. 23Cis a bottom view of light flux controlling member1200, andFIG. 23Dis a sectional view taken along line U-U ofFIG. 23B.FIG. 24Ais a side view of light flux controlling member1200,FIG. 24Bis a sectional view taken along line V-V ofFIG. 23D, andFIG. 24Cis a sectional view taken along line W-W ofFIG. 23D. It is to be noted that, inFIGS. 23A to 24C, diffusing member1220and an engagement hole engaged with auxiliary protrusion1227described later are omitted.FIG. 25Ais a plan view of diffusing member1220,FIG. 25Bis a front view of diffusing member1220,FIG. 25Cis a bottom view of diffusing member1220,FIG. 25Dis a sectional view taken along line X-X ofFIG. 25A,FIG. 25Eis a side view of diffusing member1220,FIG. 25Fis a sectional view taken along line Y-Y ofFIG. 25C, FIG.25G is a sectional view taken along line Z-Z ofFIG. 25C, andFIG. 25His a sectional view taken along line AA-AA ofFIG. 25C.FIG. 26is an enlarged sectional view of a center portion of light flux controlling member1200.

As illustrated inFIGS. 22A to 22C, illumination apparatus1100includes frame110, substrate120, a plurality of light emitting elements130, a plurality of light flux controlling members1200and cover140. A pair of light emitting element130and light flux controlling member1200functions as a light-emitting device. Illumination apparatus1100of Embodiment 6 is different from illumination apparatus1000of Embodiment 5 in the form of light flux controlling member1200. Therefore, the same components as those of illumination apparatus1000of Embodiment 5 are denoted by the same reference numerals, and the descriptions thereof are omitted.

(Form of Light Flux Controlling Member)

As illustrated inFIGS. 22A to 26, light flux controlling member1200of Embodiment 6 includes a light flux controlling member main body and diffusing member1220.

The light flux controlling member main body includes incidence surface210, total reflection surface220, two light guiding sections1230and two emission surfaces240.

On the bottom surfaces of light guiding sections1230(the surface on light emitting element130side with respect to optical axis LA of the light emitting element direction), second recesses1270are respectively formed. Two second recesses1270are each formed in a region around the center portion of light flux controlling member1200, but are not in communication with recess250.

The size and form of second recess1270are not particularly limited as long as the desired light distribution (the light distribution which does not reduce the effect of the present invention) can be obtained and the required strength of light flux controlling member1200can be ensured. In the present embodiment, the form in a plan view of second recess1270is an isosceles triangular form whose bottom side is located on light emitting element130side (seeFIG. 23C). The depth of second recess1270is constant on a side nearer to light emitting element130, but gradually decreases as the distance from light emitting element130increases (seeFIG. 23D). For example, the maximum depth of second recess1270is about 0.5 to 1.5 mm. In the minor axis direction of the light flux controlling member main body, second recess1270has a cross-sectional form in which the bottom portion is in a form of a line and the side portion is in a form of a curve (seeFIG. 24C). That is, in the internal form of second recess1270, the bottom portion is composed of a planar surface and the side portion is composed of a curved surface. It is to be noted that, when light flux controlling member1200is formed by injection molding, second recess1270is preferably formed at a position where a sink mark is possibly formed. With this configuration, formation of a sink mark at the time of injection molding can be limited, and the manufacturing cost can be reduced.

As illustrated inFIGS. 25AtoFIG. 26, diffusing member1220includes a plurality of prism rows1222, a plurality of auxiliary protrusions1227, and a plurality of fixing nails1228. Diffusing member1220of the present embodiment extends in the axis direction of diffusing member1220(major axis direction of the light flux controlling member main body) in comparison with diffusing members820,820aand820bof Embodiment 4 and the modifications of Embodiment 4. At the both end portions of diffusing member1220in the major axis direction, a plurality of auxiliary protrusions1227and a plurality of fixing nails1228are disposed.

Prism rows1222are disposed on a part of the internal surface of diffusing member1220in a direction orthogonal to the axis direction of diffusing member1220. The position where prism rows1222are disposed with respect to the light flux controlling member main body is the same as with prism rows822,822aand822bof Embodiment 4 and modifications of Embodiment 4. Prism rows1222each include first curved surface1223and second curved surface1224. The cross-sectional forms of first curved surface1223and second curved surface1224are each substantially a quadrant (seeFIG. 26). First curved surface1223and second curved surface1224are alternately and continuously disposed.

Auxiliary protrusions1227are engaged with engagement holes not illustrated in the drawings that are disposed on the upper portion of light guiding section1230on the light emitting element130side, and thus auxiliary protrusions1227reinforce, with diffusing member1220, parts where the strength is insufficient in the light flux controlling member main body. Auxiliary protrusions1227are disposed on the light flux controlling member main body side. Auxiliary protrusions1227are disposed at respective positions which are located on the center portion of diffusing member1220in the minor axis direction and are distant from light emitting element130in the major axis direction of diffusing member1220(seeFIG. 25C).

Together with the light flux controlling member main body, fixing nails1228fix diffusing member1220on substrate120. Fixing nails1228are formed at four corners in a plan view of diffusing member1220(seeFIGS. 25A to 25D).

FIG. 27illustrates light paths at a center portion of the light flux controlling member main body. As illustrated inFIG. 27, light emitted at a small angle with respect to optical axis LA of light emitting element130is incident on the light flux controlling member main body from light incidence surface210. Since the light emitted at a small angle with respect to optical axis LA has a high luminous intensity, when total reflection surface220does not function and consequently the light is emitted as it is, a bright point is undesirably formed at a portion immediately above light emitting element130. Since part of light incident on the light flux controlling member main body is reflected by total reflection surface220toward light guiding section1230in the present embodiment, formation of a bright point at a portion in the vicinity of light emitting element130is limited (a dark point is easily formed at a portion in the vicinity of light emitting element130). On the other hand, light emitted at a large angle with respect to optical axis LA is also incident on the light flux controlling member main body from incidence surface210. Part of the light incident on the light flux controlling member main body once passes through the inside of second recess1270(output from the light flux controlling member main body), and is again incident on the light flux controlling member main body. This light is output from emission surface240of light guiding section1230toward cover140. As described, light (represented by a solid line inFIG. 27) that is emitted at a large angle with respect to optical axis LA and refracted by being passed through second recess1270before output from emission surface240is output from a region nearer to optical axis LA with respect to the light guided in the light flux controlling member main body having no second recess1270(represented by a broken line inFIG. 27). Thus, formation of a dark point in a region around light emitting element130can be limited.

As described above, illumination apparatus1100of Embodiment 6 has an effect similar to that of illumination apparatus900of Embodiment 5. In addition, since second recess1270is formed in light guiding section1230in light flux controlling member1200of Embodiment 6, the weight and material cost can be reduced in comparison with light flux controlling member1000of Embodiment 5. In addition, the cross-sectional form of the incidence surface of each prism row1222is rounded, and thus the direction of light emitted toward cover140can be adjusted.

FIGS. 28AtoFIG. 29Dillustrate a configuration of light flux controlling member1400of a first modification of Embodiment 6.FIG. 28Ais a front view of light flux controlling member1400,FIG. 28Bis a plan view of light flux controlling member1400,FIG. 28Cis a bottom view of light flux controlling member1400, andFIG. 28Dis a sectional view taken along line AB-AB ofFIG. 28B.FIG. 29Ais a side view of light flux controlling member1400,FIG. 29Bis a sectional view taken along line AC-AC ofFIG. 28D,FIG. 29Cis a sectional view taken along line AD-AD ofFIG. 28D, andFIG. 29Dis a sectional view taken along line AD-AD ofFIG. 28D. It is to be noted that diffusing member1220is omitted inFIG. 28A to 29D.

As illustrated inFIG. 28A to 29D, light flux controlling member1400of the first modification of Embodiment 6 is different from light flux controlling member1200of Embodiment 6 in the form of second recess1470of the light flux controlling member main body. Therefore, the same components as those of light flux controlling member1200of Embodiment 6 are denoted by the same reference numerals, and the descriptions thereof are omitted.

(Form of Light Flux Controlling Member)

In light flux controlling member1400of the first modification of Embodiment 6, one end portion of second recess1470is located on light emitting element130side, and the other end portion thereof reaches the side surface of light flux controlling member1400in the major axis direction (seeFIG. 28CandFIG. 28D). The depth of second recess1470is small on light emitting element130side (the side nearer to the center of light flux controlling member1400), and is great on the side surface side of light flux controlling member1400(the side nearer to the end portion of light flux controlling member1400). In addition, the depth of second recess1470at the center portion of light guiding section1230is formed such that the depth gradually increases as the distance from light emitting element130increases. In addition, the cross-sectional form of second recess1470at a portion on light emitting element130side in the minor axis direction is a semicircular foam (seeFIG. 29C), and the cross-sectional form of second recess1470at a portion on the side surface side of light flux controlling member1400in the minor axis direction is a temple bell form (seeFIG. 29D).

As described above, an illumination apparatus including light flux controlling member1400of the first modification of Embodiment 6 has an effect similar to that of illumination apparatus1100including light flux controlling member1200of Embodiment 6. In addition, since the size of second recess1470is greater than that of second recess1270of Embodiment 6, the weight can further be reduced.

FIGS. 30A to 31Cillustrate a configuration of light flux controlling member1600of a second modification of Embodiment 6.FIG. 30Ais a front view of light flux controlling member1600,FIG. 30Bis a plan view of light flux controlling member1600,FIG. 30Cis a bottom view of light flux controlling member1600, andFIG. 30Dis a sectional view taken along line AF-AF ofFIG. 30B.FIG. 31Ais a side view of light flux controlling member1600,FIG. 31Bis a sectional view taken along line AG-AG ofFIG. 30D, andFIG. 31Cis a sectional view taken along line AH-AH ofFIG. 30D. It is to be noted that diffusing member1220is omitted inFIGS. 30A to 31C.

As illustrated inFIGS. 30A to 31C, light flux controlling member1600of the second modification of Embodiment 6 is different from light flux controlling member1200of Embodiment 6 in the form of second recess1670. Therefore, the same components as those of light flux controlling member1200of Embodiment 6 are denoted by the same reference numerals, and the descriptions thereof are omitted.

(Form of Light Flux Controlling Member)

One of second recesses1670of the second modification of Embodiment 6 is in communication with the other of second recesses1670at an end portion on light emitting element130side (seeFIG. 30CandFIG. 30D). Therefore, in the present modification, part of incidence surface210on light emitting element130side is cut out by second recess1670.

The depth of second recess1670is constant on a side nearer to light emitting element130, but is gradually reduced as the distance from light emitting element130increases. The cross-sectional form of second recess1670in the minor axis direction of the light flux controlling member main body has a form which is obtained by cutting out part of a circle (seeFIG. 31BandFIG. 31C).

Second recess1670includes on the internal surface thereof second incidence surface1614on which part of light emitted from light emitting element130is incident. That is, part of the internal surface of second recess1670functions as second incidence surface1614. On second incidence surface1614, light emitted at a large angle with respect to optical axis LA is incident. Second incidence surface1614is disposed on the internal surface of second recess1670, on a side nearer to light emitting element130. In addition, second incidence surface1614is disposed in such a manner as to surround incidence surface210, and is connected to the opening edge of incidence surface210.

FIG. 32Aillustrates light paths at a center portion of light flux controlling member1600in which the maximum depth of second recess1670is 1.0 mm.FIG. 32Billustrates light paths at a center portion of light flux controlling member1600′ in which the maximum depth of second recess1670is 2.0 mm.

As illustrated inFIG. 32A, in light flux controlling member1600in which the maximum depth of second recess1670is 1.0 mm, light emitted at a small angle with respect to optical axis LA is incident on light flux controlling member1600from light incidence surface210. Since the light emitted at a small angle with respect to optical axis LA has a high luminous intensity, when total reflection surface220does not function and the light is emitted as it is, a bright point is undesirably formed at a portion immediately above light emitting element130. Since part of light incident on light flux controlling member1600is reflected by total reflection surface220toward light guiding section1230in the present embodiment, formation of a bright point at a portion immediately above light emitting element130is limited (in other words, a dark point may be formed at a portion immediately above light emitting element130). On the other hand, light emitted at a large angle with respect to optical axis LA is incident on light flux controlling member1600from second incidence surface1614. Part of this light is output from a region nearer to optical axis LA with respect to light having entered from incidence surface210. Thus, a dark point that is easily formed at a portion immediately above light emitting element130is limited. On the other hand, as illustrated inFIG. 32B, in light flux controlling member1600′ in which the maximum depth of second recess1670′ is 2.0 mm, the amount of light entering from second incidence surface1614′ is great in comparison with light flux controlling member1600having second recess1670whose maximum depth is 1.0 mm. Consequently, the amount of light output toward a portion immediately above light emitting element130is great, and thus a bright point may be formed at a portion immediately above light emitting element130. Accordingly, it is preferable to appropriately adjust the maximum depth of second recess1670in consideration of the balance between light output from a region around light emitting element130and light travelling in light guiding section1230, in order not to cause luminance unevenness.

As described above, light flux controlling member1600of the second modification of Embodiment 6 has an effect similar to that of light flux controlling member1200of Embodiment 6.

(Simulation of Illuminance Distribution of Illumination Apparatus)

A simulation was performed on an illuminance distribution of an illumination apparatus having a light flux controlling member main body including a second recess. As the light flux controlling member main body, the light flux controlling member main body of Embodiment 6 in which second recesses1270are not in communication with each other, and light flux controlling member main bodies in which second recesses1670are in communication with each other and the maximum depth of second recess1670is 0.5, 1.0, 1.5, or 2.0 mm were used. In addition, for comparison, a simulation was also performed on an illumination apparatus including light flux controlling member1000of Embodiment 5 having no second recess.

One light emitting element130(white LED) was disposed on substrate120, and a light flux controlling member main body having a length of 100 mm was disposed on light emitting element130. The outer diameter of cover140was 26 mm. It is to be noted that diffusing member1220was not disposed in these illumination apparatuses.

FIG. 33Ais a graph illustrating results of a simulation of the illuminance distribution on the upper side of the illumination apparatuses, andFIG. 33Bis a graph illustrating results of a simulation on the near side (front surface side) of the illumination apparatuses. The abscissa represents the position of illumination apparatus100in the major axis direction (D; mm), and the center point where light emitting element130is disposed is “0.” The ordinate represents the illuminance (I; lux) at each point when the external surface (exterior surface) of cover140is assumed to be the illuminated surface. InFIGS. 33A and 33B, solid line A represents the luminance distribution of an illumination apparatus including light flux controlling member1000having no recess, broken line B represents the luminance distribution of an illumination apparatus including a light flux controlling member main body in which the maximum depth of the recess is 0.5 mm, dashed line C represents the luminance distribution of an illumination apparatus including a light flux controlling member main body in which the maximum depth of the recess is 1.0 mm, broken line D represents the luminance distribution of an illumination apparatus including a light flux controlling member main body in which the maximum depth of the recess is 1.5 mm, solid line E represents the luminance distribution of an illumination apparatus including a light flux controlling member main body in which the maximum depth of the recess is 2.0 mm, and solid line F represents the luminance distribution of an illumination apparatus including a light flux controlling member main body in which a second recesses are not in communication with each other. It is to be noted that, in positions in the major axis direction of the illumination apparatus, the peaks around +60 mm and −60 mm are associated with light emitted from the side surfaces of the light flux controlling member.

As illustrated inFIG. 33AandFIG. 33B, in the light flux controlling member main bodies in which the maximum depth of second recess1670is 0.5, 1.0, or 1.5 mm (light flux controlling member1600of the second modification of Embodiment 6) and the light flux controlling member main body in which second recesses1270are not in communication with recess250(light flux controlling member1200of Embodiment 6), the illuminance on the external surface of cover140in association with light emitted from the end portion of light guiding section and the illuminance on the external surface of cover140in association with light emitted from a region around the center portion were substantially the same, and the luminance unevenness was small. On the other hand, in light flux controlling member main body1600′ in which the maximum depth of second recess1670′ is 2.0 mm, the illuminance on the external surface of cover140in association with light emitted from a region around the center portion was significantly greater than the illuminance on the external surface of cover140in association with light emitted from the end portion of light guiding section1230, and thus significant luminance unevenness was undesirably caused. Accordingly, in the light flux controlling member main bodies used herein, the maximum depth of the second recess preferably falls within the range of 0.0 to 1.5 mm.

This application is entitled to and claims the benefit of Japanese Patent Application No. 2012-093813 filed on Apr. 17, 2012, Japanese Patent Application No. 2012-263162 filed on Nov. 30, 2012, and Japanese Patent Application No. 2013-046735 filed on Mar. 8, 2013, the disclosure each of which including the specification, drawings and abstract is incorporated herein by reference in its entirety.

INDUSTRIAL APPLICABILITY

The illumination apparatus of the embodiments of the present invention can be used in place of fluorescent tubes, and is therefore widely applicable to various kinds of illumination apparatus.

REFERENCE SIGNS LIST