JP5764407B2 - Luminous flux control member, light emitting device, and surface light source device - Google Patents

Description

The present invention relates to a light beam control member that controls the emission of light from a light emitting element (for example, an LED), a light emitting device that uses the light beam control member, and a surface to be illuminated such as a liquid crystal display panel using the light emitting device. The present invention relates to a surface light source device that illuminates in a shape.

In recent years, from the viewpoint of energy saving and environmental protection, illuminated members such as advertising panels are illuminated by light emitting devices using LEDs as light sources.

For example, the light emitting device 100 shown in FIG. 4B is configured such that light from the LED 101 is emitted as illumination light through the optical direction conversion optical element 102. The light direction changing optical element 102 of the light emitting device 100 causes the light from the LED 101 to enter the inside from the light incident surface 103, and reflects a part of the light incident from the light incident surface 103 by the light reflecting surface 104. A part of the light that is emitted from the light exit surface (cylindrical side surface) 105 and is emitted from the light exit surface 104 out of the light incident from the light incident surface 103 is emitted from the light reflecting surface 104. ing. A plurality of such light emitting devices 100 are arranged in a line on the substrate, and constitute a surface light source device that illuminates an illuminated member (not shown) such as an advertising panel in a planar shape from the back side. (Patent Document 1).

Also proposed is a surface light source device in which the side view LED is arranged in the center of the surface light source device (surface illumination device), the emitted light from the side view LED is guided to the hollow light guide region, and the light emitting surface member is evenly irradiated. (Patent Document 2 (FIGS. 5 and 6)).

Republished Patent No. WO2008 / 007492 JP 2010-009785 A

When the light emitting device 100 of Patent Document 1 is used in the surface light source device of Patent Document 2 instead of the side view LED of Patent Document 2, the portion directly above the row where the light emitting device 100 is arranged on the light emitting surface becomes particularly bright. . Such a problem occurs in a surface light source device in which a plurality of light emitting devices 100 are arranged in a row and the arrangement density of the light emitting devices 100 is sparse in a direction orthogonal to the rows.

The light direction changing optical element 102 of the light emitting device 100 is formed in a rotationally symmetric shape with respect to its central axis, so that light is emitted isotropically in all directions 360 degrees from the central axis in a plan view. The Therefore, immediately above the row in which the light emitting devices 100 are arranged, the light irradiation ranges from the plurality of light emitting devices 100 overlap, and a bright portion is more likely to occur than in a direction where the arrangement density of the light emitting devices 100 is sparse.

Therefore, the present invention is applicable to a surface light source device having different arrangement densities of light emitting devices in two directions orthogonal to each other, a light flux controlling member having anisotropic orientation characteristics, a light emitting device using the light flux controlling member, and the light emission An object of the present invention is to provide a surface light source device using the device.

As shown in FIGS. 1 and 11, the invention of claim 1 is centered on an optical axis L, which is a direction in which light at the center of a three-dimensional outgoing light beam from the light emitting element 3 travels with respect to the light emitting element 3. The light flux control member 4 is arranged as follows. The light flux controlling member 4 according to the present invention includes a light incident surface portion 7 on which light from the light emitting element 3 is incident, a light reflecting surface portion 11 that reflects light incident from the light incident surface portion 7, and the light flux controlling member 4. A light emitting surface portion 12 that is located on the side surface and emits light reflected by the light reflecting surface portion 11. The light incident surface portion 7 is formed on the back surface 5 side of the light flux controlling member 4 facing the light emitting element 3 , arranged so as to be centered on the optical axis L, and the light emitting element 3. It arrange | positions so that it may oppose. In addition, the light incident surface portion 7 includes a first light incident surface portion 13 on which a first light beam portion that is a central light beam portion located in the vicinity of the optical axis L of the emitted light beam is incident, and the first light incident surface portion 13. The light traveling direction of the second light beam portion, which is disposed so as to surround the light incident surface portion 13 and is positioned so as to surround the first light beam portion of the emitted light beam, is substantially along the optical axis L. In this way, the second light incident surface portion 14 that is converted into an optical path and is incident on the light flux controlling member 4 is provided. The second light incident surface portion 14 is a Fresnel lens including a plurality of protrusions 15a and 15b that are formed so as to protrude concentrically around the optical axis L. The light reflecting surface portion 11 is a tapered surface that forms a tapered recess 10 that is recessed from the top surface 8 located on the opposite side of the back surface 5 of the light flux controlling member 4 toward the back surface 5 side. Thus, the light is formed so as to converge on the optical axis L, and the light incident from the light incident surface portion 7 is reflected toward the light emitting surface portion 12. The light exit surface portion 12 connects the pair of first exit surfaces 17a and 17b formed symmetrically with respect to the virtual plane including the optical axis L and the pair of first exit surfaces 17a and 17b. Second exit surfaces 18 and 18 are provided. Further, the first emission surfaces 17a and 17b are formed so as to diverge and emit the light reaching via the light reflecting surface portion 11, rather than the second emission surfaces 18 and 18. When the direction orthogonal to the axis L is a side, the light reflected by the light reflecting surface portion 11 is emitted from the first emission surfaces 17a and 17b and the second emission surfaces 18 and 18 toward the side. It is like that.

The invention of claim 2 is characterized in that the second exit surface 18 of the light exit surface portion 12 of the light flux controlling member 4 according to the invention of claim 1 is characterized as shown in FIG. That is, the second emission surface 18 is a part of a cylindrical surface centered on the optical axis L.

The invention of claim 3 is characterized in that the second exit surface 18 of the light exit surface 12 in the light flux controlling member 4 according to the invention of claim 1 as shown in FIG. That is, the second emission surface 18 is a tapered surface having a smaller diameter on the top surface 8 side than the back surface 5 side, and is a part of a tapered surface centered on the optical axis L.

As shown in FIGS. 1 and 11, the light beam control member 4 according to any one of the first to third aspects is characterized in that the first emission surfaces 17 a and 17 b have a feature. . That is, the first emission surfaces 17a and 17b are a pair of planes parallel to the optical axis L and a pair of planes symmetrical with respect to the plane including the optical axis L.

As shown in FIGS. 1 and 11, the invention of claim 5 includes a light emitting element 3 installed on a substrate 2 and a light flux controlling member 4 according to any one of claims 1 to 4 . The light-emitting devices 1 and 32 are characterized by the above.

In the invention of claim 6 , as shown in FIG. 9, a plurality of light emitting devices 1 and 32 according to the invention of claim 5 are arranged in a row, and the light emitted from the plurality of light emitting devices is reflected by the reflecting member 25. The present invention relates to the surface light source device 22 that illuminates the illuminated member 26 in a planar shape by the light emitted directly from the light emitting devices 1 and 32 and the light reflected by the reflecting member 25. In the surface light source device 22, the light flux controlling members 4 of the adjacent light emitting devices 1 and 32 are arranged such that the first emission surfaces 17 a and 17 b face each other.

According to the light flux controlling member of the present invention, anisotropic alignment characteristics can be realized, and even if a plurality of densely arranged light flux controlling members are arranged adjacent to each other, the light flux controlling members are densely arranged. Can be suppressed by the first emission surface of the light emission surface portion, and the light from a plurality of light sources overlaps at the intermediate position with other light flux control members arranged closely to illuminate the same portion. It is possible to suppress the occurrence of bright portions due to the above. As a result, according to the light flux controlling member of the present invention, variation in illuminance distribution on the irradiated surface can be suppressed, and illumination quality can be improved.

1 shows a light emitting device according to a first embodiment of the present invention. 1A is a front view of the light emitting device, FIG. 1B is a plan view of the light emitting device, FIG. 1C is a side view of the light emitting device, and FIG. 1D is a light emitting device. FIG. 1E is a cross-sectional view of the light-emitting device shown by cutting along the line A1-A1 of FIG. 1B, and FIG. 1F is FIG. 1B. It is sectional drawing of the light-emitting device cut | disconnected and shown along A2-A2 line | wire. FIG. 2 is an enlarged view of a second light incident surface portion of a light flux controlling member constituting the light emitting device according to the first embodiment of the present invention, and FIG. 2A is a first example of the second light incident surface portion, FIG. FIG. 2B is a diagram illustrating a second example of the second light incident surface portion, and FIG. 2C is a diagram illustrating a third example of the second light incident surface portion. FIG. 3 is a diagram showing an optical path diagram of a light emitting device according to the first embodiment of the present invention and a conventional light emitting device in comparison, and FIG. 3A is an optical path diagram when the light emitting device according to the first embodiment is viewed in plan view. FIG. 3B is an optical path diagram when the conventional light emitting device is viewed in plan. FIG. 4 is a diagram showing an optical path diagram of the light emitting device according to the first embodiment of the present invention and a conventional light emitting device in comparison, and FIG. 4A is an optical path diagram in a longitudinal section of the light emitting device according to the first embodiment. 4 (b) is an optical path diagram in a longitudinal section of a conventional light emitting device. 1 shows a light emitting device according to Comparative Example 1; FIG. 5A is a front view of the light emitting device, FIG. 5B is a plan view of the light emitting device, and FIG. 5C is a back view of a light flux controlling member constituting the light emitting device. (D) is sectional drawing of the light-emitting device shown cut along the A3-A3 line of FIG.5 (b). It is a figure which contrasts and shows the illumination distribution of the light-emitting device which concerns on 1st Embodiment of this invention, and the light-emitting device which concerns on the comparative example 1. FIG. 7A is a front cross-sectional view illustrating a measurement state of the illuminance distribution of the light emitting device according to the first embodiment of the present invention, and FIG. 7B illustrates a measurement state of the illuminance distribution of the light emitting device according to Comparative Example 1. It is front sectional drawing shown. 8A is a plan view showing a measurement state of the illuminance distribution of the light emitting device according to the first embodiment of the present invention, and FIG. 8B is a plan view showing a measurement state of the illuminance distribution of the light emitting device according to Comparative Example 1. FIG. 9A is a plan view of the surface light source device, FIG. 9B is a sectional view of the surface light source device cut along the line A4-A4 of FIG. 9A, and FIG. It is sectional drawing of the surface light source device cut | disconnected and shown along the A5-A5 line | wire of 9 (a). FIG. 10A is a diagram showing an illuminance distribution measurement region of the surface light source device, and FIG. 10B is an enlarged view of a portion F (illuminance distribution measurement region) of FIG. 10A. . 2 shows a light emitting device according to a second embodiment of the present invention. 11A is a front view of the light emitting device, FIG. 11B is a plan view of the light emitting device, FIG. 11C is a side view of the light emitting device, and FIG. 11D is a light emitting device. FIG. 11 (e) is a cross-sectional view of the light-emitting device shown by cutting along the line A6-A6 of FIG. 11 (b), and FIG. 11 (f) is FIG. 11 (b). It is sectional drawing of the light-emitting device shown cut | disconnected along A7-A7 line | wire. 4 shows a light emitting device according to Comparative Example 2. 12A is a front view of the light-emitting device, FIG. 12B is a plan view of the light-emitting device, and FIG. 12C is a back view of a light flux controlling member constituting the light-emitting device. (D) is sectional drawing of the light-emitting device shown cut along the A8-A8 line of FIG.12 (b). It is a figure which contrasts and shows the illumination distribution of the light-emitting device which concerns on 2nd Embodiment of this invention, and the light-emitting device which concerns on the comparative example 2. FIG. FIG. 14A is a front cross-sectional view showing the measurement state of the illuminance distribution of the light emitting device according to the second embodiment of the present invention, and FIG. 14B shows the measurement state of the illuminance distribution of the light emitting device according to Comparative Example 2. It is front sectional drawing shown. 15A is a plan view showing a measurement state of the illuminance distribution of the light emitting device according to the first embodiment of the present invention, and FIG. 15B is a plan view showing a measurement state of the illuminance distribution of the light emitting device according to Comparative Example 1. FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[First Embodiment]
(Light emitting device)
FIG. 1 shows a light emitting device 1 according to this embodiment. 1A is a front view of the light emitting device 1, FIG. 1B is a plan view of the light emitting device 1, FIG. 1C is a side view of the light emitting device 1, and FIG. d) is a rear view of the light emitting device 1, and FIG. 1 (e) is A1 in FIG. 1 (b).
FIG. 2 is a cross-sectional view of the light-emitting device 1 shown cut along the line A <b> 1, and FIG.
It is sectional drawing of the light-emitting device 1 shown cut | disconnected along 2-A2 line.

As shown in FIG. 1, the light emitting device 1 includes a light emitting element 3 (for example, L) installed on a substrate 2.
The light from the ED and the LED sealed by the sealing member is emitted through the light flux control member 4, and the light emitting element 3 and the light flux control member 4 correspond one-to-one. And
In the light emitting device 1, a leg 6 erected on the back surface 5 side of the light flux controlling member 4 is fixed on the substrate 2 on which the light emitting element 3 is mounted with an adhesive, and the central axis L 1 of the light flux controlling member 4 emits light. It is positioned concentrically with the optical axis L of the element 3. Here, the optical axis L of the light emitting element 3 refers to the traveling direction of light at the center of the three-dimensional emitted light beam from the light emitting element 3.

(Flux control member)
The light flux controlling member 4 is made of, for example, a transparent resin material such as PMMA (polymethyl methacrylate), PC (polycarbonate), EP (epoxy resin), or transparent glass.

The light flux controlling member 4 is formed in a planar shape obtained by cutting off a circle with a width of two faces.
The central axis L1 is coincident with the planar centroid. The light flux controlling member 4 includes a light incident surface portion 7 formed on the back surface 5 (the bottom surface of FIGS. 1A and 1D) facing the light emitting element 3, and a top surface located on the opposite side of the back surface 5. 8 (the upper surface of FIGS. 1A and 1D), a tapered light reflecting surface portion 11 that forms a recess 10 recessed in a substantially conical shape from the top surface 8, and the outer edge and the top surface 8 of the back surface 5 And a light emitting surface portion 12 that connects the outer edge. Here, the term “conical” means not only when the surface of the recess 10 has a conical shape, but also when the surface of the recess 10 has a curved surface resembling a conical shape, or when the surface of the recess 10 has a conical shape. This also includes the case of a similar aspherical surface (in this embodiment). In this light flux controlling member 4, four leg portions 6 that are fixed on the substrate are erected on the back surface 5 radially outward from the light incident surface portion 7.

The light incident surface portion 7 is a first circular flat surface centered on the central axis L1 of the light flux controlling member 4.
The light incident surface portion 13 and a second light incident surface portion 14 formed so as to surround the first light incident surface portion 13. The first light incident surface portion 13 is a central light flux portion located in the vicinity of the optical axis L of the light flux emitted from the light emitting element 3, and the traveling direction of the light is substantially along the optical axis L. The first light beam portion is made incident. The second light incident surface portion 1
Reference numeral 4 denotes a light beam portion other than the first light beam portion of the emitted light beam from the light emitting element 3, and a second light beam portion positioned so as to surround the first light beam portion is made incident thereon. This second
The light incident surface portion 14 is a Fresnel lens in which a plurality of ring-shaped protrusions 15a and 15b are concentrically formed, and each of the protrusions 15a and 15b is a surface 15a1 and 15b1 positioned on the inner side (near the central axis L1). And the surfaces 15a2 and 15b2 positioned on the outer side, and the light of the second light flux portion is made to face the surfaces 15a1, 15b1 so that the light traveling direction of the second light flux portion is aligned in a direction substantially parallel to the optical axis L. And is totally reflected by the surfaces 15a2 and 15b2 (see FIG. 2A). Here, the reason why the traveling direction of the light in the second light beam portion is aligned in a direction “substantially” parallel to the optical axis L is that the manufacturing error of the Fresnel lens as the second light incident surface portion 14,
Assembling error between the light emitting element 3 and the light flux controlling member 4 and the light emitting point of the light emitting element 3 emit light with a certain area instead of one point. Considering deviation from the parallel direction (from the design value).

1 (e) and 1 (f), the light reflecting surface portion 11 is a tapered surface (substantially conical concave surface that forms a rotationally symmetric tapered recess 10 centered on the central axis L1. (A rotationally symmetric aspherical surface about the axis L1), and the apex 16 of the tapered surface is formed so as to be located on the central axis L1 (so that the tapered surface converges on the central axis L1), and a part thereof It is cut out by a dihedral width portion 17 described later. In addition, the light reflecting surface portion 11 is
The diameter D2 of the end portion on the top surface 8 side is larger than the diameter D1 on the outer peripheral end side of the light incident surface portion 7 (D1 ≦
D2). Such a light reflecting surface portion 11 totally reflects the light incident from the light incident surface portion 7 toward the light emitting surface portion 12. Note that the diameter D2 of the end portion on the top surface 8 side of the light reflecting surface portion 11 is smaller than the diameter D3 at the outer peripheral end of the top surface 8.

The light emission surface portion 12 includes a pair of flat surfaces 17a and 17b parallel to the central axis L1 and a two-surface width portion 17 as a first emission surface including a pair of planes 17a and 17b that are plane-symmetric with respect to a plane including the central axis L1. A pair of curved surfaces 18a and 18b connecting the pair of flat surfaces 17a and 17b, the top surface 8 and the back surface 5 and a pair of curved surfaces 18a and 18b forming a part of a cylindrical surface centered on the optical axis L. It consists of a curved surface portion 18 as two exit surfaces. That is, the light emission surface portion 12 is formed by cutting the outer peripheral surface of the cylinder by a pair of virtual planes parallel to the central axis of the cylinder and a plane symmetric with respect to a plane including the central axis of the cylinder. It has a side shape like this. Such a light emitting surface portion 12 emits light totally reflected by the light reflecting surface portion 11 from the two-surface width portion 17 and the curved surface portion 18 to the side when the direction orthogonal to the optical axis L is the side. It is supposed to be. The light exit surface portion 12 is provided with a draft gradient along the Z-axis direction in order to facilitate the release of the light flux controlling member 4 from an injection mold (not shown).

FIG. 2A is an enlarged view showing the second light incident surface portion 14 in the light flux controlling member 4 shown in FIG. As shown in FIG. 2A, the second light incident surface portion 14 is formed such that other ring-shaped protrusions 15a have the same height except for the outermost ring-shaped protrusion 15b. In addition, the 2nd light-incidence surface part 14 is not limited to the shape shown to Fig.2 (a), You may make it a shape as shown to FIG.2 (b)-(c). That is, the second light incident surface portion 14 shown in FIG. 2B has a ring-shaped protrusion 15 adjacent to the outermost ring-shaped protrusion 15b.
From a to the innermost ring-shaped protrusion 15a is formed obliquely so as to approach the light emitting element 3 at an angle θ1 with respect to the back surface 5 (see FIG. 1). Further, the second light incident surface portion 14 shown in FIG. 2C has a protrusion height as it goes from the ring-shaped protrusion 15a adjacent to the outermost ring-shaped protrusion 15b to the innermost ring-shaped protrusion 15a. Is formed to gradually increase.
Here, in each of the second light incident surface portions 14 shown in FIGS. 2A to 2C, the formation position of the ring-shaped protrusion 15 a adjacent to the outermost ring-shaped protrusion 15 b is a position λ from the back surface 5. It is in. Thus, by devising the shape of the second light incident surface portion 14, it is possible to reduce the light that enters from the surfaces 15 a 1 and 15 b 1 and reaches the light emitting surface portion 12 directly without passing through the surfaces 15 a 2 and 15 b 2. it can.

The light flux controlling member 4 according to the present embodiment has a pair of flat surfaces 17a that form the dihedral width portion 17.
, 17b is formed so that the ratio (W / D3) of the width dimension W between the curved surface portion 18 and the diameter D3 of the curved surface portion 18 is 0.7, but is not limited thereto, and is optimal in accordance with the required light flux control performance. Number (W /
D3) is employed.

(Luminescent characteristics)
3 and 4 show the optical path diagrams of the light emitting device 1 according to the present embodiment and the conventional light emitting device 100 in comparison. FIG. 3A is an optical path diagram when the light emitting device 1 according to this embodiment is viewed in plan. FIG. 3B is an optical path diagram when the conventional light emitting device 100 is viewed in plan. FIG. 4A is an optical path diagram in a longitudinal section (a section corresponding to FIG. 1F) of the light emitting device 1 according to the present embodiment. FIG. 4B is an optical path diagram in a longitudinal section of the conventional light emitting device 100.

First, based on FIG. 3, the light emission characteristics of the light emitting device 1 according to the present embodiment and the conventional light emitting device 10.
This will be described in comparison with the light emission characteristics of zero. As shown in FIG. 3B, the conventional light emitting device 100 distributes light uniformly around the optical element for optical direction conversion 102 (all directions of 360 ° in the XY plane) around the optical axis L. (Isotropically). On the other hand, as shown in FIG. 3A, in the light emitting device 1 according to this embodiment, light emitted from the two-surface width portion 17 of the light flux controlling member 4 is emitted from the curved surface portion 18 of the light flux controlling member 4. Outgoes light closer to the Y direction than the light, emits light closer to the X axis direction, sparse, and emits light from the vicinity of the middle between the X axis and the Y axis so that the emitted light closer to the Y axis direction becomes dense. .

Next, the light emission characteristics of the light emitting device 1 according to the present embodiment and the light emission characteristics of the conventional light emitting device 100 will be described based on FIG. As shown in FIG. 4B, the conventional light emitting device 100 causes the light from the LED 101 to enter the light direction changing optical element 102 from the light incident surface 103 of the light direction changing optical element 102, and the light. A part of the light incident from the incident surface 103 is reflected by the light reflecting surface 104 of the light direction converting optical element 102 and is emitted from the light emitting surface (cylindrical side surface) 105 of the light direction converting optical element 102. Of the light incident from the light incident surface 103 of the direction changing optical element 102, a part of the light except the light emitted from the light emitting surface 105 of the light direction changing optical element 102 is used as the light of the light direction changing optical element 102. The light is emitted from the reflection surface 104. On the other hand, as shown in FIG. 4A, the light emitting device 1 according to the present embodiment causes the light from the light emitting element 3 to enter the light beam control member 4 from the light incident surface portion 7 of the light beam control member 4, The light incident from the light incident surface portion 7 is totally reflected by the light reflecting surface portion 11 toward the light emitting surface portion 12 side, and the light totally reflected by the light reflecting surface portion 11 is transmitted from the light emitting surface portion 12 to the light flux controlling member 4 side. It is made to emit to the direction. Here, the light emitting device 1 according to the present embodiment uses the first light beam of the light beam control member 4 as the first light beam portion, which is the light beam portion on the center side located in the vicinity of the optical axis L of the emitted light beam from the light emitting element 3. Incident light is made to travel from the incident surface portion 13 in a direction along the optical axis L. Further, in the light emitting device 1 according to the present embodiment, the second light beam portion positioned so as to surround the first light beam portion of the emitted light beam from the light emitting element 3 is approximately aligned with the optical axis L by the second light incident surface portion 14. The light path is changed so as to be parallel and incident. As a result, the light emitting device 1 according to the present embodiment can efficiently totally reflect the light from the light emitting element 3 incident from the light incident surface portion 7 of the light flux controlling member 4 by the light reflecting surface portion 11. It is possible to suppress emission from the light reflecting surface portion 11 in the direction directly above the light emitting element 3 (Z-axis direction).

(Comparative Example 1)
FIG. 5 shows a light emitting device 20 according to Comparative Example 1. The light emitting device 20 according to the comparative example 1 is in the present embodiment in that the light exit surface portion 12 of the light flux controlling member 4 is a cylindrical surface and the two-surface width portion 17 is not formed on the light flux controlling member 4. Different from the light emitting device 1. The light-emitting device 20 according to Comparative Example 1 is common to the light-emitting device 1 according to this embodiment because the other configurations are the same as those of the light-emitting device 1 according to this embodiment except for the shape of the light emission surface portion 12. Components that are the same as those in the light-emitting device 1 according to the present embodiment are denoted by the same reference numerals, and descriptions that overlap with those of the light-emitting device 1 according to the present embodiment are omitted.

Similar to the light emitting device 100 according to the conventional example, the light emitting device 20 according to Comparative Example 1 emits light isotropically in all directions of 360 ° from the optical axis in a planar view. Further, the light emitting device 20 according to the comparative example 1 can suppress the emission of light from the light reflecting surface portion 11 in the same manner as the light flux controlling member 4 of the light emitting device 1 according to the present embodiment. Therefore, the light emitting device 20 according to the comparative example 1 can suppress the emission of light in the direction directly above the light emitting element 3 (Z-axis direction) as compared with the light emitting device 100 according to the conventional example.

(Comparison with Comparative Example 1)
FIG. 6 shows the illuminance distribution of the light emitting device 20 according to the comparative example 1 and the light emitting device 1 according to the present embodiment in comparison. That is, FIG. 6 shows the illuminance distribution on the irradiated surface irradiated with the light emitted from the light emitting device 1 according to this embodiment and the irradiated surface irradiated with the light emitted from the light emitting device 20 according to Comparative Example 1. It is a figure which compares and shows the upper illumination distribution. In FIG. 6,
A diagram represented by a solid line shows the illuminance distribution by the light emitting device 1 according to the present embodiment, and a diagram represented by a dotted line shows the illuminance distribution by the light emitting device 20 according to Comparative Example 1. In FIG. 6, the horizontal axis indicates the distance (mm) from the light emitting element 3 (optical axis L), and the vertical axis indicates the illuminance ratio when the maximum illuminance of Comparative Example 1 is 1.

Further, the illuminance distribution on the irradiated surface shows the result of measurement by moving the measurement point from the optical axis L in the ± X direction at a predetermined interval on the irradiated surface 21, as shown in FIGS. Is.
Further, the irradiated surface 21 is disposed at a position separated from the substrate 2 by H along the Z-axis direction. Further, the light flux controlling member 4 of the light emitting device 1 according to the present embodiment is disposed so that the two-surface width portion 17 of the light emitting surface portion 12 is orthogonal to the ± X axis direction.

As shown in FIG. 6, the light emitting device 1 according to the present embodiment includes a light emitting device 20 according to Comparative Example 1.
As a result, the illuminance on the irradiated surface 21 immediately above the X axis can be kept low. This is due to the function (see FIG. 3A) of the dihedral width portion 17 of the light flux controlling member 4 in the light emitting device 1 according to the present embodiment.

(Surface light source device)
FIG. 9 is a diagram showing a surface light source device 22 using the above-described light emitting device 1. Note that FIG.
) Is a plan view of the surface light source device 22, FIG. 9B is a sectional view of the surface light source device 22 cut along the line A4-A4 of FIG. 9A, and FIG. 9C is FIG. It is sectional drawing of the surface light source device 22 cut | disconnected and shown along the A5-A5 line of a).

As shown in FIG. 9, the surface light source device 22 includes a casing 23 having a rectangular planar shape and opening upward, a reflecting member 25 disposed on the inner bottom surface 24 of the casing 23, and a casing. A plurality of light emitting devices 1 arranged in a row and at equal intervals on the reflecting member 25 along the longitudinal direction of the housing 3 along the longitudinal direction of the housing 3 (X direction in FIG. 9A), and the housing 23 And an illuminated member 26 (for example, a liquid crystal panel or an advertising panel) arranged so as to close the opening. Here, the light emitting devices 1 and 1 adjacent to each other are flat surfaces 17 a and 17 b that form the dihedral width portion 17 of the light flux controlling member 4.
Are arranged so as to face each other.

In this surface light source device 22, the reflecting member 25 is formed of, for example, a plate-like member having excellent light reflecting performance, and is parallel to the inner bottom surface 24 of the housing 23 as shown in FIG. Body 2
3 and a flat surface 25a extending along the X direction with a constant width, and a pair of inclined surfaces 25b and 25b rising obliquely from both ends of the flat surface 25a in the Y direction toward the opening end of the housing 23. It has become.

The surface light source device 22 configured as described above reflects light emitted from the light emitting device 1 toward the side by the reflecting member 25 and the inner wall surface 27 of the housing 23, and the reflected light causes the illuminated member 26 to be illuminated. It is designed to illuminate in a planar form from the back side.

(Contrast of the surface light source device according to this embodiment and the surface light source device according to Comparative Example 1)
Next, regarding the surface light source device 22 according to the present embodiment and the surface light source device 28 according to Comparative Example 1, on the irradiated surface 30 (the surface inside the illuminated member 26 and facing the light emitting device 1). The illuminance distribution will be described in comparison with Tables 1 to 3 shown below. Here, the surface light source device 28 according to Comparative Example 1 is obtained by replacing the light emitting device 1 of the surface light source device 22 according to the present embodiment with the light emitting device 20 according to Comparative Example 1 (see FIG. 9).

Table 1 shows the illuminance distribution on the irradiated surface 30 in the surface light source device 28 according to Comparative Example 1 (see FIGS. 9 and 10). Table 2 shows the illuminance distribution on the irradiated surface 30 in the surface light source device 22 according to the present embodiment. However, as shown in FIG. 10, the irradiated surface 30 as the measurement range of the illuminance distribution has a long side dimension of 700 mm and a short side dimension of 400 mm.
When the irradiated member 26 of mm is viewed in plan, the light axis L of the central light emitting device 1 (20) and the light of the other light emitting device 1 (20) located to the right of the central light emitting device 1 (20). Including an axis L, and
A center line 31 connecting the optical axes L and L of the adjacent light emitting devices 1 (20) and 1 (20) (as shown in FIG. 9, a plurality of light emitting devices 1 and 20 are arranged in a line. Surface light source device 2
2 (28) center line 31) to a direction orthogonal to the center line 31 (Y direction) is a rectangular range including a position of 50 mm. And in this irradiated surface 30, central light-emitting device 1 (2
The light emitting device 1 (20) at the center is defined as a row passing through the optical axis L of 0) and orthogonal to the center line 31.
The column passing through the intermediate position of the optical axis L of the other light emitting device 1 (20) and the optical axis L of the other light emitting device 1 (20) and orthogonal to the center line 31 is b row, and is adjacent to the central light emitting device 1 (20). Other light emitting device 1 (2
0), the column passing through the optical axis L and orthogonal to the center line 31 is c, and the center line 31 of each column a to c.
The upper position (0 mm), the position 25 mm in the Y direction from the center line 31 of each row a to c, and each row a
A total of nine locations of 50 mm in the Y direction from the center line 31 of ~ c are illuminance measurement locations. Moreover, the maximum value of the illumination intensity on the to-be-irradiated surface 30 of the surface light source device 28 which concerns on the comparative example 1 was set to 100, and the illumination intensity distribution of Table 1 and Table 2 was represented on the basis of this maximum value (100).

As shown in Table 1, in the surface light source device 28 according to Comparative Example 1, the light from the plurality of light emitting devices 20 arranged in a row illuminates the array of the light emitting devices 20 in an overlapping manner. It can be seen that the value of illuminance at is high and a bright portion is generated on the center line 31. In Comparative Example 1, the illuminance value is particularly high at the intermediate position between adjacent light emitting devices 20 and 20 (position in row b and 0 mm in the Y direction) higher than other parts (close to the maximum value of 100). Adjacent light emitting device 2
It can be seen that a bright portion is generated at an intermediate position between 0 and 20.

On the other hand, as shown in Table 2, in the surface light source device 22 according to the present embodiment, light from the plurality of light emitting devices 1 arranged in a row overlaps and illuminates immediately above the arrangement of the light emitting devices 1. Therefore, the illuminance value on the center line 31 can be made substantially uniform, and each column a to
The difference between the illuminance value on the center line 31 of c and the illuminance value at the position of 50 mm in each column a to c is smaller than that in Table 1.

Here, assuming that the value obtained by dividing the maximum value of the illuminance measurement value in Table 1 by the minimum value is the degree of uniformity, the degree of uniformity of the surface light source device 28 according to Comparative Example 1 is 1.72. Further, if the value obtained by dividing the maximum value of the illuminance measurement in Table 2 by the minimum value is the degree of uniformity, the degree of uniformity of the surface light source device 22 according to the present embodiment is 1.38. As described above, the surface light source device 22 according to the present embodiment has a degree of uniformity smaller than that of the surface light source device 28 according to Comparative Example 1, and the illuminance distribution on the irradiated surface 30 is a surface light source according to Comparative Example 1. It is made more uniform than the illuminance distribution on the irradiated surface 30 of the device 28.

Table 3 shows measured values of illuminance at each measurement point of the surface light source device 28 according to Comparative Example 1 (see Table 1).
Measurement value of illuminance at each measurement point of the surface light source device 22 according to the present embodiment (see Table 2)
The change rate (illuminance change rate) is shown as “illuminance ratio”. As shown in Table 3,
The difference in illuminance increases from the position of 50 mm toward the center line (0 mm) in each column a to c, and is the largest at the measurement point on the center line (0 mm) of the b column. Such an illuminance change rate is attributed to the function of the dihedral width portion 17 of the light flux controlling member 4 according to the present embodiment.

Although Tables 1 to 3 above do not indicate the illuminance of the entire inner surface (all irradiated surfaces) of the illuminated member 26, the surface light source device 22 according to the present embodiment and the surface according to the comparative example 1. The average value of illuminance on all irradiated surfaces in the light source device 28 was substantially the same. From this, it was confirmed that the surface light source device 22 according to the present embodiment did not cause light loss as compared with the surface light source device 28 according to Comparative Example 1.

[Second Embodiment]
(Light emitting device)
FIG. 11 shows a light emitting device 32 according to a second embodiment of the present invention. The light emitting device 32 shown in FIG. 11 is different from the light flux controlling member 4 according to the first embodiment in the shape of the light exit surface 12 of the light flux controlling member 4, but the other configuration is the light emitting device 1 according to the first embodiment. So that
Constituent parts corresponding to the light emitting device 1 according to the first embodiment are denoted by the same reference numerals, and descriptions overlapping with those of the light emitting device 1 according to the first embodiment are omitted.

In the light flux controlling member 4 constituting the light emitting device 32 according to the second embodiment, the curved surface portion 18 of the light emitting surface portion 12 is a part of a tapered surface. That is, the curved surface portion 18 of the light emitting surface portion 12 is
The top surface 8 side is a tapered surface having a smaller diameter than the back surface 5 side, and is a part of the tapered surface centered on the central axis L1 (optical axis L). In the second embodiment, the light flux controlling member 4 has D5 / D4 of 0.8, where the outer diameter on the back surface 5 side is D4 and the outer diameter on the top surface 8 side is D5. Further, in the second embodiment, the light flux controlling member 4 sets W / D4 to 0.7, where W is the width dimension of the two-surface width portion 17. However, the light flux controlling member 4 according to the second embodiment is not limited to such a value of D5 / D4, W / D4, and optimum numerical values (D5 / D4, W / D4) according to the required light flux controlling performance. ) Is adopted.

(Luminescent characteristics)
In the light emitting device 32 according to the second embodiment, since the curved surface portion 18 of the light flux controlling member 4 has a tapered shape, the light emitted from the curved surface portion 18 is emitted more than when the curved surface portion 18 of the light emitting element 3 has a cylindrical shape. Since the emission angle with respect to the optical axis L is slightly larger, the bright part that is likely to occur in the vicinity of the light emitting device 32 can be more effectively suppressed than the light emitting device 1 according to the first embodiment,
The light emitting characteristics similar to those of the light emitting device 1 according to the first embodiment are exhibited.

(Comparative Example 2)
FIG. 12 shows a light emitting device 33 according to Comparative Example 2. In the light emitting device 33 according to the comparative example 2, the shape of the light emitting surface portion 12 of the light flux controlling member 4 is a tapered surface, and the light flux controlling member 4
The second embodiment differs from the light emitting device 32 according to the second embodiment in that the dihedral width portion 17 is not formed. The light emitting device 33 according to the comparative example 2 has the same configuration as the light emitting device 32 according to the second embodiment except for the shape of the light emitting surface portion 12, and therefore the light emitting device 32 according to the second embodiment.
The components corresponding to are assigned the same reference numerals as those of the light emitting device 32 according to the second embodiment, and the description overlapping the description of the light emitting device 32 according to the second embodiment is omitted.

Similar to the light emitting device 100 according to the conventional example, the light emitting device 33 according to the comparative example 2 isotropically emits light from the light emitting surface portion 12 in all directions of 360 ° from the optical axis L in a planar view state. Is emitted. Further, in the comparative example 2, similarly to the light flux controlling member 4 of the light emitting device 32 according to the second embodiment, the emission of light from the light reflecting surface portion 11 can be suppressed. Therefore, the light emitting device 33 according to the comparative example 2 can suppress the emission of light in the direction directly above the light emitting element 3 as compared with the light emitting device 100 according to the conventional example.

(Comparison with Comparative Example 2)
FIG. 13 shows the illuminance distribution of the light emitting device 33 according to Comparative Example 2 and the light emitting device 32 according to the second embodiment in comparison. That is, FIG. 13 shows the illuminance distribution on the irradiated surface 21 irradiated with light emitted from the light emitting device 32 according to the second embodiment and the irradiated light irradiated from the light emitting device 33 according to Comparative Example 2. It is a figure which compares and shows the illumination distribution on the irradiation surface 21 (refer FIG. 14). In FIG. 13, a diagram represented by a solid line shows the illuminance distribution by the light emitting device 32 according to the second embodiment, and a diagram represented by a dotted line shows the illuminance distribution by the light emitting device 33 according to Comparative Example 2.

Further, as shown in FIGS. 14 and 15, the illuminance distribution on the irradiated surface 21 is obtained by measuring the measurement points by moving the measurement points from the optical axis L in the ± X direction at a predetermined interval on the irradiated surface 21. It is shown. Further, the irradiated surface 21 is disposed at a position separated from the substrate 2 by H along the Z-axis direction. Further, the light flux controlling member 4 of the light emitting device 32 according to the second embodiment has the light emitting surface portion 12.
Are disposed so as to be orthogonal to the ± X-axis direction.

As shown in FIG. 13, the light emitting device 32 according to the second embodiment can suppress the illuminance on the irradiated surface 21 immediately above the X axis lower than the light emitting device 33 according to Comparative Example 2.

(Surface light source device)
The light emitting device 32 according to the second embodiment constitutes the surface light source device according to the second embodiment by using the surface light source device 22 shown in FIG. 9 instead of the light emitting device 1 according to the first embodiment. can do. The light emitting device 33 according to Comparative Example 2 is the same as the light emitting device 2 according to Comparative Example 1.
By using instead of 0, the surface light source device according to Comparative Example 2 can be configured.

(Contrast of the surface light source device according to the second embodiment and the surface light source device according to Comparative Example 2)
Next, regarding the surface light source device according to the second embodiment and the surface light source device according to Comparative Example 2, the irradiated surface 3
The illuminance distribution on 0 will be described in comparison with Tables 4 to 6 shown below. The irradiated surface 30 corresponds to the irradiated surface 30 as the measurement range of the illuminance distribution shown in FIG. And nine illuminance measurement locations in Tables 4 to 6 (0 mm, 25 mm, 50 in each row ac)
Each of three locations in mm corresponds to the nine illuminance measurement locations in Tables 1 to 3. Also,
The maximum value of the measured values of the illuminance on the irradiated surface 30 of the surface light source device 28 according to Comparative Example 1 is defined as 100, and the illuminance distributions in Tables 4 and 5 are expressed using this maximum value (100) as a reference. .

Table 4 shows the illuminance distribution on the irradiated surface 30 in the surface light source device according to Comparative Example 2. Table 5 shows the illuminance distribution on the irradiated surface 30 in the surface light source device according to the second embodiment.

As shown in Table 4, the surface light source device according to Comparative Example 2 includes a plurality of light emitting devices 3 arranged in a line.
Since the light from 3 illuminates the light emitting device 33 in an overlapping manner, it can be seen that the illuminance on the center line 31 is high and a bright portion is generated on the center line 31. In Comparative Example 2,
In particular, the illuminance value at an intermediate position between the adjacent light emitting devices 33 and 33 (b row and 0 mm position) is conspicuously higher than the other portions, and a bright portion is generated at an intermediate position between the adjacent light emitting devices 33 and 33. I understand that. These points are common to the surface light source device 28 according to Comparative Example 1 shown in Table 1. However, the surface light source device according to the comparative example 2 can make the angle of the light emitted from the curved surface portion 18 with respect to the optical axis L larger than that of the surface light source device 28 according to the comparative example 1, and the bright portion near the light emitting device 33. Variation in illuminance distribution is reduced (Table 1,
(See Table 4).

On the other hand, as shown in Table 5, in the surface light source device according to the second embodiment, the light from the plurality of light emitting devices 32 arranged in a row overlaps and illuminates directly above the arrangement of the light emitting devices 32. Therefore, the illuminance value on the center line 31 can be made substantially uniform, and each column a
The difference between the illuminance value on the center line 31 of ˜c and the illuminance value at the position of 50 mm in each column a to c is smaller than that in Table 4. That is, the surface light source device according to the second embodiment can reduce variation in illuminance on the irradiated surface 30 as compared with the surface light source device according to Comparative Example 2.

Here, when the value obtained by dividing the maximum value of the illuminance value in Table 4 by the minimum value is defined as the degree of uniformity, the degree of uniformity of the surface light source device according to Comparative Example 2 is 1.43. Further, assuming that the value obtained by dividing the maximum value of illuminance measurement in Table 5 by the minimum value is the degree of uniformity, the degree of uniformity of the surface light source device according to the second embodiment is 1.
. 17 As described above, the surface light source device according to the second embodiment has a degree of uniformity smaller than that of the surface light source device according to Comparative Example 2, and the illuminance distribution on the irradiated surface 30 is according to Comparative Example 2. Is more uniform than the illuminance distribution on the irradiated surface 30.

Table 6 shows the measured values of illuminance at each measurement point of the surface light source device according to the second embodiment (see Table 5) with respect to the measured values of illuminance at each measurement point of the surface light source device according to Comparative Example 2 (see Table 4). The change rate (illuminance change rate) is shown as “illuminance ratio”. As shown in Table 6, the difference in illuminance increases from the position of 50 mm toward the center line (0 mm) in each row ac, and the measurement on the center line 31 (0 mm) in row b. It is the largest in terms. Such an illuminance change rate is caused by the function of the two-surface width portion 17 of the light flux controlling member 4 according to the second embodiment.

Although Tables 4 to 6 above do not indicate the illuminance of the entire inner surface (all irradiated surfaces) of the illuminated member 26, the surface light source device according to the second embodiment and the surface according to the comparative example 2. The average value of illuminance on all irradiated surfaces in the light source device was almost the same. From this, it was confirmed that the surface light source device according to the second embodiment did not cause light loss as compared with the surface light source device according to Comparative Example 2.

[Modification]
The top surface 8 of the light flux controlling member 4 according to the first embodiment of the present invention and the top surface 8 of the light flux controlling member 4 according to the second embodiment may be roughened.

Further, in the surface light source device 22 according to the present invention, the plurality of light emitting devices 1 are densely arranged in one row. However, the present invention is not limited to this, and a plurality of rows in which the plurality of light emitting devices 1 are densely arranged are provided. May be. However, the light emitting devices 1 are arranged so that the density of the light emitting devices 1 in the direction orthogonal to the arrangement is sparser than the density of the light emitting devices 1 on the array. In addition, the light emitting devices 1 in adjacent rows may be arranged so as to be staggered.

Further, the two-surface width portion 17 as the first emission surface of the light flux controlling member 4 is the same as that of the first embodiment and the second embodiment.
In the embodiment, the flat surfaces 17a and 17b are formed. However, the present invention is not limited to this, and a surface that diverges light may be applied so as to obtain an effect of reducing emitted light toward the arrangement direction. For example, a convex surface having a larger radius of curvature than the curved surface portion 18 as the second exit surface of the light flux controlling member 4 (the divergence effect is lower than that of the plane but higher than that of the rotationally symmetric curved surface portion 18), or a concave surface (divergent than the plane). High effect).

The light emitting device according to the present invention is not limited to being used in a surface light source device, and can be used alone as a guide light, an indirect illumination tool, or the like.

DESCRIPTION OF SYMBOLS 1,32 ... Light-emitting device, 2 ... Board | substrate, 3 ... Light-emitting element (for example, LED), 4 ... Light flux control member, 5 ... Back surface, 7 ... Light incident surface part, 8 ... Top surface, 10 ...... Recess, 11 …… Light reflecting surface portion, 12 …… Light emitting surface portion, 13 …… First light incident surface portion, 14 …… Second light incident surface portion, 1
5a, 15b... Projection, 17... Width across flats, 17a and 17b... Flat surface (first exit surface),
18 …… Curved surface portion (second exit surface), 22 …… Surface light source device, 25 …… Reflecting member, 26 …… Illuminated member, L …… Optical axis (center of luminous flux)

Claims (6)

A light flux controlling member disposed so as to be centered on an optical axis that is a direction in which light at the center of a three-dimensional emitted light flux from the light emitting element travels with respect to the light emitting element,
A light incident surface portion for allowing light from the light emitting element to enter, a light reflecting surface portion for reflecting light incident from the light incident surface portion, and emitting light reflected by the light reflecting surface portion located on a side surface of the light flux controlling member A light emitting surface portion to be
The light incident surface portion is
It is formed on the back side facing the light emitting element of the light flux controlling member,
Arranged to be centered on the optical axis and opposed to the light emitting element,
A first light incident surface portion for entering a first light flux portion that is a central light flux portion located in the vicinity of the optical axis of the emitted light flux;
A light traveling direction of a second light beam portion, which is disposed so as to surround the first light incident surface portion and is positioned so as to surround the first light beam portion of the emitted light beam, is a direction substantially along the optical axis. A second light incident surface portion that changes the optical path so as to be incident on the light flux controlling member, and
The second light incident surface portion is a Fresnel lens composed of a plurality of protrusions formed concentrically around the optical axis;
-The light reflecting surface portion is
A tapered surface that forms a tapered recess recessed from the top surface located on the opposite side of the back surface of the light flux control member toward the back surface, and is formed so as to converge on the optical axis;
The light incident from the light incident surface portion is reflected toward the light emitting surface portion,
-The light exit surface is
A pair of first emission surfaces formed symmetrically with respect to a virtual plane including the optical axis, and a second emission surface connecting the pair of first emission surfaces,
The first emission surface is formed so as to diverge and emit the light reaching via the light reflection surface portion than the second emission surface,
When the direction orthogonal to the optical axis is a side, the light reflected by the light reflecting surface portion is emitted from the first emission surface and the second emission surface toward the side.
A light flux controlling member characterized by the above. The second emission surface is a part of a cylindrical surface centered on the optical axis.
The light flux controlling member according to claim 1. The second emission surface is a tapered surface whose top surface side is smaller in diameter than the back surface side and is a part of a tapered surface centered on the optical axis.
The light flux controlling member according to claim 1. The first emission surface is a pair of planes parallel to the optical axis and a pair of planes symmetrical with respect to a plane including the optical axis.
The light flux controlling member according to any one of claims 1 to 3. A light-emitting element installed on a substrate, and the light flux controlling member according to any one of claims 1 to 4,
  A light emitting device characterized by that. A plurality of the light emitting devices according to claim 5 are arranged in a line, the light emitted from the plurality of light emitting devices is reflected by a reflecting member, the light emitted from the light emitting device and directly reached, and the light reflected by the reflecting member A surface light source device that illuminates the illuminated member in a planar shape,
  The light flux controlling members of the adjacent light emitting devices are arranged such that the first emission surfaces face each other.
  A surface light source device.

Images