JP2012243396A - Light flux control member, light-emitting device and planar light source device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain emission of light from a light-emitting element toward a direction directly above the light-emitting element through a light flux control member, and to emit the light from the light-emitting element widely toward a side of the light flux control member.SOLUTION: A light-incident surface part 7 of the light flux control member 4 makes the light from the light-emitting element 3 refracted and incident to array nearly in a direction along a light axis L, most of the light incident from the light incident surface part 7 is made totally reflected on a light reflecting surface part 11, and then, the light reflected at the light reflecting surface part 11 can be widely emitted from a light emission surface part 12 to a side of the light flux control member 4. As a result, the light-emitting device 1 can restrain emission of light toward a direction directly above the light-emitting element 3 and the light flux control member 4.

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. 8 is configured such that light from the LED 101 is emitted as illumination light via the optical direction conversion optical element 102. The light direction changing optical element 102 of the light emitting device 100 allows light from the LED 101 to enter the light incident surface 103 to the inside.
A part of the light incident from the light incident surface 103 is reflected by the light reflecting surface 104 to emit a light emitting surface (
Light exit surface 1 out of the light incident from the light incident surface 103.
A part of the light except the light emitted from 04 is emitted from the light reflecting surface 104. A plurality of such light emitting devices 100 are arranged on the back side of an illuminated member (not shown) such as an advertising panel, and illuminate the illuminated member in a planar shape from the back side (Patent Literature). 1)
.

Republished Patent No. WO2008 / 007492 (refer to paragraph number 0028, FIG. 1 and FIG. 8 in particular)

However, since the conventional light emitting device 100 shown in FIG. 8 emits light also from the light reflecting surface 104, a lot of light is emitted directly above the LED 101 and the optical element 102 for changing the light direction. Is done. As a result, the light from the LED 101 is converted into the light direction converting optical element 10.
2, and the light from the LED 101 is converted into an optical element 102 for changing the light direction.
Side (the traveling direction of light at the center of the three-dimensional emitted light beam from the LED 101 is the optical axis L,
When it is necessary to emit light widely in the direction orthogonal to the optical axis L), the conventional light emitting device 10 is used.
0 could not be used.

Accordingly, the present invention provides a light flux controlling member capable of suppressing the light from the light emitting element from being emitted in the direction directly above the light emitting element, and capable of widely emitting the light from the light emitting element to the side, and the light flux. An object of the present invention is to provide a light emitting device using a control member and a surface light source device using the light emitting device.

As shown in FIGS. 1, 5, and 6, the first aspect of the present invention is a light incident surface portion 7 on which light from the light emitting element 3 is incident and a light reflecting surface portion that reflects light incident from the light incident surface portion 7. 11 and a light flux controlling member 4 having a light emitting surface portion 12 that emits light reflected by the light reflecting surface portion 11. In the invention of claim 1,
The light incident surface portion 7 is
The light flux controlling member 4 is formed on the back surface 5 side facing the light emitting element 3,
When the direction in which the light at the center of the three-dimensional emitted light beam from the light emitting element 3 travels is the optical axis L, the light axis is arranged with the optical axis L as the center and is opposed to the light emitting element 3. ,
A first light incident surface portion 13 on which a first light flux portion that is a central light flux portion located in the vicinity of the optical axis L of the emitted light flux is incident;
The light traveling direction of the second light beam portion which is disposed so as to surround the first 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. And a second light incident surface portion 14 that enters the light flux controlling member 4 after changing the optical path so as to be in the same direction. Also,
The light reflecting surface portion 11 is
A tapered surface that forms a tapered recess 10 that is recessed from the top surface 8 of the light flux controlling member 4 facing the back surface 5 toward the back surface 5, and the tapered surface defines the optical axis L. A rotationally symmetric surface around the center,
The light incident from the first light incident surface portion 13 and the second light incident surface portion 14 is totally reflected toward the light emitting surface portion 12. Also,
The light exit surface 12 is
A cylindrical surface connecting the top surface 8 and the back surface 5, the cylindrical surface centered on the optical axis L;
If the direction orthogonal to the optical axis L is the side, the light totally reflected by the light reflecting surface portion 11 is emitted toward the side. And
The second light incident surface portion 14 is a Fresnel lens composed of a plurality of protrusions 15a and 15b formed concentrically with the optical axis L as a center.

As shown in FIGS. 5 and 6, the invention of claim 2 is a light flux controlling member 4 according to the invention of claim 1.
The top surface 8 is roughened so as to diffuse and emit light.

As shown in FIGS. 1, 5 and 6, the invention of claim 3 includes a light emitting element 3 installed on a substrate 2 and a light flux controlling member 4 according to the invention of claim 1 or 2. The light-emitting device 1 is characterized in that the central axis L1 of the light flux controlling member 4 is arranged concentrically with the optical axis L.

The invention of claim 4 is reflected by the light emitting device 1 according to the invention of claim 3, the reflecting member 25 that reflects the light emitted from the light emitting device 1, and the reflecting member 25, as shown in FIG. 7. It is related with the surface light source device 22 characterized by having the to-be-illuminated member 26 illuminated in planar shape with the light.

According to the light flux controlling member of the present invention, it is possible to suppress the light from the light emitting element from being emitted in the direction directly above the light emitting element, and to widely emit the light from the light emitting element to the side.

1 shows a light emitting device according to an embodiment of the present invention. 1A is a side view of the light emitting device 1, FIG. 1B is a plan view of the light emitting device 1, FIG. 1C is a rear view of the light emitting device 1, and FIG. FIG. 2 is a cross-sectional view of the light emitting device 1 cut along the line A1-A1 in FIG. FIG. 2 is an enlarged view of a second light incident surface portion of a light flux controlling member (first example) constituting the light emitting device 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. It is a figure which shows the light distribution characteristic of the light-emitting device shown in FIG. 4A is a diagram corresponding to FIG. 1D, and FIG. 4B is an enlarged view of a part of FIG. 4A (a part of the second light incident surface portion). FIG. 4C is a diagram schematically showing illumination light viewed from the B direction in FIG. FIG. 5A is a plan view showing a second example of the light flux controlling member constituting the light emitting device of the present invention, and FIG. 5B is a partially enlarged view of the light flux controlling member shown in FIG. It is. It is sectional drawing which shows the 3rd example of the light beam control member which comprises the light-emitting device of this invention, and is a figure corresponding to FIG.1 (d). It is a figure which shows the surface light source device using the light-emitting device of this invention. 7A is a plan view of the surface light source device, FIG. 7B is a sectional view taken along line A2-A2 of FIG. 7A, and FIG. 7C is FIG. 7A. It is sectional drawing cut | disconnected and shown along the A3-A3 line | wire. It is a figure which shows the conventional light-emitting device.

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

(Light emitting device)
FIG. 1 shows a light emitting device 1 according to this embodiment. 1A is a side view of the light emitting device 1, FIG. 1B is a plan view of the light emitting device 1, FIG. 1C is a rear view of the light emitting device 1, and FIG. d) Light-emitting device 1 shown by cutting along line A1-A1 in FIG.
FIG.

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.

(First example of light flux controlling 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 so that its planar shape is a circular shape, and its central axis L1 coincides with the centroid of the planar shape. 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 conical light reflecting surface portion 11 that forms a concavity 10 recessed conically from the top surface 8, an outer peripheral edge of the back surface 5, and an outer periphery of the top surface 8 And a light emitting surface portion 12 formed in a substantially cylindrical shape so as to be connected to the end. In addition, the light flux controlling member 4 has four leg portions 6 erected at equal intervals along the circumferential direction 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. Here, the reason why the light traveling direction of the second light flux 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 and the light emitting element 3 Assembling error of 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, so that the light traveling direction of the second light flux portion is from the direction parallel to the optical axis L. (From design value)
This is in consideration of deviation.

As shown in FIG. 1D, the light reflecting surface portion 11 is a conical surface having a tilt angle of 45 ° and an apex angle of 90 ° with respect to the central axis L1 (a rotationally symmetric tapered surface with the central axis L1 as the center). And the apex 16 of the conical surface is formed on the central axis L1. Further, the light reflecting surface portion 11 has a diameter D2 at the end portion on the top surface 8 side that is larger than a 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 D4 at the outer peripheral end of the top surface 8.

The light exit surface 12 has a diameter D4 at the end on the top surface 8 side larger than a diameter D3 at the end on the back surface 5 side in order to facilitate the release of the light flux controlling member 4 from an injection mold (not shown). A draft is added to make it smaller.

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.

(Light distribution characteristics of light-emitting device)
FIG. 3A is a diagram showing the light distribution characteristics of the light emitting device 1 shown in FIG. The light distribution characteristic of the light emitting device 1 shown in FIG. 3A is a position (reference position 0) that is a predetermined distance away from the light emission center 17 of the light emitting element 3 along the optical axis L, as shown in FIG. 3B. °) is arranged at 360 °, and the illuminometer 18 is 360 ° clockwise (+ θ direction) with the light emission center 17 of the light emitting element 3 as the rotation center.
The illuminance is measured by rotating.

As shown in FIG. 3A, according to the light emitting device 1 according to the present embodiment, the side of the light emitting element 3 is compared with the illuminance in the direction directly above the light emitting element 3 (the direction along the optical axis L). The illuminance in the direction (substantially orthogonal to the optical axis L) is about three times larger, the light from the light emitting element 3 can be prevented from being emitted directly above the light flux controlling member 4, and the light from the light emitting element 3 Light is emitted widely to the side of the light flux controlling member 4.

As described above, the light emitting device 1 of the present embodiment changes the optical path so that the light incident surface portion 7 of the light flux controlling member 4 aligns the light from the light emitting element 3 in the direction substantially along the optical axis L, and the light incident Most of the light incident from the surface portion 7 can be totally reflected by the light reflecting surface portion 11, and the light reflected by the light reflecting surface portion 11 can be widely emitted from the light emitting surface portion 12 to the side of the light flux controlling member 4 (FIG. 1). As a result, the light emitting device 1 of the present embodiment can suppress the emission of light in the direction directly above the light emitting element 3 and the light flux controlling member 4 (see FIG. 3).

(Second example of light flux controlling member)
As described above, the first example of the light flux controlling member 4 can suppress the light from the light emitting element 3 from being emitted in the direction directly above the light emitting element 3, and most of the light from the light emitting element 3 is emitted from the light emitting surface portion. 12 when the light leaked from the top surface 8, which is a ring-shaped flat surface, is viewed from above the light flux controlling member 4 (from the direction of the arrow B). It is visually recognized as a ring-shaped light band 20 (see FIG. 4). However, the dimensions are not required. As shown in FIG. 4B, the light incident from the curved surface 21 formed at the tips of the projections 15a and 15b having a substantially triangular cross section constituting the second light incident surface portion 14 (Fresnel lens) is obtained. This is due to emission from the surface 8 or the like. Therefore, in order to prevent the ring-shaped light band 20 from occurring, the tips of the protrusions 15a and 15b constituting the second light incident surface portion 14 (Fresnel lens) are sharpened (the curved surface 21 is not formed). It is effective to eliminate the top surface 8 that is a ring-shaped flat surface, but the top surface is a ring-shaped flat surface without forming the curved surface 21 at the tips of the protrusions 15a and 15b. Eliminating 8 is difficult in manufacturing (injection molding) and handling of the light flux controlling member 4.

Therefore, in the second example of the light flux controlling member shown in FIG. 5, the entire ring-shaped top surface 8 is roughened (roughened with minute irregularities), and light leaking from the ring-shaped top surface 8 is diffused. Further, the generation of the ring-shaped light band 20 can be prevented, and the illumination light can be emitted more uniformly than the first example of the light flux controlling member 4.

(Third example of light flux controlling member)
In the third example of the light flux controlling member 4 shown in FIG. 6, the diameter D 4 ′ on the top surface 8 side is set to the first light flux controlling member 4.
The diameter is larger than the diameter D4 on the top surface 8 side in the example (D4′≈2D4), and the entire top surface 8 is roughened (see FIG. 1D).

The third example of the light flux controlling member 4 can emit illumination light more uniformly than the first and second examples of the light flux controlling member 4 (see FIGS. 1 and 5).

(Surface light source device)
FIG. 7 is a diagram showing a surface light source device 22 using the light emitting device 1 described above. Note that FIG.
) Is a plan view of the surface light source device 22, FIG. 7B is a sectional view of the surface light source device 22 cut along the line A2-A2 of FIG. 7A, and FIG. It is sectional drawing of the surface light source device 22 cut and shown along the A3-A3 line of a).

As shown in FIG. 7, 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 line 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. 7A), and the opening of the housing 23 Illuminated member 2 arranged so as to close
6 (for example, a liquid crystal panel or an advertising panel).

In this surface light source device 22, the reflecting member 25 is formed of 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. A flat surface 25a extending in the X direction with a constant width at the center of the flat surface 25, and a pair of inclined surfaces 25b and 25b that rise 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.

According to such a surface light source device 22, the illumination target member 26 can be illuminated in a planar shape with uniform illumination light by the light emitting device 1 that is smaller than in the conventional example, so that the number of components can be reduced and the weight can be reduced as compared with the conventional example. , Energy saving and product price reduction.

(Modification)
The light exit surface portion 12 of the light flux controlling member 4 shown in FIGS. 1, 5, and 6 is exemplified by a substantially cylindrical surface, but the planar shape is an elliptical shape or a polygonal shape (square, pentagon, hexagon, etc.). It may be a surface. In addition,
The reason for the substantially cylindrical surface is to make it easier to release the light flux controlling member 4 from the injection mold.
This is because it is considered that the light exit surface portion 12 of the light flux controlling member 4 is not a complete cylindrical surface by providing a draft gradient. The light reflecting portion surface portion 11 is not limited to the conical concave portion, and may be an aspheric tapered surface designed so that the light incident from the light incident surface portion 7 can be totally reflected sideways.

The light-emitting device 1 according to the present invention is not limited to being used for the surface light source device 22, and can be used alone as a guide light, an indirect illumination tool, or the like.

DESCRIPTION OF SYMBOLS 1 ... 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,
12... Light exit surface portion, 13... First light incident surface portion, 14.
Vertex 22... Surface light source device 25. Reflecting member 26. Illuminated member L L. Optical axis (center of light flux) L 1.

Claims (4)

A light incident surface portion on which light from the light emitting element is incident;
A light reflecting surface portion that reflects light incident from the light incident surface portion;
A light exit surface that emits light reflected by the light reflector surface; and
A light flux controlling member having
The light incident surface portion is
The light beam control member is formed on the back side facing the light emitting element, and the optical axis is the direction in which the light at the center of the three-dimensional outgoing light beam from the light emitting element travels. Arranged so as to be centered 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 direction in which the light traveling direction of the 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 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 light reflecting surface portion is
A tapered surface that forms a tapered recess that is recessed from the top surface facing the back surface of the light flux controlling member toward the back surface, the tapered surface being a rotationally symmetric surface about the optical axis And
The light incident from the first light incident surface portion and the second light incident surface portion is totally reflected toward the light emitting surface portion;
The light exit surface portion is
A cylindrical surface connecting the top surface and the back surface, the cylindrical surface centered on the optical axis;
-When the direction orthogonal to the optical axis is the side, the light totally reflected by the light reflecting surface portion is emitted toward the side,
The second light incident surface portion is a Fresnel lens including a plurality of protrusions formed concentrically around the optical axis.
A light flux controlling member characterized by the above. The top surface is roughened to diffuse and emit light;
The light flux controlling member according to claim 1. A light emitting element installed on a substrate, and the light flux controlling member according to claim 1 or 2,
The central axis of the light flux controlling member is arranged concentrically with the optical axis,
A light emitting device characterized by that. The light-emitting device according to claim 3, a reflecting member that reflects light emitted from the light-emitting device, and an illuminated member that is illuminated in a planar shape by the light reflected by the reflecting member. A characteristic surface light source device.

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