JP2011165590A - Light emitting device, surface light source device, display device, and luminous flux control member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a luminous flux control member capable of uniformalizing brightness of illumination light in an illuminated face without increasing the number of light emitting devices when aiming at thinning and light-weight of a surface light source device and a display device equipped with this, and capable of suppressing an increase of power consumption and a hike of a product price. <P>SOLUTION: The luminous flux control member 10 is provided with a light incident part 16 into which light from a light emitting element 6 is made incident, a light emission control part 17 to control emission of light in a prescribed region from an optical axis K of the light emitting element 6 out of the light incident from the light incident part 16, a light re-incidence part 18 to make a total reflection of the directly reached light incident from the light incident part 16 and moreover make re-incident the directly reached light emitted from the light emission control part 17, and a light guide part 20 to emit the light incident from the light incident part 16 and the light re-incident from the light re-incidence part 18 in a process to guide in a direction parting away from the optical axis K of the light emitting element 6. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to a light emitting device using a light emitting element (for example, an LED), a surface light source device and a display device using the light emitting device, and a light flux controlling member that constitutes the light emitting device together with the light emitting element.

(Prior art 1)
Conventionally, as shown in FIG. 10, fluorescent lamps 100a to 100c have been used as light sources,
The light from the fluorescent lamps 100a to 100c is incident on the light guide plates 101a to 101c,
Light emitting devices 103a to 103c are known that emit light from fluorescent lamps 100a to 100c propagating through the light guide plates 101a to 101c in a planar shape from the emission surfaces 102a to 102c of the light guide plates 101a to 101c. . And these light-emitting devices 103a-10
3c is arranged in combination on a reflecting member (not shown), and the plurality of light emitting devices 103a to 103a.
Light control member (diffusing plate, prism sheet, etc.) 104 by the planar light emitted from 03c
There is known a surface light source device 106 configured to illuminate a member to be illuminated (such as a liquid crystal display panel or an advertising panel) 105 from the back side via a light source (see Patent Document 1).

However, the surface light source device 106 disclosed in Patent Document 1 includes each light emitting device 103a.
The shape of the light guide plates 101a to 101c is different from each other (refer to FIGS. 8 and 13 in Patent Document 1), and a plurality of types of light guide plates 101a to 101c having different shapes must be manufactured. It had the problem of being bulky. Further, the surface light source device 106 disclosed in Patent Document 1 includes a plurality of types of light emitting devices 103a to 103c (particularly, light guide plates 101a to 101c).
) In a tandem shape, but a plurality of types of light emitting devices 103a-1
It has been pointed out that the assembly of 03c is difficult and the production man-hours increase.

(Prior art 2)
Further, as shown in FIG. 11A, a plurality of light emitting elements (LEDs) 6 are arranged on the substrate 7,
Light emitted from the plurality of light emitting elements 6 is illuminated via a diffusion plate 11 (not shown)
A surface light source device 110 is known in which a liquid crystal display panel) is irradiated in a planar shape from the back side. A technique similar to this surface light source device 110 is disclosed in Patent Document 2.

The emitted light characteristics of the light emitting element 6 constituting the surface light source device 110 shown in FIG. 11A are as follows. The light axis of the light emitting element 6 is on the diffusion plate 11 arranged at a predetermined distance L from the substrate 7. The steep chevron-shaped luminance distributions C1 to C3 in which the luminance directly above K is the highest are obtained (
(Refer FIG.11 (b)). In FIG. 11B, the luminance ratio is a dimensionless value indicating the relative luminance when the highest luminance on the diffusion plate 11 whose back surface is the irradiated surface 15 is 1.

Even if such a surface light source device 110 illuminates the irradiated surface 15 so that the light from the plurality of light emitting elements 6 is mixed, the position directly above the light emitting elements 6 becomes the brightest, and between the adjacent light emitting elements 6. There was a tendency that the position of was darkest (see luminance distribution C in FIG. 11C). As a result, such a surface light source device 110 is not required to have a uniform surface illumination on the diffuser plate by the illumination light applied to the illumination target member, and an improvement in illumination quality has been demanded.

(Prior art 3)
Conventionally, a surface light source device 120 as shown in FIG. In the surface light source device 120, a light beam control member (lens) 121 is covered on the light emitting element 6 on a one-to-one basis to form a light emitting device 122, and light from the light emitting element 6 is spread by the light beam control member 121 to cover the diffusion plate 11. The irradiation surface 15 is irradiated. A technique similar to such a surface light source device 120 is disclosed in Patent Document 3.

As shown in FIG. 12B, the surface light source device 120 shown in FIG.
The luminance distributions C1 to C3 of the irradiation light for each of the light emitting devices 122 in the above form a mountain-shaped luminance distribution that is gentler than the luminance distributions C1 to C3 of the irradiation light for each of the light emitting elements 6 in FIG. . As a result, when the surface light source device 120 shown in FIG. 12A illuminates the irradiated surface 15 of the diffusion plate 11 so that the light from the plurality of light emitting devices 122 is mixed, the illumination light on the diffusion plate 11 is reflected. The luminance distribution C becomes uniform (see FIG. 12C).

Since the surface light source device 120 according to the conventional technology 3 can share the plurality of light emitting devices 122, the problems of the conventional technology 1 can be solved. In addition, the surface light source device 120 according to the prior art 3 has a problem of the prior art 2 because the light from the plurality of light emitting devices 122 is sufficiently mixed to enable uniform surface illumination. Can be resolved.

JP 2001-312916 A JP 2009-54563 A JP 2009-152142 A

By the way, the surface light source device 120 according to the related art 3 mixes in a state where the light from the adjacent light emitting devices 122 is irradiated on the irradiated surface 15, and each light emitting device is configured to have a planar illumination with uniform luminance. The dimension between 122 (pitch P) and the dimension L from the board | substrate 7 to the diffusion plate 11 are determined (refer Fig.12 (a)).

Therefore, as shown in FIG. 13A, the surface light source device 120 according to the prior art 3 shortens the dimension from the substrate 7 to the diffusion plate 11 (for example, L / 2), thereby reducing the thickness and weight. When trying to illustrate, the luminance distributions C1 to C3 (see FIG. 13B) of the illumination light for each light emitting device 122 on the diffusion plate 11 are the luminance distribution C1 of the illumination light for each light emitting device 122 in FIG. It becomes a mountain shape that is steeper than ~ C3. As a result, the surface light source device 120 shown in FIG.
As shown in (c), the light emitted from the plurality of light emitting devices 122 cannot be sufficiently mixed in the irradiated surface 15, and the luminance of the illumination light on the diffusion plate 11 in the portion directly above the light emitting element 6 is high. On the other hand, the luminance of the illumination light on the diffusion plate 11 between the adjacent light emitting elements 6 is lowered, and the luminance distribution C of the illumination light on the diffusion plate 11 varies.

In order to solve such a problem, the pitch P between the light emitting devices 122 is shortened, and the number of the light emitting devices 122 is increased, so that the light from the adjacent light emitting devices 122 is sufficiently irradiated on the irradiated surface 15. It is also conceivable to obtain planar illumination with uniform brightness.

However, in such a case, not only the luminance of the illumination light on the diffusion plate 11 becomes higher than necessary, but also the number of the light emitting devices 122 increases, the power consumption increases, and the product price increases. Arise.

Therefore, the present invention makes the luminance of the illumination light uniform on the diffusion plate without increasing the number of light emitting devices when the surface light source device and the display device including the surface light source device are reduced in thickness and weight. An object of the present invention is to provide a light flux controlling member capable of suppressing an increase in electric power and suppressing an increase in product price. Another object of the present invention is to provide a light emitting device including such a light flux controlling member, a surface light source device including the light emitting device, and a display device including the surface light source device.

The invention of claim 1 relates to a light emitting device 5 configured to emit light from the light emitting element 6 through a light flux controlling member 10 (see FIGS. 1 to 7). In the present invention, the light flux controlling member 10 includes a light incident part 16 for allowing light from the light emitting element 6 to enter and a predetermined range from the optical axis K of the light emitting element 6 among the light incident from the light incident part 16. The light control emission parts 17 and 30 for controlling the emission of the light inside, and the light incident directly from the light incident part 16 and directly reaching the light are also totally reflected and emitted directly from the light control emission parts 17 and 30 A light re-incident part 18 for re-entering the light, and the light incident from the light incident part 16 and the light re-incident from the light re-incident part 18 are guided in a direction away from the optical axis K of the light emitting element 6. And a light guide unit 20 that emits light in the process. The light incident portion 16 of the light flux controlling member 10 is the light emitting element 6.
In a recess 16 ₁ corresponding one-to-one, a first light incident to the incident by deflecting the light from the light emitting element 6 is located at the bottom of the recess 16 ₁ in the optical axis K side of the light emitting element 6 Surface 16a;
And a, a second light entrance plane 16b to be incident to spread the light from the light emitting element 6 are connected the recess 16 _first open end 22 and the first light incident surface 16a. The first light incident surface 16 a is a surface of a conical protrusion protruding toward the light emitting element 6, and the top 16 c of the protrusion is formed so as to coincide with the optical axis K of the light emitting element 6. Has been. The second
The light incident surface 16b of a cylindrical curved surface located so as to surround the optical axis K of the light emitting element 6, the heading said the first of said open end 22 of the recess 16 ₁ from the light incident surface 16a Therefore, it is formed so that the diameter gradually increases. In addition, the light control emission units 17 and 30 totally reflect the light incident from the first light incident surface 16a and directly reaching after being deflected near the optical axis K of the light emitting element 6, When it is assumed that the totally reflected light is emitted toward the light re-incident part 18 side, and the light flux controlling member 10 is cut along a virtual plane including the optical axis K of the light emitting element 6. The projections 17 ₁ and 30 ₁ having a substantially triangular cross section projecting in the direction opposite to the projecting direction of the first light incident surface 16a are formed.

The invention of claim 2 is characterized by the light control emission part 17 of the light emitting device 5 according to the invention of claim 1 (see FIGS. 4E, 7C, and 7D). In the present invention, when it is assumed that the light control emitting portion 17 is cut along the imaginary plane including the optical axis K of the light emitting element 6, the light control emitting portion 17 is the top portion of the protrusion 17 _{1 having} a substantially triangular cross section. 17 a is formed so as to be located on the optical axis K of the light emitting element 6.

The invention of claim 3 is characterized by the light control emission part 30 of the light emitting device 5 according to the invention of claim 1 (see FIG. 6E). When it is assumed that the light control emitting unit 30 cuts the light flux controlling member 10 along a virtual plane including the optical axis K of the light emitting element 6, the projection 30 ₁ having a substantially triangular cross section is formed on the light emitting element 6. It is formed so as to be symmetrical with respect to the optical axis K.

Invention of Claim 4 is related with the surface light source device 2 provided with the light-emitting device 5 which concerns on any one of Claim 1 thru | or 3 (FIG. 1, FIG. 2, FIG. 5 (a), FIG. 8, FIG. 9 (a)). In the surface light source device 2 according to the present invention, a plurality of light emitting devices 5 are arranged on the substrate 7, and light emitted from the plurality of light emitting devices 5 is emitted in a planar shape via the light control member 4. ing.

A fifth aspect of the present invention is a display device 1 comprising the surface light source device 2 according to the fourth aspect of the present invention, and a member to be illuminated 3 that is illuminated by the planar light emitted from the surface light source device 2. (See FIG. 2).

The invention of claim 6 relates to a light flux controlling member 10 that emits light from the light emitting element 6 (see FIGS. 2, 4, 6, and 7). In the present invention, the light flux controlling member 10 includes a light incident part 16 for making the light from the light emitting element 6 incident and a light incident from the light incident part 16 within a predetermined range from the optical axis K of the light emitting element 6. The light control emission parts 17 and 3 for controlling the emission of light in
0, a light re-incident unit 18 that totally reflects light that has directly entered and reached from the light incident unit 16 and re-enters light that has directly arrived after being emitted from the light control emitting units 17 and 30; A light guide unit 20 that emits light incident from the incident unit 16 and light re-entered from the light re-incidence unit 18 in a process of guiding the light in the direction away from the optical axis K of the light emitting element 6. . The light incident portion 16 of the light flux controlling member 10 has a dent 16 ₁ corresponding to the light emitting element 6 on a one-to-one basis.
A first light incident surface 16a that is positioned at the bottom of the recess 16 ₁ and that allows light from the light emitting element K to be deflected toward the optical axis K of the light emitting element 6 and to enter the recess 16 ₁ . Open end 22
And a first light incident surface 16a, and a second light incident surface 16b that spreads the light from the light emitting element 6 to enter. The first light incident surface 16 a is a surface of a conical protrusion protruding toward the light emitting element 6, and the top 16 c of the protrusion is formed so as to coincide with the optical axis K of the light emitting element 6. Has been. The second light incident surface 16b, the light emitting element 6 is a cylindrical curved surface located so as to surround the optical axis K of the first of the open end 22 of the recess 16 ₁ from the light incident surface 16a It is formed so that the diameter gradually increases as it goes to. In addition, the light control emitting units 17 and 30 totally reflect the light that has directly entered and arrived from the first light incident surface 16a, and emits the totally reflected light toward the light re-incident unit 18 side. When it is assumed that the light-emitting element 6 is cut along a virtual plane including the optical axis K, the cross-section is substantially triangular and protrudes in the direction opposite to the protruding direction of the first light incident surface 16a. The projections 17 ₁ and 30 ₁ are formed.

The present invention spreads the light from the light emitting element over a wide range in the direction away from the optical axis of the light emitting element by the functions of the light incident portion, the light control emitting portion, the light reincident portion, and the light guiding portion of the light flux controlling member. Since the light can be emitted, the brightness of the illumination light on the light control member is made uniform without increasing the number of light emitting devices when the surface light source device and the display device including the surface light source device are reduced in thickness and weight. In addition, the increase in power consumption can be suppressed, and the rise in product price can be suppressed.

It is a figure which shows the display apparatus which concerns on embodiment of this invention, and is a top view (plan view of a surface light source device) of a display apparatus which removes a to-be-illuminated member and a light control member, and shows it. It is sectional drawing which shows the display apparatus which concerns on embodiment of this invention, and is sectional drawing of the display apparatus cut | disconnected and shown along the A1-A1 line | wire of FIG. It is a top view of the board | substrate which shows the state which attached the several light emitting element. It is a figure which shows the light beam control member which concerns on embodiment of this invention. 4A is a plan view of the light flux controlling member, FIG. 4B is a side view of the light flux controlling member, and FIG. 4C is cut along line A2-A2 in FIG. 4A. 4 (d) is a rear view of the light flux control member, and FIG. 4 (e) is an enlarged view of the portion B1 in FIG. 4 (c). It is a partially expanded sectional view. FIG. 5A is a cross-sectional view schematically showing a part of the display device shown in FIG. 2, and FIG. 5B is a light control member (illuminated by light from a single light-emitting device). FIG. 5C is a diagram showing the luminance distribution in a state where light from a plurality of light emitting devices is mixed on the irradiated surface of the light control member. It is a figure which shows the light beam control member which concerns on the modification 1 of this invention. 6 (a) is a plan view of the light flux controlling member, FIG. 6 (b) is a side view of the light flux controlling member, and FIG. 6 (c) is cut along the line A3-A3 in FIG. 6 (a). 6 (d) is a rear view of the light flux controlling member, and FIG. 6 (e) is an enlarged view of the portion B2 in FIG. 6 (c). It is a partially expanded sectional view. It is a figure which shows the light beam control member which concerns on the modification 2 of this invention. 7A is a plan view of the light flux controlling member, FIG. 7B is a side view of the light flux controlling member, and FIG. 7C is cut along line A4-A4 of FIG. 7A. 7D is a cross-sectional view of the light flux controlling member shown by cutting along the line A5-A5 in FIG. 7A, and FIG. It is a reverse view of a light beam control member. It is a figure which shows the display apparatus which uses the light beam control member which concerns on the modification 2 of this invention, and is a top view (plan view of a surface light source device) of a display apparatus which removes a to-be-illuminated member and a light control member, and shows it. FIG. 9A is a schematic cross-sectional view (a cross-sectional view corresponding to FIG. 5A) with a part of the display device shown in FIG. 8 omitted, and FIG. 9B is a single light-emitting device. FIG. 9C is a diagram showing a luminance distribution on a light control member (diffusion plate) illuminated by light from FIG. 9, and FIG. 9C is a diagram in which light from a plurality of light emitting devices is mixed on the irradiated surface of the light control member. It is a figure which shows the luminance distribution of a state. It is a figure which shows the surface light source device of the prior art 1. FIG. 11A is a cross-sectional view schematically showing a part of the display device according to the related art 2, and FIG. 11B shows a light control member (illuminated with light from a single light emitting element). FIG. 11C is a diagram showing the luminance distribution in a state where light from a plurality of light emitting elements is mixed on the irradiated surface of the light control member. FIG. 12A is a cross-sectional view schematically showing a part of the display device according to the related art 3, and FIG. 12B shows a light control member (illuminated by light from a single light emitting device). FIG. 12C is a diagram showing the luminance distribution in a state where light from a plurality of light emitting devices is mixed on the irradiated surface of the light control member. FIG. 13A is a schematic cross-sectional view in the case where the distance between the substrate and the irradiated surface of the display device according to Prior Art 3 is halved, and FIG. 13B is illuminated by light from a single light emitting device. FIG. 13C is a diagram showing the luminance distribution on the light control member (diffusion plate), and FIG. 13C shows the luminance distribution in a state where light from a plurality of light emitting devices is mixed on the irradiated surface of the light control member. FIG.

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

(Light emitting device, surface light source device and display device)
1 and 2 show a display device 1 according to this embodiment and a surface light source device 2 constituting the display device 1. 1 is a plan view of a display device 1 with a member to be illuminated (for example, a liquid crystal display panel, an advertising panel) 3 and a light control member 4 removed (a plan view of the surface light source device 2).
It is. 2 is a cross-sectional view of the display device 1 (a cross-sectional view including the reference optical axis K1 of the light-emitting device 5), and is a cross-sectional view of the display device 1 cut along the line A1-A1 of FIG. It is. Here, the reference optical axis K1 refers to the traveling direction of light at the center of the three-dimensional emitted light beam from the light emitting device 5. In the present embodiment, the reference optical axis K1 of the light emitting device 5 and the light emitting element (for example,
LED) 6 optical axis K (light traveling direction at the center of a three-dimensional outgoing light beam from the light emitting element 6)
A case where and match will be described as an example. Therefore, in the following description, the reference optical axis K1 will be described in other words as the optical axis K. Moreover, in this embodiment, the light emitting element 6 is LE.
It shall include LED sealed by D and the sealing member.

As shown in these drawings, the display device 1 of the present embodiment includes a substrate 7 disposed on the back surface side (lower side in FIG. 2) of the light control member 4 having a square planar shape with a predetermined interval. A plurality of light emitting devices 5 arranged on the substrate 7 at substantially equal intervals (with a pitch P), and the light exit side of the light control member 4 (
And an illuminated member 3 disposed on the surface side opposite to the back surface side of the light control member 4 and on the upper side in FIG. In the present embodiment, the reflective sheet 8 is disposed on the substrate 7 so that the light leaked from the light emitting device 5 is reflected by the reflective sheet 8 to enhance the light use efficiency. Here, in the case where the surface of the substrate 7 exhibits a reflecting function, the reflecting sheet 8 may be omitted.

Moreover, in this embodiment, the light-emitting device 5 is comprised by the light emitting element 6 and the light beam control member 10 arrange | positioned so that it may correspond to this light emitting element 6 on a one-to-one basis.

Moreover, in this embodiment, the board | substrate 7, the light-emitting device 5, and the light control member 4 comprise the surface light source device 2 which illuminates the to-be-illuminated member 3 planarly.

In the present embodiment, the surface light source device 2 and the illuminated member 3 constitute the display device 1.

And the light control member 4 in this embodiment is the diffusion plate 1 located in the light beam control member 10 side.
1 and a first prism sheet 12 placed on the exit surface (upper surface in FIG. 2) side of the diffuser plate 11 and placed on the exit surface (upper surface in FIG. 2) side of the first prism sheet 12 Second
It consists of a prism sheet 13 and a diffusion sheet 14 that is arranged on the emission surface (upper surface in FIG. 2) side of the second prism sheet 13. Among these, the diffusion plate 11 has a function of diffusing and transmitting light from the light emitting device 5. The first prism sheet 12 and the second prism sheet 13 are arranged so that the prism protrusions are orthogonal to each other, and the traveling direction of the light emitted from the diffusion plate 11 is deflected toward the optical axis K of the light emitting element 6. It has a function to do. Further, the diffusion sheet 14 prevents the prism protrusions of the second prism sheet 13 from being damaged,
The light emitted from the second prism sheet 13 is diffused and transmitted.

As shown in FIG. 3, a plurality of light emitting elements 6 (4 rows and 5) are arranged on the substrate 7 at equal intervals (pitch P).
However, the present invention is not limited to this, and a plurality of portions are densely or densely arranged on the substrate 7 and intentionally irradiated surfaces (of the diffusion plate 11 shown in FIG. 2). You may make it change the brightness | luminance of the illumination light irradiated to the lower surface 15.

(Flux control member)
FIG. 4 is a diagram showing the light flux controlling member 10 constituting the display device 1 according to the present embodiment. 4A is a plan view of the light flux controlling member 10, FIG. 4B is a side view of the light flux controlling member 10, and FIG. 4C is an A2-A2 line in FIG. 4A. 4D is a cross-sectional view of the light flux controlling member 10 cut along the line A, FIG. 4D is a back view of the light flux controlling member 10, and FIG. 4E is FIG.
It is a partial expanded sectional view of the light beam control member 10 which expands and shows the B1 part of (c).

As shown in FIG. 4, the light flux controlling member 10 has a substantially disk shape as a whole, and a planar shape thereof is a circular shape. For example, PMMA (polymethyl methacrylate), PC (polycarbonate), EP ( It is made of transparent resin material such as epoxy resin) or transparent glass.

As shown in FIGS. 1 and 2, this light flux controlling member is used in combination with the light emitting element 6 so that the center axis K2 is positioned coaxially with the optical axis K of the light emitting element 6. Is done.

As shown in FIG. 4, the light flux controlling member 10 includes a light incident portion 16 for allowing light from the light emitting element 6 to enter, and an optical axis K of the light emitting element 7 among the light incident from the light incident portion 16. The light control emitting unit 17 that controls the emission of light within a predetermined range from the light, and the light that has directly entered and arrived from the light incident unit 16 is totally reflected and the light that has been emitted from the light control emitting unit 17 and reached directly The light re-incident part 18 to be incident and the light incident from the light incident part 16 and the light incident from the light re-incident part 18 are emitted in the process of guiding the light away from the optical axis K (center axis K2) of the light emitting element 6. Light guide 20
And.

Indentations 16 ₁ functions as a light incident portion 16 of the light flux controlling member 10, the back surface 21 side (
4 (b), (c), and (e), which is formed on the lower surface side facing the light emitting element 6 in FIG. It is made to inject into. The recess 16 ₁ is formed so as to central axis K2 of the light flux controlling member 10, the first light incident surface 16a, and its open end 22 the first light incident surface 16a located at the bottom And a second light incident surface 16b for connecting the two. The diameter of the opening end 22 of the recess 16 ₁ is larger than the diameter of the light emitting element 6. Then, it positioned inside the light emitting surface depressions 16 ₁ of the light-emitting element 6.

The first light incident surface 16 a is a side surface of a substantially conical protrusion that protrudes toward the light emitting element 6 (the lower side in FIG. 4E), and the top 16 c of the protrusion is the center of the light flux controlling member 10. It is formed so as to be positioned on the axis K2, and light with high luminous intensity from the light emitting element 6 is deflected toward the optical axis K of the light emitting element 6 (closer to the central axis K2 of the light flux controlling member 10) to be incident. It is designed to function as a collimating lens. Here, the shape of the protrusion as the light incident portion 16 is substantially conical, not to mention the conical protrusion formed on the side surface where the generatrix is a straight line, but the side surface is convex toward the light emitting element 6 side. This is because a projection having a curved surface or a shape similar to a cone formed with a concave curved surface toward the light emitting element 6 side is included (see FIGS. 2 and 4). In addition,
The light from the light emitting element 6 that has entered the light flux controlling member 10 from the first light incident surface 16 a becomes light within a predetermined range from the optical axis K that is controlled to be emitted by the light control emitting unit 17.

The second light incident surface 16b is a cylindrical curved surface located so as to surround the central axis K2 (optical axis K of the light-emitting element 6), the first open end 22 of the recess 16 ₁ from the light incident surface 16a The curved surface is formed so as to gradually increase in diameter as it goes, and the light from the light emitting element 6 is spread and entered into the light flux controlling member 10 (see FIGS. 2 and 4).

As shown in FIG. 4E, the light control emission part 17 of the light flux controlling member 10 is on the emission surface 23 side (the upper surface side of FIGS. 2, 4B, 4C, and 4E). This is a protrusion 17 ₁ formed at the center of the surface facing the light control member 4, and is a substantially conical protrusion 17 ₁ protruding in a direction opposite to the protruding direction of the first light incident surface. The projection 17 ₁ as the light control emitting portion 17 cuts the light flux controlling member 10 along a virtual plane including the central axis K2 (optical axis K) (cut along the line A2-A2 in FIG. 4A). The cross-sectional shape shown is substantially triangular, and the top portion 17a is formed so as to be located on the central axis K2 (the optical axis K of the light emitting element 6). The protrusion 17 ₁ as the light control emitting portion 17 proceeds along the optical axis K of the light-emitting element 6 out of the light incident from the first light incident surface 16a (substantially parallel to the central axis K2). ) Totally reflects the light that has directly reached the side surface 17b,
The totally reflected light is emitted from the side surface 17b toward the light re-incident part 18 side. Here, the shape of the projection 17 ₁ of the light control emitting portion 17 is made substantially conical. The reason is that the side surface 17b is a convex curved surface as well as the conical projection 17 ₁ formed by the side surface 17b having a straight line. Alternatively, the protrusion 17 ₁ having a shape similar to a cone formed with a concave curved surface is included. The diameter of the lower end 17c of the protrusion 17 ₁ is equal to the diameter of the first light incident surface 16a or larger than the diameter of the first light incident surface 16a.

As shown in FIGS. 4C and 4E, the light re-incidence portion 18 of the light flux controlling member 10 is an inclined surface formed on the exit surface 23 side so as to surround the projection 17 ₁ as the light control exit portion 17. 18a, which is a tapered inclined surface 18a formed so as to expand obliquely upward from the lower end 17c of the protrusion 17 ₁ to the emission surface 23 of the light guide unit 20. The tapered inclined surface 18a has a hollow disk shape with the planar shape centered on the central axis K2 (the optical axis K of the light emitting element 6). The inclined surface 18 a as the light re-incident part 18 totally reflects the light incident directly from the second light incident face 16 b toward the light guide part 20, and is emitted from the light control emitting part 17. Thus, the light that has reached directly is incident again toward the light guide 20 side. 4A and 4E.
), The center axis K2 (the optical axis K of the light emitting element 6) is the center between the inclined surface 18a as the light re-incident part 18 and the projection 17 ₁ as the light control emitting part 17. Annular recess 2
4 is formed.

The light guide portion 20 of the light flux controlling member 10 is positioned so as to surround the light incident portion 16 and the light control emitting portion 17 (see FIGS. 4C and 4E), and the central axis K2 (the optical axis of the light emitting element 6). It is formed in a substantially disc shape centering on K) (see FIGS. 4A and 4D). The light guide 20 of the light flux controlling member 10 is a flat surface formed so that the emission surface 23 is orthogonal to the central axis K2 (the optical axis K of the light emitting element 6) (FIGS. 4B and 4C). (See (e)). Further, as shown in FIG. 4E, the light guide 20 of the light flux controlling member 10 has a rear surface 21 side and a peripheral portion of the recess 16 _{1 at} the exit surface 23.
Is a flat surface 21a that is parallel to the central axis K2 and is inclined so that the portion on the back surface 21 side and surrounding the flat surface 21a is closer to the emission surface 23 as it is away from the central axis K2. The plate thickness is gradually reduced as the distance from the central axis K2 increases. Further, the outer peripheral surface (end surface) 25 of the light guide unit 20 of the light flux controlling member 10 has a surface subjected to diffusion treatment (for example, roughening), and is guided through the light guide unit 20 to reach. It is designed to diffuse light. Thereby, since it can suppress that the light which guided the inside of the light guide part 20 and arrived at the end surface 25 is reflected internally, it guides the inside of the light guide part 20 of the light beam control member 10 again, and the direction of the center axis K The light returned to can be reduced. Also, as shown in FIG.
At least one of the back surface 21 and the output surface 23 of the light guide 20 of the light flux controlling member 10 is formed with an emission promoting means (not shown) that promotes light emission. The light emission promoting means is the light guide unit 20.
These are composed of minute protrusions and minute grooves formed on at least one of the back surface 21 and the emission surface 23, or a combination thereof.

And the light guide part 20 of such a light beam control member 10 guides the light from the light emitting element 6 incident from the second light incident surface 16b in the direction away from the optical axis K, and the light re-incident part 18. The light incident from the inclined surface 18a is guided in a direction away from the optical axis K, and the light is emitted from the emission surface 23 in the light guiding process. Here, when light guided in the direction away from the optical axis K from the light guide 20 is emitted from the emission surface 23 of the light guide 20, most of the emitted light expands around the optical axis K. (See FIG. 5 (a))
.

Further, each surface constituting the light flux controlling member 10 is designed so as to control light emitted from one point where the light emitting surface of the light emitting element 6 and the optical axis K intersect. Therefore, a part of the light emitted from the position away from the optical axis K of the light emitting element 6 out of the light from the light emitting element 6 (the optical axis K of the light emitting element 6).
The light having a lower light intensity than the light having a higher light intensity in the vicinity is emitted also in a region near the optical axis K of the light emitting element 6 (for example, the light control emission unit 17).

As shown in FIGS. 2 and 4, the light flux controlling member 10 is fixed (for example, bonded) on the substrate 7 through a plurality of round bar-like legs 26 formed to protrude from the back surface 21 of the light guide unit 20. The

(Effect of this embodiment)
In the surface light source device 2 configured as described above, each function of the light incident portion 16, the light control emitting portion 17, the light re-incident portion 18 and the light guide portion 20 of the light flux controlling member 10 is exhibited, thereby The luminance distribution (individual luminance distribution of the light emitting device 5) of the light emitted from the light emitting device 5 and irradiating the irradiated surface 15 of the diffusion plate 11 (light control member 4) is shown in FIGS. As shown in FIG. 13, the top portion is flat in a wide range and the whole is a mountain shape close to a gentle isosceles trapezoidal shape.
Compared with the conventional example shown in FIG. 1, the luminance at a position away from the optical axis K of the light emitting element 6 is high, and the decrease in the luminance at a position away from the optical axis K of the light emitting element 6 is also gradual. Moreover, in the surface light source device 2 of the present embodiment, as shown in FIG. 5A, the distance between the substrate 7 and the irradiated surface 15 is L / 2, and between the adjacent light emitting devices 5 and 5. Although the pitch is P and the same as the surface light source device 120 of the conventional example shown in FIG.
5 are mixed to form planar illumination light having substantially uniform luminance on the diffusion plate 11 (FIG. 5 (
c)). In FIG. 5B, the curves C1 to C3 indicate the luminance distribution (light emitting device 5) on the diffusion plate 11 when light from each light emitting device 5 is irradiated on the irradiated surface 15 of the diffusion plate 11.
(Individual luminance distribution), and has the same shape. Further, in FIG. 5C, a line indicated by C is obtained when light from a plurality of light emitting devices 5 (for example, C <b> 1 to C <b> 3) is mixed in the irradiated surface 15 of the diffusion plate 11 and the diffusion plate 11. The luminance distribution on the diffusion plate 11 is shown, and the luminance distribution is almost constant. 5B and 5C, the luminance ratio is the highest luminance of light emitted from the diffusion plate 11 immediately above the light emitting element 6 in the conventional example shown in FIG. The relative luminance when the highest luminance) is 1. Further, in the conventional surface light source device 110 shown in FIG. 11 and the conventional surface light source device 120 shown in FIGS. 12 to 13, the surface light source of this embodiment is included in the same components as the surface light source device 2 of this embodiment. The same reference numerals as those of the device 2 are given.

Therefore, even if the display device 1 using the surface light source device 2 according to the present embodiment is reduced in thickness and weight, the planar light emitted from the light control member 4 and applied to the illuminated member 3 is reduced. The luminance becomes uniform, and the image display quality of the illuminated member 3 is improved.

On the other hand, the surface light source device 120 of the conventional example shown in FIG. 13A cannot sufficiently mix the light emitted from each light emitting device 122 on the irradiated surface 15, and the optical axis of the light emitting element 6. Since the luminance of the illumination light on the diffusion plate 11 in the vicinity immediately above K is increased and the luminance of the illumination light on the diffusion plate 11 between the light emitting devices 122 and 122 is decreased, the luminance distribution of the illumination light on the diffusion plate 11 is reduced. It becomes non-uniform (see FIG. 13C).

As a result, when the display device 1 using the surface light source device 2 according to the present embodiment is reduced in thickness and weight, the brightness of the illumination light on the diffusion plate 11 is increased without increasing the number of the light emitting devices 5. It is possible to equalize, suppress an increase in power consumption, and suppress an increase in product price.

(Modification 1 of the light flux controlling member)
FIG. 6 is a diagram illustrating a first modification of the light flux controlling member 10. Since the light beam control member 10 according to Modification 1 is the same as the light beam control member 10 according to the above embodiment except for the light control emission unit 30, the same structure as the light beam control member 10 according to the above embodiment. The same reference numerals are given to the parts,
The description which overlaps with the said embodiment is abbreviate | omitted. Further, the surface light source device 2 according to the above embodiment will be described with reference to the drawings as appropriate.

As shown in FIG. 6, in the light flux controlling member 10 according to the first modification, a concave portion 31 that is recessed in a substantially inverted conical shape is formed in the central portion on the exit surface 23 side. The concave portion 31 has a substantially inverted conical top portion (deepest portion) 32 positioned on the central axis K2 of the light flux controlling member 10 (the optical axis K of the light emitting element 6), and the substantially inverted conical center line has a luminous flux. The control member 10 is formed to be concentric with the central axis K2. The light flux controlling member 10 is placed around the exit surface 2 around the substantially inverted conical recess 31.
3 side is formed to a substantially triangular projection 30 ₁ comprising an annular when viewed from form a projection on the first light incident surface 16a opposite to the direction of the light incident portion 16 (FIG. 6 (See (e)). The substantially triangular cross section of the projection 30 ₁ is the slope of the recess 31 on the inner circumferential side of the inclined surface 30a is substantially inverted conical shape, slope 30b of the outer peripheral side is a slope of substantially tapered shape and includes a central axis K2 When it is assumed that the light flux controlling member 10 is cut in a virtual plane, the light flux controlling member 10 is formed so as to be positioned symmetrically with respect to the central axis K2. Then, the light flux controlling member projection 30 ₁ of the exit surface 23 side formed substantially triangular cross section 10 functions as light control output unit 30. That is, the slope 30a of the inner peripheral side of the projection 30 ₁ of the light incident from the first light incident surface 16a, totally reflects the light that has directly reached by traveling along the central axis K2 (optical axis K) . The light totally reflected by the inclined surface of the inner peripheral side is to be emitted toward the outer peripheral side of the inclined surface 16b of the projection 30 ₁ to the optical re-incident portion 18 side.

Here, the concave portion 31 on the exit surface 23 side of the light flux controlling member 10 has a substantially inverted conical shape because the side surface as well as the conical concave portion 31 formed by the side surface (slope 30a) having a straight generatrix. This is because it also includes a concave portion 31 having a shape similar to a cone formed by a convex curved surface or a concave curved surface. In addition, the reason why the protrusion 30 ₁ functioning as the light control emitting portion 30 has a substantially triangular cross section is that the generatrix of the inclined surface 30b on the outer peripheral side includes the straight protrusion 30 ₁ as well as the inclined surface 30b on the outer peripheral side.
There is because also include projections 30 ₁ of the convex surface or concave surface.

In the case of injection molding, the light flux controlling member 10 according to Modification Example 1 having such a configuration has a sharp (spherical shape) the deepest portion 32 of the concave portion 31 on the exit surface 23 side for convenience in manufacturing a mold cavity. Therefore, the light from the light emitting element 6 that has entered from the first light incident surface 16a is emitted from the deepest portion 32 of the recess 31 along the central axis K2.
It is difficult to emit the light directly above (see FIG. 2).

On the other hand, when the light flux controlling member 10 according to the above embodiment is injection-molded, the top portion 17a of the projection 17 ₁ as the light control emitting portion 17 is formed in this modification 1 due to the convenience in manufacturing the mold cavity. Compared to the deepest portion 32 of the concave portion 31 of the light flux controlling member 10 according to FIG.

Therefore, the light flux controlling member 10 according to the first modification is the light flux controlling member 10 of the above embodiment.
As compared with the above, it is possible to suppress the amount of light that passes through the light axis 6 along the optical axis K.
The brightness of the illumination light on the diffusing plate 11 can be made more uniform than the light flux controlling member 10 of the above embodiment (see FIG. 2).

(Modification 2 of the light flux controlling member)
FIG. 7 is a diagram illustrating a second modification of the light flux controlling member 10. The light flux controlling member 10 according to the second modified example is different from the light flux controlling member 10 of the above embodiment except for the point that the planar shape is square and the light guide length of the light guide unit 20 is increased. Since it is the same, the same code | symbol is attached | subjected to the component similar to the light beam control member 10 which concerns on the said embodiment, and the description which overlaps with the said embodiment is abbreviate | omitted.

The light flux controlling member 10 according to the second modification example configured as described above has an emission surface 23 of the light guide unit 20.
Is larger than the luminous flux control member 10 according to the above-described embodiment, and the light from the light emitting element 6 can be emitted in a wider range than the luminous flux control member 10 according to the above-described embodiment.

FIG. 8 shows a light emitting device 5 in which the light flux controlling member 10 according to the second modification is used in place of the light flux controlling member 10 according to the above-described embodiment, and the surface light source device 2 and the display device 1 using the light emitting device 5. Is. As shown in FIG. 8, a plurality of luminous flux control members 10 are arranged in a matrix with a slight gap (not shown) with other neighboring luminous flux control members 10 (20 in total in a matrix of 4 rows and 5 columns). It arrange | positions and it arrange | positions so that the to-be-irradiated surface 15 may be divided into 20 equally spaced (refer FIG. 9). Here, a slight gap formed between the adjacent light flux control members 10 and 10 (
(Not shown) is for absorbing the difference in thermal expansion between the light flux controlling member 10 and the substrate 7 (FIG. 9).
(See (a)).

In the surface light source device 2 using the light flux controlling member 10 according to the second modified example having such a configuration, the light from the light emitting element 6 is reliably guided to the intermediate position between the adjacent light emitting elements 6 by the light flux controlling member 10. Therefore (see FIG. 9), the luminance of the illumination light irradiated on the irradiated surface 15 is made more uniform than in the surface light source device 2 of the above-described embodiment (see FIGS. 9B and 9C).

(Other variations)
Note that the light flux controlling member 10 according to the embodiment and the first and second modified examples has a small area of the end faces 25 and 25 ′ to such an extent that it is not necessary to consider the influence of light reflection by the end faces 25 and 25 ′.
You may abbreviate | omit the spreading | diffusion process of the end surfaces 25 and 25 '.

Moreover, although the light beam control member 10 which concerns on the said embodiment and the modification 1 and 2 illustrated the aspect which makes the back surface 21 a taper surface, it is not restricted to this, While making the output surface 23 a taper surface, it is the back surface 21.
May be a plane orthogonal to the central axis K2, and the back surface 21 and the exit surface 23 may be tapered surfaces.

Further, the planar shape of the light flux controlling member 10 is not limited to the circular shape exemplified in the embodiment and the first modification, and the square exemplified in the second modification, but other polygons such as a rectangle and a hexagon, and an elliptical shape. You may form in.

The light emitting device 5 according to the present invention can be used alone as a room lamp or the like instead of a light bulb. The light-emitting device 5 according to the present invention can be widely used as a light source or the like of a surface light source device that illuminates a liquid crystal display device, an advertising board or the like in a planar shape from the back side. Moreover, the light-emitting device 5 which concerns on this invention can be used as an illuminating device which illuminates an advertising board etc. from the surface side.

DESCRIPTION OF SYMBOLS 1 ... Display apparatus, 2 ... Surface light source device, 3 ... Illuminated member, 4 ... Light control member, 5 ... Light-emitting device, 6 ... Light emitting element (for example, LED), 7 ... Board | substrate, 10 ... ... light flux controlling member, 16 ...
... light incident part, 16 ₁ ... depression, 16a ... first light incident surface, 16b ... second light incident surface,
16c: Top, 17: Light control exit, 17 ₁ ... Projection, 17a: Top, 18 ... Light re-incidence, 20 ... Light guide, 30 ... Light control exit, 30 ₁ ... ... protrusions

Claims (6)

In a light emitting device adapted to emit light from a light emitting element via a light flux controlling member,
The light flux controlling member includes a light incident part that allows light from the light emitting element to enter, and light that controls emission of light within a predetermined range from the optical axis of the light emitting element among light incident from the light incident part. From the control light emitting unit, a light re-incidence unit that totally reflects the light incident directly from the light incident unit and that directly reaches the light emitted from the light control output unit, and the light incident unit. A light guide that emits light in the process of guiding incident light and light re-entered from the light re-incident part in a direction away from the optical axis of the light-emitting element, and
The light incident part is a dent corresponding to the light emitting element on a one-to-one basis. The light incident part is positioned at the bottom of the dent and deflects light from the light emitting element near the optical axis of the light emitting element to enter the first light incident part. A light incident surface; and a second light incident surface that connects the opening end of the recess and the first light incident surface to spread light from the light emitting element, and
The first light incident surface is a surface of a conical protrusion protruding toward the light emitting element side, and the top of the protrusion is formed to coincide with the optical axis of the light emitting element.
The second light incident surface is a cylindrical curved surface located so as to surround the optical axis of the light emitting element, and the diameter gradually increases from the first light incident surface toward the opening end of the recess. Is formed to
The light control emitting unit totally reflects light that has been directly incident after being deflected near the optical axis of the light emitting element among the light incident from the first light incident surface, and the totally reflected light is reflected by the light. In the case where it is assumed that the light flux controlling member is cut along a virtual plane including the optical axis of the light emitting element, the projection direction of the first light incident surface is emitted toward the re-incident part side. Formed so as to form a protrusion with a substantially triangular cross section protruding in the opposite direction,
A light emitting device characterized by that. When it is assumed that the light control emission unit cuts the light flux controlling member at a virtual plane including the optical axis of the light emitting element, the top of the protrusion having a substantially triangular cross section is on the optical axis of the light emitting element. Formed to be located,
The light-emitting device according to claim 1. In the light control emitting unit, when it is assumed that the light flux controlling member is cut along a virtual plane including the optical axis of the light emitting element, the protrusion having a substantially triangular cross section is symmetrical with respect to the optical axis of the light emitting element. Formed to be located in the
The light-emitting device according to claim 1. A plurality of light emitting devices according to any one of claims 1 to 3 are arranged on a substrate, and light emitted from the plurality of light emitting devices is emitted in a planar shape via a light control member.
A surface light source device. A surface light source device according to claim 4;
A to-be-illuminated member that is illuminated by the planar emission light emitted from the surface light source device;
A display device comprising: In the light flux controlling member that emits light from the light emitting element,
A light incident part for allowing light from the light emitting element to enter; a light control emitting part for controlling emission of light within a predetermined range from the optical axis of the light emitting element among the light incident from the light incident part; A light re-incidence unit that totally reflects light that has directly entered and arrived from the light incident unit, and that re-enters light that has been directly emitted and reached from the light control emitting unit, and the light incident from the light incident unit and the light A light guide part that emits light re-incident from the re-incident part in a process of guiding the light in a direction away from the optical axis of the light emitting element, and
The light incident part is a dent corresponding to the light emitting element on a one-to-one basis. The light incident part is positioned at the bottom of the dent and deflects light from the light emitting element near the optical axis of the light emitting element to enter the first light incident part. A light incident surface; and a second light incident surface that connects the opening end of the recess and the first light incident surface to spread light from the light emitting element, and
The first light incident surface is a surface of a conical protrusion protruding toward the light emitting element side, and the top of the protrusion is formed to coincide with the optical axis of the light emitting element.
The second light incident surface is a cylindrical curved surface located so as to surround the optical axis of the light emitting element, and the diameter gradually increases from the first light incident surface toward the opening end of the recess. Is formed to
The light control emitting unit is configured to totally reflect the light incident directly from the first light incident surface and to emit the totally reflected light toward the light reincident unit side, When it is assumed that the light-emitting element is cut along a virtual plane including the optical axis, the light-emitting element is formed so as to form a protrusion having a substantially triangular cross section protruding in a direction opposite to the protruding direction of the first light incident surface.
A light flux controlling member characterized by the above.

Images