JP2009099604A - Light control member, light flux control member, light emitting device, and illumination device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light control member, a luminous flux control member, a light-emiting device, and a lighting device, which can obtain a sufficient use efficiency of the light and smoothly collecting the light emitted from a light-emitting element. <P>SOLUTION: The light-emitting device 10 is composed as follows: assuming that a cross-point between an optical axis Z and a light-emitting surface of a light-emitting element 1 is a reference point O, an angle between a line connecting a point on a light entrance face 2a with the reference point O and the optical axis Z is α<SB>1</SB>, and a distance between the point on the light entrance face 2a and the reference point O is R<SB>1</SB>, the R<SB>1</SB>monotonously increases in accordance with an increase in α<SB>1</SB>at least in the range of α<SB>1</SB><π/3; assuming that an angle between a line connecting a point on a light output face 2b with the reference point O and the optical axis Z is α<SB>2</SB>, a distance between a point on the light ouput face 2b and the reference point O is R<SB>2</SB>, the R<SB>2</SB>monotonously increases in accordance with an increase in α<SB>2</SB>at least in the range of α<SB>2</SB><π/3; and assuming that a refractive index of a material of the light control member 2 is n, and a value -ΔR<SB>2</SB>/(R<SB>2</SB>Δα<SB>2</SB>) with the increment ΔR<SB>2</SB>of R<SB>2</SB>to the increment Δα<SB>2</SB>of α<SB>2</SB>divided by R<SB>2</SB>and multiplied by -1 is A<SB>2</SB>, an equation A<SB>2</SB><1/√(n<SP>2</SP>-1) is satisfied. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a light control member, a light beam control member, a light emitting device, and a lighting device including the light emitting device, and includes, for example, a light control member, a light beam control member, a light control member, or a light beam control member that collects light from a light source. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting device that can be used for various types of illumination such as general illumination in a room and a lighting device including the light emitting device.

  2. Description of the Related Art In recent years, an illumination device including a light-emitting device using a light-emitting element such as a light-emitting diode (hereinafter referred to as an LED) as a light source is known as an illumination device used for various types of illumination such as indoor general illumination. As a light emitting device using an LED used for such an illumination device as a light source, for example, the light emitting devices disclosed in Patent Literature 1 and Patent Literature 2 can be given.

  FIG. 8 is a schematic cross-sectional view of a conventional light emitting device 100 disclosed in Patent Document 1. As shown in FIG. The light emitting device 100 includes a light emitting element 101 and a light control member 102 that collects light from the light emitting element 101. The light control member 102 includes a light incident surface 102a on which light from the light emitting element 101 is incident, and a light emitting surface 102b from which light incident on the light incident surface 102a is emitted. The light exit surface 102b is formed on a rotational ellipsoid around the major axis of the ellipse with one end of the major axis of the ellipse as a vertex, and the light control member 102 is arranged so that a straight line including the major axis of the ellipse becomes the optical axis X. is there. The light incident surface 102b has a refractive index of the light control member of n, a focal point, and a polar coordinate whose starting point is a straight line extending from the focal point far from the vertex of the ellipse to the vertex. When the distance between a predetermined point on the optical axis is a,

It has a shape that satisfies At this time, by arranging the light source (light emitting element 101) at a predetermined point, the virtual image of the light source coincides with the focal point, so that the light emitted from the light source is in a direction parallel to the major axis of the ellipse at the light incident surface 102a. Since the light is refracted, the light emitted from the light source can be converted into parallel light.

Next, a schematic cross-sectional view of a conventional light emitting device 110 disclosed in Patent Document 2 is shown in FIG. The light emitting device 110 includes an LED 111 which is a light emitting element, and a reflector main body 112 which is a light control member having a parabolic surface or a reflective surface 112c formed on an approximate curved surface thereof in order to reflect the side light of the LED 111 forward. I have. In the central part of the reflecting surface 112c of the reflector body 112, a recess 112a into which the LED 111 is inserted is formed. In addition, a lens 112b for correcting the traveling direction of the light emitted forward from the LED 111 is provided at the front position of the LED 111 in the recess 112a. Since the light L emitted from the LED 111 in the lateral direction can be reflected by the reflecting surface 112c and emitted from the emitting surface, the light utilization efficiency can be improved.
Japanese Patent Laid-Open No. 4-99074 JP 2003-281909 A

  However, these conventional light emitting devices have the following problems. In the light emitting device 100 of Patent Document 1, light emitted from the LED 101 in a direction other than the angle range of α corresponding to the light incident surface 102a shown in FIG. 8 cannot be condensed because it does not enter the light incident surface 102a. is there. In order to solve this problem, it is conceivable that the LED 101 is brought close to the light control member 102 so that most of the light emitted from the LED 101 can enter the light incident surface 102a, but the reflectance increases. There is a problem. That is, the light emitting device 100 of Patent Document 1 has a problem that sufficient light utilization efficiency cannot be obtained.

  Further, in the light emitting device of Patent Document 2, since the light control member 112 has a complicated shape as shown in FIG. 9, there is a problem that the manufacture is not easy and the cost increases. In addition, when this light emitting device is used for general illumination, the reflector body 112 and the lens 112b of the light control member 112 have different actions, and each action member forms an illuminance distribution separately. Otherwise, there is a problem that the illuminance distribution is not smooth. In order to cope with this problem, a separate measure for smoothing the illuminance distribution is required and the cost increases.

  The present invention has been made to solve the above-described problems, and provides a light control member and a light flux control capable of smoothly collecting light emitted from a light emitting element while obtaining sufficient light use efficiency. It is an object of the present invention to provide a light emitting device having a member, a light control member, or a light flux controlling member, and an illumination device including the light emitting device.

The light-emitting device according to the present invention includes a light-emitting element and a light control member that controls light emitted from the light-emitting element, wherein the light control member controls light emitted from the light-emitting element. A light incident surface that is incident on the member; and a light exit surface from which light incident on the light incident surface is emitted from the light control member, the light incident surface being axially symmetric with respect to a reference optical axis of the light emitting element. A straight line connecting an arbitrary point on the light incident surface and the reference point when the reference point is an intersection of the reference optical axis and the light emitting surface of the light emitting element, and the reference ₁ the angle between the optical axis alpha, the distance between the arbitrary point and the reference point on the light incident surface as R _1, at least α ₁ <π / 3 range, R ₁ with increasing alpha ₁ Increases monotonously, and the light exit surface has a convex curved surface portion that is axisymmetric with respect to the reference optical axis. There, a straight line connecting said reference point and an arbitrary point on the light emitting surface, ₂ the angle between the reference optical axis alpha, a distance between the reference point and an arbitrary point on the light emitting surface As R ₂ , at least in the range of α ₂ <π / 3, R ₂ monotonously decreases as α ₂ increases, suppressing total reflection on the exit surface of the light control member, and suppressing illuminance unevenness on the irradiated surface. It is characterized by that.

  In the present invention, the distance between the point on the light incident surface and the reference point is increased according to an increase in the angle formed between the straight line connecting the point on the light incident surface and the reference point and the reference optical axis. Because it increases monotonically, light is refracted in the direction of approaching the reference optical axis at the light incident surface, and further according to the increase in the angle between the straight line connecting the point of the light exit surface and the reference point and the reference optical axis Thus, since the distance between the point on the light exit surface and the reference point is monotonously decreased, the light is further refracted in the direction of approaching the reference optical axis at the light incident surface. The distance between the light incident surface and the light emitting surface and the reference point is monotonous over an angular range of π / 3 from the reference optical axis, including about 3/4 of the light beam emitted from a general light emitting element. Since the light incident surface and the light output surface are formed so as to increase or monotonously decrease, it is possible to collect light smoothly without causing a sudden change in the illuminance distribution. Further, by appropriately forming the light emitting surface, total reflection on the light emitting surface is suppressed. For this reason, it becomes possible to suppress the cause of uneven illuminance such as light not being emitted from a partial region of the light emitting surface.

A light emitting device according to the present invention includes a light emitting element, a light incident surface on which light emitted from the light emitting element is incident, and a light control member having a light emitting surface from which light incident on the light incident surface is emitted. In the light emitting device, the light control member is formed such that the light incident surface and the light emitting surface have curved portions that are axially symmetric with respect to the optical axis of the light emitting element, and the light incident surface has at least α _In the range of ₁ <π / 3, R ₁ is monotonically increased as α ₁ increases,
However,
α ₁ ; a light-emitting surface of the light-emitting element, a straight line connecting an intersection of the optical axes and a point on the light incident surface, and an angle formed by the optical axis,
R ₁ : Distance between the intersection and a point on the light incident surface The light exit surface has a monotonous decrease in R _{2 as} α ₂ increases in the range of at least α ₂ <π / 3, and the following conditions: Formula (1)

It is formed so that it may satisfy | fill.
However,
α ₂ ; a straight line connecting a light emitting surface of the light emitting element and an intersection of the optical axes and a point on the light emitting surface, and an angle formed by the optical axes,
R ₂ : distance between the intersection and a point on the light exit surface;
n: the refractive index of the material constituting the light control member,
A _2; the increment [Delta] R ₂ of R ₂ with respect to increment [Delta] [alpha] ₂ of the alpha ₂ is divided by R _2, a value multiplied by _{-1 -ΔR 2 / (R 2 Δα} 2)

In the present invention, the distance between the point on the light incident surface and the intersection point increases monotonously as the angle between the straight line connecting the point on the light incident surface and the intersection point and the optical axis increases. Therefore, the light is refracted in the direction of approaching the optical axis at the light incident surface, and further, on the light output surface according to the increase in the angle between the straight line connecting the point of the light output surface and the intersection and the optical axis. Since the distance between the point and the intersection is monotonously decreasing, the light is further refracted in the direction of approaching the optical axis at the light incident surface. The distance between the light incident surface and the light emitting surface and the intersection point monotonically increases over an angle range of π / 3 from the optical axis, including about 3/4 of a light beam emitted from a general light emitting element, or Since the light incident surface and the light output surface are formed so as to monotonously decrease, it is possible to smoothly collect light without causing a sudden change in the illuminance distribution. Moreover, since the light exit surface is formed so that A ₂ satisfies the conditional expression (1), total reflection on the light exit surface is suppressed. For this reason, it becomes possible to suppress the cause of uneven illuminance such as light not being emitted from a partial region of the light emitting surface.

In the light emitting device according to the present invention, when the light control member has α ₁ of 0 on the light incident surface, A ₁ is 0.
However,
A _1; the alpha ₁ increment [Delta] [alpha] ₁ value increment [Delta] R ₁ of R ₁ divided by R ₁ for _{ΔR 1 / (R 1 Δα 1} )
The light emitting surface is configured such that when α ₂ is 0, A ₂ is 0.

  In the present invention, since the light emitted on the optical axis is emitted from the light control member without being bent on the light incident surface and the light emission surface of the light control member, the illuminance unevenness becomes dark on the optical axis. Can be suppressed.

  In the light emitting device according to the present invention, the light control member is made of a translucent material having a refractive index of 1.45 or more and 1.65 or less.

  In the present invention, the shape of the light control member can be easily formed by using a resin such as acrylic or polycarbonate as the translucent material having a refractive index of 1.45 to 1.65. In addition, the cost can be reduced.

  The light emitting device according to the present invention includes a light emitting element, a light incident surface on which light emitted from the light emitting element is incident, and a light control member having a light emitting surface from which light incident on the light incident surface is emitted. In a light emitting device comprising: A in a plane that is spaced apart from the light control member toward the light emission side and orthogonal to the optical axis of the light emitting element, A is the following conditional expression (2):

Is the value obtained by
However,
φ ₁ ; angle P (φ ₁ ) between the light emitted from the light emitting element and the optical axis; conditional expression (3) below the light distribution characteristic of the light emitting element

It is comprised so that it may satisfy | fill.
However,
r; distance C from the optical axis in the plane; constant σ determined so as to satisfy φ ₁ = 0 when r = 0;

  In the present invention, since the light-emitting device is configured to satisfy the conditional expressions (2) and (3), the plane is separated from the light control member toward the light emission side and orthogonal to the optical axis of the light-emitting element. For example, the distribution of light emitted from the light emitting element can be made close to a Gaussian distribution on the floor surface when the light emitting device is installed on the ceiling. For this reason, the illumination nonuniformity which the said light produces on the said plane can be suppressed.

In the light emitting device according to the present invention, when the light distribution characteristic P (φ ₁ ) of the light emitting element is Lambert distribution in the plane, the following conditional expression (4):

It is comprised so that it may satisfy | fill.

  In the present invention, since the light emitting device is configured to satisfy the conditional expression (4), the light emitted from the light emitting element in the Lambertian distribution can be converted into the Gaussian distribution in the plane. Thereby, the light-emitting device which can obtain smooth illuminance distribution using a general light-emitting element can be provided.

In the light emitting device according to the present invention, when the light control member has a refractive index of 1.65 or less and a value Δφ obtained by subtracting φ ₂ from φ ₁ is 13π / 90 or less, the following conditional expression: (5)
1 / 88.5 ≦ θ ₁ / θ ₂ ≦ 88.5 (5)
It is comprised so that it may satisfy | fill.
However,
θ ₁ ; light reaching the light exit point on the light exit surface from which light is emitted from the light entrance point on the light entrance surface where the light from the light emitting element is incident, and at the light entrance point An angle θ ₂ formed with a perpendicular to the light incident surface; an angle φ ₂ formed between light reaching the light emitting point from the light incident point and a perpendicular to the light emitting surface at the light emitting point; Angle between light emitted from a point and the optical axis

In the light emitting device according to the present invention, when the light control member has a refractive index of 1.65 or less and a value Δφ obtained by subtracting φ ₂ from φ ₁ is π / 6 or less, the following conditional expression: (6)
1 / 4.7 ≦ θ ₁ / θ ₂ ≦ 4.7 (6)
It is comprised so that it may satisfy | fill.
However,
θ ₁ ; light reaching the light exit point on the light exit surface from which light is emitted from the light entrance point on the light entrance surface where the light from the light emitting element is incident, and at the light entrance point An angle θ ₂ formed with a perpendicular to the light incident surface; an angle φ ₂ formed between light reaching the light emitting point from the light incident point and a perpendicular to the light emitting surface at the light emitting point; Angle between light emitted from a point and the optical axis

Further, in the light emitting device according to the present invention, when the light control member has a refractive index of 1.65 or less and a value Δφ obtained by subtracting φ ₂ from φ ₁ is 7π / 36 or less, the following conditional expression: (7)
1 / 2.2 ≦ θ ₁ / θ ₂ ≦ 2.2 (7)
It is comprised so that it may satisfy | fill.
However,
θ ₁ ; light reaching the light exit point on the light exit surface from which light is emitted from the light entrance point on the light entrance surface where the light from the light emitting element is incident, and at the light entrance point An angle θ ₂ formed with a perpendicular to the light incident surface; an angle φ ₂ formed between light reaching the light emitting point from the light incident point and a perpendicular to the light emitting surface at the light emitting point; Angle between light emitted from a point and the optical axis

In the light emitting device according to the present invention, when the light control member has a refractive index of 1.65 or less and a value Δφ obtained by subtracting φ ₂ from φ ₁ is 2π / 9 or less, the following conditional expression: (8)
1 / 1.4 ≦ θ ₁ / θ ₂ ≦ 1.4 (8)
It is comprised so that it may satisfy | fill.
However,
θ ₁ ; light reaching the light exit point on the light exit surface from which light is emitted from the light entrance point on the light entrance surface where the light from the light emitting element is incident, and at the light entrance point An angle θ ₂ formed with a perpendicular to the light incident surface; an angle φ ₂ formed between light reaching the light emitting point from the light incident point and a perpendicular to the light emitting surface at the light emitting point; Angle between light emitted from a point and the optical axis

In the light emitting device according to the present invention, when the light control member has a refractive index of 1.65 or less and a value Δφ obtained by subtracting φ ₂ from φ ₁ is 43π / 180 or less, the following conditional expression: (9)
1 / 1.1 ≦ θ ₁ / θ ₂ ≦ 1.1 (9)
It is comprised so that it may satisfy | fill.
However,
θ ₁ ; light reaching the light exit point on the light exit surface from which light is emitted from the light entrance point on the light entrance surface where the light from the light emitting element is incident, and at the light entrance point An angle θ ₂ formed with a perpendicular to the light incident surface; an angle φ ₂ formed between light reaching the light emitting point from the light incident point and a perpendicular to the light emitting surface at the light emitting point; Angle between light emitted from a point and the optical axis

  In the present invention, since the light-emitting device is configured to satisfy any one of the above conditions, the reflectance of light emitted from the light-emitting element can be reduced to 15% or less. Light utilization efficiency can be improved.

  Moreover, the illuminating device which concerns on this invention is equipped with the light-emitting device as described in any one of 1st invention from 11th invention, It is characterized by the above-mentioned.

  According to the present invention, it is possible to provide an illumination device that has reduced reflectivity due to Fresnel reflection and improved condensing performance.

A light control member according to the present invention is a light control member that controls light emitted from a light emitting element, and a light incident surface on which light emitted from the light emitting element enters the light control member; and the light incident surface A light exit surface from which light incident on the light control member is emitted, and the light entrance surface has a concave curved surface portion that is axisymmetric with respect to a reference optical axis of the light emitting element, and the reference optical axis When an intersection point with the light emitting surface of the light emitting element is used as a reference point, an angle formed between a straight line connecting an arbitrary point on the light incident surface and the reference point and the reference optical axis is α ₁ , When the distance between an arbitrary point on the surface and the reference point is R ₁ , at least in the range of α ₁ <π / 3, R ₁ monotonously increases as α ₁ increases. It is a shape having a convex curved surface portion that is axisymmetric with respect to the optical axis, and an arbitrary point on the light exit surface and the reference point A straight line connecting _two an angle between the reference optical axis alpha, a distance between the reference point and an arbitrary point on the light exit surface as R _2, at least in alpha ₂ <[pi / 3 range, alpha _As R ₂ increases, R ₂ decreases monotonously, suppressing total reflection on the exit surface, and reducing illuminance unevenness on the irradiated surface.

  In the present invention, the distance between the point on the light incident surface and the reference point is increased according to an increase in the angle formed between the straight line connecting the point on the light incident surface and the reference point and the reference optical axis. Since the light monotonously increases, when light is incident on the light incident surface, the light is refracted in a direction approaching the reference optical axis at the light incident surface, and a straight line connecting the point of the light emitting surface and the reference point As the distance between the point on the light exit surface and the reference point decreases monotonically with the increase in the angle formed with the reference optical axis, the direction in which the light approaches the reference optical axis further on the light incident surface Will be refracted. The distance between the light incident surface and the light emitting surface and the reference point is monotonous over an angular range of π / 3 from the reference optical axis, including about 3/4 of the light beam emitted from a general light emitting element. Since the light incident surface and the light output surface are formed so as to increase or monotonously decrease, it is possible to collect light smoothly without causing a sudden change in the illuminance distribution. Further, by appropriately forming the light emitting surface, total reflection on the light emitting surface is suppressed. For this reason, it becomes possible to suppress the cause of uneven illuminance such as light not being emitted from a partial region of the light emitting surface.

  A light flux controlling member according to the present invention is characterized in that a plurality of light controlling members according to the thirteenth invention are provided continuously.

  In the present invention, a plurality of light control members are continuously provided. For example, when a plurality of light control members are required as in a lighting device using a plurality of light emitting elements as light sources, light emission is performed. By appropriately forming the light flux controlling member in accordance with the arrangement of the elements, it is not necessary to perform positioning and mounting individually, and it is possible to efficiently assemble the lighting device.

  According to the present invention, it is possible to smoothly collect light emitted from a light emitting element while obtaining sufficient light use efficiency. In addition, it is possible to reduce illuminance unevenness on the irradiated surface.

  Hereinafter, the present invention will be described with reference to the drawings illustrating embodiments thereof. FIG. 1 is a schematic cross-sectional view of a light emitting device 10 according to the present embodiment. The light-emitting device 10 includes a light-emitting element 1 and a light control member 2 that collects light emitted from the light-emitting element 1. The direction of the optical axis (reference optical axis) Z refers to the traveling direction of light at the center of the three-dimensional outgoing light flux of the light emitted from the light emitting element 1. In the figure, for the sake of convenience, the direction vertically upward from the light emitting element 1 is defined as an optical axis (reference optical axis) Z.

  In the drawing, the light emitting element 1 indicated by a rectangle is a member that emits light around the optical axis Z, and has a rotationally symmetric shape around the optical axis Z. The shape of the light emitting element 1 does not have to be a rotationally symmetric shape about the optical axis Z, and may be a rectangular parallelepiped, a polyhedron, or the like. As the light emitting element 1, a well-known LED chip can be used, for example, and it is not specifically limited.

  A light control member 2 is provided on the light emitting surface side of the light emitting element 1. The light control member 2 is a member for changing the direction of the light L emitted from the light emitting element 1, and condenses the light L by bending the light L in a direction nearly parallel to the optical axis Z. The light control member 2 has a curved portion that is axisymmetric with respect to the optical axis Z, a light incident surface 2 a on which the light L emitted from the light emitting element 1 is incident, and a curved portion that is axially symmetric with respect to the optical axis Z. The light emitting surface 2b from which the light L incident on the light incident surface 2a is emitted, and the bottom surface 2c that also serves as a support surface for the light control member that connects the edges of the light incident surface 2a and the light emitting surface 2b. Have. The light emitting element 1 is arranged such that the light emitting surface of the light emitting element 1 is positioned on the plane including the edge of the light incident surface 2a or on the light control member 2 side from the plane.

  As shown in the figure, the cross-sectional shape of the light incident surface 2a of the light control member 2 intersects the optical axis Z substantially perpendicularly on the optical axis Z, and the inclination of the contour line gradually changes from the vicinity of the optical axis Z. It has a shape close to a paraboloid. On the other hand, the cross-sectional shape of the light exit surface 2b of the light control member 2 is such that the inclination of the contour line is substantially perpendicular to the optical axis Z in the vicinity of the optical axis Z and the inclination change is gradually large, and thereafter approaches the vertical direction to the optical axis Z. Accordingly, the change in the inclination of the contour line becomes smaller and gradually changes in a direction parallel to the optical axis Z.

  The light control member 2 used in the present embodiment is, for example, a lens called a meniscus lens (light condensing member) configured from a lens having a convex surface on one side and a concave surface on the other side.

  The light control member 2 is not particularly limited, such as a transparent resin or glass, but a transparent resin having a refractive index of 1.45 or more and 1.65 or less can be preferably used. Specifically, it is a transparent resin material such as polymethyl methacrylate (PMMA) having a refractive index of 1.49, polycarbonate (PC) having a refractive index of 1.59, and epoxy resin (EP). These transparent resin materials can be injection-molded, can be easily manufactured, and can reduce costs.

  Next, a configuration for changing the direction of the light L on the light exit surface 2b of the light control member 2 will be described with reference to FIG. 1 is an enlarged partial sectional view of a part of the light emitting device 10 shown in FIG.

In the figure, the light incident surface 2a is a straight line connecting an arbitrary point P1 on the light incident surface 2a and the reference point O, where the intersection of the optical axis Z and the light emitting surface of the light emitting element ₁ is the reference point O. And the optical axis Z is α ₁ , and the distance between the point P ₁ on the light incident surface 2a and the reference point O is R ₁ , at least in the range of α ₁ <π / 3. _The concave surface is formed such that R ₁ monotonously increases as ₁ increases. When the light emitting characteristics of the light emitting element 1 are a Lambert distribution which is a light distribution characteristic of a general light emitting element, about 3/4 of the light emitted from the light emitting element 1 is included in the range of α ₁ <π / 3. It will be. In this specification, unless otherwise specified, radians are used for angle notation.

Next, the light exit surface 2b has an angle formed between a straight line connecting an arbitrary point P ₂ on the light exit surface 2b and the reference point O and the optical axis Z, α ₂ , and the point P ₂ on the light exit surface 2b. When the distance between the reference point O and the reference point O is R ₂ , at least in the range of α ₂ <π / 3, R ₂ is formed as a convex surface that monotonously decreases as α ₂ increases.

In the light control member 2 formed in this way, the light L incident on the light incident surface 2a is refracted toward the optical axis Z and further refracted toward the optical axis Z when emitted from the light exit surface 2b. The principle is shown below. If the shape of the light incident surface 2a is, alpha ₁ is R ₁ is not changed even increased (increment [Delta] R ₁ in R ₁ in the sectional view of FIG relative increment [Delta] [alpha] ₁ of the alpha ₁ is 0) shape, or reference In the case of a spherical surface having a radius R ₁ centered on the point O, light is incident on the light incident surface perpendicularly, and thus propagates without changing its direction.

On the other hand, when the shape of the light-incoming surface 2a has a shape in which R ₁ increases with increasing alpha _1, i.e., increment [Delta] R ₁ of R ₁ for increment [Delta] [alpha] ₁ of alpha ₁ in a cross-sectional view of the figure [Delta] R _1> 0 In this case, the tangent line at the point P ₁ on the light incident surface 2a becomes an angle closer to the direction perpendicular to the optical axis Z than the tangent line of the circle having the radius R ₁ with the reference point O as the center. The light L emitted from the light and incident at an arbitrary point P ₁ is bent in a direction approaching the optical axis Z and propagates in the light control member 2. At this time, when _{ΔR 1 / R 1 Δα 1 =} A 1, A 1 is the A _1> 0.

Next, R ₂ decreases on the light exit surface 2b as α ₂ increases, so that the tangent at the point P ₂ on the light exit surface 2b is a tangent of a circle with a radius R ₂ centered on the reference point O. The angle becomes closer to an angle parallel to the optical axis Z, and the light incident on the point P ₂ from the direction of the straight line connecting the reference point O and the point P ₂ is further bent in a direction closer to the optical axis Z. Actually, since there is the light incident surface 2a, as shown in the figure, the light actually enters the point P ₂ rather than the angle formed by the straight line connecting the reference point O and the point P ₂ and the normal at the point P ₂ . The angle formed by the light L and the normal line at the point P ₂ is larger, and the light L is bent in a direction approaching the optical axis Z. Thus, by having the light incident surface 2a and the light emitting surface 2b having the above characteristics, a light emitting device with improved light collecting properties can be obtained.

Next, conditions for emitting light from the light emitting surface 2b will be described with reference to FIG. First, consider the light (indicated by a broken line in the figure) incident on the point P ₂ from the direction of the straight line connecting the reference point O and the point P ₂ on the light exit surface 2b.

The angle between the line connecting the normal and the reference point O and the point P ₂ at point P ₂ beta, the amount of change in R ₂ when alpha ₂ is changed by a small amount [Delta] [alpha] ₂ When [Delta] R _2,
tan β = −ΔR ₂ / R ₂ Δα ₂ Next, when the refractive index of the light control member 2 is n, in order for the light incident on the point P ₂ to be emitted from the light emitting surface 2b, it is necessary to satisfy the conditional expression of n sin β ≦ 1. -ΔR ₂ / R ₂ Δα ₂ = A ₂

This is a condition for the light incident on the point P ₂ from the direction of the straight line connecting the reference point O and the point P ₂ on the light emission surface ₂ b to be emitted from the light emission surface 2 b. The above is a condition that holds when the light emitted from the reference point O reaches the light exit surface 2b without being bent at the light entrance surface 2a, but is actually refracted at the light entrance surface 2a. The incident angle of the light L reaching the point P ₂ on 2b is larger than β. for that reason,

Total reflection will always occur under the above conditions. Therefore, at least A ₂ is the following conditional expression (1)

It is necessary to form the light emitting surface 2b so as to satisfy the above.

In the above, portions other than α ₁ = 0 and α ₂ = 0 have been described. When α ₁ = 0 and α ₂ = 0, the light L emitted from the light emitting element 1 in the optical axis Z direction is used as it is. Since it is necessary to emit light in the optical axis Z direction, it is necessary to configure the light control member 2 so that A ₁ and A ₂ are zero.

  Next, based on FIG. 3, a configuration in which the light L emitted from the light emitting element 1 is separated from the light control member 2 toward the light emission side and suppresses uneven illuminance in a plane orthogonal to the optical axis Z will be described. . 1 is an enlarged partial sectional view of a part of the light emitting device 10 shown in FIG.

In FIG. 3, an angle formed between the light L emitted from the light emitting element 1 and reaching the light incident surface 2a and the optical axis Z is φ ₁ . Further parallel, incident on the light incident surface 2a, and reaching the light-outgoing surface 2b, the light L emitted from the light-outgoing surface 2b, the light L is a street light axis Z and emitted point P ₄ that reaches the light-outgoing surface 2b An angle formed with a straight line is φ ₂ .

Further, in the figure, the point at which light L emitted from the light-emitting element 1 enters the light-incoming surface 2a and light incident point P _3, the law in the light L and the light incident point P ₃ which is incident from the light incident point P ₃ The angle made with the line is expressed as θ ₁ . Further, transmitted through the light control member 2, a point on the exit surface of the light L incident on the light-outgoing surface 2b and the light emitting point P _4, the light L and the light emitting point P ₄ which reaches the light emitting point P ₄ The angle formed with the normal to is represented as θ ₂ .

  As shown in the figure, the light L emitted from the light emitting element 1 enters the light incident surface 2a, propagates through the inside of the light control member 2, and then externally (for example, in the air) from the light emitting surface 2b. The light is emitted according to Snell's law. At this time, the light beam from the light emitting element 1 emitted from the light control member 2 according to the present invention is refracted and emitted so as to approach the optical axis Z.

In the light emitting device 10 described above, in order to further improve the light condensing property and suppress the uneven illuminance when the light emitting devices 10 are arranged in a plurality of matrices, the light L emitted from the light emitting element 1 is irradiated on the irradiation surface. It is considered preferable to have a distribution such as a Gaussian distribution that is bright on the optical axis Z of the light-emitting device 10 and darkens as the distance from the optical axis Z increases. Therefore, as a result of intensive studies, the inventors have found that the light L emitted from the light-emitting element 1 having a light distribution characteristic of P (φ ₁ ) has the following conditions.

That is, the distance from the optical axis Z is r and the angle between the light L emitted from the light emitting element 1 and the optical axis Z in a plane that is separated from the light control member 2 on the light emission side and orthogonal to the optical axis Z. Is φ ₁ , A is a value obtained by the above-described equation (2), C is a constant that satisfies φ ₁ = 0 when r = 0, and σ is a constant that represents light condensing property. It has been found that when the conditional expression (3) is satisfied, the light L from the light emitting element 1 whose light distribution characteristic is P (φ ₁ ) can be made Gaussian on a plane, for example, on the floor.

  In this manner, the light emitting device 10 is configured to satisfy the above-described conditions, whereby the light L can be made Gaussian distribution on the floor surface. Thereby, when the light-emitting devices 10 are arranged in a plurality of matrices, unevenness in illuminance of the light L emitted from the light-emitting element 1 can be suppressed.

In particular, a Lambertian distribution represented by P (φ ₁ ) = P ₀ cos φ ₁ (P ₀ is a constant), which is a light distribution characteristic of a general LED, is important, and satisfies the conditional expression (4) described above. The Lambertian distribution can be converted into a Gaussian distribution on the plane (on the floor surface). Thereby, the illuminance unevenness of the light L emitted from the light emitting element 1 when the light emitting devices 10 are arranged in a plurality of matrices can be further suppressed.

FIG. 4 is a graph showing the relationship between θ ₁ / θ ₂ and the reflectance in the light emitting device 10. In the figure, the vertical axis represents the reflectance, and the horizontal axis represents θ ₁ / θ ₂ in logarithmic display. The refractive index used for the calculation is a refractive index of 1.65 that gives the highest reflectance in the range of the refractive index of 1.45 to 1.65. The reflectance includes the reflectance including reflection on both the light incident surface 2a and the light emitting surface 2b. When Δφ = φ ₁ −φ ₂ is constant, the reflectivity is minimized when θ ₁ / θ ₂ = 1, that is, when θ ₁ = θ _2. The greater the Δφ, the greater the reflectivity. I understand that

  On the other hand, in order to improve the light condensing property of the light L by the light control member 2, it is necessary to make the light emitted from the light emitting element 1 as close as possible to the direction perpendicular to the optical axis Z. Therefore, it is necessary to increase Δφ. is there.

  FIG. 5 is a graph showing the relationship between the transmittance of light emitted into the air from a material having a refractive index of 1.65 and the angle of incidence on the exit surface. In the figure, the vertical axis indicates the transmittance, and the horizontal axis indicates the incident angle. As shown in the figure, at an incident angle at which the transmittance due to Fresnel reflection is less than 85%, the transmittance rapidly fluctuates with respect to a minute change in the incident angle. For this reason, there arises a problem that the condensing characteristic varies at an incident angle where the transmittance is less than 85%. Therefore, it is desirable that the transmittance is 85% or more, that is, the reflectance is 15% or less.

The condition for setting the reflectance to 15% or less is expressed by the following conditional expressions (10) to (15), considering the graph shown in FIG.
In Δφ ≦ 5π / 36, 0 ≦ θ ₁ / θ ₂ ≦ ∞ (10)
At Δφ = 13π / 90, 1 / 88.5 ≦ θ ₁ / θ ₂ ≦ 88.5 (11)
At Δφ = π / 6, 1 / 4.7 ≦ θ ₁ / θ ₂ ≦ 4.7 (12)
At Δφ = 7π / 36, 1 / 2.2 ≦ θ ₁ / θ ₂ ≦ 2.2 (13)
At Δφ = 2π / 9, 1 / 1.4 ≦ θ ₁ / θ ₂ ≦ 1.4 (14)
At Δφ = 43π / 180, 1 / 1.1 ≦ θ ₁ / θ ₂ ≦ 1.1 (15)

Further, when Δφ ≧ 11π / 45, the reflectance cannot be made 15% or less. Taking these into account, the following conditional expressions (5) to (9)
In Δφ ≦ 13π / 90, 1 / 88.5 ≦ θ ₁ / θ ₂ ≦ 88.5 (5)
In Δφ ≦ π / 6, 1 / 4.7 ≦ θ ₁ / θ ₂ ≦ 4.7 (6)
In Δφ ≦ 7π / 36, 1 / 2.2 ≦ θ ₁ / θ ₂ ≦ 2.2 (7)
In Δφ ≦ 2π / 9, 1 / 1.4 ≦ θ ₁ / θ ₂ ≦ 1.4 (8)
In Δφ ≦ 43π / 180, 1 / 1.1 ≦ θ ₁ / θ ₂ ≦ 1.1 (9)
By satisfying any of the above, the reflectance can be suppressed to 15% or less, and the utilization efficiency of the light L can be improved as compared with the light emitting device 100 according to the related art.

  In the present embodiment, when the refractive index of the light control member 2 is 1.65 or less, the conditions for suppressing the reflectance to 15% or less and improving the utilization efficiency of the light L are described. However, these conditions are appropriately set in the same procedure according to the selection of the material used for the light control member 2.

  An example of a lighting device including the light-emitting device according to this embodiment is illustrated in FIG. FIG. 6 is an external perspective view of the illumination device 20 including the light emitting device according to the present embodiment, and FIG. 7 is a partial cross-sectional view of the illumination device 20 taken along line VII-VII in FIG.

  In the figure, reference numeral 12 denotes a resin or metal cover. The cover 12 has a rectangular frame portion 12a having a rectangular window, and a rectangular shape 4 extending in one direction substantially orthogonally from the edge of the rectangular frame portion 12a. Side walls 12b, 12b ... are provided. A metal frame 13 is fitted in the cover 12, and the cover 12 and the frame 13 constitute a casing of the lighting device 20.

  As shown in FIG. 7, the frame 13 is provided with a substrate 14, on which a plurality of the light-emitting elements 1, 1. On the light emitting surface side of these light emitting elements 1, 1..., A light collecting sheet (light flux controlling member) 11 integrally formed with a plurality of light control members 2, 2. The axis and the center of the light emitting surface of the light emitting elements 1, 1.

  A plurality of protruding portions 2d, 2d,... Are formed on the bottom surface of the light control members 2, 2,. The substrate 14 on which the light collecting sheet 11 and the light emitting elements 1, 1... Are mounted is fixed to the frame 13 with screws 15, 15. The substrate 14 is pressed against the frame 13 by the protrusions 2d, 2d... And the substrate 14 abuts almost the entire surface of the frame 13, so that the heat generated by the light emitting elements 1, 1. . In addition, even when there is no protrusion part 2d, 2d ..., it is also possible to use the bottom face (refer FIG. 1) of a light control member as a support surface of a light control member.

  Since the illuminating device 20 configured as described above includes the light emitting device 10 according to the present embodiment, the reflectance due to Fresnel reflection can be reduced, and the light utilization efficiency can be improved. Specific examples of the lighting device include lighting devices for general lighting such as base lights and downlights used for room lighting.

  In addition, the light control member and the light emitting device having the light control member can smoothly collect light while suppressing light reflection in the light control member and ensuring light use efficiency, and therefore, the use is limited to general illumination. It is also effective for other uses. For example, it can be suitably applied to a backlight for a liquid crystal display device.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims, and the technical means disclosed in different embodiments can be appropriately combined. Such embodiments are also included in the technical scope of the present invention.

It is typical sectional drawing of the light-emitting device which concerns on this Embodiment. It is the fragmentary sectional view which expanded a part of light-emitting device shown in FIG. It is the fragmentary sectional view which expanded a part of light-emitting device shown in FIG. It is a graph which shows the relationship between (theta) ₁ / (theta) ₂ and the reflectance in the light-emitting device concerning this Embodiment. It is a graph which shows the relationship between the transmittance | permeability of the light radiate | emitted in the air from the material of refractive index 1.65, and the incident angle to an output surface. It is an external appearance perspective view of an illuminating device provided with the light-emitting device which concerns on this Embodiment. It is a fragmentary sectional view of the illuminating device by the VII-VII line of FIG. It is typical sectional drawing of the conventional light-emitting device. It is typical sectional drawing of the conventional light-emitting device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light emitting element 2 Light control member 2a Light incident surface 2b Light output surface 10 Light-emitting device 11 Condensing sheet | seat (light beam control member)
α ₁ angle α ₂ angle Δα ₁ angle Δα ₂ angle O Reference point (intersection)
R ₁ distance R ₂ distance P ₁ entrance point P ₂ exit point Z optical axis

Claims (14)

In a light emitting device including a light emitting element and a light control member that controls light emitted from the light emitting element,
The light control member includes a light incident surface on which light emitted from the light emitting element enters the light control member, and a light emission surface from which light incident on the light incident surface is emitted from the light control member,
The light incident surface has a concave curved surface portion that is axisymmetric with respect to a reference optical axis of the light emitting element,
When an intersection point of the reference optical axis and the light emitting surface of the light emitting element is used as a reference point, an angle formed between a straight line connecting the arbitrary point on the light incident surface and the reference point and the reference optical axis is α ₁ , where R ₁ is a distance between an arbitrary point on the light incident surface and the reference point, at least in the range of α ₁ <π / 3, R ₁ monotonously increases as α ₁ increases,
The light exit surface is a shape having a convex curved surface portion that is axisymmetric with respect to the reference optical axis,
An angle between a straight line connecting an arbitrary point on the light exit surface and the reference point and the reference optical axis is α ₂ , and a distance between the arbitrary point on the light exit surface and the reference point is R _2. At least in the range of α ₂ <π / 3, R ₂ decreases monotonically as α ₂ increases,
A light emitting device characterized in that total reflection is suppressed on the emission surface of the light control member, and uneven illuminance on the irradiation surface is suppressed. In a light emitting device comprising: a light emitting element; and a light control surface having a light incident surface on which light emitted from the light emitting element is incident and a light emitting surface from which light incident on the light incident surface is emitted.
The light control member is formed such that the light incident surface and the light exit surface have curved portions that are axially symmetric with respect to the optical axis of the light emitting element, respectively.
The light incident surface is formed so that R ₁ monotonously increases as α ₁ increases in a range of at least α ₁ <π / 3,
However,

α ₁ ; a light-emitting surface of the light-emitting element, a straight line connecting an intersection of the optical axes and a point on the light incident surface, and an angle formed by the optical axis,
R ₁ : distance between the intersection and a point on the light incident surface

In the light exit surface, at least in the range of α ₂ <π / 3, R ₂ monotonously decreases as α ₂ increases, and the following conditional expression (1)

A light-emitting device formed so as to satisfy the above.
However,
α ₂ ; a straight line connecting a light emitting surface of the light emitting element and an intersection of the optical axes and a point on the light emitting surface, and an angle formed by the optical axes,
R ₂ : distance between the intersection and a point on the light exit surface;
n: the refractive index of the material constituting the light control member,
A _2; the increment [Delta] R ₂ of R ₂ with respect to increment [Delta] [alpha] ₂ of the alpha ₂ is divided by R _2, a value multiplied by _{-1 -ΔR 2 / (R 2 Δα} 2) The light control member has an A ₁ of 0 when α ₁ is 0 on the light incident surface,

However,
A _1; the alpha ₁ increment [Delta] [alpha] ₁ value increment [Delta] R ₁ of R ₁ divided by R ₁ for _{ΔR 1 / (R 1 Δα 1} )

3. The light emitting device according to claim 1, wherein the light emitting surface is configured such that when α ₂ is 0, A ₂ is 0. 4.   The light-emitting device according to claim 1, wherein the light control member is made of a translucent material having a refractive index of 1.45 or more and 1.65 or less. In a light emitting device comprising: a light emitting element; and a light control surface having a light incident surface on which light emitted from the light emitting element is incident and a light emitting surface from which light incident on the light incident surface is emitted.
In a plane that is separated from the light control member to the light emission side and is orthogonal to the optical axis of the light emitting element, A is the following conditional expression (2):

Is the value obtained by

However,
φ ₁ ; angle P (φ ₁ ) between the light emitted from the light emitting element and the optical axis; light distribution characteristics of the light emitting element

The following conditional expression (3)

A light-emitting device configured to satisfy the above.
However,
r; distance C from the optical axis in the plane; constant σ determined to satisfy φ ₁ = 0 when r = 0; In the plane,
When the light distribution characteristic P (φ ₁ ) of the light emitting element is Lambert distribution, the following conditional expression (4)

The light emitting device according to claim 5, wherein the light emitting device is configured to satisfy The light control member has a refractive index of 1.65 or less,
When the value Δφ obtained by subtracting φ ₂ from φ ₁ is 13π / 90 or less, the following conditional expression (5)
1 / 88.5 ≦ θ ₁ / θ ₂ ≦ 88.5 (5)
The light-emitting device according to claim 5, wherein the light-emitting device is configured to satisfy the above.
However,
θ ₁ ; light reaching the light exit point on the light exit surface from which light is emitted from the light entrance point on the light entrance surface where the light from the light emitting element is incident, and at the light entrance point An angle θ ₂ formed with a perpendicular to the light incident surface; an angle φ ₂ formed between light reaching the light emitting point from the light incident point and a perpendicular to the light emitting surface at the light emitting point; Angle between light emitted from a point and the optical axis The light control member has a refractive index of 1.65 or less,
When the value Δφ obtained by subtracting φ ₂ from φ ₁ is π / 6 or less, the following conditional expression (6)
1 / 4.7 ≦ θ ₁ / θ ₂ ≦ 4.7 (6)
The light-emitting device according to claim 5, wherein the light-emitting device is configured to satisfy the above.
However,
θ ₁ ; light reaching the light exit point on the light exit surface from which light is emitted from the light entrance point on the light entrance surface where the light from the light emitting element is incident, and at the light entrance point An angle θ ₂ formed with a perpendicular to the light incident surface; an angle φ ₂ formed between light reaching the light emitting point from the light incident point and a perpendicular to the light emitting surface at the light emitting point; Angle between light emitted from a point and the optical axis The light control member has a refractive index of 1.65 or less,
When the value Δφ obtained by subtracting φ ₂ from φ ₁ is 7π / 36 or less, the following conditional expression (7)
1 / 2.2 ≦ θ ₁ / θ ₂ ≦ 2.2 (7)
The light-emitting device according to claim 5, wherein the light-emitting device is configured to satisfy the above.
However,
θ ₁ ; light reaching the light exit point on the light exit surface from which light is emitted from the light entrance point on the light entrance surface where the light from the light emitting element is incident, and at the light entrance point An angle θ ₂ formed with a perpendicular to the light incident surface; an angle φ ₂ formed between light reaching the light emitting point from the light incident point and a perpendicular to the light emitting surface at the light emitting point; Angle between light emitted from a point and the optical axis The light control member has a refractive index of 1.65 or less,
When the value Δφ obtained by subtracting φ ₂ from φ ₁ is 2π / 9 or less, the following conditional expression (8)
1 / 1.4 ≦ θ ₁ / θ ₂ ≦ 1.4 (8)
The light-emitting device according to claim 5, wherein the light-emitting device is configured to satisfy the above.
However,
θ ₁ ; light reaching the light exit point on the light exit surface from which light is emitted from the light entrance point on the light entrance surface where the light from the light emitting element is incident, and at the light entrance point An angle θ ₂ formed with a perpendicular to the light incident surface; an angle φ ₂ formed between light reaching the light emitting point from the light incident point and a perpendicular to the light emitting surface at the light emitting point; Angle between light emitted from a point and the optical axis The light control member has a refractive index of 1.65 or less,
When a value Δφ obtained by subtracting φ ₂ from φ ₁ is 43π / 180 or less, the following conditional expression (9)
1 / 1.1 ≦ θ ₁ / θ ₂ ≦ 1.1 (9)
The light-emitting device according to claim 5, wherein the light-emitting device is configured to satisfy the above.
However,
θ ₁ ; light reaching the light exit point on the light exit surface from which light is emitted from the light entrance point on the light entrance surface where the light from the light emitting element is incident, and at the light entrance point An angle θ ₂ formed with a perpendicular to the light incident surface; an angle φ ₂ formed between light reaching the light emitting point from the light incident point and a perpendicular to the light emitting surface at the light emitting point; Angle between light emitted from a point and the optical axis   An illumination device comprising the light-emitting device according to claim 1. A light control member for controlling light emitted from the light emitting element,
A light incident surface on which light emitted from the light emitting element is incident on a light control member, and a light emission surface on which light incident on the light incident surface is emitted from the light control member,
The light incident surface has a concave curved surface portion that is axisymmetric with respect to a reference optical axis of the light emitting element,
When an intersection point of the reference optical axis and the light emitting surface of the light emitting element is used as a reference point, an angle formed between a straight line connecting the arbitrary point on the light incident surface and the reference point and the reference optical axis is α ₁ , where R ₁ is a distance between an arbitrary point on the light incident surface and the reference point, at least in the range of α ₁ <π / 3, R ₁ monotonously increases as α ₁ increases,
The light exit surface is a shape having a convex curved surface portion that is axisymmetric with respect to the reference optical axis,
An angle between a straight line connecting an arbitrary point on the light exit surface and the reference point and the reference optical axis is α ₂ , and a distance between the arbitrary point on the light exit surface and the reference point is R _2. At least in the range of α ₂ <π / 3, R ₂ decreases monotonically as α ₂ increases,
A light control member characterized by suppressing total reflection on the exit surface and reducing unevenness in illuminance on the irradiated surface.   A light beam control member comprising a plurality of the light control members according to claim 13 provided continuously.

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