JP2012145829A - Light-emitting device and luminaire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase an amount of light in surface and lateral directions, ensure a front luminance, and enhance diffusibility of light.SOLUTION: An inventive light-emitting device includes a light source and a light flux control part for controlling light emitted from the light source. The light flux control part has a light incident surface and a light emission surface. In a plane perpendicular to the optical axis of the light emitted from the light source, a region 30, where the light beam density of the light emitted from the light emission surface becomes higher as a distance from the optical axis as an origin increases, exists, and also in the above-described plane, a region 31, where the light beam density becomes lower as a distance from the point located far from the optical axis as an origin increases, exists at least in one place.

Description

  The present invention relates to a light emitting device that controls light emitted from a light source by a light flux controlling member, and an illumination device including the light emitting device.

  2. Description of the Related Art Conventionally, some illumination devices (for example, a liquid crystal backlight and a signboard illumination) include a light emitting device that realizes uniform light distribution by covering a light source with a light beam control member. In this light emitting device, the light emitted from the LED light source is spread to the light emitting surface side by the light flux controlling member. By uniformly arranging the light emitting device in the lighting device, light is illuminated on the front panel of the lighting device without uneven brightness.

  As a light emitting device using such an LED as a light source, for example, the light emitting device 100 disclosed in Patent Document 1 can be cited. FIG. 11 is a cross-sectional view of a conventional light emitting device 100.

  In the light emitting device 100, the light H from the light emitting element 101 is emitted to the irradiated surface 107 through the light flux controlling member 102. The light flux controlling member 102 includes a light emitting surface 106 that restricts the light emitting direction only on the irradiated surface 107 side.

  The light emitting surface 106 transmits the light H that has entered the light incident surface 103 from the light emitting element 101 and has reached the light emitting surface 106 without being reflected by other parts through the light flux controlling member 102. The light is emitted toward the irradiated surface 107 so as not to intersect after the emission.

  Further, the light density of the light emitted from the light emitting surface 106 in the light emitting device 100 is sparser than the other parts in the vicinity of the optical axis Z, and gradually becomes denser as the distance from the optical axis Z increases.

  Examples of other light emitting devices using LEDs as light sources include the light emitting devices disclosed in Patent Document 2 and Patent Document 3.

  A recess is formed at a position corresponding to the LED on the back side of the light flux controlling member in the light emitting device of Patent Document 2. By forming this dent shape only on the back surface side, the emitted light beam density near the optical axis Z is sparser than the other parts, and the light beam density gradually becomes denser as the distance from the optical axis increases.

  A hemispherical recess is formed at a position corresponding to the light emitting element on the back side of the light flux controlling member in the light emitting device of Patent Document 3. In addition, the predetermined range centered on the optical axis on the surface side of the light flux controlling member has a smooth curved surface that is convex downward, and the range that is away from the optical axis is an upward convex that is continuously formed. It has a smooth curved surface shape. Thus, the light distribution is controlled by making both the back side and the front side have curved surfaces.

  Currently, there is a demand for illuminating all surfaces other than the back surface of the illumination device in illumination devices (for example, signboard illumination and indicator lights). Therefore, a light-emitting device that secures the front luminance of the lighting device and improves the light diffusibility is desired. In order to ensure the front luminance, it is necessary to ensure a sufficient amount of light in the direction of the reference optical axis, and in order to improve the light diffusibility, it is necessary to widen the light distribution.

JP 2007-294187 A (released on November 8, 2007) JP 2007-115708 (May 10, 2007) JP 2007-227410 A (published September 6, 2007)

  However, the conventional light emitting devices have the following problems.

  In the light emitting device of Patent Document 1, the light quantity in the reference optical axis direction is sufficient and the front luminance is ensured, but the light distribution is narrow and the emission angle ± 60 in the lateral direction (perpendicular to the optical axis Z). No light is emitted from ° to ± 90 °. Therefore, light cannot be diffused and a surface other than the front surface of the illuminating device cannot be illuminated (see the dashed line 82 in FIG. 8B).

  In the light emitting device of Patent Document 2, light distribution is wide, light is emitted sufficiently in the lateral direction, and light is diffused. However, the amount of light in the direction of the reference optical axis is insufficient, and the front luminance is not ensured (see the broken line 83 in FIG. 8B).

  Also in the light emitting device of Patent Document 3, light distribution is wide, light is sufficiently emitted in the lateral direction, and light is diffused. However, the amount of light in the direction of the reference optical axis is insufficient, and the front luminance is not ensured (see the dotted line 84 in FIG. 8B).

  The light density in the conventional light emitting device is gradually increased as the distance from the optical axis Z increases.

  In such a conventional light emitting device, the light distribution becomes narrower when it is attempted to secure the front luminance by increasing the amount of light in the direction of the reference optical axis. Therefore, the light diffusibility in the lateral direction is reduced.

  Further, if the light distribution is expanded in the lateral direction to improve the light diffusibility, the amount of light in the reference optical axis direction is sacrificed. Therefore, the front luminance cannot be ensured.

  As described above, in the conventional light emitting device, it is impossible to simultaneously increase the amount of light in the front direction and the lateral direction to secure front luminance and improve light diffusibility.

In order to solve the above problems, a light-emitting device according to the present invention provides
A light emitting device comprising a light source and a light flux controlling member that controls light emitted from the light source,
The light flux controlling member has a light incident surface and a light exit surface,
In a plane orthogonal to the optical axis of the light emitted from the light source, the light density of the light emitted from the light emitting surface becomes denser as the distance from the optical axis increases from the optical axis as a base point. There is an area,
In the plane, there is at least one region in which the light density becomes more sparse as the distance from the optical axis becomes a base point away from the optical axis.

  According to said structure, the light radiate | emitted from the light source injects from the incident surface of a light speed control member, propagates the inside of a light speed control member, and is radiate | emitted from the output surface. Thereby, the light from the light source is controlled by the light speed control member.

  Here, in the light emitting device of the present invention, as the light beam density of the light emitted from the light emitting surface is away from the optical axis with the optical axis as a base point in a plane orthogonal to the optical axis of the light emitted from the light source. There are areas that are becoming denser. Along with this, there is at least one region in the plane in which the light density becomes more sparse as the distance from the optical axis becomes a base point away from the optical axis. Here, in the former area, the light density on the light source side is sparser. On the other hand, in the latter region, the light density away from the light source is sparser. As a result, in the entire region of the light emitting surface, a region where the light density is sparse is formed both at the vicinity of the optical axis and at a position away from the optical axis. As a result, the amount of light in the direction of the optical axis (that is, the front direction) can be secured and the orientation can be expanded.

In the light emitting device according to the present invention,
It is preferable that the region in which the light density becomes more sparse is at a position where the angle formed by the optical axis and the light emitted from the light source is 65 ° or less.

  According to the above configuration, the light quantity in the front direction and the lateral direction can be reduced by providing a region where the light beam becomes sparser at a position where the angle between the optical axis and the light emitted from the light source is 65 ° or less. At the same time, the front luminance can be ensured and the light diffusibility can be improved.

In the light emitting device according to the present invention,
The illuminance distribution on the diffusion surface of the light emitted from the light exit surface is I, A is a magnification (an arbitrary rational number greater than 0 and less than 1), r is the distance from the optical axis, and σ1 and σ1 are respectively When the dispersion has a different Gaussian distribution, the light flux controlling member has the following formula (1):

It is preferable to have a shape satisfying

  According to said structure, the secondary peak of light quantity arises in light distribution, and there exists an effect of extending light distribution to a horizontal direction, ensuring the light quantity of an optical axis direction.

In the light emitting device according to the present invention,
The light flux controlling member further includes a bottom surface connecting the light incident surface and the light emitting surface,
The light emitting device is reflected on the light emitting surface at a position where the light emitted from the light source on the bottom surface, enters the light flux controlling member from the light incident surface, and is reflected on the light emitting surface. It is preferable to further include a light transmission part that transmits the transmitted light.

  According to said structure, the Fresnel reflection component which refracts | refracts so that the light reflected in the light-projection surface may approach an optical axis again from a light-projection surface can be suppressed. Thereby, it is possible to make it difficult to cause uneven brightness of the irradiated light.

  In order to solve the above-described problems, an illumination device according to the present invention includes any one of the light-emitting devices described above.

  According to said structure, the illuminating device which can make the ensuring of front brightness and the improvement of the diffusibility of light compatible is realizable.

  The light emitting device according to the present invention has an effect that it is possible to achieve both the front luminance and the improvement of light diffusibility.

(A) is sectional drawing which shows the structure of the light-emitting device which concerns on one Embodiment of this invention, (b) is a figure which shows the path | route of the light radiate | emitted from the light source in detail. (A) is a graph showing the relationship between θ1 and θ2 in the light emitting device, (b) is a graph showing the relationship between θ1 and θ2 / θ1 in the light emitting device, and (c) is in the light emitting device. It is a graph which shows the relationship of the increase amount of (theta) 1 and (theta) 2. FIG. It is a figure which shows the light ray of the light radiate | emitted from the light-projection surface in a light-emitting device. (A) is sectional drawing of the light-emitting device which concerns on other embodiment of this invention, (b) is sectional drawing of the light-emitting device which concerns on other embodiment which concerns on this invention. It is sectional drawing which shows the light-emitting device which does not have a light transmissive part. It is sectional drawing of the light-emitting device which has a light transmissive part. It is a graph which shows the illuminance distribution on the diffusion plate at the time of arrange | positioning the light-emitting device which has a light transmissive part, and the illuminance distribution on the diffusion plate at the time of arrange | positioning the light-emitting device which does not have a light transmissive part. (A) is a graph which shows the relationship of the increase amount of (theta) 1 and (theta) 2 in the conventional light-emitting device, (b) is a graph which shows the relationship between the light quantity and light distribution in the conventional light-emitting device. It is a graph which shows the difference in the light distribution of the conventional light-emitting device and the light-emitting device of this invention. It is a graph which shows the difference between the increase amount of (theta) 2 accompanying the increase in (theta) 1 in the conventional light-emitting device, and the increase amount of (theta) 2 accompanying the increase in (theta) 1 in the light-emitting device of this invention. It is sectional drawing of the conventional light-emitting device.

[Embodiment 1]
An embodiment of the present invention will be described below with reference to FIGS. 1 to 4, 9, and 10.

(Configuration of Light Emitting Device 10)
Fig.1 (a) is sectional drawing of the light-emitting device 10 which concerns on embodiment of this invention. The light emitting device 10 shown in the figure includes a light emitting element 1 and a light flux controlling member 2. In the light emitting device 10, the light flux controlling member 2 is disposed so as to cover the periphery of the light emitting element 1.

  The light emitting device 10 has a rotationally symmetric shape about the optical axis Z. The direction of the optical axis Z is the traveling direction of light at the center of the three-dimensional outgoing light beam of the light emitted from the light emitting element 1. In the figure, for the sake of convenience, the direction upward from the light emitting element 1 is defined as an optical axis Z.

(Light emitting element 1)
The light emitting element 1 is a member that emits light around the optical axis Z. A known LED chip or the like can be used as the light emitting element 1. However, the configuration is not particularly limited. The shape of the light emitting element 1 may be rotationally symmetric as in the light emitting device 10, or may be a rectangular parallelepiped instead of rotationally symmetric.

(Flux control member 2)
FIG. 1B is an explanatory diagram for explaining the light L, θ1, and θ2 emitted from the light emitting element 1 in the light emitting device 10. As shown in this figure, the light flux controlling member 2 is a member that diffuses the light L emitted from the light emitting element 1. The light flux controlling member 2 has a light incident surface 2a, a light emitting surface 2b, and a bottom surface 2c. The light incident surface 2 a is a surface on which the light L emitted from the light emitting device 10 enters the light flux controlling member 2. The light emitting surface 2b is a surface from which the light L emitted from the light emitting device 10 and incident from the light incident surface 2a is emitted. The bottom surface 2c is a surface connecting the light incident surface 2a and the light emitting surface 2b.

  The cross section of the light incident surface 2a has a bell shape. On the other hand, the cross-sectional shape of the light exit surface 2b has a shape close to a semicircle. That is, the contour line of the cross section of the light incident surface 2a intersects the optical axis Z substantially perpendicularly to the optical axis Z as shown in FIG. In the place away from the optical axis Z, the inclination does not change much. On the other hand, as shown in FIG. 1B, the contour line of the cross section of the light exit surface 2b intersects the optical axis Z substantially perpendicularly on the optical axis Z, and its inclination gradually decreases as the distance from the optical axis Z increases. And gradually change in a direction parallel to the optical axis Z.

  By having such a shape, the light flux controlling member 2 diffuses the light L by bending the light L emitted from the light emitting element 1 in a direction close to perpendicular to the optical axis Z. The light L emitted from the light emitting element 1 is incident on the light incident surface 2a, propagates through the light flux controlling member 2, and then is emitted from the light emitting surface 2b to the outside according to Snell's law. At this time, the light from the light emitting element 1 emitted from the light flux controlling member 2 is refracted and emitted away from the optical axis Z.

(Shape of the light flux controlling member 2)
It is desirable that the light flux controlling member 2 has a shape that satisfies the following expression (1).

Here, in Expression (1), I represents the illuminance distribution on the diffusion surface of the light emitted from the light emitting surface 2b. A indicates a magnification (an arbitrary rational number greater than 0 and less than 1). r represents the distance from the optical axis Z. σ ₁ and σ ₂ indicate different variances of the Gaussian distribution. Therefore, I is an illuminance distribution obtained by adding two Gaussian distributions having different dispersion values to the illuminance distribution on the diffusion surface. By forming the light flux controlling member 2 in such a shape that satisfies such conditions, a secondary peak of the light amount is further generated in the light distribution, and the effect of spreading the light distribution in the lateral direction while ensuring the light amount in the optical axis direction is achieved. Play. The light flux controlling member 2 shown in FIG. 1 satisfies the above formula (1).

  The light flux controlling member 2 only needs to be formed of a translucent material. For example, polymethyl methacrylate or polycarbonate can be used as the material.

(Relationship between θ1 and θ2)
As shown in FIG. 1B, a point where the light L emitted from the light emitting element 1 reaches the light incident surface 2a is defined as an incident point P1, and an angle formed between the light L and the optical axis Z is defined as θ1. Further, a point where the light L propagating through the light flux controlling member 2 reaches the light exit surface 2b is defined as an exit point P2, and the light L emitted from the light exit surface 2b is formed by a line passing through P2 and parallel to the optical axis Z. The angle is θ2.

  FIG. 2A is a graph showing the relationship between θ1 and θ2 in the light emitting device 10. In the figure, the vertical axis represents θ2 and the horizontal axis represents θ1. As indicated by a thick line 20 in the figure, θ2 monotonously increases with an increase in θ1.

  FIG. 2B is a graph showing the relationship between θ1 and θ2 / θ1 in the light emitting device 10. In the figure, the vertical axis represents θ2 / θ1, and the horizontal axis represents θ1. As shown by the solid line 21 in the figure, θ2 / θ1 decreases as θ1 increases. Further, as shown in FIG. 2A, θ2> θ1 is always satisfied except in the vicinity of the direction parallel to the optical axis Z. Therefore, as shown by the solid line 21, θ2 / θ1> 1 is always satisfied.

  FIG. 2C is a graph showing the relationship between the increase amounts of θ1 and θ2 in the light emitting device 10. In the figure, the vertical axis indicates the amount of increase in θ2, and the horizontal axis indicates θ1. Here, the amount of increase of θ2 is the amount of increase in θ2 as θ1 increases. As shown by the solid line 22 in the figure, when θ1 ≦ 45 ° and θ1 ≧ 55 °, the increase amount of θ2 monotonously decreases as θ1 increases. However, the increase amount of θ2 temporarily increases when 45 ° ≦ θ1 ≦ 55 °. The angle of θ1 at which the increase amount of θ2 temporarily increases is not particularly limited as long as θ1 ≦ 65 °.

(Ray diagram)
FIG. 3 is a diagram illustrating light rays emitted from the light emission surface 2 b of the light emitting device 10. In the figure, light rays are drawn from the position of the light emitting element 1 in increments of 1 °. It can be seen that the light density in the vicinity of θ2 = 70 ° to 75 ° is sparse by temporarily increasing the increase amount of θ2 in the vicinity of θ1 = 45 ° to 55 °.

  More specifically, in the light emitting device 10, as shown in FIG. 3, the light beam density of the light emitted from the light emitting surface 2 b is within the plane perpendicular to the optical axis of the light emitted from the light source 1. There is a region 30 that becomes denser with increasing distance from the optical axis Z with the axis Z as a base point. Along with this, in the plane, there is a region 31 in which the light density becomes sparser as the distance from the optical axis Z increases from the point away from the optical axis Z. Here, in the region 30, the light density on the light source 1 side is sparser. On the other hand, in the region 31, the light density on the side away from the light source 1 is sparser. As a result, in the entire region of the light exit surface 2b (that is, 0 ° ≦ θ2 ≦ 90 °), a region where the light density is sparse is formed both near the optical axis Z and at a position away from the optical axis Z. Is done. As a result, the amount of light in the direction of the optical axis Z (that is, the front direction) can be secured and the orientation can be expanded.

  The region 31 is not necessarily limited to one location, and may be at least one location in the light emitting device 10. That is, there may be a plurality of regions 31.

(Relationship between light intensity and light distribution)
FIG. 8A is a graph showing the relationship between θ1 and θ2 increase in a conventional light emitting device. In the figure, a dashed line 80 indicates the relationship between the amount of increase in θ1 and θ2 in the conventional first light emitting device. On the other hand, a broken line 81 indicates the relationship between θ1 and θ2 increase in the conventional second light emitting device. As shown in FIG. 8A, in the conventional first and second light emitting devices, the amount of increase of θ2 is constantly decreasing with the increase of θ1. That is, the increase amount of θ2 monotonously decreases over the entire range of θ1.

  FIG. 8B is a graph showing the relationship between the light amount and the light distribution in the conventional light emitting device. The horizontal axis of the figure indicates the emission angle of the light emitted from the light exit surface 2b. On the other hand, the vertical axis indicates the relative amount of light emitted from the light exit surface 2b.

  In FIG. 8B, a dashed line 82 indicates the relationship between the light amount and the light distribution in the conventional first light emitting device. A broken line 83 indicates the relationship between the light amount and the light distribution in the conventional second light emitting device. A dotted line 84 indicates the relationship between the light amount and the light distribution in the conventional third light emitting device.

  In the first conventional light emitting device, the relationship between the increase amount of θ1 and θ2 is as shown by a one-dot broken line 80 in FIG. That is, θ2 near the optical axis Z is smaller than that of the conventional second light emitting device. Thereby, as shown by the one-dot broken line 82 in FIG. 8B, the front luminance is sufficiently increased. On the other hand, no light is emitted in the lateral direction.

  In the conventional second light emitting device, the relationship between θ1 and the increase in θ2 is as shown by a broken line 81 in FIG. That is, θ2 near the optical axis Z is larger than that of the conventional first light emitting device. Thereby, as indicated by a broken line 83 in FIG. 8B, a large amount of light is emitted in the lateral direction. On the other hand, not much light is emitted to the front, and as a result, the front luminance decreases to about 10% of the peak value.

  As described above, in the conventional light emitting device, the amount of light in the horizontal direction decreases when the amount of light in the reference optical axis direction is increased to ensure the front luminance, while the amount of light in the direction of the reference optical axis decreases when the amount of light in the horizontal direction is increased. There is a problem that the front brightness cannot be secured.

  On the other hand, in the light emitting device 10 of the present invention, as shown in FIG. 3C, there are positions where the light density is sparse in the vicinity of the optical axis and in positions other than the optical axis. That is, the increase amount of θ2 is temporarily increased at a place other than the optical axis. As a result, it is possible to spread the light distribution in the lateral direction while securing the light quantity in the direction of the optical axis Z (front direction).

(Difference in light distribution)
FIG. 9 is a graph showing the light distribution in the conventional light emitting device and the light distribution in the light emitting device 10. FIG. 10 is a graph showing the relationship between the increasing amounts of θ1 and θ2 in the conventional light emitting device and the increasing amount of θ1 and θ2 in the light emitting device 10.

  In the conventional light emitting device, as shown by the dotted line 93 in FIG. 10, the increase amount of θ2 always monotonously decreases as θ1 increases. According to this conventional light emitting device, the amount of light in the direction of the reference optical axis and the spread of the light distribution are in an inversely proportional relationship. Therefore, when trying to spread the light distribution as shown by the solid line 92 in FIG. So the front brightness is always sacrificed.

  On the other hand, in the light emitting device 10 of the present invention, there is a place where the increase amount of θ2 is temporarily increased except for the optical axis Z, as indicated by a broken line 94 in FIG. Thereby, as shown by the broken line 91 in FIG. 9, the light quantity in the direction of the optical axis Z can be sufficient even when the light distribution is widened. As a result, sufficient front luminance can be ensured.

  Moreover, the illuminating device provided with the light-emitting device 10 also falls in the technical scope of the present invention. This illuminating device can also increase the amount of light in the front direction and the horizontal direction at the same time, thereby ensuring front luminance and improving light diffusibility.

[Embodiment 2]
Other embodiments according to the present invention will be described below with reference to FIGS. 4 to 7 and FIG. Configurations other than those described in the present embodiment are the same as those in the first embodiment. For convenience of explanation, members having the same functions as those shown in the drawings in the first embodiment are given the same reference numerals, and the description thereof is omitted.

(Light transmission part)
FIG. 4A is a cross-sectional view of a light emitting device 11 according to another embodiment of the present invention. FIG. 4B is a cross-sectional view of a light emitting device 12 according to another embodiment of the present invention.

  The light emitting device 11 further includes a light transmission unit 3 in addition to the light source 1 and the light flux controlling member 2. The light transmitting portion 3 is provided on the bottom surface 2 c of the light flux controlling member 2. The light transmission part 3 transmits the light reflected on the light emitting surface 2b or changes it in the direction perpendicular to the optical axis Z. The light transmitting portion 3 is not particularly limited as long as it is made of the same material as the light flux controlling member 2 and transmits light reflected by the light exit surface 2b or changes in a direction perpendicular to the optical axis Z. . For example, a shape like the light transmission part 4 shown in FIG.4 (b) may be sufficient. 4A and 4B, the light transmitting portions 3 and 4 have a rotationally symmetric shape with respect to the optical axis Z, and are formed as a single member connected in series around the optical axis Z. .

  The installation position of the light transmission part 3 is not particularly limited as long as it is installed on the bottom surface 2c and can transmit more light reflected by Fresnel on the light emission surface 2b in the minus direction of the optical axis Z.

(Effect of light transmission part)
FIG. 5 is a cross-sectional view showing the light emitting device 10 that does not have the light transmitting portion 3. As shown in the figure, the diffusion plate 5 is arranged in the light emitting direction of the light emitting surface 2b of the light emitting device 10. The light emitted from the light emitting element 1 in the light emitting device 10 enters the light incident surface 2a, and then is emitted as light L1 from the light emitting surface 2b. Here, part of the light is reflected without being emitted from the light emitting surface 2b by Fresnel reflection, reflected at the bottom surface 2c, further reflected at the light incident surface 2a, and reaches the light emitting surface 2b again. The light reaching the light emitting surface 2b is refracted so as to approach the optical axis Z on the light emitting surface 2b, and reaches the diffusion plate 5 on the light emitting device 10 as light L2.

  As described above, in the light emitting device 10, the brightness near the optical axis Z of the diffusion plate 5 increases, and brightness unevenness may occur near the optical axis Z.

  FIG. 6 is a cross-sectional view of the light emitting device 11 having the light transmission part 3. As shown in the figure, the diffusion plate 5 is arranged in the light emitting direction of the light emitting surface 2b in the light emitting device 11. The light emitting device 11 includes a light transmitting portion 3 on the bottom surface 2c. The light emitted from the light emitting element 1 in the light emitting device 11 enters the light incident surface 2a, and then is emitted as light L1 on the light emitting surface 2b. Here, a part of the light is reflected without being emitted from the light emitting surface 2b by Fresnel reflection, and is condensed near the light incident surface 2a of the bottom surface 2c.

  The light emitting device 11 is reflected on the light emitting surface 2b at a position where the light emitted from the light source 1 on the bottom surface 2c, incident on the light flux controlling member 2 from the light incident surface 2a, and reflected on the light emitting surface 2b is collected. The light transmission part 3 which permeate | transmits the emitted light is further provided. Thereby, Fresnel-reflected light is incident on the light transmission part 3 and part of the light L2 is emitted in the direction of the optical axis Z, but most of the light L3 is transmitted through the light transmission part 3. Therefore, it is possible to control the Fresnel reflection component that has caused the luminance unevenness in the light emitting device 10.

  As described above, the light transmission part has an effect of making it difficult to cause luminance unevenness on the diffusion plate 5.

(Contrast of illuminance distribution)
FIG. 7A shows an illuminance distribution on the diffusion plate 5 when the light emitting device 11 having the light transmission part 3 is arranged, and on the diffusion plate 5 when the light emitting device 10 not having the light transmission part 3 is arranged. It is a graph which shows illumination intensity distribution. In the figure, the vertical axis represents the relative illuminance distribution of the irradiation light on the diffusion plate 5. On the other hand, the horizontal axis indicates the position of the diffusion plate 5, and the horizontal axis is the center immediately above the light emitting element 1 in each light emitting device. A solid line 70 in the figure shows the illuminance distribution of the light emitting device 11 having the light transmission part 3. On the other hand, a broken line 71 indicates the illuminance distribution of the light emitting device 10 that does not have the light transmission part 3.

  Comparing the solid line 70 and the broken line 71 in the figure, in the vicinity of the center of the diffuser plate, the solid line 70 is a smooth curve, whereas the broken line 71 is not a smooth curve but at the center of the diffuser plate and on both the left and right sides. Illuminance shows the highest value. Therefore, it can be seen that, in the light emitting device 11, the luminance unevenness near the light emitting element 1 is more suppressed than the light emitting device 10.

  FIG. 7B shows the illuminance distribution on the diffusion plate 5 when a plurality of light emitting devices 11 having the light transmission part 3 are arranged, and the diffusion plate 5 when a plurality of light emitting devices 10 not having the light transmission part 3 are arranged. It is a graph which shows illuminance distribution in the upper part. In the figure, the vertical axis represents relative illuminance on the diffusion plate 5. Further, the horizontal axis indicates the position of the diffusion plate 5. A solid line 72 in the figure shows the illuminance distribution on the diffusion plate 5 when the plurality of light emitting devices 11 are evenly arranged. On the other hand, the broken line 73 indicates the illuminance distribution on the diffusion plate 5 when the plurality of light emitting devices 10 are evenly arranged. Comparing the solid line 72 and the broken line 73 in the figure, the solid line 72 is a smooth curve, whereas the broken line 73 is not smooth but a curve having many small peaks. These peaks are caused by illuminance unevenness of irradiated light immediately above the light emitting element 1 of each light emitting device 10.

  As described above, when a plurality of light emitting devices 10 are arranged, luminance unevenness occurs as a whole irradiation light. On the other hand, when a plurality of light emitting devices 11 are arranged, luminance unevenness does not occur in the entire irradiation light.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

  The light emitting device of the present invention can be widely used as various light emitting layers for uniformly irradiating light over a wide range. Moreover, the illuminating device provided with the light emitting device of the present invention can be widely used as various illuminating devices such as signboard illumination, backlight, guide light, and indicator light.

DESCRIPTION OF SYMBOLS 1 Light emitting element 2 Light flux control member 2a Light incident surface 2b Light emitting surface 2c Bottom surface 3 Light transmitting part 4 Light transmitting part 5 Diffuser 10 Light emitting device 11 Light emitting device 12 Light emitting device 30 Region 31 Region θ1 The light emitted from the light emitting element Angle of angle formed by optical axis θ2 Angle of angle formed by light emitted from light exit surface and line parallel to optical axis

Claims (5)

A light emitting device comprising a light source and a light flux controlling member that controls light emitted from the light source,
The light flux controlling member has a light incident surface and a light exit surface,
In a plane orthogonal to the optical axis of the light emitted from the light source, the light density of the light emitted from the light emitting surface becomes denser as the distance from the optical axis increases from the optical axis as a base point. There is an area,
The light emitting device according to claim 1, wherein there is at least one region in the plane in which the light density becomes sparser with increasing distance from the optical axis with a point away from the optical axis as a base point.   2. The light emitting device according to claim 1, wherein the region where the light density becomes more sparse is located at an angle of 65 ° or less between the optical axis and the light emitted from the light source. The illuminance distribution on the diffusion surface of the light emitted from the light exit surface is I, A is a magnification (an arbitrary rational number greater than 0 and less than 1), r is the distance from the optical axis, and σ1 and σ1 are respectively When the dispersion has a different Gaussian distribution, the light flux controlling member has the following formula (1):

The light emitting device according to claim 1, wherein the light emitting device has a shape satisfying the above. The light flux controlling member further includes a bottom surface connecting the light incident surface and the light emitting surface,
The light emitting device is reflected on the light emitting surface at a position where the light emitted from the light source on the bottom surface, enters the light flux controlling member from the light incident surface, and is reflected on the light emitting surface. The light-emitting device according to claim 1, further comprising a light transmission portion that transmits the light.   An illuminating device comprising the light emitting device according to claim 1.

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