WO2016163357A1

WO2016163357A1 - Illumination device

Info

Publication number: WO2016163357A1
Application number: PCT/JP2016/061115
Authority: WO
Inventors: 智仁桑垣内
Original assignee: ナルックス株式会社
Priority date: 2015-04-10
Filing date: 2016-04-05
Publication date: 2016-10-13
Also published as: JPWO2016163357A1

Abstract

The objective of the present invention is to provide an illumination device whereby a light beam irradiated from the side surface of a light source is controlled suitably so that the illuminance of an illuminated surface is as uniform as possible. This illumination device comprises the light source (150) disposed over a substrate (200), and an optical element (110) covering the light source and having an entrance surface (111) and an exit surface (113). The light source emits light from an upper surface and the side surface. In a cross section containing the central axis of the optical element, the entrance surface is constituted in such a manner that θ2 - θ1 is positive when θ1 is 15 degrees, θ2 - θ1 is negative when θ1 is 30 degrees, and θ2 - θ1 decreases almost monotonously as θ1 increases from 15 degrees to 30 degrees, where: P0 is the central position of the light-emitting portion on the side surface in the central axis direction; θ1 is a counterclockwise angle, relative to an orthogonal direction to the central axis, formed by a light beam emitted from P0; and θ2 is a counterclockwise angle, relative to the orthogonal direction to the central axis, formed by the light beam after passage through the entrance surface.

Description

Lighting device

The present invention relates to an illumination device including a light source and an optical element that diffuses light from the light source.

The illumination for backlight used for a liquid crystal display has a lighting device that combines a light source such as a light emitting diode (LED) and an optical element that controls light distribution at a predetermined pitch. The optical element includes a concave incident surface and an output surface whose curvature changes from a concave shape to a convex shape toward the end portion from the central axis so as to distribute light over a wide range (for example, Patent Document 1).

In recent years, flip chip type LEDs have attracted attention as light sources. The flip chip type LED has higher light emission efficiency than the conventional LED, and the number of LEDs required per display can be reduced. With the use of flip-chip type LEDs, the pitch between LEDs has increased, and optical elements that distribute light over a wider range have become necessary. In some flip chip type LEDs, the phosphor is not surrounded by a package and has a light emitting surface on the side as well as the top surface. In an illuminating device that uses a light source that also has a light-emitting surface, a part of the light emitted from the side surface of the light source passes through the bottom surface of the optical element and is scattered by the substrate. There is a problem that there are many rays that cannot be done. Therefore, in order to solve the above-described problems, an illuminating device (for example, Patent Document 2) provided with a regular reflection region on a substrate and an illuminating device (for example, an optical device having a bottom surface inclined with respect to the substrate surface) Patent document 3) has been developed.

However, in the conventional illumination device, many of the light rays emitted from the side surface of the light source reach the bottom surface and the edge of the light source to generate scattered light, and this scattered light increases the illuminance immediately above the light source. However, it was inevitable that uneven illuminance occurred on the irradiated surface.

Thus, conventionally, an illuminating device that appropriately controls the light emitted from the side surface of the light source, suppresses the increase in illuminance near the light source, and makes the illuminance of the irradiated surface as uniform as possible has not been developed. .

An optical element having a shape similar to that of the optical element of the present invention is known (for example, Patent Document 4). However, this optical element is not used with a light source that also has a light emitting surface on its side surface, and the shape of this optical element does not control the light emitted from the side surface of the light source.

JP 2009-044016 A JP2015-215984A Japanese Patent Laying-Open No. 2015-043427 JP 2012-064654 A

Therefore, there is a need for an illumination device that appropriately controls the light emitted from the side surface of the light source, suppresses the increase in illuminance near the light source, and makes the illuminance of the irradiated surface as uniform as possible.

The illumination device according to the first aspect of the present invention includes a light source disposed on a substrate, and an optical element that covers the light source and includes an incident surface and an output surface. The incident surface is a surface of a recess opened at the bottom surface of the optical element, the exit surface is provided on the opposite side of the bottom surface, and the light source is configured to emit light from the top surface and the side surface. In the cross section including the central axis of the element, the central position in the central axis direction of the light emitting portion on the side surface of the light source is P0, and the counterclockwise angle that the light emitted from P0 is perpendicular to the central axis is θ1. When the light beam passes through the incident surface and is in the direction perpendicular to the central axis, the counterclockwise angle is θ2, and θ1 is 15 degrees, θ2−θ1 is positive, and θ1 is Θ2-θ1 is negative at 30 degrees, and the incident surface is configured such that θ2-θ1 decreases substantially monotonically as θ1 increases from 15 degrees to 30 degrees.

When θ2−θ1 is positive, the light beam radiated from the point P0 travels further away from the bottom surface after passing through the incident surface and before reaching the incident surface. Therefore, according to the illumination device of the present aspect, in a wide range of θ1 of at least 15 degrees, the light beam emitted from P0 passes through the incident surface and is further away from the bottom surface than before reaching the incident surface. move on. Therefore, among the light rays radiated from the side surface of the light source, the light rays that reach the emission surface increase and the light rays that reach the bottom surface decrease. As a result, an increase in illuminance near the light source can be suppressed, and the illuminance on the irradiated surface can be made more uniform.

An illumination device according to a second aspect of the present invention includes a light source disposed on a substrate, and an optical element that covers the light source and includes an incident surface and an output surface. The incident surface is a surface of a recess opened at the bottom surface of the optical element, the exit surface is provided on the opposite side of the bottom surface, and the light source is configured to emit light from the top surface and the side surface. In the cross section including the central axis of the element, the central position in the central axis direction of the light emitting portion on the side surface of the light source is P0, and the counterclockwise angle that the light emitted from P0 is perpendicular to the central axis is θ1. P1 is a point where the light beam reaches the incident surface, Rs is a distance between P0 and P1 when θ1 = 0, and P0 and P1 when P1 is located at the end of the incident surface. The distance is Rt, and the minimum distance between P0 and the incident surface is Rm.
0.8 <Rm / Rs <0.9
1.2 <Rt / Rs <1.4
The incident surface is configured to satisfy the above.

When the above condition is satisfied, in the cross section including the central axis of the optical element, the angle (acute angle) between the tangent of the incident surface at the point on the incident surface and the direction perpendicular to the central axis, that is, the direction of the substrate is It gets smaller as it gets closer to the part. For this reason, in the illumination device of this aspect, compared with the illumination device of the prior art, in a wider range of θ1, the light emitted from P0 passes through the incident surface and then reaches the incident surface, Proceed further away from the bottom. Therefore, among the light rays radiated from the side surface of the light source, the light rays that reach the emission surface increase and the light rays that reach the bottom surface decrease. As a result, an increase in illuminance near the light source can be suppressed, and the illuminance on the irradiated surface can be made more uniform.

An illumination device according to a third aspect of the present invention includes a light source disposed on a substrate, and an optical element that covers the light source and includes an incident surface and an output surface. The incident surface is a surface of a recess opened at the bottom surface of the optical element, the exit surface is provided on the opposite side of the bottom surface, and the light source is configured to emit light from the top surface and the side surface. In the cross section including the central axis of the element, the central position in the central axis direction of the light emitting portion on the side surface of the light source is P0, and the counterclockwise angle that the light emitted from P0 is perpendicular to the central axis is θ1. P1 is a point where the light beam reaches the incident surface, r2 is a distance in a direction perpendicular to the central axis from the central axis to the end of the output surface, and r2 is a distance from the substrate to the end of the output surface. The distance in the central axis direction is h2, the distance in the direction perpendicular to the central axis from the central axis to P1 is r1, the distance in the central axis direction from the substrate to P1 is h1, and θ1 is 0 or less. In the area

The incident surface is configured such that P1 that satisfies the above condition exists.

When the above condition is satisfied, the light beam emitted from the point P0 and reaching the point P1 on the incident surface reaches the exit surface. In the illumination device of this aspect, the light emitted from P0 reaches the exit surface after passing through the entrance surface in a wider range of θ1 as compared with the prior art illumination device. Therefore, among the light rays radiated from the side surface of the light source, the light rays that reach the emission surface increase and the light rays that reach the bottom surface decrease. As a result, an increase in illuminance near the light source can be suppressed, and the illuminance on the irradiated surface can be made more uniform.

In the illumination device according to the first embodiment of the present invention, an edge portion is further provided between the bottom surface and the emission surface, and the bottom surface and the edge portion are diffusion surfaces.

In the illumination device according to the second embodiment of the present invention, in a cross section including the central axis of the optical element, an angle formed by a straight line indicating the bottom surface of the optical element and the central axis is smaller than 90 degrees. The shape of the optical element is determined.

According to the present embodiment, the height of the foot portion is shortened even if an error occurs with respect to the design value of the gap amount between the bottom surface near the end of the incident surface and the substrate due to the shrinkage of the resin in the injection molding process. As a result, the amount of the gap between the peripheral portion of the incident surface and the substrate can be adjusted to the design value.

In the illumination device according to the third embodiment of the present invention, the shapes of the entrance surface and the exit surface are configured to be symmetric with respect to the central axis.

It is a figure which shows the illumination unit for backlight containing an illuminating device provided with a light source and an optical element. It is a figure for demonstrating two types of light sources. It is a figure which shows distribution of the luminous intensity by said two types of light sources. It is a figure explaining an illuminating device provided with the light source of the type shown in FIG.2 (b), and the optical element of a prior art. It is a figure which shows the structure of the illuminating device of one Embodiment of this invention provided with the light source and new optical element of the type shown in FIG.2 (b). It is a figure which shows an example of a structure of a light source. It is a figure which shows the relationship between (theta) 1 and (theta) 2- (theta) 1 about the illuminating device of an Example and a comparative example. It is a figure which shows the relationship with the distance R from the point P0 along the light ray of the direction of (theta) 1 and (theta) 1 to the entrance plane about the illuminating device of an Example and a comparative example. It is a figure for demonstrating three types of distance Rm, Rs, and Rts between the point P0 and an entrance plane about the illuminating device of an Example and a comparative example. It is a figure which shows the relationship between (theta) 1 and (theta) 2 and (theta) n about the illuminating device of an Example and a comparative example. It is a figure which shows the illumination intensity of the to-be-irradiated surface by the illuminating device of an Example and a comparative example. It is a figure which shows the optical element of the illuminating device of one Embodiment of this invention. It is a figure for demonstrating the error with respect to the design shape of the shape of the optical element manufactured by injection molding. It is a figure which shows the shape of the optical element of the illuminating device of one Embodiment of this invention.

FIG. 1 is a diagram showing a backlight illumination unit including an illumination device 100 including a light source 150 and an optical element 110. The light sources 150 are arranged on the substrate 200 at a predetermined pitch, and the optical elements 110 are installed so as to cover the respective light sources 150. The illumination unit further includes a diffusion plate 300. The light beam emitted by the light source 150 is distributed over a wide range by the optical element 110 and irradiates the diffusion plate 300.

FIG. 2 is a diagram for explaining two types of light sources. FIG. 2A shows a light source 150X having a light emitting surface only on the upper surface. The light emitting chip 151 covered with the phosphor 153 is housed in a package 155. Since the side surface of the phosphor 153 is covered with the package 155, no light is emitted from the side surface of the light source 150X. FIG.2 (b) is a figure which shows the light source 150 used for the illuminating device of this invention. A light emitting chip 151 covered with a phosphor 153 is provided on the table 157. Since the phosphor 153 is not covered with the package, light is also emitted from the side surface of the light source 150. In FIG. 2A and FIG. 2B, solid arrows indicate light rays emitted from the top surface, and dotted arrows indicate light rays emitted from the side surface. In order to realize an illumination unit with as few light sources as possible, a light source of the type shown in FIG. 2B, in which light is emitted from the top and side surfaces, is preferred.

FIG. 3 is a diagram showing the luminous intensity distribution by the above two types of light sources. The horizontal axis in FIG. 3 represents an angle θ between the direction perpendicular to the upper surface of the light source and the traveling direction of the emitted light, and the vertical axis in FIG. 3 represents the normalized luminous intensity. The solid line in FIG. 3 represents the luminous intensity of the light source of the type shown in FIG. 2B, where light is emitted from the top and side surfaces, and the dashed line in FIG. The luminous intensity of the type of light source shown in FIG. In the light source of the type shown in FIG. 2A, the angle θ is in the range of −90 degrees to 90 degrees, and the luminous intensity is proportional to the cosine of the angle θ according to Lambert's cosine law. In other ranges, no light beam is generated and the luminous intensity is zero. In the light source of the type shown in FIG. 2 (b), a luminous flux is generated in the range of -180 degrees to -90 degrees and 90 degrees to 180 degrees, and the luminous intensity is also in accordance with Lambert's cosine law in the above range. Proportional to cosine of angle θ.

FIG. 4 is a diagram for explaining an illumination device 100X including the light source 150 of the type shown in FIG. 2B and a conventional optical element 110X. Fig.4 (a) is a figure which shows the structure of the illuminating device 100X. FIG. 4B is a diagram illustrating a path of light rays emitted from a point on a side surface of the light source 150 (a point P0 described later). The incident surface 111X of the optical element 110X is the surface of a recess that opens to the bottom surface 117X of the optical element 110X. The emission surface 113X is provided on the opposite side of the bottom. An edge portion 115X is provided between the emission surface 113X and the bottom surface 117X. The entrance surface 111X and the exit surface 113X of the optical element 110X are symmetric with respect to the central axis OP. The light source 150 and the optical element 110X are arranged so that the axis OP passes through the center of the light source 150. The central axis OP is the optical axis. FIGS. 4A and 4B are cross-sectional views including the optical axis OP and one side surface of the light source 150. The edge portion 115X and the bottom surface 117X have a diffusion structure such as a texture. The reason why the edge portion 115X and the bottom surface 117X are provided with a diffusing structure is to reduce unevenness in illuminance that occurs near the optical element due to Fresnel reflected light from the exit surface.

As shown in FIG. 4B, the light emitted from the point on the side surface of the light source 150 reaches the bottom surface 117X and is diffused. A part of the diffused light reaches the edge 115X and is further diffused. Since the exit surface designed to refract the direct light far away cannot refract the scattered light far away, the illuminance in the vicinity of the central axis on the irradiated surface becomes high. As a result, the illuminance immediately above the optical element 110X increases, and the illuminance uniformity on the irradiated surface decreases.

FIG. 5 is a diagram showing a configuration of the illumination device 100 according to one embodiment of the present invention including the light source 150 of the type shown in FIG. 2B and a new optical element 110. The incident surface 111 of the optical element 110 is the surface of a recess that opens to the bottom surface 117 of the optical element 110. The emission surface 113 is provided on the opposite side of the bottom. An edge portion 115 is provided between the emission surface 113 and the bottom surface 117. The entrance surface 111 and the exit surface 113 of the optical element 110 are symmetric with respect to the axis OP. The light source 150 and the optical element 110 are arranged so that the axis OP passes through the center of the light source 150. The axis OP is the optical axis. FIG. 5 is a cross-sectional view including the optical axis OP and one side surface of the light source 150. The edge portion 115 and the bottom surface 117 have a diffusion structure such as a texture. The reason why the edge portion 115X and the bottom surface 117X are provided with a diffusing structure is to reduce unevenness in illuminance that occurs near the optical element due to Fresnel reflected light from the exit surface.

FIG. 6 is a diagram illustrating an example of the configuration of the light source 150. The light source 150 includes a base 157 and a rectangular parallelepiped phosphor 153 disposed thereon. The upper surface US and the side surface SS of the phosphor 153 are light emitting surfaces. The center of the side is defined as point P0. In general, the phosphor may have any shape. A point P0 is determined at the center position of the light emitting surface on the side surface of the light source 150 in the height direction.

In FIG. 5, the direction of the substrate surface 200 and the bottom surface 117 of the optical element 110 is the horizontal direction, and the direction of the optical axis OP is the vertical direction. An angle (acute angle) between the light beam emitted from the point P0 and the horizontal direction is defined as θ1. The angle θ1 is measured counterclockwise. Let P1 be the point where the light beam emitted from the point P0 reaches the incident surface. An angle (acute angle) formed by the light beam entering the optical element 110 at the point P1 with the horizontal direction is θ2. The angle θ2 is measured counterclockwise. In addition, an angle (acute angle) formed by a straight line connecting the point P1 and a point indicating the boundary between the emission surface 113 and the edge portion 115 with the horizontal direction is defined as θn. The angle θn is measured counterclockwise. The horizontal distance from the optical axis OP to the point P1 is r1, the horizontal distance from the optical axis OP to the point indicating the boundary between the exit surface 113 and the edge portion 115 is r2, and the vertical direction from the substrate 200 to the point P1. Is the distance h1 and the distance in the vertical direction from the substrate 200 to the point indicating the boundary between the emission surface 113 and the edge portion 115 is h2, the angle θn can be expressed by the following equation.

Therefore, the condition that the light beam emitted from the point P0 and reaching the point P1 on the incident surface 111 does not reach the edge portion 115 but reaches the output surface 113 is as follows.

Hereinafter, examples of the present invention and comparative examples (conventional examples) will be described. The optical elements of Examples and Comparative Examples are made of acrylic, and the refractive index with respect to d-line is 1.49.

Table 1 is a table | surface which shows the shape of the entrance plane and output surface of the optical element of an Example and a comparative example (conventional example). The intersection of the incident surface, the exit surface, and the optical axis is the origin of the coordinates of each surface. The optical axis is defined as the z axis, and the x axis perpendicular to the optical axis is determined. For the z-axis, the direction from the entrance surface to the exit surface is the positive direction, and for the x-axis, the direction away from the optical axis is the positive direction.

The main parameters of the optical elements of the examples are as follows.
Distance from substrate to incident surface apex: 3.57 [mm]
Distance from substrate to emission surface apex: 4.59 [mm]
Incident surface diameter: 3.76 [mm]
Output surface diameter: 15.7 [mm]
Distance between bottom surface and substrate: 0.08 [mm]

The main parameters of the optical element of the comparative example are as follows.
Distance from substrate to incident surface apex: 3.57 [mm]
Distance from substrate to emission surface apex: 4.59 [mm]
Incident surface diameter: 2.944 [mm]
Output surface diameter: 15.7 [mm]
Distance between bottom surface and substrate: 0.08 [mm]
Here, the incident surface diameter is the diameter of the opening of the incident surface on the bottom surface. The incident surface diameter of the example is larger than the incident surface diameter of the comparative example.

The light sources of the examples and comparative examples are those shown in FIG. The upper light emitting surface US is a square having a side of 1.2 mm. The height of the light source including the stage is 0.6 mm and is disposed on the substrate. The light emitting surface SS on the side is 1.2 mm in the X direction and 0.3 mm in the z direction, and is disposed perpendicular to the substrate. The center point P0 of the light emitting surface SS is 0.45 mm higher than the substrate. The total luminous flux emitted from the light emitting surface is 100 lumens.

FIG. 7 is a diagram showing the relationship between θ1 and θ2-θ1 for the illumination devices of the example and the comparative example. The horizontal axis in FIG. 7 represents θ1, and the vertical axis in FIG. 7 represents θ2-θ1. Moreover, the continuous line of FIG. 7 represents an Example, and the broken line of FIG. 7 represents a comparative example. According to FIG. 7, θ2−θ1 decreases as θ1 increases. In the embodiment, θ2-θ1 is positive in the region where θ1 is smaller than 21 degrees, but θ2-θ1 is negative in the region where θ1 is larger than 21 degrees. In the comparative example, θ2-θ1 is positive in the region where θ1 is smaller than 9.5 degrees, but θ2-θ1 is negative in the region where θ1 is larger than 9.5 degrees.

When θ2−θ1 is positive, the light beam radiated from the point P0 travels further away from the bottom surface after passing through the incident surface and before reaching the incident surface. Therefore, in the embodiment, as compared with the comparative example, more light rays emitted from the point P0 pass through the incident surface and are further away from the bottom surface than before reaching the incident surface. Proceed to For this reason, the light rays reaching the exit surface 113 increase, and the light rays reaching the bottom surface 117 decrease.

Generally, in the region where θ1 is −10 degrees or more, θ2−θ1 decreases almost monotonously as θ1 increases. The shape of the incident surface is preferably configured so that θ2−θ1 is positive in a region where θ1 is up to 15 degrees.

FIG. 8 is a diagram showing the relationship between the angle θ1 and the distance R from the point P0 along the light beam in the direction of the angle θ1 to the incident surface for the illumination devices of the example and the comparative example. The horizontal axis of FIG. 8 represents θ1, and the vertical axis of FIG. Moreover, a continuous line shows an Example and a dotted line shows a comparative example.

FIG. 9 is a diagram for explaining three types of distances Rm, Rs, and Rt between the point P0 and the incident surface for the illumination devices of the example and the comparative example. Let P1 be the point where the light beam radiated from the point P0 reaches the incident surface. The distance between P0 and P1 when θ1 = 0 is Rs, the distance between P0 and P1 when P1 is located at the end of the incident surface is Rt, and the minimum distance between P0 and the incident surface is Rm. .

8, points corresponding to Rm, Rs, and Rt of the example are indicated by circles, and points corresponding to Rm, Rs, and Rt of the comparative example are indicated by square marks.

Rm, Rs, and Rt of an Example are as follows.
Rm = 0.860 [mm], θ1 = 21.36 [degrees] at that time
Rs = 0.967 [mm], θ1 = 0 [degree] at that time
Rt = 1.3 [mm], then θ1 = -16.08 [degree]

Rm, Rs, and Rt of the comparative example are as follows.
Rm = 0.800 [mm], θ1 = 9.52 [degree] at that time
Rs = 0.812 [mm], θ1 = 0 [degree] at that time
Rt = 0.947 [mm], at that time θ1 = −22.96 [degrees]
Therefore, the following conditions are satisfied for the example.
0.8 <(Rm / Rs) = 0.889 <0.9
1.2 <(Rt / Rs) = 1.345 <1.4
On the other hand, for the comparative example, the above two inequalities are not satisfied as follows.
(Rm / Rs) = 0.987
(Rt / Rs) = 1.167

In the case where the above two inequalities are satisfied, in the cross section including the central axis of the optical element, the angle (acute angle) formed by the tangent at the point on the incident surface and the direction perpendicular to the central axis increases toward the end. Become. Therefore, in the illuminating device of the embodiment, compared with the illuminating device of the prior art, in a wider range of θ1, after the light beam emitted from P0 passes through the incident surface, compared with before reaching the incident surface, Proceed further away from the bottom. Therefore, among the light rays radiated from the side surface of the light source, the light rays that reach the emission surface increase and the light rays that reach the bottom surface decrease. As a result, an increase in illuminance near the light source can be suppressed, and the illuminance on the irradiated surface can be made more uniform.

FIG. 10 is a diagram showing the relationship between θ1, θ2, and θn for the illumination devices of the example and the comparative example. The horizontal axis of FIG. 10 represents θ1, and the vertical axis of FIG. 10 represents θ2 and θn. In FIG. 10, the solid line represents θ2 of the example, and the broken line represents θ2 of the comparative example. A one-dot chain line represents θn of the example, and a two-dot chain line represents θn of the comparative example. According to FIG. 10, in the embodiment, there is a region where θ2 ≧ θn in a region where θ1 is 0 or less. Specifically, θ2 ≧ θn in the region where θ1 is −8 degrees or more. On the other hand, in the comparative example, there is no region where θ2 ≧ θn in the region where θ1 is 0 or less. Only in the region where θ1 is 5 degrees or more, θ2 ≧ θn. As described above, in the embodiment, more light rays reach the exit surface as compared with the comparative example, so that the scattered light generated at the bottom surface and the edge portion is reduced as compared with the comparative example.

FIG. 11 is a diagram illustrating the illuminance of the irradiated surface by the illumination devices of the example and the comparative example. The irradiated surface is arranged in parallel with the substrate at a position of 30 mm from the substrate. The horizontal axis in FIG. 11 represents the distance from the optical axis, and the vertical axis in FIG. 11 represents the illuminance. The unit of illuminance is lumens per square meter (lm / m ² ). According to FIG. 11, the peak of illuminance by the illumination device of the example is lower than the peak of illuminance by the illumination device of the comparative example. In the illumination device of the example, compared with the illumination device of the comparative example, the ratio of the light beam reaching the diffusion structure of the bottom surface and the edge portion of the side light emission light beam is low, the generation of scattered light is suppressed, and the illuminance peak Has fallen. Therefore, according to the illuminating device of an Example, compared with the illuminating device of a comparative example, a more uniform illumination distribution is obtained.

As described above, in the illumination device of the present invention, the shape of the incident surface of the optical element is based on the point P0 of the center position in the height direction of the light emitting surface of the side surface of the light source in the cross section including the central axis of the optical element. It is defined as. Defining the shape of the incident surface of the optical element with reference to the point P0 of the center position in the height direction of the light emitting surface on the side surface of the light source increases the number of rays that pass through the emitting surface among the light rays emitted from the light emitting surface of the side surface. This is based on the new knowledge of the inventor that the uniformity of illuminance on the irradiated surface is improved by reducing the light rays reaching the bottom surface, which is a technical idea not found in the prior art.

FIG. 12 is a diagram showing an optical element of the illumination device according to the embodiment of the present invention. Fig.12 (a) is a perspective view of the optical element of the illuminating device of one Embodiment of this invention. FIG. 12B is a cross-sectional view including the central axis of the optical element of the illumination device according to the embodiment of the present invention. The optical element includes an entrance surface 111, an exit surface 113, a bottom surface 117, an edge portion 115, a foot portion 1151, and a gate portion 1153. The incident surface 111 is a concave surface having an opening in the bottom surface 117. The edge portion 115 connects the peripheral portion of the emission surface 113 and the peripheral portion of the bottom surface 117. The edge portion 115 is provided with a foot portion 1151 for fixing the optical element to the substrate. The edge portion 115 is further provided with a gate portion 1153 which is a resin inlet when the optical element is manufactured by injection molding. The bottom surface 117 and the edge portion 115 are formed so as to have a diffusing function such as applying a texture.

FIG. 13 is a diagram for explaining an error of the shape of the optical element manufactured by injection molding with respect to the designed shape. The bottom surface indicated by the solid line indicates the bottom surface of the designed optical element, and the bottom surface indicated by the dotted line indicates the bottom surface of the optical element manufactured by injection molding. When the resin shrinks in the injection molding process, an error Δz as shown in FIG. 13 may occur. In such a case, the shape of the peripheral portion of the incident surface 111A changes, and among the light beams emitted from the side surface of the light source 150, the light beam reaching the bottom surface 117A and the edge portion 115A increases. In order to prevent this, a measure for shortening the height L of the foot 1151A can be considered. However, when the error Δz is larger than the height L of the foot portion 1151A, the gap amount between the peripheral portion of the incident surface 111A and the substrate 200 cannot be adjusted to the design value only by changing the height L. As a result, when the gap amount is adjusted to the design value, the mold block corresponding to the bottom surface of the optical element is corrected, which requires cost and time.

FIG. 14 is a diagram showing the shape of the optical element of the illumination device according to the embodiment of the present invention. FIG. 14 is a view showing a cross section including the central axis of the optical element. In the cross section including the central axis of the optical element, the shape of the optical element is determined so that the angle formed by the straight line indicating the bottom surface of the optical element and the central axis is smaller than 90 degrees. That is, when the optical element is arranged on the substrate 200, the distance d2 between the bottom surface 117B and the substrate 200 at the position where the distance from the central axis is rb, which is in the vicinity of the edge portion 115B of the bottom surface 117B, is equal to that of the bottom surface 117B. The shape of the optical element is determined so that the distance from the central axis in the vicinity of the incident surface 111B is larger than the distance d1 between the bottom surface 117B and the substrate 200 at the position of ra. By determining the shape of the optical element as shown in FIG. 14, even if an error Δz with respect to the design value of the gap between the bottom surface near the end of the incident surface and the substrate occurs due to resin shrinkage in the injection molding process. By shortening the height of the foot portion 1151B, the gap amount between the peripheral portion of the incident surface 111B and the substrate can be adjusted to the design value.

In the above description, it is assumed that the shapes of the entrance surface and the exit surface are objects with respect to the central axis of the optical element. In another embodiment, a plurality of sections may be provided around the central axis, and the shapes of the entrance surface and the exit surface in the plurality of sections may be different.

Claims

A light source disposed on the substrate;
An illumination device that covers the light source and includes an optical element having an entrance surface and an exit surface,
The incident surface is a surface of a recess opened in the bottom surface of the optical element, and the exit surface is provided on the opposite side of the bottom surface,
The light source is configured to emit light from an upper surface and a side surface;
In the cross section including the central axis of the optical element, the central position in the central axis direction of the light emitting portion on the side surface of the light source is P0, and the light emitted from P0 is in the direction perpendicular to the central axis. Is θ1, and the light beam passes through the incident surface and then becomes a direction perpendicular to the central axis. The counterclockwise angle is θ2, and θ2-θ1 is positive when θ1 is 15 degrees. An illuminating device in which the incident surface is configured such that θ2−θ1 is negative when θ1 is 30 degrees and θ2−θ1 decreases substantially monotonously as θ1 increases from 15 degrees to 30 degrees.
A light source disposed on the substrate;
An illumination device that covers the light source and includes an optical element having an entrance surface and an exit surface,
The incident surface is a surface of a recess opened in the bottom surface of the optical element, and the exit surface is provided on the opposite side of the bottom surface,
The light source is configured to emit light from an upper surface and a side surface;
In the cross section including the central axis of the optical element, the central position in the central axis direction of the light emitting portion on the side surface of the light source is P0, and the light emitted from P0 is in the direction perpendicular to the central axis. Is θ1, and the point where the light ray reaches the incident surface is P1, the distance between P0 and P1 when θ1 = 0 is Rs, and P0 and P1 when P1 is located at the end of the incident surface Rt, and the minimum distance between P0 and the incident surface as Rm,
0.8 <Rm / Rs <0.9
1.2 <Rt / Rs <1.4
An illumination device in which the incident surface is configured to satisfy the above.
A light source disposed on the substrate;
An illumination device that covers the light source and includes an optical element having an entrance surface and an exit surface,
The incident surface is a surface of a recess opened in the bottom surface of the optical element, and the exit surface is provided on the opposite side of the bottom surface,
The light source is configured to emit light from an upper surface and a side surface;
In the cross section including the central axis of the optical element, the central position in the central axis direction of the light emitting portion on the side surface of the light source is P0, and the light emitted from P0 is in the direction perpendicular to the central axis. Is a point where the light beam reaches the incident surface, P1, a distance from the central axis to the exit surface end in the direction perpendicular to the central axis is r2, and the exit surface end from the substrate Θ1 is 0, where h2 is the distance in the direction of the central axis up to h1, r1 is the distance in the direction perpendicular to the central axis from the central axis to P1, and h1 is the distance in the direction of the central axis from the substrate to P1. In the following areas

The illumination device in which the incident surface is configured such that P1 that satisfies the above condition exists.
The lighting device according to any one of claims 1 to 3, further comprising an edge portion between the bottom surface and the exit surface, wherein the bottom surface and the edge portion are diffusion surfaces.
The shape of the optical element is determined so that an angle formed by a straight line indicating the bottom surface of the optical element and the central axis is smaller than 90 degrees in a cross section including the central axis of the optical element. 4. The lighting device according to any one of 4.
The illumination device according to any one of claims 1 to 5, wherein the shapes of the entrance surface and the exit surface are symmetric with respect to the central axis.