JP2011258408A - Optical element and lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lighting device and an optical element capable of securing indoor uniform illuminance at low cost while taking design into consideration.SOLUTION: An outer surface 12a of the optical element 12 has a shape of rotational symmetry against an axis X of the optical element 12. Meanwhile, an inner surface 12e of the optical element 12 has four divided regions. More concretely, the element has a shape as if the back surface of the optical element 12 is dug out by four oval spheres having major axes at an interval of 90 degrees on an identical surface orthogonally crossing the axial line X of the optical element.

Description

  The present invention relates to an optical element and an illuminating device, and more particularly to an illuminating device which is disposed on a ceiling or the like and is suitable for illuminating an interior, and an optical element used therefor.

  Conventionally, incandescent bulbs and fluorescent lamps have been widely used as light sources for illuminating the interior. However, in recent years when environmental protection has begun to attract attention, lighting fixtures using LED light sources that consume less power than conventional incandescent bulbs and fluorescent lamps have been developed and are already on the market.

  For example, Patent Literature 1 discloses a light-emitting device that is a backlight that illuminates in a planar shape from the back side of a liquid crystal display panel and can also be used for indoor general illumination.

Japanese Patent No. 4357508

  According to the light-emitting device of Patent Document 1, it is possible to perform illumination with light and dark variations suppressed by controlling light distribution characteristics of light emitted from a single LED light source via a light flux control member. It is disclosed that this can be used for an indoor lighting device. However, in the current LED light source, the amount of light is often low compared to incandescent bulbs and fluorescent lamps with only one light emitting element, and a plurality of light emitting elements are used to ensure brightness that can be used as an indoor lighting device. There is a need. As a problem with indoor lighting fixtures, when a lighting fixture is arranged only in the center of a room to be illuminated, there is a problem that the illuminance is high immediately below the light source, but the illuminance is low around the room. Therefore, in order to ensure uniform illuminance throughout the room using the light-emitting device of Patent Document 1, it is necessary to provide a plurality of light-emitting devices on the ceiling, which requires time and effort for installation and wiring, and interior design. There is a problem of limiting the degree of freedom.

  Although the present invention is low-cost, for example, even when a lighting fixture is arranged only in the center of a room, the light distribution characteristic of light emitted from the lighting fixture is a distribution in which the intensity directly below the fixture is weak compared to the peripheral portion Thus, an object of the present invention is to provide an illuminating device and an optical element that can ensure substantially uniform illuminance at the center and the periphery of a room.

The optical element according to claim 1 is a lighting device having a plurality of planar light sources and an optical element,
The exit surface of the optical element has a rotationally symmetric shape with respect to the axis of the optical element,
The incident surface of the optical element has a shape corresponding to each planar light source and combined with a part of the surface of an elliptic sphere having a major axis in a direction perpendicular to the axis of the optical element,
The optical axis of the planar light source is located in the incident surface of the optical element and is located on the side farther from the axis of the optical element than the center of the corresponding elliptical sphere.

  In order to solve the problems of the prior art, it is preferable that, for example, the center and the periphery of a room can be illuminated almost uniformly with a single lighting device having a plurality of light sources. As one method for controlling the light distribution of such an illumination device, it is conceivable to install the light axes of the respective light sources so as to be directed toward the periphery of the room, thereby increasing the illuminance around the room. . However, when a plurality of planar light sources such as LED light sources are used, forming on the same substrate is advantageous in terms of cost because manufacturing and wiring are easier, and further, the overall thickness can be reduced. The design is also convenient, and it is difficult to arrange a plurality of light sources on the same substrate so that the directions of the optical axes of the light sources are different.

  The present inventor pays attention to such a problem, and for example, even when a plurality of planar light sources such as LED light sources are formed on the same substrate, by controlling the light distribution characteristics using an optical element, It has been found that the illuminance can be uniformed directly below and in a direction angled with respect to it. More specifically, the exit surface of the optical element has a rotationally symmetric shape with respect to the axis of the optical element, the incident surface of the optical element corresponds to each planar light source, and the optical element A shape obtained by combining a part of the surface of an elliptical sphere having a major axis in a direction perpendicular to the axis of the element, and the optical axis of the planar light source is within the incident surface of the optical element; Since the optical element is located farther from the axis of the optical element than the center of the corresponding ellipsoidal sphere, the light distribution characteristics of the light emitted from the plurality of planar light sources are controlled by the optical element, and the illumination device By appropriately allocating the amount of light between the position immediately below and the angled direction, it is possible to achieve uniform illuminance in the room even though it is a single lighting device. The “planar light source” refers to a light source that emits light from a surface such as a substrate. For example, there is an LED light source, but it is not limited thereto. In addition, when a plurality of planar light sources are arranged close to each other, they can be regarded as a single light source (that is, one optical axis is used). The “axis” represents a straight line passing through the center of the exit surface of the optical element and in the normal direction of the exit surface at the center of the exit surface. The “optical axis” represents a straight line passing through the light emission center of each light emitting source and in the normal direction of the light emitting surface. Furthermore, the “elliptical sphere” represents a three-dimensional shape expressed by Equation 2 described later. Further, “a plurality of planar light sources are arranged close to each other” means that the relationship between the distance α between the light emission centers of the individual light sources and the closest distance β between the light emission regions of the light sources is β / α <0. 25, and the light emission center refers to the geometric center of gravity of the light emitting surface (see FIG. 10).

  An optical element according to a second aspect is the optical element according to the first aspect, wherein an optical axis of the planar light emitting light source is arranged on a concentric circle centering on an axis of the optical element, and an emission surface of the optical element. Is characterized in that the outer sides of the concentric circles are convex. Thereby, the surrounding light distribution characteristic can be made favorable.

  According to a third aspect of the present invention, there is provided the optical element according to the second aspect, wherein the exit surface of the optical element has a region in which the inner side of the concentric circle is concave. Thereby, the light distribution characteristic in the axial line vicinity of an illuminating device can be adjusted.

  According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the planar light source is an LED light source.

  According to a fifth aspect of the present invention, in the invention according to the fourth aspect, the number of the planar light source is four, and the surface to be illuminated is illuminated in a rectangular shape by the light emitted through the optical element. It is characterized by that. Therefore, it is suitable for use in indoor lighting having a rectangular floor surface.

The optical element according to claim 6 is an optical element of an illumination device having a plurality of planar light sources and an optical element,
The exit surface of the optical element has a rotationally symmetric shape with respect to the axis of the optical element,
The incident surface of the optical element has a shape corresponding to each planar light-emitting light source and a part of the surface of an elliptical sphere having a major axis in a direction orthogonal to the axis of the optical element. It is characterized by that. Thereby, the light distribution characteristic of the light radiate | emitted from the several planar light source can be varied by the direction which has an angle with respect to an axial direction and an axial line.

  An optical element according to a seventh aspect is the invention according to the sixth aspect, wherein the centers of the ellipsoidal spheres are arranged at equal intervals on a concentric circle centered on the axis of the optical element. Is characterized in that the outer sides of the concentric circles are convex. Thereby, the surrounding light distribution characteristic can be made favorable.

  An optical element according to an eighth aspect is the invention according to the seventh aspect, wherein an exit surface of the optical element has a region in which the inner side of the concentric circle is concave. Thereby, the light distribution characteristic in the axial line vicinity of an illuminating device can be adjusted.

  The optical element according to claim 9 is the optical element used in the illumination device according to any one of claims 6 to 8, wherein the plurality of planar light emitting sources are arranged concentrically. And the centers of the ellipsoidal spheres are arranged at equal intervals on a concentric circle centered on the axis of the optical element, and the radius of the concentric circles on which the centers of the ellipsoidal spheres are arranged is the plurality of planar light emitting sources. Is smaller than the radius of the concentric circle in which is arranged. Thereby, the light distribution characteristic of the light emitted from the plurality of planar light sources can be controlled, and the amount of light can be appropriately distributed between directly under the lighting device and the direction angled with respect to the lighting device.

  ADVANTAGE OF THE INVENTION According to this invention, the illumination apparatus and optical element which can ensure substantially uniform illumination intensity in the whole room can be provided, considering the design and being low-cost.

It is a front view of the illuminating device which concerns on 1st Embodiment. It is the figure which cut | disconnected the illuminating device of FIG. 1 by the II-II line | wire, and looked at the arrow direction. It is the figure which cut | disconnected the illuminating device of FIG. 1 by the III-III line | wire, and looked at the arrow direction. It is the figure which cut and showed the board | substrate contact surface of the optical element by 90 degree | times. It is a simulation figure which shows the light distribution characteristic in the illuminating device of this Embodiment. It is the figure which simulated the state which irradiated the floor surface with the illuminating device 10 of this Embodiment. It is a front view of the illuminating device which concerns on 2nd Embodiment. It is the figure which cut | disconnected the illuminating device of FIG. 7 by the VIII-VIII line, and looked at the arrow direction. It is a simulation figure which shows the light distribution characteristic in the illuminating device of this Embodiment. It is a figure which shows arrangement | positioning of a planar light emission light source.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a front view of the illumination device according to the first embodiment. FIG. 2 is a view of the lighting device of FIG. 1 taken along the line II-II and viewed in the direction of the arrow. FIG. 3 is a view of the illumination device of FIG. 1 taken along line III-III and viewed in the direction of the arrow. FIG. 4 is a schematic view showing the substrate contact surface of the optical element cut by 90 degrees together with the light emitting portion.

  The illuminating device 10 includes a disk-shaped substrate 11 on which four light emitting portions 11 a serving as LED light sources are formed, and a cup-shaped optical element 12 attached to the substrate 11. The light emitting portions 11a are arranged at 90 ° intervals so that the optical axes L are arranged at equal intervals on a concentric circle centered on the axis X of the optical element 12. The substrate 11 is assembled to a base or the like (not shown) and attached to an indoor ceiling or the like. The optical element 12 is made of glass or plastic and is formed by a mold.

  The outer surface 12 a (outgoing surface) of the optical element 12 has a rotationally symmetric shape with respect to the axis X of the optical element 12. More specifically, the peripheral region 12c of the outer surface 12a has a convex shape having a circular cross section. On the other hand, the central region 12d of the outer surface 12a is slightly concave, but it may be flat or convex. Such a rotationally symmetric shape is less likely to damage the design. The boundary line between the peripheral region 12c and the central region 12d is along a circle centered on the axis X, and is preferably located outward from the optical axis L of the light emitting portion 11a.

  On the other hand, the inner surface 12b (incident surface) of the optical element 12 is divided into four regions. More specifically, the optical element 12 includes four elliptical spheres each having a major axis at 90 ° intervals on the same plane orthogonal to the axis X of the optical element, and the center of each elliptical sphere arranged on a concentric circle. It has a shape that is similar to that of the back side. That is, the inner surface 12b has a shape obtained by combining a part 12f of the surface of the ellipsoidal sphere, and a region composed of a part of the surface of the ellipsoidal sphere is concave toward the light source.

  Furthermore, in FIG. 4, when the major axis of the elliptic sphere is A, the axis X of the optical element 12 and the optical axis L of the light emitting portion 11a are orthogonal to the major axis A. The distance from the axis X to the center of the elliptical sphere (the center of the long axis A) O is L1 (the radius of the concentric circle where the center of the elliptical sphere is arranged), and from the axis X of the optical element 12 to the optical axis L of the light emitting portion 11a. Is set to L2 (the radius of the concentric circle in which the optical axis of the light emitting unit is disposed), the relationship 0.4 <L1 / L2 <0.8 is established. Here, since L1 / L2 exceeds the lower limit, the ellipsoidal sphere is arranged corresponding to the light source position, so that the light distribution of the light emitted from the light emitting unit can be appropriately controlled. Further, when L1 / L2 is less than the upper limit, the position of the ellipsoidal sphere is not excessively outside, so that the size of the optical element 12 can be reduced.

  FIG. 5 is a simulation diagram showing the light distribution characteristics in the illumination device of the present embodiment, where the 0 degree direction is the direction of the axis X, and the amount of light reached is represented by the size of the radius. The dashed-dotted line in FIG. 5 is the original emission characteristic of the light emitting part 11a that does not pass through the optical characteristic. That is, it can be seen that the light emitting portion 11a alone is the brightest illuminated immediately below, but the illuminance is extremely lowered as the distance from the light emitting portion 11a increases.

  The dotted lines shown in FIG. 5 indicate the light distribution characteristics in the cross-sectional direction shown in FIG. 2 in the illumination device 10 assembled with the optical element 12 of the present embodiment. That is, in the cross-sectional direction shown in FIG. 2, it can be seen that the amount of light reached is higher in the range of about ± 30 degrees to ± 60 degrees than in the 0 degree direction. Such a light distribution characteristic is called batwing. In general, since the distance from the lighting device 10 attached to the ceiling to the floor surface directly below is shorter than the distance to the surrounding floor surface, the light distribution characteristic of the bat wing makes the illuminance of the floor surface uniform. It can be said that it is preferable in the above.

  On the other hand, the solid line shown in FIG. 5 shows the light distribution characteristic in the cross-sectional direction shown in FIG. 3 in the illumination device 10 assembled with the optical element 12 of the present embodiment. That is, in the cross-sectional direction shown in FIG. 3, it can be seen that a peak with the highest amount of reached light appears at a position of ± 65 degrees. Thus, by making the inner surface of the optical element 12 a non-rotationally symmetric surface, a specific angular direction (here, every 90 degrees in a plane orthogonal to the axis X of the illuminating device, and ±± with respect to the axis X) In the direction of 65 degrees, the amount of light reaching can be increased. Thereby, light can be selectively projected to the four corners of the room that tends to be dark.

  FIG. 6 is a diagram simulating a state in which the floor surface is irradiated by the illumination device 10 of the present embodiment, and shows that the illuminance is higher as the density of stippling is lower. As shown in FIG. 6, according to the illumination device 10 of the present embodiment, the floor surface in the room can be illuminated in a square shape, so that the illuminance around the room can be ensured while using the single illumination device 10. it can.

  FIG. 7 is a front view of the illumination device according to the second embodiment. FIG. 8 is a view of the illuminating device of FIG. 7 taken along line VIII-VIII and viewed in the direction of the arrow.

  The illuminating device 20 includes a disk-shaped substrate 21 on which three light emitting portions 21 a serving as LED light sources are formed, and a cup-shaped optical element 22 attached to the substrate 21. The light emitting portions 21a are arranged at 120 degree intervals so that the optical axes L are arranged on concentric circles centering on the axis X of the optical element 22. The substrate 21 is assembled to a base or the like (not shown) and attached to an indoor ceiling or the like.

  The outer surface 22a of the optical element 22 has a rotationally symmetric shape with respect to the axis X of the optical element 12 as in the above-described embodiment. On the other hand, the inner surface 22b of the optical element 22 is divided into three regions. More specifically, three ellipsoidal spheres having long axes at 120 degree intervals on the same plane orthogonal to the axis X of the optical element have a shape that is obtained by hollowing out the back surface of the optical element 22. That is, the inner surface 22b has a shape in which a part 22f of the surface of the elliptic sphere is combined.

  FIG. 9 is a simulation diagram showing the light distribution characteristics in the lighting apparatus of the present embodiment, where the 0 degree direction is the direction of the axis X, and the amount of light reached is represented by the size of the radius. The dotted line shown in FIG. 9 indicates the light distribution characteristic in the direction orthogonal to the cross section shown in FIG. 8 (IX-IX cross section in FIG. 7) in the illumination device 20 assembled with the optical element 22 of the present embodiment. That is, it can be seen that in the cross-sectional direction, the amount of light reached is highest at a position of ± 50 degrees. On the other hand, the solid line shown in FIG. 9 shows the light distribution characteristic in the cross-sectional direction shown in FIG. 8 in the illumination device 10 assembled with the optical element 12 of the present embodiment. That is, in the cross-sectional direction shown in FIG. 8, the light distribution characteristic is asymmetrical in right and left, and the peak of the amount of reached light is at a position of ± 70 degrees, but a region narrower on the right side than the left side can be illuminated far. ing. Thus, by changing the shape of the inner surface 22b of the optical element 22, light distribution control according to the floor surface shape of the room in which the lighting device 20 is installed can be performed.

(Example)
An example corresponding to the present embodiment will be described. First, the shape of the exit surface (outer surface) of the optical element is represented by the aspherical shape shown in Equation 1. The aspherical shape is defined by substituting the data in Table 1 into Equation 1, with the intersection between the exit surface and the axis of the optical element as the origin, the z-axis as the axial direction, the x-axis and the y-axis as the directions orthogonal to the axis. Thus, the z coordinate of the aspheric surface corresponding to the (x, y) coordinate is obtained. In the table, four light sources correspond to the first embodiment, and three light sources correspond to the second embodiment (the same applies hereinafter).

  The shape of the incident surface (inner surface) of the optical element is represented by the aspherical shape shown in Equation 2. The shape of the aspherical surface is (L1, Z1_1, γ1), (L1, Z1_2, γ2), (L1, Z1_3, γ3) in Table 2 as the origin, the z axis in the axial direction, and the x axis in the direction orthogonal to the axial line, Assume that the y-axis is used, and the data of Table 2 is substituted into Equation 2, thereby obtaining the aspherical z-coordinate corresponding to the (x, y) coordinate.

  The present invention is not limited to the above embodiment. For example, not only one LED light source but also a plurality of LED light sources may be arranged for each surface corresponding to the surface of one elliptical sphere. In such a case, it is desirable to arrange so that the major axis of the elliptic sphere and the optical axes of the plurality of LED light sources intersect.

DESCRIPTION OF SYMBOLS 10 Illuminating device 11 Board | substrate 11a Light emission part 12 Optical element 12a Outer surface 12b Inner surface 12c Peripheral area | region 12d Central area | region 12f Part of inner surface 20 Illuminating device 21 Substrate 21a Light-emitting part 22 Optical element 22a Outer surface 22b Inner surface A Ellipsoidal sphere Long axis L Optical axis O of light emitting part O Center of elliptical sphere X Optical element axis

Claims (9)

An illumination device having a plurality of planar light sources and optical elements,
The exit surface of the optical element has a rotationally symmetric shape with respect to the axis of the optical element,
The incident surface of the optical element has a shape corresponding to each planar light source and combined with a part of the surface of an elliptic sphere having a major axis in a direction perpendicular to the axis of the optical element,
An illuminating device, wherein an optical axis of the planar light source is located on a side farther from an axis of the optical element than a center of the corresponding elliptical sphere.   The optical axis of the planar light source is arranged on a concentric circle centering on the axis of the optical element, and the exit surface of the optical element is convex outward of the concentric circle. The lighting device according to claim 1.   The illuminating device according to claim 2, wherein an exit surface of the optical element has a region in which the inner side of the concentric circle is concave.   The lighting device according to claim 1, wherein the planar light source is an LED light source.   The illumination apparatus according to claim 4, wherein the number of the planar light source is four, and the illuminated surface is illuminated in a rectangular shape by the light emitted through the optical element. An optical element of a lighting device having a plurality of planar light source and optical element,
The exit surface of the optical element has a rotationally symmetric shape with respect to the axis of the optical element,
The incident surface of the optical element has a shape corresponding to each planar light-emitting light source and combined with a part of the surface of an elliptic sphere having a major axis in a direction orthogonal to the axis of the optical element. A featured optical element.   The centers of the ellipsoidal spheres are arranged at equal intervals on a concentric circle centered on the axis of the optical element, and the exit surface of the optical element is convex outward from the concentric circle. The optical element according to claim 6.   The optical element according to claim 7, wherein an exit surface of the optical element has a region in which an inner side of the concentric circle is concave.   The optical element is an optical element used in an illuminating device in which the plurality of planar light sources are arranged on a concentric circle, and the centers of the ellipsoidal spheres are equidistantly spaced on a concentric circle centering on the axis of the optical element The concentric circle in which the center of the elliptic sphere is arranged is smaller than the radius of the concentric circle in which the plurality of planar light sources are arranged. An optical element according to 1.