JP2016110807A - Lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an LED lighting device which achieves excellent visual quality and efficiency.SOLUTION: A lighting device 1 includes: LEDs 2a to 2f serving as light sources which emit light to the front side; and an optical member 3 disposed at the front side of the light sources and having a first major surface 3a and a second major surface 3b facing the first major surface 3a. A first optical element 31 is provided on the first major surface 3a of the optical member 3. A second optical element 32 is provided on the second major surface 3b of the optical member 3. The first optical element 31 and the second optical element 32 have shapes different from each other.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a lighting device.

Lighting devices such as downlights that use highly directional LEDs as light sources reduce the glare (dazzling) and graininess (brightness of LEDs, also called “hot spots”) when looking at the device. In order to improve, generally, a diffusion plate is disposed on the front side of the LED.
However, if the diffusibility of the diffusion plate is increased in order to suppress hot spots more reliably, there is a problem that the amount of light transmitted through the diffusion plate is reduced (the efficiency of the apparatus is reduced). In order to solve such a problem, for example, in the illuminating device of Patent Document 1, a plate-like optical member having a cylindrical or spherical fine structure formed on both sides may be arranged on the front side of the LED. Proposed.

JP 2012-64527 A

  However, as in the illumination device of Patent Document 1, hot spots may not be sufficiently suppressed only by forming a fine structure portion, and further improvement is required.

  This invention is made | formed in view of such a problem, and it aims at providing the LED lighting apparatus excellent in appearance and efficiency.

  In order to solve the above-mentioned problems, the present inventor has studied various forms of optical elements (microstructure parts) formed on the front and back surfaces of the optical member disposed on the front surface side of the LED. As a result, the inventors have obtained the knowledge that hot spots can be effectively suppressed, thereby completing the present invention.

  (1) An illumination device of the present invention includes a light source that emits light toward the front, a first main surface and a second main surface that are disposed in front of the light source and that are opposed to the first main surface. An optical member having a first optical element on the first main surface of the optical member, and a second optical surface on the second main surface of the optical member. The first optical element and the second optical element are different in shape from each other.

(2) In the above (1), one of the first optical element and the second optical element has a curved surface with respect to the optical axis, and the other has an inclined plane inclined with respect to the optical axis. .
(3) In the above (2), the optical element having the curved surface is formed in a dome shape, and the optical element having the inclined plane is formed in a pyramid shape.

(4) In any one of the above (1) to (3), the first optical element and the second optical element are each provided in a lattice shape.
(5) In any one of the above (1) to (4), a plurality of the light sources are provided, and the remaining light sources are arranged rotationally symmetrically around one light source.

  ADVANTAGE OF THE INVENTION According to this invention, the LED lighting apparatus excellent in appearance and efficiency can be provided.

(A) is the front view of the illuminating device which concerns on embodiment of this invention, Comprising: The figure which showed the point light source through, (b) is AA sectional drawing of (a). It is a figure explaining a 1st optical element. It is a figure explaining a 2nd optical element. It is a figure which shows the modification of the 2nd optical element. It is a figure explaining the luminance distribution of the illuminating device 1 which concerns on embodiment of this invention. It is a figure explaining the mechanism of the illuminating device which concerns on embodiment of this invention. It is a figure explaining the mechanism of the illuminating device which concerns on embodiment of this invention.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention (hereinafter referred to as embodiments) will be described in detail with reference to the accompanying drawings. Note that the same number is assigned to the same element throughout the description of the embodiment.

(overall structure)
FIG. 1A is a front view of a lighting device according to an embodiment of the present invention, and is a view showing a point light source in a transparent manner, and FIG. 1B is a cross-sectional view taken along line AA in FIG.
As shown in FIG. 1, an illuminating device 1 according to an embodiment of the present invention includes LEDs (light emitting diodes) 2 a to 2 f serving as point light sources that emit light toward the front, and predetermined LEDs in front of the LEDs 2 a to 2 f. A disk-shaped (for example, 60 mmφ) optical member 3 disposed at a distance (for example, 20 mm), and a housing 4 that integrally holds the LEDs 2a to 2f and the optical member 3 are provided. In FIG. 1A, the optical member 3 is shown in a transparent manner. In this embodiment, the number of LEDs is six (plural). As shown in the figure, one LED 2a arranged at the center and five LEDs arranged at equal intervals (rotationally symmetric) on the outer peripheral side thereof. It is comprised from LED2b-2f.
Since the present invention is characterized by the optical member 3, the optical member 3 will be described below.

(Optical member 3)
The optical member 3 is formed using a transparent member (resin material), and a plurality of “first optical elements (31 described later) are provided over substantially the entire area of the incident surface (first main surface) 3 a facing the LEDs 2 a to 2 f. ) ”Is formed, and a plurality of“ second optical elements (32 to be described later) ”are formed over substantially the entire area of the exit surface (second main surface) 3b facing the entrance surface. Since the first optical element 31 and the second optical element 32 are formed so as to have different shapes, the traveling directions of incident light can be controlled to be different from each other.

(First optical element ("dimple") 31)
FIG. 2 is a diagram illustrating the first optical element.
Each of the first optical elements 31 is a convex dimple (dome-shaped convex portion) having a curved surface with respect to the optical axis. The plurality of first optical elements 31 are arranged in a staggered pattern and constitute a fly-eye lens as a whole. Table 1 shows an example of the pitch in the X direction, the pitch in the Y direction, the cutting tool R, the maximum depth, and the contact angle in the first optical element 31.

(Second optical element ("pyramid") 32)
FIG. 3 is a diagram for explaining the second optical element 32, and FIG. 4 is a diagram showing a modification of the second optical element 32. As shown in FIG. 3, each of the second optical elements 32 has an inclined plane inclined with respect to the optical axis, and has four inclined surfaces arranged in a rotationally symmetrical manner on the outer surface. It has a (pyramidal) shape and is formed in a concave shape. In addition, although the example of the prefix quadrangular pyramid is shown in FIG. 3, the thing of a pointed quadrangular pyramid can also be applied as shown in FIG. The plurality of second optical elements 32 are arranged in a lattice pattern. Table 2 shows examples of the triangular angle, the bottom surface width, and the height in the second optical element 32.

  FIG. 5 is a diagram illustrating the luminance distribution of the illumination device 1 according to the embodiment of the present invention. FIG. 5 shows the results of analyzing the luminance distribution in the front direction (optical axis direction) on the emission surface (second surface) 3b, and the magnitude of luminance is displayed in color. The lighting device 1 of the embodiment of the present invention (FIG. 5C) includes a reference example 1 (FIG. 5A) in which dimples are provided on both sides and a reference example 2 in which pyramids are provided on both sides (FIG. 5C). ), It can be seen that the light is uniformly dispersed over the entire exit surface to a level where almost no hot spots are observed. The level is substantially the same as in Conventional Example 1 (when a diffusion plate having a transmittance of 65% and a diffusion material dispersed therein is used). Reference Example 1 and Reference Example 2 are examples in which the same optical element is provided on both sides.

Next, when comparing the efficiency (light flux emitted from the optical member / light flux emitted from the LED × 100), the value 86% of the illumination device of the present embodiment is 90% of the reference example 1 and that of the reference example 2. It can be seen that the value is substantially the same as the value 85%, which is clearly larger than the value 65% of the conventional example 1.
From these analysis results, it is shown that the lighting device 1 according to the present embodiment can suppress hot spots without reducing efficiency.

  6 and 7 are diagrams for explaining the mechanism of the illumination device according to the embodiment of the present invention. 6A shows the luminance distribution in the front direction on the virtual exit surface when no optical member is arranged (Study 1), and FIG. 6B shows the incident (without providing a pyramid on the exit surface). FIG. 10C shows the luminance distribution in the front direction when dimples are formed on the surface (Study 2), and FIG. 8C shows the case of forming a pyramid on the exit surface (without providing dimples on the entrance surface) (Study 3). The luminance distribution in the front direction is shown.

  First, comparing the luminance distribution of Study 1 with the luminance distribution of Study 2, light is evenly distributed around the optical axis of each LED by placing an optical member having dimples on the entrance surface in front of the LED. (See FIG. 7A).

  Next, comparing the luminance distribution of Study 1 and the brightness distribution of Study 3, by placing an optical member having a pyramid on the exit surface in front of the LED, the light is surrounded by the optical axis of each LED as a reference. Although it is diffused, almost no light is observed in the vicinity of the optical axis, and the light is dispersed at each of four equally divided positions on the circumference of a predetermined diameter centered on the optical axis of each LED. I understand. Such a luminance distribution is considered to be caused by the refraction and reflection action according to the incident angle of the light ray incident on each of the four inclined surfaces included in the outer surface of the pyramid (see FIG. 7B). .

  Next, when the second luminance distribution and the third luminance distribution are compared, it can be seen that light is emitted from mutually complementary regions. From this, when the optical member according to the present invention having the configuration of Study 2 and the configuration of Study 3 was used, the deflection / diffusion action of the first optical element and the second optical element was appropriately combined. As a result, it can be considered that the luminance distribution in the front direction is made uniform over the entire exit surface.

  The luminance distribution on the exit surface can be controlled by the LED arrangement, the distance between the LED and the optical member, the directivity of each LED, the shape of each optical element, and the like. The shape of each optical element is the maximum tangent angle when the optical element is a dome shape, the inclination angle of the inclined surface or the number of inclined surfaces when the optical element is a pyramid shape, (Ii) The area ratio between the inclined surface and the flat surface is a main factor in adjusting the luminance distribution.

Next, a modified example of the lighting device according to the embodiment of the present invention will be described.
The first optical element 31 may be provided on the second surface 3b, and the second optical element 32 may be provided on the first surface 3a. With this configuration, the orientation distribution of light emitted from the optical element tends to be widened (80 ° → 90 ° as a beam angle). This is an advantageous configuration when assembling a diffused downlight.

  The second optical element 32 may have another polygonal pyramid shape such as a triangular pyramid instead of the quadrangular pyramid. The first optical element 31 may be any one as long as it has a complementary luminance distribution with the second optical element 32, and may be composed of a plurality of planes, for example. As for the second optical element 32, when a flat surface is required, a flat surface may be provided between the adjacent first optical elements 31 instead of the prefix. The first optical element 31 and the second optical element 32 may be concave or convex. The planar shape of the optical member 3 may be another shape such as a rectangle instead of a circle. Of course, a plurality of LEDs can be appropriately arranged according to the shape of the optical member 3.

  As mentioned above, although this invention was demonstrated using embodiment, it cannot be overemphasized that the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiments. Further, it is apparent from the description of the scope of claims that embodiments with such changes or improvements can also be included in the technical scope of the present invention.

1 Lighting device 2a to 2f LED
3 Optical member 3a Incident surface (first main surface)
3b Outgoing surface (second main surface)
31 1st optical element 32 2nd optical element 4 Case

Claims (5)

A light source that emits light forward,
An illumination device comprising a first main surface and an optical member having a second main surface facing the first main surface, disposed in front of the light source,
A first optical element is provided on the first main surface of the optical member,
A second optical element is provided on the second main surface of the optical member,
The lighting device, wherein the first optical element and the second optical element have different shapes.   2. The first optical element and the second optical element, wherein one has a curved surface with respect to the optical axis and the other has an inclined plane inclined with respect to the optical axis. The lighting device described. The optical element having the curved surface is formed in a dome shape,
The illumination device according to claim 2, wherein the optical element having the inclined plane is formed in a pyramid shape.   The lighting device according to any one of claims 1 to 3, wherein the first optical element and the second optical element are each provided in a lattice shape. 5. The lighting device according to claim 1, wherein a plurality of the light sources are provided, and the remaining light sources are arranged rotationally symmetrically with respect to one light source.