Lighting device

Abstract

The present invention provides a lighting device that has a sufficiently wide irradiation angle and uniform light intensity within a predetermined range, even when using light sources with a narrow divergence angle, such as lasers, or light sources that are close to parallel light. [Solution] The lighting device 100 includes a light source 1 having at least one light-emitting part, a first optical element 10 that receives light emitted from the light source 1 and emits it with an increased emission angle, and a second optical element 20 that receives light emitted from the first optical element 10 and emits it with an even increased irradiation angle.

Claims

1. An optical element having a first surface and a second surface facing the first surface, The optical element includes a microlens array in which a plurality of microlenses are arranged on either the first surface or the second surface. The microlens array is such that the specific tilt angle β of a microlens included in a first region where the distance from a predetermined position is within a first value is constant, and the specific tilt angle β of a microlens included in a second region where the distance from the predetermined position exceeds the first value decreases monotonically. The aforementioned specific inclination angle β represents the inclination angle of the tangent plane at the lens surface located at a distance of 0.6 × D (where D is the diameter of the microlens in a plan view) from the center of the microlens. An optical element characterized by the following features.

2. The optical element according to claim 1, characterized in that the maximum value βmax of the specific inclination angle β is 20 to 40°.

3. The optical element according to claim 2, characterized in that the minimum value βmin of the specific tilt angle β is 5 to 25°.

4. The optical element according to claim 3, characterized in that the ratio of βmin to βmax is 0.2 to 1.

0.

5. When the two orthogonal directions within the plane on which the microlens array is provided are defined as the X and Y directions, and the direction perpendicular to the X and Y directions is defined as the Z direction, On the surface on which the microlens array is provided, the microlenses are arranged at positions where their arrangement is randomly varied, based on the regular arrangement of hexagonal dense or rectangular grid points, within a range of ±4 μm in the x and y directions and ±1 μm in the z direction from the grid point positions. An optical element according to any one of claims 1 to 4, characterized in that

6. An optical element according to any one of claims 1 to 5, Used in lighting devices, The lighting device includes a light source having at least one light-emitting part and the optical element, The optical element is configured to receive light emitted from the light source, and to amplify the radiation angle of the light before emitting it. An optical element characterized by the following features.

7. The optical element according to claim 6, The illumination device has a lens configured to receive light emitted from the optical element and to amplify the radiation angle of the light before emitting it. An optical element characterized by the following features.

8. The optical element according to claim 7, In the radiant intensity distribution of the light emitted from the aforementioned lighting device, when the maximum radiant intensity is set to 1, the radiant intensity at an emission angle of ±90° of the emitted light is 0.5 or higher. An optical element characterized by the following features.

9. The optical element according to claim 7 or 8, In the radiant intensity distribution of light emitted from the aforementioned light source, the full width at half maximum (FWHM) is 6° or more and 40° or less. An optical element characterized by the following features.

10. An optical element according to any one of claims 6 to 9, Let L be the distance from the light source to the optical element, and let θ be the angle of spread of the light emitted from the light source. 0 (However, θ 0 D is defined as the radiant intensity distribution of the light emitted from the light source, which is half of the full width at half maximum (FWHM), and the average value of the radius of the microlens. Ａ In that case, 10<π×(L×tanθ 0 ) ２ / π×D Ａ ２ That is An optical element characterized by the following features.

Images