A light guide plate includes: an annular part formed in an annular shape along an element array of multiple light emitting elements; and an annular inner part formed on an annular inside of the annular part continuously with the annular part. The annular part includes: an element array-facing part which is a part facing the element array and which has an incident surface to allow light emitted from the light emitting elements to enter; and a first reflecting part which is a part located closer to the annular inner part than the element array-facing part, and which has a reflecting surface for reflecting the light entering from the incident surface toward the annular inner part. The first reflecting part includes a first light scattering region having a light scattering treatment applied thereto.
1. An illumination device comprising:
a light guide plate; and
multiple light emitting elements annularly arranged on a back side of the light guide plate,
wherein the light guide plate comprises:
an element array-facing part which is a part facing an element array of the multiple light emitting elements and which has an incident surface to allow light emitted from the light emitting elements to enter; an outer annular outer part provided on an annular outside of the element array-facing part;
an inner reflecting part which is located on an inner side of the element array-facing part and has a reflecting surface for reflecting the light entering from the incident surface toward the inner side of the element array-facing part, and which has a first light scattering region having a light scattering treatment applied thereto; and
an annular inner part formed on an inner side of the inner reflecting part continuously with the inner reflecting part, the annular inner part, the inner guide part and the annular outer part comprise a solid light guide plate.
2. The illumination device according to claim 1 , wherein the light scattering treatment applied to the first light scattering region is to provide recesses and/or projections in the reflecting surface of the inner reflecting part.
3. The illumination device according to claim 2 , wherein the number of the recesses and/or projections per unit area in the reflecting surface of the first light scattering region increases as they get farther from the light emitting elements.
4. The illumination device according to claim 2 , wherein the number of the recesses and/or projections per unit area in the reflecting surface of the first light scattering region increases as deviation angles of the recesses and/or projections relative to axes of the light emitting elements increase.
5. The illumination device according to claim 2 , wherein an area occupation ratio of the recesses and/or projections in the reflecting surface of the first light scattering region increases as they get farther from the light emitting elements.
6. The illumination device according to claim 2 , wherein an area occupation ratio of the recesses and/or projections in the reflecting surface of the first light scattering region increases as deviation angles of the recesses and/or projections relative to axes of the light emitting elements increase.
7. The illumination device according to claim 2 , wherein the inner annular part comprises a third light scattering region having a light scattering treatment applied thereto, while recesses and/or projections are provided in the third light scattering region, and
wherein an area occupation ratio of the recesses and/or projections in the first light scattering region and the third light scattering region has a tendency to increase from the first light scattering region toward the third light scattering region.
8. The illumination device according to claim 7 , wherein in the increase in the area occupation ratio of the recesses and/or projections from the first light scattering region toward the third light scattering region, there is a discontinuity between the first light scattering region and the third light scattering region.
9. The illumination device according to one of claim 1 ,
wherein the light guide plate further comprises an outer reflecting part which is a part located closer to the annular outer part than the element array-facing part and which has a reflecting surface for reflecting the light entering from the incident surface toward the annular outer part, and
wherein the outer reflecting part comprises a second light scattering region having a light scattering treatment applied thereto.
10. The illumination device according to claim 9 , wherein the light scattering treatment applied to the second light scattering region is to provide recesses and/or projections in a reflecting surface of the outer reflecting part.
11. The illumination device according to claim 10 , wherein the number of the recesses and/or projections per unit area in the reflecting surface of the second light scattering region increases as they get farther from the light emitting elements.
12. The illumination device according to claim 10 , wherein the number of the recesses and/or projections per unit area in the reflecting surface of the second light scattering region increases as deviation angles of the recesses and/or projections relative to axes of the light emitting elements increase.
13. The illumination device according to claim 10 , wherein an area occupation ratio of the recesses and/or projections in the reflecting surface of the second light scattering region increases as they get farther from the light emitting elements.
14. The illumination device according to claim 10 , wherein an area occupation ratio of the recesses and/or projections in the reflecting surface of the second light scattering region increases as deviation angles of the recesses and/or projections relative to axes of the light emitting elements increase.