A display device includes a transmissive liquid crystal display panel that is disposed on a front side of a display medium that effects variable display, and an area light source device that is disposed between the liquid crystal display panel and the display medium and illuminates a back surface of the liquid crystal display panel. The area light source device includes a light source, and a light guide that includes a transmissive display part, which is opposed to the display medium, and emits light, which is radiated from the light source, toward the liquid crystal display panel. The light guide is configured such that a thickness at an end face along an edge that defines the transmissive display part is less than a thickness at a surface of the light guide, which is opposed to the light source.
1. A display device comprising:
a transmissive liquid crystal display panel that is disposed on a front side of a display medium that effects variable display; and
an area light source device that is disposed between the liquid crystal display panel and the display medium and illuminates a back surface of the liquid crystal display panel,
wherein the area light source device includes:
a light source; and
a light guide that includes a transmissive display part, which is opposed to the display medium, and emits light, which is radiated from the light source, toward the liquid crystal display panel, and
the light guide is configured such that a thickness at an end face along an edge that defines the transmissive display part is less than a thickness at a surface of the light guide, which is opposed to the light source.
2. The display device according to claim 1 , wherein the transmissive display part is substantially rectangular.
3. The display device according to claim 2 , wherein as regards the end faces along four edges, a thickness at end faces that are parallel to a longitudinal direction of the display medium is less than the thickness at the surface of the light guide, which is opposed to the light source.
4. The display device according to claim 1 , wherein the light guide is substantially rectangular, and said light sources are disposed to face two side surfaces along long sides of the light guide.
5. The display device according to claim 1 , wherein the area light source device includes an optical sheet that is disposed between the light guide and the liquid crystal display panel and imparts predetermined optical characteristics to emission light from the light guide.
6. The display device according to claim 1 , wherein the light guide includes a recess portion, which corresponds to the transmissive display part, on a back surface of the light guide, which is opposed to the display medium.
7. The display device according to claim 1 , wherein the light guide includes an opening part that corresponds to the transmissive display part.
8. The display device according to claim 1 , wherein the light guide includes an inclined surface, which is inclined outward from the transmissive display part, on a back surface of the light guide, which is opposed to the display medium.
9. The display device according to claim 8 , wherein the angle of inclination of the inclined surface is in a range between 20° and 80°.
10. The display device according to claim 8 , wherein the inclined surface has a prism shape.
11. The display device according to claim 6 , wherein the transmissive display part has a depth in a range between 50% and 90% of the thickness of the light guide.
12. The display device according to claim 1 , wherein at least a part of the display medium is accommodated in the transmissive display part.
13. The display device according to claim 1 , wherein the area light source device includes a reflection plate that is disposed on a back surface of the light guide at an area other than the transmissive display part.
14. The display device according to claim 1 , wherein the display medium is disposed at a substantially central part of the liquid crystal display panel.
15. The display device according to claim 1 , further comprising a mechanical rotary reel, which is rotatably disposed, as the display medium.