Backlight device, light source device, lens, electronic apparatus and light guide plate

1. A backlight device comprising:

a light emitting element;

a lens having an incident surface on which light emitted by said light emitting element is incident, and an outgoing surface configured to converge light and from which the light incident on said incident surface is transmitted out;

a light guide plate having a light incidence plane and introducing through said incidence plane light transmitted out from said outgoing surface, so as to perform surface light emission; and

a reflective member operative to reflect a portion of the light having already been transmitted through said outgoing surface of said lens toward said incidence plane of said light guide plate, the reflective member including a base part having an end edge portion that is disposed a distance furthest from the light guide plate relative to other portions of the reflective member, wherein the end edge portion of the base part is closer to the light guide plate than the light emitting element is to the light guide plate and said incident surface includes a principal surface having an ability to converge light and a projected surface provided at an end portion of said principal surface and projected from said principal surface, and wherein light emitted by said light emitting element is incident on the projected surface prior to reflection by the base part of the reflective member.

2. The backlight device as set forth in claim 1 , wherein said outgoing surface has a principal surface having said ability to converge light and a side surface provided at a side portion of said principal surface; and

said backlight device further comprises a reflective portion provided so as to face said side surface and causing the light transmitted out from said side surface to be re-incident on said side surface and to be transmitted out through said principal surface.

3. The backlight device as set forth in claim 1 , wherein said outgoing surface has a principal surface having said converging ability and a side surface provided at a side portion of said principal surface; and

said reflective member has a first reflective surface operative to reflect a portion of the light transmitted out from said outgoing surface of said lens, toward said incidence plane of said light guide plate, and a second reflective surface provided so as to face said side surface and reflecting the light transmitted out from said side surface to cause the light to be re-incident on said side surface and be transmitted out through said principal surface.

4. The backlight device as set forth in claim 3 , wherein said reflective member includes a base part comprising said second reflective surface having a constant thickness and a wedge part comprising said first reflective surface and having a thickness that gradually decreases in a direction in a direction away from said base part toward said light guide plate.

5. The backlight device as set forth in claim 1 , wherein said incident surface diverges light upon transmittal of light through the incident surface.

6. The backlight device as set forth in claim 1 , wherein the outgoing surface of said lens is one of a cylindrical surface and a toroidal surface.

7. The backlight device as set forth in claim 1 , wherein the principal surface of said lens is one of a cylindrical surface and a toroidal surface.

8. The backlight device as set forth in claim 1 , wherein said lens has a reflective surface provided at a side portion of said outgoing surface and reflecting the light which is incident on said incident surface and which passes through said lens.

9. The backlight device as set forth in claim 1 , wherein said light emitting element is an element emitting light in a plurality of colors.

10. The backlight device as set forth in claim 1 , wherein said light guide plate has a lens portion or prism portion provided at said incidence plane.

11. A backlight device comprising:

a light emitting element;

a lens including

an incident surface on which light emitted by said light emitting element is incident, the incident surface including a principal surface having an ability to converge light and a projected surface provided at an end portion of said principal surface and projected from said principal surface, wherein light emitted by said light emitting element is incident on the projected surface prior to reflection by a first reflective portion,

an outgoing surface configured to converge light and from which the light incident on said incident surface goes out, and

a side surface provided at a side portion of said outgoing surface;

a light guide plate having a light incidence plane and introducing through said incidence plane light going out from said outgoing surface, so as to perform surface light emission;

the first reflective portion provided so as to face said side surface and causing light having already been transmitted through said side surface to be again incident on said side surface and to go out through said outgoing surface; and

a second reflective portion operative to reflect light having already been transmitted through said outgoing surface toward said incidence plane of said light guide plate.

12. The backlight device as set forth in claim 11 , wherein the first reflective portion comprises a base part having an end edge portion that is disposed a distance further from the light guide plate relative to second reflective portion, wherein the end edge portion of the base part is closer to the light guide plate than the light emitting element is to the light guide plate.

13. The backlight device as set forth in claim 11 , wherein the first reflective portion includes a base part having a constant thickness and the second reflective portion includes a wedge part having a thickness that gradually decreases in a direction going away from said base part and toward said light guide plate.

14. The backlight device as set forth in claim 11 , wherein said incident surface diverges light upon transmittal of light through the incident surface.

15. The backlight device as set forth in claim 11 , wherein the outgoing surface or the principal surface of said lens is one of a cylindrical surface and a toroidal surface.

16. A light source device for irradiating with light an incidence plane of a light guide plate performing surface light emission, comprising:

a light emitting element;

a lens having an incident surface on which light emitted by said light emitting element is incident, and an outgoing surface configured to converge light and from which the light incident on said incident surface goes out; the light guide plate having a light incidence plane and introducing through said incidence plane light transmitted out from said outgoing surface, so as to perform surface light emission; and

a reflective member operative to reflect a portion of the light having already been transmitted through said outgoing surface of said lens toward said incidence plane of said light guide plate, wherein the reflective member includes a base part having a constant thickness and a wedge part having a thickness that gradually decreases in a direction going away from said base part and toward said light guide plate and said incident surface includes a principal surface having an ability to converge light and a projected surface provided at an end portion of said principal surface and projected from said principal surface, and wherein light emitted by said light emitting element is incident on the projected surface prior to reflection by the base part of the reflective member.

17. The light source device as set forth in claim 16 , wherein the base part includes an end edge portion that is disposed a distance further from the light guide plate relative to other portions of the reflective member, wherein the end edge portion of the base part is closer to the light guide plate than the light emitting element is to the light guide plate.

18. The light source device as set forth in claim 16 , wherein said outgoing surface includes a side surface provided at a side portion of said principal surface and further comprising a reflective portion provided so as to face said side surface and causing the light transmitted out from said side surface to be re-incident on said side surface and to be transmitted out through said principal surface.

19. The light source device as set forth in claim 16 , wherein said outgoing surface includes a side surface provided at a side portion of said principal surface and said reflective member has a first reflective surface operative to reflect a portion of the light transmitted out from said outgoing surface of said lens toward said incidence plane of said light guide plate, and a second reflective surface provided so as to face said side surface and reflecting the light transmitted out from said side surface to cause the light to be re-incident on said side surface and be transmitted out through said principal surface.

20. The light source device as set forth in claim 16 , wherein said incident surface diverges light upon transmittal of light through the incident surface.