Illumination device and display device provided with the same
An illumination device has a blue light emitting element that emits blue light and a light guide member that guides blue light emitted from the blue light emitting element to a light exit surface of the light guide member. A first color conversion element includes a red phosphor that emits red light in response to excitation with the blue light. The first color conversion element is disposed on an optical path between the blue light emitting element and the light guide member. A second color conversion element is disposed on a light exit surface side of the light guide member and separated from the first color conversion element. The second color conversion element comprises a pair of non-permeable transparent substrates, a resin disposed between the non-permeable transparent substrates, and a green phosphor dispersed in the resin for emitting green light in response to excitation with the blue light.
1. An illumination device, comprising:
a blue light emitting element that emits blue light;
a light guide member that guides blue light emitted from the blue light emitting element to a light exit surface of the light guide member;
a first color conversion element including a red phosphor that emits red light in response to excitation with the blue light, the first color conversion element being disposed on an optical path between the blue light emitting element and the light guide member; and
a second color conversion element disposed on a light exit surface side of the light guide member and separated from the first color conversion element, the second color conversion element comprising a pair of non-permeable transparent substrates, a transparent bonding layer disposed between the non-permeable transparent substrates, a resin applied onto the transparent bonding layer, and a green phosphor dispersed in the resin for emitting green light in response to excitation with the blue light.
2. An illumination device according to claim 1 ; wherein the second color conversion element further comprises a diffusion layer containing transparent diffused beads dispersed therein, the diffusion layer being disposed on an upper surface of one of the non-permeable transparent substrates of the second color conversion element.
3. An illumination device according to claim 2 ; wherein the second color conversion element further comprises another phosphor that is excited with the blue light, a weight ratio of the another phosphor to the green phosphor being equal to or smaller than 30%.
4. An illumination device according to claim 2 ; wherein the green phosphor comprises a phosphor material composed of a II-group metal thiogallate and a rare-earth dopant.
5. An illumination device according to claim 1 ; wherein the second color conversion element further comprises another phosphor that is excited with the blue light, a weight ratio of the another phosphor to the green phosphor being equal to or smaller than 30%.
6. An illumination device according to claim 5 ; wherein the another phosphor is a red phosphor that converts light into red light in response to excitation with the blue light.
7. An illumination device according to claim 6 ; wherein the red phosphor of the second conversion element includes the same substance as that of the red phosphor of the first conversion element.
8. An illumination device according to claim 7 ; further comprising a multi-layer film disposed on a rear side of the light guide member and comprised of one of a polyester reflecting sheet and a white polyethylene terephthalate (PET) reflecting sheet.
9. An illumination device according to claim 6 ; further comprising a multi-layer film disposed on a rear side of the light guide member and comprised of one of a polyester reflecting sheet and a white polyethylene terephthalate (PET) reflecting sheet.
10. An illumination device according to claim 5 ; wherein the another phosphor is a color phosphor that converts light into orange light in response to excitation with the blue light.
11. An illumination device according to claim 10 ; further comprising a multi-layer film disposed on a rear side of the light guide member and comprised of one of a polyester reflecting sheet and a white polyethylene terephthalate (PET) reflecting sheet.
12. An illumination device according to claim 5 ; wherein the another phosphor is a color phosphor that converts light into yellow light in response to excitation with the blue light.
13. An illumination device according to claim 12 ; further comprising a multi-layer film disposed on a rear side of the light guide member and comprised of one of a polyester reflecting sheet and a white polyethylene terephthalate (PET) reflecting sheet.
14. An illumination device according to claim 5 ; further comprising a multi-layer film disposed on a rear side of the light guide member and comprised of one of a polyester reflecting sheet and a white polyethylene terephthalate (PET) reflecting sheet.
15. An illumination device according to claim 1 ; wherein the green phosphor comprises a phosphor material composed of a II-group metal thiogallate and a rare-earth dopant.
16. A display device for illuminating a non-self light emission display element with light emitted from a blue light emitting element, the display device comprising:
a light guide member that guides blue light emitted from the blue light emitting element to a light exit surface of the light guide member;
a first color conversion element including a red phosphor that emits red light in response to excitation with the blue light, the first color conversion element being disposed on an optical path between the blue light emitting element and the light guide member; and
a second color conversion element disposed on a light exit surface side of the light guide member and separated from the first color conversion element, the second color conversion element comprising a pair of non-permeable transparent substrates, a transparent bonding layer disposed between the non-permeable transparent substrates, a resin applied onto the transparent bonding layer, and a green phosphor dispersed in the resin for emitting green light in response to excitation with the blue light.
17. A display device according to claim 16 ; further comprising a color filter for color display, the color filter including a green colored portion in which transmittance of light of 470 nm or less is equal to or lower than 20% of transmittance of light at a vicinity of 535 nm.
18. A display device according to claim 17 ; wherein the second color conversion element further comprises another phosphor that is excited with the blue light to emit light, a weight ratio of the another phosphor to the green phosphor being equal to or smaller than 30%.
19. A display device according to claim 16 ; further comprising a color filter for color display, the color filter including a green colored portion in which transmittance of light of 600 nm or more is equal to or lower than 20% of transmittance of light at a vicinity of 535 nm.
20. A display device according to claim 19 ; wherein the second color conversion element further comprises another phosphor that is excited with the blue light to emit light, a weight ratio of the another phosphor to the green phosphor being equal to or smaller than 30%.
21. A display device according to claim 16 ; wherein the second color conversion element further comprises a diffusion layer containing transparent diffused beads dispersed therein, the diffusion layer being disposed on an upper surface of one of the non-permeable transparent substrates of the second color conversion element.
22. A display device according to claim 16 ; wherein the second color conversion element further comprises another phosphor that is excited with the blue light to emit light, a weight ratio of the another phosphor to the green phosphor being equal to or smaller than 30%.