Lighting device

• US 9,226,359 B2
• Filed: 12/12/2014
• Issued: 12/29/2015
• Est. Priority Date: 11/19/2010
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Seo, Satoshi
• Primary Examiner(s): LE, DON P
• Application Number:
  US14/568,705
• Publication Number:
  US 20150137711A1
• Time in Patent Office: 382 Days
• Field of Search: 315/297, 315/192, 315/312
• US Class Current: 1/1
• CPC Class Codes: H01L 25/075 the devices being of a type provided for in group H01L33/00
• CPC Class Codes: H01L 27/156 two-dimensional arrays
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H05B 45/20 Controlling the colour of the light
• CPC Class Codes: H05B 45/60 Circuit arrangements for operating LEDs comprising organic material, e.g. for operating organic light-emitting diodes [OLED] or polymer light-emitting diodes [PLED]
• CPC Class Codes: H10K 19/901 Assemblies of multiple devices comprising at least one organic element specially adapted for rectifying, amplifying, oscillating or switching
• CPC Class Codes: H10K 2101/27 Combination of fluorescent and phosphorescent emission
• CPC Class Codes: H10K 50/157 between the light-emitting layer and the cathode
• CPC Class Codes: H10K 50/165 comprising dopants
• CPC Class Codes: H10K 50/17 Carrier injection layers
• CPC Class Codes: H10K 50/171 Electron injection layers
• CPC Class Codes: H10K 50/841 Self-supporting sealing arrangements
• CPC Class Codes: H10K 50/844 Encapsulations
• CPC Class Codes: H10K 50/854 comprising scattering means
• CPC Class Codes: H10K 50/858 comprising refractive means, e.g. lenses
• CPC Class Codes: H10K 59/30 Devices specially adapted for multicolour light emission
• CPC Class Codes: H10K 59/32 Stacked devices having two or more layers, each emitting at different wavelengths
• CPC Class Codes: H10K 59/84 Parallel electrical configurations of multiple OLEDs

Abstract

A lighting device using an electroluminescent material, in which color mixing and dimming can be performed by a simple method, is provided. A lighting device including a first light-emitting element and a second light-emitting element which emits light having a wavelength longer than that of light emitted from the first light-emitting element and starts to emit light at a lower voltage than the first light-emitting element, is provided. The first light-emitting element and the second light-emitting element are connected in parallel, whereby a mixed color of emission colors of the first light-emitting element and the second light-emitting element is controlled by a voltage applied to the first light-emitting element and the second light-emitting element.

Claims

1. A lighting device comprising:

a first light-emitting element emitting a first light; and

a second light-emitting element electrically connected to the first light-emitting element, the second light-emitting element emitting a second light,

wherein the second light has a longer wavelength than the first light,

wherein the second light-emitting element starts to emit the second light at a lower voltage than the first light-emitting element,

wherein a luminance of the second light-emitting element is greater than or equal to 10 cd/m² and less than 10000 cd/m² at the time a first voltage is applied to the first light-emitting element,

wherein the first voltage is a voltage at which the first light-emitting element starts to emit light, and

wherein the first light-emitting element and the second light-emitting element are arranged on the same surface.

2. The lighting device according to claim 1,

wherein a mixed color of a color of the first light and a color of the second light is controlled by a voltage applied to the first light-emitting element and the second light-emitting element.

3. The lighting device according to claim 1,

wherein the first light-emitting element is connected in parallel to the second light-emitting element connected.

4. The lighting device according to claim 1,

wherein the first light-emitting element has approximately the same area as the second light-emitting element.

5. The lighting device according to claim 1, further comprising a power source electrically connected to the first light-emitting element and the second light-emitting element.

6. The lighting device according to claim 1,

wherein the second light-emitting element emits the second light with higher luminance than the first light emitted from the first light-emitting element.

7. The lighting device according to claim 1,

wherein the color of the first light and the color of the second light are in a relation of complementary colors.

8. The lighting device according to claim 1,

wherein the first light-emitting element has an emission spectrum peak greater than or equal to 450 nm and less than or equal to 510 nm, and

wherein the second light-emitting element has an emission spectrum peak greater than or equal to 550 nm and less than or equal to 600 nm.

9. The lighting device according to claim 1,

wherein a light-emitting substance in the first light-emitting element is a fluorescent compound, and

wherein a light-emitting substance in the second light-emitting element is a phosphorescent compound.

10. A lighting device comprising:

a first light-emitting element emitting a first light; and

a second light-emitting element electrically connected to the first light-emitting element, the second light-emitting element emitting a second light,

wherein the second light has a longer wavelength than the first light,

wherein the second light-emitting element starts to emit the second light at a lower voltage than the first light-emitting element,

wherein a luminance of the second light-emitting element is greater than or equal to 10 cd/m² and less than 10000 cd/m² at the time a first voltage is applied to the first light-emitting element,

wherein the first voltage is a voltage at which the first light-emitting element starts to emit light, and

wherein the first light-emitting element and the second light-emitting element are stacked.

11. The lighting device according to claim 10,

wherein a mixed color of a color of the first light and a color of the second light is controlled by a voltage applied to the first light-emitting element and the second light-emitting element.

12. The lighting device according to claim 10,

wherein the first light-emitting element is connected in parallel to the second light-emitting element connected.

13. The lighting device according to claim 10,

wherein the first light-emitting element has approximately the same area as the second light-emitting element.

14. The lighting device according to claim 10, further comprising a power source electrically connected to the first light-emitting element and the second light-emitting element.

15. The lighting device according to claim 10,

wherein the second light-emitting element emits the second light with higher luminance than the first light emitted from the first light-emitting element.

16. The lighting device according to claim 10,

wherein the color of the first light and the color of the second light are in a relation of complementary colors.

17. The lighting device according to claim 10,

wherein the first light-emitting element has an emission spectrum peak greater than or equal to 450 nm and less than or equal to 510 nm, and

wherein the second light-emitting element has an emission spectrum peak greater than or equal to 550 nm and less than or equal to 600 nm.

18. The lighting device according to claim 10,

wherein a light-emitting substance in the first light-emitting element is a fluorescent compound, and

wherein a light-emitting substance in the second light-emitting element is a phosphorescent compound.

19. A lighting device comprising:

a plurality of first light-emitting elements each emitting a first light; and

a plurality of second light-emitting elements electrically connected to the plurality of first light-emitting elements, the plurality of second light-emitting elements each emitting a second light,

wherein the second light has a longer wavelength than the first light,

wherein each of the plurality of second light-emitting elements starts to emit the second light at a lower voltage than each of the plurality of first light-emitting elements,

wherein a luminance of the plurality of second light-emitting elements is greater than or equal to 10 cd/m² and less than 10000 cd/m² at the time a first voltage is applied to the plurality of first light-emitting elements,

wherein the first voltage is a voltage at which the plurality of first light-emitting elements starts to emit light, and

wherein the plurality of first light-emitting elements and the plurality of second light-emitting elements are arranged on the same surface.

20. The lighting device according to claim 19,

wherein a mixed color of a color of the first light and a color of the second light is controlled by a voltage applied to the plurality of first light-emitting elements and the plurality of second light-emitting elements.

21. The lighting device according to claim 19,

wherein the plurality of first light-emitting elements is connected in parallel to the plurality of second light-emitting elements connected.

22. The lighting device according to claim 19,

wherein the plurality of first light-emitting elements has approximately the same area as the plurality of second light-emitting elements.

23. The lighting device according to claim 19, further comprising a power source electrically connected to the plurality of first light-emitting elements and the plurality of second light-emitting elements.

24. The lighting device according to claim 19,

wherein the plurality of second light-emitting elements emits the second light with higher luminance than the first light emitted from the plurality of first light-emitting elements.

25. The lighting device according to claim 19,

wherein the plurality of first light-emitting elements and the plurality of second light-emitting elements are arranged in a honeycomb structure.

26. The lighting device according to claim 19,

wherein the color of the first light and the color of the second light are in a relation of complementary colors.

27. The lighting device according to claim 19,

wherein each of the plurality of first light-emitting elements has an emission spectrum peak greater than or equal to 450 nm and less than or equal to 510 nm, and

wherein each of the plurality of second light-emitting elements has an emission spectrum peak greater than or equal to 550 nm and less than or equal to 600 nm.

28. The lighting device according to claim 19,

wherein a light-emitting substance in each of the plurality of first light-emitting elements is a fluorescent compound, and

wherein a light-emitting substance in each of the plurality of second light-emitting elements is a phosphorescent compound.