Lighting device

• US 8,866,407 B2
• Filed: 08/19/2011
• Issued: 10/21/2014
• Est. Priority Date: 08/20/2010
• Status: Expired due to Fees

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Takahashi, Kei
• Primary Examiner(s): A, Minh D
• Application Number:
  US13/213,395
• Publication Number:
  US 20120043911A1
• Time in Patent Office: 1,159 Days
• Field of Search: 315/224, 315/185.R, 315/291, 315/307, 315/308, 315/312, 315/294
• US Class Current: 315/294
• CPC Class Codes: G09G 2320/041 Temperature compensation
• CPC Class Codes: G09G 2320/043 Preventing or counteracting the effects of ageing
• CPC Class Codes: G09G 2330/00 Aspects of power supply; Aspects of display protection and defect management
• CPC Class Codes: G09G 2360/147 the originated light output being determined for each pixel
• CPC Class Codes: G09G 3/20 for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
• CPC Class Codes: G09G 3/3225 using an active matrix
• CPC Class Codes: G09G 3/34 by control of light from an independent source
• CPC Class Codes: H05B 47/10 Controlling the light source
• CPC Class Codes: H10K 50/00 Organic light-emitting devices integrated devices or assemblies of multiple devices H10K59/00, H10K65/00; organic semiconductor lasers H01S5/36
• CPC Class Codes: H10K 59/00 Integrated devices, or assemblies of multiple devices, comprising at least one organic light-emitting element covered by group H10K50/00
• CPC Class Codes: Y02B 20/40 Control techniques providing energy savings, e.g. smart controller or presence detection

Abstract

A lighting device whose power conversion efficiency is improved by suppression of fluctuation in luminance of a light-emitting element and deterioration of the light-emitting element due to a change in temperature and a change over time and whose power consumption is reduced is provided. The disclosed invention is a lighting device that has a function of correcting a change in temperature and a change over time and includes at least one switching regulator in a driver portion. Constant current drive is performed on light-emitting elements and monitor light-emitting elements are used, so that highly-efficient output voltage which is corrected to have an optimal level is applied to the light-emitting elements and stable drive is performed for a long time. Power conversion efficiency is improved by a switching regulator, so that the total power consumption of the lighting device is reduced.

Claims

1. A lighting device comprising:

a first light-emitting element;

a second light-emitting element;

a circuit configured to perform constant current drive on the first light-emitting element and the second light-emitting element; and

a switching regulator configured to detect a voltage generated in the second light-emitting element and configured to output the voltage,

wherein a first terminal of the first light-emitting element and an output terminal of the switching regulator are electrically connected to each other,

wherein a first terminal of the second light-emitting element and the circuit are electrically connected to each other, and

wherein a second terminal of the first light-emitting element is electrically connected to a second terminal of the second light-emitting element.

2. The lighting device according to claim 1,

wherein an input terminal of the switching regulator and the circuit are electrically connected to a wiring for supplying a high power supply potential.

3. The lighting device according to claim 1,

wherein the second terminal of the first light-emitting element and the second terminal of the second light-emitting element are electrically connected to a wiring for supplying a low power supply potential.

4. The lighting device according to claim 1, further comprising a plurality of first light-emitting elements,

wherein each of the plurality of first light-emitting elements is the first light-emitting element.

5. The lighting device according to claim 1, further comprising a plurality of second light-emitting elements,

wherein each of the plurality of second light-emitting elements is the second light-emitting element.

6. The lighting device according to claim 1, further comprising:

a plurality of first light-emitting elements; and

a plurality of second light-emitting elements,

wherein each of the plurality of first light-emitting elements is the first light-emitting element,

wherein each of the plurality of second light-emitting elements is the second light-emitting element, and

wherein the number of the plurality of second light-emitting elements is smaller than the number of the plurality of first light-emitting elements.

7. The lighting device according to claim 1,

wherein the first light-emitting element and the second light-emitting element are formed over the same substrate.

8. The lighting device according to claim 1,

wherein the first light-emitting element and the second light-emitting element are EL elements.

9. The lighting device according to claim 1, further comprising:

a plurality of first light-emitting elements; and

a plurality of second light-emitting elements,

wherein each of the plurality of first light-emitting elements is the first light-emitting element,

wherein each of the plurality of second light-emitting elements is the second light-emitting element,

wherein the plurality of first light-emitting elements are connected to each other in parallel, and

wherein the plurality of second light-emitting elements are connected to each other in parallel.

10. The lighting device according to claim 1, further comprising:

a plurality of first light-emitting elements; and

a plurality of second light-emitting elements,

wherein each of the plurality of first light-emitting elements is the first light-emitting element,

wherein each of the plurality of second light-emitting elements is the second light-emitting element,

wherein the plurality of first light-emitting elements are connected to each other in series, and

wherein the plurality of second light-emitting elements are connected to each other in series.

11. The lighting device according to claim 1,

wherein the switching regulator comprising:

an output voltage control circuit comprising a transistor, a diode, a coil, and a capacitor; and

a power converter circuit comprising a resistor, an error amplifier, a phase compensation circuit, a comparator, a triangle wave generator, and a buffer.

12. A display device comprising the lighting device according to claim 1 in a display portion.

13. A display device comprising the lighting device according to claim 1 in a backlight portion.

14. An electronic device comprising the lighting device according to claim 1 in a display portion.

15. An electronic device comprising the lighting device according to claim 1 in a backlight portion.

16. A lighting device comprising:

a first light-emitting element;

a second light-emitting element;

a first switching regulator configured to perform constant current drive on the first light-emitting element and the second light-emitting element; and

a second switching regulator configured to detect a voltage generated in the second light-emitting element and configured to output the voltage,

wherein a first terminal of the first light-emitting element and an output terminal of the second switching regulator are electrically connected to each other,

wherein a first terminal of the second light-emitting element and an output terminal of the first switching regulator are electrically connected to each other, and

wherein a second terminal of the first light-emitting element is electrically connected to a second terminal of the second light-emitting element.

17. The lighting device according to claim 16,

wherein an input terminal of the first switching regulator and an input terminal of the second switching regulator are electrically connected to a wiring for supplying a high power supply potential.

18. The lighting device according to claim 16,

wherein the second terminal of the first light-emitting element and the second terminal of the second light-emitting element are electrically connected to a wiring for supplying a low power supply potential.

19. The lighting device according to claim 16, further comprising a plurality of first light-emitting elements,

wherein each of the plurality of first light-emitting elements is the first light-emitting element.

20. The lighting device according to claim 16, further comprising a plurality of second light-emitting elements,

wherein each of the plurality of second light-emitting elements is the second light-emitting element.

21. The lighting device according to claim 16, further comprising:

a plurality of first light-emitting elements; and

a plurality of second light-emitting elements,

wherein each of the plurality of first light-emitting elements is the first light-emitting element,

wherein each of the plurality of second light-emitting elements is the second light-emitting element, and

wherein the number of the plurality of second light-emitting elements is smaller than the number of the plurality of first light-emitting elements.

22. The lighting device according to claim 16,

wherein the first light-emitting element and the second light-emitting element are formed over a same substrate.

23. The lighting device according to claim 16,

wherein the first light-emitting element and the second light-emitting element are EL elements.

24. The lighting device according to claim 16, further comprising:

a plurality of first light-emitting elements; and

a plurality of second light-emitting elements,

wherein each of the plurality of first light-emitting elements is the first light-emitting element,

wherein each of the plurality of second light-emitting elements is the second light-emitting element,

wherein the plurality of first light-emitting elements are connected to each other in parallel, and

wherein the plurality of second light-emitting elements are connected to each other in parallel.

25. The lighting device according to claim 16, further comprising:

a plurality of first light-emitting elements; and

a plurality of second light-emitting elements,

wherein each of the plurality of first light-emitting elements is the first light-emitting element,

wherein each of the plurality of second light-emitting elements is the second light-emitting element,

wherein the plurality of first light-emitting elements are connected to each other in series, and

wherein the plurality of second light-emitting elements are connected to each other in series.

26. The lighting device according to claim 16,

wherein the second switching regulator comprising:

an output voltage control circuit comprising a transistor, a diode, a coil, and a capacitor; and

a power converter circuit comprising a resistor, an error amplifier, a phase compensation circuit, a comparator, a triangle wave generator, and a buffer.

27. A display device comprising the lighting device according to claim 16 in a display portion.

28. A display device comprising the lighting device according to claim 16 in a backlight portion.

29. An electronic device comprising the lighting device according to claim 16 in a display portion.

30. An electronic device comprising the lighting device according to claim 16 in a backlight portion.

31. A lighting device comprising:

a first power supply line;

a second power supply line;

a plurality of first light-emitting elements on a substrate;

a plurality of second light-emitting elements on the substrate; and

a driver portion electrically connected to the first power supply line, the driver portion comprising a switching regulator configured to detect a voltage generated in the plurality of second light-emitting elements and configured to output the voltage to the plurality of first light-emitting elements,

wherein the number of the plurality of second light-emitting elements is smaller than the number of the plurality of first light-emitting elements,

wherein anodes of the plurality of first light-emitting elements and anodes of the plurality of second light-emitting elements are electrically connected to the driver portion,

wherein cathodes of the plurality of first light-emitting elements and cathodes of the plurality of second light-emitting elements are electrically connected to the second power supply line, and

wherein the cathodes of the plurality of first light-emitting elements are electrically connected to the cathodes of the plurality of second light-emitting elements.

32. The lighting device according to claim 31,

wherein the plurality of first light-emitting elements are connected to each other in parallel, and

wherein the plurality of second light-emitting elements are connected to each other in parallel.

33. The lighting device according to claim 31,

wherein the plurality of first light-emitting elements are connected to each other in series, and

wherein the plurality of second light-emitting elements are connected to each other in series.

34. The lighting device according to claim 31,

wherein the substrate is a flexible substrate.

35. The lighting device according to claim 31,

wherein the driver portion further comprises a switching regulator configured to perform constant current drive on the plurality of first light-emitting elements and the plurality of second light-emitting elements.

36. The lighting device according to claim 31,

wherein the driver portion further comprises a circuit configured to perform constant current drive on the plurality of first light-emitting elements and the plurality of second light-emitting elements.