LIGHT EMITTING DEVICE FOR AC POWER OPERATION

• US 20160345398A1
• Filed: 08/05/2016
• Published: 11/24/2016
• Est. Priority Date: 06/28/2005
• Status: Active Grant

• Current Assignee: Seoul Viosys Co., Ltd. (Seoul Semiconductor Co., Ltd.)
• Original Assignee: Seoul Viosys Co., Ltd. (Seoul Semiconductor Co., Ltd.)
• Inventors: Lee, Chung Hoon, Speck, James S., Kim, Hong San, Kim, Jae Jo, Kim, Sung Han, Lee, Jae Ho
• Granted Patent: US 10,292,220 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H01L 2224/48137 the bodies being arranged next to each other, e.g. on a common substrate
• CPC Class Codes: H01L 2224/49107 on the semiconductor or solid-state body
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• CPC Class Codes: H01L 27/153 in a repetitive configuration, e.g. LED bars
• CPC Class Codes: H01L 27/156 two-dimensional arrays
• CPC Class Codes: H05B 33/02 Details
• CPC Class Codes: H05B 45/14 using electrical feedback from LEDs or from LED modules
• CPC Class Codes: H05B 45/40 Details of LED load circuits
• CPC Class Codes: H05B 45/42 Antiparallel configurations
• CPC Class Codes: H05B 45/44 with an active control inside an LED matrix
• CPC Class Codes: H05B 45/46 having LEDs disposed in parallel lines
• CPC Class Codes: H05B 45/48 having LEDs organised in strings and incorporating parallel shunting devices
• CPC Class Codes: H05B 47/155 Coordinated control of two or more light sources

Abstract

Disclosed is an improved light-emitting device for an AC power operation. A conventional light emitting device employs an AC light-emitting diode having arrays of light emitting cells connected in reverse parallel. The arrays in the prior art alternately repeat on/off in response to a phase change of an AC power source, resulting in short light emission time during a ½ cycle and the occurrence of a flicker effect. An AC light-emitting device according to the present invention employs a variety of means by which light emission time is prolonged during a ½ cycle in response to a phase change of an AC power source and a flicker effect can be reduced. For example, the means may be switching blocks respectively connected to nodes between the light emitting cells, switching blocks connected to a plurality of arrays, or a delay phosphor. Further, there is provided an AC light-emitting device, wherein a plurality of arrays having the different numbers of light emitting cells are employed to increase light emission time and to reduce a flicker effect.

Claims

1-12. -12. (canceled)

13. A light-emitting device, comprising:

an array of light emitting cells electrically connected in series disposed between a source terminal and a ground terminal;

a power source connected to the source terminal to drive the light emitting cells of the array; and

a switching block electrically connected to nodes between two adjacent light emitting cells of the array and the ground terminal to form current paths between the nodes of the array and the ground terminal based on a voltage level received from the power source such that the light emitting cells of the array are sequentially turned on and off.

14. The light-emitting device of claim 13,

wherein the switching block is configured to maintain a substantially constant current flowing through the light emitting cells of the array.

15. The light-emitting device of claim 13,

wherein the substantially constant current flowing through the light emitting cells of the array is in a range of 15 to 25 mA.

16. The light-emitting device of claim 13,

wherein the switching block operates to sequentially turn on the light emitting cells of the array while the voltage level from the power source increases.

17. The light-emitting device of claim 13,

wherein the switching block operates to sequentially turn off the light emitting cells of the array while the voltage level from the power source decreases.

18. The light-emitting device of claim 13,

wherein the light emitting cells include GaN-based light emitting cells.

19. The light-emitting device of claim 13,

wherein at least one of the light emitting cells includes a first-type semiconductor layer and a second-type semiconductor layer and an active layer interposed between the first-type semiconductor layer and the second-type semiconductor layer.

20. The light-emitting device of claim 13, further comprising an additional array of light emitting cells electrically connected in series disposed between the source terminal and the ground terminal.

21. The light emitting device of claim 20, wherein a number of the light emitting cells in the array is different from a number of light emitting cells in the additional array.

22. The light emitting device of claim 13, wherein the switching block is configured to sequentially turn on the light emitting cell in an order and sequentially turn off the light emitting cells in a reverse order.