Light emitting device for AC power operation

• US 8,860,331 B2
• Filed: 02/08/2013
• Issued: 10/14/2014
• 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
• Primary Examiner(s): Owens, Douglas W
• Assistant Examiner(s): Chen, Jianzi
• Application Number:
  US13/762,932
• Publication Number:
  US 20130169174A1
• Time in Patent Office: 613 Days
• Field of Search: 315/185.R, 315/186, 315/192, 315/193, 315/185.S, 315/200.R, 315/201, 315/203, 315/200.A, 315/209.R, 315/210, 315/226, 315/294, 315/295, 315/312, 315/313, 315/317, 315/320, 315/323, 315/360, 315/362, 362/217, 362/219, 362/221, 362/222, 362/223, 362/227, 362/249, 362/251, 362/252, 362/362, 362/363, 362/375, 362/800, 362/806, 362/812
• US Class Current: 315/312
• 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. 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. A light-emitting device comprising:

a light emitting diode (LED) chip arranged on a single substrate, the LED chip comprising;

an array of light emitting cells connected in series; and

a bridge rectifier comprising a plurality of diode cells;

a transparent member covering the LED chip;

a first phosphor configured to be excited by light emitted from the LED chip and to emit light in a visible wavelength range; and

a second phosphor configured to be excited by light emitted from the LED chip and to emit light in a visible wavelength range,

wherein the first phosphor has a longer decay time than the decay time of the second phosphor.

2. The light-emitting device as claimed in claim 1, wherein the diode cells are configured to emit light.

3. The light-emitting device as claimed in claim 2, wherein the diode cells comprise the same structure as the light emitting cells.

4. The light-emitting device as claimed in claim 1, wherein the bridge rectifier comprises four nodes, and the array of light emitting cells is connected between two nodes among the four nodes of the bridge rectifier.

5. The light-emitting device as claimed in claim 1,

wherein the decay time of the second phosphor is less than 1 msec, wherein the decay time is a time taken to reach 10% of an initial value after the light emitted from the light emitting cells is blocked, and

wherein the light-emitting device is configured to emit white light comprising a mixture of light emitted from the LED chip, visible wavelength light emitted from the first phosphor, and visible wavelength light emitted from the second phosphor.

6. The light-emitting device as claimed in claim 5, wherein the LED chip is configured to emit blue wavelength light.

7. The light-emitting device as claimed in claim 6, wherein the first phosphor is configured to emit red wavelength light and the second phosphor is configured to emit yellow or green wavelength light.

8. The light-emitting device as claimed in claim 5, wherein the LED chip is configured to emit ultraviolet wavelength light.

9. The light-emitting device as claimed in claim 1, wherein a decay time of the first phosphor is the same as or longer than a time during which the array of the light emitting cells is configured to be turned off while the light-emitting device is in operation.

10. The light-emitting device as claimed in claim 1, wherein wires electrically connect the plurality of light emitting cells in series.

11. A light-emitting device, comprising:

a light emitting diode (LED) chip comprising a plurality of light emitting cells connected in series, parallel, or series-parallel;

a transparent member covering the LED chip;

a first phosphor configured to be excited by light emitted from the LED chip and to emit light in a visible light range; and

a second phosphor configured to be excited by light emitted from the LED chip and to emit light in a visible wavelength range,

wherein the first phosphor has a longer decay time than the decay time of the second phosphor.

12. The light-emitting device as claimed in claim 11, wherein the plurality of light emitting cells are connected in series-parallel, comprising:

a first serial array, a second serial array, and a third serial array of light emitting cells of the plurality of light emitting cells,

wherein the first serial array, the second serial array, and the third serial array are connected in parallel.