Light emitting device for AC power operation
First Claim
1. A light-emitting device, comprising:
- a light emitting device (LED) chip comprising an array of light emitting cells electrically connected in series disposed between a source terminal and a ground terminal, wherein each of the light emitting cells includes a first-type semiconductor layer, an active layer formed on the first-type semiconductor layer, and a second-type semiconductor layer formed on the active layer, wherein the first-type semiconductor layer is located between a first side and a second side of the first-type semiconductor layer that are opposite sides of the first-type semiconductor layer and has a portion not covered by the active layer and the second-type semiconductor layer, and wherein the first side is closer to the second-type semiconductor layer than the second side is;
reflective layers formed on the light emitting cells;
bumpers formed on the reflective layers;
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,wherein a given light emitting cell in the array of light emitting cells is electrically connected to an adjacent light emitting cell through an electrical path connecting the not covered portion of a first-type semiconductor layer of the given light emitting cell to a second-type semiconductor layer of the adjacent light emitting cell, the entire electrical path disposed closer to the first side of the first-type semiconductor layer of the given light emitting cell than the second side of the first-type semiconductor layer of the given light emitting cell.
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Accused Products
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.
37 Citations
18 Claims
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1. A light-emitting device, comprising:
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a light emitting device (LED) chip comprising an array of light emitting cells electrically connected in series disposed between a source terminal and a ground terminal, wherein each of the light emitting cells includes a first-type semiconductor layer, an active layer formed on the first-type semiconductor layer, and a second-type semiconductor layer formed on the active layer, wherein the first-type semiconductor layer is located between a first side and a second side of the first-type semiconductor layer that are opposite sides of the first-type semiconductor layer and has a portion not covered by the active layer and the second-type semiconductor layer, and wherein the first side is closer to the second-type semiconductor layer than the second side is; reflective layers formed on the light emitting cells; bumpers formed on the reflective layers; 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, wherein a given light emitting cell in the array of light emitting cells is electrically connected to an adjacent light emitting cell through an electrical path connecting the not covered portion of a first-type semiconductor layer of the given light emitting cell to a second-type semiconductor layer of the adjacent light emitting cell, the entire electrical path disposed closer to the first side of the first-type semiconductor layer of the given light emitting cell than the second side of the first-type semiconductor layer of the given light emitting cell. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A light-emitting device (LED), comprising:
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a switching block connected to an AC power source; a first LED group connected to the switching block and including arrays of light emitting cells connected to conduct electric current in a first direction; and
a second LED group connected to the switching block and including arrays of light emitting cells connected to conduct electric current in a second direction,wherein the first LED group and the second LED group are connected to a common connection terminal, wherein each light emitting cell includes a first-type semiconductor layer, an active layer formed on the first-type semiconductor layer, and a second-type semiconductor layer formed on the active layer, wherein the first-type semiconductor layer is located between a first side and a second side of the first-type semiconductor layer that are opposite sides of the first-type semiconductor layer and has a portion not covered by the active layer and the second-type semiconductor layer, and wherein the first side is closer to the second-type semiconductor layer than the second side is, and wherein a given light emitting cell in each array of light emitting cells is electrically connected to an adjacent light emitting cell through an electrical path connecting the not covered portion of a first-type semiconductor layer of the given light emitting cell to a second-type semiconductor layer of the adjacent light emitting cell, the entire electrical path disposed closer to the first side of the first-type semiconductor layer of the given light emitting cell than the second side of the first-type semiconductor layer of the given light emitting cell. - View Dependent Claims (14, 15, 16, 17, 18)
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Specification