Light engine with LED switching array

• US 9,357,604 B2
• Filed: 08/14/2012
• Issued: 05/31/2016
• Est. Priority Date: 08/16/2011
• Status: Active Grant

• Current Assignee: Huizhou Light Engine Limited
• Original Assignee: Huizhou Light Engine Limited
• Inventors: Siu, Kam Wah, Leung, Wa Hing
• Primary Examiner(s): Owens, Douglas W
• Assistant Examiner(s): Kaiser, Syed M
• Application Number:
  US13/585,463
• Publication Number:
  US 20130043799A1
• Time in Patent Office: 1,386 Days
• Field of Search: 315/193, 315/169.3, 345/694, 345/74, 345/82, 345/102, 257/738, 357/65
• 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 2224/48472 the other connecting portion not on the bonding area also being a wedge bond, i.e. wedge-to-wedge
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• 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 2924/13091 Metal-Oxide-Semiconductor Field-Effect Transistor [MOSFET]
• CPC Class Codes: H01L 2924/30107 Inductance
• CPC Class Codes: H05B 45/30 Driver circuits
• CPC Class Codes: H05B 45/44 with an active control inside an LED matrix

Abstract

An LED array switching apparatus comprises, on a single PCB substrate: a plurality of LED arrays D1 to Dn connected in series, each LED array having a forward voltage; an AC voltage supply coupled to the plurality of LED arrays; and a plurality of constant current sources G1 to Gn, coupled to outputs of LED arrays D1 to Dn, respectively, each of the constant current sources being switchable between a current regulating state and an open state such that as the voltage of the AC voltage supply increases, LED arrays are switched on and lit to form a higher forward voltage LED string, and as the voltage of the AC voltage supply decreases, LED arrays are switched off and removed from the LED string starting with the most recently lit LED array.

Claims

1. An LED array switching apparatus, comprising, on a single PCB substrate:

a plurality of LED arrays (D1 to Dn) connected in series, each LED array having a forward voltage;

an AC voltage supply coupled to the plurality of LED arrays; and

a plurality of constant current sources (G11 to Gn), coupled to output cathodes of LED arrays (D1 to Dn), respectively, each of the constant current sources being switchable between a current regulating state and an open state such that as the voltage of the AC voltage supply increases, LED arrays are switched on and lit to form a higher forward voltage LED string, and as the voltage of the AC voltage supply decreases, LED arrays are switched off and removed from the LED string starting with the most recently lit LED array, wherein the plurality of constant current sources (G11 to Gn) are directly coupled to the output cathodes of LED arrays (D1 to Dn), respectively.

2. The LED array switching apparatus according to claim 1, wherein the plurality of LED arrays and the plurality of constant current sources are formed as semiconductor chips, and the semiconductor chips are affixed to the PCB substrate by direct chip attachment (DCA).

3. The LED array switching apparatus according to claim 2, wherein the semiconductor chips are affixed to the PCB substrate using thermal adhesive.

4. The LED array switching apparatus according to claim 2 or 3, wherein an electrical connection between the semiconductor chips and the PCB substrate is provided by bond wiring.

5. The LED array switching apparatus according to claim 4, wherein the bond wiring is by thermosonic Au ball bonding.

6. The LED array switching apparatus according to claim 4, wherein the bond wiring is by ultrasonic Al wedge bonding.

7. The LED array switching apparatus according to claim 2, further comprising an encapsulant encapsulating at least the semiconductor chips.

8. The LED array switching apparatus according to claim 2, wherein the PCB substrate area for placing semiconductor chips for the LED arrays and the PCB substrate area for placing semiconductor chips for constant current sources are set in proportion to the amount of heat dissipated by the respective types of semiconductor chips.

9. The LED array switching apparatus according to claim 1, wherein LEDs of a particular array are placed next to LEDs of other arrays.

10. The LED array switching apparatus according to claim 1, wherein the PCB substrate is formed from a material in the group consisting of ceramic, glass, organic and flex substrates.

11. The LED array switching apparatus according to claim 1, wherein the LED arrays (D1 to Dn) and the constant current sources (G1 to Gn) are disposed on the PCB substrate based on an amount of heat dissipated by the LED arrays (D1 to Dn) and an amount of heat dissipated by the constant current sources (G11 to Gn).

12. The LED array switching apparatus according to claim 1, wherein no more than two of the constant current sources (G11 to Gn) are switched to the current regulating state during a supply of the voltage by the AC voltage supply.

13. The LED array switching apparatus according to claim 1, wherein the output cathodes of the plurality of LED arrays (D1 to Dn) are connected to input anodes of immediately subsequent ones of the plurality of LED arrays (D1 to Dn).

14. The LED array switching apparatus according to claim 1, wherein the output cathodes of the plurality of LED arrays (D1 to Dn) are directly connected to the input anodes of immediately subsequent ones of the plurality of LED arrays (D1 to Dn).

15. An LED array switching apparatus, comprising, on a single PCB substrate:

a plurality of LED arrays (D1 to Dn) connected in series, each LED array having a forward voltage;

an AC voltage supply coupled to the plurality of LED arrays; and

a plurality of constant current sources (G11 to Gn), coupled to output cathodes of LED arrays (D1 to Dn), respectively, each of the constant current sources being switchable between a current regulating state and an open state such that as the voltage of the AC voltage supply increases, LED arrays are switched on and lit to form a higher forward voltage LED string, and as the voltage of the AC voltage supply decreases, LED arrays are switched off and removed from the LED string starting with the most recently lit LED array, wherein nodes formed by connections of the output cathodes of the plurality of LED arrays (D1 to Dn) to input anodes of immediately subsequent ones of the plurality of LED arrays (D1 to Dn) are coupled to the plurality of constant current sources (G11 to Gn), respectively.

16. An LED array switching apparatus, comprising, on a single PCB substrate:

a plurality of LED arrays (D1 to Dn) connected in series, each LED array having a forward voltage;

an AC voltage supply coupled to the plurality of LED arrays; and

a plurality of constant current sources (G11 to Gn), coupled to output cathodes of LED arrays (D1 to Dn), respectively, each of the constant current sources being switchable between a current regulating state and an open state such that as the voltage of the AC voltage supply increases, LED arrays are switched on and lit to form a higher forward voltage LED string, and as the voltage of the AC voltage supply decreases, LED arrays are switched off and removed from the LED string starting with the most recently lit LED array, wherein nodes formed by connections of the output cathodes of the plurality of LED arrays (D1 to Dn) to input anodes of immediately subsequent ones of the plurality of LED arrays (D1 to Dn) are directly coupled to the plurality of constant current sources (G11 to Gn), respectively.