# US 2014/0197740 A1 · Led light source > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0197740 A1 - Document ID: US20140197740A1 - Status: Published application - Kind: A1 - Application number: 14/239,166 - Filed: 2012-08-21 - Published: 2014-07-17 - Earliest claimed: 2011-08-23 - Assignees: Koninklijke Philips N.V. - Inventors: Henricus Marius Joseph Maria Kahlman; Ralph Kurt; Haimin Tao - Web page: https://patentgrep.com/patent/US20140197740A1 ## CPC - H05B 45/48: having LEDs organised in strings and incorporating parallel shunting devices - H05B: ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL ## Abstract A LED light source comprises a first rectifier (DB1) having input terminals coupled to an AC voltage source and output terminals connected by a first series arrangement comprising N LED loads and further comprises circuitry (I1, I2, I3, CC) for making the LED loads one by one carry a current when the momentary value of the AC voltage increases and one by one stop carrying a current when the momentary value of the AC voltage decreases. The LED light source also comprises a second rectifier (DB2) having input terminals coupled to the AC voltage source via a reactive element and LED1 LED2 LED3 output terminals connected by a second series arrangement comprising M LED loads and further comprises circuitry (I4) for making the LED loads one by one carry a current when the momentary value of the AC voltage present at the input terminals of the second rectifier increases and one by one stop carrying a current when the momentary value of the AC voltage decreases. ## Claims ### Claim 1 LED light source comprising a first circuit input terminal and a second circuit input terminal for connection to a supply voltage source supplying an AC supply voltage with frequency f, a first rectifier equipped with a first input terminal coupled to the first circuit input terminal and a second input terminal coupled to the second circuit input terminal, a first series arrangement comprising N LED loads, a first and second end of said first series arrangement being coupled to a first output terminal a ld a second output terminal of the first rectifier respectively, wherein N is an integer first control means for during a period of the rectified AC supply voltage subsequently making the LED loads comprised in the first series arrangement carry a current, one by one and in dependency of the momentary amplitude of the rectified AC supply voltage when the momentary amplitude increases and for subsequently making the LED loads stop carrying a current, one by one, and in dependency of the momentary amplitude of the rectified AC supply voltage when the momentary amplitude decreases, a second rectifier equipped with a first input terminal coupled to the first circuit input terminal via a reactive element and a second input terminal coupled to the second circuit input terminal, a second series arrangement comprising M LED loads, a first and second end of said second series arrangement being coupled to a first output terminal and a second output terminal of the second rectifier respectively, wherein M is an integer, and a second control means for, during a period of the rectified AC voltage present between the output terminals of the second rectifier, subsequently making the LED loads comprised in the second series arrangement carry a current, one by one and in dependency of the momentary amplitude of the rectified AC voltage when the momentary amplitude increases and for subsequently making the LED loads stop carrying a current, one by one, and in dependency of the momentary amplitude of the rectified AC voltage when the momentary amplitude decreases. ### Claim 2 (depends on 1) LED light source according to claim 1, wherein the reactive element is a capacitor. ### Claim 3 (depends on 1) LED light source according to claim 1, wherein the first control means comprise at least N-1 control strings co r rising a switch and shunting N-1 of the N LED loads respectively, a control circuit coupled to the N-1 control strings for controlling the switches comprised in the control strings, and a current source coupled between the Nth LED load and the second output terminal of he rectifier. ### Claim 4 (depends on 1) LED light source according to claim 1, wherein the second control means comprise at least M-1 control strings comprising a switch and shunting M-1 of the M LED loads respectively, a control circuit coupled to the M control strings for controlling the switches comprised in the control strings, and a current source coupled between the Nth LED load and the second output terminal of the rectifier. ### Claim 5 (depends on 1) LED light source according to claim 1, wherein the first control means comprises N control strings comprising a switchable current source and connecting the cathode of a LED load to the second output terminal of the rectifier. ### Claim 6 (depends on 1) LED light source according to claim 1, wherein the second control means comprises M cont o strings comprising a switchable current source and connecting the cathode of a LED load to the second output terminal of the rectifier. ### Claim 7 Method for operating a LED light source equipped with a first series arrangement of N LED loads and a second series arrangement of M LED loads comprising the steps of providing an AC supply voltage with frequency f, rectifying the AC supply voltage by means of a first rectifier, and supplying the rectified AC voltage to the series arrangement comprising N LED loads, during a period of the rectified AC supply voltage subsequently making the LED loads carry a current, one by one, in dependency of the momentary amplitude of the rectified AC supply voltage, when the momentary amplitude increases, and subsequently making the LED loads stop carrying a current, in dependency of the momentary amplitude of the AC supply voltage, when the momentary amplitude decreases, and also the simultaneous steps of providing the AC supply voltage with frequency f to a second rectifier via a reactive element, rectifying the AC voltage present at the input of the second rectifier, and supplying the rectified AC voltage to the series arrangement comprising M LED loads, during a period of the rectified AC voltage subsequently making the LED loads carry a current, one by one, in dependency of the momentary amplitude of the rectified AC voltage, when the amplitude increases, and subsequently making the LED loads stop carrying a current, in dependency of the momentary amplitude of the rectified AC voltage, when the amplitude decreases.