# US 8,569,969 B2 · Methods and apparatus for controlling multiple light sources via a single regulator circuit to provide variable color and/or color temperature light > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,569,969 B2 - Document ID: US8569969B2 - Status: Granted - Kind: B2 - Application number: 13/122,921 - Filed: 2009-10-02 - Published: 2011-08-11 - Granted: 2013-10-29 - Earliest claimed: 2008-10-10 - Assignees: Koninklijke Philips N.V. - Applicants: Timothy Moss - Inventors: Timothy Moss - Web page: https://patentgrep.com/patent/US8569969B2 ## CPC - H05B 45/20: Controlling the colour of the light - H05B 45/375: using buck topology - Y02B 20/30: Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED] - H05B: ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL - Y02B: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS ## Abstract Methods and apparatus for adjusting the color or color temperature of combined light emitted by one or more LEDs (210, 220, 230) driven by a single switching regulator circuit (200). Properties of the light output are changed by intentionally varying a source voltage (212) provided as an input to the regulator circuit (205). The connection of different colored LEDs in various branches (160, 170, 180) of the switching regulator circuit (205) facilitates adjustment of the respective drive currents provided to the LEDs, and hence the color or color temperature of the resulting combined light, merely by adjusting the level of the source voltage of the regulator circuit. ## Claims ### Claim 1 A lighting apparatus, comprising: a buck regulator circuit comprising a first branch for conducting a switch current, a second branch for conducting a freewheeling current, and a third branch for conducting a load current; at least one first LED disposed in the first branch of the buck regulator circuit; and at least one second LED disposed in the second branch of the buck regulator circuit. ### Claim 2 (depends on 1) The apparatus of claim 1, wherein: the at least one first LED is configured to generate first radiation having a first spectrum; and the at least one second LED is configured to generate second radiation haying a second spectrum different than the first spectrum. ### Claim 3 (depends on 2) The apparatus of claim 2, wherein one of the at least one first LED and the at least one second LED includes at least one red LED, and wherein another of the at least one first LED and the at least one second LED includes at least one blue LED. ### Claim 4 (depends on 2) The apparatus of claim 2, wherein the at least one first LED includes at east one first white LED and wherein the at least one second LED includes at least one second white LED. ### Claim 5 (depends on 2) The apparatus of claim 2, wherein the buck regulator circuit receives a source voltage and further comprises at least one load disposed in the third branch and at least one feedback control circuit for providing a regulated load voltage and/or a regulated load current to the at least one load, and wherein the apparatus further comprises: at least one user interface for varying the source voltage to the buck regulator circuit so as to control a first intensity of the first radiation and a second intensity of the second radiation. ### Claim 6 (depends on 5) The apparatus of claim 5, wherein the at least one load includes at least one third LED for generating third radiation. ### Claim 7 (depends on 6) The apparatus of claim 6, wherein: one of the at least one first LED and the at least one second LED includes at least one red LED; another of the at least one first LED and the at least one second LED includes at least one blue LED; and the at least one third LED includes at least one white LED. ### Claim 8 (depends on 6) The apparatus of claim 6, wherein the feedback control circuit includes a reference voltage for determining a value of the regulated load voltage or the regulated load current to the at least one load, and wherein the at least one user interface is configured to vary the source voltage to the buck regulator circuit and the reference voltage of the feedback control circuit so as to control the first intensity of the first radiation, the second intensity of the second radiation, and a third intensity of the third radiation. ### Claim 9 A method, comprising providing at least one first LED in a first current branch of a buck regulator circuit and at least one second LED in a second current branch of the buck regulator circuit, and varying a DC source voltage of the buck regulator circuit to increase a first magnitude of a first current provided to the at least one first LED and simultaneously to decrease a second magnitude of a second current provided to the at least one second LED. ### Claim 10 (depends on 9) The method of claim 9, wherein the at least one first LED emits first radiation of a first spectrum and the at least one second LED emits second radiation of a second spectrum, and wherein varying the DC source voltage results in a change in at least one optical characteristic of combined radiation formed by a mixing of the first radiation and the second radiation. ### Claim 11 (depends on 10) The method of claim 10, wherein varying the DC source voltage results in a change in a color and/or color temperature of the combined light. ### Claim 12 (depends on 10) The method of claim 10, wherein the lighting control circuit further comprises at least one third LED, and wherein the at least one third LED emits third radiation of a third spectrum, and wherein a magnitude of the third radiation does not change in response to varying the DC source voltage. ### Claim 13 An apparatus, comprising: a controllable DC source; a switch branch coupled to the controllable DC source and comprising at least one switch and at least one first LED; a filtering circuit comprising: at least one inductor coupled to the at least one switch; at least one filter capacitor coupled to the at least one inductor; and at least one second LED coupled to the at least one inductor and the at least one filter capacitor, wherein the at least one second LED forms a freewheeling branch; a load branch; and a feedback control circuit for changing a duty cycle of the at least one switch to provide a regulated voltage or regulated current to the load branch, wherein changing the duty cycle of the at least one switch alters a first magnitude of first light generated by the at least one first LED and a second magnitude of second light generated by the at least one second LED. ### Claim 14 (depends on 13) The apparatus of claim 13, wherein changing the duty cycle of the at least one switch occurs in response to a change in a source voltage output generated by the controllable DC source. ### Claim 15 (depends on 13) The apparatus of claim 13, further comprising at least one third LED connected in the load branch, wherein the at least one third LED generates third light as essentially white light. ### Claim 16 (depends on 15) The apparatus of claim 15, wherein the first light is essentially red light and the second light is essentially blue light. ### Claim 17 (depends on 16) The apparatus of claim 16, wherein the first light, second light, and third light combine to form combined essentially white light emitted from the apparatus, and wherein changing the duty cycle of the at least one switch results in a change in the color temperature of the combined essentially white light. ### Claim 18 (depends on 13) The apparatus of claim 13, further comprising at least one user interface configured to vary the output of the controllable DC source. ### Claim 19 (depends on 18) The apparatus of claim 18, wherein the at least one user interface is further configured to vary at least a portion of the feedback control circuit. ### Claim 20 (depends on 19) The apparatus of claim 19, wherein an operation of the at least one user interface simultaneously varies the output of the controllable DC source and the at least a portion of the feedback control circuit.