Patent ID: 9549447
Date: 2017-01-17
CPC Classifications: A01G,H05B,Y02B

Claim:
1. A lighting circuit comprising: a primary set of light-emitting diodes to output light of a first color; a secondary set of light-emitting diodes to output light of a second color; wherein a temperature-dependent reduction in the light output of the primary set of light-emitting diodes is greater than a temperature-dependent reduction in the light output of the secondary set of light-emitting diodes; and a flux ratio fixing arrangement to maintain a substantially constant ratio between the light output of the primary set of light-emitting diodes and the light output of the secondary set of light-emitting diodes during a temperature-dependent overall reduction in light output of the primary and secondary sets of light-emitting diodes of the lighting circuit, wherein the flux ratio fixing arrangement is configured to decrease a current through light-emitting diodes of the secondary set based on a drop in forward voltage over light-emitting diodes of the primary set of light-emitting diodes, or to increase a current through the light-emitting diodes of the primary set of light-emitting diodes based on a drop in forward voltage over the light emitting diodes of the secondary set of light-emitting diodes; and wherein the flux ratio fixing arrangement comprises: