US Patent No. 9,609,715

SYSTEMS FOR PROVIDING TUNABLE WHITE LIGHT WITH HIGH COLOR RENDERING


Patent No. 9,609,715
Issue Date March 28,2017
Title Systems For Providing Tunable White Light With High Color Rendering
Inventorship Raghuram L. V. Petluri, Los Angeles, CA (US)
Paul Kenneth Pickard, Los Angeles, CA (US)
Assignee EcoSense Lighting Inc., Los Angeles, CA (US)

Claim of US Patent No. 9,609,715

1. A semiconductor light emitting device comprising:
a first light emitting diode (“LED”) string that comprises a first LED that has a first recipient luminophoric medium that
comprises a first luminescent material, wherein the first LED and first luminophoric medium together emit a first unsaturated
light having a first color point within a blue color range defined by a line connecting the ccx, ccy color coordinates of
the infinity point of the Planckian locus (0.242, 0.24) and (0.12, 0.068), the Planckian locus from 4000K and infinite CCT,
the constant CCT line of 4000K, the line of purples, and the spectral locus;

a second LED string that comprises a second LED that has a second recipient luminophoric medium that comprises a second luminescent
material, wherein the second LED and second luminophoric medium together emit a second unsaturated light having a second color
point within a red color range defined by the spectral locus between the constant CCT line of 1600K and the line of purples,
the line of purples, a line connecting the ccx, ccy color coordinates (0.61, 0.21) and (0.47, 0.28), and the constant CCT
line of 1600K;

a third LED string that comprises a third LED that has a third recipient luminophoric medium that comprises a third luminescent
material, wherein the third LED and third luminophoric medium together emit a third unsaturated light having a third color
point within a yellow/green color range defined by the constant CCT line of 4600K, the Planckian locus between 4600K and 550K,
the spectral locus, and a line connecting the ccx, ccy color coordinates (0.445, 0.555) and (0.38, 0.505);

a fourth LED string that comprises a fourth LED that has a fourth recipient luminophoric medium that comprises a fourth luminescent
material, wherein the fourth LED and fourth luminophoric medium together emit a fourth unsaturated light having a fourth color
point within a cyan color range defined by a line connecting the ccx, ccy color coordinates (0.18, 0.55) and (0.27, 0.72),
the constant CCT line of 9000K, the Planckian locus between 9000K and 4600K, the constant CCT line of 4600K, and the spectral
locus;

a drive circuit that is responsive to input from one or more of an end user of the semiconductor light emitting device and
one or more sensors measuring a characteristic associated with the performance of the semiconductor light emitting device,

wherein the drive circuit is configured to adjust the relative values of first, second, third, and fourth drive currents provided
to the LEDs in the first, second, third, and fourth LED strings, respectively, to adjust a fifth color point of a fifth unsaturated
light that results from a combination of the first, second, third, and fourth unsaturated light and,

wherein the blue color range comprises a region on the 1931 CIE Chromaticity Diagram defined by a 60-step MacAdam ellipse
at 20000K, 40 points below the Planckian locus.