Systems for providing tunable white light with high color rendering

• US 9,526,143 B1
• Filed: 06/03/2016
• Issued: 12/20/2016
• Est. Priority Date: 01/28/2016
• Status: Active Grant

• Current Assignee: Korrus Incorporated (MKD Electric, Inc.), Synergistic Ventures, Inc.
• Original Assignee: EcoSense Lighting Inc.
• Inventors: Petluri, Raghuram L. V., Pickard, Paul Kenneth III
• Primary Examiner(s): Owens, Douglas W
• Assistant Examiner(s): Kaiser, Syed M
• Application Number:
  US15/173,538
• Time in Patent Office: 200 Days
• Field of Search: 315/297, 315/307, 315/312, 315/149, 315/291, 315/294
• US Class Current: 1/1
• CPC Class Codes: F21K 9/00 Light sources using semiconductor devices as light-generating elements, e.g. using light-emitting diodes [LED] or lasers
• CPC Class Codes: F21Y 2113/13 comprising an assembly of point-like light sources
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: H01L 25/0753 the devices being arranged next to each other
• CPC Class Codes: H01L 25/50 Multistep manufacturing processes of assemblies consisting of devices, each device being of a type provided for in group H01L27/00 or H01L29/00 H01L21/50 takes precedence
• CPC Class Codes: H01L 2933/0041 relating to wavelength conversion elements
• CPC Class Codes: H01L 33/50 Wavelength conversion elements
• CPC Class Codes: H01L 33/504 Elements with two or more wavelength conversion materials
• CPC Class Codes: H05B 45/20 Controlling the colour of the light
• CPC Class Codes: H05B 45/24 using electrical feedback from LEDs or from LED modules
• CPC Class Codes: H05B 45/48 having LEDs organised in strings and incorporating parallel shunting devices

Abstract

The present disclosure provides systems for generating tunable white light. The systems include a plurality of LED strings that generate light with color points that fall within blue, yellow/green, red, and cyan color ranges, with each LED string being driven with a separately controllable drive current in order to tune the generated light output.

Claims

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; and

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.

2. The semiconductor light emitting device of claim 1,

wherein the LEDs in the first, second, and third LED strings comprise blue LEDs having a peak wavelength between about 405 nm and about 485 nm;

and

wherein the LEDs in the fourth LED string comprise cyan LEDs having a peak wavelength between about 485 nm and about 520 nm.

3. The semiconductor light emitting device of claim 1,

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.

4. The semiconductor light emitting device of claim 1,

wherein the red color range comprises a region on the 1931 CIE Chromaticity Diagram defined by a 20-step MacAdam ellipse at 1200K, 20 points below the Planckian locus.

5. The semiconductor light emitting device of claim 1,

wherein the yellow/green color range comprises a region on the 1931 CIE Chromaticity Diagram defined by a 16-step MacAdam ellipse at 3700K, 30 points above Planckian locus.

6. The semiconductor light emitting device of claim 1,

wherein the cyan color range comprises a region on the 1931 CIE Chromaticity Diagram defined by 30-step MacAdam ellipse at 6000K, 68 points above the Planckian locus.

7. The semiconductor light emitting device of claim 1,

wherein the drive circuit is configured to adjust the fifth color point so that it falls within a 7-step MacAdam ellipse around any point on the black body locus having a correlated color temperature between 1800K and 10000K.

8. The semiconductor light emitting device of claim 7,

wherein the light emitting device is configured to generate the fifth unsaturated light corresponding to a plurality of points along a predefined path with the light generated at each point having light with one or more of Ra≧

90, R9≧

60, and GAI_BB≧

95.

9. The semiconductor light emitting device of claim 1,

wherein the drive circuit is configured to adjust the fifth color point so that it falls within a 7-step MacAdam ellipse around any point on the black body locus having a correlated color temperature between 1800K and 6500K;

and

wherein the light emitting device is configured to generate the fifth unsaturated light corresponding to a plurality of points along a predefined path with the light generated at each point having light with one or more of Ra≧

90, R9≧

75, and GAI_BB≧

95.

10. A method of forming a light emitting apparatus, the method comprising:

providing a substrate,

mounting a first LED, a second LED, a third LED, and a fourth LED on the substrate, providing first, second, third, and fourth luminophoric mediums in illuminative communication with the first, second, third, and fourth LEDs, respectively,

wherein a combined light emitted by the first, second, third, and fourth LEDs and the first, second, third, and fourth luminophoric mediums together has a fifth color point that falls within a 7-step MacAdam ellipse around any point on the black body locus having a correlated color temperature between 1800K and 10000K,

wherein the first LED and the first luminophoric medium are configured to emit combined 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;

the second LED and the second luminophoric medium are configured to emit combined 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;

the third LED and the third luminophoric medium are configured to emit combined 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); and

the fourth LED and the fourth luminophoric medium are configured to emit combined 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.