Systems for providing tunable white light with high color rendering

• US 10,602,583 B2
• Filed: 07/30/2018
• Issued: 03/24/2020
• Est. Priority Date: 01/28/2016
• Status: Active Grant

• Current Assignee: Korrus Incorporated (MKD Electric, Inc.)
• Original Assignee: EcoSense Lighting Inc.
• Inventors: Petluri, Raghuram L. V., Pickard, Paul Kenneth
• Primary Examiner(s): Chai, Raymond R
• Application Number:
  US16/049,086
• Publication Number:
  US 20190059138A1
• Time in Patent Office: 603 Days
• 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 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, and

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 first luminophoric medium together emit a first unsaturated light having a first spectral power distribution having spectral power distribution intensity of between 27.0 and 65.1 for the wavelength range of 501 nm to 600 nm, between 24.8 and 46.4 for the wavelength range of 601 nm to 700 nm, and between 1.1 and 6.8 for the wavelength range of 701 nm to 780 nm, relative to a value of 100.0 for the wavelength range of 380 nm to 500 nm;

wherein the second LED and second luminophoric medium together emit a second unsaturated light having a second spectral power distribution having spectral power distribution intensity of between 3.3 and 17.4 for the wavelength range of 380 nm to 500 nm, between 8.9 and 24.8 for the wavelength range of 501 nm to 600 nm, and between 1.1 and 18.1 for the wavelength range of 701 nm to 780 nm, relative to a value of 100.0 for the wavelength range of 601 nm to 700 nm;

wherein the third LED and third luminophoric medium together emit a third unsaturated light having a third spectral power distribution having spectral power distribution intensity of between 2.4 and 35.8 for the wavelength range of 380 nm to 500 nm, between 61.2 and 142.0 for the wavelength range of 601 nm to 700 nm, and between 7.9 and 21.1 for the wavelength range of 701 nm to 780 nm, relative to a value of 100.0 for the wavelength range of 501 nm to 600 nm; and

wherein the fourth LED and fourth luminophoric medium together emit a fourth unsaturated light having a fourth spectral power distribution having spectral power distribution intensity of between 19.9 and 32.2 for the wavelength range of 380 nm to 500 nm, between 14.7 and 42.4 for the wavelength range of 601 nm to 700 nm, and between 1.3 and 6.1 for the wavelength range of 701 nm to 780 nm, relative to a value of 100.0 for the wavelength range of 501 nm to 600 nm.

2. The method of claim 1, wherein:

the first, second, and third LEDs and first, second, and third luminophoric mediums are provided as phosphor-coated blue light emitting device chips; and

the fourth LED and fourth luminophoric medium are provided as a phosphor-coated cyan light emitting device chip.

3. The method of claim 1, wherein the first, second, third, and fourth luminophoric mediums are provided in positions remotely located from the first, second, third, and fourth LEDs.

4. The method of claim 1,

wherein the first spectral power distribution has a spectral power distribution intensity of between 0.3 and 8.1 for the wavelength range of 380-420 nm, between 20.9 and 196.1 for the wavelength range of 461-500 nm, between 15.2 and 35.6 for the wavelength range of 501-540 nm, between 25.3 and 40.5 for the wavelength range of 541-580 nm, between 26.3 and 70 for the wavelength range of 581-620 nm, between 15.4 and 80.2 for the wavelength range of 621-660 nm, between 5.9 and 20.4 for the wavelength range of 661-700 nm, between 2.3 and 7.8 for the wavelength range of 701-740 nm, and between 1.0 and 2.3 for the wavelength range of 741-780 nm, relative to a value of 100.0 for the wavelength range of 421-460 nm;

wherein the second spectral power distribution has a spectral power distribution intensity of between 0 and 14.8 for the wavelength range of 380-420 nm, between 2.1 and 157.8 for the wavelength range of 421-460 nm, between 2.0 and 6.7 for the wavelength range of 461-500 nm, between 1.4 and 12.2 for the wavelength range of 501-540 nm, between 8.7 and 20.5 for the wavelength range of 541-580 nm, between 48.5 and 102.8 for the wavelength range of 581-620 nm, between 1.8 and 74.3 for the wavelength range of 661-700 nm, between 0.5 and 29.5 for the wavelength range of 701-740 nm, and between 0.3 and 9.0 for the wavelength range of 741-780 nm, relative to a value of 100.0 for the wavelength range of 621-660 nm;

wherein the third spectral power distribution has a spectral power distribution intensity of between 0.0 and 1.1 for the wavelength range of 380-420 nm, between 1.0 and 25.3 for the wavelength range of 421-460 nm, between 4.2 and 52.7 for the wavelength range of 461-500 nm, between 56.6 and 77.5 for the wavelength range of 501-540 nm, between 80.5 and 123.4 for the wavelength range of 581-620 nm, between 48.4 and 144.9 for the wavelength range of 621-660 nm, between 12.6 and 88.8 for the wavelength range of 661-700 nm, between 3.2 and 34.4 for the wavelength range of 701-740 nm, and between 1.0 and 10.5 for the wavelength range of 741-780 nm, relative to a value of 100.0 for the wavelength range of 541-580 nm; and

wherein the fourth spectral power distribution has a spectral power distribution intensity of between 0.1 and 0.7 for the wavelength range of 380-420 nm, between 0.5 and 1.6 for the wavelength range of 421-460 nm, between 39.6 and 58.6 for the wavelength range of 461-500 nm, between 62.0 and 80.4 for the wavelength range of 541-580 nm, between 41.6 and 59.9 for the wavelength range of 581-620 nm, between 23.1 and 57.1 for the wavelength range of 621-660 nm, between 6.6 and 35.0 for the wavelength range of 661-700 nm, between 1.8 and 13.5 for the wavelength range of 701-740 nm, between 0.6 and 4.1 for the wavelength range of 741-780 nm, relative to a value of 100.0 for the wavelength range of 501-540 nm.

5. 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 spectral power distribution having spectral power distribution intensity of between 27.0 and 65.1 for the wavelength range of 501 nm to 600 nm, between 24.8 and 46.4 for the wavelength range of 601 nm to 700 nm, and between 1.1 and 6.8 for the wavelength range of 701 nm to 780 nm, relative to a value of 100.0 for the wavelength range of 380 nm to 500 nm;

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 spectral power distribution having spectral power distribution intensity of between 3.3 and 17.4 for the wavelength range of 380 nm to 500 nm, between 8.9 and 24.8 for the wavelength range of 501 nm to 600 nm, and between 1.1 and 18.1 for the wavelength range of 701 nm to 780 nm, relative to a value of 100.0 for the wavelength range of 601 nm to 700 nm;

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 spectral power distribution having spectral power distribution intensity of between 2.4 and 35.8 for the wavelength range of 380 nm to 500 nm, between 61.2 and 142.0 for the wavelength range of 601 nm to 700 nm, and between 7.9 and 21.1 for the wavelength range of 701 nm to 780 nm, relative to a value of 100.0 for the wavelength range of 501 nm to 600 nm;

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 spectral power distribution having spectral power distribution intensity of between 19.9 and 32.2 for the wavelength range of 380 nm to 500 nm, between 14.7 and 42.4 for the wavelength range of 601 nm to 700 nm, and between 1.3 and 6.1 for the wavelength range of 701 nm to 780 nm, relative to a value of 100.0 for the wavelength range of 501 nm to 600 nm; and

a drive circuit 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.

6. The semiconductor light emitting device of claim 5,

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.

7. The semiconductor light emitting device of claim 5,

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 5,

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. The semiconductor light emitting device of claim 5,

wherein the first spectral power distribution has a spectral power distribution intensity of between 0.3 and 8.1 for the wavelength range of 380-420 nm, between 20.9 and 196.1 for the wavelength range of 461-500 nm, between 15.2 and 35.6 for the wavelength range of 501-540 nm, between 25.3 and 40.5 for the wavelength range of 541-580 nm, between 26.3 and 70 for the wavelength range of 581-620 nm, between 15.4 and 80.2 for the wavelength range of 621-660 nm, between 5.9 and 20.4 for the wavelength range of 661-700 nm, between 2.3 and 7.8 for the wavelength range of 701-740 nm, and between 1.0 and 2.3 for the wavelength range of 741-780 nm, relative to a value of 100.0 for the wavelength range of 421-460 nm.

11. The semiconductor light emitting device of claim 5,

wherein the second spectral power distribution has a spectral power distribution intensity of between 0 and 14.8 for the wavelength range of 380-420 nm, between 2.1 and 157.8 for the wavelength range of 421-460 nm, between 2.0 and 6.7 for the wavelength range of 461-500 nm, between 1.4 and 12.2 for the wavelength range of 501-540 nm, between 8.7 and 20.5 for the wavelength range of 541-580 nm, between 48.5 and 102.8 for the wavelength range of 581-620 nm, between 1.8 and 74.3 for the wavelength range of 661-700 nm, between 0.5 and 29.5 for the wavelength range of 701-740 nm, and between 0.3 and 9.0 for the wavelength range of 741-780 nm, relative to a value of 100.0 for the wavelength range of 621-660 nm.

12. The semiconductor light emitting device of claim 5,

wherein the third spectral power distribution has a spectral power distribution intensity of between 0.0 and 1.1 for the wavelength range of 380-420 nm, between 1.0 and 25.3 for the wavelength range of 421-460 nm, between 4.2 and 52.7 for the wavelength range of 461-500 nm, between 56.6 and 77.5 for the wavelength range of 501-540 nm, between 80.5 and 123.4 for the wavelength range of 581-620 nm, between 48.4 and 144.9 for the wavelength range of 621-660 nm, between 12.6 and 88.8 for the wavelength range of 661-700 nm, between 3.2 and 34.4 for the wavelength range of 701-740 nm, and between 1.0 and 10.5 for the wavelength range of 741-780 nm, relative to a value of 100.0 for the wavelength range of 541-580 nm.

13. The semiconductor light emitting device of claim 5,

wherein the fourth spectral power distribution has a spectral power distribution intensity of between 0.1 and 0.7 for the wavelength range of 380-420 nm, between 0.5 and 1.6 for the wavelength range of 421-460 nm, between 39.6 and 58.6 for the wavelength range of 461-500 nm, between 62.0 and 80.4 for the wavelength range of 541-580 nm, between 41.6 and 59.9 for the wavelength range of 581-620 nm, between 23.1 and 57.1 for the wavelength range of 621-660 nm, between 6.6 and 35.0 for the wavelength range of 661-700 nm, between 1.8 and 13.5 for the wavelength range of 701-740 nm, between 0.6 and 4.1 for the wavelength range of 741-780 nm, relative to a value of 100.0 for the wavelength range of 501-540 nm.

14. The semiconductor light emitting device of claim 5, wherein the drive circuit is responsive to input from one or more of a control system and one or more sensors.

15. The semiconductor light emitting device of claim 5, wherein each of the first, second, third, and fourth luminescent materials has insubstantial conductive thermal communication from each of the first, second, third, and fourth solid state emitters, respectively.

16. The semiconductor light emitting device of claim 5, wherein each of the first, second, third, and fourth luminescent materials comprises one or more phosphors.

17. The semiconductor light emitting device of claim 5, wherein each of the first, second, third, and fourth luminescent materials is spatially separated from each of the first, second, third, and fourth solid state emitters, respectively.

18. The semiconductor light emitting device of claim 5,

wherein the first spectral power distribution has a spectral power distribution intensity of between 0.3 and 8.1 for the wavelength range of 380-420 nm, between 20.9 and 196.1 for the wavelength range of 461-500 nm, between 15.2 and 35.6 for the wavelength range of 501-540 nm, between 25.3 and 40.5 for the wavelength range of 541-580 nm, between 26.3 and 70 for the wavelength range of 581-620 nm, between 15.4 and 80.2 for the wavelength range of 621-660 nm, between 5.9 and 20.4 for the wavelength range of 661-700 nm, between 2.3 and 7.8 for the wavelength range of 701-740 nm, and between 1.0 and 2.3 for the wavelength range of 741-780 nm, relative to a value of 100.0 for the wavelength range of 421-460 nm;

wherein the second spectral power distribution has a spectral power distribution intensity of between 0 and 14.8 for the wavelength range of 380-420 nm, between 2.1 and 157.8 for the wavelength range of 421-460 nm, between 2.0 and 6.7 for the wavelength range of 461-500 nm, between 1.4 and 12.2 for the wavelength range of 501-540 nm, between 8.7 and 20.5 for the wavelength range of 541-580 nm, between 48.5 and 102.8 for the wavelength range of 581-620 nm, between 1.8 and 74.3 for the wavelength range of 661-700 nm, between 0.5 and 29.5 for the wavelength range of 701-740 nm, and between 0.3 and 9.0 for the wavelength range of 741-780 nm, relative to a value of 100.0 for the wavelength range of 621-660 nm;

wherein the third spectral power distribution has a spectral power distribution intensity of between 0.0 and 1.1 for the wavelength range of 380-420 nm, between 1.0 and 25.3 for the wavelength range of 421-460 nm, between 4.2 and 52.7 for the wavelength range of 461-500 nm, between 56.6 and 77.5 for the wavelength range of 501-540 nm, between 80.5 and 123.4 for the wavelength range of 581-620 nm, between 48.4 and 144.9 for the wavelength range of 621-660 nm, between 12.6 and 88.8 for the wavelength range of 661-700 nm, between 3.2 and 34.4 for the wavelength range of 701-740 nm, and between 1.0 and 10.5 for the wavelength range of 741-780 nm, relative to a value of 100.0 for the wavelength range of 541-580 nm; and

wherein the fourth spectral power distribution has a spectral power distribution intensity of between 0.1 and 0.7 for the wavelength range of 380-420 nm, between 0.5 and 1.6 for the wavelength range of 421-460 nm, between 39.6 and 58.6 for the wavelength range of 461-500 nm, between 62.0 and 80.4 for the wavelength range of 541-580 nm, between 41.6 and 59.9 for the wavelength range of 581-620 nm, between 23.1 and 57.1 for the wavelength range of 621-660 nm, between 6.6 and 35.0 for the wavelength range of 661-700 nm, between 1.8 and 13.5 for the wavelength range of 701-740 nm, between 0.6 and 4.1 for the wavelength range of 741-780 nm, relative to a value of 100.0 for the wavelength range of 501-540 nm.

19. The semiconductor light emitting device of claim 5,

wherein the second spectral power distribution has a spectral power distribution intensity of between 0 and 14.8 for the wavelength range of 380-420 nm, between 2.1 and 157.8 for the wavelength range of 421-460 nm, between 2.0 and 6.7 for the wavelength range of 461-500 nm, between 1.4 and 12.2 for the wavelength range of 501-540 nm, between 8.7 and 20.5 for the wavelength range of 541-580 nm, between 48.5 and 102.8 for the wavelength range of 581-620 nm, between 1.8 and 74.3 for the wavelength range of 661-700 nm, between 0.5 and 29.5 for the wavelength range of 701-740 nm, and between 0.3 and 9.0 for the wavelength range of 741-780 nm, relative to a value of 100.0 for the wavelength range of 621-660 nm;

wherein the third spectral power distribution has a spectral power distribution intensity of between 0.0 and 1.1 for the wavelength range of 380-420 nm, between 1.0 and 25.3 for the wavelength range of 421-460 nm, between 4.2 and 52.7 for the wavelength range of 461-500 nm, between 56.6 and 77.5 for the wavelength range of 501-540 nm, between 80.5 and 123.4 for the wavelength range of 581-620 nm, between 48.4 and 144.9 for the wavelength range of 621-660 nm, between 12.6 and 88.8 for the wavelength range of 661-700 nm, between 3.2 and 34.4 for the wavelength range of 701-740 nm, and between 1.0 and 10.5 for the wavelength range of 741-780 nm, relative to a value of 100.0 for the wavelength range of 541-580 nm; and

wherein the fourth spectral power distribution has a spectral power distribution intensity of between 0.1 and 0.7 for the wavelength range of 380-420 nm, between 0.5 and 1.6 for the wavelength range of 421-460 nm, between 39.6 and 58.6 for the wavelength range of 461-500 nm, between 62.0 and 80.4 for the wavelength range of 541-580 nm, between 41.6 and 59.9 for the wavelength range of 581-620 nm, between 23.1 and 57.1 for the wavelength range of 621-660 nm, between 6.6 and 35.0 for the wavelength range of 661-700 nm, between 1.8 and 13.5 for the wavelength range of 701-740 nm, between 0.6 and 4.1 for the wavelength range of 741-780 nm, relative to a value of 100.0 for the wavelength range of 501-540 nm.

20. The semiconductor light emitting device of claim 5,

wherein the second spectral power distribution has a spectral power distribution intensity of between 0 and 14.8 for the wavelength range of 380-420 nm, between 2.1 and 157.8 for the wavelength range of 421-460 nm, between 2.0 and 6.7 for the wavelength range of 461-500 nm, between 1.4 and 12.2 for the wavelength range of 501-540 nm, between 8.7 and 20.5 for the wavelength range of 541-580 nm, between 48.5 and 102.8 for the wavelength range of 581-620 nm, between 1.8 and 74.3 for the wavelength range of 661-700 nm, between 0.5 and 29.5 for the wavelength range of 701-740 nm, and between 0.3 and 9.0 for the wavelength range of 741-780 nm, relative to a value of 100.0 for the wavelength range of 621-660 nm;

and

wherein the third spectral power distribution has a spectral power distribution intensity of between 0.0 and 1.1 for the wavelength range of 380-420 nm, between 1.0 and 25.3 for the wavelength range of 421-460 nm, between 4.2 and 52.7 for the wavelength range of 461-500 nm, between 56.6 and 77.5 for the wavelength range of 501-540 nm, between 80.5 and 123.4 for the wavelength range of 581-620 nm, between 48.4 and 144.9 for the wavelength range of 621-660 nm, between 12.6 and 88.8 for the wavelength range of 661-700 nm, between 3.2 and 34.4 for the wavelength range of 701-740 nm, and between 1.0 and 10.5 for the wavelength range of 741-780 nm, relative to a value of 100.0 for the wavelength range of 541-580 nm.

21. The semiconductor light emitting device of claim 5,

wherein the second spectral power distribution has a spectral power distribution intensity of between 0 and 14.8 for the wavelength range of 380-420 nm, between 2.1 and 157.8 for the wavelength range of 421-460 nm, between 2.0 and 6.7 for the wavelength range of 461-500 nm, between 1.4 and 12.2 for the wavelength range of 501-540 nm, between 8.7 and 20.5 for the wavelength range of 541-580 nm, between 48.5 and 102.8 for the wavelength range of 581-620 nm, between 1.8 and 74.3 for the wavelength range of 661-700 nm, between 0.5 and 29.5 for the wavelength range of 701-740 nm, and between 0.3 and 9.0 for the wavelength range of 741-780 nm, relative to a value of 100.0 for the wavelength range of 621-660 nm;

and

wherein the fourth spectral power distribution has a spectral power distribution intensity of between 0.1 and 0.7 for the wavelength range of 380-420 nm, between 0.5 and 1.6 for the wavelength range of 421-460 nm, between 39.6 and 58.6 for the wavelength range of 461-500 nm, between 62.0 and 80.4 for the wavelength range of 541-580 nm, between 41.6 and 59.9 for the wavelength range of 581-620 nm, between 23.1 and 57.1 for the wavelength range of 621-660 nm, between 6.6 and 35.0 for the wavelength range of 661-700 nm, between 1.8 and 13.5 for the wavelength range of 701-740 nm, between 0.6 and 4.1 for the wavelength range of 741-780 nm, relative to a value of 100.0 for the wavelength range of 501-540 nm.

22. The semiconductor light emitting device of claim 5,

wherein the third spectral power distribution has a spectral power distribution intensity of between 0.0 and 1.1 for the wavelength range of 380-420 nm, between 1.0 and 25.3 for the wavelength range of 421-460 nm, between 4.2 and 52.7 for the wavelength range of 461-500 nm, between 56.6 and 77.5 for the wavelength range of 501-540 nm, between 80.5 and 123.4 for the wavelength range of 581-620 nm, between 48.4 and 144.9 for the wavelength range of 621-660 nm, between 12.6 and 88.8 for the wavelength range of 661-700 nm, between 3.2 and 34.4 for the wavelength range of 701-740 nm, and between 1.0 and 10.5 for the wavelength range of 741-780 nm, relative to a value of 100.0 for the wavelength range of 541-580 nm;

and

wherein the fourth spectral power distribution has a spectral power distribution intensity of between 0.1 and 0.7 for the wavelength range of 380-420 nm, between 0.5 and 1.6 for the wavelength range of 421-460 nm, between 39.6 and 58.6 for the wavelength range of 461-500 nm, between 62.0 and 80.4 for the wavelength range of 541-580 nm, between 41.6 and 59.9 for the wavelength range of 581-620 nm, between 23.1 and 57.1 for the wavelength range of 621-660 nm, between 6.6 and 35.0 for the wavelength range of 661-700 nm, between 1.8 and 13.5 for the wavelength range of 701-740 nm, between 0.6 and 4.1 for the wavelength range of 741-780 nm, relative to a value of 100.0 for the wavelength range of 501-540 nm.