SOLID STATE LIGHTING FIXTURE WITH INCANDESCENT DIMMING CHARACTERISTICS

• US 20160128155A1
• Filed: 10/31/2014
• Published: 05/05/2016
• Est. Priority Date: 10/31/2014
• Status: Active Grant

• Current Assignee: ABL IP Holding LLC (Acuity Brands, Inc.)
• Original Assignee: Juno Manufacturing LLC (Acuity Brands, Inc.)
• Inventors: CHOWDHURY, Towfiq, PETLURI, Raghuram L.V.
• Granted Patent: US 9,867,254 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H05B 45/10 Controlling the intensity of the light
• CPC Class Codes: H05B 45/20 Controlling the colour of the light
• CPC Class Codes: H05B 45/30 Driver circuits
• CPC Class Codes: H05B 45/3577 Emulating the dimming characteristics, brightness or colour temperature of incandescent lamps
• CPC Class Codes: H05B 45/46 having LEDs disposed in parallel lines
• CPC Class Codes: H05B 47/10 Controlling the light source
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

A dimmable LED lighting system includes first, second and third types of LED light sources, and an LED driver to control the supply of current on first, second and third channels, respectively to the first, second and third types of LED light sources. The first, second and third types of LED light sources are selected according to their spectral power distribution (SPD) curves. The selected SPD curves together model a dimming color curve that is characteristic of an incandescent light source when the first, second and third types of LED light sources are separately driven with current at predefined power ratios that correspond to dimming levels over a dimming region of the dimming color curve. The dimmable LED lighting system can have a color rendering index R_a greater than 80 over the dimming region.

Claims

1. A dimmable LED lighting system comprising:

a first type of LED light source, a second type of LED light source and a third type of LED light source, each of the first, second and third types of LED light sources being selected with a different spectral power distribution (SPD) curve, the selected SPD curves together modeling a dimming color curve that is characteristic of an incandescent light source when the first, second and third types of LED light sources are driven on first, second and third channels, respectively, at predefined power ratios that correspond to dimming levels over a dimming region of the dimming color curve; and

an LED driver to control current supply on the first, second and third channel to the first, second and third types of LED light sources respectively at a power ratio from the predefined power ratios according to a selected dimming level.

2. The dimmable LED lighting system of claim 1, wherein the dimming color curve is defined by the following equation:

CCT=2920+396ln(x)+88.7ln(x)²+11.6ln(x)³

where CCT is a color correlated temperature, and

 

x is a dim percentage.

3. The dimmable LED lighting system of claim 1, wherein the first, second, and third types of LED light sources and their associated first, second and third channels have the following properties:

20≦

α

₁≦

35, 35≦

β

₁≦

58, and 1.63≦

γ

₁≦

1.79 on the first channel,

12.8≦

α

₂≦

17.85, 46≦

β

₂≦

66, and 3.6≦

γ

₂≦

3.8 on the second channel, and

7.7≦

α

₃≦

13.7, 80≦

β

₃≦

155, and 10.2≦

γ

₃≦

11.6 on the third channel,

where

S(λ

) is a function of the SPD curve which reflects spectral power versus a wavelength of an LED light source,

I₁ is {Max[S(λ

)]} in a wavelength range of 400 to 500 nm,

I₂ is {Min[S(λ

)]} in a wavelength range of 420 to 550 nm,

I₃ is {Max[S(λ

)]} in a wavelength range of 500 to 700 nm,

α

₁=I₁/I₂, β

₁=I₃/I₂ and γ

₁=I₃/I₁ on the first channel,

α

₂=I₁/I₂, β

₂=I₃/I₂ and γ

₂=I₃/I₁ on the second channel, and

α

₃=I₁/I₂, β

₃=I₃/I₂ and γ

₃=I₃/I₁ on the third channel.

4. The dimmable LED lighting system of claim 3, wherein

(1) α

₁=25, β

₁=42, or γ

₁=1.73 on the first channel,

(2) α

₂=15, β

₂=55, or γ

₂=3.65 on the second channel, or

(3) α

₃=9.5, β

₃=103, or γ

₃=10.8 on the third channel.

5. The dimmable LED lighting system of claim 1, wherein the first, second, and third types of LED light sources and their associated first, second and third channels have the following properties:

α

₁;

α

₂;

α

₃=(from 2.3 to 3.8);

(from 1.2 to 2.1);

1,

β

₁;

β

₂;

β

₃=(from 0.35 to 0.52);

(from 0.41 to 0.72);

1, and

γ

₁;

γ

₂;

γ

₃=(from 0.13 to 0.17);

(from 0.31 to 0.36);

1.

where

S(λ

) is a function of spectral power versus a wavelength of an LED light source,

I₁ is {Max[S(λ

)]} in a wavelength range of 400 to 500 nm,

I₂ is {Min[S(λ

)]} in a wavelength range of 420 to 550 nm,

I₃ is {Max[S(λ

)]} in a wavelength range of 500 to 700 nm,

α

₁=I₁/I₂, β

₁=I₃/I₂ and γ

₁=I₃/I₁ on the first channel,

α

₂=I₁/I₂, β

₂=I₃/I₂ and γ

₂=I₃/I₁ on the second channel, and

α

₃=I₁/I₂, β

₃=I₃/I₂ and γ

₃=I₃/I₁ on the third channel.

6. The dimmable LED lighting system of claim 1, wherein the first, second, and third types of LED light sources and their associated first, second and third channels have the following properties:

20≦

α

₁≦

35, 35≦

β

₁≦

58, and 1.63≦

γ

₁≦

1.79 on the first channel,

7.7≦

α

₂≦

13.7, 80≦

β

₂≦

155, and 10.2≦

γ

₂≦

11.6 on the second channel, and

the third type of LED light source is amber LED light source on the third channel,

where

I₁ is {Max[S(λ

)]} in a wavelength range of 400 to 500 nm,

I₂ is {Min[S(λ

)]} in a wavelength range of 420 to 550 nm,

I₃ is {Max[S(λ

)]} in a wavelength range of 500 to 700 nm,

α

₁=I₁/I₂, β

₁=I₃/I₂ and γ

₁=I₃/I₁ on the first channel,

α

₂=I₁/I₂, β

₂=I₃/I₂ and γ

₂=I₃/I₁ on the second channel, and

α

₃=I₁/I₂, β

₃=I₃/I₂ and γ

₃=I₃/I₁ on the third channel.

7. The dimmable LED lighting system of claim 1, wherein a color rendering index Ra is greater than 90 over the dimming region of the dimming color curve for the combination of the first, second and third types of LED light sources with one of the first, second and third types of the LED light sources on one channel having an Ra greater than 90 and the other two of the first, second and third types of LED light sources on the other channels having an Ra less than 90.

8. A method of operating an LED lighting system comprising:

providing a first type of LED light source, a second type of LED light source and a third type of LED light source, each of the first, second and third types of LED light sources being selected with different spectral power distribution (SPD) curves, the selected SPD curves together modeling a dimming color curve that is characteristic of an incandescent light source when the first, second and third type of LED light sources are driven on first, second and third channels, respectively, at predefined power ratios that correspond to predefined dimming levels over a dimming region of the dimming color curve; and

controlling current supply on the first, second and third channels to the first, second and third types of LED light sources respectively at a power ratio from the predefined power ratios according to a selected dimming level.

9. The method of claim 8, wherein the dimming color curve is defined by the following equation:

CCT=2920+396ln(x)+88.7ln(x)²+11.6ln(x)³

where CCT is a color correlated temperature, and

 

x is a dim percentage.

10. The method of claim 8, wherein the first second, and third types of LED light sources and their associated first, second and third channels have the following properties:

20≦

α

₁≦

35, 35≦

β

₁≦

58, and 1.63≦

γ

₁≦

1.79 on the first channel,

12.8≦

α

₂≦

17.85, 46≦

β

₂≦

66, and 3.6≦

γ

₂≦

3.8 on the second channel, and

7.7≦

α

₃≦

13.7, 80≦

β

₃≦

155, and 10.2≦

γ

₃≦

11.6 on the third channel,

where

S(λ

) is a function of spectral power versus a wavelength of an LED light source,

I₁ is {Max[S(λ

)]} in a wavelength range of 400 to 500 nm,

I₂ is {Min[S(λ

)]} in a wavelength range of 420 to 550 nm,

I₃ is {Max[S(λ

)]} in a wavelength range of 500 to 700 nm,

α

₁=I₁/I₂, β

₁=I₃/I₂ and γ

₁=I₃/I₁ on the first channel,

α

₂=I₁/I₂, β

₂=I₃/I₂ and γ

₂=I₃/I₁ on the second channel, and

α

₃=I₁/I₂, β

₃=I₃/I₂ and γ

₃=I₃/I₁ on the third channel.

11. The method of claim 10, wherein

α

₁=25, β

₁=42, or γ

₁=1.73 on the first channel,

α

₂=15, β

₂=55, or γ

₂=3.65 on the second channel, or

α

₃=9.5, β

₃=103, or γ

₃=10.8 on the third channel.

12. The method of claim 8, wherein the first second, and third types of LED light sources and their associated first, second and third channels have the following properties:

α

₁;

α

₂;

α

₃=(from 2.3 to 3.8);

(from 1.2 to 2.1);

1,

β

₁;

β

₂;

β

₃=(from 0.35 to 0.52);

(from 0.41 to 0.72);

1, and

γ

₁;

γ

₂;

γ

₃=(from 0.13 to 0.17);

(from 0.31 to 0.36);

1,

where

S(λ

) is a function of spectral power versus a wavelength of an LED light source,

I₁ is {Max[S(λ

)]} in a wavelength range of 400 to 500 nm,

I₂ is {Min[S(λ

)]} in a wavelength range of 420 to 550 nm,

I₃ is {Max[S(λ

)]} in a wavelength range of 500 to 700 nm,

α

₁=I₁/I₂, β

₁=I₃/I₂ and γ

₁=I₃/I₁ on the first channel,

α

₂=I₁/I₂, β

₂=I₃/I₂ and γ

₂=I₃/I₁ on the second channel, and

α

₃=I₁/I₂, β

₃=I₃/I₂ and γ

₃=I₃/I₁ on the third channel.

13. The method of claim 8, wherein the first second, and third types of LED light sources and their associated first, second and third channels have the following properties:

20≦

α

₁≦

35, 35≦

β

₁≦

58, and 1.63≦

γ

₁≦

1.79 on the first channel,

7.7≦

α

₂≦

13.7, 80≦

β

₂≦

155, and 10.2≦

γ

₂≦

11.6 on the second channel, and

the third type of LED light source is amber LED light source on the third channel,

where

I₁ is {Max[S(λ

)]} in a wavelength range of 400 to 500 nm,

I₂ is {Min[S(λ

)]} in a wavelength range of 420 to 550 nm,

I₃ is {Max[S(λ

)]} in a wavelength range of 500 to 700 nm,

α

₁=I₁/I₂, β

₁=I₃/I₂ and γ

₁=I₃/I₁ on the first channel,

α

₂=I₁/I₂, β

₂=I₃/I₂ and γ

₂=I₃/I₁ on the second channel, and

α

₃=I₁/I₂, β

₃=I₃/I₂ and γ

₃=I₃/I₁ on the third channel.

14. The method of claim 8, wherein a color rendering index Ra is greater than 90 over the dimming region of the dimming color curve for the combination of the first, second and third types of LED light sources with one of the first, second and third types of the LED light sources on one channel having an Ra greater than 90 and the other two of the first, second and third types of LED light sources on the other channels having an Ra less than 90.

15. The method of claim 8, further comprising:

updating the predefined power ratios configured on the LED driver.

16. A method of manufacturing an LED lighting system comprising:

selecting a first type of LED light source, a second type of LED light source and a third type of LED light source, each of the first, second and third types of LED light sources being selected with different spectral power distribution (SPD) curves, the selected SPD curves together modeling a dimming color curve that is characteristic of an incandescent light source when the first, second and third type of LED light sources are driven on first, second and third channels, respectively, at predefined power ratios that correspond to predefined dimming levels over a dimming region of the dimming color curve; and

configuring an LED driver to control the supply of current on the first, second and third channels to the first, second and third types of LED light sources respectively at a power ratio from the predefined power ratios according to a selected dimming level.

17. The method of claim 16, wherein the first second, and third types of LED light sources and their associated first, second and third channels have the following properties:

20≦

α

₁≦

35, 35≦

β

₁≦

58, and 1.63≦

γ

₁≦

1.79 on the first channel,

12.8≦

α

₂≦

17.85, 46≦

β

₂≦

66, and 3.6≦

γ

₂≦

3.8 on the second channel, and

7.7≦

α

₃≦

13.7, 80≦

β

₃≦

155, and 10.2≦

γ

₃≦

11.6 on the third channel,

where

S(λ

) is a function of spectral power versus a wavelength of an LED light source,

I₁ is {Max[S(λ

)]} in a wavelength range of 400 to 500 nm,

I₂ is {Min[S(λ

)]} in a wavelength range of 420 to 550 nm,

I₃ is {Max[S(λ

)]} in a wavelength range of 500 to 700 nm,

α

₁=I₁/I₂, β

₁=I₃/I₂ and γ

₁=I₃/I₁ on the first channel,

α

₂=I₁/I₂, β

₂=I₃/I₂ and γ

₂=I₃/I₁ on the second channel, and

α

₃=I₁/I₂, β

₃=I₃/I₂ and γ

₃=I₃/I₁ on the third channel.

18. The method of claim 16, wherein the first second, and third types of LED light sources and their associated first, second and third channels have the following properties:

20≦

α

₁≦

35, 35≦

β

₁≦

58, and 1.63≦

γ

₁≦

1.79 on the first channel,

7.7≦

α

₂≦

13.7, 80≦

β

₂≦

155, and 10.2≦

γ

₂≦

11.6 on the second channel, and

the third type of LED light source is amber LED light source on the third channel,

where

I₁ is {Max[S(λ

)]} in a wavelength range of 400 to 500 nm,

I₂ is {Min[S(λ

)]} in a wavelength range of 420 to 550 nm,

I₃ is {Max[S(λ

)]} in a wavelength range of 500 to 700 nm,

α

₁=I₁/I₂, β

₁=I₃/I₂ and γ

₁=I₃/I₁ on the first channel,

α

₂=I₁/I₂, β

₂=I₃/I₂ and γ

₂=I₃/I₁ on the second channel, and

α

₃=I₁/I₂, β

₃=I₃/I₂ and γ

₃=I₃/I₁ on the third channel.

19. The method of claim 16, wherein a color rendering index Ra is greater than 90 over the dimming region of the dimming color curve for the combination of the first, second and third types of LED light sources with one of the first, second and third types of the LED light sources on one channel having an Ra greater than 90 and the other two of the first, second and third types of LED light sources on the other channels having an Ra less than 90.