Methods for combining light emitting devices in a white light emitting apparatus that mimics incandescent dimming characteristics and solid state lighting apparatus for general illumination that mimic incandescent dimming characteristics

• US 8,950,892 B2
• Filed: 03/17/2011
• Issued: 02/10/2015
• Est. Priority Date: 03/17/2011
• Status: Active Grant

• Current Assignee: CREE Led Incorporated (Smart Global Holdings Incorporated)
• Original Assignee: CREE Incorporated (Wolfspeed, Inc.)
• Inventors: Cash, Mark Charles
• Primary Examiner(s): Mai, Anh
• Assistant Examiner(s): Lee, Brenitra M
• Application Number:
  US13/050,110
• Publication Number:
  US 20120236553A1
• Time in Patent Office: 1,426 Days
• Field of Search: 362/249.02, 362/244, 362/240, 362/235, 362/227, 362/231
• US Class Current: 362/231
• CPC Class Codes: F21K 9/65 specially adapted for changing the characteristics or the distribution of the light, e.g. by adjustment of parts
• CPC Class Codes: F21V 9/40 with provision for controlling spectral properties, e.g. colour, or intensity
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: H01L 33/50 Wavelength conversion elements
• CPC Class Codes: H05B 45/20 Controlling the colour of the light
• CPC Class Codes: H05K 3/30 Assembling printed circuits with electric components, e.g. with resistor
• CPC Class Codes: Y10T 29/4913 Assembling to base an electrical component, e.g., capacitor, etc.

Abstract

A light emitting apparatus includes a first light emitting device configured to emit light having a first chromaticity point that falls within a region on a 1931 CIE Chromaticity Diagram defined by points having coordinates (0.32, 0.40), (0.36, 0.48), (0.43, 0.45), (0.42, 0.42), (0.36, 0.38), and at least two second light emitting devices, each of the at least two second light emitting devices emits light having a respective second chromaticity points that that have ccx values greater than 0.4077 and ccy values less than 0.3944 on the 1931 CIE Chromaticity Diagram. A combined light emitted by the first light emitting device and the at least two second light emitting devices has a third chromaticity point that falls within a 7-step MacAdam ellipse around a point on the black body locus having a correlated color temperature between 2700K and 6500K. The third chromaticity may shift to a more reddish chromaticity when power supplied to the light emitting devices is decreased.

Claims

1. A light emitting apparatus, comprising:

a first light emitting device configured to emit light having a first chromaticity point that falls within a region on a 1931 CIE Chromaticity Diagram that is within a 7-step MacAdam ellipse around any point in a space defined by points having coordinates (0.32, 0.40), (0.36, 0.48), (0.43, 0.45), (0.42, 0.42), (0.36, 0.38); and

at least two second light emitting devices, wherein each of the at least two second light emitting devices emits light having a respective second chromaticity points that have ccx values greater than 0.4077 and ccy values less than 0.3944 on the 1931 CIE Chromaticity Diagram;

wherein a combined light emitted by the first light emitting device and the at least two second light emitting devices has a third chromaticity point that falls within a 7-step MacAdam ellipse around a point on the black body locus having a correlated color temperature between 2700K and 6500K; and

wherein the respective second chromaticity points fall within a second region on the 1931 CIE Chromaticity Diagram defined by points having coordinates (0.4077, 0.3652), (0.4147, 0.3814), (0.4593, 0.3944), and (0.4492, 0.3772).

2. The light emitting apparatus of claim 1, wherein the respective second chromaticity points fall below a line on the 1931 CIE Chromaticity Diagram defined by points having coordinates (0.4147, 0.3814) and (0.4593, 0.3944).

3. The light emitting apparatus of claim 1, wherein the respective second chromaticity points fall outside a 7-step MacAdam ellipse around any point on the black body locus.

4. The light emitting apparatus of claim 1, wherein the respective second chromaticity points fall within one of a plurality of second regions on the 1931 CIE Chromaticity Diagram denoted regions 7R, 7U, 8R and 8U;

wherein the 7R region is defined by points having coordinates (0.4077, 0.3652), (0.4147, 0.3814), (0.4259, 0.3853), and (0.4181), (0.3688) on the 1931 CIE Chromaticity Diagram;

the 7U region is defined by points having coordinates (0.4181, 0.3688) (0.4259, 0.3853), (0.4373, 0.3893), and (0.4286, 0.3725) on the 1931 CIE Chromaticity Diagram;

the 8R region is defined by points having coordinates (0.4373, 0.3893), (0.4483, 0.3919), (0.4389, 0.3748), (0.4286, 0.3725) on the 1931 CIE Chromaticity Diagram; and

the 8U region is defined by points having coordinates (0.4483, 0.3919), (0.4593, 0.3944), (0.4492, 0.3772), (0.4389, 0.3748) on the 1931 CIE Chromaticity Diagram.

5. The light emitting apparatus of claim 1, wherein the first and at least two second light emitting devices comprise phosphor-coated blue light emitting device chips.

6. The light emitting apparatus of claim 1, wherein the third chromaticity point is within a 7-step MacAdam ellipse of a point on the black body locus having a correlated color temperature between 3000K and 4000K.

7. The light emitting apparatus of claim 1, further comprising a current supply coupled to the first light emitting device and a resistor in parallel with the first light emitting device.

8. A lighting fixture including a light emitting apparatus as recited in claim 1.

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

providing a substrate;

mounting a first light emitting device configured to emit light having ccx, cry color coordinates within an area on a 1931 CIE Chromaticity Diagram defined by points having coordinates (0.32, 0.40), (0.36, 0.48), (0.43, 0.45), (0.42, 0.42), (0.36, 0.38) on the substrate; and

mounting at least two second light emitting devices on the substrate, wherein each of the at least two second light emitting devices emits light having a respective first chromaticity point that falls outside a 10-step MacAdam ellipse around any point on the black body locus and having a respective second chromaticity points that have ccx values greater than 0.4077 and cry values less than 0.3944 on the 1931 CIE Chromaticity Diagram on the package body;

wherein a combined light emitted by the first light emitting device and the at least two second light emitting devices has a second chromaticity point that falls within a 7-step MacAdam ellipse around any point on the black body locus having a correlated color temperature between 2700K and 6500K; and

wherein the respective second chromaticity points fall within a second region on the 1931 CIE Chromaticity Diagram defined by points having coordinates (0.4077, 0.3652), (0.4147, 0.3814), (0.4593, 0.3944), and (0.4492, 0.3772).

10. The method of claim 9, wherein the respective second chromaticity points fall within one of a plurality of second regions on the 1931 CIE Chromaticity Diagram denoted regions 7R, 7U, 8R and 8U;

wherein the 7R region is defined by points having coordinates (0.4077, 0.3652), (0.4147, 0.3814), (0.4259, 0.3853), and (0.4181), (0.3688) on the 1931 CIE Chromaticity Diagram;

the 7U region is defined by points having coordinates (0.4181, 0.3688), (0.4259, 0.3853), (0.4373, 0.3893), and (0.4286, 0.3725) on the 1931 CIE Chromaticity Diagram;

the 8R region is defined by points having coordinates (0.4373, 0.3893), (0.4483, 0.3919), (0.4389, 0.3748), (0.4286, 0.3725) on the 1931 CIE Chromaticity Diagram; and

the 8U region is defined by points having coordinates (0.4483, 0.3919), (0.4593, 0.3944), (0.4492, 0.3772), (0.4389, 0.3748) on the 1931 CIE Chromaticity Diagram.

11. The method of claim 9, wherein the respective second chromaticity points have a ccx value greater than about 0.41 and a ccy value less than about 0.39 on the 1931 CIE Chromaticity Diagram.

12. The method of claim 9, wherein the first and at least two second light emitting devices comprise phosphor-coated blue light emitting device chips.

13. The method of claim 9, wherein the third chromaticity point is within a 7-step MacAdam ellipse of a point on the black body locus having a correlated color temperature between 3000K and 4000K.

14. The method of claim 9, further comprising providing a current supply and a resistor on the substrate, and coupling the current supply to the first light emitting device.

15. The method of claim 9, further comprising coupling a resistor in parallel with the first light emitting device.