Flexible printed wiring structure for LED light engine

Patent metadata

Field	Value
Publication number	US-11073251-B2
Application number	US-201916729131-A
Country	US
Kind code	B2
Filing date	Dec 27, 2019
Priority date	Apr 23, 2019
Publication date	Jul 27, 2021
Grant date	Jul 27, 2021

Abstract

A lighting engine, system, and method of fabrication are described. The system includes a chassis with a ridge extending from a bottom that defines inner and outer cavities. A flexible printed circuit (FPC) is disposed in contact with a wall of the inner and outer cavities and on the ridge top and is connected to wiring retained within bosses in the outer cavity. LEDs are mounted on the FPC to emit light toward a center of the cavity. A light guide disposed has an edge that opposes the LEDs and receives light emitted by the LEDs. The FPC has a polyimide insulator coupled with a pressure-sensitive adhesive (PSA), a copper layer on the polyimide insulator, and a high-reflectivity white coverlay on the copper layer. Other apparatuses, systems, and methods are also disclosed.

First claim

What is claimed is:

1. A lighting system comprising:
a chassis comprising a ridge having an inner wall that forms an inner cavity, the ridge extending from a bottom of the chassis;
a flexible printed circuit (FPC) mounted on a wall of the inner cavity, the FPC having a leg that extends, for electrical contact, over a top of the ridge to an outer wall on an opposite side of the protrusion as the inner wall, the outer wall of the ridge defining an outer cavity, the inner cavity contained within the outer cavity, the FPC mounted on the ridge with the LEDs positioned to emit light toward a center of the inner cavity, wiring in the outer cavity connected to the FPC via an electrical connector, the FPC comprising:
an insulator,
an adhesive material coupled with the polyimide insulator,
a conductive layer on the insulator, the conductive layer thicker than the insulator, and
a high-reflectivity coverlay on the conductive layer; and

light emitting diodes (LEDs) mounted on the FPC to contact the conductive layer.

2. The lighting system of claim 1 , wherein:
the wiring is coupled to raised bosses within the outer cavity to retain the wiring in the outer cavity.

3. The lighting system of claim 1 , wherein:
wiring of the FPC is connected to the LEDs to allow control of at least one attribute of the LEDs, the at least one attribute including color distribution and intensity distribution of light from the LEDs.

4. The lighting system of claim 1 , wherein:
the FPC encloses a circle, and
the LEDs are disposed uniformly around the circle and configured to emit light symmetrically in all directions.

5. The lighting system of claim 4 , wherein:
the FPC comprises a first FPC formed in a first semicircle and a second FPC formed in a second semicircle, the first semicircle and the second semicircle forming the circle,
the first FPC comprises a first set of the LEDs and the second FPC comprises a second set of the LEDs, and
the wiring is to supply power to each of the first FPC and the second FPC, the wiring connected to opposite ends of each of the first FPC and the second FPC.

6. The lighting system of claim 5 , wherein:
the wiring connected to adjacent ends of the first FPC and the second FPC have different polarities.

7. The lighting system of claim 1 , wherein:
the FPC encloses a circle, and
the LEDs are disposed non-uniformly around the circle such that light from the LEDs is emitted asymmetrically.

8. The lighting system of claim 7 , wherein:
the FPC comprises a first FPC formed in a first semicircle and a second FPC formed in a second semicircle, the first semicircle and the second semicircle forming the circle,
the first FPC comprises a first set of the LEDs and the second FPC comprises a second set of the LEDs, and
the wiring is to supply power to each of the first FPC and the second FPC, the wiring connected to opposite ends of each of the first FPC and the second FPC.

9. The lighting system of claim 8 , wherein:
a first end of the first FPC is adjacent to a first end of the second FPC,
a second end of the first FPC is adjacent to a second end of the second FPC, and
the first set of the LEDs is disposed more proximate to the first end of the first FPC than to the second end of the first FPC, and the second set of the LEDs is disposed more proximate to the first end of the second FPC than to the second end of the second FPC.

10. The lighting system of claim 9 , wherein:
the first set of the LEDs and the second set of the LEDs have the same number of LEDs.

11. The lighting system of claim 8 , wherein:
the wiring connected to adjacent ends of the first FPC and the second FPC have the same polarity.

12. The lighting system of claim 8 , wherein:
a first end of the first FPC is adjacent to a first end of the second FPC,
a second end of the first FPC is adjacent to a second end of the second FPC, and
the first set of the LEDs is centered within the first FPC such that the first set of LEDs is equidistant to the first end and the second end of the first FPC, and the second set of the LEDs is centered within the second FPC such that the second set of LEDs is equidistant to the first end and the second end of the second FPC.

13. The lighting system of claim 12 , wherein:
the first set and the second set of the LEDs have the same number of LEDs.

14. The lighting system of claim 12 , wherein:
the wiring connected to adjacent ends of the first FPC and the second FPC have different polarities.

15. The lighting system of claim 1 , wherein:
the chassis has a notch formed in an outer surface, and
a cable stress reliever is snapped into the notch to provide stress relief for a cable used to support the lighting system.

16. A lighting engine comprising:
a chassis having a cavity formed therein, the cavity having an inner cavity and an outer cavity defined by a ridge extending from a bottom of the chassis, the inner cavity contained within the outer cavity;
a flexible printed circuit (FPC) mounted on a wall of the cavity with light emitting diodes (LEDs) positioned to emit light toward a center of the cavity, an outer wall of the ridge defining the outer cavity, the FPC mounted on the ridge with the LEDs positioned to emit light toward a center of the inner cavity, wiring in the outer cavity connected to the FPC via an electrical connector, the FPC comprising:
an insulator,
an adhesive coupled with the insulator,
a conductive layer on the insulator, the conductive layer being thicker than the insulator, and
a high-reflectivity coverlay on the conductive layer;

the LEDs mounted on the FPC to contact the conductive layer;
a light guide positioned within the cavity to receive light emitted by the LEDs through an edge of the light guide; and
a reflector adjacent to the light guide and configured to cover the light guide entirely, the reflector configured to reflect substantially all light incident on the reflector from the light guide back toward the light guide.

17. The lighting engine of claim 16 , wherein:
the FPC comprises FPC strips configured in a circle, and
each of the FPC strips comprises a set of the LEDs.

18. A method of fabricating a lighting system, the method comprising:
attaching a flexible printed circuit (FPC) to a wall of an inner cavity having a circular cross-section, the inner cavity formed by a ridge extending from a bottom of a metal chassis that defines the inner cavity and an outer cavity surrounding the inner cavity, the FPC having light emitting diodes (LEDs) mounted thereon such that the LEDs are positioned to emit light toward a center of the cavity, the FPC extending over and in contact with a top of the ridge to a wall in the outer cavity, the FPC comprising:
an insulator,
an adhesive coupled with the insulator,
a conductive layer on the insulator, the conductive layer being thicker than the polyimide insulator, and
a high-reflectivity coverlay on the copper layer;

connecting wiring in the outer cavity to the FPC in the outer cavity; and
coupling the wiring to raised bosses within the outer cavity to retain the wiring in the outer cavity.

19. The method of claim 18 , wherein:
attaching the FPC to the wall of the inner cavity comprises attaching semicircular FPC strips to different portions of the wall to form a circular FPC structure, each of the FPC strips comprising a set of the LEDs, and
connecting wiring in the outer cavity to the FPC in the outer cavity comprises attaching wiring to ends of each of the FPC strips, a polarity of the wiring attac

Assignees

• Lumileds Llc

Inventors

• Diana Frederic Stephane
• Teoh Seng-Hup
• Wasilko Michael

Classifications

• H10H29/14

  comprising multiple light-emitting semiconductor components · CPC title

• H10H20/857

  Interconnections, e.g. lead-frames, bond wires or solder balls · CPC title

• G02B6/0085

  Means for removing heat created by the light source from the package · CPC title

• H05K1/147

  at least one of the printed circuits being bent or folded, e.g. by using a flexible printed circuit (H05K1/148 takes precedence) · CPC title

• H05K1/0274

  Optical details, e.g. printed circuits comprising integral optical means (H05K1/0269 takes precedence; coupling light guides with opto-electronic components G02B6/42) · CPC title