Light distribution using tapered waveguides in LED-based tubular lamps as replacements of linear fluorescent lamps

• US 20120002436A1
• Filed: 06/30/2011
• Published: 01/05/2012
• Est. Priority Date: 07/02/2010
• Status: Active Grant

• Current Assignee: Khan, Mujibun Nisa
• Original Assignee: Khan, Mujibun Nisa
• Inventors: Khan, Mujibun Nisa
• Granted Patent: US 8,348,467 B2
• Time in Patent Office: Days
• US Class Current: 362/555
• CPC Class Codes: F21K 9/61 using light guides
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]

Abstract

An LED replacement-lamp design concept comprising tapered waveguides to provide uniform and effective light distribution is disclosed. Currently, most LED-based replacement lamps for linear fluorescent lamps (LFLs) place discrete surface mount LEDs directly on a cylindrical base. This produces non-uniform, directional light that cannot illuminate large spaces as effectively as LFLs can. A design of an LED lamp with a semi-circle cross-section is proposed as a replacement for LFLs that get placed against the ceiling or some blocking surface. The flat back side of the proposed lamp is used to place a heat-sink. The design comprises of discrete LED chips or modules arranged on a board, where light from these modules are guided through tapered waveguides to create broad, uniform illumination over the entire curved surface of the lamp cover, which may be either transparent or translucent. The lamp'"'"'s light is uniformly distributed in many directions, effectively illuminating large spaces.

Claims

1. An LED-lamp replacement unit design, for replacing LFLs or Tx'"'"'s, generally comprising:

a. Any construction that uses LEDs with optical waveguides or “

lightpipes”

to diffuse any light from the LED light source via any optical waveguide to produce broad area illumination. Substantially uniform surface illumination from this proposed LED-based lamp design is expected as opposed to existing methods that place LED modules directly on the illumination surface, which produces more concentrated and directed light. Any construction that uses LEDs with optical waveguides or lightpipes will be referred to as “

LED-waveguide ensemble”

in all the descriptions that follow from here on.

b. In the LED-waveguide ensemble, any construction that uses LEDs on a plane or any other shaped-base and extends light from the LED sources in a diffused and broad manner using optical waveguides of certain length and width. The base on which LEDs are placed includes a planar substrate or may include any base that may be square, rectangular, or any non regular shape or size.

c. In the LED-waveguide ensemble, any optical waveguides that use constant width or variable width for both core and cladding for broadening the light distribution from the LED source or sources.

d. In the LED-waveguide ensemble, any optical waveguides that may use different length for different LED sources for directing the source light to an arbitrary shape lamp surface.

e. In the LED-waveguide ensemble, any optical waveguides that use materials such as plastic, glass, polymer, or any other solid or liquid material.

f. In the LED-waveguide ensemble, any optical waveguides that may be optical fibers since optical fibers are technically waveguides. The optical waveguide used in the proposed configuration may include multimode or single mode waveguides of any size. The shape of these optical waveguides may comprise straight or any curved shape to direct light to various physical locations.

g. In the LED-waveguide ensemble, any optical waveguide that terminate seamlessly on the lamp surface to avoid any surface darkness or dark spots. The seamless termination may include appropriate tapering of the waveguide width and shaping the front-ends of the waveguides using any curve or flat structures necessary.

2. An LED-based tubular lamp comprising a D-shaped cross-section as opposed to a circular cross-section that is used in fluorescent tubular lamps. The resulting structure of the proposed lamp then has a flat surface on one side and a semi-circular shape on the other side.

3. An LED-based replacement lamp for LFLs that use the flat surface against the ceiling that is non-illuminating.

4. An LED-based replacement lamp for LFLs that use the flat surface to attach a suitable heat-sink to provide effective thermal management.

5. An LED-based replacement lamp for LFLs that embeds or inserts the heat-sink on the flat surface into the ceiling so that it is not visible from below the ceiling where illumination is provided within the living space.

6. An LED-based replacement lamp for LFLs that use either transparent or translucent lamp cover.

7. An LED-based replacement lamp for LFLs that uses either LED chips or modules discrete light sources. The LEDs may be either surface-emitting or edge-emitting structures.

8. An LED-based replacement lamp for LFLs that uses white or single-color (e.g., red, blue, green, etc.) light sources. The LED modules discussed in this invention may be made using inorganic or organic semiconductors. The organic semiconductor LEDs are also known as OLEDs.