Bidirectional LED Light Sheet with Printed Conductors
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Solution Overview
Problem
High-power LEDs used in solid state lighting generate excessive heat and are costly due to complex packaging, making them expensive for high-output applications like fluorescent light fixtures, and existing light sheets are not bidirectional, limiting lighting effects in environments.
Innovation Solution
Bidirectional light sheets are created by sandwiching bare LED chips between substrates with conductors, allowing for series connections without wires and alternate orientations to emit light in two directions, with reflective and transparent layers to direct light, and can be oriented non-parallel to ceilings for customizable lighting effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If high-power LEDs are used for solid state lighting, then luminous efficacy is improved (100-200 lumens/watt), but cost and packaging complexity increase significantly
Solution Approach 1:
The invention divides the lighting system into modular light sheets containing arrays of small LED chips. Each light sheet is a self-contained module with integrated conductors and substrates, allowing independent fabrication and assembly. This segmentation reduces the packaging complexity of individual LEDs while maintaining high overall luminous efficacy through arrays of multiple chips.
Solution Approach 2:
The invention replaces expensive packaged high-power LEDs with arrays of inexpensive bare LED chips. By using cheap individual chips that can be mass-produced and directly mounted on substrates with printed conductors, the system achieves cost-effective lighting without requiring complex packaging for each high-power LED unit.
2Ease of manufacture
If arrays of bare LED chips are sandwiched between substrates with conductors, then cost is reduced, but light emission is unidirectional rather than bidirectional
Solution Approach 1:
The invention introduces asymmetry in LED chip orientation within the light sheet array. By alternating the orientation of adjacent LED chips, the system achieves bidirectional light emission from a single planar structure. This asymmetric arrangement allows light to be emitted in opposite directions simultaneously, providing versatility for different mounting and illumination configurations while maintaining cost-effective bare chip construction.
Solution Approach 2:
The invention transitions from conventional unidirectional light emission to bidirectional emission by utilizing the planar dimension of the light sheet. Instead of emitting light in one direction from a point source, the alternating LED orientations create two opposing light-emitting surfaces, effectively using the sheet's dimensional structure to provide multi-directional illumination capability.
3Ease of operation
If light sheets are oriented parallel to the floor, then conventional illumination is achieved, but glare control and aesthetic lighting effects are limited
Solution Approach 1:
The invention enables dynamic orientation of light sheets at various angles including vertical mounting perpendicular to the ceiling. This dynamic positioning capability allows the same light sheet technology to adapt to different installation requirements and lighting scenarios, providing both conventional parallel illumination and alternative angled or vertical configurations for glare control and aesthetic effects.
Solution Approach 2:
The light sheet design achieves multi-functionality by being capable of operating in multiple orientations and configurations. A single light sheet can be installed parallel to the floor for conventional illumination, angled for specific lighting zones, or mounted vertically for glare-free overhead lighting, making the technology universally applicable to diverse lighting needs without requiring specialized designs for each application.
4Illumination intensity
If vertical LEDs with reflective bottom electrodes are used, then light emission from top surface is improved, but bidirectional emission requires complex wire connections
Solution Approach 1:
The invention extracts the wire connection requirement entirely from the system by using printed conductors on substrates to make direct electrical contact with LED chip electrodes. This eliminates the need for individual wire bonds or solder connections, reducing assembly complexity and enabling automated manufacturing while maintaining effective electrical connectivity for bidirectional LED arrays.
Solution Approach 2:
The invention replaces the mechanical wire connection system with a planar conductor pattern system printed on flexible or rigid substrates. Instead of using physical wires to connect LED electrodes, the conductive traces on the substrate provide electrical pathways, substituting a complex mechanical wiring system with a simpler two-dimensional conductive network that facilitates bidirectional LED operation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution reduces costs and complexity by enabling efficient, bidirectional light emission that can be customized for various lighting effects, including uniform illumination of floors and ceilings, while avoiding glare and achieving high lumen output.
Implementation Method 1
an array of bare light emitting diode (LED) chips, having top electrodes and bottom electrodes, are sandwiched between two or more substrates having conductors formed on their surfaces
Implementation Method 2
The conductors may connect any number of LEDs in series and are ultimately connected to a power source
Implementation Method 3
The bottom electrode of commercially available vertical LEDs is reflective and covers the entire bottom surface of the LED
Implementation Method 4
Reflectors (e.g., prisms) in the substrates may be used to direct any side light toward the desired light output surface of the sheet
Implementation Method 5
The top electrode is intended by the LED manufacturer to be bonded to a thin wire using ultrasonic bonding or other bonding technique
Data Source
AI summary
A bidirectional light sheet including at least first and second arrays of bare LED chips having top and bottom electrodes, where the arrays of LEDs are sandwiched between at least two transparent substrates having conductors bonded to the electrodes without wires, forming light sheets to emit light from opposite surfaces of the light sheet to create a bidirectional light sheet. The light sheet may be suspended from a ceiling to be non-parallel to the ceiling A reflector or a plurality of lenses may be included in the light sheet to emit light at any peak intensity angle to achieve a predetermined light emission pattern.