Multi-LED Shared-Substrate Layout for Single-Supply Displays
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Solution Overview
Problem
Large-format inorganic light-emitting diode (iLED) displays face challenges with low resolution due to the need for multiple power supplies, ground connections, and control signals for each color emitter, leading to increased circuitry, wiring, and assembly costs, as well as reduced power efficiency.
Innovation Solution
A multi-LED structure with a single, unitary substrate and patterned semiconductor layers, where LEDs are electrically connected in series or parallel, sharing common layers and electrodes, allowing a single current and voltage supply for multiple emitters, reducing the number of components and connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate power supplies and control signals are provided for each color light emitter in each multi-color pixel, then each light emitter can operate efficiently at its optimal voltage and current, but the number of power supplies, lines, and connections increases three times, reducing available space and increasing costs
Solution Approach 1:
Multiple separate power supplies and control circuits for different color LEDs are merged into a single shared power supply and control system. The patent implements this by creating a multi-LED structure where red, green, and blue LEDs share common anode or cathode connections and are controlled by a single power supply through current mirror circuits that distribute appropriate currents to each LED type based on a single control signal.
Solution Approach 2:
A single power supply and control system is designed to perform multiple functions by controlling different color LEDs simultaneously. The control circuit acts as a universal controller that can drive red, green, and blue LEDs with different current requirements using the same control signal, eliminating the need for separate dedicated control circuits for each LED color.
2Device complexity
If a single power supply is used to provide power to all three different iLEDs in the full-color pixels, then the number of power supplies and connections is reduced, but excess voltage is dropped across other circuit components, increasing heat and reducing overall display system power efficiency
Solution Approach 1:
The patent changes the electrical parameters (voltage and current distribution) dynamically based on the specific LED being driven. By using current mirror circuits with different mirror ratios, the system adjusts the current magnitude for each LED color while maintaining a single power supply voltage, thereby minimizing voltage drops and heat generation in intermediate components.
Solution Approach 2:
The patent replaces traditional voltage-dropping resistor networks with current mirror circuits that use active transistor-based current regulation. This substitution eliminates the need for dissipative resistors and allows for efficient current distribution to different LEDs based on their specific electrical characteristics, significantly reducing power loss as heat.
3Manufacturing precision
If smaller iLEDs are used to achieve higher resolution displays, then display resolution improves, but the available space for circuitry and wiring is reduced, making assembly more difficult and costly
Solution Approach 1:
Multiple LED structures are merged onto a single substrate with shared electrical connections. The patent implements this by placing red, green, and blue LEDs in close proximity on the same substrate and providing them with shared anode or cathode connections, thereby reducing the total wiring space required and simplifying the assembly process for high-resolution displays.
Solution Approach 2:
The patent transitions from planar wiring arrangements to a three-dimensional integrated structure where multiple LED layers are stacked or arranged in vertical configurations. This dimensional change allows for higher resolution displays with smaller pitch while maintaining adequate space for electrical connections by utilizing vertical interconnects rather than horizontal routing.
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
Improves power efficiency and reduces circuitry and assembly costs while maintaining high resolution by enabling a single power supply for multiple emitters, facilitating smaller and more efficient LED structures.
Implementation Method 1
Inorganic light-emitting diodes are semiconductor light sources relying on p-n junctions to emit light when a suitable voltage is applied across the light-emitting diode
Implementation Method 2
The color of the light emitted from the iLED corresponds to the energy bandgap of the semiconductor. Thus, different semiconductor materials can emit different colors of light when stimulated with suitably different voltages
Data Source
AI summary
A multi-LED structure comprises a first LED and a separate second LED disposed on a common multi-LED native substrate. The LEDs each comprise a common first layer having a cantilever portion and a base portion and a common second layer having a light-emitting emission portion disposed only over the base portion. An LED electrode electrically connects the first LED to the second LED. The cantilever portion extends in a direction different from the base portion or a length of the cantilever portion is less than a distance between the emission portions of the first and second LEDs.