Optically Addressed Active-Matrix Pixels for Large-Substrate Signal Integrity
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Solution Overview
Problem
Existing active-matrix systems for displays and imaging devices face challenges with signal degradation due to resistive losses and parasitic capacitance, limiting control signal frequencies and operational sensitivity to voltage variations across large substrates.
Innovation Solution
An electro-optically controlled active-matrix system is introduced, featuring row wires and column light-pipes with a row controller providing electrical signals and a column controller providing optical signals, respectively, along with pixels that are capacitively coupled to both, allowing for improved frequency operation and reduced sensitivity to voltage variations through micro-transfer printed inorganic light-emitting diodes and sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If electrical signals are transmitted through row and column wires extending over large substrates, then functional devices can be controlled across the substrate, but signal degradation occurs due to wire resistance, propagation delays, and parasitic capacitance that limit control signal frequencies
Solution Approach 1:
The patent segments the control signal transmission into two independent paths: electrical signals for row selection and optical signals for column selection. This segmentation allows each signal type to be transmitted through optimized pathways, with electrical signals confined to shorter row wires and optical signals transmitted through light pipes, thereby reducing the cumulative effect of resistance and parasitic capacitance across large substrates
Solution Approach 2:
The patent introduces optical signals as an intermediary medium for column control. Instead of transmitting electrical signals through long column wires that suffer from resistance and capacitance effects, the system uses optical signals that can be transmitted through light pipes without these electrical limitations, effectively mediating the control signal transmission across large distances
2Length of stationary object
If electrical signals are transmitted over large substrates, then control is achieved across the display area, but control signal frequencies are significantly limited due to propagation delays and parasitic capacitance
Solution Approach 1:
The patent replaces the electrical signal transmission mechanism (which is limited by RC time constants and propagation delays) with an optical signal transmission mechanism for column control. Optical signals travel at the speed of light and are not subject to the same parasitic capacitance and resistance effects, enabling significantly higher control signal frequencies across large substrate areas
3Quantity of substance
If power and ground signals are distributed across large substrates through wires or conductive planes, then functional devices receive power, but voltage values vary at different locations due to resistance in the power and ground distribution network
Solution Approach 1:
The patent segments the power distribution function from the signal control function. By using separate power and ground wires dedicated solely to power distribution, independent of the signal control pathways, the system reduces voltage drops and improves voltage stability at pixel locations while maintaining efficient power delivery across large substrate areas
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 enhances the frequency of pixel operation and reduces sensitivity to supply voltage and ground signal variations, improving signal integrity and frequency capabilities in active-matrix systems.
Implementation Method 1
column light-pipes extending in a column direction disposed on the system substrate, a column controller operable to provide a respective column optical signal to each of the column light-pipes
Implementation Method 2
Each of the pixels can comprise a pixel circuit that is uniquely responsive to one of the row wires and to one of the column light-pipes, the pixel circuit operable to receive the respective row electrical signal from the row wire
Implementation Method 3
The column controller can comprise an inorganic light-emitting diode that emits light into each of the column light-pipes
Implementation Method 4
The pixel circuit can comprise an optical input circuit responsive to the respective column optical signal and an electrical input circuit responsive to the respective row electrical signal, wherein the optical input circuit comprises a light sensor
Data Source
AI summary
An electro-optically controlled active-matrix system comprises a system substrate, row wires extending in a row direction disposed on the system substrate, a row controller providing a row electrical signal to each row wire, column light-pipes extending in a column direction disposed on the system substrate, a column controller providing a column optical signal to each column light-pipe, and pixels disposed over the system substrate. Each pixel can comprise a pixel circuit that is uniquely responsive to a row wire and to a column light-pipe, the pixel circuit receiving the row electrical signal from the row wire and receiving the column optical signal from the column light-pipe. In some embodiments, column wires carrying column electrical signals extend in a column direction over the system substrate and the pixel circuit is capacitively coupled to the row wire, the column wire, or both.