Micro-LED Pixel Control Architecture with Shared Transistor Logic
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Solution Overview
Problem
Helmet-mounted or head-worn micro-displays require high brightness and resolution in a small area, leading to space constraints that necessitate complex control circuitry with many transistors, resulting in poor process yields and high costs due to the need for small geometry semiconductor processes.
Innovation Solution
A display architecture where two subpixel LEDs are controlled via a shared control circuit and switching element, allowing one set of brightness control transistors to control two subpixels, organizing driving and control elements into pixel units of four driving elements and three control elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If separate control circuitry is used for each subpixel to achieve high brightness and resolution, then display quality is improved, but transistor count increases leading to poor process yields and high costs
Solution Approach 1:
The patent combines the control of two green subpixels into a single control unit. The switching element receives a single green control signal and distributes it to both green subpixels, allowing one set of brightness control transistors to control two subpixels simultaneously. This merging reduces the total transistor count per pixel from 8 to 6 transistors while maintaining full display quality and color accuracy.
2Area of stationary object
If control transistors are made very small to fit within available space, then area utilization is improved, but manufacturing complexity increases due to need for small geometry semiconductor processes
Solution Approach 1:
By merging the control circuits for the two green subpixels into a single shared control unit, the patent reduces the total number of transistors that need to be fabricated. This reduction in transistor count directly decreases the total area required for control circuitry, allowing the use of larger, more manufacturable transistor geometries without compromising display area utilization.
3Ease of manufacture
If a shared control circuit is used to reduce transistor count, then manufacturing cost is improved, but control circuit complexity increases
Solution Approach 1:
The patent segments the pixel control into distinct functional units: red subpixel control, blue subpixel control, and a shared green control unit. The switching element is segmented into control logic that routes signals to appropriate subpixels. This segmentation allows the shared green control unit to handle both green subpixels efficiently without creating excessive overall complexity, as each color channel maintains its own control pathway.
Solution Approach 2:
The switching element acts as an intermediary between the single green control signal and the two green subpixels. It receives the green control signal and intelligently distributes it to the appropriate subpixel based on the current frame requirements, managing the complexity of shared control without burdening the external control logic.
4Measurement precision
If more transistors are used for fine gray scale control, then brightness control precision is improved, but process yield decreases due to high transistor count
Solution Approach 1:
The patent merges the brightness control functionality for the two green subpixels into a single control unit with shared transistors. This merging reduces the total transistor count from 8 to 6 transistors per pixel, significantly improving process yield. The shared control unit maintains full 10-bit gray scale control precision by using the same brightness control mechanism for both green subpixels, ensuring that fine gray scale control is preserved despite the reduction in transistor count.
Data Source
AI summary
In a display with subpixel LEDs, each pixel includes two subpixel LEDs controlled via a shared control circuit and switching element. Switching element logic allows one set of brightness control transistors to alternatively control two subpixels. The driving and control elements of a display backplane are organized into pixels units of four driving elements and three control elements. Each pixel may comprise two green subpixels controlled via the switching element. Alternatively, each pixel may comprise a white subpixel that only illuminates when the colored pixels are off; the green and white subpixels are controlled via the switching element.