Adaptable Backplane for Emissive Pixel Arrays
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Solution Overview
Problem
Existing backplanes for emissive display arrays are not adaptable to drive LEDs of differing sizes efficiently, and they struggle to maintain performance across a wide range of temperatures, leading to inefficiencies and increased development costs.
Innovation Solution
A backplane design that can be adapted to drive LEDs of varying sizes by modifying a single metal layer and incorporating a via mask, along with a witness circuit and thermalized current management circuit, to ensure consistent current delivery across temperature variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed backplane design is used for emissive display arrays, then manufacturing and design are simplified, but the backplane cannot adapt to drive LEDs of differing sizes efficiently
Solution Approach 1:
The backplane design is segmented into multiple metal layers, with the top metal layer being configurable to accommodate different LED pitches. This segmentation allows the backplane to be adapted to different LED sizes by modifying only the top metal layer configuration rather than redesigning the entire backplane structure.
Solution Approach 2:
The backplane incorporates dynamic configurability through different top metal layer designs that can be selected based on the specific LED pitch requirements. This dynamic aspect allows the same backplane substrate to serve multiple applications with different LED sizes by changing the metal layer configuration.
2Reliability
If existing backplane designs are used, then development costs are reduced, but performance consistency across wide temperature ranges cannot be maintained
Solution Approach 1:
The backplane incorporates temperature compensation circuits that provide feedback mechanisms to maintain consistent current control across varying temperature ranges. These circuits monitor temperature changes and adjust operating parameters accordingly to ensure reliable performance.
Solution Approach 2:
The backplane design includes circuits that can change operating parameters such as voltage and current in response to temperature variations. This allows the system to maintain consistent LED performance across wide temperature ranges by dynamically adjusting electrical parameters.
3Productivity
If the backplane is redesigned for each LED size, then optimal performance for each application is achieved, but development costs and time increase
Solution Approach 1:
The backplane is designed with universal compatibility through a standardized substrate and configurable top metal layer that can accommodate multiple LED pitches. This multi-functionality allows a single backplane design to serve multiple applications with different LED sizes, reducing development costs while maintaining application-specific optimization.
Solution Approach 2:
The backplane incorporates pre-configured metal layer structures and via patterns that are designed in advance to accommodate different LED pitches. This preliminary preparation allows for quick adaptation to different applications without requiring complete redesigns, thereby improving development efficiency.
Data Source
AI summary
A backplane suitable to pulse width modulate an array of emissive pixels with a current that is substantially constant over a wide range of temperatures. A current control circuit provides means to provide a constant current to an array of current mirror pixel drive elements. The current control circuit comprises a thermally stable bias resistor and a thermally stable band-gap voltage source to provide thermally stable controls and a large L p-channel reference current FET with an associated large L n-channel bias FET configured to provide a reference current at a required voltage to the gate of a large L p-channel current source FET. The current control circuit and the current mirror pixel drive elements are similar circuits with one current control circuit able to control a substantial number of pixel drive elements.