Local Active Matrix Display Architecture for 100% LED Duty Cycle
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional display technologies face limitations in achieving high multiplexing ratios and optimal LED efficiency, particularly at high frame rates, due to reduced emission time and increased driving currents, which affect peak brightness and LED lifetime.
Innovation Solution
A local active matrix display architecture that combines digital driving capabilities of pixel driver chips with a thin film transistor (TFT) layer providing sample-and-hold and current source capabilities, allowing for 100% emission duty cycle and reduced driving currents, decoupling emission time from program time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional passive matrix driving is used with high multiplexing ratios, then device complexity is reduced, but LED efficiency deteriorates due to reduced emission time and increased driving currents
Solution Approach 1:
The display is divided into multiple LPM groups, with each group driven by a dedicated pixel driver chip. This segmentation allows independent optimization of each group's emission duty cycle, enabling high multiplexing ratios overall while maintaining 100% emission duty cycle within each local group, thus preserving LED efficiency without requiring complex global driving circuits
Solution Approach 2:
A TFT layer is introduced as an intermediary between the pixel driver chips and the LED matrix. The TFT layer provides sample-and-hold capability and current source functionality, acting as a mediator that decouples the emission time from program time. This allows the pixel driver chips to operate at high multiplexing ratios while the TFT layer maintains optimal current levels for LED efficiency
2Speed
If high frame rates are achieved with conventional architectures, then display quality improves, but emission time is reduced and driving currents increase, affecting peak brightness and LED lifetime
Solution Approach 1:
The TFT layer performs preliminary action by pre-charging the pixel circuits and establishing current sources before the LED emission phase. The sample-and-hold capability of the TFT layer prepares the driving conditions in advance, allowing the LEDs to emit at optimal current levels for the entire emission duration, thus maintaining emission time even at high frame rates
Solution Approach 2:
The architecture enables continuous useful action by maintaining 100% emission duty cycle within each LPM group. While the overall frame rate increases, each local group continuously emits light without interruption, ensuring that the useful emission action is sustained throughout the frame period, thereby preserving LED lifetime and peak brightness
3Reliability
If emission duty cycle is increased to maintain LED efficiency, then multiplexing ratio is limited, but device complexity and power consumption increase
Solution Approach 1:
By segmenting the LED matrix into multiple LPM groups driven by separate pixel driver chips, each group can operate at 100% emission duty cycle independently. This segmentation resolves the contradiction by allowing high multiplexing ratio at the global level (many groups) while maintaining simple driving architecture at the local level (each group is self-contained with dedicated driver and TFT circuits)
Solution Approach 2:
The pixel driver chip and TFT layer are merged into an integrated local driving unit for each LPM group. This combination consolidates the digital driving capability of the pixel driver chip with the analog sample-and-hold and current source capability of the TFT layer, creating a unified driving architecture that achieves high multiplexing ratios without increasing overall system complexity
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
Enables operation at higher multiplexing ratios with reduced power consumption and complexity, maintaining optimal LED efficiency and extending OLED and micro LED lifetimes, while facilitating larger matrix sizes and varied display panel configurations.
Implementation Method 1
the TFT layer provides sample-and-hold and current source capability per sub-pixel
Implementation Method 2
the TFT layer provides sample-and-hold and current source capability per sub-pixel
Implementation Method 3
an array of light emitting diodes on the thin film transistor layer
Implementation Method 4
an array of light emitting diodes on the thin film transistor layer
Data Source
AI summary
A local active matrix display panel, circuits and methods of operation are described. In an embodiment, a local active matrix display panel includes an array of pixel driver chip, a thin film transistor layer in electrical contact with the array of pixel driver chips, and an array of light emitting diodes electrically connected with the thin film transistor layer.