OLED Pixel Circuit Voltage Variation and Flicker Control
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Solution Overview
Problem
Existing OLED devices have limited luminance and high energy consumption, with Liquid Crystal On Silicon (LCOS) devices offering higher luminance but lower contrast and higher energy usage, necessitating improved voltage variation and dynamic range in OLED pixel matrices.
Innovation Solution
An integrated device with a semiconducting substrate and active OLED pixels, featuring a first nMOS transistor with its source and substrate coupled, and a refresh circuit with nMOS and pMOS transistors, electrically insulated from each other, to enhance voltage variation and dynamic range, while reducing flicker and energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If OLED diodes are used to improve contrast and reduce energy consumption, then contrast and energy efficiency are improved, but luminance is limited and lower than LCOS devices
Solution Approach 1:
The patent changes the electrical parameters of the OLED pixel circuit by coupling the source and substrate of the first nMOS transistor together, and by electrically insulating the substrate of the first transistor from the substrate of the refresh circuit. This configuration changes the voltage distribution and allows for increased voltage variation (500-600 millivolts) across the OLED diode, thereby increasing luminance output while maintaining the energy efficiency benefits of OLED technology
2Illumination intensity
If voltage variation is increased to improve luminance, then luminance is improved, but dynamic range and flicker control become challenging
Solution Approach 1:
The patent segments the substrate into electrically isolated parts, with the substrate of the first nMOS transistor electrically insulated from the substrate of the refresh circuit. This segmentation allows independent optimization of voltage variation for luminance enhancement while maintaining stable reference potentials for flicker control. The source-substrate coupling of the first transistor further segments the voltage control, enabling 500-600 millivolt variation without compromising display stability
Solution Approach 2:
The refresh circuit, with its isolated substrate configuration, provides stable feedback control for the OLED pixel. By electrically insulating the refresh circuit substrate from the first transistor substrate, the circuit maintains consistent reference potentials that enable reliable feedback control of the OLED luminance, preventing flicker even when voltage variation is increased to 500-600 millivolts
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
The solution achieves improved voltage variation of 500-600 millivolts, increasing dynamic range and reducing flicker, enabling OLED devices to match or exceed the luminance of LCOS devices with lower energy consumption.
Implementation Method 1
devices furnished with OLED diodes have been developed
Implementation Method 2
an OLED diode and a control circuit
Data Source
AI summary
An integrated device includes a semiconducting substrate having a matrix of active pixels formed therein. Each active pixel includes an OLED diode, a first nMOS transistor having its source coupled to an anode of the OLED diode, and a refresh circuit coupled to a gate of the first nMOS transistor. The first nMOS transistor has its source and its substrate coupled together. The first nMOS transistor is situated in and on a first part of the semiconductor substrate, and the refresh circuit is situated in and on a second part of the semiconductor substrate, with the first part and the second part being electrically insulated from one another.