Pixel Memory Circuit for OLED Power Reduction
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Solution Overview
Problem
Conventional OLED display apparatuses face high power consumption due to leakage currents in transistors, which affect the retention of gate voltage and correct operation of pixels, especially in partial dimmed lit modes.
Innovation Solution
Incorporating a memory circuit within each pixel to store image data during a frame time, eliminating the need for continuous data transmission from the source driver, and implementing a mode switching circuit to switch between normal and Memory-In-Pixel modes for reduced power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If image data is continuously transmitted from the source driver to each pixel during a frame time, then the pixel circuit can maintain correct operation, but the source driver consumes additional power continuously
Solution Approach 1:
The patent applies preliminary action by having the source driver write image data to the pixel circuit memory before the frame time elapses. The memory then holds this data throughout the frame period, eliminating the need for continuous data transmission. This allows the source driver to complete its data writing task early and enter a low-power state, while the pixel circuit maintains correct operation using the pre-stored image data.
2Reliability
If leakage current compensation is implemented to maintain gate voltage, then pixel operation accuracy is improved, but power consumption increases
Solution Approach 1:
The patent extracts the data storage function from the pixel circuit and places it in a dedicated memory component within the pixel circuit. By separating the storage function (memory) from the driving function (transistor), the system can maintain gate voltage without requiring continuous compensation currents. The memory holds the image data statically, eliminating the need for continuous leakage compensation that would otherwise be required to maintain voltage levels.
3Productivity
If the source driver continuously outputs scan signals and image data, then all pixels can be updated, but power consumption increases especially in partial dimmed lit modes
Solution Approach 1:
The patent implements periodic action by having the source driver output scan signals and image data only periodically (once per frame) rather than continuously. The memory in each pixel circuit stores the image data for the entire frame period, allowing the source driver to enter a low-power state between frame updates. This periodic operation mode significantly reduces overall power consumption, especially in partial dimmed lit modes where continuous updates are not necessary.
Data Source
AI summary
A display apparatus includes a plurality of pixels. Each pixel has a light emitting unit, a memory cell, and a driving circuit. The memory cell stores an image data. The driving circuit is electrically connected with the light emitting unit and the memory cell, and drives the light emitting unit according to the image data.