Display Pixel Memory Using PCM for Low-Frequency Data Retention
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Solution Overview
Problem
OLED displays experience current leakage in storage capacitors at low frequencies, leading to changes in pixel values and increased power consumption due to continuous data voltage writing on static screens.
Innovation Solution
Replace storage capacitors with phase change memory (PCM) having non-volatile characteristics to store pixel data voltage, allowing maintenance of desired grayscale even at low scan rates and reducing power consumption by skipping continuous write operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the storage capacitor magnitude is increased to prevent current leakage, then the data voltage stability is improved, but the pixel area is increased
Solution Approach 1:
The patent changes the fundamental parameter of storage from volatile capacitor to non-volatile memory, eliminating the need for large capacitor magnitude to maintain data voltage stability. The non-volatile memory inherently retains data without continuous power, so the storage element can be much smaller while maintaining reliability.
Solution Approach 2:
The patent introduces a separate non-volatile memory component that copies and stores the data voltage information from the traditional storage capacitor. This allows the original capacitor to be reduced in size while the memory retains the data, effectively decoupling the storage function from the display function.
2Measurement precision
If continuous write operations are performed to maintain pixel values, then the display accuracy is improved, but the power consumption is increased
Solution Approach 1:
Instead of continuous write operations, the patent uses periodic updates only when frame content changes. The non-volatile memory retains data between frames, so writes are performed only when necessary (at frame start or when content changes), dramatically reducing power consumption while maintaining display accuracy.
Solution Approach 2:
The non-volatile memory performs self-service by automatically retaining data voltage information without requiring continuous power or refresh operations. The memory inherently maintains the pixel data, eliminating the need for continuous write operations and associated power consumption.
3Duration of action of stationary object
If additional storage capacitors are disposed to compensate for current leakage, then the data retention is improved, but the device complexity is increased
Solution Approach 1:
The patent extracts the data retention function from the pixel-level storage capacitor and relocates it to a dedicated non-volatile memory component. This separation allows the pixel circuit to remain simple while the memory handles the complex data retention function externally.
Solution Approach 2:
The non-volatile memory acts as an intermediary between the display driver and the pixel storage capacitor. It mediates the data transfer by storing data voltage information and providing it to the capacitor only when needed, simplifying the overall system architecture.
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
Maintains pixel data voltage across multiple frames, reduces power consumption, and minimizes latency in data storage and retrieval operations, particularly beneficial for VR and AR devices.
Implementation Method 1
a storage capacitor may be replaced with a display storage (e.g., phase change memory (PCM)) having a non-volatile characteristic
Data Source
AI summary
An electronic device may include: a display in which a plurality of pixels are arranged; a display storage in which are arranged a plurality of pixel memories storing data voltage information for lighting the plurality of pixels; a display driver IC (DDI) that operates the display and the display storage; a processor that controls the operation of the display driver; and a memory operatively connected to the processor. The memory may include instructions for storing data voltage information in the display storage and loading the stored data voltage information during one frame period when executed by the processor. Various other embodiments are also possible.