Organic Light Emitting Display Driving Method Sub-field Memory
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Solution Overview
Problem
In organic light emitting display devices, the increase in the number of scan lines leads to longer minimum display time, resulting in increased minimum luminance, particularly in high-resolution devices, where the existing digital driving methods struggle to efficiently manage sub-fields to prevent false contours and maintain gray linearity.
Innovation Solution
The proposed method involves dividing a single frame into multiple sub-fields with distinct address and display periods, utilizing a sub-field memory unit to selectively apply data signals to sub-pixels, and employing a time-to-bit mapping method to reduce memory capacity and prevent false contours, allowing for flexible sub-field disposition and flicker reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of scan lines is increased to achieve high resolution, then the display resolution is improved, but the minimum display time increases leading to increased minimum luminance
Solution Approach 1:
The patent segments the display time into multiple sub-fields within a single frame, allowing independent control of display periods for different gray levels. By dividing the frame into multiple sub-fields (e.g., 6 sub-fields for 6-bit gray levels), the patent enables precise control of minimum display time without increasing scan line density, thus maintaining high resolution while reducing minimum luminance.
2Illumination intensity
If the minimum display time is reduced to lower minimum luminance, then the luminance control is improved, but the gray linearity and false contour prevention become difficult to maintain
Solution Approach 1:
The patent implements dynamic control of display periods for different sub-fields, where each sub-field can have independently adjusted display time based on its binary weight. This dynamic adjustment allows the system to maintain precise gray level linearity by optimizing the display period of each sub-field according to the required gray level representation, while keeping the overall minimum display time short.
Solution Approach 2:
The patent employs feedback mechanisms through the sub-field memory structure that stores and manages data signals for multiple sub-fields. The system monitors and adjusts the display periods to ensure proper gray level representation, preventing false contours by maintaining appropriate display times for each sub-field based on the binary weight system.
3Manufacturing precision
If the display period is extended to maintain gray linearity, then the gray level representation is improved, but the minimum display time increases
Solution Approach 1:
The patent segments the gray level representation across multiple sub-fields within a single frame, where each sub-field contributes a specific binary weight to the overall gray level. This segmentation allows the system to achieve precise gray level representation through combinatorial logic rather than extending a single display period, thus maintaining short minimum display time while ensuring accurate gray linearity.
Data Source
AI summary
A method of driving an organic light emitting display device includes: receiving an image signal by sub-field with respect to a single frame comprising the N number of sub-fields (N is a natural number greater than 2) from the exterior; dividing a single sub-field into an address period and a display period and selectively calling a data signal of a single sub-field from the M number of sub-field memories (M is a natural number greater than 2); and applying the called data signal of the single sub-field to a sub-pixel.