Electro-Optical Device Subfield Driving with Pixel Memory
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Solution Overview
Problem
Subfield driving methods for electro-optical devices face challenges in maintaining gradation characteristics, particularly when pixels are partially biased during a frame, leading to deterioration in displayed gradations, especially in multiple-gradation scenarios.
Innovation Solution
The method involves dividing a frame into subfields, storing gradation data in each pixel's memory, and repeatedly reading and applying voltage based on the stored data to ensure uniform gradation display, with the number and order of voltage applications corresponding to the data read, thereby enhancing gradation characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If subfield driving is used to reduce circuit scale and suppress deterioration of display quality, then circuit complexity is reduced and display quality is improved, but gradation characteristics deteriorate when pixels are partially biased during a frame
Solution Approach 1:
The frame period is divided into multiple subfields, and the pixel driving period is segmented across these subfields. By distributing the pixel on-state periods across different subfields rather than concentrating them in one subfield, the invention achieves uniform time density while maintaining the circuit scale reduction benefits of subfield driving.
Solution Approach 2:
The invention employs periodic action by repeating the pixel driving pattern across multiple subfields. The pixel is driven in an on-state during specific subfields and off-state during others, creating a periodic driving pattern that achieves both circuit simplification and uniform gradation characteristics through temporal distribution.
2Adaptability or versatility
If pixels are driven by a combination of subfields to achieve gradation display, then the number of voltage levels required is reduced, but uniformity in gradation display deteriorates due to partial bias
Solution Approach 1:
The invention achieves equipotentiality in terms of time density distribution across subfields. By carefully designing the pixel driving pattern to ensure uniform time density (the product of on-state voltage level and duration) across all subfields, the invention eliminates potential differences in gradation display uniformity that would otherwise arise from partial bias conditions.
Solution Approach 2:
The invention changes the temporal parameters of pixel driving by adjusting which subfields drive the pixel to an on-state versus off-state. This parameter change in the driving pattern ensures that the cumulative effect across all subfields produces uniform gradation display while maintaining adaptability to different voltage levels.
3Use of energy by moving object
If gradation data are written in pixel memories only when necessary, then power consumption is reduced, but gradation characteristics deteriorate due to insufficient data refresh
Solution Approach 1:
The invention applies partial action by selectively refreshing gradation data in pixel memories only for those pixels that require updates, rather than refreshing all pixels in every frame. This partial refresh approach reduces power consumption while maintaining gradation characteristics by performing the minimum necessary writing operations.
Solution Approach 2:
The pixel memories serve themselves by retaining gradation data across multiple frames without requiring continuous rewriting. The invention leverages the memory's ability to hold data, allowing the system to reduce writing operations and power consumption while maintaining display quality through intelligent detection of when data refresh is actually needed.
Data Source
AI summary
The invention enhances gradation characteristics and realizes higher quality in a picture, in the context of subfield driving using a pixel provided therein with a memory. A method of driving an electro-optical device that divides a predetermined period of time into a plurality of subfields SF5 to SF17, performs gradational display with a combination of subfields SF corresponding to gradation data, and provides a memory storing gradation data that is provided in each of a plurality of pixels is disclosed. In the method, at least part of gradation data is written in a memory provided in each of pixels. Further, data written in the memory are repeatedly read several times based on gradation signals defining each of the subfields SF, and a voltage having time density corresponding to read data is repeatedly applied to the pixels to thereby perform gradational display in accordance with gradation data.