Pixel Electrode Multi-Charging for Low-Refresh Luminance Stability
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Solution Overview
Problem
Existing display devices experience a change in luminance when transitioning from a high-frequency image signal cycle to a low-frequency cycle due to reduced pixel charging frequency and potential image-sticking phenomena, leading to perceptible flicker and luminance fluctuations.
Innovation Solution
A display device and control method that involves charging the pixel electrode multiple times within a single frame period when transitioning from a high-frequency to a low-frequency image signal cycle, with an odd number of charges to maintain polarity reversal and reduce luminance changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the image signal writing frequency is reduced from 60 Hz to 1 Hz to save power, then power consumption is reduced, but luminance stability deteriorates due to off-state leakage in pixel TFT
Solution Approach 1:
The patent applies periodic action by performing multiple charge operations within a single frame period when operating at low frequency (1 Hz). Specifically, the drive circuit charges the pixel electrode multiple times (e.g., 3 or more times) during each frame period, creating periodic charging actions that compensate for the long intervals between frame updates. This periodic charging maintains sufficient charge levels in the pixel electrode despite the reduced overall writing frequency, thereby maintaining luminance stability while achieving power savings.
2Use of energy by moving object
If the pixel charging frequency is reduced from 60 times per second to once per second, then power consumption is reduced, but the time interval between charging operations increases causing luminance change
Solution Approach 1:
The patent applies segmentation by dividing a single frame period into multiple charging operations. Instead of performing one charge operation per frame period at 1 Hz, the drive circuit segments the frame period into multiple intervals and performs multiple charge operations (e.g., 3 or more times) within each frame period. This segmentation reduces the time interval between consecutive charging operations, compensating for the reduced frame frequency and maintaining adequate charge levels in the pixel electrode to prevent luminance degradation.
3Use of energy by moving object
If writing frequency is reduced to 1 Hz, then power efficiency is improved, but off-state leakage in pixel TFT causes charge loss and luminance reduction
Solution Approach 1:
The patent applies preliminary action by performing multiple charge operations within each frame period to proactively compensate for the charge loss that will occur due to off-state leakage. By charging the pixel electrode multiple times before the frame period ends, the system ensures that sufficient charge is maintained in the pixel electrode despite the ongoing leakage current. This preliminary charging action counteracts the expected charge loss and maintains reliable charge retention and luminance levels throughout the display operation.
Data Source
AI summary
A display device includes: a pixel electrode; a drive circuit configured to charge the pixel electrode in accordance with an image signal; and a control unit configured to control a timing when the drive circuit charges the pixel electrode, wherein, when a cycle in which the image signal is changed is changed from a first cycle to a second cycle that is longer than the first cycle, the control unit causes the drive circuit to charge the pixel electrode in accordance with an identical image signal more than once in one cycle in which the image signal is changed.