Display Power Management via Interlaced Sub-Frame Refresh
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Solution Overview
Problem
Existing power management methods for displays fail to effectively reduce energy consumption and minimize flicker during low refresh rates, as the source driver remains active during time intervals between frames, leading to inconsistent capacitance and noticeable flicker.
Innovation Solution
The method involves interlaced refreshing of sub-frames by classifying scan lines into groups and modulating control signals to turn the source driver on/off during specific periods, shortening time intervals in pulse timing distributions, and dynamically adjusting the number of refreshing periods based on image content differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the refresh rate is reduced from 60 Hz to 5 Hz to reduce workload and energy consumption, then energy savings are achieved, but the source driver remains in standby status during time intervals between frames causing limited energy savings and noticeable flicker due to TFT leakage current
Solution Approach 1:
The frame is divided into two sub-frames (first sub-frame and second sub-frame) that are displayed alternately during the same time period. This segmentation allows the display to maintain visual continuity and reduce flicker while operating at a lower refresh rate, thereby achieving energy savings without compromising display quality
Solution Approach 2:
The source driver is periodically turned on and off in synchronization with the alternating display of first and second sub-frames. By enabling the source driver only during the display period of each sub-frame and disabling it during the alternate period, energy consumption is significantly reduced while the periodic refresh maintains image stability and minimizes flicker
2Use of energy by moving object
If the refresh rate is reduced to save energy, then energy consumption decreases, but the sustaining time of a single frame becomes longer leading to inconsistent capacitance and voltage of the liquid crystal
Solution Approach 1:
The original frame is segmented into two sub-frames that are displayed alternately within the same time period. This segmentation effectively halves the sustaining time for each sub-frame compared to displaying a single frame for the entire period, thereby maintaining more consistent capacitance and voltage levels in the liquid crystal while still achieving energy savings through the reduced overall refresh rate
Solution Approach 2:
By periodically refreshing the display with alternating first and second sub-frames, the system maintains liquid crystal stability through more frequent updates than a single frame would provide at the same average refresh rate. This periodic refresh pattern ensures that capacitance and voltage remain consistent while energy consumption is reduced compared to maintaining a single frame for the extended period
3Loss of energy
If the source driver is kept in standby status during time intervals between frames at low refresh rate, then some energy is saved, but the energy savings are still limited and the display flicker becomes more obvious
Solution Approach 1:
The display period is segmented into alternating intervals for first sub-frame and second sub-frame. By displaying one sub-frame while the source driver is enabled and then switching to the other sub-frame with the source driver disabled, the system achieves substantial energy savings while the rapid alternation prevents visible flicker
Solution Approach 2:
The source driver is periodically enabled and disabled in sync with the alternating sub-frame display. This periodic operation allows the driver to remain active only when needed for displaying a sub-frame and remain inactive during the alternate sub-frame period, maximizing energy savings while maintaining display stability and minimizing flicker through the rapid periodic refresh
Data Source
AI summary
A power management method and a power management device for a display are disclosed, including: comparing contents in an original frame image with contents in a previous image to generate a plurality of successive second periods with first stages and second stages, shortening a plurality of time intervals in the first pulse timing distribution and outputting the first pulse timing distribution for displaying a first sub-frame image on the display during the first stage of one of the plurality of successive second periods, and shortening a plurality of time intervals in the second pulse timing distribution and outputting the second pulse timing distribution for displaying a second sub-frame image on the display during the first stage of the other one of the plurality of successive second periods; and turning off the driving circuit of the display in the second stages.