Organic Light Emitting Display Flicker Reduction via Holding Frames
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Solution Overview
Problem
Existing organic light emitting displays face issues with flicker and increased power consumption, particularly during the duty driving of controlling display luminance, which affects image quality and efficiency.
Innovation Solution
The implementation of a timing controller that introduces holding frames between writing frames, increases the toggle frequency of the emission signal during holding frames to be higher than or equal to N times the frame frequency, and adjusts the toggle frequency based on the ON duty ratio of the emission signal, while disabling certain blocks during holding frames to reduce power consumption and flicker.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If duty driving is used to control display luminance, then power consumption is reduced, but flicker occurs affecting image quality
Solution Approach 1:
The patent applies periodic action by dividing the frame period into multiple sub-frames with different emission duty ratios. Instead of using a single duty cycle, the display alternates between multiple sub-frames with varying emission patterns, creating a periodic structure that reduces flicker perception while maintaining average luminance levels and power savings.
Solution Approach 2:
The patent segments the frame period into multiple sub-frames, where each sub-frame has a different emission duty ratio. This segmentation allows the display to control luminance through multiple smaller intervals rather than a single continuous emission period, thereby reducing flicker while maintaining power efficiency.
2Object-affected harmful factors
If emission duty ratio is increased to reduce flicker, then image quality improves, but power consumption increases
Solution Approach 1:
By implementing periodic emission patterns across multiple sub-frames with varying duty ratios, the patent achieves flicker reduction without requiring a consistently high emission duty ratio. The periodic variation in emission patterns allows the display to maintain lower average power consumption while improving image quality through reduced flicker perception.
Solution Approach 2:
The patent changes the emission duty ratio parameter across different sub-frames rather than maintaining a fixed high duty ratio. By varying the duty ratio parameter periodically, the display achieves flicker reduction while keeping the average power consumption at acceptable levels.
3Speed
If data current is increased to improve writing speed, then data transmission speed improves, but drive current increases causing higher power consumption
Solution Approach 1:
The patent applies preliminary action by pre-charging data lines during non-emission periods or before data writing operations. This pre-charging prepares the data lines in advance, allowing faster data writing without requiring sustained high current levels during the actual writing process, thereby improving writing speed while controlling power consumption.
Solution Approach 2:
The patent uses periodic action by alternating between data writing operations and non-emission periods. During non-emission periods, data lines can be pre-charged or prepared without affecting the displayed image, enabling faster subsequent writing operations while maintaining lower average power consumption through the periodic on-off pattern.
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
This approach effectively reduces flicker and power consumption by optimizing the emission signal frequency and duty ratio, enhancing the operational stability and image quality of organic light emitting displays.
Implementation Method 1
When an operating voltage is applied to the anode and the cathode, a hole passing through the hole transport layer HTL and an electron passing through the electron transport layer ETL move to the emission layer EML, forming an exciton. As a result, the emission layer EML generates visible light.
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
Disclosed are an organic light emitting display which can reduce flicker, along with power consumption, and a driving method thereof. In low-power operation mode of the organic light emitting display, at least one holding frame is placed between writing frames in which image data is written, the output of the source driver is enabled during the writing frames, the output of the source driver is disabled during the holding frames, and the toggle frequency of the emission signal is increased to be higher than or equal to N times the frame frequency (N is a positive integer greater than or equal to 2) by controlling the emission driver during the holding frames. This can significantly reduce perceived flicker.