Display Driver Non-Emission Time Adjustment for Variable Frequency Luminance Stability
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Solution Overview
Problem
Display devices driven at variable frequencies experience luminance differences due to changes in driving transistor hysteresis, leading to visible flicker and reduced display quality when switching from one driving frequency to another.
Innovation Solution
The display device adjusts the non-emission time of the first frame period of the second driving frequency based on the non-emission time of the first frame period of the first driving frequency, and adjusts the emission duty ratio accordingly to maintain equal average luminance across frequency changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the driving frequency of the display panel is changed from a first driving frequency to a second driving frequency, then the display device can operate at variable frequencies to adapt to different usage scenarios, but a hysteresis characteristics change of the driving transistor occurs causing luminance difference and visible flicker
Solution Approach 1:
The patent adjusts the non-emission time parameter of the first frame period when the driving frequency changes from a first driving frequency to a second driving frequency. By modifying this temporal parameter, the patent compensates for the hysteresis characteristics change of the driving transistor, thereby maintaining stable luminance and preventing flicker while allowing variable frequency operation
Solution Approach 2:
The patent proactively adjusts the non-emission time of the first frame period at the moment of frequency switching from the first driving frequency to the second driving frequency. This preliminary action compensates for the hysteresis effect before it causes visible luminance instability, preventing flicker rather than correcting it after occurrence
2Stability of the object's composition
If the average luminance of the first frame period of the second driving frequency is made equal to the average luminance of the frame period of the first driving frequency, then flicker is improved, but temporary flashing becomes visible and display quality is reduced
Solution Approach 1:
The patent applies a preliminary adjustment to the non-emission time of the first frame period specifically during frequency transitions. By setting this non-emission time based on the relationship between the first and second driving frequencies, the patent prevents temporary flashing at the critical moment of transition while maintaining equal average luminance, thus resolving the contradiction between flicker reduction and flashing prevention
3Object-affected harmful factors
If the emission duty ratio of the first frame period of the second driving frequency is adjusted based on the non-emission time of the first frame period of the first driving frequency, then transient flashing is improved, but the device complexity increases due to additional control calculations
Solution Approach 1:
The patent changes the non-emission time parameter of the first frame period based on a straightforward calculation involving the first and second driving frequencies. This single parameter adjustment simplifies the control logic compared to complex multi-parameter adjustments, reducing device complexity while effectively preventing transient flashing through the emission duty ratio adjustment
Data Source
AI summary
A display device includes: a display panel including pixels; and a display panel driver which drives the display panel. When a driving frequency of the display panel is changed from a first driving frequency to a second driving frequency which is different from the first driving frequency, the display panel driver determines a non-emission time of a first frame period of the second driving frequency based on a non-emission time of a frame period of the first driving frequency.