Display Device Variable Refresh Rate Without Frame Memory
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Solution Overview
Problem
Display devices without frame memory cannot be driven in a variable refresh rate (VRR) in video mode, as they lack the necessary memory to adjust the driving frequency of the display panel dynamically.
Innovation Solution
The display device includes a driving controller that counts the number of pulses of the emission signal in each frame, performs frequency down or up dimming based on measurement and calculation count values, and adjusts the number of pulses in dimming frames to change the driving frequency, enabling operation in a variable refresh rate without frame memory.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a display device operates in video mode without frame memory, then real-time image data transmission is achieved, but variable refresh rate operation cannot be supported
Solution Approach 1:
The emission signal pulse count is dynamically adjusted based on the target refresh rate. The driving controller counts emission signal pulses in each frame and modifies the pulse count in subsequent frames to achieve the desired variable refresh rate, enabling dynamic frequency adjustment without frame memory
Solution Approach 2:
The driving controller measures the actual refresh rate by counting emission signal pulses and compares it with the target refresh rate. Based on this feedback, the controller adjusts the emission signal pulse count in subsequent frames to converge the actual refresh rate to the target value, enabling precise variable refresh rate control
2Use of energy by moving object
If the driving frequency is changed dynamically to achieve variable refresh rate, then power consumption is reduced at lower refresh rates, but display performance may deteriorate during frequency transitions
Solution Approach 1:
The emission signal is applied periodically with varying pulse counts across frames. By controlling the number of emission signal pulses in each frame based on target refresh rate, the system achieves variable refresh rate operation that reduces power consumption at lower frequencies while maintaining display continuity
Solution Approach 2:
The driving controller calculates the required emission signal pulse count in advance based on the target refresh rate and frame timing. This preliminary determination of pulse counts ensures smooth frequency transitions and prevents display performance deterioration during rate changes
Data Source
AI summary
A display device may perform frequency down dimming or frequency up dimming based on a measurement count value generated by counting a number of pulses of an emission signal in frame period. Accordingly, the frequency down dimming or the frequency up dimming may be possible, and the display panel may be driven in a variable refresh rate in which the driving frequency of the display panel changes without a frame memory.