Display Driving Circuit for Smooth VRR Luminance Transitions
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge in electroluminescent display devices is the perception of unnatural refresh rate changes due to variations in luminance when the refresh rate is adjusted using a variable refresh rate (VRR) mode.
Innovation Solution
The solution involves a display device with a flag unit, counter, and register units to adjust bias voltage and light emission signal values, allowing for smooth transitions in pulse width and bias voltage during refresh rate changes, using a frame-based approach to minimize luminance differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the refresh rate is changed in VRR mode, then power consumption is reduced or driving speed is adjusted, but luminance difference occurs at the change point which is perceived by viewers
Solution Approach 1:
The patent applies preliminary action by adjusting the bias voltage before the refresh rate change occurs. The bias voltage adjustment is performed in advance to compensate for the luminance difference that will occur during the refresh rate transition, thereby preventing viewers from perceiving the change.
Solution Approach 2:
The patent changes the bias voltage parameter dynamically based on the refresh rate. Different bias voltage values are applied depending on whether the display is operating at a first refresh rate or a second refresh rate, allowing the system to maintain luminance uniformity across different operating conditions.
2Illumination intensity
If the bias voltage is adjusted to compensate for luminance difference, then luminance uniformity is improved, but device complexity increases due to additional control circuits
Solution Approach 1:
The timing controller performs multiple functions: it controls the variable refresh rate, counts the frame number, determines whether it is a refresh frame or hold frame, and adjusts the bias voltage based on these conditions. By consolidating these functions into a single controller, the patent avoids adding separate dedicated circuits for each function.
Solution Approach 2:
The system uses its own internal resources (timing controller, frame counter, and existing signal lines) to perform the bias voltage adjustment function. The timing controller leverages its existing frame counting capability and refresh frame/hold frame determination logic to automatically control the bias voltage without requiring external assistance or additional independent circuits.
Data Source
AI summary
An electroluminescent display device using a variable refresh rate (VRR) mode. The occurrence of a difference in luminance at a time point of a refresh rate change is reduced, thereby preventing viewers from perceiving the change of the refresh rate.