Display Device Self-Scan Voltage Compensation
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Solution Overview
Problem
Display devices often experience tearing phenomena due to frequency mismatches between the rendering frequency of the host processor and the driving frequency of the display panel, which existing variable frame modes like Free-Sync and G-Sync aim to address but may not fully mitigate, especially concerning voltage changes at the anode electrode of light emitting elements.
Innovation Solution
A display device that adjusts its driving frequency by applying self-scan voltages to sub-pixels based on calculated ratios of grayscale values of image data, minimizing voltage changes at the anode electrode through flexible determination of self-scan voltages during both display scan and self-scan periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If variable frame mode is used to synchronize rendering frequency and driving frequency, then tearing phenomenon is reduced, but voltage changes at the anode electrode occur due to coupling with data line
Solution Approach 1:
The patent introduces a self-scan period as an intermediary time slot between display scan periods. During this self-scan period, the source driver applies self-scan voltages to data lines to compensate for voltage changes caused by coupling effects. This mediator mechanism allows the system to maintain stable anode electrode voltages while operating in variable frame mode, thus resolving the contradiction between reducing tearing and preventing voltage fluctuations.
Solution Approach 2:
The patent dynamically adjusts the self-scan voltage values based on the grayscale values of the displayed image data. By calculating the ratio of grayscale values and determining appropriate self-scan voltages, the system adapts the compensation parameters to match the actual display content. This parameter change approach enables precise compensation for coupling-induced voltage changes while maintaining the benefits of variable frame rate operation.
2Reliability
If self-scan voltages are applied to compensate voltage changes, then anode electrode stability is improved, but device complexity increases due to additional control mechanisms
Solution Approach 1:
The source driver is designed to perform multiple functions: driving data lines during display scan periods and applying self-scan voltages during self-scan periods. The timing controller also handles both normal display timing and self-scan timing generation. This multi-functionality approach allows the existing driver circuits to provide compensation without requiring entirely separate dedicated compensation hardware, thus limiting the increase in device complexity.
Solution Approach 2:
The patent implements a periodic self-scan period that alternates with display scan periods. This periodic structure allows the compensation mechanism to operate in a regular, predictable cycle rather than continuously, simplifying the control logic. The timing controller generates periodic self-scan enable signals that trigger the source driver to switch between normal data driving mode and self-scan voltage application mode, making the complex control mechanism more manageable and efficient.
Data Source
AI summary
A display device includes a display panel including a first sub-pixel which displays a first color and is connected to a first data line and a gate line, a gate driver which provides a gate signal to the gate line, a source driver which provides a data voltage to the first data line in a display scan period of a frame and provides a first self-scan voltage to the first data line in a self-scan period of the frame, and a timing controller which calculates a first ratio of each of grayscale values of first color image data for the first color of the frame and determines the first self-scan voltage based on the first ratio.