Display Panel Driver Synchronization for Variable Frame Rates
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Solution Overview
Problem
Display devices often experience a tearing phenomenon due to mismatched rendering and driving frequencies, limiting the expressible driving frequency and causing image distortions.
Innovation Solution
A display device that synchronizes its driving frequency with the input frequency of image data by starting scan operations in synchronization with input timing and delaying subsequent frames until previous frames are completed, allowing for variable frame modes and expanded expressible frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a variable frame mode is used to synchronize rendering frequency and driving frequency, then tearing phenomenon is prevented, but the expressible driving frequency is limited
Solution Approach 1:
The patent implements dynamic frame skipping where the number of frames skipped is adjusted based on the input frame rate. When input frame rate exceeds the natural refresh rate, the system dynamically calculates and applies appropriate frame skipping (e.g., skipping 1 frame out of 2, or 1 frame out of 3) to achieve precise driving frequency control. This dynamic adjustment expands the range of expressible driving frequencies beyond fixed variable frame modes.
Solution Approach 2:
The patent changes the parameter of frame skipping ratio to control driving frequency. By varying the frame skipping parameter (skipping N frames out of M total frames), the system can achieve multiple discrete driving frequencies (e.g., 30Hz, 37.5Hz, 45Hz, 52.5Hz, 60Hz, 72Hz, 90Hz) from a single fixed refresh rate capability, thereby expanding the expressible frequency range without requiring multiple physical display panels.
2Adaptability or versatility
If frame skipping is performed to expand expressible driving frequency, then more frequencies become available, but image data input timing becomes misaligned with scan operation timing
Solution Approach 1:
The patent performs preliminary frame skipping at the input data stage rather than at the display output stage. The timing controller proactively discards certain input frames before they reach the display panel, ensuring that the remaining frames are perfectly synchronized with the panel's scan operations. This preliminary action prevents timing misalignment from occurring in the first place, eliminating the need for complex real-time synchronization adjustments.
Solution Approach 2:
The timing controller acts as an intermediary between the image data source and the display panel. It receives input frames, applies frame skipping based on the target driving frequency, and outputs synchronized frames to the panel. This intermediary function decouples the input frame rate from the display refresh rate, allowing independent optimization of both while maintaining precise synchronization through the timing controller's frame rate conversion and timing adjustment capabilities.
3Reliability
If the scan operation is delayed to wait for input image data, then synchronization is improved, but frame time increases and productivity decreases
Solution Approach 1:
The system performs preliminary frame selection and skipping before the scan operation begins. The timing controller determines which frames to display and which to skip in advance, based on the target driving frequency and input frame rate. This preliminary action ensures that when frames are sent to the display panel, they are ready for immediate scanning without requiring delays or waiting, thus maintaining high productivity while achieving precise synchronization.
Solution Approach 2:
The patent implements periodic frame skipping patterns (e.g., display 1 frame, skip 1 frame, display 1 frame, skip 2 frames) that align with the display panel's periodic scan operations. By making the frame skipping periodic and predictable, the system synchronizes the display refresh with the input frame rate without introducing irregular delays, thereby maintaining consistent frame timing and high refresh productivity while achieving accurate synchronization.
Data Source
AI summary
A display device includes a display panel including pixels, and a display panel driver which starts a scan operation in synchronization with an input timing of input image data, performs the scan operation every a scan cycle in one frame, and delays a start of the scan operation of an (N+1)-th frame until the scan operation of an N-th frame ends when the input image data of the (N+1)-th frame is input during the scan operation of the N-th frame, where N is a positive integer.