Local Dimming Drive Circuit for Jitter-Free VRR Backlight Refresh
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Solution Overview
Problem
Conventional constant current driving solutions for display panels experience jitter and stroboscopic phenomena due to frequent adjustments in register configuration parameters to synchronize with varying vertical synchronization signals, affecting display quality.
Innovation Solution
A local dimming drive circuit that includes a dimming control circuit and a constant current drive circuit, where the dimming control circuit processes backlight brightness data to output at a fixed refresh rate greater than the vertical synchronization signal, ensuring stable backlight brightness data refresh without parameter adjustments, thus avoiding jitter and stroboscopic effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If register configuration parameters are frequently adjusted to synchronize backlight refresh rate with variable vertical synchronization signals, then frequency compatibility is improved, but backlight current jitter occurs causing stroboscopic phenomenon
Solution Approach 1:
The patent applies preliminary action by pre-configuring the backlight refresh rate to a fixed value (e.g., 165Hz) that is higher than the maximum expected vertical synchronization signal frequency. This allows the system to handle variable VRR frequencies (50Hz, 60Hz, 100Hz, 120Hz) without needing to dynamically adjust parameters, thereby avoiding jitter and stroboscopic effects while maintaining frequency compatibility across different scenarios.
2Reliability
If backlight refresh rate is fixed at a higher frequency, then stroboscopic phenomenon is eliminated, but data loss may occur if not properly synchronized
Solution Approach 1:
The patent implements feedback by having the dimming control circuit monitor the vertical synchronization signal frequency and dynamically adjust the backlight brightness data update timing. The circuit receives the VSYNC signal, determines the current VRR frequency, and synchronizes the backlight brightness data updates accordingly, ensuring that data is refreshed at appropriate intervals even when operating at a fixed high refresh rate (e.g., 165Hz), thereby preventing data loss while maintaining stability.
Data Source
AI summary
Disclosed are a local dimming drive circuit, a local dimming drive method, a local dimming drive system and an electronic equipment. The local dimming drive circuit includes: a dimming control circuit and a constant current drive circuit; the input end of the dimming control circuit is connected to the mainboard, and the output end of the dimming control circuit is connected to the input end of the constant current drive circuit, and the output end of the constant current drive circuit is connected to the backlight panel; the mainboard is configured to provide the first backlight brightness data and the first vertical synchronization signal; the dimming control circuit is configured to obtain the second backlight brightness data according to the first backlight brightness data, and output the second backlight brightness data at the refresh rate of the first vertical synchronization signal.