Backlight Driving Circuit Row-by-Row Control for Motion Streak Reduction

The patent divides the backlight driving function into separate control circuits for each row of LED strings. Each row has its own driving transistor, storage capacitor, and control transistors, enabling independent row-by-row control. This segmentation allows the backlight to be divided into multiple controllable segments (rows) that can be activated sequentially to match liquid crystal response timing, thereby reducing motion streak effects while maintaining manageable circuit complexity through modular design.

The patent implements preliminary charging of storage capacitors during the liquid crystal response time before the backlight needs to be activated. The control transistors charge the storage capacitors in advance during the scan stage, so that when the display frame requires backlight illumination, the capacitors are already charged and ready to immediately drive the LED strings. This preliminary action ensures the backlight turns on precisely when needed without adding significant circuit complexity.

The patent implements periodic activation of backlight rows synchronized with the liquid crystal response cycle. Each row of backlight is activated in periodic intervals corresponding to the liquid crystal twisting and stabilizing cycles. The driving circuit uses scan signals and reset signals to create periodic charging and discharging cycles of storage capacitors, which in turn create periodic backlight illumination patterns that match the liquid crystal refresh rhythm, thereby eliminating motion streaks even at high refresh rates.

The patent transforms the static backlight-on-all-rows approach into a dynamic row-by-row activation system. The backlight driving circuit dynamically controls which rows are illuminated based on the current display frame requirements and liquid crystal response state. Control transistors dynamically charge and discharge storage capacitors to activate or deactivate specific rows at appropriate times, creating a dynamic backlight pattern that adapts to the liquid crystal twisting process and eliminates motion artifacts.

The patent segments the backlight control into independent row-specific circuits, where each row has dedicated driving and control transistors plus a storage capacitor. This segmentation enables the active matrix product to independently control each row's activation state, allowing previous rows to be turned off while new rows are turned on. The segmented architecture provides the flexibility needed for row-by-row backlight control that matches the liquid crystal display's progressive scanning and refresh operation.

The patent introduces storage capacitors as intermediary energy storage elements between the power supply and the LED strings, controlled by scan and reset signals. These capacitors act as intermediaries that can be charged during the scan stage and then discharge to drive the backlight during the display stage. This intermediary mechanism enables precise timing control of each row's backlight activation, allowing the system to turn off previous rows while turning on current rows by simply controlling which capacitors are charged and discharged at each time step.