LCD Power Switching Circuit Reducing Rush Current

The patent applies preliminary action by pre-charging the capacitor connected to the gate of the main switching transistor before activating the power supply. This pre-charging action ensures that when the transistor switches on, the gate already has the necessary voltage to control a gradual current rise rather than an instantaneous rush current, thereby protecting the LCD from aging while maintaining quick voltage application.

The patent uses an intermediary approach by introducing a capacitor and resistor network between the power supply and the LCD. This intermediary circuitry acts as a buffer that controls the rate of current delivery to the LCD, preventing direct rush current application while still enabling fast voltage establishment through controlled charging paths.

The patent extracts the residual voltage removal function from the main power switching path by using a separate discharge circuit with a dedicated switching transistor and resistor. This extracted discharge path can be activated independently to quickly drain residual voltage from the LCD without affecting the main power supply timing, enabling fast power down while maintaining operational reliability.

The patent applies preliminary action by preparing the discharge path in advance during normal operation, with the discharge transistor and resistor already in position but inactive. When power down is required, this pre-positioned discharge circuit can be immediately activated to rapidly remove residual voltage, avoiding the 20-second delay while ensuring operational reliability through controlled discharge.