LCD Timing Controller Reset Circuit for Rapid Power Cycling
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Solution Overview
Problem
Liquid crystal displays often experience reset abnormalities when turned on and off quickly due to insufficient charging time of capacitors in the timing controller, leading to improper power supply reset.
Innovation Solution
Incorporating a reset auxiliary pin and a charging control circuit with comparators and a current source switch to manage the charging of capacitors, ensuring that the reset pin and auxiliary pin voltages meet specific reference levels to control the charging process, thereby preventing reset abnormalities during rapid power transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the shutdown power-on interval is shortened to enable quick turning on and off, then the response speed is improved, but the internal logic circuit of the timing controller cannot work normally causing reset abnormality
Solution Approach 1:
The patent applies preliminary action by introducing a reset auxiliary pin that performs preliminary charging of a capacitor before the main reset operation. This preliminary charging ensures that when quick power-on occurs, the capacitor already has sufficient voltage to allow the internal logic circuit to work normally, thus preventing reset abnormality while maintaining fast response speed
Solution Approach 2:
The patent uses an intermediary approach by adding a reset auxiliary pin and associated capacitor as a mediator between the power supply and the main reset circuit. This intermediary component buffers the voltage transition and ensures stable operation of the internal logic circuit during quick power-on, resolving the contradiction between speed and reliability
2Speed
If the first capacitor C1 charges quickly through the first resistor R1, then the charging speed is improved, but the charge cannot be completely released causing abnormality when the device is rebooted
Solution Approach 1:
The patent applies segmentation by dividing the single capacitor charging/discharging function into two separate capacitors: the first capacitor C1 for normal operation and the second capacitor (connected to reset auxiliary pin) for quick power-on recovery. This segmentation allows each capacitor to be optimized for its specific function, with the second capacitor ensuring complete discharge and release of charge to prevent reboot abnormalities
Solution Approach 2:
The second capacitor connected to the reset auxiliary pin acts as an intermediary that ensures complete discharge of charge before reboot. This intermediary capacitor provides a dedicated discharge path that guarantees full release of electrical charge, preventing the abnormalities that occur when the first capacitor's charge is not completely released
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution effectively delays the reset of the power supply to prevent abnormalities during both normal and quick power transitions, ensuring stable operation by ensuring capacitors are adequately charged or discharged within predetermined times.
Implementation Method 1
a second capacitor, wherein a first end of a second resistor and a first end of the second capacitor are respectively connected to a reset auxiliary pin, and a second end of the second resistor and a second end of the second capacitor are grounded
Implementation Method 2
a first resistor and a first capacitor, wherein a first end of the first resistor and a first end of the first capacitor are respectively connected to a reset pin, and a second end of the first resistor is connected to a power supply voltage
Data Source
AI summary
Disclosed is a liquid crystal display, including: a timing controller, including a reset pin, a reset auxiliary pin, a charging circuit and a charging control circuit; a reset pin circuit; a reset auxiliary pin circuit, of which a reset auxiliary pin is externally connected to a first end of a second resistor and a first end of a second capacitor, and a second end of the second resistor and a second end of the second capacitor are grounded; wherein the charging circuit includes a current source and a current source switch, and the current source is connected to an input end of the current source switch, and an output end of the current source switch is connected to the first end of the second capacitor, and a control end of the current source switch is connected to a charging control signal.