LCD Data Driver Pre-Charge Circuit for Thermal Management
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Solution Overview
Problem
Liquid crystal display devices face increased heating issues due to high driving frequency and voltage, leading to safety concerns such as overheating and potential fires, particularly in large-scale high-resolution applications.
Innovation Solution
A method and apparatus for driving a liquid crystal display device that utilizes pre-charge voltages to reduce the heating value of the data driver by minimizing charge and discharge currents through a charge sharing method and external pre-charge voltage source, separating the pre-charge voltage source from the data driving integrated circuit to prevent temperature increases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If driving voltage is increased to improve picture quality, then picture quality is improved, but heating value of the data driver increases
Solution Approach 1:
The patent applies preliminary action by pre-charging the data line with a first pre-charge voltage before the actual data signal is applied. This pre-charging action reduces the voltage difference that the output buffer must handle, thereby reducing the charging current and power consumption during the actual data signal transition, while still achieving the required picture quality through the subsequent data signal
2Measurement precision
If driving frequency is increased to achieve high resolution, then resolution is improved, but heating value of the data driver increases
Solution Approach 1:
The patent uses preliminary action by pre-charging the data line before each data signal transition. This reduces the actual charging current required during high-frequency operation, enabling high resolution displays to be achieved without proportionally increasing the heating value, as the output buffer operates at lower current levels
Solution Approach 2:
The patent applies parameter changes by dynamically adjusting the pre-charge voltage level and selecting different pre-charge strategies based on the data signal characteristics. This allows optimization of power consumption and heating reduction while maintaining the required resolution and driving frequency performance
3Temperature
If data driver power consumption is reduced to lower temperature, then temperature is reduced, but charging current must be optimized
Solution Approach 1:
The patent applies preliminary action by pre-charging the data line with a first pre-charge voltage before the actual data signal is applied. This pre-charging action reduces the voltage difference that the output buffer must handle, thereby reducing the charging current and power consumption during the actual data signal transition, while still achieving the required picture quality through the subsequent data signal
Solution Approach 2:
The patent uses an intermediary approach by introducing a pre-charge voltage as an intermediate step between the power supply and the data signal. This pre-charge voltage acts as a mediator that reduces the burden on the output buffer, allowing lower charging currents and reduced power consumption while maintaining proper data signal delivery
Data Source
AI summary
A method for driving a liquid crystal display is provided. In the method, a first pre-charge voltage and a second pre-charge voltage are generated from an external voltage source separated from a data driving integrated circuit. A data line is pre-charged with the first pre-charge voltage during a first period. The data line is charged to reach a target value of a first data signal during a second period. The data line is pre-charged with the second pre-charge voltage during a third period. The data line is charged to reach a target value of a second data signal during a fourth period. A liquid crystal display device is capable of reducing the heating value of a driver that drives the data line.