LCD Data Driver Precharge Circuit for IC Heating Reduction
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Solution Overview
Problem
High-resolution and large-size liquid crystal display devices experience increased heating in drive integrated circuits (ICs) due to higher driving frequencies and load amounts, leading to reliability degradation and safety hazards, primarily because the output buffer acts as a significant heating source.
Innovation Solution
A data driving apparatus for liquid crystal display devices that includes an output buffer with an input amplifier, an outputter, a control switch unit, and a mode controller, which operates in a switching mode to precharge output channels using charging and discharging currents, reducing the output current and thereby lowering the temperature of the drive IC. The apparatus selectively uses precharge voltages based on data voltage differences and gray scale conditions to minimize heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high resolution and large size LCD device is developed with increased driving frequency and load amount, then display performance is improved, but heating value of drive IC increases
Solution Approach 1:
The patent applies preliminary action by precharging the output channel before data signal output. The output buffer performs precharging operation in advance to prepare the output channel, which reduces the charging/discharging current during actual data output and thereby reduces heating of the drive IC while maintaining high resolution display performance
2Productivity
If output buffer operates with high current to drive high resolution display, then data signal output capability is improved, but output buffer becomes main heating source
Solution Approach 1:
The output buffer performs precharging operation in advance to prepare the output channel. This preliminary action reduces the amount of charging/discharging current required during actual data signal output, thereby reducing the heating value of the output buffer while maintaining its data signal output capability
Solution Approach 2:
The output buffer operates in periodic cycles alternating between precharge mode and data output mode. During precharge period, the output channel is precharged; during data output period, data signals are transmitted. This periodic operation reduces average current consumption and heating while maintaining productivity
3Productivity
If drive IC temperature increases due to high power consumption, then driving capability for high resolution display is improved, but reliability of drive IC is degraded
Solution Approach 1:
By precharging the output channel before data output, the patent reduces the peak current demand during data transmission. This preliminary preparation reduces power consumption and heating of the drive IC, thereby improving reliability while maintaining the driving capability for high resolution displays
Data Source
AI summary
A data driving apparatus for a liquid crystal display device includes an output buffer for buffering and outputting a data voltage input from a digital-analog converter, wherein the output buffer includes an input amplifier for amplifying and outputting current proportional to the data voltage, an outputter for supplying a data voltage corresponding to the input data voltage to an output channel using charging and discharging current proportional to output current from the input amplifier, a control switch unit connected between the input amplifier and the outputter, for driving the outputter in a switching mode to precharge the output channel in a precharge period prior to a data supplying period in which the outputter outputs the data voltage, and a mode controller for controlling the control switch unit in response to an input control signal.