Display Driving Circuit Voltage Averaging Heat Reduction
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Solution Overview
Problem
Existing driving circuits for liquid crystal display devices face issues with high power consumption, heat generation, and display characteristic deterioration due to the need for external capacitors and increased time constants when setting data line voltages to intermediate levels during polarity inversion.
Innovation Solution
A driving circuit with changeover switches and short-circuit switches that alternate gray-scale voltages between data line groups, averaging voltage values through a common node, reducing on-resistance and time constants, and using low-on-resistance switches for short-circuiting to minimize heat generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If external storage capacitor is connected to set data line voltage to intermediate level, then power consumption is reduced, but device complexity and cost increase
Solution Approach 1:
The invention extracts and eliminates the external storage capacitor from the circuit by using the inherent capacitance of the liquid crystal panel itself. The data line is short-circuited to the common electrode during polarity inversion, utilizing the liquid crystal capacitance to maintain the intermediate voltage level without requiring additional external components.
Solution Approach 2:
The liquid crystal panel's own capacitance is utilized to perform the voltage holding function that would otherwise require an external capacitor. The system serves itself by using its inherent electrical properties to achieve the desired intermediate voltage state during polarity inversion.
2Device complexity
If data lines are short-circuited without external capacitor, then device complexity is reduced, but time constant increases and voltage setting speed decreases
Solution Approach 1:
The data line is connected to the common electrode potential during polarity inversion, creating an equipotential state. This allows the data line voltage to be rapidly established at the intermediate level by equating it with the common electrode voltage, thereby reducing the time constant and improving voltage setting speed.
3Use of energy by moving object
If data lines are short-circuited through switches, then intermediate voltage is achieved, but heat is generated from on-resistance
Solution Approach 1:
The invention converts the potentially harmful heat generation from switch on-resistance into a beneficial low-resistance path by carefully selecting switch types and configurations. Low-on-resistance switches are used to minimize I²R losses, and the switching is timed to occur during polarity inversion when the liquid crystal capacitance already stores energy, reducing the overall energy dissipation.
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
The solution enables rapid setting of data line voltages to intermediate levels, reducing power consumption and heat generation while maintaining display quality by averaging voltage values between data line groups.
Implementation Method 1
a plurality of short-circuit switches for short-circuiting data line of the first data line group and data line of the second data line group to produce a plurality of short-circuited data line groups
Implementation Method 2
a changeover switch for sequentially switching between a first operation of applying a positive gray-scale voltage to a first data line group and applying a negative gray-scale voltage to a second data line group
Implementation Method 3
a plurality of common node-connected switches corresponding to the plurality of short-circuited data line groups and short-circuiting a corresponding one of the short-circuited data line groups to a common node
Data Source
AI summary
A driving circuit according to an embodiment of the invention includes: a switching unit for sequentially switching between a first operation of applying a positive gray-scale voltage to odd-numbered data lines and applying a negative gray-scale voltage to even-numbered data lines and a second operation of applying a negative gray-scale voltage to odd-numbered data lines and applying a positive gray-scale voltage to the even-numbered data lines; a plurality of short-circuit switches for short-circuiting a pair of adjacent odd-numbered data lines and a pair of adjacent even-numbered data lines to produce a plurality of pairs of short-circuited data lines in a switching period between the first operation and the second operation; and a plurality of common node-connected switches corresponding to the plurality of data line pairs and short-circuiting a corresponding one of the data line pairs to a common node.