Source Driver Polarity Inversion via Multiplexing Switching
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Solution Overview
Problem
Conventional source drivers for liquid crystal displays (LCDs) face limitations in generating diverse signal polarity inversion patterns due to their complex circuit structures, which lead to increased circuit area and restricted variability in polarity inversion patterns, failing to provide more complex driving signal sequences.
Innovation Solution
The implementation of a source driver that utilizes a multiplexing device and a switching device to control signal transmitting routes between different signal channels, allowing digital-to-analog converting circuits to output signals of single polarity, and enabling the generation of various polarity inversion patterns by alternately switching the polarities of source driving signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the circuit structure of the digital-to-analog converting circuit is designed to support both positive and negative voltage outputs, then the polarity inversion functionality is achieved, but the circuit area is increased
Solution Approach 1:
Instead of designing the digital-to-analog converting circuit to directly output both positive and negative voltages, the invention inverts the approach by using a single-polarity DAC circuit combined with switching devices that selectively connect to different voltage lines (ELVDD or ELVSS) based on polarity control signals, thereby achieving polarity inversion without complicating the DAC circuit structure
Solution Approach 2:
The invention introduces switching devices (first and second switching devices) as intermediary components between the single-polarity DAC circuit and the output, which act as mediators to selectively connect the DAC output to different voltage references (ELVDD or ELVSS), enabling polarity inversion functionality while keeping the DAC circuit simple
2Adaptability or versatility
If switching devices are used to control signal routes of adjacent signal channels, then the polarity inversion effect is achieved, but the variety of polarity inversion patterns is limited
Solution Approach 1:
The invention segments the signal routing control into multiple independent switching devices (first switching device for odd channels, second switching device for even channels), each controlled by independent control signals, allowing flexible and independent control of polarity inversion patterns for different signal channels without increasing overall system complexity
3Device complexity
If the source driver continuously imposes electric field of specific direction on the LC cell, then the driving voltage generation is simplified, but the LC cell structure is damaged
Solution Approach 1:
The invention implements periodic polarity inversion by alternately switching the polarity of driving voltages applied to the LC cell over time, using control signals that periodically change state to switch between connecting to ELVDD or ELVSS, thereby preventing continuous unidirectional electric field exposure and extending LC cell lifespan while maintaining relatively simple driving voltage generation circuitry
Data Source
AI summary
In accordance with revealed embodiments of the present invention, a source driver is provided, which is capable of providing a variety of polarity inversion patterns of source driving signals. Additionally, due to properly utilizing a multiplexing device and a switching device, hardware architecture of the inventive source driver is no more complicated than that of the conventional source driver. As a result, the present invention provides a source driver having the greater performance than the conventional source driver without increasing hardware cost and circuitry complexity.