LCD Source Driver Level Shifter for AC/DC Common Voltage Output
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Solution Overview
Problem
Conventional source drivers for liquid crystal displays are not compatible for generating AC and DC common voltages due to the limitations of existing level shifters, which can only shift signals within specific voltage ranges and not across multiple ranges.
Innovation Solution
A level shifter with an input stage, middle stage, and output stage that generates signals across two voltage ranges, allowing the source driver to produce both AC and DC common voltages by using logic signals and reference sources to control output signals through switches and digital-to-analog conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional level shifters are used to shift signals within specific voltage ranges, then the level shifter can operate reliably within its designed voltage range, but the source driver cannot be compatible for generating both AC and DC common voltages
Solution Approach 1:
The level shifter is designed with dual output capabilities to perform multiple functions. The output stage can generate first output signals with voltages between first positive and first negative output source voltages at a first output terminal, or second output signals with voltages between second positive and second negative output source voltages at a second output terminal. This allows a single level shifter to support both AC common voltage generation (using first output signals) and DC common voltage generation (using second output signals), eliminating the need for separate level shifters for each function.
2Adaptability or versatility
If separate level shifters are used for AC and DC common voltage generation, then each level shifter can be optimized for its specific voltage range, but the source driver requires different hardware structures for different voltage generation modes
Solution Approach 1:
The patent combines the functionality of separate level shifters into a single integrated level shifter. The middle stage generates both first logic signals and second logic signals, which are then used by the output stage to generate either first output signals or second output signals. This merging eliminates hardware structure differences between AC and DC common voltage generation modes, as the same level shifter hardware can be configured to generate either type of output based on the logic signals provided.
Data Source
AI summary
A level shifter for a source driver of a liquid crystal display is provided. The level shifter includes: an input stage for generating a signal with a voltage of between a positive input source voltage and a negative input source voltage according to an input logic; a middle stage for generating a first logic signal and a second logic signal according to the signal; and an output stage, for generating a first output signal with a voltage of between a first positive output source voltage and a first negative output source voltage at a first output terminal or a second output signal with a voltage of between a second positive output source voltage and a second negative output source voltage at a second output terminal according to the first logic signal and the second logic signal.