Dual-Range Source Driver Output Buffer for LCD Power Reduction
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Solution Overview
Problem
The existing output buffers in source drivers for liquid crystal displays consume high power due to the need for hundreds of buffer amplifiers to drive color LCDs, leading to inefficient energy usage.
Innovation Solution
The implementation of an output buffer system comprising an upper buffer and a lower buffer, where the upper buffer outputs a positive polarity signal over a specific voltage range and the lower buffer outputs a negative polarity signal over another range, with optimized voltage relationships to reduce power consumption, including voltage differences and common voltages to minimize power usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional output buffers are used to drive all data lines in a color LCD, then the display can be driven across the full voltage range, but power consumption becomes excessively high
Solution Approach 1:
The output buffer is divided into two separate buffers: an upper buffer for driving data lines requiring positive polarity signals (Vcom to V2) and a lower buffer for driving data lines requiring negative polarity signals (V1 to Vcom). This segmentation allows each buffer to operate within a limited voltage range, reducing power consumption while collectively covering the full display voltage range through coordinated operation.
2Use of energy by moving object
If the voltage ranges of upper and lower buffers overlap significantly, then full supply range can be covered, but power consumption increases
Solution Approach 1:
The upper buffer is configured with supply terminals at V1 and V2, while the lower buffer has supply terminals at V3 and V4, where V2>V4 and V1>V3. This creates a controlled overlap region (V2 to V4) where both buffers can operate, but each buffer primarily serves its designated voltage range. The different voltage configurations optimize power consumption in each local operating region while maintaining overall coverage.
Data Source
AI summary
An output buffer and a controlling method are disclosed. The output buffer comprises an upper buffer and a lower buffer. In the controlling method, at first, a first voltage (V1) and a second voltage (V2) are applied on the upper buffer, and a third voltage (V3) and a fourth voltage (V4) are applied on the lower buffer, wherein V1>V2, V1>V4, V3>V2, and V3>V4. Then, the upper buffer is operated to output data to a plurality of pixels thereby operating the liquid crystals of the pixels over an upper supply range, wherein the upper supply range is from V1 to V2. Thereafter, the lower buffer is operated to output data to the pixels thereby operating the liquid crystals of the pixels over a lower supply range, wherein the lower supply range is from V3 to V4.