Display Driver Precharging and Common Voltage Segmentation
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Solution Overview
Problem
Conventional time division driving methods for display devices, such as TFT-LCDs, result in high power consumption due to the large amount of current consumed during the driving operations of the source driver and common voltage driver.
Innovation Solution
A source driver that precharges source lines with a predetermined voltage and a common voltage driver that discretely and sequentially increases or decreases the common voltage, reducing power consumption by optimizing the voltage levels and switching sequences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional time division driving method is used for source driver and common voltage driver, then display device can be driven with standard circuit configuration, but average current consumption is high
Solution Approach 1:
The patent applies preliminary action by precharging source lines to a predetermined voltage level before the main data writing operation. This precharging step prepares the source lines in advance, reducing the voltage swing required during the actual data writing phase, thereby significantly reducing the current consumption of the source driver during horizontal scan periods.
Solution Approach 2:
The patent segments the voltage writing process into two distinct phases: a precharging phase where source lines are charged to a predetermined voltage, and a main writing phase where actual image data is written. This segmentation allows each phase to be optimized independently, with the precharging phase handling the bulk of the voltage requirement, thus reducing energy loss during the main writing operation.
2Loss of energy
If source lines are precharged with predetermined voltage and common voltage is discretely adjusted, then current consumption is reduced, but circuit complexity increases
Solution Approach 1:
The common voltage driver is configured to discretely adjust the common voltage level in advance before the source driver operates. This preliminary adjustment of common voltage to match the precharged source line voltage reduces the voltage differential during data writing, minimizing current consumption without requiring complex real-time adjustment circuits.
Solution Approach 2:
The patent implements periodic action by adjusting the common voltage at specific intervals (at the beginning of each horizontal scan period or frame period) rather than continuously. This periodic adjustment synchronized with the display refresh cycle achieves energy savings while maintaining relatively simple circuit timing control logic.
Data Source
AI summary
A source driver and a common voltage driver for a display device using a time division driving method, in which the source driver outputs an analog voltage corresponding to digital image data to a corresponding source line out of a plurality of source lines, after precharging the corresponding source line with a predetermined voltage. The common voltage driver discretely and sequentially increases or decreases the common voltage. By using the source driver and the common voltage driver, the power consumed upon driving of the display device can be reduced.