Data Driver IC Demultiplexer Reduces Chip Area and Power
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Solution Overview
Problem
The increasing number of data lines in liquid crystal display panels leads to a rise in the number of output amplifiers needed, resulting in increased chip area and power consumption in data driver ICs, which is undesirable for mobile applications where power efficiency is crucial.
Innovation Solution
Implementing a time divisional driving method where one output amplifier drives multiple data lines by using a combination of panel-side and driver-side demultiplexers to select data lines, reducing the number of output amplifiers and control signals, and optimizing the connection between output nodes and D/A converters to minimize power consumption and effective display area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of data lines is increased to support more pixels, then the display resolution is improved, but the number of output amplifiers must be increased, resulting in increased chip area and power consumption
Solution Approach 1:
The patent divides the data line driving function into multiple segments by introducing a demultiplexer that sequentially selects and drives different data lines. Instead of having one output amplifier per data line, a single output amplifier is time-division multiplexed across multiple data lines through the demultiplexer, thereby reducing the total number of output amplifiers and chip area while maintaining the ability to drive all data lines for high-resolution displays
Solution Approach 2:
The patent implements periodic action by sequentially and repeatedly driving different data lines in time-division manner. The demultiplexer cycles through selecting different data lines in sequence, with each data line receiving its drive signal during a specific time slot. This periodic selection allows a single output amplifier to serve multiple data lines over time, reducing chip area while supporting high display resolution
2Productivity
If the number of output amplifiers is increased to drive more data lines, then the data line driving capability is improved, but the steady-state power consumption is increased
Solution Approach 1:
The patent makes a single output amplifier universal by enabling it to drive multiple different data lines through the demultiplexer. The output amplifier performs multiple functions sequentially, serving as the driver for data line 1 at one time, then data line 2 at another time, and so on. This multi-functionality allows the system to maintain full data line driving capability while using fewer output amplifiers, thereby reducing steady-state power consumption
Solution Approach 2:
The patent employs periodic action where the single output amplifier is activated in periodic time slots to drive different data lines. Instead of multiple amplifiers operating continuously in parallel, one amplifier operates periodically across multiple data lines, reducing the total power consumption while maintaining the ability to drive all necessary data lines for the display
3Productivity
If demultiplexers are integrated in the display panel to select data lines, then the time divisional driving is achieved, but the effective display area is reduced due to the throttling region
Solution Approach 1:
The patent inverts the conventional approach by placing the demultiplexer in the data driver IC rather than in the display panel. This reversal of location eliminates the need for the demultiplexer to occupy physical space within the effective display area of the panel, thereby avoiding the creation of a throttling region while still achieving time-divisional driving functionality
Data Source
AI summary
A display apparatus includes a display panel; and a data driver configured to output drive voltages from a plurality of output nodes to drive the display panel. The data driver includes a plurality of output amplifiers, each of which is configured to receive a gradation voltage corresponding to a pixel data and to output the drive voltage in response to the gradation voltage; and a driver-side demultiplexer configured to connect the plurality of output amplifiers to selection output nodes selected from among the plurality of output nodes. The display panel includes a plurality of data lines; and a panel-side demultiplexer configured to connect selection data lines selected from among the plurality of data lines with the plurality of output nodes.