Demultiplexing Device with Sample-Hold Circuits for Display Data Programming
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Solution Overview
Problem
In display devices, the use of demultiplexers to reduce the number of data drive ICs results in insufficient data programming time for pixels, particularly in organic electroluminescent displays, where data current application is reduced due to the half-horizontal period timing of analog switches.
Innovation Solution
A demultiplexing device that samples and holds data current for pixels of the same color using sample/hold circuits, allowing concurrent data current application to multiple data lines within one horizontal period, thereby maintaining data programming time without increasing the number of data drive ICs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If demultiplexers are used to reduce the number of data drive ICs, then the number of data drive ICs is reduced, but the data programming time for pixels becomes insufficient
Solution Approach 1:
The patent applies preliminary action by sampling and holding the data current before it is needed for pixel programming. The sample/hold circuit captures the data current in advance and maintains it during the programming period, ensuring sufficient programming time even when multiple data lines share a single drive IC through demultiplexing.
2Device complexity
If analog switches are used in demultiplexers to alternately transmit data signals, then the number of data drive ICs is reduced, but the data current application time is reduced to half the horizontal period
Solution Approach 1:
The patent introduces an intermediary sample/hold circuit between the demultiplexer and the data lines. This intermediary component buffers the data current, allowing the demultiplexer to operate with reduced time slots while the sample/hold circuit maintains the current level throughout the entire programming period, thus compensating for the time loss caused by demultiplexing.
Data Source
AI summary
In a display device, a demultiplexer is used to transmit a data current to a data line. The demultiplexer includes a plurality of sample/hold circuits for sampling the time-divided and sequentially input current and holding them to the data line. A plurality of data lines coupled to the demultiplexer are coupled to pixels of the same color, and hence, currents with different levels are transmitted to pixels of different colors. A sample/hold circuit for transmitting a higher level current uses a driving transistor having a larger ratio of a channel width and a channel length.