Display Drive System Dynamic Current Routing
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Solution Overview
Problem
Conventional organic EL display devices using a current programming method suffer from luminance variations due to manufacturing variations in current conversion circuits, leading to uneven displays with bright and dark parts, which are difficult to maintain below 1% variation.
Innovation Solution
A drive system with a matrix of pixels and current conversion circuits, where a first selector circuit dynamically routes digital display signals to current conversion circuits and a second selector circuit reroutes analog currents to distribute current variations across columns, alternating the correspondence between current conversion circuits and pixel groups in each scanning period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If n pieces of current conversion circuits are formed of LSIs for converting digital display signals into currents, then the drive system can supply currents to pixel groups divided in columns, but manufacturing variations cause output current values to vary, resulting in luminance variations and uneven displays
Solution Approach 1:
The patent applies dynamic switching of current conversion circuits through selector circuits. Instead of using a fixed assignment of current conversion circuits to column groups, the system dynamically switches which current conversion circuit serves which column group during different horizontal scanning periods. This dynamic reassignment distributes manufacturing variations across different spatial locations over time, reducing visible unevenness in the display.
Solution Approach 2:
The patent changes the operational parameters of the current conversion circuits by varying their assignment to different column groups. By changing which circuit serves which column group dynamically, the system alters the effective output characteristics across the display over time, transforming the static manufacturing variation problem into a dynamic distribution problem that averages out the variations.
2Device complexity
If the same current conversion circuit drives the same pixel group continuously, then the circuit design is simple, but unusually high or low output currents cause uneven displays with bright and dark parts in corresponding lines
Solution Approach 1:
The patent introduces dynamic switching between current conversion circuits and column groups using selector circuits. The correspondence relationship is changed during operation rather than being fixed, allowing the system to adapt to manufacturing variations. This dynamic approach maintains relatively simple circuit design while significantly improving display uniformity.
Solution Approach 2:
The patent creates multiple current conversion circuits that are functionally identical but physically distinct due to manufacturing variations. By having multiple copies and dynamically switching between them, the system can distribute the effects of individual circuit variations across the entire display, preventing localized unevenness from becoming visible.
Data Source
AI summary
This invention provides a drive system of a display device preventing an uneven display caused by output current values of current conversion circuits. A drive system of a display device of the invention has a plurality of pixels disposed in a matrix of m rows and n columns and having current drive elements, n pieces of current conversion circuits converting digital display signals inputted from outside into analog signals corresponding to the digital display signals, a first selector circuit selectively supplying the digital display signals to the n pieces of the current conversion circuits, and a second selector circuit selectively supplying current outputs of n pieces of the current conversion circuits to pixel groups divided in columns.