Organic Light Emitting Display Driver Using Common Current Source
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Solution Overview
Problem
The manufacturing cost of organic light emitting display drivers is increased due to the need for separate current sources for each column line, leading to inefficiencies in the generation and application of drive currents.
Innovation Solution
A method where column lines are grouped and a common current source is used to apply drive currents in a time-division manner, with charge switches and voltage retaining circuits to preliminarily charge pixels, reducing the number of current sources and improving efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate current sources are used for each column line, then the drive current can be continuously applied to maintain light emission, but the manufacturing cost and device complexity increase
Solution Approach 1:
Multiple column lines are grouped together and share a common current source. The data driver is divided into multiple data driver units, each controlling a group of column lines. This merging approach reduces the total number of current sources needed, thereby reducing manufacturing cost and device complexity while maintaining proper drive current application to each pixel group.
Solution Approach 2:
The display panel is divided into multiple pixel groups, where each group corresponds to a specific region controlled by a data driver unit. By segmenting the overall system into manageable units, the patent achieves cost-effective driving without requiring a separate current source for every single column line across the entire display.
2Ease of manufacture
If a common current source is used for multiple column lines, then the manufacturing cost decreases, but the drive current application becomes less efficient
Solution Approach 1:
The patent employs time-division multiplexing where drive currents are applied periodically to different pixel groups in sequence. Each data driver unit activates its corresponding column line group during specific time intervals, ensuring that all pixels receive adequate drive current over time while sharing common current sources. This periodic action maintains manufacturing cost benefits while improving overall system efficiency.
3Ease of manufacture
If drive current is intermittently applied to reduce cost, then the manufacturing cost decreases, but the light emission characteristics may deteriorate
Solution Approach 1:
The patent ensures continuous light emission by rapidly switching between different pixel groups in a time-division manner. Although any single group receives intermittent drive current, the overall system maintains continuous illumination because multiple groups are activated in sequence within the human visual persistence time. This approach preserves light emission characteristics while reducing manufacturing costs through shared current sources.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces the manufacturing cost of the data driver and maintains the emission characteristics of the organic light emitting display by intermittently applying drive currents, ensuring effective light emission without deteriorating performance.
Implementation Method 1
Energy is discharged by excitons generated by recombination of electrons and holes, which are respectively introduced from the metal electrode 101 and the transparent electrode 102. Accordingly, the pixel 1 can emit light to an exterior through the transparent electrode 102 and the glass substrate 105.
Data Source
AI summary
An organic light emitting display includes column lines for receiving a drive current, each column line belonging to one of groups. Row lines are for receiving a scan signal. Organic light emitting diodes of pixels are at crossings of the row and column lines. A data driver includes a common current source and drive switching elements. The common current source is for applying the drive current to the column lines in one group. The drive switching elements are connected to the common current source and are for applying the drive current to the column lines in said one group within a drive period in which the scan signal is applied. Charge switches connected to the column lines are turned-on before the drive current is applied to the column lines, and turned-off during the drive period. A voltage retaining circuit coupled with the charge switches is for preliminarily charging the pixels.