EL Display Driving Method for Cross-Talk Reduction
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Solution Overview
Problem
Conventional EL display devices face challenges in achieving high definition due to increased complexity and yield issues caused by current leaks and cross-talk effects in pixel circuits, which affect image quality and luminosity.
Innovation Solution
A driving method for EL display devices that involves a specific timing of supplying a leak control voltage to the video signal wire, deliberately generating a leak current to uniformly decrease the voltage stored in capacitors across all pixels, thereby reducing cross-talk effects and maintaining consistent luminosity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional pixel circuits are used with multiple transistors and control wires to correct drive transistor characteristics, then manufacturing precision and reliability are improved, but device complexity increases which hinders achieving high definition
Solution Approach 1:
The patent extracts and eliminates unnecessary transistors and control wires from the pixel circuit by introducing a simplified circuit structure with only two transistors and one capacitor. The gate terminal of the second transistor is directly connected to the video signal wire, removing the need for separate control wires and additional transistors while maintaining the ability to correct drive transistor characteristics through the capacitor's voltage storage function.
Solution Approach 2:
The capacitor in the simplified pixel circuit serves multiple functions: it stores voltage to compensate for drive transistor characteristic variations, maintains stable operation during the display period, and enables the circuit to achieve high definition without requiring additional dedicated components for each function.
2Device complexity
If the number of transistors and control wires is reduced to simplify the pixel circuit, then device complexity decreases enabling high definition, but current leaks and cross-talk effects increase which worsen image quality
Solution Approach 1:
The patent applies preliminary action by writing a reference voltage to the capacitor during the voltage writing period before the display period begins. This preliminary voltage storage compensates for potential current leaks and cross-talk effects that may occur during the display period, ensuring stable image quality without requiring complex circuit structures.
Solution Approach 2:
The patent converts the potential harmful effect of current leaks into a beneficial compensatory mechanism. By deliberately designing the capacitor to store voltage that compensates for expected current leaks, the simplified circuit structure achieves stable operation without the need for additional error correction circuits, thereby reducing device complexity while maintaining image quality.
3Device complexity
If a simplified pixel circuit with two transistors and one capacitor is used, then device complexity decreases enabling high definition, but voltage variations and cross-talk effects affect image quality and luminosity consistency
Solution Approach 1:
The patent applies equipotentiality by ensuring that all pixels receive the same reference voltage through the capacitor before the display period. This equalizes the starting voltage condition across all pixels, compensating for manufacturing variations and ensuring uniform luminosity and image quality throughout the display area without requiring complex voltage regulation circuits.
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 method effectively reduces the impact of cross-talk, ensuring uniform voltage reduction across all pixels and improving image quality by averaging voltage variations, thus enhancing the display's ability to maintain consistent luminosity and reduce local cross-talk effects.
Implementation Method 1
a capacitor arranged between the gate terminal and a source terminal of the drive transistor
Implementation Method 2
An electroluminescence element (referred to herein as [EL element]) is known as a light emitting element which utilizes an electroluminescence phenomenon
Data Source
AI summary
A method of driving a display device with a plurality of pixels including a video signal wire, a first power supply wire supplied with a first potential, a second power supply wire supplied with a second potential different to the first potential, a light emitting element arranged between the first power supply wire and the second power supply wire, a drive transistor controlling a value of a current supplied to the light emitting element, and a switch arranged between the video signal wire and the drive transistor, and inputting a signal of the video signal wire to a gate terminal of the drive transistor, wherein a minimum gradation level potential is supplied to the video signal wire after a video signal is written to the capacitor of an Nth row pixel until a video signal is written to the capacitor of an Mth (N<M) row pixel.