EL Display Panel Module Threshold Correction Circuit
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Solution Overview
Problem
Organic EL display panels using active matrix driving methods face challenges in maintaining stable light emission characteristics and high picture quality due to aged deterioration of I-V characteristics, especially when using n-channel thin film transistors, which also lead to increased fabrication costs.
Innovation Solution
An EL display panel module with a pixel array and driving circuit on the same substrate, where a threshold value correction operation is performed commonly for multiple pixel circuits, and a reset potential lower than the reference potential is applied before writing the signal potential, ensuring consistent light emission and reducing fabrication costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If n-channel thin film transistors are used in the pixel circuit, then fabrication cost is reduced, but light emission characteristics become unstable due to threshold value and mobility variations
Solution Approach 1:
The patent applies preliminary action by performing threshold value correction before the normal operation of the pixel circuit. A correction operation is executed in advance to adjust the threshold voltage of the n-channel TFT, compensating for variations and aging effects before the display panel is put into service. This ensures stable light emission characteristics while maintaining the cost advantage of using n-channel TFTs.
Solution Approach 2:
The patent changes the threshold voltage parameter of the n-channel thin film transistor through a correction operation. By dynamically adjusting the threshold voltage based on measured characteristics, the system compensates for manufacturing variations and aging, stabilizing the current flow and light emission despite using lower-cost n-channel devices with inherent parameter variations.
2Manufacturing precision
If threshold value correction operation is performed commonly for multiple pixel circuits, then fabrication cost is reduced and picture quality is improved, but the complexity of the driving circuit increases
Solution Approach 1:
The patent merges the threshold value correction operation across multiple pixel circuits that share common signal lines. Instead of correcting each pixel independently, the correction is performed collectively for groups of pixels connected to the same scan and signal lines, reducing the number of separate correction operations needed and simplifying the driving circuit architecture while maintaining uniform picture quality.
Solution Approach 2:
The driving circuit is designed with multi-functionality, where the same correction operation mechanism serves multiple pixel circuits simultaneously. The circuit structure allows a single correction operation to benefit multiple pixels, reducing overall circuit complexity while achieving high manufacturing precision across the display panel.
3Reliability
If reset potential lower than reference potential is applied before signal writing, then light emission is stabilized, but additional control steps are required
Solution Approach 1:
The reset potential is applied as a preliminary action before the signal writing operation. By establishing the correct potential state in advance, the system ensures that the n-channel TFT operates with stable characteristics when the signal is written, preventing subsequent drift and maintaining consistent light emission. This preliminary reset step is integrated into the existing control sequence without adding significant complexity.
Data Source
AI summary
Disclosed herein is an EL display panel module, including: a pixel array section including a panel serving as a substrate, and a plurality of pixels disposed in a matrix on the panel and each including a pixel circuit, and a light emitting region; and a driving circuit for driving the pixel circuits such that a threshold value correction operation is carried out commonly for plural ones of the pixel circuits which are connected to each signal line and writing of a signal potential corresponding to a gradation value is executed time-sequentially for the individual pixel circuits, the driving circuit applying a reset potential lower than a reference potential for the threshold value correction to the plural ones of the pixel circuits before first writing of the signal potential after the threshold value correction operation is completed; the pixel array section and the driving circuit being mounted on the same substrate.