Pixel Circuit Dark Spot Detection via Test Transistors
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Solution Overview
Problem
Existing display apparatuses face challenges in reducing dark spots caused by dust or defects during fabrication, leading to decreased yield and increased costs, particularly with complex 5TR driving configurations that hinder high-definition displays in small-sized devices.
Innovation Solution
A display apparatus with a simplified 2TR configuration that includes a driving transistor, storage capacitor, sampling transistor, and test transistors to identify and isolate dark spots, allowing for selective supply of driving current and improved luminance control, while reducing the number of components and wiring lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a complex 5TR driving configuration is used to improve dark spot detection capability, then the ability to identify and isolate dark spots is enhanced, but the device complexity and number of components increase
Solution Approach 1:
The pixel is divided into multiple divisional pixels (first, second, third divisional pixels) with different transistor configurations. This segmentation allows dark spot detection through comparative luminance measurement while keeping each divisional pixel's component count manageable, resolving the contradiction between detection capability and device complexity
Solution Approach 2:
The invention uses luminance intensity comparison (analogous to color/brightness detection) among divisional pixels to identify dark spots. By comparing the luminance output of different divisional pixels driven by the same driving current, the system can detect abnormal pixels without requiring complex additional components
2Measurement precision
If more test transistors are added to each pixel to improve dark spot specification accuracy, then the precision of dark spot identification is enhanced, but the manufacturing cost and device complexity increase
Solution Approach 1:
The driving transistor serves multiple functions: it drives the electro-optical element for normal display operation and simultaneously enables dark spot detection by controlling current flow to divisional pixels. This multi-functionality achieves accurate dark spot specification without adding dedicated test transistors, resolving the contradiction between measurement precision and device complexity
Solution Approach 2:
The pixel circuit uses its own driving transistor and electro-optical element to perform self-diagnosis for dark spot detection. The system leverages existing components to detect and specify defective pixels, eliminating the need for separate test components and reducing overall device complexity while maintaining detection accuracy
3Productivity
If the pixel circuit is simplified to reduce component complexity, then the manufacturing efficiency and yield are improved, but the capability to detect and isolate dark spots may be compromised
Solution Approach 1:
By dividing the pixel into multiple divisional pixels with distinct transistor connections, the invention enables dark spot isolation through selective connection control. The segmentation allows defective portions to be identified and electrically isolated while maintaining the overall simplified pixel structure, thus preserving both manufacturing efficiency and dark spot isolation capability
Solution Approach 2:
The invention employs dynamic connection control where the connection state between transistors and electro-optical elements can be changed during operation. This dynamic switching capability enables the simplified pixel circuit to adapt between normal display mode and dark spot detection/isolation mode, maintaining both productivity and reliability
4Reliability
If a 5TR configuration is used to improve dark spot detection, then the dark spot specification capability is enhanced, but the pixel area and device size increase
Solution Approach 1:
The invention merges the dark spot detection function with the normal display function by using the same driving transistor and electro-optical element for both purposes. The divisional pixels share common components, and dark spot detection is achieved through comparative luminance measurement rather than additional physical test structures, thus enhancing detection capability while minimizing pixel area
Data Source
AI summary
A pixel array section includes a plurality of pixel circuits disposed in a matrix and each including a driving transistor, a storage capacitor, an electro-optical element, and a sampling transistor. Each pixel circuit includes a pixel divided into a plurality of divisional pixels for each of which an electro-optical element is provided, and a test transistor provided between the driving transistor and the electro-optical elements for carrying out on/off operations for specifying whether or not the electro-optical element is a dark spot element so that the electro-optical element of the dark spot can be specified. The number of the test transistors is smaller than the number of the divisional elements of the original one pixel.