Shared Output Switch Pixel Circuit for OLED Display
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Solution Overview
Problem
Existing active matrix display apparatuses, particularly organic EL display apparatuses, face challenges in reducing the number of elements and lines within each pixel, which affects the layout area and definition, while also dealing with variations in mobility that can lead to inappropriate display and viewer discomfort.
Innovation Solution
The display apparatus incorporates a pixel circuit with a driving transistor, a pixel switch, and storage capacitance, where multiple pixels share an output switch, reducing the number of output switches, scanning lines, and reset lines, and employs specific control signals for initialization, offset cancel, and video signal write operations to manage threshold variations and improve image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If each pixel includes its own output switch, then the pixel circuit can independently control the display element, but the number of elements and lines increases, leading to larger layout area and reduced definition
Solution Approach 1:
The patent merges the output switch function from individual pixel circuits into a shared output switch that serves multiple pixels. Specifically, one output switch is shared by four pixels arranged in a 2x2 matrix, significantly reducing the number of output switches and associated scanning lines while maintaining the ability to independently control each pixel's display element through the shared switch's gate electrode connections
2Area of stationary object
If multiple pixels share an output switch, then the number of elements and lines is reduced, but the complexity of controlling threshold variations and mobility differences increases
Solution Approach 1:
The patent implements preliminary action by introducing an initialization signal that is applied to the gate electrode of the output switch before the actual display signal. This initialization step pre-charges or pre-biases the gate electrode to a known state, compensating for threshold variations and mobility differences among the shared pixels. The initialization signal ensures that all pixels starting from the same electrical state, simplifying subsequent control operations
Solution Approach 2:
The patent employs feedback mechanisms through offset cancel operations where the display apparatus measures and compensates for threshold variations in the shared output switch. By monitoring the electrical characteristics of the shared switch and adjusting the initialization signal accordingly, the system maintains consistent display performance across all pixels sharing the same output switch
Data Source
AI summary
According to one embodiment, a display apparatus includes a plurality of pixels and a plurality of control lines. A pixel circuit of each of the pixels includes a driving transistor, an output switch, a pixel switch and a storage capacitance. A number of pixels PX of the plurality of pixels which are adjacent to one another in a column direction share the output switch.