OLED Pixel Circuit Photosensing Internal Compensation
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Solution Overview
Problem
Existing pixel circuits in OLED displays face challenges in achieving real-time compensation without external equipment, leading to increased routings and reduced pixel aperture ratio due to the need for built-in optical and electrical compensation.
Innovation Solution
A pixel circuit design incorporating an organic light emitting diode, a driving transistor, and a photosensitive circuit that senses light emission intensity and sets a potential, allowing for internal compensation without external CCD cameras, thereby reducing routing complexity and enhancing aperture ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external compensation equipment such as CCD camera is used to perceive optical characteristics, then measurement precision is improved, but device complexity increases and pixel aperture ratio decreases
Solution Approach 1:
The patent extracts the compensation function from external equipment and integrates it directly into the pixel circuit. The photosensitive circuit is embedded within the pixel structure, eliminating the need for external CCD cameras or specialized perception equipment, thereby reducing device complexity while maintaining measurement precision
Solution Approach 2:
The photosensitive circuit is nested within the pixel circuit structure, with the photodiode integrated alongside the OLED and driving transistor. This nesting allows the compensation function to be housed within the existing pixel footprint, avoiding additional external equipment and reducing overall system complexity
2Speed
If built-in optical and electrical compensation circuits are added to achieve real-time compensation, then compensation speed is improved, but device complexity increases and pixel aperture ratio decreases
Solution Approach 1:
The patent merges the optical sensing function with the electrical compensation function in a single integrated pixel circuit. The photodiode, driving transistor, and compensation capacitors are combined into one unified structure, enabling simultaneous optical detection and electrical compensation without separate built-in circuits, thus reducing routing complexity
Solution Approach 2:
The pixel circuit is designed with multi-functionality, where the same pixel structure performs both light emission (OLED) and light sensing (photodiode) functions. This universal design eliminates the need for separate dedicated compensation circuits, reducing device complexity while achieving real-time compensation speed
3Adaptability or versatility
If additional routing for compensation circuits is added, then compensation functionality is improved, but pixel aperture ratio decreases
Solution Approach 1:
The patent utilizes the vertical dimension by stacking components (OLED, photodiode, transistors, capacitors) in a layered structure rather than spreading them out horizontally. This vertical integration allows compensation functionality to be achieved without increasing the horizontal pixel area, thereby maintaining aperture ratio
Solution Approach 2:
The compensation circuit components are nested within the pixel structure, with the photodiode and compensation capacitors integrated alongside the OLED and driving transistor. This nesting approach enables full compensation functionality without requiring additional routing that would consume pixel aperture area
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
Enables real-time compensation mechanisms within the pixel circuit, reducing the need for external detection systems and increasing the pixel aperture ratio by integrating compensation functions directly into the circuit.
Implementation Method 1
a photodiode connected between the second node and the third node
Data Source
AI summary
A pixel circuit comprising an organic light emitting diode; a driving transistor including a gate, a source connected to a first node, a drain connected to a second power supply terminal; and a photosensitive circuit connected between a second node and a third node, the second node configured to receive a reference voltage. The driving transistor is configured to, responsive to a gate voltage and a source voltage, control a magnitude of a driving current flowing through the organic light emitting diode. The photosensitive circuit is configured to sense an intensity of light emission of the organic light emitting diode and to set a potential at the third node according to the reference voltage and the intensity that was sensed, the potential that was set being detectable by an external circuit via a sense line.