Pixel Circuit with Sensing Sub-circuit for Uniform Brightness
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Solution Overview
Problem
In Active Matrix Organic Light-emitting Diode (AMOLED) displays, the Excimer Laser Annealing and doping process for manufacturing Thin Film Transistors (TFTs) fails to ensure uniformity of TFTs, leading to deviations in threshold voltage, resulting in non-uniform brightness across pixels, and there is a need to integrate biometric recognition functions like fingerprint recognition and touch sensing without external sensors.
Innovation Solution
A pixel circuit with a driving sub-circuit, reset sub-circuit, data writing sub-circuit, and sensing sub-circuit, where the driving sub-circuit provides current for light emission, the reset sub-circuit resets the circuit, the data writing sub-circuit writes data voltage, and the sensing sub-circuit senses external inputs, allowing for independent light emission current from threshold voltage and integrating biometric functions by using scanning and control signals to manage data and read signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If Excimer Laser Annealing and doping process is used for manufacturing TFTs, then manufacturing efficiency is improved, but uniformity of TFTs deteriorates leading to threshold voltage deviation
Solution Approach 1:
The pixel circuit is divided into multiple functional sub-circuits (driving sub-circuit, reset sub-circuit, data writing sub-circuit, sensing sub-circuit) that operate independently. Each sub-circuit handles specific functions separately, allowing the driving current to be controlled independently from the threshold voltage variations, thus compensating for manufacturing non-uniformity while maintaining production efficiency
Solution Approach 2:
The patent changes the operational parameters of the pixel circuit by introducing separate control signals and multiple transistor configurations. By adjusting gate voltages and using different transistor switching states, the circuit compensates for threshold voltage deviations without requiring rework on the manufacturing process, thereby maintaining high productivity while improving uniformity
2Device complexity
If basic 2T1C pixel circuit is used, then device complexity is reduced, but brightness uniformity deteriorates due to threshold voltage variations
Solution Approach 1:
The pixel circuit is segmented into four independent sub-circuits with dedicated functions. The driving sub-circuit controls light emission, the reset sub-circuit resets the circuit state, the data writing sub-circuit writes data voltages, and the sensing sub-circuit detects external inputs. This segmentation allows independent optimization of each function, achieving brightness uniformity without excessive complexity
Solution Approach 2:
The pixel circuit is designed with multi-functional transistors and nodes that serve multiple purposes. For example, certain transistors function as switches in one context and as current mirrors in another. This multi-functionality achieves sophisticated brightness control and uniformity compensation without proportionally increasing device complexity
3Measurement precision
If external sensors are used for biometric recognition, then sensing accuracy is improved, but device complexity and integration difficulty increase
Solution Approach 1:
The sensing function is merged with the existing pixel circuit structure. The sensing sub-circuit uses the same transistor and capacitor elements already present in the pixel circuit, combining display and sensing functions into a single integrated unit. This eliminates the need for separate external sensors while maintaining sensing accuracy
Solution Approach 2:
The pixel circuit is designed with universal elements that can perform both display driving and biometric sensing functions. By using the same physical structures for dual purposes, the patent achieves accurate fingerprint recognition and touch sensing without adding external sensor components, thereby reducing integration complexity
Data Source
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AI summary
The embodiments of the present disclosure disclose a pixel circuit and a method for driving the same, a display panel and a display apparatus. The pixel circuit includes: a driving sub-circuit configured to provide current for causing a light-emitting element to emit light to the light-emitting element under control of a light-emitting control signal; a reset sub-circuit having a reset signal terminal for receiving a reset signal, wherein the reset sub-circuit is connected to the driving sub-circuit and a first terminal of the light-emitting element, and is configured to reset the driving sub-circuit and the first terminal of the light-emitting element under control of the reset signal; a data writing sub-circuit connected to the driving sub-circuit and the reset sub-circuit, and configured to write a data voltage into the driving sub-circuit under control of a first control signal; and a sensing sub-circuit configured to receive a data signal via a first signal terminal, and transmit the data signal to the data writing sub-circuit under control of a second control signal; and sense an external input, and read the sensed external input into a read signal line under control of a read control signal.