Pixel Circuit Time-Multiplexed Fingerprint Detection
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Solution Overview
Problem
Current optical fingerprint recognition technologies using OLED display panels face challenges with low precision and high noise in detecting fingerprint patterns due to limited detection capability and interference between sense electrical signals from photodiodes in a column, leading to low signal-to-noise ratios and reduced precision.
Innovation Solution
The implementation of a pixel circuit with an active detection method and a light-emitting control circuit that time-multiplexes a constant current to the photoelectric sense circuit, enhancing signal precision and reducing noise, while optimizing the structural layout and reducing manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If passive detection method is used with photodiodes arranged in columns, then device complexity is reduced, but measurement precision deteriorates due to signal interference and low signal-to-noise ratio
Solution Approach 1:
The patent implements periodic action by alternating between a display period (where the light-emitting element emits light) and a photoelectric sense period (where the photoelectric sense circuit detects reflected light). This time-division multiplexing allows the same circuit to perform both display and detection functions sequentially, eliminating signal interference that occurs in passive detection methods while maintaining device simplicity.
Solution Approach 2:
The light-emitting control circuit serves dual functions: it drives the light-emitting element during the display period and provides constant current to the photoelectric sense circuit during the detection period. This self-service approach eliminates the need for separate detection circuits, reducing device complexity while improving measurement precision through active detection with controlled current sources.
2Measurement precision
If active detection method with time-multiplexed constant current is used, then measurement precision is improved, but device complexity increases due to additional circuit requirements
Solution Approach 1:
The light-emitting control circuit is designed with multi-functionality to serve both as a display driver and a constant current source for the photoelectric sense circuit. By controlling the switching between display and detection modes, the same circuit performs multiple functions, improving measurement precision through active detection without requiring entirely separate circuitry.
Solution Approach 2:
The patent merges the display function and detection function into a single integrated pixel circuit. The light-emitting element, light-emitting control circuit, and photoelectric sense circuit are combined such that the control circuit manages both light emission and light detection operations, reducing overall device complexity while maintaining the precision benefits of active detection.
3Ease of manufacture
If photoelectric sense circuit is integrated within pixel unit, then manufacturing cost is reduced, but area available for detection is reduced
Solution Approach 1:
The photoelectric sense circuit is nested within the pixel unit structure, sharing the same physical space and control infrastructure as the light-emitting element. The sense circuit is positioned to receive light reflected from the finger while being electrically integrated with the existing pixel circuitry, achieving cost-effective integration without requiring separate detection modules that would consume additional 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
This approach improves the detection precision and signal-to-noise ratio of fingerprint recognition, reduces the space occupied by the photoelectric sense circuit, and lowers manufacturing costs, resulting in a more effective and efficient fingerprint recognition system.
Implementation Method 1
a photoelectric sense circuit configured to sense light incident on the photoelectric sense circuit
Implementation Method 2
a light-emitting element configured to emit light in response to a light-emitting current signal
Data Source
AI summary
A pixel circuit and a drive method thereof and a display panel are provided. The pixel circuit includes a light-emitting element, a light-emitting control circuit and a photoelectric sense circuit. The light-emitting control circuit is configured to drive the light-emitting element to emit light and includes a first end, a second end and a third end; the first end is connected with a first power supply terminal, and the second end is connected with one end of the light-emitting element. Other end of the light-emitting element is connected with a second power supply terminal. The photoelectric sense circuit is configured to sense light incident thereon and includes a sense signal output end and a sense voltage input end, the sense voltage input end is connected with the second power supply terminal, and the sense signal output end is connected with the third end of the light-emitting control circuit.