Optical Fingerprint Sensor Pixel Layout for Noise Blocking
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Solution Overview
Problem
The detection capability of fingerprint sensors in display devices is deteriorated by external noise, leading to reduced sensitivity.
Innovation Solution
The input sensing device incorporates a power line, driving lines, and signal lines with sensor pixels that include optical sensors and transistors connected in a specific configuration to reduce noise interference, utilizing a photodiode and transmission transistors to enhance signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a light-sensing sensor with optical sensor array is used for fingerprint sensing, then the fingerprint detection function is provided, but external noise reduces the sensitivity and detection capability
Solution Approach 1:
The patent introduces a noise cancellation unit as an intermediary component that receives both the fingerprint sensing signal and the noise signal, processes them separately, and combines them to eliminate noise. This mediator approach allows the system to handle noise as a separate entity rather than letting it directly interfere with the detection process.
Solution Approach 2:
The patent segments the sensing system into multiple independent components: a fingerprint sensing unit, a noise sensing unit, and a noise cancellation unit. Each unit has a dedicated function, allowing the noise to be processed independently from the fingerprint signal, thereby improving overall detection precision without compromising sensitivity.
2Reliability
If sensor pixels with photodiodes and transistors are configured to reduce noise, then the signal-to-noise ratio is improved, but the device structure becomes more complex
Solution Approach 1:
The patent merges multiple functions into the sensor pixel structure itself. The photodiode serves both as the light-sensitive element and as part of the signal processing circuit. Transistors are integrated directly within the pixel to perform amplification and noise filtering, eliminating the need for separate processing components and reducing overall device complexity while maintaining high signal-to-noise ratio.
Solution Approach 2:
The sensor pixel is designed as a multi-functional unit where the photodiode, transistors, and associated circuits work together to perform sensing, signal amplification, noise filtering, and data output all within a single integrated structure. This universal design approach improves reliability without proportionally increasing device complexity.
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 configuration improves the sensing sensitivity by blocking noise and leakage currents, resulting in better fingerprint detection accuracy.
Implementation Method 1
an optical sensor that transfers a photoelectrically converted charge from the power line to a first node
Data Source
AI summary
An input sensing device including: a power line; driving lines; a first signal line including sub-lines; a second signal line connected to the sub-lines; and sensor pixels connected to the power line, the driving lines, and the first signal line, wherein at least one sensor pixel of the sensor pixels includes: an optical sensor that transfers a photoelectrically converted charge from the power line to a first node in response to a driving signal provided through a first driving line of the driving lines; a first transistor connected between the first node and a first sub-line among the sub-lines, wherein the first transistor includes a gate electrode connected to the first driving line; and a second transistor connected between the first node and a second sub-line among the sub-lines, wherein the second transistor includes a gate electrode connected to the first driving line.