PIN Photodiode Detection With Shield Wiring for Signal Stability
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Solution Overview
Problem
Increasing the sensing area of PIN photodiodes to enhance detection sensitivity leads to increased parasitic capacitance, which causes variations in output signals and reduces detection accuracy.
Innovation Solution
A detection device with a shield wiring line overlapping scan lines and signal lines, reducing parasitic capacitance by supplying a fixed potential to transistors, thereby stabilizing signal variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sensing area of PIN photodiodes is increased to enhance detection sensitivity, then detection sensitivity is improved, but parasitic capacitance increases causing signal variations and reducing detection accuracy
Solution Approach 1:
A shield wiring line is introduced as an intermediary element between the scan lines and the photodiode sensing area. This shield wiring line, connected to a fixed potential (ground or power supply), acts as an electrostatic shield that reduces the parasitic capacitance coupling between the scan lines and the photodiodes, thereby stabilizing the output signals while maintaining the large sensing area configuration
2Quantity of substance
If the sensing area is increased, then photocurrent and detection sensitivity are improved, but the distance between photodiode and scan line decreases increasing parasitic capacitance
Solution Approach 1:
The shield wiring line serves as a mediating structure that physically separates the scan lines from the photodiode sensing area while maintaining electrical shielding. By positioning the shield wiring line between the scan lines and the photodiodes and connecting it to a fixed potential, the parasitic capacitance is reduced without compromising the photocurrent generation in the enlarged sensing 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
The solution improves detection sensitivity and reduces signal variations, enhancing the accuracy of the detection device.
Implementation Method 1
increases the parasitic capacitance. This parasitic capacitance may cause variation in output signals from the photodiodes
Implementation Method 2
a plurality of photodiodes that are provided in an area surrounded by the scan lines and the signal lines and each include a p-type semiconductor layer, an i-type semiconductor layer, and an n-type semiconductor layer
Data Source
AI summary
According to an aspect, a detection device includes: a substrate; a plurality of transistors provided on the substrate; a plurality of scan lines that extend in a first direction; a plurality of signal lines that extend in a second direction intersecting the first direction; a plurality of photodiodes that are provided in an area surrounded by the scan lines and the signal lines and each include a p-type semiconductor layer, an i-type semiconductor layer, and an n-type semiconductor layer; and a shield wiring line that extends in the first direction and overlaps a corresponding one of the scan lines. The shield wiring line is electrically coupled to, among the signal lines, a power supply signal line configured to supply a power supply potential to the transistors.