Sensing Layer Side Coverage for Fingerprint Photo Current Ratio
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Solution Overview
Problem
Conventional fingerprint identification technologies face errors in dim light conditions due to less distinct peaks and troughs, requiring repeated sensing processes for successful identification.
Innovation Solution
A display device with a sensing element substrate that includes a substrate, switch element, insulation layer, electrically conductive layer, signal line, sensing layer, and electrode layer, where the sensing layer covers the top surface and sides of the electrically conductive layer, increasing the light sensing area and enhancing the ratio of photo current to dark current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sensing layer only covers the top surface of the electrically conductive layer, then the device structure is simple, but the light sensing area is small resulting in low photo current to dark current ratio
Solution Approach 1:
The sensing layer is extended from covering only the top surface to also covering the first side and second side of the electrically conductive layer, effectively adding vertical/d lateral dimensions to the sensing area. This multi-dimensional coverage increases the light sensing area without proportionally increasing device complexity, thereby improving the photo current to dark current ratio.
2Reliability
If the light sensing area is increased by extending sensing layer coverage, then the photo current to dark current ratio improves, but the manufacturing process becomes more complex
Solution Approach 1:
The sensing layer is integrated to simultaneously cover the top surface, first side, and second side of the electrically conductive layer as a unified continuous structure. This merging approach allows the sensing layer to provide extended light sensing area while being fabricated as a single integrated component, reducing the number of separate fabrication steps and maintaining ease of manufacture.
3Measurement precision
If the aperture ratio is increased to improve light sensing, then the sensitivity improves, but the device structure becomes more complex
Solution Approach 1:
The sensing layer configuration serves multiple functions simultaneously: it covers the top surface for primary sensing, extends to the first and second sides to increase light sensing area, and maintains structural integration with the electrically conductive layer. This multi-functional design improves sensitivity and aperture ratio while avoiding the need for separate additional components, thereby limiting the increase in overall 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 sensitivity of the sensing device by increasing the light sensing area and aperture ratio, allowing for more accurate fingerprint identification even in low-light conditions.
Implementation Method 1
the sensing device detects light reflected by the fingerprint of the finger
Data Source
AI summary
A display device includes a pixel array substrate, a sensing element substrate, and a display medium layer. The display medium layer is disposed between the pixel array substrate and the sensing element substrate. The sensing element substrate includes a substrate, a switch element, an insulation layer, an electrically conductive layer, a signal line, a sensing layer, and an electrode layer. The switch element is disposed on the substrate. The insulation layer covers the switch element. The electrically conductive layer is disposed on the insulation layer. The signal line is electrically connected to the electrically conductive layer. The sensing layer covers a top surface of the electrically conductive layer, a first side of the electrically conductive layer, and a second side of the electrically conductive layer. The electrode layer covers the sensing layer. The electrode layer is electrically connected to the switching element.