Optical Sensor Light Shielding Layer Reduces Inter-Pixel Charge Leakage
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Solution Overview
Problem
Optical sensors with organic photodiodes experience a decrease in contrast due to electric charges generated between adjacent pixels, which affects their performance in detecting biometric information.
Innovation Solution
Incorporating a light shielding layer that covers at least a part of the active layer between adjacent pixel electrodes on the light-receiving side, preventing unwanted light from entering and reducing charge leakage between pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a common organic photoelectric conversion layer is used between pixel electrodes, then device complexity is reduced and manufacturing is simplified, but electric charge generated between adjacent pixels flows into the pixels causing contrast to decrease
Solution Approach 1:
The patent divides the common organic photoelectric conversion layer into functionally distinct regions by introducing light shielding layers between adjacent pixels. This segmentation prevents charge carriers generated in inter-pixel regions from flowing into pixel electrodes, thereby resolving the contrast degradation issue while maintaining the overall common-layer structure for manufacturing efficiency
Solution Approach 2:
The patent introduces light shielding layers as intermediary structures between adjacent pixels in the common organic photoelectric conversion layer. These intermediary layers block light and charge carrier flow between pixels, preventing the harmful effect of inter-pixel charge leakage while maintaining the benefits of a common photoelectric conversion layer
2Productivity
If the active layer is made larger to increase light reception area, then detection efficiency is improved, but charge generated in regions between pixels increases causing contrast to decrease
Solution Approach 1:
The patent applies local quality by creating spatial variations in the photoelectric conversion layer's light-receiving properties. Light shielding layers are strategically placed in inter-pixel regions to have different optical properties (light-blocking) compared to pixel regions (light-transmitting), enabling the active layer to maintain large area for detection while preventing charge leakage in specific local regions
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 enhances the contrast and detection efficiency of the optical sensor by minimizing the flow of electric charges between adjacent pixels, thereby improving the accuracy of biometric data detection.
Implementation Method 1
an active layer converting incident light into electric charges
Implementation Method 2
a light shielding layer covering at least a part of the active layer between the adjacent electrodes on a light receiving side that receives the incident light
Data Source
AI summary
An optical sensor includes: a plurality of electrodes adjacent to one another; an organic photoelectric conversion layer that includes an active layer and is laminated in common on the plurality of electrodes, the active layer converting incident light into an electric charge; and a light shielding layer covering at least a part of the active layer between the adjacent electrodes on a light receiving side that receives the incident light.