Image Sensor Infrared Intensity and Cost Reduction
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Solution Overview
Problem
Conventional image sensors for iris recognition in electronic devices face challenges in effectively receiving and processing both visible light and infrared due to separate portions that result in infrared light intensity loss and higher manufacturing costs.
Innovation Solution
The image sensor design includes a visible light receiving portion with a color filter, infrared cutoff filter, and a first white filter, and an infrared receiving portion with an infrared photodiode, second white filter, and infrared pass filter, optimized to minimize infrared light path loss and reduce manufacturing costs by using white photoresist filters and micro-lens layers for improved signal intensity and focus adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If separate portions are used for receiving visible light and infrared, then both visible light and infrared can be received, but infrared light intensity loss occurs
Solution Approach 1:
The patent combines the visible light receiving portion and infrared receiving portion into a single integrated image sensor structure. The infrared photodiode is positioned at the same substrate level as visible light photodiodes, and both share common optical path components including the same infrared cutoff filter layer. This merging eliminates separate optical paths that cause infrared light intensity loss while maintaining the capability to receive both visible light and infrared simultaneously.
2Adaptability or versatility
If separate portions are used for receiving visible light and infrared, then both visible light and infrared can be received, but manufacturing cost increases
Solution Approach 1:
The patent integrates infrared receiving functionality into the existing visible light image sensor manufacturing process. The infrared photodiodes are formed alongside visible light photodiodes using the same substrate and shared filter layers. This merging allows both functions to be produced in a single manufacturing run, eliminating the need for separate production lines and reducing overall manufacturing costs.
Solution Approach 2:
The image sensor is designed with multi-functionality, where a single device structure serves dual purposes: visible light imaging and infrared sensing. The shared optical path, common substrate, and overlapping manufacturing processes enable one universal device to replace what would traditionally require two separate devices, thereby simplifying production and reducing costs.
3Ease of manufacture
If infrared photodiode is disposed at the same level as visible light photodiode, then manufacturing cost is reduced, but infrared light path optimization becomes more challenging
Solution Approach 1:
The patent applies local quality by positioning the infrared photodiode at the same substrate level as visible light photodiodes in specific regions, while maintaining different optical path characteristics above each type of photodiode. The infrared photodiode region is equipped with an infrared pass filter and lacks a color filter, whereas visible light photodiodes have color filters. This localized differentiation optimizes each photodiode type's light reception while maintaining overall manufacturing simplicity through shared substrate and filter structures.
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 design enhances infrared intensity reception, meeting user demands and simplifying subsequent signal analysis while reducing manufacturing costs by minimizing light path loss and optimizing filter placement and materials.
Implementation Method 1
The infrared receiving portion includes an infrared photodiode, a second white filter, and an infrared pass filter. The infrared is received by the infrared photodiode after passing through the second white filter and the infrared pass filter.
Data Source
AI summary
An image sensor is provided. The image sensor includes a visible light receiving portion and an infrared receiving portion. The visible light receiving portion is configured to receive a visible light. The visible light receiving portion includes a first white filter. The infrared receiving portion is configured to receive infrared. The infrared receiving portion includes an infrared photodiode, a second white filter, and an infrared pass filter. The second white filter is disposed on the infrared photodiode. The infrared pass filter is disposed on the infrared photodiode. The infrared is received by the infrared photodiode after passing through the second white filter and the infrared pass filter.