Microlens Fingerprint Imaging Layout for Smaller Sensor Chips
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Solution Overview
Problem
Conventional optical fingerprint sensors have a large chip size due to the need for numerous optical elements, leading to high fabrication costs and inefficient use of space, which limits their miniaturization and integration in compact devices.
Innovation Solution
The optical imaging device features a substrate with a matrix arrangement of detecting units, including optoelectronic elements and micro-lenses, where each detecting unit has multiple openings in opaque layers to form optical channels, allowing for a reduced chip size while maintaining an enlarged field of view and improved light reception efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional optical fingerprint sensors use multiple optical elements (beam splitters, collimators, focusing mirrors) to achieve accurate fingerprint imaging, then the imaging quality is improved, but the chip size increases and fabrication cost increases
Solution Approach 1:
The patent combines multiple optical functions (collimation, focusing, beam splitting) into a single integrated optical element or detector array structure. The detector array itself is configured to receive light from multiple angles and positions, eliminating the need for separate collimators and focusing mirrors, thereby reducing chip size while maintaining imaging quality
Solution Approach 2:
The optical element or detector array performs multiple functions simultaneously: it collimates light, focuses light, and divides light paths to different detectors. This multi-functional design replaces multiple specialized optical components, reducing the overall chip area while achieving the same imaging performance
2Measurement precision
If conventional optical fingerprint sensors use direct light reception for each detector to ensure accurate light capture, then the light reception accuracy is improved, but the chip size increases
Solution Approach 1:
The patent transitions from a two-dimensional planar arrangement of detectors to a three-dimensional optical path configuration using microlenses. The microlenses focus light from different angles onto specific detector elements, enabling accurate light reception without requiring each detector to have a large direct viewing area, thus reducing the overall sensor active area
3Adaptability or versatility
If conventional optical fingerprint sensors use multiple optical elements to achieve wide-angle imaging, then the field of view is enlarged, but the device complexity increases
Solution Approach 1:
The patent divides the imaging function across multiple detector elements in an array, where each detector element is paired with a microlens. This segmentation allows each element to capture light from a specific angular range, and the combined array achieves wide-angle imaging without requiring complex optical elements like beam splitters and focusing mirrors
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 enables a smaller sensor active area, reducing fabrication costs and allowing for wider-angle fingerprint imaging, enhancing the optical fingerprint sensor's performance and integration capabilities.
Implementation Method 1
The at least one first micro-lens is disposed over the first opaque layer. The at least one first micro-lens overlaps at least one of the plurality of first pixels.
Implementation Method 2
an array of imaging detectors to receive the light reflected from the sensing area
Data Source
AI summary
An aspect of the present invention provides an optical imaging device including a first detecting unit. The first detecting unit includes a plurality of first pixels, a first opaque layer and at least one first micro-lens. The plurality of first pixels respectively has a plurality of first optoelectronic elements. The first opaque layer has at least one opening and is disposed over the plurality of first optoelectronic elements. The at least one first micro-lens is disposed over the first opaque layer, and overlaps at least one of the plurality of first pixels.