Microlens Array Optical Fingerprint Sensor for Compact Mobile Integration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing fingerprint sensor technologies face challenges in compact design due to the large size of lenses and photosensor arrays required to image a reasonable fingerprint area, which is not feasible in the limited space of a cell phone.
Innovation Solution
A multiple-lens optical fingerprint reader with a microlens array and integrated circuit configuration, where each microlens focuses light from a portion of the fingerprint region onto multiple photosensors, allowing for overlapping images and efficient image stitching, and is fabricated using a thin glass substrate with reflowable optical material and preformed stamps to reduce size and enhance imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single lens and single array of photosensors are used to image fingerprint, then the structure is simple, but the lens and photosensor array become large requiring considerable space
Solution Approach 1:
The patent divides the single lens into multiple microlenses arranged in an array, and divides the single photosensor array into multiple photosensor arrays. Each microlens images a specific portion of the fingerprint onto corresponding photosensors. This segmentation allows the system to maintain imaging capability while reducing the size of individual components and fitting them within limited mobile device space.
2Area of stationary object
If multiple microlenses are used to reduce size, then the device fits in limited space, but the microlenses must focus light from offset portions of fingerprint
Solution Approach 1:
The patent assigns different functional characteristics to different parts of the microlens array. Microlenses at the center of the array focus light from fingerprint portions directly above them, while microlenses at the edges focus light from offset portions of the fingerprint. This local differentiation allows the entire array to capture the complete fingerprint image through coordinated offset imaging, enabling compact design while maintaining imaging quality.
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 effective fingerprint imaging within the limited space of a cell phone, reducing the size of the integrated circuit and improving image quality while maintaining efficient verification processes.
Implementation Method 1
each microlens of the microlenses configured to focus light arriving at that microlens from a portion of a fingerprint region of a finger adjacent a surface of the display to form an image on a plurality of photosensors associated with that microlens
Implementation Method 2
illuminating a fingerprint region of a finger of the user with an organic light emitting diode (OLED) display panel
Data Source
AI summary
A multiple-lens optical fingerprint reader for reading fingerprints through a display has a spacer; and multiple microlenses with concave and convex surfaces in a microlens array, each microlens of multiple lenses focuses light arriving at that microlens from a finger adjacent the display through the spacer forms an image on associated photosensors on a photosensor array of an image sensor integrated circuit. A method of verifying identity of a user includes illuminating a finger of the user with an OLED display; focusing light from the finger through arrayed microlenses onto a photosensor array, reading the array into overlapping electronic fingerprint images; extracting features from the overlapping fingerprint images or from a stitched fingerprint image, and comparing the features to features of at least one user in a library of features and associated with one or more fingers of one or more authorized users.