Optical Fingerprint Sensor Prism Volume Reduction
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Solution Overview
Problem
Conventional optical fingerprint image acquisition devices are bulky and cannot be effectively integrated into compact electronic devices due to their large volume, despite previous attempts to miniaturize them, such as those described in P.R.C. invention patent publications CN101034437 A and CN102004912 B, which still fall short in practical applications for increasingly miniaturized electronic products.
Innovation Solution
An optical fingerprint sensor with a prism module that includes a shell, an optical prism with specific included angles for reflections, and an image sensing unit with a lens and image receiver, allowing for multiple reflections to maintain an optical path while reducing the device's volume, enabling broader fingerprint collection areas and miniaturization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional optical fingerprint image acquisition devices use traditional prism arrangements, then the optical path can be maintained, but the device volume becomes large and cannot be integrated into compact electronic devices
Solution Approach 1:
The patent applies dimensional change by arranging optical components in a layered three-dimensional structure rather than traditional planar arrangement. The prism is positioned at a first layer, the fingerprint sensor at a second layer, and the light source at a third layer, creating a vertical stacking configuration that reduces horizontal space occupation while maintaining optical path effectiveness through controlled light reflection and transmission across layers
Solution Approach 2:
The patent implements nesting by integrating multiple functional components within a compact layered structure where the prism, fingerprint sensor, and light source are arranged in overlapping vertical positions. The fingerprint sensor is positioned to detect light that has passed through the prism layer, while the light source is placed to illuminate through both the prism and fingerprint sensor layers, creating a nested configuration that minimizes overall device volume
2Volume of moving object
If the prism volume is constrained to reduce device size, then miniaturization is achieved, but the fingerprint collection area becomes limited and definition deteriorates
Solution Approach 1:
The patent applies local quality by optimizing specific regions of the optical path for different functions: the prism region is designed with specific refraction properties for light direction control, the fingerprint sensor region is positioned for maximum light reception efficiency, and the light source region is configured for optimal illumination distribution. This localized optimization allows each component to perform its function at maximum efficiency within a constrained volume
Solution Approach 2:
The patent employs parameter changes by adjusting the refractive index parameters of the prism material, modifying the angular parameters of light incidence and reflection, and optimizing the positional parameters of the fingerprint sensor relative to the prism. These parameter optimizations enable high-definition fingerprint capture while maintaining a reduced prism volume and compact overall device structure
3Volume of moving object
If previous miniaturization approaches are used, then device size is reduced, but the solutions still cannot satisfy increasingly miniaturized electronic products in practical applications
Solution Approach 1:
The patent implements universality by designing a multi-functional integrated optical module where the same layered structure serves multiple purposes: the prism simultaneously performs light refraction and directional control, the fingerprint sensor layer both captures fingerprint patterns and filters light, and the light source provides both illumination and acts as a reference for optical alignment. This multi-functionality enables the compact device to meet diverse miniaturization requirements across different electronic product applications
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
The solution effectively reduces the volume of the optical fingerprint sensor while maintaining a clear optical path, allowing for broader fingerprint collection areas suitable for one, two, or five fingers, significantly improving upon conventional devices by enabling more compact and efficient fingerprint recognition.
Implementation Method 1
a light ray undergoes a first reflection and a second reflection with the basal plane and the mirror surface, respectively
Implementation Method 2
there being a first included angle provided between the mirror surface and the collection surface, a second included angle provided between the mirror surface and the basal plane
Data Source
AI summary
The invention is an optical fingerprint sensor with prism module, including a shell; an optical prism arranged in the shell, the optical prism comprising a collection surface, a basal plane, a mirror surface and an output surface, there being a first included angle provided between the mirror surface and the collection surface, a second included angle provided between the mirror surface and the basal plane, a third included angle provided between the output surface and the collection surface, and a fourth included angle provided between the output surface and the basal plane; and an image sensing unit combined with the shell, comprising multiple luminous elements arranged beneath the basal plane of the optical prism correspondingly, and an image receiver and a lens arranged corresponding to the output surface. Thereby, an user is allowed to place fingerprint onto the collection surface for a light source of the luminous elements to be input from the basal plane and irradiated onto the fingerprint, and a light ray undergoes a first reflection and a second reflection with the basal plane and the mirror surface, respectively. After that, the output surface acts as a background surface and a light ray output as the light ray undergoes the second reflection for the image receiver to receive the light ray and form a fingerprint image, such that the advantages of maintaining an optical path effectively and reducing the volume of the optical fingerprint sensor are accomplished.