Monolithic Light Pipe Array Lens for Optical Finger Navigation
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Solution Overview
Problem
Conventional optical finger navigation devices are costly due to the use of expensive optical elements for manipulating light reflected from a finger onto an image sensor array.
Innovation Solution
A light pipe array lens is used, comprising a monolithic block with a two-dimensional array of light pipes made of a first material enclosed by a second material with a lower index of refraction, functioning similarly to a fiber bundle lens but at a lower cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional optical elements are used to manipulate light reflected from a finger onto an image sensor array, then optical manipulation function is achieved, but device cost increases
Solution Approach 1:
The patent creates a simplified copy of the traditional fiber bundle lens structure using light pipes formed directly in a monolithic block of optical material. Instead of using expensive optical fibers, the invention uses molded light pipe structures that replicate the light-guiding function at a fraction of the cost, while maintaining the essential optical manipulation capabilities needed for finger navigation
Solution Approach 2:
The patent changes the physical and material parameters of the optical system by forming light pipes directly in a monolithic block of optical material with specific refractive index properties. The light pipes have different refractive indices than the surrounding material, enabling total internal reflection and efficient light transmission without requiring expensive precision optical elements
2Use of energy by moving object
If a fiber bundle lens is used to transmit light, then light transmission efficiency is achieved, but manufacturing cost increases
Solution Approach 1:
The patent replaces expensive, fragile optical fibers with inexpensive, easily manufactured light pipes formed in a monolithic block. The light pipes can be mass-produced using standard molding techniques, making the optical system much more cost-effective while maintaining sufficient light transmission efficiency for the application
Solution Approach 2:
The patent uses composite material structures where light pipes with different refractive indices are formed within a monolithic block of optical material. This composite structure enables efficient light transmission through total internal reflection at the interfaces between materials with different refractive indices, achieving fiber-bundle-like performance with simpler manufacturing
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 light pipe array lens provides a cost-effective solution for optical finger navigation devices by efficiently transmitting light from a navigation surface to an image sensor array, enabling accurate tracking of relative movements while reducing overall device costs.
Implementation Method 1
Each of the light pipes is enclosed by a second material having an index of refraction lower than an index of refraction of the first material
Data Source
AI summary
An optical finger navigation device and method for making the device uses a light pipe array lens, which includes an array of light pipes formed in a monolithic block of material. The light pipe array lens is configured to function similarly to a fiber bundle lens to transmit light through the lens using the light pipes in the monolithic block of material.