Single-Package Optical Mouse Sensor Integrating VCSEL and Photodiode Array
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Solution Overview
Problem
Mechanical mice are prone to inaccuracy and malfunction due to dirt accumulation and wear, while optical mice face complex design and low optical efficiency issues.
Innovation Solution
An optical navigation apparatus with a single packaged silicon die integrating a VCSEL light source, photodiode array, and microcontroller, which uses coherent light to form a speckle pattern for accurate position tracking without the need for external calibration or alignment, and includes capacitive sensing for user input detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical mice use a rotating ball and shaft encoders to detect motion, then they provide basic pointing functionality, but they are prone to inaccuracy and malfunction due to dirt accumulation and wear
Solution Approach 1:
The patent replaces the mechanical ball and shaft encoder system with an optical detection system using a laser source, illumination optics, collection optics, and a photodiode array. This substitution eliminates mechanical wear and dirt accumulation issues while maintaining motion detection functionality through optical means.
Solution Approach 2:
The patent integrates multiple functional components (light source, illumination optics, collection optics, photodiode array, and processing circuitry) into a single integrated package. This merging reduces the overall system complexity and improves reliability by minimizing the number of separate mechanical interfaces and potential failure points.
2Measurement precision
If optical mice use LED illuminating at grazing incidence with a two-dimensional CMOS detector, then they provide high pointing accuracy, but they have complex design and low optical efficiency
Solution Approach 1:
The patent changes the illumination parameter from LED grazing incidence to laser illumination at optimized angles. The laser source provides coherent light that creates a speckle pattern, enabling more efficient optical interaction with the surface while maintaining high measurement precision through the photodiode array detection system.
Solution Approach 2:
The patent replaces the LED-based illumination system with a laser-based system that uses coherent light to generate speckle patterns. This substitution improves optical efficiency by reducing energy loss and enhancing the signal-to-noise ratio in the optical detection process.
3Measurement precision
If optical mice use LED illuminating at grazing incidence with a two-dimensional CMOS detector, then they provide high pointing accuracy, but they have complex design requirements
Solution Approach 1:
The patent combines the light source, illumination optics, collection optics, and photodiode array into a single integrated package with unified alignment. This merging simplifies the overall design by eliminating the need for separate calibration and alignment procedures that would be required for multiple discrete components.
Solution Approach 2:
The integrated package design enables self-alignment of optical components, eliminating the need for external calibration or manual adjustment during assembly. The components are pre-aligned within the package, reducing design and manufacturing complexity while maintaining high measurement precision.
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 provides robust, accurate, and efficient cursor movement tracking with reduced complexity and increased optical efficiency, enhancing the lifespan and performance of pointing devices.
Implementation Method 1
uses coherent light to form a speckle pattern
Implementation Method 2
Light from a coherent source scattered off of a rough surface generates a random intensity distribution of light known as speckle
Implementation Method 3
a photodiode array configured at the detection plane to receive the speckle pattern of the scattered light
Data Source
AI summary
An optical navigation apparatus including a package incorporating a light source and a single die of silicon. The single die of silicon includes a photodiode array configured at the detection plane to receive the speckle pattern of the scattered light from the collection optics, circuitry configured to process signals from the photodiode array to determine changes in position of the apparatus relative to the tracking surface, analog circuitry configured to control and drive current through the light source, interface circuitry configured to communicate position data by outputting the position data via a data interface, a microcontroller comprising a processor core and memory for storing computer-readable code and data, and a system bus configured to communicate instructions and data between the microcontroller and said digital, analog, and interface circuitries. Other embodiments, aspects and features are also disclosed.