Dense Multi-Axis Photosensitive Array for Motion Sensing
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Solution Overview
Problem
Conventional optical pointing devices, such as mechanical mice and previous optical mice architectures, suffer from inaccuracy and limited redundancy in detecting motion, especially along off-axis directions, due to dirt accumulation and insufficient signal redundancy.
Innovation Solution
A dense multi-axis array of photosensitive elements is employed, arranged along three or more axes in a space-filling configuration, allowing motion detection by measuring differential photocurrents between elements, which increases signal redundancy and reduces signal dropouts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two or more one dimensional arrays are used at orthogonal angles to track motion, then motion detection in two directions is achieved, but accuracy along off-axis directions deteriorates due to insufficient signal redundancy
Solution Approach 1:
The patent transitions from using separate 1D arrays arranged orthogonally to a single 2D array with elements arranged along three or more non-orthogonal axes. This dimensional change allows the array to capture motion information from multiple directions simultaneously, providing signal redundancy without requiring multiple separate detector arrays. The 2D configuration enables off-axis motion to be detected with sufficient signal buildup, resolving the contradiction between measurement precision and reliability.
Solution Approach 2:
The 2D array with multi-axis configuration serves multiple functions simultaneously: it detects motion along multiple axes, provides signal redundancy for off-axis movement, and maintains compact form factor. Each photosensitive element contributes to multiple measurement axes, making the system universally capable of detecting motion in any direction within the detection plane, thereby improving both accuracy and reliability.
2Device complexity
If orthogonal linear comb arrays are used, then simplified data processing is achieved, but signal to noise ratio deteriorates for off-axis motion due to small signal buildup
Solution Approach 1:
By arranging photosensitive elements in a 2D configuration along three or more non-orthogonal axes rather than separate 1D orthogonal arrays, the system enables off-axis motion to produce sufficient signal buildup. The multi-axis 2D arrangement ensures that motion in any direction activates multiple detector elements simultaneously, improving signal to noise ratio while maintaining manageable data processing through correlation-based motion detection algorithms.
3Measurement precision
If mechanical elements like shaft encoders are used, then motion detection is achieved, but device lifespan deteriorates due to wear and dirt accumulation
Solution Approach 1:
The patent replaces mechanical motion detection elements (shaft encoders, rotating balls) with an optical detection system using a 2D array of photosensitive elements. This substitution eliminates mechanical wear and dirt accumulation issues, as the optical system detects motion through light correlation without physical contact between moving parts. The photosensitive array maintains measurement precision while significantly extending device lifespan by removing mechanical failure modes.
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 improved accuracy and resistance to signal fade during off-axis movement, reduces signal dropouts, and efficiently utilizes space by enabling multiple dependent axes within a confined area, enhancing the reliability and performance of optical displacement sensors.
Implementation Method 1
a two dimensional array of multiple photosensitive elements... motion is determinable along each of the axes by measuring differential photocurrents between photosensitive elements along each of the axes
Data Source
AI summary
The present disclosure describes an optical displacement sensor having a dense multi-axis array of photosensitive elements. Generally, the sensor includes a two dimensional array of multiple photosensitive elements. In one embodiment, the array includes multiple linear arrays of photosensitive elements arranged along three or more axes in a space-filling, close-packed multi-axis array. The photosensitive elements are connected to each other in such a way that motion is determinable along each of the axes by measuring differential photocurrents between photosensitive elements along each of the axes. The inventive architecture advantageously increases signal redundancy, and reduces signal drop-out or low signals due to random fluctuations in the incident or absorbed light or in the signals from the photosensitive elements.