Optical Displacement Circuit for Height-Aware Pointing Detection
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Solution Overview
Problem
Existing optical pointing devices face issues with tracking accuracy due to variations in sensor height from the work surface, which can lead to misinterpretation of horizontal movements and reduced information availability, especially when the device is lifted or tilted.
Innovation Solution
A displacement detection method and circuit that utilize a pixel array to detect height variations by comparing auxiliary averages with a main average, allowing for optimal tracking capabilities by distinguishing between lifting and tilting motions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the sensor height is fixed and the spotlight is centered inside the active area, then the system design is simplified, but manufacturing tolerances and user movement cause the real height to differ from the nominal height, leading to tracking errors
Solution Approach 1:
The patent applies the dynamics principle by making the system adaptable to height variations. Instead of fixing the sensor height, the system dynamically detects the actual height through spotlight position analysis and adjusts displacement calculations accordingly. The pixel array continuously monitors spotlight position, and the system recalibrates based on detected height changes, transforming a static design into a dynamic one that compensates for manufacturing tolerances and user movement.
Solution Approach 2:
The patent implements feedback by using the pixel array to detect spotlight position and feed this information back to correct displacement measurements. The system monitors the actual spotlight location on the pixel array, compares it with the expected centered position, and uses this feedback to adjust the displacement calculation. This closed-loop feedback mechanism compensates for height variations without requiring complex mechanical adjustments.
2Adaptability or versatility
If the spotlight moves along the horizontal axis due to height changes, then the optical path accommodates height variation, but the sensor misinterprets the spotlight movement as horizontal movement of the working surface rather than an effect of height change
Solution Approach 1:
The patent applies inversion by reversing the interpretation logic. Instead of assuming spotlight movement always indicates surface displacement, the system inverts the approach by first detecting height changes through spotlight position analysis and then using this height information to correct the displacement measurement. The system asks 'what caused this spotlight movement?' and determines it's height variation rather than surface movement, thereby inverting the traditional interpretation sequence.
Solution Approach 2:
The patent introduces an intermediary mechanism - the auxiliary pixel arrays and spotlight position detection system - that mediates between the optical path and the displacement measurement. This intermediary detects the spotlight's actual position and provides correction data before the final displacement calculation is made, preventing the misinterpretation of height-induced spotlight movement as surface displacement.
3Reliability
If only part of the active area of the pixel array is illuminated due to height changes, then the optical system maintains focus, but less information is available for the sensor to measure the displacement
Solution Approach 1:
The patent applies segmentation by dividing the pixel array into multiple functional zones: a central primary pixel array for main displacement measurement and surrounding auxiliary pixel arrays for height detection and spotlight position monitoring. This segmentation allows different regions to serve different purposes - the central area maintains optimal illumination for displacement measurement while the auxiliary areas detect height changes and provide correction data, thereby preserving information despite partial illumination.
Solution Approach 2:
The patent implements multi-functionality by making the pixel array system perform multiple functions simultaneously. The same pixel array that detects displacement also detects spotlight position and infers height changes. The auxiliary pixel arrays serve dual purposes: detecting both the presence and position of the spotlight for height determination. This multi-functional approach maximizes information extraction from the available illuminated area.
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 method and circuit effectively quantify height changes and correct displacement values, ensuring accurate cursor movement by differentiating between lifting and tilting actions.
Implementation Method 1
measuring the varying intensity pattern of a portion of a surface which is illuminated with radiation of a light source
Implementation Method 2
a photodetector array for measuring the varying intensity pattern
Data Source
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AI summary
The present invention relates to a displacement detection circuit (100) configured to implement a displacement detection method (500) for a pointing device (199) having at least one pixel array (190). Said displacement detection circuit (100) comprises at least one main calculator (110), at least one auxiliary calculator (111, 112, 113) at least one comparator (130) and at least one motion detector (150). Said at least one main calculator (110) is configured to calculate at least one main average (210) corresponding to the average of said at least one pixel array (190), which is compared to at least one auxiliary average (211, 212, 213) of said at least one auxiliary calculator (111, 112, 113). According to the result of the comparison, said at least one motion detector (150) indicates at least one direction (250) of displacement of the pointing device (199).