Optical Pointer Defective Pixel Detection and Exclusion
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Solution Overview
Problem
Existing methods for defective pixel detection in optical pointing devices do not effectively address issues caused by misaligned illumination sources and do not exclude defective pixels from navigation computations, leading to errors in motion detection.
Innovation Solution
An optical pointing device with a light source and navigation sensor that detects defective pixels by using adaptive and fixed thresholds, as well as a smooth frame method to identify and exclude aberrant pixels from motion computation, ensuring accurate navigation data generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If defective pixels are not excluded from navigation computations, then all pixel data is utilized for motion detection, but navigation accuracy deteriorates due to biased computations from defective pixels
Solution Approach 1:
The patent applies preliminary action by detecting and identifying defective pixels before they are used in navigation computations. The system performs defective pixel detection in advance, creates a mask to exclude these pixels, and then uses only the valid pixels for motion detection and navigation calculations, preventing biased results from the outset.
Solution Approach 2:
The patent extracts and removes defective pixel data from the navigation computation process. By creating a defective pixel mask that identifies stuck high, stuck low, and abnormal sensitivity pixels, the system separates valid pixel data from invalid data, ensuring that only reliable pixel values contribute to motion detection and navigation accuracy.
2Manufacturing precision
If existing BPC techniques replace bad pixel values with good values from neighboring pixels, then defective pixel locations are filled, but navigation computations remain biased as defective pixels are not excluded
Solution Approach 1:
The patent inverts the conventional BPC approach. Instead of replacing defective pixel values with estimated values from neighboring pixels (as done in digital cameras), the system excludes defective pixels entirely from navigation computations by creating a mask that sets their weights to zero, thereby preventing them from biasing the motion detection results.
3Illumination intensity
If the illumination source becomes misaligned, then portions of the photodetector array receive inadequate illumination, but existing methods cannot distinguish these pixels as defective
Solution Approach 1:
The patent applies feedback by continuously monitoring pixel response characteristics and using this information to identify defective pixels. The system analyzes pixel values across multiple frames, detects patterns indicating defective pixels (such as stuck high, stuck low, or abnormal sensitivity), and adjusts the navigation computation by excluding these pixels through masking, thereby maintaining navigation accuracy despite illumination variations.
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 identifies and excludes defective pixels, improving navigation accuracy and robustness to noise and illumination misalignment issues, enhancing the reliability of optical pointing devices.
Implementation Method 1
a light source for illuminating an imaging surface, thereby generating reflected images
Implementation Method 2
Each individual photodetector operates to output a signal with a magnitude that is proportional to the intensity of light incident on the site of the photodetector
Data Source
AI summary
An apparatus for controlling the position of a screen pointer includes a light source for illuminating an imaging surface, thereby generating reflected images. The apparatus includes a navigation sensor for generating digital images based on the reflected images, detecting defective pixel locations in the digital images, and generating movement data based on the digital images that is indicative of relative motion between the imaging surface and the apparatus.