Optical Mouse Illumination Correction Before Low-Bit ADC
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Solution Overview
Problem
Existing optical mice require high-bit-depth analog-to-digital converters (ADCs) to correct non-uniform illumination profiles, leading to increased power, hardware, and processing requirements due to digital calculations in the direct method.
Innovation Solution
The feedback method performs illumination profile correction iteratively in the analog domain using low-resolution digitized data, allowing corrections and processing before digitization, reducing the need for high-bit-depth ADCs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-bit-depth ADCs are used to correct non-uniform illumination profiles, then measurement precision is improved, but use of energy and device complexity increase
Solution Approach 1:
The patent replaces high-bit-depth digital signal processing with an analog domain solution. An analog gain stage with digitally controlled gain coefficients corrects the illumination profile before the ADC, allowing the use of low-bit-depth ADCs while maintaining correction accuracy. This substitution of analog processing for digital processing reduces power consumption and device complexity.
2Measurement precision
If high-bit-depth ADCs are used to correct non-uniform illumination profiles, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent replaces complex high-bit-depth digital processing hardware with a simpler analog gain stage. The analog gain stage applies illumination correction before digitization, enabling the use of low-bit-depth ADCs and reducing overall device complexity while maintaining measurement precision.
Solution Approach 2:
The patent performs illumination profile correction in advance, before the signal is digitized. By applying the gain correction in the analog domain prior to ADC conversion, the system avoids the need for complex post-digitization processing and high-bit-depth converters.
3Measurement precision
If digital calculations are performed in the direct method, then illumination correction is achieved, but use of energy and processing requirements increase
Solution Approach 1:
The patent substitutes analog domain processing for digital domain processing. By implementing the illumination correction through an analog gain stage with digitally controlled coefficients, the system eliminates the need for power-intensive digital calculations while achieving the same correction objective.
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
This approach significantly decreases power, hardware, and processing requirements while maintaining accurate displacement tracking by converging on optimal gain coefficients for illumination correction.
Implementation Method 1
An optical mouse is a computer mouse which uses a light source, typically a light-emitting diode (LED), and a light detector, such as an array of photodiodes, to detect movement of the mouse relative to a surface.
Implementation Method 2
a light detector, such as an array of photodiodes, to detect movement
Implementation Method 3
analog gain stage configured to pixelwise multiply pixels of a raw data pixel array with gain coefficients of a gain array
Data Source
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AI summary
A method is provided for applying an illumination correction for an optical computer mouse. The method comprises the steps of: flashing (101) a light source of the mouse directed towards a surface; accumulating (103) voltage on a pixel array of the mouse to obtain raw pixel values of an image frame in response to detecting light reflected from the surface; applying (105) analog correction to the raw pixel values based on digital gain coefficients to obtain an array of corrected pixel values forming corrected image data; digitizing (109) the corrected image data with an analog-to-digital converter to obtain digital pixel values forming digital image data; and updating (111) the digital gain coefficients so that a respective gain coefficient corresponding to a respective digital pixel value is incremented if the respective digital pixel value is below or equal to a given pixel threshold value, and so that the respective gain coefficient corresponding to the respective digital pixel value is decremented if the respective digital pixel value is above the given pixel threshold value.