Optical Mouse Locus Smoothing via Displacement Accumulation
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Solution Overview
Problem
Conventional optical mice produce zigzag loci due to noise in image frames, affecting user operation accuracy during fine movements.
Innovation Solution
An optical device and locus smoothing method that outputs zero displacement when accumulated displacement does not exceed a threshold, and outputs average displacement when the accumulated parameter reaches a predetermined value, thereby reducing noise interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the optical mouse outputs displacement with a fixed report rate, then the response speed is maintained, but noise causes zigzag loci that reduce measurement precision
Solution Approach 1:
The patent applies preliminary action by accumulating small displacements before outputting them. The processing unit accumulates multiple small displacement values that would otherwise cause zigzag loci, and only outputs the accumulated value when it exceeds a threshold or a predetermined number of accumulations are reached. This preliminary accumulation filters out noise while maintaining the report rate timing.
Solution Approach 2:
The patent changes the output parameter from individual small displacements to accumulated displacements. By transforming the output parameter from raw displacement values to threshold-exceeding accumulated values, the system eliminates zigzag loci while maintaining the required report rate for responsive cursor movement.
2Measurement precision
If small displacements are output directly, then the response sensitivity is high, but noise interference creates zigzag loci
Solution Approach 1:
The patent converts the harmful effect of noise into a beneficial filtering mechanism. By accumulating small displacements including noisy ones and only outputting when the accumulated value exceeds a threshold, the system transforms individual noisy measurements into a smoothed output that eliminates zigzag loci while preserving detectable movement patterns.
Solution Approach 2:
The patent introduces an intermediary accumulation mechanism between the image sensor and the output. The processing unit acts as an intermediary that accumulates small displacements and applies threshold filtering, serving as a mediator that eliminates noise while preserving the essential movement information for cursor control.
3Stability of the object's composition
If displacement threshold filtering is applied, then locus smoothness is improved, but the device complexity increases
Solution Approach 1:
The patent applies self-service by using the processing unit's existing displacement calculation capability to also perform accumulation and threshold filtering. The same processing unit that calculates displacement from image frames also accumulates these values and determines when to output, eliminating the need for separate filtering hardware and reducing overall device complexity.
Data Source
AI summary
There is provided an optical navigation device including an image sensor, a processing unit, a storage unit and an output unit. The image sensor is configured to successively capture images. The processing unit is configured to calculate a current displacement according to the images and to compare the current displacement or an accumulated displacement with a threshold so as to determine an outputted displacement. The storage unit is configured to save the accumulated displacement. The output unit is configured to output the outputted displacement with a report rate.