Optical Navigation Device Brightness Differential State Detection
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Solution Overview
Problem
Conventional optical navigation devices face challenges in accurately determining whether they are lifted from a work surface due to interference from noise and ambient light, especially on surfaces with low reflectance, leading to cursor jitter and operating errors.
Innovation Solution
The optical navigation device employs a light source with adjustable brightness values and an image sensor to calculate differential images and average intensity differences, using these metrics to identify the operating state and enter a sleep mode when necessary, while normalizing with exposure parameters to enhance accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If image quality is used to determine lifting state, then the device can enter sleep mode, but noise and ambient light cause false detection leading to cursor jitter
Solution Approach 1:
The patent changes the parameter used for detection from general image quality to average intensity difference of differential images. By illuminating the work surface with different brightness values and calculating the difference between image frames, the system creates a new parameter that is insensitive to ambient light and noise, thereby resolving the contradiction between reliable sleep mode activation and accurate operating state identification
Solution Approach 2:
The patent introduces differential images as an intermediary between the raw image frames and the operating state determination. By calculating the difference between image frames taken at different brightness levels, the system creates an intermediate representation that eliminates ambient light interference, allowing accurate detection without false positives
2Device complexity
If conventional image quality detection is used, then the system is simple, but it cannot accurately identify operating state on low-reflectance surfaces
Solution Approach 1:
The patent transforms the detection parameter from absolute image quality metrics to differential intensity measurements. By illuminating at multiple brightness levels and computing differences, the method adapts to low-reflectance surfaces where conventional single-level detection fails, improving measurement precision while maintaining reasonable system complexity
Solution Approach 2:
The patent employs periodic illumination at different brightness values to actively probe the work surface reflectance characteristics. This periodic action allows the system to distinguish between low reflectance due to surface properties versus low signal due to lifting, thereby maintaining accuracy on challenging surfaces
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 effectively eliminates interference from noise and ambient light, allowing for accurate identification of the operating state, even on low-reflectance surfaces, thereby improving the device's accuracy and preventing unnecessary sleep mode activation.
Implementation Method 1
at least one light source (11), a light control unit (151), an image sensor (13) and a processing unit (15). The light source (11) is configured to illuminate the work surface (S)
Implementation Method 2
The image sensor (13) receives reflected light from the work surface (S) and outputs a first image frame (I1) corresponding to the first brightness value and a second image frame (I2) corresponding to the second brightness value
Data Source
AI summary
There is provided an optical navigation device including at least one light source, an image sensor and a processing unit. The light source illuminates a work surface in a first brightness value and a second brightness value. The image sensor receives reflected light from the work surface and outputs a first image frame corresponding to the first brightness value and a second image frame corresponding to the second brightness value. The processing unit calculates a differential image of the first image frame and the second image frame and identifies an operating state according to the differential image.