Dynamic Shutter Threshold Calibration for Optical Navigation
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Solution Overview
Problem
Conventional optical imagers face challenges in accurately detecting the presence or absence of a navigation object due to variability in shutter values caused by changing ambient light conditions, leading to erroneous movement detection and noise issues.
Innovation Solution
A system comprising a sensor array, shutter controller, and threshold generator that dynamically adjusts shutter thresholds based on stable shutter set values for finger-on and finger-off states, adapting to ambient light conditions to improve navigation signal accuracy and reduce noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If variable shutter values are used to continuously adjust to ambient light conditions, then the optical imager can optimize navigation signals under changing light conditions, but the variability makes it difficult to detect transitions between navigation states and causes erroneous movement detection
Solution Approach 1:
The system dynamically adjusts shutter values based on detected ambient light conditions while maintaining stability through hysteresis thresholds. The shutter controller continuously monitors ambient light levels and modifies shutter duration accordingly, allowing the system to adapt to changing environmental conditions without causing spurious state transitions. This dynamic adjustment resolves the contradiction by enabling both adaptability and precise state detection through controlled variability.
Solution Approach 2:
The system implements feedback mechanisms where the shutter controller monitors both ambient light conditions and navigation state transitions. By feeding back the detected transitions and ambient light levels, the system can adjust shutter values to maintain stable state detection. The hysteresis thresholds provide feedback-based control that prevents oscillation between states while allowing smooth adaptation to ambient light changes.
2Reliability
If fixed shutter threshold values are used to regulate noise during state transitions, then the optical imager can limit noise from ambient light entering before transition, but the fixed thresholds become ineffective when ambient light levels vary relative to internal light conditions
Solution Approach 1:
The system replaces fixed shutter thresholds with dynamic thresholds that adapt to ambient light conditions. The shutter controller continuously adjusts the threshold values based on detected ambient light levels, ensuring that noise regulation remains effective regardless of whether ambient light is stronger or weaker than internal light conditions. This dynamic threshold adjustment resolves the contradiction by maintaining both reliability and adaptability.
Solution Approach 2:
The system changes the parameter values of shutter thresholds based on ambient light conditions. By modifying threshold parameters dynamically rather than using fixed values, the system can maintain effective noise regulation across varying ambient light scenarios. The parameter adjustment ensures that the thresholds remain appropriate relative to both ambient and internal light conditions.
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 dynamic adjustment of shutter thresholds enhances the detection of navigation object presence or absence, reducing spurious navigation movements and sensor array noise, leading to more accurate navigation signals and improved user input device performance.
Implementation Method 1
The sensor array obtains image data in response to light incident on the sensor array
Data Source
AI summary
A user input device to generate a shutter threshold adaptive to ambient light conditions. The user input device includes a sensor array, a shutter controller, and a threshold generator. The sensor array obtains image data in response to light incident on the sensor array. The shutter controller is coupled to the sensor array. The shutter controller controls a shutter time during which the sensor array is responsive to the light incident on the sensor array according to a shutter value. The threshold generator is coupled to the shutter controller. The threshold generator dynamically generates a shutter threshold corresponding to the shutter value. The shutter threshold defines a transition of a finger-on/off state.