Optical Navigation Sensor Circuit Power Management
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Solution Overview
Problem
Optical navigation systems using speckle-based detectors face signal fading issues, leading to erratic and unreliable displacement estimation, which affects overall performance, and current solutions increase complexity and power consumption.
Innovation Solution
The implementation of redundant 2D comb-arrays with a control circuit that dynamically powers down one array to reduce power consumption, using a signal processing method that combines motion data from both arrays to mitigate signal fading and adjust illumination levels with an automatic gain control circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If redundant arrays are used to mitigate signal fading, then reliability is improved, but power consumption increases
Solution Approach 1:
The system dynamically switches between single-array and dual-array modes based on signal quality conditions. The control circuit monitors signal fading and activates the second array only when needed, making the redundancy dynamic rather than static, thus reducing average power consumption while maintaining reliability when required
Solution Approach 2:
The system changes the operational state parameter of the arrays from always-on to conditionally-active. By monitoring signal quality parameters and adjusting the activation state of redundant arrays accordingly, the system optimizes the balance between reliability and power consumption
2Reliability
If signal processing complexity is increased to minimize signal fading impact, then reliability is improved, but device complexity increases
Solution Approach 1:
The system segments the signal processing task by dividing it between a control circuit that handles basic monitoring and switching, and a signal processor that handles complex calculations only when needed. This segmentation allows simple continuous operation with complex processing activated only during signal fading conditions
Solution Approach 2:
The control circuit acts as an intermediary between the arrays and the signal processor, filtering and pre-processing signals before they reach the main processor. This intermediary layer reduces the complexity burden on the main signal processor while maintaining reliable displacement estimation
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 reduces power consumption while maintaining system performance by minimizing the impact of signal fading and optimizing power usage based on required accuracy and precision, making it suitable for power-sensitive applications like wireless mice.
Implementation Method 1
a two-dimensional (2D) array of photosensitive elements or detectors, such as photodiodes
Data Source
AI summary
A circuit and method are provided for reducing power consumption in an optical navigation system for use in an input device to sense displacement of the device relative to a surface. Generally, the system includes: (i) an optical sensor having at least first and second arrays of photosensitive elements; (ii) imaging optics to map an illuminated portion of the surface to the optical sensor; (iii) a signal processor including a first and second sensor circuits coupled to the respective first and second arrays to generate from each array a set of signals in response to motion of light received thereon; and (iv) a control circuit capable of independently switching power to the sensor circuits. In one embodiment, the control circuit powers down one sensor circuit when the strength of the set of signals from the other is greater than a predetermined minimum thereby maintaining device performance. Other embodiments are also disclosed.