Optical Navigation Module with Capacitive Lift Detection
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Solution Overview
Problem
Existing optical navigation modules require new mechanical and optical designs for each device, and changing the maximum lift height is costly due to precision manufacturing needs, limiting their adaptability and increasing costs.
Innovation Solution
The optical finger navigation module incorporates a capacitive sensor to detect lift height and switch between tracking motion and ambient light detection modes, using a substrate with a photo-detector array and light source to adapt to different lift heights without requiring new designs, and includes a capacitive sensor to interrupt motion data when the lift height exceeds a maximum, reducing power consumption in battery-operated devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If optical lift detection mechanisms are used based on image defocus or signal strength, then lift detection capability is achieved, but device complexity and manufacturing cost increase due to precision design requirements
Solution Approach 1:
The patent replaces the optical lift detection mechanism (based on image defocus or signal strength) with a capacitive sensor that directly measures lift height. This substitution eliminates the need for complex optical design and fine-tuning, as the capacitive sensor provides direct electrical measurement of the distance between the tracking surface and the optical navigation module, thereby reducing device complexity while maintaining lift detection capability.
Solution Approach 2:
The patent changes the detection parameter from optical properties (image focus, light intensity) to electrical capacitance. By measuring capacitance between the capacitive sensor and the tracking surface, the system directly obtains lift height information without requiring complex optical processing, simplifying the overall system design and manufacturing.
2Adaptability or versatility
If maximum lift height is changed in optical navigation modules, then adaptability to different devices is improved, but manufacturing cost increases due to new precision design requirements
Solution Approach 1:
The patent implements a universal optical navigation module design where the capacitive sensor can measure lift height across different devices and configurations. The module can be programmed with different maximum lift height thresholds to accommodate various applications without requiring physical redesign or precision manufacturing adjustments, thereby improving adaptability while maintaining ease of manufacture.
Solution Approach 2:
The patent makes the maximum lift height parameter dynamic and programmable rather than fixed by mechanical design. The capacitive sensor continuously measures lift height, and the system can adjust the maximum lift height threshold through software configuration, allowing the same hardware to adapt to different devices without costly remanufacturing.
3Reliability
If optical navigation modules operate continuously, then motion tracking capability is maintained, but power consumption increases in battery-operated devices
Solution Approach 1:
The patent uses the capacitive sensor to periodically monitor lift height and determine when the optical navigation module is in contact with or near the tracking surface. The system activates the light source and photo-detector array only when the capacitive sensor indicates appropriate conditions for tracking, thereby maintaining motion tracking capability while significantly reducing power consumption during periods when tracking is not needed.
Solution Approach 2:
The capacitive sensor provides continuous feedback about the lift height to the control system. Based on this feedback, the system intelligently activates or deactivates the power-consuming optical components, ensuring that motion tracking capability is maintained only when necessary while minimizing overall power consumption in battery-operated devices.
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 solution allows the optical navigation module to efficiently track motion within a specific lift height range, prevent erroneous data from excessive lift, and conserve power by switching to ambient light detection, enhancing adaptability and reducing manufacturing costs.
Implementation Method 1
a capacitive sensor to detect a lift height separating a tracking surface from the optical navigation module
Implementation Method 2
a light source to illuminate a tracking surface, and a sensor, such as a charge-coupled device (CCD), complementary metal-oxide-semiconductor (CMOS) imaging array, or a comb array, to capture an image or signal in light reflected from the surface
Data Source
AI summary
Optical navigation modules and methods of operating the same to sense relative movement between the optical navigation module and a tracking surface are provided. In one embodiment, the optical navigation module comprises: (i) a light source to illuminate at least a portion of a surface relative to which the optical navigation module is moved; (ii) an integrated circuit (IC) including a photo-detector array (PDA) to detect a light pattern propagated onto the PDA from the surface, and a signal processor to translate changes in the light pattern propagated onto the PDA into data representing motion of the optical navigation module relative to the surface; and (iii) a substrate to which the light source and IC are mounted, the substrate including an aperture in a light path between the surface and the PDA. Other embodiments are also disclosed.