Optical Grid Virtual Spacing for Piezo Motor Positioning
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Solution Overview
Problem
Piezo motors used in optical grids for precise positioning, such as in barcode scanners, often suffer from limited resolution due to light beam wavelength constraints, leading to inaccurate focusing and positioning issues, especially when trying to achieve quarter-grid spacing precision.
Innovation Solution
The implementation of a virtual reduced spacing technique within the optical grid using two slightly offset light beams and a novel motor movement algorithm allows for quarter-grid spacing resolution, enabling precise positioning of a piezo motor by generating a pattern of transitions and calibrating clock cycles to accurately locate targets between optical grid elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If piezo motors are used for positioning in optical grids, then positioning speed is improved, but positioning precision deteriorates due to wavelength limitations
Solution Approach 1:
The patent transitions from direct physical measurement to a computational dimension by using signal processing and clock cycle counting to achieve sub-wavelength positioning precision. The system measures position by counting clock cycles during motor operation rather than relying solely on optical grid spacing, effectively adding a temporal measurement dimension that overcomes the spatial wavelength limitation.
Solution Approach 2:
The system changes the measurement parameter from spatial (optical grid spacing) to temporal (clock cycle counting). By measuring the time duration of motor operation in clock cycles and using this temporal data to calculate position, the system achieves precision beyond what is possible with the original spatial optical grid measurements alone.
2Measurement precision
If optical grid spacing is reduced to improve resolution, then measurement precision is improved, but light sensors pick up interfering signals
Solution Approach 1:
The patent introduces signal processing algorithms and clock cycle counting as an intermediary measurement method. Instead of directly reducing physical grid spacing, the system uses computational processing of motor operation time to achieve fine resolution, acting as a mediator that provides high precision without the harmful interference that would result from physical grid compression.
Solution Approach 2:
The system replaces the mechanical/optical measurement approach with an electronic timing-based approach. Instead of relying on physical optical grid elements and light sensor detection, the system uses electronic clock cycle counting during motor operation to determine position, substituting a mechanical/optical system with an electronic one that avoids signal interference issues.
3Measurement precision
If quarter-grid positioning is attempted to improve precision, then measurement precision is improved, but non-linear motor movement causes location errors
Solution Approach 1:
The patent performs preliminary characterization of the piezo motor's non-linear movement behavior. By pre-measuring and storing the relationship between clock cycles and actual motor displacement, the system compensates for non-linearity in advance, ensuring accurate positioning even when operating at quarter-grid precision levels.
Solution Approach 2:
The system implements feedback by using the counted clock cycles to continuously monitor and adjust motor positioning. The measured time duration provides real-time information about motor position that can be used to compensate for non-linear movement and achieve accurate quarter-grid positioning through iterative correction.
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 enhances the resolution of piezo motor positioning, allowing for accurate and precise focusing, reducing costs by avoiding the need for more expensive motors and additional hardware, while maintaining high measurement accuracy.
Implementation Method 1
light sources, which emit a beam of light, and light sensors, which become excited by variations in light and detect whether the beam of light is reflected back
Implementation Method 2
control piezo movement of a motor
Data Source
AI summary
Methods for performing a scheme that results in a refined measurement pattern within an optical grid are provided. Physically adjusting spacing of elements within an optical grid to achieve enhanced resolution is historically unfeasible, as reduction of the spacing causes light sensors of the optical grid to pick up false signals when reading light beams. Technology introduced by the present invention generates a virtual reduced spacing of the elements within the optical grid by using two signals that are slightly different. These slightly different signals can accomplish, at least, quarter-grid spacing resolution within the optical grid. Additionally, the enhanced resolution derived from the virtual reduced spacing is employed to govern movement of a motor. The motor movement is in response to one or more changes of direction such that the motor is operating in its linear range. Advantageously, the virtual reduced spacing allows for substantial movement in a non-linear phase, while only limited movement in a linear phase is necessary to locate accurately a target within the optical grid.