Micro-Mirror Array Self-Calibration via Capacitance Measurement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for calibrating micro-mirror array devices, especially when used as variable focal length lenses, are inefficient for run-time characterization and production throughput due to the time-consuming nature of optical metrology techniques, which cannot account for drift in the voltage-tilt angle characteristic during operation.
Innovation Solution
A built-in self-calibration method using capacitance measurements to determine the voltage-tilt angle characteristic by defining reference tilt angles, measuring capacitance, interpolating between them, and applying a voltage sweep to associate capacitance values with tilt angles, allowing for run-time calibration and storage for adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical metrology techniques are used to characterise voltage-tilt angle relationship, then measurement precision is improved, but productivity deteriorates due to time-consuming characterization of each micro-mirror element
Solution Approach 1:
The patent replaces optical metrology techniques with electrical capacitance measurements to characterize the voltage-tilt angle relationship. By measuring capacitance between the micro-mirror and backplate at different tilt angles and voltages, the system achieves accurate characterization without the time-consuming optical inspection process, thereby improving productivity while maintaining measurement precision.
2Measurement precision
If optical metrology techniques are used for characterisation, then measurement precision is improved, but loss of time increases making run-time calibration impossible
Solution Approach 1:
The patent substitutes optical measurement systems with electrical capacitance sensing to determine the voltage-tilt angle relationship. This electrical approach provides rapid measurements that enable run-time calibration, eliminating the time loss associated with optical metrology while preserving measurement accuracy through capacitance-based characterization.
Solution Approach 2:
The micro-mirror array device performs self-calibration by measuring its own capacitance characteristics at different operating conditions. The device uses its inherent capacitance properties to automatically determine the voltage-tilt angle relationship without requiring external optical metrology equipment, enabling fast run-time calibration that compensates for drift.
3Reliability
If comprehensive characterisation is performed before device operation, then reliability is improved, but loss of time increases preventing run-time calibration
Solution Approach 1:
The patent performs preliminary capacitance measurements at defined reference tilt angles to establish the voltage-tilt angle relationship before full operation. This preliminary characterization provides the baseline data needed for reliable operation, while the fast electrical measurement method ensures it can be completed quickly without preventing subsequent run-time calibration.
Solution Approach 2:
The device performs its own reliability characterization by measuring capacitance relationships internally. This self-characterization capability ensures reliable operation while minimizing time loss, and the same self-service mechanism enables ongoing run-time calibration to maintain reliability throughout the device lifecycle.
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
Enables fast and efficient run-time calibration of micro-mirror arrays, improving production throughput and accounting for drift in the voltage-tilt angle characteristic, enhancing the quality and performance of micro-mirror array devices.
Implementation Method 1
determining a capacitance measurement for each micro-mirror element corresponding to each reference tilt angle
Implementation Method 2
the tilt of the micro-mirror is controlled by the actuation of electrodes associated with the micro-mirror, for example, by using an applied voltage
Data Source
AI summary
A built-in self-calibration system and method for a micro-mirror array device, for example, operating as a variable focal length lens is described. The calibration method comprises determining a capacitance value for each micro-mirror element in the array device at a number of predetermined reference angles to provide a capacitance-reference angle relationship. From the capacitance values, an interpolation step is carried to determine intermediate tilt angles for each micro-mirror element in the array. A voltage sweep is applied to the micro-mirror array and capacitance values, for each micro-mirror element in the array, are measured. For a capacitance value that matches one of the values in the capacitance-reference angle relationship, the corresponding voltage is linked to the associated tilt angle to provide a voltage-tilt angle characteristic which then stored in a memory for subsequent use.