3D Measurement Apparatus Using Phase Shift Calibration
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Solution Overview
Problem
Three-dimensional measurement using the phase shift method requires multiple imaging operations, significantly increasing measurement time, especially when inspecting large numbers of objects on a printed circuit board.
Innovation Solution
A three-dimensional measurement apparatus that reduces imaging time by obtaining measurement values at two positions, using a first light pattern at multiple phases and a second light pattern at a single phase shifted by half a pixel, allowing for more accurate and higher-resolution measurements with fewer imaging operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple imaging operations are performed at different positions with phase shift method, then measurement accuracy is improved, but measurement time is significantly increased
Solution Approach 1:
The patent applies preliminary action by performing calibration imaging at the first position before measurement imaging at the second position. The calibration images capture gain and offset values that are then used to correct the measurement images, eliminating the need to perform calibration at each measurement position. This preliminary calibration step reduces the total number of imaging operations required while maintaining measurement accuracy.
Solution Approach 2:
The patent uses copying by capturing calibration data (gain and offset values) at the first position and reusing this calibration information for measurements at the second position. Instead of performing complete calibration procedures at each position, the system copies the calibration parameters and applies them to correct measurement images taken at different positions, significantly reducing imaging time while preserving measurement precision.
2Measurement precision
If phase is changed in four different stages to take four image data, then measurement accuracy is ensured, but imaging time is extended
Solution Approach 1:
The patent applies partial action by performing phase shift imaging with only three phases (0°, 120°, 240°) instead of the conventional four phases. This reduced phase sequence is sufficient to calculate height information when combined with images from multiple positions, achieving the required measurement accuracy with fewer imaging operations and faster imaging speed.
3Manufacturing precision
If measurement is performed at two positions with half-pixel shift, then measurement resolution is improved, but total imaging operations increase
Solution Approach 1:
The patent merges the calibration process and measurement process into an optimized sequence. By performing calibration at the first position and then using those calibration parameters for measurements at the second position, the system combines multiple functions into a streamlined workflow. This merging reduces the total number of imaging operations required while maintaining the half-pixel shift benefit for improved resolution.
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 configuration significantly shortens measurement time while maintaining high accuracy, enabling faster inspection of printed circuit boards and expanding the measurable height range with improved resolution.
Implementation Method 1
grids configured to convert the light emitted from the light source into a light pattern having a light intensity distribution in a sinusoidal waveform (fringe-like pattern)
Implementation Method 2
an imaging unit configured to take an image of reflected light from the measurement object irradiated with the light pattern
Implementation Method 3
A height (Z) at each coordinates (X,Y) on the measurement object such as solder paste is then determined by using this phase φ, based on the principle of triangulation
Data Source
AI summary
A measurement apparatus includes an illumination device irradiating an object with a first and a second pattern, a camera taking image data of the object, a motor displacing the object, and a processor measuring the object, obtaining a first value of the object based on a first number of image data taken with the first pattern at a first number of phases at a first position, obtaining a gain and/or offset based on the first number of image data, obtaining a second value of the object based on the gain and/or offset and a second number of image data taken with the second pattern at a second number of phases at a second position, obtaining height data of the object based on the first and the second value, and obtaining the second value with an average of the gain and/or offset of pixels adjacent to each pixel.