3D Measurement Device Phase Shift Imaging Optimization
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Solution Overview
Problem
Existing three-dimensional measurement devices using the phase shift method require multiple imaging operations across different luminance levels, leading to increased measurement time, especially when dealing with printed circuit boards featuring solder paste, which complicates height measurement due to varying background colors and luminance differences.
Innovation Solution
A three-dimensional measurement device that employs a light source and grid to create striped light patterns, with a luminance controller and phase controller to adjust luminance and phase levels, allowing for efficient three-dimensional measurement by taking fewer images under optimized luminance conditions, using image data to determine gain and offset relationships for accurate measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple imaging operations are performed under different luminance levels to measure both high-brightness and low-brightness areas, then measurement accuracy is improved, but measurement time increases
Solution Approach 1:
The measurement area is segmented into a first measurement object area (solder area) and a second measurement object area (background area). The first area is measured using a first light pattern with first luminance, while the second area is measured using a second light pattern with second luminance. This segmentation allows each area to be measured under optimal luminance conditions, improving overall measurement accuracy while managing measurement time through targeted imaging strategies.
Solution Approach 2:
Instead of performing complete multi-phase imaging for both areas under both luminance levels, the patent applies partial imaging: the first area undergoes three-dimensional measurement based on a predetermined number of different image data, while the second area undergoes three-dimensional measurement based on only two different image data. This partial action approach reduces the total number of images required, thereby shortening measurement time while maintaining sufficient measurement accuracy for both areas.
2Measurement precision
If four different image data are taken for phase shift measurement, then measurement accuracy is improved, but imaging time increases
Solution Approach 1:
The patent applies partial imaging by requiring only two different image data for the second measurement object area (background area) instead of the conventional four image data. The phase relationship grasping unit utilizes the relationship between gain and offset determined from the first area's measurement to enable accurate phase calculation with reduced image data. This partial action reduces imaging time while maintaining measurement accuracy through intelligent use of available image data and mathematical relationships.
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 reduces imaging time by allowing three-dimensional measurement of both high-brightness and low-brightness areas with improved accuracy, using two images under different phases for the second measurement object area, thereby shortening the overall measurement time.
Implementation Method 1
a light source configured to emit a predetermined light
Implementation Method 2
a grid configured to convert the light emitted from the light source into a light pattern having a sinusoidal (striped) light intensity distribution
Implementation Method 3
image data taken by the imaging unit having intensity distributions I0, I1, I2 and I3 corresponding to these phases
Implementation Method 4
The phase of the light pattern is changed in, for example four different stages (φ+0, φ+90°, φ+180° and φ+270°) by changeover control of the above grid
Implementation Method 5
A height (Z) at each coordinates (X,Y) on a measurement object is determined by using this phase φ, based on the principle of triangulation
Data Source
AI summary
A three-dimensional measurement device includes a light source and grid that irradiate a measurement object; a luminance controller that changes luminance levels of the light; a phase controller that changes phase levels of the light pattern; a camera that takes an image of the measurement object; and a processor that three-dimensionally measures a first measurement object area based on different image data taken by radiating a first light pattern in different phases; determines a relationship between a gain and offset determined according to an imaging condition based on the different image data; and three-dimensionally measures a second measurement object area based on two different image data taken by radiating a second light pattern in two different phases by using a gain and offset regarding each pixel determined according to a luminance value of each pixel in the two different image data and the determined relationship.