3D Measuring Device Adaptive Light Pattern for PCB Solder Inspection
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Solution Overview
Problem
Existing three-dimensional measuring devices face challenges in achieving a balance between increasing the height range of measurement, maintaining high accuracy, and minimizing the number of imaging operations, which affects processing speed and efficiency, particularly when dealing with varying heights of cream solder on printed circuit boards.
Innovation Solution
A three-dimensional measuring device that combines the phase shift method and spatial encoding method, using an irradiation means to determine the appropriate imaging count based on height data, allowing for adaptive imaging operations to optimize measurement efficiency and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the gaps between the lines of the irradiated light pattern are widened to adjust to the maximum height among measurement objects, then the height range capable of measurement is increased, but resolution ability deteriorates and measurement accuracy worsens
Solution Approach 1:
The patent applies dynamics by making the light pattern gaps adaptive rather than fixed. The irradiation means dynamically adjusts the gaps between lines of the light pattern based on the actual height of the measurement object. This allows the system to optimize for both height range and measurement accuracy depending on the specific object being measured, resolving the contradiction between adaptability and precision.
2Measurement precision
If the gaps between the lines of the light pattern are narrowed to improve measurement accuracy, then measurement accuracy is improved, but the height range capable of measurement becomes insufficient
Solution Approach 1:
The system dynamically adjusts the light pattern configuration based on the measurement object's height. When measuring taller objects, the gaps are widened to accommodate the height range. When measuring shorter objects, the gaps are narrowed to improve measurement accuracy. This dynamic adaptation resolves the contradiction between accuracy and height range capability.
3Adaptability or versatility
If the spatial encoding method is combined with the phase shift method to increase the height range capable of measurement, then the height range is increased, but the number of imaging operations increases and processing speed decreases
Solution Approach 1:
The patent applies partial action by selectively using only the spatial encoding method when the measurement object's height exceeds the capability range of the phase shift method. For objects within the phase shift method's capability range, only that method is used. This selective application reduces the number of imaging operations compared to always using both methods, thereby maintaining processing speed while still achieving extended height range capability when needed.
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 enables an increase in the measurable height range while ensuring high accuracy and minimizing imaging operations, thereby improving measurement efficiency by determining the optimal imaging count based on the height of the measurement object.
Implementation Method 1
an irradiation means used that combines a light source and a sine wave pattern filter, and this irradiation means illuminates the printed circuit board using a light pattern having a sinusoidal (stripe shaped) light intensity distribution. Thereafter, points on the circuit board are measured using a CCD camera or the like disposed directly above the circuit board.
Implementation Method 2
In a three-dimensional measuring device using this phase shift method, an irradiation means is used that combines a light source and a sine wave pattern filter, and this irradiation means illuminates the printed circuit board using a light pattern having a sinusoidal (stripe shaped) light intensity distribution. Thereafter, points on the circuit board are measured using a CCD camera or the like disposed directly above the circuit board. In this case, intensity I of light at a point P on the measurement object in the image is given by the following equation: I=e+f×cos(φ) (within the formula, e=direct current optical noise (offset component), f=sine wave contrast (reflectivity), and φ=phase imparted by unevenness of the object).
Implementation Method 3
combining the above-described phase shift method with the spatial encoding method has been proposed to obtain a large height range capable of measurement while also attaining highly accurate measurement
Data Source
AI summary
A three-dimensional measuring device includes an irradiation means capable of irradiating a striped light pattern used for a spatial encoding method and a striped light pattern used for a phase shift method on a measurement object part on a board main body, an imaging means capable of imaging a measurement object part irradiated by the light pattern, an image control means for controlling imaging by the imaging means, a first calculation means for calculating a height of the measurement object part according to the phase shift method based on a multiplicity of image data imaged by the imaging means, and a second calculation means capable of using the spatial encoding method to identify a line corresponding to the measurement object part from among the image data at a time of calculation by the first calculation means by the phase shift method based on the image data.