Stacked Optical Imaging Apparatus for SMT Screen Printer Alignment
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Solution Overview
Problem
Current imaging apparatuses for reference mark measurement and inspection in solder paste printing suffer from low precision, speed, and reliability, especially in high-density SMT production, due to mechanical positioning limitations and manual inspection subjectivity, which are inadequate for modern electronic component demands.
Innovation Solution
The imaging apparatus features a compact structure with two stacked light sources, beamsplitters, optical reflectors, and image sensors, forming a T- or L-shaped configuration, allowing simultaneous orthogonal illumination and imaging in both upward and downward directions, utilizing a ring light source for lateral illumination and digital image processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a low-angle ring light source, two light sources, a beamsplitter, an optical reflector, an imaging lens and an image sensor are used with light sources illuminating at different time, then the light path is simple and cost is low, but the image acquiring positions of the lower image and the upper image are inconsistent and the dimension of the imaging apparatus in the direction of the upward and downward light path is too large
Solution Approach 1:
The patent merges the upward and downward illumination functions into a single light source positioned at the center of the screen, eliminating the need for separate light sources for each direction. This consolidation simplifies the overall light path structure while ensuring that both upward and downward images are acquired from the same positional reference point, thereby resolving the position inconsistency issue.
Solution Approach 2:
The single light source serves multiple functions by providing illumination for both upward and downward image acquisition simultaneously. This multi-functional design eliminates the complexity of having separate illumination systems for different directions while maintaining consistent imaging positions, thus improving measurement precision without significantly increasing device complexity.
2Device complexity
If a low-angle ring light source, two light sources, a beamsplitter, an optical reflector, an imaging lens and an image sensor are used with light sources illuminating at different time, then the light path is simple and cost is low, but the dimension of the imaging apparatus in the direction of the upward and downward light path is too large
Solution Approach 1:
The patent merges the upward and downward illumination functions into a single light source positioned at the center of the screen, eliminating the need for separate light sources for each direction. This consolidation simplifies the overall light path structure while ensuring that both upward and downward images are acquired from the same positional reference point, thereby resolving the position inconsistency issue.
Solution Approach 2:
The single light source serves multiple functions by providing illumination for both upward and downward image acquisition simultaneously. This multi-functional design eliminates the complexity of having separate illumination systems for different directions while maintaining consistent imaging positions, thus improving measurement precision without significantly increasing device complexity.
3Ease of manufacture
If mechanical positioning with holes and sinker bars is used, then the alignment method is simple, but the precision is low and the speed is low
Solution Approach 1:
The patent replaces the mechanical positioning system (holes and sinker bars) with an optical imaging system that uses a single light source, beamsplitter, and image sensor to capture and process images for alignment. This substitution eliminates mechanical contact and positioning holes, thereby significantly improving measurement precision and alignment speed while maintaining ease of implementation through optical methods.
4Ease of manufacture
If manual inspection is used for solder paste printing quality, then the inspection method is simple, but the reliability is low due to subjectivity and vision fatigue
Solution Approach 1:
The patent replaces manual visual inspection with an automated optical imaging system that captures images of the solder paste printing process and uses image processing to objectively evaluate printing quality. This substitution eliminates human subjectivity and vision fatigue, thereby significantly improving inspection reliability while maintaining simplicity through automated image analysis.
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 design enables high-speed, high-precision alignment and inspection with minimized relative movement between the screen and printed circuit board, improving image quality and adaptability to high-density SMT production requirements.
Implementation Method 1
the beams of light are reflected back to the beamsplitter and refracted to the imaging lens by the beamsplitter
Implementation Method 2
the beams of light are reflected back to the beamsplitter
Implementation Method 3
the optical reflectors are provided with an upward reflection plane and a downward reflection plane
Data Source
AI summary
An imaging apparatus for fully automatic screen printer including two stacked light sources, two stacked beamsplitters, two stacked optical reflectors, two stacked imaging lens and two stacked image sensors, wherein the two stacked optical reflectors and the two stacked light sources are correspondingly disposed on two different sides of the two beamsplitters, the two stacked imaging lens are disposed on another side of the beamsplitters different from that of the optical reflectors and the light sources, the two stacked image sensors are disposed behind the imaging lens; the optical reflectors are provided with an upward reflection plane and a downward reflection plane, the optical axes of the imaging lenses are orthogonal to that of the light sources. The imaging apparatus is of two independent optical paths which capture the image of the printed circuit board and that of the screen respectively. Furthermore, the imaging apparatus is of compact structure, high acquiring speed and optical paths easy to be adjusted.