Nozzle Coating Pattern-Width Control Using Camera Feedback
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Solution Overview
Problem
Existing methods for controlling the pattern-width of coating liquid dispensed from a nozzle on printed circuit boards are inefficient, leading to measurement errors, excessive liquid consumption, and inaccuracies in nozzle height adjustment, which degrade coating quality and increase production time and costs.
Innovation Solution
A method and apparatus utilizing a camera to measure and adjust the pattern-width of the coating liquid by calculating image data from the nozzle and coating liquid, allowing precise control of dispensing pressure and nozzle height, enabling real-time adjustment to maintain the pattern-width within a reference error range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical fiber sensor or laser sensor is used to measure coating liquid pattern, then measurement can be performed, but measurement precision is poor with error of approximately 3 mm
Solution Approach 1:
The patent replaces the mechanical/optical sensor-based measurement system (optical fiber sensor or laser sensor) with a vision-based measurement system using a camera and image processing. This substitution eliminates the inherent measurement errors (approximately 3 mm) associated with sensor characteristics and provides higher measurement precision for coating liquid pattern width.
Solution Approach 2:
The patent creates a visual copy (image) of the coating liquid pattern using a camera, then processes this image data to determine pattern width. This copying approach allows for precise measurement without physical contact or interference from sensor characteristics, achieving better measurement precision than direct sensor measurement.
2Measurement precision
If coating liquid is dispensed continuously for long time for measurement, then pattern ends can be distinguished by sensor, but time consumption and liquid consumption increase
Solution Approach 1:
The patent uses periodic dispensing of coating liquid (dispensing for a predetermined time, then stopping for measurement) rather than continuous dispensing. This periodic action allows the coating liquid to form a stable, measurable pattern without requiring prolonged dispensing, significantly reducing both time consumption and liquid consumption while maintaining measurement accuracy.
Solution Approach 2:
The patent performs measurement during the dispensing process itself (real-time measurement) rather than after complete dispensing. By capturing images during the dispensing operation and processing the images to determine pattern width, the system achieves measurement without requiring additional time for separate measurement sessions, reducing total time consumption.
3Ease of repair
If nozzle is separated from robot for maintenance, then maintenance can be performed, but mechanical clearance occurs causing coordinate error
Solution Approach 1:
The patent implements a feedback mechanism using vision measurement to detect and compensate for coordinate errors of the nozzle. By continuously measuring the actual position and pattern width, the system can identify deviations caused by mechanical clearance and adjust subsequent dispensing operations to maintain precision, thereby compensating for maintenance-induced errors.
Solution Approach 2:
The vision measurement system automatically detects and provides data for correcting nozzle coordinate errors without requiring manual intervention or complex recalibration procedures. The system self-monitors its own performance and generates correction information, making the precision maintenance process simpler and more accessible.
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 significantly reduces the time and amount of coating liquid required, improves measurement accuracy from mm to μm precision, enhancing coating quality and production efficiency while minimizing waste.
Implementation Method 1
photographing the dispensed coating liquid with the camera
Data Source
AI summary
Disclosed is a method for controlling the pattern-width of a coating liquid dispensed from a nozzle. The method includes the steps of: dispensing the coating liquid downward from the nozzle in a dispensing position on a measurement reference line to photograph with a camera positioned at a predetermined horizontal distance from the measurement reference line arranged perpendicularly to a coating reference surface; calculating the pattern-width of the coating liquid on the coating reference surface from image data obtained by photographing the coating liquid dispensed from the nozzle in the dispensing position with the camera; comparing the calculated pattern-width of the coating liquid with a coating liquid reference pattern-width; and adjusting dispensing pressure by increasing or decreasing pressure of air supplied to a pressure container that provides the coating liquid to the nozzle when the calculated pattern-width of the coating liquid is outside the reference allowed error.