Substrate Coating Device Optical Bead Shape Control
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Solution Overview
Problem
Conventional substrate coating devices cannot accurately control the amount of coating liquid on a substrate surface due to indirect estimation of bead shape, leading to non-uniform film thickness areas, especially at the start and end of coating processes.
Innovation Solution
A substrate coating device with a nozzle, shape measuring means for optical measurement of the bead shape, shape altering means to adjust the bead shape, and control means to prepare data for precise operation of the shape altering means, allowing direct measurement and control of the coating process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If indirect estimation of bead shape is used based on pump pressure and substrate vibration measurement, then device complexity is reduced, but measurement precision and manufacturing precision deteriorate
Solution Approach 1:
The patent replaces indirect mechanical estimation methods (pressure sensors, vibration sensors) with direct optical measurement using imaging devices. The imaging device captures images of the bead shape formed between the nozzle and substrate, providing direct visual measurement of the coating liquid's morphology without requiring mechanical sensors or complex estimation algorithms.
Solution Approach 2:
The patent introduces an imaging device as an intermediary between the coating process and measurement system. This intermediary directly observes and records the bead shape formation process, enabling precise measurement of coating quality parameters while maintaining simplicity in the overall device architecture.
2Device complexity
If indirect estimation of bead shape is used, then device complexity is reduced, but manufacturing precision of coating thickness deteriorates
Solution Approach 1:
The patent implements a feedback control system where the imaging device continuously monitors the bead shape during coating, and the control unit adjusts coating parameters based on the measured bead shape data. This real-time feedback enables precise control of coating thickness and uniformity, directly addressing the manufacturing precision issue.
Solution Approach 2:
The patent replaces indirect mechanical estimation with direct optical measurement of bead shape, enabling more accurate control of coating thickness. By visually measuring the actual bead morphology, the system can make precise adjustments to achieve uniform coating, improving manufacturing precision without significantly increasing device complexity.
3Measurement precision
If optical measurement of bead shape is implemented, then measurement precision and manufacturing precision are improved, but device complexity increases
Solution Approach 1:
The imaging device serves multiple functions: it measures bead shape, monitors coating quality, and provides data for control adjustments. This multi-functionality reduces the need for separate measurement and control components, thereby limiting the increase in device complexity while achieving high measurement precision.
4Manufacturing precision
If optical measurement and direct control of bead shape is implemented, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent implements feedback control where the imaging device measures bead shape and the control unit adjusts coating parameters accordingly. This feedback mechanism enables precise control of coating amount and uniformity, directly improving manufacturing precision while using a relatively simple control architecture.
Solution Approach 2:
The control unit performs multiple functions: it processes images from the imaging device, calculates optimal coating parameters, and controls the coating process. This multi-functionality consolidates control capabilities into a single unit, improving manufacturing precision without proportionally increasing device complexity.
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
Enables immediate and accurate control of the coating amount on the substrate surface, reducing non-uniform areas at the start and end of the coating process by directly measuring and adjusting the bead shape.
Implementation Method 1
The shape measuring means is configured to optically measure a bead shape of the coating liquid delivered from the nozzle on the substrate
Data Source
AI summary
The substrate coating device (10) includes a slit nozzle (1), a first camera (3), a second camera (4), a control section (5), a pump (8), and a pressure control chamber (9). The control section (5) controls the supply of the coating liquid from the pump (8) to the slit nozzle (1) in accordance with the result of comparison between a bead shape imaged by the first camera (3) and a reference shape. The control section (5) also controls the air pressure on the upstream side of the slit nozzle (1) by the pressure control chamber (9) in accordance with the result of comparison between a distance measured from an image taken by the second camera (4) and a reference distance.