Slit Nozzle Transparent Walls for Liquid Surface Detection
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Solution Overview
Problem
The existing spin coating method is inefficient in using coating liquid, as most of it is scattered outside the substrate, and there is a need for improved detection of the liquid surface within the slit nozzle to maintain uniform film thickness in the slit coating method.
Innovation Solution
A coating apparatus with a slit nozzle, a moving mechanism, a storage portion illumination unit, and an imaging unit, where the slit nozzle has transparent walls for illuminating and imaging the liquid surface, allowing for accurate detection of the liquid surface level and flattening determination using reference portions and adjustable brightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If spin coating method is used to coat coating liquid on substrate, then coating liquid can be applied on substrate, but most of the coating liquid is scattered outside the substrate resulting in poor use efficiency
Solution Approach 1:
The invention extracts and eliminates the harmful scattering effect by using a slit nozzle to control the coating liquid flow path. The slit-shaped ejecting port confines the coating liquid to a narrow stream that follows the substrate surface, preventing lateral scattering and ensuring the liquid remains within the substrate boundaries throughout the coating process.
Solution Approach 2:
The invention changes the geometric parameters of the ejecting port from a conventional circular or wide opening to a narrow slit shape. This parameter change in the nozzle geometry transforms the coating liquid discharge pattern from a wide spray to a concentrated linear stream, dramatically improving coating liquid utilization efficiency while maintaining coating quality.
2Loss of substance
If slit nozzle is used to apply coating liquid by scanning, then coating liquid use efficiency is improved, but accurate detection of liquid surface level is difficult without transparent walls
Solution Approach 1:
The invention applies the principle of optical property changes by making the nozzle walls transparent. This allows light to pass through the nozzle body, enabling optical sensors to detect the liquid surface level, meniscus position, and flow characteristics within the nozzle. The transparency transforms the nozzle from an opaque structure to an optically accessible channel for precise measurement.
Solution Approach 2:
The transparent nozzle walls act as an intermediary that allows optical signals to penetrate into the liquid flow region. This intermediary structure enables non-contact measurement of liquid parameters while maintaining the functional integrity of the nozzle, bridging the gap between the liquid flow control system and the detection system.
3Strength
If opaque nozzle walls are used, then structural integrity is maintained, but liquid surface and flow characteristics cannot be observed for quality control
Solution Approach 1:
The invention changes the optical property of the nozzle material from opaque to transparent, allowing visual and optical detection of liquid flow characteristics. This material property change enables real-time monitoring of liquid surface level, flow uniformity, and potential anomalies without compromising the nozzle's mechanical function.
Solution Approach 2:
The transparent nozzle structure serves multiple functions simultaneously: it maintains the structural integrity and coating liquid delivery function of the nozzle, while also acting as an optical window for detection and monitoring. This multi-functionality eliminates the need for separate transparent observation windows or additional sensing structures.
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 proper detection of the liquid surface within the slit nozzle, ensuring uniform head pressure and consistent film thickness during the coating process, reducing waste and improving coating efficiency.
Implementation Method 1
a storage portion illumination unit configured to illuminate an inside of the storage portion through the transparent member of the first wall
Implementation Method 2
an imaging unit configured to image the inside of the storage portion through the transparent member of the second wall
Implementation Method 3
a slit-shaped ejecting port configured to eject the coating liquid fed from the storage portion through a slit-shaped flow path
Implementation Method 4
The coating liquid slightly exposed from the ejecting port of the slit nozzle comes in contact with the substrate
Data Source
AI summary
Disclosed is a coating apparatus configured to properly detect a liquid surface of a coating liquid stored within a slit nozzle. The disclosed coating apparatus includes a slit nozzle, a moving mechanism, a storage portion illumination unit, and an imaging unit. The slit nozzle includes an elongated main body, a storage portion configured to store a coating liquid within the main body, and a slit-shaped ejecting port configured to eject the coating liquid fed from the storage portion through a slit-shaped flow path, wherein at least a part of each of a first wall and a second wall which face each other in the main body is formed of a transparent member. The moving mechanism is configured to move the slit nozzle with respect to a substrate. The storage portion illumination unit is configured to illuminate an inside of the storage portion through the transparent member of the first wall. The imaging unit is configured to image the inside of the storage portion through the transparent member of the second wall.