Cylindrical Substrate Coating Speed Control for Uniform Film
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Solution Overview
Problem
Conventional methods for applying a photosensitive layer to a cylindrical conductive support in electrophotographic photoreceptors face challenges such as non-uniform coating thickness, inefficiencies in coating liquid use, and defects like the 'liquid trailing phenomenon, leading to image defects and poor production efficiency.
Innovation Solution
A method and apparatus that control the circumferential speed ratio between the applicator roll and the cylindrical substrate during coating, with a ratio of 1.2 to 15.0, to prevent the liquid trailing phenomenon and achieve uniform coating thickness, while allowing for simple control and efficient use of coating liquid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If immersion coating is used to apply coating liquid to cylindrical substrate, then coating can be applied to the surface, but the film thickness becomes non-uniform due to gravity effect causing liquid trailing phenomenon
Solution Approach 1:
The patent applies dynamics by rotating the cylindrical substrate at a controlled speed during coating liquid application. This rotational motion creates centrifugal force that counteracts gravity, preventing the coating liquid from trailing downward and ensuring uniform film thickness distribution around the cylinder surface.
Solution Approach 2:
The patent changes the operational parameters by controlling the rotation speed of the cylindrical substrate within a specific range (5-50 m/min). This parameter control optimizes the balance between centrifugal force (preventing liquid trailing) and coating quality, achieving uniform film thickness without excessive liquid dispersion.
2Productivity
If lifting speed is increased to improve production efficiency, then coating process is faster, but film thickness uniformity deteriorates due to gravity effect
Solution Approach 1:
The patent resolves this contradiction by introducing rotational dynamics during the coating process. The cylindrical substrate rotates horizontally while being coated, creating centrifugal force that prevents liquid trailing regardless of the lifting speed. This allows high production efficiency to be maintained without sacrificing film thickness uniformity.
3Manufacturing precision
If coating liquid amount is increased to ensure sufficient coverage, then coating coverage is improved, but liquid trailing phenomenon worsens due to excess liquid
Solution Approach 1:
The patent uses rotational dynamics to manage coating liquid distribution. The rotation creates centrifugal force that evenly distributes the coating liquid across the substrate surface, allowing sufficient coverage with appropriate liquid amounts while preventing excess liquid from trailing downward due to gravity.
4Ease of operation
If circumferential speeds of applicator roll and cylindrical substrate are equal, then coating is simple to control, but liquid trailing phenomenon occurs at detachment
Solution Approach 1:
The patent applies dynamics by creating a controlled speed difference between the applicator roll and cylindrical substrate during detachment. The substrate rotates faster than the applicator roll, generating centrifugal force that prevents liquid trailing at the detachment point while maintaining simple overall control of the coating process.
Solution Approach 2:
The patent changes the speed parameter relationship by setting the cylindrical substrate rotation speed higher than the applicator roll speed during specific phases of the coating process. This parameter adjustment prevents liquid trailing at detachment while maintaining ease of operation through controlled parameter management.
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 the formation of a coating film with uniform thickness and no joints, improving the quality and efficiency of the electrophotographic photoreceptor production by preventing image defects and optimizing the use of coating liquid.
Implementation Method 1
a first circumferential speed detecting means for detecting a circumferential speed at which the cylindrical substrate is rotated; second circumferential speed detecting means for detecting a circumferential speed at which the applicator roll is rotated
Implementation Method 2
when detaching the applicator roll and the cylindrical substrate from each other, such control is carried out that a circumferential speed V1 of one of the applicator roll and the cylindrical substrate is higher than a circumferential speed V2 of the other
Data Source
AI summary
To suppress generation of a joint when detaching an applicator roll and cylindrical substrate from each other in a simple control to form a coating film having a uniform thickness efficiently on the cylindrical substrate is provided. A coating liquid is supplied from a pan to an applicator roll via a metalling roll, the applicator roll supplied with the coating liquid and a cylindrical substrate provided so as to be close to or in contact with the applicator roll are rotated. The coating liquid is transferred from the applicator roll to the cylindrical substrate, and the cylindrical substrate is rotated in a predetermined number. Thereafter, such control is carried out that the circumferential speed V1 of one of the applicator roll and the cylindrical substrate is higher than the circumferential speed V2 of the other when detaching the applicator roll and the cylindrical substrate from each other.