Electrophotographic Photoreceptor Layers for Uniform Charging
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Solution Overview
Problem
Existing electrophotographic photoreceptors suffer from abrasion resistance issues and charging unevenness, particularly when the charge transport layer thickness varies along the axial direction due to the viscosity of polyarylate resin and gravitational effects during coating.
Innovation Solution
The photoreceptor design includes a charge generation layer with thickness variations at the ends to counteract gravitational effects, ensuring uniformity of the charge transport layer thickness by adjusting the pull-up speed, blade pressure, or spray amount during coating, and using a polyarylate resin with specific molecular weight and concentration to enhance abrasion resistance and prevent charging unevenness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the charge transport layer is coated using conventional methods with polyarylate resin, then the coating process is simple, but the layer thickness becomes uneven due to viscosity and gravitational effects
Solution Approach 1:
The charge generation layer is designed with non-uniform thickness distribution, where the thickness varies along the axial direction of the photoreceptor. Specifically, the thickness is greater at the ends and smaller at the center, which compensates for the gravitational settling of polyarylate resin during coating. This local variation in thickness achieves uniform charge transport layer thickness while maintaining simple coating processes.
Solution Approach 2:
The non-uniform thickness design of the charge generation layer is performed in advance to counteract the gravitational effects that will occur during the subsequent coating of the charge transport layer. By pre-positioning the thickness variation, the patent prevents the harmful effect of uneven coating before it occurs, ensuring uniform final layer thickness.
2Ease of manufacture
If the charge transport layer thickness varies along the axial direction, then the coating process is easier, but abrasion resistance deteriorates
Solution Approach 1:
The charge generation layer has locally varied thickness to compensate for gravitational effects during coating, ensuring that the charge transport layer achieves uniform thickness. This uniform thickness of the charge transport layer maintains consistent abrasion resistance across the entire photoreceptor surface, preventing weak points that would reduce overall reliability.
3Ease of manufacture
If the charge transport layer thickness varies along the axial direction, then the coating process is simpler, but charging unevenness increases
Solution Approach 1:
The charge generation layer is designed with non-uniform thickness distribution along the axial direction, with greater thickness at the ends and smaller thickness at the center. This local variation compensates for the gravitational settling of polyarylate resin during coating, ensuring that the charge transport layer achieves uniform thickness and thereby preventing charging unevenness.
Solution Approach 2:
The non-uniform thickness design of the charge generation layer is implemented in advance to counteract the gravitational effects during subsequent coating operations. This preliminary compensation prevents charging unevenness before it occurs, maintaining high manufacturing precision in the final product.
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
The design achieves improved abrasion resistance and reduces charging unevenness by maintaining uniform layer thickness, extending the photoreceptor's lifespan and enhancing image quality.
Implementation Method 1
a charge generation layer, and a charge transport layer formed on the charge generation layer
Implementation Method 2
due to the viscosity of polyarylate resin and gravitational effects during coating
Data Source
Figure 1~2
Figure 3
AI summary
An electrophotographic photoreceptor includes a conductive substrate; and a photosensitive layer disposed on the conductive substrate and including a charge generation layer and a charge transport layer, in which the charge transport layer has an average thickness of 30 µm or greater, the charge transport layer contains a polyarylate resin, and an absorption spectrum measured by peeling off the photosensitive layer and dissolving the photosensitive layer in tetrahydrofuran satisfies Expression (1) and Expression (2), Iu≤0.95×Im 1.05×Im≤Il in a case where a total length of the electrophotographic photoreceptor in an axial direction is defined as L, Im represents an absorbance of the photosensitive layer at a wavelength of 678 nm, which is peeled from a center of the electrophotographic photoreceptor in the axial direction, Iu represents an absorbance of the photosensitive layer at a wavelength of 678 nm, which is peeled at a position of 0.40 L from the center of the electrophotographic photoreceptor in the axial direction toward one end, and Il represents an absorbance of the photosensitive layer at a wavelength of 678 nm, which is peeled at a position of 0.40 L from the center of the electrophotographic photoreceptor in the axial direction toward the other end.