Electrophotographic Photoreceptor Undercoat for Thick-Paper Fogging Control
Solution Overview
Problem
Image forming apparatuses using electrophotographic photoreceptors face issues with fogging on thick paper due to low heat conduction, requiring longer fixation times and decreased charge retention, leading to increased rotation speed adjustments and prolonged charging to development times.
Innovation Solution
The apparatus incorporates an electrophotographic photoreceptor with a conductive substrate, an undercoat layer containing a binder resin and electron transport material, and a photosensitive layer, ensuring a moving time from charging to development of 90 msec or longer, and adhering to specific Fermi level and LUMO energy level relationships to suppress energy barrier accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the rotation speed of the electrophotographic photoreceptor is decreased to allow longer fixation time for thick paper, then image fixation quality is improved, but charge retention power is decreased leading to fogging
Solution Approach 1:
The invention changes the energy level parameters of the undercoat layer by selecting electron transport materials with specific LUMO energy levels (3.0 eV or higher) and adjusting the Fermi level through material selection. This parameter optimization ensures that the energy difference between the undercoat layer and charge generation layer remains within 0.1-0.5 eV, maintaining charge retention even at lower rotation speeds required for thick paper fixation
Solution Approach 2:
The invention uses composite material structure with an undercoat layer containing binder resin and electron transport material (such as zinc oxide, tin oxide, or titanium oxide particles) combined with specific organic compounds. This composite structure optimizes both the thermal properties for fixation and the electrical properties for charge retention, resolving the contradiction between fixation time and charge retention
2Loss of time
If the moving time from charging to development is extended to 90 msec or longer for thick paper, then fixation completeness is improved, but charge retention decreases causing toner adhesion to non-image areas
Solution Approach 1:
The invention optimizes the energy level parameters of the undercoat layer, specifically setting the LUMO energy level to 3.0 eV or higher and controlling the Fermi level to maintain an energy difference of 0.1-0.5 eV with the charge generation layer. This parameter optimization allows the system to tolerate longer moving times (90 msec or longer) without significant charge loss, enabling complete fixation on thick paper while preventing fogging
Solution Approach 2:
The undercoat layer acts as an intermediary between the conductive support and the photosensitive layer, mediating charge transfer. By selecting electron transport materials with appropriate energy levels in the undercoat layer, the invention creates an optimized charge transfer pathway that maintains charge retention over extended periods, allowing longer moving times without fogging
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 configuration effectively suppresses fogging on thick paper by maintaining charge retention and reducing energy barrier accumulation, even at lower rotation speeds, thereby improving image quality.
Implementation Method 1
an undercoat layer provided on the conductive substrate, containing a binder resin and an electron transport material
Implementation Method 2
electrophotographic photoreceptor including a conductive substrate, an undercoat layer provided on the conductive substrate
Data Source
Figure 1~2
Figure 3
AI summary
An image forming apparatus includes an electrophotographic photoreceptor that includes a conductive substrate, an undercoat layer provided on the conductive substrate, containing a binder resin and an electron transport material, and satisfying Expression 1-1, and a photosensitive layer provided on the undercoat layer, a charging device that charges a surface of the electrophotographic photoreceptor, an electrostatic latent image forming device that forms an electrostatic latent image on the charged surface of the electrophotographic photoreceptor, a developing device that develops the electrostatic latent image formed on the surface of the electrophotographic photoreceptor with a developer containing a toner to form a toner image, and a transfer device that transfers the toner image to a surface of a recording medium, in which a moving time of an outer peripheral surface of the electrophotographic photoreceptor, required from charging performed by the charging device to development performed by the developing device, is 90 msec or longer, 0.20≤EF1−ELUMO1≤0.60 (in Expression 1-1, EF1 represents a Fermi level of the undercoat layer, and ELUMO1 represents an energy level of LUMO of the undercoat layer).