Two-Component Development Voltage Tuning to Suppress Carrier Development
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Solution Overview
Problem
Image forming apparatuses using amorphous silicon photosensitive members face issues with carrier movement from the development device to the photosensitive drum, leading to carrier development, which affects image quality.
Innovation Solution
The apparatus employs a two-component development system with specific voltage and gap settings, including a direct-current voltage (Vdc) and alternating-current voltage (Vac), where the peak-to-peak value of Vac is controlled relative to the gap between the image carrying member and developer carrying member, adhering to specific formulae to minimize carrier development.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a two-component development system is employed in an image forming apparatus with high process linear velocity, then productivity is improved, but carrier development occurs leading to image quality degradation
Solution Approach 1:
The patent applies parameter changes by optimizing the alternating-current voltage amplitude and frequency in the development voltage to suppress carrier development. Specifically, the amplitude is set to 0.5 to 2.0 kV and frequency to 1 to 10 kHz, which creates an electrostatic field that prevents carrier adhesion to the photosensitive drum while maintaining high-speed operation
Solution Approach 2:
The patent employs periodic action by using alternating-current voltage with specific frequency (1 to 10 kHz) in the development voltage. This periodic voltage creates a dynamic electrostatic field that periodically repels carriers from the photosensitive drum surface, preventing carrier development while allowing high-speed image formation
2Reliability
If amorphous silicon photosensitive member is used due to its high dielectric constant, then image formation capability is improved, but carrier adhesion to photosensitive drum increases causing carrier development
Solution Approach 1:
The patent introduces an intermediary mechanism by applying alternating-current voltage to the development roller, which creates an electrostatic field that acts as a mediator between the two-component developer and the photosensitive drum. This electrostatic field prevents direct adhesion of carriers to the high-dielectric amorphous silicon surface while allowing toner attachment
3Manufacturing precision
If development voltage is increased to improve toner attachment, then image density is improved, but carrier development is exacerbated
Solution Approach 1:
The patent segments the development voltage into two distinct components: a direct-current voltage component (Vdc) for toner attachment and an alternating-current voltage component (Vac) for carrier suppression. The DC component provides the necessary electric field for toner adhesion, while the AC component with amplitude 0.5 to 2.0 kV and frequency 1 to 10 kHz prevents carrier adhesion, allowing both functions to operate independently and optimally
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 effectively suppresses carrier development and associated image defects, ensuring high-quality image formation by maintaining optimal electrostatic conditions.
Implementation Method 1
The charging device electrostatically charges the surface of the image carrying member
Implementation Method 2
The exposure device exposes the surface of the image carrying member electrostatically charged by the charging device to light to form an electrostatic latent image with reduced electrostatic charge
Implementation Method 3
The development voltage power supply applies to the developer carrying member a development voltage resulting from superposing an alternating-current voltage Vac on a direct-current voltage Vdc
Data Source
AI summary
An image forming apparatus includes an image carrying member, a charging device, an exposure device, a development device, and a development voltage power supply. The image carrying member has an amorphous silicon photosensitive layer formed on its surface. The development device includes a developer carrying member carrying two-component developer containing toner and carrier. The development voltage power supply applies to the developer carrying member a development voltage having an alternating-current voltage superposed on a direct-current voltage. When the blank part potential on the image carrying member is V0 [V], the direct-current voltage is Vdc [V], the peak-to-peak value of the alternating-current voltage Vac is Vpp [kV], and the gap between the image carrying member and the developer carrying member is Ds [mm], 10≤V0−Vdc≤90 and 1.2≤Vpp/Ds≤3.5 are fulfilled.