Contact Charging Image Forming Apparatus with AC Developing Bias
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Solution Overview
Problem
Image forming apparatuses using contact charging methods struggle to maintain high-quality image formation over long periods with positively charged single-layer electrophotographic photosensitive bodies, often experiencing charging non-uniformities and ozone generation.
Innovation Solution
An image forming apparatus employing a contact charging method with a charging device that includes a positively charged single-layer electrophotographic photosensitive body, a developing roller, and a voltage application unit with an AC developing bias frequency of 2.6 to 4.2 kHz, which suppresses ozone generation and ensures uniform charging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a contact charging method is used, then ozone generation is suppressed, but charging non-uniformities occur over time
Solution Approach 1:
The patent applies a specific frequency range (2.6 to 4.2 kHz) for the AC component of developing bias to optimize toner adhesion and image quality while maintaining stable charging conditions. This parameter optimization resolves the contradiction by finding the optimal operating point that maintains charging uniformity over extended periods.
2Productivity
If a positively charged single-layer electrophotographic photosensitive body is used, then image formation speed is improved, but the photosensitive layer becomes breakable
Solution Approach 1:
The patent optimizes the frequency parameter of AC developing bias within 2.6 to 4.2 kHz to enhance toner adhesion strength. This compensates for the reduced mechanical strength of single-layer photosensitive bodies by improving the electrostatic bonding force between toner and the photosensitive surface.
3Reliability
If image quality is maintained over long periods, then charging stability must be improved, but this increases device complexity
Solution Approach 1:
The patent specifies a precise frequency range (2.6 to 4.2 kHz) for AC developing bias to achieve stable image quality over extended periods. This parameter-based approach provides charging stability through optimized electrical conditions rather than complex mechanical or structural modifications.
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 solution enables the formation of high-quality images over extended periods while minimizing ozone generation and maintaining image reproducibility and density uniformity, even with a relatively breakable photosensitive layer.
Implementation Method 1
a voltage application unit which applies a developing bias to the developing roller, wherein the frequency of an AC component of the developing bias applied by the voltage application unit is 2.6 to 4.2 kHz
Implementation Method 2
a charging device which is based on a contact charging method for charging a circumferential surface of the image carrier while making contact with the circumferential surface of the image carrier
Implementation Method 3
an exposure device for forming an electrostatic latent image based on image data on the photosensitive drum
Implementation Method 4
a developing device for developing an electrostatic latent image on the photosensitive drum, into a toner image
Data Source
AI summary
An image forming apparatus, having: an image carrier configured by a positively charged single-layer electrophotographic photosensitive body; a charging device which is based on a contact charging method for charging a circumferential surface of the image carrier while making contact with the circumferential surface of the image carrier; a developing roller which is disposed so as to oppose the image carrier and carry and convey toner on the circumferential surface; and a voltage application unit which applies a developing bias to the developing roller, wherein the frequency of an AC component of the developing bias applied by the voltage application unit is 2.6 to 4.2 kHz.