Image Forming Apparatus Fog Suppression via Voltage-Exposure Coordination
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Solution Overview
Problem
In image forming apparatuses using electrophotographic recording systems, the differing rising and falling characteristics of developing and charging high-voltage power sources make it difficult to maintain proper back contrast, leading to toner consumption due to fog generation during non-image formation processes.
Innovation Solution
An image forming apparatus with a controller that adjusts the exposure unit's exposure amount in conjunction with the changing developing voltage, ensuring the back contrast is maintained within a proper range by controlling the exposure of the image bearing member's surface during the transition from one developing voltage to another, even when the charging voltage and developing voltage have different characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the developing voltage is changed from a first developing voltage to a second developing voltage, then the back contrast can be adjusted to suppress fog, but the differing rising and falling characteristics of the developing and charging high-voltage power sources make it difficult to maintain proper back contrast during the transition period
Solution Approach 1:
The exposure amount is adjusted in advance before the developing voltage transition is complete. By predicting the voltage change trajectory and pre-adjusting the exposure amount, the system ensures that proper back contrast is maintained throughout the transition period, preventing fog generation during the critical changing phase of the developing voltage.
Solution Approach 2:
The control unit continuously monitors the developing voltage level and dynamically adjusts the exposure amount based on the current voltage state. This feedback mechanism ensures that the back contrast remains within the proper range throughout the voltage transition, compensating for the differing rising and falling characteristics of the power sources.
2Loss of substance
If the exposure amount is reduced to suppress fog during non-image formation, then toner consumption is reduced, but the back contrast may become insufficient during the voltage transition period
Solution Approach 1:
The exposure amount is made dynamic rather than fixed, adjusting continuously according to the developing voltage level. During the voltage transition period, the exposure amount is temporarily increased to maintain proper back contrast, then reduced to suppress fog during stable voltage operation, optimizing both image quality and toner efficiency.
Solution Approach 2:
The system changes the exposure amount parameter in response to developing voltage changes. By coordinating the exposure amount parameter with the developing voltage parameter, the system maintains proper back contrast during voltage transitions while minimizing exposure during stable operation to reduce fog and toner consumption.
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 fog generation and reduces toner consumption by maintaining optimal back contrast during both the rising and falling phases of the high-voltage power sources, thereby improving the efficiency of the image forming process.
Implementation Method 1
the charged surface of the photosensitive drum is exposed to light by an exposure unit to form an electrostatic latent image
Implementation Method 2
a surface of an electrophotographic photosensitive member (hereinafter, referred to as a photosensitive drum or a drum) is uniformly charged by a charging member
Implementation Method 3
the electrostatic latent image is developed by a developing unit to form a toner image by using developer (hereinafter, referred to as toner)
Implementation Method 4
the toner image is transferred onto a recording material by a transfer member
Implementation Method 5
by using a fixing device, the toner image is fixed onto the recording material and output as an image
Data Source
AI summary
During non-image formation, an exposure unit exposes an image formable region on the image bearing member surface charged by a charging member to light, and, in a state where toner is able to be supplied from a developing member to the image bearing member, during a period from when a developing voltage starts to be changed from a first developing voltage to a second developing voltage smaller than the first developing voltage until the developing voltage is completed to be changed to the second developing voltage. A controller controls the exposure unit so that, after the image bearing member surface exposed to light with a first exposure amount by the exposure unit passes through a development portion, the image bearing member surface exposed to light with a second exposure amount smaller than the first exposure amount by the exposure unit passes through the development portion.