Toner Charge-Based Transfer Voltage Control in Tandem Printers
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Solution Overview
Problem
In tandem-type image forming apparatuses, using a common voltage power source for transfer biases across multiple image forming portions leads to inconsistent transfer contrast, resulting in image defects such as voids and scattering, which compromise both transfer efficiency and image quality.
Innovation Solution
An image forming apparatus with a controller that adjusts the transfer voltage and potential for each photosensitive member based on the stored information about the toner charge amount, ensuring optimal transfer contrast across all image forming portions, even when a common transfer bias is applied.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a common transfer bias is applied to all image forming portions, then device complexity is reduced and cost is lowered, but transfer contrast becomes insufficient for colors with low charge amounts, causing image defects
Solution Approach 1:
The patent changes the electrical potential parameter of the photosensitive member surface dynamically based on toner charge amount. When toner charge amount decreases, the controller adjusts the potential of the image portion to maintain adequate transfer contrast, resolving the contradiction between using a common transfer bias and maintaining reliable transfer efficiency.
2Reliability
If transfer bias is increased to maintain transfer contrast for all colors, then transfer efficiency is maintained, but transfer scattering increases and image quality deteriorates
Solution Approach 1:
The patent applies local quality by adjusting the potential specifically at the image portion of the photosensitive member where toner is present, rather than uniformly increasing transfer bias across all colors. This localized adjustment maintains transfer efficiency only where needed while preventing transfer scattering in other areas, thus preserving image quality.
3Manufacturing precision
If transfer bias is decreased to improve transfer scattering, then image quality improves, but transfer contrast becomes insufficient for some colors, causing image defects
Solution Approach 1:
The patent introduces dynamics by making the photosensitive member potential adjustable rather than fixed. The controller dynamically changes the potential based on detected toner charge amounts, allowing the system to adapt transfer contrast to actual conditions while maintaining a generally lower transfer bias to reduce transfer scattering and improve image quality.
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 image defects and improves transfer scattering while maintaining high transfer efficiency, ensuring consistent image quality across all colors without the need for individual bias settings for each color.
Implementation Method 1
an electrostatic latent image is formed on a photosensitive member by electrostatically charging a surface of the photosensitive member by a charging means
Implementation Method 2
exposing the charged surface of the photosensitive member to light by an exposure means
Implementation Method 3
the electrostatic latent image is developed with toner as a developer by a developing means
Implementation Method 4
a predetermined primary transfer bias is applied, so that the toner image is primary-transferred onto the intermediary transfer member
Data Source
AI summary
An image forming apparatus includes a first image forming portion including a first photosensitive member, a first charging member, and a first developing member including a first accommodating portion; a second image forming portion including a second photosensitive member, a second charging member, and a second developing member including a second accommodating portion; an exposure portion; an applying portion; a storing portion; and a controller. When, in the storing portion, information on toner accommodated in the first accommodating portion is changed from first information to second to information and information on toner accommodated in the second accommodating portion is not changed, the controller carries out control so that a transfer voltage is changed from a first transfer voltage to a second transfer voltage and so that a potential of an image portion formed on the second photosensitive member is changed from a first potential to a second potential.