Image Forming Apparatus Surface Potential Prediction
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Solution Overview
Problem
Conventional image forming apparatuses using electrophotography face challenges in maintaining uniform image density due to fluctuations in the surface potential of photosensitive members, particularly influenced by humidity and temperature, leading to variations in toner density and printing speed, which existing control methods fail to accurately predict and stabilize.
Innovation Solution
An image forming apparatus that predicts and controls the surface potential fluctuations of photosensitive members by calculating absolute humidity and rotation time, adjusting developing and charging biases to maintain constant development contrast, and switching process speeds based on print material types to stabilize image density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the number of revolutions of the photosensitive member before latent image formation is increased to stabilize image density, then image density uniformity is improved, but printing speed and productivity deteriorate
Solution Approach 1:
The patent applies preliminary action by performing charge elimination and charging steps before the actual image formation to stabilize the surface potential of the photosensitive member. This preliminary conditioning ensures uniform image density without requiring excessive revolutions during printing, thus maintaining productivity while improving image quality consistency.
2Manufacturing precision
If sensor installation is implemented to detect and control VL fluctuations, then image density stability is improved, but apparatus size and cost increase
Solution Approach 1:
The patent employs self-service by using the existing charging device and photosensitive member characteristics to predict and control surface potential fluctuations. Instead of adding external sensors, the system utilizes built-in components and environmental parameter monitoring to achieve VL stabilization, thereby avoiding increased apparatus size and cost while maintaining image density stability.
3Device complexity
If conventional control methods are used without considering absolute humidity, then device complexity is kept low, but prediction accuracy of VL fluctuations deteriorates
Solution Approach 1:
The patent applies parameter changes by incorporating absolute humidity as a critical environmental parameter into the prediction model. By monitoring and adjusting control parameters based on absolute humidity levels, the system achieves accurate prediction of VL fluctuations without significantly increasing device complexity, as the humidity data is integrated into existing control algorithms.
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 effectively stabilizes image density by accurately predicting and adjusting for surface potential fluctuations, improving printing speed and productivity while maintaining uniform image quality across varying humidity and temperature conditions.
Implementation Method 1
The surface potential at this stage is called a VD potential. The surface of the photosensitive member is then irradiated with laser light or LED light which is controlled to be turned on/off based on a signal from a controller (hereinafter referred to as an exposure step). A spot on the photosensitive member that is irradiated with light is reduced in electric potential, and thus an electrostatic latent image is formed on the surface of the photosensitive member.
Implementation Method 2
The charging device applies a bias to the photosensitive member to charge the surface of the photosensitive member to a given electric potential (hereinafter referred to as a charging step).
Implementation Method 3
Subsequently, a developing bias is applied to the developing device, which is placed to face the photosensitive member and which is filled with toner. This shifts the toner charged to a given level onto an electrostatic latent image on the photosensitive member, which is a photosensitive drum or the like, thereby turning the electrostatic latent image into a toner image
Implementation Method 4
Thereafter, a bias having a polarity opposite to that of the toner on the photosensitive member is applied to the transfer member, which is a transferring roller placed adjacent to the photosensitive member and moving in the forward direction at approximately the same speed as the photosensitive member. In this state, the transfer material passes between the photosensitive member and the transfer member, with the result that the toner on the photosensitive member is transferred to the transfer material
Data Source
AI summary
An image forming apparatus which predicts VL fluctuates of a photosensitive drum, taking a rotation speed of the photosensitive drum during image formation into consideration, and controls the image formation based on the prediction, for always obtaining an image of a stable density. The image forming apparatus performs appropriate image formation control by controlling image forming conditions based on a photosensitive member rotation time, a photosensitive member stop time, a temperature of the environment, an absolute humidity of the environment, and the rotation speed of the photosensitive member.