Image Forming Apparatus Transfer Voltage Adjustment for Edge Defects
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Solution Overview
Problem
Conventional image forming apparatuses using electrophotographic processes face issues with image defects at the end portions of recording materials due to varying moisture levels and electrical resistance, leading to abnormal discharge during image transfer, even after adjusting the transfer voltage using diagnostic charts with patches only in the central portion.
Innovation Solution
An image forming apparatus that outputs a chart with test toner images of different transfer voltages, including halftone images, specifically formed within 50 mm from the edge in the width direction perpendicular to the feeding direction of the recording material, allowing for precise adjustment of the transfer voltage to prevent image defects at the end portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the transfer voltage is adjusted using a chart with patches only in the central portion of the recording material, then the adjustment process is simple and the chart is easy to produce, but image defects occur at the end portion of the recording material
Solution Approach 1:
The patent applies local quality by placing test patches specifically at the end portion of the recording material where image defects occur. This localized testing approach allows the adjustment chart to focus on the problematic area rather than uniformly distributing patches across the entire material, thereby maintaining ease of manufacture while improving reliability at the critical end portion.
Solution Approach 2:
The patent implements preliminary action by including test patches at the end portion of the recording material before actual image formation. This allows the transfer voltage to be adjusted in advance based on observations from the end portion patches, preventing image defects before they occur in practical operation.
2Reliability
If the transfer voltage is increased to compensate for high electrical resistance at the end portion, then image transfer improves, but abnormal discharge occurs causing image defects
Solution Approach 1:
The patent applies feedback by using the test patches at the end portion to observe image formation quality and transfer characteristics. Based on these observations, the transfer voltage is adjusted to an appropriate level that ensures proper image transfer without causing abnormal discharge, creating a closed-loop adjustment process.
Solution Approach 2:
The patent implements parameter changes by adjusting the transfer voltage to an optimal value based on observations from the end portion test patches. This voltage adjustment compensates for the high electrical resistance at the end portion without exceeding the threshold that would cause abnormal discharge, thereby resolving the contradiction between transfer quality and discharge prevention.
3Ease of operation
If test patches are placed only in the central portion of the recording material, then the adjustment process is straightforward, but the adjustment does not account for moisture variation at the end portion
Solution Approach 1:
The patent applies local quality by specifically placing test patches at the end portion of the recording material where moisture variation occurs. This localized approach allows the adjustment process to directly observe and account for the specific conditions at the end portion, improving measurement precision without significantly complicating the overall adjustment process.
Solution Approach 2:
The patent implements preliminary action by forming test images at the end portion before actual image formation. This allows the operator to observe the effects of moisture variation and electrical resistance at the end portion in advance, and adjust the transfer voltage accordingly, ensuring proper image quality throughout the recording material.
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 adjusts the transfer voltage to prevent image defects at the end portions of recording materials, ensuring high-quality image formation even with materials prone to defects, and is compatible with various sizes of recording materials with a simplified control structure.
Implementation Method 1
The transfer of a toner image from an image bearing member to a recording material is often performed by applying a transfer voltage to a transfer member such as a transfer roller which contacts the image bearing member to form a transfer portion
Implementation Method 2
application device configured to apply a transfer voltage for the image transfer to said image transfer device
Data Source
AI summary
An image forming apparatus includes an image bearing member, an image transfer device for transferring a toner image from the image bearing member to a sheet, an application device for applying a transfer voltage to the image transfer device, and a controller for controlling an output mode operation for outputting a predetermined chart in which test halftone toner images transferred with different transfer voltages are formed to adjust the transfer voltage. When outputting a maximum size of the chart, the controller forms the test toner images in a region within 50 mm from an edge in a width direction perpendicular to a feeding direction of the sheet.