Toner Density Adjustment Using Cleaner Image
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Solution Overview
Problem
In electrophotographic image forming apparatuses, the non-uniform distribution of external additives on the intermediate transfer member due to the separation and adherence of titanium oxide during toner development affects the accuracy of toner density measurement and adjustment, leading to degraded image quality.
Innovation Solution
An image forming apparatus that forms a cleaner toner image covering the entire area where the test pattern is formed, which is then removed along with the external additive, ensuring uniformity and allowing for accurate toner density measurement and adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a test pattern is formed on the intermediate transfer member for density measurement, then toner density can be measured and adjusted, but external additive adheres to the surface causing incorrect measurement
Solution Approach 1:
The patent applies preliminary action by forming a cleaner toner image on the intermediate transfer member before forming the test pattern. This cleaner toner image serves as a preparatory layer that removes external additives from the surface, ensuring that when the test pattern is subsequently formed and measured, the surface conditions are uniform and accurate measurements can be obtained without interference from adhered external additives.
2Productivity
If cleaning member contacts the intermediate transfer member to remove toner, then residual toner is removed, but external additive adheres non-uniformly to the surface
Solution Approach 1:
The patent converts the harmful effect of external additive adhesion into a beneficial process. By intentionally forming a cleaner toner image that covers the entire surface and then removing it, the process utilizes the cleaner toner image as a vehicle to carry away non-uniformly distributed external additives. The removal of this cleaner toner image simultaneously removes the external additives, restoring surface uniformity for subsequent test pattern formation.
3Productivity
If multiple toner images are transferred before density adjustment, then printing productivity is maintained, but external additive distribution becomes increasingly non-uniform
Solution Approach 1:
The patent implements periodic action by inserting a density adjustment cycle between printing operations. After a certain number of toner images are transferred during normal printing, the system periodically performs density adjustment by forming and removing a cleaner toner image. This periodic intervention restores the uniformity of external additive distribution on the intermediate transfer member surface, allowing printing productivity to be maintained over extended periods without degradation in measurement accuracy.
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 ensures correct toner density measurement and adjustment, maintaining uniform external additive distribution, thereby improving image quality by maintaining consistent toner density across the intermediate transfer member.
Implementation Method 1
a sensor that detects measurement light from a test pattern on a surface of the image carrier for density adjustment
Implementation Method 2
an external additive such as titanium oxide is attached to the toner. Due to a developing bias and a primary transfer bias applied when a toner image is developed, the external additive separates and flies from the toner, and adheres on the surface of the intermediate transfer member
Data Source
AI summary
In an image forming apparatus, a density adjustment unit causes to form a cleaner toner image on a surface of an image carrier and remove the cleaner toner image for density adjustment, and causes to form a test pattern after removing the cleaner toner image. The cleaner toner image is formed to cover a whole area on which the test pattern may be formed.