Developer Transport Speed Control for Image Density Uniformity
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Solution Overview
Problem
Image forming apparatuses face issues with uneven developer distribution, leading to defects such as blur or low density in printed images due to excessive pressure from the upstream developer-transporting unit, particularly affecting the center portion of the image.
Innovation Solution
The apparatus includes a speed controller that increases the rotation speed of the upstream developer-transporting unit if the center density of a reference developed image is lower than the edge density, detected by a density detecting unit, to reduce excessive pressure and improve image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the upstream developer-transporting unit applies excessive pressure to transport developer, then developer transport efficiency is improved, but image quality deteriorates due to blur and low density in the center portion
Solution Approach 1:
The patent applies dynamics by making the rotation speed of the upstream developer-transporting unit variable rather than fixed. The speed is dynamically adjusted based on detected image density: when center density is lower than edge density, the rotation speed is increased to reduce excessive pressure and improve developer distribution uniformity, thereby resolving the contradiction between transport efficiency and image quality
Solution Approach 2:
The patent changes the operational parameter (rotation speed) of the upstream developer-transporting unit to resolve the contradiction. By adjusting the rotation speed parameter in response to density detection results, the system optimizes both developer transport efficiency and image quality, preventing blur and low density defects while maintaining adequate transport performance
2Quantity of substance
If the upstream developer-transporting unit rotates at high speed, then developer supply to the development area is improved, but uneven developer distribution occurs causing center density to decrease
Solution Approach 1:
The patent implements feedback control by using a density detecting unit to monitor the developed image density and feeding this information back to the speed controller. The controller adjusts the upstream developer-transporting unit's rotation speed based on the feedback: when center density is detected to be lower than edge density, the speed is increased to improve developer distribution uniformity and ensure adequate center density
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 adjustment in rotation speed decreases pressure on the developer, reducing image defects like blur and low density areas, ensuring more consistent and high-quality image formation across the image area.
Implementation Method 1
a subjected-to-development member that rotates and has a surface on which an electrostatic latent image is formed
Implementation Method 2
a first developer-transporting unit carrying the developer on a circumferential surface thereof and transporting the developer toward the subjected-to-development member while rotating
Implementation Method 3
a regulator that regulates the thickness of a layer of the developer carried by the circumferential surface of the first developer-transporting unit
Implementation Method 4
a density detecting unit that detects center density and edge density of a developed image formed on the subjected-to-development member
Data Source
AI summary
An image forming apparatus includes a subjected-to-development member; a first developer-transporting unit; a regulator that regulates the thickness of a developer; a second developer-transporting unit; a density detecting unit that detects center density and edge density of a developed image formed on the subjected-to-development member by the first developer-transporting unit and the second developer-transporting unit; a reference-image forming controller that forms a reference developed image on the subjected-to-development member by forming an electrostatic latent image having a uniform image density at a center position and an edge position; and a speed controller that increases rotation speed of the second developer-transporting unit as compared to the case of forming the reference developed image if the center density of the reference developed image detected by the density detecting unit is lower than the edge density.