Developing Roller Voltage Control for Image Density Uniformity
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Solution Overview
Problem
In image forming apparatuses, variations in the distance between the developing roller and the image carrier cause uneven toner supply, leading to density issues in printed images, as the direct current voltage correction is delayed due to stabilization requirements of alternating current voltage, and can result in mistaken air discharge sensing during electric discharge measurement.
Innovation Solution
An image forming apparatus with a developing roller, a voltage applying part, a direct current correcting part, and a correction switching part, where the direct current voltage is corrected based on alternating current variations and switched between operating and non-operating states to maintain a constant electric field and prevent delays in toner supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If direct current voltage correction is applied based on alternating current variation, then uneven density caused by distance variation is suppressed, but direct current voltage rise is delayed due to stabilization requirements
Solution Approach 1:
The system performs preliminary stabilization of the alternating current voltage before applying direct current voltage correction. This ensures that the alternating current is fully stabilized and any transient effects have subsided, allowing the subsequent direct current correction to proceed without delay or instability, thus resolving the contradiction between precision and time loss.
2Quantity of substance
If alternating current voltage is heightened to optimize toner supply, then toner supply amount is improved, but mistaken air discharge sensing occurs
Solution Approach 1:
The system introduces a current detection circuit as an intermediary to monitor the actual current flowing between the developing roller and image carrier. This intermediary measurement allows the system to distinguish between increased current due to optimized toner supply and current due to actual air discharge, preventing mistaken detection while maintaining optimal toner supply through heightened alternating current voltage.
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 solution ensures consistent toner supply and prevents delays in direct current voltage rise, maintaining image quality by stabilizing the electric field and avoiding mistaken air discharge sensing, thus preventing toner thinning and ensuring uniform image density.
Implementation Method 1
a high voltage obtained by superimposing an alternating current voltage and a direct current voltage on each other
Implementation Method 2
an electric field between the image carrier and the developing roller
Implementation Method 3
if the close distance between the image carrier and the developing roller is varied, an electric field between the image carrier and the developing roller is varied, and thereby, a toner supply amount is varied
Implementation Method 4
The correction switching part switches the direct current voltage correcting part between an operating state and a non-operating state
Data Source
AI summary
An image forming apparatus includes a developing roller, a voltage applying part, a direct current correcting part and a correction switching part. The developing roller supplies a toner to an image carrier. The voltage applying part applies a superimposed voltage of an alternating current voltage and a direct current voltage to the developing roller. The direct current correcting part corrects the direct current voltage on the basis of variation of an alternating current flowing between the voltage applying part and the developing roller. The correction switching part switches the direct current voltage correcting part between an operating state and a non-operating state.