Transfer Voltage Duty Ratio Control for Embossed Paper
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Solution Overview
Problem
Image forming apparatuses struggle to transfer toner images efficiently onto the recessed portions of embossed paper, resulting in low image quality due to uncontrollable toner scattering and uneven image density.
Innovation Solution
The apparatus controls the transfer voltage by varying the duty ratio of the AC voltage applied to the secondary transfer roller, optimizing it based on the paper type, image pattern, humidity, and image mode to ensure efficient toner transfer onto embossed paper surfaces without blurring or blotting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a combination of DC and AC voltages is applied to the transfer roller to transfer toner onto recessed portions of embossed paper, then transfer efficiency to recessed areas is improved, but toner particles reciprocally move and scatter uncontrollably causing blotted images
Solution Approach 1:
The patent applies AC voltage with a specific duty ratio (50% or less) to create periodic electric field variations that enable toner to enter recessed portions during the on-period while limiting excessive reciprocation during the off-period. This periodic voltage application resolves the contradiction by controlling the timing and duration of electric field activation.
Solution Approach 2:
The patent changes the duty ratio parameter of the AC voltage to 50% or less, transforming the voltage waveform characteristics to achieve optimal balance between transfer efficiency and image quality. This parameter adjustment allows the electric field to be strong enough to pull toner into recesses but controlled enough to prevent uncontrolled scattering.
2Manufacturing precision
If the AC voltage amplitude is reduced to minimize toner scattering, then image quality is improved, but transfer efficiency to recessed portions deteriorates
Solution Approach 1:
By using periodic AC voltage with controlled duty ratio instead of continuous DC voltage, the system achieves higher peak electric field strength during the on-period to ensure toner enters recessed portions, while the off-period allows toner to settle. This periodic action resolves the contradiction between voltage amplitude and transfer efficiency.
Solution Approach 2:
The patent dynamically switches the voltage between on and off states with controlled duty ratio, creating time-varying electric field conditions that adapt to the transfer process requirements. This dynamic voltage control enables both sufficient transfer force and controlled toner settlement.
3Productivity
If only DC voltage is applied to the transfer roller, then toner transfer to flat surfaces is efficient, but recessed portions of embossed paper receive insufficient toner transfer
Solution Approach 1:
The patent superimposes AC voltage on DC voltage to create periodic electric field variations that actively pull toner into recessed portions during the AC on-period, while the DC component maintains overall transfer direction. This periodic modulation resolves the contradiction by adding targeted enhancement for recessed areas without sacrificing overall efficiency.
Solution Approach 2:
The patent uses a composite voltage waveform combining DC and AC components, where DC provides stable baseline transfer and AC provides dynamic enhancement for recessed areas. This composite voltage approach achieves both overall efficiency and uniform distribution across different surface topographies.
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 significantly improves transfer efficiency and image quality by minimizing unintended toner scattering and ensuring consistent image density across embossed paper surfaces, even on recessed areas.
Implementation Method 1
the application of the AC voltage in addition to the DC voltage can generate an electric field capable of causing toner particles to be ejected from the image bearing member
Implementation Method 2
The application of the AC voltage in addition to the DC voltage caused toner particles to reciprocally move between the image bearing member and recording medium
Data Source
AI summary
An image forming apparatus includes a rotatable image bearing member for bearing a toner image; a transfer member constituting a transfer portion for transferring the toner image formed on the image bearing member onto a recording material; a voltage source for applying, to the transfer member, a voltage in the form of superimposed DC voltage and AC voltage; a controller for controlling the voltage source such that a duty ratio of the AC voltage is changed in accordance with a kind of the recording material; and an executing portion for executing an operation in an image forming mode in which the toner image is transferred from the image bearing member onto the recording material with the duty ratio controlled by the controller.