Transfer Device Power Supply Control for Uneven Surfaces
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Solution Overview
Problem
Conventional electrophotography image forming apparatuses face challenges in transferring toner onto recessed portions of sheets with uneven surfaces, leading to unclear printing due to low transfer ratios and potential aerial discharge issues.
Innovation Solution
A transfer device incorporating a power supply control unit that manages both DC and AC voltages, selectively outputting a superimposed voltage with a short-pulse square wave to enhance toner transfer onto recessed areas, thereby improving image quality on uneven surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an AC voltage is superimposed on a DC voltage to increase toner transfer ratio onto recessed portions, then the transferability at recessed portions is improved, but the peak voltage becomes extremely high causing aerial discharge and voids at protruding portions
Solution Approach 1:
The patent applies periodic AC voltage superimposed on DC voltage to create oscillating electric fields that periodically move toner particles into recessed portions. The periodic nature of the AC component enables repeated oscillation cycles, allowing toner to be progressively transferred into difficult-to-reach areas without requiring excessively high peak voltages that would cause aerial discharge.
Solution Approach 2:
The superimposed AC voltage creates an oscillating electric field that mechanically vibrates or oscillates the toner particles on the sheet surface. This vibration effect helps toner particles move into recessed portions through the oscillating motion, improving transfer ratio without needing to increase the DC voltage to harmful levels.
2Productivity
If a DC voltage is applied to transfer toner onto a sheet, then the transfer process is simple and efficient, but recessed portions on uneven surfaces receive insufficient toner transfer
Solution Approach 1:
The patent merges DC voltage (for efficient overall transfer) with AC voltage (for enhanced recessed portion coverage) into a combined superimposed voltage waveform. The DC component maintains high transfer efficiency while the AC component adds the necessary oscillation to reach recessed areas, achieving both productivity and uniformity improvements simultaneously.
3Manufacturing precision
If the voltage is increased to improve toner transfer onto recessed portions, then the transfer ratio increases, but aerial discharge occurs generating voids at protruding portions
Solution Approach 1:
The patent changes the voltage parameter from a simple DC level to a time-varying superimposed waveform (DC + AC). This parameter transformation allows the system to achieve high transfer ratios through the oscillating AC component rather than by increasing the DC level, thereby preventing aerial discharge and maintaining image reliability while improving transfer precision.
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
The solution significantly increases the toner transfer ratio onto recessed portions, reducing image blurriness and preventing voids at protruding areas, resulting in improved image quality regardless of surface smoothness or environmental conditions.
Implementation Method 1
an AC voltage determined based on a second control signal is superimposed on a DC voltage output from the DC power supply
Implementation Method 2
electrophotography image forming apparatuses apply a direct-current (DC) voltage to an electrostatic toner pattern formed on an image carrier, thereby moving a developer, such as a toner, forming the electrostatic toner pattern to a sheet
Implementation Method 3
a toner reciprocates between a toner carrier and a sheet with the AC frequency. This increases the transferability at the recessed portions on the sheet surface
Data Source
AI summary
A transfer device includes a power supply control unit, a direct-current (DC) power supply, an alternating-current (AC) power supply, and a transfer unit. The power supply control unit controls a first control signal for controlling a DC voltage and a second control signal for controlling an AC voltage based on a condition relating to image formation. The DC power supply outputs the DC voltage based on the first control signal. The AC power supply selectively outputs, with a particular waveform, either of the DC voltage output from the DC power supply or a superimposed voltage obtained by superimposing the AC voltage determined based on the second control signal on the DC voltage output from the DC power supply. The transfer unit transfers a developer onto a sheet using a voltage output from the AC power supply.