Transfer Device Using Superimposed AC DC Bias for Rough Media
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Solution Overview
Problem
Image forming apparatuses face issues with toner transfer onto recording media with rough surfaces, leading to leakage and image defects due to the use of oscillating electric fields, which increase power consumption and affect electronic devices.
Innovation Solution
An image forming apparatus with a transfer device that uses a superimposed bias of AC and DC voltages to create a transfer electric field, where the transfer speed is adjusted based on the intensity of the oscillating electric field to prevent leakage, and a separate DC power source is used for high smoothness media to ensure proper toner transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an oscillating electric field is applied to increase toner transferability onto rough surfaces, then transferability is improved, but leakage occurs and power consumption increases
Solution Approach 1:
The patent changes the parameters of the electric field by superimposing AC voltage on DC voltage, creating a composite electric field that combines the benefits of both oscillating and steady fields. This allows effective toner transfer onto rough surfaces while controlling leakage and power consumption through optimized voltage parameters
Solution Approach 2:
The patent uses a composite electric field structure combining AC and DC components. The AC component provides oscillating effect for rough surface penetration, while the DC component provides steady field for stable transfer, creating a synergistic effect that resolves the contradiction between transferability and power consumption
2Reliability
If an oscillating electric field is applied to improve toner transfer onto rough surfaces, then transferability is improved, but leakage occurs affecting electronic devices
Solution Approach 1:
By optimizing the AC voltage amplitude parameter to be within a specific range (0.5-2 times the DC voltage), the patent achieves effective toner transfer while keeping the electric field intensity below the leakage threshold, thus eliminating the harmful effect on electronic devices
Solution Approach 2:
The DC voltage component acts as an intermediary that stabilizes the electric field, preventing the oscillating AC component from causing excessive field intensity that would lead to leakage, while still allowing the AC component to provide the necessary oscillating effect for rough surface transfer
3Productivity
If transfer speed is increased to improve productivity, then output is improved, but toner transfer completeness deteriorates on rough surfaces
Solution Approach 1:
The patent applies periodic AC voltage to create oscillating electric field that repeatedly moves toner particles back and forth during the transfer process. This periodic action ensures complete toner transfer onto rough surfaces even at higher transfer speeds, as the oscillating field continuously replenishes toner supply to recessed areas
Solution Approach 2:
The patent makes the electric field dynamic by superimposing oscillating AC voltage on the DC voltage. This dynamic electric field adapts to the varying gap distances in rough surface topography, maintaining effective toner transfer across different transfer speeds and ensuring complete image formation
4Device complexity
If a single DC power source is used to simplify device structure, then device complexity is reduced, but transfer effectiveness on rough surfaces deteriorates
Solution Approach 1:
The patent merges AC and DC power sources into a unified superimposed bias system. The AC power source and DC power source are electrically connected in series, with their voltages superimposed to create a composite electric field that effectively transfers toner onto rough surfaces while maintaining reasonable device complexity
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 effectively prevents leakage and ensures reliable toner transfer onto various recording media surfaces, including those with high roughness, by adjusting transfer speed and using a separate DC power source for high smoothness media, thereby reducing power consumption and maintaining image quality.
Implementation Method 1
an oscillating electric field is applied to the transfer nip, thereby moving the toner back and forth in the transfer nip
Implementation Method 2
a transfer bias having a polarity opposite that of the toner is supplied to form a transfer electric field which enables toner to move from an image bearing member to the recording medium
Data Source
AI summary
An image forming apparatus includes a controller and a transfer device including a power source to output a superimposed bias in which an AC voltage is superimposed on a DC voltage, a first electrode, a second electrode disposed opposite the first electrode with an image bearing member interposed therebetween to form a transfer electric field to transfer a toner image on the image bearing member to a recording medium. The controller including a CPU adjusts the transfer electric field and a transfer speed. One of the first electrode and the second electrode is connected to the power source, and the other is grounded. The controller adjusts the transfer speed such that in a case in which an oscillating electric field of the transfer electric field is strong, a maximum transfer speed is slower than the maximum transfer speed in a case in which the oscillating electric field is weak.