Transfer Device Bias Control for Toner Transfer Reliability
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Solution Overview
Problem
The use of a secondary transfer bias including both DC and AC voltages in image forming apparatuses leads to the deterioration of transfer members, resulting in shortened lifespan and transfer failures, especially when dealing with recording sheets with surface irregularities like Japanese paper, due to inadequate toner transfer to concave portions.
Innovation Solution
A transfer device that applies a DC voltage with the same polarity as the secondary transfer bias and an AC voltage with a smaller amplitude, or only a DC voltage, when an inter-sheet area passes through the transfer nip during continuous image formation, to suppress member deterioration and ensure consistent toner transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a secondary transfer bias including both DC and AC voltages is applied, then toner transfer to surface concave portions is improved, but transfer member deterioration accelerates and lifespan is shortened
Solution Approach 1:
The patent applies AC voltage periodically during the transfer process to enable toner to reciprocate and reach surface concave portions, while using DC voltage as a baseline. This periodic action ensures complete toner transfer to irregular surfaces without continuously exposing transfer members to harsh AC voltage that would cause deterioration.
Solution Approach 2:
The patent optimizes the parameters of the secondary transfer bias by setting specific voltage values and ratios between AC and DC components. By carefully controlling these electrical parameters, the system achieves effective toner transfer while minimizing damage to transfer members, thus extending their lifespan.
2Duration of action of stationary object
If only DC voltage is applied as secondary transfer bias, then transfer member deterioration is suppressed, but toner transfer to surface concave portions is insufficient
Solution Approach 1:
The patent introduces AC voltage as a periodic component叠加 on the DC voltage. This periodic action creates an oscillating electric field that enables toner particles to move reciprocally, allowing them to reach into surface concave portions that would be inaccessible with a static DC field alone.
Solution Approach 2:
The patent uses a composite voltage system combining both AC and DC components. The DC voltage provides a stable baseline field for overall toner transfer, while the AC voltage component adds oscillatory motion to reach difficult-to-access areas, creating a synergistic effect that neither voltage type could achieve alone.
3Reliability
If AC voltage with large amplitude is continuously applied, then toner reciprocation is enhanced, but output responsiveness delay increases
Solution Approach 1:
The patent applies AC voltage in a periodic manner rather than continuously, synchronizing the AC cycles with the transfer process timing. This periodic application enhances toner reciprocation when needed while allowing brief intervals that reduce cumulative time delay and improve overall output responsiveness.
Solution Approach 2:
The patent applies AC voltage with optimized amplitude that is sufficient to achieve toner reciprocation but not excessively large. This partial action approach provides just enough oscillatory force to move toner into concave portions without creating excessive delay in the transfer process.
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 reduces the delay in output responsiveness of the DC voltage, prevents transfer failures, and extends the life of transfer members by minimizing the impact of AC voltage on the transfer process, while maintaining image quality and productivity.
Implementation Method 1
a secondary transfer electric field that allows the electrostatic movement of the toner image from the secondary transfer opposed roller side to the secondary transfer roller side is formed between the secondary transfer opposed roller and the secondary transfer roller
Data Source
AI summary
A transfer device includes a transfer member and a bias applicator. The transfer member contacts a surface, on which a toner image is borne, of an image bearing body, to form a transfer nip. The bias applicator applies a DC voltage and an AC voltage as transfer bias to transfer the toner image on the image bearing body to a recording sheet in the transfer nip. The bias applicator applies a DC voltage having a same polarity as the DC voltage of the transfer bias and an AC voltage having an amplitude smaller than the AC voltage of the transfer bias or applies the DC voltage having the same polarity as the DC voltage of the transfer bias without applying an AC voltage, when an inter-sheet area that exists on the image bearing body passes through the transfer nip during a continuous image formation period.