Developing Bias Control for Humidity-Driven Toner Fog
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Solution Overview
Problem
Image forming apparatuses experience toner fog and density unevenness, particularly in low humidity environments, due to increased peak-to-peak voltage of the developing bias, which exacerbates potential differences and toner adherence issues.
Innovation Solution
The apparatus adjusts the peak-to-peak voltage and duty ratio of the developing bias in response to humidity changes, maintaining a constant potential difference Vgo and controlling the duty ratio to suppress toner fog and density unevenness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the peak-to-peak voltage of AC voltage components of the developing bias is increased to reduce sub-scanning density unevenness in low humidity environments, then density evenness is improved, but toner fog occurs due to increased potential difference
Solution Approach 1:
The patent applies dynamics by making the developing bias parameters dynamic rather than fixed. The control section adjusts the peak-to-peak voltage and duty ratio of the AC voltage components based on detected humidity levels. In low humidity environments, the system increases peak-to-peak voltage to reduce density unevenness while simultaneously adjusting the duty ratio to control the potential difference and prevent toner fog. This dynamic adaptation allows the system to optimize image quality for different environmental conditions.
Solution Approach 2:
The patent employs parameter changes by modifying multiple parameters of the developing bias simultaneously. When humidity decreases, the system increases the peak-to-peak voltage to combat density unevenness while adjusting the duty ratio to maintain appropriate potential difference. This coordinated parameter adjustment resolves the contradiction between improving density evenness and preventing toner fog by balancing two critical parameters rather than changing only one.
2Object-generated harmful factors
If the duty ratio of AC voltage components is adjusted to control potential difference and prevent toner fog, then toner fog is suppressed, but density unevenness may worsen if peak-to-peak voltage is not simultaneously adjusted
Solution Approach 1:
The patent applies merging by combining the control of two developing bias parameters (peak-to-peak voltage and duty ratio) into a unified control mechanism. The control section simultaneously adjusts both parameters based on humidity detection, ensuring that the duty ratio adjustment for toner fog suppression works in coordination with peak-to-peak voltage adjustment for density evenness. This combined approach ensures that neither parameter undermines the other's effectiveness.
Solution Approach 2:
The patent uses parameter changes by coordinating adjustments of multiple parameters. When the duty ratio is modified to control potential difference and prevent toner fog, the system simultaneously adjusts the peak-to-peak voltage to maintain density evenness. This coordinated parameter change strategy ensures that suppressing toner fog does not come at the expense of density uniformity.
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
Simultaneously reduces toner fog and density unevenness across varying humidity levels by dynamically adjusting the developing bias parameters, ensuring consistent image quality.
Implementation Method 1
a humidity sensor that detects humidity
Implementation Method 2
a developing bias applying portion that applies a developing bias to the developer bearing member to develop the electrostatic latent image formed on the image bearing member by the latent image forming portion using the developer borne by the developer bearing member, the developing bias including a direct current voltage and an alternating current voltage that are superimposed on each other
Data Source
AI summary
An image forming apparatus includes a developing bias applying portion that applies a developing bias including a direct current voltage and an alternating current voltage to a developer bearing member that bears toner. When a voltage on the same-polarity side of a charging polarity of the toner with respect to the direct current voltage out of the alternating current voltage is referred to as Vgo, the developing bias applying portion applies the developing bias to the developer bearing member so that as compared to a peak-to-peak voltage in a case where humidity is a first humidity, the peak-to-peak voltage in a case where humidity is a second humidity that is lower than the first humidity is greater, and so that the voltage Vgo in the case where humidity is the second humidity is the same as the voltage Vgo in the case where humidity is the first humidity.