Power Supply Unit for Image Forming Apparatus
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Solution Overview
Problem
Existing image forming apparatuses face issues with toner splashing and image quality degradation due to fluctuations in humidity, as the characteristic curves used for power supply control are determined at low humidity conditions, leading to excessive power supply at high humidity.
Innovation Solution
An image forming apparatus with a power supply unit that adjusts power based on detected current and voltage values, using a characteristic line that shifts from an increasing to a decreasing tendency with increasing electrical characteristic values, and an ascertainment unit to determine the optimum control target value based on the type of recording medium, thereby stabilizing power supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If power supply is increased to ensure sufficient toner adhesion, then toner transfer completeness improves, but toner splashing and image carrier damage occur
Solution Approach 1:
The patent applies dynamic control of power supply to the transfer unit by continuously monitoring electrical resistance values and adjusting the power supply accordingly. The control unit varies the power supply level based on real-time resistance measurements, enabling the system to adapt to changing environmental conditions (temperature and humidity) and prevent both insufficient transfer and excessive power that causes splashing.
Solution Approach 2:
The system implements feedback control by measuring the electrical resistance value of the transfer unit system, comparing it with reference values stored in the storage unit, and adjusting the power supply based on the comparison result. This closed-loop feedback mechanism ensures that the power supply is optimized for current environmental conditions, preventing toner splashing while maintaining complete transfer.
2Object-generated harmful factors
If power supply is decreased to prevent toner splashing, then toner transfer control improves, but toner adhesion becomes insufficient and toner remains on image carrier
Solution Approach 1:
The system dynamically adjusts power supply levels based on real-time electrical resistance measurements. When resistance values indicate dry environmental conditions (lower resistance), the system increases power supply to ensure complete toner transfer. When resistance values indicate humid conditions (higher resistance), the system decreases power supply to prevent splashing, thus adapting to environmental changes.
Solution Approach 2:
The control unit continuously monitors electrical resistance and uses feedback from this measurement to adjust power supply. The feedback mechanism compares actual resistance values with reference values stored in memory, and automatically adjusts power supply to maintain optimal transfer conditions, preventing both incomplete transfer and splashing.
3Ease of operation
If characteristic curve is determined at low humidity conditions, then control simplicity is maintained, but power supply becomes excessive at high humidity causing image quality degradation
Solution Approach 1:
Instead of using a fixed characteristic curve determined at low humidity, the system dynamically determines the appropriate power supply level by measuring real-time electrical resistance values. The control unit adjusts power supply based on the measured resistance and corresponding environmental conditions (temperature and humidity), ensuring optimal image quality across varying humidity levels while maintaining control simplicity through automated adaptation.
Solution Approach 2:
The system changes the operating parameters (power supply level) based on measured electrical resistance values that reflect environmental conditions. By storing multiple reference resistance values and their corresponding optimal power supply levels in the storage unit, the system can select and apply the appropriate parameter set for current conditions, maintaining image quality without complex manual adjustment.
4Adaptability or versatility
If electrical resistance measurement is used to control power supply, then adaptability to environmental changes improves, but measurement precision requirements increase
Solution Approach 1:
The system stores multiple reference electrical resistance values and their corresponding optimal power supply levels in the storage unit before operation. These pre-stored reference values cover a range of environmental conditions, allowing the control unit to select the most appropriate reference value for current conditions without requiring extremely precise real-time measurements. This cushioning approach provides a buffer against measurement uncertainties.
Solution Approach 2:
The system dynamically selects from multiple pre-stored reference resistance values based on the range in which the measured resistance falls. Rather than requiring precise matching to a single reference value, the system adapts by selecting the most appropriate reference from a set, providing environmental adaptability while reducing the stringency of measurement precision requirements through dynamic selection from predefined options.
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
Prevents image quality degradation caused by humidity changes by optimizing power supply control, ensuring stable toner transfer and reducing the risk of toner splashing across varying humidity levels.
Implementation Method 1
great fluctuations arise in electrical resistance values of a transfer unit, an image carrier, and a recording sheet to be nipped between the transfer unit and the image carrier depending on an ambient environment (particularly a temperature and a humidity)
Implementation Method 2
a voltage detection unit for detecting a voltage value for the transfer unit
Implementation Method 3
a current detection unit for detecting a value of a current flowing to the transfer unit
Implementation Method 4
a characteristic line showing a relationship between an electric characteristic value based on both detection values or a detection value of the voltage detection unit and an optimum value of the control target
Data Source
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AI summary
An image forming apparatus has a transfer unit, a power supply unit that takes a value of a current imparted to the transfer unit as a control target and that supplies power conforming to the value of the control target to the transfer unit; and a determination unit that acquires a detection value of a voltage detection unit and a detection value of a current detection unit and that determines, as a control target value for the power supply unit, an optimum value for the control target derived from a characteristic line showing a relationship between an electric characteristic value based on both detection values or a detection value of the voltage detection unit and an optimum value of the control target. The characteristic line is a line showing a relationship of a change in the absolute value of the optimum value for the control target shifting from an increasing tendency (Z2) to a decreasing tendency (Z1) with an increase in absolute vale of the electric characteristic value based on both detection values or the detection value of the voltage detection unit.