Transfer Voltage Control in Image Forming Apparatus
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Solution Overview
Problem
Conventional image forming apparatuses experience electric discharges due to increased load from deteriorating transfer rollers, leading to faulty images, as they apply currents close to maximum values during estimation before paper feeding, resulting in excessively high voltages.
Innovation Solution
An image forming apparatus with a control unit that applies two different current values lower than those during paper feeding, estimates and controls the output voltage to stay within a limiter voltage range, preventing excessive voltage outputs during estimation and paper feeding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current values close to maximum are applied during estimation before paper feeding, then the current-voltage characteristic can be accurately estimated, but excessively high voltage is output causing electric discharge
Solution Approach 1:
The patent applies preliminary action by measuring the voltage at a low current value before paper feeding starts. This preliminary voltage measurement allows the control unit to calculate the current-voltage characteristic and determine an appropriate transfer current in advance, preventing electric discharge before it occurs during actual paper feeding.
Solution Approach 2:
The patent applies partial action by using a low current value (first current value) during the estimation phase instead of applying maximum current. This partial current application is sufficient to measure the voltage and calculate the characteristic, while avoiding the excessive voltage output that would cause electric discharge.
2Object-affected harmful factors
If low current values are applied during estimation before paper feeding, then electric discharge is prevented, but the current-voltage characteristic estimation becomes less accurate
Solution Approach 1:
The patent applies feedback by measuring the voltage at the low current value and using this feedback information to calculate the current-voltage characteristic. The control unit then uses this calculated characteristic to determine the appropriate transfer current for paper feeding, ensuring both accurate estimation and prevention of electric discharge.
Solution Approach 2:
The patent substitutes the mechanical approach of directly applying high current for estimation with an electrical calculation approach. By measuring voltage at low current and using Ohm's law to calculate the characteristic, the system achieves accurate estimation without the harmful effects of high current application.
3Duration of action of stationary object
If constant current is applied to transfer roller during non-paper feeding time, then the transfer roller can be maintained, but voltage may become excessively high due to deterioration over time
Solution Approach 1:
The patent applies dynamics by making the current application adaptive rather than constant. The control unit dynamically adjusts the current value based on real-time voltage measurements and calculated current-voltage characteristics, allowing the system to maintain the transfer roller while preventing voltage from becoming excessively high due to deterioration.
Solution Approach 2:
The patent uses feedback control where the control unit continuously monitors voltage, calculates the current-voltage characteristic, and adjusts the transfer current accordingly. This feedback mechanism maintains the transfer roller's performance while preventing voltage spikes caused by deterioration over time.
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 solution prevents electric discharges and faulty images by maintaining appropriate voltage levels, ensuring reliable operation over time without excessive voltage outputs during current application.
Implementation Method 1
applies currents having at least two different values during times in which paper is not being fed, the two current values being lower than a current value during paper feeding; estimates an output voltage on a basis of a voltage detected through the application of the currents
Data Source
AI summary
An image forming apparatus includes a transfer unit that transfers a toner image on an image bearer onto a transfer medium. The image forming apparatus includes a control unit that controls a transfer voltage to be output to the transfer unit in accordance with a certain condition. The control unit applies currents having at least two different values while paper is not being fed. The two current values are lower than a current value during paper feeding. The control unit estimates an output voltage on a basis of a voltage detected through the application of the currents. When the estimated output voltage falls below a certain limiter voltage, the control unit controls to bring the output voltage to a value calculated through the certain condition. When the estimated output voltage exceeds the certain limiter voltage, the control unit controls to bring the output voltage to the limiter voltage.