Transfer Voltage Control for White Void Prevention
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Solution Overview
Problem
Conventional image forming apparatuses using electrophotographic processes often experience 'white void' defects due to excessive secondary transfer voltage, which is difficult to distinguish and adjust, especially when dealing with varying recording materials, leading to inefficient image transfer.
Innovation Solution
An image forming apparatus that adjusts the secondary transfer voltage by outputting a chart with test images and detecting their density, using a controller to set the optimal voltage based on sensor readings with and without the recording material, thereby preventing excessive voltage application.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the secondary transfer voltage is increased to improve image transfer efficiency, then the image transfer efficiency is improved, but white void defects occur due to excessive voltage
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the secondary transfer voltage based on detected current values. The system changes the voltage parameter from a fixed high value to a dynamically optimized value that prevents white void defects while maintaining transfer efficiency. The controller adjusts the voltage based on the relationship between current and voltage, finding the optimal operating point.
Solution Approach 2:
The patent implements feedback control by detecting the current value during secondary transfer and using this information to adjust the secondary transfer voltage. The sensor provides real-time feedback on the electrical conditions, and the controller uses this feedback to prevent excessive voltage application that would cause white void defects.
2Ease of operation
If the preset recording material part voltage is used for all recording materials, then the device operation is simplified, but the transfer voltage may be higher or lower than appropriate for specific materials
Solution Approach 1:
The patent applies self-service by enabling the system to automatically determine the appropriate secondary transfer voltage without requiring manual intervention or complex user input. The sensor detects current values, and the controller automatically calculates and adjusts the optimal voltage based on the detected parameters, making the system adapt to different recording materials autonomously.
Solution Approach 2:
The patent implements dynamics by transitioning from a static preset voltage system to a dynamic voltage adjustment system. The secondary transfer voltage is no longer fixed but changes dynamically based on real-time detection of current values and the specific recording material being used, optimizing performance for each material type.
3Extent of automation
If patch density detection is used to select secondary transfer voltage, then voltage adjustment is automated, but the absolute value of voltage becomes excessively large causing white void defects
Solution Approach 1:
The patent applies mechanics substitution by replacing the conventional patch density detection method with an electrical parameter detection method. Instead of relying on optical density measurements that lead to excessively high voltage values, the system uses current value detection combined with voltage-current relationship analysis to determine optimal voltage, substituting one measurement approach for a more accurate electrical approach.
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 allows for precise adjustment of the secondary transfer voltage, reducing the occurrence of 'white void' defects and improving image transfer efficiency by accounting for the specific properties of the recording material.
Implementation Method 1
a transfer member configured to transfer the toner image from the image bearing member onto a recording material at a transfer portion under application of a voltage
Implementation Method 2
a sensor configured to detect a current value or a voltage value when the voltage is applied from the voltage source to the transfer member
Data Source
AI summary
An image forming apparatus includes an image bearing member, a transfer member, a voltage source, a sensor configured to detect a current value or a voltage value, an image detecting portion, and a controller capable of executing an operation in a mode for setting a transfer voltage to be applied to the transfer member, on the basis of a result of detection of a test chart formed on a test recording material. The controller sets the transfer voltage on the basis of a first detection result acquired by the sensor under application of a voltage to the transfer member when the recording material is absent in the transfer portion and a second detection result acquired by the sensor under application of the test voltages to the transfer member when the test recording material is present in said transfer portion during the operation in the mode.