Image Forming Apparatus Density Correction via Transfer Resistance
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Solution Overview
Problem
The density of images formed on a sheet in an electrographic image forming apparatus can deviate from the target value due to variations in the conductivity of the path through which the secondary transfer current flows, despite density correction control, as the existing methods do not accurately account for the effects of secondary transfer resistance changes over time.
Innovation Solution
The apparatus includes a control unit that forms a test image on an intermediate transfer member, measures its density, corrects the measured density based on the evaluation of the secondary transfer resistance, and generates a gradation correction table to adjust image forming conditions, using an evaluation value such as accumulated power supply time to account for resistance changes, thereby ensuring the image density on the sheet matches the target density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If density correction control is performed by measuring test image density on the intermediate transfer member, then the density of the test image can be corrected to match the target value, but the density of the image formed on the sheet may still deviate from the target value due to variations in secondary transfer resistance
Solution Approach 1:
The control unit continuously monitors the density of test images formed on the intermediate transfer member and uses this feedback information to adjust image forming conditions. By comparing the measured density with the target density and making real-time corrections, the system compensates for variations in secondary transfer resistance and maintains consistent image density on sheets.
Solution Approach 2:
The system changes image forming parameters such as transfer voltage, development charge, or exposure amount based on the measured density deviations. When density variations are detected, the control unit adjusts these parameters to compensate for the effects of secondary transfer resistance changes, ensuring the final image density on sheets remains within the target range.
2Adaptability or versatility
If the secondary transfer current flows through a path with varying conductivity, then the transfer process can adapt to different usage conditions, but the density of the transferred image changes from the density in the intermediate transfer member
Solution Approach 1:
The system uses density measurement feedback to detect changes in secondary transfer characteristics caused by varying conductivity. By continuously monitoring test image density and adjusting image forming parameters accordingly, the system adapts to different usage conditions while maintaining consistent image density on sheets despite changes in transfer path conductivity.
Solution Approach 2:
The control unit performs preliminary density measurements on test images before actual sheet production. By measuring and evaluating test image density in advance, the system can predict and compensate for potential density deviations that may occur during secondary transfer, allowing for preemptive parameter adjustments to maintain density consistency.
3Measurement precision
If a test image is formed on the intermediate transfer member and its density is measured, then density correction data can be generated, but the measured density does not fully account for the effects of secondary transfer resistance variations
Solution Approach 1:
The control unit uses the measured test image density as feedback information to infer changes in secondary transfer resistance. By analyzing density deviations and their relationship with usage conditions, the system recovers information about secondary transfer resistance variations and uses this information to adjust image forming parameters, preventing density loss during the transfer process.
Solution Approach 2:
Instead of directly measuring secondary transfer resistance through complex electrical measurements, the system substitutes this difficult-to-measure electrical parameter with an optical measurement approach. By measuring the optical density of test images and using this information to infer transfer characteristics, the system simplifies the measurement process while still capturing the essential information needed for density correction.
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 effectively maintains image density on the sheet at the target value by accounting for secondary transfer resistance variations, preventing deviations caused by changes in conductivity, thus improving image quality and consistency.
Implementation Method 1
a transfer member configured to output a transfer voltage, in order to cause a transfer current to flow so as to transfer the image formed on the intermediate transfer member to a sheet
Implementation Method 2
a first measurement unit configured to measure a density of the image formed on the intermediate transfer member
Data Source
AI summary
An image forming apparatus includes an image forming unit configured to form an image on an intermediate transfer member; a transfer member configured to output a transfer voltage in order to cause a transfer current to flow so as to transfer the image to a sheet; a measurement unit configured to measure a density of the image; and a control unit configured to control the image forming unit to form a test image on the intermediate transfer member based on test image data, control the measurement unit to acquire a measured density of the test image, correct the measured density based on an evaluation value of an electric resistance of a path through which the transfer current flows, and generate data for density correction based on the test image data and a corrected measured density.