Image Forming Apparatus Surface Potential Detection
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Solution Overview
Problem
Conventional image forming apparatuses face challenges in accurately and efficiently detecting the light portion surface potential of image bearing members due to environmental and thickness variations, leading to insufficient correction and errors in image quality.
Innovation Solution
The apparatus includes a charging member, an exposure portion, a transfer member, a setting portion for discharge start voltages, and a calculating/correcting portion to determine and correct the light portion surface potential by calculating the correction amount based on positive and negative discharge start voltages, allowing for real-time adjustment and improved detection efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the charging roller is used to charge the photosensitive drum and detect its potential, then the detection can be performed, but it takes much time because the photosensitive drum must rotate one full turn to return to the charging roller position
Solution Approach 1:
The patent introduces a transfer roller as an intermediary component to perform the potential detection function. Instead of using the charging roller directly, the transfer roller charges the photosensitive drum in a non-image area and detects the potential through current measurement during the transfer process. This mediator approach allows detection without requiring the drum to complete a full rotation back to the original charging position, thereby reducing detection time while maintaining measurement capability.
2Loss of time
If the transfer roller is used to detect the photosensitive drum potential, then the detection time is reduced, but air bubbles and dust deposits on the transfer roller surface cause unevenness and detection errors
Solution Approach 1:
The patent applies preliminary cleaning actions to the transfer roller surface before potential detection. By pre-cleaning the transfer roller to remove air bubbles and dust deposits, the system ensures a smooth surface condition that prevents detection errors. This preliminary maintenance action maintains measurement precision while allowing the use of the transfer roller for rapid detection.
Solution Approach 2:
The system incorporates feedback mechanisms to monitor and detect potential issues with the transfer roller surface. By continuously monitoring detection results and identifying anomalies caused by surface unevenness, the system can trigger cleaning operations or adjust detection parameters to maintain accuracy despite the use of the transfer roller for time-efficient detection.
3Device complexity
If conventional control with estimated image bearing member potential is used, then the system is simple, but the contrast correction is insufficient due to environmental and thickness variations
Solution Approach 1:
The patent replaces the conventional estimation-based control system with an electrical measurement system. Instead of using mechanical or empirical estimation methods that vary with environment and thickness, the system uses electrical current measurement during the transfer process to directly determine the actual potential of the image bearing member. This substitution provides accurate, real-time data for precise contrast correction while maintaining manageable system complexity through integrated measurement.
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 reduces the time required for detecting the image bearing member's surface potential and ensures high-quality image formation, irrespective of environmental changes and image bearing member thickness variations.
Implementation Method 1
a charging member for electrically charging an image bearing member
Implementation Method 2
an exposure portion for exposing the image bearing member to light in order to form a latent image on a surface of the image bearing member
Implementation Method 3
a transfer member for transferring a toner image from the image bearing member onto a sheet
Implementation Method 4
a setting portion for setting a positive-side discharge start voltage when a positive-side voltage relative to a reference potential is applied to the transfer member after a voltage is applied to the charging member so that a surface of the image bearing member is charged to the reference potential
Data Source
AI summary
An image forming apparatus includes: a charging member; a transfer member; a setting portion for setting a positive-side discharge start voltage when a positive-side voltage relative to a reference potential is applied to the transfer member after a voltage is applied to the charging member so that a surface of the image bearing member is charged to the reference potential by the charging member and for setting a negative-side discharge start voltage when a negative-side voltage relative to the reference potential is applied to the transfer member after the voltage is applied; a calculating portion for calculating a correction amount for correcting a light portion surface potential, of the image bearing member, calculated by the calculating portion on the basis of the positive-side and negative-side discharge start voltages; and a correcting portion for correcting the light portion surface potential by using the correction amount.