Image Forming Apparatus Contact State Detection
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Solution Overview
Problem
In electrophotographic image forming apparatuses, accurately determining the contact state between an image bearing member and an intermediate transfer member is challenging due to variations in current flowing from primary transfer members, especially when a common transfer power source is used for multiple image forming units, leading to difficulties in detecting the contact state accurately.
Innovation Solution
An image forming apparatus with a detection unit to monitor currents in primary transfer members and a control unit to select between contact and separation modes based on detected currents, allowing for accurate determination of the contact state between the image bearing member and the intermediate transfer member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a common transfer power source is applied to multiple primary transfer members, then device complexity is reduced, but measurement precision of contact state deteriorates due to large current variation
Solution Approach 1:
The patent segments the detection function by introducing a separate detection circuit for each primary transfer member, while keeping the power supply unified. This allows individual current monitoring for each transfer member without requiring separate power sources, thus maintaining low device complexity while improving measurement precision through dedicated detection paths.
Solution Approach 2:
The patent introduces a detection circuit as an intermediary component between the common transfer power source and the primary transfer members. This intermediary enables precise measurement of current flowing through each transfer member by providing a dedicated detection path, while the common power source continues to supply voltage to all members simultaneously.
2Loss of substance
If image forming units are stopped when not used for monochrome images, then loss of substance is reduced, but reliability of contact state detection deteriorates due to large current variation
Solution Approach 1:
The patent performs preliminary detection of the contact state by monitoring current flow before making operational decisions. The detection circuit continuously monitors current through each primary transfer member, allowing the system to determine contact state in advance and make informed decisions about whether to activate image forming units, thereby ensuring reliable detection even when units are stopped.
Solution Approach 2:
The patent implements a feedback mechanism where the detection circuit continuously monitors current flow through primary transfer members and provides real-time information about contact state. This feedback allows the control system to adjust operations dynamically, maintaining reliable contact state detection by continuously monitoring electrical parameters rather than relying on mechanical position feedback.
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 enables precise control over the contact state, reducing wear and tear on unused image forming units and improving the accuracy of image transfer processes, thereby enhancing the operational efficiency and longevity of the apparatus.
Implementation Method 1
an image forming apparatus that forms an image by sequentially transferring toner images with a plurality of colors onto a transfer material using an electrophotographic system
Implementation Method 2
a detection unit configured to detect currents flowing in the first transfer member and the second transfer member, in a case where voltage is applied to the first transfer member and the second transfer member from the transfer power source
Data Source
AI summary
A controller can select and execute a full color mode of performing image formation in a first state in which each primary transfer member is in contact with an intermediate transfer belt, and a monochrome mode of performing image formation in a second state in which only a primary transfer member is in contact with the intermediate transfer belt. The controller determines which state of the first state and the second state is formed, based on a detection result obtained by a current detection circuit when a photosensitive drum is charged by a charging roller, and voltage is applied to the primary transfer member from a primary transfer power source.