Sheet Conveyance Apparatus Paper Dust Removal Mechanism
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Solution Overview
Problem
Existing sheet conveyance systems in electrophotographic printers fail to effectively prevent paper dust from flowing back into the conveyance path, especially when the paper dust has small particle sizes, leading to image defects due to adherence on the photosensitive drum or toner.
Innovation Solution
A sheet conveyance apparatus with a rotary member, a counter member forming a conveyance nip, a first contact member (sponge) for scraping paper dust, and a second contact member (backflow preventing member) with a contacting and separating mechanism that ensures the second member abuts and separates from the rotary member based on rotation direction, preventing paper dust from entering the conveyance path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a gap is provided between the first paper dust removing roller and the first reverse conveyance preventing member, then scraping of paper dust by the first sponge member is not inhibited when the roller rotates in forward direction, but small particle size paper dust can pass through the gap and adhere to the photosensitive drum or toner
Solution Approach 1:
The second paper dust removing roller is configured to rotate in opposite directions depending on the operation mode (forward rotation during normal conveyance, reverse rotation during paper end detection). The contact pressure between the roller and paper dust removing member is dynamically adjusted based on rotation direction, ensuring effective paper dust removal in both directions while preventing small particles from passing through gaps.
Solution Approach 2:
The contact pressure parameter between the paper dust removing member and the roller surface is changed based on the rotation direction. During forward rotation, the member contacts the roller surface to allow scraping; during reverse rotation, increased contact pressure prevents paper dust from entering the conveyance path, thereby eliminating image defects caused by small particles.
2Reliability
If the first reverse conveyance preventing member is positioned to scrape paper dust from the roller, then paper dust conveyance is restricted when roller rotates in reverse direction, but the member may inhibit scraping operation when roller rotates in forward direction
Solution Approach 1:
The system dynamically changes the operational state of the paper dust removing member based on roller rotation direction. During forward rotation, the member is positioned to scrape paper dust effectively; during reverse rotation, the member is activated to abut against the roller surface, preventing paper dust from entering the conveyance path. This dynamic adjustment ensures both scraping effectiveness and paper dust restriction without mutual interference.
3Reliability
If the second contact member continuously contacts the rotary member, then paper dust is effectively prevented from entering conveyance path during reverse rotation, but scraping efficiency is reduced during forward rotation
Solution Approach 1:
The contact state of the second paper dust removing member with the rotary member is dynamically controlled based on rotation direction. During forward rotation, the member maintains a slight gap or reduced contact to allow efficient scraping by the first sponge member. During reverse rotation, the member is actuated to firmly contact the roller surface, creating a barrier that prevents paper dust from entering the conveyance path, thereby optimizing both scraping efficiency and paper dust prevention at different operational phases.
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
Effectively prevents paper dust from entering the conveyance path, even for small particles, thereby reducing image defects and maintaining image quality by ensuring the backflow preventing member contacts the rotary member without gaps, ensuring reliable removal of paper dust during both forward and reverse rotations.
Implementation Method 1
the conveyance portion being configured to convey a sheet at the conveyance nip by the rotary member rotating in a first direction
Implementation Method 2
a first contact member configured to come into contact with a surface of the rotary member at a first position
Implementation Method 3
a contacting and separating mechanism configured to abut the second contact member against the surface of the rotary member and separate the second contact member from the surface of the rotary member
Data Source
AI summary
A sheet conveyance apparatus includes a conveyance portion including a rotary member, and a counter member, a first contact member, a second contact member, and a contacting and separating mechanism. The contacting and separating mechanism causes the second contact member to separate from the surface of a rotary member of a conveyance portion when the rotary member rotates in the first direction, and causes the second contact member to abut against the surface of the rotary member when the rotary member rotates in a second direction opposite to the first direction.