Discharge Device Sheet Curling Control via Dual-Surface Pressing
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Solution Overview
Problem
In electro-photographic image-forming apparatuses, sheets often curl during the fixing process due to heat, leading to uneven toner distribution and image quality issues.
Innovation Solution
A discharge device comprising a transport unit, a contact member that presses the sheet from one side, a guide member that guides the sheet without contact, and a discharge unit, which together manage the sheet's curl by applying tensional forces to counteract heat-induced curling, ensuring proper discharge and image formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If heat is applied to fix toner on the sheet, then toner fixation is achieved, but the sheet curls due to thermal expansion
Solution Approach 1:
The guide member is positioned to contact the first surface of the sheet before or during the fixing process, providing a counteracting force that prevents curling from occurring in the first place. This preliminary anti-action counterbalances the thermal expansion forces that would otherwise cause the sheet to curl during heating.
Solution Approach 2:
The guide member acts as an intermediary element between the heating unit and the discharge unit, mediating the sheet's behavior during the fixing process. By contacting the first surface while the contact member presses the second surface, the guide member serves as a mediator that distributes and balances the forces acting on the sheet, preventing uneven thermal expansion and curling.
2Ease of operation
If the contact member presses the sheet firmly, then sheet control is improved, but the guide member may come into contact with the contact member
Solution Approach 1:
The guide member is positioned at a different spatial location (contacting the first surface from above) than the contact member (pressing the second surface from below). This dimensional separation in the vertical direction allows both members to operate independently without interference, even when the contact member applies firm pressure to control the sheet.
Solution Approach 2:
The sheet control function is segmented into two independent actions: the contact member pressing the second surface from below and the guide member guiding the first surface from above. This segmentation allows each member to perform its function independently without mechanical interference, maintaining simple device structure while achieving effective sheet control.
3Strength
If the sheet is heated during fixing, then toner is fixed, but image quality deteriorates due to uneven toner distribution
Solution Approach 1:
The guide member acts as an intermediary that ensures uniform contact and pressure distribution across the first surface of the sheet during the fixing process. By working in conjunction with the contact member on the opposite side, it helps distribute heat and pressure evenly, preventing localized overheating or uneven toner fixation that would compromise image quality.
Solution Approach 2:
The dual-contact configuration (contact member on second surface, guide member on first surface) creates a homogeneous pressure and heat distribution across the entire sheet area during fixing. This homogeneous treatment ensures uniform toner distribution and consistent image quality across the whole sheet, avoiding the defects that would arise from uneven heating or pressing.
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
The solution effectively manages curling by inducing opposing forces to the heat-induced curl, ensuring sheets are discharged without further curling, maintaining image quality and preventing jams, thus enhancing the operational reliability of the image-forming apparatus.
Implementation Method 1
a contact member that comes into contact with the second surface of the medium transported by the transport unit, and that moves in a first direction in which the contact member presses the medium to a side of the first surface
Implementation Method 2
An object in the form of a sheet may curl if it is heated. For example, in an electro-photographic image-forming apparatus, a sheet may curl in the fixing process, in which toner is fixed on the sheet by use of heat.
Data Source
AI summary
A discharge device includes a transport unit that transports a medium in the form of a sheet having a first surface and a second surface on the opposite side of the first surface; a contact member that comes into contact with the second surface of the medium transported by the transport unit, and that moves in a first direction in which the contact member presses the medium to a side of the first surface, and in a second direction opposite to the first direction within a predetermined range; a guide member provided so that the guide member does not come into contact with the contact member, that guides the medium transported by the transport unit while contacting the first surface of the medium, after the contact member comes into contact with the medium; and a discharge unit that discharges the medium guided by the guide member.