Image Forming Apparatus Sheet Interval Control
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Solution Overview
Problem
In image forming apparatuses with a fixing device using an endless belt and a pad, the heat capacity is low, leading to temperature differences between the heating roller and the pressure unit, causing sheet curl and potential wrapping around the roller, especially during continuous printing, regardless of sheet type.
Innovation Solution
An image forming apparatus with a controller that adjusts the sheet interval based on the type of sheet, setting a longer interval for sheets prone to curling to reduce temperature differences and prevent curling, and adjusts the nip pressure and temperature settings to maintain optimal printing conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If continuous printing is performed with a small heat capacity pressure unit, then printing productivity is improved, but temperature difference between heating roller and pressure unit increases causing sheet curl
Solution Approach 1:
The patent changes the physical parameters of the pressure unit by replacing the conventional pad structure with an endless belt having higher heat capacity. This parameter change allows the pressure unit to maintain temperature during continuous printing, reducing the temperature difference with the heating roller and preventing sheet curl while maintaining high productivity
2Speed
If sheet interval is reduced for high speed printing, then printing speed is improved, but temperature difference increases causing curl in sheets prone to curling
Solution Approach 1:
The patent modifies the thermal parameter of the pressure unit by using an endless belt with higher heat capacity, enabling it to maintain temperature even when sheets are fed at short intervals. This allows high-speed printing without causing temperature difference-induced curl in susceptible sheets
3Device complexity
If pad structure is used for pressure unit, then device complexity is reduced, but heat capacity is insufficient leading to temperature instability
Solution Approach 1:
The patent changes the material parameter of the pressure unit from conventional pad material to endless belt material with higher heat capacity. This parameter change provides temperature stability during continuous operation while maintaining relatively simple device structure
Solution Approach 2:
The patent applies the concept of an endless belt (similar to the heating roller's endless belt structure) to the pressure unit, creating a analogous structure that mirrors the thermal characteristics of the heating roller, thereby achieving temperature stability
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 suppresses sheet curling across various sheet types by optimizing sheet intervals and temperature management, ensuring consistent and efficient printing performance.
Implementation Method 1
a heater configured to heat the roller
Implementation Method 2
The sheet is nipped between the endless belt and the roller
Data Source
AI summary
An image forming apparatus includes a roller, a heater configured to heat the roller, an endless belt, a nip forming member, a supply roller configured to supply a sheet, and a controller. The sheet is nipped between the endless belt and the roller. The endless belt is nipped between the nip forming member and the roller such that a nip portion is formed. The controller is configured to supply a plurality of first kind of sheets by the supply roller at a first interval when the plurality of first kind of sheets are sequentially conveyed and supply a plurality of second kind of sheets by the supply roller at a second interval greater than the first interval when the plurality of second kind of sheets belonging to a kind in which curl occurs more frequently than the plurality of first kind of sheets are sequentially conveyed.