Fixing Device Surface Pressure and Hardness for Toner Anchoring
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Solution Overview
Problem
Image forming apparatuses using electrophotography face challenges in achieving low temperature fixability and hot offset resistance due to toner with low ductility, where increasing surface pressure degrades hot offset resistance and energy efficiency.
Innovation Solution
An image forming apparatus with a fixing device having a surface pressure of 1.5 kgf/cm2 or less and a Martens hardness of 1.0 N/mm2 or less at 23° C., along with toner particles exhibiting a projected area ratio of 1.60 or less at 120° C. to 23° C., to improve anchoring and fixability while maintaining energy efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the surface pressure of the nipping portion is increased to improve anchoring between toner and recording medium, then low temperature fixability is improved, but hot offset resistance is degraded
Solution Approach 1:
The invention changes the physical parameters of the fixing members by controlling their hardness (Martens hardness of 1.0 N/mm² or less at 23°C) and surface pressure (1.5 kgf/cm² or less), allowing optimal anchoring without excessive pressure that would cause hot offset
Solution Approach 2:
The invention uses composite material structures for the fixing members, combining materials with specific hardness characteristics to achieve both sufficient anchoring force and adequate releasability, resolving the contradiction between fixability and hot offset resistance
2Reliability
If the surface pressure of the nipping portion is increased to improve anchoring, then low temperature fixability is improved, but energy efficiency is degraded due to increased heat capacity of fixing members
Solution Approach 1:
By changing the hardness parameter of the fixing members to 1.0 N/mm² or less, the invention reduces the required surface pressure to 1.5 kgf/cm² or less, which decreases the heat capacity and thickness of the fixing members, thereby improving energy efficiency while maintaining fixability
3Reliability
If crystalline resin content in toner is increased to improve low temperature fixability, then anchoring is improved, but toner becomes soft and weak to stirring stress, causing agglomeration
Solution Approach 1:
The invention optimizes the crystalline resin content parameter in toner to achieve sufficient anchoring force while maintaining toner strength and resistance to stirring stress, preventing agglomeration in the development unit
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 enhances low temperature fixability and hot offset resistance for toner with low ductility, ensuring effective image formation and energy efficiency in image forming apparatuses.
Implementation Method 1
a fixing device to fix the visible image transferred onto the recording medium, the fixing device including a fixing rotation member; and a pressure rotation member to form a nipping portion by contacting the fixing rotation member
Implementation Method 2
a charger to charge the image bearing member
Implementation Method 3
an irradiator to expose the image bearing member to light to form a latent electrostatic image thereon
Data Source
AI summary
An image forming apparatus includes: an image bearing member; a charger; an irradiator; a development device having an accommodation unit to accommodate toner to obtain a visible image; a transfer device; and a fixing device to fix the visible image transferred onto a recording medium. The fixing device having a fixing rotation member; and a pressure rotation member to form a nipping portion by contacting the fixing rotation member, wherein the surface pressure of the nipping portion is 1.5 kgf/cm2 or less, wherein the fixing rotation member has a Martens hardness of 1.0 N/mm2 or less at 23° C., wherein the ratio of the projected area of a single particle of the toner onto the recording medium at 120° C. to the projected area of a single particle of the toner onto the recording medium at 23° C. is 1.60 or less.