Image Forming Apparatus Developing Contrast Control for Thin Sheets
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Solution Overview
Problem
Existing image forming apparatuses face difficulties in handling various sheet thicknesses, particularly thin sheets, as they often get wound around rollers, leading to potential claw marks and increased costs due to the need for additional peeling mechanisms.
Innovation Solution
The image forming apparatus includes a control unit that discriminates between two modes based on sheet thickness, adjusting the developing contrast electric potential and transfer biases to reduce toner attachment and prevent sheet winding, using a pressing control unit to manage the transfer rollers and fixer interactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the image forming apparatus uses a standard transfer process with fixed developing contrast electric potential, then thick sheets can be printed with sufficient toner attachment, but thin sheets get wound around rollers and may receive excessive toner attachment
Solution Approach 1:
The patent applies dynamics by making the developing contrast electric potential variable rather than fixed. The control unit dynamically adjusts the developing contrast electric potential based on detected sheet thickness, switching between a first potential for thick sheets and a second potential for thin sheets. This dynamic adaptation resolves the contradiction by allowing optimal toner attachment control for each sheet type while preventing sheet winding issues.
Solution Approach 2:
The patent changes the electrical parameter (developing contrast electric potential) based on sheet thickness. By detecting sheet thickness and adjusting the developing contrast electric potential accordingly, the system optimizes toner attachment for thin sheets while preventing excessive attachment that causes winding. This parameter change approach directly addresses both the toner attachment control and sheet winding prevention requirements.
2Reliability
If the image forming apparatus provides a transfer peeling portion or peeling claw to facilitate peeling of thin sheets, then sheet winding is avoided, but claw marks may be left on the sheet increasing costs
Solution Approach 1:
The patent replaces the mechanical peeling system (peeling claws or transfer peeling portions) with an electrical control system. By adjusting the developing contrast electric potential, the system controls toner attachment at the molecular level, eliminating the need for mechanical intervention. This substitution resolves the contradiction by preventing sheet winding through electrical parameter optimization rather than mechanical peeling, thus avoiding claw marks on sheets.
3Adaptability or versatility
If the image forming apparatus is designed to cope with various sheet thicknesses, then versatility is improved, but device complexity increases
Solution Approach 1:
The patent applies universality by creating a single engine design that can handle various sheet thicknesses through a unified control mechanism. The control unit detects sheet thickness and automatically adjusts the developing contrast electric potential, allowing one engine to serve multiple functions (printing on thin sheets, thick sheets, coated sheets, etc.). This multi-functionality approach resolves the contradiction by providing versatility without requiring separate engines for different sheet types.
Solution Approach 2:
The patent uses parameter changes to maintain a simple engine design while achieving versatility. By varying the developing contrast electric potential based on sheet thickness detection, the same hardware configuration can adapt to different recording media. This parameter-based adaptation eliminates the need for complex mechanical modifications or multiple engine designs, resolving the contradiction between versatility and device complexity.
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 effectively suppresses sheet winding and maximizes toner attachment control, preventing claw marks and reducing costs by optimizing toner distribution and transfer processes for both thick and thin sheets.
Implementation Method 1
a surface of a photoconductive drum is similarly charged
Implementation Method 2
a laser beam is radiated to the charged photoconductive drum to form an electrostatic latent image
Implementation Method 3
the electrostatic latent image of the photoconductive drum is developed by a developing device to form a toner image
Implementation Method 4
The toner image of the photoconductive drum is primary transferred to a rotating intermediate transfer belt and the like, and the toner image is secondary transferred onto the sheet
Implementation Method 5
The sheet, onto which the toner image is transferred, is heated by a fixer and a toner image is fixed on the sheet
Data Source
AI summary
An image forming apparatus according to an embodiment includes a charging device that charges an electric charge to an image carrier, a developing device supplying the image carrier with a developer, and a transfer device that transfers a toner image formed on the image carrier by a developing device onto a recording medium. The apparatus further includes a control unit, discriminates between a first mode of forming an image on a first recording medium of a first thickness and a second mode of forming an image on a second recording medium thinner than the first recording medium to control a developing contrast electric potential, and controls a magnitude of the developing contrast electric potential in the second mode so as to be lower than the first mode.