Sheet Charge Polarity Control for Reliable Duplex Stacking
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Solution Overview
Problem
Existing image forming apparatuses face issues with sheets sticking together due to electrostatic charges, particularly when sheets are charged with the same polarity, leading to stacking failures, and existing solutions do not adequately address the need for polarity-specific charge removal or application based on print settings.
Innovation Solution
The image forming apparatus incorporates a charge removing unit and a charge application unit with control units to manage voltage polarity based on print mode (simplex or duplex) and sheet orientation, ensuring appropriate polarity application for charge removal or addition, using contact and non-contact methods to prevent sheet sticking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If voltage with the same polarity as the charged sheet surface is applied, then the charging of the sheet deteriorates, but this causes sheets to stick together due to electrostatic force
Solution Approach 1:
The charge removing control unit dynamically switches the polarity of voltage applied to the charge removing member based on the detected sheet discharge surface orientation (front surface or rear surface). This dynamic adaptation ensures the applied voltage always has appropriate polarity to remove charges effectively regardless of which surface is discharged, preventing sheet sticking while maintaining reliable stacking
Solution Approach 2:
The system changes the polarity parameter of the applied voltage based on the sheet discharge condition. When the front surface is discharged, one polarity is applied; when the rear surface is discharged, the opposite polarity is applied. This parameter change allows the charge removing member to effectively neutralize charges on whichever surface is facing outward, preventing electrostatic sticking
2Reliability
If a charge removing unit is added to remove sheet charges, then sheet sticking is prevented, but the device complexity increases
Solution Approach 1:
The charge removing member is designed to perform charge removal functionality regardless of which surface of the sheet is discharged. By combining the charge removing member with a polarity switching control unit that detects sheet orientation, a single component can handle both front-surface and rear-surface discharge scenarios, eliminating the need for separate charge removing units for each surface and thus reducing overall device complexity
Solution Approach 2:
The charge removing control unit automatically detects the sheet discharge surface orientation and self-adjusts the voltage polarity without external intervention. This self-service capability eliminates the need for complex manual switching mechanisms or additional sensors, allowing the system to adapt to different discharge conditions autonomously while maintaining simple device architecture
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 prevents sheet sticking by adjusting voltage polarity according to print settings, ensuring uniform charge removal and application, thereby improving the reliability of the image forming process.
Implementation Method 1
a charge removing unit that is arranged downstream of the reversing conveyance path in a sheet conveyance direction and removes a charge of a sheet by applying voltage to a charge removing member
Implementation Method 2
a charge application unit that is arranged downstream of the reversing conveyance path in a sheet conveyance direction and applies charge to a sheet by applying voltage to a charge application member
Implementation Method 3
applying voltage to a charge removing member
Data Source
AI summary
An image forming apparatus includes an image printing unit configured to print an image on a sheet, a charge removing unit that is arranged downstream of a reversing conveyance path in a sheet conveyance direction and configured to remove a charge of a sheet, and a charge removing control unit configured to control voltage to be applied to the charge removing member, wherein the charge removing control unit performs control to apply voltage to the charge removing member with first polarity in a case where a first simplex printing operation is executed, to apply voltage to the charge removing member with second polarity in a case where a second simplex printing operation is executed, and to apply voltage to the charge removing member with the first polarity in a case where a duplex printing operation is executed.