Sheet Conveyance Control for Static Discharge in Image Forming Systems
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Solution Overview
Problem
In image forming systems, the ejection sheet sticking phenomenon occurs due to insufficient discharge of static electricity during post-processing, especially in low temperature and humidity environments or duplex printing modes, leading to difficulties in turning pages of booklets created by post-processing.
Innovation Solution
An image forming system with a discharge member and voltage applying unit that accelerates the conveying speed of sheets between the image forming unit and post-processing unit, controlling the acceleration timing based on the type of post-processing to ensure effective discharge of static electricity and prevent sheet sticking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the sheet is accelerated during discharge of static electricity by the discharge member, then post-processing time is reduced and productivity is improved, but the discharge current value becomes inappropriate and static electricity cannot be sufficiently discharged
Solution Approach 1:
The patent applies dynamics by making the conveying speed variable during the discharge process. The sheet is conveyed at a first speed during discharge and then accelerated to a second speed after discharge is complete. This dynamic speed adjustment ensures appropriate discharge current during the discharge phase while still achieving productivity improvement through acceleration afterward.
Solution Approach 2:
The patent applies preliminary action by completing the static electricity discharge process at a controlled first speed before accelerating the sheet. This ensures that the discharge is fully accomplished under optimal conditions before the speed change, preventing any residual static electricity issues while still allowing subsequent acceleration for productivity.
2Productivity
If sheets are continuously stacked on the sheet ejection tray, then printing efficiency is maintained, but air between sheets is compressed and electrostatic attraction increases causing sheet sticking
Solution Approach 1:
The patent extracts the harmful electrostatic charge from the sheets by introducing a discharge member that applies discharge voltage to remove static electricity from the toner image surface. This extraction of the harmful factor (static charge) prevents sheet sticking while allowing continuous stacking and maintaining printing efficiency.
Solution Approach 2:
The discharge member acts as an intermediary between the sheets and the electrostatic problem. By positioning the discharge member in the sheet conveyance path, it mediates the electrostatic issue by providing a controlled discharge path that neutralizes charges without interfering with the continuous printing process or sheet stacking.
3Reliability
If discharge voltage is applied to the discharge member, then static electricity is discharged from the sheet, but sheet acceleration during discharge causes inappropriate discharge current and insufficient charge removal
Solution Approach 1:
The patent applies dynamics by implementing variable speed conveyance - maintaining a first speed during discharge voltage application and then accelerating to a second speed after discharge completion. This dynamic control ensures appropriate discharge current during the voltage application phase while still achieving productivity through subsequent acceleration.
Solution Approach 2:
The patent applies periodic action by dividing the conveyance process into distinct phases: a first period at constant speed during discharge voltage application, and a second period with acceleration after discharge. This periodic speed adjustment ensures proper discharge current control during the critical discharge phase while maintaining operational efficiency.
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
Prevents sheet sticking during post-processing by optimizing the discharge of static electricity, allowing for smooth page turning of booklets regardless of the post-processing type, thereby enhancing the usability and quality of the final printed products.
Implementation Method 1
a discharge member that is arranged between the image forming unit and the post-processing unit in a sheet conveying direction, and discharges static electricity from the sheet that is conveyed by the conveying unit
Implementation Method 2
a voltage applying unit that applies to the discharge member a discharge voltage for discharging static electricity from the sheet
Data Source
AI summary
An image forming system includes: an image forming unit that forms a toner image on a sheet; a post-processing unit that performs post-processing to the sheet; a conveying unit that conveys the sheet from the image forming unit to the post-processing unit; a discharge member that is arranged between the image forming unit and the post-processing unit in a sheet conveying direction, and discharges static electricity from the sheet conveyed by the conveying unit; a voltage applying unit that applies to the discharge member a discharge voltage for discharging static electricity from the sheet; and a control unit that accelerates a conveying speed of the sheet when the discharge voltage is applied by the voltage applying unit, and controls the conveying unit to vary acceleration timing for accelerating the conveying speed of the sheet in accordance with a type of the post-processing.