Sheet Conveying Device Separation Jam Prevention
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Solution Overview
Problem
Existing sheet conveying devices in image forming apparatuses face challenges in accurately determining the separation state between sheets and rotating bodies, leading to potential separation jams and increased power consumption due to inefficient separation mechanisms.
Innovation Solution
A sheet conveying device equipped with a separation state determining unit that includes an illumination unit and an imaging unit to acquire positional information of the sheet tip, allowing for precise determination of the separation state and controlled separation using a sheet separating unit, thereby preventing separation jams and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separating claw is used to forcibly separate the recording sheet from the fixing roller, then sheet separation is improved, but the fixing roller surface is worn and fixing property becomes nonuniform
Solution Approach 1:
The patent replaces the mechanical separating claw system with a non-contact air flow separation system. A blowing unit directs air flow to the gap between the sheet tip and fixing roller surface, utilizing aerodynamic forces to separate the sheet without mechanical contact, thereby preventing wear on the fixing roller while maintaining effective sheet separation
Solution Approach 2:
The patent employs pneumatic principles by using a blowing unit to generate controlled air flow that acts on the sheet tip in the gap region. The air flow provides the necessary force to separate the sheet from the fixing roller surface without requiring mechanical contact, thus solving the wear problem while maintaining separation reliability
2Ease of manufacture
If air type separation system is used to separate sheet non-contact, then fixing roller surface is not worn, but heat is taken from fixing roller and power consumption increases
Solution Approach 1:
The patent implements periodic or conditional operation of the blowing unit based on detected separation states. The separation assistance is provided only when separation difficulty is detected, rather than continuously, thereby reducing heat loss from the fixing roller and lowering power consumption while maintaining effective separation when needed
Solution Approach 2:
The patent adjusts the operation parameters of the blowing unit based on the detected separation state. By changing the air flow intensity or activation timing according to the separation difficulty, the system minimizes heat loss from the fixing roller while providing sufficient separation force only when necessary, thus optimizing power consumption
3Measurement precision
If laser displacement sensor is used to detect sheet position, then separation state can be determined, but device complexity increases
Solution Approach 1:
The patent uses an imaging unit to capture an image of the sheet tip position and then processes this visual information to determine separation state. This approach replaces complex mechanical or electromagnetic sensing with optical imaging and image processing, simplifying the detection system while maintaining measurement precision
Solution Approach 2:
The patent introduces an imaging unit as an intermediary that converts the physical sheet position into visual information. This intermediary approach allows for non-contact, optically-based detection of sheet position and separation state, reducing the complexity associated with direct mechanical or electromagnetic sensing systems
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 device enables prompt and accurate determination of the separation state, preventing separation jams and reducing power consumption by optimizing the operation of the sheet separating mechanism.
Implementation Method 1
an illumination unit configured to illuminate a nip portion in a sheet passing direction
Implementation Method 2
there is a method of separating the recording sheet without generating scratches in the peripheral surface of the fixing roller, by strongly blowing air from a tip of a nozzle to a gap slightly caused between a tip of the recording sheet and the periphery surface of the fixing roller
Data Source
AI summary
A sheet conveying device that passes a sheet to a nip portion formed between first and second rotating bodies, and conveys the sheet, the sheet conveying device includes a separation state determining unit configured to determine a separation state between the sheet having passed the nip portion and a surface of the first rotating body, a sheet separating unit configured to allow force to act on the sheet, and a control unit configured to control the force acting on the sheet by the sheet separating unit according to a result of the separation state determining unit, wherein the separation state determining unit includes an illumination unit, an imaging unit, and an acquisition unit, and the separation state between the sheet and the first rotating body is determined based on the acquired positional information of a tip of the sheet.