Movable Cover Guide for Jammed Sheet Extraction in Image Forming Apparatus
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Solution Overview
Problem
Conventional image-forming devices face issues with liquid ingress when spilled, difficulty in extracting jammed sheets between discharge and fixing units, and precision temperature detection of heating rollers due to external air and airflow effects.
Innovation Solution
The design incorporates a movable second conveying guide that can be positioned to expose or cover the conveying path, a top cover that moves to open or close, and a thermistor protected by a cover to reduce temperature fluctuation effects, facilitating sheet extraction and precise temperature detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the cover is opened to allow user access for removing jammed sheets, then ease of operation is improved, but liquid can flow directly into the fixing unit causing reliability deterioration
Solution Approach 1:
The cover is divided into a first cover portion and a second cover portion that can move relative to each other. The second cover portion can be independently opened to expose only the conveying path for sheet removal, while the first cover portion remains closed to protect the fixing unit from liquid ingress.
Solution Approach 2:
Different portions of the cover have different protective functions. The first cover portion protects the fixing unit from liquid, while the second cover portion allows localized access to the conveying path. This selective protection approach enables both ease of operation and reliability.
2Reliability
If the conveying path is fully enclosed to prevent liquid ingress, then reliability is improved, but difficulty in extracting jammed sheets increases
Solution Approach 1:
The second cover portion is designed to be movable, allowing the conveying path to be dynamically opened or closed. When a sheet is jammed, the second cover portion can be opened to facilitate sheet extraction. When not in use, it remains closed to prevent liquid ingress, thus resolving the contradiction between reliability and ease of operation.
3Measurement precision
If the thermistor element is exposed to detect temperature, then measurement capability is improved, but temperature detection precision deteriorates due to external air and airflow effects
Solution Approach 1:
A thermistor protection portion is introduced as an intermediary structure between the thermistor element and the external environment. This protection portion allows the thermistor to detect temperature while shielding it from direct exposure to external air and airflow, thus maintaining measurement precision without excessive complexity.
4Measurement precision
If the thermistor element is protected from external air, then temperature detection precision is improved, but device complexity increases
Solution Approach 1:
The thermistor protection portion is merged with the cover structure, specifically integrated into the first cover portion. This integration approach provides thermistor protection while avoiding additional complex structures, as the cover itself serves dual purposes: protecting the fixing unit from liquid and shielding the thermistor from external air effects.
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 liquid from entering the fixing unit, simplifies sheet extraction, and enhances the precision of temperature detection of the heating roller, improving operational reliability and user convenience.
Implementation Method 1
The thermistor element is a non-contact thermistor that detects the temperature of the heating rotary body without contacting the surface thereof
Implementation Method 2
a fixing unit (60) having a heating roller (61) and configured to thermally fix a developer image deposited on a sheet (S)
Data Source
AI summary
An image forming apparatus includes a fixing unit, discharge unit, first and second guides, and top cover. The discharge unit is disposed obliquely above a heating member of the fixing unit. The first guide extends from a position above the heating member toward the discharge unit and has an upstream portion in a conveying direction of an image-fixed sheet. The second guide is disposed above the heating member and faces the upstream portion. The second guide defines an upper portion of the conveying path. A part of the second guide faces the upstream portion in the first position, and exposes the upstream portion in the second position. The top cover is movable between an open position where the second guide is exposed and a closed position where the second guide is covered. The first guide has a guide surface sloping downward in the conveying direction.