Fixing Device Discharge Guide for Safe Jam Clearance

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Solution Overview

Problem

Existing image forming apparatuses lack effective safety measures to prevent exposure of high-temperature fixing members during sheet jam removal, particularly on the discharge side, and actuator displacement due to sheet impact during jam clearance.

Innovation Solution

A fixing device with a discharge guide and actuator mechanism that includes a rotating shaft and detection pieces to accurately detect sheet presence, combined with a cover that exposes the fixing device on the discharge side, allowing safe sheet jam treatment without power interruption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If a heating body with high temperature increasing property is used to heat only the pressurized region, then energy saving is improved, but safety deteriorates due to risk of user contact with hot fixing member

Engineering Contradiction:

Improveenergy savingVSAvoidsafety risk from hot fixing member

Core Design Contradiction:

Use of energy by moving objectVSObject-affected harmful factors

Solution Approach 1:

The fixing device is segmented into multiple functional regions: an exposed discharge side region and a covered heat source region. The shutter selectively covers only the necessary areas (heat source and pressurized region) while leaving the discharge side exposed, allowing energy-efficient localized heating while maintaining safety by preventing access to hot zones.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A shutter mechanism acts as an intermediary between the user and the hot fixing member. The shutter can be opened to expose the discharge side for sheet removal while remaining closed to protect the heat source region, mediating between the need for user access and the need to prevent contact with hot surfaces.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of operation

If no shutter is provided on the discharge side to allow easy sheet removal, then ease of operation is improved, but safety deteriorates due to exposure of heater and fixing member

Engineering Contradiction:

Improveease of sheet removalVSAvoidexposure of heater and fixing member

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The discharge guide is segmented with a slit that selectively exposes only the discharge side while keeping the heat source region covered. This allows users to access and remove sheets from the discharge side without exposing them to the hot heater and fixing member, maintaining both ease of operation and safety.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the fixing device have different exposure qualities: the discharge side is locally exposed for easy sheet removal, while the heat source and pressurized region remain covered for safety. This localized quality differentiation resolves the contradiction between accessibility and safety.

Inventive Principle:

Principle #3Local quality

3Measurement precision

If the detection piece is exposed to allow sheet detection, then detection function is improved, but reliability deteriorates due to position displacement when jammed sheet is removed

Engineering Contradiction:

Improvesheet detection accuracyVSAvoidactuator position stability

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The detection piece is nested within the slit of the discharge guide, which acts as a protective housing. The slit allows the detection piece to detect sheets passing through while preventing direct contact with jammed sheets that could displace the actuator, maintaining both detection functionality and position stability.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The slit in the discharge guide serves as an intermediary structure between the detection piece and the sheet path. It allows optical or mechanical detection to occur while physically protecting the detection piece from direct sheet contact during jam removal, preventing position displacement.

Inventive Principle:

Principle #24Intermediary (Mediator)

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

Ensures safe and efficient sheet jam clearance without risking contact with high-temperature components and maintains accurate actuator detection, enhancing user safety and operational efficiency.

Implementation Method 1

a method of heating only a pressurized region by using a heating body (a flat heater) formed with a resistance heating element on a ceramic substrate

Methodology Applied

Scientific EffectResistance heating: Joule Heating

Data Source

PatentUS12416889B2Fixing device including discharge guide guiding sheet passed through pressurized region and image forming apparatus

Publication Date: 2025.09.16 KYOCERA DOCUMENT SOLUTIONS INC

AI summary

A fixing device includes a fixing member, a pressure roller, a discharge rollers pair, a discharge guide, and an actuator. The fixing member is heated by a heat source. The pressure roller forms a pressurized region. The discharge rollers pair includes an upper roller and a lower roller, and conveys the sheet passed through the pressurized region. The discharge guide guides the sheet passed through the pressurized region to the discharge rollers pair. The actuator includes a rotating shaft supported by the discharge guide rotatably and movably in an axial direction and a detection piece extending radially from the rotating shaft, and rotated by the sheet passed through the pressurized region to detect the sheet. The discharge guide has a slit in which the detection piece is housed to regulate a moving of the detection piece in a width direction of the sheet.