Fixing Belt Reflector Opening Width for Nip Temperature Uniformity

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Solution Overview

Problem

Existing fixing devices in image forming apparatuses experience temperature unevenness in the longitudinal direction of the fixing nip due to the wider center portion of the nip formation pad, leading to slower temperature rise at the center and increased heating requirements.

Innovation Solution

A fixing device configuration with a nip formation pad having a wider central region in the longitudinal direction and a reflector with an opening of varying width, where the central region's opening is wider than the end portions, to enhance heat distribution and reduce temperature differences.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the nip formation pad has a wider center portion in the longitudinal direction than each end portion, then the width difference of the fixing nip between center and end portions is reduced, but the temperature at the center portion rises more slowly causing temperature difference in the fixing nip

Engineering Contradiction:

Improveuniformity of fixing nip widthVSAvoidtemperature uniformity in fixing nip

Core Design Contradiction:

Manufacturing precisionVSTemperature

Solution Approach 1:

The reflector is designed with different opening widths at different locations: a first opening at the center portion with a first width, and a second opening at an end portion with a second width. This local differentiation allows the center region to receive more reflected heat than the end regions, compensating for the slower heat conduction at the wider center portion of the nip formation pad.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The reflector's opening width parameter is changed along the longitudinal direction of the nip formation pad. The first width at the center is greater than the second width at the end portions, creating a gradient heat distribution that matches the thermal conductivity gradient of the nip formation pad, thereby achieving uniform temperature distribution across the fixing nip.

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If the center portion of the nip formation pad is wider than end portions, then the fixing nip width difference is reduced, but extra heating is required to heat the center portion to target temperature

Engineering Contradiction:

Improvefixing nip width uniformityVSAvoidheating energy consumption

Core Design Contradiction:

Manufacturing precisionVSUse of energy by moving object

Solution Approach 1:

The reflector provides localized heat reflection with different intensities at different positions. The first opening at the center portion has a larger width to reflect more heat to the center region, while the second opening at end portions has a smaller width. This local quality differentiation optimizes heat distribution without requiring uniform extra heating across the entire pad.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent converts the harmful effect of slow heat conduction at the wider center portion into a beneficial design feature. By intentionally designing the reflector with a larger first opening at the center, the slower heat conduction is compensated by increased reflected heat input, transforming what was originally a problem into a balanced thermal design.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 configuration effectively reduces temperature differences across the fixing nip, ensuring more uniform heating and reducing the need for extra heating to achieve the target fixing temperature.

Implementation Method 1

a reflector (34) disposed inside the loop of the fixing belt (22) and having an opening (34k) opened to the nip formation pad (32)... configured to reflect heat from the heater

Methodology Applied

Scientific EffectReflection: Reflection

Implementation Method 2

a heater configured to heat the fixing belt... heat the fixing belt (22 and the nip formation pad (32) to a target temperature

Methodology Applied

Scientific EffectHeating: Heating

Implementation Method 3

the temperature at the center portion in the longitudinal direction of the nip formation pad (32) rises more slowly than the temperature at each end portion... heat conduction

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP3660595B1Fixing device and image forming apparatus incorporating the same

Publication Date: 2021.02.24 RICOH CO LTD

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AI summary

A fixing device (7) includes an endless fixing belt (22), a heater (31), a pressing member (23), a nip formation pad (32) disposed inside a loop of the fixing belt (22) and configured to contact the pressing member (23) to form a fixing nip, and a reflector (34) disposed inside the loop of the fixing belt (22) and configured to reflect heat from the heater (31). The nip formation pad (32) has a wider width at a portion corresponding to a central region in a longitudinal direction than an end portion of the nip formation pad (32) in the longitudinal direction. The reflector (34) extends in a longitudinal direction of the nip formation pad (32) and has an opening (34k) opened to the nip formation pad (32). The opening (34k) has a wider width at a portion corresponding to the central region in the longitudinal direction than a width at an end portion of the reflector (34) in the longitudinal direction; and corresponding image forming apparatus.