Divided Heater Blocks for Thermal Management in Image Formers

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Solution Overview

Problem

Existing image heating apparatuses in electrophotographic systems face challenges in preventing temperature rises in non-sheet-passing portions during continuous printing, leading to potential overheating and the need for throughput reduction or standby periods to manage heat equilibrium.

Innovation Solution

The apparatus employs a heater configuration with divided heat generating blocks and independent power control, utilizing thermistors to detect temperature differences and adjust electric power distribution along the heater's length, ensuring balanced heat distribution and minimizing throughput reduction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If continuous printing is performed on recording materials smaller than maximum sheet-passing width, then productivity is improved, but temperature rise occurs in non-sheet-passing portions

Engineering Contradiction:
ImprovethroughputVSAvoidtemperature of non-sheet-passing portion
Core Design Contradiction:
ProductivityVSTemperature

Solution Approach 1:

The heater is divided into multiple heat generating blocks along the longitudinal direction, with each block independently controllable. This segmentation allows selective heating of only those regions where recording material passes, preventing temperature rise in non-sheet-passing portions while maintaining high throughput

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different regions of the heater are provided with different heating characteristics by dividing it into multiple blocks. The heat generating blocks positioned at non-sheet-passing portions have reduced or zero power supply, creating local heating differences that prevent temperature accumulation in specific areas

Inventive Principle:
Principle #3Local quality

2Temperature

If throughput is decreased to suppress temperature rise, then temperature control is improved, but productivity deteriorates

Engineering Contradiction:
Improvetemperature controlVSAvoidthroughput
Core Design Contradiction:
TemperatureVSProductivity

Solution Approach 1:

The power supply to heat generating blocks is dynamically adjusted based on real-time temperature detection. When temperature in non-sheet-passing portions approaches limits, the system automatically reduces power to affected blocks, enabling continuous operation at high throughput without manual intervention or standby periods

Inventive Principle:
Principle #15Dynamics

3Temperature

If heater is divided into multiple heat generating blocks with independent power control, then temperature distribution is improved, but device complexity increases

Engineering Contradiction:
Improvetemperature distributionVSAvoidheater control system
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The heater is divided into multiple heat generating blocks along the longitudinal direction, with each block independently controllable. This segmentation allows selective heating of only those regions where recording material passes, preventing temperature rise in non-sheet-passing portions while maintaining high throughput

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Temperature detection elements are positioned to detect temperatures at heat generating blocks, and the system automatically adjusts power distribution based on detected temperatures, enabling self-regulating temperature control without complex external intervention

Inventive Principle:
Principle #25Self-service

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 solution effectively suppresses temperature rises in non-sheet-passing portions, maintaining high throughput and preventing overheating, while reducing the need for extended standby periods, thus enhancing operational efficiency and reliability.

Implementation Method 1

a heat generating element provided on an inner surface of the fixing film, generates heat by being energized

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Implementation Method 2

temperature detection elements provided at respective heat generating blocks, detect temperatures at the heat generating blocks

Methodology Applied
Scientific EffectThermistor effect: Thermistor

Data Source

PatentEP3276429B1Image heating apparatus and image forming apparatus
Publication Date: 2022.01.05 CANON KK
  • EP3276429B1 patent drawingFigure 1
  • EP3276429B1 patent drawingFigure 2
  • EP3276429B1 patent drawingFigure 3

AI summary

An apparatus includes a heater including a first and second heat generating blocks; and a power control portion that controls electric power to be supplied to respective heat generating blocks. When a recording material passes the position of the heater, and in a longitudinal direction of the heater, when an entire range in which the second heat generating block is provided is a range in which the recording material passes and only a portion of a range in which the first heat generating block is provided is a range in which the recording material passes, the power control portion controls the electric power to be supplied to respective heat generating blocks so that an electric power Wd supplied to the first heat generating block is smaller than an electric power Wc supplied to the second heat generating block.