PTC Heater Blocks for Non-Sheet-Passing Temperature Control
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Solution Overview
Problem
Existing image heating devices in copiers and printers experience temperature rise at non-sheet-passing portions, leading to component damage and toner offset, despite the use of heat generating resistors with positive temperature coefficient (PTC) to reduce current flow.
Innovation Solution
A heater design with multiple heating blocks, each comprising a first and second conductive element and a PTC resistor, allowing independent power control of each block, and a diagonal power feeding method to ensure uniform heat distribution and reduce temperature rise at non-sheet-passing areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a heat generating resistor with positive temperature coefficient is used to reduce current flow at high temperature, then temperature rise at non-sheet-passing portion is reduced, but heat generation at the same portion cannot be completely eliminated
Solution Approach 1:
The heater is divided into multiple heating blocks (first heating block, second heating block, third heating block) along the conveying direction. Each heating block can be independently controlled, allowing selective activation of blocks based on paper size and position, thereby eliminating unnecessary heat generation at non-sheet-passing portions while maintaining effective heating where needed.
Solution Approach 2:
The heater employs dynamic control mechanisms including a moving contact 131 that shifts position based on paper size detection, and a controller 105 that adjusts power supply to different heating blocks according to real-time temperature feedback from temperature sensors 121-124. This dynamic adaptation allows the system to optimize heat generation patterns, reducing energy loss at non-sheet-passing portions while maintaining effective heating.
2Stability of the object's composition
If power is supplied to all heating blocks simultaneously, then uniform heat distribution is achieved, but temperature rise at non-sheet-passing portion increases
Solution Approach 1:
Different heating blocks are activated selectively based on the actual paper size and position. For example, when small size paper is conveyed, only the central heating block is activated, while side heating blocks remain inactive. This local activation strategy ensures uniform heat distribution across the paper width while preventing temperature rise at non-sheet-passing portions, as each active block provides targeted heating only where paper is present.
Solution Approach 2:
Temperature sensors 121-124 positioned at different locations provide real-time feedback to the controller 105 about the actual temperature distribution. Based on this feedback, the controller dynamically adjusts power supply to different heating blocks, activating only those needed to maintain uniform heat distribution while avoiding excessive temperature at non-sheet-passing portions. This closed-loop control ensures optimal balance between heat uniformity and temperature control.
3Device complexity
If the heater structure is simplified to reduce device complexity, then manufacturing cost is reduced, but temperature control precision deteriorates
Solution Approach 1:
The heater is segmented into multiple independently controllable heating blocks, each with its own temperature sensor and control pathway. This segmentation allows for distributed temperature control, where each block can be precisely controlled based on local temperature feedback, achieving high temperature control precision without requiring a complex centralized control system. The modular structure simplifies manufacturing while enabling precise control.
Solution Approach 2:
Each heating block is equipped with its own temperature sensor and control mechanism, enabling self-regulation based on local temperature conditions. This self-service approach reduces the need for complex external control systems, as each block automatically adjusts its operation based on feedback from its own temperature sensor, achieving precise temperature control with relatively simple overall structure.
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
Effectively prevents temperature rise at non-sheet-passing portions, ensuring even heat distribution and enhanced safety by reducing current flow and temperature in areas without paper, thereby preventing component damage and toner offset.
Implementation Method 1
a heat generating resistor provided between the first conductive element and the second conductive element and showing a positive temperature characteristic of resistance, which generates heat when power is supplied via the first conductive element and the second conductive element
Implementation Method 2
a heat generating resistor provided between the first conductive element and the second conductive element and showing a positive temperature characteristic of resistance
Data Source
AI summary
A heater of the present invention includes jointed heat generating resistors having a positive temperature characteristic of resistance and provided between a first conductive element and a second conductive element on a substrate in a longitudinal direction of the substrate, and a plurality of heating blocks provided in the longitudinal direction, each of which is a set of the first conductive element, the second conductive element, and the heat generating resistor, and power supplied to at least one of the plurality of heating blocks can be controlled independent of other heating blocks.