Wiring Sheet Electrode Layout for Uniform Heater Temperature

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Solution Overview

Problem

The use of thin electrodes, such as metal wires, in wiring sheets results in significant temperature variation due to a relatively large resistance difference between the electrodes and conductive linear bodies, making the electrode's resistance value non-negligible and causing temperature fluctuations during heat generation.

Innovation Solution

A wiring sheet design that satisfies specific resistance value conditions (F1, F2, and F3) is implemented, where the resistance of conductive linear bodies and electrodes are balanced to minimize temperature variation, with conductive linear bodies arranged at intervals not exceeding 20 mm and electrodes' resistance increasing with distance from power feeders.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If thin electrodes such as metal wires are used to improve flexibility of electrode portions, then flexibility is improved, but resistance value of electrodes increases causing temperature variation

Engineering Contradiction:
Improveflexibility of electrode portionsVSAvoidtemperature variation
Core Design Contradiction:
Ease of operationVSTemperature

Solution Approach 1:

The patent applies local quality by making the electrode width variable along its length. The electrode is designed with a wider section at the power feeder end and a narrower section at the opposite end, creating non-uniform local properties. This allows the electrode to have lower resistance where needed (near power feeders) while maintaining flexibility elsewhere, resolving the contradiction between flexibility and resistance control.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent changes the geometric parameter of the electrode (width) to control its electrical resistance. By varying the width along the electrode length, the resistance distribution is optimized. This parameter change allows thin electrodes to be used while controlling overall resistance and minimizing temperature variation, addressing both flexibility and temperature stability requirements.

Inventive Principle:
Principle #35Parameter changes

2Loss of substance

If thin electrodes are used to reduce material usage and cost, then manufacturing cost is reduced, but resistance value becomes significant causing temperature variation

Engineering Contradiction:
Improvematerial usage of electrodesVSAvoidtemperature variation
Core Design Contradiction:
Loss of substanceVSTemperature

Solution Approach 1:

The electrode is designed with varying local width to optimize material usage. The wider section near power feeders provides lower resistance with minimal additional material, while the narrower section reduces overall material consumption. This local quality variation allows cost-effective thin electrode design while controlling temperature variation through strategic material placement.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

By changing the width parameter of the electrode along its length, the patent achieves optimal balance between material usage and resistance control. The variable width design uses material more efficiently - concentrating it where resistance control is most critical - thereby reducing overall material consumption while preventing temperature variation.

Inventive Principle:
Principle #35Parameter changes

3Ease of manufacture

If uniform width electrodes are used to simplify manufacturing, then manufacturing complexity is reduced, but temperature distribution becomes non-uniform

Engineering Contradiction:
Improveelectrode manufacturing simplicityVSAvoidtemperature distribution uniformity
Core Design Contradiction:
Ease of manufactureVSTemperature

Solution Approach 1:

The patent implements local quality variation in electrode width to achieve uniform temperature distribution. The wider sections near power feeders compensate for higher current density and heat generation, while narrower sections in other areas maintain appropriate resistance. This local variation, while adding manufacturing complexity, is achieved through straightforward width control during electrode formation.

Inventive Principle:
Principle #3Local quality

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

The design effectively restrains temperature variation by ensuring the resistance values of electrodes and linear bodies are proportionate, maintaining consistent heat generation and reducing temperature differences across the sheet.

Implementation Method 1

when electric current is applied to the wiring sheet for heat generation

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Data Source

PatentEP4247116B1Wiring sheet and sheet-form heater
Publication Date: 2026.02.25 LINTEC CORP
  • EP4247116B1 patent drawingFigure 1
  • EP4247116B1 patent drawingFigure 2
  • EP4247116B1 patent drawingFigure 3

AI summary

A wiring sheet includes: a pseudo sheet structure (2) including a plurality of conductive linear bodies (21) arranged at intervals; a pair of electrodes (4); and a first power feeder (51) provided for one of the electrodes (4) and a second power feeder (52) provided for the other of the electrodes (4), in which provided that the number of the conductive linear bodies (21) is N, a resistance value of each conductive linear body (21) is r, a resistance value of each electrode (4) is R, a resistance value of each electrode (4) between the n-th conductive linear body (21) and the (n-1)th conductive linear body (21) counted from a side at which the first power feeder (51) and the second power feeder (52) are provided is Rn, the wiring sheet satisfies all conditions represented by numerical formulae (F1), (F2) and (F3) below, r/R≤300 Rn≤Rn−1 where n is an integer of 2 or more, 0<R2−RN