Thermal Head Electrode Geometry for Residue Prevention

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Solution Overview

Problem

When heat generating portions in thermal heads are positioned downstream of the ridge portion, the top portion is subjected to maximum pressing force, leading to a risk of printing residue adhering to the first corner portion, which can cause residue accumulation and interference with the recording medium.

Innovation Solution

The thermal head design includes heat generating portions positioned downstream of the ridge portion, with at least one electrode's first corner portion located more upstream, having an inclination angle of 75° or less from the substrate, reducing the likelihood of residue accumulation by minimizing the pressing force and exposure to printing residue.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If heat generating portions are disposed more downstream than the top portion of the ridge portion, then image quality is enhanced and thermal head speed is improved, but the first corner portion is formed on the top portion of the ridge portion which is subject to maximum pressing force, causing printing residue to adhere thereto

Engineering Contradiction:

Improvethermal head speedVSAvoidprinting residue adhesion

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The electrode is designed with different regions having different functions: the first corner portion (upstream) has a smaller width to reduce residue adhesion, while the second corner portion (downstream) has a larger width to maintain image quality. This local differentiation resolves the contradiction by optimizing each region's geometry for its specific functional requirement.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The electrode structure employs asymmetric design where the first corner portion and second corner portion have different widths. This asymmetry allows the upstream region to minimize pressing force exposure while the downstream region maintains contact for quality printing, thus resolving the technical contradiction between speed and residue adhesion.

Inventive Principle:

Principle #4Asymmetry

2Device complexity

If the first corner portion is formed on the top portion of the ridge portion, then electrode configuration is simplified, but the top portion is subject to maximum pressing force from platen roller leading to residue accumulation

Engineering Contradiction:

Improveelectrode configurationVSAvoidresidue accumulation

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The electrode width varies locally along its length, with the first corner portion having a smaller width than the second corner portion. This local quality differentiation reduces residue adhesion at the upstream region while maintaining reliable contact at the downstream region, resolving the contradiction between configuration simplicity and reliability.

Inventive Principle:

Principle #3Local quality

3Temperature

If heat generating portions are positioned downstream of the ridge portion, then heat distribution is improved, but the inclination angle of the first corner portion must be controlled to prevent residue adhesion

Engineering Contradiction:

Improveheat distributionVSAvoidpressing force on first corner portion

Core Design Contradiction:

TemperatureVSObject-affected harmful factors

Solution Approach 1:

The electrode width parameter is changed along its length, with the first corner portion having a smaller width than the second corner portion. This parameter variation reduces the pressing force effect at the upstream region while maintaining heat distribution quality at the downstream region, resolving the contradiction between temperature control and harmful factors.

Inventive Principle:

Principle #35Parameter changes

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 reduces the possibility of printing residue adhering to the thermal head, enhancing operational efficiency and reducing residue accumulation, while maintaining precise electrode patterns and uniform heat distribution.

Implementation Method 1

a plurality of heat generating portions disposed on the ridge portion

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentUS9676205B2Thermal head and thermal printer

Publication Date: 2017.06.13 KYOCERA CORP

AI summary

A thermal head includes: a substrate; a thermal storage layer disposed on the substrate and having a ridge portion; heat generating portions disposed on the ridge portion; and electrodes which are disposed on the substrate. At least one of the electrodes has a first corner portion at which a side surface and an upper surface intersect, more upstream in the conveyance direction of the recording medium than the top portion of the ridge portion. In a cross section of the thermal head, an inclination angle of an imaginary line which connects an intersection point of an imaginary line which hangs downward from the top portion (13b1) of the ridge portion and the substrate, with the first corner portion, is 75° or less from the substrate. Thus, printing residue is less likely to adhere to the thermal head.