Thermal Print Head Convex Substrate for Roller Interference

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Solution Overview

Problem

Existing thermal print heads face challenges in achieving enhanced printing quality while preventing interference from platen rollers, especially during miniaturization, due to the design of the substrate and heat generating portions.

Innovation Solution

A thermal print head with a substrate made of semiconductor material featuring a convex portion with inclined surfaces, a resistor layer with heat generating portions, and a wiring layer, designed to minimize interference by optimizing the angle and surface roughness of the convex portion, allowing for efficient heat dissipation and smooth contact with recording media.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a convex portion with inclined surfaces is added to the substrate to enhance printing quality, then printing quality is improved, but device complexity increases

Engineering Contradiction:

Improveprinting qualityVSAvoidsubstrate structure

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The convex portion is segmented into multiple inclined surfaces (first inclined surface, second inclined surface, third inclined surface, fourth inclined surface) with different tilt angles, allowing each surface to serve a specific function in guiding and pressing the recording medium while maintaining manufacturing precision

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the convex portion have different local qualities through varying inclination angles - the first and second inclined surfaces have steeper angles for primary contact and pressing, while the third and fourth inclined surfaces have gentler angles for guidance and smooth transitions, optimizing printing quality at each location

Inventive Principle:

Principle #3Local quality

2Volume of moving object

If the thermal print head is miniaturized to reduce size, then device size is reduced, but interference from platen roller increases

Engineering Contradiction:

Improvethermal print head sizeVSAvoidplaten roller interference

Core Design Contradiction:

Volume of moving objectVSObject-affected harmful factors

Solution Approach 1:

The convex portion extends in the thickness direction (z-direction) from the main surface of the substrate, creating a vertical dimension that elevates the heat generating portions above the platen roller interference zone, allowing miniaturization in planar dimensions while maintaining clearance from the platen roller through vertical positioning

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Object-affected harmful factors

If the inclined surfaces have steep tilt angles to prevent platen roller interference, then interference prevention is improved, but manufacturing difficulty increases

Engineering Contradiction:

Improveplaten roller interferenceVSAvoidconvex portion fabrication

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The steep inclination is segmented into multiple surfaces with different angles rather than a single steep surface, distributing the manufacturing complexity across multiple manageable surfaces while achieving the overall steep profile needed to prevent platen roller interference

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different inclination angles are used for different surfaces (first and second inclined surfaces have steeper angles, third and fourth have gentler angles), optimizing both interference prevention and manufacturability by varying the geometric parameters across different regions

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

The solution achieves enhanced printing quality and prevents interference from platen rollers, ensuring reliable operation and reduced risk of damage to the recording medium, while maintaining high heat conductivity and cost-effectiveness.

Implementation Method 1

a resistor layer, including a plurality of heat generating portions arranged in the main scanning direction and located on the convex portion

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 2

the substrate includes a semiconductor material... advantages of higher heat conductivity

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS11850870B2Thermal print head and manufacturing method thereof

Publication Date: 2023.12.26 ROHM CO LTD

AI summary

The present disclosure provides a thermal print head. The thermal print head includes a substrate having a main surface and a convex portion and including a semiconductor material; a resistor layer including a plurality of heat generating portions located on the convex portion; and a wiring layer conducted to the plurality of heat generating portions and formed to contact the resistor layer. The convex portion has a top surface, a first inclined surface and a second inclined surface. The first inclined surface and the second inclined surface are disposed between the main surface and the top surface, separated from each other in a sub-scanning direction, and tilted with respect to the main surface. A first tilted angle of the first inclined surface with respect to the main surface and a second tilted angle of the second inclined surface with respect to the main surface are greater than 55 degrees.