Polygon Mirror Laser Scanning Layout for Wide Electrical Steel Sheets

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Solution Overview

Problem

Conventional laser scanning devices for electrical steel sheets require multiple units to cover the wide sheet width, leading to increased equipment size and cost due to power reflection losses at the polygon mirror's corners, making it difficult to arrange them compactly without gaps or overlaps.

Innovation Solution

A laser scanning device with a polygon mirror that rotates parallel to the sheet surface, using an optical system with a plane mirror and focusing mirror to guide the laser beam, allowing for compact arrangement by reducing the width occupied by each device and increasing the effective scanning length.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the diameter of the polygon mirror is increased to reduce power reflection loss, then the scanning width is improved, but the width occupied by the laser scanning device increases

Engineering Contradiction:

Improvepower reflection lossVSAvoidwidth occupied by device

Core Design Contradiction:

Loss of energyVSArea of stationary object

Solution Approach 1:

The patent changes the orientation of the polygon mirror from a conventional configuration where the rotation axis is perpendicular to the scanning direction to a configuration where the rotation axis is parallel to the scanning direction. This dimensional reorientation allows the laser beam to scan a wider area without requiring a larger mirror diameter, thereby reducing the width occupied by the device while maintaining scanning performance.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent modifies the rotational orientation parameter of the polygon mirror, changing it from a conventional perpendicular arrangement to a parallel arrangement with the scanning direction. This parameter change enables the system to achieve the same scanning width with a smaller mirror diameter, reducing both power reflection loss and device width.

Inventive Principle:

Principle #35Parameter changes

2Area of stationary object

If multiple laser irradiation devices are arranged to cover the sheet width, then the scanning coverage is improved, but the equipment size increases

Engineering Contradiction:

Improvescanning coverageVSAvoidequipment size

Core Design Contradiction:

Area of stationary objectVSVolume of stationary object

Solution Approach 1:

By reorienting the polygon mirror rotation axis to be parallel to the scanning direction, the patent enables a single device to achieve wider scanning coverage that would otherwise require multiple devices arranged side by side. This dimensional change reduces the number of devices needed and consequently reduces the overall equipment size and volume.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Device complexity

If the rotation axis of the polygon mirror is orthogonal to the laser scanning direction, then the scanning mechanism is simplified, but the device width increases

Engineering Contradiction:

Improvescanning mechanism complexityVSAvoiddevice width

Core Design Contradiction:

Device complexityVSArea of stationary object

Solution Approach 1:

The patent inverts the conventional orientation of the polygon mirror rotation axis from being perpendicular to the scanning direction to being parallel to it. This inversion resolves the contradiction by achieving compact device width while maintaining an equally simple scanning mechanism through the reversed configuration.

Inventive Principle:

Principle #13The other way round (Inversion)

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 enables compact, cost-effective arrangement of laser scanning devices along the sheet width, reducing the number of devices needed and minimizing equipment size while maintaining effective scanning performance.

Implementation Method 1

a polygon mirror which has a polygonal shape including a top surface and a bottom surface that are polygonal, in which at least any one surface excluding the top surface and the bottom surface is formed as a mirror, which rotates about an axis serving as a rotation axis and penetrating the top surface and the bottom surface, and which causes the laser beam irradiated from the laser beam output unit to be reflected at the mirror

Methodology Applied

Scientific EffectReflection: Reflection

Data Source

PatentUS20240139869A1Laser scanning device, laser scanning method, laser processing device, and electrical steel sheet manufacturing method

Publication Date: 2024.05.02 NIPPON STEEL CORPORATION

AI summary

Provided is a laser scanning device that scans a surface of an electrical steel sheet with a laser beam, and includes: a laser beam output unit which irradiates the laser beam; a polygon mirror which has a polygonal shape including a top surface and a bottom surface that are polygonal, in which at least any one surface excluding the top surface and the bottom surface is formed as a mirror, which rotates about an axis serving as a rotation axis and penetrating the top surface and the bottom surface, and which causes the laser beam irradiated from the laser beam output unit to be reflected at the mirror; and an optical system which guides the laser beam reflected at the polygon mirror to the surface of an electrical steel sheet, the rotation axis of the polygon mirror being parallel to the surface of the electrical steel sheet and substantially parallel to a direction in which the laser beam is scanned.