Surface-Emission Laser Array Thermal Management

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Solution Overview

Problem

High-density surface-emission laser arrays face challenges in reducing the interval between laser diode elements for high-resolution and high-speed image formation, leading to thermal interference and non-uniform output, which shortens the lifetime and degrades performance.

Innovation Solution

A surface-emission laser array design with a reduced interval between diode elements in the sub-scanning direction and a larger interval in the main scanning direction, along with specific interconnection patterns, to minimize thermal interference and ensure uniform output.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the interval between laser diode elements is reduced to increase the number of beams, then productivity is improved, but thermal interference increases and output uniformity deteriorates

Engineering Contradiction:
Improvenumber of laser beamsVSAvoidoutput uniformity
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent applies local quality by differentiating the interval settings in different directions: smaller intervals in the sub-scanning direction (where more beams are needed for productivity) and larger intervals in the main scanning direction (where thermal interference is more critical). This directional differentiation allows the system to optimize both productivity and output uniformity simultaneously.

Inventive Principle:
Principle #3Local quality

2Productivity

If the number of laser beams is increased for high-speed image formation, then productivity is improved, but device complexity increases due to cooling system requirements

Engineering Contradiction:
Improveimage formation speedVSAvoidcooling system
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent changes the physical parameters of the laser diode array by using surface-emission type diodes with inherently lower power consumption (1/10th of edge-emission types), and by optimizing the spatial arrangement with directional interval differentiation. These parameter changes reduce the total heat generation and enable higher beam counts without proportionally increasing cooling system complexity.

Inventive Principle:
Principle #35Parameter changes

3Productivity

If laser diode elements are arranged in a two-dimensional array with small intervals, then productivity is improved, but thermal interference increases leading to shortened lifetime

Engineering Contradiction:
Improvewriting densityVSAvoidlaser array lifetime
Core Design Contradiction:
ProductivityVSDuration of action of stationary object

Solution Approach 1:

The patent applies asymmetry by creating an asymmetric interval pattern where the spacing between adjacent laser diode elements differs between the sub-scanning direction (smaller interval) and the main scanning direction (larger interval). This asymmetric arrangement optimizes writing density while providing thermal relief pathways that extend component lifetime.

Inventive Principle:
Principle #4Asymmetry

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 design achieves uniform output and extended lifetime of the laser array by reducing thermal interference and optimizing the spacing between diode elements, enabling high-density and high-speed image formation.

Implementation Method 1

a surface-emission laser diode is a semiconductor laser device that emits a light perpendicularly to the substrate

Methodology Applied
Scientific EffectLaser emission: Laser

Implementation Method 2

surface-emission laser diode elements (3301-3336)

Methodology Applied
Scientific EffectLight emission from semiconductor: Light Emitting Diode

Implementation Method 3

reducing thermal interference and optimizing the spacing between diode elements

Methodology Applied
Scientific EffectThermal interference: Conduction (thermal)

Data Source

PatentEP2013952B1Surface-emission laser array, optical scanning apparatus and image forming apparatus
Publication Date: 2021.02.24 RICOH CO LTD
  • EP2013952B1 patent drawingFigure 1
  • EP2013952B1 patent drawingFigure 2
  • EP2013952B1 patent drawingFigure 3

AI summary

A surface-emission laser array comprises a plurality of surface-emission laser diode elements arranged in the form of a two-dimensional array, wherein a plurality of straight lines drawn perpendicularly to a straight line extending in a first direction from respective centers of the plurality of surface emission laser diode elements aligned in a second direction perpendicular to the first direction, are formed with generally equal interval in the first direction, the plurality of surface-emission laser diode elements are aligned in the first direction with an interval set to a reference value, and wherein the number of the surface-emission laser diode elements aligned in the first direction is smaller than the number of the surface-emission laser diode elements aligned in the second direction.