Projector Rotor Assembly for Crack-Resistant Wavelength Conversion

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Solution Overview

Problem

The substrate in projectors can experience thermal expansion due to light irradiation, leading to stress concentration and potential cracking, especially with a central hole for fixing a rotational shaft.

Innovation Solution

A rotor unit with a fixing member that includes multiple seat surfaces and recesses to uniformly distribute heat and securely attach the substrate to the rotational shaft, preventing stress concentration and improving rotation balance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a hole is provided at the center of the substrate for fixing a rotational shaft, then the substrate can be fixed to the rotational shaft, but stress is easily concentrated by the thermal expansion and cracks are easily generated

Engineering Contradiction:
Improvefixing strengthVSAvoidcrack resistance
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The substrate is divided into a first substrate with a hole for rotational shaft fixation and a second substrate without a hole that is coupled to the first substrate. This segmentation allows the second substrate to compensate for stress concentration caused by thermal expansion around the hole, preventing crack generation while maintaining fixing strength.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The substrate system combines two substrates with different structural characteristics - one with a hole for fixation and one without a hole for stress distribution. This composite structure leverages the advantages of both designs: the first substrate enables secure rotational shaft attachment while the second substrate provides stress relief during thermal expansion.

Inventive Principle:
Principle #40Composite materials

2Temperature

If a heat sink is bonded to the substrate to prevent temperature increase, then the temperature can be controlled, but the device complexity and weight increase

Engineering Contradiction:
Improvesubstrate temperatureVSAvoidstructure complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The second substrate without a hole serves a dual function: it maintains structural integrity during thermal expansion and inherently manages heat distribution across the substrate assembly. This self-service approach eliminates the need for separate heat sink components while still achieving temperature control through the substrate's own thermal properties and stress distribution capabilities.

Inventive Principle:
Principle #25Self-service

3Weight of moving object

If the substrate material is made lighter, then the weight is reduced, but the fixing strength and heat resistance may deteriorate

Engineering Contradiction:
Improvesubstrate weightVSAvoidfixing strength
Core Design Contradiction:
Weight of moving objectVSStrength

Solution Approach 1:

By segmenting the substrate into two coupled substrates, the design achieves weight reduction through optimized material distribution. The first substrate with the hole provides necessary fixing strength for the rotational shaft, while the second substrate contributes to overall structural integrity and heat resistance without adding excessive weight, as it lacks the heavy hole structure.

Inventive Principle:
Principle #1Segmentation

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

Prevents substrate cracking by ensuring uniform heat distribution and enhancing the fixing strength and rotation balance of the rotor unit, eliminating the need for a heat sink and reducing weight.

Implementation Method 1

When the wheel 40 is mounted on the seat surfaces 25 with the adhesive material 39, even if heat is accumulated in the substrate 41, the heat can be uniformly diffused in the entire substrate material

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP3244261B1Rotating body unit, rotating body, and projector
Publication Date: 2021.12.29 SONY GROUP CORP
  • EP3244261B1 patent drawingFigure 1
  • EP3244261B1 patent drawingFigure 2
  • EP3244261B1 patent drawingFigure 3

AI summary

[Solving Means] A rotor unit includes a rotor including a substrate and a wavelength conversion region, and a driving unit. The substrate includes an outer edge and is configured such that a substrate material is continuously provided from a center to the outer edge. The wavelength conversion region is provided on the substrate and receives light having a first wavelength region and emits light having a second wavelength region different from the first wavelength region. The driving unit rotates the rotor.