Light Source Unit with Diffusing and Dichroic Layers

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Solution Overview

Problem

Conventional projectors using solid light emitting devices for light sources face issues such as potential burning of luminescent material layers and uneven luminance in projected images due to direct exposure of blue laser light and directional light emission, which affects the longevity and image quality.

Innovation Solution

A light source unit comprising a first solid light emitting device as an excitation source, a second luminescent material layer, and an optical device with a dichroic layer that transmits light from the first source and reflects light from the second source, along with a diffusing layer that diffuses light from the first source, ensuring even light distribution and protecting the luminescent material layer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If light from the first solid light emitting device is directed directly onto the luminescent material layer, then the light intensity is sufficient for excitation, but the luminescent material layer may burn and its service life decreases

Engineering Contradiction:

Improvelight intensityVSAvoidservice life of luminescent material layer

Core Design Contradiction:

Illumination intensityVSReliability

Solution Approach 1:

A diffusing plate is introduced as an intermediary component between the first solid light emitting device and the luminescent material layer. This diffusing plate scatters the directed light into a broader distribution, reducing the peak intensity that could cause burning while maintaining sufficient overall excitation intensity. The diffusing plate acts as a mediator that transforms concentrated light into distributed light, protecting the luminescent material layer while preserving excitation effectiveness.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Loss of energy

If light from the solid light emitting device is directed directly onto the display device, then the light transmission efficiency is high, but uneven luminance is generated in the projected image

Engineering Contradiction:

Improvelight transmission efficiencyVSAvoiduniformity of luminance

Core Design Contradiction:

Loss of energyVSManufacturing precision

Solution Approach 1:

The diffusing plate serves as an intermediary that receives directed light from the solid light emitting device and transforms it into diffused light. This diffusion process creates more uniform illumination across the display device, eliminating uneven luminance patterns in the projected image while maintaining high light transmission efficiency through the optical system.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Measurement precision

If a dichroic mirror is used to separate wavelengths, then the color separation is precise, but the device complexity increases

Engineering Contradiction:

Improvewavelength separation precisionVSAvoidoptical system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent combines the diffusing function and wavelength separation function into a single integrated optical device. The diffusing plate is positioned to work in conjunction with the dichroic mirror, creating a unified optical path that achieves both light diffusion and precise wavelength separation without requiring separate complex assemblies. This merging reduces overall device complexity while maintaining functional precision.

Inventive Principle:

Principle #5Merging (Combining)

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 effectively diffuses light from the excitation source onto the luminescent material layer, preventing burning and enhancing image quality by reducing uneven luminance, while allowing for flexible layout and extended lifespan of the luminescent material, and reduces the risk of image distortion.

Implementation Method 1

an optical device which has a diffusing layer which diffuses a pencil of light emitted from the first light source

Methodology Applied

Scientific EffectLight diffusion: Scattering

Implementation Method 2

a dichroic layer which transmits a pencil of light emitted from the first light source and reflects a pencil of light emitted from the second light source

Methodology Applied

Scientific EffectDichroic filtering: Dichroic Filter

Implementation Method 3

a second light source having a luminescent material layer which emits light in a wavelength range which is different from light in a wavelength range emitted from the first light source by using the first light source as an excitation light source

Methodology Applied

Scientific EffectLuminescence: Luminescence

Data Source

PatentUS9817304B2Light source unit having optical device having diffusing layer and dichroic layer, projector, optical device, and optical device manufacturing method

Publication Date: 2017.11.14 CASIO COMPUTER CO LTD

AI summary

There is provided a light source unit comprising a first light source having a solid light emitting device, a second light source having a luminescent material layer which emits light in a wavelength range which is different from light in a wavelength range which is emitted from the first light source by using the light emitted from the first light source as an excitation light source, and an optical device which is disposed between the first light source and the second light source, wherein the optical device has a dichroic layer which transmits a pencil of light emitted by the first light source and reflects a pencil of light emitted by the second light source, and a diffusing layer which diffuses the pencil of light emitted from the first light source.