Projector Illumination Device Angular Distribution Control

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Solution Overview

Problem

Existing light source devices for projectors, which irradiate a phosphor layer with laser light to produce fluorescence, face issues with color unevenness due to differences in light distribution between fluorescence and diffused light, and using a high diffusing power diffusion layer reduces light use efficiency.

Innovation Solution

An illumination device with a diffusion element that receives beam bundles at different angles, expanding the angular distribution of intensity from the center to the periphery, reducing backscattering, and achieving a gentler angular distribution without enhancing diffusion characteristics, thereby aligning light distributions and improving light use efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a diffusion layer with high diffusing power is used to expand the light distribution of diffused light, then the light distribution is expanded to align with fluorescence, but backscattering increases and light use efficiency is reduced

Engineering Contradiction:

Improvelight distributionVSAvoidlight use efficiency

Core Design Contradiction:

Illumination intensityVSLoss of energy

Solution Approach 1:

The invention changes the angular distribution parameter of the incident beam bundle by making the angular distribution of intensity have a low value at the center and high values at the periphery. This parameter change allows the diffusion element to expand the angular distribution of emitted light without requiring high diffusing power, thereby reducing backscattering and maintaining light use efficiency while still achieving alignment with fluorescence light distribution

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

Instead of enhancing the diffusion characteristics of the diffusion element to expand light distribution, the invention inverts the approach by controlling the incident beam's angular distribution to have low intensity at the center and high intensity at the periphery. This inverse approach achieves the same goal of expanding emitted light distribution while avoiding the drawbacks of high diffusing power

Inventive Principle:

Principle #13The other way round (Inversion)

2Reliability

If the light distribution of diffused light is expanded to align with fluorescence, then color unevenness is reduced, but a diffusion layer with high diffusing power causes much backscattering and difficulty in formation

Engineering Contradiction:

Improvecolor unevennessVSAvoiddiffusion layer formation

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The invention changes the angular distribution parameter of the incident beam to have low intensity at the center and high intensity at the periphery. This parameter modification allows the diffusion element to produce gentler angular distribution in the emitted beam, achieving color uniformity without requiring difficult-to-form high diffusing power diffusion layers

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

Rather than making the diffusion layer have high diffusing power to achieve color uniformity, the invention inverts the approach by controlling the incident beam's angular distribution characteristics. This makes the system easier to manufacture while still achieving the goal of aligning light distributions to eliminate color unevenness

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

The solution effectively reduces color unevenness and enhances display quality by aligning light distributions, while maintaining high light use efficiency, achieving diffusion close to Lambert diffusion.

Implementation Method 1

a diffusion element 12 and a light source device 9 that emits a beam bundle including a first unit beam bundle (LA) to be incident on the diffusion element along a first direction and a second unit beam bundle (LB) to be incident on the diffusion element along a second direction

Methodology Applied

Scientific EffectDiffusion: Diffusion

Implementation Method 2

light source devices that irradiate a phosphor layer with laser light as excitation light to produce fluorescence at a wavelength different from the excitation light

Methodology Applied

Scientific EffectFluorescence: Fluorescence

Data Source

PatentUS9860497B2Illumination device and projector

Publication Date: 2018.01.02 SEIKO EPSON CORP

AI summary

An illumination device includes a diffusion element and a light source device that emits a beam bundle including a first unit beam bundle to be incident on the diffusion element along a first direction and a second unit beam bundle to be incident on the diffusion element along a second direction. An angle formed by the first unit beam bundle with an optical axis of the beam bundle is greater than an angle formed by the second unit beam bundle with the optical axis, and the illumination device satisfies I2<I1 where I1 is a luminous flux of the first unit beam bundle, and I2 is a luminous flux of the second unit beam bundle.