Projector Optical Layout With Reduced Mirror Air Gap

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

The existing projection optical systems face challenges in minimizing the size due to the need for a large air gap between mirrors to prevent interference, leading to increased system dimensions.

Innovation Solution

The optical system incorporates a first optical element with a concave reflecting surface and a second optical element with powered transmission surfaces, allowing for a reduced air gap and enabling compact design while maintaining image quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a large air gap is ensured between the first mirror and the second mirror to prevent physical interference, then the mirrors can be positioned to avoid interference, but the projection optical system grows in size

Engineering Contradiction:

Improveprevention of physical interference between mirrorsVSAvoidsize of projection optical system

Core Design Contradiction:

ReliabilityVSLength of stationary object

Solution Approach 1:

The patent applies curved surfaces (concave first mirror, convex second mirror) to enable the mirrors to be positioned closer together. The curvature allows the light beams to be properly directed and focused without requiring a large air gap, thus reducing the overall system size while maintaining functional separation between the mirrors

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The patent changes the geometric parameters of the mirrors (curvature radius, surface shape) to optimize the optical path. By adjusting these parameters, the system achieves compact dimensions while ensuring that the mirrors do not physically interfere with each other during operation

Inventive Principle:

Principle #35Parameter changes

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 allows for a more compact optical system with improved aberration correction and reduced interference, achieving high resolution and suppressed spot variation.

Implementation Method 1

The first optical element has a first reflecting surface having a concave shape

Methodology Applied

Scientific EffectReflection: Reflection

Implementation Method 2

At least one of the first transmission surface, the second reflecting surface, and the second transmission surface has power

Methodology Applied

Scientific EffectRefraction: Refraction

Data Source

PatentUS12547062B2Optical system and projector

Publication Date: 2026.02.10 SEIKO EPSON CORP

AI summary

An optical system includes a first optical element, and a second optical element arranged at a reduction side of the first optical element. The first optical element has a first reflecting surface having a concave shape. The second optical element has a first transmission surface, a second reflecting surface arranged at the reduction side of the first transmission surface, and a second transmission surface arranged at the reduction side of the second reflecting surface. A first optical axis of the first reflecting surface is parallel to a second optical axis of the first transmission surface. At least one of the first transmission surface, the second reflecting surface, and the second transmission surface has power.