Dual Focus Structure for Projector Lens Group Adjustment

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Solution Overview

Problem

Projector systems face challenges in correcting trapezoidal distortion and curvature of field when projecting images at extremely close distances, leading to blurs in the center and periphery of the display, which existing focusing methods cannot adequately address.

Innovation Solution

The implementation of a projector system comprising a refractive optical system with multiple lens groups and a mirror train, featuring a first focus structure that moves lens groups differently along the image display element's normal line for floating focusing, and a second focus structure that adjusts the position of these groups to correct distortions and blurs across the entire image.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a single focus structure is used to adjust the projector system, then the structure remains simple, but it cannot simultaneously correct blurs in the center and periphery of the display

Engineering Contradiction:

Improvefocus uniformityVSAvoidfocusing structure

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The focusing structure is divided into two independent focus adjustment mechanisms: a first focus structure that moves lens groups for floating focusing to correct periphery blurs, and a second focus structure that adjusts the position of the light bulb relative to the lens groups to correct center blurs. This segmentation allows each structure to specialize in correcting different types of focus issues without interfering with each other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system employs dynamic focus adjustment where lens groups can be moved independently by the first focus structure during operation to adapt to different projection distances and correct curvature of field, while the second focus structure provides additional dynamic adjustment capability for center focus issues.

Inventive Principle:

Principle #15Dynamics

2Adaptability or versatility

If the distance between the refractive optical system and the light bulb varies, then the projector can adapt to different projection conditions, but focus uniformity across the display deteriorates

Engineering Contradiction:

Improveprojection distance adaptationVSAvoidfocus uniformity

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The first focus structure enables dynamic movement of lens groups along the optical axis in response to changes in projection distance, implementing floating focusing that maintains focus uniformity across the display regardless of the distance between the refractive optical system and the light bulb.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The separation of focus adjustment functions between two independent structures allows the first focus structure to handle distance adaptation through lens group movement while the second focus structure maintains center focus, ensuring focus uniformity is preserved across varying projection conditions.

Inventive Principle:

Principle #1Segmentation

3Adaptability or versatility

If different focal lengths are used to adjust image size, then the projector becomes more versatile, but uniform focus across the entire display area deteriorates

Engineering Contradiction:

Improveimage size adjustmentVSAvoidfocus uniformity

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The two-focus structure separates the responsibilities: the first focus structure handles floating focusing for uniform focus maintenance when focal length changes, while the second focus structure corrects center focus issues, allowing versatile image size adjustment without sacrificing focus uniformity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system changes the position parameter of lens groups through the first focus structure to maintain focus uniformity when focal length parameters are adjusted, rather than relying solely on focal length changes for image size adjustment.

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 effectively corrects blurs and distortions in the projected image, ensuring uniform focus and image quality across the entire display area, even when the distance between the refractive optical system and the light bulb varies or when different focal lengths are used.

Implementation Method 1

a refractive optical system including a plurality of lens groups

Methodology Applied

Scientific EffectRefraction: Refraction

Implementation Method 2

a mirror train including a curved mirror

Methodology Applied

Scientific EffectReflection: Reflection

Data Source

PatentUS10451961B2Focus adjustment system for an image display device

Publication Date: 2019.10.22 RICOH CO LTD

AI summary

An image display device includes an image display element, a light source, an illumination system, a projector system comprising a refractive optical system including a plurality of lens groups, and a mirror train including a curved mirror, a first focus structure configured to move the respective lens groups of the refractive optical system by different amounts along a normal line of the image display element, and a second focus structure configured to move the respective lens groups along the normal line of the image display element by different amounts from those of the first focus structure.