Projection Variable Focusing Lens with Telecentric Reduction

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Solution Overview

Problem

Existing projection zoom lenses face challenges in achieving high magnifying power, small size, light weight, low manufacturing cost, and effective aberration correction, particularly when power varies, due to complex lens driving mechanisms and restrictions in lens group movement.

Innovation Solution

A projection variable focusing lens with four lens groups, including a first negative refractive power group, a second positive refractive power group that moves along the optical axis for focal length variation, a third group with specific lens configurations for aberration correction, and a fourth positive refractive power group, ensuring a telecentric reduction side and simplified lens driving mechanism.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a projection zoom lens with two or more variable power lens groups is used to achieve high magnifying power and zoom function, then the magnifying power and versatility are improved, but the device complexity and manufacturing cost increase due to complicated lens driving mechanisms

Engineering Contradiction:

Improvezoom functionVSAvoidlens driving mechanism

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent extracts and removes the zoom function from the lens system, keeping only the focusing function. This eliminates the need for variable power lens groups and their complex driving mechanisms, while still achieving high magnifying power through the fixed power lens configuration with telecentric reduction side design.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of using multiple variable power lens groups to achieve zoom (conventional approach), the patent inverts the approach by using a fixed power lens system with specific group configurations (including negative and positive power groups) that achieves high magnification without requiring zoom capability. This reverses the traditional design philosophy.

Inventive Principle:

Principle #13The other way round (Inversion)

2Adaptability or versatility

If a projection zoom lens with multiple lens groups is used to achieve high magnifying power, then the magnifying power is improved, but the device size and weight increase

Engineering Contradiction:

Improvemagnifying powerVSAvoidlens weight

Core Design Contradiction:

Adaptability or versatilityVSWeight of moving object

Solution Approach 1:

The patent removes the unnecessary zoom functionality and associated heavy lens groups, retaining only the essential focusing function. This extraction of non-essential components reduces the overall lens weight while maintaining the required high magnifying power through the optimized four-group configuration.

Inventive Principle:

Principle #2Taking out (Extraction)

3Adaptability or versatility

If a projection zoom lens with multiple lens groups is used to achieve high magnifying power, then the magnifying power is improved, but the manufacturing cost increases

Engineering Contradiction:

Improvemagnifying powerVSAvoidmanufacturing cost

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent extracts and eliminates the zoom mechanism components, which are expensive to manufacture and assemble. By using a fixed power lens system with only focusing capability, the number of precision-machined components is reduced, directly lowering manufacturing costs while achieving the required high magnifying power.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of following the conventional path of adding zoom functionality to increase magnifying power (which increases cost), the patent inverts the approach by using a simplified fixed-power design that achieves high magnification through optical configuration rather than mechanical zoom, thereby reducing manufacturing cost.

Inventive Principle:

Principle #13The other way round (Inversion)

4Adaptability or versatility

If a projection zoom lens is used to achieve high magnifying power, then the magnifying power is improved, but the lens driving mechanism complexity increases

Engineering Contradiction:

Improvemagnifying powerVSAvoidlens driving mechanism

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent removes the zoom driving mechanism entirely by eliminating the zoom function. Only the focusing driving mechanism remains, which is inherently simpler. The high magnifying power is achieved through the fixed optical configuration rather than variable power mechanisms.

Inventive Principle:

Principle #2Taking out (Extraction)

5Manufacturing precision

If existing projection zoom lenses are used to correct aberrations when power varies, then some aberration correction is achieved, but the correction effectiveness is insufficient particularly when power varies

Engineering Contradiction:

Improveaberration correctionVSAvoidaberration correction effectiveness

Core Design Contradiction:

Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

The patent removes the variable power function that causes aberration issues. By using fixed power lens groups with specifically designed configurations (including the telecentric reduction side and balanced positive/negative power groups), aberration correction is achieved more effectively without the complications of power variation.

Inventive Principle:

Principle #2Taking out (Extraction)

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 enables a projection variable focusing lens that is telecentric, offers high magnifying power, small size, light weight, and low manufacturing cost, while effectively correcting aberrations and reducing the complexity of lens driving mechanisms, thus improving overall optical performance.

Implementation Method 1

When a focal length varies, the second lens group is moved in an optical axis direction

Methodology Applied

Scientific EffectLens movement for focal length variation:

Implementation Method 2

During focusing, the third lens group is moved in the optical axis direction

Methodology Applied

Scientific EffectLens movement for focusing:

Implementation Method 3

a first lens group having a negative refractive power, a second lens group having a positive refractive power, a third lens group, and a fourth lens group having a positive refractive power arranged in this order from a magnification side

Methodology Applied

Scientific EffectRefraction: Refraction

Data Source

PatentUS8199419B2Projection variable focusing lens and projection display device

Publication Date: 2012.06.12 FUJIFILM CORP

AI summary

A projection variable focusing lens and a projection display device that has a reduction side which is telecentric, a high magnifying power, a small size, a light weight, and a low manufacturing cost and is capable of correcting all aberrations occurring when power varies with good balance. A projection variable focusing lens that moves only one lens group when power varies includes a first negative lens group G1, a second positive lens group G2, a third lens group G3, and a fourth positive lens group G4 arranged in this order from a magnification side. When a focal length varies, only the second lens group G2 is moved along an optical axis X. During focusing, the third lens group G3 is moved along the optical axis X. A reduction side is substantially telecentric.