Prism Assembly Curved Surface Back Focal Length Reduction

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Solution Overview

Problem

Conventional projection display systems with single reflective light valves have a long back focal length, resulting in a large volume for the projection lens, which complicates the system and increases size and production costs.

Innovation Solution

A projection display device is designed with a collimating means installed between the reflective light valve and the prism assembly, featuring optical curved surfaces on the light emitting and incident surfaces of the prism assembly, which reduces the back focal length and simplifies the image formation and illumination devices by replacing traditional lens functions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If a single reflective light valve is used in a projection display system, then the system becomes more compact and suitable for presentation use, but the back focal length becomes too long and the projection lens volume becomes too large

Engineering Contradiction:

Improvesystem sizeVSAvoidback focal length

Core Design Contradiction:

Volume of moving objectVSLength of stationary object

Solution Approach 1:

The patent applies curved optical surfaces (spheroidality principle) by configuring the light emitting surface of the prism assembly as an optical curved surface. This curvature enables the prism assembly to perform both beam combining and optical focusing functions, effectively reducing the back focal length while maintaining compact system dimensions suitable for presentation use.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The patent merges multiple optical functions into the prism assembly by configuring its light emitting surface as an optical curved surface. This allows the prism assembly to simultaneously perform beam combining and optical focusing that would traditionally require separate lenses, thereby reducing the overall system size and back focal length.

Inventive Principle:

Principle #5Merging (Combining)

2Adaptability or versatility

If a prism assembly is installed between the light valve and projection lens, then the system can function with a single reflective light valve, but the back focal length increases and requires a larger projection lens

Engineering Contradiction:

Improvesingle light valve operationVSAvoidprojection lens volume

Core Design Contradiction:

Adaptability or versatilityVSVolume of stationary object

Solution Approach 1:

The patent combines multiple optical functions into the prism assembly by configuring its light emitting surface as an optical curved surface. This integration allows the prism assembly to simultaneously perform beam combining and optical focusing, eliminating the need for additional lenses and reducing the projection lens volume.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The prism assembly is designed with multi-functionality by configuring its light emitting surface as an optical curved surface, enabling it to perform both beam combining and optical focusing functions that would traditionally require separate dedicated optical components.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If traditional lens systems are used for image formation and illumination, then the optical functions are well-established, but the system becomes complex and the back focal length becomes too long

Engineering Contradiction:

Improveoptical function stabilityVSAvoidoptical system complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges multiple traditional lens functions into the prism assembly by configuring its light emitting surface as an optical curved surface. This integration maintains reliable optical performance while reducing system complexity by eliminating separate lens components for beam combining and focusing.

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

This configuration shortens the back focal length, reduces the size of the projection lens, and lowers production costs while simplifying the optical system, making it more compact and efficient.

Implementation Method 1

The light source 11 provides an illumination beam incident into the prism 12, and the beam is then projected on the light valve 13 by means of total reflection.

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 2

A projection display device according to the present invention comprises an illumination device, a light valve and a projection lens with a prism assembly and an image formation set

Methodology Applied

Scientific EffectCollimation: Lens

Data Source

PatentUS7350928B2Projection display system

Publication Date: 2008.04.01 YOUNG OPTICS

AI summary

A projection display system comprises an illumination device, a prism assembly, a projection lens and a reflective light valve. The prism assembly has a first light incident surface, a first light emitting surface and a second light emitting surface. The first light emitting surface is an optical curved surface. An illumination beam is incident on the light valve after it enters the prism assembly from the first light incident surface. A modulated beam is generated after it is processed through the light valve. Finally, the modulated beam is projected into the projection lens through the prism assembly. Because a surface of the prism assembly is set to be an optical curved surface to replace a lens in the projection lens or the illumination device, a back focal length of the system is shortened and the projection lens or the illumination device is simplified.