Fresnel Lens Optical Engine for DLP Projection
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Solution Overview
Problem
Conventional DLP projection apparatuses with Non-Telecentric optical engines suffer from mechanical interference and stray light due to the use of aspheric lenses, leading to poor imaging quality and reduced luminance.
Innovation Solution
The implementation of a Fresnel lens with a reduced thickness and a receiving portion to replace the aspheric lens, which mitigates stray light and mechanical interference by reducing the surface area of the receiving portion, thereby improving imaging quality and reducing material costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If an aspheric lens is used to focus light in a Non-Telecentric optical engine, then the structure can be simplified, but mechanical interference occurs between the aspheric lens and the lens assembly due to the small angle between illumination and imaging sections
Solution Approach 1:
The patent introduces a receiving portion that extends in the depth dimension (along the optical axis) to accommodate the lens assembly. This dimensional extension allows the aspheric lens to maintain its focusing function while creating sufficient spatial separation to avoid mechanical interference with the lens assembly, thus resolving the contradiction between structure simplification and mechanical interference.
2Object-generated harmful factors
If the aspheric lens is cut off to form a depression for receiving the lens assembly, then mechanical interference is avoided, but the surface area of the aspheric lens is reduced causing total reflection and stray light
Solution Approach 1:
The patent converts the potentially harmful stray light generated at the depression interface into a beneficial effect by strategically positioning the reflective mirror to redirect this light back through the aspheric lens. The mirror transforms what would be wasted stray light into useful illumination, maintaining imaging quality while preserving the mechanical clearance provided by the depression.
3Volume of stationary object
If the surface area of the aspheric lens is reduced to avoid mechanical interference, then space is saved, but luminance performance deteriorates due to decreased light utilization efficiency
Solution Approach 1:
The patent introduces a reflective mirror as an intermediary element that mediates between the space constraints and luminance requirements. The mirror captures light that would otherwise be lost due to the reduced lens surface area and redirects it through the aspheric lens, effectively increasing light utilization efficiency while maintaining the compact space configuration.
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 Fresnel lens effectively reduces stray light and mechanical interference, enhancing imaging quality without compromising brightness, while also minimizing the use of lens materials and space, thus optimizing the optical engine's performance and cost-effectiveness.
Implementation Method 1
a light ray is focused onto the light valve and then reflected by the reflective surface into the lens assembly for imaging
Implementation Method 2
The Fresnel lens is formed with a receiving portion adapted to correspondingly receive at least one portion of the lens assembly
Implementation Method 3
a light ray is focused onto the light valve and then reflected by the reflective surface into the lens assembly for imaging
Data Source
AI summary
An imaging system and an optical engine comprising the imaging system are provided. The imaging system in this invention at least comprises a lens assembly, a light valve, and a Fresnel lens. The Fresnel lens is formed with a receiving portion adapted to correspondingly receive at least one portion of the lens assembly and replaces the conventional aspheric lens to focus a light ray onto the light valve. The light valve reflects the light ray into the lens assembly for imaging. Thereby, the Fresnel lens is adapted to decrease the surface area of the receiving portion to eliminate the influence of stray light on the imaging quality and to economize lens material costs.