Retro Total Reflecting Telecentric Pico Projector Optical Engine

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Solution Overview

Problem

Pico projector apparatuses face challenges in balancing volume size and optical engine efficiency, as existing designs either result in insufficient brightness or increased size when attempting to enhance brightness by combining multiple light source modules with dichroic combiners.

Innovation Solution

A retro total reflecting type telecentric optical configuration is employed, utilizing a prism set with specific intersecting angles and a dual LED light path configuration, including a dichroic combiner, light beam homogenization, and an illumination lens set to achieve conjugate imaging and reduce volume while increasing brightness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If multiple light source modules with dichroic combiner are used to enhance brightness, then brightness is improved, but volume size increases

Engineering Contradiction:

ImprovebrightnessVSAvoidvolume size

Core Design Contradiction:

Illumination intensityVSVolume of stationary object

Solution Approach 1:

The patent combines multiple light source modules (first and second light source modules) with different wavelengths into a single integrated light source assembly that shares common optical paths. The dichroic combiner merges the light from multiple sources while maintaining compact configuration, resolving the contradiction between brightness enhancement and volume reduction.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent employs a folded optical path configuration where light travels through multiple dimensions (upward, lateral, downward directions) using prism sets and mirrors. This three-dimensional light path arrangement allows multiple light sources to be integrated without proportionally increasing the device footprint, effectively decoupling brightness from volume.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Volume of stationary object

If single light path design is used to reduce size, then volume size is reduced, but brightness becomes insufficient

Engineering Contradiction:

Improvevolume sizeVSAvoidbrightness

Core Design Contradiction:

Volume of stationary objectVSIllumination intensity

Solution Approach 1:

The patent divides the optical system into separate light paths for different wavelength ranges (first light path for longer wavelengths, second light path for shorter wavelengths) while maintaining an integrated structure. This segmentation allows each light source to be optimized for its specific wavelength while contributing to overall brightness, resolving the contradiction between compact size and sufficient brightness.

Inventive Principle:

Principle #1Segmentation

3Productivity

If specific angle of incidence is used for reflection-type image generator, then optical engine efficiency is improved, but volume size increases

Engineering Contradiction:

Improveoptical engine efficiencyVSAvoidvolume size

Core Design Contradiction:

ProductivityVSVolume of stationary object

Solution Approach 1:

The patent employs asymmetric prism angles (first prism with 45-degree angle, second prism with 30-degree angle) to optimize the light path geometry. These specific asymmetric angles enable the reflection-type image generator to achieve optimal incidence angles for high optical efficiency while the folded path configuration keeps the overall volume compact, resolving the contradiction between efficiency and size.

Inventive Principle:

Principle #4Asymmetry

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 smaller-sized pico projector with higher optical engine efficiency and achieves conjugate imaging, effectively addressing the trade-off between size and brightness.

Implementation Method 1

a dichroic combiner, a light beam homogenization means, an illumination lens set

Methodology Applied

Scientific EffectDichroic combination: Dichroic Filter

Implementation Method 2

retro total reflecting type telecentric optical configuration

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Data Source

PatentUS8696137B2Pico projector apparatus of retro total reflecting type telecentric optical configuration

Publication Date: 2014.04.15 QISDA CORP

AI summary

A high efficiency projector apparatus comprising an illumination lens set including a first illumination lens and a second illumination lens, and the image is imaged conjugatedly on the image projection lens set, when light traveling distance between the first illumination lens of focal distance f1 and the second illumination lens of focal distance f2 is “d”, light source module produces first multiple virtual light sources on output side of light beam homogenization means, first multiple virtual light sources are located within f1 producing virtual image of second multiple virtual light sources on same side as the first multiple virtual light sources, the second multiple virtual light sources are distanced from the second illumination lens by value of D, the D value has value according to (f2<D<2f2), such that the second multiple virtual light sources are substantially conjugatedly imaged on the image projection lens set.