LED Projector With Collector Arrays for Lambertian Light Loss
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Solution Overview
Problem
Projectors using LEDs as image sources face inefficiencies due to Lambertian emission, leading to light loss and resolution constraints, especially when generating full-color images.
Innovation Solution
An array of LEDs with different colors is used, each coupled with a collector structure to reduce light emission angles, and a projector unit collimates the light, allowing for spatial or angular displacement to form full-color frames without losing resolution, using mechanisms like movable arrays or adjustable optical elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If LEDs are used as light source, then the projector size can be reduced, but light emission efficiency deteriorates due to Lambertian emission pattern
Solution Approach 1:
The patent introduces an optical element (microlens array or light pipe array) as an intermediary between the LED array and the image generation system. This intermediary captures the wide-angle Lambertian emission from each LED and redirects it into a more directional beam, thereby improving light collection efficiency without requiring larger projector dimensions.
2Illumination intensity
If multiple LEDs of different colours are used to generate full colour image, then image quality improves, but system complexity increases due to multiple collector structures required
Solution Approach 1:
The patent combines multiple colour LEDs (red, green, blue) into single elements where each element contains at least three LEDs of different colours. This merging approach allows full-color image generation while reducing the total number of collector structures needed, as each collector can serve multiple colour LEDs within its element.
Solution Approach 2:
Each collector structure is designed to be multi-functional by collecting light from multiple LEDs of different colours within a single element. This universal collector design reduces the overall number of collectors required in the system while maintaining the capability to generate full-color images.
3Loss of energy
If collector structures are used to reduce light emission angles, then light collection efficiency improves, but projector size increases
Solution Approach 1:
The patent employs thin-film optical elements such as microlens arrays or light pipe arrays that can be integrated closely with the LED structure. These thin-film components effectively redirect light from wide-angle emission to more directional beams without adding significant volume to the projector, thus improving light collection efficiency while maintaining compact dimensions.
4Measurement precision
If spatial movement of element arrays is used to form full colour frames, then image resolution is maintained, but device complexity increases
Solution Approach 1:
The patent utilizes dynamic spatial movement or angular displacement of element arrays relative to collector structures to sequentially illuminate different colour LEDs. This dynamic approach allows full-color frame generation while maintaining image resolution, as the movement enables each collector to access multiple colour LEDs within its element over time.
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 enhances light collection efficiency, maintains image resolution, and allows for compact projector designs suitable for pico-projectors and wearable devices.
Implementation Method 1
an array of collector structures, each collector structure configured to receive light from a single LED at any one time and reduce the angle over which the LED emits light
Implementation Method 2
a projector unit configured to receive the light from the array of collector structures and collimate the light such that a frame is formed
Implementation Method 3
LEDs are Lambertian emitters and so emit light over a wide range of angles
Data Source
AI summary
A projector for generating a frame of an image is disclosed, comprising an array of elements arranged in a plane, each element comprising at least three LEDs which have different respective colours, and an array of collector structures, each configured to receive light from a single LED at any one time and reduce the angle over which the LED emits light. A projector unit is configured to receive the light from the array of collector structures and collimate the light such that a full colour frame is formed from combining a plurality of subframes formed through a spatial movement of the array of elements with respect to the array of collector structures such that each collector structure receives light from a different LED during each subframe, and/or a displacement of the light emitted from each LED such that the light from each LED illuminates multiple pixels of the frame.