PAPI LED Light Source Aperture Plates Sharp Transition
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Solution Overview
Problem
Existing LED-based Precision Approach Path Indicator (PAPI) systems face difficulties in achieving a sharp, flat transition between red and white light sectors, which is crucial for accurate visual assistance to pilots during aircraft landing, due to the complexity of optical systems and the need for multiple LEDs to achieve sufficient luminous intensity.
Innovation Solution
A simplified PAPI configuration using a single collimating lens with arrays of red and white LEDs, a planar blade to separate the light into sectors, and optional baffles or aperture plates to control light distribution, ensuring a sharp transition between red and white light sectors, is employed. This setup includes a housing with a light source, a collimating lens, and baffles that align the light beams to maintain the required sharpness and intensity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a multiplicity of LEDs is used to achieve sufficient luminous intensity, then the light output is improved, but the transition sharpness between red and white sectors deteriorates
Solution Approach 1:
The patent divides the light source into separate red LED array and white LED array, with each array independently controlled. This segmentation allows precise control over the light emission from each color source, enabling sharp transitions while maintaining sufficient luminous intensity from each array individually.
Solution Approach 2:
The patent introduces a planar blade as an intermediary element positioned between the red and white LED arrays. This blade physically separates the light paths and creates the sharp transition line, acting as a mediator that allows both color arrays to operate at high intensity without compromising transition sharpness.
2Device complexity
If a simplified optical system is used, then the device complexity is reduced, but the transition sharpness between red and white sectors deteriorates
Solution Approach 1:
The patent extracts and removes complex optical elements such as collimator lenses, reflective surfaces, and lateral spreader lenses from the system. By eliminating these components and relying on the inherent properties of LEDs and a simple planar blade, the system achieves transition sharpness without requiring complex optical infrastructure.
Solution Approach 2:
The patent utilizes the self-collimating property of LEDs, where each LED naturally emits light in a controlled pattern without requiring external collimation. This self-service characteristic allows the system to achieve sharp transitions using only the LED arrays and a planar blade, eliminating the need for additional optical components.
3Manufacturing precision
If incandescent halogen lamps are used as light source, then the chromaticity and transition smoothness are improved, but the power consumption increases and lamp life decreases
Solution Approach 1:
The patent changes the fundamental parameter of the light source from incandescent halogen lamps to LED technology. This parameter change enables the system to achieve comparable chromaticity and transition smoothness while dramatically reducing power consumption and extending operational life, as LEDs are inherently more energy-efficient and have longer lifespans.
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 provides a clear and accurate indication of the aircraft's position relative to the glide path, enhancing aviation safety by simplifying the optical system and optimizing the transition between red and white sectors, thus aiding pilots in safe descent.
Implementation Method 1
A collimating lens of a predetermined width and height has a predetermined focal length f, and has an optic axis aligned with the axis of the light source. The collimating lens is spaced distally from the light source.
Implementation Method 2
The collimating lens is spaced distally from the light source. Also along the optic axis of the lens there are first baffle or aperture plate
Implementation Method 3
A planar blade extends from the light source to the first frame and has a proximal edge positioned between the first and second arrays of LEDs. This blade also has a distal edge extending across the aperture of the first frame so that the first frame is substantially at the focal distance f from the collimating lens. The blade divides the beam into white and red sectors
Implementation Method 4
The first frame is positioned between the light source and the collimating lens at a distance from the lens substantially equal to the lens's focal length f. The first frame has a horizontally elongated cut-out or aperture.
Data Source
AI summary
A precision approach path indicator (PAPI) employs an LED light source with first and second arrays of LEDs or other efficient light sources, disposed one above the other and emitting their respective color lights along an optic axis to a collimating lens of focal length f. First and (optional) second aperture plates positioned along the optic axis, each being a respective frame with a cut-out defining a horizontally elongated aperture for light passing along the optic axis. Intermediate aperture plate(s) can be positioned between the first and second aperture plates. The first frame is positioned between the light source and the collimating lens at the focal distance f from the lens. The optional second aperture plate is positioned at the collimating lens and covers top, bottom, and side edge portions of the lens. A planar blade extends from the light source to the first frame and has a distal edge extending across the aperture of the first aperture plate, substantially at the focus of the collimating lens, dividing the beam into white and red sectors. The intermediate aperture plate(s) can be adjusted for optimal separation. The PAPI can be considered to have an illumination portion formed of the light source(s), blade, and first frame; and an imaging portion formed of an enclosure and a lens positioned at its focal length distant from the front frame aperture and edge of the blade.