Stimulated Emission OLEDs for Narrow-Angle Light Delivery
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Solution Overview
Problem
Conventional OLEDs used in head-mounted displays suffer from low light throughput due to their area light emission properties, emitting light over a wide range of angles, which results in significant light loss and inefficiency, particularly in applications where imagery is overlaid on ambient views, leading to issues with balancing display brightness and ambient light.
Innovation Solution
The use of stimulated emission OLEDs and chiral band-edge emission enhanced OLEDs (C-OLEDs) that emit light in a narrow cone of angles, reducing light loss by ensuring nearly all emitted light passes through the optical system, and the integration of optical components like lenses and polarizing beam splitters to enhance light delivery and reduce parts count.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional OLEDs are used as area light emitters, then they provide wide viewing angles and uniform light distribution, but most light strikes cavity walls and is lost, resulting in low light throughput
Solution Approach 1:
The patent changes the emission parameter of the OLED from wide-angle area emission to narrow-angle point-source emission. By using stimulated emission OLEDs, the light emission angle is changed from broad (conventional OLEDs emit over wide angles) to narrow (stimulated emission OLEDs emit in a narrow cone), fundamentally altering how light propagates through the optical assembly and reduces wall strikes.
Solution Approach 2:
The patent uses stimulated emission OLEDs that replicate the light emission characteristics of laser sources - narrow beam divergence and point-source behavior. This copying of laser-like emission properties from conventional OLEDs enables high light throughput while maintaining the benefits of OLED technology.
2Illumination intensity
If conventional OLEDs emit light over a wide range of angles, then they provide broad viewing coverage, but the amount of useful light passing through the aperture is reduced
Solution Approach 1:
The patent changes the angular distribution parameter of light emission from broad (conventional OLEDs) to narrow (stimulated emission OLEDs). This parameter change ensures that light rays are directed more precisely toward the aperture, increasing the fraction of useful light delivery without requiring complex optical redirection systems.
3Use of energy by moving object
If conventional OLEDs are used in head-mounted displays, then they offer lower power dissipation and wide operating temperature range, but they require larger optical assemblies to capture sufficient light
Solution Approach 1:
The patent changes the emission geometry parameter from area emission to point-source emission with narrow angular divergence. This enables compact optical assemblies because the light does not spread out widely before reaching the aperture, allowing head-mounted displays to maintain low power dissipation while reducing overall device volume.
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 approach significantly increases light delivery to the user's eyes with reduced power dissipation and parts count, enabling effective operation in various ambient lighting conditions and improving energy efficiency in head-mounted and head-up displays.
Implementation Method 1
organic light emitting diodes that emit by stimulated emission
Implementation Method 2
chiral band-edge emission enhanced OLEDs (C-OLEDs) that emit light in a narrow cone of angles
Implementation Method 3
integration of optical components like lenses and polarizing beam splitters to enhance light delivery
Implementation Method 4
polarizing beam splitters to enhance light delivery
Data Source
AI summary
Disclosed herein are head-mounted and other display assemblies that utilize organic light emitting diodes as image sources. In the organic light emitting diodes utilized in these display assemblies light is emitted by stimulated emission. As a results of this, the organic light emitting diodes utilized emit light vertically within a narrow cone about axes normal to the planes of the organic light emitting diodes. This narrow cone of emission results in greatly reduced light insertion losses when light transits from the organic light emitting diodes through the display assemblies and as a result increased energy efficiency in the operation of the display assemblies.