Optical Guide for Vehicle Lighting with Inclined Exit Face
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Solution Overview
Problem
Traditional motor vehicle lighting and signaling systems face challenges in achieving homogeneous light emission from a surface source with sufficient luminance, while maintaining design flexibility and aesthetics, due to limitations in OLED technology such as low luminance and shape constraints imposed by protective glass.
Innovation Solution
A motor vehicle optical system that allows the exit face to be freely inclined and oriented, using a surface light source with high directivity OLEDs and an optical guide to maximize light intensity in a preferred direction, enabling flexible shaping and increased luminance, while maintaining homogeneity across the exit face.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If conventional OLEDs are used to create a surface light source, then the emission surface area is increased, but the luminance becomes insufficient for signaling applications
Solution Approach 1:
The patent changes the optical parameters of the OLED by introducing a microcavity structure with specific thickness (d) that creates optical resonance. This resonance effect modifies the emission characteristics, directing light preferentially in the normal direction and significantly increasing luminance in that direction while maintaining the surface area advantage of OLEDs.
Solution Approach 2:
The OLED structure is segmented into multiple functional layers (electrodes, transport layers, emitting layer, microcavity layers) that work together to achieve both surface area coverage and high luminance. The microcavity is itself segmented into specific thickness zones that create the resonance effect.
2Reliability
If protective glass slides are added to OLEDs to protect from water and oxygen, then reliability is improved, but shape flexibility and design freedom are severely limited
Solution Approach 1:
The patent replaces rigid glass slides with flexible thin film encapsulation layers that provide protection from water and oxygen while allowing the OLED to achieve various shapes including curved and uneven surfaces. This thin film approach maintains reliability without the shape constraints of glass.
3Illumination intensity
If the OLED emission direction is made highly directional (non-Lambertian) to improve luminance, then luminance in the preferred direction is increased, but the exit face orientation is constrained to be normal to the OLED plane
Solution Approach 1:
The patent introduces an optical element as an intermediary between the OLED and the exit face. This optical element decouples the OLED plane from the exit face orientation, allowing the exit face to be inclined or curved relative to the OLED while maintaining the preferred emission direction through optical redirection.
4Shape
If flexible substrate OLEDs are used to escape flatness constraints, then shape freedom is improved, but luminance remains relatively low and insufficient for photometric functions
Solution Approach 1:
The patent applies the microcavity resonance structure to flexible substrate OLEDs, changing the optical parameters to achieve high luminance. The specific thickness parameters of the microcavity layers are optimized to create resonance that directs light in the normal direction with high intensity, enabling flexible OLEDs to achieve luminance levels suitable for signaling applications.
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 system achieves high luminance of at least 5000 Cd/m² in the preferred optical direction, providing enhanced visibility and aesthetics with a homogeneous light distribution, allowing for various lighting and signaling functions without shape or orientation constraints.
Implementation Method 1
The guide is configured so that light emitted by the surface light source enters the guide through the input face and escapes from the guide through the output face
Implementation Method 2
The guide may include a reflective face oriented to reflect light toward the output face
Implementation Method 3
All of these layers constitute a microcavity whose thickness is adjusted to create optical resonance. The result of such a structure is the emission of a beam of light having a high directivity
Implementation Method 4
modified OLEDs have been proposed to greatly increase the emission directivity of the OLED
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
The present invention relates to an optical system for a motor vehicle, in particular a signaling and/or lighting device, which is designed to emit light the intensity of which is at a maximum in a given preferred optical direction (20), and which comprises: a surface light source (30) having a front wall emitting light the intensity of which is at a maximum in a main emitting direction (31), an optical guide (1) including a input surface (2) and an output surface (3) at least partially forming an outer surface of the system, the system being designed such that the light enters into the guide via the input surface (2) and escapes via the output surface (3), the optical guide (1) being shaped such that the intensity of the light at the output of the system is at a maximum in the preferred optical direction (20).