Stepped Collimator Light Guide for Stray-Light-Free Backlighting
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Solution Overview
Problem
Existing light guide designs for display devices in vehicles face inefficiencies in light deflection, leading to unwanted stray light and limited display area due to the need for larger apertures, especially in compact designs.
Innovation Solution
A light guide with a collimator featuring a stepped structure and collimating contours that modifies light angles to prevent stray light, ensuring homogeneous backlighting without the need for baffles, allowing for compact and efficient light distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a curved deflection surface is used to increase deflection efficiency, then deflection efficiency is improved, but the length of the curved area increases, requiring a larger aperture to block stray light
Solution Approach 1:
The collimator is divided into multiple segments (first collimator segment, second collimator segment, third collimator segment) with different functions. The first segment collimates light, the second segment deflects collimated light at 45 degrees, and the third segment handles uncollimated light. This segmentation allows each segment to be optimized for its specific function, achieving high deflection efficiency while maintaining a compact overall structure that minimizes the aperture width needed for stray light blocking.
Solution Approach 2:
Different regions of the light guide are given different optical properties. The deflection area has a light deflection surface at 45 degrees specifically for deflecting collimated light, while other areas have structures optimized for their local functions (such as the light-guiding area with parallel top surface and inclined bottom surface). This local optimization allows high deflection efficiency in the deflection area without requiring a large aperture, as each local region performs its specific function efficiently.
2Manufacturing precision
If the light guide length is increased to achieve homogeneous backlighting, then backlighting homogeneity is improved, but the device size increases
Solution Approach 1:
The invention changes the optical parameters of light propagation by introducing a collimator that creates collimated light. This fundamental parameter change (from divergent to collimated light) allows the light to travel longer distances without significant spreading, enabling homogeneous backlighting over longer light guide lengths without proportionally increasing the device size. The collimated light maintains its directional properties, allowing efficient light distribution over extended areas.
Solution Approach 2:
The invention transitions from planar light propagation to three-dimensional light control by introducing a light-guiding area with a parallel top surface and an inclined bottom surface. This dimensional change creates a volumetric light-guiding path that allows collimated light to propagate efficiently over longer distances while maintaining compact cross-sectional dimensions, achieving homogeneous backlighting without excessive device size increase.
3Device complexity
If a planar deflection surface is used, then the design is simpler, but deflection efficiency is reduced due to increased stray light
Solution Approach 1:
The deflection function is segmented into specific regions: the second collimator segment provides the light deflection surface at 45 degrees for deflecting collimated light, while the third collimator segment handles uncollimated light. This segmentation allows the deflection surface to be optimized for its specific function (achieving high deflection efficiency) while other segments handle stray light management, maintaining overall design simplicity despite the enhanced functionality.
4Object-affected harmful factors
If the aperture is enlarged to block stray light from compact deflection designs, then stray light control is improved, but the display area is reduced
Solution Approach 1:
The invention converts potentially harmful uncollimated light (which would become stray light) into a useful resource by introducing the third collimator segment. This segment is specifically designed to receive and redirect uncollimated light that missed the collimation process, deflecting it at appropriate angles to contribute to the backlighting. This converts what would be waste light into useful illumination, eliminating the need for large apertures to block stray light while maximizing the usable display area.
Solution Approach 2:
The third collimator segment acts as an intermediary between the light source and the display area, specifically handling uncollimated light. It mediates the light path by deflecting uncollimated light at appropriate angles, preventing it from becoming harmful stray light while still contributing to the overall backlighting. This intermediary structure allows compact design without sacrificing stray light control or display area.
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 achieves uniform, borderless backlighting by minimizing stray light and optimizing light utilization, enabling efficient illumination even in small spaces with minimal light loss.
Implementation Method 1
the collimator converts the coupled light into collimated light by means of a collimating contour
Implementation Method 2
The light propagates through the light guide by total internal reflection and is then coupled out again with the help of microstructures on the light guide
Implementation Method 3
the light guide has a light-guiding area for guiding the collimated light along an axis, wherein the light-guiding area has a top surface that is configured parallel to the axis and a bottom surface that is inclined relative to the axis and has a structure for deflecting the collimated light incident on the bottom surface as deflected light towards the top surface
Data Source
Figure 1a~1c
Figure 2
Figure 3
AI summary
The present invention relates to an optical fiber (400) for a display device (100) with a display panel (200). The optical fiber (400) has a coupling area (420) with a collimator (421), wherein the collimator (421) has a groove (425) with a coupling surface (426) for coupling light (301) from a light source (300). The collimator (421) converts the coupled light (301) into collimated light (310) by means of a collimating contour. The light guide (400) has a light guide area (460) for guiding the collimated light (310) along an axis (480), wherein the light guide area (460) has a top surface (461) which is designed parallel to the axis (480) and a bottom surface (462) which is inclined relative to the axis (480) and a structure (463) for deflecting the collimated light (310) incident on the bottom surface (462) as deflected light (311) in the direction of the top surface (461).The deflected light (311) is coupled out of the light guide (400) at the top (461) of the light guide area (460). The light guide (400) has a deflection area (470) with a light deflection surface (471) for deflecting the collimated light (310) into the light guide area (460), the light deflection surface (471) being arranged at an angle (α1) of 45° to the orientation of the collimated light (310) and to the axis (480) of the light guide area (460). The collimator (421) has a step (431-434).