Asymmetric Prism Sheet for Automotive Dashboard Backlight
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Solution Overview
Problem
Automobile dashboard display devices require a wide viewing angle in the horizontal direction to ensure visibility from both driver and passenger seats while preventing light from being projected onto the door glass, which can obstruct the sideview mirror, compromising safety.
Innovation Solution
A backlight system incorporating a prism sheet with specific geometric configurations, including a first surface with a first base and a second surface with a scalene triangular cross-section, optimized to distribute light evenly across the horizontal plane, reducing light projection onto the door glass and enhancing visibility of the sideview mirror.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the display device is configured to have a wide light distribution angle in the horizontal direction to ensure visibility from both driver and passenger seats, then the viewing angle is improved, but the light is projected onto the door glass which obstructs the sideview mirror
Solution Approach 1:
The patent applies asymmetry by configuring the prism sheet with different prism patterns on its first and second surfaces. The first surface has prisms with a first pitch L1, while the second surface has prisms with a different pitch L2 where L2/L1 is between 0.5 and 0.7. This asymmetric configuration creates an asymmetric light distribution pattern that directs light away from the door glass while maintaining wide horizontal viewing angles for the display.
Solution Approach 2:
The patent implements local quality by creating different light distribution characteristics in different spatial directions. The asymmetric prism configuration produces a light distribution that is wide in the horizontal direction (good for viewing) but controlled in the direction toward the door glass (preventing projection). This allows the same optical component to provide different light distribution qualities for different viewing directions.
2Adaptability or versatility
If the display device is disposed at the center of the dashboard to be seen from both driver's seat and passenger's seat, then the accessibility is improved, but the light distribution causes projection onto the door glass
Solution Approach 1:
The asymmetric prism configuration with different pitches on opposite surfaces creates a directional light distribution that maintains wide horizontal viewing angles for multi-seat visibility while preventing light from projecting onto the door glass. The asymmetry allows the centrally disposed display to serve multiple viewers without creating harmful projections.
Solution Approach 2:
The optical design provides different light distribution qualities in different directions: wide angular distribution horizontally for multi-seat viewing, and restricted distribution toward the door glass area. This local differentiation of light properties enables the display to be centrally positioned for accessibility while avoiding projection issues.
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 optimized light distribution ensures that the display is visible from both driver and passenger seats without projecting onto the door glass, thereby improving driver safety by maintaining visibility of critical components like the sideview mirror.
Implementation Method 1
a prism sheet disposed opposite to the LEDs... a first prism having a first base and a first pitch L1 is formed on the first surface, a second prism having a cross section that is scalene triangular in shape having a second base having a length L2
Data Source
AI summary
In a backlight that includes a plurality of LEDs and a prism sheet disposed opposite to the LEDs, the prism sheet has a first surface opposite to the LEDs and a second surface on the opposite side of the first surface, a first prism having a first base and a first pitch L1 is formed on the first surface, a second prism having a cross section that is scalene triangular in shape having a second base having a length L2, a first base angle θ1, and a second base angle θ2 smaller than the first base angle is formed on the second surface, and L2<L1.