Triangular Prism Backlight Unit for Compact Head-Up Displays
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Solution Overview
Problem
Backlight units for head-up display devices are typically large due to the presence of multiple optical members like lenses and mirrors, necessitating a reduction in device size while maintaining optical functionality.
Innovation Solution
A backlight unit with a housing containing a light source and an optical member with a triangular prism shape made of translucent material, featuring curved entrance, exit, and reflecting walls that adjust the beam width of light beams, allowing for a compact design by integrating multiple optical functions into a single component.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple optical members (lenses and mirrors) are used to direct light beams, then the optical functionality is maintained, but the device size becomes larger
Solution Approach 1:
The patent combines multiple optical functions (light reception, total internal reflection, and light emission) into a single optical member with a triangular prism shape. This merging of functions eliminates the need for separate lenses and mirrors, thereby reducing the overall device size while maintaining the required optical functionality for directing light beams from the light source to the liquid crystal display device
Solution Approach 2:
The optical member is designed as a multi-functional component that simultaneously performs multiple optical tasks: receiving light from the light source through the entrance wall, reflecting light internally through the reflecting wall using total internal reflection, and emitting light through the exit wall toward the display device. This multi-functionality allows a single component to replace what would traditionally require multiple separate optical elements
2Ease of manufacture
If the optical member uses flat surfaces, then the manufacturing is simpler, but the beam width control capability is reduced
Solution Approach 1:
The patent incorporates curved surfaces on the entrance wall, exit wall, and/or reflecting wall of the triangular prism optical member. These curved surfaces provide optical properties that enable control over the beam width of light beams passing through or reflecting off the surfaces. The curvature allows for focusing or diverging effects that flat surfaces cannot achieve, thereby enhancing beam width control capability while still maintaining a relatively simple prism-based structure
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 compact design achieves a smaller device size while maintaining the necessary optical properties to effectively direct light beams to the liquid crystal display device, enhancing the overall efficiency and miniaturization of the head-up display system.
Implementation Method 1
still another side wall serving as a reflecting wall that reflects the light beams that have been incident on the entrance wall to the exit wall inside the prism portion
Implementation Method 2
at least one side wall among the entrance wall, the exit wall, and the reflecting wall has a curved surface shape having an optical property that changes a degree of increase or decrease in a beam width of light beams passing through the one side wall
Data Source
AI summary
A backlight unit includes a housing having an opening in which an liquid crystal display device is disposed, a light source disposed inside the housing, and an optical member disposed inside the housing, turning a path of light from the light source toward the liquid crystal display device, and having a triangular prism portion made of a translucent material. The prism portion has one side wall serving as an entrance wall on which the light from the light source is incident, another side wall as an exit wall emitting light to the liquid crystal display device, and still another side wall as a reflecting wall reflecting the light incident on the entrance wall to the exit wall inside the prism portion.