Vertically Stacked RGB LED Backlight for VR Headset Illumination
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Solution Overview
Problem
Edge-lit backlights for liquid crystal displays (LCDs) using a single layer of white LEDs have limited color gamut and brightness, making them less suitable for head-mounted displays (HMDs) which require improved illumination.
Innovation Solution
A liquid crystal display (LCD) device with a backlight featuring vertically stacked LEDs of different colors (e.g., red, green, and blue) that emit light at specific wavelengths, combined using a light guide to enhance color gamut and brightness, and packaged to reduce hotspots by arranging LEDs along the edges of the LCD panel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single layer of white LEDs is used in the backlight, then the device complexity is reduced, but the color gamut and brightness are limited
Solution Approach 1:
The patent transitions from a single-layer LED arrangement to a multi-layer stacked LED configuration. By stacking multiple LED layers vertically, the system increases the effective light emission area and improves color gamut without significantly increasing the horizontal footprint, thus resolving the contradiction between device complexity and illumination quality.
Solution Approach 2:
The patent employs a composite backlight structure combining multiple LED types (white LEDs and color LEDs) in stacked layers. This composite approach allows the system to leverage the high brightness of white LEDs while adding the color gamut benefits of color LEDs, achieving superior overall performance without requiring a complete redesign of the backlight system.
2Illumination intensity
If vertically stacked LEDs are used to improve color gamut and brightness, then the illumination quality is enhanced, but the device thickness increases
Solution Approach 1:
The patent implements a nested multi-layer LED structure where multiple LED layers are vertically stacked within a compact footprint. Each LED layer is positioned directly above or below the other, creating a space-efficient configuration that improves illumination quality without requiring proportional increases in overall device thickness.
Solution Approach 2:
The patent utilizes the vertical dimension (z-axis) to arrange multiple LED layers, effectively distributing the light emission function across three dimensions rather than expanding horizontally. This dimensional transition allows the system to achieve enhanced brightness and color gamut while maintaining a relatively compact overall thickness through optimized layer spacing and integration.
3Stability of the object's composition
If LEDs are arranged along edges to reduce hotspots, then the uniformity of illumination is improved, but the light distribution path becomes more complex
Solution Approach 1:
The patent positions LED arrays along the edge regions of the display panel, utilizing the peripheral dimension for light source placement. This edge-mounted configuration, combined with light guide structures, distributes light across the display surface through optical pathways, achieving uniform illumination while keeping the LED components located at the boundaries rather than scattered across the entire surface.
Solution Approach 2:
The patent introduces light guide structures as intermediary elements between the edge-mounted LED arrays and the display surface. These light guides act as mediators that collect light from the LEDs positioned along the edges and distribute it uniformly across the display area, reducing hotspots while managing the complexity of light distribution through dedicated optical components.
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 provides a wider color gamut and increased brightness for the LCD panel, reducing hotspots and improving uniformity, which is particularly beneficial for head-mounted displays by enhancing the overall illumination quality.
Implementation Method 1
The plurality of LEDs include at least a first color LED and a second color LED emitting first light and second light at a first direction, respectively, at a first wavelength and a second wavelength, respectively
Implementation Method 2
The light guide is configured to combine the first light and the second light received from the plurality of LEDs into combined light to illuminate the LCD panel, and direct the combined light to the pixels of the LCD panel in a second direction
Data Source
AI summary
A liquid crystal display (LCD) device including a backlight with vertically stacked light emitting diodes (LEDs). The LCD device includes an LCD panel and a backlight for illuminating the LCD panel. The backlight includes a plurality of LEDs and a light guide. The plurality of LEDs are stacked vertically and disposed behind the LCD panel along one or more edges of the LCD panel. The plurality of LEDs include at least a first color LED and a second color LED emitting first light and second light at a first direction, respectively, at a first wavelength and a second wavelength, respectively. The light guide is disposed behind the LCD panel and adjacent to the plurality of LEDs. The light guide is configured to combine the first light and the second light received from the plurality of LEDs into combined light to illuminate the LCD panel.