Light Spreading Structures for HMD Pixel Fill Factor
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Solution Overview
Problem
Head-mounted displays suffer from screen door effects due to low fill factors in pixels, which are exacerbated when images are magnified by lenses, leading to visual artifacts for users.
Innovation Solution
Enhancing the fill factor of pixels in head-mounted displays by incorporating light spreading structures such as fiber bundle layers or arrays of microlenses that laterally spread light emitted by organic light-emitting diodes, increasing the fill factor to 90% or more.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pixels are made smaller to increase resolution, then more pixels can be packed into the display panel, but the fill factor decreases causing screen door effects
Solution Approach 1:
The patent introduces a light spreading structure as an intermediate optical element between the pixel array and the user's eye. This adds a new dimensional layer to the optical path, allowing light to be redistributed laterally across the pixel surface. The light spreading structure converts the vertical light emission from pixels into lateral light distribution, effectively increasing the fill factor without changing the physical pixel dimensions or spacing.
Solution Approach 2:
The light spreading structure acts as an intermediary optical element that mediates between the pixel array and the user's eye. It receives light from the pixels and redistributes it to fill the gaps between adjacent pixels, thereby eliminating screen door effects. This intermediary structure allows the system to maintain small pixel pitch for high resolution while achieving high fill factor appearance.
2Productivity
If the pixel pitch is reduced to increase pixel density, then more pixels fit in the display panel, but the fill factor decreases leading to visual artifacts
Solution Approach 1:
By introducing the light spreading structure as an intermediate layer, the patent transforms the problem from a two-dimensional pixel layout constraint to a three-dimensional optical path solution. The light spreading structure adds vertical dimension to the optical system, allowing light to travel through an intermediate medium that redistributes it laterally, thereby achieving high pixel density without visual artifacts.
Solution Approach 2:
The light spreading structure serves as an intermediary that decouples the physical pixel pitch from the perceived light distribution. It receives light from densely packed pixels and redistributes it to create uniform illumination, eliminating visual artifacts while maintaining high pixel density for improved productivity in terms of display information capacity.
3Area of stationary object
If lenses are added to magnify images in head-mounted displays, then viewing magnification is improved, but screen door effects are intensified
Solution Approach 1:
The patent applies the light spreading structure before the light enters the lens system. By pre-spreading the light laterally across the pixel surface before magnification, the structure ensures that when the lens magnifies the image, the light distribution remains uniform and continuous. This preliminary light spreading action prevents the lens from magnifying the gaps between pixels, thereby avoiding intensification of screen door effects.
Solution Approach 2:
The light spreading structure is positioned as an intermediary between the pixel array and the lens system. It modifies the light distribution characteristics before the light enters the lens, ensuring that the magnified image maintains high fill factor. This intermediary structure allows the lens to provide image magnification while the light spreading structure simultaneously eliminates screen door effects by redistributing light laterally.
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
Minimizes screen door effects and enhances display quality by ensuring a higher percentage of the display surface area is utilized for image rendering, providing a clearer and more immersive visual experience for users.
Implementation Method 1
The light spreading structures may laterally spread light that is being emitted by the organic light-emitting diodes
Implementation Method 2
A fiber bundle layer may be formed from a layer of fibers each of which overlaps a respective one of the pixels
Implementation Method 3
An array of microlenses may be formed on the pixel array so that each microlens overlaps one, two, three, or other suitable number of organic light-emitting diodes
Data Source
AI summary
An electronic device with a display may be provided with an array of pixels each of which includes subpixels formed from organic light-emitting diodes. The electronic device may have support structures such as a head-mountable frame or other head-mountable support structure. Optical structures such as lenses may be provided through which the array of pixels is viewable by a user. The array of pixels and the lenses or other optical structures may be supported by the head-mounted support structure. Light spreading structures may overlap the array of pixels to enhance the fill factor of the pixels. The light spreading structures may be formed from a fiber bundle layer, an array of microlenses, or other optical structures that laterally spread light that has been emitted by the organic light-emitting diodes and thereby enhances the fill factor of the pixels.