Projection Substrate Waveguide Luminance Uniformity
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Solution Overview
Problem
Conventional eyeglass-type devices and head-mounted displays face challenges in maintaining consistent luminance of projected images due to complex optical systems and limited space, leading to variations in image brightness.
Innovation Solution
A projection substrate with a simple configuration, comprising a transparent substrate, a diffraction grating formed on the substrate, and a reflective layer, which guides projection light from an incident region to an emission region, ensuring consistent luminance by reflecting the light effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a complex optical system is used to maintain consistent luminance, then image brightness uniformity is improved, but device complexity increases
Solution Approach 1:
The patent extracts and eliminates complex optical systems (lenses, mirrors, prisms) from the display device, retaining only the essential waveguide structure. By removing unnecessary optical components, the design achieves luminance uniformity through the waveguide's inherent light guidance properties rather than through complex optical correction mechanisms.
Solution Approach 2:
The waveguide structure serves multiple functions simultaneously: it guides light from the light source, distributes it uniformly across the display region, and provides the optical path for image projection. This multi-functionality eliminates the need for separate optical components that would otherwise be required to achieve luminance uniformity.
2Device complexity
If a simple optical system is used to reduce device complexity, then device complexity is reduced, but luminance uniformity deteriorates
Solution Approach 1:
The waveguide structure incorporates local variations in refractive index and geometric cross-section along its length and across its width. These local quality variations enable the simple waveguide structure to control light distribution and achieve uniform luminance without requiring complex optical systems.
Solution Approach 2:
The patent utilizes changes in the waveguide's physical parameters (refractive index, cross-sectional dimensions, wall thickness) to control light propagation and achieve uniform luminance distribution. By optimizing these parameters, the simple waveguide structure achieves the same luminance uniformity as complex optical systems.
3Volume of moving object
If limited space is utilized for eyeglass-type devices, then device miniaturization is improved, but optical system complexity increases
Solution Approach 1:
The patent merges the light guidance function and the display function into a single integrated waveguide structure. By combining these functions, the design eliminates the need for separate optical components, achieving both device miniaturization and functional integration without increasing complexity.
Solution Approach 2:
The waveguide structure is designed to be integrated within the limited space of eyeglass-type devices, with the light source, waveguide, and display region arranged in a compact nested configuration. This nesting approach maximizes space utilization while maintaining a simple optical system.
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 reduced variation in luminance of the projection image, providing a consistent and stable image quality to the user without the need for complex optical systems.
Implementation Method 1
a diffraction grating that is formed of resin on the transparent substrate and guides the projection light that has passed through the transparent substrate to the emission region
Implementation Method 2
a reflective layer that is formed on a surface of the diffraction grating, on a side opposite the transparent substrate, and reflects the projection light
Data Source
AI summary
A projection substrate having an incident region into which a projection light enters, the projection substrate including: a transparent substrate that transmits light that entered from a first surface to a second surface opposite to the first surface and transmits the projection light that projects an image on the second surface; a diffraction grating that is formed on the transparent substrate and guides the projection light to an emission region; and a reflective layer that reflects the projection light on the opposite side of the diffraction grating.