Beam Width Expander for Retinal Scanning Displays
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Solution Overview
Problem
Retinal scanning display devices experience uneven brightness due to changes in the direction of the eyeball, leading to occluded portions and varying light intensities reaching the retina, which are not effectively addressed by existing beam width expanders.
Innovation Solution
A retinal scanning display device with a beam width expander that includes a pair of reflection faces and partially reflective layers with transmittances exceeding 50%, stacked along a direction, and light-transmissive layers, which expands the beam width to ensure consistent light distribution and prevent uneven brightness when the eyeball moves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the beam width of the light beam is expanded using a conventional beam width expander with partially reflective layers having transmittance of 50% or less, then the beam width is expanded to prevent occluded portions when the pupil position changes, but uneven brightness is generated in the image when the eyeball moves due to different light intensity distributions
Solution Approach 1:
The patent changes the transmittance parameter of the partially reflective layers from 50% or less to more than 50%. This parameter change fundamentally alters the light intensity distribution within the beam width expander, enabling uniform brightness across the expanded beam width while still achieving the desired beam width expansion to prevent occluded portions when the pupil position changes.
2Adaptability or versatility
If the light beam is made incident on the eye from different angular directions by changing the incident angle to the beam width expander, then the scanning function is achieved, but the amount of light reaching the retina changes when the eyeball moves, causing uneven brightness
Solution Approach 1:
By changing the transmittance parameter of the partially reflective layers to more than 50%, the patent achieves uniform light intensity distribution that remains consistent across different incident angles. This allows the scanning function to operate effectively while maintaining constant brightness levels even when the eyeball moves and the light beam enters from different angular directions.
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 ensures that the light rays reaching the retina remain consistent in intensity and distribution, preventing uneven brightness and occluded portions, even when the eyeball moves, thereby maintaining image clarity and consistency.
Implementation Method 1
alternately stacked partially reflective layers 11 and light-transmissive layers 12 disposed between a pair of reflection faces 13, 14
Implementation Method 2
plural first light-transmissive layers 12A disposed so as to be interposed between each of the pair of first reflection faces 13A, 14A and an adjacent first partially reflective layer 11A
Data Source
AI summary
In a retinal scanning display device, a scanning section scans a light beam emitted from a light source to form a scanned image. The light beam emitted from the scanning section is expanded in beam width of the light beam in a first direction by a first beam width expander. The first beam width expander includes alternately stacked first partially reflective layers and first light-transmissive layers disposed between a pair of first reflection faces that face each other in the first direction. The plural partially reflective layers include a partially reflective layer having a transmittance exceeding 50%. This enables the light intensity distribution to be appropriately adjusted in the first direction for a light beam expanded in the first direction.