Microlens Array Asymmetry for Virtual Image Projection Luminance
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Solution Overview
Problem
Virtual image projection devices using microlens arrays suffer from luminance unevenness due to periodic intensity distribution reflections, which are not adequately addressed in existing technologies.
Innovation Solution
A virtual image projection device is designed with a microlens array where the short side directions of lens cells are not aligned straight, and the aspect ratio of the lens cells is adjusted to match the light emitting region shape of the light source, reducing luminance unevenness by minimizing dark regions and enhancing light use efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If Koehler irradiation using a microlens array is adopted to obtain high luminance, then luminance is improved, but luminance unevenness occurs due to periodic intensity distribution reflection
Solution Approach 1:
The microlens array employs an asymmetric arrangement where odd-numbered and even-numbered lens cells are offset relative to each other in the short side direction. This asymmetric configuration prevents the periodic reflection of intensity distribution that causes luminance unevenness, while preserving the high luminance benefit of Koehler irradiation.
Solution Approach 2:
Different lens cells in the microlens array are positioned with different offsets in the short side direction. Specifically, odd-numbered lens cells have one offset pattern while even-numbered lens cells have a different offset pattern, creating local variations that collectively eliminate the periodic intensity distribution reflection across the entire array.
2Use of energy by moving object
If the aspect ratio of lens cells is matched to the light emitting region shape, then light use efficiency is improved, but manufacturing complexity increases
Solution Approach 1:
The invention specifies particular aspect ratio ranges for the lens cells (1.0 to 1.6) that match common light emitting region shapes. By defining these parameter ranges, the patent optimizes light use efficiency while providing clear manufacturing specifications that balance performance with manufacturability.
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 effectively reduces luminance unevenness and improves light use efficiency by staggering the short side directions of lens cells and matching the aspect ratios of the light source and lens cells, resulting in a more uniform image projection.
Implementation Method 1
a microlens array that emits the light, which is emitted from the light source, as light having a predetermined angle distribution
Implementation Method 2
an imaging lens that concentrates the light from the microlens array
Data Source
AI summary
A virtual image projection device that generates image light includes a light source that emits light; a microlens array that emits the light, which is emitted from the light source, as light having a predetermined angle distribution; an imaging lens that concentrates the light from the microlens array; a display unit that is irradiated with the light, which is concentrated by the imaging lens, to generate an image; and a projection unit that projects the image, which is generated by the display unit, as image light. The microlens array is disposed such that short side directions of lens cells do not line up straight.