Compact Display Module with Intersecting Optical Axes
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Solution Overview
Problem
Existing head-mounted display apparatuses require numerous optical members to compensate for wavelength dispersion, leading to a large size due to the need for specific positional relationships between optical elements.
Innovation Solution
A display module configuration that includes an image light generation device, a first reflection section, a first diffraction element, a second reflection section, and a second diffraction element, where the optical axes intersect and reflection regions overlap, allowing for compact design by folding optical paths and reducing the size of the display device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple optical members are arranged to satisfy specific positional relationships for wavelength compensation, then wavelength dispersion is compensated, but the device size becomes large
Solution Approach 1:
The patent combines multiple optical functions (diffraction, reflection, wavelength compensation) into an integrated optical system where the first and second diffraction elements work together with reflection surfaces in a compact arrangement. The optical axes intersecting and reflection regions overlapping allows these functions to be merged in space, achieving wavelength compensation without requiring separate large-scale optical paths for each function.
Solution Approach 2:
The patent utilizes three-dimensional spatial arrangement by having optical axes intersect and reflection regions overlap in different spatial dimensions. This allows the optical path to be folded back on itself, enabling wavelength compensation functionality to be achieved in a compact volume by exploiting the third dimension rather than requiring linear extension of optical components.
2Volume of moving object
If optical paths are folded to reduce device size, then device compactness is improved, but optical alignment precision becomes more difficult to maintain
Solution Approach 1:
The patent employs asymmetric optical path folding where the first and second diffraction elements are positioned at specific asymmetric angles relative to each other, with their optical axes intersecting at a defined point. This asymmetric arrangement, combined with overlapping reflection regions, creates a geometrically constrained system where alignment tolerances are naturally reduced, making the folded optical path more robust to manufacturing variations.
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 compact design of the display module achieves effective wavelength compensation and reduces the size of the display device while maintaining image quality, making it more wearable and aesthetically pleasing.
Implementation Method 1
a first diffraction element including a first incident surface and configured to diffract and deflect the image light emitted from the first reflection section and entering through the first incident surface
Implementation Method 2
a second diffraction element including a second incident surface and configured to diffract and deflect the image light emitted from the second reflection section and entering through the second incident surface, thereby forming an exit pupil
Implementation Method 3
a first reflection section configured to reflect the image light emitted from the image light generation device
Implementation Method 4
a second reflection section configured to reflect the image light emitted from the first diffraction element
Data Source
AI summary
A display module includes an image light generation device configured to generate image light, a first reflection section configured to reflect the image light from the image light generation device, a first diffraction element configured to diffract the image light entering a first incident surface, a second reflection section configured to reflect the image light from the first diffraction element, and a second diffraction element configured to diffract the image light entering a second incident surface, thereby forming an exit pupil. When viewed from a normal line direction of a virtual plane including a normal line of the first incident surface and a normal line of the second incident surface, an optical axis of the image light from the image light generation device toward the first reflection section and an optical axis of the image light from the first diffraction element toward the second reflection section intersect each other.