Prism Mirror Optical Unit for See-Through Display
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Solution Overview
Problem
Existing see-through type display devices face challenges in securing a region for visually recognizing externals and increasing the degree of freedom in appearance, particularly due to the restricted arrangement of optical components and the inability to install an aperture diaphragm at the intermediate pupil position.
Innovation Solution
The display device incorporates a projection lens, a prism mirror with a light incident, inner reflection, and light emission surface, a see-through mirror, and a first diaphragm that limits the passage of imaging light. The first diaphragm is arranged between the projection lens and the light incident surface or between the light emission surface of the prism mirror and the see-through mirror.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the aperture diaphragm is arranged at the intermediate pupil position within the optical element, then the imaging performance is improved, but the arrangement of optical components is restricted and the degree of freedom in appearance is reduced
Solution Approach 1:
The aperture diaphragm function is segmented into two separate locations: one between the projection lens and light incident surface, and another between the light emission surface and see-through mirror. This segmentation allows the imaging performance to be maintained while providing flexibility in optical component arrangement.
Solution Approach 2:
The prism mirror serves as an intermediary optical element that enables the aperture diaphragm to be positioned at alternative locations. By introducing the prism mirror with specific reflection surfaces, the optical path is configured such that the aperture diaphragm can effectively control imaging light without being constrained to the traditional intermediate pupil position within the optical element.
2Object-affected harmful factors
If the aperture diaphragm is arranged at the intermediate pupil position, then unnecessary light is blocked, but the position is partially within the optical element making installation difficult
Solution Approach 1:
The aperture diaphragm function is divided into two separate positions outside the optical element, making installation feasible while maintaining the light-blocking function. The first diaphragm is positioned between the projection lens and light incident surface, and the second between the light emission surface and see-through mirror, both accessible locations that avoid the installation difficulties of positioning within the optical element.
Solution Approach 2:
The aperture diaphragm is extracted from its traditional position within the optical element and relocated to external positions. This extraction solves the installation difficulty while the optical design ensures that the light control function remains effective through the combined action of the prism mirror and diaphragm arrangement.
3Reliability
If the see-through type display device uses traditional mirror arrangement, then the virtual image is formed, but the region for visually recognizing externals is restricted
Solution Approach 1:
The optical path is configured to utilize three-dimensional space more effectively. By using the prism mirror with inclined reflection surfaces and positioning components in multiple spatial dimensions, the device achieves compact arrangement that preserves external visibility region while maintaining virtual image formation capability.
Solution Approach 2:
The optical component arrangement employs asymmetric configuration rather than traditional symmetric mirror placement. The prism mirror with specific inclination angles and the strategically positioned aperture diaphragms create an asymmetric optical path that optimizes both virtual image formation and external view preservation.
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
This configuration allows for improved imaging performance by blocking unnecessary light while selectively transmitting the required imaging light, thereby enhancing the display device's ability to provide a clear virtual image while maintaining a see-through view of externals.
Implementation Method 1
a prism mirror 22 that has a light incident surface 22a on which the imaging light emitted from the projection lens 21 is incident, an inner reflection surface 22b that reflects the imaging light from the light incident surface 22a, and a light emission surface 22c that emits the imaging light from the inner reflection surface 22b
Implementation Method 2
a see-through mirror 23 that reflects the imaging light emitted from the prism mirror 22 toward a pupil position PP
Data Source
AI summary
A display device includes an image element, a prism mirror configured to cause imaging light emitted from the image element to be incident on a light incident surface, to reflect the imaging light by an inner reflection surface, and to emit the imaging light from a light emission surface, thereby emitting the imaging light so that the imaging light is returned in an inclined direction, a see-through mirror configured to reflect the imaging light emitted from the prism mirror toward a pupil position, and a basic aperture diaphragm configured to limit the passage of the imaging light incident on the light incident surface of the prism mirror.