AR Optical Device Light Leakage Prevention
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Solution Overview
Problem
Conventional augmented reality optical devices suffer from light leakage, compromising confidentiality, design aesthetics, and optical efficiency due to stray light leaking outside, especially when using reflective or diffractive optical elements.
Innovation Solution
The optical device incorporates a reflective unit with a size of 4 mm or less, featuring a first surface for reflecting image light and a second surface made of a light-absorbing material to prevent external light leakage, ensuring that only intended light reaches the user's pupil, with edge surfaces of the optical means also utilizing light-absorbing materials to minimize stray light reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a reflective unit smaller than the pupil is used to increase depth of field, then the focal length for augmented reality image is increased and the image remains in focus when the user changes focal length for real world, but light leakage occurs where image light leaks to the outside
Solution Approach 1:
The patent applies the principle of converting harm into benefit by treating the second surface of the reflective unit not as a simple reflective surface but as a light-absorbing surface. This converts the potentially harmful light leakage into a beneficial feature where the second surface actively absorbs stray light, preventing it from leaking outward while maintaining the pinhole effect benefits of the small reflective unit.
Solution Approach 2:
The patent applies local quality by differentiating the optical properties of the two surfaces of the reflective unit. The first surface maintains high reflectivity to direct image light to the user's pupil, while the second surface has high light absorption properties to prevent stray light leakage. This localized differentiation of optical properties resolves the contradiction between maintaining focus and preventing light leakage.
2Reliability
If conventional optical systems are used to provide augmented reality, then virtual images can be superimposed on real images, but the devices have complicated configurations resulting in considerable weight and volume
Solution Approach 1:
The patent extracts the essential function of the optical system into a single, compact reflective unit that is smaller than the human pupil. By taking out only the necessary reflective function and eliminating complex multi-element optical systems, the patent achieves augmented reality functionality with considerably reduced weight and volume while maintaining the core capability of superimposing virtual images on real-world objects.
3Reliability
If conventional optical systems are used to provide augmented reality, then virtual images can be superimposed on real images, but the manufacturing processes are complicated resulting in high manufacturing costs
Solution Approach 1:
The patent simplifies the optical system by extracting only the essential reflective function into a single reflective unit, eliminating the need for complex multi-element optical assemblies. This extraction of the core function reduces manufacturing complexity and lowers production costs while maintaining the augmented reality functionality of superimposing virtual images on real-world objects.
4Duration of action of moving object
If a reflective unit smaller than the pupil is used to achieve pinhole effect, then depth of field is increased, but optical efficiency is lowered due to light leakage to the outside
Solution Approach 1:
The patent converts the light-absorbing property of the second surface into a beneficial feature that prevents optical energy loss. By making the second surface light-absorbing, the patent transforms what would be a source of optical inefficiency (light leaking out) into a mechanism that captures and absorbs stray light, thereby maintaining optical efficiency while preserving the extended depth of field achieved through the small reflective unit design.
Solution Approach 2:
The patent applies local quality by assigning different optical properties to different surfaces of the reflective unit. The first surface is highly reflective to maintain optical efficiency for the intended path of light to the user's eye, while the second surface is highly absorptive to prevent optical energy loss from stray light. This localized optimization of optical properties resolves the contradiction between depth of field and optical efficiency.
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 effectively prevents light leakage, maintaining confidentiality, enhancing the device's appearance, and increasing optical efficiency by ensuring that only intended light is directed to the user's eye, while minimizing external reflections.
Implementation Method 1
a first surface configured to reflect the image light corresponding to an image for augmented reality, output from the image output unit, toward the pupil of the eye of the user
Implementation Method 2
a second surface which is a surface opposite to the first surface and is made of a light absorbing material that does not reflect light
Data Source
AI summary
The present invention provides an optical device for augmented reality having an external light leakage prevention function, the optical device including: an image output unit configured to output image light corresponding to an image for augmented reality; at least one reflective unit configured to transfer the image light to the pupil of an eye of a user by reflecting the image light; and an optical means configured such that the reflective unit is disposed therein and it transmits at least part of image light, output from a real object, therethrough toward the pupil; wherein the at least one reflective unit is formed to have a size of 4 mm or less, and includes a first surface configured to reflect the former image light toward the pupil and a second surface which is a surface opposite to the first surface; and wherein the second surface is made of a light absorbing material.