Virtual Image Display Apparatus Light Flux Intersection Shift
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Solution Overview
Problem
Existing virtual image display apparatuses face issues such as continuous visibility of video images when the wearer temporarily avoids them, and difficulty in achieving a see-through configuration due to large and heavy optical systems, which affect the user's line of sight control and image recognition range.
Innovation Solution
A virtual image display apparatus that adjusts light flux diameter and focus position to change the image light display range according to the user's line of sight, allowing only specific video images to be visible by shifting the intersection point of light flux components from the iris position towards the retina, and using a see-through configuration with a diffraction optical element to superimpose virtual images on outside light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a diffraction optical element is disposed in the optical path to adjust light fluxes, then the angle of divergence of light flux in a specific direction is increased for reduction in light loss, but the portion of the apparatus in front of the eye becomes large and heavy
Solution Approach 1:
The patent changes the optical parameters by shifting the intersection point of principal rays from the iris position toward the retina position. This parameter change allows the light fluxes to be properly directed without requiring additional diffraction optical elements, thereby reducing apparatus weight while maintaining efficient light delivery to the retina
2Loss of energy
If a diffraction optical element is disposed in the optical path, then light flux adjustment is improved, but it becomes difficult to achieve a see-through configuration that allows image light to be superimposed on outside light
Solution Approach 1:
By shifting the intersection point of principal rays toward the retina, the patent achieves proper light flux direction without blocking the optical path with additional optical elements. This allows outside light to pass through to the retina while image light is properly directed, enabling a see-through configuration where virtual images are superimposed on the external view
3Duration of action of moving object
If video images are always tracked and provided according to eye motion, then continuous video observation is enabled, but video images remain visible even when the wearer temporarily averts the eyes, which may bother the user
Solution Approach 1:
The patent shifts the intersection point of principal rays from the iris position toward the retina position. This creates a conditional viewing system where image light only reaches the retina when the user's line of sight is properly aligned with the apparatus. When the user averts their eyes, the light fluxes no longer intersect at the correct position and images become invisible, giving the user control over when to view video content
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
Enables the user to recognize video images only when looking in the intended direction, removing unnecessary images from view and allowing for efficient image introduction and see-through observation without increasing the apparatus size or weight.
Implementation Method 1
adjusts light flux diameter and focus position to change the image light display range according to the user's line of sight
Implementation Method 2
a diffraction optical element is disposed in the optical path to adjust light fluxes in such a way that the angle of divergence of a light flux in a specific direction is greater than those of light fluxes in the other directions
Data Source
AI summary
Image light is formed of light flux components having a diameter of, e.g., 3 mm or smaller. The image light is then caused to be incident on the iris of an eye to form an image in the form of a virtual image. The position where the principal rays of the light flux components that form the image light intersect one another is set to be a position shifted from the position of the iris of the eye toward the retina. The range of the light flux components that reach the retina can thus be changed in accordance with the motion of the eye. As a result, in accordance with a change in the line of sight that occurs when a wearer moves the line of sight in a specific direction, the image light can be so controlled that only image light components in the specific direction reach the retina of the eye.