Dual Light Guide Plates for Wide Angle View HMDs
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Solution Overview
Problem
Head-mounted displays (HMDs) face limitations in widening the angle of view for a more immersive experience, as existing configurations with two diffraction grating members can only enlarge the display image area in one direction, failing to meet demands for broader viewing angles.
Innovation Solution
An optical device configuration featuring a first and second light guide plate with respective deflection units, including A, B, and C deflection members, which deflect and reflect light to expand the viewing angle by projecting images orthogonally onto the plates, allowing for wider image display without the limitations of single-axis expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If two diffraction grating members are used to enlarge the display image area, then the image area is expanded in one direction, but the angle of view cannot be further widened
Solution Approach 1:
The patent transitions from single-axis image area expansion to two-axis expansion by introducing a second light guide plate oriented perpendicular to the first. This dimensional change allows the display image area to be enlarged not only in the horizontal direction but also in the vertical direction, thereby widening the angle of view in multiple dimensions simultaneously.
Solution Approach 2:
The patent divides the single light guide plate into two separate light guide plates (first and second), each handling different directional expansions. The first light guide plate expands the image area in one direction while the second light guide plate expands it in a perpendicular direction, allowing independent optimization of each axis without interference.
2Area of stationary object
If multiple diffraction grating members are arranged to expand display area, then the image coverage increases, but light interference occurs
Solution Approach 1:
By orienting the second light guide plate perpendicular to the first light guide plate, the patent separates the light propagation paths into different spatial dimensions. This dimensional separation prevents light interference between the two systems while still achieving combined expansion of the display image area in both horizontal and vertical directions.
3Device complexity
If a single light guide plate is used, then the structure is simple, but the angle of view is limited
Solution Approach 1:
The patent introduces a second light guide plate oriented perpendicular to the first, adding a vertical dimension to the previously horizontal expansion system. This dimensional addition widens the angle of view in both horizontal and vertical directions while maintaining relatively simple individual structures for each light guide plate.
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 doubles the horizontal angle of view by dividing and recombining light between the deflection units on separate light guide plates, preventing light interference and enhancing the overall viewing experience.
Implementation Method 1
a first diffraction grating member that includes a reflective type volume hologram diffraction grating that diffracts and reflects the light incident on the light guide plate
Implementation Method 2
a first diffraction grating member that includes a reflective type volume hologram diffraction grating that diffracts and reflects the light incident on the light guide plate
Implementation Method 3
a light guide plate in which an incident light propagates inside by total reflection and is thereafter emitted
Data Source
AI summary
The optical device includes a first light guide plate, a first deflection unit 30 including three deflection members, a second light guide plate, and a first deflection unit including three deflection members, a part of a light emitted from the image formation device is incident on the first deflection member and emitted from the third deflection member via the light guide plate and the second deflection member, and when a propagation direction of a light deflected by the second deflection member in the first light guide plate is a first direction, and a propagation direction of a light deflected by the second deflection member in the second light guide plate is a second direction, the first direction is non-parallel to the second direction and is opposite to the second direction.