Active Display Alignment for Multi-Display Devices
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Solution Overview
Problem
Current solutions for correcting display misalignment in head-mounted display (HMD) devices increase device thickness, reducing the 'eye box' and visibility of projected images, as they integrate optics between the user's eyes or adjacent to the forehead or nose bridge.
Innovation Solution
A compact architectural solution that includes a display alignment sensing assembly merging signals from first and second display assemblies via a waveguide, using an optical sensor to detect disparities and adjust rendering positions in real-time, maintaining the eye box size and visibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If display alignment correction optics are integrated between the user's eyes or adjacent to the forehead or nose bridge, then display misalignment can be corrected, but device thickness increases and eye box size decreases
Solution Approach 1:
The patent extracts the alignment sensing function from the traditional inter-ocular region and relocates it to the temporal region (side of the head). The display alignment sensing assembly is positioned to receive signals from display assemblies via waveguides that extend laterally, removing the need for thick optical components between the eyes or on the forehead.
Solution Approach 2:
The patent transitions from a longitudinal arrangement (optics between eyes along the midline) to a lateral arrangement (sensing assembly at the temporal side). This dimensional repositioning allows alignment correction functionality to be distributed to the side of the device, reducing midline thickness while maintaining correction capability.
2Manufacturing precision
If display alignment correction optics are integrated between the user's eyes or adjacent to the forehead or nose bridge, then display misalignment can be corrected, but eye box size and visibility of projected images decrease
Solution Approach 1:
The alignment sensing function is extracted from the central optical path and relocated to the temporal region. This separation prevents the sensing assembly from encroaching on the eye box volume, maintaining full visibility of projected images while enabling alignment correction.
Solution Approach 2:
By moving the sensing assembly to the temporal dimension (side of the head) rather than positioning it in the central optical path, the patent preserves the eye box area. The waveguide-based signal transmission allows alignment data to be collected from the lateral position without blocking the forward viewing path.
3Length of stationary object
If waveguides are used to direct signals from display assemblies to the sensing assembly, then alignment detection can be achieved without increasing device thickness, but optical signal loss may occur
Solution Approach 1:
The waveguides serve dual functions: they transmit display signals to the user's eyes and simultaneously route alignment verification signals to the sensing assembly. This multi-functionality eliminates the need for separate alignment sensing optics, reducing overall device thickness while maintaining signal integrity through established waveguide pathways.
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 solution actively corrects signal misalignment due to thermal and environmental influences without decreasing the eye box size, ensuring improved image clarity and alignment in AR and VR systems.
Implementation Method 1
A waveguide directs the second signal from the output of the second display assembly to the display alignment sensing assembly
Implementation Method 2
the first signal and the second signal are merged into a combined signal and received at an optical sensor
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
A device disclosed herein includes a display alignment sensing assembly positioned to receive a first signal output from a first display assembly and a second signal output from a second display assembly. A waveguide directs the second signal from the output of the second display assembly to the display alignment sensing assembly where the first signal and the second signal are merged into a combined signal received at an optical sensor. A display alignment tracker detects a positioning disparity between the first signal and the second signal within the combined signal and outputs a rendering position adjustment instruction to correct for the detected positioning disparity.