SMA Actuator for Head-Mounted Display Interpupillary Distance Adjustment
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Solution Overview
Problem
Existing head-mounted display devices lack a reliable method for adjusting interpupillary distance, leading to suboptimal user experiences due to manual adjustments that may not accurately align lenses for each user.
Innovation Solution
Incorporating a shape memory alloy (SMA) element connected between the base and lenses, along with a braking element, to electronically adjust and fix the interpupillary distance, allowing for precise and accurate alignment of lenses using SMA elements that change length when heated, and a linking mechanism to synchronize the movement of both lenses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If manual adjustment of lens distance is used, then device complexity is reduced, but manufacturing precision and reliability of interpupillary distance adjustment deteriorate
Solution Approach 1:
The patent replaces the manual mechanical adjustment system with an electronic control system using shape memory alloy elements. These SMA elements can be electrically actuated to precisely control the distance between lenses, eliminating the need for manual mechanical adjustment while achieving accurate interpupillary distance alignment for each user.
Solution Approach 2:
The patent utilizes shape memory alloy elements that change their physical dimensions (length) in response to electrical stimulation. This parameter change allows the lens distance to be dynamically adjusted to match each user's specific interpupillary distance, improving alignment precision without requiring complex mechanical adjustment mechanisms.
2Manufacturing precision
If shape memory alloy element is used for lens adjustment, then manufacturing precision of interpupillary distance is improved, but device complexity increases
Solution Approach 1:
The patent replaces complex mechanical adjustment mechanisms with shape memory alloy elements that can be electrically controlled. This substitution simplifies the overall adjustment mechanism while maintaining high precision in interpupillary distance alignment, as the SMA elements directly respond to electrical signals to achieve the desired lens positioning.
Solution Approach 2:
The patent employs shape memory alloy elements whose physical parameters (length) can be changed through electrical stimulation. This allows for precise control of lens distance with a relatively simple actuation mechanism, improving alignment precision without proportionally increasing device complexity.
3Reliability
If traditional motor-based adjustment system is used, then adjustment reliability is improved, but device weight and volume increase
Solution Approach 1:
The patent replaces traditional motor-based adjustment systems with shape memory alloy elements. SMA elements are significantly lighter and more compact than motors while providing reliable adjustment functionality. The solid-state nature of SMA elements eliminates moving parts associated with motors, reducing weight and volume while maintaining adjustment reliability.
Solution Approach 2:
The patent utilizes the unique property of shape memory alloys to change their length through electrical stimulation. This parameter change mechanism provides a lightweight and compact alternative to motor-based systems, achieving reliable lens adjustment without the weight and volume penalties of traditional motorized systems.
4Ease of manufacture
If manual lens adjustment is used, then ease of manufacture is improved, but adaptability to different users deteriorates
Solution Approach 1:
The patent replaces manual adjustment mechanisms with electrically controllable shape memory alloy elements. This substitution enables programmable and automated adjustment to match each user's specific interpupillary distance, significantly improving adaptability while maintaining ease of manufacture through standardized electronic control components.
Solution Approach 2:
The patent employs shape memory alloy elements that can be electrically actuated to achieve precise dimensional changes. This allows the device to adapt to different users' interpupillary distances through electrical control, improving versatility without complicating the manufacturing process, as the SMA elements can be integrated into standard manufacturing workflows.
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 precise electronic adjustment of interpupillary distance, reducing blur and improving visual clarity, while occupying less volume and being more lightweight compared to motor-based systems, ensuring optimal lens alignment for each user.
Implementation Method 1
The first SMA element is connected between the base and the first lens or connected between the second lens and the first lens, and is used to move the first lens and adjust a distance between the first lens and the second lens
Implementation Method 2
SMA elements that change length when heated
Data Source
AI summary
A head-mounted display device includes a base, a first lens, a second lens, a first shape memory alloy (SMA) element, and a braking element. The first lens and the second lens are movably disposed on the base. The first SMA element is connected between the base and the first lens or connected between the second lens and the first lens, and is used to move the first lens and adjust a distance between the first lens and the second lens. The braking element is disposed on the base. The braking element brakes the first lens at a braking position. The braking element is separated from the first lens at a movable position.