Ring-Shaped HMD Mount With Torque Limiter for Fine Fit Adjustment
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Solution Overview
Problem
Existing head-mounted display (HMD) mount units face challenges in providing a circumference variable mechanism that allows for easy adjustment to fit various head shapes, leading to inconvenience due to difficulties in fine-tuning the circumference and holding force.
Innovation Solution
A ring-shaped mount unit with a first and second housing, featuring band portions and an engagement mechanism, including a pinion and torque limiter, allowing for intuitive enlargement and reduction of the circumference through operations A and B, generating holding forces in both directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a retention mechanism is provided to prevent the inner belt from moving in a direction where the inner belt is removed from the outer belt, then the HMD can be securely held on the user's head, but it becomes difficult to make fine adjustments to enlarge the circumference of the mount unit
Solution Approach 1:
The patent applies a torque limiter that allows the pinion to rotate freely up to a certain threshold torque, enabling fine adjustments. When the applied torque exceeds the threshold, the torque limiter slips or disengages, allowing larger circumference changes. This dynamic behavior resolves the contradiction by providing both secure holding (when torque is below threshold) and easy adjustment (when torque exceeds threshold).
Solution Approach 2:
The torque limiter changes the mechanical parameter of resistance to rotation based on the applied torque. At low torque levels, it provides high resistance to maintain holding force. At high torque levels, it reduces resistance to enable easy adjustment. This parameter change resolves the contradiction between maintaining holding force and enabling fine adjustments.
2Adaptability or versatility
If a rack and pinion is combined with a latching mechanism, then the circumference can be adjusted, but the user needs to keep turning the dial to achieve the maximum circumference
Solution Approach 1:
The torque limiter creates a dynamic system where the resistance to dial rotation changes based on the applied force. Initially, the torque limiter provides high resistance for precise control. As the user applies more force, the torque limiter slips or disengages, allowing the dial to rotate more freely and achieve maximum circumference adjustment with less effort. This resolves the contradiction between adjustment range and operation complexity.
Solution Approach 2:
The torque limiter operates in periodic cycles of engagement and disengagement. During normal adjustment, it is engaged providing controlled resistance. When maximum adjustment is needed, it disengages periodically allowing rapid rotation. This periodic action enables both precise control and easy achievement of maximum circumference.
3Adaptability or versatility
If the circumference of the mount unit is enlarged, then the holding force is weakened, but the mount unit becomes more comfortable for various head shapes
Solution Approach 1:
The torque limiter dynamically adjusts the holding force based on the circumference size. When the mount unit is at a smaller circumference, the torque limiter is engaged providing strong holding force. When the circumference is enlarged, the torque limiter disengages or slips, reducing the holding force to prevent discomfort. This dynamic adjustment resolves the contradiction between adaptability and holding force.
Solution Approach 2:
The system changes the mechanical parameter of holding force in response to circumference changes. As the circumference increases, the torque limiter reduces the holding force parameter to maintain comfort. This parameter change enables the mount unit to adapt to various head shapes while maintaining appropriate holding force for each size.
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 easy and intuitive adjustment of the mount unit's circumference, improving user convenience by allowing precise fitting and comfortable wear without the need for complex operations, while maintaining a suitable holding force.
Implementation Method 1
a torque limiter configured to limit torque applied to a pinion from an operation member
Data Source
AI summary
A head mounted device includes a ring-shaped mount unit for mounting the head mounted device on a head of a user, the ring-shaped mount unit including a first housing having a band portion on each of both sides thereof and a second housing having an engagement portion to be engaged with the band portion, and the ring-shaped mount unit being formed in a ring shape that enables enlargement and reduction of a circumference thereof by engagement of the band portion with the engagement portion. The head mounted device further includes a circumference holding unit, such as a torque limiter, configured to generate a holding force at least in a circumference enlargement direction of the ring-shaped mount unit.