Adjustable Head Strap Brake Mechanism for Quiet Tension Retention
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Solution Overview
Problem
Traditional adjustable strap systems for head-worn devices, such as head-mounted displays, often result in audible clicking noises due to pawl engagement with tooth arrays, and they require rotating the adjustment knob to loosen tension for removal, leading to loss of tension settings.
Innovation Solution
The adjustable strap system incorporates a braking mechanism with a pinion gear and racks, allowing for smooth tension adjustment without audible clicks. It also features a lengthening mechanism, such as spiral springs, that enables additional strap travel without rotating the adjustment knob, maintaining the initial tension setting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pawl engagement mechanism is used for tension adjustment, then the strap system can maintain tension settings, but it produces audible clicking noises
Solution Approach 1:
The patent removes the pawl engagement mechanism that causes clicking noises while retaining the essential function of maintaining tension settings through an alternative braking mechanism. The braking element applies friction to the drum to hold position without mechanical engagement clicks.
Solution Approach 2:
The patent replaces the mechanical pawl-tooth array engagement system with a friction-based braking system. The braking element presses against the drum surface to create holding force, substituting the clicking mechanical engagement with smooth friction-based position maintenance.
2Ease of operation
If the adjustment knob is rotated to loosen tension for removal, then the strap can be easily adjusted, but the tension setting is lost
Solution Approach 1:
The patent introduces a dynamic braking mechanism that can be selectively engaged and disengaged. During removal, the braking element is released to allow free rotation of the drum and adjustment knob without resistance, enabling easy strap loosening while preserving the ability to re-engage the brake and restore tension settings.
Solution Approach 2:
The patent allows the user to perform preliminary actions (rotating the adjustment knob freely) without immediately engaging the braking mechanism. The brake can be engaged later to restore the desired tension setting, separating the loosening action from the tension-maintaining action.
3Reliability
If the strap length is fixed by the adjustment knob position, then the tension setting is maintained, but additional strap travel is limited
Solution Approach 1:
The patent creates a dynamic system where the braking element can be selectively engaged to maintain tension at specific positions while allowing movement at other times. This enables the strap to have both fixed tension points and flexible travel ranges, combining reliability with adaptability.
Solution Approach 2:
The patent allows changes in the operational state of the braking mechanism, transitioning between engaged (tension maintained) and disengaged (travel allowed) states. This parameter change enables the system to provide both stable tension settings and additional strap travel as needed.
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 solution provides a quiet, smooth, and comfortable operation by eliminating audible clicks and allowing for additional strap length travel while maintaining the desired tension setting, facilitating easy donning and doffing of head-worn devices.
Implementation Method 1
at least one braking element disposed adjacent to an inner surface of a drum... configured to rotate about the axle... positioned to apply a friction force to the drum
Implementation Method 2
a lengthening mechanism, such as spiral springs, that enables additional strap travel without rotating the adjustment knob
Data Source
AI summary
The disclosed strap adjustment device may include a pinion gear secured to an adjustment knob, a first rack secured to a first strap and engaged with the pinion gear, a second rack secured to a second strap and engaged with the pinion gear, a braking element disposed adjacent to an inner surface of a drum, a brake engagement element configured to press the at least one braking element toward the inner surface of the drum to maintain a length of the first strap and the second strap by engagement of the braking element against the inner surface of the drum, and a spiral spring configured to allow for an increase in a length of the first strap and the second strap when a tension force is applied to at least one of the first strap or the second strap.