Vibration Actuator with Linear Ball Bearings for Compact Wearables
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Solution Overview
Problem
Conventional vibration actuators require large attaching spaces, suffer from mechanical load limitations due to metal fatigue, and have increased friction and component count, especially when downsized, leading to reduced output and assembly challenges.
Innovation Solution
A vibration actuator design featuring a flat coil and magnet configuration with linear bearings that allow the movable member to freely vibrate, reducing friction and mechanical load through ball-bearing contact, enabling efficient vibration and downsizing while maintaining durability and assemblability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a flat-plate shaped vibration actuator is used to downsize the device, then the device size is reduced, but a large attaching space is required which enlarges the ring-shaped device
Solution Approach 1:
The patent integrates the linear bearing function directly into the movable member structure by providing guide surfaces on the movable member that contact the balls, eliminating the need for separate bearing components. This merging of functions allows the actuator to achieve compact dimensions without requiring additional attaching space for separate bearing assemblies.
Solution Approach 2:
The movable member serves multiple functions: it acts as both the vibrating element and the bearing support structure. The guide surfaces provided by the movable member simultaneously constrain the ball movement and support the vibrational motion, creating a multi-functional component that reduces overall device size.
2Device complexity
If the movable member is held only with the metal spring, then the structure is simple, but the mechanical load is large causing metal fatigue and limited product lifetime
Solution Approach 1:
The patent replaces the traditional metal spring mechanical support system with a magnetic field-based positioning system. The coil generates a magnetic field that interacts with the magnet on the movable member to provide positioning and support forces, substituting mechanical spring loading with electromagnetic forces that eliminate metal fatigue issues.
3Stability of the object's composition
If a sliding movement part is employed to restrict rotation, then the rotational restriction is achieved, but the number of components and cost are increased and friction attenuation is increased reducing output
Solution Approach 1:
The rotational restriction function is merged into the guide surface geometry of the movable member. The shaped guide surfaces inherently constrain the balls to prevent rotational movement while allowing linear vibration, eliminating the need for separate rotational restriction components.
Solution Approach 2:
The balls serve as intermediary elements that transmit force between the coil-magnet system and the movable member while the guide surfaces mediate the motion constraints. This intermediary ball-bearing system provides rotational restriction without requiring direct mechanical contact or additional restriction components.
4Stability of the object's composition
If the sliding movement part is used, then the rotational restriction is achieved, but the friction attenuation is increased which reduces the output
Solution Approach 1:
The patent replaces the high-friction sliding contact system with a low-friction rolling ball-bearing system. The balls roll along the guide surfaces instead of sliding, dramatically reducing friction losses and improving the transmission of electromagnetic force to vibrational output.
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 achieves efficient vibration with reduced friction and mechanical load, enhancing durability and assemblability, allowing for compact and reliable operation of the actuator.
Implementation Method 1
a movable member including a magnet disposed opposite to the coil, the movable member being configured to vibrate back and forth in one direction with respect to the fixing body above the planar part by cooperation of the coil and the magnet
Implementation Method 2
the pair of linear bearings including a ball capable of freely rolling and making contact with the two side surfaces
Data Source
AI summary
An oscillatory actuator has: a fixed body that has a planar part and a flat coil disposed on the planar part; and a movable body that has a magnet facing the coil and oscillates in a reciprocating manner in one direction relative to the fixed body above the planar part via cooperation between the coil and the magnet. The fixed body has a pair of linear bearings that are respectively disposed along both side surfaces extending in said one direction of the movable body and are equipped with balls capable of rolling and coming into contact with the respective side surfaces. The movable body is supported via the balls of the linear bearings so as to be able to oscillate in said one direction.