Ferritic Core Haptic Actuator for Quiet Linear Motion
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Solution Overview
Problem
Existing haptic actuators in electronic devices often produce undesirable noise and lack control over haptic output, with rotary mass actuators causing a 'buzzy' feel and linear actuators being large or unidirectional, while also being noisy and lacking precision in haptic feedback.
Innovation Solution
A bidirectional linear actuator with a ferritic core and stationary magnet arrays, utilizing a coil architecture to induce electromagnetic forces for precise and controlled linear motion, providing a slimmer profile and quieter operation by channeling magnetic flux into a ferritic shaft to enhance the Lorentz force and reduce fringing effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If rotary mass actuators are used to provide haptic output, then haptic feedback can be provided, but the device produces audible noise and a buzzy feel
Solution Approach 1:
The patent replaces the mechanical rotary mass actuation system with an electromagnetic linear actuation system. The linear actuator uses electromagnetic forces to move a shaft back and forth linearly, eliminating the rotational inertia and uncontrolled shaking characteristic of rotary mass actuators, thereby reducing noise and improving haptic control precision.
Solution Approach 2:
The patent implements bidirectional linear motion capability where the shaft can move in both directions along its axis. This dynamic bidirectional movement allows for precise control over the haptic output timing and characteristics, enabling discrete outputs without unacceptably long time intervals between them.
2Object-affected harmful factors
If linear actuators are used instead of rotary mass actuators, then haptic output is crisper and quieter, but the actuators are relatively large
Solution Approach 1:
The patent reorients the magnetic field geometry from a traditional radial configuration to a轴向 (axial) configuration where magnetic field lines run parallel to the shaft axis. This dimensional reorientation allows for a more compact actuator design with reduced volume while maintaining the quiet operation and crisp haptic output characteristics.
Solution Approach 2:
The patent employs a nested arrangement where the coil is wound around the shaft, and the magnetic circuit components are integrated within the housing. This nesting of components allows for a compact design that reduces the overall actuator volume while maintaining effective electromagnetic coupling.
3Object-affected harmful factors
If linear actuators are used, then haptic output is quieter, but they can only move mass in a single direction
Solution Approach 1:
The patent implements bidirectional linear motion capability where the shaft can move in both directions along its axis. This dynamic bidirectional movement allows for precise control over the haptic output timing and characteristics, enabling discrete outputs without unacceptably long time intervals between them.
Solution Approach 2:
The patent segments the magnetic circuit into distinct north and south pole arrays positioned on opposite sides of the shaft. This segmentation allows independent control of magnetic polarity on each side, enabling the shaft to be actuated in both directions along its axis by selectively energizing coils with appropriate current directions.
4Power
If traditional magnet arrays are used in linear actuators, then electromagnetic force can be generated, but magnetic flux fringing reduces force efficiency
Solution Approach 1:
The patent introduces a ferritic shaft as an intermediary magnetic conductor between the magnetic pole arrays and the coil. This ferritic shaft serves as a magnetic flux guide that channels the magnetic field lines axially, reducing fringing effects and improving the efficiency of electromagnetic force generation.
Solution Approach 2:
The patent employs a ferritic shaft material that combines ferromagnetic properties with mechanical strength. This composite material approach allows for efficient magnetic flux conduction while maintaining structural integrity, reducing magnetic flux fringing and improving electromagnetic force efficiency.
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 enables a more controlled and quiet haptic output with a slimmer profile, effectively addressing the noise and precision issues of existing actuators by using a ferritic core to enhance magnetic field strength and reduce unwanted vibrations.
Implementation Method 1
Current in the conducting coils induces electromagnetic forces on the shaft, causing it to move linearly
Implementation Method 2
utilizing a coil architecture to induce electromagnetic forces for precise and controlled linear motion
Implementation Method 3
channeling magnetic flux into a ferritic shaft to enhance the Lorentz force and reduce fringing effects
Data Source
AI summary
Disclosed herein are linear actuators and haptic actuators for providing haptic output on an electronic device. In some embodiments, the linear actuator comprises two linear arrays of permanent magnets within and fixed to a housing. The linear arrays are arranged in parallel planes oriented toward, and located on opposites sides of, a moveable assembly comprising a shaft having a ferritic core. The shaft comprises a set of conducting coils, each conducting coil being located between a magnet from each of the two linear arrays. The linear actuator comprises a support mechanism that is attached to both the housing and to the moveable assembly and is configured to pivot. An electromagnetic force can arise from a current in the coils to cause the moveable assembly to move linearly between the two linear arrays.