The functionality of a Vibration Motor is defined by its internal construction, which has evolved to meet diverse application needs. The most traditional type is the Eccentric Rotating Mass (ERM) motor. It consists of a brushed DC motor shaft connected to a semi-circular counterweight. The motor's rotational speed directly controls vibration frequency, while the mass and offset of the weight determine amplitude. A more advanced type is the Linear Resonant Actuator (LRA). Instead of a spinning mass, an LRA uses a magnetic mass attached to a spring within a coil. When an AC signal is applied, the mass oscillates linearly at a resonant frequency, providing faster, more precise, and quieter vibrations with a wider range of haptic effects compared to an ERM.

Key performance parameters for a Vibration Motor include rated voltage, operating speed (RPM for ERMs), resonant frequency (for LRAs), start/stop time, and the generated vibration force (often measured in G-force). The housing must securely contain the moving parts while effectively transmitting vibrations. For ERMs, the quality of the brushes and bearings affects lifespan and noise. For LRAs, the precision of the spring and magnetic assembly is critical. Miniaturization has been a major trend, leading to ultra-thin piezoelectric motors that generate vibration through the deformation of a ceramic element when voltage is applied, though these are less common.

Selecting the right motor type involves balancing factors like desired haptic profile, response time, power budget, physical space, and cost. The engineering behind different Vibration Motor architectures demonstrates a focus on optimizing the user experience. From the simple rumble of an ERM to the sharp, distinct tap of an LRA, the evolution of this technology continues to refine how we physically interact with the digital world.