Existing Vibration Technologies

Satisfice [verb]: to act in such a way to satisfy the minimum requirements for achieving a particular result.

When product designers set out to develop products that use vibration, they find that they have few technology alternatives to implement this important feature. The few classes of components that are available for use— each have their own constraints.  The designer has to cobble together these components in the hope that they meet their performance goals, but typically they compromise on design goals, have increased costs and their consumers have poor experiences.

Performance requirements are rapidly increasing, but existing technologies are not improving. Consumers are demanding smaller devices, better functionality and longer battery life; and designers are eager to implement disruptive features like HD Haptics. At the same time manufacturers are looking for ways to cut costs 

Existing vibration technologies cannot meet old performance requirements, much less new ones. And there are no other technologies emerging that have the potential to increase vibration performance.

Existing Actuator Technologies

As consumers demand better products that contain vibration, engineers have tried every method possible to increase the performance of the available actuators. Having pushed actuator performance to its limits, designers now have to choose between compromising on performance goals, over-driving actuators at the expense of reliability and battery life or developing their own proprietary solutions at great risk and cost.

The following list gives a brief explanation of the available technologies:

ERM

Standard ERM

ERM or rotary vibration motors are rotary motors with attached eccentric mass at a fixed amplitude. As current is supplied to the motor, it spins up and vibration is created as the eccentric mass is rotates.

Vibrations are transmitted through the motor, and into the device, which causes rapid wear. Because of the dampening involved with the relatively large mass of the device, these motors tend to have effectively limited frequency response.

These motors have highly variable performance between units, over the life of a battery, and over the life of a device and they tend to wear out rapidly.

LRA

Standard LRA

Linear Resonating Actuators are small actuators which are run at a single-resonant frequency with little power and a single-axis of operation. They require an expensive third-party driver chip to remain in resonance. These actuators have high costs and limited performance.

Proprietary Technologies - Because of the lack of other options, several manufacturers have developed their own proprietary vibration technologies for specific purposes. These technologies are developed at great risk and expense, typically for a single application.

Apple® Taptic® Motor

Apple® Taptic® Motor – In an effort to provide haptic functionality in Apple’s recent generation of laptops and watches, they developed the Apple Taptic vibration motor. This motor provides high lateral impact to provide haptic feedback. Production issues for the Apple Taptic motor was the cause of a six-week delay in the launch of the Apple Watch.

Sonicare® Toothbrush Motor – the Sonicare motor was developed to provide high-frequency and powerful vibration for their line of revolutionary toothbrushes. The motor uses a proprietary and expensive manufacturing processes to ensure that the resonant frequency of the brush heads matches the drive frequency in the brush handles.

Clarisonic® Skin Appliance – the Clarisonic Skin Appliance was invented by the same team as the Sonicare toothbrush. They applied the same technology to face cleaning.

Existing Vibration Driver Technologies

Vibration motors and actuators are only part of a solution. To drive a vibration motor, a circuit must be created to drive the motor and to protect the other components on the circuit from reverse EMF and other issues caused by the actuator. Brushed motors may use simple circuits but brushless motors, like LRAs, require an expensive motor driver or feedback-based based driver.

Motor drivers can be a significant cost factor in a vibration solution, potentially costing more than the actuator itself.

Problems with Existing Vibration Technologies

Existing vibration technologies are the cause of many performance, cost and consumer satisfaction issues with products that contain vibration.

Poor Vibration Performance

  • Limited Vibration Power - Existing technologies have very limited vibration strength.

  • Limited Vibration Range - Existing technologies have very limited range of vibration. ERMs operate over a broad range, but tend to provide usable power only at a small range of speeds.

  • Poor Efficiency - Existing technologies have very poor efficiency, which leads to the need for larger batteries. This drives device size and cost.

  • Limited Axis-Control - ERMs operate orbitally and LRAs operate linearly, perpendicular to their mounting, limiting design options.

  • Slow Start/Stop Speed - Existing technologies are slow to start and stop, limiting their usefulness.

Consumer Satisfaction Issues

  • Poor Reliability - Existing actuators, especially ERMs have very poor reliability. Because the relatively large eccentric mass is mounted on a very small shaft supported by small bushings, these motors begin to destruct as soon as they are first used.

  • Noise - Existing actuators cause significant noise, which causes consumer issues. These motors get nosier as they wear. Efforts to dampen the noise also tend to dampen the vibration power.

  • Poor Unit-to-Unit Consistency - ERMs have high variability unit-to-unit, which diminishes product quality.

Device Cost and Size Issues

  • Motor size – Existing actuators have a large size/performance ratio. And, in an effort to meet vibration performance goals, some designers use even larger motors. These motors create design constraints leading to larger devices.

  • Component size and cost - the number of discrete components drives device size and cost.

  • Efficiency Issues - because of the poor efficiency of existing motors, designers either must use larger batteries or have short run times.

  • Reliability Issues - poor reliability of these existing technology drives warranty returns and poor consumer experiences.

Apple® and Taptic® Motor are trademarks of Apple Inc.

Sonicare® and PHILIPS® is a registered trademark of Koninklijke Philips N.V

CLARISONIC® is a trademark of Pacific Bioscience Laboratories, Inc