Vibration Motors – ERMs and LRAs
There are two basic types of vibration motor. An eccentric rotating mass vibration motor (ERM) uses a small unbalanced mass on a DC motor when it rotates it creates a force that translates to vibrations. A linear resonant actuator (LRA) contains a small internal mass attached to a spring, which creates a force when driven.
As specialists in the supply and design of vibration motors, you can find our stocked motors in our product catalogue. If you can’t find exactly what you need or would like to discuss a project, please do not hesitate to contact our engineers here. If you prefer to read online, you will find lots of additional information and guides to help you understand how vibration motors work.
See the sections below to explore our different vibration motors!
An Introduction to Vibration Motors
Small vibration motors have been around since the 1960s. Initially, they were developed for massaging products, but their development took a new turn in the 1990s when consumers required vibra-call on their mobile/cell phones. Today, designers and users alike have learned from two decades of mobile phones, that vibration alerting is an excellent way to alert operators to an event.
These days miniature vibrating motors are used in a wide range of products, such as tools, scanners, medical instruments, GPS trackers, and control sticks. Vibrator motors are also the main actuators for haptic feedback which is an inexpensive way to increase a product’s value and differentiate it from the competition.
So, if you landed here because you want to make something vibrate, you’re in good company. Precision Microdrives is the leading supplier of sub-Ø60 mm vibrating motors. We carry the widest range of stock and we offer unrivalled application support and on-hand technical expertise.
Precision Microdrives Vibration Motor Ranges
Our ranges of vibration motors help group together alternative products for similar applications, mainly by their construction. You can click on the images below to read more about each range and access the different vibration motors’ datasheets.
Our Pico Vibe™ Range includes our smallest DC vibration motors, perfect for lightweight applications or where space is at a premium. They include miniaturised DC coreless motors with eccentric masses, both in cylindrical and coin form (see the Form Factors section below for more details). This is our widest range, from lightweight vibrations in sizes down to 3mm up to powerful 6G+ motors, they will fit a variety of different applications and power needs.
Precision Haptic™ actuators include our linear resonant actuators as well as a few eccentric rotating mass vibration motors that are specifically designed for haptic feedback applications. They have excellent rise and stop times, which can be improved using specialised driving techniques. You may also wish to compare them to our Pico Vibe™ range as, although not singled out, many of them also offer great haptic performance. Why not try our Haptic Feedback Evaluation Kit to compare different actuators?
Our largest motors are found in our Uni Vibe™ range, which are often our most powerful due to their bigger size. However, as specialists in the supply of miniature DC vibration motors, these ERMs typically do not exceed 50mm in diameter. With the extra vibration strength, our Uni Vibe™ motors are perfect for heavier applications or for those seeking extra vibration strength.
Our brushless vibration motors are in our Dura Vibe™ range. They are long-life motors that are suitable for applications that demand extra long performance time. To achieve this they are based on BLDC motors so do not suffer from commutator wear. Many of these BLDC vibration motors are coin types that include an internal driving IC, making them very easy to integrate.
Different Vibration Motor Form Factors
Whilst the end goal of vibration motors is to produce a force, there are many ways of achieving it. There is a wide range of physical forms, both internal and external, to help you achieve this. To guide you, the articles below help describe the main characteristics of each type. You will notice that some motors may belong to multiple categories, for example, our encapsulated motors are based on ERMs, so you may want to look at several different types for additional information.
Our most popular form factor is the ERM or ‘pager’ motor. This is because there are lots of DC motors available in this cylindrical form, where the eccentric mass helps create an unbalanced force. They are also the most versatile – they can be mounted on PCBs, encapsulated, use a variety of power connections, and even be based on brushless motors. However, coin or ‘pancake’ motors use the same operating principle – but their eccentric mass is kept in their small circular body (which is where they get their names from). They are restricted in amplitude because of their size but have extremely low profiles (only a few mm!) which make them popular in applications which space is restricted.
Encapsulation is the process of sealing an ERM into a plastic housing. These units are popular for applications where the motor is housed with injection moulding or ones that require waterproof vibration motors. Motors that are mounted to PCBs have several connection types, including SMD vibration motors, through-hole chassis, or spring pad terminals. Some even use leaded power connections and a specialised mounting technique (like adhesives) so that PCB tracks do not need to reach the motor itself.
Linear Resonant Actuators (LRA) are the most unique devices in our collection of vibration motors. Although they sometimes look like coin motors, they do not use an eccentric mass to create force. Instead, they have a magnetic mass attached to a spring and driven by a voice coil – a similar design to loudspeakers. This means they are very efficient, have excellent response, and need different drivers compared to a DC vibration motor. Similarly, brushless vibration motors also have different driving requirements. Without wearing the brushes of the commutator, they last for a very long time but (unless the vibration motor has an internal driver IC) are slightly more complicated to operate.
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Common Vibration Motor Applications And Examples
Our customers are always coming up with ever more inventive uses for vibration motors, so it is difficult for us to list them all here! To help, we have discussed some of our most popular categories over the years below.
Haptic Feedback and Vibration Alerting are not necessarily applications themselves, but they are different methods of implementing vibrations within applications. Haptic Feedback uses advanced vibration patterns and effects to convey complicated information to users. Vibration Alerting tends to be a simple on/off alert, perhaps with a ramp effect. A good example is a mobile phone, which in the early days would simply vibrate to notify the user of a call/text. Later, they would play SMS in Morse code, now they have a range of effects for games and applications. Over time, they have progressed from Vibration Alerting to Haptic Feedback.
Vibration motors are a popular method for moving materials and products that can become stuck in chutes or hoppers without the need for human intervention. These applications typically employ some of our larger motors, however, emulsifiers or scientific experiments sometimes make use of smaller vibration motors that meet their specific requirements. Conversely, medical applications will often use smaller devices as within handheld equipment. These devices often have tight requirements for their suppliers, including factory audits, which we are more than happy to help with at Precision Microdrives.
Light, portable devices that need to alert users are perfect for miniature vibration motors – especially when they are powered by batteries. Our wide range of stocked motors helps you select a vibration motor that fits your device’s form factor – not the other way around. Cars are using more and more sensors to assist drivers, unfortunately, these are accompanied by annoying beeps and tones. Vibration motors help give silent information to the driver or augment the audio only warnings.
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