That's how big the difference is between vibration motors in smartphones

The vibration of a smartphone: it can remind us when we are called. It can warn us when we receive an important message. That was the intention when the first vibration motors were installed in a smartphone. Today we clarify the question of what differences there are between vibration motors in smartphones.

With the introduction of the Apple Watch in 2014, Apple broke this tradition with the Taptic Engine, Taptic for "tactile" and "haptic". A little later it also reached the iPhone, the use of vibrations was expanded to include haptic feedback during use.

In addition, the non-mechanical home button in the iPhone 7, the small vibration when the number wheel in the clock is turned, the simulation of a mechanical keyboard with the help of vibrations: all examples of how vibrations can break the boundaries of two-dimensionality. A distinction is made between high-quality and "cheap" vibrations. However, many do not know the difference. Today we will show you what exactly is behind it.

Rough overview

A rough overview before we start: The typical vibration motor is called ERM motor, Eccentric Rotating Mass (rotating mass). Then the linear motor was added in the years later, it is divided into the z- and x-axis linear motor.

Difference in vibration shown on a real test

Recorded vibrations can be heard in the following lines. We have a representative for each species so that the differences can be heard clearly. Reviews are not taking place yet, the use of headphones is strongly recommended:

Explanation of the functionality

Which smartphone did you like the most? The grouping in the three different types of engines can be heard clearly. The audio wave also reflects which vibrations were crisper.

The difference is huge. We come to the explaining phase.

ERM vibration motor

In the classic ERM vibration motor, roughly speaking, a rotating mass piece was installed on a motor. The electric coil of the motor receives power from the magnetic field and thus causes the mass to rotate. Due to a so-called centrifugal force, which arises due to the inertia of a body, the whole unit moves together. The whole thing at high speed and the smartphone vibrates.

ERM engine working principle sketch (Image: kellydzt)

It takes a while from the start of the triggering to the vibration, because you first have to set the piece of mass in rapid motion. If you listen carefully, you will notice a latency. Also, you can't get short, crisp vibrations, you can tell from the audio wave that it is rather sluggish. At the same time, the speed also determines the strength of the vibration, which cannot be adjusted individually. The vibrations are all the same, with the adjustable "strength" mostly only the duration of the vibration is changed.

Why do many manufacturers still use this type of vibration motor despite the disadvantages? Price reasons. They are by far the cheapest and pull down the budget needed in a mid-range smartphone.

z-axis LRA vibration motor

On the other hand, there is the z-axis LRA linear motor. It mainly consists of a voice coil, a moving magnetic mass and a spring.

Structure of the engine (Image: kellydzt)

When the current in the coil is changed, so does the magnetic field and the magnetic mass automatically moves up and down in the direction of the z-axis.

z-axis LRA motor mode of operation (Image: kellydzt)

This creates the vibrations that no longer feel so sluggish. The movement can be carried out briefly. As the current changes, these also allow the vibration strength and frequency to be controlled. The energy consumption of an LRA motor is only half that of an ERM motor.

ProIt only becomes problematic when the smartphone is on the table, because the motor fires directly in its downward direction. This creates the extremely loud, frightening noise. This can hardly be avoided, with Samsung it is extremely bad.

Picture: TechnikNews

X-axis LRA vibration motor

The best x-axis vibration motor works in principle in the same way as the z-axis LRA motor, because both use the current strength and coil to change the magnetic field in order to perform back and forth movements via magnetic masses and a spring. Only the direction was changed from the z-axis to the x-axis.

Due to the thickness limitations of a smartphone, z-axis vibration motors have only a small amount of freedom of movement. The vibrations can still sound a bit sluggish and not quite crisp, this is the case with x-axis vibration motors. The advantage of them is simply the larger space to move, which allows the most precise vibrations, greater strength and the highest quality feel. We are currently seeing more and more smartphones that use this type of vibration motor.

Movement space in comparison (picture: TechnikNews)

For such high-quality vibrations you have to sacrifice a lot of valuable space, which is already small Apple Watch consists, for example, of only one third of the Taptic Engine.

The softwareProblem

An Problem has been left out until now, because the same vibration motor gives you a completely different feeling on different smartphones. Some x-axis motors give an ERM motor experience, some z-axis motors feel like x-axis. That Proproblem is a long word: software optimization.

Having the best screen installed is of no use if the color coordination is not right. The largest camera sensor does not take good pictures if the image processing does not match. It's exactly the same for vibration motors, for example some pre-installed keyboards that have absolutely not been adapted to the device and that feel awful. Adaptation is generally not available on some smartphones. I hope that every manufacturer starts to make an effort to optimize it, because no consumer would complain about the better user experience.

Where can you find which vibration motors?

Shortly before the end, I would like to give a rough overview of the market. Since this date is usually not yet to be found on data sheets, you have to inform yourself offline by testing a device or teardown images.

ERM vibration motors can currently be found in most smartphones for less than 300 euros, such as the company's mid-range devices Samsung, Huawei, Realme and many more. at OPPO, Vivo and Motorola it is currently the case that all devices (with three exceptions) use an ERM motor.

Z-axis LRA vibration motors are mostly represented in the upper class, for example in the Find X3 Neo. They are rarely found as a surprise in the lower class, such as in the LITTLE X3 NFC or the Redmi Note 10 Pro. They used to be standard in flagship models like the Xiaomi Mi 9 or Huawei Mate 20 Pro. For reasons of space, however, they are also included in the Huawei P range, the OPPO Find X3 Pro and applied to all Samsung flagships.

Request for vibration motors

Vibrations are important and great, because poor feedback also massively reduces the feeling of high quality of a smartphone. High-quality feedback greatly increases the desire to use the smartphone. I hope that more and more manufacturers focus on this and maybe start to advertise with it. The fact that consumers do not consider it important does not mean that a 799-cent vibration motor can be installed for 30 euros. Nobody would deny a good user experience.

Sources

Texas Instruments: Solutions for ERM and LRA Actuators

YouTube: kellydzt

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