Shake it like a Polaroid picture…
A long time ago cell phones had physical keyboards. Perhaps you won’t even remember, or you weren’t born yet. Much have changed since the iPhone was introduced in 2007. For the old timers out there, here’s a flashback from the old days!
One of the greatest innovations Steve Jobs introduced to the world in 2007 was the “soft” keyboard. Instead of a mechanical keyboard, the iPhone allowed you to key by touching the screen. Blackberry and its followers said, at the time, that people would never give up the mechanical keyboards in their Blackberries. I guess we both know who was right…
A critical feature of a “soft” keyboard is its haptic feedback. What is haptic feedback? Well, that’s the “shake” the phone does when you touch the screen, a way to trick your brain into thinking it’s touching a mechanical keyboard. The same motor used to shake your phone during a touch is also used to vibrate when your device is in silence mode.
There is a wide range of haptic motors used in smartphones today. From Apple’s famous Taptic Engine to simple rotational motors, we’ve seen quite a variety of solutions to this problem over the years. The release of the new Samsung S10 Plus brought us another type of haptic feedback motor. Here’s an x-ray we got of S10’s vibration motor during the teardown with our friends from ifixit:
Not very exciting right?! Looks like a broken turntable. And you’ll likely miss that analogy as well… Anyway, the dark disk you see is a weight that moves up and down. An electromagnetic field applied to this magnet pulls it down, and a spring pushes it right back up. To see this cool movement, check the following video taking with our TruView Prime X-Ray system.
So now you know how a vertical linear motor works. To compare to a horizontal type, here’s a video from Apple’s Taptic Engine:
Geek Level 11
Here’s a little behind the scenes! It wasn’t easy to get the x-ray video of S10’s vibration motor. As you can see in this photo from ifixit’s teardown, the motor is nicely nested inside the phone:
It makes sense that vibration motor is well nested inside the case – after all, it needs to vibrate the whole phone when powered. And you don’t want it to come loose, otherwise it will be running inside your phone like a Tasmanian devil.
To get you the nice video in this post, we asked our ifixit surgeons to extract the vibration motor from its housing. We needed to do that to get you the nice side view shot that shows the weight moving up and down. Why not taking a side x-ray shot of the whole phone you ask? Good question! Unfortunately there’s a lot of stuff on the way, and the images came out too busy. Here’s one example:
And here’s the vibration motor as removed from the S10. Note you can’t just plug the terminals to a DC power supply. Instead, we had to connect it to a signal generator. We used a sine wave with 5V peak-to-peak. The frequency of the sine wave determines how fast the motor vibrates. The video in this post was taken with 10Hz.