We’ve seen several online media outlets reporting that Apple have changed their vibration motor in the newest iPhone 5. Many are saying they find the new motor louder and ‘sluggish’, but prefer the increased vibration strength as they previously missed many of the vibration alerts.
Something that we’ve caught onto is that many are suggesting the 4S used a Linear Resonant Actuator, instead of the Eccentric Rotating Mass vibration motors that were used in previous iPhone’s. The latest edition has reverted to a cylindrical form factor.
Most of this is based on a teardown of the phone by iFixit, with the motor pictured below:
This would be an interesting change, not just to the motor but also for the drive circuitry.
LRAs require an AC signal, which usually means dedicated driver chip is used within the digital circuit. This means the iPhone would have had a driver integrated for just one edition before moving back to the ERM.
As we've not had a chance to test the motor, it’s also possible that the above motor is a coin vibration motor, which is an ERM and can be driven in the same method as the cylindrical ERMs with a DC voltage. Also, coin vibration motors have poorer haptic performance than their cylindrical counterparts. Particularly lag time, which is the time taken for the motor to reach the minimum vibration strength that humans can feel (0.04G) from rest. You can sort our vibration motors by Typical Lag Time using the following link:
Then again, Apple may actually have implemented an LRA for one edition, only to have to give it up due to space requirements. The easiest way to test is for a user to stick a DC voltage across the terminals of the motor and see if it vibrates! Any volunteers?!
Linear Resonant Actuators