A micro exhibit of good design

I have an electric toothbrush¹.

For all the decline of Braun since Dieter Rams left the company in 1995, they have managed one good feature with this unit that frequently pleases me.

Being a battery powered toothbrush, the unit does have to be charged periodically, about once every two weeks. The battery life is fine, but what is interesting to me – the feature that signifies good design to me – is how the need to charge the unit is communicated to the user.

Good design should guide the user toward good action. Rather than running down linearly, the micro-controller instead creates a hard step in the battery voltage when it dips below a predetermined threshold. This drop in voltage causes a noticeable drop in brush speed, making it immediately clear that the unit needs charging. The unit does have a red light that shows at this point too but we’re all so used to ignoring all the little warnings of light and sound that our devices emit that I pay it no mind. It is the tactile response that elicits a practical response in me.

A second order effect, say you’re travelling and you didn’t bring the charger, at this lower speed the brush will continue working for a few more days, where it might last only one more day were it left to run at full tilt. Enough warning to make it through the trip or source a manual toothbrush.

The result of this good design is that in the almost four years I have owned this toothbrush, despite not keeping it in its charging cradle except when it needs charging, I have never had it run flat. Even I, the most forgetful of people, have been able to keep the thing charged by way of this method of tangible feedback.

This is good, opinionated design.