Electric Toothbrush

Overview

The electric toothbrush is a sonic, rechargeable oral-care appliance. Rather than a rotary motor, it uses a linear resonant actuator that vibrates the brush stem tens of thousands of times per minute, driving fluid between the teeth in addition to direct bristle contact. The handle is fully sealed for wet use and charges inductively, with no exposed metal contacts.

The Handle Housing encloses the drive, battery and electronics, and the Brush Head snaps onto the drive shaft as a replaceable consumable.

How it works

The Sonic Drive is the core mechanism: an electromagnet coil acts on magnets carried by a sprung armature. The Control Board energizes the coil at the actuator's mechanical resonance, so the armature swings with large amplitude for little power. That oscillation passes through the drive shaft to the head coupling and bristles at sonic frequency, around 31,000 strokes per minute.

The control board carries the microcontroller, a pressure sensor that warns when the user brushes too hard, and an accelerometer that tracks handle orientation for quadrant timing. A two-minute timer pulses the actuator every 30 seconds to pace movement around the mouth, and mode buttons select cleaning intensity.

Power is stored in the Battery Pack, a single Li-Po cell with a protection board. Charging is contactless: the Charging Receiver Coil in the handle base picks up energy transmitted by the Base Charger when the handle is docked. The base rectifies mains power and oscillates its transmit coil; the handle's charge IC rectifies the received field and charges the cell. Sealing the handle this way keeps the device watertight for rinsing and shower use.