Its a twist on Sloans original patent for the Optima hands free facuets.
Ever hear of this?
ELECTRONIC AUTOMATIC FAUCET DEVICE
Document Type and Number:
United States Patent 3799198
An electronic automatic faucet device wherein an emitting element of visible or invisible rays, a receiving element for said rays, and a magnet valve are provided for the faucet of a water conduit, wherein the beam path between both the elements is momentarily intercepted, that is, the beam is shut for a short time and the original irradiating state is immediately recovered, thereby to energize the magnet valve into the water feeding state. When the beam path is subsequently intercepted for a moment, the magnet valve is deenergized into the water stopping state. Furthermore, simultaneously with initiation of the water feeding state, a timer circuit starts so as to automatically change said water feeding state to the water stopping state when a predetermined period of time has elapsed.
THey were using photocell beams in the 70's to activate faucets, but as stated they needed an emitter and a receiver to operate. The new ones combine everything into a single unit.