A signal transmission device includes a transmission unit, a first connection unit, a second connection unit, and a reception unit. The transmission unit sends a transmission signal. The first connection unit includes a first electrode electrically connected to the transmission unit. The second connection unit includes a second electrode that engages with the first connection unit, and, when engaged with the first connection unit, is statically coupled with the first electrode. The reception unit is electrically connected to the second electrode and receives the transmission signal.
