To provide a signal transmission apparatus capable of also causing a signal receiver that the relevant signal transmitter does not originally pair with each other, to receive a signal by a tone signal and does not cause a signal recepter which is not required to receive a signal, to receive a signal. トーン信号によって当該信号送信装置が本来は互いにペアを構成しない信号受信装置に対しても信号を受信させることが可能であって、且つ、信号の受信を必要としない信号受信装置に信号の受信をさせることのない信号送信装置を提供する - 特許庁