Telephone-coupled visual alphanumeric communication device for deaf persons

Claim 1

A receiver for converting alphanumeric two-frequency electrical signals transmitted from a push-button telephone to visible signals at a message-receiving station, said receiver comprising: an inductive pickup easily removably attachable to a telephone constituting part of said message-receiving station, an amplifier having its input connected to said inductive pickup for amplifying received electrical signals, a bank of differently tuned high-frequency detectors, a bank of differently tuned low-frequency detectors, said amplifier having its output connected to the input of said detectors, a display having a plurality of row conductors and a plurality of column conductors, a plurality of cross-points each formed by the intersection of a row conductor and a column conductor, a plurality of light-emitting diodes each connected between a row conductor and a column conductor at each cross-point, each high-frequency detector being connected to one of said column conductors and each low-frequency detector being connected to one of said row conductors, an inverter unit inserted between either the high-frequency or the low-frequency bank of detectors and the its connected conductors, and a power supply for said receiver, said receiver being electrically conductively isolated from the telephones at the sending and receiving stations.