Abstract: A head (13) comprises a closed container (15) carrying internal (139) and external electrodes and a nozzle (18) and is mounted removably on a carriage (14) on which it is held by a permanent magnet (43) in such a way that the head bears with the external electrode against a metal sheet (32). The magnet is of an annular shape and is carried by the carriage. It attracts a metal plate (39) in the bottom of the container, which carries a pin (41) for centering the head on the carriage and is utilized to make connection to the internal electrode (139). A protuberance adjacent the nozzle (18) presses against the metal sheet (32) which in turn presses the paper (11) against a platen (10). The protuberance establishes the jet-to-paper spacing.

Abstract: A keyboard comprises a plurality of keys which, when depressed, elastically deform conductive laminae which thereby go with a snap action from a stable configuration to an unstable configuration to complete an electrical circuit associated thereto. Each lamina has the form of two mutually transverse pairs of parallel edge strips spanned by a diagonal strip and the edge strips have permanent bends set into them such that the diagonal strip is bowed in the stable configuration towards the corresponding key. A fixed contact on the lamina is located adjacent one end of the diagonal strip and a movable contact is located in the central region of the diagonal strip. A single key actuates two identical laminae, one through an actuator resiliently coupled to the key and the other through an actuator fixed to the key.