In a signal transmitter and a signal receiver, a multiplexing part multiplexes a video signal and a time-base-compressed audio signal on the basis of a multiplexing control signal to transmit the multiplexed signal through a data line in the signal transmitter. The sheet for forming an image is provided with two or more image-formative layers which are defined by frame respectively and arranged in a longitudinal direction of the sheet. The inkjet head also includes a driver IC configured to supply a drive signal to the actuator unit, a plurality of plates extending from the flow passage unit, and a cover member secured to the plurality of plates.