A short-range radio transmitter of a communication device comprising a short-range radio and a long-range radio is controlled to delay packets which are scheduled to be transmitted at the same time as a long-range transmitter of the long-range radio commences or discontinues to transmit. The structure includes a light-guiding plate for receiving, from a light-incident surface, light coming from a light source, and for allowing the light to exit from a bottom surface; a reflective liquid crystal display panel opposed to the bottom surface of the light-guiding plate; and a prism disposed on the side of a top surface of an upper substrate of the liquid crystal display panel. Users can send data andor commands to the directional drilling equipment.