ADVERTISING DISPLAY APPARATUS, NAMELY DISPLAY UNITS PARTICULARLY ADAPTED TO DISPLAY ADVERTISING TO A MOVING VIEWER; ADVERTISING BOARDS, ADVERTISING DISPLAY BOARDS AND SIGN BOARDS, EACH NAMELY OF THE TYPE PARTICULARLY ADAPTED TO DISPLAY MESSAGES TO A MOVING VIEWER; LIGHT-CONTAINING BOXES OVER WHICH A TRANSPARENCY CAN BE FITTED, THE BOXES BEING SUITABLE TO BACK LIGHT THE TRANSPARENCY; LIQUID CRYSTAL DISPLAYS; SCREENS, NAMELY PROJECTION AND IMAGE DISPLAY SCREENS; SHUTTERS FOR CONTROLLING ILLUMIN...