Abstract: An electrostatic display device includes an insulative base, a substantially transparent fixed electrode mounted on the base, a substantially transparent dielectric layer such as silicon dioxide applied on the outer surface of the fixed electrode, a resilient sheet electrode fixed at one end thereof to the base and extending therefrom adjacent to the fixed electrode, a means for applying a voltage between the fixed electrode and the sheet electrode, and a display placed on or behind the inner surface of the fixed electrode. When there is no voltage between the fixed and the sheet electrodes, the display is visible through the transparent fixed electrode and the dielectric layer, whereas upon applying a voltage between the fixed and the sheet electrodes, the sheet electrode is attracted to and covers the outer surface of the fixed electrode, thereby concealing the display.

Abstract: A controlling unit for a.c. driving an electrostatic device such as an electrostatic display device having a fixed electrode, a resilient sheet electrode and a dielectric layer interposed between the electrodes wherein the sheet electrode is drawn to the outer surface of the fixed electrode to cover the same upon the application of a voltage between the fixed and the sheet electrodes whereas the sheet electrode is kept apart from the fixed electrode upon the removal of the voltage between the electrodes. The controlling unit of this invention includes a resistance in series with an a.c. voltage supply and the electrostatic display device, a triode thyristor switch with a first terminal and a second terminal connected across the fixed and the sheet electrodes, and a switching means for controlling the gate of the thyristor so that the thyristor has an on-off switching function at its leakage current region.

Abstract: An electrostatic display device includes a casing with a pair of side walls, a fixed electrode having a cylindrical surface and a ridge at the upper most portion of the surface, a pair of flaps of resilient sheet electrode standing adjacent to the fixed electrode along the inner surface of the side walls, and a layer of insulating material provided on the outer surface of the fixed electrode and/or the inner surface of the resilient sheet electrode, whereby upon applying a voltage to the electrodes, the resilient flaps are attracted to the cylindrical surface of the fixed electrode and cover the same in a moment, changing the appearance of the device.

Abstract: An electrostatic display assembly including a plurality of channel shaped casings fixed to an insulating base plate into a line, each casing having a pair of side walls, a fixed electrode extending throughout the length of the casings therein, a resilient sheet electrode supported within each casing so that a pair of flaps of the sheet electrode extend upwards adjacent to the fixed electrode along the inner surface of each casing, and a thin layer of insulating material interposed between the outer surface of the fixed electrode and the inner surfaces of the resilient sheet electrodes, whereby upon the application of voltage between the fixed electrode and any one of the resilient sheet electrodes which are electrically independent of each other, that flaps of the sheet electrode are attracted to the surface of the fixed electrode and covers the same in part, changing the appearance of the assembly.