Abstract: A passive optical display device, which has at least one digit place, has a cavity which is formed by space plates and contains a material which is switchable between different optical states by an electric field, and has electrodes on the surfaces of the plates with the electrode on one surface having seven segments characterized by the segment being interconnected into four separate groups and the electrodes on the other surface being in two parts with the shape of the groups and parts being selected so that if one of the parts or groups does not receive an electrical voltage when it should, the symbol becomes meaningless.