Abstract: A mold assembly including an outer mold and an associated inner mold, the inner mold being organized to engage in the outer mold, the outer mold having a curved main portion with a central opening and an outer rim extending in a plane, and the inner mold having a curved main portion with a central chimney shaped to pass with small clearance through the opening and an outer rim which, when the molds are mutually engaged, is coplanar with the outer rim of the outer mold and co-operates therewith to close the molding space defined between the curved portions.

Abstract: nnnnA grey tone display and a driving method are described. The display comprises a light influencing layer, an electrode pad located adjacent to the layer at one side of the layer in order to define a pixel in the layer, an n-channel field effect transistors connected to the electrode pad at its source terminal, a p-channel field effect transistors connected to the electrode pad at its source terminal, a first control line connected to the drain terminal of the n-channel field effect transistor, a second control line connected to the drain terminal of the p-channel field effect transistor, a third control line connected to the gate terminals of the n-channel field effect transistor and the p-channel field effect transistor, and a control circuit for supplying control signals to the first, second and third control lines. By this configuration, the voltage of the electrode pad can be arbitrarily controlled by adjusting the input level at the gate terminals.