Patent ID: 7604706

Claim:
A method for producing a reversible image display medium, which comprises two substrates opposed to each other with a predetermined gap therebetween; one or more developer-accommodating cells formed between the two substrates, each having a periphery surrounded by a partition wall; and a dry developer contained in each of the cell(s), wherein the dry developer contains at least two kinds of frictionally chargeable dry developing particles having different chargeable polarities and different optical reflection densities, the method comprising the steps of: forming a resin-molded substrate having one surface which is projected and dented and which includes concavities for forming the developer-accommodating cells for producing a resin-molded substrate; accommodating the dry developer into the concavities on the one surface of the resin-molded substrate formed at the resin-molded substrate forming step and employed as one of the two substrates of the image display medium; and fixing another substrate to the one surface of the resin-molded substrate formed at the resin molded substrate forming step with an adhesive composed of the same kind of resin material as that of the resin layer providing the one surface of the resin-molded substrate; wherein the resin-molded substrate forming step comprises the step of: forming an initial resin substrate by laminating a plurality of resin layers; and heating and pressing the one surface of the initial resin substrate by a molding die to provide the projected and dented surface, wherein the heating and pressing operation is carried out in a manner such that substantially no deformation occurs on the resin layer providing the surface opposed to the one surface of the initial resin substrate, wherein the molding die includes a plurality of the transfer rollers stepwise arranged in a passing direction of the initial resin substrate and opposed to a press roller with a gap therebetween, the transfer rollers have an irregular peripheral surface with projected portions and dented portions for molding the one surface of the initial resin substrate into the projected and dented surface, and the resin-molded substrate is formed by passing the initial resin substrate through the gap between the transfer rollers and the press roller, respectively, and the heating and pressing operation is repeated a plurality of times to give the resin-molded substrate.