Electrically-actuated variable transmission film having very low haze and a visible grid in a clear state

A light attenuator (200, 203, 204) comprising a cell (300, 303, 304) having a first transparent substrate (190) and a second transparent substrate (190) defining respective viewing faces (150, 153, 154) and with opposite major surfaces having transparent electrodes (160) and spaced apart (5) to provide a volume there between, said volume containing a transparent polymer structure (100, 103, 104) and electrophoretic ink (1, 2, 3), said electrophoretic ink comprising charged particles (10, 11, 12) dispersed in a transparent fluid (15, 16, 17),

• wherein said charged particles are responsive to an electric field applied to said electrodes and move between:
• a first extreme light state in which said charged particles are maximally spread within said cell to lie in a path of sunlight through the cell, thereby attenuating the sunlight, and a second extreme light state in which said charged particles are maximally concentrated within the cell in locations (130, 133, 134) defined by said polymer structure thereby removing said charged particles from the path of sunlight through the cell, transmitting the sunlight, and providing visual access,
• wherein in said second light state, a viewing face of said light attenuator has a visible pattern of attenuating areas (20, 24) abutting on transparent areas (30, 34) defined by a presence and an absence, respectively, of concentrated charged particles, and
• wherein a repeating unit of said visible pattern consists of an attenuating area and a transparent area, and wherein said repeating unit has a dimension (50, 55 and 60, 65) between 0.3 mm and 3 cm, while a centre-to-centre distance (40, 41) of adjacent attenuating areas or a centre-to-centre distance (45, 46) of adjacent transparent areas is between 0.6 mm and 6 cm.