Appearance-modifying device, method for manufacturing such a device, and method for operating such a device

An appearance-modifying device (10;

• 30), for modifying the appearance of a surface covered thereby, comprising:
• a first substrate (11) having a first electrode layer (17) arranged on a first side thereof, the first electrode layer (17) being covered by a dielectric layer (21);
• a second substrate (12), arranged opposite the first side of the first substrate (11);
• a spacer structure (13) spacing apart the first (11) and second substrates (12) in such a way that a space between the first (11) and second (12) substrates is divided into a plurality of cells (15, 16:
• 31);
• in each cell (15, 16:
• 31), an optically transparent fluid (19) having a plurality of particles (20) dispersed therein, the particles (20) being moveable in the fluid (19) through application of an electric field;
• and
• a second electrode (18) spaced apart from the first electrode (17) layer at least by the dielectric layer (21),
• wherein the dielectric layer (21), in each cell (15, 16:
• 31), has a recess formed therein;
• and
• wherein the distribution of particles (20) within each of the cells (15, 16:
• 31) is controllable, by application of a voltage between the electrodes (17, 18), from a first, dispersed state, to a second state in which the particles (20) are concentrated adjacent to at least one of the recess in the dielectric layer (21) and the second electrode (18).

A method for operating an appearance-modifying device (30) comprising a plurality of cells (31), each cell comprising a plurality of particles including a first set (20a) of charged particles having a first color and a first polarity, and a second set (20b) of charged particles having a second color and a second polarity, opposite the first polarity, distributed in an optically transparent fluid (19), and first (17) and second (18) electrodes for enabling laterally displacing the particles (20a, 20b) to concentrate the particles at a first (45) and/or a second (46) particle concentration site through application of a voltage between the first (17) and second (18) electrodes,

• wherein each cell is configured in such a way that application between the first (17) and second (18) electrodes of a given voltage results in a first electric field adjacent to the first particle concentration site (45) and a second electric field adjacent to the second particle concentration site (46), the first electric field having a higher field strength than the second electric field, the method comprising the steps of:
• determining a polarity and a magnitude of the voltage between the first (17) and second (18) electrodes resulting in that the first electric field is sufficiently strong to concentrate the first set of charged particles (20a) to the first electrode (17), and that the second electric field is so weak that the second set of particles (20b) substantially remain in a dispersed state;
• and
• applying the determined voltage between the first (17) and second (18) electrodes to thereby control the cell (31) to a state having substantially the second color.