A method of driving a display layer comprising an electrophoretic fluid and having first and second surfaces on opposed sides thereof, the electrophoretic fluid comprising four and not more than four types of charged particles, namely high positive particles having a first optical characteristic, high negative particles having a second optical characteristic, low positive particles having a third optical characteristic and low negative particles having a fourth optical characteristic (G; Y), all dispersed in a solvent or solvent mixture, the first, second, third and fourth (G; Y) optical characteristics differing from one another, the method comprising: (a) applying a high electric field having a polarity which drives the high positive particles towards the first surface, thereby causing the first optical characteristic to be displayed at the first surface; (b) applying a high electric field having a polarity which drives the high negative particles towards the first surface, thereby causing the second optical characteristic to be displayed at the first surface; the method being characterized in that: (c) once the first optical characteristic is displayed at the first surface, applying a low electric field having a polarity which drives the low negative particles towards the first surface but is not strong enough to overcome the attractive force between the high positive particles and the high negative particles but sufficient to overcome the attractive force between other oppositely charged particles (13, 14), thereby causing the fourth optical characteristic (G; Y) to be displayed at the first surface; (d) once the second optical characteristic is displayed at the first surface, applying a low electric field having a polarity which drives the low positive particles towards the first surface but is not strong enough to overcome the attractive force between the high positive particles and the high negative particles but sufficient to overcome the attraction forces between other charged particles (13, 14), thereby causing the third optical characteristic to be displayed at the first surface; and (e) applying a shaking waveform to cause a fifth optical characteristic different from the first, second, third and fourth (G; Y) optical characteristics to be displayed at the first surface. (a) applying a high electric field having a polarity which drives the high positive particles towards the first surface, thereby causing the first optical characteristic to be displayed at the first surface; (b) applying a high electric field having a polarity which drives the high negative particles towards the first surface, thereby causing the second optical characteristic to be displayed at the first surface; (c) once the first optical characteristic is displayed at the first surface, applying a low electric field having a polarity which drives the low negative particles towards the first surface but is not strong enough to overcome the attractive force between the high positive particles and the high negative particles but sufficient to overcome the attractive force between other oppositely charged particles (13, 14), thereby causing the fourth optical characteristic (G; Y) to be displayed at the first surface; (d) once the second optical characteristic is displayed at the first surface, applying a low electric field having a polarity which drives the low positive particles towards the first surface but is not strong enough to overcome the attractive force between the high positive particles and the high negative particles but sufficient to overcome the attraction forces between other charged particles (13, 14), thereby causing the third optical characteristic to be displayed at the first surface; and (e) applying a shaking waveform to cause a fifth optical characteristic different from the first, second, third and fourth (G; Y) optical characteristics to be displayed at the first surface.