An electrophoretic display panel (1), comprising a plurality of picture elements (2), an electrophoretic medium (5) having charged particles (6), and first and second electrodes (3,4) associated with each picture element (2) for receiving a potential difference. As the display (1) is addressed, for each picture element (2), the product of voltage and duration of picture voltages is read from a controller (102). After one or more image update periods, there will be a history generated of the total energy seen by each picture element (2). DC balancing is achieved by introducing feedback loop into the controller (102) which attempts to reduce the number stored in the memory (104) to zero, for each picture element (2) by applying one or more high voltage short pulses with a polarity opposite to the number stored in the memory (104).