an electro - optic display system comprises a plurality of display elements each capable of producing an optical display signal in response to electrical operating energy , a separate channel to each of said display elements , each of said channels incorporating a photosensitive element for the purpose of opening the channel in which that photosensitive element is incorporated for a given period to enable electrical operating energy to be applied during the given period via that channel to an appropriate one of said display elements , a generator of electromagnetic radiation signals arranged to irradiate in response to electrical control signals selected ones of said photosensitive elements and a generator of electrical control signals arranged to feed electrical control signals to said generator of electromagnetic radiation signals . the display elements may be arranged in a straight line which may be one row or column of a matrix array of the elements . the photosensitive elements may be photoconductors or photovoltaic elements and they may be part of a single patch formed as an integrated structure with the display elements on a common substrate . the display elements may for example be electroluminescent elements or liquid crystal elements . the first mentioned generator may be a plurality of semiconductor light - emitting diodes .