Matrix display device with diode switching elements

Claim 1

A display apparatus comprising first and second spaced-apart supporting plates; an electro-optical display medium disposed between the supporting plates; a plurality of picture elements, each defined by a first picture electrode disposed on the first supporting plate and a second picture electrode disposed on the second supporting plate; first and second arrangements of driving electrodes disposed on the first and second supporting plates, respectively, each picture electrode being electrically connected to a predetermined one of the driving electrodes on the respective supporting plate; and a plurality of switching elements, each electrically connected in series with a respective one of the picture electrodes and the driving electrode electrically connected thereto; characterized in that each switching element comprises a punch-through diode device having three regions, each of p-type or n-type semiconductor material, said regions including a central region formed from one of said types of semiconductor material and including two outer regions formed from the other of said types of semiconductor material, each outer region forming a respective p-n junction with the central region, the distance between the p-n junctions being sufficiently small that, when a predetermined switching voltage is applied across the device, punch-through occurs between said junctions between either one of the junctions breaks down.