ACTIVE MATRIX SUBSTRATE

摘要

PURPOSE:To reduce irregularity of a signal current, by providing a first writing earth wire having a first writing element connected thereto and a second writing earth wire having a third writing element connected thereof, and further providing a first and second control elements for making an entire writing current constant at the time of writing operation. CONSTITUTION:Drive electrodes 1, vertical switches 2, horizontal switches 5, erasing elements 6 and writing elements 7 are arranged respectively in large numbers in an array form, and a writing signal passes through one of the vertical switches 2 selected by a vertical scanning circuit 21 from one of the drive electrodes 1 to be transmitted to a vertical signal wire 4. Further, a signal passing through one of the horizontal switches 5 selected by a horizontal scanning circuit 20 passes through a first writing element 70 and a third writing element 71 to be respectively transmitted to a first writing earth wire 8 and a second writing earth wire 81. At this time, a voltage drop proportional to a writing current and the resistance of the writing earth wires is generated in the writing earth wires. The voltage drop is different according to the position of each writing element on a substrate and an entire writing current value, but the currents flowing to first and second writing earth wires are made constant by control elements 93, 94 regardless of the total number of writings, and writing currents are taken out from opposite directions to be synthesized.