JPH05250990

PURPOSE:To detect a defective part, and also heighten work efficiency by treating a pattern inspection on a back plate electrically in a back plate inspecting method for a display device where laterally symmetrical same electrodes are formed in multi-shape patterns. CONSTITUTION:Electrically conductive rubber 8 having a common electrode 7 is connected to plural electrodes 4 where patterns are formed on a back plate substrate 1, and false signals 10 are inputted to the common electrode of the equipotential electrically conductive rubber, and the signals transmitted through back plate patterns 4 are detected by means of a selecting circuit 12, a differential Amp circuit 13 and a comparing circuit 14 arranged in the rear stage. The detected result is displayed by means of a display element 15. Thereby, the detection of a failure place becomes possible, and inputs of the selecting circuit 12 are also switched by means of a counter circuit 17 in synchronism with a reference clock signal, so that an inspecting time can be shortened significantly.