Patent ID: 7915906
Filing Date: 2011-03-29
Classification: G02F,G09G

Abstract:
1. A test device for a liquid crystal display device in which a liquid crystal display unit has liquid crystal display elements arranged in matrix, and thin film transistors have their respective drains connected to the liquid crystal display elements, their respective gates commonly connected to row lines, and their respective sources commonly connected to column lines, the transistors arranged in the same row sharing the line of that row, the transistors arranged in the same column sharing the line of that column, the rows of the lines being controlled by a row driver, and the columns of the lines being supplied with multi-level voltage depending upon gradation of a display image by a column driver, the test device comprising: a comparator circuit provided in each of either the rows or columns of the lines for detecting which of the rows or columns of the lines is selected; an encoder circuit receiving the detection result from the comparator circuit and scanning bi-directionally from head to tail or vice versa of the rows or columns of the lines to obtain the number of the selected row or column line, a plurality of bus lines constituting a bus being varied in voltage level depending upon the obtained number of the selected row or column line and encoding the voltage level in relation with the number; and a read-out circuit reading the voltage level of the bus lines from the encoder circuit to determine if the encoded number is identical with the number of the selected row or column line, wherein said comparator circuit, said encoder circuit, and said read-out circuit being built in the same substrate as the liquid crystal display elements.