Patent ID: 6633135
Filing Date: 2003-10-14
Classification: G09G,Y10S

Abstract:
An apparatus for evaluating an organic EL display which comprises: an array of pixels in which each pixel is connected to a respective one of a plurality of signal lines and to a respective one of a plurality of selection lines, in which each pixel includes a switch circuit, a constant current circuit and an organic EL element, with the switch circuit being operative to connect the signal line for the pixel to the constant current circuit when the selection line for the pixel is suitably energized, and in which the constant current circuit includes a capacitor which is charged and discharged based on a voltage on the signal line for the pixel when the selection line for the pixel is suitably energized, the capacitor supplying a constant current to the organic EL elements, according to a charge stored in the capacitor, the apparatus being comprised of:a test voltage generation circuit which generates test signals; a control circuit that controls the test voltage generation circuit to supply the test signals to the signal lines and selection lines to energize the organic EL elements of the pixels one at a time; a current detection circuit which is operative to detect a first current flowing in an energized organic EL element when the capacitor in the pixel has been charged and to detect a second current flowing in the energized organic EL element when the capacitor in the pixel has been discharged; and a defect decision circuit which identifies a pixel as defective based on a difference between the first and second currents.