Patent ID: 8085258
Filing Date: 2011-12-27
Classification: G09G

Abstract:
1. A driving method for an organic electroluminescence light emitting portion using a driving circuit for driving the organic electroluminescence light emitting portion, the organic electroluminescence light emitting portion including (A) a driving transistor of the n channel type having source/drain regions, a channel formation region and a gate electrode, (B) an image signal writing transistor having source/drain regions, a channel formation region and a gate electrode, and (C) a capacitor element having a pair of electrodes, the driving transistor being configured such that the image signal writing transistor being configured such that the driving circuit further including the first node initializing transistor being configured such that a first voltage for supplying current toward the organic electroluminescence light emitting portion through the driving transistor and a second voltage for preventing a potential difference between the second node and a cathode electrode provided on the organic electroluminescence light emitting portion from exceeding a threshold voltage of the organic electroluminescence light emitting portion being selectively applied from the power supply section to the first one of the source/drain regions of the driving transistor, and a lightly doped drain structure being formed adjacent the first one of the source/drain regions of the driving transistor, said driving method for an organic electroluminescence light emitting portion comprising the steps of: (a) carrying out a pre-process of applying a first node initializing voltage from the first node initializing voltage supply line to the first node through the first node initializing transistor, which is placed in an on state by a signal from the first node initializing transistor control line, so that the potential difference between the first node and the second node may exceed the threshold voltage of the driving transistor and applying the second voltage from the power supply section to the first one of the source/drain regions of the driving transistor; (b) carrying out a threshold voltage cancellation process of applying, in a state wherein the first node initializing voltage remains applied from the first node initializing voltage supply line to the first node through the first node initializing transistor which maintains an on state in response to a signal from the first node initializing transistor control line, the first voltage from the power supply section to the first one of the source/drain regions of the driving transistor to cause the potential at the second node to vary toward the potential of the difference of the threshold voltage of the driving transistor from the potential at the first node in a state wherein the potential at the first node is maintained; (c) carrying out a writing process of applying the image signal from the data line to the first node through the image signal writing transistor, which is placed in an on state by a signal from the scanning line; and (d) carrying out a process of placing the image signal writing transistor into an off state in accordance with a signal from the scanning line to place the first node into a floating state and supplying current according to the value of the potential difference between the first node and the second node from the power supply section to the organic electroluminescence light emitting portion through the driving transistor.