Patent ID: 8994629
Filing Date: 2015-03-31
Classification: G09G,G11C

Abstract:
1. A display device comprising a gate shift register, the display device comprising: a display panel; a gate shift register comprising a plurality of stages cascade-connected to each other and sequentially supplying scan pulses to scan lines of the display panel; a threshold voltage sensing circuit comprising a monitoring TFT and a detection TFT and outing a sensed voltage; and a VDD regulator circuit that calculates a threshold voltage of a pull-down transistor included in each of the plurality of stages, adaptively adjusts a variable high-potential voltage based on the calculated threshold voltage, and gives feedback to the threshold voltage sensing circuit, wherein an nth one of the plurality of stages comprising: a pull-up transistor that outputs any one of gate shift clocks as an nth scan pulse of a gate high voltage in accordance with a potential of a Q node for controlling a switching operation of the pull-up transistor; a pull-down transistor that is connected to the pull-up transistor through an output node, and outputs a low-potential voltage as an nth scan pulse of a gate low voltage in accordance with a potential of a QB node for controlling a switching operation of the pull-down transistor; and a switching circuit that charges and discharges the Q node and the QB node, respectively, or vice versa in response to a set signal and a reset signal, wherein an adaptively adjusted variable high-potential voltage is applied to the QB node to correspond to a shift in the threshold voltage of the pull-down transistor, and wherein the monitoring TFT charges the sensed voltage, which is obtained by subtracting the threshold voltage from the variable high-potential voltage, in a first node in response to the variable high-potential voltage and a monitoring pulse applied to a first electrode: and the detection TFT outputs the sensed voltage charged in the first node to the VDD regulator circuit in response to a detection pulse applied to a control electrode.