Gate driver and display panel having the same
A display panel includes pixels connected to gate lines, and a gate driver that supplies a gate signal to at least one of the gate lines and includes a plurality of stages. Each stage includes a pull-up transistor to apply a turn-on voltage of a first clock signal to an output terminal responsive to a voltage at a Q-node, a pull-down transistor to apply a turn-off voltage to the output terminal responsive to a voltage at a QB-node that holds the turn-on voltage during a period in which the output terminal is applied the turn-off voltage, and a QB-node control unit to apply the turn-on voltage to the QB-node responsive to the first clock signal and a second clock signal in reverse-phase with the first clock signal. Accordingly, a display panel may include a gate driver that can set, reset, and hold the voltage at a QB-node.
1. A gate driver, comprising:
a QB-node control unit configured to control a QB-node, the QB-node being a gate node of a pull-down transistor, the QB-node control unit comprising:
a first transistor and a second transistor, each having an electrode connected to a QP-node for controlling the QP-node;
a third transistor configured to apply a gate-off voltage to the QB-node;
a fourth transistor having a gate electrode connected to the QP-node, the fourth transistor being configured to apply a second clock signal to the QB-node; and
a first capacitor connected between the QP-node and an input terminal inputting the second clock signal,
wherein the first transistor is controlled by a start signal,
wherein the second transistor is controlled by a first clock signal,
wherein an electrode of the first transistor is connected to an input terminal being applied the gate-off voltage,
wherein an electrode of the second transistor is directly connected to an output terminal outputting an output signal of the gate driver,
wherein a gate electrode of the third transistor and a gate electrode of the first transistor are directly connected to an input terminal inputting the start signal, and
wherein the second transistor is turned on, such that the output signal of the gate driver is applied to the QP-node, and the fourth transistor is turned on, such that the second clock signal is applied to the QB-node, while the output signal of the gate driver is a gate-on voltage.
2. The gate driver of claim 1 , wherein the QB-node control unit further comprises a second capacitor connected between the QB-node and an input terminal being applied a gate-off voltage.
3. The gate driver of claim 1 , further comprises a fifth transistor configured to apply a gate-on voltage to the gate electrode of the pull-up transistor.
4. The gate driver of claim 1 , further comprises a sixth transistor controlled by the QB-node, the sixth transistor being connected between the gate of the pull-up transistor and an input terminal being applied a gate-off voltage.
5. The gate driver of claim 3 , further comprises a seventh transistor controlled by an input terminal being applied a gate-on voltage, the seventh transistor being configured to divide a node connected to the gate electrode of the pull-up transistor into a Q1-node and a Q2 node.
6. The gate driver of claim 1 , further comprises a third capacitor connected between the gate electrode of the pull-up transistor and an output terminal outputting an output signal of the gate driver.