Gate signal line driving circuit and display device with suppression of changes in the threshold voltage of the switching elements

A display device comprising:

• a display panel;
• and
• a gate signal line driving circuit which is formed in a display panel so as to output a scanning signal to the display panel, the gate signal line driving circuit including a plurality of stages of fundamental circuits, each of the fundamental circuits including,
• an ON-voltage output element,
• a first node connected to a control terminal of the ON-voltage output element,
• a first switching element which supplies a high voltage to the first node in accordance with an output signal from a fundamental circuit at a previous stage;
• a second switching element which supplies a low voltage to the first node in accordance with an output signal from a fundamental circuit at a next stage,
• first and second OFF-voltage output elements,
• a second node electrically connected to the control terminals of the first and second OFF-voltage output elements,
• a third switching element the control terminal of which is connected to a clock signal and which supplies a high voltage to the second node,
• a fourth switching element the control terminal of which is connected to the first node and which supplies a low voltage to the second node,
• fifth and sixth switching elements the control terminals of which are electrically connected to the second node and which supply a low voltage to the first node when the fifth and sixth switching elements are in the ON state,
• a first control switching element which electrically disconnects the control terminal of the first OFF-voltage output element and the second node in the first period and which electrically connects the control terminal of the first OFF-voltage output element and the second node in the second period,
• a second control switching element which supplies a low voltage to the control terminal of the first OFF-voltage output element in the first period,
• a third control switching element which electrically disconnects the control terminal of the second OFF-voltage output element and the second node in the first period and which electrically connects the control terminal of the second OFF-voltage output element and the second node in the second period, and
• a fourth control switching element which supplies a low voltage to the control terminal of the second OFF-voltage output element in the second period,
• wherein the first node is changed so as to have a high voltage by the first switching element, the ON-voltage output element outputs an ON voltage, and the fourth switching element changes the second node so as to have a low voltage,
• wherein the first and second OFF-voltage output elements are put into the OFF state by the second node being at a low voltage,
• wherein the first node is changed so as to have a low voltage by the second switching element, the ON-voltage output element is put into the OFF state, and the fourth switching element is put into the OFF state, whereby the second node is charged to a high voltage by the third switching element,
• wherein the second node is changed so as to have a high voltage, whereby the first and second OFF-voltage output elements are put into the ON state to output an OFF voltage, and the fifth and sixth switching elements supply a low voltage to the first node, and
• wherein the first to fourth control switching elements are put into the ON state in a third period to supply a high voltage to the second node.