Patent ID: 8339531
Filing Date: 2012-12-25
Classification: G09G

Abstract:
1. A display device, having a pixel circuit group provided by arranging a plurality of pixel circuits, wherein the pixel circuit includes: a display element unit including a unit display element; an internal node that is a part of the display element unit and holds a voltage of pixel data applied to the display element unit; a first switch circuit that transfers the voltage of the pixel data supplied from a data signal line to the internal node through at least a predetermined switch element; a second switch circuit that transfers a voltage supplied to a predetermined voltage supply line to the internal node without passing through the predetermined switch element; and a control circuit that holds a predetermined voltage depending on the voltage of the pixel data held by the internal node at one end of a first capacitor element and controls on/off of the second switch circuit, the second switch circuit includes a first transistor element and a third transistor element, the control circuit includes a second transistor element, and each of the first to third transistor elements has a first terminal, a second terminal, and a control terminal that controls conduction between the first and second terminals, the second switch circuit is configured by a series circuit of the first transistor element and the third transistor element, the control circuit is configured by a series circuit of the second transistor element and the first capacitor element, one end of the first switch circuit is connected to the data signal line, one end of the second switch circuit is connected to the voltage supply line, the other ends of the first and second switch circuits and the first terminal of the second transistor element are connected to the internal node, the control terminal of the first transistor element, the second terminal of the second transistor element, and one end of the first capacitor element are connected to each other to form an output node of the control circuit, the control terminal of the second transistor element is connected to a first control line, the control terminal of the third transistor element is connected to a second control line, the other end of the first capacitor element is connected to the third control line, the predetermined switch element is a fourth transistor element having a first terminal, a second terminal, and a control terminal that controls conduction between the first and second terminals, and the control terminal is connected to a scanning signal line, a data signal line drive circuit that independently drives the data signal lines, a control line drive circuit that independently drives the first and second control lines, and a scanning signal line drive circuit that drives the scanning signal line are provided, in a self-refresh action for compensating for a voltage change of the internal nodes at the same time by operating the second switch circuits and the control circuits in the plurality of pixel circuits, the scanning signal line drive circuit applies a predetermined voltage to the scanning signal lines connected to all the pixel circuits included in the pixel circuit group to turn off the fourth transistor elements, the control line drive circuit applies a predetermined voltage to the second control line to turn off the third transistor element, and applies a first control voltage to the first control line such that when a voltage state of binary pixel data held by the internal node is in a first voltage state, a current flowing from one end of the first capacitor element to the internal node is cut off by the second transistor element, and when the voltage state is in a second voltage state, the second transistor element is turned on, thereafter, the control line drive circuit applies a first boost voltage to the third control line to give a voltage change caused by capacitive coupling through the first capacitor element to one end of the first capacitor element, so that when the voltage of the internal node is in the first voltage state, the voltage change is not suppressed and the first transistor element is turned on, thereafter, the control line drive circuit changes an applied voltage to the first control line into a second control voltage, so that a current flowing from one end of the first capacitor element to the internal node is cut off by the second transistor element regardless of whether the voltage state of the internal node is in the first voltage state or the second voltage state, thereafter, the control line drive circuit changes an applied voltage to the third control line into a second boost voltage that is closer to a ground voltage than the first boost voltage to give a voltage change caused by capacitive coupling through the first capacitor element to one end of the first capacitor element so as to shift a potential of the output node toward the ground potential, so that when the voltage state of the internal node is in the first voltage state, the first transistor element is continuously turned on, and when the voltage state is in the second voltage state, the first transistor element is turned off, and, thereafter, the control line drive circuit changes an applied voltage to the second control line to turn on the third transistor element so as to supply the voltage of the pixel data in the first voltage state to all the voltage supply lines connected to the plurality of pixel circuits targeted by the self-refresh action.