Pixel circuit, display unit, and pixel circuit drive method

A display device comprising:

• a plurality of pixel circuits arranged in a matrix;
• a data line arranged for each column of said matrix of pixel circuits, the data line supplying a data signal in accordance with luminance information to the pixel circuits;
• a first control line arranged for each row of said matrix of pixel circuits;
• and
• first and second reference potentials,
• wherein each pixel circuit includes
• an electro-optic element having a luminance variation according to current flow,
• a drive transistor configured to control a current flowing from the first reference potential to the electro-optic element connected to the drive transistor via a first node, the current flowing through the drive transistor in accordance with a control voltage applied to a gate of the drive transistor via the second node connected thereto,
• a pixel capacitance element connected between said first node and said second node, the pixel capacitance maintaining a constant voltage between the first and second nodes when the electro-optic element is emitting light,
• a first switch connected between said data line and said second node, the first control line controlling conduction of the first switch, and
• a first circuit configured to disconnect said first node from the drive transistor when said electro-optic element is in a first non-emitting state, the first circuit being controlled by a second control line, the first node being at a second reference potential when disconnected from the drive transistor, and
• a second circuit configured to hold said first node at a predetermined potential other than the first or second reference potentials when the electro-optic element is in a second non-emitting state, the second circuit being controlled by a third control line separate from the second control line,
• said current supply line of the drive transistor, said first node, and said electro-optic element being connected in series between said first reference potential and second reference potential,
• the first switch, first circuit and second circuit being held in non-conductive states during the first non-emitting state of the electro-optic element,
• the first switch, and second circuit being held in a conductive state and the first circuit being held in a non-conductive state during the second non-emitting state of the electro-optic element.

A method of driving a pixel circuit including an electro-optic element having a luminance variation according to current flow, comprising:

• supplying data to the pixel circuit via a data line, the data corresponding to luminance information;
• controlling a current flowing through a drive transistor in accordance with a control voltage applied to a gate of the drive transistor, the gate of the drive transistor being connected to a second node, the source of the drive transistor being connected to the electro-optic element via a first node;
• maintaining a constant voltage between the first and second nodes using a pixel capacitance element when the electro-optic element emits light, the pixel capacitance being connected between the first and second nodes;
• controlling a conductance of a first switch connected between the data line and the second node in accordance with a first control line;
• disconnecting the first node from the drive transistor when the electro-optic element is in a first non-emitting state, the drive transistor, first node and electro-optic element being connected in series between the first and second reference potentials, the first node being at a second reference potential when disconnected from the drive transistor;
• changing a potential of said first node to a fixed potential via said first circuit when the electro-optic element is in a second non-emitting state;
• holding said first switch at a conductive state when writing data propagated over said data line to said pixel capacitance element;
• connecting the first node to a predetermined potential other than the first or second reference potentials via a second circuit and in accordance with a third control line separate from the second control line;
• holding said first switch in the non-conductive after writing the data to the pixel capacitance element;
• and
• releasing, via the first circuit, the potential of said first node from the fixed potential, wherein the first switch, first circuit and second circuit are held in non-conductive states during the first non-emitting state of the electro-optic element, and the first switch and second circuit are held in conductive states and the first circuit is held in a non-conductive state during the second non-emitting state of the electro-optic element.