Pixel circuit, display device, driving method of pixel circuit, and driving method of display device

A display device comprising:

• scanning lines arranged in rows;
• signal lines arranged in columns;
• and
• pixel circuits arranged in a form of a matrix at parts where said scanning lines intersect said signal lines;
• said pixel circuits each including at least an electrooptic element, a drive transistor, a sampling transistor, and a retaining capacitance;
• said drive transistor having a gate connected to an input node, a source connected to an output node, and a drain connected to a predetermined power supply potential;
• said electrooptic element having one terminal connected to said output node and another terminal connected to a predetermined potential;
• said sampling transistor being connected between said input node and said signal line;
• said retaining capacitance being connected to said input node;
• said sampling transistor operating when selected by said scanning line, sampling an input signal from said signal line, and retaining the input signal in said retaining capacitance;
• said drive transistor supplying a driving current to said electrooptic element according to a signal potential retained in said retaining capacitance, whereby display is made;
• said pixel circuits each further including a compensating circuit configured to compensate for a decrease in the magnitude of the driving current that is generated by the drive transistor for a given input signal, the decrease being caused by a secular change of said drive transistor;
• said compensating circuit including:
• a detecting section configured to accumulate charge carried by said driving current for a certain period of time and to output a detection potential corresponding to an amount of charge accumulated, and
• a feedback section configured to obtain a difference by comparing a magnitude of said input signal with a magnitude of said detection potential and to add a potential corresponding to said difference to said signal potential retained in said retaining capacitance.

A driving method of a pixel circuit disposed at a part where a scanning line and a signal line intersect each other, said pixel circuit including at least an electrooptic element, a drive transistor, a sampling transistor, and a retaining capacitance, said drive transistor having a gate connected to an input node, a source connected to an output node, and a drain connected to a predetermined power supply potential, said electrooptic element having one terminal connected to said output node and another terminal connected to a predetermined potential, said sampling transistor being connected between said input node and said signal line, said retaining capacitance being connected to said input node, said driving method comprising the steps of:

• said sampling transistor operating when selected by said scanning line, sampling an input signal from said signal line, and retaining the input signal in said retaining capacitance;
• said drive transistor supplying a driving current to said electrooptic element according to a signal potential retained in said retaining capacitance;
• performing a compensation operation that compensates for a decrease in the magnitude of the driving current that is generated by the drive transistor for a given input signal, the decrease being caused by a secular change of said drive transistor,
• said compensating operation comprising:
• accumulating charge carried by said driving current for a certain period of time and obtaining a detection potential corresponding to an amount of charge accumulated;
• and
• obtaining a difference by comparing a magnitude of said input signal with a magnitude of said detection potential and adding a potential corresponding to said difference to said signal potential retained in said retaining capacitance.

A driving method of a display device, said display device including scanning lines in a form of rows, signal lines in a form of columns, and pixel circuits arranged in a form of a matrix at parts where said scanning lines intersect said signal lines, said pixel circuits each including at least an electrooptic element, a drive transistor, a sampling transistor, and a retaining capacitance, said drive transistor having a gate connected to an input node, a source connected to an output node, and a drain connected to a predetermined power supply potential, said electrooptic element having one terminal connected to said output node and another terminal connected to a predetermined potential, said sampling transistor being connected between said input node and said signal line, said retaining capacitance being connected to said input node, said driving method comprising the steps of:

• when said sampling transistor operates when selected by said scanning line, samples an input signal from said signal line, and retains the input signal in said retaining capacitance, and
• said drive transistor supplies a driving current to said electrooptic element according to a signal potential retained in said retaining capacitance, whereby display is made,
• performing a compensation operation that compensates for a decrease in said driving current that is caused by a secular change of said drive transistor by detecting a decrease in said driving current from a side of said output node, and feeding back a result of detection to a side of said input node,
• said compensating operation comprising:
• accumulating charge carried by said driving current for a certain period of time and obtaining a detection potential corresponding to an amount of charge accumulated;
• and
• obtaining a difference by comparing a magnitude of said input signal with a magnitude of said detection potential and adding a potential corresponding to said difference to said signal potential retained in said retaining capacitance.