Driving circuit of display element and image display apparatus

A driving circuit of a display element for performing a driving control including a first period for setting a current to be supplied to the display element, a second period for setting a gray-scale of the display element, and a third period for supplying a driving current to the display element, comprising:

• a current source circuit having a first transistor and a holding circuit for holding a gate voltage of the first transistor during the first period at the voltage corresponding to a constant current to be supplied to the display element;
• and
• a control circuit including a second transistor for switching the current to the display element from the current source circuit, a third transistor whose one terminal is connected to a gate of the second transistor, and a capacitor element whose one end is connected to a gate of the third transistor and the other end is connected to a line, and controlling a light emission time of the display element by controlling the second transistor during the third period,
• wherein, during the second period, a constant voltage is applied from the line, and after that, a gray-scale voltage is applied, and an electric charge is accumulated in the capacitor element based on the difference between the gray-scale voltage and a threshold value voltage of the third transistor, and
• wherein, during the third period, an ON voltage to turn on the second transistor is applied to the gate of the second transistor through the third transistor, and after that, a sweep voltage is applied to the capacitor element, so that the ON time of the second transistor is controlled.

A driving circuit of a display element having a first period for setting a current to be supplied to the display element, a second period for setting a gray-scale of the display element, and a third period for supplying a driving current to the display element, comprising:

• a current source circuit having a first transistor and a holding circuit for holding a gate voltage of the first transistor during the first period at an electric potential corresponding to a constant current to be supplied to the display element, and
• a control circuit including a second transistor connected in series to the first transistor and a capacitor element whose one end is connected a gate of the second transistor and the other end is connected to a line, and controlling a light emission time of the display element by controlling the second transistor during the third period,
• wherein, during the second period, an electric charge based on the difference between a gray-scale voltage supplied to the capacitor element from the line and a gate voltage of the second transistor is accumulated, and
• wherein a sweep voltage is applied to the capacitor element from the line during the third periods, so that the ON time of the second transistor is controlled.

A driving circuit of a display element having a first period for setting a current to be supplied to the display element, a second period for setting a gray-scale of the display element, and a third period for supplying a driving current to the display element, comprising:

• a current source circuit having a first transistor and a holding circuit for holding a gate voltage of the first transistor during the first period at an electric potential corresponding to a constant current to be supplied to the display element, and
• a control circuit including a second transistor connected in series to the current source circuit and connected in parallel to the display element and the capacitor element whose one terminal is connected to gate of the second transistor and the other terminal is connected to a line, and controlling the light emission time of the display element by controlling the second transistor during the third period,
• wherein a constant voltage is applied from the line during the first period, wherein the gray-scale voltage is applied from the line during the second period, and moreover, a gate of the second transistor and the one terminal are short-circuited, and an electric charge based on the difference between the gray-scale voltage and the gate voltage of the second transistor is accumulated in the capacitor element, and
• wherein a sweep voltage is applied during the third period, so that the ON time of the second transistor is controlled.

A driving circuit of a display element for performing a driving control including a first period for setting a current to be supplied to the display element, a second period for setting a gray-scale of the display element, and a third period for supplying a driving current to the display element, comprising:

• a current source circuit having a first transistor and a holding circuit for holding a gate voltage of the first transistor during the first period at the voltage corresponding to a constant current to be supplied to the display element;
• and
• a control circuit including a second transistor for switching the current to the display element from the current source circuit, a third transistor whose one terminal is connected to a control terminal of the second transistor, and a capacitor element whose one end is connected to a control terminal of the third transistor and the other end is connected to a line through a switch, and controlling the light emission time of the display element by controlling the second transistor during the third period,
• wherein, during the second period, an electric charge based on the difference between a gray-scale voltage supplied to the capacitor element from the line and a threshold voltage of the third transistor is accumulated, and
• wherein, during the third period, an ON voltage is applied to a gate of the second transistor, and at the same time, a sweep voltage is applied to the capacitor element, so that the ON time of the second transistor is controlled.

A driving circuit of a display element including a first period for setting a current to be supplied to the display element, a second period for setting a gray-scale of the display element, and a third period for supplying a driving current to the display element, comprising:

• a current source circuit having a holding circuit for holding a value corresponding to a constant current to be supplied to the display element during the first period;
• and
• a control circuit controlling a time of supplying the constant current to the display element from the current source circuit during the third period, according to a gray-scale voltage supplied during the second period,
• wherein the current source circuit includes at least a first transistor,
• wherein the control circuit includes a second transistor whose source and drain are connected in series between the current source circuit and the display element, whose gate is connected to one end of a capacitor element directly or through a switch, in which the constant current is in a sub threshold region of a gate voltage—drain current characteristic, and in which an OFF current is equal to or less than 0.1% of the constant current, and
• wherein, during the third period, the time of supplying the constant current to the display element is controlled by time-dependently changing a gate voltage of the second transistor and thus controlling an ON time between the source and the drain of the second transistor.

A driving circuit of a display element including a first period for setting a current to be supplied to the display element, a second period for setting a gray-scale of the display element, and a third period for supplying a driving current to the display element, comprising:

• a current source circuit having a holding circuit for holding a value corresponding to a constant current to be supplied to the display element during the first period;
• and
• a control circuit controlling a time of supplying the constant current to the display element from the current source circuit during the third period, according to a gray-scale voltage supplied during the second period,
• wherein the current source circuit includes at least a first transistor,
• wherein the control circuit includes a second transistor whose source and drain and the display element are connected in parallel with respect to the current source circuit, whose gate is connected to one end of a capacitor element directly or through a switch, in which the constant current is in a sub threshold region of a gate voltage—drain current characteristic, and in which an OFF current is equal to or less than 0.1% of the constant current, and
• wherein, during the third period, the time of supplying the constant current to the display element is controlled by time-dependently changing a gate voltage of the second transistor and thus controlling an OFF time between the source and the drain of the second transistor.