Pixel circuit and display device

摘要

[Problem to be solved] Obtain a constitution for a data driver which does not easily affected by transistor characteristics. [Solution] A plurality of coupling capacitances 7 is connected to data enable lines which is equipped to at least two set potentials. A plurality of bit transistors 6 which is turned on and off in accordance with the display data of a plurality of bits controls the relation of connection between a plurality of coupling capacitances and data enable lines to control the total capacitance of the said plurality of coupling capacitances. Display element operates in accordance with the voltage accumulated to the total capacitance of the said coupling capacitance according to the difference between the two set potentials equipped to the data enable line. By the operations above, a display is controlled by multi-bit display data per each pixel.

主权项

1. A circuit of a display device for driving a first and a second organic EL element in which display brightness is controlled by display data having six bits, comprising:
three coupling capacitors connected to a data enable line; three bit transistors, wherein a first terminal of each bit transistor is electrically connected to a bit line, each bit line conveying one high-order bit or one low-order bit of the display data, and a second terminal of each bit transistor is electrically connected to a corresponding one of the three coupling capacitors; a first selection transistor with a first terminal electrically connected to a first select line and a second terminal electrically connected to a third terminal of all of the bit transistors; a second selection transistor with a first terminal electrically connected to a second select line and a second terminal electrically connected to the third terminal of all of the bit transistors; a first reset transistor with a first terminal electrically connected to a first reset line and a second terminal electrically connected to the third terminal of all of the bit transistors; a second reset transistor with a first terminal electrically connected to a second reset line and a second terminal electrically connected to the third terminal of all of the bit transistors; a first driving transistor with a first terminal electrically connected to a third terminal of the first selection transistor and a second terminal electrically connected to a power supply line; a second driving transistor with a first terminal electrically connected to a third terminal of the second selection transistor and a second terminal electrically connected to the power supply line; a first retentive capacitor with a first terminal electrically connected to the first terminal of the first driving transistor and a second terminal electrically connected to the second terminal of the first driving transistor; a second retentive capacitor with a first terminal electrically connected to the first terminal of the first driving transistor and a second terminal electrically connected to the second terminal of the second driving transistor; a first light emission control transistor with a first terminal electrically connected to a first light emission control line, a second terminal electrically connected to a third terminal of the first driving transistor, and a third terminal electrically connected to a first terminal of the first organic EL element; a second light emission control transistor with a first terminal electrically connected to a second light emission control line, a second terminal electrically connected to a third terminal of the second driving transistor, and a third terminal electrically connected to a first terminal of the second organic EL element; wherein either a channel width of the first driving transistor is eight times the channel width of the second driving transistor or a channel length of the first driving transistor is one-eighth the channel length of the second driving transistor; and wherein a voltage corresponding to a threshold voltage of the first driving transistor is retained by the first retention capacitor during a first period when the first light emission control transistor is turned off, the first reset transistor is turned on, and the data enable line is switched between two set voltages, and then, during a second period, a voltage accumulated to the total capacity of the plurality of coupling capacitors according to the difference between the two set voltages applied to the data enable line is applied to the gate of the first driving transistor by the first selection transistor and wherein a voltage corresponding to a threshold voltage of the second driving transistor is retained by the second retention capacitor during a third period when the second light emission control transistor is turned off, the second reset transistor is turned on, and the data enable line is switched between two set voltages, and then, during a fourth period, a voltage accumulated to the total capacity of the plurality of coupling capacitors according to the difference between the two set voltages applied to the data enable line is applied to the gate of the second driving transistor by the second selection transistor.