Display device and electronic device

摘要

To suppress enlargement of pixel area even in the case of reducing current supplied to an electroluminescent element. A switch transistor, a first driving transistor, an electroluminescent element, and a second driving transistor provided between the first driving transistor and the electroluminescent element are included. A power supply potential is supplied to a gate of the second driving transistor. Drain current of the second driving transistor is controlled by the first driving transistor and the second driving transistor, so that a value of current supplied to the electroluminescent element is controlled.

主权项

1. A display device comprising:
a pixel comprising a first transistor, a second transistor, a third transistor, an electroluminescent element, and a capacitor; a data signal line; a capacitor line; and a semiconductor layer, wherein a first terminal of the first transistor is electrically connected to a first terminal of the second transistor, wherein a second terminal of the second transistor is electrically connected to a first terminal of the electroluminescent element, wherein a gate of the first transistor is electrically connected to a first terminal of the capacitor, wherein a first terminal of the third transistor is electrically connected to the gate of the first transistor, wherein a second terminal of the third transistor is electrically connected to the data signal line, wherein the semiconductor layer includes the first terminal of the capacitor and a channel formation region of the third transistor, wherein the capacitor line includes a second terminal of the capacitor, wherein the second transistor is configured to operate in a saturation region to supply a current Id to the electroluminescent element when the first transistor operates in a linear region by controlling a voltage supplied to a gate of the second transistor, wherein the Id is defined by:Id<12⁢WL1+L2⁢μ⁢⁢Cox⁡(Vg-Vth)2, where L1 is a channel length of the first transistor, L2 is a channel length of the second transistor, W is each of channel widths of the first transistor and the second transistor, μ is each of field-effect mobilities of the first transistor and the second transistor, Vg is a voltage supplied to a gate of the first transistor, Vth is a threshold voltage of the first transistor, Cox is a sum of gate capacitances of the first transistor and the second transistor, wherein an amount of the current Id is controlled in accordance with a data signal supplied to the gate of the first transistor, and wherein the data signal line and the capacitor line overlap each other.