Patent ID: 8664581

Claim:
An input/output device comprising: a pixel area including a first light emission circuit, a second light emission circuit, and a photodetection circuit, wherein the photodetection circuit is configured to generate a voltage having a value corresponding to an intensity of incident light, each of the first light emission circuit and the second light emission circuit comprising: a drive transistor comprising a source, a drain, and a gate; and a light emitting element comprising a first current terminal and a second current terminal, wherein the first current terminal is electrically connected to the source or the drain of the drive transistor, wherein a first voltage is input to the second current terminal, and wherein the light emitting element emits light in accordance with a current flowing between the first current terminal and the second current terminal; the second light emission circuit comprising: a switching element comprising a first terminal and a second terminal, wherein a second voltage is input to the first terminal, wherein the second terminal is electrically connected to the first current terminal of the light emitting element, and wherein, when an object to be detected is over the pixel area, light emitted from the second light emission circuit is reflected by the object to be detected, and light reflected by the object to be detected enters the photodetection circuit.