Patent ID: 9379138
Filing Date: 2016-06-28
CPC Classification: H01L

Claim Text:
1. A semiconductor device comprising: a light-receiving element; a first transistor; a second transistor; a third transistor; a CPU; and a controller, wherein one of electrodes of the light-receiving element is electrically connected to a node, wherein one of a source electrode and a drain electrode of the first transistor is electrically connected to the node, wherein a gate of the second transistor is electrically connected to the node, wherein one of a source and a drain of the third transistor is electrically connected to one of a source and a drain of the second transistor, wherein the other of the source and the drain of the third transistor is electrically connected to a wiring, wherein the wiring is electrically connected to the CPU, wherein the CPU is electrically connected to the controller, wherein the controller is electrically connected to a gate of the first transistor, wherein the first transistor comprises an oxide semiconductor layer in a channel formation region, wherein an oxide layer containing oxygen at a proportion higher than a stoichiometric composition is located over the source electrode, the drain electrode and the oxide semiconductor layer, wherein the CPU is configured to select a first driving method in which a third potential which is higher than a first potential and lower than a second potential is supplied to the gate of the first transistor in accordance with an external light intensity, wherein the controller is configured to supply the third potential to the gate of the first transistor in accordance with a result of a selection of the CPU, wherein the first potential makes the first transistor be in an off state, and wherein the second potential makes the first transistor be in an on state.