Display device and driving method of display device

Abstract

A display device that can switch between normal display and see-through display is provided. Visibility in see-through display is improved. A liquid crystal element overlaps with a light-emitting element. The light-emitting element, a transistor, and the like overlapping with the liquid crystal element transmit visible light. When the liquid crystal element blocks external light, an image is displayed with the light-emitting element. When the liquid crystal element transmits external light, an image displayed with the light-emitting element is superimposed on a transmission image through the liquid crystal element.

1 . A display device comprising:
 a light-emitting element;   a first transistor electrically connected to the light-emitting element; and   a liquid crystal element overlapping with the first transistor,   wherein the first transistor includes a first gate electrode, a first semiconductor layer, a first source electrode, and a first drain electrode,   wherein at least one of the first gate electrode, the first semiconductor layer, the first source electrode, and the first drain electrode is configured to transmit visible light,   wherein the light-emitting element includes a first electrode, a second electrode, and a light-emitting layer between the first electrode and the second electrode,   wherein the first electrode and the second electrode are each configured to transmit visible light, and   wherein the liquid crystal element transmits light when applied with an electric field, and blocks light when not applied with an electric field.   
     
     
         2 . The display device according to  claim 1 , wherein at least one of the first semiconductor layer, the first gate electrode, the first source electrode, and the first drain electrode includes a metal oxide. 
     
     
         3 . The display device according to  claim 1 , further comprising:
 a second transistor electrically connected to and overlapping with the liquid crystal element,   wherein the second transistor includes a second gate electrode, a second semiconductor layer, a second source electrode, and a second drain electrode, and   wherein at least one of the second gate electrode, the second semiconductor layer, the second source electrode, and the second drain electrode is configured to transmit visible light.   
     
     
         4 . The display device according to  claim 3 , wherein the first transistor and the second transistor are on the same plane. 
     
     
         5 . The display device according to  claim 1 , wherein the liquid crystal element is a passive matrix liquid crystal element or a segment liquid crystal element. 
     
     
         6 . The display device according to  claim 1 , further comprising:
 a first substrate;   a second substrate; and   an insulating layer;   wherein the insulating layer is between the first substrate and the second substrate,   wherein the light-emitting element is between the first substrate and the insulating layer,   wherein the liquid crystal element is between the second substrate and the insulating layer, and   wherein at least one of the first gate electrode, the first semiconductor layer, the first source electrode, and the first drain electrode of the first transistor is in contact with the insulating layer.   
     
     
         7 . The display device according to  claim 6 , further comprising:
 a wiring electrically connected to the liquid crystal element,   wherein the first transistor and the wiring are between the insulating layer and the first substrate, and   wherein the wiring is electrically connected to the liquid crystal element in an opening in the insulating layer.   
     
     
         8 . The display device according to  claim 7 , further comprising a second transistor electrically connected to the wiring. 
     
     
         9 . The display device according to  claim 7 , wherein the wiring is configured to transmit visible light. 
     
     
         10 . The display device according to  claim 1 , further comprising:
 a first wiring; and   a second wiring intersecting with the first wiring,   wherein the first wiring is electrically connected to the first gate electrode of the first transistor,   wherein the second wiring is electrically connected to one of the first source electrode and the first drain electrode of the first transistor, and   wherein the first wiring and the second wiring are each configured to block visible light.   
     
     
         11 . The display device according to  claim 1 , further comprising:
 a first wiring; and   a second wiring intersecting with the first wiring,   wherein the first wiring is electrically connected to the first gate electrode of the first transistor,   wherein the second wiring is electrically connected to one of the first source electrode and the first drain electrode of the first transistor, and   wherein the first wiring and the second wiring are each configured to transmit visible light.   
     
     
         12 . A display device comprising:
 a liquid crystal element;   a first transistor over and overlapping with the liquid crystal element;   a light-emitting element over and electrically connected to the first transistor; and   a display surface over the light-emitting element,   wherein the light-emitting element includes a first electrode, a second electrode, and a light-emitting layer between the first electrode and the second electrode,   wherein the first electrode and the second electrode are each configured to transmit visible light, and   wherein the liquid crystal element transmits light when applied with an electric field, and blocks light when not applied with an electric field.   
     
     
         13 . The display device according to  claim 12 ,
 wherein the first transistor includes a first gate electrode, a first semiconductor layer, a first source electrode, and a first drain electrode, and   wherein at least one of the first semiconductor layer, the first gate electrode, the first source electrode, and the first drain electrode is configured to transmit visible light.   
     
     
         14 . The display device according to  claim 12 ,
 wherein the first transistor includes a first gate electrode, a first semiconductor layer, a first source electrode, and a first drain electrode, and   wherein at least one of the first semiconductor layer, the first gate electrode, the first source electrode, and the first drain electrode includes a metal oxide.   
     
     
         15 . The display device according to  claim 12 , further comprising:
 a second transistor electrically connected to and overlapping with the liquid crystal element,   wherein the second transistor includes a second gate electrode, a semiconductor layer, a second source electrode, and a second drain electrode, and   wherein at least one of the second gate electrode, the semiconductor layer, the second source electrode, and the second drain electrode is configured to transmit visible light.   
     
     
         16 . The display device according to  claim 15 , wherein the first transistor and the second transistor are on the same plane. 
     
     
         17 . The display device according to  claim 12 , wherein the liquid crystal element is a passive matrix liquid crystal element or a segment liquid crystal element. 
     
     
         18 . The display device according to  claim 12 , further comprising:
 a first substrate;   a second substrate, and   an insulating layer;   wherein the insulating layer is between the first substrate and the second substrate,   wherein the light-emitting element is between the first substrate and the insulating layer,   wherein the liquid crystal element is between the second substrate and the insulating layer,   wherein the first transistor includes a first gate electrode, a first semiconductor layer, a first source electrode, and a first drain electrode, and   wherein at least one of the first gate electrode, the first semiconductor layer, the first source electrode, and the first drain electrode of the first transistor is in contact with the insulating layer.   
     
     
         19 . The display device according to  claim 18 , further comprising:
 a wiring electrically connected to the liquid crystal element,   wherein the first transistor and the wiring are between the insulating layer and the first substrate, and   wherein the wiring is electrically connected to the liquid crystal element in an opening in the insulating layer.   
     
     
         20 . The display device according to  claim 19 , further comprising a second transistor electrically connected to the wiring. 
     
     
         21 . The display device according to  claim 19 , wherein the wiring is configured to transmit visible light. 
     
     
         22 . The display device according to  claim 12 , further comprising:
 a first wiring; and   a second wiring intersecting with the first wiring,   wherein the first transistor includes a first gate electrode, a first semiconductor layer, a first source electrode, and a first drain electrode,   wherein the first wiring is electrically connected to the first gate electrode of the first transistor,   wherein the second wiring is electrically connected to one of the first source electrode and the first drain electrode of the first transistor, and   wherein the first wiring and the second wiring are each configured to block visible light.   
     
     
         23 . The display device according to  claim 12 , further comprising:
 a first wiring; and   a second wiring intersecting with the first wiring,   wherein the first transistor includes a first gate electrode, a first semiconductor layer, a first source electrode, and a first drain electrode,   wherein the first wiring is electrically connected to the first gate electrode of the first transistor,   wherein the second wiring is electrically connected to one of the first source electrode and the first drain electrode of the first transistor, and   wherein the first wiring and the second wiring are each configured to transmit visible light.