Semiconductor device

Abstract

A semiconductor device in which a reduction in size and thinness are realized is provided. The semiconductor device of the present invention can realize a reduction in size by forming light emitting elements as a light source, and photodiodes as photoelectric conversion elements on the same substrate. Further, it becomes possible to control two signal lines by using one driver circuit with using an output switching circuit. As a result, it becomes possible to reduce the area occupied by the driver circuits of the semiconductor device, and the semiconductor device can be made smaller.

1 . (canceled) 
     
     
         2 . A semiconductor device comprising:
 a first and a second signal lines;   third signal lines;   a display portion;   liquid crystal element portions in the display portion, each liquid crystal element portion comprising a pixel electrode and a transistor with a gate electrically connected to the first signal line and one of a source and a drain electrically connected to one of the third signal lines;   a sensor portion in the display portion, the display portion including a sensor, the sensor including a sensor electrode; and   a liquid crystal layer over one of the pixel electrodes,   wherein the one of the pixel electrodes is over the sensor electrode,   wherein the sensor portion is electrically connected to the second signal line, and   wherein the sensor portion is shared by a plurality of the liquid crystal element portions.   
     
     
         3 . The semiconductor device according to  claim 2 ,
 wherein the semiconductor device is configured so that in a first period:
 a first pulse signal is input into the first signal line, and 
 a first constant potential is applied to the second signal line, and 
   wherein the semiconductor device is configured so that in a second period:
 a second constant potential is applied to the first signal line, 
 a second pulse signal is input into the second signal line, and a signal is output from the sensor portion. 
   
     
     
         4 . A semiconductor device comprising:
 a first to a fourth signal lines;   a display portion;   a first liquid crystal element portion in the display portion, the first liquid crystal element portion comprising a first pixel electrode and a first transistor with a gate electrically connected to the first signal line;   a second liquid crystal element portion in the display portion, the second liquid crystal element portion comprising a second pixel electrode and a second transistor with a gate electrically connected to the first signal line;   a sensor portion in the display portion, the sensor portion including a sensor, the sensor including a sensor electrode; and   a liquid crystal layer over the first pixel electrode,   wherein the first pixel electrode is over the sensor electrode,   wherein one of a source and a drain of the first transistor and one of a source and a drain of the second transistor are electrically connected to the third and to the fourth signal lines, respectively,   wherein the sensor portion is electrically connected to the second signal line, and   wherein the sensor portion overlaps with each of the third and the fourth signal lines.   
     
     
         5 . A semiconductor device comprising:
 a first to a fourth signal lines;   a display portion;   a first liquid crystal element portion in the display portion, the first liquid crystal element portion comprising a first pixel electrode and a first transistor with a gate electrically connected to the first signal line;   a second liquid crystal element portion in the display portion, the second liquid crystal element portion comprising a second pixel electrode and a second transistor with a gate electrically connected to the first signal line;   a sensor portion in the display portion, the sensor portion including a sensor, the sensor including a sensor electrode; and   a liquid crystal layer over the first pixel electrode,   wherein the first pixel electrode is over the sensor electrode,   wherein one of a source and a drain of the first transistor and one of a source and a drain of the second transistor are electrically connected to the third and to the fourth signal lines, respectively,   wherein the sensor portion is electrically connected to the second signal line,   wherein the sensor portion overlaps with each of the third and the fourth signal lines,   wherein the semiconductor device is configured so that in a first period:
 a first pulse signal is input into the first signal line, and 
 a first constant potential is applied to the second signal line, and 
   wherein the semiconductor device is configured so that in a second period:
 a second constant potential is applied to the first signal line, 
 a second pulse signal is input into the second signal line, and a signal is output from the sensor portion. 
   
     
     
         6 . The semiconductor device according to  claim 2 ,
 wherein the sensor is a photodiode.   
     
     
         7 . The semiconductor device according to  claim 4 ,
 wherein the sensor is a photodiode.   
     
     
         8 . The semiconductor device according to  claim 5 ,
 wherein the sensor is a photodiode.   
     
     
         9 . The semiconductor device according to  claim 2 ,
 wherein the sensor portion comprises a transistor in the display portion.   
     
     
         10 . The semiconductor device according to  claim 4 ,
 wherein the sensor portion comprises a transistor in the display portion.   
     
     
         11 . The semiconductor device according to  claim 5 ,
 wherein the sensor portion comprises a transistor in the display portion.   
     
     
         12 . The semiconductor device according to  claim 2 ,
 wherein a circuit driving the sensor portion comprises transistor in a same plane as the transistors of the liquid crystal element portions.   
     
     
         13 . The semiconductor device according to  claim 4 ,
 wherein a circuit driving the sensor portion comprises transistor in a same plane as the transistors of the liquid crystal element portions.   
     
     
         14 . The semiconductor device according to  claim 5 ,
 wherein a circuit driving the sensor portion comprises transistor in a same plane as the transistors of the liquid crystal element portions.