Imaging device, monitoring device, and electronic appliance

Abstract

A highly accurate imaging device or a highly accurate imaging device capable of detecting differences is provided. A configuration including a circuit in which variation in threshold voltage among amplifier transistors of pixels is corrected is employed. The configuration reduces variation in difference data due to variation in the threshold voltage among the amplifier transistors of the pixels to obtain highly accurate imaging data. Furthermore, charge corresponding to difference data between imaging data in an initial frame and imaging data in a current frame is accumulated in pixels and the difference data is read from each pixel, whereby highly accurate difference data is obtained when whether there is a difference between the initial frame and the current frame is determined.

1 . (canceled) 
     
     
         2 . An imaging device comprising:
 a pixel; and   an analog processing circuit electrically connected to an output of the pixel,   wherein the analog processing circuit is configured to detect a difference between a first image data and a second image data is zero or not.   
     
     
         3 . The imaging device according to  claim 2 ,
 wherein the pixel further comprises a plurality of transistors, and   wherein the pixel is configured to correct variation in threshold voltage among the plurality of transistors.   
     
     
         4 . The imaging device according to  claim 3 ,
 wherein the plurality of transistors each comprise a semiconductor layer, and   wherein the semiconductor layer comprises an oxide semiconductor.   
     
     
         5 . The imaging device according to  claim 2 ,
 wherein the pixel is configured to accumulate difference data between the first image data in a first frame and the second image data in a second frame.   
     
     
         6 . The imaging device according to  claim 2 ,
 wherein the analog processing circuit further comprises an adder circuit.   
     
     
         7 . A monitoring device comprising:
 a camera comprising the imaging device according to  claim 2 ;   a display device functionally connected to the camera;   a memory device functionally connected to the camera; and   an alarm device functionally connected to the camera.   
     
     
         8 . An electronic appliance comprising:
 the monitoring device according to  claim 7 ; and   an operation key.   
     
     
         9 . An imaging device comprising:
 a pixel comprising a sensor; and   an analog processing circuit electrically connected to an output of the pixel,   wherein the analog processing circuit is configured to detect a difference between a first image data and a second image data is zero or not.   
     
     
         10 . The imaging device according to  claim 9 ,
 wherein the pixel further comprises a plurality of transistors, and   wherein the pixel is configured to correct variation in threshold voltage among the plurality of transistors.   
     
     
         11 . The imaging device according to  claim 10 ,
 wherein the plurality of transistors each comprise a semiconductor layer, and   wherein the semiconductor layer comprises an oxide semiconductor.   
     
     
         12 . The imaging device according to  claim 9 ,
 wherein the pixel is configured to accumulate difference data between the first image data in a first frame and the second image data in a second frame.   
     
     
         13 . The imaging device according to  claim 9 ,
 wherein the analog processing circuit further comprises an adder circuit.   
     
     
         14 . A monitoring device comprising:
 a camera comprising the imaging device according to  claim 9 ;   a display device functionally connected to the camera;   a memory device functionally connected to the camera; and   an alarm device functionally connected to the camera.   
     
     
         15 . An electronic appliance comprising:
 the monitoring device according to  claim 14 ; and   an operation key.   
     
     
         16 . The imaging device according to  claim 9 ,
 wherein the sensor is configured to generate photoelectric converted signal charge.