Light-emitting element display device

Abstract

A light-emitting element display device includes a substrate, one or a plurality of thin film transistors, a light-emitting element, a first electrode, and a second electrode. The substrate includes an insulating material. The thin film transistors are in each pixel of a display area on the substrate. The light-emitting element emits light by current flow in each pixel. The first electrode is between the substrate and the thin film transistors, and overlaps at least two of the thin film transistors when viewed in plan. The second electrode includes a conducting material, and is arranged across the first electrode from the substrate via an insulating film so as to form a capacitor together with the first electrode.

What is claimed is: 
     
         1 . A light emitting element display device comprising:
 a substrate;   a plurality of pixels in a display area on the substrate;   a plurality of thin film transistors in each of the plurality of pixels;   a light emitting element in each of the pixels; and   a capacitor including:
 a first electrode which is arranged between the substrate and a semiconductor layer of one of the plurality of thin film transistor and overlaps with the semiconductor layer in plan view; and 
 a second electrode between the first electrode and the semiconductor layer. 
   
     
     
         2 . The light emitting element display device according to  claim 1 , wherein the plurality of thin film transistors in each of the plurality of pixels includes:
 a pixel transistor controlling input of an applied voltage corresponding to a grayscale value to the capacitor; and   a driver transistor controlling light emission based on the applied voltage, and   wherein the second electrode is coupled to a gate of the driver transistor.   
     
     
         3 . The light emitting element display device according to  claim 2 , wherein the first electrode is coupled to one of a source and a drain of the driver transistor. 
     
     
         4 . The light emitting element display device according to  claim 1 , wherein the light emitting element includes:
 an anode;   an organic electroluminescence layer connected to the anode; and   a cathode connected on the organic electroluminescence layer,   wherein   the first electrode is coupled to the cathode, and   the second electrode is coupled to the anode.   
     
     
         5 . The light emitting element display device according to  claim 1 , wherein the first electrode spreads over two or more of the plurality of pixels. 
     
     
         6 . The light emitting element display device according to  claim 1 , wherein the first electrode is coupled to a reference potential. 
     
     
         7 . The light emitting element display device according to  claim 1 , further comprising a third electrode which is arranged on the second electrode and is coupled to the first electrode so as to form the capacitor together with the second electrode. 
     
     
         8 . The light emitting element display device according to  claim 2 , wherein each of the pixel transistor and the driver transistor overlaps with the first and the second electrodes. 
     
     
         9 . A light emitting element display device comprising:
 a substrate;   a plurality of pixels in a display area on the substrate;   a plurality of thin film transistors in each of the plurality of pixels;   a light emitting element in each of the pixels; and   a capacitor including:
 a semiconductor layer of one of the plurality of thin film transistors; and 
 a first electrode which is arranged between the substrate and the semiconductor layer and overlaps with the semiconductor layer in plan view. 
   
     
     
         10 . The light emitting element display device according to  claim 9 , wherein the plurality of thin film transistors in each of the plurality of pixels includes:
 a pixel transistor controlling input of an applied voltage corresponding to a grayscale value to the capacitor; and   a driver transistor controlling light emission based on the applied voltage, and   wherein the semiconductor layer is coupled to a gate of the driver transistor.   
     
     
         11 . The light emitting element display device according to  claim 10 , wherein the first electrode is coupled to one of a source and a drain of the driver transistor. 
     
     
         12 . The light emitting element display device according to  claim 9 , further comprising another capacitor including: a second electrode between the first electrode and the substrate; and the first electrode. 
     
     
         13 . The light emitting element display device according to  claim 12 , wherein the light emitting element includes:
 an anode;   an organic electroluminescence layer connected to the anode; and   a cathode connected on the organic electroluminescence layer,   wherein   the first electrode is coupled to the anode, and   the second electrode is coupled to the cathode.   
     
     
         14 . A light emitting element display device comprising:
 a substrate;   a plurality of pixels in a display area on the substrate;   a plurality of thin film transistors in each of the plurality of pixels;   a light emitting element in each of the pixels; and   a capacitor including:
 a first electrode which is arranged between the substrate and a conductive layer of one of the plurality of thin film transistor and overlaps with the conductive layer in plan view; and 
 a second electrode between the first electrode and the conductive layer. 
   
     
     
         15 . The light emitting element display device according to  claim 14 , further comprising another capacitor including: a semiconductor layer which lies at a same level as the conductive layer and overlaps with the first electrode in plan view; and the first electrode. 
     
     
         16 . The light emitting element display device according to  claim 14 , wherein the plurality of thin film transistor in each of the plurality of pixels includes:
 a pixel transistor controlling input of an applied voltage corresponding to a grayscale value to the capacitor; and   a driver transistor controlling light emission based on the applied voltage, and   wherein the second electrode is coupled to one of a source and a drain of the driver transistor.   
     
     
         17 . The light emitting element display device according to  claim 16 , wherein the light emitting element includes:
 an anode;   an organic electroluminescence layer connected to the anode; and   a cathode connected on the organic electroluminescence layer,   wherein   the first electrode is coupled to the cathode, and   the second electrode is coupled to the anode.