Method to prevent static destruction of an active element comprised in a liquid crystal display device

Abstract

A liquid crystal display device which utilizes an active matrix substrate and its substrate, and which is provided with a novel method of manufacture which can reduce the manufacturing process of amorphous silicon thin film transistors of reverse stagger construction, and an electrostatic protection means which is created using this method of manufacture. In a thin film transistor manufacturing process, along with forming an aperture for connecting the contact hole and the external terminal in a manufacturing process for a thin film transistor, utilization is made of ITO film as the wiring. The electrostatic protection means is formed from a bidirectional diode (electrostatic protection element) which is composed utilizing an MOS transistor connected between the electrode (PAD) for connecting the external terminal, and the joint electric potential line. The electrostatic protection element is substantially a transistor, with great current capacity, and utilizing the TFT formation process of pixel components in their existent state, the process can be formed without any complications.

1 . An active matrix substrate, comprising: 
 a scanning line;    a signal line;    a thin film transistor disposed in correspondence with intersections of the scanning line and the signal line;    a pixel electrode disposed in correspondence with the thin film transistor; and    a protective element to prevent static electricity destruction electrically connected between at least one of the scanning line and the signal line, and a common electric potential line, the protective element at least in part forming a pixel electrode material layer.    
   
   
       2 . The active matrix substrate of  claim 1 , at least one of the scanning line and the signal line being electrically connected to an electrode to connect an external terminal, the protective element being electrically connected between the common electric potential line and the electrode to connect the external terminal.  
   
   
       3 . The active matrix substrate of  claim 1 , the protective element using the thin film transistor.  
   
   
       4 . The active matrix substrate of  claim 3 , one of a source electrode and a drain electrode of the thin film transistor for the protective element being electrically connected to one of the scanning line and the signal line via the pixel electrode material layer.  
   
   
       5 . The active matrix substrate of  claim 3 , the protective element including a diode that is formed from the thin film transistor electrically connected between a gate electrode and one of a source electrode and a drain electrode.  
   
   
       6 . The active matrix substrate of  claim 5 , one of a source electrode and a drain electrode of the thin film transistor for the protective element being electrically connected to one of the scanning line and the signal line via the pixel electrode material layer.  
   
   
       7 . The active matrix substrate of  claim 5 , a gate electrode of the thin film transistor for the protective element being electrically connected to one of the source electrode and the drain electrode of the thin film transistor via the pixel electrode material layer.  
   
   
       8 . The active matrix substrate of  claim 3 , the protective element including a first diode formed from the connection of the gate electrode and a drain electrode of a first thin film transistor, and a second diode formed from the connection of the gate electrode and a drain electrode of a second thin film transistor, the first diode and the second diode being connected mutually in a reverse direction, in parallel.  
   
   
       9 . The active matrix substrate of  claim 1 , the common electric potential line being electrically connected to a facing electrode.  
   
   
       10 . The active matrix substrate of  claim 9 , the common electric potential line being electrically connected to a pad to connect a facing electrode via the pixel electrode material layer.  
   
   
       11 . A liquid crystal display device, comprising: 
 the active matrix substrate of  claim 1.