Method for sequentially electrophoresis depositing carbon nanotube of field emission display

Abstract

A method sequentially performs electrophoresis depositing carbon nanotube of field emission display. Only one cathode strip is subjected to electrical field at one time during electrophoresis deposition. Therefore, the electrophoresis deposition is confined to local area. A cathode plate includes a plurality of cathode strips and the cathode strips sequentially have potential difference with respect to the anode strips, whereby only one electrical field is present for one pixel at one time and carbon nanotube is formed at that pixel. The cathode strips are sequentially applied with voltage for global electrophoresis deposition.

1 . A method for sequentially electrophoresis depositing carbon nanotube of field emission display, comprising 
 connecting anode ends of a power source to anode strips of an anode plate, connecting cathode ends of the power source to one input end of a plurality of controllers, connecting output ends of the controllers to a plurality of cathode strips of a cathode plate, connecting a signal generator to another input end of the controllers;    providing an electrophoresis tank with electrophoresis solution therein and placing the anode plate and the cathode plate parallel in the electrophoresis tank;    outputting voltages from anode ends of the power source to the anode strips, the signal generator sending pulse voltage signal to one of the controllers such that one of the cathode strip is conducted while the remaining cathode strips are not conducted, whereby only one electrical field is present for one pixel at one time and carbon nanotube is formed at that pixel;    conducting next cathode strip successively and keeping the remaining cathode strips being non-conducted to fabricate carbon nanotube electron emission source in sequential manner.    
   
   
       2 . The method of  claim 1 , wherein the power source provides the anode plate with DC or DC pulse voltage, wherein the voltage is 100-300V and the pulse frequency is 250 Hz.  
   
   
       3 . The method of  claim 1 , wherein the anode plate can be one of platinum plate, titanium plate or screen-printing plate.  
   
   
       4 . The method of  claim 1 , wherein the controller is one of amplifier and switch.  
   
   
       5 . The method of  claim 4 , wherein the switch is a timing switch.  
   
   
       6 . The method of  claim 1 , wherein the cathode plate has a plurality of cathode strips thereon.  
   
   
       7 . The method as in  claim 1 , wherein the cathode strip is a semi-finished product with gate and sacrifice layer.  
   
   
       8 . The method as in  claim 7 , wherein the sacrifice layer is functioned to prevent unwanted deposition such as gate and dielectric layer.  
   
   
       9 . The method as in  claim 7 , further comprising a step of removing the sacrifice layer.  
   
   
       10 . The method as in  claim 1 , wherein the cathode plate and the anode plate are placed in the electrophoresis tank parallel with 3-5 cm separation therebetween.  
   
   
       11 . The method as in  claim 1 , wherein the electrophoresis solution used alcohol as solution, the electron emission source uses powder material made of carbon nanotube formed by arc discharge, the carbon nanotube has average tube length below 5 μm and average diameter below 100 nm and has multiple wall, the carbon nanotube has an additive concentration of 0.1%˜0.005%.  
   
   
       12 . The method as in  claim 11 , wherein the additive concentration is preferably 0.02%  
   
   
       13 . The method as in  claim 1 , wherein the solution further comprises chargers, the charger uses metal salt being conductive after electrophoresis.  
   
   
       14 . The method as in  claim 13 , wherein the metal salt is one of InCl and indium nitride or other salt with tin.  
   
   
       15 . The method as in  claim 13 , wherein the charger is InCl salt with 0.1-0.005% weight concentration and glass powder with at 5% weight concentration to enhance adhesion.  
   
   
       16 . The method as in  claim 15 , wherein the charger is preferably with 0.01% weight concentration  
   
   
       17 . The method as in  claim 1 , wherein the signal generator generates a continuous square wave signal.  
   
   
       18 . A method for sequentially electrophoresis depositing carbon nanotube of field emission display, comprising 
 connecting anode ends of a power source to anode strips of an anode plate, connecting cathode ends of the power source to one input end of a plurality of controllers, connecting output ends of the controllers to a plurality of cathode strips of a cathode plate, connecting a signal generator to another input end of the controllers;    providing an electrophoresis tank with electrophoresis solution therein and placing the anode plate and the cathode plate parallel in the electrophoresis tank;    outputting voltages from anode ends of the power source to the anode strips, the signal generator sending pulse voltage signal sequentially to one of the controllers such that one of the cathode strip is conducted while the remaining cathode strips are not conducted, whereby only one electrical field is present for one pixel at one time and carbon nanotube is formed at that pixel;    conducting next cathode strip successively and keeping the remaining cathode strips being non-conducted to fabricate carbon nanotube electron emission source in sequential manner.