Current load device and method for driving the same

Abstract

This invention provides a precise current load device. A cell includes a power supply line, a ground line, first and second voltage supply lines, a signal line, first, third and fourth control lines, first to fourth switches, a p-type TFT, a capacitance element, and a current load element. A source of the p-type TFT is connected to the power supply line, one terminal of the current load element is connected to the ground line, the first switch is connected between the signal line and a drain of the p-type TFT, the second switch is connected between the drain and the gate of the p-type TFT, the third switch is connected between the drain of the p-type TFT and the current load element, and the fourth switch is connected between the voltage supply line and the current load element.

1 - 22 . (canceled)  
   
   
       23 . method for driving a current load device, the current load device being active-matrix driven and comprising a plurality of cells each comprising a current load element, the method comprising: 
 driving, by a driving transistor, the current load element; and retaining, by a retention capacitance element, a voltage to be applied to said driving transistor, wherein said current load element has not been driven not only for the period in which said retention capacitance element is setting an appropriate voltage level to be retained therein, but also for a part of the period in which said retention capacitance element does not perform the setting operation.    
   
   
       24 . The method for driving a current load device according to  claim 23 , wherein the supply of the current to said current load element is stopped before the operation for setting the voltage level for said retention capacitance element.  
   
   
       25 . The method for driving a current load device according to  claim 23 , wherein when the supply of the current to said current load element is stopped, charges stored in said current load element is forcedly removed.  
   
   
       26 . The method for driving a current load device according to  claim 23 , wherein when setting the voltage level for said retention capacitance element, said driving transistor operates in a saturation region.  
   
   
       27 . The method for driving a current load device according to  claim 23 , wherein when setting the voltage level for said retention capacitance element, the performance of passing the current through said driving transistor is set after the performance of supplying the voltage to said retention capacitance element and said driving transistor.  
   
   
       28 . The method for driving a current load device according to  claim 23 , wherein the operation for setting the voltage level for said retention capacitance element includes a period in which the current flowing through the signal line is passed across a drain and source of said driving transistor.  
   
   
       29 . The method for driving a current load device according to  claim 23 , wherein a performance of said current load element is set based on two factors, a first factor being the performance of said current load element in the case of being driven by said driving transistor, and a second factor being a ratio between a period in which said current load element operates and a period in which said current load element does not operate.  
   
   
       30 - 31 . (canceled)  
   
   
       32 . The method for driving a current load device according to  claim 23 , wherein said current load element is a light emitting device.  
   
   
       33 . The method for driving a current load device according to  claim 23 , wherein said current load element is an organic EL device.  
   
   
       34 - 35 . (canceled)