Circuit, driver circuit, organic electroluminescent display device electro-optical device, electronic apparatus, method of controlling the current supply to an organic electroluminescent pixel, and method for driving a circuit

Abstract

A driver circuit operating in stages that comprise a programming stage and a reproduction stage, the circuit comprising: a plurality current paths each of which passes through the circuit, a current driven element, a transistor connected so as operatively to control the current supplied to the said element, a capacitor connected for storing an operating voltage of the transistor during the programming stage, and switching means which control the current paths, the arrangement being such that one of the current paths does not include the said element. No current is applied to the current driven element by the current controlling transistor during the programming stage and thus the overall power consumption is reduced. Furthermore, the circuit can be operated from a normal supply voltage rather than requiring a high bias voltage. During the programming stage, the circuit uses a current sink rather than a current source. Preferably, the current driven element is an electroluminescent element.

1 . A circuit to drive a current driven element, comprising: 
 a first transistor having a first terminal, a second terminal and a first gate;    a capacitor connected to the first gate of the first transistor; and    a second transistor having a third terminal, a fourth terminal and a second gate,    the first terminal being electrically connected to the first gate thorough the second transistor when the second transistor is in an on-state,    the first terminal being connected to the third terminal,    the fourth terminal being connected to the capacitor, and    a capacitance between the second gate and the third terminal being lower than a capacitance of the capacitor.    
   
   
       2 . A circuit to drive a current driven element, comprising: 
 a first transistor having a first terminal, a second terminal and a first gate;    a capacitor connected to the first gate of the first transistor; and    a second transistor having a third terminal, a fourth terminal and a second gate,    the first terminal being electrically connected to the first gate thorough the second transistor when the second transistor is in an on-state,    the first terminal being connected to the third terminal,    the fourth terminal being connected to the capacitor,    a capacitance between the second gate and the third terminal being lower than a capacitance of the capacitor, and    a first gate voltage of the first gate being determined by a data current flowing through the first transistor.    
   
   
       3 . The circuit according to  claim 2 , 
 further comprising a third transistor connected to the first terminal,    the first gate voltage being determined by a data current flowing through the first transistor and the third transistor.    
   
   
       4 . The circuit according to  claim 3 , 
 at least one of the second transistor and the third transistor having a structure to reduce a leakage current.    
   
   
       5 . The circuit according to  claim 4 , 
 the structure being one of a multi-gate structure and a lightly doped drain structure.    
   
   
       6 . The circuit according to  claim 3 , 
 the third transistor having a structure to reduce a leakage current.    
   
   
       7 . The circuit according to  claim 1 , 
 a first gate voltage of the first gate being determined by a data current flowing through the first transistor when the first terminal is electrically connected to the capacitor through the second transistor.    
   
   
       8 . An electro-optical device comprising the circuit according to  claim 1 .  
   
   
       9 . An electro-optical device having a plurality of pixels, each of the plurality of pixels comprising: 
 a current driven element;    a first transistor having a first terminal, a second terminal and a first gate;    a capacitor connected to the first gate of the first transistor; and    a second transistor having a third terminal, a fourth terminal and a second gate,    the first terminal being electrically connected to the first gate thorough the second transistor when the second transistor is in an on-state,    the first terminal being connected to the third terminal,    the fourth terminal being connected to the capacitor,    a capacitance between the second gate and the third terminal being lower than a capacitance of the capacitor,    a first gate voltage of the first gate being determined by a data current flowing through the first transistor when the second transistor is in an on-state, and    the first gate voltage determined by the data current determining a current level of a driving current supplied to the current driven element.    
   
   
       10 . The electro-optical device according to  claim 9 , 
 each of the plurality of pixels further comprising a third transistor,    at least one of the second transistor and the third transistor having a structure to reduce a leakage current.    
   
   
       11 . The electro-optical device according to  claim 9 , 
 each of the plurality of pixels further comprising a third transistor connected to the first terminal,    the data current flowing through the first transistor and the third transistor.    
   
   
       12 . The electro-optical device according to  claim 10 , 
 the structure to reduce a leakage current being one of a multi-gate structure and a lightly doped drain structure.    
   
   
       13 . The electro-optical device according to  claim 9 , 
 the current driven element being an electroluminescent element.    
   
   
       14 . The electro-optical device according to  claim 9 , 
 each of the plurality of pixels further comprising a fourth transistor,    the driving current flowing through the first transistor and the fourth transistor.    
   
   
       15 . The electro-optical device according to  claim 11 , 
 the second transistor and the third transistor being controlled by a same signal.    
   
   
       16 . An electronic apparatus comprising the electro-optical device according to  claim 9.