El display, el display driving circuit and image display

Abstract

The EL display apparatus according to this invention is provided with an EL light emitting element, a current driving device for driving the EL light emitting element by a current responsive to a source signal represented by a current, and a signal current source ( 634 ) for outputting the source signal in response to image signal to the current driving device via a source signal line, the EL display apparatus being further provided with a precharge voltage source ( 631 ) for outputting a predetermined voltage and a switching and connecting unit ( 636, 637 ) capable of selectively connecting either the signal current source or the precharge voltage source to the source signal line ( 638 ).

1 . An EL display apparatus comprising: 
 an El light emitting element;    a current driving device for driving the EL light emitting element by a current responsive to a source signal represented by a current; and    a signal current source for outputting the source signal in response to an image signal to the current driving device via a source signal line, characterized in that the EL display apparatus further comprises a precharge voltage source for outputting a predetermined voltage and a switching and connecting unit capable of selectively connecting either the signal current source or the precharge voltage source to the source signal line.    
   
   
       2 . The EL display apparatus according to  claim 1 , wherein 
 the switching and connecting unit connects the precharge voltage source and the signal current source to the source signal line such that the source signal is output to the source signal line after the predetermined voltage is applied to the source signal line in one horizontal scan period.    
   
   
       3 . The EL display apparatus according to  claim 2 , wherein 
 a duration of applying the predetermined voltage is 0.2 μs or more and 3 μs or less.    
   
   
       4 . The EL display apparatus according to  claim 2 , wherein 
 the current driving device drives the EL light emitting element by a current responsive to a voltage of a control terminal connected to the source signal line; and    the predetermined voltage is a voltage by which the current driving device so drives the EL light emitting element as to achieve black display.    
   
   
       5 . The EL display apparatus according to  claim 2 , wherein 
 the current driving device drives the EL light emitting element by a current responsive to a voltage of a control terminal connected to the source signal line; and    the predetermined voltage is responsive to gray scale data of the image signal.    
   
   
       6 . The EL display apparatus according to  claim 1 , wherein 
 the switching and connecting unit connects the precharge voltage source to the source signal line when the gray scale data of the image signal is a predetermined one.    
   
   
       7 . The El display apparatus according to  claim 1 , wherein 
 a plurality of the EL light emitting elements emitting a plurality of types of colors are connected to a plurality of the source signal lines, respectively, and    the precharge voltage source outputs the predetermined voltages for the colors respectively to the source signal lines.    
   
   
       8 . The El display apparatus according to  claim 1 , wherein 
 the current driving device comprises a transistor.    
   
   
       9 . The El display apparatus according to  claim 1 , wherein 
 the current driving device comprises a current mirror circuit.    
   
   
       10 . The El display apparatus according to  claim 1 , wherein 
 a plurality of pixels are disposed in matrix;    each of the pixels is provided with the EL light emitting element and the current driving device;    each of columns or rows of the pixels is provided with the source signal line;    the current driving devices of the rows or the columns are connected selectably to the source signal lines;    each of the source signal lines is provided with the signal current source, the precharge voltage source, and the switching and connecting unit;    a plurality of gate lines for transmitting a gate signal to select the current driving devices per column or row are provided; and    a gate driver for outputting the gate signal to the gate lines is provided.    
   
   
       11 . An electronic display appliance comprising: 
 an image display unit comprising the El display apparatus according to  claim 1 , wherein a plurality of pixels are disposed in matrix; each of the pixels is provided with the EL light emitting element and the current driving device, each of columns or rows of the pixels is provided with the source signal line, the current driving devices of the columns or the rows are connected selectably to the source signal lines, each of the source signal lines is provided with the signal current source, the precharge voltage source, and the switching and connecting unit, a plurality of gate lines for transmitting a gate signal to select the current driving devices per row or column are provided, and a gate driver for outputting the gate signal to the gate lines is provided;    a receiver; and    a speaker.    
   
   
       12 . A driving circuit of EL display apparatus, comprising: 
 a plurality of unit current sources;    a reference current generation circuit for defining a current to be output from the unit current sources;    a plurality of current switching circuits disposed on output ends of the unit current sources,    a current wiring having one end connected to the current switching circuits via a first change over switch and the other end connected to source signal lines; and    a precharge voltage source which outputs a predetermined voltage and is connected to the current wiring via a second change over switch, wherein    the current switching circuits are turned on and off depending on 30 gray scale data of an image signal, and    the first and the second change over switches selectively connect either the current switching circuits or the precharge voltage source to the source signal line.    
   
   
       13 . The driving circuit of EL display apparatus according to  claim 12 , wherein 
 the unit current sources are connected to the current switches in such a fashion that the number of the unit current sources to be aligned parallel and connected to each of the current switches is a number from 2 raised to the 0th power to 2 raised to the nth power (n is a natural number).    
   
   
       14 . The driving circuit of EL display apparatus according to  claim 12 , wherein 
 the reference current generation circuit has an operation amplifier, the operation amplifier defining a current output from the unit current sources.    
   
   
       15 . The El display apparatus according to  claim 1 , wherein 
 the precharge voltage source has an output impedance smaller than an output impedance of the signal current source.