Active Matrix Type Display Apparatus and a Driving Device of a Load

Abstract

An active matrix type display device includes a plurality of pixel circuits arranged in a matrix shape. The pixel circuit has a display device, a drive transistor of a first conductivity type for controlling a current flowing in the display device, a capacitor provided at a control electrode of the drive transistor, and a switch, connected to the control electrode of the drive transistor, for holding a drive control signal at the capacitor. The switch includes a switching transistor of the first conductivity type and a switching transistor of a second conductivity type, in which one main electrode of the switching transistor of the first conductivity type and one main electrode of the switching transistor of the second conductivity type are connected serially. One of the other main electrode of the switching transistor of the first conductivity type and the other main electrode of the switching transistor of the second conductivity type is connected to the control electrode of the drive transistor.

1 . An active matrix type display apparatus having a plurality of pixel circuits arranged in a matrix,
 wherein said pixel circuit comprises:   a display element;   a drive transistor of a first conductivity type for controlling a current flowing in said display element;   a capacitor provided at a control electrode of said drive transistor; and   a switch, connected to said control electrode of said drive transistor, for holding a drive control signal at said capacitor, and   said switch includes a switching transistor of the first conductivity type and a switching transistor of a second conductivity type in which one main electrode of said switching transistor of the first conductivity type and one main electrode of said switching transistor of the second conductivity type are connected, and one of the other main electrode of said switching transistor of the first conductivity type and the other main electrode of said switching transistor of the second conductivity type is connected to said control electrode of said drive transistor.   
   
   
       2 . An apparatus according to  claim 1 , wherein
 the other one of the other main electrode of said switching transistor of the first conductivity type and the other main electrode of said switching transistor of the second conductivity type is connected to one main electrode of said drive transistor, and   by turning on both of said switching transistor of the first conductivity type and said switching transistor of the second conductivity type, said control electrode and said one main electrode of said drive transistor are short-circuited.   
   
   
       3 . An apparatus according to  claim 2 , wherein the other main electrode of said switching transistor of the first conductivity type is connected to said control electrode of said drive transistor. 
   
   
       4 . An apparatus according to  claim 3 , wherein
 a switching transistor of the second conductivity type for selecting a row is provided between said one main electrode of said drive transistor and a signal line,   a switching transistor of the first conductivity type for selecting light emission is provided on a path of the current flowing in said display element, and   a control electrode of said switching transistor of the second conductivity type, a control electrode of said switching transistor for selecting the row, and a control electrode of said switching transistor for selecting the light emission are connected in common to a second scan signal line.   
   
   
       5 . An apparatus according to  claim 2 , wherein after the time when said switching transistor of the first conductivity type is changed from ON to OFF, said switching transistor of the second conductivity type is changed from ON to OFF. 
   
   
       6 . An apparatus according to  claim 2 , wherein the other main electrode of said switching transistor of the second conductivity type is connected to said control electrode of said drive transistor. 
   
   
       7 . An apparatus according to  claim 6 , wherein
 a switching transistor of the second conductivity type for selecting a row is provided between said one main electrode of said drive transistor and a signal line,   a switching transistor of the first conductivity type for selecting light emission is provided on a path of the current flowing in said display device, and   a control electrode of said switching transistor of the second conductivity type, a control electrode of said switching transistor for selecting the row, and a control electrode of said switching transistor for selecting the light emission are connected in common to a second scan signal line.   
   
   
       8 . An apparatus according to  claim 1 , wherein
 the other one of the other main electrode of said switching transistor of the first conductivity type and the other main electrode of said switching transistor of the second conductivity type is connected to an output terminal of a voltage buffer, and   an input terminal of said voltage buffer is connected to a signal line.   
   
   
       9 . An apparatus according to  claim 1 , wherein
 the other one of the other main electrode of said switching transistor of the first conductivity type and the other main electrode of said switching transistor of the second conductivity type is connected to an output terminal of a source-follower circuit, and   an input terminal of said source-follower circuit is connected to a signal line.   
   
   
       10 . An apparatus according ot  claim 1 , wherein
 the other one of the other main electrode of said switching transistor of the first conductivity type and the other main electrode of said switching transistor of the second conductivity type is connected to an output terminal of a feedback type operational amplifier, and   an input terminal of said feedback type operational amplifier is connected to a signal line.   
   
   
       11 . An apparatus according to  claim 1 , wherein said drive transistor of the first conductivity type and said switching transistor of the first conductivity type are p-channel type thin film transistors and said switching transistor of the second conductivity type is an n-channel type thin film transistor. 
   
   
       12 . A driving device of a load, comprising:
 a drive transistor of a first conductivity type for controlling a current flowing in said load;   a capacitor provided at a control electrode of said drive transistor; and   a switch, connected to said control electrode of said drive transistor, for holding a drive control signal at said capacitor, and   said switch includes a switching transistor of the first conductivity type and a switching transistor of a second conductivity type in which one main electrode of said switching transistor of the first conductivity type and one main electrode of said switching transistor of the second conductivity type are connected, and   one of the other main electrode of said switching transistor of the first conductivity type and the other main electrode of said switching transistor of the second conductivity type is connected to said control electrode of said drive transistor.   
   
   
       13 . A device according to  claim 12 , wherein a plurality of circuits each having said drive transistor of the first conductivity type, said capacitor, and said switch are arranged in a matrix. 
   
   
       14 - 15 . (canceled)