Level shift circuit, display apparatus, and portable terminal

Abstract

In the structure in which an input signal IN and a reverse-phase signal XIN thereof are externally input, an external IC is required for generating the reverse-phase signal XIN, and the number of required input signal terminals is two. A level shift circuit formed on an insulating substrate, such as a glass substrate, using transistors with large characteristic variations, for example, TFTs with high thresholds Vth, includes a complementary generator unit ( 11 ) driven by a first power supply (VCC) having an amplitude voltage equal to the amplitude voltage of a signal externally input from the substrate to generate complementary signals from a single-phase input signal IN. The complementary signals generated by the complementary generator unit ( 11 ) are level-shifted by a level shift unit ( 14 ). Therefore, it is no longer necessary to externally input the reverse-phase signal XIN.

1 . A level shift circuit formed on an insulating substrate for level shifting an externally input signal input from outside the substrate, comprising: 
 a complementary generator unit formed on said insulating substrate and driven by a first power supply having an amplitude voltage equal to an amplitude voltage of the externally input signal input from outside the insulating substrate for generating a complementary signal from the externally input signal; and    a level shift unit formed on said insulating substrate and driven by a second power supply having a higher voltage than the first power supply for shifting the level of the complementary signal.    
   
   
       2 - 3 . (canceled)  
   
   
       4 . A display apparatus comprising: 
 a display unit having a matrix of pixels formed on a transparent insulating substrate; and    a level shift circuit formed on the transparent insulating substrate together with the display unit for shifting the level of an input signal input from outside the substrate so as to drive the display unit,    wherein the level shift circuit includes:    a complementary generator unit driven by a first power supply having an amplitude voltage equal to an amplitude voltage of the signal input from the outside of the substrate for generating a complementary signal from the input signal; and    a level shift unit driven by a second power supply having a higher voltage than the first power supply for shifting the level of the complementary signal.    
   
   
       5 - 8 . (canceled)  
   
   
       9 . A portable terminal including a display apparatus as a screen display unit, the display apparatus comprising: 
 a display unit having a matrix of pixels formed on a transparent insulating substrate; and    a level shift circuit formed on the transparent insulating substrate together with the display unit for shifting the level of an input signal input from outside the substrate so as to drive the display unit,    wherein the level shift circuit includes:    a complementary generator unit driven by a first power supply having an amplitude voltage equal to an amplitude voltage of the signal input from the outside of the substrate for generating a complementary signal from the input signal; and    a level shift unit driven by a second power supply having a higher voltage than the first power supply for shift the level of the complementary signal.    
   
   
       10 . A display apparatus according to  claim 4 , wherein said input signal is a signal selected from a group including a master clock, a horizontal synchronous pulse, a vertical synchronous pulse, and display data.  
   
   
       11 . A portable terminal including a display apparatus as a screen display unit according to  claim 9 , wherein said input signal is a signal selected from a group including a master clock, a horizontal synchronous pulse, a vertical synchronous pulse, and display data.  
   
   
       12 . A level shift circuit according to  claim 1 , wherein said complementary generator unit is comprised of two CMOS inverters in series, and wherein the output of each inverter are both connected as inputs to the level shift unit.  
   
   
       13 . A display apparatus according to  claim 4 , wherein said complementary generator unit is comprised of two CMOS inverters in series, and wherein the output of each inverter are both connected as inputs to the level shift unit.  
   
   
       14 . A portable terminal including a display apparatus as a screen display unit according to  claim 9 , wherein said complementary generator unit is comprised of two CMOS inverters in series, and wherein the output of each inverter are both connected as inputs to the level shift unit.  
   
   
       15 . A level shift circuit according to  claim 12 , wherein said two CMOS inverters function to provide the level shift unit with the externally input signal and its complement while preventing the flow of a D.C. current across an input terminal on the insulating substrate of said externally input signal.  
   
   
       16 . A display apparatus according to  claim 13 , wherein said two CMOS inverters function to provide the level shift unit with the externally input signal and its complement while preventing the flow of a D.C. current across an input terminal on the insulating substrate of said externally input signal.  
   
   
       17 . A portable terminal including a display apparatus as a screen display unit according to  claim 14 , wherein said two CMOS inverters function to provide the level shift unit with the externally input signal and its complement while preventing the flow of a D.C. current across an input terminal on the insulating substrate of said externally input signal.