Booster circuit and display device

Abstract

A display device includes a display panel having scan lines, and a booster circuit configured to generate an output voltage and to supply the output voltage as power source to the display panel. The booster circuit includes a charge pump and a feedback circuit section configured to control a booster operation of the charge pump depending on the output voltage. A mode of the booster operation includes a charge mode that charges the output capacitor and a discharge mode that discharges the output capacitor. The mode is switched depending on the output voltage. The feedback circuit section includes a booster operation control section configured to secure a period during which the mode is not switched between the charge mode and the discharge mode in accordance with an external synchronizing signal. The period includes a timing at which an active scan line is switched among the plurality of scan lines.

1 . A display device comprising:
 a display panel having a plurality of scan lines; and   a booster circuit configured to generate an output voltage and to supply said output voltage as power source to said display panel,   wherein said booster circuit comprises:   a charge pump configured to perform a booster operation that boosts a voltage supplied from an external power source and outputs the boosted voltage as said output voltage through an output capacitor; and   a feedback circuit section configured to control said booster operation of said charge pump depending on said output voltage,   wherein a mode of said booster operation includes:   a charge mode that charges said output capacitor with the voltage supplied from said external power source; and   a discharge mode that discharges said output capacitor,   wherein said mode of said booster operation is switched between said charge mode and said discharge mode depending on said output voltage,   wherein said feedback circuit section comprises a booster operation control section configured to secure a period during which said mode is not switched between said charge mode and said discharge mode in accordance with an external synchronizing signal, and   wherein said period includes a timing at which an active scan line is switched among said plurality of scan lines.   
     
     
         2 . The display device according to  claim 1 ,
 wherein said booster operation control section comprises a voltage dividing circuit section configured to voltage-divide said output voltage with a voltage dividing ratio varying depending on said external synchronizing signal and to output the divided voltage as a feedback voltage, and   wherein said feedback circuit section further comprises:   a reference voltage source section configured to output a reference voltage; and   a comparison circuit section configured to make a comparison between said reference voltage and said feedback voltage and to output a comparison result signal indicating the result of said comparison for controlling said booster operation.   
     
     
         3 . The display device according to  claim 1 ,
 wherein said booster operation control section comprises a reference voltage source section configured to output a reference voltage varying depending on said external synchronizing signal, and   wherein said feedback circuit section further comprises:   a voltage dividing circuit section configured to voltage-divide said output voltage and to output the divided voltage as a feedback voltage; and   a comparison circuit section configured to make a comparison between said reference voltage and said feedback voltage and to output a comparison result signal indicating the result of said comparison for controlling said booster operation.   
     
     
         4 . The display device according to  claim 1 ,
 wherein said feedback circuit section further comprises:   a voltage dividing circuit section configured to voltage-divide said output voltage and to output the divided voltage as a feedback voltage;   a reference voltage source section configured to output a reference voltage; and   a comparison circuit section configured to make a comparison between said reference voltage and said feedback voltage and to output a comparison result signal indicating the result of said comparison for controlling said booster operation, and   wherein said comparison circuit section comprises:   a comparator configured to make the comparison between said reference voltage and said feedback voltage and to generate said comparison result signal; and   said booster operation control section that comprises a synchronizing circuit configured to output said comparison result signal after performing waveform modulation of said comparison result signal in accordance with said external synchronizing signal.   
     
     
         5 . The display device according to  claim 4 ,
 wherein said external synchronizing signal comprises:   a first external synchronizing signal for stating said booster operation of said charge pump; and   a second external synchronizing signal for stopping said booster operation of said charge pump, and   wherein said booster operation control section further comprises:   a first external control signal input section to which said first external synchronizing signal is supplied; and   a second external control signal input section to which said second external synchronizing signal is supplied.   
     
     
         6 . A method of driving a display panel comprising:
 generating, by using a charge pump, a booster voltage from a voltage supplied from an external power source; and   supplying said booster voltage as power source to said display panel,   wherein said generating the booster voltage comprises:   activating, in a charge mode, said charge pump to perform a booster operation that boosts the voltage supplied from said external power source;   deactivating, in a discharge mode, said charge pump to stop said booster operation;   switching a mode between said charge mode and said discharge mode depending on said booster voltage; and   securing a period during which said mode is not switched between said charge mode and said discharge mode in accordance with an external synchronizing signal,   wherein said period includes a timing at which an active scan line is switched among a plurality of scan lines of said display panel.