Liquid crystal display device

Abstract

LCD device including: a first LCD panel for displaying an image in a transmission mode; a second LCD panel for displaying an image in a reflection mode; and a power supply circuit for supplying a first counter voltage for displaying in the transmission mode to a first counter electrode of the first LCD panel and a second counter voltage for displaying in the reflection mode to a second counter electrode of the second LCD panel, wherein the first counter voltage and the second counter voltage are at voltage levels mutually different from one another.

1 . A liquid crystal display device comprising:
 a first liquid crystal display panel for displaying an image in a transmission mode, the first liquid crystal display panel having a number of first pixel electrodes, a first counter electrode for applying an electric field between itself and the first pixel electrodes, and a first liquid crystal layer interposed between the first pixel electrodes and the first counter electrode;   a second liquid crystal display panel for displaying an image in a reflection mode, the second liquid crystal display panel having a number of second pixel electrodes, a second counter electrode for applying an electric field between itself and the second pixel electrodes, and a second liquid crystal layer interposed between the second pixel electrodes and the second counter electrode; and   a power supply circuit for supplying a first counter voltage for displaying in the transmission mode to the first counter electrode of the first liquid crystal display panel and a second counter voltage for displaying in the reflection mode to the second counter electrode of the second liquid crystal display panel,   wherein the first counter voltage and the second counter voltage are at voltage levels mutually different from one another.   
     
     
         2 . A liquid crystal display device according to  claim 1 , wherein the first counter voltage is a voltage optimized for displaying in the transmission mode, and
 the second counter voltage is a voltage optimized for displaying in the reflection mode.   
     
     
         3 . A liquid crystal display device according to  claim 1 , wherein the power supply circuit has a first counter voltage generation circuit for applying the first counter voltage to the first counter electrode of the first liquid crystal display panel, and a second counter voltage generation circuit for applying the second counter voltage to the second counter electrode of the second liquid crystal display panel. 
     
     
         4 . A liquid crystal display device according to  claim 1 , wherein the first counter voltage is lower than the second counter voltage. 
     
     
         5 . A liquid crystal display device according to  claim 1 , wherein the first liquid crystal display panel has a first substrate and a second substrate sandwiching the first liquid crystal layer therebetween,
 the second liquid crystal display panel has a third substrate and a fourth substrate sandwiching the second liquid crystal layer therebetween,   the first substrate is separated from the third substrate and the fourth substrate, and   the second substrate is separated from the third substrate and the fourth substrate.   
     
     
         6 . A liquid crystal display device according to  claim 1 , comprising:
 an illumination device disposed at a back face of the first liquid crystal display panel,   wherein the power supply circuit applies the first counter voltage to the first counter electrode of the first liquid crystal display panel when the illumination device is on, and   the power supply circuit applies the second counter voltage to the second counter electrode of the second liquid crystal display panel when the illumination device is off.   
     
     
         7 . A liquid crystal display device according to  claim 1 , wherein the first liquid crystal display panel has a first substrate and a second substrate sandwiching the first liquid crystal layer therebetween,
 the second liquid crystal display panel has a third substrate and a fourth substrate sandwiching the second liquid crystal layer therebetween,   the first liquid crystal display panel has a first active matrix array, and   the second liquid crystal display panel has a second active matrix array.   
     
     
         8 . A liquid crystal display device according to  claim 1 , wherein the first liquid crystal display panel has a first image signal line supplying image signals to the first pixel electrodes,
 the second liquid crystal display panel has a second image signal line supplying image signals to the second pixel electrodes,   the first image signal line is electrically connected to the second image signal line, and   the first image signal line and the second image signal line are driven by an image signal drive circuit in common.