Light pen, photo detective liquid crystal display device and display device having the light pen

Abstract

A photo detective LCD device includes a light pen. The light pen includes a body, a driving pulse generating module and a light generating module. The body has a pen shape, and an end of the body includes an opening through which light exits. The driving pulse generating module is disposed in the body and generates first and second driving power pulses having first and second frequencies, respectively. The light generating module generates first and second light in response to the first and second driving power pulses, respectively. The first and second light flickers in a third frequency and a fourth frequency, respectively. The power consumption is reduced, and the brightness of sensing light is enhanced. The light pen generates light having at least two different frequencies, and the display device recognizes light generated from the light pen effectively. Therefore, the display device may operate without failure.

1 . A liquid crystal display device comprising:
 a light pen including:
 a body; 
 a photo detective module that is configured to detect a first light inputted from an external source to output a first sensing signal, the photo detective module being disposed in the body; 
 a control module that is configured to output a control signal in response to the first sensing signal; and 
 a light generating module that is configured to receive a driving power signal in response to the control signal to generate a second light; 
   a liquid crystal display panel including:
 a first substrate; 
 a second substrate facing the first substrate; 
 a liquid crystal layer interposed between the first substrate and the second substrate; 
 a plurality of first electrodes disposed on the first substrate; 
 a second electrode disposed on the second substrate; and 
 a photo detective element that is configured to detect the second light to output a second sensing signal having a position information, the photo detective element being disposed between the first electrodes, the position information having a position to which the second light is incident; and 
   a driving module that is configured to generate first and second driving signals, the first driving signal being applied to the first and second electrodes so that the liquid crystal display panel outputs the first light, and the second driving signal being applied to the first and second electrodes in response to the second sensing signal so that the liquid crystal display panel outputs a third light.   
   
   
       2 . The liquid crystal display device of  claim 1 , wherein the liquid crystal display device further includes a lamp assembly having a lamp and an inverter, the lamp and the inverter face the first substrate, the inverter supplies a power signal to the lamp, and the driving power signal is supplied by the inverter. 
   
   
       3 . A liquid crystal display device comprising:
 a light pen including:
 a body; 
 a driving pulse generating module that is configured to generate a first driving power pulse having a first frequency during a first time period and a second driving power pulse having a second frequency during a second time period, the driving pulse generating module being disposed in the body; and 
 a light generating module that is configured to generate a first light in response to the first driving power pulse and a second light in response to the second driving power pulse, the first light flickering at a third frequency, and the second light flickering at a fourth frequency; 
   a liquid crystal display panel including:
 a plurality of pixels that is configured to control a transmissivity of a third light passing through a liquid crystal layer to display an image; and 
 a photo detective element that is configured to detect a position into which the first and second lights are incident, the photo detective element being disposed between the pixels; 
   a sensed signal processing unit including a comparator module, the comparator module comparing a first intensity of a first sensing signal with a second intensity of a second sensing signal, the first sensing signal corresponding to a third light inputted from an external source, the second sensing signal corresponding to the first and second lights; and   a driving module that is configured to generate first and second driving signals, the first driving signal being applied to the pixels, and the second driving signal being applied to the pixels in response to the second sensing signal.   
   
   
       4 . A display device comprising:
 a light pen including:
 a body; 
 a photo detective module that is configured to detect a first light inputted from an external source to output a first sensing signal, the photo detective module being disposed in the body; 
 a control module that is configured to output a control signal in response to the first sensing signal; and 
 a light generating module that is configured to receive a driving power signal in response to the control signal to generate a second light; 
   a display unit including a plurality of photo detective elements, the photo detective elements outputting the first light, detecting the second light to output a second sensing signal having a position information, the position information having a position to which the second light is incident;   a driving module that is configured to generate first and second driving signals, the first driving signal allowing the display unit to output the first light, and the second driving signal allowing the display unit to output a third light in response to the second sensing signal.