Power-off discharge circuit, and source driver circuit having the same

Abstract

A power-off discharge circuit comprises a power voltage detection unit that detects whether a first power voltage for driving a source driver circuit is blocked and generates a discharge control signal, and a discharge unit that discharges a load circuit in a display panel based on the discharge control signal.

What is claimed is: 
     
         1 . A power-off discharge circuit of a display device, the circuit comprising:
 a power voltage detection unit which detects whether a first power voltage which drives a source driver circuit is blocked and generates a discharge control signal; and   a discharge unit which discharges a load circuit in a display panel of the display device based on the discharge control signal.   
     
     
         2 . The circuit of  claim 1 , wherein the display device is a liquid crystal display (LCD) device. 
     
     
         3 . The circuit of  claim 2 , wherein the load circuit corresponds to one column of the display panel. 
     
     
         4 . The circuit of  claim 1 , wherein the discharge control signal has a first voltage level when the display device enters into a power-off state, the first voltage level of the discharge control signal controlling the load circuit to be discharged. 
     
     
         5 . The circuit of  claim 4 , wherein the first power voltage is blocked when the display device enters into the power-off state. 
     
     
         6 . The circuit of  claim 1 , wherein the discharge control signal has a second voltage level when the display device operates in a power-on state, and the second voltage level of the discharge control signal controls the load circuit so that the load circuit is not discharged. 
     
     
         7 . The circuit of  claim 6 , wherein the first power voltage is supplied when the display device operates in the power-on state. 
     
     
         8 . The circuit of  claim 1 , further comprising:
 a driving voltage generation unit which generates a second power voltage which drives the power voltage detection unit based on the first power voltage.   
     
     
         9 . The circuit of  claim 8 , wherein the driving voltage generation unit generates the second power voltage by performing a voltage division operation on the first power voltage. 
     
     
         10 . The circuit of  claim 9 , wherein the power voltage detection unit controls the discharge control signal to have a voltage level between the second power voltage and a ground voltage. 
     
     
         11 . The circuit of  claim 10 , further comprising:
 a level shift unit which performs a level shifting operation on the voltage level of the discharge control signal based on the first power voltage.   
     
     
         12 . A source driver circuit, comprising:
 a decoder which decodes a digital data which indicates a gradation level to generate an analog gradation voltage corresponding to the digital data;   an output buffer which amplifies the analog gradation voltage to output a source line driving voltage to a load circuit in a display panel of a display device;   a switch which turns off when a first power voltage which drives the source driver circuit is blocked, and turns on when the first power voltage is supplied; and   a power-off discharge circuit which discharges the load circuit when the first power voltage is blocked, and which does not discharge the load circuit when the first power voltage is supplied.   
     
     
         13 . The circuit of  claim 12 , wherein the first power voltage is blocked when the display device enters into a power-off state, and the first power voltage is supplied when the display device operates in a power-on state. 
     
     
         14 . The circuit of  claim 12 , wherein the power-off discharge circuit comprises:
 a power voltage detection unit which detects whether the first power voltage is blocked and generates a discharge control signal; and   a discharge unit which discharges the load circuit based on the discharge control signal.   
     
     
         15 . The circuit of  claim 14 , wherein the power-off discharge circuit further comprises:
 a driving voltage generation unit which generates a second power voltage which drives the power voltage detection unit based on the first power voltage.   
     
     
         16 . The circuit of  claim 15 , wherein the power-off discharge circuit further comprises:
 a level shift unit which performs a level shifting operation on the voltage level of the discharge control signal based on the first power voltage.