公开(公告)号：JPH10333642A

公开(公告)日：1998-12-18

申请号：JP13680197

申请日：1997-05-27

Applicant: IBM

Inventor： SAKAETANI TETSUYA ,  AMAMIYA TAKAHISA ,  SUZUKI MIDORI

IPC: G02F1/133 ,  G09G3/36

Abstract: PROBLEM TO BE SOLVED: To erase an after-image arising in cutting off a system power supply with an inexpensive circuit construction without securing a special power supply. SOLUTION: The liquid crystal display device has a gate line 32 connected to a gate for a transistor 31a in an active switch element, a node A to supply gate low voltage Vgl thereto, a P channel transistor 37 connected between the node A and a charge accumulating means 36, a node C connected to its gate, a voltage supply means 38 to supply voltage to the node C for keeping the P channel transistor in a highly resistant condition while power voltage Vdd is supplied to the liquid crystal display device, a voltage dropping means 39 to set the node C to such voltage that the P channel transistor is in a low resistant condition with capacity coupling, depending on the change of the power voltage Vdd, when there is no voltage supply, a control means 33 to supply charge from the charge accumulating means through the node A to the gate line for making the transistor 31a in a low resistant state.