Patent ID: 8355015
Filing Date: 2013-01-15
Classification: G09G,H01L

Abstract:
1. A semiconductor device comprising: a transistor; a P-channel transistor having one of a source terminal and a drain terminal connected to a high potential power source so that a high potential can be applied to the one of the source terminal and the drain terminal; a wiring electrically connecting one of a source terminal and a drain terminal of the transistor and the other of the source terminal and the drain terminal of the P-channel transistor; a capacitor having a first terminal electrically connected to a gate terminal of the transistor and a second terminal electrically connected to a first power source line; a switch connected between the gate terminal of the transistor and the one of the source terminal and the drain terminal of the transistor; a first rectifying element having a third terminal electrically connected to the wiring and a fourth terminal electrically connected to a second power source line; and a second rectifying element having a fifth terminal electrically connected to the wiring and a sixth terminal electrically connected to a third power source line; wherein a forward current direction of the first rectifying element is a direction flowing from the third terminal to the fourth terminal, wherein a forward current direction of the second rectifying element is a direction flowing from the sixth terminal to the fifth terminal, wherein the first rectifying element and the second rectifying element comprise a first diode-connected thin film transistor and a second diode-connected thin film transistor, respectively, wherein a ratio W/L of a gate width W to a gate length L of the first diode connected thin film transistor is lower than a ratio W/L of the second diode-connected thin film transistor, wherein the semiconductor device is configured so that a current flows to at least one of the first rectifying element and the second rectifying element when a potential of the wiring becomes outside a set range so that the potential of the wiring returns back within the set range, wherein the second power source line has a higher potential than the first power source line and the third power source line, and wherein a current drive capacity of the second rectifying element is at least twice as large as a current drive capacity of the first rectifying element.