| 摘要 |
PURPOSE:To expand the life of a device by previously impressing an inversional pulse to prevent drain current from reduction due to the movement of a threshold voltage generated by impressing a selective pulse between the gate and drain of a thin film transistor (TR). CONSTITUTION:When a selective pulse is impressed to a gate line 6, a positive voltage is impressed to the gate side between the gate and drain and between the gate and source of the thin film TR 8. At that time, carriers are injected to a gate insulating film of the TR 8 from a channel. Thereby, the threshold voltage of the TR 8 is moved in a direction reducing the driving capacity of the TR 8. In order to cancel the movement of the threshold voltage, an inversional pulse having a reverse code to a selective pulse is impressed to the gate side between the gate and drain and between the gate and source prior to the impression of the selective pulse. Consequently, all carriers injected into the gate insulating film are discharged to the channel. Thereby, the threshold voltage of the TR 8 is varied within a minute time, but in a long time, there is no variation in the threshold voltage.
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