Pixel circuit based on double-gate transistor and drive method thereof

Abstract

The application discloses a pixel circuit based on a double-gate transistor and a drive method thereof. In one embodiment, the pixel circuit comprises a light-emitting device OLED, a drive transistor T1, switch transistors T2-T5, a capacitor C1 and a capacitor C2; and the drive transistor T1 is a double-gate transistor and is used to drive the light-emitting device OLED to emit light. For the drive transistor in the pixel circuit of the application, the double-gate transistor is used to replace a single-gate transistor as a drive transistor in a traditional technology, a bottom gate of the double-gate transistor is used as the main gate, and then a top gate source voltage is used to adjust a threshold voltage of the drive transistor; and, because stability of a double-gate a-IGZO TFT is higher than stability of a single-gate device, the double-gate a-IGZO TFT can achieve threshold extraction and compensation and can achieve good display uniformity at the same time.

Description

technical field [0001] The present application relates to the technical field of displays, in particular to a pixel circuit based on a double-gate transistor and a driving method thereof. Background technique [0002] Active matrix organic light-emitting diode (Active Matrix Organic Light-Emitting Diode, OLED) has been widely studied in recent years due to its advantages of high brightness, high luminous efficiency, wide viewing angle and low power consumption, and has been rapidly applied to a new generation of display systems. . The traditional AMOLED pixel unit is a structure of two thin film field effect transistors (ThinFilmTransistor, TFT) and a storage capacitor, such as figure 1 As shown, where T1 is the driving transistor, T2 is the switching transistor, C S For storage capacitors and OLEDs for light emitting devices. The switching transistor T2 responds to the signal from the scan control signal line, samples the signal from the data line, and the storage capaci...

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Problems solved by technology

[0005] Although figure 1 The structure of the pixel circuit shown is simple, but as time goes by, the components in it will age, especially the drive transistor T1 and the organic light-emitting diode OLED will age, resulting in drift in the threshold voltage of the drive transistor T1 and OLED, and the pixel matrix The threshold voltage drift of the drive transistor T1 and OLED of each pixel unit in the pixel matrix is ​​also different; in addition, because the thin film field effect transistor is made of polysilicon material, the threshold voltage of the drive transistor T1 of each pixel unit in the pixel matrix will be V TH It has non-uniform characteristics; in the above two cases, according to the formula (1), it can be seen that the driving current I DS At this time, it will change, which will cause the inhomogeneity of the pixel matrix display

[0006] To solve the problem of pixel matrix display unevenness caused by threshold voltage drift and unevenness of driving transistors and OLEDs, two methods based on intra-pixel compensation have been proposed: current programming scheme and voltage programming scheme.

Although the current programming scheme has relatively high compensation accuracy, it takes a long time to set up, especially in the case of small current and large parasitic capacitance; although the voltage programming scheme has fast driving speed, the compensation accuracy is not ideal, and the current error increases with the threshold voltage variation. bigger and bigger

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