The invention provides a grid drive circuit with the self-compensation function. The grid drive circuit comprises a plurality of cascaded grid driver on array (GOA) units. The Nth grade of GOA unit comprises an upward-pull control module, an upward-pull module, a downward-transfer module, a first downward-pull module, a bootstrap capacitor module and a downward-pull maintaining module; the upward-pull module, the first downward-pull module, the bootstrap capacitor module and the downward-pull maintaining module are electrically connected with the Nth grade grid signal point Q(N) and the Nth grade horizontal scanning line G(N), the upward-pull control module and the downward-transfer module are electrically connected with the Nth grade grid signal point Q(N), and the first direct-current low voltage VSS1 and the second direct-current low voltage VSS2 are input into the downward-pull maintaining module. Due to the design of the downward-pull maintaining module with the self-compensation function, reliability of long-term operation of the grid drive circuit is improved; moreover, the design of the downward-pull maintaining module directly controlled by a set of direct-current signal source DC can be adopted for the grid drive circuit with the self-compensation function, and therefore not only can circuit layout design space be saved, but also the overall power consumption of the circuit can be reduced.

Grid drive circuit with self-compensation function

The present invention provides a scan driving circuit for oxide semiconductor thin film transistors, a pull-down holding circuit part ( 600 ) employed in the scan driving circuit for the oxide semiconductor thin film transistors comprises a main inverter and an auxiliary inverter. By introducing a constant low voltage level (DCL) and setting the constant low voltage level (DCL)<the second negative voltage level (VSS 2 )<the first negative voltage level (VSS 1 ), the influence of electrical property of the oxide semiconductor thin film transistors to the scan driving circuit, particularly the bad function due to the electric leakage issue, can be prevented to ensure that the pull-down holding circuit part ( 600 ) can be normally pulled down in the functioning period and at higher voltage level in a non-functioning period to effectively maintain the first node (Q(N)) and the output end (G(N)) at low voltage level.

Scan driving circuit for oxide semiconductor thin film transistors

This brief develops a novel hydrogenated amorphous silicon thin-film transistor (a-Si:H TFT) gate driver with short rising and falling times. The driving capability of the a-Si:H device is improved owing to the enlarged gate voltages by the two-step-bootstrapping structure of the proposed gate driver. The measured rising time, falling time, and voltage swing of the output waveform are $2.05~\mu$ s, 1.31 $\mu$ s, and 27.1 V, respectively, after an accelerated lifetime test at 70 °C for 120 h.

Gate Driver Based on a-Si:H Thin-Film Transistors With Two-Step-Bootstrapping Structure for High-Resolution and High-Frame-Rate Displays

A hydrogenated amorphous silicon (a-Si:H) thin-film transistor (TFT) gate driver on array with low-level holding TFTs (LLH TFTs) biased under bipolar pulse is investigated. It is shown that the bipolar bias at low frequency significantly alleviates the threshold voltage shift of the LLH TFTs. As a result, the lifetime of the proposed gate driver is demonstrated to be several times of that under the conventional unipolar pulse bias. In addition, the improvement in the lifetime becomes more significant at the higher work temperature. The liquid crystal display television panels (32-in, $1366\times \textrm {RGB}\times 768$ ) with the proposed a-Si:H gate drivers integrated on array are manufactured, and the feasibility of the proposed driving scheme is well verified.

Integrated a-Si:H Gate Driver With Low-Level Holding TFTs Biased Under Bipolar Pulses

This paper proposes a new hydrogenated amorphous silicon thin-film-transistor-based (a-Si:H TFT-based) gate driver circuit that uses the time-division driving method to ameliorate the display-to-touch crosstalk. The proposed work utilizes a recharging circuit to discharge the voltage on the gate node of the driving TFT when the touch sensing starts with the purpose of suppressing the long-term stress of the driving TFT, and charges the gate node of the driving TFT again before the end of the touch-sensing period to enhance the driving capability of the gate driver circuit. Furthermore, the proposed gate driver circuit achieves bidirectional transmission and an adjustable reporting rate of touch sensing. Measurements verify that the threshold voltage shift of the driving TFT is suppressed from 4.8 to 2.9 V after 120 h of stress at 85 °C and the output waveforms of the proposed gate driver circuits are generated correctly with forward transmission, backward transmission, and pausing in different stages. Moreover, the measured output waveforms are stable without distortion after 360 h reliability test at 85 °C. Consequently, the proposed gate driver circuit is suitable for use in 5.46-in full high-definition panels with in-cell touch technology.

Bidirectional Gate Driver Circuit Using Recharging and Time-Division Driving Scheme for In-Cell Touch LCDs

Threshold voltage shift ( $\Delta V_{\mathrm{ TH}}$ ) effect of hydrogenated amorphous silicon thin-film transistors under bipolar pulse bias stress (BPBS) is investigated. The dependence of the $\Delta V_{\mathrm{ TH}}$ effect on the signal pulsewidth, stress temperature, and negative pulse voltage magnitude of the BPBS is systematically measured, and explained by the charge trapping and detrapping theory. Results show that the BPBS leads to a noticeably suppressed $\Delta V_{\mathrm{ TH}}$ , compared with the conventional unipolar pulse bias stress. It is suggested that the BPBS with proper negative pulse voltage magnitude and low pulse frequency is an effective way of suppressing $\Delta V_{\mathrm{ TH}}$ , especially when the thin-film transistors work relatively at high temperature.

Threshold Voltage Shift Effect of a-Si:H TFTs Under Bipolar Pulse Bias

The invention provides an integrated gate drive circuit and a display panel with the same. The integrated gate drive circuit comprises cascaded multistage gate drive units and multistage additional gate drive units, wherein the nth-stage gate drive unit comprises a drive unit (42) and a drop-down unit (44), and the mth-stage additional gate drive unit comprises an additional drive unit (52) and an additional drop-down unit (54). A double-drop-down structure is adopted in the integrated gate drive circuit, a thin film transistor in the drop-down unit and a thin film transistor in the additional drop-down unit in the circuit can be in a bipolar voltage bias working environment, the drift of threshold voltages of the thin film transistor in the drop-down unit and the drift of threshold voltages of the thin film transistor in the additional drop-down unit are restrained effectively, the service life of the circuit is prolonged, and the circuit can meet the demands of large and medium size display panels better. Meanwhile, the circuit is simple in structure, low in power consumption and suitable for working at low temperature and high temperature.

Integrated gate drive circuit and display panel with same

A high reliable amorphous silicon gate driver with shared dual pull-down units is proposed and fabricated for large-sized TFT-LCD applications. A special unit in the driver is designed to generate bipolar pulse bias for low-level holding TFTs to suppress the threshold voltage shift, which achieves 40.5% and 34.8% improvement compared with conventional DC and unipolar pulse bias respectively according to measurement results.

P‐12: A‐Si:H TFT Gate Driver with Shared Dual Pull‐Down Units for Large‐Sized TFT‐LCD Applications

The invention discloses a gate driving circuit unit and a gate driving circuit The gate driving circuit unit comprises a driving control module, a driving module, a low-level maintaining module, a scanning signal output end and a transmission signal output end The driving control module further comprises bootstrap series units The gate driving circuit comprises the gate driving circuit units in N-grade cascade connection The driving control module of the gate driving circuit unit controls the driving module to be in a charging or discharging state according to an input signal; the driving module charges the scanning signal output end and the transmission signal output end in a charging state and discharges the scanning signal output end and the transmission signal output end in a discharging state According to the design of bootstrap series units, when the threshold voltage of a transistor is negative, electric leakage at a driving control end can be inhibited; when the threshold voltage of the transistor is positive, charging of the driving control end can be accelerated, so that rising/dropping time of an output signal is shortened, and the threshold voltage application range of the circuit is expanded

Limei Zeng

Papers

Integrated a-Si:H Gate Driver With Low-Level Holding TFTs Biased Under Bipolar Pulses

Threshold Voltage Shift Effect of a-Si:H TFTs Under Bipolar Pulse Bias

Integrated gate drive circuit and display panel with same

P‐12: A‐Si:H TFT Gate Driver with Shared Dual Pull‐Down Units for Large‐Sized TFT‐LCD Applications

Gate driving circuit unit and gate driving circuit