Real-Time Compensation in Organic Light-Emitting Diode Television Displays Using Current Sensing Method With Charge Integrators

This paper proposes a novel method for sensing and compensating for the characteristics of thin-film transistors (TFTs) in organic light-emitting diode (OLED) television (TV) displays. The proposed method uses a charge integrator (CI) to sense the TFT currents and calculates the TFT threshold voltage ( $\text{V}_{\mathbf {TH}}$ ) and transconductance parameter (K) using the two different sensed currents. The sensing of the two different currents can be performed within $300 \mu \text{s}$ , which is the vertical blank time for an ultra-high-definition resolution with a refresh rate of 120 Hz, enabling real-time compensation. A new measurement method of all feedback capacitors ( $\text{C}_{\text {FB}}$ s) of CIs is proposed to overcome the variation of $\text{C}_{\text {FB}}$ . The proposed sensing circuit uses differential sensing and auto-zero methods to provide high panel noise immunity and accurate sensing. The performance of the compensation was estimated using Smart-SPICE (Simulation Program with Integrated Circuit Emphasis) simulation under the conditions of ±0.5 V and ±10 % variations in $\text{V}_{\text {TH}}$ and K, respectively. The simulation demonstrated that the current deviation decreased from a maximum of 98.8 % before compensation to 2.3 % after compensation. The compensation performance of the proposed method was verified using a 13.7-inch active-matrix OLED (AMOLED) panel with a resolution of 960 × 540. The results showed that the current deviation of the 13.7-inch AMOLED panel decreased from 40.4 % before compensation to 2.7 % after compensation. The proposed method offers a more accurate and faster compensation solution for high-resolution and large-sized OLED TV displays compared to conventional methods.