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 (V_TH) and transconductance parameter (K) using the two different sensed currents. The sensing of the two different currents can be performed within 300 μs, 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 (C_FBs) of CIs is proposed to overcome the variation of C_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 V_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.