| abstract |
Electroluminescent (EL) subpixels, such as organic light emitting diode (OLED) subpixels, are compensated for aging effects such as threshold voltage Vth shift, EL voltage Voled shift, and OLED efficiency loss. . At one or more measurement reference gate voltages, the drive signal for the subpixel is measured to form a status signal representative of the characteristics of the drive transistor and EL emitter of the subpixel. Current measurements are made in the linear operating region of the drive transistor, improving the signal-to-noise ratio in systems such as modern LTPS PMOS OLED displays, which display has a relatively small Voiced shift over its lifetime, Therefore, it has a relatively small current change due to channel length modulation. Various noise sources are also suppressed, further increasing the signal to noise ratio. |