Power saving through state retention in IGZO-TFT AMOLED displays for wearable applications

Abstract

We present a qHD (960 × 540 with three sub‐pixels) top‐emitting active‐matrix organic light‐emitting diode display with a 340‐ppi resolution using a self‐aligned IGZO thin‐film transistor backplane on polyimide foil with a humidity barrier. The back plane process flow is based on a seven‐layer photolithography process with a CD = 4 μm. We implement a 2T1C pixel engine and use a commercial source driver IC made for low‐temperature polycrystalline silicon. By using an IGZO thin‐film transistor and leveraging the extremely low off current, we can switch off the power to the source and gate driver while maintaining the image unchanged for several minutes. We demonstrate that, depending on the image content, low‐refresh operation yields reduction in power consumption of up to 50% compared with normal (continuous) operation. We show that with the further increase in resolution, the power saving through state retention will be even more significant.

35‐2: 40x Current Variation Reduction Enabled by an External VT‐Compensation Scheme for AMOLED Displays using a 3T2C‐Pixel Circuit with Dual‐Gate TFTs

“…The compensation principle is validated on a display with a self-aligned a-IGZO dual-gate TFT backplane. The backplane technology and layer stack, schematically represented in Figure 1, is similar to the backplane described in [5], however a back-gate (BGate) is added.…”

“…In this situation, the video data on the front-gate remains and the calibration data on the back-gate is refreshed. Since the retention in a-IGZO is very good, as shown in [5], the calibration refresh rate can be much slower than the frame rate, so it has no impact on the visual experience.…”

High refresh rate and low power consumption AMOLED panel using top‐gate n‐oxide and p‐LTPS TFTs

“…Due to the limited amount of battery, it is important to reduce power consumption of the display. To reduce power consumption, one of the approach is adapting pixel circuit for low refresh rate driving 1 . On the other hand, there is also a tendency to require high refresh rate driving (generally up to 120 Hz) 2 .…”

Oxide semiconductor thin-film transistors with nano-splitting and field-surrounding channels fabricated by subwavelength photolithography

“…Oxide semiconductors with high tunability of carrier concentrations, as major components of thin film transistors (TFTs), are widely applied in the field of sensors [1,2], optoelectronic [3,4] and the driving circuits of liquid-crystal display [5,6] as well as organic light-emitting diode [7,8]. With the development of the application, the requirement of the device performance synchronously increases, such as enhancing the output current, field-effect mobility and improving the switching speed.…”