100 dpi 4-a-Si:H TFTs Active-Matrix Organic Polymer Light-Emitting Display

Investigation on the Current Nonuniformity in Current-Mode TFT Active-Matrix Display Pixel Circuitry

“…In both technologies, the luminance of the lighting element is proportional to its current density, and therefore current-mode pixel driving approaches appear to be a natural solution for high quality FEDs or OLEDs. To date, current-copier and current-mirror type pixel circuitry based on amorphous silicon (a-Si) or polycrystalline silicon thin film transistor (poly-Si TFT) technologies have been proposed for the active matrix addressed OLEDs [3], [4]. Lin et al [5] used a current-mirror-based switch-current memory pixel circuit for OLEDs to improve the accuracy and operation frequency, and Levy et al [6] has already designed a CMOS subthreshold-voltage-scaling current-mirror driver for OLED-on-silicon to improve the bandwidth and settling behavior.…”

70.3: Current-Scaling a-Si:H TFT Pixel Electrode Circuit for AM-OLEDs

“…To demonstrate the current-scaling function of the pixel electrode circuit in comparison with both the conventional current-driven [4] and current-mirror pixel circuits [7], we fabricated all three pixel electrode circuits using the same a-Si:H TFT technology, and measured I AVE as a function of I DATA for each pixel electrode circuit as shown in Fig. 5.…”

“…Over last several years, it was shown by several authors [1][2][3][4][5] that the current driving pixel electrode circuits are among the most desirable solutions for active-matrix organic light-emitting displays (AM-OLEDs). However, as display size and resolution increase, a large timing delay can be observed at a low data current and its importance increases with the display size [6].…”

A Simple and Effective Approach to Improve the Output Linearity of Switched-Current AMOLED Pixel Circuitry

“…Compared with the voltage-mode driving methodology, the current-mode one has advantages such as improved display spatial uniformity, good environmental immunity, excellent linearity, and proven long-term stability [2], and thus, it is preferred for highperformance active-matrix OLEDs (AMOLEDs). To realize current-mode AM driving, the switched-current (S-I)-type pixel circuits were developed to control and drive the OLED elements [3], [4]. The long-time and signal-dependent settling problems in the S-I pixel circuits can be solved to meet the video bandwidth requirements by using current-scaling [5], [6], current-feedback [7], or hybrid driving approaches [2].…”