Multi-line addressing driving technology in OLED displays

A multi-line addressing technique is one that simultaneously drives one or more traces in a display to increase the frame rate without increasing the line speed. Especially for O LED displays, multi-line addressing technology can reduce power consumption, extend life cycle, and often provide active matrix functions for passive OLED (POLED) displays.

Since each pixel of a passive OLED display has a true active component, an organic light-emitting diode (OLED), it can be used as a demodulator for amplitude-modulated orthogonal frequency division multiplexing (OFDM) carriers on the display line signal. . Although this complicated method of addressing pixels in the display does not seem necessary at first (after all, we only need to increase or decrease the row and column signals for most displays), but as can be seen from Figure 1, any Any method that uses binary (digital) signals cannot address multi-line pixels without affecting other line pixels. As shown in Figure 1, when trying to digitally control two pixels of different traces (pixel 1 and pixel 8 in the figure), it causes two or more unintended pixels, such as pixel 1 and pixel 7, to be activated. They are the mirror pixels of Pixel 2 and Pixel 8, respectively.

Figure 1 Problems faced by digital multi-line addressing


Due to the above-mentioned problem of digital control, the pixel-level multi-line addressing method has always been analogous. The image data is still processed digitally in the processor, but the image decomposition method is used to decompose the image into row and column data, and then convert it into an analog signal by a digital analog converter (DAC). The analog row and column signals are typically OFDM carriers, and each frequency element in the row and column signals represents the control of a single pixel in the display.

Multi-line addressing POLED displays can now be implemented (without the use of Walsh functions, can be used in any active matrix display, such as active addressing for passive LCDs only), as early as the 1995 patent application 5644340 (US) in. In this method, each column of the display is an independent reference frequency (same as the local oscillator), and each row of signals is a linear combination of all column reference frequencies within a particular amplitude.

The intersection of each row and column signal maps the frequency control of each pixel (each column signal has the same frequency, but the frequency of each line of signal is different). Each pixel contains a simple demodulation circuit that demodulates the input reticular signals to produce a signal amplitude that controls the brightness of the pixels (Figure 2). In this way, all pixels can be controlled at the same time and exhibit different brightness.

Figure 2 pixel unit architecture

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