Passive matrix

The upper limit for passive matrix OLEDs thus depends on many factors, including the reverse current of the diodes, the current delivery of the row drivers, the roll-off in OLED power efficiency, and the brightness and contrast ratio requirements of the application. The practical limit is probably less than VGA resolution (480 rows by 640 x 3 columns, where the factor of 3 reflects the RGB subpixels for color) for power-sensitive portable applications. However, such considerations are less important where a wall-plug is available and one company in Japan (Idemitsu Kosan [190]) has demonstrated full color television using passive OLED arrays. 

D Braun, J Rowe, and G Yu, Crosstalk and image uniformity in passive matrix polymer LED displays, Synth. Met., 102 920-921, 1999. 

Displays based on OLEDs may be addressed either passively or actively [124], and the drive requirements are quite different in each case. In passive-matrix addressing, the display is addressed one line at a time, so if a display has 480 lines then a pixel can only be emitting for... 

OLEDs grown and encapsulated using these techniques are beginning to show significant promise. Recently, Chwang et al. demonstrated the effects of flexing a 64x64 (180 dpi) passive-matrix flexible OLED (FOLED) display fabricated on a PET substrate with thin film encapsulation [166], In addition, lifetimes of thin-film-encapsulated OLED test pixels on flexible substrates have now been demonstrated to be thousands of hours [162,167],... 

M Arai, K Nakaya, O Onitsuka, T Inoue, M Codama, M Tanaka, and H Tanabe, Passive matrix display of organic LEDs, Synth. Met., 91 21-25, 1997. 

J. Bimstock, J. Biassing, A. Hunze, M. Stoel, K. Heuser, J. Worle, A. Winnacker, and G. Wittmann, Screen-printed passive matrix displays based on light-emitting polymers, Appl. Phys. Lett., 78 3905-3907, 2001. 

Kodak is commercialising its low molecular weight OLEDs for use in both passive and active matrix display architectures. It has also licensed its technology to Pioneer Corp who have commercialised passive matrix displays for car radios and cellular phone displays. TDK has displays for cellular phones, personal digital assistants and car instrumentation clusters. Perhaps the most significant collaboration to date has been with Sanyo. Sanyo s capabilities in low-temperature polycrystalline silicon have been married with Kodak s low MW materials to produce a full colour, 5 inch active matrix display, commercialisation of which was expected in 2001. 

Passive Matrix LCD The reahzation of high resolution displays, or even the more simple alphanumeric displays, requires the independent addressing of each pixel. Different matrix techniques have been established common characteristics are the rectangular... 

TABLE 21. Display products in 2000 (AM active matrix, PM passive matrix)... 

On the basis of these initial results passive matrix OLED displays were realized in a German government funded project, headed by AIXTRON, to investigate the potential of OVPD for display applications. Figure 9.17 shows low information-content displays produced on passive matrix substrates and large-area OLEDs. 

Fig. 9.17. Passive matrix display and large-area OLED logos showing RGB and AIXTRON obtained by OVPD at TU Braunschweig.

Active-matrix displays differ from the aforementioned displays in that they have a switch incorporated into each pixel (Tsukada 2000). This removes the limitations encountered in passive matrix displays but requires more sophisticated processing equipment to be used. The dominant pixel switch technology is the amorphous silicon thin-film transistor (TFT) on glass (Tsukada 2000), although other technology... 

Liang, R.C. Hou, J. Zang, H.M. and Chung, J. (2003) Passive Matrix Microcup Electrophoretic Displays. IDMC Digest, 351-354. 

Although there have been several examples of flexible OLED displays on plastics, including passive-matrix OLED displays on poly(ethylene terephthalate) (PET) substrates from Pioneer and Universal Display Corporation [26, 27], and a-Si H TFT-driven monochrome active-matrix OLED displays on poly(ethylene naphthalate) (PEN) from Honeywell [28], there have been no demonstrations of organic TFT-... 

Fig. 10.17 Left a 96 by 64 pixel passive matrix display fabricated with Covion polymer. Right a flexible polymer LED. Reproduced with permission of Covion Organic Semiconductors GmbH.

In cell and molecular biology where mechanisms of enzyme action are not understood and attributed to some kind of Maxwell demon, all is specificity, and the lipids of membranes serve to do no more than act as a passive matrix for proteins and as a protection for the procreation of a uni-dimensional, machine like and stolidly boring DNA. There is more to it than that. 

There are two major types of LCD displays in use in laptops today active matrix screen and passive matrix screen. Their main differences lie in the quality of the image. Both types, however, use some kind of lighting behind the LCD panel to make the screen easier to view. 

Within the passive matrix screen, there are two rows of transistors one at the top, another at the side. When the computer s video circuit wants to turn a particular pixel on (turn it black), it sends a signal to the x- and y-coordinate transistors for that pixel, thus turning them on. This then causes voltage lines from each axis to intersect at the desired coordinates, turning the desired pixel black. Figure 6.20 illustrates this concept. 

The main difference between active matrix and passive matrix is image quality. Because the computer takes a millisecond or two to light the coordinates for a pixel in passive matrix displays, the response of the screen to rapid changes is poor, causing, for example, an effect known as submarining If, on a computer with a passive matrix display, you move the mouse rapidly from one location to another, it will disappear from the first location and reappear in the new location without appearing anywhere in between. 

Figure 13-17. Schematic of a small portion of passive matrix pixel array. Each pixel is defined by the overlap of one row and one column electrode.

The ability to process the luminescent semiconducting polymer from solution enables the introduction of simple and potentially inexpensive methods for manufacturing pixilated displays. There are two general classes of pixilated displays that differ in the manner in which the individual pixels are switched on and off passive matrix displays and active matrix displays. 

FIGURE 6.4.17 (a) Passive matrix and (b) active matrix OLED display pixels. 

The passive matrix consists of a set of row electrodes and column electrodes, with an OLED formed at each intersection. A row is selected for light emission by applying a select voltage pulse, forward biasing the diodes in that row. Currents proportional to the image data for the selected row are applied to the column lines by the driver circuits. All the unselected rows are reverse biased. 

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