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Driving methods for a roll blind display

IP.com Disclosure Number: IPCOM000030857D
Publication Date: 2004-Aug-30
Document File: 1 page(s) / 37K

Publishing Venue

The IP.com Prior Art Database

Abstract

ID695772 and ID695774

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This is the abbreviated version, containing approximately 52% of the total text.

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ID 695772, ID 695774

Driving methods for a roll blind display

    In Figure 1 the roll blind principle is shown. A substrate is covered with ITO transparent column electrodes. These are covered with a thin dielectric to electrically isolate the column electrodes. The thin dielectric can be made to function as a color filter. A foil is deposited which is covered with a conductive row electrode. This foil is glued to the dielectric on one side of every column of pixels. The row electrodes are in between the dielectric and the foil. In reflective mode the front side of the foil is covered with a white layer to reflect the ambient light. Rectangular cuts are made on three sides after which it is heated to shrink the foil, which in turn rolls up. This opens up the pixel giving a white pixel in transmissive mode or a dark pixel in reflective mode. When applying a certain voltage difference between the columns and the rows, the electrostatic forces rolls down the foil to the substrate, thereby covering the pixel and creating a dark pixel in transmissive mode or a white pixel in reflective mode.

    A roll blind pixel is sensitive to the amplitude of the voltage, the polarity is not important. It shows that most dielectric materials show charging behavior. The capacitor, formed by a pixel, charges up, which reduces the electrostatic force and a pixel can unroll.

    To reduce this, in a display polarity over a pixel is reversed repeatedly. Charging can be different dependent on the polarity of the voltage applied to a pixel. This charging can be reduced by making the time shorter for a negative polarity than for a positive polarity (or vice versa). Charging the polarity makes it necessary to create drivers with more levels than would be necessary if no charging occurs. Addressing a display only for one polarity, while the data on the display remains unchanged is possible by the ti...