Patent Application
20130162511
1. Technical Field
The present disclosure relates to display devices and, more particularly, to an electrophoretic display device.
2. Description of Related Art
Electrophoretic effects are well known among scientists and engineers, wherein electrophoretic particles dispersed in a fluid or liquid medium move under the influence of an electric field. For use as an electronic paper (E-paper) display device, an electrophoretic display is preferred over a liquid crystal display (LCD) because of a better reflectivity and contrast ratio. A typical E-paper display device includes a common electrode, a Thin Film Transistor (TFT) pixel electrode and an electrophoretic medium arranged between the common electrode and the pixel electrode.
The TFT pixel electrode is a special kind of field-effect transistor made by depositing thin films of a semiconductor active layer as well as the dielectric layer and metallic contacts over a supporting substrate. The TFT pixel electrode is too thick to meet the demands of thinner, lighter of the electronic paper display device.
Many aspects of the embodiments can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present disclosure. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.
The disclosure, including the accompanying, is illustrated by way of example and not by way of limitation. It should be noted that references to “an” or “one” embodiment in this disclosure are not necessarily to the same embodiment, and such references mean at least one.
The lower substrate 20 can be made of plastic, or glass, for example. The lower substrate 20 includes a base 21 and a plurality of paralleled row electrodes 22 arranged between the base 21 and the electrophoretic medium 30. A chemistry etching, film printing processing or projection photolithography can be employed to form the plurality of paralleled row electrodes 22 on the surface of the base 21.
The upper substrate 40 can be made of glass, or other transparent materials of high light propagation efficiency, such as polyimide (PI), polycarbonate (PC), or polyethylene terephthalate (PET) or polymethylmethacrylate (PMMA). The upper substrate 40 includes a base 41 and a plurality of paralleled column electrodes 42. The plurality of paralleled column electrodes 42 is transparent and arranged between the base 41 and the electrophoretic medium 30. A chemistry etching, film printing processing or projection photolithography can be employed to form the plurality of paralleled column electrodes 42 on a surface of the base 41, which corresponds to a display surface of the upper substrate 40 to be viewed by a person such as an operator. The paralleled column electrodes 42 can be made of indium tin oxide (ITO).
In this embodiment, the row electrodes 22 are scanning electrodes, a scanning signal is applied on the row electrodes 22, and the column electrodes 42 are signal electrodes, a dynamic driving signal is applied on the column electrodes 42. The electrophoretic medium 30 is refreshed by the electrical field formed between the row electrodes 22 and the column electrodes 42 according to the dynamic driving signal. In other embodiments, the row electrodes 22 are signal electrodes and the column electrodes 42 are scanning electrodes.
The electrical field intensity of the pixel 50 is V, the refreshing time is T.
The formula of a moving distance L1 of the first electrophoretic particles 306 is L1=k1 ∫0T ∫31 VV f(v,t)dvdt; and the formula of a moving distance L2 of the second electrophoretic particles 308 is L2=k2 ∫0T ∫−VV f(v,t)dvdt.
The optical states of the pixel 50 depends on the location of the first electrophoretic particles 306 and the second electrophoretic particles 308 in the microcapsules 302. The location of the first electrophoretic particles 306 and the second electrophoretic particles 308 further depends on their movement distance during refreshing time. The optical states of the pixel 50 can be controlled via controlling the scanning signal applied on the corresponding row electrode 22 and the dynamic driving signal applied on the corresponding column electrode 42.
The electrophoretic medium 30 is driven by the rectangular stripe electrodes arranged on the opposite surfaces of the upper substrate 40 and the lower substrate 20, the E-paper display device 10 is thinner, cheaper and lighter than a E-paper display device employing a TFT pixel electrode.
It is to be understood, however, that even though numerous characteristics and advantages of the present disclosure have been set forth in the foregoing description, together with details of the structure and function of the present disclosure, the present disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the present disclosure to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.
| Number | Date | Country | Kind |
|---|---|---|---|
| 201110437289.X | Dec 2011 | CN | national |
