Patent Application
20090033631
The present invention relates generally to an electronic drawing surface. The electronic drawing surface may be used, for example, to provide a customizable housing for consumer electronic devices.
Commercially available magnetic drawing surfaces are clean and easily erasable. However, they are bulky and cannot be easily integrated into flexible or conformable housings for electronic devices such as mobile telephones. A software-controllable active display can be made to have such a format, but it increases the size, cost and power consumption of the device.
An electrophoretic display is an information display that forms visible images by rearranging charged pigment particles using an applied electric field. In one example, positively charged white particles and negatively charged black particles are suspended in transparent liquid in a microcapsule. A film of microcapsules is placed between two electrodes: a front common transparent electrode and a rear pixel electrode. A transistor matrix in a backplane is used to apply volatges to the pixel electrodes. The direction of the electric field determines whether white or black particles are pulled to the front viewing surface, since the particles will migrate electrophoretically to the electrode bearing the charge opposite to that on the particles. The rear electrode is divided into a number of small picture elements (pixels), so that an image can be formed by applying the appropriate voltage to each region of the display to create a pattern of black and white regions.
Electrophoretic displays are examples of electronic paper, because of their paper-like appearance and low power consumption. However, an electrophoretic display with a rear electrode array cannot be used as a drawing surface without the use of a position sensing device and corresponding control circuitry to control the rear electrode array. Such components would increase the power consumption.
Other types of displays include cholesteric and nanochromatic displays and displays using liquid powders.
A portable device has been disclosed that has an outer surface of programmable electronic paper. The electronic paper changes appearance in response to data input from a keypad, thereby changing the appearance of the portable device. Keypad entry of data is not suitable for graphical input. In addition, the display requires a keypad and corresponding control circuitry. This makes the display unsuitable as an independent device that can be added to an existing portable device.
The accompanying figures, in which like reference numerals refer to identical or functionally similar elements throughout the separate views and which together with the detailed description below are incorporated in and form part of the specification, serve to further illustrate various embodiments and to explain various principles and advantages all in accordance with the present invention.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.
Before describing in detail embodiments that are in accordance with the present invention, it should be observed that the embodiments reside primarily in combinations of method steps and apparatus components related to a rewritable electronic drawing surface. Accordingly, the apparatus components and method steps have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.
In this document, relational terms such as first and second, top and bottom, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. The terms “comprises,” “comprising,” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element preceded by “comprises . . . a” does not, without more constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element.
The rear electrodes are pixel electrodes that control which color is displayed at each picture element (pixel) of the display. The rear electrodes 106 are coupled by conductive adhesives 108 to backplane switching transistors 110. The transistors are commonly thin-film transistors (TFT's) arranged in an array to form an active-matrix. Each switching transistor corresponds to a pixel electrode and the array is controlled by a display driver 112. The front electrode 104 is a transparent electrode and is common to whole display.
The common electrode 104 and the pixel electrodes 106 are respectively driven at different electric potentials causing electric fields by which the charged pigment particles, in the bistable media layer 102, move in the desired directions to form a desired display content in response to display data.
To use such a display as an electronic drawing surface, the display driver must be provided with the display data. This, in turn, requires some kind of user input device. The display driver and transistors, and possibly the input device, would consume power and add cost and complexity to the device.
Optionally, transparent front electrodes 206 may be used. These may be a conductive polymer, such as PEDOT, that is printed on top of the bistable media layer. The front electrodes provided enhanced electrical contact between a drawing tool (discussed below) and the bistable media layer. In addition, the front electrodes provide a protective layer that protects both the bistable media layer and any underlying product. Multiple front electrodes may be used to enhance the resolution of the drawing surface. In one embodiment, the electrodes are printed in an array.
In operation, a power circuit 208 is coupled to the rear common electrode 204 and also to a drawing tool 210. In one embodiment, the power circuit is integrated with the drawing tool. In a further embodiment, the power circuit is integrated with the underlying product. In a still further embodiment the power supply is a separate unit.
Optionally, a reset cover 212 is provided. In one embodiment, the reset cover includes a single common electrode 212 that may be connected to the power supply circuit 208 and used to reset the drawing surface.
In operation, an electrical potential is generated between the common rear electrode 204 and the drawing tool 210 (or the optional reset cover 212). Provided the field has sufficient strength, the area of the bistable media layer 202 is set according to the direction of the electrical field. In one embodiment, a user-operable switch is provided to enable control of the direction of the electric field generated by the power supply for data correction purposes.
One or more drawing tools 210 may be provided. The drawing tools may have different tip areas so as to allow a user to select the width of a line drawn with the drawing tool or the area of a stamp mark made by the tool. A drawing tool with a large tip area may be provided for use as an eraser.
It will be apparent to those of ordinary skill in the art that other types of bistable media or electronic paper may be used without departing from the present invention. For example, charged particles may be suspended in a fluid that is contained in micro-cups in an embossed surface to form an electrophoretic, bistable media layer.
To reset the drawing surface, a reset cover comprising a common electrode may be placed over the drawing surface. The reset cover applies a common voltage across the drawing surface and causes the surface to become a single color.
The drawing surface may be applied to a variety of objects, including, for example, portable electronic devices, signs and toys. The drawing surface may have a variety of shapes.
In the foregoing specification, specific embodiments of the present invention have been described. However, one of ordinary skill in the art appreciates that various modifications and changes can be made without departing from the scope of the present invention as set forth in the claims below. Accordingly, the specification and figures are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of the present invention. The benefits, advantages, solutions to problems, and any element(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential feature or element of any or all the claims. The invention is defined solely by the appended claims including any amendments made during the pendency of this application and all equivalents of those claims as issued.
