Abstract:
A portable display device includes a flexible electrophoretic display, a circuit board electrically connected to the display, and a base receiving and securing the display and the circuit board therein. The display includes a pair of electrodes for providing an electric field therebetween, and a microcapsule layer positioned between the electrodes. The circuit board is electrically connected to the electrodes of the display for providing power to the electrodes and controlling the electric field generated between the electrodes. The base comprises at least two portion foldable to each other to thereby allow the display to be foldable with the at least two portions.

Description:
FIELD OF THE INVENTION 
   The present invention generally relates to portable display devices, and in particular to a portable display device using an electrophoretic display. 
   DESCRIPTION OF RELATED ART 
   In today&#39;s advancing electronics industry public demand is for greater portability, smaller and lighter are considered superior characteristics of electronic devices. However, conventional display device technology is reaching a limit in just how small a display can be made that still adequately provides a quality image. Typical display devices utilize a rigid design that doesn&#39;t allow for compact storage and mobility. 
   What is needed is a portable display device which overcomes the above-mentioned problems. 
   SUMMARY OF THE INVENTION 
   An exemplary portable display device includes a flexible electrophoretic display, a circuit board electrically connected to the display, and a base receiving and securing the display and the circuit board therein. The display includes a pair of electrodes for providing an electric field therebetween, and a microcapsule layer positioned between the electrodes. The circuit board is electrically connected to the electrodes of the display for providing power to the electrodes and controlling the electric field generated between the electrodes. The base comprises at least two portion foldable to each other to thereby allow the display to be foldable with the at least two portions. 
   Other systems, methods, features, and advantages of the present portable display device will be or become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional systems, methods, features, and advantages be included within this description, be within the scope of the present apparatus, and be protected by the accompanying claims. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Many aspects of the present portable display device can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present device. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
       FIG. 1  is an isometric view of a portable display device in an unfolded state, according to a first embodiment, the portable display device including a display and a circuit board; 
       FIG. 2  is a schematic view showing the display and the circuit board of the portable display device of  FIG. 1 ; 
       FIG. 3  is a schematic view showing a cross-section of the display; 
       FIG. 4  is a schematic view showing architecture of a microcapsule in the display; 
       FIG. 5  is an isometric view of the portable display device of  FIG. 1 , showing a half-folded state thereof; 
       FIG. 6  is an isometric view of the portable display device of  FIG. 1 , showing a fully-folded state thereof; and 
       FIG. 7  is an isometric view of a portable display device in accordance with a second embodiment. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Reference will now be made to the drawings to describe the embodiments of the present portable display, in detail. 
   Referring to  FIG. 1 , the portable display device in accordance with a first embodiment includes a base  10 , a display  20 , a stylus  30 , a plurality of buttons  40 , and a hinge  50 . The base  10  is a main body of the portable display device, and is divided into a first portion  12  and a second portion  14  by the hinge  50 . The first and second portions  12 ,  14  are rotatable with respect to each other around an axis of the hinge  50 . The display  20  is fixed in a rectangular frame of the base  10 . The stylus  30  is removably fixed to a side of the base  10  for entering information on the display  20 . The buttons  40  are arranged at a corner or corners of the base  10  to activate designated functions. 
   Also referring to  FIG. 2 , the display  20  is embedded in the base  10  with a viewing surface  21  thereof exposed to users. The display  20  is electrically connected to a circuit board  70  via a flexible cable  23  to achieve data transmission between the circuit board  70  and the display  20 . The circuit board  70  is secured in the base  10 , under the display  20 . The circuit board  70  is a controller and a power supplier of the display  20 . 
   Usually, displays can be sorted into a luminous type display and a non-luminous type display according to their light sources. Cathode-ray tube (CRT) displays are typical luminous type displays but occupy a lot of space. Liquid crystal displays (LCDs) are typical non-luminous type displays. An LCD is a kind of rigid flat panel display with a relatively smaller thickness. 
   The above-mentioned kinds of displays are unsatisfactory in flexibility. An electrophoretic display is a flexible and foldable flat panel non-luminous type display, which utilizes electrophoresis. In electrophoresis, to create an image, an electric field is applied to a dispersion liquid having particulates dispersed in a liquid phase dispersion medium, particles naturally charged by the dispersion (electrophoretic particles) migrate according to a Coulomb force to create a desired image. The display  20  is such a flexible electrophoretic display. 
   Referring to  FIG. 3 , a cross-section of the display  20  is illustrated. The display  20  includes a first substrate  22 , a second substrate  24 , a microcapsule layer  26 , a first electrode  27 , and a second electrode  28 . The microcapsule layer  26  is constructed by a plurality of procumbent microcapsules  60 . The microcapsules  60  are transparent, and are glued together with transparent adhesive. The first electrode  27  and the second electrode  28  are respectively positioned at two opposite sides of the microcapsule layer  26  at a predetermined interval, to provide an electric field therebetween. The first and second substrates  22 ,  24  are respectively positioned at the two opposite sides of the microcapsule layer  26  to sandwich and protect the microcapsule layer  26  and the first and second electrodes  27 ,  28 . One of the first and second electrodes  27 ,  28  is a common electrode, and the other is a pixel electrode to provide an electric difference in potential with respect to the common electrode. At least one of the first and second electrodes  27 ,  28  is transparent and at least one of the first and second substrates  22 ,  24  adjacent to the transparent electrode is transparent. The transparent electrode is set as the viewing surface  21 . In order to be flexible, the first and the second substrates  22 ,  24  can be chosen to be made of plastic material. The display  20  can be made by plastic transistor technology. Plastic transistor technology is process whereby circuits are formed on plastic such as flexible plastic used in the present embodiment. 
   A detailed structure of the microcapsules is shown in  FIG. 4 . Each microcapsule  60  encloses a plurality of color particles  61 , white particles  62 , and a dispersing medium  63  for the particles  61 ,  62 . The color particles  61  are selected from red (R) particles, green (G) particles, and blue (B) particles, while the white particles  62  are used as non-display particles. The color particles  61  and the white particles  62  carry unlike charges. That is, the color particles  61  have a positive charge and the white particles have a negative charge, or vice-versa. The dispersing medium  63  is encapsulated to separate the color particles  61  from the white particles  62 , preventing the color particles  61  and the white particles  62  from collecting together due to their mutual attraction to each other. When a given electric potential difference is provided to the first and second electrodes  27 ,  28 , the color particles  61  and the white particles  62  are arranged in a desired pattern. The desired pattern remains viewable without further power needing to be supplied until a next electric potential is provided to the first and second electrodes  27 ,  28  thus creating a new desired pattern. In this way, desired images and text are accordingly presented on the viewing surface  21 . A diameter of the microcapsulcs  60  is from 30 to 100 micrometers (μm), so the display  20  has high definition and contrast. Because the display  20  is a non-luminous display with low radiation, it is suitable for prolonged viewing. Moreover, since power is not required by the display  20  for continuous display of a given desired pattern, the display  20  has relatively lower power consumption. 
   In order to use the stylus  30  as an input device, a pressure sensor  29  is inserted between the microcapsule layer  26  and one of the substrates  22 ,  24 . The pressure sensor  29  is used for sensing a pressure applied thereon. The pressure sensor  29  is connected to the circuit board  70 , and transmits a signal, which is input to the circuit board  70  in response to an applied pressure thereon. The circuit board  70  receives the signal, and rcsponds to the input in a pre-determined desired manner. For example, a location of the applied pressure on the screen may correspond to a user selecting a function from a menu viewed on the display  20  and applying the stylus  30  thereto, or the pressure applied may result in an image depicting the patterns of applied pressure for forming a picture or handwritten text to he stored in a memory or transmitted by some communication medium. 
   Referring to  FIG.5  and  FIG. 6 , two different states of the portable display device are respectively illustrated. The portable display device can be folded for compact storage by pivoting the second portion  14  to cover the first portion  12  about the hinge  50 . The fully-folded portable display device, as shown in  FIG. 6 , is small and compact with superior portability. The portable display device adopting the flexible electrophoretic display  20 , can be configured to be folded in a variety of ways as desired. 
   Referring to  FIG. 7 , a portable display device in accordance with a second embodiment is illustrated. The portable display device includes a base  80 , a display  20 , a stylus  30 , a plurality of buttons  40 , a pair of hinges  90 , and a circuit board (not shown). The base  80  is divided into a first portion  82 , a second portion  84 , and a third portion  86 . The first, second and third portions  82 ,  84 ,  86  of the base  80  are successively pivotably attached by the hinges  90 . The portable display device can thus be twice folded to reduce the storage size thereof to one third of its original size, thereby achieving a very compact effect. 
   As described above, the portable display device adopts an electrophoretic display. The electrophoretic display has low radiation and power consumption, and high definition and contrast. It is suitable for many electronic devices. 
   It should be emphasized that the above-described embodiments of the present invention, including any preferred embodiments, are merely possible examples of implementation of the principles of the invention, and are merely set forth for a clear understanding of the principles of the invention. Many variations and modifications may be made to the above-described embodiments of the invention without departing substantially from the spirit and principles of the invention. All such modifications and variations are intended to be included herein within the scope of this disclosure and the present invention and be protected by the following claims.