Abstract:
A transflective electrophoretic display and a method for manufacturing the same are proposed. The transfiective electrophoretic display including a top substrate and a bottom substrate, multiple separating walls disposed between the top and bottom substrates, a transflective film, and an electrophoretic display medium, can be designed to display colors by using multicolor electrophoretic display media or color filters. The display can be viewed with or without ambient light by adopting a backlight module, as well as to improve the overall display quality.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention is related to a transflective electrophoretic display and a method for manufacturing the same, and more particularly, to a display structure that changes the behavior of charged pigment particles via adjustment of an electric field and a method for manufacturing the display structure.  
         [0003]     2. Description of Related Art  
         [0004]     An electrophoretic display adjusts an electric field to control the distribution of charged particles to change its display regions&#39;reflectance for ambient light and thus to display images. The electrophoretic display is flexible and the images shown on the electrophoretic display can be viewed by using ambient light. Furthermore, the electrophoretic display can be made by using a roll-to-roll manufacturing procedure. It is thus convenient for mass production and its cost can also be reduced. Moreover, the visual angle of the electrophoretic display is unlimited. Hence, the images shown on the electrophoretic display can be viewed from any angle. In addition, the electrophoretic display is insensitive to spacing variation of substrates and possesses bistability. Hence, the technology of the electrophoretic display is vital for development of flexible displays or electronic papers.  
         [0005]     In general, the surfaces of particles can be charged via the dissociation per se or absorption of other charged materials. When the charged particles are put in an electric field, they drift toward an oppositely charged pole. This phenomenon is called electrophoresis. The speed of electrophoresis alters with the categories, diameters, and concentration of charged particles, the intensity, distribution, and direction of external electric fields, and the categories of display solvents. The electrophoretic display shows the images by using the properties of electrophoresis.  
         [0006]     U.S. Pat. No. 6,750,844 discloses an electrophoretic display structure. This patent discloses a transparent film made with microcapsules and coated with an adhesive material. The microcapsules include display solvent with white and black particles having opposite electric poles. The transparent film is disposed on a substrate with a driving circuit to provide a display device. U.S. Pat. No. 6,751,007 and 6,750,844 further disclose an electrophoretic display structure with separating walls. The separating walls are formed between display units to make the display structure stronger than the previous one. The shape, size, and proportion of the separating walls determine the implementation manner of the display structure. Hence, the separating walls are the main members of the display structure. The rooms formed between the separating walls are filled with an electrophoretic display solvent having pigment particles. Moreover, by using a microcup technology proposed in these two patents, the edge-sealing limitation of the display units is removed and the display structure has a better image-displaying quality. Besides, by using the microcup technology, the display solvent is effectively confined to specific rooms and the display structure can be made flexible.  
         [0007]     A transflective electrophoretic display is disclosed in U.S. Pat. No. 6,751,007. The display device has multiple display cells  103  separated by separating walls  109 .  FIG. 1A  shows a display cell  103  of the transflective electrophoretic display. The display cell  103  has a top transparent layer  101  and a bottom electrode plate  102  and is surrounded by the separating walls  109 . The room formed between the separating walls  109  is filled with a dielectric display solvent  105  having multiple charged pigment particles  104 . A sealing layer  106  is provided on the dielectric display solvent  105  to confine it to the room formed between the separating walls  109 . The display cell  103  is thereby completed. In addition, a backlight module  107  is provided to assist the electrophoretic display device to display images.  
         [0008]     In the prior art shown in  FIG. 1A , in order to perform the display function, the charged pigment particles  104  of the dielectric display solvent  105  are controlled by the electric field provided by the top and bottom substrates, i.e. the top transparent layer  101  and the bottom electrode plate  102 . The electric field is provided in accordance with an up/down switching mode, an in-plane switching mode, and a dual switching mode. As shown in  FIG. 1A , the top substrate is made of ITO glass. The bottom substrate includes in-plane electrodes  110 a and  110 b, bottom electrodes  111 , and gaps  112 .  
         [0009]     The technology for providing in-plane electric fields can be found in U.S. Pat. No. 6,639,580, “Electrophoretic Display Device and Method for Addressing Display Device.” The in-plane electric field is produced via the in-plane electrodes disposed on the substrate, i.e. the first and second display electrodes. The charged pigment particles of the electrophoretic display solvents are controlled by the electric fields to perform the display function.  
         [0010]     Reference is made to  FIG. 1B , which shows an embodiment of the prior art disclosed in U.S. Pat. No. 6,751,007. The display structure shown in  FIG. 1B  has multiple microcups, i.e. display cells  103 , which form a rectangular array.  
         [0011]     U.S. Pat. No. 6,751,007 further discloses a color display structure. As shown in  FIG. 2A , each color display cell  20  of the display structure at least has three display sub-cells for providing blue light, red light, and green light, respectively. The colorless display solvent  25  includes multiple white charged pigment particles  24  for scattering light emitted from a backlight module (not shown). The sub-cells have a red color filter  21 , a green color filter  22 , and blue color filter  23 , respectively.  
         [0012]     The electrodes of the bottom substrate are controlled to provide different electric fields to control the charged pigment particles  24  to change the light-scattering extents of the sub-cells. The filters  21 ,  22 , and  23  are used to produce color lights via their light-filtering functions, respectively. Thus, various color effects are provided.  
         [0013]     The white charged pigment particles  24  can be replaced by black charged pigment particles capable of absorbing light. In this way, another display structure with a contrary color-generating operation is provided.  
         [0014]     Reference is made to  FIG. 2B , which shows another color display structure of the prior art. The color display cell  20  includes three display sub-cells for providing blue light, red light, and green light, respectively. The colorless display solvent  25  includes multiple color charged pigment particles. The color charged pigment particles include red charged pigment particles  26 , green charged pigment particles  27 , and blue charged pigment particles  28 . The color display cell  20  has a white or black back plate  29 . The electrodes of the bottom substrate are controlled to provide different electric fields to control the color charged pigment particles  25 ,  27 , and  28  to change the light-scattering extents of the sub-cells. Thus, various color effects are provided.  
         [0015]     Most conventional electrophoretic display devices are reflective display devices. However, this type of display devices cannot show images when ambient light is insufficient or doesn&#39;t exist. On the other hand, transmittance electrophoretic display devices use the electrophoretic display media as light shutter, only. Color light needs to be produced by using color filters together with backlight modules. Thus, the power consumption of transmittance electrophoretic display devices is so large that made this display not suitable for mobile device applications.  
         [0016]     The transflective electrophoretic display disclosed in U.S. Pat. No. 6,751,007 uses the separating walls  109  as a medium for light transmission. In this way, the electrophoretic display can be viewed even in darkness. However, the separating walls  109  may leak light. Furthermore, in this display device, the light emitted from the backlight module doesn&#39;t pass through the display solvent directly and is only used for illumination. Hence, this display device doesn&#39;t have a high display quality. At the same time, it adopts a dual-mode driving mechanism. Hence, this display device is complicated in design and has a difficult manufacturing process.  
       SUMMARY OF THE INVENTION  
       [0017]     An objective of the present invention is to provide a transflective electrophoretic display structure to use both ambient light and backlight as light sources. The display structure of the present invention not only enhances the overall brightness but also illuminates the display area in darkness. The backlight module of the present invention can be adjusted according to the intensity of ambient light so that the power consumption is reduced and the contrast of images is increased. Moreover, since the present invention adopts a simple driving mechanism, the design and manufacturing process can be simplified.  
         [0018]     For achieving the objective above, the present invention provides a method for manufacturing a transflective electrophoretic display having a transflective film. The method includes steps as follows. A top substrate having multiple first electrodes is provided. A bottom substrate having multiple second electrodes is provided. The transflective film is formed on the bottom substrate. Multiple separating walls are provided to form multiple display rooms between the top substrate and the bottom substrate. Finally, the top substrate and the bottom substrate are combined.  
         [0019]     For achieving the objective above, the present invention provides a transflective electrophoretic display, including a top substrate having multiple first electrodes and multiple anisotropic reflective plates, a bottom substrate having multiple second electrodes, multiple separating walls that are made of an opaque material and form multiple display rooms between the top substrate and the bottom substrate, a display medium having multiple pigment particles and transparent display solvents, and a transfiective film disposed on the bottom substrate. The display rooms are filled with the display medium.  
         [0020]     Furthermore, in one embodiment, the transparent display solvents of the display medium can include red, blue, or green display solvents. In another embodiment, the color display solvents can be replaced by using red, green, and blue color filters together with colorless display solvents.  
         [0021]     Numerous additional features, benefits and details of the present invention are described in the detailed description, which follows. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0022]     The foregoing aspects and many of the attendant advantages of this invention will be more readily appreciated as the same becomes better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:  
         [0023]      FIG. 1A  is a schematic diagram showing a display cell of a conventional electrophoretic display device;  
         [0024]      FIG. 1B  is a schematic diagram showing a conventional electrophoretic display device;  
         [0025]      FIG. 2A  is a schematic diagram showing a conventional color display cell;  
         [0026]      FIG. 2B  is a schematic diagram showing another conventional color display cell;  
         [0027]      FIGS. 3A-3D  show a manufacturing procedure of a transflective electrophoretic display device in accordance with the present invention;  
         [0028]      FIG. 4A  shows a transflective electrophoretic display device having a display cell that displays a black color in accordance with the first embodiment of the present invention;  
         [0029]      FIG. 4B  shows a transflective electrophoretic display device having a display cell that displays a white color in accordance with the first embodiment of the present invention;  
         [0030]      FIG. 5A  shows a transflective electrophoretic display device having a display cell that displays a white color in accordance with the second embodiment of the present invention;  
         [0031]      FIG. 5B  shows a transflective electrophoretic display device having a display cell that displays a black color in accordance with the second embodiment of the present invention;  
         [0032]      FIG. 6A  shows a color transflective electrophoretic display device having a color display cell that displays a white color in accordance with the third embodiment of the present invention;  
         [0033]      FIG. 6B  shows a color transflective electrophoretic display device having a color display cell that displays a black color in accordance with the third embodiment of the present invention;  
         [0034]      FIG. 6C  shows a color transflective electrophoretic display device having a color display cell that displays a red color in accordance with the third embodiment of the present invention;  
         [0035]      FIG. 7A  shows a color transflective electrophoretic display device having a color display cell that displays a white color in accordance with the fourth embodiment of the present invention;  
         [0036]      FIG. 7B  shows a color transflective electrophoretic display device having a color display cell that displays a black color in accordance with the fourth embodiment of the present invention;  
         [0037]      FIG. 7C  shows a color transflective electrophoretic display device having a color display cell that displays a red color in accordance with the fourth embodiment of the present invention;  
         [0038]      FIG. 8A  shows a color transfiective electrophoretic display device having a color display cell that displays a white color in accordance with the fifth embodiment of the present invention;  
         [0039]      FIG. 8B  shows a color transflective electrophoretic display device having a color display cell that displays a black color in accordance with the fifth embodiment of the present invention;  
         [0040]      FIG. 8C  shows a color transflective electrophoretic display device having a color display cell that displays a red color in accordance with the fifth embodiment of the present invention;  
         [0041]      FIG. 9A  shows a specific structure of a transflective film in accordance with the present invention;  
         [0042]      FIG. 9B  shows another specific structure of a transflective film in accordance with the present invention; and  
         [0043]      FIG. 9C  shows transmitting paths of the light emitted from the backlight module when a transflective film having cup-shaped openings is used. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0044]     The present invention provides a transflective electrophoretic display device, which has the advantages of reflective and transmittance display devices. The transflective electrophoretic display device has a transparent top substrate. The top and bottom substrates of the display device have electrodes for providing transverse electromagnetic fields. Between the top and bottom substrates form multiple separating walls. A transflective film and a transparent electrophoretic medium having pigment particles are provided on the bottom substrate. The display device can show a monochrome or color images.  
         [0045]     Furthermore, ambient light and backlight both can completely pass through the display medium to enhance the brightness of the display device. Thus, the display device can be viewed without ambient light. Moreover, the intensity of the backlight can be adjusted according to the intensity of ambient light so that the consumption of electric energy is reduced. The embodiments of the present invention are described as follows.  
         [0046]     Reference is made to  FIGS. 3A-3D , which show a manufacturing procedure of a transflective electrophoretic display device in accordance with the present invention. In  FIG. 3A , a top substrate  30  is provided. The top substrate  30  has multiple electrodes (not shown). Multiple color filters can be provided above or beneath the display rooms (not shown). The color filters can be disposed on the top or bottom substrate and their colors can be red, green, or blue. The color filters can also be replaced by an electrophoretic display medium. The top substrate  30  is transparent and has multiple anisotropic reflective plates  42 . The anisotropic reflective plates  42  are located below display cells to reflect light along specific directions. The electrodes of the top and bottom substrates can be driven to form an electric field in accordance with an in-plane switching mode, an up/down switching mode or a dual switching mode.  
         [0047]     In  FIG. 3B , a bottom substrate  32  is provided. The bottom substrate  32  has multiple electrodes and is transparent. The electrodes can be edge electrodes for producing transverse electromagnetic fields. A transflective film  34  is provided on the bottom substrate  32  and can be formed via a sputtering process. The transflective film  34  can be made of a metal material or a transmittance material with a specific structure. Both the transmittance and the reflectance of the transflective film  34  range from 1% to 99%. The transflective film  34  allows back light to pass partially through and partially reflects ambient light. In addition, a light source is disposed below the bottom substrate  32 .  
         [0048]     In Fig . 3 C, multiple separating walls  36  are formed between the top and bottom substrates to form multiple display rooms  38 . The separating walls  36  can be transparent or opaque and form a close and regular structure with a lattice or hexagonal shape. An electrophoretic display medium is infused into the display rooms  38  and its color can be red, green or blue. The electrophoretic display medium can be replaced by multiple color filters. Multiple pigment particles  40  are placed into the display rooms  38 . The pigment particles  40  can be black particles, color particles or transparent color particles.  
         [0049]     In  FIG. 3D , the top substrate  30  and the bottom substrate  32  are combined. A light source can be disposed beneath the bottom substrate  32  (not shown). The light source can be a backlight module.  
         [0050]     Reference is made to  FIG. 4A , which shows a transfiective electrophoretic display device having a display cell that displays a black color in accordance with the first embodiment of the present invention. In this embodiment, the color of the pigment particles is black. When light emitted from the backlight module passes through the bottom substrate  32  and the transflective film  34  to enter the display rooms  38 , the light is reflected by the separating walls  36 , which are opaque in this embodiment, and is passed toward the top substrate  30 . As shown in  FIG. 4A , since the light is completely absorbed by the black particles distributed along and covering the lower surface of the top substrate  30 , the backlight does not pass through the display cell. In this embodiment, the black particles can also be distributed along and covering the upper surface of the bottom substrate  32  (not shown). In addition, since the black particles cover the top or bottom substrate, ambient light is also absorbed by the black particles. Hence, the display cell displays a black color.  
         [0051]     Reference is made to  FIG. 4B , which shows a transflective electrophoretic display device having a display cell that displays a white color in accordance with the first embodiment of the present invention. In this embodiment, the separating walls  36  are opaque. When light emitted from the backlight module passes through the bottom substrate  32  and the transflective film  34  to enter the display rooms  38 , the light is reflected by the separating walls  36  and is passed toward the top substrate  30 . Since the black charged particles are attracted to the lower ends of the separating wall  36 , the light can pass through the display cell completely to show a white color. In addition, the display device of the present invention can also show images via reflection of ambient light. The ambient light first passes through the top substrate  30  to enter the display room  38  and then is reflected out from the display cell by the transflective film  34 . Thus, the display cell displays a white color.  
         [0052]     Reference is made to  FIG. 5A , which shows a transfiective electrophoretic display device having a display cell that displays a white color in accordance with the second embodiment of the present invention. The display cell includes a transparent top substrate  30  and a bottom substrate  32 . Separating walls  36  are disposed between the top and bottom substrates. Anisotropic reflective plates  42  are disposed in the top substrate  30  above the separating walls  36 . Both the transparent top substrate  30  and the bottom substrate  32  have in-plane electrodes for providing transverse electric fields. The pigment particles  40  are distributed near the lower ends of the separating walls  36 . A transflective film  34  is provided on the bottom substrate  32 .  
         [0053]     In this embodiment, the separating walls  36  are transparent and light emitted from a light source disposed beneath the display room  38  can pass through the transflective film  34  and the separating walls  36 . When the light reaches the anisotropic reflective plates  42 , it is not reflected back along the original path but to the display room directly. The light is then reflected out from the display cell by the transflective film  34 .  
         [0054]     Reference is made to  FIG. 5B , which shows a transflective electrophoretic display device having a display cell that displays a black color in accordance with the second embodiment of the present invention. As shown in  FIG. 5B , light emitted from the light source disposed beneath the display room  38  passes through the transflective film  34  to enter the display room  38  and through the separating walls  36  to reach the anisotropic reflective plates  42 . The light is not reflected back along the original path but to the display room directly. Due to the electric field provided by the electrodes of the bottom substrate  32 , the pigment particles  40  are distributed along and cover the lower surface of the top substrate  30 . Thus, the light inside the display room  38  is completely absorbed by the pigment particles  40  and the ambient light cannot enter the display room  38 . Therefore, the display cell displays a black color in this status.  
         [0055]     In the present invention, the electrodes of the bottom substrate are driven to form an electric field in accordance with an in-plane switching mode. The electrodes of the top substrate are driven to form an electric field in accordance with an up/down switching mode, an in-plane switching mode or a dual switching mode. A backlight module can be further included in the present invention and disposed beneath the bottom substrate.  
         [0056]     Furthermore, by modification of the structure, the present invention can provide a display device with color display cells. Each of the color display cells at least has three sub-cells for showing a red color, a blue color and a green color, respectively. A color display cell includes a transparent top substrate and a bottom substrate. Separating walls are disposed between the top and bottom substrates. The top substrate or the bottom substrate has electrodes disposed thereon. The color display cell further includes multiple pigment particles and three transparent color electrophoretic display solvents having a red color, a blue color and a green color, respectively. The color electrophoretic display solvents can be replaced by using color filters together with colorless transparent electrophoretic display solvents.  
         [0057]     The display device of the present invention is capable of using the light emitted from a backlight module or ambient light to display images. Hence, the display device is enhanced in brightness and can be viewed even without ambient light. The light intensity of the backlight module can be adjusted according to the intensity of ambient light to reduce the power consumption and improve on the contrast and color of the images shown.  
         [0058]     Reference is made to FIGS.  6 A-C, which shows a color transflective electrophoretic display device in accordance with the present invention. As shown in FIGS.  6 A-C, a color display cell  50  includes a transparent top substrate  501  and a bottom substrate  502 . Separating walls  52  are disposed between the top and bottom substrates to form display rooms. The bottom substrate  502  has electrodes disposed thereon. The color display cell  50  at least has three sub-cells for showing a red color, a blue color and a green color, respectively. Furthermore, the top substrate  501  can have electrodes capable of being driven to produce an electric field in accordance with an in-plane switching mode, an up/down switching mode or a dual switching mode. The bottom substrate  502  has a transfiective film.  
         [0059]     In this embodiment, the separating walls  52  are opaque. When light passes through the top substrate  501  and color display solvents filling the display rooms, color light is produced. In addition, the color light can also be produced by reflection of ambient light. When ambient light passes through the color display solvents  51 ,  53 , and  55  and then reflected back by the transflective film of the bottom substrate  502 , the color light is produced. In this way, the brightness is enhanced.  
         [0060]     The colors of the color display solvents  51 ,  53 , and  55  are red, green, and blue, respectively. Each of the color display solvents  51 ,  53 , and  55  includes multiple charged pigment particles  54 . When light is reflected from the anisotropic plates of the top substrate  501  into the color display solvents  51 ,  53 , and  55 , light with different colors is produced.  
         [0061]     Reference is made to  FIG. 6A , which shows a color transflective electrophoretic display device having a color display cell that displays a white color in accordance with the third embodiment of the present invention. First, light emitted from the backlight module beneath the bottom substrate  502  passes through the transflective film  512  and enters the display rooms formed between the separating walls  52 . Due to the color display solvents  51 ,  53 , and  55 , red, green and blue lights are produced. In addition, the charged pigment particles in the color display solvents  51 ,  53 , and  55  drift to the lower ends of the separating walls  52  because a predetermined electric field is provided. Thus, the red, green and blue lights can pass through the top substrate  501  and are mixed together to form white light.  
         [0062]     The color display cell can also produce color light by reflection of ambient light. When ambient light passes through the color display solvent  51 ,  53 , or  55  and is reflected back by the transfiective film  512 , the color light is produced. In this way, the overall brightness of the display device is enhanced.  
         [0063]     Reference is made to  FIG. 6B , which shows a color transflective electrophoretic display device having a color display cell that displays a black color in accordance with the third embodiment of the present invention. The color display cell  50  at least has three sub-cells for showing a red color, a blue color and a green color, respectively. First, light emitted from the backlight module beneath the bottom substrate  502  passes through the transflective film  512  and enters the display rooms formed between the separating walls  52 . In order to display a black color, the electric field is controlled to make the black charged particles drift toward and completely cover the lower surface of the top substrate  501 . The light provided by the backlight module thus cannot pass through the top substrate  501 , so the color display cell  50  shows a black color.  
         [0064]     If the color display cell  50  needs to show a red color, as shown in  FIG. 6C , the electric field is controlled to make the black charged particles inside the green display solvent  53  and the blue display solvent  55  cover the lower surface of the top substrate  501  and make the black charged particles inside the red display solvent  51  drift to the lower ends of the separating walls  52 . The light can pass thus through the transfiective film  512  and the red display solvent  51  to make the color display cell  50  show a red color. Similarly, by changing the position of the black charged particles, the color display cell  50  can show various colors.  
         [0065]     The color display cell mentioned above is formed by using the separating walls  52  disposed between the top and bottom substrates. The position of the black charged particles is changed according to the electric field. For example, if the display cell needs to display a white color, all of the black charged particles are attracted to low ends of the separating walls. Thus, light can completely pass through the three sub-cells of the color display cell to produce red, green, and blue lights. Then, the red, green, and blue lights are mixed together to show a white color.  
         [0066]     Reference is made to  FIG. 7A , which shows a color transflective electrophoretic display device having a color display cell displaying a white color in accordance with the fourth embodiment of the present invention. In this embodiment, the separating walls are opaque. The top substrate  601 , the bottom substrate  602 , and the separating walls  62  form multiple display rooms. The display rooms are filled with transparent, colorless, electrophoretic display solvents  61   a ,  61   b , and  61   c . Each of the transparent, colorless, electrophoretic display solvents  61   a ,  61   b , and  61   c contains multiple black charged particles  64 .  
         [0067]     In this embodiment, a color display cell has three display rooms. Each of the display rooms has a color filter disposed therein. The color filter is attached to the lower surface of the top substrate  601 . The colors of the color filters  621 ,  623 , and  625  of the three display rooms are red, green, and blue.  
         [0068]     First, a predetermined electric field is provided to make the charged pigment particles  64  drift to the lower ends of the separating walls  62 . At the same time, light emitted from the backlight module beneath the bottom substrate  602  passes through the electrophoretic display solvents  61   a ,  61   b , and  61   c  and the color filters  621 ,  623 , and  625  to produce red, green and blue lights. The red, green and blue lights are then mixed together to form white light.  
         [0069]     The color display cell can also produce color light by reflection of ambient light. When ambient light passes through the color filters  621 ,  623 , and  625  and is reflected back by the transflective film  66 , color light is produced. In this way, the color display cell doesn&#39;t need to use the backlight module or uses the backlight module just for enhancing overall brightness of the display device.  
         [0070]     Reference is made to  FIG. 7B , which shows a color transflective electrophoretic display device having a color display cell that displays a black color in accordance with the fourth embodiment of the present invention. First, light emitted from the backlight module beneath the bottom substrate  602  passes through the transflective film  66  and enters the display rooms formed between the separating walls  62 . In order to display a black color, the electric field is controlled to make the black charged particles  64  drift toward and completely cover the lower surface of the top substrate  601 . The light provided by the backlight module thus cannot pass through the top substrate  601 , so the color display cell  50  shows a black color.  
         [0071]     If the color display cell needs to show a red color, as shown in  FIG. 7C , the electric field is controlled to make the black charged particles inside the display rooms having the green color filter  623  and the blue color filter  625  cover the lower surface of the top substrate  601  and make the black charged particles inside the display room having the red color filter  621  drift to the lower ends of the separating walls  62 . Hence, the light can only pass through the transflective film  66  and the red color filter  621  to make the color display cell show a red color.  
         [0072]     Reference is made to  FIG. 8A , which shows a color transflective electrophoretic display device having a color display cell that displays a white color in accordance with the fifth embodiment of the present invention. In this embodiment, the separating walls are opaque. The top substrate  701 , the bottom substrate  702 , and the separating walls  72  form multiple display rooms. The display rooms are filled with transparent, colorless, electrophoretic display solvents  71   a ,  71   b , and  71   c . Each of the transparent, colorless, electrophoretic display solvents  71   a ,  71   b , and  71   c  contains multiple black charged pigment particles  74 .  
         [0073]     In this embodiment, a color display cell has three display rooms. Each of the display rooms has a color filter disposed therein. The color filter is attached to the upper surface of the bottom substrate  702 . The colors of the color filters  721 ,  723 , and  725  of the three display rooms are red, green, and blue.  
         [0074]     First, a predetermined electric field is provided to make the black charged pigment particles  74  drift to the lower ends of the separating walls  72 . At the same time, light emitted from the backlight module beneath the bottom substrate  702  passes through the electrophoretic display solvents  71   a ,  71   b , and  71   c  and the color filters  721 ,  723 , and  725  to produce red, green and blue lights. The red, green and blue lights are then mixed together to form white light.  
         [0075]     The color display cell can also produce color light by reflection of ambient light. When ambient light passes through the color filters  721 ,  723 , and  725  and is reflected back by the transflective film  76 , the color light is produced. In this way, the color display cell doesn&#39;t need to use the backlight module or uses the backlight module just for enhancing overall brightness of the display device.  
         [0076]     Reference is made to  FIG. 8B , which shows a color transflective electrophoretic display device having a color display cell that displays a black color in accordance with the fifth embodiment of the present invention. First, light emitted from the backlight module beneath the bottom substrate  702  passes through the transflective film  76  and the color filters and enters the display rooms formed between the separating walls  72 . In order to display a black color, the electric field is controlled to make the black charged pigment particles  74  drift toward and completely cover the lower surface of the top substrate  701 . The light provided by the backlight module thus cannot pass through the top substrate  701 , so the color display cell shows a black color.  
         [0077]     If the color display cell needs to show a red color, as shown in  FIG. 8C , the electric field is controlled to make the black charged pigment particles  74  inside the display rooms having the green color filter  723  and the blue color filter  725  cover the lower surface of the top substrate  701  and make the black charged pigment particles  74  inside the display room having the red color filter  721  drift to the lower ends of the separating walls  72 . Hence, the light can only pass through the transflective film  76  and the red color filter  721  to make the color display cell show a red color.  
         [0078]     Reference is made to  FIG. 9A , which shows a specific structure of a transflective film in accordance with the present invention. The transflective film  80  allows light emitted from the backlight module to pass partially through and partially reflects ambient light. The transfiective film  80  can be made of metal. Both the transmittance and the reflectance of the transflective film  34  range from 1% to 99%. In this embodiment, the transflective film  80  is a reflective film having multiple round holes  82  formed thereon. The round holes  82  are provided for light to pass through. Due to the round holes, light emitted from the backlight module is allowed to pass partially through the transflective film  80  while ambient light is partially reflected.  
         [0079]     Reference is made to  FIG. 9B , which shows another specific structure of a transflective film in accordance with the present invention. In this embodiment, the transflective film  80  is made with cup-shaped openings  84 . When the cup-shaped openings  84  are made, multiple reflective layers  840  are first provided on the cup-shaped openings  84  and then multiple metal films  842  are coated above the reflective layers  840 . The reflective layers  840  are made of resin.  
         [0080]     In the design mentioned above, changing the inclined angle of the sidewall of the cup-shaped opening  84  can effectively improve upon the transmittance of the light emitted from the backlight module. As shown in  FIG. 9C , which shows transmitting paths of the light emitted from the backlight module, the cup-shaped design of the present invention allows more light to pass through the transflective film  80 .  
         [0081]     Although the present invention has been described with reference to the preferred embodiments thereof, it will be understood that the invention is not limited to the details thereof. Various substitutions and modifications have been suggested in the foregoing description, and others will occur to those of ordinary skill in the art. Therefore, all such substitutions and modifications are embraced within the scope of the invention as defined in the appended claims.