Abstract:
A display apparatus is disclosed that includes two opposing substrates, an electrophoretic element arranged between the substrates; pixel electrodes that are arranged on one of the substrates and are divided into pixel groups including at least a first pixel group and a second pixel group, a common electrode that is arranged on the other substrate, and a control unit that controls frame display operations of the pixel groups. The control unit controls the first pixel group to start frame display operations for displaying a frame and then controls the second pixel group to start frame display operations for displaying another frame before the frame display operations of the first pixel group are completed.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a display apparatus that uses electrophoretic elements. 
     2. Description of the Related Art 
     It is noted that various forms of paper-type display apparatuses are recently being developed. Such display apparatus technology may be applied to an electronic book that is configured to display an image of one page (frame) of a document on a display unit at one time and successively switch the pages (frames) being displayed to enable a user to virtually turn the pages of the document at a desired speed in a manner similar to turning the pages of an actual book, for example. A display apparatus that uses electrophoretic elements is known as one form of such paper-type display apparatus.  FIGS. 1-3  are diagrams illustrating a configuration of a display apparatus that uses electrophoretic elements according one prior art example. 
       FIG. 1  is a first diagram illustrating a configuration of a display apparatus  100  according to the prior art.  FIG. 2  is a second diagram illustrating a configuration of the display apparatus  100 .  FIG. 3  is an enlarged view of a thin film transistor (TFT)  105  of the display apparatus  100 . 
     As is shown in  FIG. 1 , the display apparatus  100  includes a display unit  120  and a drive circuit  130  that drives the display unit  120 . 
     In the following, the display unit  120  is described with reference to  FIGS. 1 and 2 . 
     The display unit  120  includes an electrode substrate  101 A and a circuit substrate  102 A that oppose each other (see  FIG. 2 ). The electrode substrate  101 A includes a transparent common electrode  101 ; and the circuit substrate  102 A includes thin film transistors (TFT)  105 , scanning lines  106 , and signal lines  107 . The circuit substrate  102 A also includes pixel electrodes  102  that are arranged into a matrix pattern on top of the thin film transistors (TFT)  105 , the scanning lines  106 , and the signal lines  107 . 
     As is shown in  FIG. 2 , a liquid having positively or negatively charged white electrophoretic particles (elements)  103  and black electrophoretic particles (elements)  104  scattered within is sealed between the common electrode  101  and the pixel electrode  102 . It is noted that the white electrophoretic elements  103  and the black electrophoretic elements  104  are charged by differing electrical charges. Also, a fixed voltage is applied to the common electrode  101  arranged on the electrode substrate  101 A. The pixel electrodes  102  arranged on the circuit substrate  102 A are each conductively connected to source electrodes of the TFT  105  arranged on the circuit substrate  102 A (see  FIG. 3 ). 
     With respect to the TFTs  105  arranged on the circuit substrate  102 A, when the TFTs  105  are arranged in the line directions, their gate electrodes  112  are connected to the scanning lines  106  (see  FIG. 3 ). On the other hand, when the TFTs  105  are arranged in the row directions, their gate electrodes  112  are connected to the signal lines  107  of the circuit substrate  102 A (not shown). 
     The TFT  105  controls the amount of current flowing between a source electrode  113  and a drain electrode  114  with the voltage applied to its gate electrode  112 . It is noted that when the source-drain current of the TFT  105  is large, a switch of the TFT  105  is turned on, and when the source-drain current of the TFT  105  is small, the switch of the TFT  105  is turned off. 
     The drive circuit  130  includes a controller  108 , a memory  109 , a scanning line driver  110 , and a signal line driver  111 . The controller  108  controls display operations of the display apparatus  100 . The memory  109  stores display data for each pixel forming a pattern of plural frames to be displayed on the display apparatus  100 . 
     In the following, operations of the display apparatus  100  are described with reference to  FIG. 1 . 
     In the case of displaying a new frame on the display apparatus  100 , a scanning command signal  10 B is transmitted from the controller  108  to the scanning driver  110 . In response to receiving the scanning command signal  10 B, the scanning line driver  110  applies corresponding voltages to the gate electrodes  112  of the TFTs  105  via the scanning lines  106  to control the switching operations of the TFTs  105 . It is noted that the scanning command signal  10 B from the controller  108  includes a control signal for determining the TFTs that are to be turned on, and a control signal for determining the output timing of the voltages to be output from the scanning line driver  110 . 
     Also, the controller  108  transmits an addressing signal  10 A to the memory  109  and a display command signal  10 C to the signal line driver  111 . At the memory  109 , display data  10 D of each pixel forming a pattern of the frame to be displayed are extracted based on the addressing signal  10 A. Then, the extracted display data  10 D are transmitted to the signal line driver  111 . 
     The signal line driver  111  applies corresponding voltages to the gate electrodes  112  of the TFTs  105  via the signal line  107  based on the display command signal  10 C and the display data  10 D. It is noted that the display command signal  10 C from the controller  108  includes a control signal for determining the timing at which the voltage is to be output from the signal line driver  111 . 
     When the TFT is turned on, the voltage applied to the gate electrode  120  of the TFT  105  is applied to the pixel electrode  102 . The pixel electrode  102  is applied a positive voltage or a negative voltage. In turn, an electric field is generated by the difference in potential between the pixel electrode  102  and the common electrode  101  so that the white electrophoretic elements  103  or the black electrophoretic elements  104  move to the common electrode  101  side. In this way, a pattern may be displayed on the common electrode  101  side. 
     As can be appreciated, displaying a frame on the display apparatus  100  involves successively turning on TFTs  105  that are connected to the scanning lines  106  based on the scanning command signal  10 B, and the frame display operations may be completed at the time desired patterns are displayed by all the pixel electrodes  102  connected to the TFTs  105 . In the following descriptions, the process of successively turning on the TFTs  105  is referred to as scanning. 
     In the following, frame switching operations performed at the display apparatus  100  are described with reference to  FIGS. 4 and 5 .  FIG. 4  is a diagram illustrating an exemplary display unit of the display apparatus  100 .  FIG. 5  is a timing chart illustrating frame switching operations of the display apparatus  100 . 
     The illustrated display unit A 01  of  FIG. 4  has scanning lines X 1 -X 6  and signal lines Y 1 -Y 8 . It is noted that scanning lines X 1 -Xm of the timing chart of  FIG. 5  corresponds to the scanning lines X 1 -X 6  of the display unit A 01 , and the signal lines Y 1 -Yn of the timing chart of  FIG. 5  corresponds to the signal lines Y 1 -Y 8  of the display unit A 01 . Also, it is assumed in the following descriptions that the display status of the display unit A 01  at an initial stage corresponds to the display status A of  FIG. 5 , and the display status of the display unit A 01  is switched from display status A to display status B and then from display status B to display apparatus C of  FIG. 5 . 
     In the display apparatus  100 , the scanning lines X 1 -X 6  of the display unit A 01  are successively scanned from scanning line X 1  to scanning line X 6 . Specifically, switching control operations are performed for successively turning on the TFTs  105  connected to the scanning lines X 1  through X 6 . It is noted that in the present case, when the source-drain current of the TFT  105  is at high level (H level), the TFT  105  is turned off, and when the source-drain current of the TFT  105  is at low level L level), the TFT  105  is turned on. 
     In the display unit A 01 , after the elapse of scanning time B 02  corresponding to the time required for completing one scanning process, voltages for displaying patterns representing the display status B of  FIG. 5  are applied to the pixel electrodes  102 . 
     Then, the white electrophoretic elements  103  and the black electrophoretic elements  104  are moved as a result of the generation of an electric field between the pixel electrodes  102  and the common electrode  101 , and the pixel electrodes  102  are switched from one color pattern to another color pattern. After the elapse of pixel pattern switching time B 01  corresponding to the time required for the pixel electrodes  102  to be switched to a different color pattern, the display status of the display unit A 01  is switched from the display status A to the display status B of  FIG. 5 . 
     As can be appreciated from the above descriptions, in switching the frame displayed on the display unit A 01  of the display apparatus  100 , the display switching time required for switching a display of one frame is equal to the total of the scanning time and the pixel pattern switching time. 
     The scanning time of the display apparatus  100  corresponds to the process time required for scanning the scanning lines  106  and applying voltages to the pixel electrodes  102 . It is noted that only a very short time is required for applying voltages to the pixel electrodes  102  so that the scanning time is substantially shorter than the pixel pattern switching time. Therefore, the required time for displaying one frame relies largely on the pixel pattern switching time. 
     The pixel pattern switching time of the display apparatus  100  is around several dozen to several hundred milliseconds (ms) which time is substantially longer than the display switching time for other types of display apparatuses such as the liquid crystal display. It is noted that the pixel pattern switching time depends on characteristics of the electrophoretic elements and is fixed regardless of the display method used. Accordingly, it is difficult to reduce the display switching time for switching the displayed frame by reducing the pixel pattern switching time. 
     Also, the display apparatus may successively switch and display plural frames in order to display a desired frame. For example, with respect to an electronic document including plural pages (frames), a user may turn the pages of the electronic document one page at a time and check the contents of each page to search a desired page. In such a case, since a relatively long display switching time is required in the conventional display apparatus using electronphoretic elements, a relatively long period of time may be required before the desired page may be displayed. 
     Also, it is noted that in the conventional display apparatus that uses electrophoretic elements, the speed at which the pages are turned cannot be adjusted. Therefore, it may take a long period of time before a desired page is displayed when a large number of pages have to be turned to reach the desired page, for example. 
     SUMMARY OF THE INVENTION 
     According to one aspect of the present invention, a technique is provided for reducing the display switching time for successively switching and displaying plural frames in a display apparatus. 
     According to another aspect of the present invention, a technique is provided for enabling adjustment of the display switching speed of a display apparatus in the case of successively switching and displaying plural frames so that a desired page may be promptly displayed. 
     According to one embodiment of the present invention, a display apparatus is provided that includes two opposing substrates, an electrophoretic element arranged between the substrates; pixel electrodes that are arranged on one of the substrates and are divided into pixel groups including at least a first pixel group and a second pixel group, a common electrode that is arranged on the other substrate, and a control unit that controls frame display operations of the pixel groups. The control unit controls the first pixel group to start frame display operations for displaying a frame and then controls the second pixel group to start frame display operations for displaying another frame before the frame display operations of the first pixel group are completed. 
     In one preferred embodiment, the display apparatus according to the above embodiment may include a change unit that changes the number of pixel groups into which the pixel electrodes are divided when a predetermined condition is satisfied during the frame display operations. 
     In another preferred embodiment, the display apparatus according to the above embodiment may include a ratio setting unit that sets information on a ratio of the number of frames to be displayed by each of the pixel groups to the total number of frames to be displayed by the display apparatus, and a ratio change unit that changes the ratio set by the ratio setting unit when a predetermined condition is satisfied during the frame display operations. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram showing a configuration of a display apparatus according to the prior art; 
         FIG. 2  is another diagram showing a configuration of the display apparatus according to the prior art; 
         FIG. 3  is an enlarged view of a thin film transistor of the display apparatus according to the prior art; 
         FIG. 4  is a diagram showing an exemplary configuration of a display unit of the display apparatus according to the prior art; 
         FIG. 5  is a timing chart illustrating frame display switching operations of the display apparatus according to the prior art; 
         FIG. 6  is a block diagram showing a configuration of a display apparatus according to a first embodiment of the present invention; 
         FIG. 7  is a diagram showing a configuration of a display unit of the display apparatus according to the first embodiment; 
         FIG. 8  is a diagram showing exemplary frames that may be displayed by the display unit; 
         FIG. 9  is a timing chart illustrating frame display switching operations of the display apparatus according to the first embodiment; 
         FIG. 10  is a diagram illustrating input signals input to scanning lines and signal lines of the display unit and the display statuses of the display unit corresponding to the timing chart of  FIG. 9 ; 
         FIG. 11  is a flowchart illustrating a successive display switching process of the display apparatus according to the first embodiment; 
         FIG. 12  is a diagram showing a configuration of a display unit of a display apparatus according to a second embodiment of the present invention; 
         FIG. 13  is a timing chart illustrating display switching operations of the display apparatus according to the second embodiment; 
         FIG. 14  is a diagram illustrating input signals input to scanning lines and signal lines of the display unit and the display statuses of the display unit corresponding to the timing chart of  FIG. 13 ; 
         FIG. 15  is a flowchart illustrating operations for determining the number of pixel groups into which pixel electrodes of the display unit are to be divided; 
         FIG. 16  is a flowchart illustrating a successive display switching process of the display apparatus according to the second embodiment; 
         FIG. 17  is a timing chart illustrating display switching operations of a display apparatus according to a third embodiment of the present invention; 
         FIG. 18  is a flowchart illustrating operations for determining the ratio of the number of frames to be displayed by each pixel group to the total number of frames to be displayed by the display unit of the display apparatus according to the third embodiment; 
         FIG. 19  is a flowchart illustrating a successive display switching process of the display apparatus according to the third embodiment; 
         FIG. 20  is a block diagram showing a configuration of a display apparatus according to a fourth embodiment of the present invention; 
         FIG. 21  is a diagram showing an exemplary manner in which pixel electrodes are divided into two pixel groups in a display unit of the display apparatus according to the fourth embodiment; 
         FIGS. 22A and 22B  are diagrams showing other exemplary manners in which the pixel electrodes are divided into two pixel groups in the display unit according to the fourth embodiment; 
         FIG. 23  is a diagram showing exemplary frames that may be displayed by the display apparatus according to the fourth embodiment; 
         FIG. 24  is a timing chart illustrating display switching operations using two pixel groups that are performed by the display apparatus according to the fourth embodiment; 
         FIG. 25  is a diagram illustrating input signals input to scanning lines and signal lines of the display unit and the display statuses of the display unit corresponding to the timing chart of  FIG. 23 ; 
         FIG. 26  is a diagram illustrating an exemplary manner in which pixel electrodes are divided into three pixel groups in the display unit of the display apparatus according to the fourth embodiment; 
         FIG. 27  is a timing chart illustrating display switching operations using three pixel groups that are performed by the display apparatus according to the fourth embodiment; 
         FIG. 28  is a diagram illustrating input signals input to scanning lines and signal lines of the display unit and the display statuses of the display unit corresponding to the timing chart of  FIG. 27 ; 
         FIG. 29  is a flowchart illustrating operations for changing the number of pixel groups in the display apparatus according to the fourth embodiment; 
         FIG. 30  is a flowchart illustrating operations after the number of pixel groups is changed in the display apparatus according to the fourth embodiment; 
         FIG. 31  is a timing chart illustrating display switching operations of a display apparatus according to a fifth embodiment of the present invention in a case where a ratio of the number of frames to be displayed by each pixel group to the total number of frames to be displayed by the display unit is set to 2/3; 
         FIG. 32  is a flowchart illustrating operations for changing the ratio in the display apparatus according to the fifth embodiment; 
         FIG. 33  is a flowchart illustrating operations of a display apparatus according to a sixth embodiment of the present invention in the case of receiving a display switching process end command signal; and 
         FIG. 34  is a graph illustrating display switching speeds realized by various display schemes according to the number of pixel groups and the ratio. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the following, preferred embodiments of the present invention are described with reference to the accompanying drawings. 
     According to one aspect of the present invention, pixel electrodes of a display apparatus are divided into plural pixel groups where a first pixel group performs display operations for displaying a given frame and a second pixel group starts display operations for displaying another frame before frame display operations by the first pixel group are completed. In this way, the frame display switching time may be reduced in the case of successively switching and displaying plural frames. According to another aspect of the present invention, the display switching speed may be adjusted by changing the number of pixel groups so that a desired frame may be promptly displayed. According to another aspect of the present invention, the display switching speed may be adjusted by changing the ratio of the number of frames to be displayed by each of the pixel groups with respect to the total number of frames to be displayed so that a desired frame may be promptly displayed. 
     First Embodiment 
       FIG. 6  is a block diagram showing a configuration of a display apparatus  400  according to a first embodiment of the present invention. 
     The illustrated display apparatus  400  includes a display unit  410  that uses electrophoretic elements and a drive unit  420  that drives the display unit  410 . The display apparatus  400  according to the present embodiment may be used for displaying plural pages of an electronic book, for example. The display apparatus  400  may successively switch the page being displayed on the display unit  410  as if to turn the pages of a book, for example. In the following descriptions, a still image that is displayed on the display unit  410  such as the image of a page of the electronic book as described above is referred to as a frame. 
     It is noted that component elements of the display unit  410  that are identical to those of the display unit  120  shown in  FIG. 1  are given the same reference numerals and their descriptions are omitted. 
     The drive unit  420  includes a controller  421 , a memory  422 , a scanning line driver  423 , a signal line driver  424 , and a setting unit  425 . 
     The controller  421  administers overall display control operations of the display unit  410 . The memory  422  may store information of plural frames to be displayed on the display unit  410 , display data for each pixel electrode forming the pattern of each frame, and identification information for identifying the frame currently being displayed on the display unit  410  of the plural frames, for example. 
     The scanning line driver  423  scans the scanning lines  106  based on a scanning command signal output from the controller  421 . The signal line driver  424  outputs display data to the pixel electrodes  102  connected to the TFT  105  that are turned on based on a display command signal output from the controller  421 . The setting unit  425  performs various setting operations within the display apparatus  400 . 
     In the following, operations of the display apparatus  400  are described. 
     When a display command is issued by a user at the display apparatus  400 , the controller  421  outputs a scanning command signal  421 A to the scanning line driver  423 . The scanning line driver  423  receives the scanning command signal  421 A and successively applies voltages to the scanning lines  106  to apply voltages to the TFTs  105  connected to the scanning lines  106 . 
     Also, the controller  421  outputs a display command signal  421 B to the signal line driver  423  and an addressing signal  421 C to the memory  422  in response to the user display command. Upon receiving the addressing signal  421 C, the memory  422  extracts display data  422 D for the pixels forming the patterns of the frames to be displayed based on the addressing signal  421 C, and outputs the extracted display data  422 D for the pixels to the signal line driver  423 . 
     The signal line driver  424  receives the display command signal  421 B from the controller  421  and applies voltages to the signal lines  107  to have the display data received from the memory  422  displayed by the pixel electrodes  102  connected to the TFTs  105  that are turned on. 
     In the following, display operations by the display unit  410  are described with reference to  FIG. 7 .  FIG. 7  is a diagram illustrating the display unit  410  of the display apparatus  400  according to the present embodiment. 
     The display unit  410  has pixel electrodes  102  that are divided into two groups, pixel group A and pixel group B, according to the scanning lines  106  to which they are connected. Specifically, in the present example, the scanning lines  106  of the display unit  410  are denoted as X 1 -X 6 , and the pixel electrodes connected to the odd-numbered scanning lines X 1 , X 3 , and X 5  belong to the pixel group A, whereas the pixel electrodes  102  connected to the even-numbered scanning lines X 2 , X 4 , and X 6  belong to the pixel group B. 
     By dividing the pixel electrodes  102  into those belonging to pixel group A and those belonging to pixel group B as is described above, and having the pixel groups display differing display data for representing patterns of differing frames, two different frames may be displayed by the display unit  410  at the same time. 
     It is noted that display control of the pixel groups may be performed by the controller  421  based on information set by the setting unit  425 , for example. 
     The setting unit  425  may set information specifying the pixel group that is to display a given frame of the plural frames stored in the memory  422 , for example. The controller  421  may control operations for outputting display data to be displayed by the pixel electrodes  102  of the pixel groups based on the information set by the setting unit  425 , for example. 
     In one specific example, the setting unit  425  may set information specifying that even-numbered frames of the plural frames stored in the memory  422  are to be displayed by the pixel group A and odd-numbered frames of the plural frames are to be displayed by the pixel group B. In this case, the controller  421  controls operations so that display data for representing an even-numbered frame are output to and displayed by the pixel electrodes  102  belonging to the pixel group A that are connected to the TFTs  105  turned on by the scanning operations of the scanning line driver  423 . Also, the controller  421  controls operations so that display data for representing an odd-numbered frame are output to and displayed by the pixel electrodes  102  belonging to the pixel group B that are connected to the TFTs  105  turned on by the scanning operations. 
     It is noted that in the above-illustrated example, the pixel electrodes  102  are divided into pixel groups according to their corresponding scanning lines  106 ; however, the manner in which the pixel electrodes  102  are divided is not limited to the above example. In alternative examples, the pixel electrodes  102  may be divided according to their corresponding signal lines  107 , or the pixel electrode  102  belonging to different pixel groups may be randomly divided and scattered across the display unit  410  regardless of their corresponding scanning lines  106  or signal lines  107 . In one embodiment, the manner in which the pixel electrodes  102  are divided may also be set by the setting unit  425 . 
     Also, in the display apparatus  400  according to the present embodiment, output timings for outputting display data to be displayed by the pixel electrodes  102  belonging to the different groups may be independently controlled so that the start timings of display operations for displaying two frames may be independently controlled. 
     For example, operations for displaying a given frame by the pixel group A (as a first pixel group) are started first after which operations for displaying another frame by the pixel group B (as a second pixel group) are started before the frame display operations of the pixel group A are completed. In this way, the display switching time required for completing frame display operations for displaying plural frames from the first frame to the last frame may be reduced in the case of successively switching and displaying the plural frames on the display unit  410 , for example. In the following descriptions, the process of successively switching and displaying plural frames on the display unit  410  from the first frame to the last frame is referred to as a successive display switching process. 
     The successive display switching process for displaying plural frames on the display unit  410  is described below with reference to  FIGS. 8-10 . 
       FIG. 8  is a diagram showing exemplary frame patterns to be displayed on the display unit  410 .  FIG. 9  is a timing chart illustrating a process of displaying the frame patterns using two pixel groups.  FIG. 10  is a diagram illustrating input signals input to the scanning lines and signal lines and the display statuses of the display unit  410  in accordance with the timing chart of  FIG. 9 . 
     It is noted that in  FIGS. 9 and 10 , the plural frames to be successively displayed are denoted as Fx where x is a number indicating the display order of the plural frames. 
     Also, it is noted that F 0  corresponds to an initial frame (first frame) to be displayed on the display unit  410  at an initial stage before the successive display switching process is started and F 7  corresponds to a target frame (last frame) that is to be displayed at the end of the successive display switching process. In the following descriptions, the frame to be displayed at the time the display switching process is ended (such as frame F 7  in the illustrated example) is referred to as a target frame. 
     Referring to  FIG. 9 , when the display apparatus  400  receives a display switching command at time point P 0 , display switching operations are started for switching the frame displayed on the display unit  410  from frame F 0  to frame F 1 . 
     In the present example, it is assumed that the initial frame F 0 , the target frame F 7 , and the even-numbered frames F 2 , F 4 , and F 6  are to be displayed by the pixel group A; and the initial frame F 0 , the target frame F 7 , and the odd-numbered frames F 1 , F 3 , and F 5  are to be displayed by the pixel group B. In the display unit  410 , the timings at which voltages are applied to the pixel electrodes  102  belonging to the pixel groups are varied based on the scanning timings. When the timings at which voltages are applied to the pixel electrodes  102  vary, the timings at which the white electrophoretic elements and the black electrophoretic elements start moving in the pixel electrodes may vary depending on each pixel electrode. Therefore, the timings at which moving operations of the white electrophoretic elements and the black electrophoretic elements are completed and the timings at which display data display operations are completed may vary depending on each pixel electrode. The display apparatus  400  according to the present invention uses such timing variations to have the pixel group A display a frame pattern and the pixel group B display another frame pattern at alternating timings so that the overall display switching time for displaying frames from frame F 0  to F 7  may be reduced, for example. 
     In  FIG. 9 , when the display apparatus  400  receives a display switching command at time point P 0 , display switching operations are started by scanning for a scanning time period  402  as is shown in  FIG. 10 . 
     In the following, the display status of the display unit  410  at time point P 0  is described. 
     At time point P 0 , the initial frame F 0  is displayed at the display unit  410 . Such a display status of the display unit  410  is denoted as S 0  in  FIG. 10 . The display unit  410  starts switching operations for switching the frame display from the initial frame F 0  to the next frame F 1 . In this case, since the next frame F 1  coming after the initial frame F 0  is to be displayed by the pixel group B, the only the frame displayed by the pixel group B is switched at time point P 0 . 
     Specifically, when display switching operations are started at time point P 0 , display data for forming the pattern of frame F 1  are input to the pixel electrodes  102  belonging to the pixel group B over the scanning time period  402  and display operations for displaying the pattern of frame F 1  are started by the pixel group B. It is noted that switching operations for switching the frame displayed by the pixel group A are not yet started during the scanning operations performed over the scanning time period  402 . Thus, display data for forming the pattern of the initial frame F 0  continues to be input to the pixel group A during the scanning time period  402 . 
     In the following, the display status of the display unit  410  at time point P 1  is described. 
     It is noted that the display status of the display unit  410  at time point P 1  is denoted as S 1  in  FIG. 10 . At time point P 1 , display switching operations for switching the frame display of the pixel group A from the pattern of frame F 0  to the pattern of frame F 2  are to be started. At this point the pattern of frame F 0  is still displayed by the pixel group A in a visually recognizable manner. Also, it is noted that the pixel group B is in the process of switching its frame display from the pattern of frame F 0  to the pattern of frame F 1  at time point P 1 . At this point, neither frame F 0  nor frame F 1  is displayed by the pixel group B in a visually recognizable manner. Thus, at time point P 1 , the pattern of frame F 0  is still displayed on the display unit  410  in a visually recognizable manner. 
     In the following, the display status of the display unit  410  at time point P 2  is described. 
     It is noted that the display status of the display unit  410  at time point P 2  is denoted as S 2  in  FIG. 10 . At time point P 2 , the pixel group A is in the process of switching its frame display from the pattern of frame F 0  to the pattern of frame F 2 , where neither of the frames is displayed in a visually recognizable manner. Also, at time point P 2 , the display switching operations for switching the frame display of the pixel group B from the pattern of frame F 0  to the pattern of frame F 1  are completed so that the pattern of frame F 1  is displayed in a visually recognizable manner by the pixel group B. 
     Thus, at time point P 2 , the pattern of frame F 1  is displayed on the display unit  410  in a visually recognizable manner. In other words, display switching operations for switching the frame display of the display unit  410  from the pattern of the initial frame F 0  to the pattern of the next frame F 1  are completed at time point P 2 . It is noted that the display switching time for switching the frame display from the pattern of frame F 0  to the pattern of frame F 1  is denoted as Ta in  FIG. 10 . Also, it is noted that at this point, a residual image resulting from the display switching operations of the pixel group A may be displayed in the background of the frame display of the pattern of frame F 1  displayed by the pixel group B of the display unit  410 . However, such a residual image may not constitute a substantial factor hampering the visibility of the display of frame F 1 . 
     In the following, the display status of the display unit  410  at time point P 3  is described. 
     It is noted that the display status of the display unit  410  at time point P 3  is denoted as S 3  in  FIG. 10 . At time point P 3 , the display switching operations started at time point P 1  for switching the frame display of the pixel group A from the pattern of frame F 0  to the pattern of frame F 2  are completed so that the pattern of frame F 2  is displayed by the pixel group A in a visually recognizable manner. Also, at time point P 3 , the pixel group B is in the process of switching its frame display from the pattern of frame F 1  to the pattern of frame F 3  which display switching operations are started at time point P 2 , and at this point, neither frame F 1  nor frame F 3  is displayed in a visually recognizable manner. 
     Thus, at time point P 3 , the pattern of frame F 2  is displayed on the display unit  410  in a visually recognizable manner. In other words, the display switching operations for switching the frame display of the display unit  410  from the pattern of frame F 1  to the pattern of frame F 2  are completed at time point P 3 . It is noted that the display switching time for switching the frame display from the pattern of frame F 1  to the pattern of frame F 2  is denoted as Tb in  FIG. 10 . 
     In the following, the display status of the display unit  410  at time point P 4  is described. 
     At time point P 4 , the pixel group A is in the process of switching its frame display from the pattern of frame F 2  to the pattern on frame F 4  which display switching operations are started at time point P 3 , and at this point neither the pattern of frame F 2  nor the pattern of frame F 4  is displayed in a visually recognizable manner. Also, at time point P 4 , the display switching operations of the pixel group B for switching the frame display from the pattern of frame F 1  to the pattern of frame F 3  are completed so that the pattern of frame F 3  is displayed in a visually recognizable manner. 
     Thus, at time point P 4 , the pattern of frame F 3  is displayed on the display unit  410  in a visually recognizable manner. In other words, the display switching operations of the display unit  410  for switching the frame display from the pattern of frame F 2  to the pattern of frame F 3  are completed at time point P 4 . 
     As can be appreciated from  FIG. 10 , the display switching time Tb is approximately half the length of the display switching time Ta. It is noted that the display switching time Ta is equal to a total of the scanning time and the pixel pattern switching time and corresponds to the display switching time of the display apparatus  100  according to the prior art. 
     In the display apparatus  400  according to the present embodiment, aside from the case of switching the frame display from the initial frame to the next frame, the display switching time for switching from one frame to another may be reduced to half the length of the display switching time of the display apparatus  100 . In this way, the overall display switching time required for successively switching and displaying plural pages to display a target frame in the display apparatus  400  may be substantially reduced compared to the display apparatus  100  of the prior art. 
     In the following, the process of successively switching the frame display from the initial frame to the target frame in the display apparatus  400  is described with reference to  FIG. 11 . 
       FIG. 11  is a flowchart illustrating a successive display switching process that is performed in the display apparatus  400  of the present embodiment. 
     According to  FIG. 11 , the controller  421  of the display apparatus  400  receives a frame display switching command (step S 901 ). In turn, the controller  421  identifies the initial frame that is displayed before successive display switching operations are started as frame N (step S 902 ). Specifically, the controller  421  reads identification information from the memory  422  for identifying the frame order of the frame being displayed before successive display switching operations are started. 
     Then, the controller  421  applies signals to the scanning lines  106  and the signal lines  107  to control the pixel group A to display the pattern of frame N, and the pixel group B to display the pattern of frame (N+1) (step S 903 ). Specifically, in a case where pixel electrodes  102  positioned on a given scanning line  106  that has its TFTs  105  turned on belongs to the pixel group A, display data signals for displaying frame N are applied to the signal lines  107 . On the other hand, in a case where pixel electrodes  102  positioned on a given scanning line  106  that has its TFTs  105  turned on belongs to the pixel group B, display data signals for displaying frame (N+1) are applied to the signal lines  107 . 
     Then, the controller  421  determines whether frame (N+1) corresponds to the target frame (step S 904 ). It is noted that a user may designate one of the plural frames to be displayed as the target frame beforehand via the setting unit  425 , for example. In another example, a user may designate the target frame while the successive display switching operations are being performed in which case the frame displayed at the time an interruption command signal for interrupting the display switching operations is input may be determined to be the target frame, for example. 
     If the frame (N+1) is determined to be the target frame in step S 904 , the controller  421  applies signals to the scanning lines  106  and the signal lines  107  to control both the pixel groups A and B to display the pattern of frame (N+1) (step S 905 ), and then ends the successive display switching process (step S 910 ). In one embodiment, upon ending the successive display switching process after the display unit  410  reaches the target frame, the control unit  421  may store information indicating the frame that has been determined as the target frame in the memory  422 , for example. 
     On the other hand, if it is determined that the frame (N+1) does not correspond to the target frame in step S 904 , the controller  421  applies signals to the scanning lines  106  and the signal lines  107  to control the pixel group A to display the pattern of frame (N+2) and the pixel group B to display the pattern of frame (N+1) (step S 906 ). 
     Then, the controller  421  determines whether the frame (N+2) corresponds to the target frame (step S 907 ). If it is determined in step S 907  that the frame (N+2) corresponds to the target frame, the controller  421  applies signals to the scanning lines  106  and the signal lines  107  to control both the pixel groups A and B to display the pattern of frame (N+2) (step S 908 ), and then ends the successive display switching process (step S 910 ). 
     On the other hand, if it is determined in step S 907  that the frame (N+2) does not correspond to the target frame, the controller  421  applies signals to the scanning lines  106  and the signal lines  107  to control the pixel groups A to display the pattern of frame (N+2) and the pixel group B to display the pattern of frame (N+3) (step S 909 ). 
     In the illustrated process of  FIG. 11 , steps S 903  through S 909  are repeated until the target frame is displayed on the display unit  410  of the display apparatus  400 . 
     Second Embodiment 
     In the following, a display apparatus according to a second embodiment of the present invention is described with reference to the accompanying drawings. It is noted that the display apparatus according to the second embodiment is substantially identical to the above-described display apparatus  400  according to the first embodiment other than the fact that the display apparatus according to the second embodiment has pixel electrodes divided into three different groups rather than two different groups. Thus, in the following descriptions, component elements of the display apparatus according to the second embodiment that are identical to those of the first embodiment are given the same reference numerals and their descriptions are omitted. It is noted that the number of pixel groups into which pixel electrodes are to be divided may be designated beforehand as is described below. 
       FIG. 10  is a diagram illustrating a display unit  410 A of the display apparatus according to the second embodiment. 
     In the illustrated display unit  410 A, the pixel electrodes  102  are divided into three pixel groups, pixel group A, pixel group B, and pixel group C, according to their corresponding scanning lines  106 . According to the present embodiment, provided that the scanning lines  106  of the display unit  410 A are denoted by Xn (where n is an integer indicating the order of the scanning line), the pixel electrodes  102  positioned on the scanning lines Xn of which n=1+3(k−1) (where k=1, 2, 3, . . . ) belong to the pixel group A. The pixel electrodes  102  positioned on the scanning lines Xn of which n=2+3(k−1) belong to the pixel group B. The pixel electrodes  102  positioned on the scanning lines Xn of which n=3+3(k−1) belong to the pixel group C. 
     It is noted that by dividing the pixel electrodes  102  of the display unit  410 A into pixel groups A, B, and C according to the scanning lines to which they are connected, and controlling the pixel electrodes  102  belonging to the different pixel groups to display differing display data for forming patterns of differing frames, three different frames may be displayed on the display unit  410 A at the same time. 
     In the following, frame display operations of the display unit  410 A are described with reference to  FIGS. 13 and 14 .  FIG. 13  is a timing chart illustrating successive frame display operations by the three pixel groups of the present embodiment.  FIG. 14  is a diagram illustrating input signals input to the scanning lines and the signal lines and the display statuses of the display unit according to the timing chart of  FIG. 13 . 
     In the following, the display status of the display unit  410 A at time point Q 0  is described. 
     At time point Q 0 , an initial frame F 0  is displayed by the display unit  410 A. The display unit  410 A starts display switching operations for switching the frame display from the initial frame F 0  to the next frame F 1 . In the present example, since the next frame F 1  coming after the initial frame F 0  is to be displayed by the pixel group B, only the pattern of the frame displayed by the pixel group B is switched at time point Q 0 . 
     When display switching operations of the pixel group B are started, display data for forming the pattern of frame F 1  are input to the pixel electrodes belonging to pixel group B during a scanning time period  602  as is shown in  FIG. 14 . In this way display operations for displaying the pattern of frame F 1  are started by the pixel electrodes of the pixel group B. It is noted that frame display switching operations for switching the frame display of the pixel groups A and C are not yet started during the scanning time period  602 . Thus, display data for forming the pattern of the initial frame F 0  continue to be input to the pixel electrodes belonging to pixel groups A and C in the scanning operations performed during the scanning time period  602 . 
     In the following, the display status of the display unit  410 A at time point Q 1  is described. 
     At time point Q 1 , the pixel group A is in the process of switching its frame display from the pattern of frame F 0  to the pattern of frame F 3 . Thus, at this point neither the pattern of frame F 0  nor the pattern of frame F 3  is displayed by the pixel group A in a visibly recognizable manner. It is noted that the pixel group C is also in the process of switching its frame display from the pattern of frame F 0  to the pattern of frame F 2  at time point Q 1 . Thus, neither the pattern of frame F 0  nor the pattern of frame F 2  is displayed by the pixel group C in a visibly recognizable manner. 
     On the other hand, at time point Q 1 , display switching operations for switching the frame display of the pixel group B from the pattern of frame F 0  to the pattern of frame F 1  are completed so that the pattern of frame F 1  is displayed by the pixel group B in a visibly recognizable manner. 
     Thus, at time point Q 1 , the pattern of frame F 1  is displayed on the display unit  410 A in a visibly recognizable manner. In other words, the display switching operations for switching the frame display of the display unit  410 A from the pattern of the initial frame F 0  to the pattern of the next frame F 1  are completed at time point Q 1 . It is noted that the display switching time for switching the frame display from the pattern of frame F 0  to the pattern of frame F 1  is denoted by T 2   a  in  FIG. 13 . Also, it is noted that a residual image resulting from the display switching operations of the pixel groups A and C may be displayed in the background of the frame display of frame F 1  that is displayed by the pixel group B of the display unit  410 A; however, such a residual image may not constitute a substantial factor hampering the visibility of the frame display of frame F 1 . 
     In the following, the display status of the display unit  410 A at time point Q 2  is described. 
     At time point Q 2 , the pixel group A is in the process of switching its frame display from the pattern of frame F 0  to the pattern of frame F 3 . Thus, neither frame F 0  nor frame F 3  is displayed by the pixel group A in a visibly recognizable manner. Also, at time point Q 2 , the pixel group B is in the process of switching its frame display from the pattern of frame F 1  to the pattern of frame F 4 . Thus, neither frame F 1  nor frame F 4  is displayed by the pixel group B in a visibly recognizable manner. 
     On the other hand, at time point Q 2 , display switching operations for switching the frame display of the pixel group C from the pattern of frame F 0  to the pattern of frame F 2  are completed so that the pattern of frame F 2  is displayed by the pixel group C in a visibly recognizable manner. 
     Thus, at time point Q 2 , the pattern of frame F 2  is displayed on the display unit  410 A in a visibly recognizable manner. In other words, display switching operations for switching the frame display of the display unit  410 A from the pattern of frame F 1  to the pattern of frame F 2  are completed at time point Q 2 . It is noted that the display switching time for switching the frame display from frame F 1  to frame F 2  is denoted by T 2   b  in  FIG. 13 . 
     In the following, the display status of the display unit  410 A at time point Q 3  is described. 
     At time point Q 3 , the pixel group B is in the process of switching its frame display from the pattern of frame F 1  to the pattern of frame F 4 . Thus, at this point, neither frame F 1  nor frame F 4  is displayed by the pixel group B in a visibly recognizable manner. Also, at time point Q 3 , the pixel group C is in the process of switching its frame display from the pattern of frame F 2  to the pattern of frame F 5 . Thus, at this point, neither frame F 2  nor frame F 5  is displayed by the pixel group C in a visibly recognizable manner. 
     On the other hand, at time point Q 3 , display switching operations for switching the frame display of the pixel group A from the pattern of frame F 0  to the pattern of frame F 3  are completed so that the pattern of frame F 3  is displayed by the pixel group A in a visibly recognizable manner. 
     Thus, at time point Q 3 , the pattern of frame F 3  is displayed on the display unit  410 A in a visibly recognizable manner. In other words, the display switching operations for switching the frame display of the display unit  410 A from the pattern of frame F 2  to the pattern of frame F 3  are completed at time point Q 3 . 
     In the present embodiment, the display switching time T 2   b  is approximately one third of the length of the display switching time T 2   a . The display switching time T 2   a  is equal to a total of the scanning time and the pixel pattern switching time and corresponds to the display switching time of the display apparatus  100  according to the prior art. 
     In the display apparatus according to the second embodiment, the display switching time for switching from one frame to another aside from the case of switching from the initial frame to the next frame may be reduced to approximately one third of the length of the display switching time of the display apparatus  100  according to the prior art. In this way, the overall display switching time for the display apparatus of the present embodiment to successively switch plural frames (pages) to display a target frame may be substantially reduced. 
     In the following, operations for successively switching and displaying plural frames from an initial frame to a target frame according to the second embodiment are described with reference to  FIGS. 15 and 16 .  FIG. 15  is a flowchart illustrating operations for determining the number of pixel groups into which pixel electrodes are to be divided. 
     According to  FIG. 15 , when the display apparatus according to the second embodiment receives a successive display switching process start command signal (step S 1301 ), the number of pixel groups into which the pixel electrodes of the display unit  410 A are to be divided may be selected (step S 1302 ). 
     For example, when the display apparatus according to the present embodiment receives a display switching process start command signal in step S 1301 , the controller  421  may display a display screen for enabling a user to select the number of pixel groups into which the pixel electrodes of the display unit  410 A are to be divided, and the user may select an arbitrary number via the display screen. In another example, plural ways of dividing the pixel electrodes of the display unit  410 A may be set by the setting unit  425  beforehand and the setting information may be stored in the memory  422 . In this case, the controller  421  may select the number of pixel groups based on the setting information before the display switching process start command signal is input to the display apparatus. It is noted that the display switching time may be reduced as the number of pixel groups is increased. 
     When the number of pixel groups into which the pixel electrodes are to be divided is selected in step S 1302 , the display apparatus starts a successive display switching process according to the selected number of pixel groups (step S 1303 ). Then, the display apparatus ends the successive display switching process upon reaching a target frame through successively switching and displaying plural frames (step S 1304 ). 
     In the following, the successive display switching process of step S 1303  is described in detail with reference to  FIG. 16 .  FIG. 16  is a flowchart illustrating the successive display switching process performed by the display apparatus according to the second embodiment. 
     According to  FIG. 16 , the controller  421  of the display apparatus according to the present embodiment starts the successive display switching process upon receiving a successive display switching process start command signal (step S 1401 ). In this case, the controller  421  identifies the initial frame that is displayed before the successive display switching process operations are performed as frame N (step S 1402 ). 
     The controller  421  applies signals to the scanning lines  106  and the signal lines  107  to control the pixel group A to display the pattern of frame N, the pixel group B to display the pattern of frame (N+1), and the pixel group C to display the pattern of frame (N−1) (step S 1403 ). Specifically, in a case where pixel electrodes  102  positioned on a given scanning line  106  that has its TFTs  105  turned on belongs to the pixel group A, display data signals for displaying frame N are applied to the signal lines  107 . In a case where pixel electrodes  102  positioned on a given scanning line  106  that has its TFTs  105  turned on belongs to the pixel group B, display data signals for displaying frame (N+1) are applied to the signal lines  107 . In a case where pixel electrodes  102  positioned on a given scanning line  106  that has its TFTs  105  turned on belongs to the pixel group C, display data signals for displaying frame (N−1) are applied to the signal lines  107 . 
     Then, the controller  421  determines whether the frame (N+1) corresponds to a target frame (step S 1404 ). It is noted that a user may designate one of the plural frames to be displayed as the target frame beforehand via the setting unit  425 , for example. In another example, a user may designate the target frame while the successive display switching operations are being performed in which case the frame displayed at the time an interruption command signal for interrupting the display switching operations is input may be determined to be the target frame, for example. 
     If the frame (N+1) is determined to be the target frame in step S 1404 , the controller  421  applies signals to the scanning lines  106  and the signal lines  107  to control the pixel groups A, B, and C to display the pattern of frame (N+1) (step S 1405 ). In turn, the frame (N+1) is displayed on the display unit  410 A, and the successive display switching process is ended (step S 1304 ). In one embodiment, upon ending the successive display switching process after the display unit  410 A reaches the target frame, the control unit  421  may store information indicating the frame that has been determined as the target frame in the memory  422 , for example. 
     On the other hand, if it is determined that the frame (N+1) does not correspond to the target frame in step S 1404 , the controller  421  applies signals to the scanning lines  106  and the signal lines  107  to control the pixel group A to display the pattern of frame N, the pixel group B to display the pattern of frame (N+1), and the pixel group C to display the pattern of frame (N+2) (step S 1406 ). 
     Then, the controller  421  determines whether the frame (N+2) corresponds to the target frame (step S 1407 ). If it is determined in step S 1407  that the frame (N+2) corresponds to the target frame, the controller  421  applies signals to the scanning lines  106  and the signal lines  107  to control the pixel groups A, B, and C to display the pattern of frame (N+2) (step S 1408 ). In turn, the frame (N+2) is displayed on the display unit  410 A, and the successive display switching process is ended (step S 1304 ). 
     On the other hand, if it is determined in step S 1407  that the frame (N+2) does not correspond to the target frame, the controller  421  applies signals to the scanning lines  106  and the signal lines  107  to control the pixel group A to display the pattern of frame (N+3), the pixel group B to display the pattern of frame (N+1), and the pixel group C to display the pattern of frame (N+2) (step S 1409 ). 
     Then, the controller  421  determines whether the frame (N+3) corresponds to the target frame (step S 1410 ). If it is determined in step S 1410  that the frame (N+3) corresponds to the target frame, the controller  421  applies signals to the scanning lines  106  and the signal lines  107  to control the pixel groups A, B, and C to display the pattern of frame (N+3) (step S 1411 ). In turn, the frame (N+3) is displayed on the display unit  410 A, and the successive display switching process is ended (step S 1304 ). 
     On the other hand, if it is determined in step S 1410  that the frame (N+3) does not correspond to the target frame, the controller  421  sets frame (N+3) as the initial frame (step S 1412 ) and the process goes back to step S 1403 . 
     In the illustrated process of  FIG. 16 , steps S 1403  through S 1412  are repeated until the target frame is displayed on the display unit  410 A. 
     Third Embodiment 
     In the following, a third embodiment of the present invention is described with reference to the accompanying drawings. It is noted that a display apparatus according to the third embodiment is identical in configuration to the display apparatus according to the second embodiment, and includes a display unit  410 A that divides pixel electrodes into three pixel groups. However, in the third embodiment, the ratio of the number of frames to be displayed by each of the pixel groups to the total number of frames to be displayed by the display unit differs from that of the second embodiment. It is noted that components of the display apparatus according to the third embodiment are given the same reference numerals as those of the display apparatus according to the second embodiment. 
     In the following, frame display operations of the display unit  410 A according to the third embodiment are described. 
       FIG. 17  is a timing chart illustrating a process of successively displaying frames using three pixel groups according to the third embodiment. 
     In the following, the display status of the display unit  410 A at time point R 0  is described. 
     At time point R 0  of  FIG. 17 , an initial frame F 0  is displayed by the display unit  410 A, and the display unit  410 A starts display switching operations for switching its frame display from the initial frame F 0  to a next frame F 1 . Since the next frame F 1  coming after the initial frame F 0  is to be displayed by the pixel group B, only the frame pattern to be displayed by the pixel group B is switched at time point R 0 . 
     In the following, the display status of the display unit  410 A at time point R 1  is described. 
     At time point R 1 , the pixel group A is in the process of switching its frame display from the pattern of frame F 0  to the pattern of frame F 2 . Thus, at this point neither frame F 0  nor frame F 2  is displayed by the pixel group A in a visibly recognizable manner. Also, at time point R 1 , the pixel group C is in the process of switching its frame display from the pattern of frame F 0  to the pattern of frame F 1 . 
     On the other hand, at time point R 1 , display switching operations for switching the frame display of the pixel group B from the pattern of frame F 0  to the pattern of frame F 1  are completed so that the pattern of frame F 1  is displayed by the pixel group B in a visibly recognizable manner. Thus, at time point R 1 , the pattern of frame F 1  is displayed on the display unit  410 A in a visibly recognizable manner. In other words, the display switching operations for switching the frame display of the display unit  410 A from the pattern of the initial frame F 0  to the pattern of the next frame F 1  are completed at time point R 1 . 
     According to the present embodiment, at time point R 1 , the pattern of frame F 1  is displayed by the pixel group B, and the pattern of frame F 1  is about to be displayed by the pixel group C. Thus, the number of pixel electrodes displaying the pattern of frame F 1  on the display unit  410 A at time point R 1  according to the present embodiment is greater than the number of pixel electrodes displaying the pattern of frame F 1  on the display unit  410 A at time point Q 1  according to the second embodiment where the three different pixel groups are each arranged to display differing frame patterns. 
     Accordingly, the visibility of the pattern of frame F 1  displayed by the display unit  410 A at time point R 1  according to the present embodiment may be improved with respect to the visibility of the pattern of frame F 1  displayed by the display unit  410 A at time point Q 1  according to the second embodiment. 
     It is noted that the display switching time for switching the frame display from the pattern of frame F 0  to the pattern of frame F 1  is denoted by T 3   a  in  FIG. 17 . Also, it is noted that a residual image resulting from the display switching operations of the pixel group A may be displayed in the background of the frame display of frame F 1  displayed by the pixel group B of the display unit  410 A; however, such a residual image may not constitute a substantial factor hampering the visibility of the frame display of frame F 1 . 
     In the following, the display status of the display unit  410 A at time point R 2  is described. 
     At time point R 2 , the pixel group B is in the process of switching its frame display from the pattern of frame F 1  to the pattern of frame F 2 . Thus, at this point, neither frame F 1  nor frame F 2  is displayed by the pixel group B in a visibly recognizable manner. Also, at time point R 2 , the pixel group C is in the process of switching its frame display from the pattern of frame F 1  to the pattern of frame F 3 . Thus, at this point neither frame F 1  nor frame F 3  is displayed by the pixel group C in a visibly recognizable manner. 
     On the other hand, at time point R 2 , display switching operations for switching the frame display of the pixel group A from the pattern of frame F 0  to the pattern of frame F 2  are completed so that the pattern of frame F 2  is displayed by the pixel group A in a visibly recognizable manner. 
     According to the present embodiment, at time point R 2 , the pattern of frame F 2  is displayed by the pixel group A, and the pattern of frame F 2  is about to be displayed by the pixel group B. Thus, as with the display status of the display unit  410 A at time point R 1 , the number of pixel electrodes displaying the pattern of frame F 2  on the display unit  410 A at time point R 2  according to the present embodiment is greater than the number of pixel electrodes displaying the pattern of frame F 2  on the display unit  410 A at time point Q 2  according to the second embodiment where the three different pixel groups are each arranged to display differing frame patterns. 
     Accordingly, the visibility of the pattern of frame F 2  displayed by the display unit  410 A at time point R 2  according to the present embodiment may be improved with respect to the visibility of the pattern of frame F 2  displayed by the display unit  410 A at time point Q 2  according to the second embodiment. It is noted that the display switching time for switching the frame display from the pattern of frame F 1  to the pattern of frame F 2  is denoted by T 3   b  in  FIG. 17 . 
     In the following, the display status of the display unit  410 A at time point R 3  is described. 
     At time point R 3 , the pixel group A is in the process of switching its frame display from the pattern of frame F 2  to the pattern of frame F 3 . Thus, at this point, neither frame F 2  nor frame F 3  is displayed by the pixel group A in a visibly recognizable manner. Also, at time point R 3 , the pixel group B is in the process of switching its frame display from the pattern of frame F 2  to the pattern of frame F 4 . Thus, at this point, neither frame F 2  nor frame F 4  is displayed by the pixel group B in a visibly recognizable manner. 
     On the other hand, at time point R 3 , display switching operations for switching the frame display of the pixel group C from the pattern of frame F 1  to the pattern of frame F 3  are completed so that the pattern of frame F 3  is displayed by the pixel group C in a visibly recognizable manner. 
     Thus, at time point R 3 , the pattern of frame F 3  is displayed by the pixel group C, and the pattern of frame F 3  is about to be displayed by the pixel group A. In other words, as with the display status of the display unit  410 A at time point R 1 , the number of pixel electrodes displaying the pattern of frame F 3  on the display unit  410 A at time point R 3  according to the present embodiment is greater than the number of pixel electrodes displaying the pattern of frame F 3  on the display unit  410 A at time point Q 3  according to the second embodiment in which the three different pixel groups are each arranged to display differing frame patterns. 
     Accordingly, the visibility of the pattern of frame F 3  displayed by the display unit  410 A at time point R 3  according to the present embodiment may be improved with respect to the visibility of the pattern of frame F 3  displayed by the display unit  410 A at time point Q 3  according to the second embodiment. It is noted that the display switching time for switching the frame display from the pattern of frame F 2  to the pattern of frame F 3  is also denoted by T 3   b  in  FIG. 17 . 
     In the present embodiment, the length of the display switching time T 3   b  is equal to approximately two thirds of the length of the display switching time T 3   a . The display switching time T 3   a  is equal to a total of the scanning time and the pixel pattern switching time and corresponds to the display switching time of the display apparatus  100  according to the prior art. 
     As can be appreciated from the above descriptions, in the present embodiment, the display switching time for switching from one frame to the next frame aside from the case of switching from the initial frame to the next frame may be reduced to approximately two thirds of the length of the display switching time of the display apparatus  100  according to the prior art. It is noted that although the display switching time in the present embodiment is longer than that of the second embodiment, visibility of the frame pattern being displayed by the display unit  410 A may be improved. 
     In the following, the ratio of the number of frames to be displayed by each of the pixel groups to the total number of frames to be displayed by the display unit is described. 
     In the first embodiment, the pixel electrodes  102  are divided into two pixel groups, and the pixel groups are each arranged to display differing frame patterns (e.g., the pixel groups A is arranged to display even-numbered frames and the pixel group B is arranged to display odd-numbered frames in the above illustrated example). Therefore, the ratio of the number of frames to be displayed by each of the pixel groups to the total number of frames to be displayed by the display unit is equal to ½. In the second embodiment, the pixel electrodes  102  are divided into three pixel groups, and the three pixel groups are each arranged to display differing frame patterns. Therefore, the ratio of the number of frames to be displayed by each of the pixel groups to the total number of frames to be displayed by the display unit is equal to ⅓. 
     In the third embodiment, the pixel electrodes  102  are divided into three pixel groups, and two of the three pixel groups are arranged to display the same frame at the same time. Therefore, the ratio of the number of frames to be displayed by each of the pixel groups to the total number of frames to be displayed by the display unit is equal to ⅔. It is noted that the visibility of the frame pattern being displayed may be improved as the value of this ratio is increased. 
     In the following, operations for successively switching and displaying plural frames from an initial frame to a target frame according to the third embodiment are described with reference to  FIGS. 18 and 19 .  FIG. 18  is a flowchart illustrating operations for determining the ratio of the number of frames to be displayed by each of the pixel groups to the total number of frames to be displayed by the display unit. 
     According to  FIG. 18 , when a successive display switching process start command signal is input to the display apparatus (step S 1601 ), the ratio of the number of frames to be displayed by each of the pixel groups to the total number of frames to be displayed by the display unit is selected (step S 1602 ). 
     For example, plural ratios may be stored in the memory  422  beforehand, and when a display switching process start command signal is input in step S 1601 , the controller  421  may display a display screen for enabling a user to select a preferred ratio, and the user may select an arbitrary number using the setting unit  425 . In another example, plural ratios may be stored in the memory  422 , and the controller  421  may be configured to select a suitable ratio. 
     When the ratio is selected in step S 1602 , the display apparatus starts a successive display switching process according to the selected ratio (step S 1603 ). Then, the display apparatus ends the successive display switching process upon reaching a target frame through successively switching and displaying plural frames (step S 1604 ). 
     In the following, the successive display switching process of step S 1603  is described in detail with reference to  FIG. 19 .  FIG. 19  is a flowchart illustrating the successive display switching process performed by the display apparatus according to the third embodiment. 
     According to  FIG. 19 , the controller  421  of the display apparatus according to the present embodiment starts the successive display switching process upon receiving a successive display switching process start command signal (step S 1701 ). In this case, the controller  421  identifies the initial frame that is displayed before the successive display switching process operations are performed as frame N (step S 1702 ). 
     Then, the controller  421  applies signals to the scanning lines  106  and the signal lines  107  to control the pixel group A to display the pattern of frame N, and the pixel groups B and C to display the pattern of frame (N+1) (step S 1703 ). Specifically, in a case where pixel electrodes  102  positioned on a given scanning line  106  that has its TFTs  105  turned on belongs to the pixel group A, display data signals for displaying frame N are applied to the signal lines  107 . In a case where pixel electrodes  102  positioned on a given scanning line  106  that has its TFTs  105  turned on belongs to the pixel group B or C, display data signals for displaying frame (N+1) are applied to the signal lines  107 . 
     Then, the controller  421  determines whether the frame (N+1) corresponds to a target frame (step S 1704 ). It is noted that a user may designate one of the plural frames to be displayed as the target frame beforehand via the setting unit  425 , for example. In another example, a user may designate the target frame while the successive display switching operations are being performed in which case the frame displayed at the time an interruption command signal for interrupting the display switching operations is input may be determined to be the target frame, for example. 
     If the frame (N+1) is determined to be the target frame in step S 1704 , the controller  421  applies signals to the scanning lines  106  and the signal lines  107  to control the pixel groups A, B, and C to display the pattern of frame (N+1) (step S 1705 ). In turn, the frame (N+1) is displayed on the display unit  410 A, and the successive display switching process is ended (step S 1604 ). In one embodiment, upon ending the successive display switching process after the display unit  410 A reaches the target frame, the control unit  421  may store information indicating the frame that has been determined as the target frame in the memory  422 , for example. 
     On the other hand, if it is determined that the frame (N+1) does not correspond to the target frame in step S 1704 , the controller  421  applies signals to the scanning lines  106  and the signal lines  107  to control the pixel groups A and B to display the pattern of frame (N+2) and the pixel group C to display the pattern of frame (N+1) (step S 1706 ). 
     Then, the controller  421  determines whether the frame (N+2) corresponds to the target frame (step S 1707 ). If it is determined in step S 1407  that the frame (N+2) corresponds to the target frame, the controller  421  applies signals to the scanning lines  106  and the signal lines  107  to control the pixel groups A, B, and C to display the pattern of frame (N+2) (step S 1708 ). In turn, the frame (N+2) is displayed on the display unit  410 A, and the successive display switching process is ended (step S 1604 ). 
     On the other hand, if it is determined in step S 1707  that the frame (N+2) does not correspond to the target frame, the controller  421  applies signals to the scanning lines  106  and the signal lines  107  to control the pixel groups A and C to display the pattern of frame (N+3) and the pixel group B to display the pattern of frame (N+2) (step S 1709 ). 
     Then, the controller  421  determines whether the frame (N+3) corresponds to the target frame (step S 1710 ). If it is determined in step S 1710  that the frame (N+3) corresponds to the target frame, the controller  421  applies signals to the scanning lines  106  and the signal lines  107  to control the pixel groups A, B, and C to display the pattern of frame (N+3) (step S 1711 ). In turn, the frame (N+3) is displayed on the display unit  410 A, and the successive display switching process is ended (step S 1604 ). 
     On the other hand, if it is determined in step S 1710  that the frame (N+3) does not correspond to the target frame, the controller  421  sets frame (N+3) as the initial frame (step S 1712 ) and the process goes back to steps S 1703 . 
     In the illustrated process of  FIG. 19 , steps S 1703  through S 1712  are repeated until the target frame is displayed on the display unit  410 A. 
     As can be appreciated from the above descriptions, according to the present embodiment, the display switching time may be reduced in the case of successively switching and displaying plural frames. 
     Fourth Embodiment 
     In the following a fourth embodiment of the present invention is described with reference to  FIG. 20 . 
       FIG. 20  is a block diagram showing a configuration of a display apparatus  400 B according to the fourth embodiment of the present invention. It is noted that components of the display apparatus  400 B that are identical to those of the display apparatus according to the first embodiment are given the same reference numerals. 
     The illustrated display apparatus  400  includes a display unit  410 B that uses electrophoretic elements and a drive unit  420 B that drives the display unit  410 B. The display apparatus  400 B according to the present embodiment may be used for displaying plural pages of an electronic book, for example. The display apparatus  400 B may successively switch a page being displayed on the display unit  410 B as if to turn the pages of a book, for example. 
     The drive unit  420 B includes a controller  421 , a memory  422 , a scanning line driver  423 , a signal line driver  424 , a setting unit  425 , and an operations unit  427 . 
     The controller  421  administers overall display control operations of the display unit  410 B. Also, the controller  421  includes a change unit  426  for changing the number of pixel groups into which pixel electrodes  102  of the display unit  410 B are divided. The memory  422  may store information of plural frames to be displayed on the display unit  410 , display data for each pixel electrode forming the pattern of each frame, and identification information for identifying the frame currently being displayed on the display unit  410  of the plural frames, for example. 
     The scanning line driver  423  scans the scanning lines  106  based on a scanning command signal output from the controller  421 . The signal line driver  424  outputs display data to the pixel electrodes  102  connected to the TFT  105  that are turned on based on a display command signal output from the controller  421 . The setting unit  425  performs various setting operations within the display apparatus  400 . Also, the display apparatus  400 B may be operated using the operations unit  427 . 
     In the following, operations of the display apparatus  400  are described. 
     When a user inputs a display command to the display apparatus  400 B via the operations unit  427 , the controller  421  outputs a scanning command signal  421 A to the scanning line driver  423 . The scanning line driver  423  receives the scanning command signal  421 A and successively applies voltages to the scanning lines  106  in order to apply voltages to the TFTs  105  connected to the scanning lines  106 . 
     Also, the controller  421  outputs a display command signal  421 B to the signal line driver  423  and an addressing signal  421 C to the memory  422  in response to the user display command. Upon receiving the addressing signal  421 C, the memory  422  extracts display data  422 D for the pixels forming the patterns of the frames to be displayed based on the addressing signal  421 C, and outputs the extracted display data  422 D for the pixels to the signal line driver  423 . 
     The signal line driver  424  receives the display command signal  421 B from the controller  421  and applies voltages to the signal lines  107  to have the display data received from the memory  422  displayed by the pixel electrodes  102  connected to the TFTs  105  that are turned on. 
     In the following, display operations by the display unit  410 B are described with reference to  FIG. 21 .  FIG. 21  is a diagram illustrating the display unit  410 B of the display apparatus  400 B according to the present embodiment. 
     The display unit  410 B has pixel electrodes  102  that are divided into two groups, pixel group A and pixel group B, according to the scanning lines  106  to which they are connected. Specifically, in the present example, the scanning lines  106  of the display unit  410 B are denoted as X 1 -X 6 , and the pixel electrodes  102  connected to the odd-numbered scanning lines X 1 , X 3 , and X 5  belong to the pixel group A, whereas the pixel electrodes  102  connected to the even-numbered scanning lines X 2 , X 4 , and X 6  belong to the pixel group B. 
     By dividing the pixel electrodes  102  into those belonging to pixel group A and those belonging to pixel group B as is described above, and having the pixel groups display differing display data for representing patterns of differing frames, two different frames may be displayed by the display unit  410 B at the same time. 
     It is noted that display control of the pixel groups may be performed by the controller  421  based on information set by the setting unit  425 , for example. 
     The setting unit  425  may set information specifying the pixel group that is to display a given frame of the plural frames stored in the memory  422 , for example. The controller  421  may control operations for outputting display data to be displayed by the pixel electrodes  102  of the pixel groups based on the information set by the setting unit  425 , for example. 
     In one specific example, the setting unit  425  may set information specifying that even-numbered frames of the plural frames stored in the memory  422  are to be displayed by the pixel group A and odd-numbered frames of the plural frames are to be displayed by the pixel group B. In this case, the controller  421  controls operations so that display data for representing an even-numbered frame are output to and displayed by the pixel electrodes  102  belonging to the pixel group A that are connected to the TFTs  105  turned on by the scanning operations of the scanning line driver  423 . Also, the controller  421  controls operations so that display data for representing an odd-numbered frame are output to and displayed by the pixel electrodes  102  belonging to the pixel group B that are connected to the TFTs  105  turned on by the scanning operations. 
     It is noted that in the above-illustrated example, the pixel electrodes  102  are divided into pixel groups according to their corresponding scanning lines  106 ; however, the manner in which the pixel electrodes  102  are divided is not limited to the above example. In alternative examples, the pixel electrodes  102  may be divided according to their corresponding signal lines  107 , or the pixel electrode  102  belonging to different pixel groups may be divided and scattered across the display unit  410  regardless of their corresponding scanning lines  106  or signal lines  107 . 
       FIGS. 22A and 22B  are diagrams illustrating other exemplary ways in which the pixel electrodes  102  may be divided into two pixel groups. In one example as is shown in  FIG. 22A , the pixel electrodes  102  of the display unit  410 B may be divided so that the pixel electrodes of pixel group A and the pixel electrodes of group B are arranged into a matrix structure. In another example as is shown in  FIG. 22B , the pixel electrodes  102  of the display unit  410 B may be divided so that pixel electrodes on the left side belong to the pixel group A and pixel electrodes on the right side belong to the pixel group B. It is noted that the manner in which the pixel electrodes  102  are divided may be set by the setting unit  425 , for example. 
     Also, in the display apparatus  400 B according to the present embodiment, output timings for outputting display data to be displayed by the pixel electrodes  102  belonging to the different groups may be independently controlled so that the start timings of display operations for displaying two frames may be independently controlled. 
     For example, operations for displaying a given frame by the pixel group A (as a first pixel group) may be started first after which operations for displaying another frame by the pixel group B (as a second pixel group) may be started before the frame display operations of the pixel group A are completed. In this way, the display switching time required for completing frame display operations for displaying plural frames from the first frame to the last frame may be reduced in the case of successively switching and displaying the plural frames on the display unit  410 B. 
     In the following, the successive display switching process for displaying plural frames on the display unit  410 B is described with reference to  FIGS. 23-25 . 
       FIG. 23  is a diagram showing exemplary frame patterns to be displayed on the display unit  410 B.  FIG. 24  is a timing chart illustrating a process of displaying the frame patterns using two pixel groups.  FIG. 25  is a diagram illustrating input signals input to the scanning lines and signal lines and the display statuses of the display unit  410 B in accordance with the timing chart of  FIG. 24 . 
     It is noted that in  FIGS. 24 and 25 , the plural frames to be successively displayed are denoted as Fx where x is a number indicating the order of the plural frames. 
     Also, it is noted that frame F 0  corresponds to an initial frame (first frame) to be displayed on the display unit  410 B at an initial stage before the successive display switching process is started and frame F 7  corresponds to a target frame (last frame) that is to be displayed at the end of the successive display switching process. 
     Referring to  FIG. 24 , when the display apparatus  400 B receives a display switching command at time point P 0 , display switching operations are started for switching the frame displayed on the display unit  410 B from frame F 0  to frame F 1 . 
     In this case, it is assumed that the initial frame F 0 , the target frame F 7 , and the even-numbered frames F 2 , F 4 , and F 6  are to be displayed by the pixel group A; and the initial frame F 0 , the target frame F 7 , and the odd-numbered frames F 1 , F 3 , and F 5  are to be displayed by the pixel group B. In the display unit  410 B, the timings at which voltages are applied to the pixel electrodes  102  belonging to the pixel groups are varied based on the scanning timings of the scanning lines  106 . When the timings at which voltages are applied to the pixel electrodes  102  vary, the timings at which the white electrophoretic elements and the black electrophoretic elements start moving within the pixel electrodes may vary depending on each pixel electrode. Therefore, the timings at which moving operations of the white electrophoretic elements and the black electrophoretic elements are completed and the timings at which display data display operations are completed may vary depending on each pixel electrode. The display apparatus  400 B according to the present embodiment may use such timing variations to have the pixel group A display a frame pattern and the pixel group B display another frame pattern at alternating timings so that the overall display switching time for displaying frames from frame F 0  to F 7  may be reduced, for example. 
     As can be appreciated from  FIG. 24 , when the display apparatus  400 B receives a display switching command at time point P 0 , display switching operations are started by performing scanning operations for a scanning time period  402  as is shown in  FIG. 25 . 
     In the following, the display status of the display unit  410 B at time point P 0  is described. 
     At time point P 0 , the initial frame F 0  is displayed at the display unit  410 B. Such a display status of the display unit  410  is denoted as S 0  in  FIG. 25 . The display unit  410 B starts switching operations for switching the frame display from the initial frame F 0  to the next frame F 1 . In this case, since the next frame F 1  coming after the initial frame F 0  is to be displayed by the pixel group B, only the frame displayed by the pixel group B is switched at time point P 0 . 
     Specifically, when display switching operations are started at time point P 0 , display data for forming the pattern of frame F 1  are input to the pixel electrodes  102  belonging to the pixel group B over the scanning time period  402  and display operations for displaying the pattern of frame F 1  are started by the pixel group B. It is noted that switching operations for switching the frame displayed by the pixel group A are not yet started during the scanning operations performed over the scanning time period  402 . Thus, display data for forming the pattern of the initial frame F 0  continues to be input to the pixel group A during the scanning time period  402 . 
     In the following, the display status of the display unit  410 B at time point P 1  is described. 
     It is noted that the display status of the display unit  410 B at time point P 1  is denoted as S 1  in  FIG. 25 . At time point P 1 , display switching operations for switching the frame display of the pixel group A from the pattern of frame F 0  to the pattern of frame F 2  are started, and at this point, the pattern of F 0  is still displayed by the pixel group A in visually recognizable manner. Also, at time point P 1 , the pixel group B is in the process of switching its frame display from the pattern of frame F 0  to the pattern of frame F 1 , and at this point neither frame F 0  nor frame F 1  is displayed by the pixel group B in a visually recognizable manner. Thus, at time point P 1 , the pattern of frame F 0  is displayed on the display unit  410 B in a visually recognizable manner. 
     In the following, the display status of the display unit  410 B at time point P 2  is described. 
     It is noted that the display status of the display unit  410 B at time point P 2  is denoted as S 2  in  FIG. 25 . At time point P 2 , the pixel group A is in the process of switching its frame display from the pattern of frame F 0  to the pattern of frame F 2 , and neither of the frames is displayed in a visually recognizable manner. Also, at time point P 2 , the display switching operations for switching the frame display of the pixel group B from the pattern of frame F 0  to the pattern of frame F 1  are completed so that the pattern of frame F 1  is displayed in a visually recognizable manner by the pixel group B. 
     Thus, at time point P 2 , the pattern of frame F 1  is displayed on the display unit  410 B in a visually recognizable manner. In other words, display switching operations for switching the frame display of the display unit  410 B from the pattern of the initial frame F 0  to the pattern of the next frame F 1  are completed at time point P 2 . It is noted that the display switching time for switching the frame display from the pattern of frame F 0  to the pattern of frame F 1  is denoted as Ta in  FIG. 25 . Also, it is noted that at this point, a residual image resulting from the display switching operations of the pixel group A may be displayed in the background of the frame display of the pattern of frame F 1  displayed by the pixel group B of the display unit  410 B. However, such a residual image may not constitute a substantial factor hampering the visibility of the display of frame F 1 . 
     In the following, the display status of the display unit  410 B at time point P 3  is described. 
     It is noted that the display status of the display unit  410 B at time point P 3  is denoted as S 3  in  FIG. 25 . At time point P 3 , the display switching operations started at time point P 1  for switching the frame display of the pixel group A from the pattern of frame F 0  to the pattern of frame F 2  are completed so that the pattern of frame F 2  is displayed by the pixel group A in a visually recognizable manner. Also, at time point P 3 , the pixel group B is in the process of switching its frame display from the pattern of frame F 1  to the pattern of frame F 3  which display switching operations are started at time point P 2 , and at this point, neither frame F 1  nor frame F 3  is displayed in a visually recognizable manner. 
     Thus, at time point P 3 , the pattern of frame F 2  is displayed on the display unit  410 B in a visually recognizable manner. In other words, the display switching operations for switching the frame display of the display unit  410 B from the pattern of frame F 1  to the pattern of frame F 2  are completed at time point P 3 . It is noted that the display switching time for switching the frame display from the pattern of frame F 1  to the pattern of frame F 2  is denoted as Tb in  FIG. 25 . 
     In the following, the display status of the display unit  410 B at time point P 4  is described. 
     At time point P 4 , the pixel group A is in the process of switching its frame display from the pattern of frame F 2  to the pattern on frame F 4  which display switching operations are started at time point P 3 , and at this point, neither frame F 2  nor frame F 4  is displayed in a visually recognizable manner. Also, at time point P 4 , the display switching operations of the pixel group B for switching the frame display from the pattern of frame F 1  to the pattern of frame F 3  are completed so that the pattern of frame F 3  is displayed by the pixel group B in a visually recognizable manner. 
     Thus, at time point P 4 , the pattern of frame F 3  is displayed on the display unit  410 B in a visually recognizable manner. In other words, the display switching operations of the display unit  410 B for switching the frame display from the pattern of frame F 2  to the pattern of frame F 3  are completed at time point P 4 . 
     As can be appreciated from  FIG. 25 , the display switching time Tb is approximately half the length of the display switching time Ta. It is noted that the display switching time Ta is equal to a total of the scanning time and the pixel pattern switching time and corresponds to the display switching time of the display apparatus  100  according to the prior art. 
     In the display apparatus  400 B according to the present embodiment, aside from the case of switching the frame display from the initial frame to the next frame, the display switching time for switching from one frame to the next frame may be reduced to half the length of the display switching time of the display apparatus  100 . In this way, the overall display switching time required for successively switching and displaying plural pages to display a target frame in the display apparatus  400 B may be substantially reduced compared to the display apparatus  100  of the prior art. 
     Further, in the display apparatus  400 B according to the present embodiment, the successive display switching time may be adjusted to enable display of the target frame in a shorter period of time. In the following, adjustment of the successive display switching time for successively switching and displaying plural frames in the display apparatus  400 B according to the present embodiment is described. 
     The frame display switching time of the display apparatus  400 B according to the present embodiment depends on the number of pixel groups. In the following, an exemplary case where the pixel electrodes  102  of the display apparatus  400 B are divided into three groups is described.  FIG. 26  shows an example in which the pixel electrodes  102  of the display unit  410 B are divided into pixel group A, pixel group B, and pixel group C. 
     In the following, frame display operations of the display unit  410 B when its pixel electrodes  102  are divided into three groups are described with reference to  FIGS. 27 and 28 .  FIG. 27  is a timing chart illustrating successive frame display operations of the display apparatus  400 B using the three pixel groups.  FIG. 28  is a diagram illustrating input signals input to the scanning lines  106  and the signal lines  107  and the display statuses of the display unit  410 B according to the timing chart of  FIG. 13 . 
     In the following, the display status of the display unit  410 B at time point Q 0  is described. 
     At time point Q 0 , the initial frame F 0  is displayed by the display unit  410 B, and the display unit  410 B starts display switching operations for switching the frame display from the initial frame F 0  to the next frame F 1 . In the present example, since the next frame F 1  coming after the initial frame F 0  is to be displayed by the pixel group B, only the pattern of the frame displayed by the pixel group B is switched at time point Q 0 . 
     When display switching operations of the pixel group B are started, display data for forming the pattern of frame F 1  are input to the pixel electrodes belonging to pixel group B during a scanning time period  602  as is shown in  FIG. 28 . In this way, display operations for displaying the pattern of frame F 1  are started by the pixel electrodes of the pixel group B. It is noted that frame display switching operations for switching the frame display of the pixel groups A and C are not yet started during the scanning time period  602 . Thus, display data for forming the pattern of the initial frame F 0  continue to be input to the pixel electrodes belonging to pixel groups A and C in the scanning operations performed during the scanning time period  602 . 
     In the following, the display status of the display unit  410 B at time point Q 1  is described. 
     At time point Q 1 , the pixel group A is in the process of switching its frame display from the pattern of frame F 0  to the pattern of frame F 3 . Thus, at this point, neither frame F 0  nor frame F 3  is displayed by the pixel group A in a visibly recognizable manner. Also, at time point Q 1 , the pixel group C is in the process of switching its frame display from the pattern of frame F 0  to the pattern of frame F 2 . Thus, neither frame F 0  nor frame F 2  is displayed by the pixel group C in a visibly recognizable manner. 
     On the other hand, at time point Q 1 , display switching operations for switching the frame display of the pixel group B from the pattern of frame F 0  to the pattern of frame F 1  are completed so that the pattern of frame F 1  is displayed by the pixel group B in a visibly recognizable manner. 
     Thus, at time point Q 1 , the pattern of frame F 1  is displayed on the display unit  410 B in a visibly recognizable manner. In other words, the display switching operations for switching the frame display of the display unit  410 A from the pattern of the initial frame F 0  to the pattern of the next frame F 1  are completed at time point Q 1 . It is noted that the display switching time for switching the frame display from the pattern of frame F 0  to the pattern of frame F 1  is denoted by T 2   a  in  FIG. 27 . Also, it is noted that a residual image resulting from the display switching operations of the pixel groups A and C may be displayed in the background of the frame display of frame F 1  that is displayed by the pixel group B of the display unit  410 B; however, such a residual image may not constitute a substantial factor hampering the visibility of the frame display of frame F 1 . 
     In the following, the display status of the display unit  410 B at time point Q 2  is described. 
     At time point Q 2 , the pixel group A is in the process of switching its frame display from the pattern of frame F 0  to the pattern of frame F 3 . Thus, at this point, neither frame F 0  nor frame F 3  is displayed by the pixel group A in a visibly recognizable manner. Also, at time point Q 2 , the pixel group B is in the process of switching its frame display from the pattern of frame F 1  to the pattern of frame F 4 . Thus, at this point, neither frame F 1  nor frame F 4  is displayed by the pixel group B in a visibly recognizable manner. 
     On the other hand, at time point Q 2 , display switching operations for switching the frame display of the pixel group C from the pattern of frame F 0  to the pattern of frame F 2  are completed so that the pattern of frame F 2  is displayed by the pixel group C in a visibly recognizable manner. 
     Thus, at time point Q 2 , the pattern of frame F 2  is displayed on the display unit  410 B in a visibly recognizable manner. In other words, display switching operations for switching the frame display of the display unit  410 B from the pattern of frame F 1  to the pattern of frame F 2  are completed at time point Q 2 . It is noted that the display switching time for switching the frame display from frame F 1  to frame F 2  is denoted by T 2   b  in  FIG. 27 . 
     In the following, the display status of the display unit  410 B at time point Q 3  is described. 
     At time point Q 3 , the pixel group B is in the process of switching its frame display from the pattern of frame F 1  to the pattern of frame F 4 . Thus, at this point, neither frame F 1  nor frame F 4  is displayed by the pixel group B in a visibly recognizable manner. Also, at time point Q 3 , the pixel group C is in the process of switching its frame display from the pattern of frame F 2  to the pattern of frame F 5 . Thus, at this point, neither frame F 2  nor frame F 5  is displayed by the pixel group C in a visibly recognizable manner. 
     On the other hand, at time point Q 3 , display switching operations for switching the frame display of the pixel group A from the pattern of frame F 0  to the pattern of frame F 3  are completed so that the pattern of frame F 3  is displayed by the pixel group A in a visibly recognizable manner. 
     Thus, at time point Q 3 , the pattern of frame F 3  is displayed on the display unit  410 B in a visibly recognizable manner. In other words, the display switching operations for switching the frame display of the display unit  410 B from the pattern of frame F 2  to the pattern of frame F 3  are completed at time point Q 3 . 
     In the present example, the display switching time T 2   b  is approximately one third of the length of the display switching time T 2   a . The display switching time T 2   a  is equal to a total of the scanning time and the pixel pattern switching time and corresponds to the display switching time of the display apparatus  100  according to the prior art. 
     In the display apparatus  400 B according to the present embodiment, by dividing the pixel electrodes  102  into three pixel groups, the display switching time for switching from one frame to the next frame, aside from the case of switching the frame display from the initial frame to the next frame, may be reduced to approximately one third of the length of the display switching time of the display apparatus  100  according to the prior art. 
     As can be appreciated from the above descriptions, by increasing the number of pixel groups from two to three in the display apparatus  400 B according to the present embodiment, the frame display switching time may be reduced further with respect to the display switching time of the display apparatus  100  according to the prior art. In other words, the frame display switching time of the display apparatus  400 B according the present embodiment may be adjusted by changing the number of pixel groups into which the pixel electrodes  102  are to be divided. For example, the number of pixel groups may be increased in order to increase the display switching speed and reduce the display switching time of the display apparatus  400 B in the case where the process time of a successive display switching process performed in the display apparatus  400 B is relatively long. 
     It is noted that the successive display switching process of the display apparatus  400 B may continue for a relatively long period of time when a large number of pages have to be turned (i.e., when a large number of frames have to be switched) before a desired page for a user (i.e., target frame) is displayed on the display unit  410 B. Accordingly, in the present embodiment, the display switching speed of the display apparatus  400 B is automatically increased to reduce the display switching time in the case where the successive display switching process continues for more than a predetermined time period. In this way, the desired page for the user may be speedily searched and displayed on the display unit  410 B. 
     Specifically, in the display apparatus  400 B according to the present embodiment, a predetermined time period that is to elapse from the start time of a successive display switching process before the number of pixel groups is to be changed is stored beforehand. It is noted that the predetermined time may be stored in the memory  422  or some other storage unit (not shown) included in the display apparatus  400 B. Also, in the display apparatus  400 B of the present embodiment, the controller  421  is configured to keep track of the time elapsed from the start of the successive display switching process using a clock function of the display apparatus  400 B. The controller  421  changes the number of pixel groups using the change unit  426  when it does not receive a successive display switching process stop command even after the predetermined time period elapses from the time the successive display switching process is started. 
     In the following, the change unit  426  is described. The change unit  426  is included in the control unit  421  and realizes the function of changing the number of pixel groups. Specifically, the change unit  426  changes the number of pixel groups from a value currently set to the display unit  410 B to a stored value set by the setting unit  425  as the number of pixel groups to be set to the display unit  410 B after the current value expires. When the number of pixels is changed by the change unit  426 , the controller  421  performs relevant control operations with respect to relevant component units of the display apparatus  400 B to change the number of pixel groups. It is noted that the number of pixel groups set by the setting unit  425  as the number of pixel groups into which the current number is to be changed may be stored in the memory  422  or some other storage unit (not shown) included in the display apparatus  400 B, for example. 
     In the following, operations for changing the number of pixel groups to be used in the display unit  410 B of the display apparatus according to the present embodiment are described with reference to  FIG. 29 .  FIG. 29  is a flowchart illustrating operations for changing the number of pixel groups used in the display unit  410  of the display apparatus  400 B. In the illustrated example of  FIG. 29 , it is assumed that the value “2” is initially set to the display unit  410 B as the number of pixel groups to be used. 
     According to  FIG. 29 , the display apparatus  400 B starts a successive display switching process in response to a successive display switching process start command input by a user via the operations unit  427  (step S 2501 ). At this point, the control unit  421  identifies the initial frame displayed on the display unit  410 B (i.e., frame displayed before the frame display is switched) as frame N (step S 2502 ), and reads information on this frame N from the memory  422 . For example, the frame information read from the memory  422  may be identification information indicating the order of frame N within the frames stored in the memory  422 . 
     Then, the controller  421  reads and sets time information to be used for determining whether the number of pixel groups should be changed (step S 2503 ). In one example, the time information may correspond to a change reference time that is set by the setting unit  425  and stored in a storage unit (not shown) of the display apparatus  400 B to be used as a reference for determining whether the controller  421  should change the number of pixel groups. In another example, the time information may be input by the user via the operations unit  427  each time a successive display switching process is started. Then, the controller  421  sets the number of pixel groups to “2” corresponding to the initial number of pixel groups and starts frame switching operations of the successive display switching process (step S 2504 ). In the following descriptions, the two pixel groups are referred to as pixel group A and pixel group B. 
     The controller  421  applies signals to the scanning lines  106  and the signal lines  107  to control the pixel group A to display the pattern of frame N and the pixel group B to display the pattern of frame (N+1) (step S 2505 ). Specifically, in a case where pixel electrodes  102  positioned on a given scanning line  106  that has its TFTs  105  turned on belongs to the pixel group A, display data signals for displaying frame N are applied to the signal lines  107 . In a case where pixel electrodes  102  positioned on a given scanning line  106  that has its TFTs  105  turned on belongs to the pixel group B, display data signals for displaying frame (N+1) are applied to the signal lines  107 . 
     Then, the controller  421  determines whether the frame (N+1) corresponds to a target frame (step S 2506 ). In the present embodiment, the controller  421  determines the target frame by determining the frame that is displayed at the time a successive display switching process execution command signal stops being input. It is noted that such determination operations are performed from the time first scanning operations are ended to the time second scanning operations are started. 
     If the frame (N+1) is determined to be the target frame in step S 2506 , the controller  421  applies signals to the scanning lines  106  and the signal lines  107  to control the pixel groups A and B to display the pattern of frame (N+1) (step S 2507 ). Then, the controller  421  ends the successive display switching process (step  2508 ). 
     On the other hand, if it is determined in step S 2506  that the frame (N+1) does not correspond to the target frame, the controller  421  compares the time elapsed from when the successive display switching process is started to the time the determination step  2506  is performed (i.e., time duration of the successive display switching process) with the change reference time set in step S 2503  (step S 2509 ). Upon determining that the time duration of the successive display switching process is longer than the reference time, the controller  421  resets the initial frame N to N=N+1 (step S 2510 ) and controls the change unit  426  to change the number of pixel groups (step S 2511 ). In the present example, it is assumed that the number of pixel groups is changed from “2” to “3” as is described in detail below. 
     Upon determining in step S 2509  that the time duration of the successive display switching process is shorter than the change reference time, the controller  421  applies signals to the scanning lines  106  and the signal lines  107  to control the pixel group A to display the pattern of frame (N+2) and the pixel group B to display the pattern of frame (N+1) (step S 2512 ). 
     Then, the controller  421  determines whether the frame (N+2) corresponds to the target frame (step S 2513 ). If it is determined in step S 2513  that the frame (N+2) corresponds to the target frame, the controller  421  applies signals to the scanning lines  106  and the signal lines  107  to control the pixel groups A and B to display the pattern of frame (N+2) (step S 2514 ), and ends the successive display switching process (step S 2508 ). 
     If it is determined in step S 2513  that the frame (N+2) does not correspond to the target frame, the controller  421  compares the time elapsed from when the successive display switching process is started to the time the determination step  2512  is performed (i.e., time duration of the successive display switching process) with the change reference time set in step S 2503  (step S 2515 ). 
     When the duration time of the successive display switching process is longer than the change reference time, the controller  421  resets the initial frame N to N=N+2 (step S 2516 ) and changes the number of pixel groups using the change unit  426  (step S 2511 ). 
     Also, when it is determined in step S 2515  that the duration time of the successive display switching process is shorter than the change reference time, the controller  421  resets the initial frame N to N=N+2 (step S 2517 ) and goes back to step S 2505  to apply signals to the scanning lines  106  and the signal lines  107  to control the pixel group A to display the pattern of frame (N=N+2), and the pixel group B to display the pattern of frame (N+1=N+3). It is noted that the controller  421  repeats the process steps of S 2505 -S 2517  until it is determined that the target frame has been reached or the duration time of the successive display switching process is longer than the change reference time. 
     In the following, operations of the display apparatus  400 B when the number of pixel groups is changed to “3” are described with reference to  FIG. 30 .  FIG. 30  is a flowchart illustrating operations of the display apparatus  400 B after the number of pixel groups is changed from “2” to “3”. In the illustrated example of  FIG. 30 , the three pixel groups are denoted as pixel group C, pixel group D, and pixel group E. 
     When the number of pixel groups is changed to “3” in the display apparatus  400 B (S 2601 ), the controller  421  applies signals to the scanning lines  106  and the signal lines  107  to control the pixel group C to display the pattern of frame N, the pixel group D to display the pattern of frame (N+1), and the pixel group E to display the pattern of frame (N−1) (step S 2602 ). Specifically, in a case where pixel electrodes  102  positioned on a given scanning line  106  that has its TFTs  105  turned on belongs to the pixel group C, display data signals for displaying frame N are applied to the signal lines  107 . In a case where pixel electrodes  102  positioned on a given scanning line  106  that has its TFTs  105  turned on belongs to the pixel group D, display data signals for displaying frame (N+1) are applied to the signal lines  107 . In a case where pixel electrodes  102  positioned on a given scanning line  106  that has its TFTs  105  turned on belongs to the pixel group E, display data signals for displaying frame (N+2) are applied to the signal lines  107 . 
     Then, the controller  421  determines whether the frame (N+1) corresponds to a target frame (step S 2603 ). If the frame (N+1) is determined to be the target frame in step S 2603 , the controller  421  applies signals to the scanning lines  106  and the signal lines  107  to control the pixel groups C, D, and E to display the pattern of frame (N+1) (step S 2604 ). Then, the controller  421  displays the frame (N+1) on the display unit  410 B, and ends the successive display switching process (step S 2605 ). 
     If it is determined in step S 2603  that the frame (N+1) does not correspond to the target frame, the controller  421  applies signals to the scanning lines  106  and the signal lines  107  to control the pixel group C to display the pattern of frame N, the pixel group D to display the pattern of frame (N+1), and the pixel group E to display the pattern of frame (N+2) (step S 2606 ). 
     Then, the controller  421  determines whether the frame (N+2) corresponds to the target frame (step S 2607 ). If it is determined in step S 2607  that the frame (N+2) corresponds to the target frame, the controller  421  applies signals to the scanning lines  106  and the signal lines  107  to control the pixel groups C, D, and E to display the pattern of frame (N+2) (step S 2608 ). Then, the controller  421  controls the display unit  410 B to display the pattern of frame (N+2) and ends the successive display switching process (step S 2605 ). 
     If it is determined in step S 2607  that the frame (N+2) does not correspond to the target frame, the controller  421  applies signals to the scanning lines  106  and the signal lines  107  to control the pixel group C to display the pattern of frame (N+3), the pixel group D to display the pattern of frame (N+1), and the pixel group E to display the pattern of frame (N+2) (step S 2609 ). 
     Then, the controller  421  determines whether the frame (N+3) corresponds to the target frame (step S 2610 ). If it is determined in step S 2610  that the frame (N+3) corresponds to the target frame, the controller  421  applies signals to the scanning lines  106  and the signal lines  107  to control the pixel groups C, D, and E to display the pattern of frame (N+3) (step S 2608 ). Then, the controller  421  controls the display unit  410 B to display the pattern of frame (N+3) and ends the successive display switching process (step S 2605 ). 
     If it is determined in step S 2610  that the frame (N+3) does not correspond to the target frame, the controller  421  applies signals to the scanning lines  106  and the signal lines  107  to control the pixel group C to display the pattern of frame (N+3), the pixel group D to display the pattern of frame (N+4), and the pixel group E to display the pattern of frame (N+2) (step S 2612 ). 
     It is noted that the controller  421  repeats the process steps of S 2602 -S 2612  until the target frame is displayed on the display unit  410 B. 
     As can be appreciated from the above descriptions, in the display apparatus  400 B according to the present embodiment, the number of pixel groups is changed after a predetermined time period (i.e., change reference time) elapses from the time a successive display switching process is started. In one example, the number of pixel groups may be increased in order to increase the frame display switching speed of the display unit  410 B. In this way, the number of pixel groups used in the display apparatus  400 B may be changed to reduce the time it takes to have a desired frame (page) displayed on the display unit  410 B so that the desired frame (target frame) may be promptly displayed. 
     In another example, the number of pixel groups used in the display apparatus  400 B may be decreased in order to decrease the frame display switching speed of the display unit  410 B. In this way, the number of pixel groups may be changed to adjust the frame display switching speed of the display unit  410 B according to usage preferences of a user so that operability of the display apparatus  400 B may be improved. 
     It is noted that in the above-described embodiment, predetermined time information is set as a reference for determining whether to change the number of pixel groups in step S 2503 . However, the present invention is not limited to such an example, and in another example, a predetermined number of frames may be used as the reference for determining whether to change the number of pixel groups. In this case, the display apparatus  400 B preferably has a counter function for counting the number of frames displayed by the display unit  410 B. In one example, such a counter function may be realized by the controller  421 . 
     In the following, an example is described in which a predetermined number of frames is used as a reference for determining whether to change the number of pixel groups. In the case where a predetermined number of frames is used as the reference for changing the number of pixel groups, the controller  421  sets a change reference frame number as reference information for changing the number of pixel groups in step S 2503  of  FIG. 29 . 
     Then, the controller  421  determines whether the number of frames displayed on the display unit  410 B after the successive display switching process has started is greater than or equal to the reference change reference frame number. If the number of frames displayed by the display unit  410 B after the successive display switching process has started is greater than or equal to the change reference frame number, operations may move on to changing the number of pixel groups. 
     It is noted that advantages similar to the case of using predetermined time information as the reference for changing the number of pixel groups may be obtained in the above example using a predetermined number of frames as the reference for changing the number of pixel groups. 
     Fifth Embodiment 
     In the following, a fifth embodiment of the present invention is described with reference to the accompanying drawings. 
     A display apparatus according to the fifth embodiment differs from that of the fourth embodiment in that it is configured to change the ratio of the number of frames to be displayed by each of the pixel groups to the total number of frames to be displayed by the display unit rather than changing the number of pixel groups. In the following, features of the fifth embodiment that are different from those of the fourth embodiment are described whereas descriptions of features identical to the fourth embodiment are omitted. Also, component elements of the display apparatus according to the fifth embodiment that are identical to those of the fourth embodiment are given the same reference numerals. 
     The display apparatus according to the fifth embodiment changes the ratio of the number of frames to be displayed by each of the pixel groups to the total number of frames to be displayed by the display unit using the change unit  426  of the controller  421  in order to adjust the frame display switching speed of the display unit  410 B. It is noted that the ratio of the number of frames to be displayed by each of the pixel groups to the total number of frames to be displayed by the display unit may simply be referred to as “ratio” hereinafter. 
     In the following, the frame display switching speed in accordance with the ratio of the display apparatus according to the fifth embodiment is described. 
     For example, in the case where the pixel electrodes  102  are divided into three pixel groups and the pixel groups are each configured to display differing frames as is described above in relation to the fourth embodiment, the frame display switching time of the display apparatus may be reduced to one third (⅓) of the display switching time of the display apparatus  100  according to the prior art. In this case, when the total number of frames to be displayed by the display unit  410 B is thirty (30) frames, the number of frames displayed by each of the pixel groups is ten (10) frames. Therefore, the ratio of the number of frames to be displayed by each of the pixel groups to the total number of frames to be displayed by the display unit  410 B is equal to ⅓. 
     In the present embodiment, another scheme is interchangeably used in which the pixel electrodes  102  are divided into three groups and two of the three pixel groups are arranged to display the same frame at the same time. In this case, if the total number of frames to be displayed by the display unit  410 B is thirty (30) frames, the number of frames to be displayed by each of the pixel groups is twenty (20) frames so that the ratio is equal to ⅔. In the following, the display switching speed of the display apparatus according to the fifth embodiment when the ratio is equal to ⅔ is described. 
       FIG. 31  is a timing chart illustrating the display switching speed of the display apparatus according to the fifth embodiment when the ratio is set to 2/3. 
     In the following, the display status of the display unit  410 B at time point R 0  is described. 
     At time point R 0  of  FIG. 31 , an initial frame F 0  is displayed by the display unit  410 B, and the display unit  410 B starts display switching operations for switching its frame display from the initial frame F 0  to a next frame F 1 . Since the next frame F 1  coming after the initial frame F 0  is to be displayed by the pixel group B, only the frame pattern to be displayed by the pixel group B is switched at time point R 0 . 
     In the following, the display status of the display unit  410 B at time point R 1  is described. 
     At time point R 1 , the pixel group A is in the process of switching its frame display from the pattern of frame F 0  to the pattern of frame F 2 . Thus, at this point neither frame F 0  nor frame F 2  is displayed by the pixel group A in a visibly recognizable manner. Also, at time point R 1 , the pixel group C is in the process of switching its frame display from the pattern of frame F 0  to the pattern of frame F 1 . 
     On the other hand, at time point R 1 , display switching operations for switching the frame display of the pixel group B from the pattern of frame F 0  to the pattern of frame F 1  are completed so that the pattern of frame F 1  is displayed by the pixel group B in a visibly recognizable manner. Thus, at time point R 1 , the pattern of frame F 1  is displayed on the display unit  410 B in a visibly recognizable manner. In other words, the display switching operations for switching the frame display of the display unit  410 B from the pattern of the initial frame F 0  to the pattern of the next frame F 1  are completed at time point R 1 . 
     According to the present embodiment, at time point R 1 , the pattern of frame F 1  is displayed by the pixel group B, and the pattern of frame F 1  is about to be displayed by the pixel group C. Thus, the number of pixel electrodes displaying the pattern of frame F 1  on the display unit  410 B at time point R 1  according to the present embodiment is greater than the number of pixel electrodes displaying the pattern of frame F 1  on the display unit  410 B at time point Q 1  of  FIG. 27  where the three different pixel groups are each arranged to display differing frame patterns. 
     Accordingly, the visibility of the pattern of frame F 1  displayed by the display unit  410 B at time point R 1  according to the present embodiment may be improved with respect to the visibility of the pattern of frame F 1  displayed by the display unit  410 B at time point Q 1  of  FIG. 27 . 
     It is noted that the display switching time for switching the frame display from the pattern of frame F 0  to the pattern of frame F 1  is denoted by T 3   a  in  FIG. 31 . Also, it is noted that a residual image resulting from the display switching operations of the pixel group A may be displayed in the background of the frame display of frame F 1  displayed by the pixel group B of the display unit  410 B; however, such a residual image may not constitute a substantial factor hampering the visibility of the frame display of frame F 1 . 
     In the following, the display status of the display unit  410 B at time point R 2  is described. 
     At time point R 2 , the pixel group B is in the process of switching its frame display from the pattern of frame F 1  to the pattern of frame F 2 . Thus, at this point, neither frame F 1  nor frame F 2  is displayed by the pixel group B in a visibly recognizable manner. Also, at time point R 2 , the pixel group C is in the process of switching its frame display from the pattern of frame F 1  to the pattern of frame F 3 . Thus, at this point neither frame F 1  nor frame F 3  is displayed by the pixel group C in a visibly recognizable manner. 
     On the other hand, at time point R 2 , display switching operations for switching the frame display of the pixel group A from the pattern of frame F 0  to the pattern of frame F 2  are completed so that the pattern of frame F 2  is displayed by the pixel group A in a visibly recognizable manner. 
     According to the present embodiment, at time point R 2 , the pattern of frame F 2  is displayed by the pixel group A, and the pattern of frame F 2  is about to be displayed by the pixel group B. Thus, as with the display status of the display unit  410 B at time point R 1 , the number of pixel electrodes displaying the pattern of frame F 2  on the display unit  410 B at time point R 2  is greater than the number of pixel electrodes displaying the pattern of frame F 2  on the display unit  410 B at time point Q 2  of  FIG. 27  where the three different pixel groups are each arranged to display differing frame patterns. 
     Accordingly, the visibility of the pattern of frame F 2  displayed by the display unit  410 B at time point R 2  may be improved with respect to the visibility of the pattern of frame F 2  displayed by the display unit  410 B at time point Q 2  of  FIG. 27 . It is noted that the display switching time for switching the frame display from the pattern of frame F 1  to the pattern of frame F 2  is denoted by T 3   b  in  FIG. 31 . 
     In the following, the display status of the display unit  410 B at time point R 3  is described. 
     At time point R 3 , the pixel group A is in the process of switching its frame display from the pattern of frame F 2  to the pattern of frame F 3 . Thus, at this point, neither frame F 2  nor frame F 3  is displayed by the pixel group A in a visibly recognizable manner. Also, at time point R 3 , the pixel group B is in the process of switching its frame display from the pattern of frame F 2  to the pattern of frame F 4 . Thus, at this point, neither frame F 2  nor frame F 4  is displayed by the pixel group B in a visibly recognizable manner. 
     On the other hand, at time point R 3 , display switching operations for switching the frame display of the pixel group C from the pattern of frame F 1  to the pattern of frame F 3  are completed so that the pattern of frame F 3  is displayed by the pixel group C in a visibly recognizable manner. 
     Thus, at time point R 3 , the pattern of frame F 3  is displayed by the pixel group C, and the pattern of frame F 3  is about to be displayed by the pixel group A. In other words, as with the display status of the display unit  410 B at time point R 1 , the number of pixel electrodes displaying the pattern of frame F 3  on the display unit  410 B at time point R 3  is greater than the number of pixel electrodes displaying the pattern of frame F 3  on the display unit  410 B at time point Q 3  of  FIG. 27  in which the three different pixel groups are each arranged to display differing frame patterns. 
     Accordingly, the visibility of the pattern of frame F 3  displayed by the display unit  410 B at time point R 3  may be improved with respect to the visibility of the pattern of frame F 3  displayed by the display unit  410 B at time point Q 3  in the example of  FIG. 27 . It is noted that the display switching time for switching the frame display from the pattern of frame F 2  to the pattern of frame F 3  is also denoted by T 3   b  in  FIG. 31 . 
     In the example of  FIG. 31 , the length of the display switching time T 3   b  is approximately two thirds of the length of the display switching time T 3   a . The display switching time T 3   a  is equal to a total of the scanning time and the pixel pattern switching time and corresponds to the display switching time of the display apparatus  100  according to the prior art. 
     As can be appreciated from the above descriptions, in the present embodiment, the display switching time for switching from one frame to the next frame aside from the case of switching from the initial frame to the next frame may be reduced to approximately two thirds of the length of the display switching time of the display apparatus  100  according to the prior art. It is noted that although the display switching time in the example is longer than that in the example of  FIG. 27 , the visibility of the frame pattern being displayed by the display unit  410 B may be improved. 
     According to the present embodiment, the ratio of the number of frames to be displayed by each of the pixel groups to the total number of frames to be displayed by the display unit  410 B may be changed to adjust the display switching speed of the display apparatus according to the present embodiment. 
     In the following, a process of changing the ratio in the display apparatus according to the fifth embodiment is described with reference to  FIG. 32 .  FIG. 32  is a flowchart illustrating operations for changing the ratio of the number of frames to be displayed by each of the pixel groups to the total number of frames to be displayed by the display unit  410 B in the display apparatus according to the present embodiment. In the illustrated example of  FIG. 32 , it is assumed that the pixel electrodes  102  of the display unit  410 B are divided into three pixel groups and the ratio is set to 2/3. Also, in this example, the three pixel groups are referred to as pixel group A, pixel group B, and pixel group C. 
     According to  FIG. 32 , the display apparatus of the present embodiment starts a successive display switching process in response to a successive display switching process start command input by a user via the operations unit  427  (step S 2801 ). At this point, the control unit  421  identifies the initial frame displayed on the display unit  410 B (i.e., frame displayed before the frame display switching is started) as frame N (step S 2802 ), and reads information on this frame N from the memory  422 . For example, the frame information read from the memory  422  may be identification information indicating the order of frame N within the frames stored in the memory  422 . 
     Then, the controller  421  reads and sets time information to be used for determining whether to change the ratio (step S 2803 ). In one example, the time information may represent a change reference time that may be set by the setting unit  425  and stored in a storage unit (not shown) of the display apparatus to be used as a reference for determining whether the controller  421  should change the ratio of the display apparatus. Then, the controller  421  sets the ratio to “2/3” corresponding to the initial ratio that is determined beforehand and starts frame switching operations of the successive display switching process (step S 2804 ). 
     The controller  421  applies signals to the scanning lines  106  and the signal lines  107  to control the pixel group A to display the pattern of frame N and the pixel groups B and C to display the pattern of frame (N+1) (step S 2805 ). Specifically, in a case where pixel electrodes  102  positioned on a given scanning line  106  that has its TFTs  105  turned on belongs to the pixel group A, display data signals for displaying frame N are applied to the signal lines  107 . In a case where pixel electrodes  102  positioned on a given scanning line  106  that has its TFTs  105  turned on belongs to the pixel group B or C, display data signals for displaying frame (N+1) are applied to the signal lines  107 . 
     Then, the controller  421  determines whether the frame (N+1) corresponds to a target frame (step S 2806 ). If the frame (N+1) is determined to be the target frame in step S 2806 , the controller  421  applies signals to the scanning lines  106  and the signal lines  107  to control the pixel groups A, B, and C to display the pattern of frame (N+1) (step S 2807 ). Then, the controller  421  controls the display unit  410 B to display the pattern of frame (N+1) and ends the successive display switching process (step S 2808 ). 
     On the other hand, if it is determined in step S 2806  that the frame (N+1) does not correspond to the target frame, the controller  421  compares the time elapsed from the time the successive display switching process has been started (i.e., time duration of the successive display switching process) with the change reference time used as a reference for changing the ratio that is set in step S 2803  (step S 2809 ). Upon determining that the time duration of the successive display switching process is longer than the reference time, the controller  421  resets the initial frame N to N=N+1 (step S 2810 ) and controls the change unit  426  to change the ratio (step S 2811 ). In the present example, it is assumed that the ratio is changed from “2/3” to “1/3” as is described in detail below. 
     Upon determining in step S 2809  that the time duration of the successive display switching process is shorter than the change reference time, the controller  421  applies signals to the scanning lines  106  and the signal lines  107  to control the pixel groups A and B to display the pattern of frame (N+2) and the pixel group C to display the pattern of frame (N+1) (step S 2812 ). 
     Then, the controller  421  determines whether the frame (N+2) corresponds to the target frame (step S 2813 ). If it is determined in step S 2813  that the frame (N+2) corresponds to the target frame, the controller  421  applies signals to the scanning lines  106  and the signal lines  107  to control the pixel groups A, B, and C to display the pattern of frame (N+2) (step S 2814 ). Then the controller  421  controls the display unit  410 B to display the pattern of frame (N+2) and ends the successive display switching process (step S 2808 ). 
     If it is determined in step S 2813  that the frame (N+2) does not correspond to the target frame, the controller  421  compares the time elapsed from the time the successive display switching process has been started (i.e., time duration of the successive display switching process) with the change reference time set in step S 2803  (step S 2815 ). When the duration time of the successive display switching process is longer than the change reference time, the controller  421  resets the initial frame N to N=N+2 (step S 2516 ) and changes the ratio of the display apparatus using the change unit  426  (step S 2811 ). 
     Also, when it is determined in step S 2815  that the duration time of the successive display switching process is shorter than the change reference time, the controller  421  applies signals to the scanning lines  106  and the signal lines  107  to control the pixel groups A and C to display the pattern of frame (N+3), and the pixel group B to display the pattern of frame (N+2) (step S 2817 ). 
     Then, the controller  421  determines whether the frame (N+3) corresponds to the target frame (step S 2818 ). If it is determined in step S 2818  that the frame (N+3) corresponds to the target frame, the controller  421  applies signals to the scanning lines  106  and the signal lines  107  to control the pixel groups A, B, and C to display the pattern of frame (N+3) (step S 2819 ). Then, the controller  421  controls the display unit  410 B to display the pattern of frame (N+3) and ends the successive display switching process (step S 2808 ). 
     If it is determined in step S 2818  that the frame (N+2) does not correspond to the target frame, the controller  421  compares the time elapsed from the time the successive display switching process has been started (i.e., time duration of the successive display switching process) with the change reference time used as a reference for changing the ratio that is set in step S 2803  (step S 2820 ). When the duration time of the successive display switching process is longer than the change reference time, the controller  421  resets the initial frame N to N=N+3 (step S 2521 ) and changes the ratio of the display apparatus using the change unit  426  (step S 2811 ). 
     When it is determined in step S 2820  that the duration time of the successive display switching process is shorter than the change reference time, the controller  421  resets the initial frame N to N=N+3 (step S 2822 ) and goes back to step S 2805  to apply signals to the scanning lines  106  and the signal lines  107  to control the pixel group A to display the pattern of frame (N=N+3) and the pixel groups B and C to display the pattern of frame (N+1=N+4). 
     It is noted that the controller  421  repeats the process steps of S 2805 -S 2822  until the target frame is displayed on the display unit  410 B. 
     In the following, the process step S 2811  for changing the ratio using the change unit  426  is described. 
     When the ratio is changed from ⅔ to ⅓ in the display apparatus according to the present embodiment, the pixel groups A, B, and C are each arranged to display differing frames. 
     In this case, operations of the display apparatus of the present embodiment after the ratio is changed to ⅓ may be identical to the operations of the display apparatus  400 B of the fourth embodiment from step S 2602  onward as illustrated in  FIG. 30 . Accordingly, descriptions of the operations of the display apparatus according to the fifth embodiment when the ratio is changed to ⅓ are omitted. It is noted that the pixel group A used in the present embodiment may correspond to the pixel group C of  FIG. 30 , the pixel group B used in the present embodiment may correspond to the pixel group D of  FIG. 30 , and the pixel group C used in the present embodiment may correspond to the pixel group E of  FIG. 30 . 
     When the ratio is changed to ⅓ in the display apparatus according to the present embodiment, the display switching speed of the display apparatus may be reduced to approximately one third (⅓) of the display switching speed of the display apparatus  100  of the prior art. On the other hand, the display switching speed of the display apparatus of the present embodiment before the ratio is changed is approximately two thirds (⅔) of the display switching speed of the display apparatus  100  according to the prior art. In this way, the display switching speed of the display apparatus according to the present embodiment may be adjusted by changing the ratio. 
     In one example, the ratio may be changed to a value that is less than the initial ratio value so that the display switching speed of the display apparatus may be increased. In this way, the required process time for having a desired frame (page) displayed by the display unit  410 B may be reduced so that the desired frame may be promptly displayed. 
     In another example, the ratio may be changed to a value that is greater than the initial ratio value so that the display switching speed of the display apparatus may be reduced. In this way, the frame display switching speed of the display apparatus may be adjusted according to usage preferences of a user so that operability of the display apparatus may be improved. 
     It is noted that in the above-described embodiment, time information is set in step S 2803  of  FIG. 32  as a reference for determining whether to change the ratio. However, the present invention is not limited to such an embodiment, and in an alternative embodiment, a predetermined number of displayed frames may be used as such a reference. In this case, the display apparatus preferably has a counter function for counting the number of frames displayed by the display unit  410 B. Such a counter function may be realized by the controller  421 , for example. 
     In the following, an embodiment in which a predetermined number of frames are used as a reference for determining whether to change the ratio is described. In the case of using a predetermined number of frames as a reference for determining whether to change the ratio, the controller  421  sets a change reference frame number in step S 2803  of  FIG. 32  instead of setting the change reference time. 
     Then, the controller  421  determines in step S 2809  whether the number of frames displayed by the display unit  410 B since the successive display switching process has been started is greater than or equal to the change reference frame number. If the number of frames displayed by the display unit  410 B is greater than or equal to the change reference frame number, the controller  421  moves on to perform operations for changing the ratio. 
     It is noted that the above embodiment may realize advantages similar to those realized in the embodiment using the change reference time as a reference for determining whether to change the ratio. 
     Sixth Embodiment 
     In the following, a sixth embodiment of the present invention is described with reference to the accompanying drawings. 
     In the display apparatus according to the sixth embodiment, operations performed upon receiving a successive display switching process end command signal differs from those of the fourth embodiment. In the following, only the features of the sixth embodiment that differ from those of the fourth embodiment are described, and elements of the sixth embodiment that are identical to those of the fourth embodiment are given the same numerical references. 
     It is noted that the structure of the display apparatus according to the sixth embodiment may be identical to that of the display apparatus  400 B according to the fourth embodiment. In the following, operations of the display apparatus  400 B according to the sixth embodiment are described with reference to  FIG. 33 .  FIG. 33  is a flowchart illustrating operations performed in the display apparatus according to the sixth embodiment upon receiving a successive display switching process end command signal. 
     In the display apparatus according to the sixth embodiment, when a successive display switching process end command signal is received, the display unit  410 B is controlled to go back a predetermined number of frames from the frame that is currently displayed by the display unit  410 B (at the time the end command signal is received) and display the corresponding frame as the target frame. It is noted that the operations illustrated in  FIG. 33  may be implemented in combination with the process of changing the number of pixel groups as is described above in relation to the fourth embodiment or the process of changing the ratio as is described above in relation to the fifth embodiment, for example. Also, in the illustrated example of  FIG. 33 , it is assumed that the pixel electrodes  102  of the display unit  410 B are divided into two pixel groups, referred to as pixel group A and pixel group B. 
     According to  FIG. 33 , in the display apparatus of the present embodiment, the controller  421  starts a successive display switching process in response to a successive display switching process start command input via the operations unit  427  (step S 2901 ). At this point, the control unit  421  identifies the initial frame displayed on the display unit  410 B (i.e., frame displayed before frame display switching operations are started) as frame N (step S 2902 ), and reads frame information related to this frame N from the memory  422 . 
     Then, the controller  421  sets information on a predetermined number of frames to be tracked back from a currently displayed frame upon receiving a successive display switching process end command signal (step S 2903 ). In one example, such information on the predetermined number of frames may be set beforehand using the setting unit  425  and stored in the memory  422  or some other storage unit (not shown) of the display apparatus. In another example, the information on the predetermined number of frames may be input by the user via the operations unit  427  when the successive display switching process is started. In such cases, the controller  421  may read the information from the relevant storage location and set the information on the predetermined number of frames in step S 2903  based on the read information. 
     Then, the controller  421  applies signals to the scanning lines  106  and the signal lines  107  to control the pixel group A to display the pattern of frame N and the pixel group B to display the pattern of frame (N+1) (step S 2904 ). Then, the controller  421  determines whether the frame (N+1) corresponds to the target frame (step S 2905 ). It is noted that in the present example, the control unit  421  of the display apparatus determines that a target frame has been displayed on the display unit  410 B when a successive display switching process end command signal is input via the operations unit  427 . Such a determination may be made during the time from when first scanning operations are ended until the time next scanning operations are started. 
     If the frame (N+1) is determined to be the target frame in step S 2905 , the controller  421  applies signals to the scanning lines  106  and the signal lines  107  to control the pixel groups A and B to display the pattern of a previously displayed frame that is tracked back a predetermined number of frames from frame (N+1) according to the information set in step S 2903  (step S 2906 ). Then, the controller  421  ends the successive display switching process (step S 2907 ). In one embodiment, upon ending the successive display switching process after determining that the target frame has been displayed by the display unit  410 B, the controller  421  may store information in the memory  422  pertaining to the frame that has been determined as the target frame out of the plural frames stored in the memory  422 . 
     If it is determined in step S 2905  that the frame (N+1) does not correspond to the target frame, the controller  421  applies signals to the scanning lines  106  and the signal lines  107  to control the pixel group A to display the pattern of frame (N+2) and the pixel group B to display the pattern of frame (N+1) (step S 2908 ). 
     Then, the controller  421  determines whether the frame (N+2) corresponds to the target frame (step S 2909 ). If it is determined in step S 2909  that the frame (N+2) corresponds to the target frame, the controller  421  applies signals to the scanning lines  106  and the signal lines  107  to control the pixel groups A and B to display the pattern of a previously displayed frame that is tracked back a predetermined number of frames from frame (N+2) according to the information set in step S 2503  (step S 2910 ). Then, the controller  421  ends the successive display switching process (step S 2907 ). 
     If it is determined in step S 2909  that the frame (N+2) does not correspond to the target frame, the controller the controller  421  resets the initial frame N to N=N+1 (step S 2911 ) and goes back to step S 2904  to apply signals to the scanning lines  106  and the signal lines  107  to control the pixel group A to display the pattern of frame (N=N+1), and the pixel group B to display the pattern of frame (N+1=N+2). 
     It is noted that the controller  421  repeats the process steps of S 2904 -S 2911  until a target frame is displayed on the display unit  410 B. 
     As can be appreciated from the above descriptions, in the display apparatus according to the present embodiment, when a successive display switching process end command signal is input, the display unit  410 B may be arranged to go back a predetermined number of frames from the frame currently displayed by the display unit  410 B to display a previously displayed frame as the target frame. Accordingly, even when there is a time difference between the point at which a user recognizes a desired framed displayed on the display unit  410 B and the point at which the user operates the operations unit  427  to stop the successive display switching process, a frame closer to the frame desired by the user may be displayed by the display unit  410 B so that the desired frame (page) may be promptly displayed. 
     In the following, the process step of S 2903  for setting information on the predetermined number of frames is described in detail. 
     In the display apparatus according to the present embodiment, the transition of frames displayed on the display unit  410 B may be faster as the frame display switching speed is increased, and the transition of the frames displayed by the display unit  410 B may be slower as the frame display switching speed is decreased. Therefore, the predetermined number of frames set in step S 2903  of  FIG. 33  is preferably adjusted according to the frame display switching speed of the display apparatus. For example, a relatively large value is preferably set as the predetermined number of frames to be tracked back from the currently displayed frame when the frame display switching speed of the display apparatus is relatively fast, and a relatively small value may preferably be set as the predetermined number of frames when the frame display switching speed of the display apparatus is relatively slow. 
     Accordingly, in certain preferred embodiments, the predetermined number of frames to be tracked back from the currently displayed frame may be set to different values depending on the number of pixel groups and/or the ratio set in the display apparatus. 
     For example, provided that Ya denotes the predetermined number of frames in the case where the pixel electrodes are divided into three pixel groups and the ratio is set to 1/3, Yb denotes the predetermined number of frames in the case where the pixel electrodes are divided into two pixel groups and the ratio is set to 1/2, and Yc denotes the predetermined number of frames in the case where the pixel electrodes are divided into three groups and the ratio is set to 2/3, the values of Ya, Yb, and Yc preferably satisfy the following relationship:
 
Ya&gt;Yb&gt;Yc
 
It is noted that such a relationship is preferably realized in view of the fact that with respect to the above three cases, the frame display switching speed may be the fastest when the pixel electrodes are divided into three pixel groups and the ratio is set to 1/3, and the frame display switching speed may be the slowest when the pixel electrodes are divided into three groups and the ratio is set to 2/3.
 
     In the following, the frame display switching speed in relation to the number of pixel groups and the ratio is described.  FIG. 34  is a graph illustrating successive display switching times realized by various successive frame display schemes. 
     As can be appreciated from  FIG. 34 , by employing the successive frame display schemes according to embodiments of the present invention that involves dividing pixel electrodes into plural pixel groups, the display switching time may be reduced compared to that of the prior art. It is noted that in the illustrated example of  FIG. 34 , the process time for switching the frame display from one frame to another frame (e.g., Ta, T 2   a , and T 3   a ) is assumed to be 0.4 seconds. Also, it is noted that in the illustrated example of  FIG. 34 , the scanning time is not taken into account in calculating the display switching time since the scanning time is substantially shorter than the pixel pattern switching time. 
     According to one embodiment of the present invention, a predetermined number of frames to be tracked back from a currently displayed frame may be set according to the frame display switching speed. In this way, a frame close to the frame desired by a user may be displayed as the target frame even when there is a time lag between the point at which the user recognizes the desired frame and the point at which the user operates the operations unit  427  to end the successive display switching process. 
     In one preferred embodiment, a specific pixel group that is to display the starting frame from which the process of going back a predetermined number of frames to display the target frame is performed may be set beforehand. In the following, the starting frame for performing the process of going back a predetermined number of frames is described in the case where the pixel electrodes are divided into three pixel groups and the ratio is set to 1/3. 
     In the case where the pixel electrodes are divided into three pixel groups and the ratio is set to ⅓ in a display apparatus according to an embodiment of the present invention, three different frames displayed by the three pixel groups may be superposed and displayed on a display unit. In this case, three different frames may be displayed by the three different pixel groups of the display unit at the time a successive display switching process end command signal is input. Accordingly, in one preferred embodiment, a specific pixel group that is to display the starting frame may be set beforehand. 
     For example, if the frame displayed by pixel group A is set to be the starting frame, the controller  421  may use the frame displayed by the pixel group A at the time a successive display switching process end command signal is input as the starting frame. Then, the controller  421  may go back a predetermined number of frames from the frame displayed by the pixel group A to display the target frame. It is noted that such a setting may be made by the setting unit  425  beforehand and stored in the memory  422  or some other storage unit (not shown) of the display apparatus. In another example, such a setting may be input by a user via the operations unit  427  when the successive display switching process is started. 
     Although the present invention is shown and described with respect to certain preferred embodiments, it is obvious that equivalents and modifications may occur to others skilled in the art upon reading and understanding the specification. The present invention includes all such equivalents and modifications, and is limited only by the scope of the claims. 
     The present application is based on and claims the benefit of the earlier filing date of Japanese Patent Application No. 2006-226523 filed on Aug. 23, 2006 and Japanese Patent Application No. 2006-352517 filed on Dec. 27, 2006, the entire contents of which are hereby incorporated by reference.