Patent Publication Number: US-2015067576-A1

Title: Display device, image forming apparatus, and display control method

Description:
INCORPORATION BY REFERENCE 
     The present application claims priority under 35 U.S.C. §119 to Japanese Patent Application No. 2013-177897, filed Aug. 29, 2013. The contents of this application are incorporated herein by reference in their entirety. 
     BACKGROUND 
     The present disclosure relates to display devices, image forming apparatuses, and display control methods for display of a plurality of pages. 
     Portable terminals of some type are configured such that when a touch panel displaying a single image file (page) detects a flick by user&#39;s single finger, an image file moved by one file from the currently displayed image file is displayed. Likewise, when the touch panel detects a flick by user&#39;s three fingers, an image file moved by three files from to the currently displayed image file is displayed. 
     SUMMARY 
     A display device according to one aspect of the present disclosure includes a display section, a detection section, and a display control section. The display section has a display surface and is configured to display a plurality of pages. The detecting section is configured to detect a touch point in touch with the display surface of the display section. The display control section is configured to flip a page toward a last page or a top page of the pages in a direction corresponding to a travel direction of touch point. The display control section changes an amount of page flip each time the detecting section detects a change in the travel direction. 
     An image forming apparatus according to the second aspect of the present disclosure includes a display device according to the first aspect of the present disclosure and an image forming section. The image forming section is configured to form on a sheet an image of a page selected from the pages. 
     A display control method according to the third aspect of the present disclosure includes: displaying a plurality of pages on a display section; obtaining information on a touch point in touch with a display surface of the display section; flipping a page toward a last page or a top page of the pages in a direction corresponding to a travel direction of the touch point; and changing an amount of page flip each time a change in the travel direction of the touch point is detected. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram showing a display device according to the first embodiment of the present embodiment. 
         FIGS. 2A-2C  are diagrams for explaining page flip control that the display device performs according to the first embodiment of the present disclosure. 
         FIG. 3  is a flowchart depicting a display control method that the display device performs according to the first embodiment of the present disclosure. 
         FIG. 4  is a diagram for explaining a page display format in which the display device initially displays a plurality of pages according to the second embodiment of the present disclosure. 
         FIGS. 5A-5D  are diagrams for explaining page flip control that the display device performs according to the second embodiment of the present disclosure. 
         FIG. 6  is a flowchart depicting a display control method that the display device performs according to the second embodiment of the present disclosure. 
         FIGS. 7A-7D  are diagrams for explaining page flip control that the display device performs according to the third embodiment of the present disclosure. 
         FIG. 8  is a flowchart depicting a display control method that the display device performs according to the third embodiment of the present disclosure. 
         FIG. 9  is a block diagram showing an image forming apparatus according to the fourth embodiment of the present embodiment. 
         FIG. 10  is a schematic cross sectional view explaining the image forming apparatus according to the fourth embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the present disclosure will be described below with reference to the accompanying drawings. Like numerals denote like elements or corresponding elements in the drawings, and duplicate description shall be omitted. 
     First Embodiment 
     [Basic Principle] 
     With reference to  FIGS. 1 and 2 , description will be made about the basic principle of a display device  10  according to the first embodiment of the present disclosure.  FIG. 1  is a block diagram showing the display device  10 .  FIGS. 2A-2C  are diagrams for explaining page flip control that the display device  10  performs. The display device  10  includes a display control section  100 , a display section  210 , and a touch panel  220  as a detection section. 
     The display section  210  has a display surface and displays a plurality of pages P of, for example, an eBook or a set of images. The touch panel  220  detects a touch point in touch with the display surface of the display section  210 . When the touch panel  220  detects a touch point moving in a travel direction (e.g., a travel direction from a point D 1  to a point D 3 ), the display control section  100  flips the pages P toward the last page or the top page of the pages P (see an arrow C 1  in  FIG. 2A , for example) in a direction corresponding to the travel direction. The display control section  100  changes the amount of page flip each time the touch panel  220  detects a change in the travel direction of the touch point. For example, the travel direction of the touch point is reversed at the point D 3 , a point D 5 , and then a point D 7 , the amount of page flip is changed from an amount of flip A 10  to an amount of flip A 20  and then to an amount of flip A 30 . 
     According to the first embodiment, each time the touch panel  220  detects a change in the travel direction of the touch point, the amount of page flip can be decreased in a stepwise manner by changing the amount of page flip (e.g., the amounts of page flip: A 10 &gt;A 20 &gt;A 30 ). As a result, a page search range can be reduced, thereby mitigating a burden in page search for a target page P from the pages P. 
     [Details of Page Flip Control] 
     Page flip control will be described in detail with reference to  FIGS. 1 and 2 . An eBook  20  will be discussed as an example in the first embodiment. The X axis and Y axis are in parallel to the long side and the short side of the display surface of the display section  210 , respectively. The display control section  100  calculates an amount of travel of the touch point on the basis of the position of the touch point that the touch panel  220  detects. The amount of travel of the touch point in the present specification means an X component of a movement vector of the touch point. 
     The display control section  100  causes the display section  210  to display the eBook  20 . The eBook  20  contains a plurality of pages P. A front edge F is displayed that forms a part of the eBook  20 . In the present specification, the user operates the touch panel  220  using his/her single finger. The touch panel  220  detects the touch point of the finger in touch with the display surface of the display section  210 . 
     As shown in  FIG. 2A , when the touch panel  220  detects the touch point moving from the point D 1  toward the point D 3 , the display control section  100  responsively flips pages P in the direction (see the arrow C 1 ) corresponding to the travel direction of the touch point. The display control section  100  flips pages P during the time when the touch panel  220  detects user&#39;s touch with the display surface of the display section  210 . When assuming that the travel direction of the touch point is reversed at the point D 3 , the display control section  100  flips pages P by the amount A 10  of page flip that corresponds to the amount of travel of the touch point from the point D 1  to the point D 3  during the time when the touch point moves from the point D 1  to the point D 3 . 
     As shown in  FIG. 2B , when the touch panel  220  detects a reversal of the travel direction of the touch point at the point D 3 , the display control section  100  reverses the page flip direction (see an arrow C 2 ) and flips the pages P. The display control section  100  flips pages P during the time when the touch panel  220  detects user&#39;s touch with the display surface of the display section  210 . When assuming next that the travel direction of the touch point is reversed again at the point D 5 , the display control section  100  flips pages P by the amount A 20  of page flip that corresponds to the amount L 20  of travel of the touch point from the point D 3  to the point D 5  during the time when the touch point moves from the point D 3  to the point D 5 . 
     As shown in  FIG. 2C , when the touch panel  220  detects a reversal of the travel direction of the touch point at the point D 5 , the display control section  100  responsively reverses the page flip direction (see an arrow C 1 ) and flips pages P. The display control section  100  flips the pages P during the time when the touch panel  220  detects user&#39;s touch with the display surface of the display section  210 . When still assuming that the travel direction of the touch point is reversed again at the point D 7 , the display control section  100  flips the pages P by the amount A 30  of page flip that corresponds to the amount L 30  of travel of the touch point from the point D 5  to the point D 7  during the time when the touch point moves from the point D 5  to the point D 7 . 
     [Display Control Method] 
     With reference to  FIGS. 1-3 , a display control method will be described that the display device  10  performs.  FIG. 3  is a flowchart depicting the display control method. Through execution of Steps S 10  to S 110 , the display control section  100  can change the amount of page flip each time a change in the travel direction of the touch point is detected. A specific procedure is as follows. 
     At Step S 10 , the display control section  100  causes the display section  210  to display the plurality of pages P (the eBook  20 ). At Step S 20 , the display control section  100  obtains through the touch panel  220  information on the touch point in touch with the display surface of the display section  210 . At Step S 30 , the display control section  100  determines the page flip direction corresponding to the travel direction of the touch point. At Step S 40 , the display control section  100  flips the pages P. 
     At Step S 50 , the display control section  100  determines whether or not the travel direction of the touch point that the touch panel  220  detects is reversed. When a negative determination is made (No) at Step S 50 , the routine proceeds to Step S 60 . At Step S 60 , the display control section  100  determines whether or not the information on the touch point is obtained through the touch panel  220 . When a positive determination is made (Yes) at Step S 60 , the routine returns to Step S 40 . In this manner, the display control section  100  flips pages P during the time when the touch panel  220  detects user&#39;s touch with the display surface of the display section  210 . 
     By contrast, when a negative determination is made (No) at Step S 60 , the routine proceeds to Step S 70 . At Step S 70 , the display control section  100  stops the page flip. 
     When a positive determination is made (Yes) at Step S 50 , the routine proceeds to Step S 90 . At Step S 90 , the display control section  100  stores the reversal point where the travel direction of the touch point is reversed. At Step S 100 , the display control section  100  flips pages P up to the reversal point. At Step S 110 , the display control section  100  reverses the page flip direction. Then, the routine returns to Step S 40 . 
     The display control section  100  executes Steps S 30 , S 110 , and S 40  to flip pages toward the last page or the top page of the pages in the direction corresponding to the travel direction of the touch point. 
     As has been described with reference to  FIGS. 1-3 , in the first embodiment, the amount of page flip can be decreased in a stepwise manner (the amounts of page flip: A 10 &gt;A 20 &gt;A 30 ) each time a reversal of the travel direction of the touch point is detected. Accordingly, the page search range can be reduced, thereby enabling mitigation of a burden in page search for a target page P. Further, according to the first embodiment, pages P are flipped during the time when the touch panel  220  detects the touch point. This means that the user&#39;s continuous touch can flip pages P. As a result, fine adjustment of page flip can be facilitated. Moreover, the user can more easily and intuitionally flip pages P than in the case of page flip by pushing a button on the touch panel. Still further, a target page P can be searched with less steps. 
     Yet further, according to the first embodiment, the amount of page flip is independent of the number of fingers in touch, in other words, is free from limitations on the number of fingers in touch. Also, detection of a plurality of touch points is not required for page flip. This can eliminate the need of complicated circuits and processes for detection of three or more points. In addition, the relationship between the travel direction of the touch point in page flip and the direction of page flip approximates to the relationship between a direction of a finger moving in turning pages of an actual book and a direction in which pages of the book are turned. Accordingly, further intuitional page flip (turning) can be achieved. 
     The display control section  100  may change the amount of page flip per unit amount of travel of the touch point each time the travel direction of the touch point changes. Detailed description will be made in the following second embodiment. 
     Second Embodiment 
     [Outline] 
     With reference to  FIG. 1 , description will be made about the display device  10  according to the second embodiment of the present disclosure. The display device  10  according to the second embodiment has the same configuration as the display device  10  shown in  FIG. 1 . The display control section  100  causes the display section  210  to display on an enlarged scale to-be-flipped pages P out of the pages P each time the touch panel  220  detects a change in the travel direction (a reversal in the second embodiment). Accordingly, the amount of page flip per unit amount of travel of the touch point can be decreased. As a result, page visibility and efficiency of page search for a target page P can be enhanced. 
     [Details of Page Flip Control] 
     Page flip control (scale control) will be described in detail with reference to  FIGS. 1 ,  4 , and  5 . The eBook  20  will be discussed as an example in the second embodiment.  FIG. 4  is a diagram for explaining a display format of the eBook  20  (a plurality pages P) that the display device  10  displays initially. 
     As shown in  FIG. 4 , the display control section  100  causes the display section  210  to display the eBook  20  in an upright, closed state. The eBook  20  contains a plurality of pages P. The display control section  100  causes the display section  210  to display a front edge F that forms a part of the eBook  20 . The front edge F functions as an operation region. The display control section  100  determines a page P as a page flip start point out of the pages P according to the position of the touch point (e.g., a point D 11 ) in the front edge F. Specific procedure is as follows. 
     The front edge F in a state in which the eBook  20  is closed has a width L that expresses the total number N of pages of the eBook  20 . The display control section  100  calculates a page P corresponding to the point D 11  where the touch panel  220  detects the touch point, based on the width L and a length LA from the point D 11  on the front edge F to the top page P, or the width L and a length LB from the point D 11  on the front edge F to the last page P. The display control section  100  determines a page corresponding to the point D 11  as a page P serving as a flip start point. The page number of the page P serving as the page flip start point can be obtained by (LA/L)×N or (1−LB/L)×N. For example, the user touches his/her finger with a point around a target page P in the front edge F as a yardstick for specification of a page P that is to be opened first (a page P serving as a page flip start point). Accordingly, the user can search for the target page P using the first opened page P as a reference. This can result in more efficient page search for the target page P. 
       FIGS. 5A-5D  are diagrams for explaining page flip control that the display device  10  performs. 
     As shown in  FIG. 5A , when the touch panel  220  detects the touch point moving from the point D 11 , the display control section  100  responsively opens the eBook  20  and flips pages P in the direction (see an arrow C 1 ) corresponding to the travel direction of the touch point. At the time when the touch point is detected at the point D 11 , the to-be-flipped pages P are pages PV 1 . When the eBook  20  is opened, the front edge F is divided. Specifically, the front edge F is divided into a front edge portion Fa and a front edge portion Fb. 
     Next, the user reverses the travel direction of his/her finger in touch with the display surface at the point D 13 . 
     As shown in  FIG. 5B , when the touch panel  220  detects the reversal of the travel direction of the touch point at the point D 13  (see  FIG. 5A ), the display control section  100  reverses the page flip direction (see the arrow C 2 ) and flips pages P. In so doing, the display control section  100  causes the display section to display to-be-flipped pages PV 2  at the reversal on an enlarged scale as compared with the pages PV 1  before the reversal. Further, the display control section  100  hides pages PI 1  (see  FIG. 5A ) other than the to-be-flipped pages PV 2  at the reversal. 
     Next, the user reverses the travel direction of the finger in touch with the display surface at the point D 15 . 
     As shown in  FIG. 5C , when the touch panel  220  detects the reversal of the travel direction of the touch point at the point D 15 , the display control section  100  responsively reverses the page flip direction (see the arrow C 1 ) and flips pages P. In so doing, the display control section  100  causes the display section  210  to display to-be-flipped pages PV 3  at the reversal (see  FIG. 5B ) on an enlarged scale as compared with the pages PV 1  before the reversal. Further, the display control section  100  hides pages PI 2  (see  FIG. 5B ) other than the to-be-flipped pages PV 3  at the reversal. 
     Next, the user removes the finger in touch with the display surface at the point D 17 . 
     As shown in  FIG. 5D , when the touch panel  220  detects transition from a touch point detecting state in which the touch point is detected to a touch point non-detecting state in which the touch point is not detected, the display control section  100  stops flipping pages P and changes the display format of the pages P (the eBook  20 ). For example, the display control section  100  changes the display format of the pages P (the eBook  20 ) from the upright format to a two-page spread format. 
     Accordingly, when the user only removes the finger from the display surface upon discovery of the target page P, the page flip can be stopped, and the target page P can be displayed in the two-page spread format. In other words, the user can change the page display format through a simple operation. 
     Furthermore, for example, the display control section  100  may be so set to change the page display format from the two-page spread format to the upright format (see  FIG. 4 ) of the pages P in response to a predetermined operation (e.g., double click) that the touch panel  220  detects in the state in which the page P is displayed in the two-page spread format. 
     [Change in Amount Of Page Flip Per Unit Amount of Travel of Touch Point] 
     With reference to  FIGS. 1 and 5 , description will be made about change in amount of page flip per unit amount of travel of the touch point. Each time the touch panel  220  detects a change in the travel direction of the touch point, the to-be-flipped pages PV is displayed on an enlarged scale. This can decrease the amount of page flip per unit amount of travel of the touch point each time a change in the travel direction of the touch point is detected. By contrast, the amount of page flip per unit time is fixed in the second embodiment. 
     A specific example will be described below. Given that Mb is an amount of page flip per unit amount of travel of the touch point before a change in the travel direction of the touch point. Given also that pages P displayed after a change in the travel direction of the touch point is increased in size (zoom rate) K times pages P displayed before the change, wherein K is larger than  1 . Accordingly, after a change in the travel direction of the touch point, an amount Ma of page flip per unit amount of travel of the touch point is Mb/K. 
     Herein, A 60  and L 60  in  FIG. 5A  denote the amount of page flip and the amount of travel of the touch point, respectively. In this case, the amount of page flip per unit amount of travel of the touch point is A 60 /L 60 , for example. Further, A 70  and L 70  in  FIG. 5B  denote the amount of page flip and the amount of travel of the touch point, respectively. In this case, the amount of page flip per unit amount of travel of the touch point is A 70 /L 70 , for example. Yet further, A 80  and L 80  in  FIG. 5C  denote the amount of page flip and the amount of travel of the touch point, respectively. In this case, the amount of page flip per unit amount of travel of the touch point is A 80 /L 80 , for example. 
     Each time a change in the travel direction of the touch point is detected, the amount of page flip per unit amount of travel of the touch point is decreased. Therefore, A 60 /L 60 &gt;A 70 /L 70 &gt;A 80 /L 80  is derived. 
     [Display Control Method] 
     With reference to  FIGS. 1 ,  3 , and  6 , a display control method will be described that the display control section  100  performs.  FIG. 6  is a flowchart depicting the display control method. Steps S 210 , S 220 , S 240 -S 270 , S 290 , and S 300  are the same in processing as Steps S 10 , S 20 , S 40 -S 70 , S 90 , and S 100 , respectively, in  FIG. 3 . Therefore, description of them is omitted. 
     At Step S 230 , the display control section  100  determines based on the position of the touch point the page flip start point and the page flip direction. Further, at Step S 280 , the display control section  100  changes the display format of the pages P (the eBook  20 ) to the two-page spread format. At Step S 310 , the display control section  100  reverses the page flip direction and displays to-be-flipped pages P on an enlarged scale. Then, the routine proceeds to Step S 240 . 
     As has been described with reference to  FIGS. 1 ,  5 , ad  6 , in the second embodiment, to-be-flipped pages P is displayed on an enlarged scale (see  FIGS. 5A-5C ) each time the touch panel  220  detects a reversal of the travel direction of the touch point. As a result, page visibility and efficiency of page search for a target page P can be enhanced further. Furthermore, as a result of display on an enlarged scale, the amount of page flip per unit amount of travel of the touch point can be deceased. This can further enhance page visibility and efficiency of page search for a target page P . Besides, the second embodiment can achieve the same advantages as those in the first embodiment. 
     The display control section  100  may change the amount of page flip per unit time each time the travel direction of the touch point changes. Detailed description will be made in the following third embodiment. 
     Third Embodiment 
     [Outline] 
     With reference to  FIG. 1 , description will be made about the display device  10  according to the third embodiment of the present disclosure. The display device  10  according to the third embodiment has the same configuration as the display device  10  shown in  FIG. 1 . 
     The display control section  100  changes the amount of page flip per unit time (hereinafter referred to as “speed”) each time the touch panel  220  detects a change (a reversal in the third embodiment) in the travel direction of the touch point. As a result, page visibility and efficiency of page search for a target page P can be enhanced. 
     [Details of Page Flip Control] 
     Page flip control (speed control) will be described in detail with reference to  FIGS. 1 ,  4 , and  7 . The eBook  20  will be discussed as an example in the third embodiment.  FIGS. 7A-7D  are diagrams for explaining page flip control that the display device  10  performs. 
     As shown in  FIG. 4 , the display control section  100  causes the display section  210  to display the eBook  20  in the upright, closed state. The display control section  100  determines a page serving as a page flip start point in the pages P according to the position of the touch point (e.g., a point D 11 ) in the front edge F of the eBook  20 . The page determination scheme is the same as that in the second embodiment described with reference to  FIG. 4 . Therefore, description thereof is omitted. 
     As shown in  FIG. 7A , when the touch panel  220  detects the touch point moving from the point D 21  toward the point D 23 , the display control section  100  responsively flips pages P in the direction (see an arrow C 1 ) corresponding to the travel direction of the touch point at a speed V 10 . 
     Next, the user reverses the travel direction of the finger in touch with the display surface at the point D 23 . 
     As shown in  FIG. 7B , in response to the reversal of the travel direction of the touch point at the point D 23  that the touch panel  220  detects, the display control section  100  reverses the page flip direction (see the arrow C 2 ) and flips pages P at a speed V 20 . The speed V 20  is smaller than the speed V 10 . 
     Next, the user reverses the travel direction of the finger in touch with the display surface at the point D 25 . 
     As shown in  FIG. 7C , in response to the reversal of the travel direction of the touch point at the point D 25  that the touch panel  220  detects, the display control section  100  reverses the page flip direction (see the arrow C 1 ) and flips pages P at a speed V 30 . The speed V 30  is smaller than the speed V 20 . 
     Next, the user removes the finger in touch with the display surface at the point D 27  therefrom. 
     As shown in  FIG. 7D , when the touch panel  220  detects transition from the touch point detecting state to the touch point non-detecting state at the point D 27 , the display control section  100  stops page flip and changes the display format of the pages P (the eBook  20 ). For example, the display control section  100  changes the display format of the pages P (the eBook  20 ) from the upright format to the two-page spread format. 
     Accordingly, when the user only removes the finger from the display surface upon discovery of the target page P, the page flip can be stopped, and the target page P can be displayed in the two-page spread format. In other words, the user can change the page display format by a simple operation. 
     Furthermore, for example, when the touch panel  220  detects a predetermined operation (e.g., double tap) in a state in which pages P are displayed in the two-page spread format, the display control section  100  may change the page display format from the two-page spread format to the upright format (see  FIG. 4 ). 
     [Speed (Amount of Page Flip Per Unit Time)] 
     The display control section  100  can decrease the speed at a predetermined rate or an arbitrary rate. In the case of the decrease at the predetermined rate, for example, the decrease rate is set to 0.5 in  FIGS. 7A-7C . Accordingly, the speed V 20  is V 10 ×0.5. Also, the speed V 30  is V 20 ×0.5 (=V 10 ×0.5×0.5). 
     [Amount of Page Flip] 
     The display control section  100  determines the amount of page flip according to the amount of travel of the touch point. Given that G is an amount of page flip per unit amount of travel of the touch point. In the third embodiment, the amount G of page flip per unit amount of travel of the touch point is fixed regardless of a change in the travel direction of the touch point. Given also that L is an amount of travel of the touch point. Accordingly, an amount U of page flip is expressed by G×L. 
     With reference to  FIGS. 7A-7C , a specific example will be described now. In  FIGS. 7A-7C , the amount L of travel of the touch point is denoted by L 90 , L 100 , and L 110 , respectively. Accordingly, the amounts U of page flip in  FIGS. 7A-7C  are expressed by G×L 90 , G×L 100 , and G×L 110 , respectively. 
     [Display Control Method] 
     With reference to  FIGS. 1 ,  6 , and  8 , a display control method will be described that the display control section  100  performs.  FIG. 8  is a flowchart depicting the display control method. Steps S 410 -S 500  are the same in processing as Steps S 210 -S 300  in  FIG. 6 . Therefore, description of them is omitted. At Step S 510 , the display control section  100  reverses the page flip direction and decreases the amount of page flip per unit time (speed). Then, the routine returns to Step S 440 . 
     As has been described with reference to  FIGS. 1 ,  7 , and  8 , in the third embodiment, the page flip speed is decreased (see  FIGS. 7A-7C ) each time the touch panel  220  detects a change in the travel direction of the touch point. As a result, page visibility and efficiency of page search for a target page P can be enhanced. Besides, the same advantages as those in the first embodiment can be achieved in the third embodiment. 
     Fourth Embodiment 
     With reference to  FIGS. 9 and 10 , description will be made about an image forming apparatus  500  according to the fourth embodiment of the present disclosure.  FIG. 9  is a block diagram showing the image forming apparatus  500 .  FIG. 10  is a schematic cross sectional view explaining the image forming apparatus  500 . 
     The image forming apparatus  500  includes a control section  110 , a storage section  120 , an original document feed section  230 , an image reading section  240 , the touch panel  220 , the display section  210 , a paper feed section  250 , a conveyance section  260 , an image forming section  270 , and a fixing section  280 . The storage section  120  incudes a main storage device (e.g., a semiconductor memory) and an auxiliary storage device (e.g., a semiconductor memory or a hard disk drive). 
     The control section  110  controls the entire image forming apparatus  500 . Specifically, the control section  110  executes a computer program stored in the storage section  120  to control the original document feed section  230 , the image reading section  240 , the touch panel  220 , the display section  210 , the paper feed section  250 , the conveyance section  260 , the image forming section  270 , and the fixing section  280 . The control section  110  may be a central processing unit (CPU), for example. The touch panel  220  is arranged on the display surface of the display section  210 , for example. 
     The control section  110  also functions as the display control section  100  in the first, second, or third embodiment. Accordingly, the control section  110 , the display section  210 , and the touch panel  220  constitute the display device  10  of any of the first to third embodiments. The storage section  120  stores image data of a plurality of pages P (an eBook  20 ). 
     The original document feed section  230  feeds an original document to the image reading section  240 . The image reading section  240  reads an image of the original document to generate image data. The paper feed section  250  includes a paper feed cassette  62  and a manual feed tray  64 . Sheets T are to be loaded on the paper feed cassette  62 . A sheet T is sent out from the paper feed cassette  62  or the manual feed tray  64  to the conveyance section  260 . These sheets T may be plain paper, recycled paper, thin paper, thick paper, an overhead projector (OHP) sheet, or the like. 
     The conveyance section  260  conveys the sheet T to the image forming section  270 . The image forming section  270  includes a photosensitive drum  81 , a charger  82 , an exposure section  83 , a flip section  84 , a transfer section  85 , a cleaning section  86 , and a static eliminating section  87 . Specifically, the image forming section  270  forms (prints) the image on the sheet T as follows. 
     The charger  82  electrostatically charges the surface of the photosensitive drum  81 . The exposure section  83  irradiates the surface of the photosensitive drum  81  with light based on the image data generated by the original document reading section  240 . As a result, an electrostatic latent image corresponding to the image data is formed on the surface of the photosensitive drum  81 . 
     The development section  84  develops the electrostatic latent image formed on the surface of the photosensitive drum  81  to form a toner image thereon. When the sheet is supplied between the photosensitive drum  81  and the transfer section  85 , the transfer section  85  transfers the toner image to the sheet T. 
     The sheet T to which the toner image is transferred is conveyed to the fixing section  280 . The fixing section  280  applies heat and pressure to the sheet T to fix the toner image to the sheet T. Then, an ejection roller pair  72  ejects the sheet T onto an exit tray  74 . The cleaning section  86  removes toner remaining on the surface of the photosensitive drum  81 . The static eliminating section  87  removes residual charges on the surface of the photosensitive drum  81 . 
     It should be noted that the present disclosure is not limited to the above embodiments and practicable in various manners within the scope not departing from the gist of the present disclosure. The following variations are possible, for example. 
     (1) The amount of page flip per unit time (speed) is fixed, while the amount of page flip per unit amount of travel of the touch point is changed in the second embodiment discussed with reference to  FIGS. 5A-5D . By contrast, the amount of page flip per unit amount of travel of the touch point time is fixed, while the amount of page flip per unit time (speed) is changed in the third embodiment discussed with reference to  FIGS. 7A-7D . However, both the amount of page flip per unit time (speed) and the amount of page flip per unit amount of travel of the touch point may be changed each time the travel direction of the touch point changes. For example, in the second embodiment, each time the travel direction of the touch point changes, the to-be-flipped pages P may be displayed on an enlarged scale, and the amount of page flip per unit amount of travel of the touch point (speed) may be changed. 
     (2) In the second embodiment described with reference to  FIGS. 5A-5D , the to-be-flipped pages PV of the pages P are displayed on an enlarged scale on the display section  210  each time the travel direction of the touch point changes. However, the to-be-enlarged target is not limited. For example, only a page PN under flip out of to-be-flipped pages PV may be displayed on an enlarged scale each time the travel direction of the touch point changes. The pages P under flip in  FIGS. 5A-5C  are pages PN 1 , PN 2 , and PN 3 , respectively. Besides, the pages PI other than the to-be-flipped pages are hidden, for example, in the second embodiment. However, the entire eBook  20  may be displayed on an enlarged scale each time the travel direction of the touch point changes. 
     (3) The present disclosure is applicable to fields of display devices, image forming apparatuses, and display control methods for display of a plurality of pages (e.g., an eBook or a set of images).