Abstract:
This display control device can effectively reduce power consumption while assuring visibility of a display area. A display control device ( 400 ) carries out display control for a display panel with an integrated touch panel and has: a touch operation information acquisition unit ( 410 ) that acquires touch operation information from the touch panel; a user operation information estimation unit ( 420 ) that estimates a region of interest, which is a region that a user is giving attention to, from the display region on the display panel on the basis of the touch operation information that is acquired; and a display control indication unit ( 440 ) that sets the brightness level for regions of non-interest, which is a region other than the region of interest estimated within the display region, lower than the set brightness level.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a display control apparatus, a display control method and a display control program for performing display control on a display panel of a touch panel. 
       BACKGROUND ART 
       [0002]    In recent years, portable terminals including a touch panel-incorporated display panel have been increasingly popular as mobile phones or portable information processing terminals or the like. Such portable terminals (hereinafter, simply referred to as “portable terminals”) use a power-driven display device such as organic EL (electro luminescence), LCD (liquid crystal display), or LED (light emitting diode) as a display panel. 
         [0003]    Many portable terminals are driven by battery and thus become inoperable when remaining battery power falls to or below a predetermined level. Therefore, reducing power consumption of such portable terminals is important to extend their continuously operable time. 
         [0004]    Power-saving techniques relating to a display panel of a portable terminal are disclosed, for example, in PTL 1 and PTL 2. 
         [0005]    The technique described in PTL 1 reduces, when no operation of a portable terminal is detected for a certain period of time, brightness of an overall display region (screen on a display panel) depending on the importance of an image being displayed. On the other hand, the technique described in PTL 2 identifies a region which is predicted to be continuously viewed by the user, based on the position of a cursor operated by the user, and reduces the brightness of regions other than the identified region. 
       CITATION LIST 
     Patent Literature 
       [0000]    
       
         PTL 1 
         Japanese Patent Application Laid-Open No. 2010-145582 
         PTL 2 
         Japanese Patent Application Laid-Open No. 2011-101296 
       
     
       SUMMARY OF INVENTION 
     Technical Problem 
       [0010]    The technique disclosed in PTL 1, however, cannot reduce the brightness while operation is in progress. In the technique disclosed in PTL 2, the region being viewed by the user may not coincide with the position of a cursor, which may cause the brightness of the region viewed by the user to decrease, compromising user comfort (hereinafter, referred to as “viewability of display region”) when viewing the display region. That is, the techniques according to the related art have a problem in that it is difficult to effectively reduce power consumption while securing viewability of the display region. 
         [0011]    A reduction in power consumption is required not only for display panels of portable terminals but also for display panels of various other electronic devices. Therefore, there is a demand for a technique capable of effectively reducing power consumption while securing viewability of a display region for display panels of various electronic devices. 
         [0012]    An object of the present invention is to provide a display control apparatus, a display control method and a display control program capable of effectively reducing power consumption while securing viewability of a display region. 
       Solution to Problem 
       [0013]    A display control apparatus according to an aspect of the present invention is a display control apparatus that performs display control on a touch-panel-incorporated display panel, the display control apparatus including: a touch operation information acquiring section that acquires touch operation information from the touch panel; a user operation information estimation section that estimates a target region from a display region of the display panel based on the acquired touch operation information, the target region being a region of interest of a user; and a display control instruction section that sets a brightness level of a non-target region to be lower than a set brightness level, the non-target region being a region other than the target region estimated in the display region. 
         [0014]    A display control method according to an aspect of the present invention is a display control method for performing display control on a touch-panel-incorporated display panel, the method including: acquiring touch operation information from the touch panel; estimating a target region from a display region of the display panel based on the acquired touch operation information, the target region being a region of interest of a user; and setting a brightness level of a non-target region to be lower than a set brightness level, the non-target region being a region other than the target region estimated in the display region. 
         [0015]    A display control program according to an aspect of the present invention is a program that causes a computer that performs display control on a touch-panel-incorporated display panel to function as: a touch operation information acquiring section that acquires touch operation information from the touch panel; a user operation information estimation section that estimates a target region from a display region of the display panel based on the acquired touch operation information, the target region being a region of interest of a user; and a display control instruction section that sets a brightness level of a non-target region to be lower than a set brightness level, the non-target region being a region other than the target region estimated in the display region. 
       Advantageous Effect of the Invention 
       [0016]    According to the present invention, it is possible to effectively reduce power consumption while securing viewability of a display region. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]      FIG. 1  is a block diagram illustrating an example of a configuration of a display control apparatus according to Embodiment 1 of the present invention; 
           [0018]      FIG. 2  is a block diagram illustrating an example of a configuration of a display apparatus including a display control apparatus according to Embodiment 2 of the present invention; 
           [0019]      FIG. 3  is a flowchart illustrating an example of operation of the display apparatus according to Embodiment 2 of the present invention; 
           [0020]      FIG. 4  illustrates an example of a touch region and a non-target region in Embodiment 2 of the present invention; 
           [0021]      FIG. 5  illustrates another example of the touch region and non-target region in Embodiment 2 of the present invention; 
           [0022]      FIG. 6  is a block diagram illustrating an example of a configuration of a display apparatus including a display control apparatus according to Embodiment 3 of the present invention; 
           [0023]      FIG. 7  illustrates an example of a configuration of a display region formed of a plurality of divided regions according to Embodiment 3 of the present invention; 
           [0024]      FIG. 8  is a flowchart illustrating an example of operation of the display apparatus according to Embodiment 3 of the present invention; 
           [0025]      FIG. 9  illustrates an example of a touch region and a non-target region according to Embodiment 3 of the present invention; 
           [0026]      FIG. 10  is a block diagram illustrating an example of a configuration of a display apparatus including a display control apparatus according to Embodiment 4 of the present invention; 
           [0027]      FIG. 11  is a flowchart illustrating an example of operation of the display apparatus according to Embodiment 4 of the present invention; and 
           [0028]      FIG. 12  illustrates an example of a touch region and non-target region according to Embodiment 4 of the present invention. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0029]    Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. 
       Embodiment 1 
       [0030]    Embodiment 1 of the present invention is an example of a basic mode of the present invention. 
         [0031]      FIG. 1  is a block diagram illustrating an example of a configuration of a display control apparatus according to the present embodiment. 
         [0032]    In  FIG. 1 , display control apparatus  400  is an apparatus that performs display control on a touch-panel-incorporated display panel (not shown), and includes touch operation information acquiring section (sensor information acquiring section)  410 , user operation information estimation section  420 , and display control instruction section  440 . 
         [0033]    Touch operation information acquiring section  410  acquires touch operation information (sensor information). 
         [0034]    User operation information estimation section  420  estimates a region of interest of a user (hereinafter, referred to as “target region”) from a display region of a display panel based on the acquired touch operation information. 
         [0035]    Display control instruction section  440  sets a brightness level of a region of the display region other than the estimated target region (hereinafter, referred to as “non-target region”) to be lower than a set brightness level. 
         [0036]    Display control apparatus  400  includes, for example, a CPU (central processing unit), a storage medium that stores a control program such as ROM (read only memory) and a working memory such as RAM (random access memory), which are not shown. In this case, the above-described functions of the respective sections are implemented by the CPU executing a control program. 
         [0037]    Such display control apparatus  400  can estimate a target region of a display region from touch operation information of a touch panel and reduce a brightness level of a non-target region. This allows display control apparatus  400  to effectively reduce power consumption while securing viewability of the display region. 
       Embodiment 2 
       [0038]    Embodiment 2 of the present invention is an example of a more specific mode of a case where the present invention is applied to a display apparatus provided with a touch-panel-incorporated display panel. 
         [0039]    &lt;Configuration of Display Apparatus&gt; 
         [0040]    First, a configuration of a display apparatus including a display control apparatus according to the present embodiment will be described. 
         [0041]      FIG. 2  is a block diagram illustrating an example of the configuration of the display apparatus including the display control apparatus according to the present embodiment. 
         [0042]    Display apparatus  100  shown in  FIG. 2  is a portable type electronic device including a mobile communication terminal such as a cellular phone, PDA (personal data assistant), digital camera, tablet, smartphone, and portable audio device, for example. Display apparatus  100  includes display panel (display section)  200 , touch panel (sensor)  300 , and display control apparatus  400 . 
         [0043]    Display panel  200  displays an image in a display region according to an image signal received from an image control section (not shown) of display apparatus  100 . Note that display panel  200  can control the brightness level for each region obtained by dividing the display region of display panel  200  (e.g., for each pixel). More specifically, display panel  200  is, for example, organic EL display, LCD or LED display. Display panel  200  in the present embodiment will be described using an organic EL display as an example. 
         [0044]    In the present embodiment, a brightness level is assumed to be a ratio of an actual brightness value to value 100 when the maximum brightness of an image displayed on display panel  200  is assumed to be 100. A set brightness level means a brightness level when display control apparatus  400  does not function. That is, the set brightness level is any one of the brightness level set beforehand by a user, brightness level set as a default value in display control instruction section  440  and brightness level of a target region, for example. 
         [0045]    Touch panel  300  outputs information indicating contents of an operation conducted on touch panel  300  (hereinafter referred to as “touch operation information”). 
         [0046]    In the present embodiment, an assumption is made that touch panel  300  is provided in a display region of display panel  200  (hereinafter simply referred to as “display region”). Touch panel  300  outputs a detection signal indicating at which position contact is sensed (hereinafter referred to as “touch operation signal” (sensor signal)) as the touch operation information. 
         [0047]    Display control apparatus  400  is an apparatus that performs display control (that is, display control on display panel  200 ) of display apparatus  100 . Display control apparatus  400  includes touch operation information acquiring section  410 , user operation information estimation section  420 , display control determining section  430 , and display control instruction section  440 . 
         [0048]    Touch operation information acquiring section  410  acquires touch operation information from touch panel  300 . 
         [0049]    More specifically, touch operation information acquiring section  410  receives a touch operation signal outputted from touch panel  300  as input and converts a position at which contact is sensed to information indicating the position using coordinates of a display region displayed by display panel  200  (hereinafter referred to as “contact point information”). 
         [0050]    Touch operation information acquiring section  410  outputs the acquired contact point information to user operation information estimation section  420 . 
         [0051]    User operation information estimation section  420  estimates a target region from the display region based on the acquired touch operation information. In other words, user operation information estimation section  420  estimates a region of the display region other than the estimated target region or a display region of display panel  200  which is not interest of the user as a non-target region. 
         [0052]    More specifically, user operation information estimation section  420  acquires a region of the display region where the user is touching with a finger (hereinafter referred to as “touch region”) from the contact point information received from touch operation information acquiring section  410 . User operation information estimation section  420  then estimates a target region from the acquired touch region. 
         [0053]    User operation information estimation section  420  outputs information indicating the estimated target region (in other words, information indicating the estimated non-target region) (hereinafter referred to as “region information”) to display control determining section  430 . 
         [0054]    Display control determining section  430  determines a brightness level of each region of the display region according to whether the region is a target region or a non-target region. 
         [0055]    More specifically, display control determining section  430  determines a brightness level of each region of the display region based on the region information inputted from user operation information estimation section  420  so that the non-target region has a brightness level lower than a set brightness level. 
         [0056]    Display control determining section  430  outputs information indicating the determined brightness level of each region (hereinafter referred to as “brightness information”) to display control instruction section  440 . 
         [0057]    Note that “determining the brightness level” is a concept including determining the ratio of the brightness level to be actually outputted to the set brightness level (output ratio with respect to the brightness value indicated by an image signal, hereinafter referred to as “level ratio”). That is, the brightness information is information specifying a level ratio. Setting a lower brightness level than the set brightness level includes a case where the level ratio outputted as brightness information has a value less than 1. 
         [0058]    Display control instruction section  440  sets the brightness level of the non-target region to be lower than the set brightness level. More specifically, display control instruction section  440  outputs, to display apparatus  100  (that is, display panel  200 ), a control signal for instructing each region of the display region to be displayed at a determined brightness level based on brightness information received from display control determining section  430 . 
         [0059]    In the present embodiment, a control signal outputted from display control instruction section  440  is a signal for instructing each pixel of, for example, an organic EL to be outputted at the above-described level ratio. 
         [0060]    Display apparatus  100  includes, for example, a CPU and a storage medium such as ROM that stores a control program and a working memory such as RAM, which are not shown. In this case, the above-described functions of the respective sections are implemented by the CPU executing a control program. 
         [0061]    Such display apparatus  100  can estimate a target region of the display region from the user&#39;s operation on display panel  200  and lower the brightness level of the non-target region. 
         [0062]    The non-target region is a so-called region not viewable or unnecessary to the user. For this reason, even when the brightness level of the display of the non-target region is lowered, comfort with which the user views the display region is hardly lost. Thus, display apparatus  100  can effectively reduce power consumption while securing viewability of the display region. 
         [0063]    The description of the configuration of display apparatus  100  has been given thus far. 
         [0064]    &lt;Operation of Display Apparatus&gt; 
         [0065]    Next, operation of display apparatus  100  will be described. 
         [0066]      FIG. 3  is a flowchart illustrating an example of operation of display apparatus  100 . 
         [0067]    First, in step S 1100 , touch operation information acquiring section  410  receives a touch operation signal from touch panel  300 . 
         [0068]    In step S 1200 , touch operation information acquiring section  410  converts the touch operation signal to contact point information through coordinate transformation processing. 
         [0069]    In step S 1300 , user operation information estimation section  420  acquires a touch region from the contact point information. 
         [0070]    In the present embodiment, an assumption is made that user operation information estimation section  420  acquires each of regions having a predetermined or greater area of continuous closed regions from which contact is detected as a touch region. 
         [0071]    For example, let us suppose that the user touches the touch panel with two fingers, the forefinger and thumb. In this case, the region where the forefinger contacts the touch panel and the region where the thumb contacts the touch panel are acquired as touch regions, respectively. 
         [0072]    Such contact states are detected when, for example, the user attempts to perform an operation of displaying an enlarged view of an image in the region between the two fingers touching the display region (hereinafter referred to as “pinch-out operation” (enlarging operation)). Such a pinch-out operation includes touching the touch panel with two fingers, and sliding the two fingers to outside in such a way that the distance between the fingers expands. 
         [0073]    User operation information estimation section  420  may substitute a region having a predetermined or greater area of the continuous closed region from which contact is detected with a region with a simple shape such as a circle of a predetermined size and acquire the substituted region as a touch region. In this case, the touch region can be simply defined by, for example, center coordinates and radius and the scale of area of the touch region can be simply determined by the radius. That is, the load of the subsequent processing can be reduced. 
         [0074]    When no contact with the touch panel is detected, the coordinate transformation processing in step S 1200  and the touch region acquiring processing in step S 1300  are not particularly performed. 
         [0075]    In step S 1400 , user operation information estimation section  420  determines from the acquired touch region, whether or not a multitouch state is in place. The “multitouch” here is a state in which there are two or more touch regions and, for example, a state in which two fingers are touching the touch panel. 
         [0076]    When a multitouch state is in place (S 1400 : YES), user operation information estimation section  420  moves to step S 1500 . When a multitouch state is not in place (S 1400 : NO), user operation information estimation section  420  moves to step S 2400  which will be described later. 
         [0077]    In step S 1500 , user operation information estimation section  420  assumes the regions having the largest area and the second largest area of the touch region as a first touch region and a second touch region, respectively. User operation information estimation section  420  then measures a distance between the first touch region and the second touch region (hereinafter referred to as “distance between two points”). The distance between two points is, for example, a distance between a point in the first touch region closest to the second touch region and a point in the second touch region closest to the first touch region. 
         [0078]    In step S 1600 , user operation information estimation section  420  estimates whether or not the user is performing a pinch-out operation. In the case of a pinch-out operation, two fingers normally start to move from a position where the distance between two points is short and then slide. Therefore, based on, for example, whether or not the distance between the two points is equal to or less than a predetermined threshold, user operation information estimation section  420  estimates whether or not the user is performing a pinch-out operation. 
         [0079]    When the user is performing a pinch-out operation (S 1600 : YES), user operation information estimation section  420  moves to step S 1700 . When the user is not performing a pinch-out operation (S 1600 : NO), user operation information estimation section  420  moves to step S 2400  which will be described later. 
         [0080]    In step S 1700 , user operation information estimation section  420  estimates the region between the first touch region and the second touch region as a region to be enlarged. 
         [0081]    In step S 1800 , user operation information estimation section  420  estimates the region to be enlarged as a target region, estimates a region of the display region other than the region to be enlarged as a non-target region and moves to step S 1900 . 
         [0082]    That is, upon determining that the user is performing a pinch-out operation, user operation information estimation section  420  estimates the region between a plurality of finger touch regions during a pinch-out operation as the target region. 
         [0083]      FIG. 4  illustrates an example of touch regions and a non-target region estimated based on the touch regions. Here, the user&#39;s fingers are shown by dotted lines together. 
         [0084]    The example of display region  510  shown in  FIG. 4  shows that forefinger  521  and thumb  522  are touching the display region. Here, an assumption is made that the region of forefinger  521  contacting display region  510  is first touch region  531  and the region of thumb  522  contacting display region  510  is second touch region  532 . Let us suppose that a point of the first touch region closest to the second touch region is first point  541  and a point of the second touch region closest to the first touch region is second point  542 . In this case, the distance between the two points is a length of line segment  543  connecting first point  541  and second point  542 . 
         [0085]    When the length of this line segment  543  is less than the predetermined threshold, user operation information estimation section  420  determines that the pinch-out operation is in progress (S 1600 : YES). User operation information estimation section  420  then assumes the region between first touch region  531  and second touch region  532  as target region  551  and assumes the other regions as non-target regions  552 . 
         [0086]    Here, a case is illustrated where non-target regions  552  are estimated in such a way that boundaries  553  between target region  551  and non-target regions  552  are straight lines parallel to a top end and a bottom end of display region  510 . Such estimation is suitable for horizontally written text information, for example. Such an aspect of boundaries  553  is not limited to this. 
         [0087]      FIG. 5  illustrates another example of the non-target regions, which corresponds to  FIG. 4 . Parts corresponding to those in  FIG. 4  are assigned the same reference numerals and description thereof will be omitted. 
         [0088]    As shown in  FIG. 5 , user operation information estimation section  420  estimates non-target regions  552 , for example, in such a way that boundaries  553  between target region  551  and non-target region  552  become straight lines orthogonal to line segment  543  connecting first point  541  and second point  542 . 
         [0089]    Such estimation is suitable for an image such as a map. When a region to be enlarged is band-shaped, the user often performs multitouch as if the user nips this band-shaped region. The direction in which forefinger  521  and thumb  522  extend is substantially orthogonal to line segment  543 . Therefore, such estimation allows estimation of a target region with still higher accuracy. 
         [0090]    Note that boundaries  553  between target region  551  and non-target regions  552  need not always be straight lines, and for example, boundary  553  may be a circle, the diameter of which may be line segment  543  connecting first point  541  and second point  542 . Boundaries  553  between target region  551  and non-target regions  552  may also be similar to display region  510  including first point  541  and second point  542  (here, rectangle) or the like. 
         [0091]    In step S 1900 , display control determining section  430  determines a brightness level of each part so that the brightness level of the non-target regions becomes lower than a set reference level. More specifically, display control determining section  430  determines a level ratio of each part so that the brightness level of the non-target regions becomes lower than a set reference level. 
         [0092]    For example, display control determining section  430  determines the level ratio of the target region to 1 and determines the level ratio of the touch region of the non-target regions to 0. Display control determining section  430  determines the level ratio of the remaining region other than the touch regions of the target region and the non-target regions (hereinafter referred to as “remaining region”) in the display region to be 0.5. In this way, uniformly determining the brightness level for each region using the level ratio makes it possible to determine a brightness level of each part with a smaller processing load. 
         [0093]    In step S 2000 , display control instruction section  440  generates a control signal to achieve the brightness level determined in step S 1900  and outputs the control signal to display panel  200 . The control signal has a content in which a level ratio is specified per region or per pixel, for example. 
         [0094]    In step S 2100 , user operation information estimation section  420  determines whether or not the touch panel operation by the user has ended. The end of the touch panel operation is that, for example, the user who has been performing the pinch-out operation removes his/her two fingers from the touch panel, and this can be determined based on whether the area of the touch region becomes 0 or not. 
         [0095]    When the touch panel operation by the user ends (S 2100 : YES), user operation information estimation section  420  moves to step S 2200 . When the touch panel operation by the user has not ended or the touch panel operation has not been performed from the beginning (S 2100 : NO), user operation information estimation section  420  moves to step S 2400  which will be described later. 
         [0096]    In step S 2200 , display control determining section  430  determines the brightness level of each part so that the brightness level of the non-target regions returns to the set brightness level. 
         [0097]    For example, display control determining section  430  determines all level ratios of the target region and non-target regions (touch region and remaining region) to 1. 
         [0098]    In step S 2300 , display control instruction section  440  generates a control signal to achieve the brightness level determined in step S 2200  and outputs the control signal to display panel  200 . 
         [0099]    In step S 2400 , user operation information estimation section  420  determines whether or not an end of the processing is instructed through a user operation or the like. 
         [0100]    When the end of the processing has not been instructed (S 2400 : NO), user operation information estimation section  420  returns to step S 1100 . When the end of the processing has been instructed (S 2400 : YES), user operation information estimation section  420  ends a series of processes. 
         [0101]    Through such an operation, display apparatus  100  can monitor the user&#39;s operation on display panel  200 . When the user&#39;s operation is a pinch-out operation, display apparatus  100  successively estimates regions other than a region to be enlarged as non-target regions and can thereby lower the brightness level of the non-target regions. 
         [0102]    Note that the user actually often places his/her fingers at an edge of a region to be enlarged, that is, inside the region to be enlarged. That is, the actual region to be enlarged is often a region including two touch regions. However, since the region where the finger is contacting is hidden by the fingers, the region is not viewable to the user. Therefore, as described above, even when the region between the two touch regions is estimated as a region to be enlarged and the regions where the fingers are contacting are estimated as the non-target regions, viewability of the display region is less likely to be lost. 
         [0103]    Display apparatus  100  may also estimate a region including two touch regions as regions to be enlarged. In this case, display apparatus  100  may estimate a region between a point of the first touch region farthest from the second touch region and a point of the second touch region farthest from the first touch region as a region to be enlarged. 
         [0104]    Display apparatus  100  may gradually lower the brightness level of the non-target region in accordance with the progress of a pinch-out operation or an elapsed time from the operation start. 
         [0105]    When the operation ends, display apparatus  100  need not always return the brightness level to the original level. 
         [0106]    As described above, display control apparatus  400  according to the present embodiment estimates the target region of the display region from the touch operation information of touch panel  300  and can thereby lower the brightness level of the non-target regions. Thus, display control apparatus  400  can effectively lower power consumption while securing viewability of the display region. 
         [0107]    Note that there may be a case where display apparatus  100  uses an LCD or LED or the like and display apparatus  100  is provided with display control apparatus  400  as a backlight. In such case, display apparatus  100  may be configured to change the brightness level through display control instruction section  440 . In this case, for example, display control instruction section  440  acquires an image signal inputted to display apparatus  100  and performs processing of changing the brightness level of each part in accordance with a determined level ratio. Display control instruction section  440  then inputs a processed image signal to display apparatus  100  as a substitute for the image signal. 
       Embodiment 3 
       [0108]    Embodiment 3 of the present invention is an example of specific modes suitable when the display region is made up of a plurality of divided regions. 
         [0109]    &lt;Configuration of Display Apparatus&gt; 
         [0110]      FIG. 6  is a block diagram illustrating an example of a configuration of a display apparatus including a display control apparatus according to the present embodiment, which corresponds to  FIG. 2  of Embodiment 2. Parts identical to those in  FIG. 2  are assigned the same reference numerals and description thereof will be omitted. 
         [0111]    In  FIG. 6 , display control apparatus  400   a  of display apparatus  100   a  further includes layout information storage section  450   a  in addition to the configuration of  FIG. 2 . Display control apparatus  400   a  includes user operation information estimation section  420   a  instead of user operation information estimation section  420  of  FIG. 2 . 
         [0112]    Layout information storage section  450   a  stores layout information indicating a layout of divided regions obtained by dividing a display region displayed by display panel  200 . The layout of the divided regions is defined by relative coordinates of the divided regions with respect to the entire display region, for example. The layout information is acquired, for example, by an image analysis section (not shown) analyzing an image signal or signal added to an image signal or accessing a server that delivers an image signal. 
         [0113]    &lt;Configuration of Display Region&gt; 
         [0114]      FIG. 7  illustrates an example of a configuration of the display region formed of a plurality of divided regions. 
         [0115]    As shown in  FIG. 7 , display region  510  is composed of, for example, four divided regions: first to fourth divided region  511  to  514 . Let us suppose that display region  510  is a web page displayed by a web browser. First divided region  511  is, for example, a region that displays a title of the web page. Second divided region  512  is, for example, a region that displays a main region of the web page. Third divided region  513  is, for example, a region that displays information on a table of contents. Fourth divided region  514  is, for example, a region that displays an advertisement. 
         [0116]    User operation information estimation section  420   a  in  FIG. 6  estimates a target region using each of the divided regions as a unit. More specifically, upon determining that the user is performing a pinch-out operation, user operation information estimation section  420   a  estimates a region between touch regions of a plurality of fingers out of the divided regions in which the pinch-out operation is in progress as a target region. In other words, user operation information estimation section  420   a  refers to the layout information stored in layout information storage section  450   a  and assumes the divided regions not including the line segment connecting the touch regions of the two fingers in the pinch-out operation as a non-target regions. 
         [0117]    More specifically, for divided regions including at least part of the line segment connecting the above-described first and second points, user operation information estimation section  420   a  determines the target region and non-target regions as in the case of Embodiment 2. User operation information estimation section  420   a  determines the divided regions not including the line segment connecting the above-described first and second points as non-target regions. 
         [0118]    &lt;Operation of Display Apparatus&gt; 
         [0119]      FIG. 8  is a flowchart illustrating an example of operation of display apparatus  100   a , which corresponds to  FIG. 3  of Embodiment 1. Parts identical to those in  FIG. 3  are assigned the same reference numerals and description thereof will be omitted. 
         [0120]    When the user is performing a pinch-out operation (S 1600 : YES), user operation information estimation section  420   a  moves to step S 1710   a.    
         [0121]    In step S 1710   a , user operation information estimation section  420   a  acquires the line segment connecting the first touch region and the second touch region as a line segment to be enlarged. 
         [0122]    In step S 1720   a , user operation information estimation section  420   a  estimates, with reference to layout information, a region of the divided regions including at least part of the line segment to be enlarged between the two touch regions as a region to be enlarged. 
         [0123]    User operation information estimation section  420   a  then moves to step S 1800 . That is, user operation information estimation section  420   a  excludes the region not including the line segment to be enlarged from the estimation target of the region to be enlarged. 
         [0124]    &lt;Touch Region and Non-Target Region&gt; 
         [0125]      FIG. 9  illustrates an example of touch regions and non-target regions, which corresponds to  FIG. 7  and  FIG. 4  of Embodiment 1. Parts corresponding to those in  FIG. 7  and  FIG. 4  are assigned the same reference numerals and description thereof will be omitted. 
         [0126]    As shown in  FIG. 9 , suppose line segment (line segment to be enlarged)  543  connecting first point  541  and second point  542  is included in second divided region  512 . In this case, user operation information estimation section  420   a  assumes region  561  of second divided region  512  between first touch region  531  and second touch region  532  as a target region. 
         [0127]    User operation information estimation section  420   a  assumes regions  562  of second divided region  512  other than region  561  as non-target regions. User operation information estimation section  420   a  assumes first, third and fourth divided regions  511 ,  513  and  514  as non-target regions. 
         [0128]    As a result, only region  561  of second divided region  512  has a set brightness level and other regions have lower brightness levels. 
         [0129]    When  FIG. 9  is compared with  FIG. 4 , the non-target region in  FIG. 9  has a greater area by a portion corresponding to the right side region (part of third divided region  513 ) of region  561 , which clearly shows that a high power-saving effect is achieved. 
         [0130]    Thus, display apparatus  100   a  according to the present embodiment assumes the divided regions not including the line segment to be enlarged in a pinch-out operation as non-target regions. 
         [0131]    In the case of a screen such as a web page where each divided region has complete information, the user normally does not watch regions other than the divided region subject to a pinch-out operation. Therefore, lowering the brightness level of the divided regions not including the line segment to be enlarged is less likely to impair the comfort for the user viewing the screen. That is, display apparatus  100   a  can more effectively lower power consumption while securing viewability of the display region. 
         [0132]    Note that in Embodiment 2 and Embodiment 3 of the present invention described so far, only the pinch-out operation is assumed to be a target for estimation of non-target regions and a reduction of the brightness level, but the target for estimation of non-target regions and a reduction of the brightness level is not limited to this. 
         [0133]    For example, the display control apparatus according to the present invention may also designate a pinch-in operation that displays a reduced view of an image or a flick operation that slides a screen vertically and horizontally as a target for estimation of non-target regions and a reduction of the brightness level. In the latter case, the display control apparatus designates a region which, for example, disappears from a display range by sliding the screen as non-target regions. 
       Embodiment 4 
       [0134]    Embodiment 4 of the present invention is an example of a specific mode when a region hidden by the user&#39;s fingers is taken into consideration. 
         [0135]    &lt;Configuration of Display Apparatus&gt; 
         [0136]      FIG. 10  is a block diagram illustrating an example of a configuration of a display apparatus including a display control apparatus according to the present embodiment, which corresponds to  FIG. 2  of Embodiment 2. Parts identical to those in  FIG. 2  are assigned the same reference numerals and description thereof will be omitted. 
         [0137]    In  FIG. 10 , display control apparatus  400   b  of display apparatus  100   b  further includes user information storage section  460   b  in addition to the configuration of  FIG. 2 . Display control apparatus  400   b  includes user operation information estimation section  420   b  instead of user operation information estimation section  420  of  FIG. 2 . 
         [0138]    User information storage section  460   b  stores user information indicating information relating to a finger position during an operation by the user. 
         [0139]    In the present embodiment, the user information is information indicating whether the user is right-handed or left-handed and is assumed to be set beforehand, for example, through an operation by the user. 
         [0140]    User operation information estimation section  420   b  estimates a region hidden by a user&#39;s finger (hereinafter referred to as “hidden region”) using the user information stored in user information storage section  460   b . User operation information estimation section  420   b  then designates the estimated hidden region as a non-target region. 
         [0141]    An assumption is made that user operation information estimation section  420   b  stores an estimation rule for estimating the hidden region from the user information beforehand. 
         [0142]    In the present embodiment, when the user is right-handed, the estimation rule is assumed to include a rule that a touch region and a region away from a right end point of the touch region in the rightward direction by a predetermined distance or more as hidden regions. On the other hand, when the user is left-handed, the estimation rule is assumed to include a rule that a touch region and a region away from a left end point of the touch region in the leftward direction by a predetermined distance or more as hidden regions. 
         [0143]    A right-handed user normally holds display apparatus  100   b  by the left hand and performs a touch panel operation by the right hand. For this reason, in the case of a right-handed user, most of the region slightly distanced rightward from the touch region of the finger is hidden by the back of the right hand. 
         [0144]    On the other hand, a left-handed user normally holds display apparatus  100   b  by the left hand and performs a touch panel operation by the left hand. For this reason, in the case of a left-handed user, most of the region slightly distanced leftward from the touch region of the finger is hidden by the back of the left hand. 
         [0145]    Therefore, the estimation rule used by user operation information estimation section  420   b  has the above-described rules. That is, user operation information estimation section  420   b  can estimate the hidden region accurately using the above-described user information and estimation rule. 
         [0146]    &lt;Operation of Display Apparatus&gt; 
         [0147]      FIG. 11  is a flowchart illustrating an example of operation of display apparatus  100   b , which corresponds to  FIG. 3  of Embodiment 1. Parts identical to those in  FIG. 3  are assigned the same reference numerals and description thereof will be omitted. 
         [0148]    User operation information estimation section  420   b  determines whether or not the user is performing an operation. When the user is not performing an operation (S 1400   b : NO), user operation information estimation section  420   b  moves to step S 2400 . On the other hand, when the user is performing an operation (S 1400   b : YES), user operation information estimation section  420   b  moves to step S 1730   b.    
         [0149]    In step S 1730   b , user operation information estimation section  420   b  refers to user information and estimates a hidden region from coordinates of the touch region based on the above-described estimation rule. 
         [0150]    In step S 1810   b , user operation information estimation section  420   b  estimates the hidden region as a non-target region, estimates regions of the display region other than the non-target region as a target region and moves to step S 1900 . 
         [0151]    &lt;Touch Region and Non-Target Region&gt; 
         [0152]      FIG. 12  illustrates an example of the touch region and non-target region, which corresponds to  FIG. 4  of Embodiment 1. Parts corresponding to those in  FIG. 4  are assigned the same reference numerals and description thereof will be omitted. 
         [0000]    Here, a case will be described where user information indicating that the user is right-handed is stored. 
         [0153]    As shown in  FIG. 12 , for example, user operation information estimation section  420   b  sets line  571  at predetermined distance d to the right from right end point  544  of first touch region  531  and second touch region  532  as a whole. User operation information estimation section  420   b  then designates the region on the left side of line  571  as target region  551  and the region on the right side of line  571  as a hidden region and non-target region  552 . This non-target region  552  is a portion covered with, for example, the back of the right hand as shown in  FIG. 12 . 
         [0154]    Thus, display apparatus  100   b  according to the present embodiment estimates a hidden part, designates the estimated hidden part as a non-target region and reduces the brightness level thereof. Thus, even when no pinch-out operation is performed, display apparatus  100   b  can effectively reduce power consumption while securing viewability of the display region. 
         [0155]    Note that display apparatus  100   b  may also estimate a hidden region with fingers from the touch region with higher accuracy. In this case, display apparatus  100   b  estimates the shape of the fingers based on the arrangement of the touch region and may designate the region covered with the estimated shape as the hidden region. In this case, display apparatus  100   b  may estimate, for each touch region, which finger is used to form the touch region from the shape, size and position thereof or the like and select the best from shape patterns of fingers stored beforehand. 
         [0156]    However, as described above, display apparatus  100   b  can reduce the processing load and more quickly lower the brightness level using the technique of estimating the touch region simply from the position of the hidden region. 
         [0157]    Display apparatus  100   b  may also use a combination of the technique of estimating regions other than the region to be enlarged as non-target regions and the technique of estimating divided regions not including a line segment to be enlarged as non-target regions described in Embodiment 2 and Embodiment 3. 
         [0158]    Embodiment 2 to Embodiment 4 of the present invention have been described with an example where a target region is estimated based on the touch panel touch operation information, but the target region estimation technique is not limited to this. 
         [0159]    For example, the display control apparatus according to the present invention may acquire a video captured using a camera, detect the direction of a line of sight of the user from the acquired video and estimate regions other than the region on which the user is gazing as non-target regions. 
         [0160]    That is, the display control apparatus may acquire information indicating a situation around the display region from a sensor that detects a situation around the display region by applying some scientific principles such as sensor information of an illumination sensor or the like. The display control apparatus may estimate a target region of the display region based on the acquired information indicating the situation around the display region. The information indicating the situation around the display region may include, for example, natural phenomenon, mechanical, electromagnetic, thermal, acoustic, chemical nature of artifact or spatial information or time information indicated by the information. 
         [0161]    The relationship between a touch region or operation type and a non-target region (hidden region) may differ depending on an environment in which the display control apparatus is used, for each user, for each image displayed, for each application by which an image is displayed, or for each display panel, for example. In this case, it is preferable that the display control apparatus according to each embodiment described above store a plurality of estimation rules for estimating a hidden region from touch operation information, layout information and user information and select an estimation rule that best meets an environment in which the apparatus is used. 
         [0162]    A display control apparatus according to this disclosure is a display control apparatus that performs display control on a touch-panel-incorporated display panel, the display control apparatus including: a touch operation information acquiring section that acquires touch operation information from the touch panel; a user operation information estimation section that estimates a target region from a display region of the display panel based on the acquired touch operation information, the target region being a region of interest of a user; and a display control instruction section that sets a brightness level of a non-target region to be lower than a set brightness level, the non-target region being a region other than the target region estimated in the display region. 
         [0163]    In the display control apparatus according to this disclosure, the set brightness level may be any one of a brightness level set beforehand by the user, a brightness level set as a default value in the display control instruction section and a brightness level of the target region. 
         [0164]    In the display control apparatus according to this disclosure, upon determining that the user is performing a pinch-out operation, the user operation information estimation section may estimate a region between a plurality of finger touch regions where the user is performing the pinch-out operation, as the target region. 
         [0165]    The display control apparatus to this disclosure may further include a layout information storage section that stores layout information indicating a layout of divided regions resulting from division of the display region, in which the user operation information estimation section may estimate the target region in units of the divided regions with reference to the layout information. 
         [0166]    In the display control apparatus according to this disclosure, the user operation information estimation section may estimate, upon determining that the user is performing a pinch-out operation, a region between the plurality of finger touch regions in the divided region where the user is performing the pinch-out operation, as the target region. 
         [0167]    The display control apparatus according to this disclosure may further include a user information storage section that stores user information indicating information relating to a finger position during operation by the user, in which the user operation information estimation section may estimate a hidden region using the user information and estimate the estimated hidden region as the non-target region, the hidden region being a region hidden by a finger of the user. 
         [0168]    A display control method according to this disclosure is a method for performing display control on a touch-panel-incorporated display panel, the method including: acquiring touch operation information from the touch panel; estimating a target region from a display region of the display panel based on the acquired touch operation information, the target region being a region of interest of a user; and setting a brightness level of a non-target region to be lower than a set brightness level, the non-target region being a region other than the target region estimated in the display region. 
         [0169]    A display control program according to this disclosure is a program that causes a computer that performs display control on a touch-panel-incorporated display panel to function as: a touch operation information acquiring section that acquires touch operation information from the touch panel; a user operation information estimation section that estimates a target region from a display region of the display panel based on the acquired touch operation information, the target region being a region of interest of a user; and a display control instruction section that sets a brightness level of a non-target region to be lower than a set brightness level, the non-target region being a region other than the target region estimated in the display region. 
         [0170]    The disclosure of Japanese Patent Application No. 2011-260186, filed on Nov. 29, 2011, including the specification, drawings, and abstract, is incorporated herein by reference in its entirety. 
       INDUSTRIAL APPLICABILITY 
       [0171]    The present invention is useful as a display control apparatus, a display control method, and a display control program capable of effectively reducing power consumption while securing viewability of a display region. That is, the present invention includes a function of providing a user with low-power and high-quality display information and is suitable for all electronic devices having a display apparatus, and particularly for battery-driven portable terminals. 
       REFERENCE SIGNS LIST 
       [0000]    
       
           100 ,  100   a ,  100   b  Display apparatus 
           200  Display panel 
           300  Touch panel 
           400 ,  400   a ,  400   b  Display control apparatus 
           410  Touch operation information acquiring section 
           420 ,  420   a ,  420   b  User operation information estimation section 
           430  Display control determining section 
           440  Display control instruction section 
           450   a  Layout information storage section 
           460   b  User information storage section