Abstract:
A computer device is provided that may comprise a display portion, a reference position input for enabling setting of a reference tilt position which is representative of an initial tilt position of the computer device. The computer device may also comprise a processor configured to perform a predetermined operation in accordance with a change in a tilt position of the computer device from the reference tilt position to a current tilt position.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    The present application claims priority from Japanese Patent Application No. JP 2010-105003 filed in the Japanese Patent Office on Apr. 30, 2010, the entire content of which is incorporated herein by reference. 
       BACKGROUND 
       [0002]    1. Technical Field 
         [0003]    The present application relates to an information processing apparatus and a display screen operating method. In particular, the present application relates to a handheld information processing apparatus capable of allowing the user to perform various operations, and also relates to a method for operating a display screen of the handheld information processing apparatus. 
         [0004]    2. Description of the Related Art 
         [0005]    Various personal computers with a wide variety of functions have been developed and proposed. In recent years, for example, notebook personal computers (hereinafter referred to as notebook PCs) have become smaller and smaller. There have been proposed notebook PCs that can be operated while being held in user&#39;s hands. 
         [0006]    Besides the notebook PCs, electronic devices with various information processing functions have been proposed which can be used while being held in user&#39;s hands. Additionally, various techniques have been proposed to improve their usability (see, e.g., Japanese Unexamined Patent Application Publication No. 2004-102738). 
         [0007]    Japanese Unexamined Patent Application Publication No. 2004-102738 describes a display apparatus which is operated while being held in user&#39;s hands. The display apparatus is equipped with an acceleration sensor and an angular velocity sensor, which detect movement of a display unit of the display apparatus in a planar direction. On the basis of the result of the detection made by the sensors, a screen displayed on the display unit is scrolled. 
       SUMMARY 
       [0008]    As described above, various techniques for operating handheld electronic devices have been proposed. However, as for techniques for operating handheld information processing apparatuses, such as notebook PCs, which allow the user to perform various operations, no technique has yet been proposed which is fully satisfactory in terms of usability. It is thus necessary to achieve further improvement in usability. 
         [0009]    The present application has been made in view of the circumstances described above. It is desirable to improve usability of a handheld information processing apparatus capable of allowing the user to perform various operations. 
         [0010]    According to the embodiment of the present application, a handheld information processing apparatus with improved usability can be provided which allows the user to perform various operations. 
         [0011]    In accordance with another embodiment of the present application, a computer device is provided. The computer device may comprise a display portion, a reference position input for enabling setting of a reference tilt position which is representative of an initial tilt position of the computer device, and a processor configured to perform a predetermined operation in accordance with a change in a tilt position of the computer device from the reference tilt position to a current tilt position. 
         [0012]    In accordance with a further embodiment of the present application, a method for use with a portable computer device is provided. The method may comprise activating a reference position input that enables setting of a reference tilt position which is representative of an initial tilt position of the portable computer device, and performing a predetermined operation which is related to a change in a tilt position of the computer device from the reference tilt position to a current tilt position. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  is an external perspective view of an information processing apparatus according to an embodiment of the present application. 
           [0014]      FIG. 2  is an internal block diagram of the information processing apparatus. 
           [0015]      FIG. 3  is a diagram for explaining various operations performed on the information processing apparatus. 
           [0016]      FIG. 4  is a diagram for explaining various operations performed on the information processing apparatus. 
           [0017]      FIG. 5  is a diagram for explaining a scrolling operation using a touchpad on the information processing apparatus. 
           [0018]      FIG. 6  is a diagram for explaining a scrolling operation using an acceleration sensor in the information processing apparatus. 
           [0019]      FIG. 7  illustrates a configuration of processing blocks for executing a scrolling operation using the acceleration sensor in the information processing apparatus. 
           [0020]      FIG. 8  is a flowchart illustrating a procedure for performing a scrolling operation using the acceleration sensor in the information processing apparatus. 
       
    
    
     DETAILED DESCRIPTION 
       [0021]    An information processing apparatus and a display screen operating method according to an embodiment of the present invention will be described with reference to the drawings in the following order. Note that the configuration of the present invention is not limited to this. 
         [0022]    1. Basic configuration of information processing apparatus 
         [0023]    2. Various operations on information processing apparatus 
         [0024]    3. Scrolling operation on information processing apparatus 
       1. Basic Configuration of Information Processing Apparatus 
     (External Configuration of Information Processing Apparatus) 
       [0025]      FIG. 1  is an external perspective view of an information processing apparatus  100  according to an embodiment of the present application. In the present embodiment, a notebook PC will be described as an example of the information processing apparatus  100 . 
         [0026]    The information processing apparatus  100  includes a main body  1  (apparatus main body), a display unit  2 , and two hinges  3 . In the example illustrated in  FIG. 1 , the two hinges  3  are attached near respective ends of a long edge la of the main body  1  adjacent to the display unit  2 . The display unit  2  is attached to the main body  1  via the two hinges  3 . Specifically, the display unit  2  is attached to the main body  1  such that it can pivot about a line connecting the centers of the two hinges  3 . The display unit  2  is opened and closed relative to the main body  1  by pivoting of the display unit  2 . 
         [0027]    The main body  1  includes a palm rest unit  4  (keyboard unit) and a main body unit  5  that constitute an upper side (facing the display unit  2 ) and a bottom side, respectively, of the main body  1 . The palm rest unit  4  and the main body unit  5  are integrally combined to form the main body  1 . The palm rest unit  4  and the main body unit  5  each are composed of a plurality of members, but have no visible screws etc. on their exteriors. 
         [0028]    The palm rest unit  4  includes operators, such as a keyboard  6 , a stick pointer  7 , and a first click button  8 . The stick pointer  7  is an operator used to move a cursor (pointer) displayed on a display screen  10  (described below) and to scroll the display screen  10 . The stick pointer  7  is located near the center of the palm rest unit  4 . 
         [0029]    The first click button  8  includes a left click button  8   a  and a right click button  8   b.  The first click button  8  is located at substantially the center of a long edge  1   b  of the palm rest unit  4  opposite the long edge  1   a  to which the hinges  3  are attached. The left click button  8   a  and the right click button  8   b  correspond to, for example, a left click button and a right click button, respectively, of a mouse used with a desktop PC in related art. 
         [0030]    Although not shown in  FIG. 1 , the main body unit  5  is equipped with, for example, a printed circuit board having a plurality of electronic components mounted thereon, a heat sink unit, and a drive such as a hard disk drive. The printed circuit board has, for example, a central processing unit (CPU), a memory, and other electronic components mounted thereon. 
         [0031]    Although not shown in  FIG. 1 , the main body unit  5  is equipped with an acceleration sensor that is used for various operation functions (described below). The acceleration sensor can be disposed at any position. For example, the acceleration sensor may be provided in the display unit  2 . If the acceleration sensor is provided in the main body unit  5 , the acceleration sensor is positioned by considering the positional relationship with other electronic components to be mounted on the main body unit  5 . In the present embodiment, the acceleration sensor is disposed, for example, substantially under the key for the letter “R”. 
         [0032]    The display unit  2  includes a housing  9 , a display screen  10  disposed on a surface of the housing  9  facing the main body  1 , a touch pad  11 , a second click button  12  (starting operator), and a display processing unit (not shown) provided inside the housing  9  and performing predetermined display processing. 
         [0033]    The display screen  10  is a screen for displaying various types of information, such as text and images. The touch pad  11  is an operator used, for example, to move a cursor (pointer) displayed on the display screen  10  and to scroll the display screen  10 . In the present embodiment, a capacitive sensor is used as the touch pad  11 . The touch pad is disposed near one corner of the housing  9  adjacent to the main body  1  (near a lower-right corner of the housing  9  in  FIG. 1 ). 
         [0034]    The second click button  12  includes a left click button  12   a  and a right click button  12   b.  The second click button  12  is disposed near the other corner of the housing  9  adjacent to the main body  1  (near a lower-left corner of the housing  9  in  FIG. 1 ). The left click button  12   a  and the right click button  12   b  correspond to, for example, a left click button and a right click button, respectively, of a mouse used with a desktop PC in related art. 
         [0035]    As described above, in the present embodiment, the touch pad  11  and the second click button  12  are disposed near the lower-right corner and the lower-left corner, respectively, of the housing  9  of the display unit  2  in  FIG. 1 . This is because of the following reasons. As will be described below, a pointing device system including the touch pad  11  and the second click button  12  of the display unit  2  is mainly used while the user holds both short edges  1   c  and  1   b  of the main body  1  of the information processing apparatus  100  with both hands. Therefore, when the touch pad  11  and the second click button  12  are disposed as described above, the user can easily operate them with thumbs while holding both the short edges lc and ld of the main body  1 . The positions of the touch pad  11  and the second click button  12  are not limited to those described above. The touch pad  11  and the second click button  12  may be disposed at any positions which allow the user to operate them with thumbs etc. while holding both the short edges  1   c  and  1   d  of the main body  1 . 
         [0036]    The information processing apparatus  100  has a pointing device system including the stick pointer  7  and the first click button  8  of the main body  1 , and another pointing device system including the touch pad  11  and the second click button  12  of the display unit  2  as described above. This means that the information processing apparatus  100  of the present embodiment has two pointing device systems. In the present embodiment, the two pointing device systems may be electrically connected to each other (by sharing a common processing system) so that they can be used simultaneously, or may have different processing systems so that they can be operated individually. 
       (Internal Configuration of Information Processing Apparatus) 
       [0037]    An internal configuration (hardware configuration) of the information processing apparatus  100  will now be described with reference to  FIG. 2 .  FIG. 2  is a block diagram illustrating hardware of the information processing apparatus  100 . 
         [0038]    The information processing apparatus  100  includes a CPU  101 , a read only memory (ROM)  102 , a random access memory (RAM)  103 , a host bus  104 , a bridge  105 , an external bus  106 , and an interface  107 . The information processing apparatus  100  further includes an input device  108 , an output device  109 , a storage device  110 , a drive  111 , a connection port  112 , a communication device  113 , an image pickup device  114 , and an acceleration sensor  115 . 
         [0039]    The CPU  101  serves both as an arithmetic processing device and a control device. Specifically, the CPU  101  controls all or some of operations within the information processing apparatus  100  in accordance with various programs recorded in the ROM  102 , the RAM  103 , and the storage device  110 , or in a removable recording medium  201  connected to the information processing apparatus  100  via the drive  111 . Therefore, the CPU  101  controls various operations (described below) in the information processing apparatus  100  of the present embodiment. 
         [0040]    The ROM  102  stores programs and arithmetic parameters used by the CPU  101 . The RAM  103  temporarily stores programs that the CPU  101  uses to perform control processing, and parameters necessary for execution of the control processing. 
         [0041]    The CPU  101 , the ROM  102 , and the RAM  103  are connected to each other via the host bus  104 , which includes an internal bus (not shown) such as a CPU bus. Data, such as the programs and arithmetic parameters described above, is input and output via the host bus  104  between the CPU  101 , the ROM  102 , and the RAM  103 . The host bus  104  is connected via the bridge  105  to the external bus  106 , such as a peripheral component interconnect/interface (PCI) bus. 
         [0042]    The input device  108  includes operation units, such as a mouse, a keyboard, a touch panel, buttons, switches, and levers, operated by the user. This means that the stick pointer  7  and the first click button  8  of the main body  1  and the touch pad  11  and the second click button  12  of the display unit  2 , described above, are included in the input device  108 . The input device  108  may include a remote control device using infrared rays or radio waves. The input device  108  may have an input function which allows direct operation from an externally-connected device  202 , such as a mobile phone or a personal digital assistant (PDA). 
         [0043]    The input device  108  includes an input control circuit that generates an operation signal corresponding to an operation performed by the user using the various operation units described above, and outputs the generated operation signal to the CPU  101 . On the basis of the operation signal output from the input device  108 , the CPU  101  executes processing corresponding to the operation performed by the user. 
         [0044]    The output device  109  includes a display device capable of visually informing the user of obtained information, and an audio output device capable of informing the user of obtained information with sound. The display device may be, for example, a cathode-ray tube (CRT) display device, a liquid-crystal display device, a plasma display device, an electro-luminescence (EL) display device, or a lamp. The audio output device includes, for example, a speaker and headphones. The output device  109  may include a printer, a mobile phone, and a facsimile. 
         [0045]    The output device  109  outputs results obtained by various types of processing performed by the information processing apparatus  100 . Specifically, a display device included in the output device  109  displays results obtained by various types of processing performed by the information processing apparatus  100  as text or images. An audio output device included in the output device  109  converts an audio signal composed of reproduced voice data and acoustic data into an analog signal and outputs it. 
         [0046]    The storage device  110  is a device for storage of data. The storage device  110  may be, for example, a magnetic storage device such as a hard disk drive (HDD), a semiconductor storage device, an optical storage device, or a magneto-optical storage device. The storage device  110  stores programs executed by the CPU  101 , various types of data, and acoustic signal data and image signal data externally obtained. 
         [0047]    The drive  111  is a reader/writer for recording media. Although the drive  111  is included in the information processing apparatus  100  in the example of  FIG. 2 , the present application is not limited to this. The drive  111  may be configured as a drive external to the information processing apparatus  100 . The drive  111  reads predetermined information recorded in the removable recording medium  201  loaded in the drive  111  and outputs the read predetermined information to the RAM  103 . Also, the drive  111  is capable of writing information to the removable recording medium  201  loaded therein. 
         [0048]    The removable recording medium  201  is, for example, a magnetic disk, an optical disk, a magneto-optical disk, or a semiconductor memory. More specifically, the removable recording medium  201  is, for example, a digital versatile disc (DVD), a Blu-ray disc (BD) (registered trademark), a compact flash (registered trademark) card, a memory stick, or a secure digital (SD) memory card. The removable recording medium  201  may be, for example, an integrated circuit (IC) card equipped with a contactless IC chip, or an external electronic device. 
         [0049]    The connection port  112  is for directly connecting an external device to the information processing apparatus  100 . The connection port  112  includes, for example, a universal serial bus (USB) port, an IEEE1394 port such as i.Link, and a small computer system interface (SCSI) port. The connection port  112  further includes, for example, an RS-232C port, an optical audio terminal, and a high-definition multimedia interface (HDMI) port. By connecting the externally-connected device  202  to the connection port  112 , the information processing apparatus  100  can directly obtain acoustic signal data and image signal data from the externally-connected device  202 , and can provide acoustic signal data and image signal data to the externally-connected device  202 . 
         [0050]    The communication device  113  is a communication interface including devices necessary for connecting the information processing apparatus  100  to, for example, a network  203 . The communication device  113  includes, for example, a communication card for a wired or wireless local area network (LAN), Bluetooth, or wireless USB (WUSB). The communication device  113  further includes an optical communication router, an asymmetric digital subscriber line (ADSL) router, or various communication modems. The information processing apparatus  100  can transmit and receive predetermined information to and from, for example, the Internet or communication devices via the communication device  113 . The network  203  is a network connected to the communication device  113  by wired or wireless communication. For example, the network  203  is the Internet, a home LAN, an infrared communication network, a radio-wave communication network, or a satellite communication network. 
         [0051]    The image pickup device  114  includes an imaging optical system and an image pickup element (not shown). The imaging optical system receives light (image light) incident from a subject and forms the incident light into an image on the image pickup element. The image pickup element converts the amount of the incident light into an electric signal (photoelectric conversion) to obtain a picked-up image. The picked-up image obtained from the image pickup element may be a moving image obtained in time series or a still image obtained at one point in time. The image pickup element is, for example, a charge coupled device (CCD) image sensor or a metal-oxide semiconductor (MOS) image sensor. 
         [0052]    The acceleration sensor  115  detects information related to a tilt of the main body  1  (acceleration). In the information processing apparatus  100  of the present embodiment, the CPU  101  may perform one or more predetermined operations, such as a scrolling operation for scrolling the display screen  10 , a rotating operation for rotating a displayed image, a cursor operation for moving a cursor displayed on the display screen, an audio/visual operation for reproducing audio/visual content, and/or a page turning operation for turning a displayed page, on the basis of the information detected by the acceleration sensor  115 . 
         [0053]    In the present embodiment, a three-axis acceleration sensor serves as the acceleration sensor  115  to handle the various operations described above. In the present embodiment, a tilt of the main body  1  is calculated on the basis of an acceleration (gravitational acceleration) component in each axis direction detected by the acceleration sensor  115 . In the present embodiment, the various operations described above are handled by one acceleration sensor  115 . However, the present application is not limited to this, and a different acceleration sensor may be provided for each of the operations. In this case, a one-axis or two-axis acceleration sensor may be used depending on the type of operation. 
         [0054]    The above-described internal configuration (hardware configuration) of the information processing apparatus  100  is merely an example. Each of the components described above may either be a general-purpose member, or hardware designed specifically for a function corresponding to the component. The hardware configuration to be used can be changed appropriately depending on the level of technology of the time when the present embodiment is carried out. 
       2. Various Operations on Information Processing Apparatus 
       [0055]    Examples of various operations that can be performed on the information processing apparatus  100  of the present embodiment will now be briefly described. 
         [0056]    As described above, the information processing apparatus  100  of the present embodiment has two pointing device systems. The stick pointer  7  and the first click button  8  of the main body  1  are used, for example, to perform a click operation, a cursor operation, and a scrolling operation on the information processing apparatus  100  placed on a desk, as in the case of a notebook PC of related art. Also, in the information processing apparatus  100  of the present embodiment, the touch pad  11  and the second click button  12  of the display unit  2  allow the user, for example, to perform a click operation, a cursor operation, and a scrolling operation while holding the information processing apparatus  100  in hands. 
         [0057]    Operations performed using the stick pointer  7  and the first click button  8  of the main body  1  will not be described here, as they are substantially the same as those performed on a notebook PC of related art. A description will be given of operations that can be performed using the touch pad  11  and the second click button  12  of the display unit  2 . 
         [0058]      FIG. 3  illustrates the information processing apparatus  100  that is held at one and the other short edges of the main body  1  (on the right and left sides in  FIG. 3 ) by the user&#39;s right and left hands, respectively (hereinafter, this position of the information processing apparatus  100  will be referred to as “landscape position”). In the information processing apparatus  100  of the present embodiment, in  FIG. 3 , the touch pad  11  is located near the lower-right corner of the display unit  2 , and the second click button  12  is located near the lower-left corner of the display unit  2 . When the user holds the information processing apparatus  100  in landscape position, the user&#39;s right thumb is placed on the touch pad  11  and the user&#39;s left thumb is placed on the second click button  12 . Therefore, when the user holds the information processing apparatus  100  of the present embodiment in landscape position, the user can easily operate the touch pad  11  and the second click button  12  while holding the information processing apparatus  100 . 
         [0059]    In the present embodiment, while holding the information processing apparatus  100  in landscape position, the user can may perform one or more predetermined operations, such as a scrolling operation for scrolling the display screen  10 , a cursor operation for moving a cursor on the display screen  10 , a page turning operation for turning a displayed page, an audio/visual operation for reproducing audio/visual content, and/or a rotating operation for rotating a displayed image. Hereinafter, a brief description will be given of a page turning operation for turning a displayed page and a rotating operation for rotating a displayed image that are performed on the information processing apparatus  100  of the present embodiment. A scrolling process in the information processing apparatus  100  of the present embodiment will be described in detail later on. 
       (Page Turning Operation for Turning Displayed Page) 
       [0060]    In the information processing apparatus  100  of the present embodiment, a page turning operation for turning a displayed page can be performed using the touch pad  11  or the acceleration sensor  115 . 
         [0061]    When using the touch pad  11 , the user moves the right thumb on the touch pad  11  along the longitudinal direction of the display screen  10  (in the direction of arrow A 1  in  FIG. 3 ) while holding the information processing apparatus  100  in landscape position (see  FIG. 3 ). Thus, a page turning operation for turning a displayed page can be done. 
         [0062]    When the acceleration sensor  115  is used, a page turning operation for turning a displayed page is done in the following manner. First, as illustrated in  FIG. 3 , the user holds the information processing apparatus  100  in landscape position. Next, as indicated by arrow A 2  in  FIG. 3 , the user rotates the information processing apparatus  100  to the right or left (by right or left clicking) in a plane facing the user. 
         [0063]    In this case, on the basis of information related to a tilt of the main body  1  (acceleration) obtained by the acceleration sensor  115 , the CPU  101  calculates a change in tilt of the main body  1 . Then, on the basis of the calculated change, the CPU  101  determines a direction of rotation of the information processing apparatus  100  and performs a page turning operation on the display screen  10  in a direction corresponding to the determined direction of rotation. For example, when the user rotates the information processing apparatus  100  to the right, the CPU  101  displays an image on the next page, and when the user rotates the information processing apparatus  100  to the left, the CPU  101  displays an image on the previous page. 
       (Rotating Operation for Rotating Displayed Image) 
       [0064]    A rotating operation for rotating a displayed image  20  in the information processing apparatus  100  of the present embodiment is performed in the following manner. First, assume that the user holds the information processing apparatus  100  in landscape position as illustrated in  FIG. 3 . In landscape position, the up-and-down direction of the displayed image  20  (a flower image in the example of  FIG. 3 ) displayed on the display screen  10  coincides with the direction of short sides of the display screen  10 . 
         [0065]    Next, assume that the user rotates the information processing apparatus  100  by 90 degrees in a plane facing the user.  FIG. 4  illustrates the information processing apparatus  100  rotated by 90 degrees from  FIG. 3  (hereinafter, this position of the information processing apparatus  100  will be referred to as “portrait position”). On the basis of a detection signal obtained by the acceleration sensor  115 , the CPU  101  determines that the information processing apparatus  100  has been rotated by 90 degrees. Then, the CPU  101  rotates the displayed image  20  by 90 degrees in the same direction as the rotation of the information processing apparatus  100  and displays the rotated displayed image  20 . Thus, when the information processing apparatus  100  is rotated to portrait position, the displayed image  20  is rotated by 90 degrees such that its up-and-down direction coincides with the longitudinal direction of the display screen  10 . 
         [0066]    The present embodiment is configured such that when the information processing apparatus  100  is rotated from landscape to portrait position, the direction of operation of the stick pointer  7  and that of the touch pad  11  are automatically rotated by 90 degrees. 
       3. Scrolling Operation on Information Processing Apparatus 
       [0067]    Next, a description will be given of a scrolling operation that the user performs while holding the information processing apparatus  100  in hands. In the present embodiment, the aspect ratio of the display screen  10  is relatively small, as illustrated in  FIG. 3 . Therefore, a scrolling operation is performed mainly in the direction of short sides of the display screen  10  (in the up-and-down direction in  FIG. 3 ). The present embodiment describes an example in which the display screen  10  is scrolled in the direction of its short sides. 
         [0068]    In the information processing apparatus  100  of the present embodiment, when performing a scrolling operation while holding the information processing apparatus  100  in hands, the user can use the touch pad  11  of the display unit  2  or the acceleration sensor  115  mounted inside the main body  1 . 
       (Method Using Touch Pad) 
       [0069]    First, a procedure for performing a scrolling operation using the touch pad  11  will be described with reference to  FIG. 5 .  FIG. 5  is a front view of the information processing apparatus  100  held in landscape position (see  FIG. 3 ) by the user. To simplify the description, the user&#39;s both hands are omitted from the illustration of  FIG. 5 . 
         [0070]    When performing a scrolling operation using the touch pad  11 , the user first presses both the left click button  12   a  and the right click button  12   b  of the second click button  12 , for example, with the left thumb (see arrow A 3  in  FIG. 5 ). This brings the operation mode of the information processing apparatus  100  into a scrolling operation mode. 
         [0071]    Next, while holding down the second click button  12 , the user moves, for example, the right thumb on the touch pad in one or the other direction (upward or downward in  FIG. 5 ) along the direction of short sides of the display screen  10 , as indicated by arrow A 4  in  FIG. 5 . 
         [0072]    The touch pad  11  detects a signal corresponding to the direction and amount of movement of the finger. The CPU  101  controls the display screen  10  on the basis of the detected signal, and scrolls the display screen  10  by a predetermined amount in the direction of short sides of the display screen  10  corresponding to the detected signal. 
         [0073]    A scrolling operation using the touch pad  11  is performed in the manner described above. The present embodiment is configured such that once the scrolling operation mode is entered, it continues until the finger is released from the second click button  12 . For example, after the scrolling operation mode is entered, even if the finger holding down the second click button  12  is displaced therefrom and one of the left click button  12   a  and the right click button  12   b  is released, the scrolling operation mode is not cancelled. This function works similarly in a scrolling operation using the acceleration sensor  115 . 
       (Method Using Acceleration Sensor) 
     (1) Operation Overview 
       [0074]    Next, an overview of a scrolling operation performed using the acceleration sensor  115  will be described with reference to  FIG. 6 .  FIG. 6  is a side view of the information processing apparatus  100  held in landscape position (see  FIG. 3 ) by the user. To simplify the description, the user&#39;s both hands are omitted from the illustration of  FIG. 6 . 
         [0075]    When performing a scrolling operation using the acceleration sensor  115 , the user first presses both the left click button  12   a  and the right click button  12   b  of the second click button  12 , for example, with the left thumb. Thus, the scrolling operation mode is entered. 
         [0076]    Next, while holding down the second click button  12 , the user rotates the information processing apparatus  100  in one or the other direction (see arrow AS in  FIG. 6 ) about the axis along which the long edge  1   a  of the main body  1  adjacent to the display unit  2  extends. The tilt of the main body  1  is thus changed. Then, the acceleration sensor  115  detects a signal corresponding to the direction and amount of change in tilt of the main body  1 , and outputs the detected signal to the CPU  101 . The CPU  101  controls the display screen  10  on the basis of the detected signal, and scrolls the display screen  10  by a predetermined amount in the direction of short sides of the display screen  10  corresponding to the detected signal. 
         [0077]    A scrolling operation using the acceleration sensor  115  is performed in the manner described above. Again, as in the case of a scrolling operation using the touch pad  11 , the scrolling operation mode continues until the finger is released from the second click button  12 . 
         [0078]    In the method using the acceleration sensor  115 , the tilt of the main body  1  at the start of a scrolling operation (initial tilt) varies depending on how the user holds the information processing apparatus  100 . In another embodiment, the initial tilt or reference position may be set automatically. Therefore, in the present embodiment, as will be described in detail below, the CPU  101  calculates the direction and amount of change in tilt of the main body  1  with respect to the initial tilt of the main body  1 , and performs the scrolling operation on the basis of the calculated direction and amount of change. 
       (2) Processing Blocks 
       [0079]    A scrolling operation using the acceleration sensor  115  will now be described in detail with reference to  FIG. 7  and  FIG. 8 .  FIG. 7  is a block diagram of a processing system necessary for performing a scrolling operation using the acceleration sensor  115 . Note that only a processing system necessary for a scrolling operation using the acceleration sensor  115  is illustrated in  FIG. 7 , and others are omitted from the illustration.  FIG. 8  is a flowchart illustrating a procedure for performing a scrolling operation using the acceleration sensor  115 . 
         [0080]    As illustrated in  FIG. 7 , the CPU  101  includes an acceleration reader  120  and a screen scrolling controller  121  (scrolling operation controller) as processing units for performing a scrolling operation using the acceleration sensor  115 . 
         [0081]    The acceleration reader  120  is connected to the acceleration sensor  115  and obtains a signal detected by the acceleration sensor  115 . The acceleration reader  120  outputs the detected signal obtained from the acceleration sensor  115  to the screen scrolling controller  121 . 
         [0082]    The screen scrolling controller  121  controls an overall scrolling operation. For example, the screen scrolling controller  121  determines the start and continuation of the scrolling operation mode, and calculates the direction and amount of scrolling in the scrolling operation. The screen scrolling controller  121  is connected, for example, to the second click button  12  and determines the start and continuation of the scrolling operation mode on the basis of an input signal from the second click button  12 . Also, on the basis of a signal detected by the acceleration sensor  115  and input from the acceleration reader  120 , the screen scrolling controller  121  calculates the direction and amount of scrolling of the display screen  10 . 
         [0083]    The direction of scrolling can be calculated from a gravitational acceleration component in each axis detected by the acceleration sensor  115 . The amount of scrolling can be determined, for example, in the following manner. First, a speed is calculated by integrating gravitational acceleration detected by the acceleration sensor  115  with respect to a predetermined period of time. Then, a distance of movement of the main body  1  is calculated by integrating the calculated speed with respect to a predetermined period of time. Then, the amount of scrolling is determined on the basis of the calculated distance of movement of the main body  1 . Note in the present embodiment that the distance of movement is calculated with respect to the start (initial state) of the scrolling operation. As noted above, the initial tilt or reference position may be set automatically. Such automatic setting may be performed by a software program (such as an application), without additional input by the user, based on the detected context. Such detected context may pertain to a number of predetermined parameters, such as time, place, device status and so forth. Then, for example, a correspondence between the calculated distance of movement and the amount of scrolling is stored as data, in advance, in the ROM  102  or the storage device  110 . The screen scrolling controller  121  determines the amount of scrolling with reference to the data stored. 
       (3) Operation Procedure 
       [0084]    With reference to  FIG. 8 , a procedure for performing a scrolling operation using the acceleration sensor  115  will be described in detail. The present embodiment describes an example in which a scrolling operation is controlled using a variable for determining whether the operation condition is in a scrolling state (hereinafter referred to as a scrolling state variable). In the following description, the scrolling state variable is set to “TRUE” when the operation condition is in a scrolling state, while the scrolling state variable is set to “FALSE” when the operation condition is not in a scrolling state. Note that the scrolling state variable is “FALSE” at the start (initial state) of a scrolling operation. 
         [0085]    First, the information processing apparatus  100  is held in landscape position by the user. Next, on the basis of an output signal from the second click button  12 , the screen scrolling controller  121  determines whether both the left click button  12   a  and the right click button  12   b  are held down (step S 1 ). Specifically, for example, the screen scrolling controller  121  determines whether held-down signals are output from both the left click button  12   a  and the right click button  12   b.    
         [0086]    If held-down signals are not output from both the left click button  12   a  and the right click button  12   b  (NO in step S 1 ), the screen scrolling controller  121  sets the scrolling state variable to “FALSE” (step S 10 ) and ends the scrolling process. 
         [0087]    On the other hand, if held-down signals are output from both the left click button  12   a  and the right click button  12   b  (YES in step S 1 ), the screen scrolling controller  121  starts the scrolling operation mode and determines whether the scrolling state variable is “TRUE” (step S 2 ). 
         [0088]    A processing procedure from step S 2  carried out at the start of the scrolling operation will now be described. As described above, the scrolling state variable is “FALSE” at the start of the scrolling operation (NO in step S 2 ). In this case, on the basis of a detection signal from the acceleration sensor  115 , the screen scrolling controller  121  calculates a tilt (initial tilt) of the main body  1  and sets the calculated tilt as a reference position (step S 3 ). Next, the screen scrolling controller  121  sets the scrolling state variable to “TRUE” (step S 4 ). Step S 4  may be performed before step S 3 . 
         [0089]    Next, the screen scrolling controller  121  determines whether the second click button  12  is held down (step S 8 ). In step S 8 , a determination is made as to whether the scrolling state continues. Therefore, the screen scrolling controller  121  determines whether a held-down signal is output from at least one of the left click button  12   a  and the right click button  12   b.    
         [0090]    If held-down signals are not output from both the left click button  12   a  and the right click button  12   b  (NO in step S 8 ), the screen scrolling controller  121  stops the scrolling operation (step S 9 ), sets the scrolling state variable to “FALSE” (step S 10 ), and ends the scrolling process. 
         [0091]    On the other hand, if a held-down signal is output from at least one of the left click button  12   a  and the right click button  12   b  (YES in step S 8 ), the screen scrolling controller  121  determines that the scrolling state continues. The screen scrolling controller  121  then returns to step S 2 . 
         [0092]    Next, a processing procedure from step S 2  carried out after the scrolling operation mode is entered and a reference position of the main body  1  is set (in step S 3 ) will be described. 
         [0093]    First, the screen scrolling controller  121  determines whether the scrolling state variable is “TRUE” (step S 2 ). After the scrolling operation mode is entered and a reference position of the main body  1  is set, the scrolling state variable is “TRUE” (YES in step S 2 ). 
         [0094]    In this case, the screen scrolling controller  121  obtains a detection signal (gravitational acceleration) from the acceleration sensor  115  and calculates the tilt of the main body  1 . On the basis of the calculated tilt, the screen scrolling controller  121  calculates the direction and amount of change in tilt of the main body  1  from the reference position set in step S 3  (step S 5 ). Next, on the basis of the calculated direction and amount of change in tilt of the main body  1 , the screen scrolling controller  121  calculates the direction and amount of scrolling of the display screen  10  (step S 6 ). 
         [0095]    Next, the screen scrolling controller  121  controls the display unit  2  on the basis of the calculated direction and amount of scrolling of the display screen  10 , and scrolls the display screen  10  in a predetermined direction by a predetermined amount (step S 7 ). Then, the screen scrolling controller  121  determines whether the second click button  12  is held down (step S 8 ). 
         [0096]    If a held-down signal is output from at least one of the left click button  12   a  and the right click button  12   b  (YES in step S 8 ), the screen scrolling controller  121  determines that the scrolling state continues. Then, the screen scrolling controller  121  repeats step S 2  to step S 7  described above. 
         [0097]    On the other hand, if held-down signals are not output from both the left click button  12   a  and the right click button  12   b  (NO in step S 8 ), the screen scrolling controller  121  stops the scrolling operation (step S 9 ), sets the scrolling state variable to “FALSE” (step S 10 ), and ends the scrolling process. In the present embodiment, a scrolling operation using the acceleration sensor  115  is performed in the manner described above. 
         [0098]    As described above, in the information processing apparatus  100  of the present embodiment, after the scrolling operation mode is entered, information related to the tilt of the main body  1  of the information processing apparatus  100  is detected by the acceleration sensor  115 , and the corresponding scrolling operation is performed on the basis of the detected information. That is, in the present embodiment, once the scrolling operation mode is entered, a predetermined scrolling operation is made possible simply by tilting the information processing apparatus  100 . Therefore, in the present embodiment, after the scrolling operation mode is entered, a scrolling operation can be performed without using operators, such as buttons and keys, and thus, improved usability can be achieved. 
         [0099]    In the present embodiment, the direction and amount of scrolling of the display screen  10  are calculated with respect to an initial tilt of the main body  1  calculated at the start of a scrolling operation. Therefore, in the present embodiment, even if the way the user holds the information processing apparatus  100  at the start of the scrolling operation (i.e., the initial tilt of the information processing apparatus  100 ) is changed, the scrolling operation can be performed accurately. 
         [0100]    In the embodiments describe above, when a scrolling operation is performed using the acceleration sensor  115 , the second click button  12  is used as an operator for starting the scrolling operation mode. However, the present application is not limited to this. As an operator for starting the scrolling operation mode, the first click button  8  or a predetermined key on the keyboard  6  may be used. However, when the user performs a scrolling operation while holding the information processing apparatus  100  in landscape position as illustrated in  FIG. 3 , using the second click button  12  as an operator for starting the scrolling operation mode makes it easier to perform the scrolling operation. 
         [0101]    In the embodiments describe above, the user holds down at least one of the left click button  12   a  and the right click button  12   b  as a way to continue the scrolling operation mode. However, the present application is not limited to this, and any method can be used. For example, a configuration may be made such that once the scrolling operation mode is entered by holding down the left click button  12   a  and the right click button  12   b  for a predetermined period of time, the scrolling operation mode can continue even if the finger is released from the second click button  12 . Alternatively, if an operator for starting the scrolling operation mode is a single operation button, both the starting and continuation of the scrolling operation mode may be executed, for example, by double-clicking on the operation button. 
         [0102]    In the embodiments describe above, the display screen  10  is scrolled in the direction of its short sides (vertical direction). However, the present application is not limited to this. In the present embodiment, since a three-axis acceleration sensor is used as the acceleration sensor  115 , the display screen  10  can also be scrolled in its longitudinal direction (horizontal direction). In this case, for example, while holding down the second click button  12 , the user may rotate the information processing apparatus  100  in a bottom plane of the main body  1  in one or the other direction. Then, the acceleration sensor  115  may detect the direction and amount of the rotation of the main body  1  so that the display screen  10  can be scrolled on the basis of the detected signal. 
         [0103]    In the embodiments describe above, for determining the direction and amount of scrolling of the display screen  10 , the acceleration sensor  115  detects information related to a tilt of the main body  1 . However, the present application is not limited to this. If the acceleration sensor  115  is mounted on the display unit  2 , the acceleration sensor  115  may detect information related to a tilt of the display unit  2  so that a scrolling operation can be performed on the basis of the detected information. 
         [0104]    It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and alterations may occur depending on design requirements and other factors insofar as they are within the scope of the appended claims or the equivalents thereof.