Abstract:
An apparatus includes a processor and a memory. The memory is configured to store computer-readable instructions. The computer-readable instructions cause the processor to perform processes that include acquiring detected stroke data indicating a trajectory of a writing portion, determining with reference to a first storage portion, based on the detected stroke data, whether a reference trajectory is included in one of one or more peripheral areas, and each of the one or more peripheral areas being an area surrounding each of one or more reference positions, and correcting the detected stroke data, based on an amount of displacement between the reference trajectory and a reference position that is inside one of the one or more peripheral areas, in a case where it is determined that the reference trajectory is included in the one of the one or more peripheral areas.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to Japanese Patent Application No. 2013-067646 filed Mar. 27, 2013, the content of which is hereby incorporated herein by reference. 
       BACKGROUND 
       [0002]    The present disclosure relates to an apparatus that is configured to correct positional displacement of characters etc. caused by positional displacement of a paper medium, and a non-transitory computer-readable medium storing computer-readable instructions. 
         [0003]    A correction apparatus is known that is configured to acquire data etc. of characters etc. that are written on a paper medium, and that is configured to correct positional displacement of the characters etc. caused by positional displacement of the paper medium. For example, a known written data input apparatus includes a left-side paper position sensor and a right-side paper position sensor. The left-side paper position sensor may detect a position of a left side corner portion of a paper sheet. The right-side paper position sensor may detect a position of a right side corner portion of the paper sheet. The written data input apparatus may correct input coordinate values that are input at a time of handwriting input, in accordance with an amount of displacement between the positions that are respectively detected by the left-side paper position sensor and the right-side paper position sensor and correct alignment positions of the paper sheet. 
       SUMMARY 
       [0004]    The above-described known written data input apparatus needs the right-side paper position sensor and the left-side paper position sensor to correct the positional displacement of the characters etc., and thus costs may increase. 
         [0005]    Embodiments of the broad principles derived herein provide an apparatus that is capable of correcting positional displacement of data such as written characters etc. while reducing costs, and a non-transitory computer-readable medium storing computer-readable instructions. 
         [0006]    Embodiments provide an apparatus that includes a processor and a memory. The memory is configured to store computer-readable instructions. The computer-readable instructions cause the processor to perform a process that includes acquiring detected stroke data. The detected stroke data is data that has been detected by a detection portion. The detected stroke data indicates a trajectory of a writing portion. The detection portion is configured to detect the trajectory of the writing portion that is close to the detection portion. The computer-readable instructions further cause the processor to perform a process that includes determining with reference to a first storage portion, based on the detected stroke data that has been acquired, whether a reference trajectory is included in one of one or more peripheral areas. The reference trajectory is at least a part of the trajectory. The first storage portion stores one or more reference positions and the one or more peripheral areas. Each of the one or more reference positions is a position that is a reference for position correction of the trajectory. Each of the one or more peripheral areas is an area surrounding each of the one or more reference positions. The computer-readable instructions further cause the processor to perform a process that includes correcting the detected stroke data, based on an amount of displacement between the reference trajectory and a reference position that is inside one of the one or more peripheral areas, in a case where it is determined that the reference trajectory is included in the one of the one or more peripheral areas. 
         [0007]    Embodiments also include a non-transitory computer-readable medium storing computer-readable instructions that, when executed by a processor of an apparatus, instruct the processor to perform processes that include acquiring detected stroke data, the detected stroke data being data that has been detected by a detection portion, the detected stroke data indicating a trajectory of a writing portion, and the detection portion being configured to detect the trajectory of the writing portion that is close to the detection portion, determining with reference to a first storage portion, based on the detected stroke data that has been acquired, whether a reference trajectory is included in one of one or more peripheral areas, the reference trajectory being at least a part of the trajectory, the first storage portion storing one or more reference positions and the one or more peripheral areas, each of the one or more reference positions being a position that is a reference for position correction of the trajectory, and each of the one or more peripheral areas being an area surrounding each of the one or more reference positions, and correcting the detected stroke data, based on an amount of displacement between the reference trajectory and a reference position that is inside one of the one or more peripheral areas, in a case where it is determined that the reference trajectory is included in the one of the one or more peripheral areas. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    Embodiments will be described below in detail with reference to the accompanying drawings in which: 
           [0009]      FIG. 1  is a configuration diagram of a handwriting input system; 
           [0010]      FIG. 2  is a diagram showing an electrical configuration of the handwriting input system; 
           [0011]      FIG. 3  is a diagram showing an example of a sheet of a paper medium; 
           [0012]      FIG. 4  is a diagram showing positions on a sensor board that correspond to coordinate information that is stored in an HDD; 
           [0013]      FIG. 5  is a flowchart of first main processing; 
           [0014]      FIG. 6  is a diagram showing a state in which the sheet is arranged on the sensor board; 
           [0015]      FIG. 7  is a diagram showing an example of an image that is displayed on a display; 
           [0016]      FIG. 8  is a flowchart of second main processing; 
           [0017]      FIG. 9  is a diagram showing a state in which the sheet is arranged on the sensor board; 
           [0018]      FIG. 10  is a diagram showing an example of an image that is displayed on the display; 
           [0019]      FIG. 11  is a data configuration diagram of a tag information data table; and 
           [0020]      FIG. 12  is a diagram showing patterns and a pattern obtained by correcting shapes of the patterns. 
       
    
    
     DETAILED DESCRIPTION 
       [0021]    Hereinafter, embodiments will be explained with reference to the drawings. An overview of a handwriting input system  1  according to a first embodiment will be explained with reference to  FIG. 1 . In the following explanation, an upper left side, a lower right side, an upper side, a lower side, an upper right side, and a lower left side of  FIG. 1  respectively define a left side, a right side, an upper side, a lower side, a rear side, and a front side of a reading device  2 . 
         [0022]    The handwriting input system  1  includes the reading device  2 , an electronic pen  3 , and a PC  4 . In the handwriting input system  1 , a user may use the electronic pen  3  to write information by writing a text (a character, a numeral, a symbol, a graphic, etc.) on a paper medium  100  that is fixed to the reading device  2 . The reading device  2  may detect a trajectory of the electronic pen  3  that writes the information on the paper medium  100 , and may acquire stroke data that will be explained below. Based on the stroke data acquired by the reading device  2 , the PC  4  may generate data etc. obtained by digitizing the information written on the paper medium  100 . 
         [0023]    The reading device  2  mainly includes a pair of left and right sensor boards  7 L and  7 R. The sensor boards  7 L and  7 R are the same rectangular thin plate-shaped boards. The sensor boards  7 L and  7 R can be opened out to a two-page spread in the left-right direction. Each of the sensor boards  7 L and  7 R is provided with a plurality of long thin loop coils that are arranged in both an X axis direction and in a Y axis direction. The reading device  2  is a thin, light-weight handwriting input device that is portable when the sensor boards  7 L and  7 R are in a folded over state. 
         [0024]    The electronic pen  3  is a known electromagnetic induction-type electronic pen. The electronic pen  3  includes a core body  31 , a coil  32 , a variable capacity condenser  33 , a board  34 , a condenser  35  and an ink storage portion  36 . The core body  31  is provided on the leading end portion of the electronic pen  3 . The core body  31  is urged toward the leading end of the electronic pen  3  by an elastic member that is not shown in the drawings. The leading end portion of the core body  31  protrudes to the outside of the electronic pen  3 . The rear end of the core body  31  is connected to the ink storage portion  36 . Ink is stored in the ink storage portion  36 . The ink storage portion  36  supplies ink to the core body  31 . When the user writes using the electronic pen  3 , the written text is formed by the ink. 
         [0025]    In a state in which the coil  32  is wound around the periphery of the ink storage portion  36 , the coil  32  is held between the core body  31  and the variable capacity condenser  33 . The variable capacity condenser  33  is fixed to the inside of the electronic pen  3  by the board  34 . The condenser  35  is mounted on the board  34 . The condenser  35  and the variable capacity condenser  33  are connected in parallel to the coil  32  and form a known resonance (tuning) circuit. 
         [0026]    The paper medium  100  has a notebook form that can be opened out to a two-page spread in the left-right direction. In the paper medium  100 , a pair of cover sheets (a front cover sheet  110 L and a back cover sheet  110 R) and a plurality of paper sheets  120  are respectively bound by a part of their edges. As an example, the paper medium  100  is an A5-sized notebook. The paper medium  100  may be mounted on the reading device  2  such that the front cover sheet  110 L is placed on the upper surface of the sensor board  7 L and the back cover sheet  110 R is placed on the upper surface of the sensor board  7 R. The user may use the electronic pen  3  to write information on the paper sheet  120  when the paper medium  100  is mounted on the reading device  2 . Position information of the electronic pen  3  that writes the information on the paper medium  100  may be detected by one of the sensor boards  7 L and  7 R that face the paper sheet  120  on which the information has been written. 
         [0027]    An electrical configuration of the handwriting input system  1  will be explained with reference to  FIG. 2 . First, an electrical configuration of the reading device  2  will be explained. The reading device  2  includes the sensor boards  7 L and  7 R, a main board  20 , and sensor control boards  28  and  29 . 
         [0028]    The main board  20  includes a CPU  21 , a flash ROM  22 , and a wireless communication portion  23 . The flash ROM  22  and the wireless communication portion  23  are electrically connected to the CPU  21 . The CPU  21  controls the reading device  2 . The flash ROM  22  stores various programs that are executed in order for the CPU  21  to control the reading device  2 . The flash ROM  22  also stores data that represents the trajectory of the electronic pen  3  that writes the information on the paper medium  100  on the sensor boards  7 L and  7 R. The data that represents the trajectory of the electronic pen  3  that writes the information on the paper medium  100  on the sensor boards  7 L and  7 R is hereinafter referred to as stroke data. The stroke data represents the trajectory of the electronic pen  3  that writes the information on the paper medium  100 , using information of a plurality of positions of the electronic pen  3  that are detected over time by the sensor boards  7 L and  7 R. The stroke data includes coordinate information that represents each of a plurality of positions on the trajectory of the electronic pen  3 . The wireless communication portion  23  is a controller that is used to execute near-field wireless communication with an external electronic device. 
         [0029]    The sensor board  7 L is electrically connected to an application-specific integrated circuit (ASIC)  28 A of the sensor control board  28 . The ASIC  28 A performs processing to generate the stroke data based on a writing operation when the writing operation by the electronic pen  3  is performed on the sensor board  7 L. This will be explained in more detail below. The sensor board  7 R is electrically connected to an ASIC  29 A of the sensor control board  29 . The ASIC  29 A performs processing to generate the stroke data based on a writing operation when the writing operation by the electronic pen  3  is performed on the sensor board  7 R. This will be explained in more detail below. The ASIC  28 A on the master side is directly connected to the CPU  21 . The ASIC  29 A on the slave side is connected to the CPU  21  via the ASIC  28 A. 
         [0030]    The principle of acquiring the stroke data in a case where the writing operation is performed on the sensor boards  7 L and  7 R by the electronic pen  3  will be briefly explained. The CPU  21  controls the ASIC  28 A and the ASIC  29 A and causes a current (a transmission current for excitation) of a specific frequency to flow to each one of the loop coils of the sensor boards  7 L and  7 R. In this way, a magnetic field is generated from each of the loop coils of the sensor boards  7 L and  7 R. For example, if the user uses the electronic pen  3  to write the information on the paper medium  100  that is fixed to the reading device  2  in this state, the electronic pen  3  comes very close to one of the sensor boards  7 L and  7 R. Thus, a resonance circuit of the electronic pen  3  resonates as a result of electromagnetic induction and an induction field is generated. 
         [0031]    Next, the CPU  21  controls the ASIC  28 A and the ASIC  29 A and stops the generation of the magnetic field from the loop coils of each of the sensor boards  7 L and  7 R. Further, the induction field generated from the resonance circuit of the electronic pen  3  is received by the loop coils of each of the sensor boards  7 L and  7 R. The CPU  21  controls the ASIC  28 A and the ASIC  29 A and causes a signal current (a reception current) that is flowing through each of the loop coils of the sensor boards  7 L and  7 R to be detected. The ASIC  28 A and the ASIC  29 A perform this operation one by one for all of the loop coils, and the position of the electronic pen  3  is detected as coordinate information based on the reception current. 
         [0032]    When the user is using the electronic pen  3  to write the information on the paper medium  100 , a writing pressure is applied to the core body  31 . The inductance of the coil  32  varies depending on the writing pressure applied to the core body  31 . In this way, the resonance frequency of the resonance circuit of the electronic pen  3  changes. The CPU  21  detects the change in the resonance frequency (a phase change) and identifies the writing pressure applied to the electronic pen  3 . More specifically, the CPU  21  can determine whether or not the information is being written on the paper medium  100  by the identified writing pressure from the electronic pen  3 . In a case where the CPU  21  determines that the information is being written on the paper medium  100 , the CPU  21  acquires the stroke data that includes the coordinate information representing the position of the electronic pen  3 , and stores the acquired stroke data in the flash ROM  22 . 
         [0033]    The reading device  2  may detect the position of the electronic pen  3  using another method. For example, the reading device  2  may be provided with a touch panel. It is preferable that the driving method of the touch panel be a resistive membrane type. The paper medium  100  may be placed on top of the touch panel. The CPU  21  may detect the position at which the writing pressure is applied from the electronic pen  3  via the touch panel, in a case where the operation of writing the information on the paper medium  100  is performed by the electronic pen  3 . 
         [0034]    Next, the electrical configuration of the PC  4  will be explained. The PC  4  includes a CPU  41 , which controls the PC  4 . The CPU  41  is electrically connected to a hard disk drive (HDD)  42 , a RAM  43 , a wireless communication portion  44 , an input circuit  45 , and an output circuit  46 . The HDD  42  stores various data such as various programs that are executed by the CPU  41 . The HDD  42  also stores a correction program, which is used to execute first main processing (refer to  FIG. 5 ) that will be explained below. 
         [0035]    The PC  4  includes a medium reading device (a CD-ROM drive, for example) that is not shown in the drawings. The PC  4  can read a correction program that is stored in a storage medium (a CD-ROM, for example) using the medium reading device and can install the correction program in the HDD  42 . The correction program may be received from an external device (not shown in the drawings) that is connected to the PC  4  or from a network, and installed in the HDD  42 . 
         [0036]    The RAM  43  stores a variety of temporary data are stored in the RAM  43 . The wireless communication portion  44  is a controller that performs near-field wireless communication with an external electronic device. The input circuit  45  performs control to transmit an instruction to the CPU  41  from an input portion  47  (such as a mouse, a keyboard, a touch panel, or the like). The output circuit  46  performs control to display an image on a display  48  in accordance with an instruction from the CPU  41 . 
         [0037]    In the present embodiment, the near-field wireless communication can be performed between the wireless communication portion  23  of the reading device  2  and the wireless communication portion  44  of the PC  4 . The reading device  2  transmits the stroke data stored in the flash ROM  22  to the PC  4  by the near-field wireless communication. The communication when the stroke data is transmitted from the reading device  2  to the PC  4  is not limited to the wireless communication and wired communication may be used. 
         [0038]    An example of the paper sheet  120  (namely, a paper sheet  701 ) of the paper medium  100  will be explained with reference to  FIG. 3 . In the following explanation, the lower side, the upper side, the left side, and the right side in  FIG. 3  respectively define the front side, the rear side, the left side, and the right side of the paper sheet  701 . The up-down direction, or a direction that is close to the up-down direction, is also referred to as “vertical” and the left-right direction, or a direction that is close to the left-right direction, is also referred to as “horizontal.” The paper sheet  701  is a page of the paper medium  100 . An illustration of the other pages of the paper medium  100  is omitted. 
         [0039]    As shown in  FIG. 3 , a mark arrangement area  705  is provided on the left portion of the paper sheet  701 . A plurality of marks (three marks, in the present embodiment)  711  to  713  are printed aligned in the up-down direction in the mark arrangement area  705 . Each of the marks  711  to  713  has a grid shape that is formed by 4 vertical dotted lines and three horizontal dotted lines. In the following explanation, when the marks  711  to  713  are referred to collectively, or when one of the marks  711  to  713  is not specified, the marks  711  to  713  are referred to as a mark  71  or marks  71 . 
         [0040]    A writing area  706  is provided to the right of the mark arrangement area  705 . A plurality of ruled lines  708  are printed in the writing area  706 . A dividing line  707  that runs in the up-down direction is printed between the mark arrangement area  705  and the writing area  706 . 
         [0041]    The coordinate information stored in the HDD  42  will be explained with reference to  FIG. 4 . In the following explanation, the coordinate in the left-right direction in  FIG. 4  is the X coordinate and the coordinate in the up-down direction in  FIG. 4  is the Y coordinate. The HDD  42  stores reference marks  721  to  723  and peripheral areas  731  to  733 . More specifically, the HDD  42  stores, as coordinate information on the sensor board  7 L, the reference marks  721  to  723  and the peripheral areas  731  to  733 .  FIG. 4  illustrates positions on the sensor board  7 L that correspond to the reference marks  721  to  723  and the peripheral areas  731  to  733 , which are stored as the coordinate information in the HDD  42 .  FIG. 4  illustrates, of the entire sensor board  7 L, only a range corresponding to the paper sheet  701 . The HDD  42  also stores reference marks and peripheral areas for the sensor board  7 R, similarly to the case of the sensor board  7 L, but an explanation thereof is omitted here. 
         [0042]    As shown in  FIG. 4 , the reference marks  721  to  723  are each an aggregate of coordinate information for a grid shape corresponding to each of the marks  711  to  713  (refer to  FIG. 3 ) on the paper sheet  701 .  FIG. 4  illustrates only upper left coordinate information (X 11 , Y 11 ) and lower right coordinate information (X 12 , Y 12 ) for the reference mark  721 , but the HDD  42  stores coordinate information of coordinates corresponding to lines of the grid-shaped reference mark  721 . In a similar manner to the reference mark  721 , the HDD  42  also stores coordinate information of the reference mark  722 , which includes upper left coordinate information (X 13 , Y 13 ) and lower right coordinate information (X 14 , Y 14 ), and coordinate information of the reference mark  723 , which includes upper left coordinate information (X 15 , Y 15 ) and lower right coordinate information (X 16 , Y 16 ). 
         [0043]    Each of the peripheral areas  731  to  733  is an aggregate of coordinate information of an area surrounding each of the reference marks  721  to  723 .  FIG. 4  illustrates only upper left coordinate information (X 1 , Y 1 ) and lower right coordinate information (X 2 , Y 2 ) for the peripheral area  731 , but the HDD  42  stores coordinate information of an area that includes a square external shape and the interior of the square external shape. In a similar manner to the peripheral area  731 , the HDD  42  stores coordinate information of the peripheral area  732 , which includes upper left coordinate information (X 3 , Y 3 ) and lower right coordinate information (X 4 , Y 4 ), and coordinate information of the peripheral area  733 , which includes upper left coordinate information (X 5 , Y 5 ) and lower right coordinate information (X 6 , Y 6 ). The peripheral area  732  is set in a range in which it is assumed that a trajectory of a line is to be positioned in a case where the user writes the line along the mark  71 , even if the paper sheet  701  is arranged such that the paper sheet  701  is tilted with respect to the sensor board  7 L (refer to  FIG. 6 , for example). In the following explanation, when the reference marks  721  to  723  are collectively referred to, or when one of the reference marks  721  to  723  is not specified, the reference marks  721  to  723  are referred to as a reference mark  72  or reference marks  72 . When the peripheral areas  731  to  733  are collectively referred to, or when one of the peripheral areas  731  to  733  is not specified, the peripheral areas  731  to  733  are referred to as a peripheral area  73  or peripheral areas  73 . 
         [0044]    The first main processing will be explained with reference to  FIG. 5 . The first main processing is processing to correct a position of a trajectory based on the stroke data etc. The user may operate the input portion  47  to input a command to activate an application that executes the first main processing. In this case, the CPU  41  of the PC  4  reads, from the HDD  42 , programs to execute the application and expands the programs into the RAM  43 . A correction program for the CPU  41  to perform the first main processing is included in the programs to execute the application. The CPU  41  performs the first main processing in accordance with commands of the correction program. The first main processing ends when the input portion  47  is operated and a command is input to end the application that executes the first main processing. 
         [0045]    In the following explanation, a specific example is exemplified in which the user writes on the paper sheet  701 , as shown in  FIG. 6 . In the specific example, the user may open the paper medium  100  and may arrange the paper sheet  701  on the sensor board  7 L. At this time, it is assumed that the paper sheet  701  is arranged such that the paper sheet  701  is tilted with respect to the sensor board  7 L. The user may use the electronic pen  3  to write text in the writing area  706  of the paper sheet  701 . After that, the user may use the electronic pen  3  to write a line along the mark  711 . 
         [0046]    As shown in  FIG. 5 , in the first main processing, connection settings are performed with the CPU  21  of the reading device  2  via the wireless communication portions  23  and  44 , and a state is set in which communication between the CPU  21  of the reading device  2  and the CPU  41  of the PC  4  is possible (step S 11 ). Next, it is determined whether or not the stroke data has been acquired (step S 12 ). If the stroke data has not been acquired (no at step S 12 ), the processing at step S 12  is repeated. 
         [0047]    The CPU  21  of the reading device  2  acquires the stroke data while the writing is being performed on the paper sheet  701 . The CPU  21  transmits the acquired stroke data to the CPU  41  of the PC  4 . If the CPU  41  has received the transmitted stroke data (yes at step S 12 ), the CPU  41  refers to the peripheral areas  73  stored in the HDD  42  and determines whether or not the stroke data acquired at step S 12  is included in one of the peripheral areas  73  (step S 13 ). More specifically, the CPU  41  determines whether or not the trajectory of the electronic pen  3  represented by the stroke data is included in one of the peripheral areas  73 . If the stroke data is not included in any of the peripheral areas  73  (no at step S 13 ), the stroke data is stored in the HDD  42 , which is a non-volatile storage device (step S 14 ). The CPU  41  then returns the processing to step S 12 . 
         [0048]    In the specific example, as shown in  FIG. 6 , the text “13:00 Meeting” is written in the writing area  706 . In this case, the stroke data corresponding to the written text is acquired (yes at step S 12 ). It is then determined that the stroke data is not included in any of the peripheral areas  73  (no at step S 13 ) and the stroke data of the trajectory of the text “13:00 Meeting” is stored in the HDD  42  (step S 14 ). 
         [0049]    At step S 13 , if it is determined that the stroke data is included in one of the peripheral areas  73  (yes at step S 13 ), it is determined whether or not the trajectory based on the stroke data that is determined to be included in one of the peripheral areas  73  is the trajectory representing the mark  71  (step S 15 ). If the trajectory based on the stroke data is not the trajectory representing the mark  71  (no at step S 15 ), the CPU  41  returns the processing to step S 12 . 
         [0050]    In the specific example, as shown in  FIG. 6 , after writing the text “13:00 Meeting” using the electronic pen  3 , the user may write the line along the mark  711 . At step S 15 , as an example, it is assumed that it is determined that the trajectory based on the stroke data is the trajectory representing the mark  711  in a case where the three horizontal lines and the four vertical lines are written. As the paper sheet  701  is tilted with respect to the sensor board  7 L, the three horizontal lines and the four vertical lines are also tilted. 
         [0051]    In a case where the user starts to write the line along the mark  711  from the first line, it is determined that the stroke data is included in the peripheral area  73  (yes at step S 13 ). However, while the three horizontal lines and the four vertical lines are not yet written, the trajectory based on the stroke data is determined not to be the trajectory representing the mark  711  (no at step S 15 ). Then, the CPU  41  repeats the processing at steps S 12 , S 13 , and S 15 . Although not shown in the drawings, the stroke data included in the peripheral area  73  is temporarily stored in the RAM  43 . Then, as shown in  FIG. 6 , in a case where the three horizontal lines and the four vertical lines are written, the trajectory based on the stroke data is determined to be the trajectory representing the mark  711  (yes at step S 15 ). The trajectory representing the mark  711  is the trajectory written by the user using the electronic pen  3 . Thus, in the trajectory representing the mark  711 , some of the lines may be short or the angle of the lines may be displaced from the mark  71 , as shown in  FIG. 6 . 
         [0052]    Next, if the trajectory based on the stroke data is the trajectory representing the mark  71  (yes at step S 15 ), the position of the trajectory of the stroke data acquired at step S 12  is corrected based on the trajectory of the stroke data included in the peripheral area  73  and on the amount of displacement of the position of the reference mark  72  that is stored in the HDD  42  (step S 16 ). 
         [0053]    In the following explanation, the stroke data that is included in the peripheral area  73  will be referred to as reference stroke data. At step S 16 , as an example, the position of the trajectory of the stroke data is corrected in the following manner. First, the CPU  41  calculates an angle displacement amount between each of the four vertical lines of the trajectory represented by the reference stroke data (the trajectory along the mark  711 ) and each of the four vertical lines of the reference mark  721  stored in the HDD  42 . The CPU  41  then calculates an average value of the four angle displacement amounts. The CPU  41  tilts the trajectory represented by the reference stroke data by the calculated average value of the angle displacement amounts. In this way, the tilt of the trajectory represented by the reference stroke data is close to the tilt of the reference mark  72 . Additionally, the CPU  41  moves the trajectory represented by the reference stroke data such that a displacement amount between the three horizontal lines and the four vertical lines of the reference mark  721  and the three horizontal lines and the four vertical lines of the trajectory represented by the reference stroke data is close to zero. More specifically, the CPU  41  moves the trajectory represented by the reference stroke data to a position in which as many as possible of points (coordinates) represented by the coordinate information of the three horizontal lines and the four vertical lines of the reference mark  72  are in the same position as points (coordinates) represented by the coordinate information of the three horizontal lines and the four vertical lines of the trajectory represented by the reference stroke data. In this manner, the position of the trajectory represented by the reference stroke data comes close to the position of the reference mark  72 . The CPU  41  also tilts the trajectory of the stroke data based on the text written in the writing area  706  by the same angle of tilt of the trajectory represented by the reference stroke data, and moves the trajectory of the stroke data based on the text by the same movement amount. The position of the trajectory of the stroke data acquired at step S 12  is corrected in this manner. 
         [0054]    Next, the trajectory based on the reference stroke data is corrected to a shape that is set in advance (step S 17 ). In the present embodiment, the shape that is set in advance is assumed to be the shape of the reference mark  72  that is stored in the HDD  42 . In this case, the trajectory based on the reference stroke data is corrected to the shape of the reference mark  72 . Next, the corrected stroke data is stored in the HDD  42 , which is the non-volatile storage device (step S 18 ). The corrected stroke data is the stroke data corrected at step S 16  and the reference stroke data corrected at step S 17 . At step S 18 , the corrected stroke data may be stored in the HDD  42  as image data that includes the trajectory based on the stroke data. After the processing at step S 18 , the CPU  41  returns the processing to step S 12 . 
         [0055]    The CPU  41  can display the stroke data stored at step S 18  on the display  48 . More specifically, the CPU  41  can display the trajectory based on the stroke data stored at step S 18  on the display  48 . As shown in  FIG. 7 , for example, the position of the text “13:00 Meeting” that was written on the paper sheet  701  in the tilted state is corrected and the stroke data is displayed on the display  48 . In  FIG. 6 , of the lines indicating the mark  711 , some of the lines are short and the angle of some of the lines is displaced from the mark  711 . However, the lines indicating the mark  711  are corrected to lines along the mark  711  and displayed. The dividing line  707 , the ruled lines  708 , and the marks  712  and  713  are not included in the stroke data, but are synthesized with the trajectory based on the stroke data stored at step S 18  and are displayed together. The dividing line  707 , the ruled lines  708 , and the marks  712  and  713  need not necessarily be displayed. 
         [0056]    Next, a second embodiment will be explained with reference to  FIG. 8 . In the second embodiment, second main processing shown in  FIG. 8  is performed. In  FIG. 8 , the same reference numerals are assigned to processing that is the same as that of the first main processing (refer to  FIG. 5 ) of the first embodiment and a detailed explanation thereof is omitted here. In the present embodiment, paper medium information, which is information relating to the paper medium  100 , is included in the reference stroke data. The paper medium information of the present embodiment is page information. 
         [0057]    As shown in  FIG. 8 , in the second main processing, the processing at steps S 11  to S 14  is performed in a similar manner to the first main processing. In a case where it is determined that the stroke data acquired at step S 12  is included in one of the peripheral areas  73  (yes at step S 13 ), the page information, which is the paper medium information, is acquired based on the reference stroke data that is included in the peripheral area  73  (step S 21 ). The acquisition of the page information is performed, for example, by a known pattern matching method and is performed by identifying a numeral that is included in the trajectory based on the reference stroke data. For example, as shown in  FIG. 9 , when the user writes the page number “32” along the lines of the mark  711  using the electronic pen  3 , the page number “32” is acquired based on the reference stroke data of the written numeral“32.” 
         [0058]    Next, as a result of the processing at step S 21 , it is determined whether or not the paper medium information has been acquired (step S 22 ). If the paper medium information has not been acquired (no at step S 22 ), the CPU  41  returns the processing to step S 12 . If the paper medium information has been acquired (yes at step S 22 ), the position of the trajectory of the stroke data acquired at step S 12  is corrected based on the amount of displacement between the trajectory based on the stroke data included in the peripheral area  73  and the position of the reference mark  72  stored in the HDD  42  (step S 23 ). 
         [0059]    At step S 23 , as an example, the position of the trajectory of the stroke data is corrected in the following manner. First, the CPU  41  calculates the angle displacement amount between the vertical lines of the trajectory represented by the reference stroke data and the vertical lines of the reference mark  721  stored in the HDD  42 . The CPU  41  then calculates an average value of the angle displacement amounts. The CPU  41  tilts the trajectory represented by the reference stroke data by the calculated average value of the angle displacement amounts. In this way, the tilt of the trajectory represented by the reference stroke data is close to the tilt of the reference mark  721 . Additionally, the CPU  41  moves the trajectory represented by the reference stroke data such that a displacement amount between the lines of the numeral of the trajectory represented by the reference stroke data and the three horizontal lines and the four vertical lines of the reference mark  721  is close to zero. More specifically, the CPU  41  moves the trajectory represented by the reference stroke data to a position in which as many as possible of points (coordinates) represented by the coordinate information of the lines of the numeral of the trajectory represented by the reference stroke data are in the same position as points (coordinates) represented by the coordinate information of the three horizontal lines and the four vertical lines of the reference mark  721 . In this manner, the position of the trajectory represented by the reference stroke data comes close to the position of the reference mark  721 . The CPU  41  also tilts the trajectory of the stroke data based on the text written in the writing area  706  by the same angle of tilt of the trajectory represented by the reference stroke data, and moves the trajectory of the stroke data based on the text by the same movement amount. The position of the trajectory of the stroke data acquired at step S 12  is corrected in this manner. 
         [0060]    Next, the trajectory based on the reference stroke data is corrected to a shape that is set in advance (step S 24 ). In the present embodiment, the shape that is set in advance is assumed to be a numeral of a predetermined font that is stored in the HDD  42 . For example, the numeral “32” that is written in straight lines along the mark  711  as shown in  FIG. 9  is corrected to the numeral “32” of the predetermined font, as shown in  FIG. 10 . Next, processing is performed in accordance with the paper medium information acquired at step S 21  (step S 25 ). In the present embodiment, the paper medium information is the page information. At step S 25 , the page information acquired at step S 21  is associated with the stroke data corrected at step S 23  and with the stroke data corrected at step S 24 , and is stored in the non-volatile HDD  42 . In this manner, the corrected stroke data is stored as the information of the page “32.” 
         [0061]    An image based on the stroke data stored at step S 25  is shown in  FIG. 10 . As shown in  FIG. 10 , the position of the text “13:00 Meeting” (refer to  FIG. 9 ) that was written on the paper sheet  701  in a tilted state is corrected and displayed. Further, the numeral “32” (refer to  FIG. 9 ) that represents the page information and that is written in straight lines along the mark  711  is corrected to the numeral of the predetermined font. 
         [0062]    Next, the CPU  41  returns the processing to step S 12 , and repeats the processing from step S 12  onward. In other words, each time the CPU  41  determines that the stroke data is included in one of the peripheral areas  73  (yes at step S 13 ), the position of the trajectory of the stroke data acquired at step S 12  is corrected based on the displacement amount between the position of the trajectory based on the reference stroke data and the position of the reference mark  72  (step S 23 ). Further, each time the CPU  41  determines that the stroke data is included in one of the peripheral areas  73  (yes at step S 13 ), the CPU  41  acquires the page information, which is the paper medium information based on the reference stroke data (step S 21 ). Then, the CPU  41  associates the acquired page information with the corrected stroke data and stores the associated information in the HDD  42  (step S 25 ). Thus, the PC  4  can manage the positionally corrected stroke data page by page. 
         [0063]    For example, as shown in  FIG. 10 , after the stroke data of the text “13:00 Meeting” and the page information “32” are stored at step S 25  in the HDD  42 , the user may open another page of the paper medium  100 . After that, the user may once more open the paper sheet  701  of the page  32  of the paper medium  100 . At that time, it is assumed that the paper sheet  701  is tilted with respect to the sensor board  7 L. The user may add text using the electronic pen  3  and may write the number “32” on the mark  712 , which is the mark  71  that is second from the top. In this case, the CPU  41  acquires the page information that is the paper medium information based on the reference stroke data (step S 21 ). Then, the CPU  41  corrects the stroke data corresponding to the added text (step S 23 ) and corrects the trajectory based on the reference stroke data to the numeral of the predetermined font (step S 24 ). Then, in addition to the stroke data corresponding to the text “13:00 Meeting”, the CPU  41  associates the stroke data corresponding to the corrected added text with the page “32” and stores the associated information (step S 25 ). In this manner, after the user has written on the paper sheet  701 , even if the user opens the paper sheet  701  of another page and then once more returns to the original page and writes on the paper sheet  701  again, it is possible to add the corrected stroke data to the page information corresponding to the original page. As a result, convenience for the user may be improved. The page information “32” that is written the second time need not necessarily be displayed on the display  48 . The page information “32” may be moved to the center of the lower portion etc. of the paper sheet  701  and displayed on the display  48 . The page information “32” need not necessarily be displayed on the display  48 . 
         [0064]    In the present embodiment, it is possible to correct the position of the trajectory based on the stroke data, based on the reference stroke data included in the stroke data acquired at step S 12  (refer to  FIG. 5  and  FIG. 8 ) (refer to step S 16  in  FIG. 5  and step S 23  in  FIG. 8 ). As a result, it is not necessary to provide a separate sensor for the purpose of position correction. It is thus possible to reduce costs while correcting positional displacement of the trajectory based on the stroke data that has been written. 
         [0065]    The trajectory based on the reference stroke data is corrected to a shape that is set in advance (refer to step S 17  in  FIG. 5  and step S 24  in  FIG. 8 ). As a result, as shown in  FIG. 7  and  FIG. 10 , the corrected trajectory becomes a neater shape than the shape of the trajectory (refer to  FIG. 6  and  FIG. 9 ) that is written using the electronic pen  3 . Thus, when the trajectory based on the reference stroke data is displayed on the display, the appearance of the displayed trajectory may be improved. 
         [0066]    In a case where the user writes along the mark  71 , the stroke data of the trajectory along the mark  71  is positioned in the peripheral area  73 . Then, the corrected stroke data is automatically stored in the HDD  42 , which is the non-volatile storage device (step S 18  in  FIG. 5  and step S 25  in  FIG. 8 ). Therefore, simply by the user writing in the position corresponding to the peripheral area  73 , the corrected stroke data is automatically stored in the HDD  42 , and thus the convenience for the user may be improved. 
         [0067]    The present disclosure is not limited to the above-described embodiments, and various modifications are possible. For example, the method to correct the position of the trajectory of the stroke data at step S 16  of the first main processing shown in  FIG. 5  and at step S 23  of the second main processing shown in  FIG. 8  is not limited to the method of the above-described embodiments, and another method may be used. For example, the CPU  41  may correct the position of the trajectory of the stroke data such that the four corners of the external shape of the reference stroke data are aligned with the four corners of the reference mark  72 . Further, the method to correct the shape of the trajectory based on the reference stroke data at step S 17  of the first main processing and at step S 24  of the second main processing is not limited to the method of the above-described embodiments, and another method may be used. The shape of the mark  71  and of the reference mark  72  is not limited to the shape of the above-described embodiment and another shape may be adopted. At step S 24  of the second main processing, the trajectory based on the reference stroke data (the numeral) is corrected to the numeral of the predetermined font, but the present disclosure is not limited to this example. For example, the numeral may be corrected to a so-called seven-segment display. The number of each of the marks  71 , the reference marks  72 , and the peripheral areas  73  is not limited to three. For example, only one mark  71 , one reference mark  72  and one peripheral area  73  may be provided, or five of each of the marks  71 , the reference marks  72  and the peripheral areas  73  may be provided. 
         [0068]    The marks  71  may be provided in the four corners of the paper sheet  701 , and the reference marks  72  and the peripheral areas  73  may be provided in positions corresponding to the marks  71  in the four corners. At step S 15  of the first main processing shown in  FIG. 5 , it may be determined that the trajectory based on the stroke data is a trajectory indicating the mark when lines have been written along all of the marks  71  provided in the four corners. In this case, when the correction of the position of the stroke data is performed at step S 16 , the position of the trajectory of the stroke data may be corrected based on the stroke data of the trajectory written along the marks  71  in the four corners. In this case, as there is a greater number of pieces of reference stroke data used in the correction, the accuracy when correcting the position of the paper sheet  701  is further improved. 
         [0069]    At step S 18  of the first main processing and step S 25  of the second main processing, the CPU  41  need not necessarily store the reference stroke data after correction that has been corrected at step S 17  and step S 24 , respectively. The processing at step S 17  and step S 24  need not necessarily be performed. The stroke data may be stored in the RAM  43  at steps S 14  and S 18  of the first main processing and at steps S 14  and S 25  of the second main processing. 
         [0070]    The first main processing and the second main processing need not necessarily be performed by the CPU  41  of the PC  4 . For example, the first main processing and the second main processing may be performed by the CPU  21  of the reading device  2 . In this case, the various data of the correction program etc. may be stored in the flash ROM  22  in place of the HDD  42  and the RAM  43 . Then, at step S 18  of the first main processing or at step S 25  of the second main processing, the CPU  21  may transmit the corrected stroke data that is stored in the flash ROM  22  to the PC  4 . The reading device  2  may be connected to a mobile terminal etc. instead of being connected to the PC  4 , and a CPU of the mobile terminal etc. may perform the first main processing and the second main processing. 
         [0071]    In the second embodiment, the paper medium information is the page information and the corrected stroke data is associated with the page information and stored (step S 25 ), but the present disclosure is not limited to this example. For example, the paper medium information may be other information, such as date information, tag information, an electronic mail address etc. At this time, the shape of the mark  71 , the reference mark  72 , and the peripheral area  73  may be a shape that accords with the type of the paper medium information. 
         [0072]    In a case where the paper medium information is the date information, the user may write a numeral of the date along the lines of the mark  71  using the electronic pen  3 . The CPU  41  may acquire the reference stroke data that accords with the numeral of the date that are written (yes at step S 12 ) and may acquire the date information (step S 21 ). Then, at step S 25 , the CPU  41  may associate the stroke data corrected at steps S 23  and S 24  with the date information and may store the associated information in the HDD  42 . In this manner, the corrected stroke data may be managed according to the date. 
         [0073]    In a case where the paper medium information is the tag information, a tag information data table  95  shown in  FIG. 11  may be stored in the HDD  42 . Patterns and tag information may be stored in the tag information data table  95  in association with each other. Each of the patterns may be a type of the reference mark  72 , and may be a pattern in which at least a part of the area on the inside of the grid-shaped reference mark  72  of the first embodiment is filled in. The tag information may be classification information. The user may operate the PC  4  to associate the desired tag information with the pattern and to store the associated information in the HDD  42 . In the tag information data table  95  shown in  FIG. 11 , schedule, memo, address book, meeting content, explanatory document, and morning meeting etc. are registered as the tag information. 
         [0074]    It is assumed that the user uses the electronic pen  3  to write the pattern in the mark  71  and the CPU  41  acquires a pattern  741  or a pattern  742  shown in  FIG. 12  as the reference stroke data (yes at step S 12  shown in  FIG. 8 ). In a case where the paper medium  100  is tilted with respect to the sensor board  7 L, the patterns  741  and  742  are also tilted. The pattern  741  is formed by filling in, using the electronic pen  3 , the upper and lower areas of the left side portion and the upper and lower areas of the center portion of the grid-shaped mark  71 . The pattern  742  is formed by drawing a line through the upper and lower areas of the left side portion and a line through the upper and lower areas of the center portion of the grid-shaped mark  71 . At step S 21 , the CPU  41  may acquire the tag information, which is the paper medium information, based on the reference stroke data of the pattern  741  or the pattern  742 . At that time, the CPU  41  may refer to the tag information data table  95  shown in  FIG. 11  and may acquire the tag information “Meeting content”, which corresponds to the pattern in which the upper and lower areas of the left side portion and the upper and lower areas of the center portion of the reference mark  72  are filled in. At step S 25 , the CPU  41  may associate the tag information “Meeting content” with the stroke data corrected at steps S 23  and S 24  and may store the associated information. The pattern  743  shown in  FIG. 12  may be a pattern shown by the reference stroke data corrected at step S 24 . The pattern  741  may be the pattern that is drawn by hand by the user, therefore the areas are not accurately filled in, and the lines are also displaced from the mark  71 . In the pattern  742 , the lines are drawn through the upper and lower areas of the left side portion and through the upper and lower areas of the center portion. However, in the pattern  743  that is corrected at step S 24 , the angles of the lines may be corrected and the filled in areas or the areas through which the lines are drawn may be accurately filled in. 
         [0075]    Although not shown in the drawings, in a case where the paper medium information is the electronic mail address, patterns similar to the patterns shown in  FIG. 11  may be associated with electronic mail addresses and may be stored in the HDD  42 . Then, similarly to the case in which the paper medium information is the tag information, the electronic mail address corresponding to the pattern may be acquired (step S 21 ). Then, at step S 25 , the stroke data corrected at steps S 23  and S 24  may be automatically transmitted to the electronic mail address acquired at step S 21 . 
         [0076]    As in the above-described second embodiment and modified example, in the second main processing, the paper medium information is acquired (step S 21 ) and the processing according to the paper medium information is performed (step S 25 ). Simply by the user writing on the mark  71  in the peripheral area  73 , the position of the stroke data is corrected at steps S 23  and S 24  and the processing according to the paper medium information is performed at step S 25 . Thus, convenience for the user may be improved. 
         [0077]    The apparatus and methods described above with reference to the various embodiments are merely examples. It goes without saying that they are not confined to the depicted embodiments. While various features have been described in conjunction with the examples outlined above, various alternatives, modifications, variations, and/or improvements of those features and/or examples may be possible. Accordingly, the examples, as set forth above, are intended to be illustrative. Various changes may be made without departing from the broad spirit and scope of the underlying principles.