Patent Publication Number: US-2006017709-A1

Title: Touch panel apparatus, method of detecting touch area, and computer product

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to a technology for preventing an error due to detection of two touch areas in a touch panel apparatus.  
      2. Description of the Related Art  
      Conventionally, a touch panel apparatus that detects a position touched with a touch pen or a finger on coordinates is proposed (see, for example, Japanese Patent Application Laid-open Nos. 2002-149348, 2001-312370, and 2001-306241). The touch panel apparatus has a touch panel provided on the surface of a liquid-crystal display (LCD), a plasma display panel (PDP), or a cathode ray tube (CRT). The touch panel detects a position on coordinates at which a touch pen or the like touches on the touch panel.  
      Specifically, plural light-emitting elements (not shown) are laid out on one vertical side  11   a  and one horizontal side  11   b  of a touch panel  11  of a touch panel apparatus  10  shown in  FIG. 11 . Plural light-receiving elements (not shown) are laid out at the other vertical side  11   c  and the other horizontal side  11   d  that are opposite to the light-emitting elements. The touch panel is provided on the surface of the LCD, the PDP, or the CRT (not shown).  
      In the above configuration, when a touch pen  20  touches an optional touch area a 1  on the touch panel  11 , the touch area a 1  shields light emitted from the light-emitting elements on the vertical side  11   a  and light emitted from the light-emitting elements on the horizontal side  11   b . Consequently, the light-receiving elements on the opposite vertical side  11   c  and on the opposite horizontal side  11   d  respectively cannot receive the lights that are emitted and shielded. Accordingly, the touch area a 1  (x-y coordinates) is detected from the layout positions of the light-receiving elements that do not receive the lights.  
      According to the conventional touch panel apparatus  10 , when the touch pen  20  touches on the touch panel  11 , a hand  30  also touches on the touch panel  11  by mistake. In this case, as shown in  FIG. 11 , a touch area a 2  on which the hand  30  touches is also detected in addition to the primary touch area a 1 . The detection of the two touch areas causes an error.  
     SUMMARY OF THE INVENTION  
      It is an object of the present invention to at least solve the problems in the conventional technology.  
      A touch panel apparatus according to one aspect of the present invention includes a touch panel provided on a display; a touch-area detecting unit that detects a touch area when an object touches on a surface of the touch panel; and a determining unit that compares, when the touch-area detecting unit detects two touch areas, dimensions of the two touch areas, validates a touch area having a smaller dimension, and invalidates a touch area having a larger dimension.  
      A touch panel apparatus according to another aspect of the present invention includes a touch panel provided on a display; a touch-area detecting unit that detects a touch area when an object touches on a surface of the touch panel; and a determining unit that compares, when the touch-area detecting unit detects two touch areas, temporal change rates of dimensions of the two touch areas, validates a touch area having a larger change rate, and invalidates a touch area having a smaller change rate.  
      A method of detecting a touch area on a touch panel, according to still another aspect of the present invention, includes detecting a touch area when an object touches on a surface of the touch panel; and determining including comparing, when two touch areas are detected at the detecting, dimensions of the two touch areas, validating a touch area having a smaller dimension, and invalidating a touch area having a larger dimension.  
      A method of detecting a touch area on a touch panel, according to still another aspect of the present invention, includes detecting a touch area when an object touches on a surface of the touch panel; and determining including comparing, when two touch areas are detected at the detecting, temporal change rates of dimensions of the two touch areas, validating a touch area having a larger change rate, and invalidating a touch area having a smaller change rate.  
      A computer-readable recording medium according to still another aspect of the present invention stores a computer program that causes a computer to execute the above methods according to the present invention.  
      The above and other objects, features, advantages and technical and industrial significance of this invention will be better understood by reading the following detailed description of presently preferred embodiments of the invention, when considered in connection with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a block diagram of a touch panel apparatus according to an embodiment of the present invention;  
       FIG. 2  depicts a user profile information registration screen according to the present embodiment;  
       FIG. 3  is an explanatory diagram of a registration operation of user profile information according to the present embodiment;  
       FIG. 4  is another explanatory diagram of a registration operation of user profile information according to the present embodiment;  
       FIG. 5  is a flowchart for explaining the operation of drawing characters with a touch pen;  
       FIG. 6  is an explanatory diagram of the drawing operation with the touch pen;  
       FIG. 7  is a cross-sectional diagram of the touch panel apparatus in the drawing operation cut along a line A-A;  
       FIG. 8  is a graph of a temporal change of dimensions of a touch area ar 1  shown in  FIG. 7 ;  
       FIG. 9  is a graph of a temporal change of dimensions of a touch area ar 2  shown in  FIG. 7 ;  
       FIG. 10  is a block diagram of a computer system for the touch panel apparatus according to the present embodiment; and  
       FIG. 11  is a schematic of a conventional touch panel apparatus. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Exemplary embodiments of the present invention will be explained below in detail with reference to the accompanying drawings. It should be noted that the invention will not be limited by the present embodiments.  
       FIG. 1  is a block diagram of a touch panel apparatus  100  according to one embodiment of the present invention. In  FIG. 1 , a display unit  101  is an LCD, a PDP, or a CRT, which displays various kinds of information. A touch panel  102  is provided on the surface of the display unit  101 . The touch panel  102  detects a touch area (expressed by x-y coordinates, for example) on which a touch pen  120  held in a hand  130  touches.  
      A vertical light-emitting unit  103  and a vertical light-receiving unit  105  are disposed opposite to each other on both vertical sides of the display unit  101 , and have functions of emitting light (including an infrared ray) and receiving light respectively. In other words, the vertical light-emitting unit  103  and the vertical light-receiving unit  105  detect a shielding of light when the light is shielded with the touch pen  120  or the hand  130 . The vertical light-emitting unit  103  drives m light-emitting elements  104   1  to  104   m  that are laid out at predetermined intervals in a vertical direction, thereby making the light-emitting elements  104   1  to  104   m  generate light respectively.  
      The vertical light-receiving unit  105  drives m light-receiving elements  106   1  to  106   m  that are laid out at predetermined intervals in a vertical direction corresponding to the light-emitting elements  104   1  to  104   m  respectively, thereby making the light-receiving elements  106   1  to  106   m  receive light emitted from the light-emitting elements  104   1  to  104   m  respectively.  
      A horizontal light-emitting unit  107  and a horizontal light-receiving unit  109  are disposed opposite to each other on both horizontal sides of the display unit  101 , and have functions of emitting light (including an infrared ray) and receiving light respectively. The horizontal light-emitting unit  107  drives n light-emitting elements  108   1  to  108   n  that are laid out at predetermined intervals in a horizontal direction, thereby making the light-emitting elements  108   1  to  108   n  generate light respectively.  
      The horizontal light-receiving unit  109  drives n light-receiving elements  110   1  to  110   n  that are laid out at predetermined intervals in a horizontal direction corresponding to the light-emitting elements  108   1  to  108   n  respectively, thereby making the light-receiving elements  110   1  to  110   1  receive light emitted from the light-emitting elements  108   1  to  108   n  respectively.  
      A vertical scan unit  111  scans the vertical light-emitting unit  103  and the vertical light-receiving unit  105  in a vertical direction based on the control of a controller  113 . A horizontal scan unit  112  scans the horizontal light-emitting unit  107  and the horizontal light-receiving unit  109  in a horizontal direction based on the control of the controller  113 . The controller  113  controls each unit. Details of the operation of the controller  113  are described later. A storage unit  114  stores user profile information  115   1  to  115   s .  
      These user profile information  115   1  to  115   s  correspond to s users, and have user&#39;s specific information based on each user&#39;s habit of touching (by mistake) the touch panel with a hand when using the touch pen  120  and a structure of the hand. Details of the user profile information  115   1  to  115   s  are described later.  
      The operation of the touch panel apparatus according to one embodiment is explained below with reference to FIGS.  2  to  9 . First, the operation of registering user profile information into the storage unit  114  is explained with reference to FIGS.  2  to  4 . When a user operates an operating unit  116  to instruct a registration, the controller  113  makes a user profile information registration screen  140  shown in  FIG. 2  to be displayed in the display unit  101  (see  FIG. 1 ).  
      The user profile information registration screen  140  is used to register user profile information by making a user intentionally touch the touch panel with a hand. The user profile information registration screen  140  displays a user name input column  141 , a cross mark  142 , and a registration button  143 .  
      A user name is input to the user name input column  141 . The cross mark  142  displays a reference position at which a front end of the touch pen  12  (see  FIG. 1 ) is to be touched. The registration button  143  is used to register the user profile information.  
      A right-handed user operates the operating unit  116  to input “Nippon Taro” as a user name into the user name input column  141 . As shown in  FIG. 3 , in a state that the user holds the touch pen  120  in the right hand  130 , the front end of the touch pen  120  touches on the cross mark  142 , and the user intentionally touches on the user profile information registration screen  140  (the touch panel  102 ) with the hand  130 .  
      The front end of the touch pen  120  and a part of the hand  130  shield the light. The horizontal scan unit  112  and the vertical scan unit  111  detect a touch area a t1  and a touch area a t2 . A result of the detection is output to the controller  113 . The touch area a t1  corresponds to the area in which light is shielded by the front end of the touch pen  120 .  
      On the other hand, the touch area a t2  is positioned at the right of the touch area a t1 , and corresponds to the area in which light is shielded by a part of the hand  130 . Light-shielded dimensions of the touch area a t1  and the touch area a t2  shown in  FIG. 3  are larger than the actual light-shielding dimensions to facilitate the understanding of these areas. The user takes off the hand  130  holding the touch pen  120  from the user profile information registration screen  140 .  
      The controller  113  recognizes the x coordinates at the left end of the touch area a t1  and the touch area a t2  respectively, and generates the user profile information  115   1  covering the user name (“Nippon Taro”) that is input to the user name input column  141 , dimensions of the touch area a t1 , the x coordinate at the left end of the touch area a t1 , dimensions of the touch area a t2 , and the x coordinate at the left end of the touch area a t2 .  
      When the user presses the registration button  143 , the controller  113  registers the user profile information  115   1  into the storage unit  114 . Thereafter, user profile information of other users are also registered.  
      A drawing operation with the touch pen  120  will be explained next with reference to FIGS.  5  to  9 .  FIG. 5  is a flowchart for explaining the operation of drawing characters or the like with the touch pen  120 . An example that Nippon Taro, as a user, draws characters with the touch pen  120  will be explained next. In using the touch panel apparatus  100 , Nippon Taro inputs his own name from the operating unit  116 , and this is recognized by the controller  113 .  
      At step SA 1  in  FIG. 5 , the controller  113  determines whether a touch area is detected in the touch panel  102  (the display unit  101 ), based on a result of detections carried out by the vertical scan unit  111  and the horizontal scan unit  112 . In this case, the controller  113  sets “No” as a result of the determination, and the controller  113  repeats this determination.  
      Nippon Taro holds the touch pen  120  in the hand  130 , and touches the display unit  101  (the touch panel  102 ) with the front end of the touch pen  120 , as shown in  FIG. 6 . A touch area a r1  corresponds to the front end of the touch pen  120 , and the area is detected as a light-shielded area. In this case, it is assumed that the hand  130  does not touch on the display unit  101  (the touch panel  102 ).  
      The controller  113  sets “Yes” as a result of the determination at step SA 1 . At step SA 2 , the controller  113  determines whether one touch area is detected within a predetermined time. In this case, the controller  113  sets “Yes” as a result of the determination.  
      At step SA 12 , the controller  113  determines whether a change rate of the dimensions of the touch area a r1  after a lapse of a predetermined time since the detection at step SA 1  is equal to or smaller than a threshold value set in advance. In other words, the controller  113  determines whether the dimensions of the touch area a r1  are stable. In this case, the controller  113  sets “Yes” as a result of the determination. When a result of the determination made at step SA 12  is “No”, the controller  113  invalidates the touch area a r1  at step SA 14 , and the controller  113  makes a determination at step SA 1 .  
      At step SA 13 , the controller  113  determines whether the dimensions of the touch area a r1  are equal to or smaller than a threshold value set in advance. In other words, the controller  113  determines whether the dimensions of the touch area a r1  correspond to the dimensions of the front end of the touch pen  120 . In this case, the controller  113  sets “Yes” as a result of the determination. When a result of the determination made at step SA 13  is “No”, the controller  113  regards that the touch area a r1  corresponds to a touch (by mistake) of the hand  130 , and invalidates the touch area a r1  at step SA 14 .  
      At step SA 11 , the controller  113  reflects the touch area a r1  in the drawing coordinates of the x-y coordinate system, and makes the display unit  101  draw the touch area a r1 . The controller  113  then makes a determination at step SA 1 .  
      The operation when the hand is touched (by mistake) on the touch panel will be explained next. In this case, as shown in  FIG. 6 , when Nippon Taro touches the display unit  101  (the touch panel  102 ) with the front end of the touch pen  120  in the state of holding the touch pen  120  in the hand  130 , Nippon Taro also unconsciously touches the display unit  101  (the touch panel  102 ) with the hand  130 .  
      As described above, the touch area a r1  corresponds to the front end of the touch pen  120 , and the area is detected as a light-shielded area. On the other hand, the touch area a r2  corresponds to a part of the hand  130 , and the area is detected as a light-shielded area. In this case, two touch areas of the touch area a r1  and the touch area a r2  are detected.  
      Accordingly, the controller  113  sets “Yes” as a result of the determination at step SA 1 . At step SA 2 , the controller  113  determines whether one touch area is detected within a predetermined time. In this case, the controller  113  sets “No” as a result of the determination.  
      At step SA 3 , the controller  113  determines whether three or more touch areas are detected. In this case, the controller  113  sets “No” as a result of the determination. At step SA 4 , the controller  113  determines whether a distance between a left end point (for example, a left lower point) of the touch area a r1  and a left end point (for example, a left lower point) of the touch area a r2  is equal to or smaller than a threshold value set in advance. In this case, the controller  113  sets “Yes” as a result of the determination.  
      At step SA 5 , the controller  113  compares a change rate of the dimensions of the touch area a r1  with a change rate of the dimensions of the touch area a r2 . Specifically, a change rate of the dimensions of the touch area a r1  corresponding to the touch pen  120  shown in  FIG. 7  is expressed in a graph of time-dimension characteristics shown in  FIG. 8 , and this change rate is very large. On the other hand, a change rate of the dimensions of the touch area a r2  corresponding to the hand  130  shown in  FIG. 7  is expressed in a graph of time-dimension characteristics shown in  FIG. 9 , and this change rate is smaller than that of the graph shown in  FIG. 8 .  
      When the change rate of the dimensions of the touch area is equal to or larger than a threshold value, the controller  113  determines that the touch area corresponds to the touch pen. On the other hand, when the change rate of the dimensions of the touch area is smaller than a threshold value, the controller  113  determines that the touch area corresponds to the hand. These determination standards are used at step SA 7  described later.  
      At step SA 6 , the controller  113  determines whether a difference between the change rate of the dimensions of the touch area a r1  and the change rate of the dimensions of the touch area a r2  is equal to or larger than a threshold value set in advance. In this case, the controller  113  sets “Yes” as a result of the determination. When a result of the determination made at step SA 6  is “No”, the controller  113  invalidates the touch area a r1  and the touch area a r2  at step SA 14 .  
      At step SA 7 , the controller  113  determines types of the touch area a r1  and the touch area a r2  based on the above determination standards. In this case, it is regarded that a change rate of the dimensions of the touch area a r1  is equal to or larger than a threshold value, and the controller  113  determines that the type of the touch area a r1  is the touch pen area, accordingly. It is also regarded that a change rate of the dimensions of the touch area a r2  is smaller than a threshold value, and the controller  113  determines that the type of the touch area a r2  is the hand area, accordingly.  
      At step SA 8 , the controller  113  reads the user profile information  115   1  corresponding to Nippon Taro from the storage unit  114 . At step SA 9 , the controller  113  checks the touch area a r1  and the touch area a r2  that are actually detected with the touch area a t1  and the touch area a t2  (see  FIG. 4 ) that correspond to the user profile information  115   1 .  
      At step SA 10 , the controller  113  determines whether a result of the check at step SA 9  is satisfactory. A result of the check is satisfactory, for example, when a correlation between the touch area a r1  and the touch area a r2  and the touch area a t1  and the touch area a t2  (see  FIG. 4 ) is equal to or higher than a threshold value. When a result of the determination made at step SA 10  is “Yes”, the controller  113  validates the touch area a r1  having a small area and having a large change rate, and reflects the touch area a r1  in the drawing coordinates at step SA 11 . When a result of the determination made at step SA 10  is “No”, the controller  113  invalidates the touch area a r1  and the touch area a r2  at step SA 14 .  
      At step SA 11 , the controller  113  validates the touch area a r1  (the touch pen area) and invalidates the touch area a r2  (the hand area), reflects the touch area a r1  in the drawing coordinates of the x-y coordinate system, makes the display unit  101  draw the touch area a r1 , and determines at step SA 1 . In other words, the controller validates the touch area a r1  and invalidates the touch area a r2  when the area of the touch area (hereinafter, “first parameter”), a change rate (hereinafter, “second parameter”), and a correlation with the user profile information (the touch area a t1  and the touch area a t2 ) (hereinafter, “third parameter”) are equal to or larger than threshold values respectively.  
      While the controller  113  determines whether the touch areas are valid based on all of the first to the third parameters in the above embodiment, the controller  113  can also determine whether the touch areas are valid based on any one of the first to the third parameters.  
      When the other hand also touches on the display unit  101  (the touch panel  102 ), and a touch area a r3  (corresponding to the other hand) is also detected in addition to the touch area a r1  and the touch area a r2 , and three touch areas are detected as shown in  FIG. 6 , the controller  113  sets “Yes” as a result of the determination at step SA 3 . At step SA 14 , the controller  113  invalidates the touch areas a r1  to a r3 .  
      When a result of the determination made at step SA 4  is “No”, the controller  113  determines at step SA 15  whether a ratio of the dimensions of the two touch areas is equal to or larger than a threshold value set in advance. When a result of the determination made at step SA 15  is “No”, the controller  113  invalidates the two touch areas at step SA 14 .  
      On the other hand, when a result of the determination made at step SA 15  is “Yes”, the controller  113  validates the touch area of smaller dimensions and invalidates the touch area of larger dimensions out of the two touch areas at step SA 16 . At step SA 11 , the controller  113  reflects the validated touch area of the smaller dimensions in the drawing coordinates of the x-y coordinate system, and makes the display area  101  draw the touch area.  
      As explained above, according to the above embodiment, when objects (the touch pen  120  and the hand  130 ) touch on the surface of the touch panel  102  (the display unit  101 ) and when the controller  113  detects two touch areas of the touch area a r1  and the touch area a r2 , the controller compares the dimensions of the two touch areas (the touch area a r1  and the touch area a r2 ). The controller validates the touch area of smaller dimensions and invalidates the touch area of larger dimensions. Therefore, it is possible to prevent errors due to detection of two touch areas.  
      Furthermore, according to the above embodiment, the controller  113  compares the dimensions of the two touch areas, and compares temporal change rates of dimensions of the two touch areas. The controller  113  validates a touch area having smaller dimensions and having a large change rate, and invalidates a touch area having larger dimensions and having a small change rate. Therefore, it is possible to prevent errors due to detection of two touch areas.  
      Furthermore, according to the above embodiment, when the two touch areas are detected, the controller  113  determines whether each touch area is valid based on the correlation between the two touch areas obtained from the profile information  115   1  (for example, the touch area a t1  and the touch area a t2  shown in  FIG. 3 ) and the two touch areas that are detected. Therefore, it is possible to prevent errors due to detection of two touch areas because of a habit of the user or the like.  
      While an embodiment of the present invention has been explained above with reference to the accompanying drawings, specific configurations of the invention are not limited thereto. In addition, any design modifications without departing from the scope of the invention are included in the present invention.  
      For example, according to the present embodiment, a program that achieves the functions of the touch panel apparatus  100  can be recorded onto a computer-readable recording medium  300  shown in  FIG. 10 . A computer  200  shown in  FIG. 10  can read the program recorded on the recording medium  300 , and execute the program to achieve the functions.  
      The computer  200  shown in  FIG. 10  includes a central processing unit (CPU)  210  that executes the program, an input device  220  such as a keyboard and a mouse, a read-only memory (ROM)  230  that stores various kinds of data, a random access memory (RAM)  240  that stores operation parameters, a reading unit  250  that reads the program from the recording medium  300 , and an output unit  260  such as a display and a printer.  
      The CPU  210  reads the program recorded on the recording medium  300  via the reading unit  250 , and executes the program to achieve the above functions. The recording medium  300  includes an optical disk, a flexible disk, and a hard disk.  
      Although the invention has been described with respect to a specific embodiment for a complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art that fairly fall within the basic teaching herein set forth.