Abstract:
A coordinate position detecting apparatus includes: a scanning unit that scans a predetermined scanning area in predetermined scanning precision along a horizontal direction and a vertical direction with respect to a display screen by employing detection beams respectively. A position of a light shielding article on the display screen is detected in correspondence with scanning positions of the detection beams which are light-shielded. The scanning unit includes: a drive control unit that switches a plurality of scanning modes having different scanning accuracies from each other; and a moving speed detecting unit that detects a moving speed of the light shielding article. The scanning unit selects a predetermined scanning mode from the plurality of scanning modes in response to the scanning speed detected by the moving speed detecting unit to perform a scanning operation.

Description:
[0001]     The present disclosure relates to the subject matter contained in Japanese Patent Application No. 2005-247940 filed on Aug. 29, 2005, which is incorporated herein by reference in its entirety.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a coordinate position detecting apparatus, and a control method and program thereof.  
         [0004]     2. Background Art  
         [0005]     An example of a coordinate position detecting apparatus for an optical type touch panel or the like is an apparatus using a coordinate position detecting method disclosed in, for instance, JP-A-2001-306241.  
         [0006]     This coordinate position detecting apparatus detects the position on the coordinates on the display screen of a display apparatus, such as a plasma display panel or a cathode-ray tube, which is touched with a finger, a pen or the like. The coordinate position detecting apparatus scans the two-dimensional display screen in the horizontal direction (X axis direction) and the vertical direction (Y axis direction) perpendicular to each other, with detection beams; respectively, and detects a position of a light shielding article touched on the display screen in correspondence to a scanning position of a light-shielded detection beam.  
         [0007]      FIG. 1  is a diagram for explaining a conventional coordinate position detecting method. A plurality of light emitting elements Ax 1  to Axn and Ay 1  to Aym are respectively arrayed on one lateral side (X axis direction) and one longitudinal side (Y axis direction) of a display screen  10 , and a plurality of light receiving elements Bx 1  to Bxn and By 1  to Bym are respectively arrayed on the other lateral side and longitudinal side opposite to the light emitting elements.  
         [0008]     A scanning operation with detection beams mentioned in this specification is to sequentially turn ON a plurality of light emitting elements Ax 1  to Axn and Ay 1  to Aym in this order, and receive the detection beams at the opposing light receiving elements. When an arbitrary point P on the display screen  10  is touched with a finger, a pen or so, detection beams emitted from corresponding light emitting elements on the lateral side and the longitudinal side are shielded, and are not received by the opposing light receiving elements, respectively. Accordingly, the touched position is specified by detecting the X-axis and Y-axis coordinate positions of the touched position from the layout positions of those light receiving elements on the lateral side and longitudinal side which have not received the beams.  
         [0009]     Data of the coordinate positions detected by the coordinate position detecting method are connected by lines based upon application software installed on a personal computer or the like, and are drawn on the display screen. In the scanning operation with the detection beams, as shown in  FIG. 2 , the light emitting elements correspond one to one to the light receiving elements, and the loci of the detection beams have a grid pattern.  
         [0010]     As a consequence, the coordinate position detecting method that provides grid-shaped loci of detection beams as shown in  FIG. 2  cannot acquire coordinate positional information with finer pitches than the layout pitches (arranging intervals) of the light emitting elements and the light receiving elements. If the numbers of the light emitting elements and the light receiving elements are increased so as to make the layout pitches narrower in order to acquire coordinate position information with finer pitches, a large number of elements are required, so that manufacturing cost is increased. Further, the layout pitches are limited to the sizes of the elements (light emitting elements and light receiving elements).  
         [0011]     As the conventional coordinate position detecting method cannot acquire coordinate positional information with finer pitches, it is difficult to accurately trace and draw the locus of a finger or a pen touching the display screen.  
         [0012]     While the coordinate position detecting method described in JP-A-2001-306241 performs the scanning operation in the limited area, the position of a finger, a pen or so moves out of the scanning range when the moving speed of the finger or the pen is fast, which may result in discontinuous draw lines to be drawn on the display screen.  
       SUMMARY OF THE INVENTION  
       [0013]     It is one of the objects of the invention to ensure acquisition of coordinate positional information with finer pitches than the layout pitches of the light emitting elements and the light receiving elements, and to ensure detection of the position of a finger, a pen or the like even when the finger, the pen or the like moves at a high speed, by way of example each.  
         [0014]     The invention provides a coordinate position detecting apparatus, including: a scanning unit that scans a predetermined scanning area in predetermined scanning precision along a horizontal direction and a vertical direction with respect to a display screen by employing detection beams respectively; wherein a position of a light shielding article on the display screen is detected in correspondence with scanning positions of the detection beams which are light-shielded; the scanning unit includes: a drive control unit that switches a plurality of scanning modes having different scanning accuracies from each other; and a moving speed detecting unit that detects a moving speed of the light shielding article; and the scanning unit selects a predetermined scanning mode from the plurality of scanning modes in response to the scanning speed detected by the moving speed detecting unit to perform a scanning operation.  
         [0015]     The invention may provide a control method of a coordinate position detecting apparatus, wherein the coordinate position detecting apparatus scans a predetermined scanning area in a predetermined scanning accuracy along a horizontal direction and a vertical direction with respect to a display screen by employing detection beams respectively, and detects a position of a light shielding article on the display screen in correspondence with scanning positions of the detection beams which are light-shielded, the control method including: performing a scanning in a first scanning mode until the light shielding article is detected; and performing a scanning in a plurality of scanning mode that are different from the first scanning mode and that is selected in response to a moving speed of the light shielding article.  
         [0016]     The invention may provide a program product for enabling a computer to control a coordinate position detecting apparatus, wherein the coordinate position detecting apparatus scans a predetermined scanning area in a predetermined scanning accuracy along a horizontal direction and a vertical direction with respect to a display screen by employing detection beams respectively, and detects a position of a light shielding article on the display screen in correspondence with scanning positions of the detection beams which are light-shielded, the program product including: software instructions for enabling the computer to instruct the coordinate position detecting apparatus to perform predetermined operations; and a computer readable medium bearing the software instructions; wherein the predetermined operations includes: performing a scanning in a first scanning mode until the light shielding article is detected; and performing a scanning in a plurality of scanning mode that are different from the first scanning mode and that is selected in response to a moving speed of the light shielding article. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]     The present invention may be more readily described with reference to the accompanying drawings:  
         [0018]      FIG. 1  is a diagram for explaining the conventional coordinate position detecting method.  
         [0019]      FIG. 2  is a diagram for explaining the loci of detection beams according to the conventional coordinate position detecting method.  
         [0020]      FIG. 3  is a structural diagram of a coordinate position detecting apparatus according to an embodiment of the invention.  
         [0021]      FIG. 4  is a diagram for explaining operations of a coordinate position detecting method according to an embodiment of the invention.  
         [0022]      FIG. 5  is a diagram for explaining the operations of the coordinate position detecting method according to the embodiment of the invention.  
         [0023]      FIG. 6  is a diagram for explaining the operations of the coordinate position detecting method according to the embodiment of the invention.  
         [0024]      FIG. 7  is a diagram for explaining the operations of the coordinate position detecting method according to the embodiment of the invention.  
         [0025]      FIG. 8  is a diagram for explaining the operations of the coordinate position detecting method according to the embodiment of the invention.  
         [0026]      FIG. 9  is a flow chart of a control method for the coordinate position detecting apparatus according to the embodiment of the invention.  
         [0027]      FIG. 10  is another example of the flow chart of the control method for the coordinate position detecting apparatus according to the embodiment of the invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0028]     A coordinate position detecting apparatus and a control method thereof according to embodiments of the present invention will now be described in detail with reference to drawings. It should be noted that the same reference symbols are used in the diagrams to denote those components which have the same functions.  FIG. 3  is a structural diagram of a coordinate position detecting apparatus  1  according to one embodiment of the invention. FIGS.  4  to  8  are diagrams for explaining operations of a coordinate position detecting method according to the embodiment of the invention.  
         [0029]     As shown in  FIG. 3 , the coordinate position detecting apparatus  1  according to the embodiment of the invention is equipped with a scanning unit  40  (scanning means) which scans a display screen  10  in a horizontal direction (X axis direction) and a vertical direction (Y axis direction) with detection beams in predetermined scanning modes, respectively. The coordinate position detecting apparatus  1  constitutes such a coordinate position detecting apparatus which detects a position of a light shielding article on the display screen  10  in correspondence to the scanning position of a light-shielded detection beam.  
         [0030]     The scanning unit  40  is equipped with an X-axis sided light emitting element unit  11 X, a Y-axis sided light emitting element unit  11 Y, an X-axis sided light emission drive unit  12 X, a Y-axis sided light emission drive unit  12 Y, and a control unit  20 . The X-axis sided light emitting element unit  11 X has “n” pieces of light emitting elements (Ax 1  to Axn) arrayed in the X axis direction of the display screen  10  in correspondence to the horizontal width thereof. The Y-axis sided light emitting element unit  11 Y has “m” pieces of light emitting elements (Ay 1  to Aym) arrayed in the Y axis direction of the display screen  10  in correspondence to the vertical width thereof. The X-axis sided light emission drive unit  12 X turns ON the X-axis sided light emitting element unit  11 X. The Y-axis sided light emission drive unit  12 Y turns ON the Y-axis sided light emitting element unit  11 Y. The control unit  20  sends control signals to the X-axis sided light emission drive unit  12 X and the Y-axis sided light emission drive unit  12 Y.  
         [0031]     The photo sensing unit  30  contains an X-axis sided light receiving element unit  13 X, a Y-axis sided light receiving element unit  13 Y, an X-axis sided output selecting unit  14 X, and a Y-axis sided output selecting unit  14 Y. The X-axis sided light receiving element unit  13 X has “n” pieces of light receiving elements (Bx 1  to Bxn) arrayed along one side of the display screen  10  and opposite to the X-axis sided light emitting element unit  11 X arrayed along one side of the display screen  10 . The Y-axis sided light receiving element unit  13 Y has “m” pieces of light receiving elements (By 1  to Bym) arrayed along one side of the display screen  10  and opposite to the Y-axis sided light emitting element unit  11 Y arrayed along one side of the display screen  10 . The X-axis sided output selecting unit  14 X and the Y-axis sided output selecting unit  14 Y respectively send signals output from the X-axis sided light receiving element unit  13 X and the Y-axis sided light receiving element unit  13 Y to the control unit  20 .  
         [0032]     The control unit  20  also contains a coordinate detecting unit  21 , a data converting unit  22 , a drive control unit  23 , and a moving speed detecting unit  24 . The coordinate detecting unit  21  detects coordinates based on the signals from the X-axis sided output selecting unit  14 X and the Y-axis sided output selecting unit  14 Y. The data converting unit  22  converts a detected coordinate position to coordinate data. The drive control unit  23  sets the turn-ON order of the X-axis sided light emitting element unit  11 X and the Y-axis sided light emitting element unit  11 y, and changes over a scanning mode to be described later. The moving speed detecting unit  24  detects a moving speed of the light shielding article on the display screen  10 .  
         [0033]     Referring now to  FIG. 4 , a description will now be made of the basic operation of “oblique scanning”, one feature of the coordinate position detecting method of the embodiment, which receives a detection beam, emitted from a light emitting element, at a plurality of light receiving elements located opposite to positions including oblique directional positions of the light emitting element so as to detect the position of the light shielding article.  
         [0034]     The light emitting elements Ax 1  to Axn of the X-axis sided light emitting element unit  11 X and the light emitting elements Ay 1  to Aym of the Y-axis sided light emitting element unit  11 Y sequentially emit detection beams toward the X-axis sided light receiving element unit  13 X and the Y-axis sided light receiving element unit  13 Y directed to the respective light emitting elements.  FIG. 4  shows a state in which the light emitting element Axi of the X-axis sided light emitting element unit  11 X and the light emitting element Ayi of the Y-axis sided light emitting element unit  11 Y are turned ON.  
         [0035]     As the detection beam emitted from the light emitting element Axi of the X-axis sided light emitting element unit  11 X has a predetermined spread, the detection beam can be received by a plurality of light receiving elements of the X-axis sided light receiving element unit  13 X, for example, Bx(i−2), Bx(i−1), Bxi, Bx(i+1) and Bx(i+2). When the light emitting element Axi is turned ON, the detection beam therefrom is detected by the light receiving elements Bx(i−2), Bx(i−1), Bxi, Bx(i+1), Bx(i+2).  
         [0036]     Similarly, as the detection beam emitted from the light emitting element Ayi of the Y-axis sided light emitting element unit  11 Y has a predetermined spread, the detection beam can be received by a plurality of light receiving elements of the Y-axis sided light receiving element unit  13 Y, for example, By(i−2), By(i−1), Byi, By(i+1) and By(i+2). When the light emitting element Ayi is turned ON, the detection beam therefrom is detected by the light receiving elements By(i−2), By(i−1), Byi, By(i+1), By(i+2).  
         [0037]     All the light emitting elements Ax 1  to Axn and Ay 1  to Aym are sequentially turned ON to carry out oblique scanning.  FIG. 5  shows the loci of the detection beams from all the light emitting elements Ax 1  to Axn and Ay 1  to Aym. Such a scanning operation allows the coordinate position of a light shielding article on the display screen  10  to be detected based on the positions of the loci of the light-shielded detection beams.  
         [0038]     The oblique scanning as shown in  FIG. 5  provides denser loci of detection beams, as compared with such a case that the grid-shaped scanning as shown in  FIG. 2  is executed, and can provide coordinate position information with narrower pitches than the layout pitches of the light emitting elements and the light receiving elements.  
         [0039]     It should also be noted that five light receiving elements can receive a detection beam from a single turned-ON light emitting element in the embodiment. However, any number of light receiving elements may be alternatively enabled to detect a detection beam from a single turned-ON light emitting element, although a total number is restricted by the spread characteristics of the detection beams of the light emitting elements and the characteristic of the detection sensitivity of the light receiving elements.  
         [0040]     In the coordinate position detecting apparatus  1  of the embodiment, the scanning unit  40  is operated in any one of a first scanning mode, a second scanning mode, and a third scanning mode.  
         [0041]     In the first scanning mode, a grid-shaped scanning operation is performed over the entire display screen  10  in a similar scanning operation in the related art shown in  FIG. 2 . The grid-shaped scanning operation is carried out as the light emitting elements Ax 1  to Axn of the X-axis sided light emitting element unit  11 X and the light emitting elements Ay 1  to Aym of the Y-axis sided light emitting element unit  11 Y, which are arrayed in correspondence to the horizontal width and vertical width of the display screen  10 , are sequentially turned ON. This first scanning mode is used in initially detecting a light shielding article.  
         [0042]     In the second scanning mode, an oblique scanning operation is performed. In the second scanning mode, a scan area is limited to a range including coordinate positions detected in the first scanning mode but narrower than the full area of the full scanning operation, and the scanning operation is performed within the range as, for example, the light emitting elements Ax(i−2), Ax(i−1), Axi, Ax(i+1), Ax(i+2) of the x-axis sided light emitting element unit  11 X and the light emitting elements Ay(i−2) , Ay(i−1), Ayi, Ay(i+1), Ay(i+2) of the Y-axis sided light emitting element unit  11 Y are sequentially turned ON as shown in  FIG. 6 .  
         [0043]     In the second scanning mode, a maximum of five light receiving elements sequentially detect a detection beam emitted from a single light emitting element.  
         [0044]     That is to say, in an example shown in  FIG. 6 , first, the light emitting element Ax(i−2) of the X-axis sided light emitting element unit  11 X is turned ON, and a detecting operation of a detection beam by the light receiving elements Bx (i−2), Bx(i−1), Bxi is sequentially executed. Next, the light emitting element Ax(i−1) is turned ON, and a detecting operation of a detection beam by the light receiving elements Bx(i−2), Bx(i−1), Bxi, Bx(i+1) is sequentially executed. Then, the light emitting element Axi is turned ON, and a detecting operation of a detection beam by the light receiving elements Bx(i−2), Bx(i−1), Bxi, Bx(i+1), Bx(i+2) is sequentially executed. Then, the light emitting element Ax(i+1) is turned ON, and a detecting operation of a detection beam by the light receiving elements Bx(i−1), Bxi, Bx(i+1), Bx(i+2) is sequentially executed. Finally, the light emitting element Ax(i+2) is turned ON, and a detecting operation of a detection beam by the light receiving elements Bxi, Bx(i+1), Bx(i+2) is sequentially executed.  
         [0045]     Similarly, the light emitting element Ay(i−2) of the Y-axis sided light emitting element unit  11 Y is turned ON, and a detecting operation of a detection beam by the light receiving elements By(i−2), By(i−1), Byi is sequentially executed. Next, the light emitting element Ay(i−1) is turned ON, and a detecting operation of a detection beam by the light receiving elements By(i−2), By(i−1), Byi, By(i+1) is sequentially executed. Then, the light emitting element Ayi is turned ON, and a detecting operation of a detection beam by the light receiving elements By(i−2), By(i−1), Byi, By(i+1), By(i+2) is sequentially executed. Then, the light emitting element Ay(i+1) is turned ON, and a detecting operation of a detection beam by the light receiving elements By(i−1), Byi, By(i+1), By(i+2) is sequentially executed. Finally, the light emitting element Ay(i+2) is turned ON, and a detecting operation of a detection beam by the light receiving elements Byi, By(i+1), By(i+2) is sequentially executed.  
         [0046]     In the third scanning mode, similar to the second scanning mode, an oblique scanning operation is performed. In the third scanning mode, a scan area is limited to a range including coordinate positions detected in the first scanning mode but narrower than the full area of the full scanning operation, and a scanning operation is performed within the range as, for example, the light emitting elements Ax(i−2), Ax(i−1), Axi, Ax(i+1), Ax(i+2) of the X-axis sided light emitting element unit  11 X and the light emitting elements Ay(i−2), Ay(i−1), Ayi, Ay(i+1), Ay(i+2) of the Y-axis sided light emitting element unit  11 Y are sequentially turned ON, as shown in  FIG. 7 .  
         [0047]     In the third scanning mode, a maximum of three light receiving elements sequentially detect a detection beam emitted from a single light emitting element. That is, the third scanning mode is featured in that a total number of light receiving elements which receive a detection beam emitted from a single light emitting element is less than that in the second scanning mode.  
         [0048]     That is to say, in an shown in  FIG. 6 , first, the light emitting element Ax(i−2) of the X-axis sided light emitting element unit  11 X is turned ON, and a detecting operation of a detection beam by the light receiving elements Bx(i−2), Bx(i−1) is sequentially executed. Next, the light emitting element Ax(i−1) is turned ON, and a detecting operation of a detection beam by the light receiving elements Bx(i−2), Bx(i−1), Bxi is sequentially executed. Then, the light emitting element Axi is turned ON, and a detecting operation of a detection beam by the light receiving elements Bx(i−1), Bxi, Bx(i+1) is sequentially executed. Then, the light emitting element Ax(i+1) is turned ON, and a detecting operation of a detection beam by the light receiving elements Bx(i−1), Bxi, Bx(i+1) is sequentially executed. Finally, the light emitting element Ax(i+2) is turned ON, and a detecting operation of a detection beam by the light receiving elements Bx(i+1), Bx(i+2) is sequentially executed.  
         [0049]     Similarly, the light emitting element Ay(i−2) of the Y-axis sided light emitting element unit  11 Y is turned ON, and a detecting operation of a detection beam by the light receiving elements By(i−2), By(i−1) is sequentially executed. Next, the light emitting element Ay(i−1) is turned ON, and a detecting operation of a detection beam by the light receiving elements By(i−2), By(i−1), Byi is sequentially executed. Then, the light emitting element Ayi is turned ON, and a detecting operation of a detection beam by the light receiving elements By(i−1), Byi, By(i+1) is sequentially executed. Then, the light emitting element Ay(i+1) is turned ON, and a detecting operation of a detection beam by the light receiving elements Byi, By(i+1), By(i+2) is sequentially executed. Finally, the light emitting element Ay(i+2) is turned ON, and a detecting operation of a detection beam by the light receiving elements By(i+1), By(i+2) is sequentially executed.  
         [0050]     In the fourth scanning mode, an oblique scanning operation is performed. In the further scanning mode, a scan area is limited to a range including coordinate positions detected in the first scanning mode but narrower than the full area of the full scanning operation, and a grid-shaped scanning operation is performed within the range as, for example, the light emitting elements Ax(i−2), Ax(i−1), Axi, Ax(i+1), Ax(i+2) of the X-axis sided light emitting element unit  11 X and the light emitting elements Ay(i−2), Ay(i−1), Ayi, Ay(i+1), Ay(i+2) of the Y-axis sided light emitting element unit  11 Y are sequentially turned ON, as shown in  FIG. 8 .  
         [0051]     It should be noted that the widths of the scan area in the second to fourth scanning modes are not limited to the above-described examples in FIGS.  6  to  8 , and may be determined adequately. The width of the scan area in the X axis direction may alternatively differ from the width of the scan area in the Y axis direction.  
         [0052]     The operations of the control method for the coordinate position detecting apparatus  1  according to the embodiment will be described next with reference to  FIGS. 3, 6  and  7 . The flow in  FIG. 9  is one example of the operational flow of the control method for the coordinate position detecting apparatus  1 .  
         [0053]     First, in a step S 1 , a judgement is made as to whether the power supply of the coordinate position detecting apparatus  1  has been turned OFF. When the power supply of the coordinate position detecting apparatus  1  is under ON status (step  1 : NO), a scanning operation is performed in the first scanning mode (step S 2 ). The scanning operation in the first scanning mode is continuously performed until a light shielding article is detected (in step S 3 ). When a light shielding article is detected (step S 3 : YES), the output of the coordinate detecting unit  21  is converted by the data converting unit  22 , and the detected coordinate data is stored in a memory apparatus (not shown) (step S 4 ). The output coordinates in the display screen  10  are computed based on the detected coordinate data, and the computed coordinates are output (step  5 S).  
         [0054]     The above-explained detection of a light shielding article is premised on that the light shielding article has been detected consecutively in two or more scanning periods. The moving speed of the light shielding article can be computed from the distance between the detected two coordinate positions, and the detection times.  
         [0055]     The moving speed detecting unit  24  computes the moving speed of the light shielding article (step S 6 ). When the moving speed of the light shielding article exceeds a predetermined speed (step S 7 : YES), it is so determined that the light shielding article is moving at a high speed, so that the drive control unit  23  executes a scanning operation in the third scanning mode suitable for responding to the high-speed movement of the light shielding article (step S 9 ). When the moving speed of the light shielding article is equal to or lower than the predetermined speed (step S 7 : NO), the drive control unit  23  executes a scanning operation in the second scanning mode by which accurate positional information is acquired (step S 8 ).  
         [0056]     When a light shielding article is detected during this new scanning mode, the above-described steps S 4  to S 7  are executed, and another scanning operation is further carried out in a scanning mode according to the moving speed of the light shielding article. When no light shielding article is detected, the flow operation is returned to the step S 1 . When the power supply is not turned OFF, the first scanning mode is executed. When the power supply is turned OFF during the operation (step  1 : YES), however, the process operation is terminated.  
         [0057]     The predetermined moving speed in the step S 7  is selected to be, for example, 10 cm/s. That is, when the moving speed of the light shielding article exceeds 10 cm/s, the light shielding article is considered as moving at a high speed, and the scanning operation is performed in the third scanning mode.  
         [0058]     According to the above-explained embodiment, when a light shielding article such as a finger or a pen moves at a high speed, the scanning period can be made shorter by reducing the total number of detection beams emitted from a single light emitting element. This ensures a response to the movement of a finger, a pen or the like, thus making it difficult to cause discontinuous drawing lines at the time of drawing a simple figure or an example where a finger, a pen or the like moves at a high speed.  
         [0059]     When the light shielding article such as a finger or a pen moves at a low speed, the loci of the detection beams in the scanning operation becomes denser by increasing the total number of detection beams emitted from a single light emitting element. This can provide more accurate coordinate positional information, and enable more accurate drawing of a complex character, figure or the like.  
         [0060]     The operation of another example of the control method for the coordinate position detecting apparatus  1  according to the embodiment will be described with reference to a flow operation in  FIG. 10  and  FIGS. 3 and 6  to  8 .  FIG. 10  shows another example of the flow operation of the control method for the coordinate position detecting apparatus  1 . It should also be noted that the same reference symbols are given to the same process operations in  FIG. 10  as those illustrated in  FIG. 9  to avoid redundant descriptions.  
         [0061]     Also, in this example shown in  FIG. 10 , the operation in the flow chart from step S 1  to step S 6  is the same as the operation in the flow chart in  FIG. 9 . In a step S 11 , the moving speed of a light shielding article is classified into three levels of “low speed”, “middle speed” and “high speed”, and a scanning operation is performed in a scanning mode suitable for each moving speed. Specifically, in the step  511 , the “low speed” is equal to or lower than a first moving speed, the “middle speed” is higher than the first moving speed and equal to or lower than a second moving speed, and the “high speed” is higher than the second moving speed.  
         [0062]     When the moving speed corresponds to the “low speed”, the light shielding article is determined as moving at a low speed, so that the drive control unit  23  performs a scanning operation in the second scanning mode suitable for the low speed (step S 12 ). When the moving speed corresponds to the “middle speed”, the light shielding article is determined as moving at a middle speed, so that the drive control unit  23  performs a scanning operation in the third scanning mode suitable for the middle speed (step S 13 ). When the moving speed corresponds to the “high speed”, the light shielding article is determined as moving at a high speed, so that the drive control unit  23  performs a scanning operation in the fourth scanning mode suitable for the high speed (step S 14 ).  
         [0063]     When a light shielding article is detected during this new scanning mode, the steps S 4  to S 11  are executed, and a scanning operation is further carried out in a scanning mode according to the moving speed of the light shielding article. When no light shielding article is detected, the flow operation is returned to the step S 1 . When the power supply is not turned OFF, the first scanning mode is executed. When the power supply is turned OFF during the operation (step S 1 : YES), however, the process operation is terminated.  
         [0064]     The first moving speed and the second moving speed which are used in the decision in the step S 11  are set in such a way that the first moving speed is 10 cm/s and the second moving speed is 50 cm/s.  
         [0065]     When the moving speed of the light shielding article is equal to or lower than 10 cm/s, the moving speed is determined as the “low speed”, and a scanning operation is performed in the second scanning mode. When the moving speed of the light shielding article is higher than 10 cm/s and equal to or lower than 50 cm/s, the moving speed is determined as the “middle speed”, and a scanning operation is performed in the third scanning mode. When the moving speed of the light shielding article is higher than 50 cm/s, the moving speed is determined as the “high speed”, and a scanning operation is performed in the fourth scanning mode.  
         [0066]     According to this embodiment in  FIG. 10 , the moving speeds of the light shielding article are classified into three sorts of “low speed”, “middle speed” and “high speed”, so that a scanning mode suitable for each moving speed can be selected. For various moving speeds, therefore, it is possible to secure the response characteristics to the movement a finger, a pen or so, and the precision of the coordinate position thereof.  
         [0067]     The numbers of light receiving elements which detect a detection beam emitted from a single light emitting element in the second scanning mode and the third scanning mode are not limited to those of the example in  FIG. 9  or  FIG. 10 .  
         [0068]     The types of the moving speeds are not limited to two in the example in  FIG. 9  or three in the example in  FIG. 10 , but may be changed to four or more types according to the moving speed of, for example, a finger, a pen or so.  
         [0069]     As described in detail above, the coordinate position detecting apparatus  1  according to the embodiment of the invention corresponds to such a coordinate position detecting apparatus which is equipped with the scanning unit  40  (scanning means) which scans the display screen  10  within the predetermined scanning area in the horizontal direction and the vertical direction in the predetermined scanning precision with the detection beams respectively, and detects the position of the light shielding article on the display screen  10  in correspondence to the scanning position of the light-shielded detection beam. The scanning unit  40  is provided with the drive control unit  23  which changes over the plurality of scanning modes of different scanning precision from one to another, and the moving speed detecting unit  24  which detects the moving speed of the light shielding article. The scanning unit  40  of the coordinate position detecting apparatus  1  performs the scanning operation with a predetermined scanning mode selected from the plurality of scanning modes in response to the moving speed of the light shielding article detected by the moving speed detecting unit  24 .  
         [0070]     As a consequence, the coordinate position detecting apparatus  1  can acquire the coordinate positional information with the finer pitches than the arranging intervals of the light emitting elements and the light receiving elements, and can detect the position of a light shielding article such as a finger or a pen even when the light shielding article moves at the high speed on the display screen  10 .  
         [0071]     The control method for the coordinate position detecting apparatus  1  according to the embodiment of the invention corresponds to such a method for controlling the coordinate position detecting apparatus  1  which scans the display screen  10  within the predetermined scanning area in the horizontal direction and the vertical direction in the predetermined scanning precision with the detection beams respectively, and detects the position of the light shielding article on the display screen  10  in correspondence to the scanning position of the light-shielded detection beam. The scanning operation is performed in the first scanning mode until the light shielding article is detected, and the scanning operation is performed after the plurality of scanning modes different from the first scanning mode are selected in response to the moving speed of the light shielding article.  
         [0072]     As a consequence, the control method for the coordinate position detecting apparatus can acquire the coordinate positional information with the finer pitches than the layout pitches of the light emitting elements and the light receiving elements, and can detect the position of the light shielding article such as the finger or the pen even when the light shielding article moves at a high speed.