Abstract:
In an optical touch panel including a first group of light emitting and receiving packages and a second group of light emitting and receiving packages provided on a display surface at opposite sides to each other, each of the light emitting and receiving packages is formed by one light emitting element and one light receiving element vertically arranged above the display surface. The light emitting element of each light emitting and receiving package of the first group opposes the light receiving element of one light emitting and receiving package of the second group, and the light emitting element of each light emitting and receiving package of the second group opposes the light receiving element of one light emitting and receiving package of the first group.

Description:
[0001]    This application claims the priority benefit under 35 U.S.C. §119 to Japanese Patent Application No. JP2012-109349 filed on May 11, 2012, which disclosure is hereby incorporated in its entirety by reference. 
       BACKGROUND 
       [0002]    1. Field 
         [0003]    The presently disclosed subject matter relates to an optical touch panel. 
         [0004]    2. Description of the Related Art 
         [0005]    In  FIG. 8 , which illustrates a first prior art optical touch panel (see:  FIGS. 1(   a ),  1 ( b ),  1 ( c ) and  1 ( d ) of EP2088499 A1,  FIG. 2  of US2012/0200537A1), a glass substrate  1  for defining a display surface also serves as an upper glass substrate of a liquid crystal display (LCD) device, for example. Also, provided on the glass substrate  1  are two substrates  2 X-a and  2 X-b along a Y-direction at opposite sides to each other. Further, provided on the glass substrate  1  are two substrates  2 Y-a and  2 Y-b along an X-direction at opposite sides to each other. 
         [0006]    In addition, X-direction light emitting elements such as light emitting diode (LED) elements  3 X-a are equidistantly arranged on the substrate  2 X-a, and X-direction light receiving elements such as phototransistor elements  3 X-b are equidistantly arranged on the substrate  2 X-b. The LED elements  3 X-a oppose respective ones of the phototransistor elements  3 X-b. 
         [0007]    Similarly, Y-direction light emitting elements such as LED elements  3 Y-a are equidistantly arranged on the substrate  2 Y-a, and Y-direction light receiving elements such as phototransistor elements  3 Y-b are equidistantly arranged on the substrate  2 Y-b. The LED elements  3 Y-a oppose respective ones of the phototransistor elements  3 Y-b. 
         [0008]    Light L X1  emitted from one of the LED elements  3 X-a passes over the display surface to reach one of the phototransistor elements  3 X-b. In this case, when an object such as a finger A is present on the display surface to intercept the light L X1 , the light L X1  does not reach the one of the phototransistor elements  3 X-b. Thus, it can be determined whether or not the finger A is present on a coordinate X 1  of the light L X1  by whether or not the one of the phototransistor elements  3 X-b detects the light L X1 . 
         [0009]    Similarly, Light L y1  emitted from one of the LED elements  3 Y-a passes over the display surface to reach one of the phototransistor elements  3 Y-b. In this case, when the finger A is present on the display surface to intercept the light L y1 , the light L y1  does not reach the one of the phototransistor elements  3 Y-b. Thus, it can be determined whether or not the finger a is present on a coordinate Y 1  of the light L Y1  by whether or not the one of the phototransistor elements  3 Y-b detects the light L Y1 . 
         [0010]    Thus, it is possible to determine whether or not the finger A is located at a position (X 1 , Y 1 ) by whether neither of the lights L Y1  and L y1  are detected. 
         [0011]    In the optical touch panel as illustrated in  FIG. 8 , however, even if other objects such as fingers B, C and D, whose positions are (X 1 , Y 2 ), (X 2 , Y 1 ) and (X 2 , Y 2 ). respectively, are present simultaneously with the finger A, the fingers B, C and D cannot be detected. That is, since propagating directions of lights L X1  and L X2  are perpendicular to those of lights L Y1  and L Y2 , the fingers B and C are shadowed by the finger A, and the finger D is shadowed by the fingers B and C. Thus, it is impossible to carry out a multiple touch operation using two or more fingers simultaneously. 
         [0012]    In  FIG. 9 , which illustrates a second prior art optical touch panel, the LED elements  3 X-a, the phototransistor elements  3 X-b, the LED elements  3 Y-a and the phototransistor elements  3 Y-b of  FIG. 8  are replaced by light emitting and receiving packages  3 X′-a, light emitting and receiving packages  3 X′-b, light emitting and receiving packages  3 Y′-a and light emitting and receiving packages  3 Y′-b, respectively. Each of the light emitting and receiving packages  3 X′-a,  3 X′-b,  3 Y′-a, and  3 Y′-b has the same configuration formed by a light emitting element such as an LED element  31  and a light receiving element such as a phototransistor  32  which are laterally and closely arranged. Thus, each of the fingers A, B, C and D can be individually detected by a reflective photo-intercepting technology. 
         [0013]    For example, light L X1  emitted from the LED element  31  of one of the light emitting and receiving packages  3 X′-a is reflected by the finger A to reach the phototransistor element  32  thereof, and also, light L Y1  emitted from the LED element  31  of one of the light emitting and receiving packages  3 Y′-a is reflected by the finger A to reach the phototransistor element  32  thereof. Thus, it can be determined whether or not the finger A is located on a position (X 1 , Y 1 ) by whether or not the reflected lights L X1  and L Y1  are both present simultaneously. 
         [0014]    In addition, light L X2  emitted from the LED element  31  of one of the light emitting and receiving packages  3 X′-b is reflected by the finger B to reach the phototransistor element  32  thereof, and also, light L Y1 , emitted from the LED element  31  of one of the light emitting and receiving packages  3 Y′-a is reflected by the finger B to reach the phototransistor element  32  thereof. Thus, it can be determined whether or not the finger B is located on a position (X 2 , Y 2 ) by whether or not the reflected lights L X2  and L Y2  are both present simultaneously. 
         [0015]    Further, light L X3  emitted from the LED element  31  of one of the light emitting and receiving packages  3 X′-a is reflected by the finger C to reach the phototransistor element  32  thereof, and also, light L Y3  emitted from the LED element  31  of one of the light emitting and receiving packages  3 Y′-b is reflected by the finger C to reach the phototransistor element  32  thereof. Thus, it can be determined whether or not the finger C is located on a position (X 3 , Y 3 ) by whether or not the reflected lights L X3  and L Y3  are both present simultaneously. 
         [0016]    Still further, light L X4  emitted from the LED element  31  of one of the light emitting and receiving packages  3 X′-b is reflected by the finger D to reach the phototransistor element  32  thereof, and also, light L Y4  emitted from the LED element  31  of one of the light emitting and receiving packages  3 Y′-b is reflected by the finger D to reach the phototransistor element  32  thereof. Thus, it can be determined whether or not the finger D is located on a position (X 4 , Y 4  by whether or not the reflected lights L X4  and L Y4  are both present simultaneously. 
         [0017]    Thus, even if X 1 =X 2 , the finger B is not shadowed by the finger A. Also, even if Y 3 =Y 1 , the finger C is not shadowed by the finger A. Further, even if X 4 =X 3  and Y 4 =Y 2 , the finger D is not shadowed by the fingers B and C. 
         [0018]    In the optical touch panel as illustrated in  FIG. 9 , however, in each of the light emitting and receiving packages  3 X′-a,  3 X′-b,  3 Y′-a and  3 Y′-b, when the light distributing characteristics of the LED element  31  and the light distributing characteristics of the phototransistor element  32  are deviated, the noise of the phototransistor element  32  would be increased. For example, when the optical axis of the LED element  31  of one of the light emitting and receiving packages is shifted horizontally in the right or left direction, so that the light distributing characteristics of this LED element  31  are deviated as shown in  FIG. 10 , light emitted from the LED element  31  and reflected by a finger would be received by the phototransistor elements of its neighboring light emitting and receiving packages to increase the noise thereof. 
       SUMMARY 
       [0019]    The presently disclosed subject matter seeks to solve one or more of the above-described problems. 
         [0020]    According to the presently disclosed subject matter, in an optical touch panel including a first group of light emitting and receiving packages and a second group of light emitting and receiving packages provided on a display surface at opposite sides to each other, each of the light emitting and receiving packages is formed by one light emitting element and one light receiving element vertically arranged above the display surface. The light emitting element of each light emitting and receiving package of the first group opposes the light receiving element of one light emitting and receiving package of the second group, and the light emitting element of each light emitting and receiving package of the second group opposes the light receiving element of one light emitting and receiving package of the first group. Thus, if the light distributing characteristics of the light emitting element and the light distributing characteristics of the light receiving element are shifted to the right or left side, the noise of the light receiving element would not be increased. 
         [0021]    Also, first and second light guide lenses are provided to oppose light emitting and receiving faces of one group of the first and second groups of light emitting and receiving packages. In this case, each of the first and second light guide lenses includes at least one light emitting and receiving face which is two-convex shaped viewed from a side thereof. Or, each of the first and second light guide lenses includes one light emitting and receiving face which is one-convex shaped viewed from a side thereof and another light emitting and receiving face which is V-shaped viewed from the side. Thus, the first and second light guide lenses serve as condenser lenses. 
         [0022]    Further, each of the light emitting and receiving packages includes a substrate for mounting the light emitting element and the light receiving element, and a resin layer for sealing the light emitting element and the light receiving element. In this case, the resin layer has a face portion sloped with respect to a face of the light emitting element. Or, a reflective layer is inserted into the resin layer to partition the resin layer for the light emitting element and the light receiving element. Thus, return light from the light emitting element to the light receiving element is suppressed. 
         [0023]    Still further, the light emitting elements of the first group of light emitting and receiving packages and the light emitting elements of the second group of light emitting and receiving packages are time-divisionally operated, and the light receiving elements of the first group of light emitting and receiving packages and the light receiving elements of the second group of light emitting and receiving packages are operated in synchronization with operations of the light emitting elements of both of the first and second light emitting and receiving packages. 
         [0024]    According to the presently disclosed subject matter, even when the light distributing characteristics of the light emitting element and the light distributing characteristics of the light receiving element are shifted horizontally in the right or left direction, the noise of the light receiving element can be suppressed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0025]    The above and other advantages and features of the presently disclosed subject matter will he more apparent from the following description of certain embodiments, as compared with the prior art, taken in conjunction with the accompanying drawings, wherein: 
           [0026]      FIG. 1  is a plan view illustrating a first embodiment of the optical touch panel according to the presently disclosed subject matter; 
           [0027]      FIGS. 2A and 2B  are perspective views of the light emitting and receiving packages of  FIG. 1 ; 
           [0028]      FIG. 3  is a cross-sectional view taken along the line III-III in  FIG. 1 ; 
           [0029]      FIG. 4  is a view illustrating a second embodiment of the optical touch panel according to the presently disclosed subject matter; 
           [0030]      FIGS. 5A and 5B  are cross-sectional views of the optical touch panel of  FIG. 4  taken along the line V-V in  FIG. 4 ; 
           [0031]      FIGS. 6A and 6B  are perspective views illustrating modifications of the light emitting and receiving packages of  FIGS. 5A and 5B ; 
           [0032]      FIGS. 7A ,  7 B,  7 C and  7 D are timing diagrams for explaining the operation of the optical touch panels of  FIGS. 1 and 4 ; 
           [0033]      FIG. 8  is a plan view illustrating a first prior art optical touch panel; 
           [0034]      FIG. 9  is a plan view illustrating a second prior art optical touch panel; and 
           [0035]      FIG. 10  is a diagram illustrating light distributing characteristics of the LED element of  FIG. 9 . 
       
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0036]    In  FIG. 1 , which illustrates a first embodiment of the optical touch panel according to the presently disclosed subject matter, the light emitting and receiving packages  3 X′-a,  3 X′-b,  3 Y′-a and  3 Y′-b of  FIG. 9  are replaced by light emitting and receiving packages  3 X″-a,  3 X″-b,  3 Y″-a and  3 Y″-b, respectively. In each of the light emitting and receiving packages  3 X″-a,  3 X″-b,  3 Y″-a and  3 Y″-b, the LED element  31  and the phototransistor element  32  are vertically and closely arranged. Therefore, even if the optical axis of the LED element  31  of one of the light emitting and receiving packages is shifted in the right or left direction, so that the light distributing characteristics of this LED element  31  are deviated, the noise of phototransistor elements of its neighboring light emitting and receiving packages is not increased. 
         [0037]    In  FIG. 2A , which illustrates one of the light emitting and receiving packages  3 Y″-a ( 3 X″-a), the LED element  31  and the phototransistor element  32  are mounted on a substrate  30  and are sealed by a resin layer  33 . In this case, the LED element  31  is located at a lower side of the phototransistor element  32 . 
         [0038]    Similarly, in  FIG. 2B , which illustrates one of the light emitting and receiving packages  3 Y″-b ( 3 X″-b), the LED element  31  and the phototransistor element  32  are also mounted on a substrate  30  and are sealed by a resin layer  33 . In this case, the LED element  31  is located at an upper side of the phototransistor element  32 . 
         [0039]    As illustrated in  FIG. 3 , which is a cross-sectional view taken along the line III-III in  FIG. 1 , the LED element  31  of one of the light emitting and receiving packages  3 Y″-a opposes the phototransistor element  32  of one of the light emitting and receiving packages  3 Y″-b, and also, the LED element  31  of the one of the light emitting and receiving packages  3 Y″-b opposes the phototransistor element  32  of the one of the light emitting and receiving packages  3 Y″-a. 
         [0040]    The optical touch panel of  FIG. 1  operates in the same way as the optical touch panel of  FIG. 9 . In this case, even when the optical axis of the LED element  31  of one of the light emitting and receiving packages is shifted horizontally in the right or left direction, so that the light distributing characteristics of this LED element  31  are deviated as shown in  FIG. 10 , light emitted from the LED element  31  and reflected by a finger would not be received by the phototransistor elements of its neighboring light emitting and receiving packages. However, when the optical axis of the LED element  31  of one of the light emitting and receiving packages is shifted vertically in the up or down direction, so that the light distributing characteristics of this LED element  31  are deviated, light emitted from the LED element  31  and reflected by a finger would be received by the phototransistor element of this one of the light emitting and receiving packages to increase the noise thereof. 
         [0041]    In  FIG. 4 , which illustrates a second embodiment of the optical touch panel according to the presently disclosed subject matter, one light guide lens  4 X-a is provided for the light emitting and receiving packages  3 X″-a to oppose light emitting and receiving faces of thereof, one light guide lens  4 X-b is provided for the light emitting and receiving packages  3 X″-b to oppose light emitting and receiving faces of thereof, one light guide lens  4 Y-a is provided for the light emitting and receiving packages  3 Y″-a to oppose light emitting and receiving faces of thereof, and one light guide lens  4 Y-b is provided for the light emitting and receiving packages  3 Y″-b to oppose light emitting and receiving faces of thereof. 
         [0042]      FIGS. 5A and 5B  are cross-sectional views of the optical touch panel of  FIG. 4  taken along the line V-V in  FIG. 4 . 
         [0043]    As illustrated in  FIG. 5A , which illustrates a first example of the light guide lenses  4 Y-a and  4 Y-b of  FIG. 4 , at least one light emitting and receiving face of the light guide lenses  4 Y-a and  4 Y-b is two-convex shaped or R-shaped viewed from their sides to form a condenser lens L 1 , while the other portion L 2  except for the condenser lens L 1  serves as a light guide. 
         [0044]    Also, in  FIG. 5A , a face portion of the resin layer  33  opposing the LED element  31  is sloped with respect to a face F 1  of the LED element  31  to suppress return light to its phototransistor element  32 , thereby reducing the noise thereof. 
         [0045]    On the other hand, as illustrated in  FIG. 5B , which illustrates a second example of the light guide lenses  4 Y-a and  4 Y-b of  FIG. 4 , one light emitting and receiving face of the light guide lenses  4 Y-a and  4 Y-b is one-convex shaped or R-shaped viewed from their sides to form a condenser lens L 1 , while the other light emitting and receiving face of the light guide lenses  4 Y-a and  4 Y-b is V-shaped viewed from their sides to form a condenser lens L 4 . The other portion L 5  except for the condenser lenses L 3  and L 4  serves as a light guide. 
         [0046]    Also, in  FIG. 5B , a face portion of the resin layer  33  opposing the LED element  31  is sloped with respect to a face F 1  of the LED element  31  to suppress return light to its phototransistor element  32 , thereby reducing the noise thereof. 
         [0047]    In  FIGS. 6A and 6B , which are perspective views illustrating modifications of the light emitting and receiving packages of  FIGS. 5A and 5B , the resin layer  33 ′ of  FIGS. 5A and 5B  with the sloped face portion is replaced by a resin layer  33 ″ into which a reflective layer  61  made of metal or the like is inserted, to thereby partition the resin layer  33 ″ for the LED element  31  and the phototransistor element  32 . In this case, the reflective layer  61  suppresses return light from the LED element  31  to its phototransistor element  32 , thereby reducing the noise thereof. 
         [0048]    An operation of the optical touch panels of  FIGS. 1 and 4  is explained next with reference to  FIGS. 7A ,  7 B,  7 C and  7 D. 
         [0049]    As shown in  FIGS. 7A and 7B , the LED element  31  of the light emitting and receiving packages  3 X″-a ( 3 Y″-a) and the LED elements  31  of the light emitting and receiving packages  3 X″-b ( 3 Y″-b) are time-divisionally operated, so that the LED elements  31  of the light emitting and receiving packages  3 X″-a ( 3 Y″-a) are not operated simultaneously with the LED elements  31  of the light emitting and receiving packages  3 X″-b ( 3 Y″-b). On the other hand, as shown in  FIGS. 7C and 7D , the phototransistor element  32  of the light emitting and receiving packages  3 X″-a ( 3 Y″-a) and the phototransistor element  32  of the light emitting and receiving packages  3 X″-b ( 3 Y″-b) are operated in synchronization with the operations of the LED elements  31  of both of the light emitting and receiving packages  3 X″-a and  3 X″-b ( 3 Y″-a and  3 Y″-b), to receive transmissive light from the LED elements  31  and reflected light from objects such as fingers. 
         [0050]    Thus, the interference between the LED elements  31  of the light emitting and receiving packages  3 X″-a ( 3 Y″-a) and the LED elements  31  of the light emitting and receiving packages  3 X″-b ( 3 Y″-b) can be avoided. 
         [0051]    In the above-described embodiments, note that only the X-direction light emitting and receiving packages  3 X″-a and  3 X″-b (and the light guide lenses  4 X-a and  4 X-b) can be provided without the Y-direction light emitting and receiving packages  3 Y″-a and  3 Y″-b (and the light guide lenses  4 Y-a and  4 Y-b). 
         [0052]    Also, in the above-described embodiments, the X-direction and Y-direction need not always be orthogonal to each other. 
         [0053]    It will be apparent to those skilled in the art that various modifications and variations can be made in the presently disclosed subject matter without departing from the spirit or scope of the presently disclosed subject matter. Thus, it is intended that the presently disclosed subject matter covers the modifications and variations of the presently disclosed subject matter provided they come within the scope of the appended claims and their equivalents. All related or prior art references described above and in the Background section of the present specification are hereby incorporated in their entirety by reference.