Patent Publication Number: US-2010117989-A1

Title: Touch panel module and touch panel system with same

Description:
BACKGROUND 
     1. Technical Field 
     The present disclosure generally relates to control systems, and particularly to touch panel modules, and touch panel systems with the touch panel module. 
     2. Description of Related Art 
     With the rapid development of science and technology, portable electronic devices, such as notebook computers, personal digital assistants (PDAs), mobile phones, global positioning systems (GPSs) and multimedia players, are now widely used in many people&#39;s lives. A typical portable electronic device is equipped with a number of mechanical input keys, and a display for displaying information (e.g., characters, pictures, etc.) thereon. The keys are used to input information/commands to the portable electronic device. However, with the ongoing trend of portable electronic devices becoming more and more multifunctional and miniaturized, the keys are commonly considered to take up a significant and unduly large amount of space. 
     Therefore, what is needed is a touch panel module which can overcome the limitations described, and a touch panel system with the touch panel module. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Many aspects of the present embodiments can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present embodiments. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
         FIG. 1  is a schematic, isometric view of a touch panel system according a first embodiment, the touch panel system including a touch panel module and a central processing unit (CPU) electrically coupled to the touch panel module. 
         FIG. 2  is an exploded view of the touch panel system shown in  FIG. 1 . 
         FIG. 3  is a cross sectional view of the touch panel module taken along the line IIII-III of  FIG. 1 , the touch panel module including a plurality of displacement sensors. 
         FIG. 4  is a schematic view of the displacement sensor working principle of  FIG. 2 . 
         FIG. 5  is a cross sectional view of the touch panel module of  FIG. 3  when touched at a point P. 
         FIG. 6  is a cross sectional view of a touch panel module according to a second embodiment. 
         FIG. 7  is a cross sectional view of a touch panel module according to a third embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIGS. 1-3 , a touch panel system  100 , in accordance with a first embodiment, includes a touch panel module  10 , and a central processing unit (CPU)  20  electrically coupled to the touch panel module  10 . 
     The touch panel module  10  includes a touch panel  11 , a supporting body  12  facing and under the touch panel  11 . There are four first elastic members  13   a,    13   b,    13   c,    13   d  sandwiched between the touch panel  11  and the supporting body  12 . There are four displacement sensors  14   a,    14   b,    14   c,    14   d  mounted on the surface and facing the touch panel  11  of the supporting body  12 . There is a receiving frame body  15  for receiving the touch panel  11  and the supporting body  12  therein. There is also a protecting film  16  mounted on the upper surface of the touch panel  11  for protecting the touch panel  11  from contamination. 
     The touch panel  11  is light pervious. The touch panel  11  includes a touch surface  112 , and a reflection surface  114  opposite to the touch surface  112 . The touch surface  112  is configured for being touched by a user. An infrared reflection film  1142  is mounted on the reflection surface  114 . The infrared reflection film  1142  reflects infrared rays to prevent infrared rays passing through the touch panel  11  from an infrared emitter  142  (see  FIG. 4 ). In this embodiment, the touch panel  11  is square shaped. 
     The supporting body  12  includes a supporting surface  124  facing the reflection surface  1142 . In this embodiment, the supporting body  12  is a square shaped fluid crystal display plate. In other embodiment, the supporting body  12  can instead be a light pervious plate. 
     The four first elastic members  13   a,    13   b,    13   c,    13   d  are respectively disposed in four corners of the supporting body  12 . Each of the four first elastic members  13   a,    13   b,    13   c,    13   d  is deformable along a direction X substantially perpendicular to the touch surface  112 . One end of each of the first elastic members  13   a,    13   b,    13   c,    13   d  is connected to the touch panel  11 . Other end of each of the first elastic members  13   a,    13   b,    13   c,    13   d  is connected to the supporting body  12  to connect the touch panel  11  to the supporting body  12 . In this embodiment, the first elastic members  13   a,    13   b,    13   c,    13   d  are springs with the same elasticity coefficient. 
     The four displacement sensors  14   a,    14   b,    14   c,    14   d  are respectively mounted in four corners of the supporting surface  124 , and near the respective first elastic members  13   a,    13   b,    13   c,    13   d  for sensing deformations of the respective first elastic members  13   a,    13   b,    13   c,    13   d.    
     The middle potion of the protecting film  16  is adhered to the touch surface  12  of the touch panel  11 . The periphery of the protecting film  16  is adhered to an inner wall of the frame body  15  to connect the frame body  15  to the touch panel  11  forming a seal to protect the touch panel  11  from contamination. 
     Referring also to  FIG. 4 , each of the displacement sensors  14   a,    14   b,    14   c,    14   d  includes the infrared emitter  142 , a collimating lens  144 , a focusing lens  146 , and an infrared sensor  148 . The collimating lens  114  receives infrared rays from the emitter  142 , and collimates the infrared rays into collimated rays. The collimated rays are reflected to the focusing lens  146  by the infrared reflection film  1142  mounted on the reflection surface  114 , then, converged by the focusing lens  146 , and finally received by the infrared sensor  148 . The infrared sensor  148  can sense a location of the edge of the reflection surface  114  according to the amount of the received infrared rays. 
     When the touch panel  11  shifts, the infrared sensor  148  can sense a displacement of the edge of the touch panel  11  according to a difference between the amount of the received infrared rays before and after the touch panel  11  is shifted. In other words, the infrared sensor  148  can sense the deformation of the first elastic member  13   a.  In other embodiments, the displacement sensor  14   a  can instead be a strain gauge displacement sensor, an inductive displacement sensor, an eddy current displacement sensor, a differential transformer displacement sensor, or a hall displacement sensor. 
     Referring also to  FIG. 5 , the central point of the touch panel  11  is defined as origin of coordinates O, when a touch point P of the touch surface  112  is touched by the user with a force F. Since the first elastic members  13   c,    13   d  are far away from the touch point P, when in equilibrium, the forces of the first elastic members  13   c,    13   d  can be ignored. Thus, the following equation can be obtained: 
         F=F   1   +F   2    (1), 
     wherein F 1 =kx 1 , F 2 =kx 2 , k is the elasticity coefficient of the first elastic member  13   a,  x 1 , x 2  are deformation of the respective first elastic members  13   a,    13   b.  Since a moment by the force F about the touch point P is zero, the moments by the forces F 1 , F 2  about the touch point P must be the total moment about the touch point P, and, when in equilibrium, this is zero. Thus, the following equation can be obtained: 
     
       
         
           
             
               
                 
                   
                     
                       
                         F 
                         1 
                       
                        
                       
                         ( 
                         
                           
                             L 
                             2 
                           
                           - 
                           
                             L 
                             x 
                           
                         
                         ) 
                       
                     
                     = 
                     
                       
                         F 
                         2 
                       
                        
                       
                         ( 
                         
                           
                             L 
                             2 
                           
                           + 
                           
                             L 
                             x 
                           
                         
                         ) 
                       
                     
                   
                   , 
                 
               
               
                 
                   ( 
                   2 
                   ) 
                 
               
             
           
         
       
     
     wherein L is the distance from the first elastic members  13   a  to the first elastic members  13   b,  L x  is the vertical distance from the touch point P to the origin of coordinates O (see  FIG. 1 ). 
     According to the above equations (1) and (2), the following equation can be obtained: 
     
       
         
           
             
               L 
               x 
             
             = 
             
               
                 
                   Lk 
                    
                   
                     ( 
                     
                       
                         x 
                         1 
                       
                       - 
                       
                         x 
                         2 
                       
                     
                     ) 
                   
                 
                 
                   2 
                    
                   F 
                 
               
               . 
             
           
         
       
     
     Therefore, the touch panel could be constructed with a relatively large display panel  11  and first elastic members  13   a,    13   b,    13   c,    13   d  with relatively large elasticity coefficient. In this case, L is close to the width of the touch panel  11 . When the force F is applied on the touch panel  11 , the force F is far smaller than Lk. Therefore, a change of the force F may be ignored relative to Lk. In other words, the force F can be considered to be a constant, and can be known by testing during design of the touch panel  11 . For example, a plurality of forces F experiment  can be tested by performing a plurality of touches on different positions of the touch panel  11 ; then, an average value of the forces is found and taken as F. Similarly, a coordinate L y  (see  FIG. 1 ) can be known by the same way of obtaining L x . 
     The CPU  20  is electrically coupled to the displacement sensors  14   a,    14   b,    14   c,    14   d.  The CPU  20  is configured for receiving deformation data x 1 , x 2 , and so on, from the displacement sensors  14   a,    14   b,    14   c,    14   d,  calculating the coordinates L x  and L y  of the touch point P according to the data, and determining the touch point P of the touch surface  112  based on the L x  and L y . 
     Referring to  FIG. 6 , a touch panel module  10   a,  in accordance with a second embodiment, includes a touch panel  11   a  having a touch surface  112   a,  and a frame body  15   a.  Most of the structure of the touch panel module  10   a  is similar to that of the touch panel module  10 , expect that, the touch panel module  10   a  also includes a plurality of second spring connecting members  18   a.  The two ends of each second spring connecting member  18   a  are respectively mounted on the touch surface  112   a  of the touch panel  11   a  and the inner wall of the frame body  15   a.    
     Referring to  FIG. 7 , a touch panel module  10   b,  in accordance with a third embodiment, includes a touch panel  11   b,  a supporting body  12   b,  four first elastic members  18   b,  and four displacement sensor  17   b.  The touch panel  11   b  includes a touch surface  112   b,  and a reflection surface  114   b  opposite to the touch surface  112   b.  The supporting body  12   b  is a frame body, and includes a bottom plate  122   b  defining an opening  123   b  at the central thereof. The bottom plate  122   b  includes a ring-shaped supporting surface  124   b  facing to the reflection surface  114   b.  The displacement sensors  17   b  are respectively mounted in four corners on the supporting surface  124   b.  Four infrared reflection films  1142   b  are respectively disposed in four corners of the reflection surface  114   b,  respectively responding to the four displacement sensors  17   b.  In other embodiment, the bottom plate  122   b  can instead be a light pervious plate without an opening. 
     While certain embodiments have been described and exemplified above, various other embodiments will be apparent to those skilled in the art from the foregoing disclosure. The disclosure is not limited to the particular embodiments described and exemplified but is capable of considerable variation and modification without departure from the scope of the appended claims.