Abstract:
A touch point detecting device is provided. The touch point detecting device comprises a plurality of electrodes and a scanning unit connected to said electrodes and scanning said electrodes with at least two variable excitation signal frequencies. A touch point detecting method is also provided. By means of the touch point detecting device, the electrode border as well as the integrated circuit package of the processor is reduced without reducing the detection accuracy of touch points.

Description:
BACKGROUND OF THE INVENTION 
     This application claims the benefit of People&#39;s Republic of China Application No. 201110152534.2, filed May 28, 2011. 
     FIELD OF THE INVENTION 
     The invention relates to the touch points detecting technology, especially to a touch points detecting device and the detecting method thereof. 
     DESCRIPTION OF THE RELATED ART 
     The technology of inputting data into electronic devices by touching is widely used. These electronic devices usually adopt the touch points detecting device to sense the touch action and generate relative electric signals for the subsequent operation. The touch points detecting device used in actual use usually is presented in the form of touch panels and touch screens. 
     According to the different touch point detecting principles, the touch points detecting device could be classified into resistive-type, capacitive-type, optical-type, electromagnetic-type, acoustic-type etc. The working principle of a capacitive touch points detecting device is that the user uses conductive touch objects such as fingers or a stylus to touch the surface of the device leading to capacitance changes at the touch points on the device surface; the processor detects the coordinates of the touch points in accordance with the capacitance changes. 
     In order to cooperate with the different electronic devices, various capacitive touch points detecting devices are developed, such as the projective capacitive touch points detecting device. The electrodes of the projective capacitive touch points detecting device include the lattice electrodes and the single axial electrodes. As far as the single axial electrodes are concerned, as each electrode has resistance, the excitation signals passing through electrodes will be attenuated coupled with the corresponding changes of the output values generated on the electrodes. As shown in  FIG. 1 , certain variation relation exists between the output value of each scanned electrode and the distance of the end providing excitation signals. Therefore, the position of the touch point on the electrodes can be determined based on the available variation relation. 
     If the excitation signals are only provided from one end of electrodes, which is called single-routing type, it will cause different output values generated for the same touch point position or the same output value generated for different touch point positions, which will further cause errors when detecting the touch point position with different size touch area by touch objects. Therefore, in order to reduce the influence caused by the touch area on detecting the touch point position, excitation signals are provided separately from both ends of electrodes, called the dual-routing type. As shown in  FIG. 2 , the touch point detecting device  1 , with the single axial electrode possessing the conventional dual-routing type, includes the electrodes  2 , the conductive lines  3  and  4 , the processor  5 , wherein the electrodes  2  have both ends A and B. The end A of the electrodes  2  is connected to the processor  5  with the conductive lines  3 , and the end B of the electrodes  2  is connected to the processor  5  with the conductive lines  4 . As shown in  FIG. 3 , when the end A is scanned, the curve of the variation relations between the output values and the distance of the touch position from the end A is defined as La; when the end B is scanned, the curve of the variation relation between the output value and the distance of the touch position also from the end A is defined as Lb. Therefore, by using the relation between the two variable curves La and Lb, two output values Dt 1  and Dt 2  can be obtained at the same touch position T which can be calculated in accordance with the two output values. 
     In view of the dual-routing touch point detecting device, each electrode needs two conductive lines, as a result of which larger insulating area is required in the surrounding of the electrodes to lay two conductive lines connecting the electrode. In addition, when integrated with the small-size device such as the portable electronic device, the touch point detecting device will be confined. Moreover, as far as the processor is concerned, the more the conductive lines, the more output/input ports (I/O pins) will need to be provided. Therefore, the processor would need a larger integrated circuit package. 
     SUMMARY OF THE INVENTION 
     An objective of the present invention is to provide a touch point detecting device to reduce the electrode border as well as the integrated circuit package of the processor without reducing the detection accuracy of touch points. 
     The touch point detecting device comprises a plurality of electrodes and a scanning unit connected to said electrodes and scanning said electrodes with at least two variable excitation signal frequencies. 
     Another objective of the present invention is to provide a touch point detecting method. 
     The touch point detecting method comprises: (a) scanning said electrodes with at least two variable excitation signal frequencies to detect output values generated on said electrodes where at least one touch points occur; and (b) calculating output value differences of said output values to detect positions of said touch points on said electrodes. 
     By adopting the touch point detecting device and the detecting method thereof, the smaller electrode border and the smaller integrated circuit package can be provided at the same time of keeping the relatively high accuracy of the touch point detection so as to favorably realize the integration with small-size devices and reduce the wastage of the production materials and other production costs. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The skilled artisan will understand that the drawings, described below, are for illustration purposes only. The drawings are not intended to limit the scope of the present teachings in any way. Like reference numerals designate corresponding parts throughout the several views. 
         FIG. 1  is a schematic diagram of the curves concerning the variation relation between the output value of the scanned electrodes and the distance of the end providing the excitation signals from the touch position; 
         FIG. 2  is a structural schematic view of the touch point detecting device possessing the conventional dual-routing type; 
         FIG. 3  is the schematic diagram of the curves concerning the variation relation between the output values for the electrodes of the detection device and the distance of the touch point from the end A of  FIG. 2 ; 
         FIG. 4  is the planar structural schematic diagram of the first embodiment of the touch point detecting device of the present invention; 
         FIG. 5  is the planar structural schematic diagram of the second embodiment of the touch point detecting device of the present invention; 
         FIG. 6  is the planar structural schematic diagram of the third embodiment of the touch point detecting device of the present invention; 
         FIG. 7  is the planar structural schematic diagram of the fourth embodiment of the touch point detecting device of the present invention; 
         FIG. 8  is the schematic diagram of the curves concerning the variation relation between the output value and the distance of the touch point from the end A while scanning the same electrode with two different frequency excitation signals; 
         FIG. 9  is the flowchart of the first embodiment of the method of detecting a touch point of the present invention; 
         FIG. 10  is the flowchart of the second embodiment of the method of detecting a touch point of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     As shown in  FIG. 4 , the touch point detecting device  100  of the first embodiment of the present invention includes a plurality of electrodes  110  with the first end A and the second end B, a plurality of conductive lines  120  and a processor  130 . The electrodes  110  extend along the same direction named the first direction X, and are arranged in parallel along the second direction Y. The first end A of each electrode  110  is connected to the processor  130  with the conductive line  120 . The touch point detecting device  100  also includes the scanning unit  140  connected to the first end A of each electrode  110 , which can be used to provide at least two variable excitation signal frequencies to the electrode  110  for scanning. According to the different circuit design requirement, the scanning unit  140  can be set within the processor  130  to form an overall component and also devised solely as an individual component separated from the processor  130  which means that the scanning unit  140  is set outside the processor  130 , both being electrically connected by the conductive line or other electrical connection ways (not shown). 
     The shape of the electrode  110  is not limited into the strip shown in FIG. °  4 , also includes other irregular geometrical shapes like polygons. The electrode  210  of the touch point detecting device  200  in the second embodiment shown in  FIG. 5  is trapezium. 
     As shown in  FIG. 6 , the touch point detecting device  300  of the third embodiment, similar to the touch point detecting device  100  of the first embodiment, includes a plurality of electrodes  310  having the first end A and the second end B, the conductive lines  320 , the processor  330  and the scanning unit  340 . The difference is that each electrode  310  includes a plurality of conductive units  311  and a plurality of conductive lines  312 . The conductive units  311  are separated mutually and connected by the conductive lines  312 . The layout of other components of the touch point detecting device  300  in the third embodiment is same as that of the touch point detecting device  100  in first embodiment. 
     As shown in  FIG. 7 , the difference between the touch point detecting device  400  of the fourth embodiment and the touch point detecting device  100  of the first embodiment is that a plurality of electrodes  410  can be divided into the first electrodes  410   a  along the first direction X and the second electrodes  410   b  along the second direction Y, wherein the first electrodes  410   a  are connected to a processor  430  with the first conductive lines  420   a , the second electrodes  410   b  are connected to the processor  430  with the second conductive lines  420   b.    
     According to different actual design requirement, the electrodes of the touch point detecting device of the present invention can be made of transparent materials such as indium tin oxides and also made of opaque materials such as metal. For example, when electrodes are opaque, they can be used as the touch pad of the electronic devices like notebook computers etc; when electrodes are transparent, they can be installed on the surface of light emitting display devices like monitors to form the touch screen. 
     The number of electrodes in the touch point detecting device of the present invention is at least two, wherein the electrode number can be determined by the size and the resolution of the touch point detecting device. Generally, the higher the resolution, the smaller the pixel required, which means the higher electrode number; the bigger the size of the touch point detecting device is, the more the electrode number is. Moreover, the first direction X and the direction Y are intersected with each other. 
     Taking the touch point detecting device of the first embodiment as an example, as shown in  FIG. 4 , the touch point detecting device  100  must be calibrated before detection, the output values generated by scanning the first end A and the second end B of the electrode  110  with variable excitation signal frequencies are defined and recorded as the baseline output values of detecting the touch point position. First of all, the touch object is contacted with the first end A of any one electrode  110 , which means that the touch point is at the first end A; the scanning unit  140  scans the electrode  110  with the first excitation signal frequency f 1 ; the processor  130  detects and records the first baseline output value Da 1 ; and then the electrode  110  is scanned with the second excitation signal frequency f 2  (f 2 &lt;f 1 ); the processor  130  detects and records the baseline output value Da 2 ; and then the processor  130  calculates the first baseline output value difference Da=Da 1 −Da 2  at the first end A according to two baseline output values Da 1  and Da 2 . In the same manner, the electrode  110  is scanned respectively with the same the first excitation signal frequency f 1  and the second excitation signal frequency f 2  mentioned above via the contact of the same touch object with the same electrode  110 ; the processor  130  respectively gets the baseline output values Db 1  and Db 2  to proceed for calculating the second baseline output value difference Db=Db 1 −Db 2  at the second end B. In accordance with the detected baseline output values Da 1 , Da 2 , Db 1  and Db 2  when the first end A and the second end B of the electrode  110  are scanned with the first excitation signal frequency f 1  and the second excitation signal frequency f 2 , the curves of the variation relation L 1  and L 2  of output value of the electrode and the distance of the touch point from the first end A can be drawn as shown in  FIG. 8 . 
     When the touch point C occurs on the surface of the touch point detecting device as shown in  FIG. 4 , the position of the touch point C can be detected in the flowing process of the first embodiment of the touch point detecting method as shown in  FIG. 9 . After starting the initial step  10 , in the step  11 , the scanning unit  140  scans all electrodes  110  with the first excitation signal frequency f 1 , wherein the scanning unit  140  can scan all electrodes  110  one at a time (sequentially or in any order) or synchronously. In the step  12 , the processor  130  determines whether the output value is generated, if not, the process then returns to the step  11 ; if yes, the process flows to the step  13 . In step  13 , the processer detects the first output value Dx 1  and the electrode  110  generating the first output value Dx 1 . 
     In the step  14 , the scanning unit  140  scans the electrode  110  generating the first output value in the step  13  with the second excitation signal frequency f 2 . In the step  15 , the processor  130  detects the second output value Dx 2  generated by the electrode  110 . In the step  16 , the processor  130  calculates the position Yc of the touch point C in the second direction Y by means of interpolation. 
     In the step  17 , the processor  130  calculates the output value difference Dx=Dx 1 −Dx 2  in accordance with the first output value Dx 1  detected in the step  13  and the second output value Dx 2  detected in the step  15 ; as shown in  FIG. 8 , the baseline output value differences Da, Db, the output value difference Dx of the touch point C and the distance between the first end A and the second end B form the proportional relation. If the position Xa of the first end A is defined as the origin of coordinate named Xa=0, the distance of the second end B from the first end A is defined as Xb. Therefore, according to the baseline output value differences Da, Db of the electrode  110  pre-stored in the processor, via the formula below: 
             Xc   =       x   b     -         (       D   x     -     D   b       )       (       D   a     -     D   b       )       ⁢     (     x   b     )               
To calculate the distance Xc of the touch point U on the electrode  110  from the first end A, which means the position of the touch point C in the first direction X. In the step  18 , the processor  130  outputs the positions Xc, Ye of the touch point C in the first direction X and in the second direction Y.
 
     According to the design requirement of different scanning methods, the touch point occurring on the surface of the touch point detecting device of the present invention can be detected by the flowing process of the second embodiment of the touch point detecting method shown in  FIG. 10 , which is essentially similar to the first embodiment of the touch point detecting method. The difference is that it is not necessary to detect the electrode  110  generating output values in the step  23 . Therefore, when executing the step  24 , the scanning unit  140  scans all the electrodes  110  with the second excitation signal frequency f 2 . 
     The above two variable excitation signal frequencies can be matched randomly, such as f 1 =1.2 MHz, and f 2 =380 kHz. In order to match different accuracy for detecting touch point, two or more variable excitation signal frequencies can be adopted for scanning the electrodes  110  respectively to calculate the average value of the touch point position Xc in the first direction. 
     The above processor includes the storage unit, the receiving unit, the calculating unit and the output unit. The storage unit is used to store the baseline output value differences Da and Db as well as the curves of the variation relation L 1  and L 2  of output value on the electrode and the distance of the touch point from the first end A; the receiving unit receive the output values generated by scanning the electrodes; The calculating unit performs the role of calculating the baseline output value differences Da, Db of the electrode, the output value difference Dx and the positions Xc, Yc of the touch point C. The results, such as the positions Xc, Yc of the touch point C, are being output to subsequent operation by the outputting unit. 
     The fourth embodiment of the touch point detecting device is regarded as two intersecting and overlapping electrode layers of the first embodiment. Therefore, the touch point detecting method mentioned above is implemented on the first electrodes  410   a  along the first direction X to calculate the position Xc of the touch point on the first electrodes  410   a , while the touch point detecting method is implemented on the second electrodes  410   b  along the second direction Y to calculate the position Yc of the touch point on the second electrodes  410   b.    
     Because the touch points generated on each electrode can be calculated separately by means of the mentioned touch point detecting method, when two or more touch points appear synchronously on the surface of the touch point detecting device and not on the same electrode, the position of each touch point can be detected by means of the touch point detecting method of the present invention. 
     While certain embodiments have been shown and described, various modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Therefore, it is to be understood that the present invention has been described by way of illustration and not limitations.