Abstract:
The present disclosure relates to a tactile sensor including a first substrate on which a first electrode is formed; a second substrate on which a second electrode and a coupling hole is formed so that the first electrode may be inserted into the coupling hole; and a dielectric covering the first electrode and the second electrode, and thus not only having flexibility and elasticity, but also requiring a reduced number of wires to be used when sending and receiving signals, making it is easier to manufacture and saving costs.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to and the benefit of Korean Patent Application No. 10-2015-0127927, filed on Sep. 9, 2015, in the Korean Intellectual Property office, the entire contents of which are incorporated herein by reference in their entirety. 
     BACKGROUND 
     Field 
     The present disclosure relates to a tactile sensor, and more particularly, to a tactile sensor that not only has flexibility and elasticity, but also requires a reduced number of wires to be used for sending and receiving signals, and is thereby easy to manufacture and saves costs. 
     Description of Related Art 
     Recently, as industrial technologies develop, there are active efforts to develop industrial robots and medical robots as tools capable of carrying out dangerous operations and detailed operations instead of human beings. 
     At the early stages of development, these robots were designed to perform simple operations repeatedly, but recently, there is a demand to develop intelligent robots of evolved forms equipped with the appearance, thoughts and even behaviors of human beings such as humanoids so that they can gradually perform more complicated operations. 
     In the case of the aforementioned intelligent robots, since it its practically impossible for designers to input all the operation programs for coping with every external situation one by one, the robots are required to recognize and determine the external environment (or stimulation) for themselves using their sensors that are similar to the sensory organs of human beings, and to behave accordingly. 
     One of the most important technologies related to these intelligent robots is the technology of tactile sensors or contact sensors capable of sensing the size, contacting position and the like of the external load contacting the intelligent robot. 
     Capacitor type sensors are one type of conventional tactile sensors. Capacitor type sensors are configured in the form of a general capacitor where a dielectric is disposed between an anode and a cathode. Thus, when the dielectric is deformed by an external stimulation, a change in capacitance occurs, and thus the external stimulation can be sensed using this change in capacitance. 
     However, conventional tactile sensors have limitations in reducing their thickness, and another problem is that the durability of the electrodes contacting external elements cannot be secured. Further, when sensing an external stimulation, in an automatic control, due to the electrode exposed towards outside, a disturbance may occur that can cause a change in the amount of control besides the reference input. Further, since wires are required as many as the number of cells in order to connect the anode and cathode in each cell (the minimum unit forming a group of anode and cathode) that constitutes the sensor, it is difficult and complicated to manufacture the sensor, which is a disadvantage. 
     Therefore, there is an emerging demand for a tactile sensor that compensates the aforementioned problems. 
     SUMMARY 
     Therefore, a purpose of the present disclosure is to solve the aforementioned problems of prior art, that is, to provide a tactile sensor having flexibility and elasticity. 
     Another purpose of the present disclosure is to provide a tactile sensor with reduced number of wires to be used to send and receive signals, and is therefore easy to manufacture and saves costs. 
     According to an embodiment of the present disclosure, there is provided a tactile sensor including a first substrate on which a first electrode is formed; a second substrate on which a second electrode having a polarity opposite to that of the first electrode is formed, and on which a coupling hole is formed in a position spaced apart from the second electrode so that the first electrode may be inserted into the coupling hole and coupled thereto; and a dielectric formed on top of the second substrate to cover the first electrode and the second electrode inserted into the coupling hole and coupled thereto. 
     Here, the first substrate may include a plurality of first plate bodies each having one said first electrode; and a plurality of first connecting bodies of which one side is connected to one of the first plate bodies, and another side is connected to another one of the first plate bodies or to the first substrate, and the second substrate may include a plurality of second plate bodies each having one said second electrode and one said coupling hole; and a plurality of second connecting bodies of which one side is connected to one of the second plate bodies, and another side is connected to another one of the second plate bodies or to another portion of the second substrate. 
     Here, on a portion of the second connecting body, a connecting hole may be formed to connect the coupling hole formed in the one of the second plate bodies and the coupling hole formed in the another one of the second plate bodies. 
     Here, the first substrate may further include a first connecting electrode that connects the first electrode formed on the one of the first plate bodies and the first electrode formed on the another one of the first plate bodies, the second substrate may further include a second connecting electrode that connects the second electrode formed on the one of the second plate bodies and the second electrode formed on the another one of the second plate bodies, and the first connecting electrode may be inserted into the connecting hole. 
     Here, either or both of the first connecting body and the second connecting body may be formed in a wave form of zig-zag shape. 
     Here, the tactile sensor may further include an insulator between the first substrate and the second substrate. 
     Here, a height of the first electrode inserted into the coupling hole and coupled thereto may be identical to a height of the second electrode. 
     According to the present disclosure, a tactile sensor having flexibility and elasticity is provided. 
     Further, the number of wires to be used to send and receive signals is reduced, thereby making it easier and inexpensive to manufacture the tactile sensor. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Example embodiments will now be described more fully hereinafter with reference to the accompanying drawings; however, they may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the example embodiments to those skilled in the art. 
       In the drawing figures, dimensions may be exaggerated for clarity of illustration. It will be understood that when an element is referred to as being “between” two elements, it can be the only element between the two elements, or one or more intervening elements may also be present between two elements. Like reference numerals refer to like elements throughout. 
         FIG. 1  is an exploded view illustrating a portion of a first substrate and a second substrate of a tactile sensor according to an embodiment of the present disclosure; 
         FIG. 2  is an assembled view of the portion of the first substrate and the second substrate illustrated in  FIG. 1 ; 
         FIG. 3  is a perspective view illustrating a state of forming a dielectric on the first substrate and the second substrate coupled to each other; 
         FIG. 4  is a cross-sectional view of a portion of the tactile sensor illustrated in  FIG. 3 ; and 
         FIGS. 5A to 5D  are views illustrating the manufacturing order of the tactile sensor according to an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Hereafter, a tactile sensor according to an embodiment of the present disclosure will be explained in detail with reference to the drawings attached. 
       FIG. 1  is an exploded view illustrating a portion of a first substrate and a second substrate of a tactile sensor according to an embodiment of the present disclosure,  FIG. 2  is an assembled view of a portion of the first substrate and the second substrate illustrated in  FIG. 1 . Further,  FIG. 3  is a perspective view illustrating a state of forming a dielectric on the first substrate and second substrate coupled to each other, and  FIG. 4  is a cross-sectional view of a portion of the tactile sensor illustrated in  FIG. 3 . 
     Referring to  FIGS. 1 to 4 , a tactile sensor according to an embodiment of the present disclosure includes a first substrate  100 , a second substrate  200 , a dielectric  300  and an insulator  400 . 
     The first substrate  100  is an element where a first electrode  112  is to be formed. The first substrate  100  may be a polymer film (polyimide film, polyester film) substrate or a glass substrate. The present disclosure uses a flexible printed circuit board (FPCB) using a polyimide film, that is a polymer film having excellent electrical, thermal, mechanical and physical/chemical characteristics together with flexibility. The first substrate  100  used in the present disclosure includes a plurality of first plate bodies  110  and a plurality of first connecting bodies  120 . The first plate body  110  is where one said first electrode  112  is formed. One side of the first connecting body  120  may be connected to one of the first plate bodies  110 , and the other side of the first connecting body  120  may be connected to another one of the first plate bodies  110 , or to another portion of the first substrate  100  besides the first plate bodies  110 . That is, all of the first substrate  100  may consist of the first plate bodies  110 , or otherwise, only a portion of the first substrate  100  may consist of the first plate bodies  110 . Here, the first connecting body  120  is formed in a wave form of zig-zag shape so that it has flexibility and elasticity such as a spring. The first electrode  112  may be made of materials such as indium tin oxide (ITO), carbon nanotube (CNT), graphene and silver nano wire, etc. Such a first electrode  112  may be configured to have a plus electrode (anode) or a minus electrode (cathode) depending on circumstances, but in the present disclosure, the first electrode  112  has a minus polarity. Further, the structure of the first electrode  112  may vary as well. That is, the first electrode  112  may have a single-layer structure or a multiple-layer structure. Meanwhile, although it is illustrated in the drawings that the first electrode  112  has a rectangular shape, there is no limitation thereto. That is, the shape of the first electrode  112  may vary, for example, a polygonal shape and semicircular shape, etc. Further, the first substrate  100  further includes a first connecting electrode  122  that connects the first electrode  112  formed on one of the first plate bodies  110  and the first electrode  112  formed in another one of the first plate bodies  110 . Such a first connecting electrode  122  is formed on the first connecting body  120  that connects the first plate bodies  110  neighboring each other. 
     The second substrate  200  is an element where a second electrode  212  having a polarity opposite to that of the first electrode  112 , that is, a plus electrode, is formed. It is also an element where a coupling hole  214  is formed in a location spaced apart from the second electrode  212  such that the first electrode  112  may be inserted into the coupling hole  214  and thus coupled to the second substrate  200 . The second substrate  200  consists of a plurality of second plate bodies  210  and a plurality of second connecting bodies  220  similarly as the first substrate  100  mentioned above. The second plate body  210  is where one said second electrode  212  and one said coupling hole  214  are formed. 
     One side of the second connecting body  220  is connected to one of the second plate bodies  210 , and another side of the second connecting body  220  is connected to another one of the second plate bodies  210  or to another portion of the second substrate  200  besides the second plate bodies  210 . That is, just as the first substrate  100 , all of the second substrate  200  may consist of the second plate bodies  210  only, or otherwise, only a portion of the second substrate  200  may consist of the second plate bodies  210 . Further, just as the first connecting body  120 , it is also desirable that the second connecting body  220  is formed in a wave form of zig-zag shape so as to have flexibility and elasticity. Here, on a portion of the second connecting body  220 , a connecting hole  222  is formed according to the shape of the second connecting body  220 . That is, a coupling hole  214  provided on the second substrate  200  and its neighboring coupling hole  214  that is close thereto are connected to each other by the connecting hole  222  formed on the second connecting body  220 . Accordingly, the first connecting electrode  122  is configured to be inserted into the connecting hole  222  just as the first electrode  112  is inserted into the coupling hole  214  of the second substrate  200  and coupled thereto. The second substrate  200  is made of a flexible printed circuit board (FPCB) just as the first substrate  100  mentioned above, and the second electrode  212  formed on the second substrate  200  may be made of a same material as or a different material from that of the first electrode  112 . For example, the first electrode  112  may be made of carbon nano tube while the second electrode  212  is made of carbon nano tube or indium tin oxide (ITO). Further, the second electrode  212  may have a single-layer structure or a multiple-layer structure, and the shape of the second electrode  212  may vary, including but not limited to, for example, a rectangular shape. Meanwhile, the second substrate  200  may further include a second connecting electrode  224  that connects the second electrode  212  formed on one of the second plate bodies  210  and the second electrode  212  formed on another one of the second plate bodies  210 . Such a second connecting electrode  224  is formed in the second connecting body  220  connecting the second plate bodies  210 , especially in the second connecting body  220  where the connecting hole  222  is not formed. 
     As aforementioned, the first electrode  112  formed on one of the first plate bodies  110  constituting the first substrate  100  is inserted through the coupling hole  214  formed in one of the second plate bodies  210  constituting the second substrate  200 , thereby forming one pair of first electrode  112  and second electrode  212 . That is, one of the first plate bodies  110  of the first substrate  100  and one of the second plate bodies  210  of the second substrate  200  are coupled to each other, forming a cell, that is a minimum unit having one first electrode  112  and one second electrode  212 . Further, as illustrated in  FIG. 3 , the first electrode  112  and the second electrode  212  is connected to a terminal T provided on a portion of the first substrate  100  and the second substrate  200  where the first plate bodies  110  and the second plate bodies  210  are not formed, configured to play the role as an entrance through which current may enter and exit. This terminal T is connected to an output control (I/O control) device (not illustrated) that controls inputting/outputting through a multiplexer (not illustrated), that is a combinational circuit generally called “Mux” and configured to select one of numerous input lines and connect it to a single output line. 
     The dielectric  300  is an element formed on top of the second substrate  200 , and configured to cover the second electrode  212  and the first electrode  112  inserted into the coupling hole  214  and coupled thereto. Here, in the present disclosure, the dielectric  300  is made of carbon micro coil (CMC), that is amorphous carbon fiber being used in various fields as an electromagnetic wave absorber, hydrogen absorber, microwave heating material, tactile proximity sensor, biological activator and the like due to its excellent electrical•chemical characteristics, and that also has excellent elasticity, thereby providing both flexibility and elasticity. 
     Meanwhile, the insulator  400  is further provided between the first substrate  100  and the second substrate  200 . Examples of the insulator  400  that may be used herein include polymer, ceramic, rubber and the like generally used in the field. 
     As aforementioned, according to the present disclosure, the first electrode  112  is formed on the first substrate  100  that constitutes one layer, and on the second substrate  200  that is formed separately from the first substrate  100  to constitute another layer, the second electrode  212  having a polarity opposite to that of the first electrode  112  is formed. These are formed in a cross stripe form, whereby the number of wires needed to send and receive signals may be minimized. Therefore, it becomes easier and more inexpensive to manufacture the tactile sensor. 
     Hereinafter, explanation will be made on an order of manufacturing the tactile sensor according to an embodiment of the present disclosure. 
       FIGS. 5A to 5D  are views illustrating the order of manufacturing the tactile sensor according to the embodiment of the present disclosure. Here, in  FIGS. 5A to 5D , one of the first plate bodies  110  of the first substrate  100  and one of the second plate bodies  210  of the second substrate  200  are coupled to each other to form a cell, that is the minimum unit having the first electrode  112  and the second electrode  212 . 
     First of all, as illustrated in  FIG. 5A , the first substrate  100  is prepared. On the first substrate  100 , that is, on the first plate body  110 , the first electrode  112  is formed. Of course, it is possible to use a first substrate  100  where a first electrode  112  is already formed beforehand, but it is also possible to prepare the first substrate  100  where the first electrode  112  is not formed, and then form the first electrode  112  with a material such as indium tin oxide (ITO), carbon nanotube (CNT), graphene and silver nano wire, etc. Here, a sputtering method may be used to form (laminate) the first electrode  112 , and it is desirable to form the first electrode  112  with carbon nanotube that has excellent adhesiveness and is inexpensive. 
     Then, as illustrated in  FIG. 5B , an insulating layer is formed on top of the first substrate  100 . Examples of the insulator  400  that may be used to form the insulating layer herein include polymer, ceramic, rubber and the like that are generally used in the field. Here, the insulator  400  should not cover the first electrode  112 . 
     After forming the insulating layer using the insulator  400 , as illustrated in  FIG. 5C , the second substrate  200  is prepared, and the first electrode  112  of the first substrate  100  is inserted into the coupling hole  114  and coupled thereto. On the second substrate  200 , that is, on the second plate body  210 , the second electrode  212  is formed. It is possible to use a second substrate  200  where the second electrode  212  is already formed beforehand just as the first substrate  100 , or otherwise, it is also possible to insert the first electrode  112  into the coupling hole  214  to couple the second substrate  200 , and then form the second electrode  212 . The second electrode  212  may be made of a material different from the first electrode  112 , but it is desirable to form the second electrode  212  with the same material (carbon nanotube) as the first electrode  112  in order to save manufacturing costs and the like. Here, it is possible to increase the efficiency of configuration by adjusting the height of the first electrode  112  and the height of the second electrode  212  being inserted into the coupling hole  214  to be identical to each other. 
     Then, as illustrated in  FIG. 5D , a dielectric layer is formed on top of the second substrate  200  from which the first electrode  112  protrudes, that is, on top of the second plate body  210 . In the present disclosure, carbon micro coil (CMC) is used as the dielectric  300  constituting the dielectric layer, thereby providing elasticity, and as the dielectric  300  covers the first electrode  112  and the second electrode  212 , the tactile sensor according to the embodiment of the present disclosure is manufactured. 
     In the drawings and specification, there have been disclosed typical embodiments of the invention, and although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation. It will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims. 
     REFERENCE NUMERALS 
     
         
         
           
               100 : FIRST SUBSTRATE 
               110 : FIRST PLATE BODY 
               112 : FIRST ELECTRODE 
               120 : FIRST CONNECTING BODY 
               122 : FIRST CONNECTING ELECTRODE 
               200 : SECOND SUBSTRATE 
               210 : SECOND PLATE BODY 
               212 : SECOND ELECTRODE 
               214 : COUPLING HOLE 
               220 : SECOND CONNECTING BODY 
               222 : CONNECTING HOLE 
               224 : SECOND CONNECTING ELECTRODE 
               300 : DIELECTRIC 
               400 : INSULATOR 
             T: TERMINAL