the following description is of the best - contemplated mode of carrying out the invention . this description is made for the purpose of illustrating the general principles of the invention , and should not be taken in a limiting sense . the scope of the invention is best determined by reference to the appended claims . fig3 shows an exemplary embodiment of a sensing device . referring to fig3 , a sensing device 3 detects a touch condition applied to a sensing array 4 . fig4 shows an exemplary embodiment of a sensing array in fig3 . as shown in fig4 , the sensing array 4 comprises sensing rows 4 - 1 ˜ 4 - n ( n is a positive integer ), and each sensing row comprises a plurality of cells . for example , the sensing row 4 - 1 comprises sensing cells c 4 - 1 ˜ c 4 - m ( m is a positive integer ). the sensing device 3 comprises a calculation unit 30 , a determination unit 31 , and a detection unit 32 . the determination unit 31 comprises a memory 310 for storing differential types of predetermined curve features and a curve processor 311 . in the embodiment , the predetermined curve features are profile forms , and the profile forms are obtained according to differential values that are not affected by interference noise . fig5 a ˜ 5c show a touch condition of a sensing row and differential values , and a profile form corresponding to the touch condition . fig5 a shows a touch condition of a sensing row 5 . assume that the sensing row 5 has a plurality of sensing cells c 5 - 1 ˜ c 5 - m . in a case that the detection of the touch condition is not affected by interference noise , when one single object 50 ( such as a finger , that is one single touch point ) touches a position corresponding to the sensing cell c 5 - 6 in the sensing row 5 , the intensity of the sensing data signals read from the sensing cells c 5 - 1 ˜ c 5 - m can be represented by a gaussian curve g 50 . at this time , a plurality of differential values is obtained according to the difference between every two sensing data signals among the sensing data signals . the differential values d 5 - 1 ˜ d 5 - 4 shown in fig5 b are the meaningful differential values when one single object 50 touches the sensing row 5 . for example , the differential value d 5 - 1 is the difference between the sensing data signals of the sensing cells c 5 - 5 and c 5 - 6 , and the differential value d 5 - 2 is the difference between the sensing data signals of the sensing cells c 5 - 6 and c 5 - 7 . a sensing curve p 50 are obtained from the differential values d 5 - 1 ˜ d 5 - 4 , as shown in fig5 c . in the embodiment , the profile forms can be represented by the following six geometry symbols : ( 1 ) regular triangle ▴: represents a full range , wherein corresponding differential values are all positive , and the differential values are increased and then decreased from the left to the right of the profile form . ( 2 ) inverted regular triangle ▾: represents full range , wherein corresponding differential values are all negative , and the differential values are decreased and then increased from the left to the right of the profile form . ( 3 ) right - angled triangle : represents a half range , wherein corresponding differential values are all positive , and the differential values are decreased from the left to the right of the profile form . ( 4 ) inverted right - angled triangle : represents a half range , wherein corresponding differential values are all negative , and the differential values are increased from the left to the right of the profile form . ( 5 ) two regular triangles ▴▴: represents two peak points of two full ranges , wherein corresponding differential values are all positive . ( 6 ) two inverted regular triangles ▾▾: represents two peak points of two full ranges , wherein corresponding differential values are all negative . referring to fig5 b ˜ 5c , when one single touch point occurs ( that is the touching of one single object 50 ), two negative differential values d 5 - 1 ˜ d 5 - 2 and two positive values d 5 - 3 and d 5 - 4 are generated . in this case , a profile form of a sensing curve p 50 obtained from the differential values d 5 - 1 ˜ d 5 - 4 is represented by . referring to fig6 a ˜ 6b , a series of differential values and a corresponding profile form in another type are shown . when one single touch point occurs , two negative differential values d 6 - 1 ˜ d 6 - 2 and three positive values d 6 - 3 and d 6 - 5 are generated . in this case , a profile form of a sensing curve p 60 obtained from the differential values d 6 - 1 ˜ d 6 - 5 is represented by ▴. referring to fig7 a and 7b , a series of differential values and a corresponding profile form in another type are shown . when one single touch point occurs , three negative differential values d 7 - 1 ˜ d 7 - 3 and two positive values d 7 - 4 and d 7 - 5 are generated . in this case , a profile form of a sensing curve p 70 obtained from the differential values d 7 - 1 ˜ d 7 - 5 is represented by ▴ . referring to fig8 a and 8b , a series of differential values and a corresponding profile form in another type are shown . when one single touch point occurs , three negative differential values d 8 - 1 ˜ d 8 - 3 and three positive values d 8 - 4 and d 8 - 6 are generated . in this case , a profile form of a sensing curve p 80 obtained from the differential values d 8 - 1 ˜ d 8 - 6 is represented by ▴▾. referring to fig9 a and 9b , a series of differential values and a corresponding profile form in another type are shown . when two touch points occur , five negative differential values d 9 - 1 ˜ d 9 - 5 and five positive values d 9 - 6 and d 9 - 10 are generated . in this case , a profile form of a sensing curve p 90 obtained from the differential values d 9 - 1 ˜ d 9 - 10 is represented by ▾▾▴. according to fig9 b , there are two peak points in the front half of the curve respectively corresponding to the differential values d 9 - 2 and d 9 - 5 . referring to fig1 a and 10b , a series of differential values and a corresponding profile form in another type are shown . when two touch points occur , five negative differential values d 10 - 1 ˜ d 10 - 5 and five positive values d 10 - 6 and d 10 - 10 are generated . in this case , a profile form of a sensing curve p 10 obtained from the differential values d 10 - 1 ˜ d 10 - 10 is represented by ▾▴▴. according to fig1 b , there are two peak points in the back half of the curve respectively corresponding to the differential values d 10 - 6 and d 10 - 8 . referring to fig1 a and 11b , a series of differential values and a corresponding profile form in another type are shown . when two touch points occur , five negative differential values d 11 - 1 ˜ d 11 - 5 and five positive values d 11 - 6 and d 11 - 10 are generated . in this case , a profile form of a sensing curve p 11 obtained from the differential values d 11 - 1 ˜ d 11 - 10 is represented by ▾▾▴▴. according to fig1 b , there are two peak points in the front half of the curve respectively corresponding to the differential values d 11 - 2 and d 11 - 5 , and there are two peak points in the back half of the curve respectively corresponding to the differential values d 11 - 6 and d 11 - 9 . the memory 310 of the determination unit 31 at least stores the profile forms p 50 , p 60 , p 70 , p 80 , p 90 , p 10 , and p 11 of fig5 b , 6 b , 7 b , 8 b , 9 b , 10 b , and 11 b in advance to serve as predetermined profile forms . fig1 shows an exemplary embodiment touch sensing method for the sensing device 3 . referring to fig3 ˜ 4 and 12 , the calculation unit 30 is coupled to the sensing array 4 . the calculation unit 30 selects one sensing row among the sensing rows 4 - 1 ˜ 4 - n to serve as a sensing row to be detected for a sensing operation ( step s 10 ). for example , the sensing row 4 - 1 is selected to serve as a sensing row to be detected . the sensing operation performed to the sensing row 4 - 1 is described in the following . the calculation unit 30 extracts sensing data signals s 4 - 1 ˜ s 4 - m from the sensing cells c 4 - 1 ˜ c 4 - m in the sensing row 4 - 1 ( step s 11 ). the sensing data signals s 4 - 1 ˜ s 4 - m respectively represent capacitance values related to the sensing cells c 4 - 1 ˜ c 4 - m . the capacitance values change with an object being approaching the sensing cells c 4 - 1 ˜ c 4 - m . the calculation unit 30 calculates the difference between every two sensing data signals among the sensing data signals s 4 - 1 ˜ s 4 - m to obtain differential values d 4 - 1 ˜ d 4 - x ( x is a positive integer , and 1 & lt ; x & lt ; m ) ( step s 12 ). the calculation unit 30 obtains a sensing curve p 40 corresponding to the sensing row 4 - 1 , according to the differential values d 4 - 1 ˜ d 4 - x ( step s 13 ). for example , referring to fig1 a ˜ 13c , an exemplary embodiment of a touch condition of a sensing row and differential values and a profile form corresponding to sensing data signals is shown . when one single object 130 ( such as finger , that is one single touch point ) touches a position near to the sensing cells c 4 - 6 and c 4 - 7 in the sensing row 5 - 1 , the intensity of the sensing data signals s 4 - 1 ˜ s 4 - m read from the sensing cells c 4 - 1 ˜ c 4 - m can be represented by a gaussian curve g 130 . the calculation unit 30 extracts sensing data signals s 4 - 1 ˜ s 4 - m from the sensing cells c 4 - 1 ˜ c 4 - m in the sensing row 4 - 1 ( step s 11 ) and calculates the difference between every two sensing data signals among the sensing data signals s 4 - 1 ˜ s 4 - m to obtain the differential values d 4 - 1 ˜ d 4 - x ( step s 12 ). the differential values d 4 - 1 ˜ d 4 - 5 shown in fig1 b are the meaningful differential values when one single object 130 touches the sensing row 4 - 1 . for example , the differential value d 4 - 1 is the difference between the sensing data signals s 4 - 5 and s 4 - 6 of the sensing cells c 4 - 5 and c 4 - 6 , and the differential value d 4 - 5 is the difference between the sensing data signals s 4 - 6 and s 4 - 7 of the sensing cells c 4 - 6 and c 4 - 7 . the calculation unit 30 obtains a sensing curve p 40 corresponding to the sensing row 4 - 1 , according to the differential values d 4 - 1 ˜ d 4 - 5 ( step s 13 ). as shown in fig1 c , in the case , the profile form of the sensing curve p 40 is represented by ▴. in some applications , the sensing row 4 - 1 may be touched by a plurality of objects . referring to fig1 a ˜ 14c , another exemplary embodiment of a touch condition of a sensing row and differential values and a profile form corresponding to sensing data signals is shown . for example , when one object 140 ( such as a finger ) touches a position near the sensing cells c 4 - 4 in the sensing row 4 - 1 , and another object 141 ( such as an finger ) touches a position near the sensing cells c 4 - 8 in the sensing row 10 , the intensity of the sensing data signals s 4 - 1 ˜ s 4 - m read from the sensing cells c 4 - 1 ˜ c 4 - m can be represented by two gaussian curves g 140 and g 141 . the calculation unit 30 extracts sensing data signals s 4 - 1 ˜ s 4 - m from the sensing cells c 4 - 1 ˜ c 4 - m in the sensing row 4 - 1 ( step s 11 ) and calculates the difference between every two sensing data signals among the sensing data signals s 4 - 1 ˜ s 4 - m to obtain the differential values d 4 - 1 ˜ d 4 - x ( step s 12 ). the differential values d 4 - 1 ˜ d 4 - 10 shown in fig1 b are the meaningful differential values when the two objects 140 and 141 touch the sensing row 4 - 1 . for example , the differential value d 4 - 1 is the difference between the sensing data signals s 4 - 1 and s 4 - 2 of the sensing cells c 4 - 1 and c 4 - 2 . the calculation unit 30 obtains a sensing curve p 40 corresponding to the sensing row 4 - 1 according to the differential values d 4 - 1 ˜ d 4 - 10 ( step s 13 ). as shown in fig1 c , in the embodiment , when the two objects 140 and 141 ( that is two touch points ) touch the sensing row 4 - 1 , there are two peak points in each of the two halves of the curve . for example , there are two peak points in the front half of the curve respectively corresponding to the differential values d 4 - 2 and d 4 - 5 , and there are two peak points in the back half of the curve respectively corresponding to the differential values d 4 - 7 and d 4 - 9 . however , in other cases ( which two touch points occur ), there are two peak points in only one of the two halves of the curve ( the front or back of the curve ). after the sensing curve corresponding to the sensing row 4 - 1 is obtained , the curve processor 311 of the determination unit 31 can perform a perfection operation to the sensing curve ( step s 14 ). the perfection operation is not limited to conventional curve perfection manners ( that is more obvious noise in the sensing curve is removed ). in the embodiment , the curve processor 311 does not perform the perfection operation to each sensing curve . that is , the step s 14 can be omitted . then , the determination unit 31 determines whether a profile form ( ▴/▾▾▴▴) of the sensing curve p 40 matches with one of the profile forms of the sensing curves p 50 . p 60 , p 70 , p 80 , p 90 , p 10 , and p 11 stored in the memory 310 ( step s 15 ). when the determination unit 31 determinates that the profile form of the sensing curve p 40 corresponding to the sensing row 4 - 1 matches with one of the profile forms of the sensing curves p 50 , p 60 , p 70 , p 80 , p 90 , p 10 , and p 11 stored in the memory 310 , the determination unit 31 notifies the detection unit 32 of the determination result . the determination result comprises that the sensing curve p 40 corresponding to the sensing row 4 - 1 matches with which one predetermined profile form . the detection unit 32 detects the touch condition of the sensing row 4 - 1 according to the determination result related to the sensing row 4 - 1 ( step s 16 ). the touch condition of the sensing row 4 - 1 comprises whether the sensing row 4 - 1 has been touched by at least one object , the number of objects touching the sensing row 4 - 1 , a position of at least one object in the sensing row 4 - 1 when the at least one object touches the sensing row 4 - 1 , and / or a touched area in the sensing row 4 - 1 when at least one object touches the sensing row 4 - 1 . after , the sensing device 3 ends the sensing operation . for example , when the determination unit 31 determinates that the profile form of the sensing curve p 40 , corresponding to the sensing row 4 - 1 , matches with the profile form ▴ of the sensing curve p 60 stored in the memory 310 , the detection unit 32 detects that the sensing row 4 - 1 is touched by one single object according to the determination result . as shown in fig1 a , the object 130 touches a position near the sensing cells c 4 - 6 and c 4 - 7 in the sensing row 4 - 1 . since the sensing curve p 40 is obtained according to the meaningful differential values d 4 - 1 ˜ d 4 - 5 , the detection unit 32 can obtain a touched position and a touched area of the single object when the single object touches the sensing row 4 - 1 . in another example , when the determination unit 31 determinates that the profile form of the sensing curve p 40 corresponding to the sensing row 4 - 1 matches with the profile form ▾▾▴▴ of the sensing curve p 11 stored in the memory 310 , the detection unit 32 detects that the sensing row 4 - 1 is touched by two single objects according to the determination result . as shown in fig1 a , the object 140 touches a position near the sensing cell c 4 - 4 in the sensing row 4 - 1 , while the object 141 touches a position near the sensing cell c 4 - 8 in the sensing row 4 - 1 . since the sensing curve p 40 is obtained according to the meaningful differential values d 4 - 1 ˜ d 4 - 10 , the detection unit 32 can obtain touched positions and touched areas of the two objects when the two objects touch the sensing row 4 - 1 . when the determination unit 31 determines that the profile form of the sensing curve corresponding to the sensing row 4 - 1 does not match one of the predetermined profile forms stored in the memory 310 , the sensing operation is ended . according to the above embodiment , after the determination unit 31 determines that the profile form of the sensing curve corresponding to the sensing row 4 - 1 does not match one predetermined profile forms stored in the memory 310 in the step s 15 and after the detection step s 16 for the sensing row 4 - 1 , the sensing operation is ended . in some embodiments , after the determination unit 31 determines that the profile form of the sensing curve corresponding to the sensing row 4 - 1 does not match one predetermined profile forms stored in the memory 310 in the step s 15 , and after the detection step s 16 for the sensing row 4 - 1 , the sensing method returns back to the step s 10 , and the calculation unit 30 can continuously select another sensing row among the sensing rows 4 - 2 ˜ 4 - n to serve as the sensing row to be detected , and the sensing operation is performed again . for example , the calculation unit 30 selects the sensing row 4 - 2 next to the sensing row 4 - 1 to serve as the sensing row to be detected . the calculation unit 30 , the determination unit 31 , and the detection unit 32 perforin the same operations as the steps s 11 ˜ s 16 . when the detection unit 32 obtains the determination result related to at least two sensing rows among the sensing rows 4 - 2 ˜ 4 - n , some sensing rows among the sensing rows 4 - 2 ˜ 4 - n , or all of the sensing rows 4 - 2 ˜ 4 - n , the detection unit 32 can detect a touch condition of the sensing array 4 according to the determination result . the touch condition of the sensing array 4 comprises whether the sensing array 4 has been touched by at least one object , the number of objects touching the sensing array 4 , a coordinate of at least one object in the sensing array 4 when the at least one object touches the sensing array 4 , and / or a touched area in the sensing array 4 when at least one object touches the sensing array 4 . according to the above description , the sensing device 3 stores several types of predetermined profile forms in advance to be compared with the profile form of the sensing curve of the sensing row to be detected . by the comparison of the profile forms , the impact of interference noise can be reduced . moreover , the sensing device 3 of the embodiment does not set the minimum threshold value . thus , when the touched area of the sensing array 4 is small , the touch condition of the sensing array 4 can be accurately detected . moreover , according to the embodiments , when the size of an object that touched the sensing array 1 is larger ( the size of the object is directly proportional to the touched area ), and the distance between every two sensing cells in one sensing row is smaller , the sensing curve obtained by the determination unit 31 can conform to real touch operation of that the object touches the sensing cells more exactly , so that the touch condition of the sensing array 4 , which is detected according to the sensing curve , can be more accurate . while the invention has been described by way of example and in tennis of the preferred embodiments , it is to be understood that the invention is not limited to the disclosed embodiments . to the contrary , it is intended to cover various modifications and similar arrangements ( as would be apparent to those skilled in the art ). therefore , the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements .