a description will now be given , with reference to the accompanying drawings , of embodiments of the present invention . a description will first be given of an embodiment of a coordinate detection device according to the present invention . fig3 is a block diagram of a coordinate detection device according to the embodiment . according to fig3 , the coordinate detection device includes a coordinate input panel 10 and a detection unit 20 . a coordinate value detected in the coordinate detection device is transmitted to a host computer 6 via a communication unit 4 . the coordinate input panel 10 includes resistive films 11 and 12 opposing each other with a space therebetween . a coordinate value is detected by an operator pressing the resistive films 11 and 12 . the resistive film 11 has a pair of electrodes 14 formed on its peripheral portion to oppose each other with an input area 13 formed therebetween . the resistive film 12 has a pair of electrodes 15 formed on its peripheral portion to oppose each other with an input area 13 formed therebetween . voltages are applied from the detection unit 20 to the respective pairs of the electrodes 14 and 15 , and the resistive films 11 and 12 are arranged so that the applied voltages cross each other at right angles . a coordinate value of a pressed ( input ) point on the input area 13 of the coordinate input panel 10 is detected by means of these voltages . for example , the electrodes 14 , to which the voltage is applied in parallel with an x - axis , detect an x - coordinate , and the electrodes 15 , to which the voltage is applied in parallel with a y - axis , detect a y - coordinate . the detection unit 20 includes transistors 21 through 25 , supply voltage terminals 26 through 29 , resistances r 1 through r 5 , a switch 5 , and a cpu ( central processing unit ) 3 . the detection unit 20 applies the voltages alternately to the electrodes 14 and 15 formed on the respective resistive films 11 and 12 of the coordinate input panel 10 so as to detect input coordinate values . the voltage from the supply voltage terminal 27 is applied to the electrodes 15 via the transistors 23 and 24 of the detection unit 20 , and the voltage from the supply voltage terminal 28 is applied to the electrodes 14 via the transistors 21 and 22 . the voltages are applied to the respective electrodes 14 and 15 by alternately switching “ on ” a pair of the transistors 23 and 24 and a pair of the transistors 21 and 22 . the resistances r 2 through r 5 are connected to the transistors 23 , 24 , 21 , and 22 , respectively , so as to control the voltages applied to the resistive films 11 and 12 . the transistor 25 is employed to detect an operator &# 39 ; s input operation to the coordinate input panel 10 by means of the voltage supplied from the supply voltage terminal 26 and controlled by the resistance r 1 . when the operator performs an input operation on the coordinate input panel 10 , the voltage detected by the resistive film 12 is transmitted first to the cpu 3 , and then the voltage detected by the resistive film 11 is transmitted to the cpu 3 . the cpu 3 detects the x - coordinate from the voltage from the resistive film 11 and the y - coordinate from the voltage from the resistive film 12 . the cpu 3 controls the detection of the coordinate value of an input point on the coordinate input panel 10 . according to the coordinate input panel 10 having the above - described structure , when a point on the input area 13 is pressed , the resistive films 11 and 12 contact each other at the point . when the voltage is applied to the electrodes 15 of the resistive film 12 , the voltage is divided at the contact point so that the voltage representing the y - coordinate is output . further , when the voltage is applied to the electrodes 14 of the resistive film 11 , the voltage is divided at the contact point so that the voltage representing the x - coordinate is output . the switch 5 switches between the absolute and relative coordinate value modes of the coordinate input panel 10 by a voltage supplied from the supply voltage terminal 29 . the cpu 3 detects a coordinate value according to either mode selected by the switching operation of the switch 5 . fig4 a and 4b are diagrams illustrating an embodiment of a coordinate detection according to the present invention . each of fig4 a and 4b shows a cross - section of a coordinate input panel according to the present invention in a state where the operator performs an input operation thereon . dotted areas shown in respective fig4 a and 4b are contact areas a and b each formed by contacting an input means , such as a pen or a finger of the operator , with the surface of the coordinate input panel when the input operation is performed . each of the contact areas a and b is a detection range of coordinates , which range varies depending on a type of the input means . fig4 a shows a case in which an input point is formed by means of a pen . the contact area a shows the detection range of the coordinate value of the input point . according to fig4 a , the surface of the coordinate input panel including resistive films 30 and 31 is pressed with the point of the pen so that a pressed portion of the resistive film 30 contacts the resistive film 31 . the contact portion is detected as coordinates . in this case , the contact area a is processed as a coordinate value . on the other hand , fig4 b shows a case in which an input point is formed by means of a finger of the operator . the contact area b shows the detection range of the coordinate value of the input point . in this case , as in the above - described case , a finger - pressed portion of the resistive film 30 contacts the resistive film 31 to form the contact area b . the contact area b is processed as a coordinate value . compared with the contact area a , the contact area b has a wider detection area of coordinates so as to cause larger variations in detected coordinate values . as an input means , a pen is more often employed to input a signature or to draw a picture , while a finger is more often employed to move a pointer . therefore , in the case of a smaller contact area , the operation mode of the coordinate detection device is set to comply with an input operation by means of a pen , and in the case of a larger contact area , the operation mode of the coordinate detection device is set to comply with an input operation by means of a finger . for example , the operation mode of the coordinate input device is set in the absolute coordinate value mode in the case of a smaller contact area , and in the relative coordinate value mode in the case of a larger contact area . thus , the operation mode of the coordinate detection device is determined based on a contact area formed by an input operation so as to comply with the input operation . therefore , the coordinate detection device , by switching the operation modes thereof , can be used as a device for inputting a signature or drawing a picture when the operator performs an input operation by means of a pen , and as a pointing device when the operator performs an input operation by means of an operator &# 39 ; s finger . fig5 is a flowchart of a process of a first - type mode determination based on a contact area formed by an input operation , in which area an input means such as a pen or a finger contacts the surface of a coordinate input panel according to the present invention . in step s 30 , a difference between the maximum and minimum values of the contact area is calculated . next , in step s 31 , it is determined whether the difference calculated in step s 30 is equal to or larger than a predetermined value c . if the result of step s 31 is “ yes ”, that is , if the difference is equal to or larger than the predetermined value c , the process goes to step s 32 , in which the operation mode of the coordinate detection device is set in a first mode . the first mode is an operation mode performing the conventional coordinate detection process which switches between the absolute and relative coordinate value modes . if the result of step s 31 is “ no ”, that is , if the difference is smaller than the predetermined value c , the process goes to step s 33 , in which the operation mode is set in either a second mode or the absolute coordinate value mode . the second mode is an operation mode in a coordinate detection process according to the present invention . as described above , the first - type mode determination determines and sets the operation mode appropriate for an input operation based on the contact area formed on the surface of the coordinate input panel by the input operation , using the predetermined value c as reference for the switching of the operation modes . by using the above - described first - type mode determination , the operation modes of the coordinate detection device can be switched in accordance with operations of the operator such as a signature input , a picture drawing , and a pointer operation . a description will now be given of a first embodiment of the coordinate detection process according to the present invention . fig6 is a flowchart of a coordinate detection process according to the first embodiment . according to fig6 , the above - described first - type mode determination is performed first to switch the operation mode of the coordinate detection device to a mode complying with an input operation . in step s 40 , it is determined whether an input operation has been performed on the coordinate input panel . if the result of step s 40 is “ no ”, that is , if the input operation has not been performed on the coordinate input panel , the process goes to step s 41 , in which the process of the first - type mode determination is performed . in step s 41 , one of the first mode and the second mode or the absolute coordinate value mode is set based on a difference between the maximum and minimum values of a contact area formed on the surface of the coordinate input panel by the input operation . after one of the above - described modes is set , in step s 42 , it is determined whether the set mode is the first mode . if the result of step s 42 is “ yes ”, that is , if the difference is equal to or larger than the predetermined value c , the next input operation is performed in the same operation mode as the conventional one . thereafter , in step s 43 , a previous coordinate value is cleared , and the process returns to step s 40 . if the result of step s 42 is “ no ”, that is , if the difference is smaller than the predetermined value c , the process returns to step s 40 . in steps s 41 through s 43 , the operation mode is determined based on the input operation . if the operation mode is determined to be the first mode , which is the same mode as employed in the conventional coordinate detection process , the previous coordinate value is cleared . if the operation mode is determined to be the second mode or the absolute coordinate value mode , the previous coordinate value is not cleared and is employed to detect the next coordinate value . if the result of step s 40 is “ yes ”, that is , if the input operation has been performed on the coordinate input panel , the process goes to step s 44 , in which the voltage of an input point on the surface of the coordinate input panel is detected . thereafter , steps s 45 and s 46 are performed . steps s 44 through s 46 are performed a predetermined number of times . in step s 45 , the maximum value of the voltage is detected to overwrite a stored maximum value , and in step s 46 , the minimum value of the voltage is detected to overwrite a stored minimum value . steps s 45 and s 46 are processes which are added when the process of the first - type mode determination is performed in the coordinate detection process . after the above - described steps , in step s 47 , it is determined whether steps s 44 through s 46 are performed the predetermined number of times . if the result of step s 47 is “ no ”, that is , if the voltage is not detected the predetermined number of times , steps s 44 through s 47 are repeated until the result of step s 47 becomes “ yes ”. by thus detecting the voltage of the input point on the surface of the coordinate input panel the predetermined number of times , a coordinate value of an input point formed by an improper input operation is prevented from being detected so that a correct coordinate value can be obtained . if the result of step s 47 is “ yes ”, that is , if the voltage is detected the predetermined number of times , the process goes to step s 48 , in which the average of the detected values of the voltage is calculated . in step s 49 , the calculated average is converted into a current coordinate value . in step s 50 , the process of the first - type mode determination is again performed based on the current coordinate value obtained in step s 49 . in step s 51 , it is determined whether the operation mode of the coordinate input panel is set in the first mode which performs the same coordinate detection process as the conventional one . if the result of step s 51 is “ yes ”, that is , if the operation mode is the first mode , in step s 55 , it is determined whether the previous coordinate value is stored . if the result of step s 55 is “ no ”, that is , the previous coordinate value is not stored , in step s 56 , the current coordinate value is stored as the previous coordinate value , and the process returns to step s 40 and the following steps are repeated . if the previous coordinate value is stored , in step s 57 , a difference between the previous and current coordinate values is calculated to be defined as a current relative coordinate value . the current coordinate value does not consider a distance between the input points of the previous and current coordinate values . after the current relative coordinate value is obtained in step s 57 , in step s 58 , the current coordinate value is converted into the previous coordinate value . in step s 59 , the current relative coordinate value is output . through above - described steps s 57 through s 59 , the relative coordinate value is calculated in the relative coordinate value mode and is output . if the result of step s 51 is “ no ”, that is , if the operation mode is not the first mode , in step s 52 , it is determined whether the operation mode is the absolute coordinate value mode . if the result of step s 52 is “ yes ”, that is , if the operation mode is the absolute value mode , the process goes to steps s 53 and s 54 . in step s 53 , the current coordinate value obtained in step s 49 is converted into a current absolute coordinate value . in step s 54 , the current absolute coordinate value obtained in step s 53 is output . thus , in steps s 53 and s 54 , the current absolute coordinate value is obtained in the absolute coordinate value mode and is output . if the result of step s 52 is “ no ”, that is , if the operation mode is not the absolute coordinate value mode , but is the second mode , the current absolute coordinate value is calculated without detecting the previous coordinate value . in the case of detecting the coordinate value in the second mode , steps s 57 through s 59 are performed without detecting the previous coordinate value in step s 55 . in step s 57 , a difference between the current coordinate value and the stored previous coordinate value is calculated to be defined as a current relative coordinate value . after the current relative coordinate value is obtained , in step s 58 , the current coordinate value is determined to be the previous coordinate value . in step s 59 , the current relative coordinate value is output . thus , a coordinate value can be detected in a mode appropriate for an input operation by employing the first - type mode determination and a previous coordinate value . fig7 is a flowchart of a process of a second - type mode determination based on an off - contact time . according to fig7 , the operation mode of the coordinate detection device is determined based on the off - contact time during which an input means such as a pen or a finger does not contact the surface of the coordinate input panel . for example , when a pen or a finger is detached from the surface of the coordinate input panel between previous and current input operations during a series of input operations , the off - contact time is often shorter in this case than is required to switch the operations of the coordinate detection device so that the coordinate detection device can be used , for example , as a pointing device . therefore , the off - contact time is compared with a predetermined time t 1 to determine an appropriate mode for the series of operations . in step s 34 , it is determined whether the off - contact time is equal to or shorter than the predetermined time t 1 . if the result of step s 34 is “ no ”, that is , the off - contact time is longer than the predetermined time t 1 , it is determined that the current input operation is performed as an operation of , for example , a pointing device , and the process goes to step s 35 , in which the first mode is set . if the result of step s 34 is “ yes ”, that is , the off - contact time is shorter than or equal to the predetermined time t 1 , the process goes to step s 36 , in which the second mode or the absolute coordinate value mode is set . thus , the second - type mode determination determines and sets the operation mode appropriate for an input operation based on the off - contact time during which an input means does not contact the surface of the coordinate input panel , using the predetermined time t 1 as reference for the switching of the operation modes . by using the above - described second - type mode determination , the operation modes of the coordinate detection device can be switched in accordance with operations of the operator such as a signature input , a picture drawing , and a pointer operation . a description will now be given of a second embodiment of the coordinate detection process according to the present invention . fig8 is a flowchart of a coordinate detection process according to the second embodiment . the coordinate detection process according to the second embodiment employs the process of the second - type mode determination shown in fig7 , which process switches the operation modes of the coordinate detection device in accordance with an input operation . in fig8 , the same steps as those in fig6 are referred to by the same numerals , and a description thereof will be omitted . if it is determined in step s 40 that an input operation has not been performed on the coordinate input panel , in step s 60 , the process of the second - type mode determination is performed to determine whether the operation mode is the first mode , or the second mode or the absolute value mode based on the off - contact time . thereafter , in step s 42 , it is determined whether the operation mode is the first mode . if the result of step s 42 is “ yes ”, that is , if the off - contact time is longer than the predetermined time t 1 , the next input operation is performed in the same operation mode as the conventional one . then , in step s 43 , a previous coordinate value is cleared , and the process returns to step s 40 . if the result of step s 42 is “ no ”, that is , the off - contact time is equal to or shorter than the predetermined time t 1 , the process goes to step s 62 . in step s 62 , the off - contact time , namely , the duration of an off - contact state where a pen or a finger is detached from the surface of the coordinate input panel , is measured . step s 62 is a process which is added when the second - type mode determination is performed in the coordinate detection process . if it is determined in step s 40 that the input operation has been performed on the coordinate input panel , steps s 44 and s 47 are repeated until the voltage of the input point is detected the predetermined number of times . thereby , a coordinate value of an input point formed by an improper input operation is prevented from being detected so that a correct coordinate value can be obtained . in step s 48 , the average of the detected values of the voltage is calculated . in step s 49 , the calculated average is converted into a current coordinate value . in step s 63 , the process of the second - type mode determination is again performed based on the current coordinate value obtained in step s 49 . in step s 63 , the operation mode is switched to one of the above - described modes so as to comply with the input operation . then , in step s 51 , it is determined whether the operation mode is set in the first mode which performs the same coordinate detection process as the conventional one . if the operation mode is the first mode , in step s 55 , it is determined whether the previous coordinate value is stored . if the previous coordinate value is not stored , in step s 56 , the current coordinate value is stored as the previous coordinate value , and the process returns to step s 40 and the following steps are repeated . if the previous coordinate value is stored , in step s 57 , a difference between the previous and current coordinate values is calculated to be defined as a current relative coordinate value . the current coordinate value does not consider a distance between the input points of the previous and current coordinate values . after the current relative coordinate value is obtained in step s 57 , in step s 58 , the current coordinate value is converted into the previous coordinate value . in step s 59 , the current relative coordinate value is output . through the above - described steps s 57 through s 59 , the relative coordinate value is calculated in the relative coordinate value mode and is output . if the result of step s 51 is “ no ”, that is , if the operation mode is not the first mode , in step s 52 , it is determined whether the operation mode is the absolute coordinate value mode . if the operation mode is the absolute value mode , the process goes to steps s 53 and s 54 . in step s 53 , the current coordinate value obtained in step s 49 is converted into a current absolute coordinate value . in step s 54 , the current absolute coordinate value obtained in step s 53 is output . thus , in steps s 53 and s 54 , the current absolute coordinate value is obtained in the absolute coordinate value mode and is output . if the result of step s 52 is “ no ”, that is , if the operation mode is not the absolute coordinate value mode , but is the second mode , the coordinate detection process is performed in the relative coordinate value mode . in the case of detecting the coordinate value in the second mode , steps s 57 through s 59 are performed without detecting and storing the previous coordinate value in step s 55 . in step s 57 , a difference between the current coordinate value and the stored previous coordinate value is calculated to be defined as a current relative coordinate value . after the current relative coordinate value is obtained , in step s 58 , the current coordinate value is determined to be a previous coordinate value . in step s 59 , the current relative coordinate value is output . thus , a coordinate value can be detected in a mode appropriate for an input operation by employing the second - type mode determination and a previous coordinate value . fig9 a and 9b are diagrams illustrating an input operation on the coordinate input panel according to the present invention . suppose that the operator inputs a japanese hiragana letter to the coordinate input panel , using an operator &# 39 ; s finger or a pen . fig9 a shows the letter input by the operator , and fig9 b is an enlarged view of a circled portion d of the letter shown in fig9 a . a description will be given with reference to the circled portion d . the coordinate values of the circled portion d of the letter are detected in the coordinate detection process according to the present invention . the coordinate values of a press end point e , at which a pen or a finger is detached from the surface of the coordinate input panel after continuously pressing the surface , and a press start point f , at which the pen or the finger starts pressing the surface , are obtained by considering an imaginary distance g therebetween by the coordinate detection process according to the present invention . fig1 a and 10b are diagrams illustrating a movement of a cursor according to the present invention . the input points formed on the surface of the coordinate input panel by the input operation as shown in fig9 a are detected according to the coordinate detection process of the present invention , and are output as shown in fig1 a . fig1 a shows the coordinate values of the input points in an output state . respective dotted arrows show routes along and directions in which the cursor moves . fig1 b is an enlarged view of a circled portion e of the letter , which portion includes one of the movements of the cursor . a description will be given with reference to the circled portion e . the coordinate values of the circled portion e of the letter are detected and output in the coordinate detection process according to the present invention . the points e and f shown in fig9 b are output as previous and current coordinate values h and i , respectively , in fig1 b . a cursor movement j is made by an imaginary operation performed by the coordinate detection process according to the present invention . as described above , by switching the operation mode to the second mode in the coordinate detection process , the same coordinate values as those of the input points are detected and output . fig1 is a diagram illustrating an input operation according to the present invention . fig1 shows a series of operations ( strokes ) to input a japanese hiragana letter to the coordinate input panel . the operator inputs a series of operations ( strokes ) ( a ) through ( e ) in this order in directions indicated by respective arrows in fig1 on the surface of the coordinate input panel . the operations ( a ) and ( e ) are the movements of the cursor . the cursor is moved to the initial input point of the stroke ( b ) by the operation ( a ). the operation ( e ) is the movement of the cursor after the letter is input to the coordinate input panel by the strokes ( b ) through ( d ). during the operations ( strokes ) ( a ) through ( e ), a pen or a finger is detached from the surface of the coordinate input panel between one operation and the following operation . although the input operation according to the present invention is described by taking the japanese hiragana letter as an example in fig9 a through 11 , the present invention can also be applied to the input operation of an english letter . fig1 is a timing chart of the switching of the operation modes based on the input operation shown in fig1 . during the operation ( a ), the pen or the finger contacts the surface of the coordinate input panel in the first mode , which performs the same switching operation as the conventional operation mode . during the switching from the operation ( a ) to the stroke ( b ), the coordinate input panel is switched “ off ”, or is in an “ off ” state . if the “ off ” state time or the off - contact time of the coordinate input panel is equal to or shorter than the predetermined time t 1 , the operation mode is switched to the second mode , which is the operation mode of the present invention . similarly , if the off - contact time during the switching from the stroke ( b ) to the stroke ( c ) is equal to or shorter than the predetermined time t 1 , the operation mode is switched to the second mode . likewise , if the off - contact time during the switching from the stroke ( c ) to the stroke ( d ) is equal to or shorter than the predetermined time t 1 , the operation mode is switched to the second mode . the off - contact time during the switching from the stroke ( d ) to the operation ( e ) is longer than the predetermined time t 1 . therefore , the operation mode is switched to the first mode . by thus switching between the first and second modes based on the comparison between the off - contact time and the predetermined time t 1 , the operation modes of the coordinate detection device can be switched freely in accordance with the operations of the operator . further , by automatically switching the switch of the coordinate input panel for switching between the operation modes “ off ” and “ on ” to switch the operation mode between the first and second modes , respectively , the cursor can be moved to the initial input point of an operation for inputting a signature or drawing a picture so that the signature can be input or the picture can be drawn from the initial input point . the present invention is not limited to the specifically disclosed embodiments , and variations and modifications may be made without departing from the scope of the present invention . the present application is based on japanese priority application no . 2000 - 040117 filed on feb . 17 , 2000 , the entire contents of which are hereby incorporated by reference .