Abstract:
A touch screen unit including a touch-sensitive panel outputting voltage signals concerning a position of a contact made thereon and a control unit generating coordinate information and operation information of the contact based on said voltage signals is provided. The operation information corresponds to operations of two or more switches.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to a coordinate input device for detecting a set of coordinates of a position of a contact on a position-sensitive surface. The present invention particularly relates to a coordinate input device which can simulate various mouse button operations. 
     A touch screen or a touch panel is a type of coordinate input devices that can be used as a position detecting device of a personal computer. In operating the personal computer, the user may simply touch objects, such as icons, displayed on a display. The touch screen may be of any type described below. One type of touch screen may include an upper conductive layer and a lower resistive layer overlaid on the upper conductive layer with a gap between the layers. Other types of the touch screen may include an upper resistive layer provided with a pair of parallel electrodes and a lower resistive layer provided with a pair of parallel electrodes arranged perpendicular to the pair of electrodes on the upper resistive layer. The upper and lower layers come into contact when there is a touch on the touch screen. The touch screen outputs coordinate information of the position of a touch, and basically operates as a single switch. 
     2. Description of the Related Art 
     It is known to place a coordinate input device such as a touch screen over a display face in order to specify a position on the display face. 
     The touch screen determines whether the upper and lower layers are in contact and then obtains the coordinate of the position of contact based on an electric potential distribution. Thus, the touch screen realizes operations such as positioning a cursor to a specified position displayed on the display. The touch screen of the related art can only determine whether or not the upper and lower layers are in contact. That is to say, only an ON/OFF representation is possible with the touch screen of the related art. Thus, the touch screen of the related art only serves as one switch. 
     When the touch screen is used with an OS (Operating System), such as Windows, based on a GUI (Graphical User Interface), a touch can only represent either a right button or a left button of a mouse. 
     Various techniques have been developed in order achieve a plurality of functions with the touch screen. For instance, with Windows CE, a touch on the touch screen panel corresponds to a left button operation of the mouse, and a touch on the touch screen simultaneous with an operation of a predetermined key of the keyboard corresponds to a right button operation of the mouse. 
     With a Windows system, when an icon displayed in a task tray is touched and the same icon is touched again directly after the first touch, it is identified as an operation of the right button. Thus, a plurality of functions can be represented. 
     Also, for a touch screen used with a dedicated retractable pen, retracting the tip of the pen represents the left button operation and pressing a button provided on the pen represents the right button operation. 
     However, with the coordinate input device of the related art, a touch on the touch screen is not sufficient for achieving the coordinate input operation and two button operations. Therefore, with the coordinate input device of the related art, it is necessary to use a further input device having two buttons to achieve two button operations. 
     Thus, in order to achieve the two button operation by the touch screen, it is necessary to use further input devices such as a dedicated pen or a keyboard. This results in an increased cost of a computer, when mounted on the computer such the notebook-type personal computer. 
     Further, it is known to configure a touch screen such that a touch on the touch screen corresponds to the left button operation. Then, such left button operation will be executed even in cases where it is simply required to designate a coordinate of a certain position. This then becomes an awkward function. 
     It is also possible to provide a predetermined region on the touch screen such that this region corresponds to the right button. With this structure, the right button operation is realized by touching the predetermined region on the touch screen. However, this results in complicated operations. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is a general object of the present invention to provide a coordinate input device which can avoid complicated operations. 
     It is another and more specific object of the present invention to provide a system which can generate information corresponding to operations of various switches of a mouse. 
     In order to achieve the above objects according to the present invention, there is provided a touch screen unit comprising: 
     a touch-sensitive panel outputting voltage signals concerning a position of a contact made thereon; and 
     a control unit generating coordinate information and operation information of the contact based on said voltage signals, 
     wherein said operation information corresponds to operations of two or more switches. 
     With the system described above, a coordinate input device such as a touch screen can implement various operations which may correspond to right and left button operations of a mouse. 
     The present invention also provides a method of generating information corresponding to operations of two or more switches based on a state of contact on the position-sensitive surface. Further, the present invention provides a machine readable medium storing program code means for implementing such a method. 
     Other objects and further features of the present invention will be apparent from the following detailed description when read in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic diagram showing system configuration incorporating a coordinate input device of a first embodiment of the present invention. 
     FIG. 2 is a block diagram showing a touch screen unit of the coordinate input device of the first embodiment of the present invention. 
     FIG. 3 is a block diagram showing a computer main body used with a coordinate input device of the first embodiment of the present invention. 
     FIG. 4 is a timing chart showing an operation of the touch screen unit of the present invention. 
     FIG. 5 is a flowchart showing an operation of the MCU of the touch screen unit shown in FIG.  2 . 
     FIG. 6 is a detailed flowchart of a touch detection step shown in FIG.  5 . 
     FIG. 7 is a detailed flowchart of a release detection step shown in FIG.  5 . 
     FIG. 8 is a schematic diagram showing a drag operation of the first embodiment of the present invention. 
     FIG. 9 is a schematic diagram showing a left button single click operation of the first embodiment of the present invention. 
     FIG. 10 is a schematic diagram showing a right button single click operation of the first embodiment of the present invention. 
     FIG. 11 is a schematic diagram showing a double click operation of the first embodiment of the present invention. 
     FIG. 12 is a schematic diagram showing operations of a first variant of the first embodiment of the present invention. 
     FIG. 13 is a schematic diagram showing an operation of a second variant of the first embodiment of the present invention. 
     FIG. 14 is a detailed flowchart of a touch detection step of a third variant of the first embodiment of the present invention. 
     FIG. 15 is a detailed flowchart of a release detection step of a third variant of the first embodiment of the present invention. 
     FIG. 16 is a schematic diagram showing a left touch output of the third variant of the first embodiment of the present invention. 
     FIG. 17 is a schematic diagram showing a right touch output of the third variant of the first embodiment of the present invention. 
     FIG. 18 is a block diagram showing a computer main body used with a coordinate input device of a second embodiment of the present invention. 
     FIG. 19 is a flowchart showing an operation of the device driver of the second embodiment of the present invention upon occurrence of a hardware interrupt. 
     FIG. 20 is a flowchart showing an OFF generation process of FIG.  19 . 
     FIG. 21 is a flowchart showing an ON continuation process of FIG.  19 . 
     FIG. 22 is a flowchart showing an ON generation process of FIG.  19 . 
     FIG. 23 is a flowchart showing an OFF continuation process of FIG.  19 . 
     FIG. 24 is a flowchart showing a timer interrupt process of the second embodiment of the present invention. 
     FIG. 25 is a flowchart showing a T 1  interrupt process of FIG.  24 . 
     FIG. 26 is a flowchart showing a T 2  interrupt process of FIG.  24 . 
     FIG. 27 is a flowchart showing a T 3  interrupt process of FIG.  24 . 
     FIG. 28 is a flowchart showing a T 4  interrupt process of FIG.  24 . 
     FIG. 29 is a flowchart showing a switch ON output process. 
     FIG. 30 is a flowchart showing a first switch ON output process. 
     FIG. 31 is a flowchart showing a second switch ON output process. 
     FIG. 32 is a flowchart showing a single-click or double-click generation process. 
     FIG. 33 is a schematic diagram showing a left button click operation of the second embodiment of the present invention. 
     FIG. 34 is a schematic diagram showing a right button click operation of the second embodiment of the present invention. 
     FIG. 35 is a schematic diagram showing a drag operation of the second embodiment of the present invention. 
     FIG. 36 is a diagram illustrating various operations which may be carried out by the second embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the following, principles and embodiments of the present invention will be described with reference to the accompanying drawings. 
     FIG. 1 is a schematic diagram showing a system configuration including a coordinate input device of a first embodiment of the present invention. A computer system  1  of the present invention includes a computer main body  2 , a display unit  3 , a coordinate input device or a touch screen unit  4  of the present invention and a keyboard  5 . 
     The display unit  3  and the touch screen unit  4  are connected to the computer main body  2 . The display unit  3  may be an LCD (Liquid Crystal Display) which outputs or displays data supplied from the computer main body  2 . 
     It is to be noted that any type of touch screen unit  4  may be used in the present invention. One type of the touch screen may include an upper conductive layer and a lower resistive layer of a film overlaid on the upper conductive layer with a gap between the layers. Other types of the touch screen may include an upper resistive layer provided with a pair of parallel electrodes and a lower resistive layer provided with a pair of parallel electrode arranged perpendicular to the pair of electrodes of the upper resistive layer. 
     The touch screen unit  4  outputs coordinate information when the upper and lower layers are brought into contact. The touch screen unit  4  is placed over a display face of the display unit  3  and is connected to the computer main body  2  so as to output coordinate information corresponding to a position on the display face of the display unit  3 . 
     The computer main body  2  moves a cursor displayed on the display  3  to a position corresponding to the coordinate information supplied from the touch screen unit  4 . In the present invention, the touch screen unit  4  also outputs information equivalent to a right button and a left button of a mouse. As will be described later, the button information is obtained based on a temporal characteristic (timing) and a positional characteristic (vector) of a contact on the touch screen unit  4 . 
     FIG. 2 shows a block diagram of the touch screen  4  of the first embodiment of the present invention. The touch screen unit  4  includes a touch screen  11 , a driving circuit  12 , an MCU (Microprogram Control Unit)  13  and an external interface  14 . 
     The touch screen  11  is connected to the driving circuit  12  and is driven by voltages (not shown) supplied from the driving circuit  12 . The touch screen  11  detects an X-coordinate detection voltage Vx and a Y-coordinate detection voltage Vy based on the position of contact. Then, the X-coordinate detection voltage Vx and the Y-coordinate detection voltage Vy are supplied to the driving circuit  12 . The driving circuit  12  passes the X-coordinate detection voltage Vx and a Y-coordinate detection voltage Vy to the MCU  13 . 
     The MCU  13  derives the coordinate information of the position of contact based on the X-coordinate detection voltage Vx and a Y-coordinate detection voltage Vy. Also, the MCU  13  outputs right button manipulation information and left button manipulation information according to temporal and positional characteristics of an occurrence of the coordinate information. The MCU  13  is connected to the external interface  14 . The external interface  14  supplies the coordinate information and the right and left button manipulation information, all of which being generated at the MCU  13 , to the computer main body  2 . 
     FIG. 3 is a block diagram showing the computer main body  2  used in combination with a coordinate input device or the touch screen unit  4  of a first embodiment of the present invention. The computer main body  2  includes a personal computer (PC) hardware part  21 , an operating system (OS)  22 , a device driver  23  and an application software  24 . 
     The PC hardware part  21  receives the coordinate information and the right and left button manipulation information supplied from the external interface  14  of the touch screen unit  4 . Then, the coordinate information and the right and left button manipulation information are transferred to the OS  22 , to the device driver  23  and finally to the application software  24 . 
     The application software  24  executes various processes according to the coordinate information and the right and left button manipulation information received from the device driver  23 . 
     Referring now to FIG. 4, an example of settings of a timing of the coordinate input device of the present invention will be described. FIG. 4 illustrates phases T 0  through T 4 . The touch screen unit  4  may have an ON state and an OFF state. Time variables t 0  to t 4  represents various timings when there is a change of voltage at the touch screen unit  4 . 
     Phase T 0  is determined as follows. Time t 0  is defined as an initial time required for determination of phase T 0 . When the voltage of the touch screen unit  4  is changed from ON state to OFF state, current time is stored in time t 0 . When a predetermined time period t 0low  has elapsed from time t 0 , the process enters phase T 0 . When a predetermined time period t 0high  has elapsed from time t 0 , the process leaves phase T 0 . In other words, maximum range of phase T 0  may be expressed as t 0high -t 0low . Then, when the voltage level at the touch screen unit  4  changes from OFF state to ON state, current time is stored in time t 1 , and the process leaves phase T 0 . Time t 1  is defined as an initial time required for determination of phase T 1 . If there is no change of voltage during maximum range t 0high -t 0low , current time is again stored in time t 0 . 
     Phase T 1  is determined as follows. When a predetermined time period t 1low  has elapsed from time t 1 , the process enters phase T 1 . When a predetermined time period t 1high  has elapsed from time t 1 , the process leaves phase T 1 . In other words, maximum range of phase T 1  may be expressed as t 1high -t 1low . Then, when the voltage level at the touch screen unit  4  changes from ON state to OFF state, current time is stored in time t 2 , and the process leaves phase T 1 . Time t 2  is defined as an initial time required for determination of phase T 2 . If there is no change of voltage during maximum range t 1high -t 1low , current time is again stored in time t 0 . 
     Phase T 2  is determined as follows. When a predetermined time period t 2low  has elapsed from time t 2 , the process enters phase T 2 . When a predetermined time period t 2high  has elapsed from time t 2 , the process leaves phase T 2 . In other words, maximum range of phase T 2  may be expressed as t 2high -t 2low . Then, when the voltage level at the touch screen unit  4  changes from OFF state to ON state, current time is stored in time t 3 , and the process leaves phase T 2 . Time t 3  is defined as an initial time required for determination of phase T 3 . If there is no change of voltage during maximum range t 2high -t 2low , current time is again stored in time t 0 . 
     Phase T 3  is determined as follows. When a predetermined time period t 3low  has elapsed from time t 3 , the process enters phase T 3 . When a predetermined time period t 3high  has elapsed from time t 3 , the process leaves phase T 3 . In other words, maximum range of phase T 3  may be expressed as t 3high -t 3low . Then, when the voltage level at the touch screen unit  4  changes from ON state to OFF state, current time is stored in time t 4 , and the process leaves phase T 3 . Time t 4  is defined as an initial time required for determination of phase T 4 . If there is no change of voltage during maximum range t 3high -t 3low , current time is again stored in time t 0 . 
     Phase T 4  is determined as follows. When a predetermined time period t 4low  has elapsed from time t 4 , the process enters phase T 4 . When a predetermined time period t 4high  has elapsed from time t 4 , the process leaves phase T 4 . In other words, maximum range of phase T 4  may be expressed as t 4high -t 4low . Then, the operation at the touch screen unit  4  is determined as a double-click. If the voltage level at the touch screen unit  4  does not change during phase T 3 , the operation is regarded as another operation such as a drag. 
     Operations such as click, double-click and button swap may be determined by means of the timing chart as described above. Operations corresponding to different switches may be determined by positional characteristics. 
     In the following, an operation of the MCU  13  of the touch screen unit  4  will be described with reference to FIG. 5, which is a flowchart showing an operation of the MCU  13  of the touch screen unit  4  shown in FIG.  2 . 
     The MCU  13  monitors a touch on the touch screen  11 . Here, the term “touch” is to be understood as a state where the upper and lower layers of the touch screen come into contact and are kept in contact for over a predetermined period of time (e.g. T 1  or T 3  in FIG.  4 ). If a touch is detected at the touch screen  11  (step S 1 ), then the coordinate of the position of the touch is checked (step S 2 ). 
     After steps S 1  and S 2 , a release on the touch screen  11  is monitored (step S 3 ). Here, the term “release” is understood to mean a state in which the upper and lower layers of the touch screen come to a non-contact state after an occurrence of the touch and are kept in a non-contact state for a predetermined period of time (e.g. T 0 , T 2  or T 4  in FIG.  4 ). If the release is detected at step S 3 , the output data is verified (step  4 ). Then, based on a result of the verification at step S 4 , it is determined whether or not there is an output data (step S 5 ). 
     If it is determined, at step S 5 , that there is an output data, the output data is output to the computer main body  2  (step S 6 ). The process returns to step S 1 . If it is determined, at step S 5 , that there is no output data, the process directly returns to step S 1 . 
     The coordinate information and the right and left button manipulation information are supplied to the computer main body  2  by repeating the above-described steps S 1  through S 6 . 
     In the following, the touch detection step of step S 1  will be described in detail. 
     FIG. 6 is a detailed flowchart of a touch detection step shown in FIG.  5 . Variables used in FIG. 6 are listed below. 
     T fn  represents time of transition from an OFF state to an ON state. This corresponds to t 1  or t 3  in FIG.  4 . 
     P fn  represents an initial coordinate of a contact point at time T fn . 
     V represents the size of a vector having the point P fn  as a starting point and the currently detected point as an end point. 
     T nn  represents duration of the ON state. This corresponds to T 1  or T 3  in FIG.  4 . 
     T on  represents a minimum time period from time T fn  that is required for the ON state to be regarded as a contact state. When time period T nn  is smaller than time period T on , the operation is not regarded as in a contact state. T on  corresponds to t 1low  or t 3low  in FIG.  4 . 
     r 1  represents a predetermined boundary value of V. When V is greater than or equal to r 1 , the contact state is regarded as a “touch”. In the following figures, a reference symbol A represents an area having r 1  as a radius. 
     T touch  is a predetermined boundary value of the time period T nn . T touch  is chosen to be greater than T on . When T nn  is greater than or equal to T touch , the contact is regarded as a “touch”. This corresponds to t 1high  or t 3high  in FIG.  4 . 
     C flag  represents a contact status information stored in the MCU  13 . When C flag =1, there has been a “touch” on the touch screen  11 . When C flag =0, there has been a “release” on the touch screen  11 , or the detected contact is a new contact. 
     E flag  represents an extended stage status information stored in the MCU  13 . When E flag =1, the process is in an extended stage. When E flag =0, the process is not in the extended stage. 
     In the touch detection step of step S 1 , first, it is determined whether or not the touch screen  11  is in an ON state (step S 1 - 1 ). If the touch screen is in an OFF state, the contact status information C flag  is set to a value “0” (step S 1 - 2 ). If the touch screen  11  is in an ON state, the coordinate of the position where the upper and lower layer of the touch screen are in contact is detected from the X-coordinate detection voltage Vx and the Y-coordinate detection voltage Vy (step S 1 - 3 ). 
     Then, the contact status information is checked to see whether a release data has been outputted or it is a new contact (step S 1 - 4 ). If the result of step S 1 - 4  is positive, current time is stored in T fn  (step S 1 - 5 ). After setting the detected coordinate as an initial coordinate P fn  (step S 1 - 6 ), the contact status information C flag  is set to a value “0” (step S 1 - 2 ). 
     If the result of step S 1 - 4  is negative, a vector operation is carried out so as to obtain the size of a vector from the initial coordinate P fn  to the detected coordinate (step S 1 - 7 ). 
     Further, a time difference between the current time T fn  previously stored in the MCU  13  at step S 1 - 5  and the current time obtained from the present detection is obtained (step S 1 - 8 ). Thus, the time period T nn  (=|T fn −(current time)|) between the previous contact and the currently detected contact is obtained. 
     Then, it is determined whether or not the time period T nn  between the previous contact and the currently detected contact is greater than or equal to a predetermined time period T on  (step S 1 - 9 ). If the result of step S 1 - 9  is negative, it is determined as a false operation and the contact status information C flag  is set to a value “0” (step S 1 - 2 ). 
     If the result of step S 1 - 9  is positive, the process proceeds to step S 1 - 10 . At step S 1 - 10 , it is determined whether the size V of the vector between the previous contact and the currently detected contact is greater than or equal to the predetermined value r 1 . 
     If the size V of the vector is greater than or equal to the predetermined value r 1 , it is determined that the process is not in the extended stage. At step S 1 - 11 , an operational mode is initialized and a touch signal is produced. Then at step S 1 - 12 , the contact status information C flag  is set to a value “1”. 
     Also, if the size V of the vector is less than the predetermined value r 1 , the process proceeds to step S 1 - 13 . Then, it is determined whether or not the time period T nn  between the previous touch and the currently detected touch is smaller than a predetermined time period T touch  (step S 1 - 13 ). 
     If the time period T nn  between the previous touch and the currently detected touch is greater than the time period T touch , it is determined that the currently detected contact does not fall into an extended operation. At step S 1 - 14 , an operational mode is initialized. After initialization of the operational mode at step S 1 - 14 , the contact status information C flag  is set to a value “1” at step S 1 - 12 . 
     If, at step S 1 - 13 , it is determined that the time period T nn  between the previous touch and the currently detected touch is less than the time period T touch , the process proceeds to step S 1 - 15 . Then, it is determined whether or not the process is in an extended stage (step S 1 - 15 ). The extended stage is set in the release detection process described later with reference to FIG.  7 . 
     If, at step S 1 - 15 , it is determined that the operation is in the extended stage, the operational mode is set to a double-click mode and the initial coordinate is stored in the MCU  13  (step S 1 - 16 ). If, at step S 1 - 15 , it is determined that the operation is not in the extended stage, the operational mode is set to a click mode and the initial coordinate is stored in the MCU  13  (step S 1 - 17 ). After the operational mode and the coordinate have been stored in the MCU  13  at steps S 1 - 16  and S 1 - 17 , the contact status information C flag  is set to a value “1” at step S 1 - 12 . Then, the process returns to the main process. 
     Referring again to FIG. 5, the coordinate stored in the MCU  13  in the touch detection process of step S 1  is checked at step S 2 . Then, the release detection process of step S 3  is carried out. 
     In the following, the release detection process of step S 3  will be described. 
     FIG. 7 is a detailed flowchart of a release detection step shown in FIG.  5 . Variables used in FIG. 7 are listed below. 
     T nf  represents time of transition from an ON state to an OFF state. This corresponds to t 0 , t 2  or t 4  in FIG.  4 . 
     T ff  represents duration of the OFF state. This corresponds to T 0 , T 2  or T 4  in FIG.  4 . 
     T off  represents a minimum time period from time T nf  that is required for the OFF state to be regarded as a non contact state. When time period T ff  is smaller than time period T off , the OFF state is not regarded as a non-contact state and remains in a contact state. This corresponds to t 0low , t 2low  or t 4low  in FIG.  4 . 
     T release  is a predetermined boundary value of the time period T ff . When T ff  is greater than or equal to T release , the OFF state is regarded as a “release”. This corresponds to t 0high , t 2high  or t 4high  in FIG.  4 . 
     In the release detection step of step S 3 , first, it is determined whether or not the touch screen  11  is in an ON state (step S 3 - 1 ). The positive result of step S 3 - 1  implies that the upper and lower layers have been brought into contact and have not become an OFF state. Then, the process returns to the main process. 
     If, at step S 3 - 1 , it is determined that the touch screen  11  is in an OFF state, the process proceeds to step S 3 - 2 . At step S 3 - 2 , it is determined if a “touch” has been previously detected. If the result of step S 3 - 2  is negative, it is determined that there is no “touch” or “release”, and the process returns to the main process. If the result of step S 3 - 2  is positive, the process proceeds to step S 3 - 3 . At step S 3 - 3 , it is determined if T nf  has been measured previously. 
     If, at step S 3 - 3 , it is determined that T nf  has not been measured previously, current time is set as T nf (step S 3 - 4 ). Then, an information indicating that there is a “touch” is stored in the MCU  13  at step S 3 - 19 . If, at step S 3 - 3 , it is determined that T nf  has been measured previously, a time period between the previous T nf  and current time is measured. In other words, the duration of the OFF state T ff  (=|T nf −current time) is obtained (step S 3 - 5 ). 
     At step S 3 - 6 , it is determined whether T ff  is greater than or equal to the predetermined time period T off . If the result of step S 3 - 6  is negative, the OFF state is regarded as a false operation and the contact status information C flag  is set to a value “1” at step S 3 - 19 . 
     If the result of step S 3 - 6  is positive, it is determined that the touch screen  11  is in a non-contact state. Then, at step S 3 - 7 , it is determined whether the operational mode stored in the MCU  13  has been initialized. 
     If the result of step S 3 - 7  is positive, it is determined whether T ff  is greater than or equal to T release  (step S 3 - 8 ). If the result of step S 3 - 7  is negative, it is not regarded as a “release” and the contact status information C flag  is set to a value “1” at step S 3 - 19 . 
     If the result of step S 3 - 7  is positive, a release signal is produced in step S 3 - 9 . Then, parameters such as current time are initialized at step S 3 - 10 . Then, the contact status information C flag  is set to a value “0” at step S 3 - 11 . Then the process returns to the main process. 
     If the result of step S 3 - 7  is negative, the process proceeds to step S 3 - 12  and determines whether or not T ff  is greater than or equal to T click . If the result of step S 3 - 12  is positive, the process proceeds to step S 3 - 13  and determines whether the operational mode is set as a double-click mode. If the result of step S 3 - 13  is negative, it is identified as a left button single click operation and a left button single click signal is produced (step S 3 - 14 ). Then the process proceeds to steps S 1 - 10  and S 1 - 11  described above. 
     If the result of step S 3 - 13  is positive, the process proceeds to step S 3 - 15  to determine whether or not the size V of the vector is greater than r 1  and less than r 2  (see FIG.  11 ). If the result of step S 3 - 13  is positive, it is identified as a right button single click operation and a right button single click signal is produced (step S 3 - 16 ). Then the process proceeds to steps S 1 - 10  and S 1 - 11  described above. 
     If the result of step S 3 - 13  is negative (and V is not greater than r 2 ), it is identified as a left button double click operation and a left button double click signal is produced (step S 3 - 17 ). Then the process proceeds to steps S 1 - 10  and S 1 - 11  described above. 
     If, at step S 3 - 12 , it is determined that T ff  is less than T click , the extended stage status information E flag  is set to a value “1” at step S 3 - 18 . Then the process proceeds to steps S 1 - 10  and S 1 - 11  described above. 
     From the touch detection step S 1  and the release detection step S 3 , a plurality of output operations, such as drag, left button single click, right button single click and double click can be stored in the MCU  13 . 
     Referring now to FIGS. 8 through 11, the plurality of output operations will be described in detail. 
     FIG. 8 is a schematic diagram showing a drag operation of the first embodiment of the present invention. A drag signal is produced in the touch detection process of step S 1 . The drag operation is achieved when a pen  31  contacts the touch panel  11  for a time period greater than T on  and moves through a distance greater than r 1 , and also when the pen  31  contacts for a time period greater than T touch . 
     FIG. 9 is a schematic diagram showing a left button single click operation of the first embodiment of the present invention. A left button single click operation signal is produced in the release detection process of step S 3 . The left button single click operation is achieved when a pen  31  contacts the touch panel  11  for a time period greater than T on , is lifted from the touch panel  11  within the time period T touch  and is kept in a non-contact state for a time period greater than T ff . 
     FIG. 10 is a schematic diagram showing a double click operation of the first embodiment of the present invention. A double click operation signal is produced in the release detection process of step S 3 . The double click operation is achieved when a second touch is detected at a position less than r 1  from the position of the first touch. 
     FIG. 11 is a schematic diagram showing a right button single click operation of the first embodiment of the present invention. A right button single click operation signal is produced in the release detection process of step S 3 . The right button single click operation is achieved when a second touch is detected at a position greater than r 1  and less than r 2  from the position of the first touch. It is to be noted that the determination of the right button single click operation is not limited to the manner described in the present embodiment. 
     FIG. 12 is a schematic diagram showing operations of a first variant of the first embodiment of the present invention. As shown in the figure, areas A 1  and A 2  are divided into sectors having angles θ  1 , θ  2 , θ  3  and θ  4 . In FIG. 12, point P 1  in area A 1  corresponds to the first touch of the pen  31  on the touch screen  11 . Points P 21  through P 24  are located in area A 2  and outside area A 1 . If the second touch is at point P 21 , the operation is regarded as a right button single click operation. If the second touch is at point P 22 , the operation is regarded as a first operation. If the second touch is at point P 23 , the operation is regarded as a second operation. If the second touch is at point P 24 , the operation is regarded as a third operation. 
     Further, an area A 3  having a radius r 3  may be provided so as to achieve an increased number of operations. FIG. 12 shows points P 31  through P 34  located in area A 3  and outside area A 2 . 
     Also, in order to identify a right button single click operation, it is sufficient to recognize an operation different from the double click operation. Therefore, for example, an operation including a first touch followed by a release and a second touch kept in contact over a predetermined time period may be regarded as a right button single click operation. 
     FIG. 13 is a schematic diagram showing an operation of a second variant of the first embodiment of the present invention. Point P 1  in area A corresponds to the first touch of the pen  31  on the touch screen  11 . Then, a second touch is made at point P 2  within area A and kept in contact over a predetermined time period. This operation is regarded as a right button single click operation. 
     FIG. 14 is a detailed flowchart of a touch detection step of a third variant of the first embodiment of the present invention. FIG. 15 is a detailed flowchart of a release detection step of a third variant of the first embodiment of the present invention. In FIGS. 14 and 15, steps similar to those of FIGS. 6 and 7 are indicated with similar reference numerals and will not be described in detail. 
     In the present embodiment, a touch signal produced at step S 1 - 11  of FIG. 6 is replaced by a left touch signal produced at step S 1 - 21  and a touch signal produced at step S 1 - 14  of FIG. 6 is replaced by a right touch signal produced at step S 1 - 22 . Also, a click mode at step S 1 - 17  of FIG. 6 is replaced by a left click mode at step S 1 - 23 . When the operational mode is set as a left click mode, when the result of S 3 - 15  shown in FIG. 14 is negative, it is determined as a left button double click and a left button double click signal is produced (step S- 22 ). 
     FIG. 16 is a schematic diagram showing a left touch output of the third variant of the first embodiment of the present invention. In FIG. 16, point P 1  in area A corresponds to the first touch of the pen  31  on the touch screen  11 . Point P 2  is located outside area A. Then, the operation is determined as a left touch and a left touch signal is produced. 
     FIG. 17 is a schematic diagram showing a right touch output of the third variant of the first embodiment of the present invention. In FIG. 17, point P 1  in area A corresponds to the first touch of the pen  31  on the touch screen  11 . Point P 3  is located inside area A. Then, the operation is determined as a right touch and a right touch signal is produced. 
     In the first embodiment of the present invention, a right button click operation is determined at the MCU  13  of the touch panel unit  4 . However, it is also possible to determine various operations by means of a software at the computer main body  2 . 
     FIG. 18 is a block diagram showing a computer main body used with a coordinate input device of a second embodiment of the present invention. In FIG. 18, components similar to those of FIG. 3 are indicated with similar reference numerals and will not be described in detail. In the present embodiment, various button operations are determined by means of a device driver  32  installed in a computer main body  31  instead of the MCU  13  of the touch screen unit  4 . 
     The device driver  32  operates according to hardware interrupt supplied from an interrupt processing part  33  of the OS  22  and a timer interrupt supplied from a timer processing part  34  of the OS  22 . When a coordinate data of a contact on the touch screen  11  is supplied from the touch screen unit  4 , the interrupt processing part  33  causes a hardware interrupt on the device driver  32  and supplies an interrupt data. 
     FIG. 19 is a flowchart showing an operation of the device driver of the second embodiment of the present invention upon occurrence of a hardware interrupt. When there is a hardware interrupt from the OS  22 , the device driver  32  checks and determines whether or not the interrupt data supplied from the touch screen unit  4  via the OS  22  is valid (steps S 11 - 1 , S 11 - 2 ). If the result of step S 1 - 12  is positive, the process proceeds to step S 11 - 3 . 
     At step S 11 - 3 , it is determined whether the previous data supplied from the touch screen unit  4  indicates an ON state of the touch screen  11 . If the result of step S 11 - 3  is positive, the process proceeds to step S 11 - 4  to determine whether the current data supplied from the touch screen unit  4  indicates an ON state of the touch screen  11 . 
     If the result of step S 11 - 4  is negative, it can be determined that the touch screen  11  has changed its state from ON to OFF. Thus, an OFF state generation process (step S 11 - 5 ) is implemented as will be described later. 
     If the result of step S 11 - 4  is positive, it can be determined that the touch screen  11  remains in an ON state. Thus, an ON state continuation process (step S 11 - 6 ) is implemented as will be described later. 
     If the result of step S 11 - 3  is negative, the process proceeds to step S 11 - 7  to determine whether the current data supplied from the touch screen unit  4  indicates an ON state of the touch screen  11 . 
     If the result of step S 11 - 7  is positive, it can be determined that the touch screen  11  has changed its state from OFF to ON. Thus, an ON state generation process (step S 11 - 8 ) is implemented as will be described later. 
     If the result of step S 11 - 7  is negative, it can be determined that the touch screen  11  remains in an OFF state. Thus, an OFF state continuation process (step S 11 - 9 ) is implemented as will be described later. 
     Referring now to FIGS. 20 through 23 and to FIG. 4, the OFF generation process, the ON continuation process, the ON generation process and the OFF continuation process of FIG. 19 will be described in detail. 
     FIG. 20 is a flowchart showing an OFF generation process of FIG.  19 . First, at step S 12 - 1 , it is determined whether it is in an ON state. If an OFF state has occurred during phase T 1  which is an ON state, the current coordinate detected at the touch screen unit  4  is set as P 2  (step S 12 - 2 ). Then, the timer measuring the duration of phase T 1  is cleared (step S 12 - 3 ). 
     At step S 12 - 4 , it is determined whether current time exceeds phase T 1  (t 1 +t 1Low ). If the result of step S 12 - 4  is positive, current time is set as t 2  (step S 12 - 5 ). Then, at step S 12 - 6 , it proceeds to the next phase, here phase T 2  (step S 12 - 6 ). Further, a timer is started to measure the predetermined timer period T 2high . Then, the process returns to the process shown in FIG.  19 . 
     If the of result step S 12 - 4  is negative, the there is a phase transition to phase T 0  (initial OFF state) at step S 12 - 8 , and current time is set as t 0  (step S 12 - 9 ). Then, the process returns to the process shown in FIG.  19 . 
     At step S 12 - 1 , if it is determined that an OFF state has not occurred during phase T 1 , the process proceeds to step S 12 - 10  to determine whether an OFF state occurred during phase T 3 . 
     If the result of step S 12 - 10  is negative, that is to say it is determined if it is during one of phases T 0 , T 2  and T 4  in which an OFF state occurred, the process proceeds to step S 12 - 11 . At step S 12 - 11 , it is determined whether it is in WAIT FOR OFF phase. If the result of step S 12 - 11  is positive, there is a phase transition to phase T 0  (initial OFF state) at step S 12 - 8 , and current time is set as t 0  (step S 12 - 9 ). 
     If the result of step S 12 - 11  is negative, a left button off output is supplied to the application (step S 12 - 12 ). Then, there is a phase transition to phase T 0  (initial OFF state) at step S 12 - 8 , and current time is set as t 0  (step S 12 - 9 ). 
     If at step S 12 - 10 , phase T 3  which is a second ON state, the current coordinate detected at the touch screen unit  4  is set as P 4  (step S 12 - 13 ). Then, the timer measuring the duration of phase T 3  is cleared (step S 12 - 14 ). 
     At step S 12 - 15 , it is determined whether current time, that is to say the time where the touch screen  11  has changed from ON state to OFF state, exceeds phase T 3  (t 3 +t 3Low ). If the result of step S 12 - 15  is negative, there is a phase transition to phase T 0  (initial OFF state) at step S 12 - 8 , and current time is set as to (step S 12 - 9 ). 
     If the result of step S 12 - 15  is positive, current time is set as t 4  (step S 12 - 16 ). Then, at step S 12 - 17 , it is proceeded to the next phase, here phase T 4  (step S 12 - 17 ). Further, a timer is started to measure the predetermined timer period T 4high . Then, the process returns to the process shown in FIG.  19 . 
     FIG. 21 is a flowchart showing an ON continuation process of FIG.  19 . First, at step S 13 - 1 , it is determined whether phase T 1  is an ON state. If the result of step S 13 - 1  is positive, the process proceeds to step S 13 - 2 . At step S 13 - 2 , it is determined whether the difference between current coordinate and the initial coordinate P 1  at the beginning of phase T 1  is greater than a predetermined area P 1Limit . 
     If the result of step S 13 - 2  is positive, the timer measuring the duration of phase T 1  is cleared (step S 13 - 3 ). Then, there is a phase transition to WAIT FOR ON phase at step S 13 - 4 . Then, for example a left button switch ON is output (step S 13 - 5 ). If the result of step S 13 - 2  is negative, the process returns to the process shown in FIG.  19 . 
     If, at step S 13 - 1 , it is determined that it is not in phase T 1 , the process proceeds to step S 13 - 6 . At step S 13 - 6 , it is determined whether it is in phase T 3 . If the result of S 13 - 6  is positive, the process proceeds to step S 13 - 7  to determine whether the phase is in the WAIT FOR ON phase. If it is in the WAIT FOR ON phase, the process returns to the process shown in FIG.  19 . If the result of step S 13 - 8  is negative, the coordinate is output at step S 13 - 8 . 
     Thus, a left button ON and a left button touch can be detected. 
     FIG. 22 is a flowchart showing an ON generation process of FIG.  19 . When there is a state transition from OFF state to ON state, at step S 14 - 1 , it proceeds to the next phase (i.e., from phase T 0  to phase T 1 , or, from phase T 2  to phase T 3 ). 
     At step S 14 - 2 , it is determined whether the phase has proceeded to phase T 1 . If the result of step S 14 - 2  is positive, current time is set as t 1  and current coordinate is set as P 1  (step S 14 - 3 ). Then at step S 14 - 4 , it is determined whether time t 1  is within phase T 0  (t 0 +t 1low ). 
     If the result of step S 14 - 4  is positive, current coordinate P 0  is output at step S 14 - 5 , and a timer measuring the duration of phase T 1  is started at step S 14 - 6 . 
     If the result of step S 14 - 4  is negative, current coordinate P 0  is output at step S 14 - 7 . Then a first button switch ON is output (step S 14 - 8 ). There is a phase transition to WAIT FOR OFF phase at step S 14 - 9  and the process returns to the process shown in FIG.  19 . 
     If, at step S 14 - 2 , it is determined that it is not in phase T 1 , the process proceeds to step S 14 - 10  to determine whether it is in phase T 3 . 
     If the result of step S 14 - 10  is positive, current time is set as t 3  and current coordinate is set as P 3  (step S 14 - 11 ). Then, the timer measuring the duration of phase T 2  is cleared (step S 14 - 12 ). Then at step S 14 - 13 , it is determined whether time t 3  is within phase T 2  (t 2 +t 2low ). 
     If the result of step S 14 - 13  is positive, a timer is started to measure the predetermined timer period T 3high  (step S 14 - 14 ). Then, the process returns to the process shown in FIG.  19 . 
     If the result of step S 14 - 13  is negative, there is a phase transition to phase T 1  at step S 14 - 15 . Then, current time is set as t 1  and current coordinate is set as P 1  (step S 14 - 16 ). The process proceeds to S 14 - 5  and S 15 - 6  described above. 
     If, at step S 14 - 10 , it is determined that the phase is not phase T 3 , current coordinate is output at step S 14 - 17  and there is a phase transition to phase T 0  at step S 14 - 18 . 
     FIG. 23 is a flowchart showing an OFF continuation process of FIG.  19 . At step S 15 , the duration of OFF T CONT  is calculated by subtracting current time from OFF generation time t 0 . Then, the process returns to the process shown in FIG.  19 . 
     Referring now to FIG. 24, a timer interrupt process of the second embodiment of the present invention will be described. 
     At step S 16 - 1 , it is determined whether the time measured by the timer has reached initial time t 1  of phase T 1 . If the result of step S 16 - 1  is positive, a T 1  interrupt process is implemented at step S 16 - 2 . The T 1  interrupt process will be described later with reference to FIG.  25 . If the result of step S 16 - 1  is negative, the process proceeds to step S 16 - 3 . 
     At step S 16 - 3 , it is determined whether the time measured by the timer has reached initial time t 2  of phase T 2 . If the result of step S 16 - 3  is positive, a T 2  interrupt process is implemented at step S 16 - 4 . The T 2  interrupt process will be described later with reference to FIG.  26 . If the result of step S 16 - 3  is negative, the process proceeds to step S 16 - 5 . 
     At step S 16 - 5 , it is determined whether the time measured by the timer has reached initial time t 3  of phase T 3 . If the result of step S 16 - 5  is positive, a T 3  interrupt process is implemented at step S 16 - 6 . The T 3  interrupt process will be described later with reference to FIG.  27 . If the result of step S 16 - 5  is negative, the process proceeds to step S 16 - 7 . 
     At step S 16 - 7 , it is determined whether the time measured by the timer has reached initial time t 4  of phase T 4 . If the result of step S 16 - 7  is positive, a T 4  interrupt process is implemented at step S 16 - 8 . The T 4  interrupt process will be described later with reference to FIG.  28 . If the result of step S 16 - 7  is negative, the process proceeds to step S 16 - 9 . At step S 16 - 9 , the time measured by the timer is set as the initial time t 0  of phase T 0 . 
     FIG. 25 is a flowchart showing a T 1  interrupt process (step S 16 - 2 ) of FIG.  24 . At step S 17 - 1 , a first switch ON is output. Then, there is a phase transition to WAIT FOR OFF phase (step S 17 - 2 ). Thus, the T 1  interrupt process can recognize that the switch has been turned ON. 
     FIG. 26 is a flowchart showing a T 2  interrupt process (step S 16 - 4 ) of FIG.  24 . At step S 18 - 1 , a first switch ON is output. Then, a generation of a single click or double click is reserved for an ON state of the first switch (step S 18 - 2 ). Thus, the T 1  interrupt process can recognize that the first switch has been single clicked or double clicked. 
     FIG. 27 is a flowchart showing a T 3  interrupt process (step S 16 - 6 ) of FIG.  24 . At step S 19 - 1 , a second switch ON is output. Then, if a switch corresponding to the right button of a mouse is turned ON, there is a phase transition to WAIT FOR OFF state (step S 19 - 2 ). Thus, the second switch ON is output in the third interrupt process. 
     FIG. 28 is a flowchart showing a T 4  interrupt process (step S 16 - 8 ) of FIG.  24 . At step S 20 - 1 , it is determined whether positions P 2 , P 3 , and P 4  at phases T 2 , T 3  and T 4 , respectively, are located within a circle C 1  of radius R 1 . 
     If the result of step S 20 - 1  is positive, a switch corresponding to the left button of a mouse is output at step S 20 - 2 . Then, a single-click or a double-click is produced (step S 20 - 3 ). 
     If the result of step S 20 - 1  is negative, it is determined if position P 2  at phase T 2  is located within the circuit C 1  of radius R 1  and if position P 4  at phase T 4  is located within the circuit C 2  of radius R 2  (step S 20 - 4 ). 
     If the result of step S 20 - 4  is positive, a second switch ON process is implemented at step S 20 - 5 . At step S 20 - 6 , there is a phase transition to phase T 2 . Then, a single-click or a double-click is produced (step S 20 - 7 ). 
     If the result of step S 20 - 4  is negative, it is determined that there is no switch operation, and there is a phase transition to phase T 0  (step S 20 - 8 ). 
     Referring to FIG. 29, the switch on process of step S 13 - 5  shown in FIG. 21 will be described. At step S 21 - 1 , it is determined whether there has been a button swap operation. If the detected position is within the circle C 1  of radius R 1 , it is determined that there is no button swap operation. If the detected position is outside the circle C 1  of radius R 1 , it is determined that there is a button swap operation. 
     If the result of step S 21 - 1  is positive, the second switch is turned ON at step S 21 - 2 . If the result of step S 21 - 1  is negative, the first switch is turned ON at step S 21 - 3 . After steps S 21 - 2  and S 21 - 3 , it is determined whether the phase is in a WAIT FOR ON phase (step S 21 - 4 ). If the result of step S 21 - 4  is positive, there is a phase transition to phase T 0  at step S 21 - 5 . If the result of step S 21 - 4  is negative, the process directly returns. Thus, either the first switch or the second switch is turned ON. 
     FIG. 30 is a flowchart showing a first switch ON output process. The first switch ON output process corresponds to step S 14 - 8  shown in FIG. 22, step S 17 - 1  shown in FIG. 25, step S 18 - 1  shown in FIG.  26  and step  20 - 2  shown in FIG.  28 . 
     In the first switch ON output process, it is determined whether there is a button swap (step S 22 - 1 ). If the result of step S 22 - 1  is negative, the first switch is turned ON (step S 22 - 2 ). If the result of step S 22 - 1  is positive, the second switch is turned ON (step S 22 - 3 ). 
     FIG. 31 is a flowchart showing a second switch ON output process. The second switch ON output process corresponds to step S 19 - 1  shown in FIG.  27  and step S 20 - 5  shown in FIG.  28 . 
     In the second switch ON output process, it is determined whether there is a button swap (step S 23 - 1 ). If the result of step S 23 - 1  is negative, the second switch is turned ON (step S 23 - 2 ). If the result of step S 23 - 1  is positive, the first switch is turned ON (step S 22 - 3 ). 
     FIG. 32 is a flowchart showing a single-click or double-click generation process. The single-click or double-click generation process corresponds to steps S 20 - 3  and S 20 - 7  shown in FIG.  28 . 
     In the single-click or double-click generation process, an OFF is output for all switches (step S 24 - 1 ). Then, at step S 24 - 2 , it is determined whether the OFF state of step S 24 - 1  is in phase T 2 . If the result of step S 24 - 2  is positive, there is a phase transition to phase T 0  (step S 24 - 3 ). If the result of step S 24 - 2  is negative, the process proceeds to step S 24 - 4 . 
     At step S 24 - 4 , it is determined whether the OFF state of step S 24 - 1  is in phase T 4 . If the result of step S 24 - 4  is positive, the phase is returned to phase T 2  (step S 24 - 5 ). Then, at step S 24 - 6 , a generation of the T 2  interrupt process (see FIG. 25) is reserved. If the result of step S 24 - 4  is negative, there is a phase transition to phase T 0  (step S 24 - 7 ). Accordingly, a generation of a single-click or double-click is reserved. 
     Referring now to FIGS. 33 through 35 and also to FIG. 4, various operations carried out in the second embodiment of the present invention will be described. 
     FIG. 33 is a schematic diagram showing a left button click operation of the second embodiment of the present invention. During phase T 0 , there is a touch on the touch screen  11  at position P 1 . The position P 1  is illustrated as a center of a circle C 1  of radius R 1 . Then, there is a phase transition to phase T 1 . During phase T 1 , there is a release at position P 2  within a circle C 1  of radius R 1  having position P 1  as the center. Then, there is a phase transition to phase T 2 . Then, time t 2high  is elapsed while in a released state and there is a phase transition to phase T 0 . Such operation is regarded as a single click of the left button of a mouse. 
     Also, during phase T 2  and before time t 2high , if there is a touch on the touch screen  11  at position P 3  within the circle C 1 , there is a phase transition to phase T 3 . During phase T 3  and before time t 3high , if there is a release on the touch screen  11  at position P 4  in the circle C 1 , there is a phase transition to phase T 4 . During T 4  and before t 4high , if there is no further touch, the operation is regarded as a double click of the left button of a mouse. 
     FIG. 34 is a schematic diagram showing a right button click operation of the second embodiment of the present invention. During phase T 0 , there is a touch on the touch screen  11  at position P 1 . The position P 1  is illustrated as a center of a circle C 2  of radius R 2  and of a circle C 3  of radius R 3 . Then, there is a phase transition to phase T 1 . If there is a release on the touch screen  11  at position P 2  in the circle C 2 , there is a phase transition to phase T 2 . During phase T 2  and before time t 2high , if there is a touch on the touch screen  11  at position P 3  outside the circle C 2  and within the circle C 3 , there is a phase transition to phase T 3 . During phase T 3  and before time t 3high , if there is a release on the touch screen  11  at position P 4  in the circle C 2 , there is a phase transition to phase T 4 . During T 4  and before t 4high , if there is no further touch, the operation is regarded as a single click of the right button of a mouse. 
     FIG. 35 is a schematic diagram showing a drag operation of the second embodiment of the present invention. During phase T 0 , there is a touch on the touch screen  11  at position P 1 . The position P 1  is illustrated as a center of a circle C 4  of radius R 4 . Then, there is a phase transition to phase T 1 . During phase T 1  and before time t 1high , if the point P 1  is brought outside circle C 4  while keeping in contact with the touch screen  11 , the operation is not regarded as a click. 
     In order to determine a single click of the right button, in FIGS. 33 through 35, together with the timing of the touch and/or release, it is detected whether touch and/or release has occurred inside or outside a predetermined area. It is to be noted that an increased number of functions can be achieved by providing predetermined angular regions about position P 1 . 
     FIG. 36 is a diagram illustrating various operations which may be carried out by the second embodiment of the present invention. There is a first touch on the touch screen  11  at position P 1 . The position P 1  is illustrated as a center of a circle C 5  of radius R 5  and of a circle C 6  of radius R 6 . The region outside circle C 5  and inside circle C 6  is divided into regions Sa, Sb, Sc and Sd which are separated by non-sensitive regions Sab, Sbc, Scd and Sda. 
     If, after a touch at position P 1  during T 1 , there is a touch in region Sa during phase T 2  and a release during T 3 , the operation is regarded as a single click of the right button. If, after a touch at position P 1  during T 1 , there is a touch in region Sb during phase T 2  and a release during T 3 , the operation is regarded as a second operation. If, after a touch at position P 1  during T 1 , there is a touch in region Sc during phase T 2  and a release during T 3 , the operation is regarded as a third operation. If, after a touch at position P 1  during T 1 , there is a touch in region Sd during phase T 2  and a release during T 3 , the operation is regarded as a fourth operation. 
     With the embodiment described above, second through fourth operations can be recognized in addition to the single click of the right button. The non-sensitive regions Sab, Sbc, Scd and Sda may prevent false operations of the touch screen unit  4 . Also, further operations can be achieved by increasing the number of predetermined regions provided on the touch screen. 
     Further, the present invention is not limited to these embodiments, but 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. 11-186599 filed on Jun. 30, 1999, the entire contents of which are hereby incorporated by reference.