Patent Publication Number: US-7712256-B2

Title: Opening and closing apparatus

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates to an opening and closing apparatus. 
   Conventionally, there has been a vehicle provided with an opening and closing apparatus structured such as to slide a door panel along the fore-and-aft direction of the vehicle by a driving force of a motor so as to open and close a door of the vehicle. The opening and closing apparatus is provided with a detecting sensor for detecting an existence of a foreign material between the door panel under a closing motion and a vehicle body. 
   For example, a detecting sensor described in Japanese Laid-Open Patent Publication No. 2004-257788 is provided with a sensor electrode for detecting a foreign material between a door panel and a vehicle body on the basis of a change of an electrostatic capacity. The sensor electrode is arranged in a front end of the door panel. Further, if a foreign material exists between the door panel and the vehicle body during the closing motion of the door panel, the electrostatic capacity in the sensor electrode is changed, and the change of the electrostatic capacity is output as a signal voltage to a control apparatus. The control apparatus compares an input voltage signal with a predetermined threshold value. In the case that the signal voltage is over the predetermined threshold value, the control apparatus determines that a foreign material exists between the door panel and the vehicle body, and moves the door panel to a full-open position on the basis of the driving force of the motor. As mentioned above, the detecting sensor described in Japanese Laid-Open Patent Publication No. 2004-257788 detects a foreign material existing between the door panel and the vehicle body in a non-contact manner. 
   If the door panel during the closing motion comes close to a full-close position, a front end of the door panel comes close to a front door and a center pillar (a B pillar). Since the front end of the door panel comes close to the front door and the center pillar, whereby the electrostatic capacity in the sensor electrode is changed, there is a risk that the signal voltage gets over the predetermined threshold value and the existence of a foreign material is erroneously detected. Accordingly, in the detecting sensor described in Japanese Laid-Open Patent Publication No. 2004-257788, if the door panel is arranged at a position spaced at a predetermined distance to the full-close position of the door panel, a control apparatus cancels a function of detecting a foreign material in the non-contact manner, whereby an erroneous detection of the existence of a foreign material is prevented. Further, when the door panel slides in a range from the position spaced at the predetermined distance to the full-close position of the door panel to the full-close position, the detecting sensor detects the contact between the door panel and a foreign material, thereby detecting a foreign material between the door panel and the vehicle body. 
   However, in the case that the function of detecting a foreign material between the door panel and the vehicle body in the non-contact manner is cancelled, when the door panel slides in the range from the position spaced at the predetermined distance to the full-close position of the door panel to the full-close position, a foreign material existing between the door panel and the vehicle body is detected first at a time when the door panel is brought into contact with a foreign material. Accordingly, there is a risk that a foreign material is wedged between the vehicle body and the door panel and a great load is applied to the foreign material, while the door panel is stopped or is moved toward the full-open position after the door panel is brought into contact with the foreign material. Therefore, it is desirable that a foreign material existing between the door panel and the vehicle body be detected in the non-contact manner as much as possible. In other words, it is desirable to widen the range in which a foreign material existing between the door panel and the vehicle body is detected in the non-contact manner, within the moving range of the door panel. 
   Further, since the shapes of the front door and the center pillar vary in correspondence to vehicle types, a degree of the change of the electrostatic capacity in the sensor electrode at a time when the front end of the door panel comes close to the front door and the center pillar is different in correspondence to the vehicle type. Accordingly, in order to widen the range for detecting a foreign material existing between the door panel and the vehicle body in the non-contact manner, it is desirable to execute the erroneous detection prevention of the existence of a foreign material caused when the front end of the door panel comes close to the front door and the center pillar, in correspondence to the vehicle type. 
   SUMMARY OF THE INVENTION 
   An object of the preset invention is to provide an opening and closing apparatus which can execute an erroneous detection prevention of a foreign material in correspondence to the shape of a fixed body such as a vehicle or the like, and widens a range in which a foreign material existing between the fixed body and a movable body can be detected in a non-contact manner within a movable range of the movable body such as a door or the like. 
   In accordance with one aspect of the present invention, an opening and closing apparatus including a fixed body, an opening portion, a movable body, a detecting sensor, a judging portion, a position detecting portion, a first change position, and a threshold value is provided. The fixed body has conductivity. The opening portion is formed in the fixed body and has a peripheral edge. The movable body is moved between a full-close position closing the opening portion and a full-open position leaving open the opening portion. The detecting sensor has a sensor electrode provided at at least one of an end portion positioned in a front side in a moving direction at a time of a closing motion of the movable body, and a peripheral edge of the opening portion facing the movable body in the moving direction in the movable body. The detecting sensor outputs an electrostatic capacity detection signal in correspondence to a change of an electrostatic capacity between the sensor electrode and a conductive foreign material moving close to the sensor electrode. The judging portion has a threshold value for judging whether or not a foreign material exists between the movable body and the peripheral edge of the opening portion, compares the threshold value with a detection value on the basis of the electrostatic capacity detection signal, and judges, on the basis of a result of comparison, whether or not a foreign material exists between the movable body and the peripheral edge of the opening portion. The position detecting portion outputs a position detection signal corresponding to a position of the movable body. The first change position is previously set between the full-open position and the full-close position. The threshold value change portion changes the threshold value on the basis of the position detection signal in the case of detecting, on the basis of the position detection signal, that the movable body is arranged at the first change position during a closing motion of the movable body. 
   Other aspects and advantages of the present invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention, together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which: 
       FIG. 1  is a perspective view showing a motor-driven slide door apparatus in accordance with an embodiment; 
       FIG. 2  is a perspective view showing the motor-driven slide door apparatus; 
       FIG. 3  is a perspective view showing a door panel; 
       FIG. 4  is a perspective view showing a terminal treatment portion; 
       FIG. 5(   a ) is a cross sectional view showing a foreign material detecting sensor; 
       FIG. 5(   b ) is a cross sectional view showing a sensor main body; 
       FIG. 6  is a block diagram showing an electric structure of the motor-driven slide door apparatus; 
       FIG. 7  is a graph showing a relation between a position of a door panel, and a change amount of an electrostatic capacity between a vehicle body and a sensor electrode; 
       FIG. 8  is a graph showing a relation between the position of the door panel and a threshold value; 
       FIG. 9  is a perspective view showing a part of a vehicle in which a foreign material detecting sensor in accordance with a first modified embodiment is arranged; 
       FIG. 10  is a graph showing a relation between a position of a door panel and a threshold value in accordance with a second modified embodiment; and 
       FIG. 11  is a graph showing a relation between a position of a door panel and a threshold value in accordance with a third modified embodiment. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   A description will be given below of an embodiment obtained by embodying the present invention to a motor-driven slide door apparatus mounted on a vehicle in accordance with the accompanying drawings.  FIGS. 1 and 2  are perspective views showing a motor-driven slide door apparatus  1  (an opening and closing apparatus) serving as an opening and closing apparatus in accordance with the present embodiment. As shown in  FIGS. 1 and 2 , the motor-driven slide door apparatus  1  is mounted on a vehicle  2 , and is provided with a vehicle body  2   a  serving as a fixed body and a body of a vehicle, a door panel  2   b  serving as a movable body, an actuating mechanism  5 , a driving mechanism  6 , a foreign material detecting portion  7 , and a control circuit apparatus  8 . The control circuit apparatus  8  serves as a judging portion and a threshold value changing portion. 
   The vehicle body  2   a  and the door panel  2   b  are formed by a metal having conductivity. A door opening  9  serving as an opening portion having a quadrangular shape is formed in a left side surface of the vehicle body  2   a . The door opening  9  is opened and closed by the door panel  2   b  having a quadrangular shape corresponding to the door opening  9 . A door panel  2   c  facing a front passenger seat is provided in a front side of the door opening  9 . A center pillar  2   d  having a conductivity extends along upper and lower sides of the vehicle  2 , within the vehicle near a boundary between the door panel  2   c  and the door panel  2   b  arranged at a full-close position. 
   The door panel  2   b  is attached so as to be movable along the fore-and-aft direction of the vehicle body  2   a  by the actuating mechanism  5 , for opening and closing the door opening  9 . A lock mechanism (not shown), for example, a latch is provided in the door panel  2   b . The lock mechanism fixes the door panel  2   b  so as to be immovable with respect to the vehicle body  2   a , in a state in which the door panel  2   b  closes the door opening  9 , that is, in a state in which the door panel  2   b  is arranged at the full-close position. A half latch detecting portion (not shown) is provided in the lock mechanism. The half latch detecting portion outputs a half latch detection signal to the control circuit apparatus  8 , if the lock mechanism is in a half latch state. 
   The actuating mechanism  5  is constituted by an upper rail  11 , a lower rail  12  and a center rail  13  provided in the vehicle body  2   a , and an upper arm  15 , a lower arm  16  and a center arm  17  provided in the door panel  2   b.    
   The upper rail  11  and the lower rail  12  are respectively provided in an upper portion and a lower portion of the door opening  9  in the vehicle  2 , and extend along fore-and-aft direction of the vehicle  2 . The center rail  13  is provided in an approximately center portion of a portion positioned in a rear side of the door opening  9  in the vehicle  2 , and extends along fore-and-aft direction of the vehicle  2 . Each of the rails  11  to  13  is formed in such a manner as to extend along fore-and-aft direction of the vehicle  2 . A front end portion of each of the rails  11  to  13  is curved toward an inner side of the vehicle. 
   The arms  15  to  17  are respectively fixed to predetermined positions of an upper portion, a lower portion and a center portion in a side surface facing the inner side of the vehicle of the door panel  2   b . The upper arm  15  is coupled to the upper rail  11 . The lower arm  16  is coupled to the lower rail  12 . The center rail  13  is coupled to the center arm  17 . The arms  15  to  17  are respectively guided by the rails  11  to  13  so as to be movable along fore-and-aft direction of the vehicle  2 . 
   The driving mechanism  6  is provided with an endless belt  21 , a slide actuator  22 , a closure actuator  23  and a position detecting apparatus  24  (refer to  FIG. 6 ) serving as a position detecting portion. The driving mechanism  6  is controlled by the control circuit apparatus  8 . A drive pulley  26  rotating around a shaft extending along the upper and lower sides of the vehicle  2  and a plurality of driven pulleys  27  are provided in a side portion of the lower rail  12 . The endless belt  21  is wound around the drive pulley  26  and the driven pulleys  27 . A distal end portion of the lower arm  16  is fixed to the endless belt  21 . 
   The slide actuator  22  is connected to the drive pulley  26 . The slide actuator  22  is provided with a slide motor  28  (refer to  FIG. 6 ), and a speed reducing mechanism (not shown) reducing a speed of rotation of the slide motor  28 . The slide motor  28  is rotated in correspondence to a drive signal input from the control circuit apparatus  8 . The rotation of the slide motor  28  is reduced by the speed reducing mechanism, and is transmitted to the drive pulley  26  from an output shaft (not shown) of the slide actuator  22 . Further, if the endless belt  21  is rotated by the rotation of the drive pulley  26 , the lower arm  16  moves along the lower rail  12 , and the door panel  2   b  is slid forward and backward. 
   The closure actuator  23  is arranged in an inner portion of the door panel  2   b . The closure actuator  23  is provided with a closure motor  29  (refer to  FIG. 6 ), and a speed reducing mechanism (not shown) reducing a speed of rotation of the closure motor  29 . The closure motor  29  is rotated in correspondence to the drive signal input from the control circuit apparatus  8  so as to actuate the lock mechanism and move the door panel  2   b  to the position where the lock can be achieved by the lock mechanism. 
   As shown in  FIG. 6 , the position detecting apparatus  24  is arranged to correspond to one of a rotating shaft (not shown) of the slide motor  28 , an output shaft (not shown) of the slide actuator  22 , and reducing gears (not shown). The reducing gears are provided between the rotating shaft of the slide motor  28  and the output shaft of the slide actuator  22 , and constitute the speed reducing mechanism. The position detecting apparatus  24  detects an amount of rotation of any one of the rotating shaft, the output shaft and the speed reducing gear from a time point when the slide motor  28  starts driving. The position detecting apparatus  24  outputs a position detection signal corresponding to the detected amount of rotation to the control circuit apparatus  8 . The position detecting apparatus  24  is constituted, for example, by a permanent magnet rotating together with any one of the rotating shaft, the output shaft and the speed reducing gear, and a Hall element arranged so as to face the permanent magnet, and outputs a pulse signal as a position detection signal. 
   As shown in  FIG. 1 , a dash board  32  of the vehicle  2  is provided with an operating switch  31  electrically connected to the control circuit apparatus  8 . If the operating switch  31  is operated by a passenger so as to leave open the door opening  9 , the operating switch  31  outputs an open signal for sliding the door panel  2   b  so as to leave open the door opening  9  to the control circuit apparatus  8 . On the other hand, if the operating switch  31  is operated by the passenger so as to close the door opening  9 , the operating switch  31  outputs a close signal for sliding the door panel  2   b  so as to close the door opening  9  to the control circuit apparatus  8 . 
   As shown in  FIG. 3 , the foreign material detecting portion  7  is provided with a foreign material detecting sensor  41  and a protector  42 . The foreign material detecting portion  7  detects the existence of a foreign material having a conductivity between the door panel  2   b  and the vehicle body  2   a , in detail, between a front end of the door panel  2   b  and a peripheral edge (a rear end of the door panel  2   c  in the present embodiment) of the door opening  9  facing the front end, at a time when the door panel  2   b  is slid in a direction of closing the door opening  9 . 
   As shown in  FIGS. 5(   a ) and  6 , the foreign material detecting sensor  41  serving as the detecting sensor is provided with a sensor main body  44 , an electrostatic capacity detecting apparatus  45  and a current detecting element  46 . As shown in  FIG. 5(   a ), the sensor main body  44  is arranged in an end portion positioned in a front side in a forward moving direction at a time of a closing operation of the door panel  2   b , that is, a front end of the door panel  2   b . The sensor main body  44  has a coaxial cable shape. In detail, as shown in  FIG. 5(   b ), a piezoelectric rubber  52  having a cylindrical shape is provided in an outer periphery of a core electrode  51  having a cylindrical shape so as to be coaxial with the core electrode  51 . The piezoelectric rubber  52  has a nature that a value of resistance becomes small and an electric current flows if a pressing force is applied to the piezoelectric rubber  52 , and has an insulating property in a state in which the pressing force is not applied. A sensor electrode  53  constituted by a conductor body having a cylindrical shape is provided in an outer periphery of the piezoelectric rubber  52  so as to be coaxial with the core electrode  51 . An outer skin  54  having an insulating property and a cylindrical shape is provided in an outer periphery of the sensor electrode  53  so as to be coaxial with the core electrode  51 . 
   As shown in  FIG. 3 , one end portion (an upper end portion in  FIG. 3 ) of the sensor main body  44  is molded by a resin, and a terminal treatment portion  61  is provided in the other end portion (a lower end portion in  FIG. 3 ) of the sensor main body  44  so as to be integrally formed with the sensor main body  44 . The terminal treatment portion  61  electrically connects the sensor main body  44 , and the electrostatic capacity detecting apparatus  45  and the current detecting element  46 . 
   As shown in  FIGS. 4 and 5(   a ), the terminal treatment portion  61  is structured such that a substrate (not shown) on which a buffer amplifier  62  and a plurality of connecting metal plates (not shown) are arranged is molded by resin together with the sensor main body  44 . An input terminal of the buffer amplifier  62  is electrically connected to the sensor electrode  53  via the metal plate. An output terminal of the buffer amplifier  62  is electrically connected to a terminal  63  provided in such a manner as to be exposed to an outer surface of the terminal treatment portion  61 . Four lead wires  64  to  67  extend from the terminal treatment portion  61 . The lead wire  64  is connected to the buffer amplifier  62  so as to supply a power source to the buffer amplifier  62 . The lead wire  65  connects the buffer amplifier  62  and the core electrode  51  to the ground surface. The lead wire  66  electrically connects the sensor electrode  53  to the electrostatic capacity detecting apparatus  45 . The lead wire  67  electrically connects the buffer amplifier  62  to the current detecting element  46 . The sensor electrode  53  is electrically connected to the current detecting element  46  via the buffer amplifier  62  by the lead wire  67 . An electric current is supplied to the sensor electrode  53  via the control circuit apparatus  8 . 
   As shown in  FIG. 6 , the electrostatic capacity detecting apparatus  45  constitutes an electrostatic capacity type sensor detecting a foreign material existing between the door panel  2   b  and the vehicle body  2   a  in a non-contact manner together with the sensor electrode  53 . The electrostatic capacity detecting apparatus  45  is driven by the control circuit apparatus  8 . If the electrostatic capacity detecting apparatus  45  detects a change of the electrostatic capacity between the sensor electrode  53  and the ground surface, it outputs the electrostatic capacity detection signal corresponding to an amount of change of the electrostatic capacity in the sensor electrode  53  to the control circuit apparatus  8 . 
   The current detecting element  46  constitutes a contact type sensor which is brought into contact with a foreign material existing between the door panel  2   b  and the vehicle body  2   a  so as to detect a foreign material, together with the core electrode  51 , the piezoelectric rubber  52  and the sensor electrode  53 . The current detecting element  46  is arranged within the door panel  2   b , and detects the electric current flowing through a portion between the sensor electrode  53  and the core electrode  51 . If the pressing force is applied to the sensor main body  44  from the external portion, that is, if the pressing force is applied to the piezoelectric rubber  52 , the value of resistance of the piezoelectric rubber  52  is changed and the electric current flows through the portion between the sensor electrode  53  and the core electrode  51 . At this time, the current detecting element  46  outputs a current detection signal indicating that the electric current flows through the portion between the sensor electrode  53  and the core electrode  51  to the control circuit apparatus  8 . A structure shown in  FIG. 6  and an operation obtained from the structure shown in  FIG. 6  correspond to one example, and they may be approximately changed. 
   As shown in  FIG. 5(   a ), the protector  42  holds the sensor main body  44 , and fixes the sensor main body  44  to the door panel  2   b . The protector  42  is provided with a mounting portion  71 , and a holding portion  72  integrally formed with the mounting portion  71 . 
   The mounting portion  71  is constituted by a reinforcing member  74  covered by an insulating resin material (including an elastomer and a rubber). The reinforcing member  74  is constituted by a plurality of bone members  74   a  coupled to each other and having a U shape and conductivity. A mounting groove  75  extending in a longitudinal direction of the mounting portion  71  and open toward an opposite side to the holding portion  72  are formed at a portion positioned in an inner side of the bone members  74   a  in the mounting portion  71 . The length in a longitudinal direction of the mounting portion  71  is set to be equal to the length in an axial direction of the sensor main body  44  (refer to  FIG. 3 ). An electric wire  77  (refer to  FIG. 4 ) is electrically connected to one end portion of the reinforcing member  74 . 
   The holding portion  72  has a cylindrical shape, and the axial length of the holding portion  72  is set equal to the length of the mounting portion  71  in the longitudinal direction. The inner diameter of an insertion hole  81  formed by an inner peripheral surface of the holding portion  72  is formed slightly larger than an outer diameter of the sensor main body  44 . The holding portion  72  mentioned above is constituted by a guard electrode  82  and a contact portion  83 . 
   The guard electrode  82  is formed by elastically deformable conductive resin materials (including the elastomer and the rubber). The guard electrode  82  is integrally formed with an opposite side portion to the opening portion in the mounting portion  71  having the U shape. The guard electrode  82  is brought into contact with the reinforcing member  74 . The guard electrode  82  has a circular arc shape open toward the opposite side to the mounting portion  71 , in the shape as seen from an axial direction of the holding portion  72 . 
   The contact portion  83  is formed by an elastically deformable insulative resin (including elastomer and rubber). The shape of the contact portion  83  as seen from the axial direction of the holding portion  72  has a circular arc shape open toward the guard electrode  82 . The contact portion  83  is integrally formed with the guard electrode  82 . In other words, the contact portion  83  and the guard electrode  82  are integrally formed, whereby the holding portion  72  having an approximately cylindrical shape is formed. 
   An outer peripheral surface of the protector  42  is covered by an insulating coating  84 , for example, made of silicon. In a state in which the sensor main body  44  is inserted into the holding portion  72 , the protector  42  is fixed to the front end of the door panel  2   b . In detail, an inner plate  91  constituting the door panel  2   b  has a fixed portion  92  formed in such a manner as to extend along a width of the vehicle in a front end portion (an end portion positioned in a front side of the vehicle  2 ), and has an extended portion  93  extended toward the front side of the vehicle from an end portion of the fixed portion  92  facing outside of the vehicle. A distal end of the extended portion  93  is covered by an outer plate  94  constituting the door panel  2   b . A bracket  95  having a bracket main body  95   a  extended toward the front side of the vehicle  2  is fixed to a side surface of the fixed portion  92  facing the front side of the vehicle  2 . The bracket  95  extends along upper and lower sides of the vehicle  2 . The bracket main body  95   a  is pressure inserted to the mounting groove  75 , whereby the protector  42  is fixed to the bracket main body  95   a , that is, the front end of the door panel  2   b.    
   In a state in which the sensor main body  44  is fixed to the door panel  2   b  via the protector  42 , the sensor main body  44  protrudes to the front side of the vehicle  2  than a distal end (including the outer plate  94  covering the extended portion  93 ) of the extended portion  93 . Further, the end surface  82   a  of the guard electrode  82 , which faces the outside of the vehicle, is positioned in the front side of the vehicle  2  than the distal end of the extended portion  93 , and a part of the guard electrode  82  is arranged between the outer plate  94  and the sensor main body  44 . 
   As shown in  FIG. 4 , in a state in which the sensor main body  44  is accommodated within the holding portion  72 , the electric wire  77  provided in the lower end of the reinforcing member  74  is screwed with the terminal  63  of the terminal treatment portion  61  provided in the lower end of the sensor main body  44 . Accordingly, as shown in  FIG. 5(   a ), the output terminal of the buffer amplifier  62  and the bone member  74   a  are electrically connected, and the output terminal of the buffer amplifier  62  and the guard electrode  82  are electrically connected. Therefore, the sensor electrode  53  and the guard electrode  82  are electrically connected via the buffer amplifier  62 . An electric power is supplied to the guard electrode  82  via the sensor electrode  53  and the buffer amplifier  62 , and a voltage of the guard electrode  82  is kept at the same value as a voltage of the sensor electrode  53 . 
   If the voltage of the guard electrode  82  is kept at the same value as the voltage of the sensor electrode  53 , even in the case that the electrostatic capacity between the guard electrode  82  and a foreign material  101  is changed by the foreign material  101  coming close to the sensor electrode  53  from a side opposite to the guard electrode  82 , the change of the electrostatic capacity does not affect the amount of change of the electrostatic capacity detected by the sensor electrode  53 . Accordingly, a portion facing the guard electrode  82  in the sensor electrode  53  comes to a dead zone. On the contrary, a portion which does not face the guard electrode  82  in the sensor electrode  53 , that is, a portion facing the contact portion  83  in the sensor electrode  53  has a detection range a capable of detecting the change of the electrostatic capacity due to the approach of a foreign material  102 . 
   As shown in  FIGS. 1 and 6 , the control circuit apparatus  8  is arranged in the inner portion of the door panel  2   b . An electric power is supplied to the control circuit apparatus  8  from a battery  110  of the vehicle  2 . The control circuit apparatus  8  outputs various drive signals for controlling the slide actuator  22  and the closure actuator  23  in correspondence to various signals input from the half latch detecting portion, the position detecting apparatus  24 , the operating switch  31 , the electrostatic capacity detecting apparatus  45  and the current detecting element  46 . Further, the control circuit apparatus  8  detects a slide amount of the door panel  2   b , that is, a position of the door panel  2   b  on the basis of the position detection signal input from the position detecting apparatus  24 . 
   If the current detection signal is input to the control circuit apparatus  8  from the current detecting element  46  during the closing motion of the door panel  2   b , the control circuit apparatus  8  determines on the basis of the input of the current diction signal that a foreign material exists between the door panel  2   b  and the vehicle body  2   a . Further, the control circuit apparatus  8  outputs to the slide motor  28  the drive signal for moving the door panel  2   b  to the full-open position. 
   The control circuit apparatus  8  has a threshold value for judging on the basis of the electrostatic capacity detection signal whether or not a foreign material exists between the door panel  2   b  and the vehicle body  2   a . If the electrostatic capacity detection signal is input to the control circuit apparatus  8  from the electrostatic capacity detecting apparatus  45 , the control circuit apparatus  8  detects a change amount (a detection value) of the electrostatic capacity in the sensor electrode  53  on the basis of the input electrostatic capacity detection signal. In the case that the detected change amount of the electrostatic capacity is larger than the threshold value as a result of comparison between the detected change amount of the electrostatic capacity and the threshold value, the control circuit apparatus  8  determines that a foreign material exists between the door panel  2   b  and the vehicle body  2   a . Further, the control circuit apparatus  8  outputs to the slide motor  28  the drive signal for moving the door panel  2   b  to the full-open position. 
     FIG. 7  shows a relation between the position of the door panel  2   b  during the closing motion, and the change amount of the electrostatic capacity actually detected by the sensor electrode  53 , in the case that no foreign material exists between the door panel  2   b  and the vehicle body  2   a .  FIG. 7  shows that the change amount of the electrostatic capacity in the sensor electrode  53  has a characteristic that if the door panel  2   b  passes a predetermined position, the change amount of the electrostatic capacity becomes larger in a curved manner while increasing a change rate step by step in proportion to coming close to the full-close position Pc. The change amount of the electrostatic capacity in the sensor electrode  53  is changed as shown in  FIG. 7 , because the front end of the door panel  2   b  comes close to the rear end of the door panel  2   c  and the center pillar  2   d  as the door panel  2   b  comes close to the full-close position Pc, whereby the electrostatic capacity becomes larger in the portion between the sensor electrode  53 , and the rear end of the door panel  2   c  and the center pillar  2   d . Accordingly, the control circuit apparatus  8  in accordance with the present embodiment changes the threshold value in correspondence to the position of the door panel  2   b , by changing the change rate of the threshold value in correspondence to the position of the door panel  2   b , as shown in  FIG. 8 . 
   A first door position P 1  is set to a position spaced at a predetermined distance (about 50 to 70 millimeters) to the full-close position Pc. In the case that the door panel  2   b  moves within a first moving range A 1  from the full-open position Po to the first door position P 1 , the change amount of the electrostatic capacity in the sensor electrode  53  comes to an approximately fixed value if no foreign material lies between the door panel  2   b  and the vehicle body  2   a . Accordingly, as shown in  FIG. 8 , in the case that the door panel  2   b  moves within the first moving range A 1 , the control circuit apparatus  8  sets the threshold value to a fixed value. In other words, the control circuit apparatus  8  sets a change rate of the threshold value to zero. The first door position P 1  corresponds to a position at which the electrostatic capacity starts increasing between the sensor electrode  53  and the center pillar  2   d , that is, a position of the door panel  2   b  at which the change amount of the electrostatic capacity in the sensor electrode  53  starts increasing, on the basis of the fact that the front end of the door panel  2   b  comes close to the center pillar  2   d , as shown in  FIG. 7 . 
   As shown in  FIG. 8 , if the door panel  2   b  is arranged at the first door position P 1 , the control circuit apparatus  8  changes the change rate of the threshold value. A second door position P 2  is set between the first door position P 1  and the full-close position Pc. Further, in the case that the door panel  2   b  moves within a second moving range A 2  from the first door position P 1  to the second door position P 2 , the control circuit apparatus  8  linearly enlarges the threshold value in accordance with the movement of the door panel  2   b  at the change rate changed at a time when the door panel  2   b  is arranged at the first door position P 1 . 
   In detail, the second door position P 2  corresponds to a position at which the front end of the door panel  2   b  comes close to the door panel  2   c , whereby the electrostatic capacity starts increasing between the sensor electrode  53  and the door panel  2   c , that is, at a position of the door panel  2   b  at which the change amount of the electrostatic capacity in the sensor electrode  53  further starts increasing, as shown in  FIG. 7 . Further, in the second moving range A 2 , if no foreign material lies between the door panel  2   b  and the vehicle body  2   a , the change amount of the electrostatic capacity in the sensor electrode  53  becomes larger in a curved manner by being affected by the approach of the sensor electrode  53  to the center pillar  2   d.    
   Accordingly, the change rate of the threshold value changed at a time when the door panel  2   b  is arranged at the first door position P 1  corresponds to a value changing the threshold value in the second moving range A 2  so as to be positioned on a straight line extending along a curve expressing a relation between the position of the door panel  2   b  and the amount of change of the electrostatic capacity in the case that the door panel  2   b  moves in the second moving range A 2 . The threshold value in the second moving range A 2  is larger than the amount of change of the electrostatic capacity in the sensor electrode  53  in the case that the door panel  2   b  moves in the second moving range A 2  in a state in which no foreign material lies between the door panel  2   b  and the vehicle body  2   a.    
   As shown in  FIG. 8 , if the door panel  2   b  is arranged at the second door position P 2 , the control circuit apparatus  8  changes the change rate of the threshold value. In detail, after the door panel  2   b  is arranged near the second door position P 2 , the amount of change of the electrostatic capacity in the sensor electrode  53  is affected by the movement of the sensor electrode  53  close to the door panel  2   c , and becomes larger in a curved manner as the door panel  2   b  comes close to the full-close position Pc. 
   At this time, the change rate of the amount of change of the electrostatic capacity in the sensor electrode  53  is larger than the change rate of the amount of change of the electrostatic capacity in the sensor electrode  53  at a time when the door panel  2   b  moves within the second moving range A 2 . Accordingly, when the door panel  2   b  is arranged at the second door position P 2 , the control circuit apparatus  8  makes the change rate of the changed threshold value larger than the change rate of the threshold value in the second moving range A 2 . A third door position P 3  is set between the second door position P 2  and the full-close position Pc. Further, in the case that the door panel  2   b  moves within a third moving range A 3  from the second door position P 2  to the third door position P 3 , the control circuit apparatus  8  linearly enlarges the threshold value in accordance with the movement of the door panel  2   b  at the change rate changed at a time when the door panel  2   b  is arranged at the second door position P 2 . 
   The change rate of the threshold value changed at a time when the door panel  2   b  is arranged at the second door position P 2  corresponds to a value changing the threshold value in the third moving range A 3  so as to be positioned on a straight line extending along a curve expressing a relation between the position of the door panel  2   b  and the amount of change of the electrostatic capacity in the case that the door panel  2   b  moves in the third moving range A 3 . The threshold value in the third moving range A 3  is larger than the amount of change of the electrostatic capacity in the sensor electrode  53  in the case that the door panel  2   b  moves in the third moving range A 3  in a state in which no foreign material lies between the door panel  2   b  and the vehicle body  2   a.    
   In the case that the door panel  2   b  moves in a fourth moving range A 4  from the third door position P 3  to the full-close position Pc, the control circuit apparatus  8  invalidates the electrostatic capacity detection signal input from the electrostatic capacity detecting apparatus  45 . In the case that the door panel  2   b  exists within the fourth moving range A 4 , it is very unlikely that a foreign material is wedged between the door panel  2   b  and the vehicle body  2   a.    
   Next, a description will be given of a motion of the motor-driven slide door apparatus  1  as a whole. If the open signal is input from the operating switch  31 , the control circuit apparatus  8  outputs a drive signal for opening the door panel  2   b  to the slide motor  28  so as to drive the slide motor  28  in a direction of opening the door panel  2   b . Further, when the drive force of the slide motor  28  is transmitted to the actuating mechanism  5 , the door panel  2   b  is slid toward the full-open position. At this time, the control circuit apparatus  8  detects the position of the door panel  2   b  on the basis of the position detection signal input from the position detecting apparatus  24 . Further, if it is detected that the door panel  2   b  is arranged at the full-open position, the control circuit apparatus  8  outputs a drive signal for stopping the door panel  2   b  to the slide motor  28  so as to stop the slide motor  28 . 
   If the close signal is input from the operating switch  31 , the control circuit apparatus  8  outputs a drive signal for closing the door panel  2   b  to the slide motor  28  so as to drive the slide motor  28  in a direction of closing the door panel  2   b . At the same time, the control circuit apparatus  8  drives the foreign material detecting sensor  41 . Further, when the driving force of the slide motor  28  is transmitted to the actuating mechanism  5 , the door panel  2   b  is slid toward the full-close position. 
   At this time, if the current detection signal is input from the current detecting element  46 , the control circuit apparatus  8  determines that a foreign material is wedged between the door panel  2   b  and the vehicle body  2   a , on the basis of the input of the current detection signal. In other words, the control circuit apparatus  8  determines that a foreign material exists between the door panel  2   b  and the vehicle body  2   a . Further, at this time, the control circuit apparatus  8  detects the amount of slide of the door panel  2   b , that is, the position of the door panel  2   b  on the basis of the position detection signal input from the position detecting apparatus  24 , and determines the threshold value on the basis of the detected position of the door panel  2   b . In detail, as shown in  FIG. 8 , in the case that the door panel  2   b  moves within the first moving range A 1 , the control circuit apparatus  8  sets the threshold value to a fixed value. 
   If the control circuit apparatus  8  detects, on the basis of the position detection signal, that the door panel  2   b  is arranged at the first door position P 1 , the control circuit apparatus  8  changes the change rate of the threshold value. Further, in the case that the door panel  2   b  moves within the second moving range A 2 , the control circuit apparatus  8  linearly enlarges the threshold value as the door panel  2   b  comes close to the full-close position Pc, at the change rate changed at a time when the door panel  2   b  is arranged at the first door position P 1 . 
   If the control circuit apparatus  8  detects, on the basis of the position detection signal, that the door panel  2   b  is arranged at the second door position P 2 , the control circuit apparatus  8  changes the change rate of the threshold value. Further, in the case that the door panel  2   b  moves within the third moving range A 3 , the control circuit apparatus  8  linearly enlarges the threshold value as the door panel  2   b  comes close to the full-close position Pc, at the change rate changed at a time when the door panel  2   b  is arranged at the second door position P 2 . 
   Even in the case that the door panel  2   b  moves within any one of the first to third moving ranges A 1  to A 3 , the control circuit apparatus  8  compares the change rate of the electrostatic capacity detected on the basis of the electrostatic capacity detection signal input from the electrostatic capacity detecting apparatus  45  with the threshold value. Further, in the case that the detected amount of change of the electrostatic capacity is larger than the threshold value, the control apparatus  8  determines that a foreign material exists between the door panel  2   b  and the vehicle body  2   a . In the case that the door panel  2   b  moves within the fourth moving range A 4 , the control circuit apparatus  8  invalidates the electrostatic capacity detection signal input from the electrostatic capacity detecting apparatus  45 . Further, the control circuit apparatus  8  validates only the current detection signal input from the current detecting element  46  and judges whether or not a foreign material exists between the door panel  2   b  and the vehicle body  2   a.    
   Even in the case that the door panel  2   b  moves within any one of the first to fourth moving ranges A 1  to A 4 , if the control circuit apparatus  8  determines that a foreign material exists between the door panel  2   b  and the vehicle body  2   a , the control circuit apparatus  8  outputs a drive signal for moving the door panel  2   b  to the full-open position Po to the slide motor  28 . If the drive signal is input, the slide motor  28  is driven in the direction of leaving open the door panel  2   b , and the door panel  2   b  is slid to the full-open position Po. 
   In the case that it is determined that no foreign material exists between the door panel  2   b  and the vehicle body  2   a , the control circuit apparatus  8  drives the slide motor  28  until the door panel  2   b  is arranged at the full-close position Pc. Further, if a half latch detection signal is input from the half latch detecting portion, the control circuit apparatus  8  outputs the drive signal to the closure motor  29 . If the drive signal is input, the closure motor  29  actuates the lock mechanism, and moves the door panel  2   b  to a position where the lock can be executed by the lock mechanism. Further, if the control circuit apparatus  8  detects, on the basis of the position detection signal, that the door panel  2   b  is arranged at the full-close position Pc, the control circuit apparatus  8  outputs a drive signal for stopping the drive to the slide motor  28  and the closure motor  29  so as to stop the slide motor  28  and the closure motor  29 . 
   As mentioned above, the present embodiment has the following operations and advantages. 
   (1) When the control circuit apparatus  8  detects that the door panel  2   b  is arranged at the first door position P 1 , and that the door panel  2   b  is arranged at the second door position P 2  on the basis of the position detection signal, the control circuit apparatus  8  changes the change rate of the threshold value. In other words, the control circuit apparatus  8  changes the threshold value in accordance with the movement of the door panel  2   b  after the door panel  2   b  is arranged at the first door position P 1 . As mentioned above, since the threshold value is changed in accordance with the movement of the door panel  2   b , it is possible to finely set a sensitivity for detecting a foreign material existing between the door panel  2   b  and the vehicle body  2   a , in correspondence to the distance between the front end of the door panel  2   b  and the vehicle body  2   a  (the rear end of the door panel  2   c , the center pillar  2   d  or the like). As a result, even if the electrostatic capacity is changed between the vehicle body  2   a  and the sensor electrode  53  during the closing motion of the door panel  2   b , the change rate of the threshold value is changed in correspondence to the position of the door panel  2   b , whereby it is possible to prevent the control circuit apparatus  8  from determining the center pillar  2   d  and the door panel  2   c  as foreign materials. In other words, even in the case that the door panel  2   b  moves in the region (the second moving region A 2  and the third moving region A 3 ) at which the electrostatic capacity is changed between the center pillar  2   d  and the door panel  2   c , and the sensor electrode  53 , during the closing motion of the door panel  2   b , it is possible to detect a foreign material existing between the door panel  2   b  and the vehicle body  2   a  in a non-contact manner. Accordingly, it is possible to widen the range at which a foreign material between the door panel  2   b  and the vehicle body  2   a  can be detected in a non-contact manner within the moving range of the door panel  2   b.    
   (2) The vehicle body  2   a  and the door panel  2   b  have various shapes in correspondence to vehicle types. Accordingly, since the front end of the door panel  2   b  comes close to the center pillar  2   d  and the door panel  2   c  during the closing motion of the door panel  2   b , the position of the door panel  2   b  at which the electrostatic capacity starts changing between the center pillar  2   d  and the door panel  2   c , and the sensor electrode  53  is subtly different in accordance with the vehicle types. Further, a change way of the electrostatic capacity in accordance with the movement of the door panel  2   b  is different in accordance with the vehicle types, between the center pillar  2   d  and the door panel  2   c , and the sensor electrode  53 . In the meanwhile, in accordance with the present embodiment, if the door panel  2   b  comes close to the full-close position Pc during the closing motion of the door panel  2   b , the amount of change of the electrostatic capacity in the sensor electrode  53  is enlarged by the movement of the door panel  2   b  closer to the center pillar  2   d  and the door panel  2   c . Further, if the control circuit apparatus  8  detects that the door panel  2   b  is arranged at the first door position P 1  corresponding to the position of the door panel  2   b  at which the amount of change of the electrostatic capacity in the sensor electrode  53  starts increasing, on the basis of the movement of the front end of the door panel  2   b  close to the center pillar  2   d , the control circuit apparatus  8  changes the change rate of the threshold value. Further, if the control circuit apparatus  8  detects that the door panel  2   b  is arranged at the second door position P 2  corresponding to the position of the door panel  2   b  at which the amount of change of the electrostatic capacity in the sensor electrode  53  starts further increasing, on the basis of the movement of the front end of the door panel  2   b  close to the door panel  2   c , the control circuit apparatus  8  changes the change rate of the threshold value. As mentioned above, since the control circuit apparatus  8  changes the change rated of the threshold value in correspondence to the distance between the center pillar  2   d  and the door panel  2   c , and the door panel  2   b  mainly affecting the amount of change of the electrostatic capacity in the sensor electrode  53 , it is possible to prevent the existence of a foreign material from being erroneously detected in correspondence to the vehicle body  2   a  and the door panel  2   b.    
   (3) After the door panel  2   b  is arranged at the first door position P 1 , the control circuit apparatus  8  changes the change rate of the threshold value in correspondence to the position of the door panel  2   b . Accordingly, it is possible to easily change the threshold value in accordance with the movement of the door panel  2   b.    
   (4) When the control circuit apparatus  8  detects that the door panel  2   b  is arranged at the first door position P 1 , and that the door panel  2   b  is arranged at the second door position P 2  on the basis of the position detection signal, the control circuit apparatus  8  changes the change rate of the threshold value. Accordingly, it is possible to set the threshold value to the value in correspondence to the change of the electrostatic capacity in accordance with the movement of the door panel  2   b  between the center pillar  2   d  and the door panel  2   c , and the sensor electrode  53 , in comparison with the case that the change rate of the threshold value is changed only one time during the period when the door panel  2   b  reaches the full-close position Pc from the first door position P 1 . Accordingly, it is possible to reduce a dispersion of the sensitivity for detecting a foreign material between the door panel  2   b  and the vehicle body  2   a . Further, since the control circuit apparatus  8  executes the change of the change ratio of the threshold value only two times, it is possible to simplify the control executed by the control circuit apparatus  8  in comparison with the case that the change rate of the threshold value is changed three times or more. 
   (5) The control circuit apparatus  8  changes the change rate of the threshold value in such a manner that the change rate of the threshold value becomes larger as the door panel  2   b  comes close to the full-close position Pc. In general, in the case that the door panel  2   b  is moved toward the full-close position Pc from the full-open position Po, if the door panel  2   b  reaches the predetermined position, the amount of change of the electrostatic capacity between the vehicle body  2   a  and the sensor electrode  53  is thereafter enlarged in such a curved manner that the change rate is enlarged step by step, as the door panel  2   b  comes close to the full-close position Pc. Accordingly, if the change rate of the threshold value is changed in such a manner that the value becomes larger as the door panel  2   b  comes close to the full-close position Pc, it is possible to set the threshold value to the value corresponding to the amount of change of the electrostatic capacity changing in accordance with the movement of the door panel  2   b  between the vehicle body  2   a  and the sensor electrode  53 . As a result, it is possible to further reduce the dispersion of the sensitivity for detecting a foreign material between the door panel  2   b  and the vehicle body  2   a.    
   (6) The change rate of the threshold value is set in correspondence to the amount of change (refer to  FIG. 7 ) of the electrostatic capacity actually detected by the sensor electrode  53  previously in the state in which no foreign material exists between the door panel  2   b  and the vehicle body  2   a  at a time of the closing motion of the door panel  2   b . Accordingly, it is possible to more reliably set the threshold value in correspondence to the shape of the front end of the door panel  2   b  and the shape of the vehicle body  2   a.    
   (7) The sensor main body  44  is provided in the front end of the door panel  2   b , that is, the end portion positioned in the front side in the forward moving direction of the door panel  2   b  at a time of the closing motion. Accordingly, in the case that a foreign material exists at the position closer to the front end of the door panel  2   b  during the closing motion between the front end of the door panel  2   b  and the rear end of the door panel  2   c , it is possible to more early detect the existence of a foreign material, for example, than the case that the sensor main body  44  is provided in the rear end of the door panel  2   c.    
   The embodiment in accordance with the present invention may be changed as follows. 
   In the embodiment mentioned above, the sensor main body  44  is arranged in the front end of the door panel  2   b  of the motor-driven slide door apparatus  1 . However, the sensor main body  44  may be fixed to the peripheral edge of the door opening  9  facing the front end of the door panel  2   b , that is, the rear end of the door panel  2   c.    
   Further, the sensor main body  44  may be provided in a flip-up backdoor  123  provided in a rear portion of a vehicle body  122  of a vehicle  121 , as shown in  FIG. 9 . In detail, a sensor main body  44  is fixed to each of both end portions of the backdoor  123  in the width of the vehicle. Each sensor main body  44  faces a peripheral edge of an opening portion  122   a  provided in the vehicle body. Even in this case, since the control circuit apparatus  8  changes the threshold value in correspondence to the position of the backdoor  123 , it is possible to obtain the same operations and advantages as those of the embodiment mentioned above. Further, in the vehicle  121  shown in  FIG. 9 , the sensor main body  44  may be fixed to a peripheral edge of the opening portion  122   a  facing the backdoor  123 , or may be fixed to the peripheral edge of the opening portion  122   a  facing a damper  124  for opening and closing the backdoor  123 . The sensor main body  44  may be fixed to a peripheral edge of a trunk positioned in a front side in a forward moving direction at a time of the closing motion, in a door of the trunk opened and closed by an electric motor, or may be fixed to a peripheral edge of an opening portion of the vehicle body opened and closed by the door of the trunk. 
   In the embodiment mentioned above, the control circuit apparatus  8  changes the change rate of the threshold value in such a manner that the change rate of the threshold value becomes larger as the door panel  2   b  comes close to the full-close position Pc. However, the control circuit apparatus  8  may change the change rate of the threshold value in correspondence to the position of the door panel  2   b , for example, in such a manner as to alternately repeat the moving range in which the change rate of the threshold value is set in such a manner that the threshold value becomes larger step by step in accordance with the movement of the door panel  2   b  to the full-close position Pc, and the moving range in which the change rate of the threshold value is set to 0. 
   In the embodiment mentioned above, when the control circuit apparatus  8  detects that the door panel  2   b  is arranged at the first door position P 1 , and that the door panel  2   b  is arranged at the second door position P 2  on the basis of the position detection signal, the control circuit apparatus  8  changes the change rate of the threshold value. However, the control circuit apparatus  8  may change the change rate of the threshold value only at a time of detecting that the door panel  2   b  is arranged at the first door position P 1 . In accordance with this structure, it is possible to make the control executed by the control circuit apparatus  8  more simple in comparison with the case that the change of the change rate of the threshold value is executed two times. 
   The control circuit apparatus  8  may change the change rate of the threshold value three times or more after detecting that the door panel  2   b  is arranged at the first door position P 1 . In accordance with this structure, it is possible to set the threshold value to the value corresponding to the amount of change of the electrostatic capacity between the vehicle body  2   a  (the door panel  2   c  and the center pillar  2   d  or the like) and the sensor electrode  53  in accordance with the movement of the door panel  2   b , in comparison with the case that the change rate of the threshold value is changed two times during the period when the door panel  2   b  reaches the full-close position Pc from the first door position P 1 . Accordingly, it is possible to reduce the dispersion of the sensitivity for detecting a foreign material between the door panel  2   b  and the vehicle body  2   a.    
   The control circuit apparatus  8  may continuously change the change rate of the threshold value as the door panel  2   b  comes close to the full-close position Pc, after detecting that the door panel  2   b  is arranged at the first door position P 1 . In this case, the threshold value is changed in a curved manner, after the door panel  2   b  is arranged at the first door position P 1 . As mentioned above, if the change rate of the threshold value is continuously changed by the control circuit apparatus  8 , it is possible to set the threshold value to the value corresponding to the amount of change of the electrostatic capacity between the vehicle body  2   a  and the sensor electrode  53  in accordance with the movement of the door panel  2   b , in comparison with the case that the change rate is changed a number of times during the period when the door panel  2   b  reaches the full-close position Pc from the first door position P 1 . Therefore, it is possible to further lower the dispersion of the sensitivity for detecting a foreign material between the door panel  2   b  and the vehicle body  2   a.    
   In the embodiment mentioned above, the control circuit apparatus  8  detects the amount of change of the electrostatic capacity in the sensor electrode  53  on the basis of the electrostatic capacity detection signal. However, the control circuit apparatus  8  may detect the electrostatic capacity (the detected value) in the sensor electrode  53  on the basis of the electrostatic-capacity detection signal. In this case, the control circuit apparatus  8  changes the change rate of the threshold value in correspondence to the position of the door panel  2   b  during the closing motion, and the electrostatic capacity actually detected by the sensor electrode  53 , in the case that no foreign material lies between the door panel  2   b  and the vehicle body  2   a . In this structure, it is possible to obtain the same operations and advantages as those of the embodiment mentioned above. 
   In the embodiment mentioned above, when the control circuit apparatus  8  detects, on the basis of the position detection signal, that the door panel  2   b  is arranged at the first door position P 1 , the control circuit apparatus  8  changes the change rate of the threshold value, thereby continuously changing the threshold value in accordance with the movement of the door panel  2   b . However, the control circuit apparatus  8  may change the threshold value in stages in correspondence to the position of the door panel  2   b , as shown in  FIG. 10 . In an example shown in  FIG. 10 , if the control circuit apparatus  8  detects, on the basis of the position detection signal, that the door panel  2   b  is arranged at the first door position P 1 , at a time of the closing motion of the door panel  2   b , the control circuit apparatus  8  changes the threshold value to a larger value than the threshold value in the first moving range A 1 . Further, in the case that the door panel  2   b  moves within the second moving range A 2 , the control circuit apparatus  8  judges on the basis of the threshold value changed at a time when the door panel  2   b  is arranged at the first door position P 1  whether or not a foreign material exists between the door panel  2   b  and the vehicle body  2   a . The control circuit apparatus  8  detects, on the basis of the position detection signal, that the door panel  2   b  is arranged at the second door position P 2 , the control circuit apparatus  8  changes the threshold value to the value larger than the threshold value in the second moving range A 2 . Further, in the case that the door panel  2   b  moves within the third moving range A 3 , the control circuit apparatus  8  judges whether or not foreign material exists between the door panel  2   b  and the vehicle body  2   a , by using the threshold value changed at a time when the door panel  2   b  is arranged at the second door position P 2 . 
   In the case that the center pillar  2   d  is arranged in a rear side of the vehicle than the rear end of the door panel  2   c , the control circuit apparatus  8  may change the threshold value in stages in correspondence to the position of the door panel  2   b , as shown in  FIG. 11 . In an example shown in FIG.  11 , if the control circuit apparatus  8  detects that the door panel  2   b  is arranged, at a fifth door position P 5  set between the full-open position Po and the full-close position Pc, a sixth door position P 6  set between the fifth door position P 5  and the full-close position Pc, and a seventh door position P 7  set between the sixth door position P 6  and the full-close position Pc, the control circuit apparatus  8  changes the threshold value. 
   The fifth door position P 5  corresponds to a position at which the electrostatic capacity starts increasing between the sensor electrode  53  and the center pillar  2   d  on the basis of the movement of the front end of the door panel close to the center pillar  2   d , that is, a position of the door panel  2   b  at which the amount of change of the electrostatic capacity in the sensor electrode  53  starts increasing. The sixth door position P 6  corresponds to a position at which the electrostatic capacity between the sensor electrode  53  and the center pillar  2   d  starts reducing on the basis of the movement of the front end of the door panel  2   b  away from the center pillar  2   d . The seventh door position P 7  corresponds to a position at which the electrostatic capacity starts increasing between the sensor electrode  53  and the door panel  2   c  on the basis of the movement of the front end of the door panel  2   b  close to the door panel  2   c , that is, a position of the door panel  2   b  at which the amount of change of the electrostatic capacity in the sensor electrode  53  starts increasing. In  FIG. 11 , a range from the full-open position Po to the fifth door position P 5  is set to a fifth moving range A 5 , and a range from the fifth door position P 5  to the sixth door position P 6  is set to a sixth moving range A 6 . Further, a range from the sixth door position P 6  to the seventh door position P 7  is set to a seventh moving range A 7 , and a range from the seventh door position P 7  to the same third door position P 3  as that of the embodiment mentioned above is set to an eighth moving range A 8 . 
   If the control circuit apparatus  8  detects, on the basis of the position detection signal, that the door panel  2   b  is arranged at the fifth door position P 5 , at a time of the closing motion of the door panel  2   b , the control circuit apparatus  8  changes the threshold value to a larger value than the threshold value in the fifth moving range A 5 . Further, in the case that the door panel  2   b  moves within the sixth moving range A 6 , the control circuit apparatus  8  compares the threshold value changed at a time when the door panel  2   b  is arranged at the fifth door position P 5 , with the amount of change of the electrostatic capacity detected on the basis of the electrostatic detection signal, and judges on the basis of the result of comparison whether or not a foreign material exists between the door panel  2   b  and the vehicle body  2   a.    
   If the control circuit apparatus  8  detects, on the basis of the position detection signal, that the door panel  2   b  is arranged at the sixth door position P 6 , the control circuit apparatus  8  changes the threshold value to a value smaller than the threshold value in the sixth moving range A 6 , and larger than the threshold value in the fifth moving range A 5 . The threshold value is changed as mentioned above, because the sensor electrode  53  moves away from the center pillar  2   d  and the amount of change of the electrostatic capacity starts reducing in the sensor electrode  53 , if the door panel  2   b  passes the sixth door position P 6 . In the case that the door panel  2   b  moves within the seventh moving range A 7 , the control circuit apparatus  8  compares the threshold value changed at a time when the door panel  2   b  is arranged at the sixth door position P 6 , with the amount of change of the electrostatic capacity detected on the basis of the electrostatic capacity detection signal, and judges on the basis of the result of comparison whether or not a foreign material exists between the door panel  2   b  and the vehicle body  2   a.    
   If the control circuit apparatus  8  detects that the door panel  2   b  is arranged at the seventh door position P 7  on the basis of the position detection signal, the control circuit apparatus  8  changes the threshold value to the larger value than the threshold value in the sixth moving range A 6 . As mentioned above, the threshold value is changed because the amount of change of the electrostatic capacity in the sensor electrode  53  starts increasing on the basis of the movement of the sensor electrode  53  close to the door panel  2   c , in the case that the door panel  2   b  passes the seventh door position P 7 . In the case that the door panel  2   b  moves within the eighth moving range A 8 , the control circuit apparatus  8  compares the threshold value changed at a time when the door panel  2   b  is arranged at the seventh position P 7 , with the amount of change of the electrostatic capacity detected on the basis of the electrostatic capacity detection signal, and judges on the basis of the result of comparison whether or not a foreign material exists between the door panel  2   b  and the vehicle body  2   a.    
   As in the examples shown in  FIGS. 10 and 11 , if the control circuit apparatus  8  is structured such that the threshold value is changed in stages on the basis of the position detection signal, it is easy to set the threshold value changed by the control circuit apparatus  8 , in comparison with the case that the threshold value is linearly and continuously changed such as the embodiment mentioned above, and the case that the threshold value is continuously changed in a curved manner. If the threshold value is changed a number of times as shown in  FIG. 11 , it is possible to set the threshold value to the value corresponding to the amount of change of the electrostatic capacity between the vehicle body  2   a  and the sensor electrode  53  in accordance with the movement of the door panel  2   b , in comparison with the case that the threshold value is changed only one time during the period when the door panel  2   b  reaches the full-close position Pc from the fifth door position P 5 . Accordingly, it is possible to further lower the dispersion of the sensitivity for detecting a foreign material between the door panel  2   b  and the vehicle body  2   a . On the other hand, if the threshold value is changed as shown in  FIG. 10 , the control circuit apparatus  8  executes the change of the threshold value only two times. Accordingly, it is possible to simplify the control executed by the control circuit apparatus  8  in comparison with the case that the threshold value is changed three times or more.