Patent Publication Number: US-2020302707-A1

Title: Input operation detector

Description:
BACKGROUND 
     1. Field 
     The present description relates to an input operation detector. 
     2. Description of Related Art 
     An input operation detector includes an operation detection electrode of which capacitance changes when a detection subject, such as the hand of a user, approaches the operation detection electrode. Japanese Laid-Open Patent Publication No. 2014-122542 describes an example of such an operation detection electrode installed in a vehicle door at the inner side of a window portion, specifically, near the lower frame of the window portion. A user intuitively performs an input operation by bringing his or her hand or the like near the door, which is an operation object, to unlock the door or to open or close the door. 
     However, the above operation detection electrode of which capacitance changes when a detection subject approaches may react to water collected on the outer surface of the vehicle. In many cases, a window portion of a vehicle has a recess into which water collected on the outer surface of the vehicle easily flows. Thus, with the structure of the related art, if the vehicle is wet, the water collected on the outer surface of the vehicle may cause erroneous determination. 
     SUMMARY 
     It is an objective of the present disclosure to provide an input operation detector that prevents erroneous determination and detects an input operation with good accuracy when a vehicle is in a wet state. 
     This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter. 
     In one general aspect, an input operation detector is provided. The input operation detector includes an operation detection electrode configured to detect an input operation from a capacitance change resulting from an approaching detection subject and a wetting detection electrode arranged next to the operation detection electrode. Water from an outer surface of a vehicle, when the vehicle is wet, collects at a location referred to as a water collection portion, and the wetting detection electrode is closer to the water collection portion than the operation detection electrode. If the water collection portion does not include water, the operation detection electrode has a greater capacitance change sensitivity than the wetting detection electrode to the approach of the detection subject. If the water collection portion includes water, the wetting detection electrode has a greater capacitance change sensitivity than the operation detection electrode to the water in the water collection portion. 
     In another general aspect, an input operation detector is provided. The input operation detector includes an operation detection electrode having a capacitance that changes when a detection subject approaches the operation detection electrode and a wetting detection electrode arranged next to the operation detection electrode. Water on an outer surface of a vehicle, when the vehicle is wet, collects at a location referred to as a water collection portion, and the wetting detection electrode has a capacitance that changes when the water collection portion includes water. The wetting detection electrode is closer to a metal component of the vehicle than the operation detection electrode and thereby has a tendency to be electrically coupled to the metal component more easily than the operation detection electrode so that if the water collection portion does not include water, a degree of change in the capacitance of the operation detection electrode when the detection subject approaches the operation detection electrode and the wetting detection electrode is greater than a degree of change in the capacitance of the wetting detection electrode when the detection subject approaches the operation detection electrode and the wetting detection electrode. The wetting detection electrode is closer to the water collection portion than the operation detection electrode so that a degree of change in the capacitance of the wetting detection electrode when the water collection portion includes water is greater than a degree of change in the capacitance of the operation detection electrode when the water collection portion includes water. 
     Other features and aspects will be apparent from the following detailed description, the drawings, and the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a vehicle in which an input operation detector is installed. 
         FIG. 2  is a block diagram illustrating a schematic configuration of the input operation detector. 
         FIG. 3  is a perspective view of an operation detection unit of the input operation detector. 
         FIG. 4  is a cross-sectional view of a sliding door taken in the vicinity of a window portion where the operation detection unit is arranged. 
         FIG. 5  is a graph showing an example of a capacitance change caused in each operation detection electrode when an input operation is performed. 
         FIG. 6  is a flowchart showing a procedure for determining detection of an input operation. 
         FIG. 7  is a flowchart showing a procedure for determining detection of an input operation. 
         FIG. 8  is a diagram illustrating a state where the lower frame of a window portion includes water. 
         FIG. 9A  is a diagram illustrating a capacitance change that occurs in an operation detection electrode and a wetting detection electrode when an input operation is performed. 
         FIG. 9B  is a diagram illustrating a capacitance change that occurs in the operation detection electrode and the wetting detection electrode when a vehicle is wet. 
         FIG. 10  is a flowchart showing a procedure for performing wetting determination on the basis of a capacitance change, determination of whether an input operation has been input, and capacitance correction. 
     
    
    
     Throughout the drawings and the detailed description, the same reference numerals refer to the same elements. The drawings may not be to scale, and the relative size, proportions, and depiction of elements in the drawings may be exaggerated for clarity, illustration, and convenience. 
     DETAILED DESCRIPTION 
     This description provides a comprehensive understanding of the methods, apparatuses, and/or systems described. Modifications and equivalents of the methods, apparatuses, and/or systems described are apparent to one of ordinary skill in the art. Sequences of operations are exemplary, and may be changed as apparent to one of ordinary skill in the art, with the exception of operations necessarily occurring in a certain order. Descriptions of functions and constructions that are well known to one of ordinary skill in the art may be omitted. 
     Exemplary embodiments may have different forms, and are not limited to the examples described. However, the examples described are thorough and complete, and convey the full scope of the disclosure to one of ordinary skill in the art. 
     An input operation detector  21  according to one embodiment that is installed in a sliding door  5  of a vehicle  1  will now be described with reference to the drawings. 
     As shown in  FIG. 1 , the vehicle  1  according to the present embodiment includes the sliding door  5  that opens and closes a door opening  3  in one side of a vehicle body  2 . The sliding door  5  of the vehicle  1  of the present embodiment has the structure of a rear door that opens toward the rear. In other words, the sliding door  5  is moved toward the rear of the vehicle (rightward in  FIG. 1 ) to open and moved toward the front of the vehicle (leftward in  FIG. 1 ) to close. The vehicle  1  of the present embodiment includes a door locking device  6  that drives a latch mechanism (not shown) to lock the sliding door  5  in a fully closed state and unlock the sliding door  5 . The vehicle  1  also includes an opening/closing driving device  7  that uses a motor (not shown) as a drive source to open and close the sliding door  5 . The vehicle  1  of the present embodiment drives the motor to open and close the sliding door  5 . 
     Specifically, as shown in  FIG. 2 , the vehicle  1  of the present embodiment includes a door electronic control unit (ECU)  10  of that controls actuation of the door locking device  6  and the opening/closing driving device  7 . The door ECU  10  also receives an input operation signal Scr indicating that an input operation unit arranged on, for example, the sliding door  5 , a portable device (not shown), or the like held by the user, has been operated. The door ECU  10  of the present embodiment is configured to control actuation of the door locking device  6  and the opening/closing driving device  7  in response to an actuation request indicated by the input operation signal Scr. 
     Specifically, the door ECU  10  of the present embodiment controls the door locking device  6  upon detection of a lock request or an unlock request in the input operation signal Scr under the condition that the portable device meets electronic key security requirements. This locks the sliding door  5  in the fully closed state in accordance with the lock request and unlocks the sliding door  5  in accordance with the unlock request. 
     The door ECU  10  according to present embodiment also controls actuation of the opening/closing driving device  7  on condition that the sliding door  5  is in an unlocked state or shifting of the sliding door  5  to the unlocked state by actuation of the door locking device  6  is permitted. This opens the sliding door  5  in accordance with an opening actuation request indicated in the input operation signal Scr and closes the sliding door  5  in accordance with a closing actuation request. 
     As shown in  FIGS. 1 and 2 , in the vehicle  1  of the present embodiment, the sliding door  5  includes an operation detection unit  15 . An output signal of the operation detection unit  15  changes when a detection subject, for example, approaches the operation detection unit  15 . The detection subject may be the hand or the like of the user. Specifically, the operation detection unit  15  in the present embodiment includes three operation detection electrodes  20  of which capacitance changes when the detection subject approaches. Further, in the vehicle  1  of the present embodiment, an output signal of the operation detection unit  15  is also input to the door ECU  10 . Accordingly, an input operation detector  21  that detects an input operation to the sliding door  5  in a non-contact state is configured in the vehicle  1  of the present embodiment. 
     As shown in  FIGS. 2 and 3 , the operation detection unit  15  of the present embodiment includes the three operation detection electrodes  20 . More specifically, the operation detection unit  15  of the present embodiment includes a first electrode  20   a , a second electrode  20   b , and a third electrode  20   c . In the operation detection unit  15  of the present embodiment, the first electrode  20   a , the second electrode  20   b , and the third electrode  20   c  have substantially the same shape and the form of a substantially rectangular flat plate. The operation detection unit  15  includes a substantially rectangular board  22 . The capacitance of one of the operation detection electrodes  20  will be referred to as capacitance Cx. The capacitance of the first electrode  20   a , the capacitance of the second electrode  20   b , and the capacitance of the third electrode  20   c  will respectively be referred to as capacitance C 1 , capacitance C 2 , and capacitance C 3 . A detection circuit  23  is mounted on the board  22  to separately detect capacitance C 1 , capacitance C 2 , and capacitance C 3 . In the operation detection unit  15  of the present embodiment, a substantially rectangular parallelepiped housing  25  accommodates the first electrode  20   a , the second electrode  20   b , and the third electrode  20   c  integrally with the board  22  and the detection circuit  23 . 
     Specifically, as shown in  FIG. 3 , in the operation detection unit  15  of the present embodiment, the detection circuit  23  is mounted on one longitudinal end of the board  22 . Further, the first electrode  20   a , the second electrode  20   b , and the third electrode  20   c  are substantially parallel to the board  22  and opposed to a mounting surface  22   a  of the board  22  on which the detection circuit  23  is arranged. The first electrode  20   a , the second electrode  20   b , and the third electrode  20   c  are extended and lined in the longitudinal direction of the housing  25  at positions that are not overlapped with the detection circuit  23 . Accordingly, the operation detection unit  15  of the present embodiment configures three detection areas that are opposed to the mounting surface  22   a  of the board  22  and correspond to the first electrode  20   a , the second electrode  20   b , and the third electrode  20   c.    
     More specifically, as shown in  FIGS. 1 and 4 , the vehicle  1  of the present embodiment includes the operation detection unit  15  installed at the inner side of a window portion  30  installed in the sliding door  5 . In other words, the operation detection unit  15  is arranged in the vicinity of a lower frame  30   b  of the window portion  30  and extended along the lower frame  30   b  that extends in the front-rear direction of the vehicle. That is, the operation detection unit  15  is arranged near the lower frame  30   b  of the window portion  30  and extended in the direction of the opening and closing actuation of the sliding door  5 . Accordingly, in the operation detection unit  15  of the present embodiment, the first electrode  20   a , the second electrode  20   b , and the third electrode  20   c  are arranged in this order from the front toward the rear of the vehicle. The operation detection unit  15  is fixed to an inner panel  31  of the sliding door  5 . The operation detection unit  15  is arranged upward from the lower frame  30   b  of the window portion  30  so that the mounting surface  22   a  of the board  22 , where the first electrode  20   a , the second electrode  20   b , and the third electrode  20   c  are arranged, is directed toward the outer side of the vehicle  1  (leftward in  FIG. 4 ). Thus, the vehicle  1  of the present embodiment allows the user to view the operation detection unit  15  from the outer side of the window portion  30 . 
     As shown in  FIG. 4 , in the vehicle  1  of the present embodiment, the lower frame  30   b  of the window portion  30  is formed by sandwiching a glass  33  between the inner panel  31  and an outer panel  32  of the sliding door  5 . The operation detection unit  15  includes a surface directed toward the passenger compartment and covered by a door panel trim  34  fixed to the inner panel  31 . The surface of the operation detection unit  15  directed toward the passenger compartment is directed rightward in  FIG. 4 . The operation detection unit  15  of the present embodiment includes a shielded electrode  35  that is covered by the door panel trim  34  and opposed to a rear surface  22   b  of the board  22 . The shielded electrode  35  is shielded from the effect a detection subject located in the passenger compartment such as an occupant of the vehicle  1 . 
     As shown in  FIGS. 1 and 2 , with the input operation detector  21  of the present embodiment, capacitance Cx of the operation detection electrode  20  included in the operation detection unit  15 , specifically, capacitance C 1  of the first electrode  20   a , capacitance C 2  of the second electrode  20   b , and capacitance C 3  of the third electrode  20   c  change when a detection subject X (such as hand) approaches the operation detection unit  15  from the outer side of the window portion  30 . An operation detection signal indicating capacitance Cx of one of the operation detection electrodes  20  will be referred to as an operation detection signal Sx. An operation detection signal indicating capacitance C 1  of the first electrode  20   a  will be referred to as a first operation signal S 1 . An operation detection signal indicating capacitance C 2  of the second electrode  20   b  will be referred to as a second operation signal S 2 . An operation detection signal indicating capacitance C 3  of the third electrode  20   c  will be referred to as a third operation signal S 3 . The operation detection unit  15  outputs the first operation signal S 1 , the second operation signal S 2 , and the third operation signal S 3  to the door ECU  10 . The input operation detector  21  of the present embodiment is configured so that the door ECU  10  detects an input operation to the sliding door  5  from the first operation signal S 1 , the second operation signal S 2 , and the third operation signal S 3 . 
     Specifically, the door ECU  10  of the present embodiment compares a preset threshold value Cth with capacitance C 1  of the first electrode  20   a  indicated by the first operation signal S 1 , capacitance C 2  of the second electrode  20   b  indicated by the second operation signal S 2 , and capacitance C 3  of the third electrode  20   c  indicated by the third operation signal S 3 , all of which are input from the operation detection unit  15 . Further, if capacitance Cx of the operation detection electrode  20  indicated by the operation detection signal Sx exceeds the threshold value Cth, the door ECU  10  compares the characteristics of the capacitance change with a preset input operation pattern to determine how the user performed an input operation. 
     As shown in  FIG. 5 , if the hand brought near the operation detection unit  15  is moved from the front toward the rear of the vehicle, the peak in the capacitance change exceeding the threshold value Cth changes in the order of capacitance C 1  indicated by the first operation signal S 1 , capacitance C 2  indicated by the second operation signal S 2 , and capacitance C 3  indicated by the third operation signal S 3 , namely, in the order of the first electrode  20   a , the second electrode  20   b , and the third electrode  20   c . In other words, a peak in the capacitance change at the first electrode  20   a , a peak in the capacitance change at the second electrode  20   b , and a peak in the capacitance change at the third electrode  20   c  sequentially appear. In the input operation detector  21  of the present embodiment, such an input operation pattern in which the detection subject X is moved from the front toward the rear of the vehicle, specifically, in the opening direction of the sliding door  5  is set as an input operation requesting the sliding door  5  to open. 
     Specifically, as shown by the flowchart in  FIG. 6 , the door ECU  10  of the present embodiment determines whether a peak in a capacitance change exceeding the threshold value Cth has shifted in the order of capacitance C 1  indicated by the first operation signal S 1 , capacitance C 2  indicated by the second operation signal S 2 , and capacitance C 3  indicated by the third operation signal S 3  (step  101 ). If the door ECU  10  detects such characteristics in a capacitance change (step  101 : YES), the door ECU  10  controls actuation of the opening/closing driving device  7  to open the sliding door  5  (step  102 ). 
     The door ECU  10  also determines whether a peak in a capacitance change exceeding the threshold value Cth has shifted in the order of capacitance C 3  indicated by the third operation signal S 3 , capacitance C 2  indicated by the second operation signal S 2 , and capacitance C 1  indicated by the first operation signal S 1  (step  103 ). In other words, the characteristics of such a capacitance change will be detected if the hand brought near the operation detection unit  15  is moved from the rear toward the front of the vehicle, specifically, in the closing direction of the sliding door  5 . If the door ECU  10  of the present embodiment detects the characteristics of such a capacitance change (step  103 : YES), the door ECU  10  controls actuation of the opening/closing driving device  7  to close the sliding door  5  (step  104 ). 
     In the input operation detector  21 , a hand-holding operation in which the detection subject X, such as the hand, approaches the operation detection unit  15  from the outer side the vehicle widthwise direction is also set as an input operation pattern. In the operation detection unit  15  of the present embodiment, a longitudinally central portion where the second electrode  20   b  is arranged is set as an operation position where the hand-holding operation is performed. The door ECU  10  of the present embodiment is configured to open or close the sliding door  5  in accordance with the position of the sliding door  5  if the characteristics in capacitance change indicated by the operation detection signal Sx correspond to the input operation pattern of a hand-holding operation. 
     Specifically, as shown by the flowchart of  FIG. 7 , the door ECU  10  of the present embodiment determines whether capacitance C 2  of the second electrode  20   b  indicated by the second operation signal S 2  has exceeded the preset threshold value Cth for a predetermined time or longer (step  201 ). If capacitance C 2  of the second electrode  20   b  indicated by the second operation signal S 2  has exceeded the threshold value Cth for the predetermined time or longer (step  201 : YES), that is, if the door ECU  10  detects a hand-holding operation performed by the user, the door ECU  10  determines whether the sliding door  5  is in a fully closed position (step  202 ). If the sliding door  5  is in the fully closed position (step  202 : YES), the door ECU  10  opens the sliding door  5  (step  203 ). If the sliding door  5  is in any open position (step  202 : NO), the door ECU  10  closes the sliding door  5  (step  204 ). 
     Wetting Detection 
     Wetting detection control performed by the input operation detector  21  of the present embodiment will now be described. 
     As shown in  FIGS. 1, 3, and 4 , the operation detection unit  15  of the present embodiment includes a wetting detection electrode  40  that is located downward from the first electrode  20   a , the second electrode  20   b , and the third electrode  20   c  and arranged next to the first electrode  20   a , the second electrode  20   b , and the third electrode  20   c . The operation detection unit  15  includes the wetting detection electrode  40  arranged next to the operation detection electrode  20 . The wetting detection electrode  40  of the operation detection unit  15  in the present embodiment has a substantially rectangular flat plate form extending substantially in parallel with the first electrode  20   a , the second electrode  20   b , and the third electrode  20   c . Further, the wetting detection electrode  40  is arranged to extend under the first electrode  20   a , the second electrode  20   b , and the third electrode  20   c . Accordingly, the wetting detection electrode  40  of the operation detection unit  15  of the present embodiment is arranged at a location that is closer to the lower frame  30   b  of the window portion  30  than the first electrode  20   a , the second electrode  20   b , and the third electrode  20   c , which are arranged along the lower frame  30   b  of the window portion  30 . 
     As described above, the operation detection unit  15  of the present embodiment includes the detection circuit  23  mounted on the board  22 . As shown in  FIG. 2 , the detection circuit  23  detects capacitance Cw of the wetting detection electrode  40  separately from capacitance C 1  of the first electrode  20   a , capacitance C 2  of the second electrode  20   b , and capacitance C 3  of the third electrode  20   c . The operation detection unit  15  of the present embodiment outputs a wetting detection signal Sw that indicates capacitance Cw of the wetting detection electrode  40  to the door ECU  10 . The door ECU  10  of the present embodiment is configured to detect that the vehicle  1  is in a wet state by comparing a capacitance change at the wetting detection electrode  40 , which is indicated by the wetting detection signal Sw, with a capacitance change at the operation detection electrode  20 , which is indicated by the operation detection signal Sx. 
     More specifically, as shown in  FIGS. 1 and 4 , the window portion  30  of the vehicle  1  is shaped to have a recess into which water  50  collected on an outer surface  1   s  of the vehicle  1  easily flows when vehicle  1  is wet. The water  50  that flows into the window portion  30  has a tendency to collect on the lower frame  30   b  of the window portion  30  where a belt molding is formed. In other words, the lower frame  30   b  of the window portion  30  is a location referred to as a water collection portion  51  where water from the outer surface  1   s  of the vehicle  1  collects when the vehicle  1  is wet. The operation detection electrode  20  arranged in the operation detection unit  15  may react to water  50  in the lower frame  30   b  of the window portion  30  serving as the water collection portion  51 . This may lead to erroneous determination that a user input operation has been detected as described above. 
     In this regard, the input operation detector  21  of the present embodiment includes the wetting detection electrode  40 , as described above, and the wetting detection electrode  40  is closer to the water collection portion  51  than the operation detection electrode  20 . 
     As shown in  FIG. 8 , if the lower frame  30   b  of the window portion  30  includes the water  50 , the wetting detection electrode  40  arranged at a location closer to the lower frame  30   b  of the window portion  30  has a greater capacitance change sensitivity to the water  50  than the first electrode  20   a , the second electrode  20   b , and the third electrode  20   c . In other words, if the water collection portion  51  includes the water  50 , the wetting detection electrode  40  has a greater capacitance change sensitivity than the operation detection electrode  20  to the water  50  in the water collection portion  51 . Specifically, since the wetting detection electrode  40  is closer to the water collection portion  51  than the operation detection electrode  20 , a degree of change in capacitance Cw of the wetting detection electrode  40  when the water collection portion  51  includes water is greater than a degree of change in capacitance Cx of the operation detection electrode  20  when the water collection portion  51  includes water. 
     Specifically, as shown in  FIG. 9A , the wetting detection electrode  40  of the present embodiment is configured to have a smaller capacitance than the operation detection electrode  20  (Cx&gt;Cw) when the detection subject X (such as hand of user) approaches the operation detection electrode  20  if the lower frame  30   b  of the window portion  30 , which serves as the water collection portion  51 , does not include the water  50 . Further, as shown in  FIG. 9B , the wetting detection electrode  40  is also configured to have a greater capacitance than the operation detection electrode  20  (Cx&lt;Cw) if the lower frame  30   b  of the window portion  30  does not include water  50 . This allows the door ECU  10  of the present embodiment to detect a wet state of the vehicle  1 . 
       FIG. 9B  shows a capacitance change when the vehicle  1  is wet and water flows to the lower frame  30   b  of the window portion  30 , which serves as the water collection portion  51  of the vehicle  1 . In the vehicle  1  of the present embodiment, the wetting detection electrode  40  arranged near the lower frame  30   b  of the window portion  30  has a tendency to be electrically coupled to the inner panel  31  and the outer panel  32  of the sliding door  5 , which are made of metal. Thus, the wetting detection electrode  40  has a smaller capacitance change sensitivity to the detection subject X such as the hand of the user that performs an input operation when the lower frame  30   b  does not include the water  50 . In this manner, since the wetting detection electrode  40  is closer to the metal component of the vehicle  1  than the operation detection electrode  20 , the wetting detection electrode  40  is more likely to be electrically coupled to the metal component than the operation detection electrode  20 . If the water collection portion  51  does not include the water  50 , a degree of change in capacitance Cx of the operation detection electrode  20  when the detection subject X approaches the operation detection electrode  20  and the wetting detection electrode  40  is greater than a degree of change in capacitance Cw of the wetting detection electrode  40  when the detection subject X approaches the operation detection electrode  20  and the wetting detection electrode  40 . The metal component includes the inner panel  31  and the outer panel  32  of the sliding door  5 . 
     When the operation detection electrode  20  has a greater capacitance change sensitivity than the wetting detection electrode  40 , that is, when the vehicle  1  is not wet, the door ECU  10  of the present embodiment determines detection of an input operation using corrected capacitance Cx′ that is obtained by adding capacitance Cw of the wetting detection electrode  40  to capacitance Cx of the operation detection electrode  20  (Cx′=Cx+Cw). 
     Specifically, the door ECU  10  of the present embodiment calculates corrected value C 1 ′ of capacitance C 1  by adding capacitance Cw of the wetting detection electrode  40  to capacitance C 1  of the first electrode  20   a  indicated by the first operation signal  51 . Further, the door ECU  10  calculates corrected value C 2 ′ of capacitance C 2  by adding capacitance Cw of the wetting detection electrode  40  to capacitance C 2  of the second electrode  20   b  indicated by the second operation signal S 2 . The door ECU  10  also calculates corrected value C 3 ′ of capacitance C 3  by adding capacitance Cw of the wetting detection electrode  40  to capacitance C 3  of the third electrode  20   c  indicated by the third operation signal S 3 . The door ECU  10  is configured to separately compare corrected value C 1 ′, corrected value C 2 ′, and corrected value C 3 ′ with the preset threshold value Cth (refer to  FIG. 5 ) to determine detection of an input operation as described above. 
     More specifically, as shown by the flowchart in  FIG. 10 , the door ECU  10  of the present embodiment compares capacitance Cx of the operation detection electrode  20  with capacitance Cw of the wetting detection electrode  40  (step  301 ). If capacitance Cx of the operation detection electrode  20  is greater than or equal to capacitance Cw of the wetting detection electrode  40  (step  301 : YES, Cx≥Cw), the door ECU  10  determines that the vehicle  1  is not in a wet state (step  302 ). 
     Then, the door ECU  10  performs correction calculation on capacitance Cx by adding capacitance Cw of the wetting detection electrode  40  to capacitance Cx of the operation detection electrode  20  (step  303 ). The door ECU  10  uses corrected capacitance Cx′ calculated in step  303  to determine detection of an input operation (step  304 ). The door ECU  10  corresponds to an input operation determining unit  10   a.    
     If the door ECU  10  of the present embodiment determines that capacitance Cw of the wetting detection electrode  40  is greater than capacitance Cx of the operation detection electrode  20  (step  301 : NO, Cx&lt;Cw), the door ECU  10  determines that the vehicle  1  is in a wet state (step  305 ). Then, the door ECU  10  prohibits determination of detection of an input operation, which is based on a capacitance change at the operation detection electrode  20  indicated by an operation detection signal Sx (step  306 ). The door ECU  10  corresponds to an operation determination prohibiting unit  10   b . With this structure, the input operation detector  21  of the present embodiment is configured to prevent erroneous input operation determination when the vehicle  1  is wet. 
     The advantages of the present embodiment will now be described. 
     (1) The input operation detector  21  includes the operation detection electrode  20  that detects an input operation from a capacitance change, which results from the approaching detection subject X, and the wetting detection electrode  40  arranged next to the operation detection electrode  20 . The water collection portion  51  collects water  50  from the outer surface  1   s  of the vehicle  1  when the vehicle  1  is wet. The wetting detection electrode  40  is closer to the water collection portion  51  than the operation detection electrode  20 . The input operation detector  21  is configured so that if the water collection portion  51  does not include water, the operation detection electrode  20  has a greater capacitance change sensitivity than the wetting detection electrode  40  to the approach of the detection subject X. Further, the input operation detector  21  is configured so that if the water collection portion  51  includes water, the wetting detection electrode  40  has a greater capacitance change sensitivity than the operation detection electrode  20 . 
     With the above structure, the wet state of the vehicle  1  is detected by comparing the capacitance change sensitivity of the operation detection electrode  20  with the capacitance change sensitivity of the wetting detection electrode  40 . This prevents erroneous determination and detects an input operation with high accuracy when the vehicle  1  is in a wet state. 
     (2) If the wetting detection electrode  40  has a greater capacitance change sensitivity than the operation detection electrode  20 , the door ECU  10 , which serves as the operation determination prohibiting unit  10   b , prohibits determination of input operation detection, which is based on a capacitance change at the operation detection electrode  20 . This prevents erroneous determination when the vehicle  1  is in a wet state. 
     (3) If the operation detection electrode  20  has a greater capacitance change sensitivity than the wetting detection electrode  40 , the door ECU  10 , which serves as the input operation determining unit  10   a , determines detection of an input operation using corrected capacitance Cx′, which is obtained by adding capacitance Cw of the wetting detection electrode  40  to capacitance Cx of the operation detection electrode  20 . 
     In other words, if the water collection portion  51  does not include the water  50 , when the detection subject X approaches the operation detection electrode  20 , capacitance Cw of the wetting detection electrode  40 , which is arranged next to the operation detection electrode  20 , is changed in the same manner as the operation detection electrode  20 . Thus, an input operation is detected with improved accuracy by using corrected capacitance Cx′, which is obtained by adding capacitance Cw to capacitance Cx. 
     (4) The wetting detection electrode  40  is configured to have, when the detection subject X approaches the operation detection electrode  20 , smaller capacitance than the operation detection electrode  20  (Cx&gt;Cw) if the water collection portion  51  does not include the water  50 . Further, the wetting detection electrode  40  is configured to have greater capacitance than the operation detection electrode  20  (Cx&lt;Cw) if the water collection portion  51  includes the water  50 . 
     The above structure determines detection of an input operation and determines wetting of the vehicle  1  by directly comparing capacitance Cx of the operation detection electrode  20  with capacitance Cw of the wetting detection electrode  40 . This reduces the calculation load. 
     (5) The operation detection electrode  20  and the wetting detection electrode  40  are arranged upward from the lower frame  30   b  of the window portion  30  in the sliding door  5  of the vehicle  1 . 
     With the above structure, the sliding door  5  can be operated by performing an intuitive input operation performed when the detection subject X (such as hand) is brought near the sliding door  5 , which is an operation object. The water  50  that flows into the window portion  30  tends to collect on the lower frame  30   b  of the window portion  30  at a belt molding. Thus, the wet state of the vehicle  1  is accurately detected with by the wetting detection electrode  40  arranged upward from the lower frame  30   b , which serves as the water collection portion  51 . 
     The sliding door  5  is substantially made of metal. The wetting detection electrode  40  arranged near the lower frame  30   b  of the window portion  30  has a tendency to be electrically coupled to the sliding door  5 , which is a conductor. Thus, the wetting detection electrode  40  can be set to have a smaller capacitance change sensitivity to the detection subject X such as the hand of the user that performs an input operation when the lower frame  30   b  does not include the water  50 . 
     (6) The input operation detector  21  includes three operation detection electrodes  20  arranged along the lower frame  30   b  of the window portion  30 . Specifically, the input operation detector  21  includes the first electrode  20   a , the second electrode  20   b , and the third electrode  20   c  arranged along the lower frame  30   b  of the window portion  30 . The wetting detection electrode  40  is arranged to extend under the first electrode  20   a , the second electrode  20   b , and the third electrode  20   c.    
     The above structure allows for the detection of plural types of input operations from a combination of a capacitance change at the first electrode  20   a , a capacitance change at the second electrode  20   b , and a capacitance change at the third electrode  20   c . Further, the capacitance change that occurs at the first electrode  20   a , the second electrode  20   b , and the third electrode  20   c  may be separately compared with a capacitance change caused at the wetting detection electrode  40 . This allows for an input operation to be detected further accurately. 
     The above illustrated embodiment may be modified as follows. The above-described embodiment and the following modifications can be combined as long as the combined modifications remain technically consistent with each other. 
     In the above embodiment, the operation detection unit  15  includes the operation detection electrode  20  and the wetting detection electrode  40  that are integrated with each other. The operation detection unit  15  is installed at the inner side of the window portion  30  in the sliding door  5  of the vehicle  1 . Instead, the operation detection unit  15  may be installed at the inner side of the window portion  30  of a different type of door, such as a swing door or a back door. The operation detection unit  15  may be installed in the window portion  30  of a member other than a door that includes the lower frame  30   b , which serves as the water collection portion  51 . The operation detection electrode  20  and the wetting detection electrode  40  do not need to be integrated as the operation detection unit  15 . The operation detection electrode  20  and the wetting detection electrode  40  may be arranged near a water collection portion  51  that differs from the lower frame  30   b  of the window portion  30 . 
     In the above embodiment, the input operation detector  21  includes three operation detection electrodes  20 . Specifically, the input operation detector  21  includes the first electrode  20   a , the second electrode  20   b , and the third electrode  20   c . However, the number of the operation detection electrodes  20  may be changed. That is, the number of the operation detection electrodes  20  may be one or two. Alternatively, the input operation detector  21  may include four or more operation detection electrodes  20 . 
     In the above embodiment, the first electrode  20   a , the second electrode  20   b , the third electrode  20   c , and the wetting detection electrode  40  have the form of a substantially rectangular flat plate. Instead, the shapes of the operation detection electrode  20  and the wetting detection electrode  40  may be changed. The wetting detection electrode  40  does not need to extend over the entire region where the operation detection electrodes  20  are arranged. 
     In the above embodiment, the wetting detection electrode  40  is configured to have a smaller capacitance than the operation detection electrode  20  (Cx&gt;Cw) when the detection subject X (such as hand of user) approaches the operation detection electrode  20  if the lower frame  30   b  of the window portion  30 , which serves as the water collection portion  51 , does not include the water  50 . The wetting detection electrode  40  is also configured to have a greater capacitance than the operation detection electrode  20  (Cx&lt;Cw) if the lower frame  30   b  of the window portion  30  includes the water  50 . 
     Instead, if the water collection portion  51  does not include the water  50 , the operation detection electrode  20  may have a greater capacitance change sensitivity than the wetting detection electrode  40  when the detection subject X approaches. Further, if the water collection portion  51  includes water  50 , the wetting detection electrode  40  may have a greater capacitance change sensitivity than the operation detection electrode  20 . In other words, capacitance Cx and capacitance Cw do not need to be directly compared. For example, capacitance Cx and capacitance Cw may each be multiplied by a unique coefficient and then compared. Alternatively, the capacitance change sensitivity may be monitored to compare the changing rate of capacitance Cx and capacitance Cw. Specifically, a degree of change in capacitance Cx of the operation detection electrode  20  may be the amount of change in capacitance Cx, the rate of capacitance Cx, a value obtained by multiplying the amount of change in capacitance Cx by a coefficient, or a value obtained by multiplying the rate of capacitance Cx by a coefficient. Likewise, a degree of change in capacitance Cw of the wetting detection electrode  40  may be the amount of change in capacitance Cw, the rate of capacitance Cw, a value obtained by multiplying the amount of change in capacitance Cw by a coefficient, or a value obtained by multiplying the rate of capacitance Cw by a coefficient. Correction calculation performed by adding capacitance Cw of the wetting detection electrode  40  to capacitance Cx of the operation detection electrode  20  may be changed. Specifically, a value obtained by multiplying capacitance Cw of the wetting detection electrode  40  by a unique coefficient may be added to a value obtained by multiplying capacitance Cx of the operation detection electrode  20  by a unique coefficient. 
     The above embodiment prohibits determination of detection of an input operation, which is based on a capacitance change at the operation detection electrode  20  if the wetting detection electrode  40  has a greater capacitance change sensitivity than the operation detection electrode  20 . Instead, the determination condition to determine detection of an input operation may be stricter if the wetting detection electrode  40  has a greater capacitance change sensitivity than the operation detection electrode  20 , specifically, if the vehicle  1  is in a wet state. Specifically, the input operation detector  21  may include, for example, a determination condition changing unit that varies the threshold value to limit determination of an input operation. This configuration also prevents erroneous determination in a preferred manner if the vehicle  1  is in a wet state. 
     In the above embodiment, an input operation performed by the user is detected if peaks in a capacitance change exceeding the threshold value Cth at the first electrode  20   a , the second electrode  20   b , and the third electrode  20   c  shift in the direction of the opening and closing actuation of the sliding door  5  and if capacitance C 2  of the second electrode  20   b  exceeds the threshold value Cth for the predetermined time or longer. Instead, an input operation by the user may be detected through an input operation pattern other than a “swipe operation” and a “hand-holding operation.” 
     The door ECU  10  (specifically, input operation determining unit  10   a  and operation determination prohibiting unit  10   b ) is not limited to a device that includes a CPU and a ROM and executes software processing. For example, a dedicated hardware circuit (such as ASIC) may be provided that executes at least part of the software processes executed in the above-described embodiment. That is, the door ECU  10  may be modified to have any one of the following configurations (a) to (c). (a) A configuration including a processor that executes all of the above-described processes according to programs and a program storage device such as a ROM that stores the programs. (b) A configuration including a processor and a program storage device that execute part of the above-described processes according to the programs and a dedicated hardware circuit that executes the remaining processes. (c) A configuration including a dedicated hardware circuit that executes all of the above-described processes. A plurality of software executing devices each including a processor and a program storage device and a plurality of dedicated hardware circuits may be provided. That is, the above processes may be executed by processing circuitry that includes at least one of a set of one or more software executing devices or a set of one or more dedicated hardware circuits. The program storage device, or computer readable media, includes any type of media that are accessible by general-purpose computers and dedicated computers. 
     Various changes in form and details may be made to the examples above without departing from the spirit and scope of the claims and their equivalents. The examples are for the sake of description only, and not for purposes of limitation. Descriptions of features in each example are to be considered as being applicable to similar features or aspects in other examples. Suitable results may be achieved if sequences are performed in a different order, and/or if components in a described system, architecture, device, or circuit are combined differently, and/or replaced or supplemented by other components or their equivalents. The scope of the disclosure is not defined by the detailed description, but by the claims and their equivalents. All variations within the scope of the claims and their equivalents are included in the disclosure.