Patent Publication Number: US-9834175-B2

Title: Door opening and closing device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priorities of Japanese Patent Application Nos.: 2015-208207 and 2015-20808 filed on Oct. 22, 2015, the contents of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     Technical Field 
     The present invention relates to a door opening and closing device used in a vehicle. 
     Related Art 
     A vehicle is equipped with a smart entry system which electrically unlocks a door locking device when a user having an electronic key approaches a door. Japanese Patent No. 5643129 discloses a door body control device which can automatically open a door even when a user does not touch a door handle in a situation where it is difficult for the user to touch the door handle such as a case where the user is holding baggage or the like with both hands. 
     Upon the detection of the user approaching the door by a distance measuring sensor disposed on the door, the door body control device performs the authentication of an electronic key which the user possesses. When the electronic key is authenticated as a legitimate electronic key and a set movement (operation intention) of the user is detected, the door body control device opens the door. 
     SUMMARY 
     However, in the door body control device disclosed in Japanese Patent No. 5643129, there is a possibility that an operation intention of a user cannot be accurately determined by the distance measuring sensor. Further, Japanese Patent No. 5643129 does not at all describe a countermeasure for determining an operation intention of a user with high accuracy by the distance measuring sensor. 
     It is an object of the present invention to provide a door opening and closing device which can detect an operation intention of a user stably and with high accuracy. 
     A first aspect of the present invention provides a door opening and closing device including: a door opening and closing drive unit capable of opening and closing a door with respect to a vehicle body; a first detection unit and a second detection unit configured to detect a detection object around the door; and a control unit configured to perform an opening and closing control of the door by way of the door opening and closing drive unit based on a detection result of the first detection unit and a detection result of the second detection unit, wherein the first detection unit has a first detection range where the detection object is detectable, the second detection unit has a second detection range where the detection object is detectable, and one operation zone is set by making a portion of the first detection range and a portion of the second detection range overlap with each other, and the control unit is configured to perform the opening and closing control of the door only when set movement of the detection object is detected within the operation zone based on at least one of the detection result of the first detection unit and the detection result of the second detection unit. 
     According to this door opening and closing device, by making a portion of the first detection range of the first detection unit and a portion of the second detection range of the second detection unit overlap with each other, a particular operation zone having a fixed width direction can be set without using a special device. Accordingly, an operation intention of a user can be detected stably and with high accuracy and hence, and an erroneous detection can be surely prevented. 
     A second aspect of the present invention provides a door opening and closing device which includes: a door opening and closing drive unit capable of opening and closing a door with respect to a vehicle body; a detection part disposed on the vehicle body and configured to detect a detection object around the door; an optical display unit configured to perform an optical display so as to guide a user to a set position, and a control unit configured to control the optical display unit and to perform an open/close control of the door by way of the door opening and closing drive unit based on a detection result of the detection part, wherein the detection part includes a transmission part configured to transmit a radio signal such that the radio signal expands radially, and a reception part configured to receive a reflection signal formed by the reflection of the radio signal on the detection object, wherein the transmission part is disposed such that an output center of the radio signal is outputted in a horizontal direction from the vehicle body. 
     According to this door opening and closing device, the optical display unit is controlled based on a detection result of the detection part and hence, it is possible to allow a user to easily recognize an operation method and an operation timing when the user performs an opening or closing operation. Accordingly, the operability and the convenience of the user can be improved. The detection unit detects a detection object upon the reception of a reflection signal of a radio signal outputted in the horizontal direction and hence, there is no possibility that the detection unit receives a reflection signal from a member other than a detection object such as a ground. With the use of a single detection unit, it is possible to perform both the detection of a detection object at a remote distance away from the vehicle body and the detection of a detection object at a near distance close to the vehicle body. Further, the detection units are mounted on the vehicle body and hence, the same reference (distance) is used in detecting a detection object in both the case where an open control of the door is performed and the case where a close control of the door is performed. Accordingly, an erroneous detection which may be caused due to the detection unit can be prevented with certainty and hence, it is possible to rapidly detect an operation intention of a user with high accuracy. 
     According to the door opening and closing device of the present invention, the particular operation zone having a fixed width direction is set by making a portion of the first detection range of the first detection part and a portion of the second detection range of the second detection unit overlap with each other and hence, an operation intention of a user can be detected stably and with high accuracy whereby an erroneous detection can be prevented with certainty. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and the other features of the present invention will become apparent from the following description and drawings of an illustrative embodiment of the invention in which: 
         FIG. 1  is a side view of a vehicle in a state where a door opening and closing device of a first embodiment is mounted on the vehicle; 
         FIG. 2  is a block diagram showing a configuration of the door opening and closing device; 
         FIG. 3  is a cross-sectional view of the door opening and closing device of the first embodiment; 
         FIG. 4  is another cross-sectional view of the door opening and closing device of the first embodiment; 
         FIG. 5  is a plan view showing a detection region of the door opening and closing device; 
         FIG. 6  is a table showing a method of determining whether or not a detection object is an obstacle; 
         FIG. 7A  is a flowchart showing a control performed by a control unit; 
         FIG. 7B  is a flowchart showing steps which follow steps shown in  FIG. 7A ; 
         FIG. 8  is a flowchart showing an obstacle detection processing in  FIG. 7A ; 
         FIG. 9  is a flowchart showing an exclusion cancellation processing in  FIG. 7A ; 
         FIG. 10  is a flowchart showing an obstacle exclusion processing in  FIG. 7A ; 
         FIG. 11  is a flowchart showing an approach mode in  FIG. 7B ; 
         FIG. 12  is a flowchart showing a start mode in  FIG. 7B ; 
         FIG. 13  is a flowchart showing a trigger mode in  FIG. 7B ; 
         FIG. 14  is a flowchart showing a back mode in  FIG. 7B ; 
         FIG. 15  is a flowchart showing a close back first mode in  FIG. 7B ; 
         FIG. 16  is a flowchart showing a close back second mode in  FIG. 7B ; and 
         FIG. 17  is a cross-sectional view of a door opening and closing device according to a second embodiment. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Hereinafter, embodiments of the present invention are described with reference to drawings. 
     First Embodiment 
       FIGS. 1 and 2  show a vehicle  1  on which a door opening and closing device  10  of a first embodiment is disposed. The door opening and closing device  10  automatically performs an open control or a close control of a door  4  of the vehicle  1  with respect to a vehicle body  2  when a user possessing a specified electronic key (not shown in the drawing) makes a preset movement without using his/her hand. In this embodiment, a back door is the openable/closable door  4 . However, the openable/closable door  4  may be a door other than the back door. 
     As shown in  FIG. 2 , the vehicle  1  includes a host ECU  5  which controls electronic equipment including the door opening and closing device  10 . The host ECU  5  also has a function as a collation unit which performs the key authentication between an electronic key and the vehicle  1  by radio communication. When a user having the electronic key approaches within a set range which is set with respect to the vehicle  1 , the host ECU  5  requests the electronic key to transmit an authentication code to the host ECU  5 . The host ECU  5  compares the authentication code received from the electronic key with an authorized code registered in the host ECU  5 . When the authentication code agrees with the authorized code, the host ECU  5  outputs a signal to the door opening and closing device  10  so as to allow the door opening and closing device  10  to perform an open/close control of the door  4 . A function of a collation unit may be imparted to a controller  30  (described later) of the door opening and closing device  10 . 
     (Detail of Door Opening and Closing Device) 
     The door opening and closing device  10  is disposed at a lower portion of the center of a bumper  3  of the vehicle body  2 . The door opening and closing device  10  includes: a door opening and closing drive unit  12  which can open/close the door  4 ; a pair of distance measuring sensors  20 A,  20 B which are a detection unit; LEDs  28  which is optical display units; and the controller  30  which is a control unit. The door opening and closing drive unit  12  is disposed on the vehicle  1 . A printed circuit board  24  on which the distance measuring sensors  20 A,  20 B, the LEDs  28  and the controller  30  are mounted is housed and disposed in a casing  14 . 
     The door opening and closing drive unit  12  is a mechanism including a drive device (a motor, a gear mechanism, a damper and the like) which can rotate the door  4  connected to the vehicle body  2  by a hinge in the opening direction and the closing direction. The door opening and closing drive unit  12  is communicably connected to the controller  30 . In this embodiment, the door opening and closing drive unit  12  and the controller  30  are connected to each other via wired connection using a communication cable. However, the door opening and closing drive unit  12  and the controller  30  may be wirelessly connected to each other via radio communication at a predetermined frequency. 
     As shown in  FIGS. 3 and 4 , a casing  14  is a box body having one end opened, and includes a bezel  15  which covers an opening side of the casing  14 . A fixing part  16  for fixing the casing  14  to the bumper  3  is formed on the bezel  15 . Sensor mounting portions  17  having a substantially cylindrical shape and opened in the horizontal direction are mounted on the bezel  15 . The sensor mounting portions  17 ,  17  are respectively inclined and opened to both outer sides such that axes of the sensor mounting portions  17 ,  17  are gradually away from each other. A lens mounting portion  18  which has substantially a cylindrical shape and on which a lens  29  is disposed is mounted on the bezel  15 . The lens mounting portion  18  is disposed on the bezel  15  such that an axis of the lens mounting portion  18  is inclined downward and outward (rearward). 
     The distance measuring sensors  20 A,  20 B are detection units which detect detection objects around the door  4 . These distance measuring sensors  20 A,  20 B are mounted on the sensor mounting portions  17 ,  17  of the bezel  15  respectively. The distance measuring sensors  20 A,  20 B are communicably connected to the printed circuit board  24  by lead lines. With reference to  FIG. 2 , the first distance measuring sensor (first detection unit)  20 A includes a transmission part  21 A which transmits a radio signal (ultrasonic wave) having a predetermined frequency, and a reception part  22 A which receives a reflection signal (reflected wave) which is formed by the reflection of the radio signal on the detection object. The second distance measuring sensor (second detection unit)  20 B includes a transmission part  21 B which has substantially the same configuration as the transmission part  21 A and a reception part  22 B which ahs substantially the same configuration as the reception part  22 A. In this embodiment, the distance measuring sensor  20 A,  20 B is formed of an ultrasonic sensor. The distance measuring sensor  20 A,  20 B may be configured such that the transmission part  21 A,  21 B and the reception part  22 A,  22 B are disposed individually or independently. Alternatively, the distance measuring sensor  20 A,  20 B may be configured such that the transmission part and the reception part are formed into an integral body thus forming a transmission/reception part. A detection object which can be detected by the distance measuring sensor  20 A,  20 B is an object which can reflect a radio signal, and includes an obstacle such as a wall or baggage, not to mention a user who is a driver of a vehicle. In this embodiment, the obstacle includes objects other than a user such as baggage which can be moved and placed around the vehicle, a structure which exists around the vehicle and cannot be moved (a wall or a pole), other vehicles parked near the vehicle or the like. 
     The printed circuit board  24  is mounted on the casing  14  such that the printed circuit board  24  extends in the direction orthogonal to an axis of the lens mounting portion  18 . A connector  25  for making the printed circuit board  24  communicably connected to the host ECU  5  and a connector  26  for making the printed circuit board  24  electrically connected to a constant voltage power source are mounted on the printed circuit board  24 . These connectors  25 ,  26  are mounted on the printed circuit board  24  such that the connectors  25 ,  26  are exposed to the outside from a bottom of the casing  14 . A plurality of (three in this embodiment) LEDs  28 , a microcomputer not shown in the drawing which forms the controller  30  and the like are mounted on a lens mounting portion  18  side of the printed circuit board  24 . 
     The LEDs  28  are optical display units which perform an optical display (operation mark) on the ground so as to guide a user to a set position. Three LEDs  28  are mounted on the printed circuit board  24  such that these LEDs  28  are positioned in the vicinity of the axis of the lens mounting portion  18 . With such a configuration, these LEDs  28  illuminate the ground as spotlights so that a user can visually recognize the operation mark even in a state where an area around the vehicle  1  is bright, not to mention in a state where the area around the vehicle  1  is dark. The lens  29  is mounted on the lens mounting portion  18 , and the lens  29  converges light from the LEDs  28  and directs a light to a ground G outside the vehicle body  2 . A focal point F of the lens  29  is set such that the focal point F is positioned at a rear end of the vehicle  1 . 
     As shown in  FIG. 2 , the controller  30  is a control unit which controls the LEDs  28  based on detection results of the distance measuring sensors  20 A,  20 B, and performs open/close driving of the door  4  by controlling the door opening and closing drive unit  12 . The controller  30  includes: a memory part  30   a ; a display control part  30   b ; a transmission/reception mode switching part  30   c ; a measurement part  30   d ; and a determination part  30   e . In this embodiment, a piece of microcomputer is used as the controller  30 , and the controller  30  has all the functions of the memory part  30   a , the display control part  30   b , the transmission/reception mode switching part  30   c , the measurement part  30   d  and the determination part  30   e . However, these parts may be individually provided as control parts. 
     A program for controlling the door opening and closing device  10  is stored in the memory part  30   a . Setting data such as threshold values T which are used in the program are also stored in the memory part  30   a . Detection data (detection results) DA 1  to DAn, DB 1  to DBn relating to detection objects detected by the distance measuring sensors  20 A,  20 B are stored in the memory part  30   a  as distance information. The memory part  30   a  can store the stored data (stored information) MA 1  to MAn and the stored data MB 1  to MBn by an amount corresponding to the set number of times (ten times, for example) of detection, and the data are deleted in order from the oldest data. Obstacle data K 1  to Kn relating to obstacles which are determined as objects not to be detected are also stored in the memory part  30   a  as stored information. 
     The display control part  30   b  changes over the state of the LEDs  28  between a light-on state, a blinking state, and a light-off state. By controlling the state of the LEDs  28  in this manner, it is possible to guide a user to move to a set position and, at the same time, it is possible to inform a user of proper timing of movement. A sound may be outputted together with lighting of the LEDs  28  as a part which informs the user of proper timing of movement. 
     The transmission/reception mode switching part  30   c  changes over a transmission/reception mode of the first distance measuring sensor  20 A and a transmission/reception mode of the second distance measuring sensor  20 B. To be more specific, the transmission/reception mode switching part  30   c  changes over a transmission/reception function of the first distance measuring sensor  20 A and a transmission/reception function of the second distance measuring sensor  20 B between a first transmission/reception mode and a second transmission/reception mode. In the first transmission/reception mode, the transmission part  21 A,  21 B and the reception part  22 A,  22 B are simultaneously driven in both the first distance measuring sensor  20 A and the second distance measuring sensor  20 B. In the second transmission/reception mode, only the transmission part  21 A,  21 B is driven in one of the first distance measuring sensor  20 A and the second distance measuring sensor  20 B, and only the reception part  22 A,  22 B is driven in the other of the first distance measuring sensor  20 A and the second distance measuring sensor  20 B. Further, in the second transmission/reception mode, a transmission/reception function of the first distance measuring sensor  20 A and a transmission/reception function of the second distance measuring sensor  20 B are alternately changed over. That is, a first state where a radio signal is outputted from the transmission part  21 A of the first distance measuring sensor  20 A and a reflection signal is received by the reception part  22 B of the second distance measuring sensor  20 B and a second state where a radio signal is outputted from the transmission part  21 B of the second distance measuring sensor  20 B and a reflection signal is received by the reception part  22 A of the first distance measuring sensor  20 A are alternately changed over. 
     The measurement part  30   d  measures distances from the first distance measuring sensor  20 A to detection objects based on the detection results DA 1  to DAn of the first distance measuring sensor  20 A, and also measures distances from the second distance measuring sensor  20 B to the detection objects based on the detection result DB 1  to DBn of the second distance measuring sensor  20 B. In this embodiment, the distance measuring sensor  20 A,  20 B can measure (determine) a distance from the distance measuring sensor  20 A,  20 B to each detection object based on a time elapsed from a point of time when a radio signal is outputted from the transmission part  21 A,  21 B to a point of when that a reflection signal is inputted to the reception part  22 A,  22 B. When a distance from the distance measuring sensor  20 A,  20 B to each detection object is small, a time elapsed from the transmission of a signal to the reception of a signal is short compared to a case where a distance from the distance measuring sensor  20 A,  20 B to each detection object is large. In this manner, by measuring a time which corresponds to a distance, the distance from the distance measuring sensors  20 A,  20 B to each detection object can be measured. 
     The determination part  30   e  determines whether or not detection objects exist based on detection results (measurement results of the measurement part  30   d ) DA 1  to DAn, DB 1  to DBn of the distance measuring sensors  20 A,  20 B. It is also determined whether the detected detection objects are objects to be detected or objects not to be detected based on detection results DA 1  to DAn, DB 1  to DBn of the distance measuring sensors  20 A,  20 B and stored information MA 1  to MAn, MB 1  to MBn in the memory part  30   a.    
     Here, the description is made in detail with respect to the determination on whether detected detection objects are objects to be detected or objects not to be detected. Based on current detection results DA 1  to DAn, DB 1  to DBn detected by the distance measuring sensors  20 A,  20 B and last-time stored information MA 1  to MAn, MB 1  to MBn (obtained in the last-time detection) stored in the memory part  30   a , the determination part  30   e  calculates a change amount in a distance with respect to all measured detection objects. The determination part  30   e  determines whether the detection object is an object to be detected or an object not to be detected based on whether a change amount in distance is equal to or smaller than a threshold value T1 (2 cm, for example). The determination part  30   e  performs a comparison between the detection results DA 1  to DAn, DB 1  to DBn and the stored information MA 1  to MAn, MB 1  to MBn for the respective distance measuring sensors  20 A,  20 B. Further, the determination part  30   e  performs a comparison in such a manner that each one of the detection results DA 1  to DAn, DB 1  to DBn is compared with all stored information MA 1  to MAn, MB 1  to MBn on a one-to-one basis, and the determination part  30   e  determines that a detection object is an object not to be detected when data agree with each other, that is, when the detection result agrees with the stored information. 
     For example, as shown in  FIG. 6 , the first distance measuring sensor  20 A receives three reflection signals, and measures a first detection result DA 1  (50 cm), a second detection result DA 2  (80 cm) and a third detection result DA 3  (100 cm) through the measurement part  30   d . In the same manner, the second distance measuring sensor  20 B receives three reflection signals, and measures a first detection result DB 1  (55 cm), a second detection result DB 2  (75 cm) and a third detection result (100 cm) through the measurement part  30   d . A first stored information MA 1  (51 cm), a second stored information MA 2  (99 cm), and a third stored information MA 3  (115 cm) which are last-time detection results of the first distance measuring sensor  20 A are stored in the memory part  30   a . In the same manner, first stored information MB 1  (54 cm), second stored information MB 2  (101 cm), and third stored information MB 3  (120 cm) which are last-time detection results of the second distance measuring sensor  20 B are stored in the memory part  30   a.    
     In comparison of the first detection result DA 1  of the first distance measuring sensor  20 A with the stored information MA 1  to MA 3  stored in the memory part  30   a , a change amount of the first detection result DA 1  from the stored information MA 1  is equal to or smaller than the threshold value T1 so that it is understood that there is no change in distance (position) of the detection object. Next, in a comparison of the second detection result DA 2  with the stored information MA 1  to MA 3 , a change amount of the second detection result DA 2  is larger than the threshold value T1 with respect to all stored information MA 1  to MA 3  so that it is understood that the position of the detection object is changed. Next, in a comparison of the third detection result DA 3  with the stored information MA 1  to MA 3 , a change amount of the third detection result DA 3  from the stored information MA 2  is equal to or smaller than the threshold value T1 so that it is understood that there is no change in the position of the detection object. 
     In the same manner, in a comparison of the first detection result DB 1  of the second distance measuring sensor  20 B with the stored information MB 1  to MB 3  in the memory part  30   a , a change amount of the first detection result DB 1  from the stored information MB 1  is equal to or smaller than the threshold value T1 so that it is understood that there is no change in position of the detection object. Next, in a comparison of the second detection result DB 2  with the stored information MB 1  to MB 3 , a change amount of the second detection result DB 2  is larger than the threshold value T1 with respect to all stored information MB 1  to MB 3  so that it is understood that the position of the detection object is changed. Next, in a comparison of the third detection result DB 3  with the stored information MB 1  to MB 3 , a change amount of the third detection result DB 3  from the stored information MB 2  is equal to or smaller than the threshold value T1 so that it is understood that there is no change in position of the detection object. 
     From these results, it can be determined that the detection objects having the detection results DA 1 , DA 3  which substantially agree with the stored information MA 1 , MA 2  are objects not to be detected such as obstacles. It can be also determined that the detection object having the detection result DA 2  which does not agree with the stored information MA 1  to MA 3  is an object to be detected which is a movable body including a user and has moved from the position of 115 cm to the position of 80 cm. In the same manner, it can be determined that the detection object having the detection results DB 1 , DB 3  which substantially agree with the stored information MB 1 , MB 2  are objects not to be detected. It can be also determined that the detection object having the detection result DB 2  which does not agree with the stored information MB 1  to MB 3  is an object to be detected and has moved from the position of 120 cm to the position of 75 cm. 
     As in the case of an example shown in  FIG. 6 , the detection results DA 1 , DA 3  of the obstacle measured by the distance measuring sensor  20 A and the detection results DB 1 , DB 3  of the obstacle measured by the distance measuring sensor  20 B have relevance. In this embodiment, however, detection results DA 1  to DAn measured by the first distance measuring sensor  20 A and detection results DB 1  to DBn measured by the second distance measuring sensor  20 B are not associated with each other, and detection results DA 1  to DAn and detection results DB 1  to DBn are independently used for the determination on whether a detection object is an object to be detected or an object not to be detected. The reason is as follows. There is a case where an obstacle (object not to be detected) exists within one detection range at a position which can be detected by either one of the distance measuring sensors  20 A,  20 B, and a user (object to be detected) exists within the other detection range at the same distance position as the obstacle. In such a case, there is a possibility that the sensor erroneously detects the user as the obstacle. That is, as described later, the detection results DA 1  to DAn, DB 1  to DBn relating to the user which is an object to be detected and obtained by the distance measuring sensors  20 A,  20 B are detected in one operation zone  34  where both the first distance measuring sensor  20 A and the second distance measuring sensor  20 B can detect a detection object. Accordingly, the detection results DA 1  to DAn and the detection results DB 1  to DBn substantially agree with each other. However, unless the obstacle is in a stopped state in the operation zone  34  for some reason, the obstacle having the detection results DA 1  to DAn, DB 1  to DBn exists within either one of the detection range of the first distance measuring sensor  20 A or the detection range of the second distance measuring sensor  20 B. 
     Next, with reference to  FIG. 5 , the description is made with respect to setting of detection ranges of the distance measuring sensors  20 A,  20 B and a control performed by the controller  30 . 
     (Detail of Detection Range) 
     As shown in  FIG. 5 , the transmission parts  21 A,  21 B of the distance measuring sensors  20 A,  20 B transmit radio signals such that the radio signals spread radially. With reference to  FIG. 3 , the transmission parts  21 A,  21 B are mounted on the vehicle body  2  by way of the casing  14 . The transmission parts  21 A,  21 B are disposed such that radio signals are outputted along output centers C 1 , C 2  of the radio-signals which extend in the horizontal direction from the vehicle body  2 . The horizontal direction means a direction extending along the ground G on which a vehicle is parked. Also with reference to  FIG. 4 , the transmission parts  21 A,  21 B are disposed such that the output centers C 1 , C 2  of the radio-signals do not intersect with each other. That is, the output centers C 1 , C 2  respectively extend to both outer sides in an inclined manner in the directions so that the output centers C 1 , C 2  are gradually away from each other. With such a configuration, the respective distance measuring sensors  20 A,  20 B can perform both the detection of a detection object at a remote distance away from the vehicle body  2  and the detection of a detection object at a near distance close to the vehicle body  2 . 
     Conical output ranges which are formed by radio signals outputted from the transmission part  21 A,  21 B define detection ranges R 1 , R 2  of the distance measuring sensor  20 A,  20 B. The output center C 1  of the radio signal transmitted from the transmission part  21 A is a first detection center axis of the first detection range R 1  of the first distance measuring sensor  20 A. The output center C 2  of the radio signal transmitted from the transmission part  21 B is a second detection center axis of the second detection range R 2  of the second distance measuring sensor  20 B. The distance measuring sensors  20 A,  20 B are disposed such that a portion of the detection range R 1  of the first distance measuring sensor  20 A on a center side of the vehicle body  2  and a portion of the detection range R 2  of the second distance measuring sensor  20 B on the center side of the vehicle body  2  overlap with each other. An area where the detection range R 1  and the detection range R 2  overlap with each other forms one operation zone  34  where both the first distance measuring sensor  20 A and the second distance measuring sensor  20 B can detect detection objects. 
     In the whole region of the pair of detection ranges R 1 , R 2  including the operation zone  34 , detection objects are detected by the first distance measuring sensor  20 A or the second distance measuring sensor  20 B. Accordingly, the region defines an approach region  32  where the authentication of the key is started. In the approach region  32 , in a first zone  32   a  formed by excluding the operation zone  34  from the detection range R 1 , only the first distance measuring sensor  20 A can detect the detection object. In the second zone  32   b  formed by excluding the operation zone  34  from the detection range R 2 , only the second distance measuring sensor  20 B can detect a detection object. 
     The operation zone  34  is divided into two or more operation detection sub zones depending on a distance from the distance measuring sensors  20 A,  20 B. To be more specific, the operation zone  34  has a trigger sub zone  35  which is a first operation detection sub zone closest to the vehicle body  2 , and a start sub zone  36  which is a second operation detection sub zone positioned more remote from the vehicle body  2  than the trigger sub zone  35  is. The start sub zone  36  is further divided into a first portion  36   a  disposed on a side close to the distance measuring sensors  20 A,  20 B, and a second portion  36   b  disposed on a side remote from the distance measuring sensors  20 A,  20 B. 
     The trigger sub zone  35  is a zone where the distance measuring sensors  20 A,  20 B detect a state where a user who is a detection object approaches the vehicle body  2 . For example, the trigger sub zone  35  is set as a range between the position away from the vehicle body  2  by 20 cm to the position away from the vehicle body  2  by 40 cm. 
     The start sub zone  36  is a zone where the door  4  does not substantially hit a user even when the door  4  is opened and closed. The start sub zone  36  ranges between a position away from the vehicle body  2  by 120 cm and a position away from the vehicle body  2  by 50 cm, for example. The first portion  36   a  forms substantially a front half of the start sub zone  36 . For example, the first portion  36   a  ranges between the position away from the vehicle body  2  by 50 cm and a position away from the vehicle body  2  by 80 cm. In the first portion  36   a , depending on a height or a posture of a user, there still remains a possibility that the door  4  hits the user when the door  4  is opened or closed. The second portion  36   b  forms substantially a rear half of the start sub zone  36 . For example, the second portion  36   b  ranges between the position away from the vehicle body  2  by 80 cm and the position away from the vehicle body  2  by 120 cm. In the second portion  36   b , regardless of a height or a posture of the user, there is no possibility that the door  4  hits a user even when the door  4  is opened or closed. 
     A first non-operation sub zone  37  is set in the operation zone  34  on a vehicle body  2  side of the trigger sub zone  35 . With reference to  FIG. 3 , the first non-operation sub zone  37  is too close to the distance measuring sensors  20 A,  20 B so that a portion of the first non-operation sub zone  37  on a ground G side falls outside the detection ranges R 1 , R 2 . Accordingly, the first non-operation sub zone  37  is excluded from the operation detection sub zone. A second non-operation sub zone  38  having a predetermined width is set between the trigger sub zone  35  and the start sub zone  36 . The second non-operation sub zone  38  is a space for ensuring whether or not a detection object exists within either one of the trigger sub zone  35  or the start sub zone  36 . 
     The determination part  30   e  can determine that a detection object exists within the first zone  32   a  when only the first distance measuring sensor  20 A receives reflection signals. The determination part  30   e  can determine that a detection object exists within the second zone  32   b  when only the second distance measuring sensor  20 B receives reflection signals. Further, the determination part  30   e  can determine that a detection object exists within the operation zone  34  when both the first distance measuring sensor  20 A and the second distance measuring sensor  20 B receive reflection signals. As described previously, the measurement part  30   d  can measure a distance from the vehicle body to a detection object based on a time elapsed from the transmission of a radio signal to the reception of a reflection signal. Accordingly, the determination part  30   e  can determine the sub zone in which a detection object exists among the sub zones  35  to  38  of the operation zone  34  based on a distance measured by the measurement part  30   d.    
     As described above, in this embodiment, by making a portion of the first detection range R 1  of the first distance measuring sensor  20 A and a portion of the second detection range R 2  of the second distance measuring sensor  20 B overlap with each other, a specified operation zone having a fixed width direction can be set without using a special device. Accordingly, it is possible to stably detect an operation intention of a user with high accuracy and hence, an erroneous detection can be prevented with certainty. Further, the respective distance measuring sensors  20 A,  20 B are disposed such that the detection center axes C 1 , C 2  do not intersect with each other, that is, the detection center axes C 1 , C 2  respectively extend in an inclined manner toward outside from each other. Accordingly, the distance measuring sensors  20 A,  20 B can be easily assembled to the casing  14 . 
     The plurality of operation detection zones  35 ,  36  are set corresponding to distances from the distance measuring sensors  20 A,  20 B. Accordingly, only a detection object (user) which moves from a fixed direction passing the plurality of operation detection zones  35 ,  36  is detected as a legitimate operation intention. With such a configuration, it is possible to prevent an erroneous operation which may be caused due to the intrusion of an animal or a foreign substance into the operation zone from the lateral direction or an approach of a third party who does not know an operation method. 
     The distance measuring sensor  20 A,  20 B detects a detection object upon the reception of a reflection signal of a radio signal outputted in the horizontal direction. Accordingly, there is no possibility that the distance measuring sensor  20 A,  20 B receives a reflection signal from a member such as a ground which is disposed at a near distance from a vehicle and does not have a fixed height. Further, the distance measuring sensors  20 A,  20 B are mounted on the vehicle body  2  and hence, the same reference (distance) is used in detecting a detection object in both the case where an open control of the door  4  is performed and the case where a close control of the door  4  is performed. Accordingly, an erroneous detection which may be caused due to the detection unit can be prevented with certainty and hence, it is possible to rapidly detect an operation intention of a user with high accuracy. 
     (Detail of Control Performed by Controller) 
     In detecting the detection objects which exist within the approach region  32  excluding the trigger sub zone  35 , the controller  30  changes over transmission/reception functions of the distance measuring sensors  20 A,  20 B to a first transmission/reception mode by the transmission/reception mode switching part  30   c . In detecting a detection object which exists within the trigger sub zone  35 , the controller  30  changes over the transmission/reception functions of the distance measuring sensors  20 A,  20 B to a second transmission/reception mode by the transmission/reception mode switching part  30   c . That is, assume the case where the detection of a detection object is performed by the distance measuring sensors  20 A,  20 B in the first transmission/reception mode. In such a case, when the detection object exists within the trigger sub zone  35 , reflection signals are inputted to the reception parts  22 A,  22 B in a state where radio signals are outputted from the transmission parts  21 A,  21 B. Accordingly, radio signals outputted from the transmission parts  21 A,  21 B and reflection signals interfere with each other so that the reception parts  22 A,  22 B cannot distinguish the radio signals and the reflection signals from each other. For this reason, a distance from the vehicle body to a detection object is erroneously recognized or cannot be measured. In view of the above, in detecting a detection object which is at a near distance from the vehicle body and exists within the trigger sub zone  35 , by changing over the transmission/reception functions of the distance measuring sensors  20 A,  20 B to a second transmission/reception mode, it is possible to prevent a state where a distance is erroneously recognized or cannot be measured. Further, in detecting a detection object which is at a long distance and exists outside the trigger sub zone  35 , by changing over the transmission/reception functions of the distance measuring sensor  20 A,  20 B to the first transmission/reception mode, the detection object can be surely detected with high accuracy. 
     Upon the detection of a state where detection objects including a user and obstacles exist within the approach region  32 , the controller  30  starts the authentication of an electronic key. Then, when the electronic key is authenticated as a legitimate electronic key and a user enters the start sub zone  36 , the controller  30  drives the LEDs  28  in a blinking manner via the display control part  30   b  thus displaying an operation mark in a blinking manner on a ground as a spotlight. Accordingly, a user moves to the trigger sub zone  35  while being guided by the spotlight. An irradiation position I where the operation mark is generated by the LEDs  28  is set within the first non-operation sub zone  37 . In this manner, the operation mark allows the user to enter the trigger sub zone  35  with certainty by stepping on the operation mark with his/her foot. That is, although an operation of the user stepping on the operation mark displayed on the ground by the LEDs  28  is detected, in an actual operation, the body of the user (a part of the body of the user in the vicinity of his/her shin, for example) is detected when the user steps on the display. In this manner, the entry of the user into the trigger sub zone  35  is detected as an operation intention of the user and hence, the operation intention of the user can be detected with certainty without an erroneous detection. 
     When a user enters the trigger sub zone  35  passing through the start sub zone  36 , the controller  30  drives the LEDs  28  in a blinking manner via the display control part  30   b  thus displaying an operation mark in a blinking manner on a ground as a spotlight. In this manner, the operation mark prompts the user to perform an operation for starting an open control or a close control of the door  4 . That is, in performing an open control of the door  4 , the controller  30  drives the LEDs  28  in a blinking manner, and stands by until the user moves back to the start sub zone  36  from the trigger sub zone  35  in accordance with the operation mark displayed in a blinking manner on the ground. Then, upon the detection of a state where the user has moved back to the start sub zone  36 , the controller  30  controls the door opening and closing drive unit  12  so as to open the door  4 . Also in performing a close control of the door  4 , in the same manner as the open control, the controller  30  drives the LEDs  28  in a blinking manner, and stands by until the user moves back to the first portion  36   a  of the start sub zone  36  in accordance with the operation mark displayed in a blinking manner on the ground. In performing the close control further, also after the user has moved back to the first portion  36   a , the controller  30  further stands by in a state where the operation mark is displayed in a blinking manner until the user moves back to the second portion  36   b . Then, upon the detection of a state where the user has moved back to the second portion  36   b , the controller  30  controls the door opening and closing drive unit  12  so as to close the door  4 . 
     As described above, in this embodiment, by displaying the operation mark in a blinking manner on the ground by driving the LED  28  in a blinking manner, it is possible to allow a user to easily recognize an operation method and an operation timing and hence, the operability and the convenience of the user can be improved. Further, when an electronic key is authenticated and a user enters the operation zone, the LEDs  28  are driven in a blinking manner and the operation mark is displayed in a blinking manner on the ground by a spotlight. Accordingly, even when a third party who does not have the electronic key enters the operation zone, the LEDs  28  are not turned on or do not blink and hence, it is possible to prevent the wasteful power consumption of a battery. 
     In obstacle detection processing, exclusion cancellation processing, obstacle exclusion processing, and an approach mode which are described later, the processing is advanced to a next step by the controller  30  based on only one of detection results DA 1  to DAn of the distance measuring sensor  20 A and the detection results DB 1  to DBn of the distance measuring sensors  20 B. However, in the processing of a start mode, a trigger mode, a back mode, a close back mode  1 , and a close back mode  2  which are concrete operations for the open/close control of the door  4 , the processing is advanced to next step by the controller  30  on a condition that both the detection results DA 1  to DAn of the distance measuring sensor  20 A and the detection results DB 1  to DBn of the distance measuring sensors  20 B are detected. For example, in detecting a detection object which exists within the trigger sub zone  35 , the distance measuring sensors  20 A,  20 B are operated in a second transmission/reception mode. In this case, the controller  30  determines whether or not the processing is to be advanced to next step based on both the detection results DA 1  to DAn of the distance measuring sensor  20 A and the detection results DB 1  to DBn of the distance measuring sensors  20 B. 
     During such processing controls, the controller  30  determines whether a detection result of a detection object is a detection result of a user who is an object to be detected or a detection result of an obstacle which is an object not to be detected based on stored information MA 1  to MAn, MB 1  to MBn in the memory part  30   a . To be more specific, with respect to a detection object whose detection result is determined by the determination part  30   e  that there is no change in movement distance the set number of times continuously, the controller  30  stores distance information relating to such a detection object in the memory part  30   a  as obstacle information K 1  to Kn. Then, the obstacle information K 1  to Kn are excluded from the detection results DA 1  to DAn, DB 1  to DBn obtained by the distance measuring sensors  20 A,  20 B, and respective controls are performed based on only the detection results of other objects to be detected. Since the detection per se of the detection object which corresponds to the distance information stored in the memory part  30   a  as the obstacle information K 1  to Kn is continued, when there is no detection results DA 1  to DAn, DB 1  to DBn which agree with non-detection obstacle information K 1  to Kn, the subjected obstacle information K 1  to Kn is deleted from the memory part  30   a.    
     As described above, in this embodiment, based on the current detection results DA 1  to DAn, DB 1  to DBn and the last-time stored information MA 1  to MAn, MB 1  to MBn, out of the detection objects which are subjected to detection, it is possible to recognize obstacles whose detection results DA 1  to DAn, DB 1  to DBn do not change and a user whose detection results DA 1  to DAn, DB 1  to DBn change from each other. Accordingly, it is possible to prevent a state where the controller  30  is erroneously operated due to the presence of an obstacle thus erroneously performing an open/close control of the door  4  and hence, an open/close control of the door  4  can be realized with certainty by accurately determining movement of a user. The controller  30  performs an open/close control of the door  4  only when the determination part  30   e  detects a set movement of a detection object which is determined as an object to be detected. Accordingly, it is possible to detect an operation intention of a user stably and with high accuracy while preventing an erroneous operation which may be caused due to an animal or an obstacle other than the user. 
     Next, a control performed by the controller  30  is specifically described with reference to flowcharts shown in  FIG. 7A  to  FIG. 16 . An open/close control of the door  4  is started when the vehicle  1  is parked and an engine is stopped. 
     (General Flow) 
     As shown in  FIG. 7A , when the engine of the vehicle  1  is stopped, the controller  30  performs the initialization thereof in step S 1 , and stands by until a detection time for the distance measuring sensors  20 A,  20 B comes in step S 2 . Here, the detection time differs between a case where a detection object determined as an object to be detected exists within the approach region  32  and a case where a detection object determined as an object to be detected does not exist within the approach region  32 . The detection time for the case where the detection object exists within the approach region  32  is set shorter than the detection time for the case where the detection object does not exist within the approach region  32 . For example, the detection is performed for every 0.5 seconds when a detection object which is an object to be detected does not exist within the approach region  32 . On the other hand, the detection is performed for every 0.05 seconds when a detection object which is an object to be detected exists within the approach region  32 . 
     When a time counted by a built-in timer of the controller  30  reaches the detection time, in step S 3 , radio signals are outputted from both or one of the transmission parts  21 A,  21 B of the distance measuring sensors  20 A,  20 B in accordance with the instruction from the transmission/reception mode switching part  30   c . Then, in step S 4 , both or the other of the reception parts  22 A,  22 B of the distance measuring sensors  20 A,  20 B receive reflection signals. 
     Next, in step S 5 , obstacle detection processing is performed where the presence or the non-presence of obstacles in detected detection objects is determined, and the results are stored as obstacle information K 1  to Kn. Then, in step S 6 , exclusion cancellation processing is performed where specified obstacle information K 1  to Kn are excluded from the stored obstacle information K 1  to Kn and excluded information are included in (returned to) information relating to the object to be detected. Then, in step S 7 , obstacle exclusion processing is performed where only data relating to the object to be detected is set as an object to be determined by excluding detection results DA 1  to DAn, DB 1  to DBn which agree with the obstacle information K 1  to Kn. Then, as shown in  FIG. 7B , the controller  30  performs controls which correspond to the respective situations. 
     That is, in step S 8 , the controller  30  determines whether or not an approach mode is set. When the approach mode is set, the processing advances to step S 9  and the approach mode is performed. Then, the processing returns to step S 2  in  FIG. 7A . The processing advances to step S 10  when the approach mode is not set. 
     In step S 10 , the controller  30  determines whether or not a start mode is set. When the start mode is set, the processing advances to step S 11  and the start mode is performed. Then, the processing returns to step S 2  in  FIG. 7A . The processing advances to step S 12  when the start mode is not set. 
     In step S 12 , the controller  30  determines whether or not a trigger mode is set. When the trigger mode is set, the processing advances to step S 13  and the trigger mode is performed. Then, the processing returns to step S 2  in  FIG. 7A . The processing advances to step S 14  when the trigger mode is not set. 
     In step S 14 , the controller  30  determines whether or not a back mode is set. When the back mode is set, the processing advances to step S 15  and the back mode is performed. Then, the processing returns to step S 2  in  FIG. 7A . The processing advances to step S 16  when the back mode is not set. 
     In step S 16 , the controller  30  determines whether or not a close back first mode is set. When the close back first mode is set, the processing advances to step S 17  and the close back first mode is performed. Then, the processing returns to step S 2  in  FIG. 7A . The processing advances to step S 18  when the close back first mode is not set. 
     In step S 18 , the controller  30  determines whether or not a close back second mode is set. When the close back second mode is set, the processing advances to step S 19  and the close back second mode is performed. Then, the processing returns to step S 2  in  FIG. 7A . The processing advances to step S 20  when the close back second mode is not set. 
     Step S 20  is performed when detection objects including a user enter the approach region  32  in a state where obstacles which exist within the approach region  32  are not yet determined or in a state where the respective modes are not set. That is, in the case where the controller  30  determines that all detection objects which can be detected by the distance measuring sensors  20 A,  20 B are obstacles, when a detection object other than obstacles is detected within the approach region  32  in a state where none of modes in step S 8  to step S 19  is set, the processing advances to step S 21 . Then, the approach mode is set and the processing returns to step S 2  in  FIG. 7A . 
     (Obstacle Detection Processing) 
     As shown in  FIG. 8 , in the obstacle detection processing performed in step S 5 , the controller  30  compares individual detection results D (DA 1  to DAn, DB 1  to DBn) with all stored information M (MA 1  to MAn, MB 1  to MBn), and stores specified detection results D as obstacle information K. 
     To be more specific, firstly, in step S 5 - 1 , the calculation is performed so as to determine whether or not an absolute value of a numerical value obtained by subtracting stored information M which is detected last time from the detection result D is smaller than a threshold value T1 (2 cm, for example). When the absolute value is smaller than the threshold value T1, that is, when the detection object is not moved, the processing advances to step S 5 - 2  and a counter Na which is the number of times that it is determined that a detection object is an obstacle is incremented by 1. 
     Next, in step S 5 - 3 , the controller  30  determines whether or not the counter Na is larger than 4. The processing advances to step S 5 - 4  when the counter Na is larger than 4, and the processing advances to step S 5 - 6  when the counter Na is equal to or smaller than 4. In step S 5 - 4 , stored information M (detection result D) where the number of times that an absolute value of a numerical value obtained by subtracting stored information M from the detection result D becomes smaller than the threshold value T1 is more than the set number of times is stored in the memory part  30   a  as obstacle information K and, then, the processing advances to step S 5 - 6 . 
     On the other hand, when the absolute value of the numerical value obtained by subtracting the stored information M from the detection result D is equal to or larger than the threshold value T1 in step S 5 - 1 , the counter Na of the subjected detection result D is cleared (set to 0) in step S 5 - 5 , and the processing advances to step S 5 - 6 . 
     In this manner, when all comparisons between the current detection results D (DA 1  to DAn, DB 1  to DBn) and the stored information M (MA 1  to MAn, MB 1  to MBn) which are detected last time are finished, the detection result D is updated and stored in the memory part  30   a  as the stored information M in step S 5 - 6  and, then, the processing returns to the general flow shown in  FIGS. 7A and 7B . 
     As described above, when the determination part  30   e  continuously detects a state where a difference between a detection result (distance) D of a detection object and stored information (distance information) M is smaller than a set threshold value T1 the predetermined number of times, the determination part  30   e  determines that the subjected detection object is an object not to be detected. Accordingly, it is possible to determine whether or not a detected detection object is an object to be detected or an object not to be detected with certainty and, at the same time, it is possible to prevent a state where an object to be detected is erroneously determined as an object not to be detected. 
     (Exclusion Cancellation Processing) 
     As shown in  FIG. 9 , in the exclusion cancellation processing performed in step S 6 , the controller  30  compares individual obstacle information K (K 1  to Kn) with all detection results D (DA 1  to DAn, DB 1  to DBn). Then, the presence or the non-presence of the detection results D which agree with the obstacle information K are detected. When there is no detection result D which agrees with the obstacle information K, the subjected obstacle information K is excluded, and the detection result D is returned to detection result relating to an object to be detected. 
     To be more specific, firstly, in step S 6 - 1 , the calculation is performed so as to determine whether or not an absolute value of a numerical value obtained by subtracting a detection result D from obstacle information K is smaller than a threshold value T2 (2 cm, for example). When the absolute value is larger than the threshold value T2, that is, the detection result D of the detection object and the stored obstacle information K are not substantially equal to each other, the processing advances to step S 6 - 2 . On the other hand, when the detection result D and the obstacle information K are substantially equal to each other, the processing skips step to step S 6 - 4  and returns to the general flow. 
     When there is no detection result D which agrees with the obstacle information K, in step S 6 - 2 , a counter Nb which is the number of times that it is determined that there is no obstacle is incremented by 1. Then, in step S 6 - 3 , the detection is performed so as to determine whether or not the counter Nb is larger than 2. When the controller  30  determines that the counter Nb is larger than 2, the processing advances to step S 6 - 4 . On the other hand, when the controller  30  determines that the counter Nb is equal to or smaller than 2, the processing skips step S 6 - 4  and returns to the general flow. In step S 6 - 4 , obstacle information K by which it is determined that there is no obstacle is erased from the memory part  30   a  so that the exclusion of the obstacle information K from the detection result D of the detection object is canceled, and the processing returns to the general flow. 
     As described above, when the measurement results D of detection objects do not include obstacle information K to be excluded, the subjected detection object is set as an object to be detected and hence, even in the case where a user is determined as an object not to be detected when the user temporarily stops due to some reason, the determination is cancelled when the user restarts movement. Accordingly, an erroneous recognition of the object not to be detected can be prevented. 
     (Obstacle Exclusion Processing) 
     As shown in  FIG. 10 , in the obstacle exclusion processing performed in step S 7 , the controller  30  compares individual obstacle information (K 1  to Kn) with all detection results D (DA 1  to DAn, DB 1  to DBn), and excludes the detection results D which substantially agree with the obstacle information K from the obstacle information (K 1  to Kn). 
     To be more specific, firstly, in step S 7 - 1 , the calculation is performed so as to determine whether or not an absolute value of a numerical value obtained by subtracting the detection result D from the obstacle information K is smaller than a threshold value T3 (2 cm, for example). When the absolute value is smaller than the threshold value T3, the processing advances to step S 7 - 2  and the subjected detection result D is excluded (=0), and the processing returns to the general flow. On the other hand, when the absolute value is equal to or larger than the threshold value T3, the processing skips step S 7 - 2  and returns to the general flow. 
     As described above, the detection result D of a detection object which is continuously determined as an object not to be detected is excluded, and an object to be detected is determined based on detection results D of other detection objects. Accordingly, it is possible to increase a speed necessary for performing the determination and hence, movement of a legitimate object to be detected can be detected with high accuracy. 
     (Approach Mode) 
     As shown in  FIG. 11 , in the approach mode performed in step S 9 , the controller  30  starts the authentication of an electronic key when a detection object (including a user) other than obstacles enters the approach region  32 . 
     That is, in step S 9 - 1 , the controller  30  determines whether or not detection objects excluding obstacles enter the approach region  32 . When there is no entry of detection objects into the approach region  32 , the processing advances to step S 9 - 2  and the approach mode is cleared, and a counter Nc which is the number of times that it is determined that detection objects enter the approach region  32  is cleared. Then, the processing returns to the general flow. On the other hand, when there is an entry of the detection objects into the approach region  32 , the processing advances to step S 9 - 3 . 
     The counter Nc is incremented by 1 in step S 9 - 3  and, then, the controller  30  determines whether or not the counter Nc is larger than 2 in step S 9 - 4 . When the counter Nc is larger than 2, the processing advances to step S 9 - 5 . On the other hand, when the counter Nc is equal to or smaller than 2, the processing skips step S 9 - 5  and step S 9 - 6  and returns to the general flow. 
     In step S 9 - 5 , the controller  30  outputs a smart entry authentication request signal to the host ECU  5 . Upon the reception of such a signal, the host ECU  5  requests the electronic key to transmit an authentication code to the host ECU  5 , and compares the authentication code which the host ECU  5  receives with an authorized code registered in the host ECU  5 . Next, in step S 9 - 6 , the approach mode is cleared, the counter Nc is cleared and a start mode is set and, then, the processing returns to the general flow. 
     As described above, before an operation intention of a user is detected in the operation zone  34 , the approach of the user is detected by detecting the detection object in the approach region  32 , and the authentication of the key is performed. Accordingly, the detection of an operation intention of a user can be rapidly performed and hence, the convenience of a user can be enhanced. 
     (Start Mode) 
     As shown in  FIG. 12 , in the start mode performed in step S 11 , when an electronic key is authenticated as a legitimate electronic key and a user is positioned in the start sub zone  36 , the controller  30  prompts a user to perform an operation for opening or closing a door. 
     That is, in step S 11 - 1 , the controller  30  confirms whether or not the smart entry authentication is normally performed based on the reception of a signal outputted from the host ECU  5 . When the electronic key is normally authenticated, the processing advances to step S 11 - 2 . On the other hand, when the electronic key is not normally authenticated, the processing advances to step S 11 - 5 . 
     In step S 11 - 2 , the controller  30  reads whether the door  4  is in an open state or in a closed state based on a signal outputted from the door opening and closing drive unit  12 . Next, in step S 11 - 3 , the controller  30  determines whether or not a detection object is positioned within the start sub zone  36  (P 1  in  FIG. 5 , for example). When the detection object exists within the start sub zone  36 , the processing advances to step S 11 - 4 . On the other hand, when the detection object does not exist within the start sub zone  36 , the processing advances to step S 11 - 8 . 
     In step S 11 - 4 , the LEDs  28  are blinked through the display control part  30   b , a transmission/reception mode of the distance measuring sensor  20 A,  20 B is changed over to a second transmission/reception mode through the transmission/reception mode switching part  30   c , and the start mode is cleared. Further, a counter Nd which is the number of times that the smart entry authentication is rejected is cleared. A counter Ne which is the number of times that a detection object cannot be detected within the start sub zone  36  is cleared. The trigger mode is set. Then, the processing returns to the general flow. 
     When the smart entry authentication is rejected in step S 11 - 1 , the counter Nd is incremented by 1 in step S 11 - 5  and, then, the controller  30  determines whether or not the counter Nd is larger than 3 in step S 11 - 6 . When the counter Nd is larger than 3, the processing advances to step S 11 - 7  where the start mode is cleared and the counters Nd, Ne are cleared. Then, the processing returns to the general flow. On the other hand, when the counter Nd is equal to or smaller than 3, the processing skips step S 11 - 7  and returns to the general flow. 
     When a detection object cannot be detected within the start sub zone  36  in step S 11 - 3 , the counter Ne is incremented by 1 in step S 11 - 8  and, then, the controller  30  determines whether or not the counter Ne is larger than 20 in step S 11 - 9 . When the counter Ne is larger than 20, the processing advances to step S 11 - 10  where the start mode is cleared and the counters Nd, Ne are cleared. Then, the processing returns to the general flow. On the other hand, when the counter Ne is smaller than 20, the processing skips step S 11 - 10  and returns to the general flow. 
     (Trigger Mode) 
     As shown in  FIG. 13 , in the trigger mode performed in step S 13 , the controller  30  prompts a user to perform an operation for starting an open control or a close control of the door  4  when the user is positioned within the trigger sub zone  35 . 
     That is, in step S 13 - 1 , the controller  30  determines whether or not there is an entry of a detection object into the trigger sub zone  35  (P 2  in  FIG. 5 , for example). When there is an entry of the detection object into the trigger sub zone  35 , the processing advances to step S 13 - 2  where the LEDs  28  are turned on, and the trigger mode is cleared. Further, a counter Nf which is the number of times that a detection object cannot be detected within the trigger sub zone  35  is cleared. The back mode is set. A transmission/reception mode of the distance measuring sensor  20 A,  20 B is changed over to a first transmission/reception mode. Then, the processing returns to the general flow. 
     On the other hand, when the entry of the detection object into the trigger sub zone  35  cannot be detected in step S 13 - 1 , the counter Nf is incremented by 1 in step S 13 - 3  and, then, the controller  30  determines whether or not the counter Nf is larger than 20 in step S 13 - 4 . When the counter Nf is larger than 20, the processing advances to step S 13 - 5  where the LEDs  28  are turned off, and the trigger mode is cleared and, at the same time, the counter Nf is cleared. Further, a transmission/reception mode of the distance measuring sensors  20 A,  20 B is changed over to a first transmission/reception mode. Then, the processing returns to the general flow. On the other hand, when the counter Nf is smaller than 20, the processing skips step S 13 - 5  and returns to the general flow. 
     (Back Mode) 
     As shown in  FIG. 14 , in the back mode performed in step S 15 , the controller  30  prompts a user to move away from the vehicle  1  and to perform an operation for starting opening or closing of the door  4 . When a control for opening the door  4  is performed, an open control of the door  4  is performed. 
     That is, the LEDs  28  are blinked in step S 15 - 1 . Then, in step S 15 - 2 , the controller  30  determines whether an open control of the door  4  or a close control of the door  4  is to be performed based on a current open/close state of the door  4 . When the close control of the door  4  is selected, the processing advances to step S 15 - 3  where the back mode is cleared and a close back first mode is set. Then, the processing returns to the general flow. On the other hand, when the open control of the door  4  is selected, the processing advances to step S 15 - 4 . 
     In step S 15 - 4 , the controller  30  determines whether or not a detection object is moved back to the start sub zone  36  (P 3  in  FIG. 5 , for example). When the detection object is moved back to the start sub zone  36 , the processing advances to step S 15 - 5 . On the other hand, when the detection object is not moved back to the start sub zone  36 , the processing advances to step S 15 - 6 . 
     In step S 15 - 5 , the controller  30  drives the door opening and closing drive unit  12  for opening the door  4  by outputting a signal for opening the door  4  to the door opening and closing drive unit  12 , and the LEDs  28  are turned off. Further, the back mode is cleared. A counter Ng which is the number of times that the detection object cannot be detected within the start sub zone  36  is cleared. Then, the processing returns to the general flow. With such operations, the door  4  of the vehicle  1  is opened with respect to the vehicle body  2 . 
     In step S 15 - 6 , the counter Ng is incremented by 1 and, then, the controller  30  determines whether or not the counter Ng is larger than 20 in step S 15 - 7 . When the counter Ng is larger than 20, the processing advances to step S 15 - 8  where the LEDs  28  are turned off, the back mode is cleared, and the counter Ng is cleared. Then, the processing returns to the general flow. On the other hand, when the counter Ng is smaller than 20, the processing skips step S 15 - 8  and returns to the general flow. 
     (Close Back First Mode) 
     As shown in  FIG. 15 , in the close back first mode, the controller  30  confirms whether or not a user moves away from the vehicle  1 . 
     That is, in step S 17 - 1 , the controller  30  determines whether or not a detection object is moved back to the first portion  36   a  of the start sub zone  36  (P 3  in  FIG. 5 , for example). When the detection object is moved back to the first portion  36   a , the processing advances to step S 17 - 2  and the close back first mode is cleared. Further, a counter Nh which is the number of times that a detection object cannot be detected within the first portion  36   a  is cleared. The close back second mode is set. Then, the processing returns to the general flow. 
     On the other hand, when the detection object is not moved back to the first portion  36   a  in step S 17 - 1 , the counter Nh is incremented by 1 in step S 17 - 3  and, then, the controller  30  determines whether or not the counter Nh is larger than 20 in step S 17 - 4 . When the counter Nh is larger than 20, the processing advances to step S 17 - 5  where the LEDs  28  are turned off, the close back first mode is cleared and the counter Nh is cleared. Then, the processing returns to the general flow. On the other hand, when the counter Nh is smaller than 20, the processing skips step S 17 - 5  and returns to the general flow. 
     (Close Back Second Mode) 
     As shown in  FIG. 16 , in the close back second mode, the controller  30  confirms whether or not a user moves away from the vehicle  1  to a safe position and, then, the controller  30  performs an operation for closing the door  4 . 
     That is, in step S 19 - 1 , the controller  30  determines whether or not a detection object is moved back to the second portion  36   b  of the start sub zone  36  (P 4  in  FIG. 5 , for example). When the detection object is moved back to the second portion  36   b , the processing advances to step S 19 - 2  where the controller  30  drives the door opening and closing drive unit  12  for closing the door  4  by outputting a signal for closing the door  4  to the door opening and closing drive unit  12 , and the LEDs  28  are turned off. Further, the close back second mode is cleared, and a counter Ni which is the number of times that a detection object cannot be detected within the second portion  36   b  is cleared. Then, the processing returns to the general flow. With such operations, the door  4  of the vehicle  1  is closed with respect to the vehicle body  2 . 
     On the other hand, when the detection object is not moved back to the second portion  36   b  in step S 19 - 1 , the counter Ni is incremented by 1 in step S 19 - 3  and, then, the controller  30  determines whether or not the counter Ni is larger than 20 in step S 19 - 4 . When the counter Ni is larger than 20, the processing advances to step S 19 - 5  where the LEDs  28  are turned off, the close back second mode is cleared and the counter Ni is cleared. Then, the processing returns to the general flow. On the other hand, when the counter Ni is smaller than 20, the processing skips step S 19 - 5  and returns to the general flow. 
     According to the door opening and closing device  10  having such a configuration, as shown in  FIG. 5 , movement of a user which is a specified object to be detected can be detected with certainty among a plurality of detection objects including obstacles O 1 , O 2 . Further, an open control or a close control of the door  4  is performed upon the detection of a set specified movement of a user and hence, an erroneous operation can be prevented with certainty and, at the same time, the convenience of a user can be largely enhanced. 
     Second Embodiment 
       FIG. 17  shows a door opening and closing device  10  according to a second embodiment. The door opening and closing device  10  of the second embodiment differs from the door opening and closing device  10  of the first embodiment with respect to a point that a first distance measuring sensor  20 A and a second distance measuring sensor  20 B are disposed such that a first detection center axis C 1  of a first detection range R 1  and a second detection center axis C 2  of a second detection range R 2  intersect with each other. To be more specific, the distance measuring sensors  20 A,  20 B are disposed such that the distance measuring sensors  20 ,  20 B are inclined inwardly from each other. In the same manner as the first embodiment, the distance measuring sensors  20 A,  20 B are disposed such that a portion of the first detection range R 1  of the first distance measuring sensor  20 A and a portion of the second detection range R 2  of the second distance measuring sensor  20 B overlap with each other. 
     The door opening and closing device  10  of the second embodiment having such a configuration can acquire the manner of operation and advantageous effects substantially equal to the manner of operation and the advantageous effects of the door opening and closing device  10  of the first embodiment. Further, the ranges close to the centers C 1 , C 2  of the detection ranges R 1 , R 2  of the respective distance measuring sensors  20 A,  20 B are set as an operation zone  34  and hence, the accuracy of detection performed by the distance measuring sensors  20 A,  20 B can be enhanced. 
     The door opening and closing device  10  of the present invention is characterized by the configuration where a portion of the first detection range R 1  of the first distance measuring sensor  20 A and a portion of the second detection range R 2  of the second distance measuring sensor  20 B are made to overlap with each other, and an open/close control of the door  4  is performed when the set movement of a detection object is detected. Other configurations of the door opening and closing device  10  of the present invention are not limited to the configuration of the above-mentioned embodiments, and the various modifications are conceivable. 
     For example, in the above-mentioned first and second embodiments, the first and second (two) distance measuring sensors  20 A,  20 B are disposed as the detection parts. However, three or more detection parts may be disposed. In the above-mentioned first and second embodiments, the operation zone  34  is divided into two operation detection sub zones  35 ,  36 . However, the operation zone  34  may be divided into three or more operation detection sub zones. 
     In the embodiment, the determination part  30   e  compares a difference between the detection result D and the stored information M with the threshold value T1 and, when the determination part  30   e  determines that the detection result D and the stored information M are substantially equal to each other continuously the set number of times, the detection object is determined as an object not to be detected. However, the determination part  30   e  may determine the detection object as an object not to be detected when the determination part  30   e  detects that the detection result D and the stored information M are substantially equal to each other continuously for a set time. In the same manner, the determination part  30   e  may compare a difference between the detection result D and the obstacle information K with the threshold value T2 and, when the determination part  30   e  determines that the detection result D and the obstacle information K are not substantially equal to each other continuously for a set time, such obstacle information may be excluded from the obstacle information K. Further, the threshold values T1 to T3 based on which it is determined whether or not a detection result and obstacle information are substantially equal to each other may take different numerical values.