Patent Publication Number: US-2021180388-A1

Title: Opening and closing body drive device

Description:
TECHNICAL FIELD 
     The present invention relates to an opening and closing body drive device. 
     BACKGROUND ART 
     For drive devices each configured to open and close an opening and closing body by a drive section, electrically-powered drive sections are adopted in some cases as in opening and closing devices for back doors of vehicles. In a case where opening and closing of an opening and closing body is performed by the electrically-powered drive section, an attempt to drive the drive section further in a state where the opening and closing body has already moved to a fully-open position or a fully-closed position causes application of an excessive load onto the drive section. Thus, suppression of this excessive load is made by stopping the drive section in accordance with position information, using a pulse count value outputted from a pulse encoder for the position of the opening and closing body. 
     With the position information using a pulse count value, however, there occurs a case where the position information on the opening and closing body by the pulse count value deviates from the actual position of the opening and closing body due to, for example, collision of the opening and closing body with a foreign object. As a device that does not generate such a difference between the position information and the actual position of the opening and closing body as described above, a vehicular opening and closing body control device which determines that the opening and closing body has arrived at the fully-closed position, when a latch mechanism that locks movement of the opening and closing body turns into a half-latched state is disclosed in Patent Literature (hereinafter, referred to as “PTL”) 1, for example. 
     CITATION LIST 
     Patent Literature 
     
         
         PTL  1   
       
    
     Japanese Patent Application Laid-Open No. 2003-184429 
     SUMMARY OF INVENTION 
     Technical Problem 
     However, in a case where the opening and closing body drive section which drives the opening and closing body for opening and closing has a cause of preventing the opening and closing body from closing, such as a case where the opening and closing body drive section has a self-lock mechanism, it is difficult to move the opening and closing body to a fully-closed position by a driving force of the latch mechanism once the latch mechanism turns into the half-latched state. For this reason, unless the opening and closing body is moved to a closing direction such that the movement amount of the opening and closing body in the half-latched state becomes an appropriate movement amount, the attempt to move the opening and closing body further in the closing direction is made although the opening and closing body has already arrived at the fully-closed position, and thus the attempt results in application of an excessive load onto the opening and closing body drive section. 
     An object of the present invention is to provide an opening and closing body drive device capable of suppressing application of an excessive load onto an opening and closing body drive section at the time of driving an opening and closing body. 
     Solution to Problem 
     An opening and closing body drive device according to the present invention includes: 
     an opening and closing body; 
     a latch mechanism which causes a striker to engage with and/or disengage from a latch and to set the opening and closing body in a closed state or an open state; 
     an opening and closing body drive section which causes the opening and closing body to move between a fully-open position and a fully-closed position; 
     a control section which controls driving of the opening and closing body drive section; and 
     a movement sensor which outputs movement information on the opening and closing body, in which 
     the control section includes a middle reference count value which is a previously set count value when the latch mechanism is set in a predetermined state, and a pushing count value which causes the opening and closing body to be set in a fully-closed state by adding and/or subtracting the pushing count value to and/or from the middle reference count value, 
     the control section compares the current count value acquired by the movement sensor when the opening and closing body is set in the predetermined state with the latch mechanism, with the middle reference count value, and corrects the current count value, and 
     the control section determines that the opening and closing body has arrived at the fully-closed position when the opening and closing body has moved by an amount corresponding to the pushing count value from a count value corresponding to the middle reference count value, and stops driving of the opening and closing body drive section. 
     Advantageous Effects of Invention 
     According to the present invention, it is made possible to suppress application of an excessive load onto an opening and closing body drive section at the time of driving an opening and closing body. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic side view of an automobile including an opening and closing body drive device of an embodiment of the present invention, 
         FIG. 2  is a partial cross-sectional view of an exemplary main configuration of an opening and closing body drive section of the opening and closing body drive device of the present embodiment, 
         FIG. 3  is a cross-sectional view taken along an A-A line illustrated in  FIG. 2  which is a partial cross-sectional view of the exemplary main configuration of the opening and closing body drive section of the opening and closing body drive device of the present embodiment, 
         FIG. 4  is a partially enlarged side view of a rear portion of the automobile including the opening and closing body drive device of the present embodiment, 
         FIG. 5A  is a diagram illustrating a fully-latched state in a latch mechanism, 
         FIG. 5B  is a diagram illustrating how transition from the fully-latched state to a half-latched state is made in the latch mechanism, 
         FIG. 5C  is a diagram illustrating the half-latched state in the latch mechanism, 
         FIG. 5D  is a diagram illustrating an unlatched state in the latch mechanism, 
         FIG. 6  is a block diagram provided for describing a control system of the opening and closing body drive device, and 
         FIG. 7  is a flowchart provided for describing opening and closing body drive control in the opening and closing body drive device. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. Note that, an automobile which controls opening and closing of a back door is illustrated in the present embodiment, as an example of opening and closing drive device  1 , but opening and closing drive device  1  is also applicable to a device which controls opening and closing of a shutter, a sliding door or a hinged door installed at a structure such as a store, a garage, or foldable eaves disposed above an opening of a front of the structure. 
     [Overall Configuration of Opening and Closing Body Drive Device] 
       FIG. 1  is a schematic side view of an automobile including an opening and closing body drive device of the present embodiment. 
     As illustrated in  FIG. 1 , opening and closing body drive device  1  includes opening member  10  which includes opening  11 , opening and closing body  20 , opening and closing body drive section  30 , control section  50 , movement sensor  60  (see  FIG. 6 ), latch mechanism  70  (see  FIG. 4 ), and latch-state detection section  80  (see  FIG. 6 ). 
     Opening and closing body drive device  1  is a device which sets opening  11  of opening member  10  to an open state and a closed state by moving opening and closing body  20 . 
     [Opening Member] 
     Opening member  10  is provided in a rear portion with respect to a traveling direction of a vehicle body in an automobile using opening and closing body drive device  1  of the present embodiment. Opening member  10  is a vehicle body used in this automobile and opening  11  is formed by an edge portion of opening member  10 . The shape of opening  11  may be any shape including a rectangular shape, a circular shape and/or the like. 
     [Opening and Closing Body] 
     Opening and closing body  20  sets opening  11  of opening member  10  to an open state (see  FIG. 1 ) or a closed state (see  FIG. 4 ). At the rear side of a vehicle, the open state of opening  11  is a state where loading and unloading of an object, such as a luggage, into or from a rear trunk via opening  11  from outside is allowed. The closed state of opening  11  is a state where opening  11  is covered. In other words, when opening and closing body  20  is in a position to block this object, such as a luggage, from passing through opening  11  and moving to an opposite side, opening and closing body  20  can set opening  11  to the closed state. Further, when opening and closing body  20  is in a position to allow the object to pass through opening  11  and move to the opposite side, opening and closing body  20  can set opening  11  to the open state. 
     In the present embodiment, an upper side portion of opening and closing body  20  is turnably attached to a side of an upper edge portion of opening  11  in opening member  10  via a shaft portion serving as a hinge. Opening and closing body  20  sets opening  11  to the open state or closed state by pivoting such that a side of a lower side portion of opening and closing body  20  vertically moves around the shaft portion, and thus coming into contact with or separating from opening  11 . In the present embodiment, the positional change of opening and closing body  20  is achieved by the pivoting mechanism described above, but the mechanism for the positional change of opening and closing body  20  is not limited to pivoting and may be any mechanism as long as opening  11  can be set to the open state and closed state. 
     [Opening and Closing Body Drive Section] 
     Opening and closing body drive section  30  moves opening and closing body  20  in an opening direction or a closing direction with respect to opening  11  of opening member  10 . More than one opening and closing body drive section  30  may be provided. In the present embodiment, opening and closing body drive section  30  is provided one each in total of two to both left and right edges of opening and closing body  20  and both left and right edges of opening  11 . Opening and closing body  20  is relatively moved with respect to opening member  10  by moving opening and closing body  20  by driving respective opening and closing body drive sections  30 , and thus, opening  11  is set to the open state or the closed state. 
     As long as two opening and closing body drive sections  30  are capable of moving opening and closing body  20  in a direction in which opening  11  is set to the open state (opening direction) and in a direction in which opening  11  is set to the closed state (closing direction), respective opening and closing body drive sections  30  may drive opening and closing body  20  in the same direction with the same driving amount. Further, as long as two respective opening and closing body drive sections  30  are capable of moving opening and closing body  20  in the opening direction and in the closing direction, two opening and closing body drive sections  30  may be configured to drive opening and closing body  20  in different directions with different driving amounts. In the present embodiment, opening and closing body drive sections  30  are provided so as to perform the same driving in synchronization with each other. 
     Opening and closing body drive sections  30  are provided between opening member  10  and opening and closing body  20  such that opening and closing body  20  is relatively movable with respect to opening member  10 . In order for opening and closing body  20  to pivotably move with respect to opening member  10 , each opening and closing body drive section  30  is attached to opening member  10  so as to be capable of moving opening and closing body  20  by driving while pivoting with respect to opening member  10 , which is a vehicle body. 
     More specifically, each opening and closing body drive section  30  has a telescopic bar shape appearance and telescopically drives by relative movement of two portions. Each opening and closing body drive section  30  includes a driving main-body portion and a forward-backward moving section. The driving main-body portion is disposed on a side of one end portion of opening and closing body drive section  30  and is connected to a side of opening member  10 . The forward-backward moving section is disposed on a side of the other end portion of opening and closing body drive section  30  and is connected to a side of opening and closing body  20 . The forward-backward moving section is attached so as to be capable of protruding and receding from a side of the other end portion of the driving main-body portion. 
     Opening and closing body drive section  30  can move, by moving the forward-backward moving section forward and backward in a longitudinal direction of opening and closing body drive section  30  with respect to the driving main-body portion, opening and closing body  20  to a fully-closed position, i.e., the position where opening and closing body  20  completely covers opening  11 , and to a fully-open position, i.e., the position where opening  11  becomes a state where opening  11  is opened to a maximum extent. Each opening and closing body drive section  30  moves opening and closing body  20  in the opening direction or the closing direction by converting a rotary motion of a motor or the like into an extension and retraction motion in a linear direction. 
     Opening and closing body drive sections  30  are provided one each to both left and right ends of the rear potion of the automobile in total of two, but the number of opening and closing body drive sections  30  to be used is not particularly limited. Further, as long as opening and closing body drive section  30  enables opening and closing of opening and closing body  20 , the structure, shape and/or installation position of opening and closing body drive section  30  is not particularly limited. 
       FIG. 2  is a partial cross-sectional view of an exemplary main configuration of the opening and closing body drive section of the opening and closing body drive device of the present embodiment.  FIG. 3  is a cross-sectional view taken along an A-A line illustrated in  FIG. 2 . 
     In the present embodiment, opening and closing body drive section  30  includes main-body cylinder portion  31 , sliding cylinder portion  32 , opening and closing motor  33 , spindle  34 , spindle nut  35 , and energizing member  36  and/or the like in this embodiment. In opening and closing body drive section  30 , main-body cylinder portion  31 , opening and closing motor  33 , spindle  34 , and energizing member  36  and/or the like correspond to the driving main-body portion, and sliding cylinder portion  32  and spindle nut  35  correspond to the forward-backward moving section. 
     Main-body cylinder portion  31  is rotatably fixed to opening member  10  on a side of one end portion of main-body cylinder portion  31  and is opened on a side of the other end thereof. Sliding cylinder portion  32  is disposed inside of main-body cylinder portion  31  such that sliding cylinder portion  32  is slidingly movable in the longitudinal direction so as to protrude and recede from the side of the other end portion of main-body cylinder portion  31 . 
     Note that, fixing end portion  39  which covers the opening of one end side is provided on one end side of main-body cylinder portion  31 . Fixing end portion  39  includes a ball socket section. By connecting a ball of attachment member  12  to be fixed to opening member  10  to the ball socket section, main-body cylinder portion  31  is connected to opening member  10  in a freely turnable manner. 
     Opening and closing motor  33  drives to move the forward-backward moving section in the longitudinal direction with respect to the driving main-body section to extend and retract opening and closing body drive section  30 . Opening and closing motor  33  is a DC motor or an AC motor. In a case where opening and closing body drive device  1  is applied to an automobile, a DC motor is preferably adopted as opening and closing motor  33  in considering that a DC power supply of the automobile is used. Note that, opening and closing motor  33  is connected to control section  50 , and rotational driving of rotation of both forward rotation and reverse rotation is controlled by control section  50 . 
     Base-end portion  34   a  of spindle  34  which extends in the longitudinal direction and which is disposed inside of sliding cylinder portion  32  is connected to opening and closing motor  33 . 
     Spindle  34  is disposed coaxially with a rotation shaft of opening and closing motor  33  and coupled to the rotation shaft of opening and closing motor  33  by base-end portion  34   a.  Spindle  34  is disposed rotatably about the axis via a bearing at main-body cylinder portion  31  on a side of base-end portion  34   a.    
     Male-screw portion  341  is formed on an outer periphery of spindle  34 , that is, a spiral groove is formed, and male-screw portion  341  is screwed into spindle nut  35 . Spindle  34  corresponds to “shaft member” of the present invention. 
     Spindle nut  35  is driven by rotation of spindle  34  and moves on spindle  34  in a rotational axis direction of spindle  34 . More specifically, spindle nut  35  is capable of moving forward and backward in the rotational axis direction (length direction) by rotation of spindle  34 . Spindle nut  35  corresponds to “nut member” of the present invention. 
     More specifically, spindle nut  35  has a cylindrical body, and is provided, on an inner peripheral surface on a base end side, with female screw portion  35 a which is screwed with male screw portion  341  on the outer periphery of spindle  34 . 
     A leading-end portion of spindle  34  is disposed within spindle nut  35 , and bearing  41  is attached to the leading-end portion of spindle  34 . The leading-end portion of spindle  34  is longitudinally freely movable via bearing  41  within spindle nut  35 . 
     The other end portion of spindle nut  35  is fixed to slide end portion  40  via lid portion  37  together with the other end portion of sliding cylinder portion  32 . 
     Energizing member  36  energizes slide end portion  40  in a direction away from fixing end portion  39  and generates a force in a direction in which opening and closing body drive section  30  extends, such that the force acts against its own weight of opening and closing body  20  which is supported by opening and closing body drive section  30 . 
     When an operation to open opening and closing body  20  is performed by opening and closing body drive section  30 , i.e., when sliding cylinder portion  32  is moved in an extension direction, the load of opening and closing body  20 , which is applied due to its own weight of opening and closing body  20  when opening and closing motor  33  rotates spindle nut  35 , can be reduced by the force in the extension direction, which is generated by energizing member  36 . 
     Energizing member  36  herein is a coil spring and is disposed inside of sliding cylinder portion  32  and around spindle nut  35 . Energizing member  36  is interposed between coil base  38  and slide end portion  40 . 
     Although coil base  38  is fixed within main-body cylinder portion  31  by the energizing force of energizing member  36 , coil base  38  may be fixed by an adhesive, welding, and/or the like. 
     Sliding cylinder portion  32  is configured to protrude from the other end portion of main-body cylinder portion  31  and to extend and retract as an entirety of opening and closing body drive section  30  by sliding movement of sliding cylinder portion  32  in the longitudinal direction. 
     Sliding cylinder portion  32  has protruding portion  32   a  on an outer periphery of sliding cylinder portion  32 . 
     Guide cylinder portion  43  is disposed between sliding cylinder portion  32  and main-body cylinder portion  31  surrounding sliding cylinder portion  32 . 
     Guide cylinder portion  43  is disposed inside of main-body cylinder portion  31 , and the rotation in a direction about the axis is regulated by coil base  38 , and guide cylinder portion  43  includes guide portion  43   a  having a groove shape which extends longitudinally. In guide portion  43   a,  protruding portion  32   a  of sliding cylinder portion  32  is disposed. Although sliding cylinder portion  32  is longitudinally movable, the rotation of sliding cylinder portion  32  in a circumferential direction is regulated. For this reason, guide cylinder portion  43  regulates rotation of spindle nut  35  about the axis of spindle nut  35  fixed to slide end portion  40  together with the other end portion of slide cylinder portion  32 . Guide cylinder portion  43  corresponds to “rotation regulation portion” of the present invention. 
     In opening and closing body drive section  30  configured in the manner described above, spindle  34  rotates when opening and closing motor  33  is driven, and spindle nut  35  regulated to be movable only longitudinally via sliding cylinder portion  32  moves longitudinally by the rotation of spindle  34 . The forward-backward moving section moves with this movement of spindle nut  35 , and thus slide end portion  40  moves. Since opening and closing body  20  is connected to slide end portion  40 , opening and closing body  20  itself moves in the opening direction or closing direction and can be positioned in the fully-open position and the fully-closed position. 
     Opening and closing body drive section  30  includes a configuration in which spindle nut  35  is screwed with spindle  34 . This configuration is a self-lock mechanism which restricts movement of spindle nut  35  by friction between spindle  34  and spindle nut  35  even when a force to retract spindle nut  35  acts on spindle nut  35  from opening and closing body  20 . When movement of spindle nut  35  is restricted in the self-lock mechanism, movement of opening and closing body  20  in the closing direction is restricted. 
     Note that, the self-lock mechanism included in opening and closing body drive section  30  may be a configuration including a worm wheel and a worm gear, for example, or may be another configuration and/or the like. 
     [Latch Mechanism] 
       FIG. 4  is a partially enlarged side view of the rear portion of the automobile including the opening and closing body drive device of the present embodiment.  FIG. 5A  is a diagram illustrating a fully-latched state in a latch mechanism.  FIG. 5B  is a diagram illustrating how transition from the fully-latched state to a half-latched state is made in the latch mechanism.  FIG. 5C  is a diagram illustrating the half-latched state in the latch mechanism.  FIG. 5D  is a diagram illustrating an unlatched state in the latch mechanism. 
     As illustrated in  FIG. 4  and  FIG. 5A , latch mechanism  70  is a mechanism provided for performing movement regulation of opening and closing body  20  in a closed state with respect to opening  11 . Latch mechanism  70  includes latch  71 , striker  72 , rotation shaft  73 , pole  74 , and closure motor  75  (see  FIG. 6 ). 
     Latch  71  is a member engageable with striker  72  and provided on an inner-side lower end portion of opening and closing body  20 . Latch  71  includes base portion  71 A, first arm  71 B which extends from an upper end portion of base portion  71 A, and second arm  71 C which extends from a lower end portion of base portion  71 A. First arm  71 B and second arm  71 C each extend in the same direction (in the direction from left to right in  FIG. 5A ) from base portion  71 A. 
     Striker  72  is a member engageable with latch  71  and includes a rod-shape portion capable of entering recess portion  71 D formed by base portion  71 A, first arm  71 B, and second arm  71 C of latch  71 . For example, a portion parallel in the left and right direction in  FIG. 4  is the rod-shape portion of striker  72 . 
     Striker  72  is provided in a position such that the rod-shape portion is engaged with latch  71  in a fully-latched state when opening and closing body  20  is set in a closed state in a lower edge portion of opening  11  in opening member  10 . Note that, in a case where latch  71  is provided on a side of opening member  10 , striker  72  is provided on a side of opening and closing body  20 . 
     Latch  71  is configured to be rotatable about rotation shaft  73 . Latch  71  transitions between a fully-latched state (state in  FIG. 5A ), a half-latched state (state in  FIG. 5C ), and an unlatched state (state in  FIG. 5D ) by rotation due to a driving force of closure motor  75 , for example. 
     The fully-latched state is a fully-engaged state in which engagement is made such that striker  72  cannot be separated from recess portion  71 D of latch  71 . The half-latched state is a state in which the engagement force between latch  71  and striker  72  is smaller than the engagement force in the fully-latched state, and striker  72  can be readily separated from recess portion  71 D of latch  71  by application of an external force. The unlatched state is a state in which latch  71  and striker  72  are completely disengaged from each other. 
     Further, latch  71  may be energized by an energizing member (not illustrated) so as to rotate in a clockwise direction in  FIG. 5A  to  FIG. 5D . Thus, by controlling rotation of pole  74  to be described later, latch  71  can be caused to rotate from the fully-latched state to the unlatched state by the energizing force of the energizing member. 
     Pole  74  is a member capable of regulating rotation of latch  71  and is provided in a position where pole  74  is capable of coming into contact with any of first arm  71 B and second arm  71 C of latch  71 . Pole  74  is provided rotatably and is controlled under driving of closure motor  75  so as to be positioned in a first position (see  FIG. 5A ), a second position (see FIG.  5 C), and a third position (see  FIG. 5D ) from an upstream side in the clockwise direction. 
     An example of an operation in latch mechanism  70  will be described, herein. First, an operation for transition from the fully-latched state to the unlatched state will be described. 
     As illustrated in  FIG. 5A , when pole  74  is in the first position, a leading end of second arm  71 C in latch  71  in the fully-latched state comes into contact with pole  74 . Thus, rotation of latch  71  is regulated, and thus, the fully-latched state of latch  71  is maintained. 
     As illustrated in  FIG. 5B , when pole  74  rotates in the clockwise direction from the first position, the contact state with second arm  71 C is released. Latch  71  rotates in the clockwise direction by the driving force of closure motor  75 . 
     As illustrated in  FIG. 5C , when pole  74  further rotates and is positioned in the second position, pole  74  and first arm  71 B of latch  71  come into contact with each other. At this time, latch  71  is in the position of the half-latched state, and the half-latched state of latch  71  is maintained by regulation of rotation of latch  71  by pole  74 . 
     As illustrated in  FIG. 5D , when pole  74  further rotates and is positioned in the third position, the contact state between pole  74  and first arm  71 B of latch  71  is released. Thus, latch  71  rotates in the clockwise direction by the driving force of closure motor  75  and is positioned in the position of the unlatched state. More specifically, latch  71  and striker  72  are completely disengaged from each other. 
     Moreover, the engagement force between latch  71  and striker  72  in the half-latched state is small as compared with the engagement force in the fully-latched state even without rotation of pole  74  from the second position. For this reason, it is possible to disengage latch  71  and striker  72  from each other by the force to move opening and closing body  20  in the opening direction due to the driving force of opening and closing motor  33 . 
     Next, an operation for transition from the unlatched state to the fully-latched state will be described. First, as illustrated in  FIG. 5C  and  FIG. 5D , by movement of opening and closing body  20  by opening and closing drive section  30  from the position of the unlatched state, latch  71  is engaged with striker  72 , and thus, latch mechanism  70  is set in the half-latched state. 
     Further, under the control of control section  50  to be described later, opening and closing motor  33  and closure motor  75  operate, and as illustrated in  FIG. 5B , latch  71  is rotated in a counterclockwise direction so as to pull striker  72  into recess portion  71 D of latch  71 , and thus, latch mechanism  70  is set in the fully-latched state. 
     Note that, as long as latch mechanism  70  has a configuration capable of being driven by closure motor  75 , latch mechanism  70  may adopt any configuration. 
     [Configuration of Control System] 
       FIG. 6  is a block diagram illustrating a control system of opening and closing body drive device  1 . 
     In opening and closing body drive device  1 , the control system includes control section  50 , movement sensor  60 , and latch-state detection section  80 . The control system of opening and closing body drive device  1  controls opening and closing body  20  driven by opening and closing body drive section  30  including opening and closing motor  33 . 
     [Movement Sensor] 
     Movement sensor  60  detects movement of a position of opening and closing body  20  by detecting, for example, an operation of opening and closing body drive section  30 , and outputs movement information on opening and closing body  20 , which is a result of the detection, to control section  50 . 
     Movement sensor  60 , for example, includes Hall elements, and detects the operation of opening and closing body drive section  30 , that is, movement of the position of opening and closing body  20  by magnetically detecting a rotation state of opening and closing motor  33 . In this case, magnets are positioned circumferentially with different intervals on a disk provided on the rotation shaft of opening and closing motor  33 , and the Hall elements of movement sensor  60  are disposed in positions facing the magnets. Pulses are generated by capturing magnets moving along with the rotation of the rotation shaft of opening and closing motor  33  by the Hall elements. Control section  50  computes the position of opening and closing body  20  by a count value resulting from counting of the pulses and computes a driving speed of opening and closing body  20  by a change in the count value. 
     Movement sensor  60  counts the captured pulses, and control section  50  uses the count value as the movement information on opening and closing body  20  and makes the count value of the pulses usable for computing the position and the driving speed of opening and closing body  20  in control section  50 . Note that, it is also possible to adopt a configuration in which movement sensor  60  not only counts pulses but also computes the position and the driving speed of opening and closing body  20  based on the count value and outputs the result of computation to control section  50 . 
     Further, as long as movement sensor  60  is capable of detecting information on movement of the position of opening and closing body  20 , movement sensor  60  may adopt any configuration, and for example, movement sensor  60  may be configured to directly detect movement of the position of opening and closing body  20  without detecting an operation of opening and closing body drive section  30 . The detection method is not limited to the detection performed magnetically using Hall elements, and any method may be adopted as long as a count value in accordance with the position of opening and closing body  20  can be generated. Further, although movement sensor  60  has been described as a sensor that is provided separately from control section  50  to be described later, movement sensor  60  may be a sensor incorporated into control section  50 . 
     Note that, control section  50  may be configured to acquire a previously set count value from a storage section and/or the like, for example, in accordance with the result of output from movement sensor  60  in a case where movement sensor  60  outputs an output value other than a count value to control section  50 . 
     [Latch-State Detection Section] 
     Latch-state detection section  80  detects a latch state of latch mechanism  70  and outputs the result of detection to control section  50 . Latch-state detection section  80 , for example, detects a latch state, such as a half-latched state, based on a rotation state of latch  71 , for example. 
     Latch-state detection section  80  includes a half-latch detection switch that transitions to an ON state when latch  71  is set in the state in  FIG. 5C  and transitions to an OFF state when latch  71  is set in a state other than the state in  FIG. 5C . More specifically, latch mechanism  70  is provided with a link mechanism (not illustrated), and the half-latch detection switch switches between the ON state and the OFF state in accordance with the rotation state of latch  71  via the link mechanism. Thus, control section  50  to be described later determines whether or not latch mechanism  70  is in a half-latched state, based on a signal of the ON state and a signal of the OFF state which are outputted from latch-state detection section  80 . 
     Further, latch-state detection section  80  may include a switch capable of detecting the unlatched state and/or the fully-latched state. 
     Moreover, as long as latch-state detection section  80  is capable of detecting a latch state of latch mechanism  70 , latch-state detection section  80  may be any detection part. 
     Further, latch-state detection section  80  may not be provided in opening and closing body drive device  1 . In this case, opening and closing body drive device  1  may be configured to acquire a detection signal of the latch state from an outside. 
     [Control Section] 
     Control section  50  includes a central processing unit (CPU), a read only memory (ROM), and a random access memory (RAM) and/or the like. The CPU reads a program from the ROM in accordance with a processing content, loads the program into the RAM, and performs centralized control for operation of each block of opening and closing body drive device  1  in cooperation with the loaded program. At this time, various types of data stored in a storage section (illustration is omitted) are referred to. The storage section (illustration is omitted) is, for example, formed of a nonvolatile semiconductor memory (so-called flash memory) and/or a hard disk drive. Control section  50 , for example, may be incorporated into an electronic control unit (ECU) which controls each part of a vehicle, or may be mounted on opening and closing body drive section  30 . 
     Control section  50  acquires movement information on opening and closing body  20 , which is outputted from movement sensor  60 , and controls opening and closing movement of opening and closing body  20  via opening and closing body drive section  30 , using the movement information. More specifically, control section  50  determines the position of opening and closing body  20  based on the result of detection of movement sensor  60 . The position information on opening and closing body  20  determined by control section  50  is stored in the storage section (illustration is omitted) as needed. Further, in a case where an operation instruction and/or the like of opening and closing body  20  is present, control section  50  controls the driving speed of opening and closing body  20  in accordance with the current position information on opening and closing body  20 . 
     The position information, for example, corresponds to the count value of pulses outputted from movement sensor  60 , and each position is previously set in accordance with the count value. For example, in a case where the count value in the fully-closed position of opening and closing body  20  is 0 while the count value in the fully-open position of opening and closing body  20  is 1500, setting is made such that each position from the fully-closed position to the fully-open position increases within a range of count values 0 to 1500 as the position moves from the fully-closed position in the opening direction. 
     Control section  50  controls a driving speed of opening and closing body  20  based on the current count value, which is the current count value of pulses. For example, in a case where opening and closing body  20  is moved from the fully-open position to the fully-closed position, control section  50  controls the driving speed of opening and closing body  20  such that the driving speed of opening and closing body  20  becomes a predetermined target speed. 
     The predetermined target speed is a target speed which is previously set for opening and closing body  20 , and for example, the predetermined target speed can be a speed that makes it possible to avoid, by avoiding behavior in accordance with the position of opening and closing body  20 , pinching and/or collision at opening and closing body  20  that occurs due to movement of opening and closing body  20  during an opening and closing operation of opening and closing body  20 . 
     When opening and closing body  20  moves to the position where latch mechanism  70  is set in the half-latched state in the vicinity of the fully-closed position, control section  50 , for example, determines that latch mechanism  70  has been set in the half-latched state, based on the result of detection of latch-state detection section  80  to be described later. Control section  50  then drives closure motor  75  in latch mechanism  70 . 
     Opening and closing body drive section  30 , herein, includes a self-lock mechanism as described above. Even when a force for movement in the closing direction acts on opening and closing body  20  due to the driving force of closure motor  75  in a case where transition from the half-latched state to the fully-latched state is made, a force to prevent opening and closing body  20  from rotating acts on opening and closing body  20  due to the self-lock mechanism included in opening and closing body drive section  30 . Thus, the driving force of closure motor  75  is cancelled out by the force to lock by the self-lock mechanism, and movement of opening and closing body  20  in the closing direction is hindered. Further, examples of causes to hinder movement of opening and closing body  20  in the closing direction include a reactive force of a rubber piece and/or the like included in opening and closing body  20 , and/or a slope, bad weather, and/or the like in addition to the self-lock mechanism. 
     In this respect, control section  50  moves opening and closing body  20  to the fully-closed position, using the driving force of opening and closing motor  33  in addition to closure motor  75 . In this manner, latch mechanism  70  in the half-latched state can be surely set in the fully-latched state, and as a result, opening and closing body  20  can be moved to the fully-closed position. 
     Meanwhile, the half-latched position of opening and closing body  20  in the half-latched state is a position which deviates in the opening direction with respect to the fully-latched position of opening and closing body  20  in the fully-latched state. For this reason, the count value in movement sensor  60  becomes a count value that varies between the half-latched position and the fully-latched position. 
     In this embodiment, for example, an assumption is made herein that the following setting is made: the count value for the fully-closed position (fully-latched position) of opening and closing body  20  is 0, the count value for the fully-open position of opening and closing body  20  is 1500, and each position from the fully-closed position to the fully-open position increases within a range of count values 0 to 1500 as the position moves from the fully-closed position in the opening direction. Further, the count value for the half-latched position is set to  20  in this case. In this case, the movement amount of opening and closing body  20  required for causing a movement from the half-latched state to the fully-latched state becomes 20 count values. 
     There is, however, a possibility that the current count value in movement sensor  60  (hereinafter, referred to as “current count value”) becomes a value that deviates from the previously set count value at which latch  71  is set in the predetermined state (hereinafter, referred to as “middle reference count value”) as a result of an error possibly made by movement sensor  60  in counting of pulses, and/or movement of opening and closing body  20  caused by an external force in a sleep state of control section  50 , which possibly occurs, for example, while the opening and closing operation of opening and closing body  20  is repeatedly performed. Examples of cases where the current count value and the middle reference count value deviate from each other include a case where movement sensor  60  misses slight movement of opening and closing body  20  caused by an external force. 
     Control section  50  compares the current count value and the middle reference count value with each other when latch mechanism  70  is set in the predetermined state, for example, the half-latched state, according to the result of detection of latch-state detection section  80 . In a case where the current count value and the middle reference count value are different from each other, control section  50  corrects the current count value. Suppose that the predetermined state is the half-latched state, herein, since the count value for the half-latched position is  20 , the middle reference count value becomes  20 . In this case, correction of the current count value is made in this embodiment when the current count value for the half-latched state is a value not 20, e.g., 30. 
     As a correction method for the current count values, any method may be used, including, for example, replacement of the current count value with the count value of the middle reference count value, and/or addition of a difference between the current count value and the middle reference count value to the current count value. 
     After correcting the current count value, control section  50  stops driving of opening and closing body drive section  30  by determining that opening and closing body  20  has arrived at the fully-closed position, when opening and closing body  20  has moved by an amount corresponding to a pushing count value from a count value corresponding to the middle reference count value, that is, the corrected current count value. Note that, the count value corresponding to the middle reference count value need not necessarily be a value equal to the corrected current count value, and for example, may be a value around the corrected current count value, e.g., a value which deviates by roughly one or two count values from the corrected current count value. 
     The pushing count value is a count value corresponding to the movement amount required from the half-latched position to the fully-closed position. More specifically, opening and closing body  20  is set in the fully-closed state by adding or subtracting the pushing count value to or from the middle reference count value. 
     More specifically, control section  50  controls the driving speed of opening and closing body  20  such that the driving speed becomes 0 when opening and closing body  20  arrives at the fully-closed position, by causing opening and closing body  20  in the half-latched position to move at a driving speed corresponding to the corrected current count value and gradually reducing the driving speed. 
     When latch mechanism  70  is in the half-latched state, the middle reference count value becomes 20. However, suppose that, when opening and closing body  20  is moved with the current count value without the current count value correction of this embodiment without any change in a case where the current count value is, for example, 30, opening and closing body  20  attempts to move further even after opening and closing body  20  arrives at the fully-closed position. 
     For the case described above, in this embodiment, the current count value is corrected from  30  to  20 , and opening and closing body  20  is moved only by the amount corresponding to the corrected current count value. In this manner, the moving amount of opening and closing body  20  by opening and closing body drive section  30  from the half-latched state can be set to an appropriate moving amount. Thus, it is made possible to suppress a case where opening and closing motor  33  keeps rotating, for example, even after opening and closing body  20  arrives at the fully-closed position. For this reason, it is also made possible to suppress application of a load onto opening and closing motor  33  itself, such as application of an overcurrent to opening and closing motor  33 , and/or to suppress application of an excessive load onto opening and closing body drive section  30 , such as a case where spindle nut  35  and/or the like which rotates by rotation of opening and closing motor  33  spins around. 
     Further, the driving speed of opening and closing body  20  is controlled using the corrected current count value. In this embodiment, the driving speed of opening and closing body  20  is variably controlled in accordance with the position of opening and closing body  20 , which can be found from the corrected current count value. For example, a position in the vicinity of the half-latched position is a position immediately before the fully-closed position for opening and closing body  20 , and thus, the control is performed such that the speed of opening and closing body  20  is gradually reduced from a predetermined speed to the speed 0, which is equivalent to the stop state. More specifically, the driving speed of opening and closing body  20  varies in the vicinity of the half-latched position. Suppose that the driving speed of opening and closing body  20  is controlled without correction of the current count value, there occurs a phenomenon in which opening and closing body  20  operates at a driving speed faster than expected, for example. Meanwhile, in this embodiment, the current count value is corrected at the time of the half-latched state, and thus, the driving speed at the time of moving opening and closing body  20  from the half-latched state can be an appropriate driving speed. For this reason, occurrence of the phenomenon in which opening and closing body  20  operates at a driving speed faster than expected can be suppressed. 
     Note that, although a description of the predetermined state has been given as the half-latched state, as long as the position of opening and closing body  20  can be identified in accordance with the state of latch mechanism  70 , the predetermined state can be a state other than the half-latched state. 
     [Driving Control of Opening and Closing Body in Opening and Closing Body Drive Device] 
       FIG. 7  is a flowchart provided for describing opening and closing body drive control in opening and closing body drive device  1 . Note that, the control in  FIG. 7  assumes that the control is one that is performed when control section  50  receives an operation instruction to set opening and closing body  20  in the closing state, while opening and closing body  20  is in the open state. 
     As indicted in  FIG. 7 , control section  50  controls opening and closing body drive section  30  so as to drive opening and closing body  20  (step S 101 ). Next, control section  50  determines whether or not latch mechanism  70  is in the half-latched state, based on a result of detection of latch-state detection section  80  (step S 102 ). 
     In a case where latch mechanism  70  is not in the half-latched state as a result of the determination (step S 102 , NO), the processing of step S 102  is repeated. Meanwhile, in a case where latch mechanism  70  is in the half-latched state as the result of determination (step S 102 , YES), control section  50  determines whether or not the current count value is equal to the middle reference count value (step S 103 ). 
     In a case where the current count value is equal to the middle reference count value as a result of the determination (step S 103 , YES), control section  50  drives opening and closing body  20 , using the current count value (step S 104 ). Note that, in step S 104 , latch mechanism  70  is also driven in addition to driving of opening and closing body  20 . 
     Meanwhile, in a case where the current count value is not equal to the middle reference count value (step S 103 , NO), control section  50  corrects the current count value (step S 105 ). After step S 105 , the processing transitions to step S 104 . More specifically, control section  50  drives opening and closing body  20 , using the corrected current count value. 
     Next, control section  50  determines whether or not opening and closing body  20  has moved by the amount corresponding to the pushing count value (step S 106 ). In a case where opening and closing body  20  has not moved by the amount corresponding to the pushing count value as a result of the determination (step S 106 , NO), the processing of step S 106  is repeated. Meanwhile, in a case where opening and closing body  20  has moved by the amount corresponding to the pushing count value (step S 106 , YES), control section  50  stops driving of opening and closing body  20  (step S 107 ). This control is then terminated. 
     According to the present embodiment described above, when latch mechanism  70  is in a predetermined state, for example, in a half-latched state, the current count value is corrected in accordance with the current count value from movement sensor  60 . Thus, the current count value in movement sensor  60  can be made appropriate, and thus, the movement amount of opening and closing body  20  by opening and closing body drive section  30  from the half-latched state, which is the predetermined state, can be an appropriate movement amount, accordingly. For this reason, it is made possible to suppress a case where, for example, opening and closing motor  33  keeps rotating after opening and closing body  20  arrives at the fully-closed position, and thus, it is also made possible to suppress application of an excessive load onto opening and closing body drive section  30  at the time of driving of opening and closing body  20 . 
     Further, the driving speed of opening and closing body  20  is controlled, using the corrected current count value, and thus, the driving speed at the time of moving opening and closing body  20  from the half-latched state can be an appropriate driving speed. For this reason, occurrence of the phenomenon in which opening and closing body  20  operates at a driving speed faster than expected can be suppressed, and consequently, the accuracy of driving speed control for opening and closing body  20  can be improved. For this reason, driving that causes opening and closing body  20  to move relatively fast in a region where opening and closing body  20  moves relatively slow can be prevented. 
     Further, in the present embodiment, a signal of latch-state detection section  80  or the like, which is capable of accurately recognizing the position of opening and closing body  20 , is used, and thus, the current count value in movement sensor  60  can be made appropriate with a simple configuration. 
     The embodiment disclosed this time is only exemplary in every aspect and should be considered nonrestrictive. The scope of the present invention is indicated not by the description above but by claims, and it is intended that every change within meaning or range equivalent to the claims is included. 
     The embodiment of the present invention has been described thus far. Note that, the above description is only illustration of a preferred embodiment of the present invention, and the scope of the present invention is not limited to this. That is, the descriptions of the configuration of the above-mentioned device and the shape of each portion are only exemplary, and it is obvious that various changes and additions to these examples are possible within the scope of the present invention. 
     Industrial Applicability 
     The opening and closing body driving device according to the present invention is useful as an opening and closing body driving device capable of suppressing application of an excessive load onto an opening and closing body drive section at the time of driving of an opening and closing body. 
     REFERENCE SIGNS LIST 
     
         
           1  Opening and closing body drive device 
           10  Opening member 
           11  Opening 
           12  Attachment member 
           20  Opening and closing body 
           30  Opening and closing body drive section 
           31  Main-body cylinder portion 
           32  Sliding cylinder portion 
           32   a  Protruding portion 
           33  Opening and closing motor 
           34  Spindle 
           35  Spindle nut 
           36  Energizing member 
           37  Lid portion 
           38  Coil base 
           39  Fixing end portion 
           40  Slide end portion 
           41  Bearing 
           43  Guide tubular portion 
           43   a  Guide portion 
           50  Control section 
           60  Movement sensor 
           70  Latch mechanism 
           71  Latch 
           71 A Base portion 
           71 B First arm 
           71 C Second arm 
           71 D Recess portion 
           72  Striker 
           73  Rotation shaft 
           74  Pole 
           75  Closure motor 
           80  Latch-state detection section 
           341  Male-screw portion