Abstract:
A geared motor includes a stopper mechanism restricting the range of movement when the trailing gear rotates in a counter-clockwise direction. In the stopper mechanism, a first and a second angle ranges are obtained by dividing the range of angle of rotation of the trailing side gear by a virtual line passing through the center of rotation of the trailing side gear and the center of rotation of the driving side gear. In the first angle range in which the stopper touching part moves in a direction approaching the center of rotation of the driving side gear when the trailing side gear rotates in a counter-clockwise direction, the stopper touching part touches the part to be touched by the stopper. Thus, when the stopper mechanism is activated, the trailing side gear is subjected to a reaction force in a direction away from the driving side gear, making the meshing shallower.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a geared motor provided with a stopper mechanism in its gear train and a pointer type display device. 
       BACKGROUND ART 
       [0002]    In a pointer type display device and the like, a geared motor including a motor and a gear train disposed inside a case is used and a pointer is fixed to an output member of the geared motor (Patent Literature 1). In the geared motor described in Patent Literature 1, a stopper mechanism is proposed to structure for stopping a gear at a home position where a pointer indicates the zero point. More specifically, a structure has been proposed that, in a first gear integrally turned with an output member and a second gear meshed with the first gear for driving the first gear, a gear side protruded part is provided at a substantially middle position in a radial direction of the first gear and a support member side protruded part is provided in a support member on an imaginary line passing through a turning center of the first gear and a rotation center of the second gear and, when the first gear is turned to the position where the pointer indicates the zero point, the gear side protruded part and the support member side protruded part are abutted with each other. 
       CITATION LIST 
     Patent Literature 
       [0003]    [PTL 1] Japanese Patent Laid-Open No. 2001-327149 
       SUMMARY OF THE INVENTION 
     Technical Problem 
       [0004]    However, in a case that the pointer is returned to the home position, when the gear side protruded part provided in the first gear is abutted with the support member side protruded part, the first gear is rebounded in a reverse direction to cause the pointer to be shaken. In other words, in a case that the pointer is to be returned to the home position, a gear connected with the second gear, a rotor of a motor part and the like are also turned and thus, when the stopper mechanism is operated and the first gear is stopped, the second gear is also going to be stopped. However, the second gear receives an inertia torque from the rotor and the like in an opposite direction and the inertia torque is transmitted to the first gear and, as a result, the first gear is rebounded. 
         [0005]    Therefore, in view of the problem described above, an objective of the present invention is to provide a geared motor and a pointer type display device in which rebounding of a gear is restrained even when a stopper mechanism provided in a gear train is operated. 
       Solution to Problem 
       [0006]    To achieve the above mentioned objective, the present invention provides a geared motor including a motor part, an output member, a gear train which includes a first gear and a second gear meshed with the first gear to drive the first gear, the gear train being structured to transmit rotation of the motor part to the output member, a support member which supports the motor part, the output member and the gear train, and a stopper mechanism which comprises a stopper abutting part provided in the first gear and a stopper abutted part provided in the support member. The stopper mechanism is structured so that, when the first gear is turned to one side in a circumferential direction, the stopper abutting part is abutted with the stopper abutted part to restrict a movable range of turning of the first gear to the one side, and the stopper abutted part is provided at a position where the first gear is applied with a reaction force in a direction separated from the second gear when the first gear is turned to the one side and the stopper abutting part is abutted with the stopper abutted part. 
         [0007]    In the present invention, when the stopper abutting part of the first gear is turned to one side in the circumferential direction and is abutted with a stopper abutted part of the support member, the first gear receives a reaction force in a direction separated from the second gear. Therefore, engagement of the first gear with the second gear becomes shallow and thus, when the stopper mechanism is operated and the first gear and the second gear are stopped, an inertia torque in an opposite direction from the second gear is hard to be transmitted to the first gear. Accordingly, rebounding of the first gear can be restrained. 
         [0008]    In the present invention, it is preferable that a turning angular range of the first gear is divided into a first angular range and a second angular range by an imaginary line passing through a turning center of the first gear and a rotation center of the second gear and, in the first angular range where the stopper abutting part is moved in a direction coming close to the rotation center of the second gear, the stopper mechanism is structured so that, when the first gear is turned to the one side, the stopper abutting part is abutted with the stopper abutted part in an angular range of 90±60° with respect to the imaginary line when viewed from the rotation center of the first gear. According to this structure, when the stopper abutting part is turned to one side in the circumferential direction and is abutted with the stopper abutted part of the support member, the first gear is easy to receive a reaction force in a direction separated from the second gear. Therefore, engagement of the first gear with the second gear becomes shallow and thus an inertia torque in an opposite direction from the second gear is hard to be transmitted to the first gear. Accordingly, rebounding of the first gear can be restrained. 
         [0009]    In the present invention, it is preferable that the stopper mechanism is structured so that the stopper abutting part is abutted with the stopper abutted part in an angular range of 90±10° with respect to the imaginary line when viewed from the rotation center of the first gear. According to this structure, when the stopper abutting part is turned to the one side in the circumferential direction and is abutted with the stopper abutted part of the support member, the first gear is further easily received with a reaction force in a direction separated from the second gear. Therefore, engagement of the first gear with the second gear becomes further shallow and thus an inertia torque in an opposite direction from the second gear is hard to be transmitted to the first gear. Accordingly, rebounding of the first gear can be restrained. 
         [0010]    In the present invention, it is preferable that the first gear is provided with a plate-shaped part in which teeth are formed on its outer peripheral face and a body part which is protruded from the plate-shaped part in a turning center axial line direction of the first gear at a center of the first gear, and the stopper abutting part is an one side end part located on the one side of the gear side protruded part which is integrally formed with the body part on an outer peripheral face of the body part. According to this structure, the stopper abutting part (one side end part of the gear side protruded part) is abutted with the stopper abutted part at a position near to the turning center axial line of the first gear. Therefore, when the stopper mechanism is operated, collision energy applied to the first gear is small and thus rebounding of the first gear can be restrained. 
         [0011]    In the present invention, the structure may be adopted that the gear side protruded part is integrally formed with the plate-shaped part. According to this structure, the strength of the gear side protruded part can be increased. 
         [0012]    In the present invention, it is preferable that the plate-shaped part is formed with plate-shaped springs which are elastically abutted with the support member in the turning center axial line direction of the first gear at a plurality of positions in a circumferential direction, and the gear side protruded part is formed at an angular position corresponding to a position between the plate-shaped springs adjacent to each other in the circumferential direction. According to this structure, even when the plate-shaped spring is formed in the plate-shaped part of the first gear, restriction of the position for forming the gear side protruded part is small. Therefore, the gear side protruded part is easily provided on an inner side in the radial direction. 
         [0013]    In the present invention, it is preferable that the support member includes a cylindrical tube part with which the plate-shaped spring is abutted, and the stopper abutted part is integrally formed with the cylindrical tube part on an inner side in a radial direction of the cylindrical tube part. According to this structure, the strength of the stopper abutted part can be increased. 
         [0014]    In the present invention, it is preferable that the stopper abutted part is the other side end part located on the other side in the circumferential direction of a support body side protruded part which is protruded from an outer side in the radial direction toward an inner side in the radial direction and toward a turning center of the first gear, and a width dimension in the circumferential direction on an inner side in the radial direction of the support body side protruded part is set to be narrower than that on its outer side in the radial direction. According to this structure, even in a case that the width in the circumferential direction of the support body side protruded part is set to be wide to some extent for securing strength, when the stopper mechanism is operated, the stopper abutting part and the stopper abutted part are abutted with each other at a position which is near to the turning center of the first gear. Therefore, when the stopper mechanism is operated, collision energy applied to the first gear is small and thus rebounding of the first gear can be restrained. Further, a movable range to the one side of the first gear can be made wide. 
         [0015]    In the present invention, it is preferable that the first gear and the output member are integrally turned with each other. According to this structure, a movable range of the output member can be directly restricted by the stopper mechanism. 
         [0016]    The geared motor in accordance with the present invention may be used, for example, in a pointer type display device and, in this case, the pointer type display device has a pointer which is held by the output member. In this case, it may be structured that a stopping position by the stopper mechanism corresponds to a home position of the pointer. 
       Effects of the Invention 
       [0017]    In the present invention, when the stopper abutting part of the first gear is turned to one side in the circumferential direction and is abutted with the stopper abutted part of the support member, the first gear receives a reaction force in a direction separated from the second gear and thus engagement of the first gear with the second gear becomes shallow. Therefore, when the stopper mechanism is operated and the first gear and the second gear are stopped, an inertia torque in an opposite direction from the second gear is hard to be transmitted to the first gear. Accordingly, rebounding of the first gear can be restrained. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0018]      FIGS. 1 a  and 1 b    are explanatory views showing a geared motor to which the present invention is applied. 
           [0019]      FIG. 2  is a cross-sectional view showing a geared motor to which the present invention is applied and which is cut at a position passing a gear train. 
           [0020]      FIGS. 3 a  and 3 b    are exploded perspective views showing a geared motor to which the present invention is applied and which is viewed from an output side. 
           [0021]      FIGS. 4 a  and 4 b    are exploded perspective views showing a geared motor to which the present invention is applied and which is viewed from an opposite-to-output side. 
           [0022]      FIGS. 5 a , 5 b  and 5 c    are explanatory views showing a driven gear which is used in a geared motor to which the present invention is applied. 
           [0023]      FIG. 6  is an explanatory view showing a planar structure of a stopper mechanism which is structured in a geared motor to which the present invention is applied. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0024]    A geared motor and a pointer type display device to which the present invention is applied will be described below with reference to the accompanying drawings. In the following descriptions, in a direction where a turning center axial line “L” of an output member  10  is extended, one side to which the output member  10  is protruded is referred to as an output side “L 1 ” and an opposite side (the other side) to the side where the output member  10  is protruded is referred to as an opposite-to-output side “L 2 ”. Further, an axial line of a rotor  5  in a motor part  1  is a rotation center axial line “L 0 ” and an axial line of a drive side gear  41  of a gear train  4  is a rotation center axial line “L 5 ”. Further, for convenience, one side of each of the rotation center axial lines “L 0 ” and “L 5 ” is referred to as the output side “L 1 ”, and the other side of each of the rotation center axial lines “L 0 ” and “L 5 ” is referred to as an opposite-to-output side “L 2 ”. 
       (Entire Structure of Pointer Type Display Device) 
       [0025]      FIGS. 1 a  and 1 b    are explanatory views showing a geared motor  100  to which the present invention is applied.  FIG. 1 a    is a perspective view showing a geared motor  100  which is viewed from an output side “L 1 ”, and  FIG. 1 b    is a perspective view showing the geared motor  100  which is viewed from an opposite-to-output side “L 2 ”.  FIG. 2  is a cross-sectional view showing the geared motor  100  to which the present invention is applied and which is cut at a position passing a gear train  4 .  FIGS. 3 a  and 3 b    are exploded perspective views showing the geared motor  100  to which the present invention is applied and which is viewed from an output side “L 1 ”.  FIG. 3 a    is an exploded perspective view showing a state that a second case member  22  is separated from a first case member  21 , and  FIG. 3 b    is an exploded perspective view showing a state that a gear train  4  and the like are detached from the first case member  21 .  FIGS. 4 a  and 4 b    are exploded perspective views showing a geared motor  100  to which the present invention is applied and which is viewed from an opposite-to-output side.  FIG. 4 a    is an exploded perspective view showing a state that the first case member  21  is separated from the second case member  22 , and  FIG. 4 b    is an exploded perspective view showing a state that the gear train  4  and the like are detached from the second case member  22 . 
         [0026]    The geared motor  100  shown in  FIGS. 1 a  through 4 b    is structured so that a shaft-shaped output member  10  is protruded from a case  2  to the output side “L 1 ” in the turning center axial line “L” direction. The geared motor  100  in this embodiment is used in a pointer type display device  200  and, as shown in  FIG. 1   a,  a pointer  11  is connected with the output member  10 . 
         [0027]    The case  2  includes a first case member  21  formed in a substantially circular shape when viewed in the turning center axial line “L” direction and a second case member  22  formed in a substantially circular shape when viewed in the turning center axial line “L” direction. The second case member  22  is overlapped with the first case member  21  from the output side “L 1 ”. The case  2  is a support member which supports a motor part  1 , a gear train  4  and an output member  10  described below. 
         [0028]    The first case member  21  is provided with an end plate part  210  and a side plate part  211  in a tube shape which is protruded to the output side “L 1 ” from an outer side edge of the end plate part  210 . An outer peripheral face of the side plate part  211  is formed with a hook  219  at a plurality of positions in a circumferential direction. The second case member  22  is provided with an end plate part  220  and a side plate part  221  in a tube shape which is protruded to the opposite-to-output side “L 2 ” from an outer side edge of the end plate part  220 . An engaging protruded part  229  is formed in the side plate part  221  at a plurality of positions in the circumferential direction. Therefore, when the hooks  219  and the engaging protruded parts  229  are engaged with each other and the first case member  21  and the second case member  22  are combined with each other, the case  2  is structured. In the first case member  21 , a protruded part  212  which is, for example, used for fixing the geared motor  100  is protruded toward the opposite-to-output side “L 2 ” from the end plate part  210 . Further, in the second case member  22 , protruded parts  222  which are, for example, used for fixing the geared motor  100  are protruded toward the output side “L 1 ” from the end plate part  220 . 
       (Structure of Motor Part  1 ) 
       [0029]    The geared motor  100  includes a motor part  1  in an inside of the case  2  and the motor part  1  is a drive source for the output member  10 . The motor part  1  is a stepping motor which includes a rotor  5  and a stator  6  disposed around the rotor  5 . The rotor  5  is rotatably supported by a support shaft  51 . An end part on the opposite-to-output side “L 2 ” of the support shaft  51  is held by a shaft hole  213   a  formed in the end plate part  210  of the first case member  21 , and an end part on the output side “L 1 ” of the support shaft  51  is held by a shaft hole  223   a  formed in the end plate part  220  of the second case member  22 . 
         [0030]    The rotor  5  includes a pinion  58  provided at an end part on the opposite-to-output side “L 2 ” in a rotation center axial line “L 0 ” direction and a magnet  50  formed in a cylindrical tube shape. An “S”-pole and an “N”-pole are alternately formed at equal angular intervals on an outer peripheral face of the magnet  50 . In this embodiment, the magnet  50  and the pinion  58  made of resin are integrated each other by insert molding. The stator  6  includes a stator core  60  provided with a plurality of salient poles which face the outer peripheral face of the magnet  50  with a gap space therebetween. A coil  8  is wound around each of two salient poles (main pole) of a plurality of the salient poles through a coil bobbin  7 . The stator core  60  is formed in a plate shape and is structured by laminating a plurality of magnetic plates which are punched in a predetermined shape. The stator core  60  is formed with a hole  68  through which a support shaft  410  of a drive side gear  41  described below is penetrated. The coil bobbin  7  holds a plurality of terminal pins  70  to which end parts of the coil  8  are bound and connected. An end part of the terminal pin  70  is protruded to the output side “L 1 ” through a hole  223   d  which is formed in the end plate part  220  of the second case member  22 . 
         [0031]    The geared motor  100  includes a gear train  4  structured to decelerate rotation of the rotor  5  and transmit it to the output member  10 . In this embodiment, the gear train  4  includes the pinion  58 , a drive side gear  41  (second gear in the present invention) meshing with the pinion  58 , and a driven gear  42  (first gear in the present invention) meshing with the drive side gear  41 . The drive side gear  41  is provided with a large diameter gear  411  meshing with the pinion  58  of the rotor  5  and a small diameter gear  412  coaxially formed with the large diameter gear  411 . The drive side gear  41  is rotatably supported by the support shaft  410 . An end part on the opposite-to-output side “L 2 ” of the support shaft  410  is held by a shaft hole  213   b  formed in the end plate part  210  of the first case member  21 . An end part on the output side “L 1 ” of the support shaft  410  is held by a shaft hole  223   b  formed in a column part  226  which is formed in the end plate part  220  of the second case member  22 . The driven gear  42  is provided with a plate-shaped part  43  in a circular plate shape whose outer peripheral face is formed with outer teeth  431  meshing with the small diameter gear  412 . 
       (Structure of Driven Gear  42 ) 
       [0032]      FIGS. 5 a , 5 b  and 5 c    are explanatory views showing the driven gear  42  which is used in the geared motor  100  to which the present invention is applied.  FIG. 5 a    is a perspective view showing the driven gear  42  which is viewed in an oblique direction on the output side “L 1 ”,  FIG. 5 b    is a plan view showing the driven gear  42  which is viewed in an oblique direction on the opposite-to-output side “L 2 ”, and  FIG. 5 c    is a side view showing the driven gear  42 . 
         [0033]    The driven gear  42  is a final gear structured to transmit its rotation to the output member  10  and to be integrally turned with the output member  10 . The driven gear  42  is structured as described below. 
         [0034]    In  FIGS. 5 a , 5 b  and 5 c   , the driven gear  42  is provided with a shaft-shaped body part  44 , which is protruded from the center of the plate-shaped part  43  to the output side “L 1 ”, and a circular protruded part  45  which is protruded from the center of the plate-shaped part  43  to the opposite-to-output side “L 2 ”. A shaft hole  440  comprised of a through hole to which the output member  10  is fitted is provided in the body part  44  and the circular protruded part  45 . The driven gear  42  and the output member  10  are integrally turned with each other. 
         [0035]    The plate-shaped part  43  is formed with a groove  47  which penetrates the plate-shaped part  43  in the turning center axial line “L” direction. The groove  47  is extended to one side around the turning center axial line “L” and then bent in a “U”-shape and extended to the other side in the circumferential direction. As a result, a portion of the plate-shaped part  43  which is surrounded by the groove  47  is formed to be a plate-shaped spring  46  whose one end in the circumferential direction is connected with the plate-shaped part  43 . A protruded part  461  protruded toward the output side “L 1 ” is formed on a tip end side of the plate-shaped spring  46 . In this embodiment, the plate-shaped spring  46  is formed at two positions with equal angular intervals in the circumferential direction so as to extend in the same direction. An angular pitch of two plate-shaped springs  46  is 180°. 
         [0036]    The plate-shaped part  43  is formed with a gear side protruded part  48  protruded to the output side “Li” and to an outer side in a radial direction at an angular position interposed in the circumferential direction between two plate-shaped springs  46 . The gear side protruded part  48  structures a stopper mechanism  9  which restricts a movable range by abutting with a support body side protruded part  28  described below when the driven gear  42  is turned in a counterclockwise direction CCW (one side in the circumferential direction). 
       (Support Structure for Driven Gear  42  and Output Member  10 ) 
       [0037]    As shown in  FIGS. 3 a    through  4   b,  the end plate part  210  of the first case member  21  is formed with a cylindrical tube part  215  protruded to the output side “L 1 ” and a cylindrical tube part  216  protruded to the opposite-to-output side “L 2 ”. The cylindrical tube parts  215  and  216  are formed with shaft holes  215   a  and  216   a  which turnably support an opposite-to-output side end part of the output member 
         [0038]    On the other hand, the end plate part  220  of the second case member  22  is formed with a cylindrical tube part  225  which is protruded to the output side “L 1 ”. The cylindrical tube part  225  is formed with a shaft hole  225   a  which turnably supports an output side portion of the output member  10 . 
         [0039]    A face on the opposite-to-output side “L 2 ” of the end plate part  220  of the second case member  22  is formed with a cylindrical tube part  227  into which the body part  44  of the driven gear  42  is entered and plate-shaped ribs  224  which are extended from the cylindrical tube part  227  toward outer sides in a radial direction. An inner diameter of the cylindrical tube part  227  is larger than an outer diameter of the body part  44  of the driven gear  42 , and an inner face of the cylindrical tube part  227  does not contact with the body part  44  of the driven gear  42 . The ribs  224  are formed at four positions with equal angular intervals around the cylindrical tube part  227 . Three ribs  224   a,    224   b  and  224   c  of four ribs  224  are connected with the side plate part  221  and the remaining one rib  224   d  is connected with the column part  226  formed with the shaft hole  223   b.    
         [0040]    In this embodiment, the circular protruded part  45  of the driven gear  42  is abutted with the cylindrical tube part  215  of the first case member  21  and movement of the driven gear  42  to the opposite-to-output side “L 2 ” is prevented. Further, the protruded parts  461  of the plate-shaped springs  46  of the driven gear  42  are elastically abutted with an end face on the opposite-to-output side “L 2 ” of the cylindrical tube part  227  of the second case member  22  and movement of the driven gear  42  to the output side “L 1 ” is restricted. Therefore, the driven gear  42  and the output member  10  are restrained from rattling in the turning center axial line “L” direction. 
       (Operations) 
       [0041]    In the geared motor  100  and the pointer type display device  200  structured as described above, when electrical power is supplied to the coil  8  through the terminal pins  70  in a state that the pointer  11  is stopped at the zero point (home position), the rotor  5  is rotated and rotation is transmitted to the output member  10  through the gear train  4 . Therefore, the pointer  11  connected with the output member  10  is turned in the clockwise direction CW. In this case, an angular position of the pointer  11  is changed by inputting a predetermined number of drive pulses into the coil  8  and, after the pointer  11  is turned to a target position in the clockwise direction CW, the pointer  11  is stopped. Further, when drive pulses for reverse rotation is supplied, the pointer can be turned in the counterclockwise direction CCW to another target position. 
       (Structure of Stopper Mechanism) 
       [0042]      FIG. 6  is an explanatory view showing a planar structure of a stopper mechanism  9  which is structured in the geared motor  100  to which the present invention is applied. In  FIG. 6 , the gear train  4  is shown by the solid line and the second case member  22  is shown by the alternate long and short dash line. 
         [0043]    In  FIG. 6 , in the geared motor  100  in this embodiment, a stopper mechanism  9  is structured between the driven gear  42  and the second case member  22  (support member) so that, when the pointer  11  shown in  FIG. 1 a    is turned in the counterclockwise direction CCW and reached to the home position indicating the zero point, a stopper abutting part  91  provided in the driven gear  42  is abutted with a stopper abutted part  92  provided in the second case member  22  to restrict a movable range in the counterclockwise direction CCW (to one side around the turning center axial line “L”) of the driven gear  42 . 
         [0044]    In this embodiment, the driven gear  42  is provided with the gear side protruded part  48  protruding toward an outer side in the radial direction on an outer peripheral face of the body part  44  which is protruded to the output side “L 1 ” from the plate-shaped part  43  at the center of the driven gear  42 . The stopper abutting part  91  is structured by an end part  481  (one side end part) which is located on the counterclockwise direction CCW side of the gear side protruded part  48 . The gear side protruded part  48  is integrally formed with the body part  44  and is also integrally formed with the plate-shaped part  43 . 
         [0045]    In this embodiment, the plate-shaped part  43  is formed with the plate-shaped spring  46  and the groove  47  at two positions in the circumferential direction, and the gear side protruded part  48  is formed at an angular position corresponding to a portion between the plate-shaped springs  46  adjacent to each other in the circumferential direction. Therefore, although an end part on an outer side in the radial direction of the gear side protruded part  48  is located on an outer side in the radial direction with respect to a portion on an inner side in the radial direction of the groove  47 , since the gear side protruded part  48  and the groove  47  are displaced from each other in the circumferential direction, the gear side protruded part  48  and the body part  44  can be integrally formed with each other. In this embodiment, the gear side protruded part  48  is formed in a planar shape in which a width dimension in the circumferential direction on its inner side in the radial direction is shorter than a width dimension in the circumferential direction on its outer side in the radial direction. Therefore, a rotatable angular range of the driven gear  42  is wide. However, it may be structured that a width dimension in the circumferential direction on an inner side in the radial direction of the gear side protruded part  48  and a width dimension in the circumferential direction on its outer side in the radial direction are equal to each other, or it may be structured that a width dimension in the circumferential direction on its inner side in the radial direction is longer than a width dimension in the circumferential direction on its outer side in the radial direction. 
         [0046]    The second case member  22  is provided with a support body side protruded part  28  which is protruded from the end plate part  220  to the opposite-to-output side “L 2 ”. The stopper abutted part  92  is structured by an end part  281  (the other side end part) on the clockwise direction CW side of the support body side protruded part  28  (the other side around the turning center axial line “L”). In this embodiment, the support body side protruded part  28  is protruded from an inner peripheral face of the cylindrical tube part  227  toward the turning center axial line “L” of the driven gear  42  in the inner side of the cylindrical tube part  227 , and an end part on an outer side in the radial direction of the support body side protruded part  28  and the inner peripheral face of the cylindrical tube part  227  are connected with each other. 
         [0047]    In this embodiment, the support body side protruded part  28  is provided with a planar shape of a substantially trapezoid and a width dimension in the circumferential direction on its inner side in the radial direction is narrower than that on its outer side in the radial direction. In other words, the support body side protruded part  28  is protruded from the inner peripheral face of the cylindrical tube part  227  to the inner side in the radial direction along an extended line of the rib  224   a  on the inner side of the cylindrical tube part  227 . In this case, a width dimension “W 1 ” on the outer side in the radial direction of the support body side protruded part  28  is substantially equal to a width dimension of the rib  224   a,  but a width dimension “W 2 ” on its inner side in the radial direction is set to be narrower than the width dimension of the rib  224   a.  In other words, the width dimension “W 1 ” on the outer side in the radial direction of the support body side protruded part  28  and the width dimension “W 2 ” on its inner side in the radial direction are set in the following relationship: 
         [0048]    the width dimension “W 1 ”&gt;the width dimension “W 2 ”. 
         [0049]    Further, the stopper abutted part  92  (end part  281  of the support body side protruded part  28 ) is provided at a position where the driven gear  42  receives a reaction force in a direction separated from the drive side gear  41  when the driven gear  42  is turned in the counterclockwise direction CCW and the stopper abutting part  91  (end part  481  of the gear side protruded part  48 ) is abutted with the stopper abutted part  92 . More specifically, when a turning angle range of the driven gear  42  is divided into a first angular range θ 1  and a second angular range θ 2  by an imaginary line “L 11 ” passing through the turning center of the driven gear  42  (turning center axial line “L”) and the rotation center of the drive side gear  41  (rotation center axial line “L 5 ”), the stopper abutted part  92  (end part  281  of the support body side protruded part  28 ) is disposed in the first angular range θ 1  in which the stopper abutting part  91  is moved in a direction so as to come close to the rotation center of the drive side gear  41  when the driven gear  42  is turned in the counterclockwise direction CCW. 
         [0050]    Further, the stopper abutted part  92  is provided in an angular range of 90±60° with respect to the imaginary line “L 11 ” when viewed from the turning center of the driven gear  42 . Especially, in this embodiment, the stopper abutted part  92  is provided in an angular range of 90±10° with respect to the imaginary line “L 11 ” when viewed from the turning center of the driven gear  42 . Therefore, when the driven gear  42  is turned in the counterclockwise direction CCW and the stopper abutting part (end part  481  of the gear side protruded part  48 ) is abutted with the stopper abutted part  92 , the driven gear  42  is surely received with a reaction force in a direction separated from the drive side gear  41 . 
         [0000]    (Principal Effects in this Embodiment) 
         [0051]    As described above, in the geared motor  100  and the pointer type display device  200  in this embodiment, the stopper mechanism  9  is provided which determines a movable range of the driven gear  42  when the driven gear  42  (output member  10 ) is turned in the counterclockwise direction CCW. Therefore, the position of the pointer  11  indicating the zero point can be determined in which the position where the stopper mechanism  9  is operated is determined as a home position of the driven gear  42 . 
         [0052]    In this embodiment, in the stopper abutting part  91  and the stopper abutted part  92  which structure the stopper mechanism  9 , the stopper abutting part  91  is an end part  481  of the gear side protruded part  48  which is integrally formed with the body part  44  on an outer peripheral face of the body part  44  of the driven gear  42 . Therefore, the stopper abutting part  91  is abutted with the stopper abutted part  92  at a position near to the turning center axial line “L” of the driven gear  42 . Therefore, when the stopper mechanism  9  is operated, collision energy received by the driven gear  42  is small and thus rebounding of the driven gear  42  can be restrained. Accordingly, when the driven gear  42  is turned in the counterclockwise direction CCW toward the zero point of the pointer  11  and the zero point is indicated, the pointer  11  is hard to be shaken. Further, the gear side protruded part  48  is integrally formed with the plate-shaped part  43  of the driven gear  42  and thus the strength of the gear side protruded part  48  can be increased. 
         [0053]    The plate-shaped part  43  is formed with the plate-shaped springs  46  at a plurality of positions in the circumferential direction and the gear side protruded part  48  is formed at an angular position corresponding to a portion between the plate-shaped springs  46  adjacent to each other in the circumferential direction. Therefore, even when the plate-shaped springs  46  are formed in the plate-shaped part  43 , restriction of the position for forming the gear side protruded part  48  is reduced. Accordingly, the gear side protruded part  48  is easily provided on an inner side in the radial direction. 
         [0054]    On the other hand, the stopper abutted part  92  is the end part  281  of the support body side protruded part  28  which is protruded toward the turning center of the driven gear  42  from an outer side in the radial direction to an inner side in the radial direction, and a width dimension in the circumferential direction of the support body side protruded part  28  on the inner side in the radial direction is narrower than that on its outer side in the radial direction. Therefore, even in a case that the width in the circumferential direction of the support body side protruded part  28  is set to be wide to some extent for securing strength, when the stopper mechanism  9  is operated, the stopper abutting part  91  and the stopper abutted part  92  are abutted with each other at a position which is near to the turning center of the driven gear  42 . Accordingly, when the stopper mechanism  9  is operated, collision energy applied to the driven gear  42  is small and thus rebounding of the driven gear  42  can be restrained. As a result, when the pointer  11  is turned in the counterclockwise direction CCW toward the zero point of the pointer  11  and the zero point is indicated, the pointer  11  is hard to be shaken. 
         [0055]    The width dimension in the circumferential direction of the support body side protruded part  28  is narrower on an inner side in the radial direction than that on its outer side in the radial direction and thus a movable range in the counterclockwise direction CCW of the driven gear  42  can be increased. Further, the support body side protruded part  28  is integrally formed with the cylindrical tube part  227  on an inner side in the radial direction of the cylindrical tube part  227 . Therefore, the strength of the support body side protruded part  28  (stopper abutted part  92 ) can be increased. 
         [0056]    In the stopper mechanism  9 , when the driven gear  42  is turned in the counterclockwise direction CCW and the stopper abutting part (the end part  481  of the gear side protruded part  48 ) is abutted with the stopper abutted part  92  (the end part  281  of the support body side protruded part  28 ), the stopper abutted part  92  is provided at a position where the driven gear  42  is applied with a reaction force in a direction separated from the drive side gear  41 . More specifically, when the stopper mechanism  9  is operated, the stopper abutting part  91  is abutted with the stopper abutted part  92  in the first angular range θ 1 . Therefore, when the stopper mechanism  9  is operated, engagement of the drive side gear  41  with the driven gear  42  becomes shallow and thus an inertia torque in an opposite direction from the drive side gear  41  and the rotor  5  is hard to be transmitted to the driven gear  42 . Accordingly, rebounding of the driven gear  42  can be restrained and thus, when the pointer  11  is turned in the counterclockwise direction CCW toward the zero point of the pointer  11  and the zero point is indicated, the pointer  11  is hard to be shaken. 
         [0057]    Especially, in this embodiment, in the first angular range θ 1 , the stopper abutting part  91  is abutted with the stopper abutted part  92  in an angular range of 90±60° with respect to the imaginary line “L 11 ” when viewed from the turning center of the drive side gear  41 . In addition, in this embodiment, in the first angular range θ 1 , the stopper abutting part  91  is abutted with the stopper abutted part  92  in an angular range of 90±10° with respect to the imaginary line “L 11 ” when viewed from the turning center of the drive side gear  41 . Therefore, when the stopper mechanism  9  is operated, the driven gear  42  is surely applied with a reaction force in a direction separated from the drive side gear  41 . Accordingly, engagement of the drive side gear  41  with the driven gear  42  becomes shallow and thus an inertia torque in an opposite direction from the drive side gear  41  and the rotor  5  is hard to be transmitted to the driven gear  42 . As a result, rebounding of the driven gear  42  can be restrained and thus, when the pointer  11  is turned in the counterclockwise direction CCW toward the zero point of the pointer  11  and the zero point is indicated, the pointer  11  is hard to be shaken. 
         [0058]    In addition, the stopper mechanism  9  is structured between the driven gear  42  integrally turned with the output member  10  and the second case member  22 . Therefore, a movable range in the counterclockwise direction CCW of the output member  10  (pointer  11 ) can be directly restricted by the stopper mechanism  9 . 
       Other Embodiments 
       [0059]    In the embodiment described above, the stopper mechanism  9  is provided between the second case member  22  of the case  2  (support member) and the driven gear  42  (second gear). However, the stopper mechanism  9  may be provided between the first case member  21  and the driven gear  42  (second gear). 
         [0060]    In the embodiment described above, the stopper mechanism  9  is structured between the driven gear  42  and the second case member  22 . However, the present invention may be applied to a case that the stopper mechanism  9  is structured between the drive side gear  41  and the second case member  22 . In this case, the drive side gear  41  corresponds to the first gear in the present invention and the pinion  56  corresponds to the second gear in the present invention. 
         [0061]    In the embodiment described above, the gear train  4  includes two gears (drive side gear  41  and driven gear  42 ) in addition to the pinion  58 . However, the present invention may be applied to a case that the gear train  4  includes two gears including the pinion  58 , or to a case that the gear train  4  includes four or more gears including the pinion  58 . 
         [0062]    In the embodiment described above, as an example, the geared motor  100  is applied to a pointer type display device  200 . However, the present invention may be applied to a geared motor other than the geared motor  100  for a pointer type display device. 
         [0063]    In the embodiment described above, the output member  10  and the driven gear  42  are separately provided from each other. However, the output member  10  and the driven gear  42  may be integrally formed with each other. In this case, it may be structured that a body part  44  having a larger diameter than the output member  10  is formed in a root portion of the shaft-shaped output member  10 . Alternatively, it may be structured that a shaft-shaped output member  10  is protruded from the plate-shaped part  43  and no body part  44  having a larger diameter than the output member  10  is formed in a root portion of the output member  10 . When the former structure is adopted, the gear side protruded part  48  is integrally formed with the body part  44 . In a case that the latter structure is adopted, a root portion of the output member  10  corresponds to the body part  44  and the gear side protruded part  48  is integrally formed in the root portion of the output member  10 . 
         [0064]    In the embodiment described above, the support body side protruded part  28  is integrally formed in the cylindrical tube part  227  of the second case member  22 . However, in a case that the cylindrical tube part  227  is not formed, it may be structured that the support body side protruded part  28  is integrally formed on only the end plate part  220 . 
       REFERENCE SIGNS LIST 
       [0065]      1  . . . motor part,  2  . . . case (support member),  4  . . . gear train,  5  . . . rotor,  6  . . . stator,  9  . . . stopper mechanism,  10  . . . output member,  11  . . . pointer,  21  . . . first case member,  22  . . . second case member (support member),  28  . . . support body side protruded part,  41  . . . drive side gear (second gear),  42  . . . driven gear (first gear),  43  . . . plate-shaped part,  44  . . . body part,  46  . . . plate-shaped spring,  48  . . . gear side protruded part,  58  . . . pinion,  91  . . . stopper abutting part,  92  stopper abutted part,  100  . . . geared motor,  200  . . . pointer type display device,  227  . . . cylindrical tube part,  281  . . . end part of support body side protruded part,  481  . . . end part of gear side protruded part, CCW counterclockwise direction (one side in circumferential direction), CW . . . clockwise direction (one side of circumferential direction), “L” . . . turning center axial line of output member, “L 11 ” . . . imaginary line, “L 5 ” . . . rotation center axial line of drive side gear, θ 1  . . . first angular range, θ 2  . . . second angular range