Patent Publication Number: US-2019187404-A1

Title: Imaging device and surveillance camera having the imaging device

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to an imaging device and a surveillance camera having the imaging device. 
     Description of the Related Art 
     Some imaging devices are configured to perform zooming by linearly moving a lens holding frame in the optical axis direction by a linear actuator to rotate a cam cylinder by using a cam follower attached to the lens holding frame and linearly moving another lens holding frame via the cam cylinder in the optical axis direction. In an imaging device with such a configuration, it is required to reduce backlash of the cam follower to the cam cylinder and to reduce backlash of the lens holding frame to the linear actuator. 
     Japanese Patent No. 5677039 discloses a configuration in which a cam follower is pressed against one surface of one cam groove by an actuation member, and a cam follower attached to the actuation member is pressed against the other surface of the one cam groove in order to reduce backlash of the lens holding frame to the cam cylinder. Japanese Patent No. 2725491 discloses a configuration in which a recess and a protrusion on the lens holding frame is engaged with a protrusion and a recess of the mounting portion of the linear actuator by the actuation member in order to remove backlash of the lens holding frame to the linear actuator. 
     If the configurations disclosed in Japanese Patent No. 5677039 and Japanese Patent No. 2725491 are combined in order to reduce backlash of the cam follower to the cam cylinder and backlash of the lens holding frame to the linear actuator, however, such a combination will result in a configuration in which a plurality of actuation members are located at different places. Therefore, a larger number of components are required. Further, a friction loss due to unnecessary force occurs, and a load is applied to the actuator. In view of the circumstances described above, the problem to be solved by the present invention is to provide an imaging device that can reduce the number of components and reduce the load applied to the actuator. 
     SUMMARY OF THE INVENTION 
     In order to achieve the objective described above, the present invention provides an imaging device having an imaging optical system having an optical member, and the imaging device includes: an optical member-holding member that holds the optical member and is movable in an optical axis direction of the imaging optical system; a coupling portion coupled to the optical member-holding member so as to be relatively movable with respect to the optical member-holding member; a drive portion that moves the optical member-holding member in the optical axis direction via the coupling portion; a cam cylinder that is rotatable about an axis line parallel to the optical axis; a first cam follower provided to the optical member-holding member and engaged with a cam groove provided to the cam cylinder; a second cam follower attached to the coupling portion and engaged with the cam groove provided to the cam cylinder; and an actuation member that actuates the second cam follower to an inner peripheral surface of the cam groove of the cam cylinder and actuates the coupling portion toward the drive portion. 
     Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective exploded view schematically illustrating a configuration example of an imaging device. 
         FIG. 2  is a perspective external view schematically illustrating a configuration example of the imaging device. 
         FIG. 3  is a sectional view schematically illustrating a configuration example of the imaging device. 
         FIG. 4  is a perspective exploded view schematically illustrating a configuration example of an optical filter unit. 
         FIG. 5  is an expansion view schematically illustrating a configuration example of a cam groove. 
         FIG. 6  is a sectional view schematically illustrating a configuration example of the imaging device. 
         FIG. 7  is a diagram schematically illustrating a configuration example of a second group lens barrel and a second group rack member. 
         FIG. 8  is a perspective view schematically illustrating a configuration example of the second group lens barrel and the second group rack member. 
         FIGS. 9A, 9B, 9C, 9D, 9E, and 9F  are diagrams schematically illustrating a configuration example of the second group lens barrel and the second group rack member. 
         FIG. 10  is a perspective view schematically illustrating a configuration example of the second group lens barrel and the second group rack member. 
         FIGS. 11A, 11B, 11C, 11D, 11E, and 11F  are diagrams schematically illustrating a configuration example of the second group lens barrel and the second group rack member. 
         FIG. 12  is a sectional view schematically illustrating a configuration example of a surveillance camera. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     Each embodiment of the present invention will be described below in detail with reference to the attached diagrams. Each direction in three-dimensional directions of an imaging device is indicated by an X-direction, a Y-direction, and a Z-direction in each drawing. The X-direction is the optical axis direction of an imaging optical system of the imaging device. The Y-direction and the Z-direction are perpendicular to the imaging optical system of the imaging device and are orthogonal to each other. 
     Imaging Device 
     First Embodiment 
       FIG. 1  is a perspective exploded view schematically illustrating a configuration example of an imaging device  1  according to a first embodiment.  FIG. 2  is a perspective external view schematically illustrating a configuration example of the imaging device  1  according to the first embodiment.  FIG. 3  is a sectional view schematically illustrating a configuration example of the imaging device  1  according to the first embodiment. As illustrated in  FIG. 1  to  FIG. 3 , the imaging device  1  according to the embodiment of the present invention has an imaging optical system. Further, the imaging device  1  has a fixed lens barrel  101  and a rear lens barrel  102  that have a function as a casing. The fixed lens barrel  101 , which is arranged on the front side of the imaging device  1  (the side facing an object), and the rear lens barrel  102 , which is arranged on the rear side (the side opposite to the side facing an object), are fixed to each other by a screw or the like. 
     The imaging optical system of the imaging device  1  has a first group lens L 1 , a second group lens L 2 , a third group lens L 3 , a fourth group lens L 4 , and a fifth group lens L 5 . Further, these lenses of each group are arranged in the order described above from the side facing an object. The first group lens L 1  is fixed so as not to move in the direction of an optical axis A. The second group lens L 2 , the third group lens L 3 , and the fourth group lens L 4  are zooming lenses related to a zooming operation (zooming) and perform zooming when moving in the optical axis A direction of the imaging optical system. The fifth group lens L 5  is a focus lens related to a focusing operation (focusing) and performs a focusing operation (focusing) when moving in the optical axis A direction of the imaging optical system. 
     In addition, the imaging optical system of the imaging device  1  has an optical filter unit  60 , an aperture unit  36 , and an image pickup device L 7 . The optical filter unit  60  has a removable optical filter L 6  on an optical path of the imaging optical system and transmits or shields a light beam in a specific wavelength range. The aperture unit  36  changes an aperture diameter by driving an aperture blade and adjusts the amount of light passing through the imaging optical system (entering the image pickup device L 7 ). A photoelectric conversion device such as a CCD sensor, a CMOS sensor, or the like can be applied to the image pickup device L 7 . 
     The first group lens L 1  is held in a first group lens barrel  10 . The first group lens barrel  10  is a member that holds the first group lens L 1  and is fixed to the fixed lens barrel  101  having a function of the casing of the imaging device  1 . 
     The second group lens L 2 , which is an example of an optical member, is held in a second group lens barrel  20   a , which is an example of an optical member-holding member. The second group lens barrel  20   a , which is an example of the optical member-holding member, is a member that holds a second guide bar of the second group lens L 2 , which is an example of the optical member, and is arranged so as to be movable in the optical axis A direction. In the present embodiment, the second group lens barrel  20   a  is guided (supported) so as to be movable in the optical axis A direction, and the rotation is restricted by a first guide bar  21  and a second guide bar  22 , which are examples of a guide member. 
     The first guide bar  21  and the second guide bar  22  are bar-shaped members parallel to each other and extend in the optical axis A direction. The second group lens barrel  20   a  is provided with a sleeve portion and an engagement groove that is substantially U-shaped when viewed in the optical axis A direction. The first guide bar  21  is then inserted through the sleeve portion. Thereby, the second group lens barrel  20   a  is guided (supported) by the first guide bar  21  so as to be movable in the optical axis A direction, and the second guide bar  22  is engaged (interlocked) with the engagement groove. Thereby, the rotation about the first guide bar  21  of the second group lens barrel  20   a  is restricted. 
     Further, to the second group lens barrel  20   a , a first cam follower  231  is attached and a second cam follower  232  is coupled via a second group rack member  24   a , which is an example of a coupling portion. The first cam follower  231  is rotatable, and the rotation center line  261  thereof is perpendicular to the optical axis A. The second group rack member  24   a , which is an example of the coupling portion, is a member that supports the second cam follower  232  and transmits drive force of a first actuator  111 , which is an example of a drive portion, to the second group lens barrel  20   a.    
     Further, the second group rack member  24   a  is a member that supports the second cam follower  232  so as to be rotatable. The second group rack member  24   a  is coupled to the second group lens barrel  20   a  so as to be relatively displaceable. In particular, the second group rack member  24   a  is able to move with respect to the second group lens barrel  20   a  in the direction (±Z-direction) of approaching or separating from the first actuator  111  and in the circumferential direction (tangential direction of the circle) of a cam cylinder  80 . The second cam follower  232  is attached to the second group rack member  24   a  so as to be rotatable. The rotation center line  262  of the second cam follower  232  is perpendicular to the optical axis A. Further, each of the first cam follower  231  and the second cam follower  232  is engaged (interlocked) with a second group cam groove  82  (that is, the same cam groove) provided in the cam cylinder  80  described later. Note that a configuration of the first cam follower  231 , the second group rack member  24   a , and the second cam follower  232  will be described later. 
     In addition, a second group position detection scale  25  for detecting a position of the second group lens barrel  20   a  in the optical axis A direction is fixed to the second group lens barrel  20   a . Further, a second group position sensor  113  that can detect the second group position detection scale  25  is fixed to the fixed lens barrel  101 . It is possible to detect the position of the second group lens barrel  20   a  in the optical axis A direction by detecting the second group position detection scale  25  by using the second group position sensor  113 . On the second group position detection scale  25 , a periodic light and dark pattern is provided in parallel to the optical axis A direction, for example. Further, an optical sensor having a light emitting portion and a light receiving portion can be applied to the second group position sensor  113 . Further, the second group position sensor  113  detects a light reflected by the light and dark pattern of the second group position detection scale  25  attached to the second group lens barrel  20   a  for conversion to an electric signal, and thereby the position of the second group lens barrel  20   a  in the optical axis A direction can be detected. 
     The third group lens L 3  is held in a third group lens barrel  30 . The third group lens barrel  30  is a member that holds the third group lens L 3  and is arranged so as to be movable in the optical axis A direction. The third group lens barrel  30  is guided (supported) so as to be movable in the optical axis A direction, and the rotation is restricted by a bar-shaped third guide bar  31  and the second guide bar  22  that are parallel to each other and extend in the optical axis A direction. 
     Specifically, the third group lens barrel  30  is provided with a sleeve portion and an engagement groove that is substantially U-shaped when viewed in the optical axis A direction. Further, the third guide bar  31  is inserted through the sleeve portion, and thereby the third group lens barrel  30  is supported (guided) so as to be movable in the optical axis A direction. Further, since the second guide bar  22  is engaged (interlocked) with the engagement groove, the rotation about the third guide bar  31  of the third group lens barrel  30  is restricted. Further, a third group cam follower  33  is attached to the third group lens barrel  30 . The third group cam follower  33  is rotatable about the axis line in a direction perpendicular to the optical axis A of the imaging optical system and engaged with a third group cam groove  83  of the cam cylinder  80  described later. 
     The aperture unit  36  is fixed to the third group lens barrel  30 . The aperture unit  36  changes an aperture diameter by driving an aperture blade and adjusts the amount of light passing through the optical path of the imaging optical system (the amount of light entering the image pickup device L 7 ). Note that a configuration of the aperture unit  36  is not particularly limited, and various known configurations can be applied. 
     The fourth group lens L 4  is held in a fourth group lens barrel  40  and moves in the optical axis A direction together with the fourth group lens barrel  40 . The fourth group lens barrel  40  is a member that holds the fourth group lens L 4  and is guided (supported) so as to be movable in the optical axis A direction, and the rotation is restricted by a fourth guide bar  41  and the second guide bar  22 . 
     Specifically, the fourth group lens barrel  40  is provided with a sleeve portion, and this sleeve portion is engaged with the fourth guide bar  41  extending in the optical axis A direction. In such a way, the fourth group lens barrel  40  is guided (supported) so as to be movable in the optical axis A direction by using the fourth guide bar  41 . Further, the fourth group lens barrel  40  is provided with an engagement groove that is substantially U-shaped when viewed in the optical axis A direction, and this engagement groove is engaged (interlocked) with the second guide bar  22 . Accordingly, the rotation about the fourth guide bar  41  of the fourth group lens barrel  40  is restricted. Further, the fourth group cam follower  43  is attached to the fourth group lens barrel  40  so as to be rotatable. The fourth group cam follower  43  is engaged (interlocked) with a fourth group cam groove  84  of the cam cylinder  80  described later. 
     The fifth group lens L 5  is held in a fifth group lens barrel  50  and moves in the optical axis A direction together with the fifth group lens barrel  50 . The fifth group lens barrel  50  is a member that holds the fifth group lens L 5  and is guided (supported) so as to be movable in the optical axis A direction, and the rotation is restricted by a fifth guide bar  51  extending in the optical axis A direction and the sixth guide bar  52 . 
     For example, the fifth group lens barrel  50  is provided with a sleeve portion and an engagement groove that is substantially U-shaped when viewed in the optical axis A direction. Further, the fifth guide bar  51  is inserted through the sleeve portion, and the fifth group lens barrel  50  is guided (supported) so as to be movable in the optical axis A direction by the fifth guide bar  51 . Further, a sixth guide bar  52  is engaged (interlocked) with the engagement groove, and the rotation about the fifth guide bar  51  of the fifth group lens barrel  50  is restricted. The fifth group rack member  54  is attached to the fifth group lens barrel  50 . The fifth group rack member  54  is a member that receives drive force of a fifth group stepping motor  115  that is a source of drive force of the fifth group lens barrel  50 . 
     The fifth group stepping motor  115  is a source of the drive force to move the fifth group lens barrel  50  in the optical axis A direction. The fifth group stepping motor  115  is fixed to the fixed lens barrel  101  and engaged with the fifth group rack member  54 . When the fifth group stepping motor  115  generates drive force in the optical axis A direction, the fifth group lens barrel  50  moves (forward and backward) in the optical axis A direction via the fifth group rack member  54 , and the focusing operation can be performed. 
       FIG. 4  is a perspective exploded view schematically illustrating a configuration example of the optical filter unit  60 . The optical filter unit  60  has a removable optical filter L 6  on the optical path of the imaging optical system and an optical filter driving mechanism that inserts and removes the optical filter L 6  on the optical path. For example, an IR cut filter  64  and a band-pass filter  66  are applied to the optical filter L 6 . 
     The IR cut filter  64  is a filter having optical characteristics for cutting infrared rays. The band-pass filter  66  is a filter having optical characteristics for transmitting a light beam of a specific wavelength range. These optical filters L 6  ( 64 ,  66 ) are held by optical filter holding frames  65  and  67 , respectively. The optical filter holding frames  65  and  67  are members that hold the optical filter L 6  so as to be movable. The optical filter holding frames  65  and  67  are held by an optical filter unit frame  61  and a cover member  68  and are movable in the direction perpendicular to the optical axis A of the imaging optical system (movable in a plane perpendicular to the optical axis A) such that the optical filter L 6  can be inserted into and removed from the optical path. 
     The optical filter driving mechanism has optical filter insertion-removal motors  116  and  117 . The optical filter insertion-removal motors  116  and  117  are drive sources to insert and remove the optical filters L 6  ( 64 ,  66 ) together with the optical filter holding frames  65  and  67  and are fixed to an optical filter insertion-removal motor holding member  107 . The optical filter insertion-removal motor holding member  107  is a member that supports the optical filter insertion-removal motors  116  and  117  and is fixed to the fixed lens barrel  101 . 
     Engagement arms  119  each rotatable in a plane perpendicular to the optical axis A of the imaging optical system are provided to rotation output shafts of the optical filter insertion-removal motors  116  and  117 , respectively. The engagement arms  119  are engaged with engaging holes  651  and  671  provided in the optical filter holding frames  65  and  67 , respectively. When these engagement arms  119  are rotated by rotation power of the optical filter insertion-removal motors  116  and  117 , the optical filters L 6  ( 64 ,  66 ) are inserted into and removed from the optical path together with the optical filter holding frames  65  and  67 , respectively. 
     When the IR cut filter  64  is inserted into the optical path, an infrared light is cut from the light entering the image pickup device L 7 , and thereby a light beam suitable for generating a typical color image is obtained. When the band-pass filter  66  is inserted into the optical path, only a light beam of a specific wavelength range such as a near-infrared light enters the image pickup device L 7 , for example, and thereby a light beam suitable for generating an image with higher contrast is obtained. When the IR cut filter  64  and the band-pass filter  66  are removed from the optical path, a light beam including an infrared ray enters the image pickup device L 7 , and thereby a greater amount of light can be obtained such that an image can be captured even under low luminance such as nighttime. 
     Further, the optical filter unit frame  61  is guided (supported) so as to be movable in the optical axis A direction of the imaging optical system and the rotation is restricted by the fifth guide bar  51  and the sixth guide bar  52 . Specifically, the optical filter unit frame  61  is provided with a sleeve portion and an engagement groove that is substantially U-shaped when viewed in the optical axis A direction. Then, the sixth guide bar  52  is inserted through the sleeve portion, and thereby the optical filter unit frame  61  is guided (supported) so as to be movable in the optical axis A direction. Since the fifth guide bar  51  is engaged (interlocked) with the engagement groove, the rotation about the sixth guide bar  52  is restricted. 
     Further, an optical filter cam follower  63  is attached to the optical filter unit frame  61 . The optical filter cam follower  63  is engaged (interlocked) with an optical filter cam groove  86  of the cam cylinder  80  described later. Note that the optical filter cam follower  63  is rotatable about the axis line in a direction perpendicular to the optical axis A. 
     Turning back to  FIG. 1  to  FIG. 3 , the image pickup device L 7  detects an incident light and generates an electric signal (imaging signal). The image pickup device L 7  is fixed on a sensor substrate  76 , and the sensor substrate  76  is held in the image pickup device holding frame  70 . The image pickup device holding frame  70  is a member that holds the image pickup device L 7  together with the sensor substrate  76  and is guided (supported) so as to be movable in the optical axis A direction and rotation is restricted by a seventh guide bar  71  and the eighth guide bar  72  extending in the optical axis A direction. 
     Specifically, the image pickup device holding frame  70  is provided with a sleeve portion and guided (supported) so as to be movable in the optical axis A direction by the seventh guide bar  71 . Further, the image pickup device holding frame  70  is provided with an engagement groove that is substantially U-shaped when viewed in the optical axis A direction, and the eighth guide bar  72  is engaged (interlocked) with the engagement groove. Thereby, rotation about the seventh guide bar  71  of the image pickup device holding frame  70  is restricted. In addition, an image pickup device rack member  74  is attached to the image pickup device holding frame  70  so as to be rotatable in a plane perpendicular to the optical axis A direction. 
     In addition, an image pickup device position detection scale  75  that detects the position of the image pickup device L 7  (the image pickup device holding frame  70 ) in the optical axis A direction is fixed to the image pickup device holding frame  70 . Further, an image pickup device position sensor  114  that detects a position of the image pickup device holding frame  70  in the optical axis A direction is fixed to the rear lens barrel  102 . It is possible to detect the position of the image pickup device L 7  in the optical axis A direction by detecting the image pickup device position detection scale  75  by using the image pickup device position sensor  114 . Note that the same configuration as that of the second group position detection scale  25  and the second group position sensor  113  used for detecting the position of the second group lens barrel  20   a  in the optical axis A direction can be applied to the configuration of the image pickup device position sensor  114  and the image pickup device position detection scale  75 . 
     Each of the first guide bar  21 , the second guide bar  22 , the fifth guide bar  51 , the sixth guide bar  52 , the seventh guide bar  71 , and the eighth guide bar  72  is held between the fixed lens barrel  101  and the rear lens barrel  102 . Further, the imaging device  1  has a guide bar holding member  103  that holds the third guide bar  31  and the fourth guide bar  41 . The guide bar holding member  103  is fixed to the fixed lens barrel  101 , and the third guide bar  31  and the fourth guide bar  41  are held between the fixed lens barrel  101  and the guide bar holding member  103 . Note that each of the first to eighth guide bars  21 ,  22 ,  31 ,  41 ,  51 ,  52 ,  71 , and  72  is a bar-shaped member extending in the optical axis A direction of the imaging optical system. 
     The cam cylinder  80  is a member rotatable about a rotation axis B (rotation center line) parallel to the optical axis A. The cam cylinder  80  is held between the fixed lens barrel  101  and the rear lens barrel  102  via a cam cylinder actuation member  81  so as to be rotatable. Further, the cam cylinder  80  is actuated in one direction (for example, +X-direction) in the optical axis A direction by the cam cylinder actuation member  81 . 
       FIG. 5  is an expansion view illustrating an example configuration of a cam groove provided to the cam cylinder  80 . As illustrated in  FIG. 5 , the cam cylinder  80  is provided with the second group cam groove  82 , the third group cam groove  83 , the fourth group cam groove  84 , and the optical filter cam groove  86 . The first cam follower  231  and the second cam follower  232  are engaged with the second group cam groove  82 . The third group cam follower  33  is engaged with the third group cam groove  83 . The fourth group cam follower  43  is engaged with the fourth group cam groove  84 . The optical filter cam follower  63  is engaged with the optical filter cam groove  86 . 
     The first actuator  111  is a source of drive force to move the second group lens barrel  20   a , the third group lens barrel  30 , the fourth group lens barrel  40 , and the optical filter unit  60  in the optical axis A direction. A vibration-type linear actuator is applied to the first actuator  111 , for example. Further, the first actuator  111  is fixed to the fixed lens barrel  101  and engaged with the second group rack member  24   a . When the first actuator  111  generates drive force in the optical axis A direction, the second group lens barrel  20   a  moves (forward and backward) in the optical axis A direction via the second group rack member  24   a . When the second group lens barrel  20   a  moves in the optical axis A direction, the cam cylinder  80  engaged with the first cam follower  231  and the second cam follower  232  rotates about the rotation axis B thereof (axis line parallel to the optical axis A). 
     When the cam cylinder  80  rotates, the third group lens barrel  30 , the fourth group lens barrel  40 , and the optical filter unit  60  move (forward and backward) in the optical axis A direction via the third group cam follower  33  engaged with the third group cam groove  83 , the fourth group cam follower  43  engaged with the fourth group cam groove  84 , and the optical filter cam follower  63  engaged with the optical filter cam groove  86 . In such a way, the second group lens barrel  20   a , the third group lens barrel  30 , the fourth group lens barrel  40 , and the optical filter unit  60  can be moved in the optical axis A direction of the imaging optical system by the drive force of the first actuator  111 . 
     The second actuator  112  is a source of drive force to move the image pickup device holding frame  70  in the optical axis A direction. A vibration-type linear actuator can be applied to the second actuator  112  in the same manner as the first actuator  111 , for example. The second actuator  112  is fixed to the rear lens barrel  102  and engaged with the image pickup device rack member  74 . When the second actuator  112  generates drive force in the optical axis A direction, the image pickup device holding frame  70  moves forward and backward in the optical axis A direction via the image pickup device rack member  74 . In such a way, the image pickup device L 7  can be moved together with the image pickup device holding frame  70  in the optical axis A direction of the imaging optical system by the drive force of the second actuator  112 . 
     By driving the first actuator  111  and the second actuator  112  in such a way, the second group lens barrel  20   a , the third group lens barrel  30 , the fourth group lens barrel  40 , the optical filter unit  60 , and the image pickup device holding frame  70  can be moved (forward and backward) in the optical axis A direction. Thereby, zooming and focusing can be performed. 
     Note that the configurations of the first actuator  111  and the second actuator  112  are not particularly limited. For the first actuator  111  and the second actuator  112 , a vibration-type linear actuator can be applied as described above. For example, the vibration-type linear actuator is formed of a slider and a vibrator (not illustrated), when a frequency signal is input to the vibrator via a flexible printed board (not illustrated), approximately elliptical motion occurs in the vibrator, and this allows drive force to occur on a pressure contact surface against the slider. 
     A lens substrate  105  is a circuit board fixed to the fixed lens barrel  101 . The lens substrate  105  inputs and outputs an electric signal in and from the image pickup device L 7  via an electric wiring  104 . Further, the lens substrate  105  transmits and receives an electric signal to and from each actuator such as the first actuator  111 , the second actuator  112 , the fifth group stepping motor  115 , the optical filter insertion-removal motors  116  and  117 , or the like or each sensor such as the second group position sensor  113 , the image pickup device position sensor  114 , or the like via a flexible printed board (not illustrated). 
     One end of the electric wiring  104  is connected to the sensor substrate  76 , and the other end is connected to the lens substrate  105 . The electric wiring  104  is preferably configured to be easily deformed such that, when the image pickup device holding frame  70  moves in the optical axis A direction, no excessive load is applied to the second actuator  112  (vibration-type linear actuator). In the present embodiment, the electric wiring  104  has a shape that is curved in a U shape and has a curvature such that no excessive load is applied to the second actuator  112 . However, the specific configuration of the electric wiring  104  is not particularly limited. 
     A heat conduction member  106  is a member that conducts heat generated in the sensor substrate  76  to a heatsink (not illustrated) and arranged to suppress a rise in the temperature of the image pickup device L 7  or the like. A flexible sheet member having a high thermal conductivity such as a graphite sheet is applied to the heat conduction member  106 , for example. Further, one end of the heat conduction member  106  is fixed (connected) to the sensor substrate  76 , and the other end is fixed (connected) to the heatsink (not illustrated). Note that the heat conduction member  106  is configured to be easily deformed in the direction of the axis line so as not to increase the load applied to the second actuator  112  (thrust required for moving) when the second actuator  112  moves the image pickup device holding frame  70  in the optical axis A direction. For example, as illustrated in  FIG. 1  or  FIG. 3 , a bellows structure can be applied so as to facilitate expansion and contraction in the optical axis A direction. 
     The arrangement of each member will now be described with reference to  FIG. 6 .  FIG. 6  is a sectional view illustrating the imaging device  1  taken along a plane perpendicular to the optical axis A of the imaging optical system when viewed from the front. The cam cylinder  80  is arranged at a position (separate position) that is shifted on the +Y-direction side to the optical axis A of the imaging optical system. The first actuator  111  and the second actuator  112  are arranged at a position (separate position) that is shifted on the +Z-direction side to the optical axis A of the imaging optical system. 
     For example, the first actuator  111  is arranged on a side face of the +Z-direction side of the fixed lens barrel  101 , and the second actuator  112  is arranged on a side face of the +Z-direction side of the rear lens barrel  102 . The fifth group stepping motor  115  is arranged at a position (separate position) that is shifted on the −Z-direction side to the optical axis A of the imaging optical system. The electric wiring  104  is arranged at a position (separate position) that is shifted on the −Y-direction side to the optical axis A of the imaging optical system and can bend in a plane approximately parallel to the X-Z plane. Further, the second group rack member  24   a  is arranged at a position (separate position) that is shifted on the +Z-direction side to the optical axis A of the imaging optical system and the rotation axis B of the cam cylinder  80 . That is, the second group rack member  24   a  is arranged between the cam cylinder  80  and the first actuator  111  in the Z-direction. 
     Next, a configuration example of the second group lens barrel  20   a  and the second group rack member  24   a  will be described.  FIG. 7  is a diagram when viewed in the optical axis A direction and schematically illustrating a configuration example of the second group lens barrel  20   a  and the second group rack member  24   a .  FIG. 8  is a perspective view schematically illustrating a configuration example of the second group lens barrel  20   a  and the second group rack member  24   a .  FIG. 9A  to  FIG. 9F  are diagrams schematically illustrating a configuration example of a part of the second group lens barrel  20   a , the second group rack member  24   a , and the periphery thereof. Specifically,  FIG. 9A  is a diagram when viewed from the −X-side,  FIG. 9B  is a diagram when viewed from the +X-side,  FIG. 9C  is a diagram when viewed from the +Y-side,  FIG. 9D  is a diagram when viewed from the −Z-side,  FIG. 9E  is a diagram when viewed from the +Z-side, and  FIG. 9F  is a sectional view when viewed from the +Z-side. Further, each of arrows L and arrows N in  FIG. 7  to  FIG. 9F  indicates the direction of actuation force of the second group rack member  24   a  applied by a rack spring  27   a.    
     As illustrated in  FIG. 7 , a rotation center line  261  of the first cam follower  231  and a rotation center line  262  of the second cam follower  232  are perpendicular to the optical axis A (X-direction) (parallel to the Y-Z plane) and pass through the rotation axis B (rotation center line) of the cam cylinder  80 . The second group rack member  24   a  is arranged between the cam cylinder  80  and the first actuator  111  in the Z-direction. Therefore, the first actuator  111  is at a position opposite to the cam cylinder  80  (+Z-direction side) when viewed from the second group rack member  24   a . Further, the second group rack member  24   a  is relatively movable with respect to the second group lens barrel  20   a  in the direction of approaching the first actuator  111 , in the direction of approaching the cam cylinder  80  (±Z-direction), and in the direction perpendicular to the optical axis A (±Y-direction). 
     An actuator connecting portion  241   a  is integrally provided on the side close to the first actuator  111  (+Z-direction side) to the second group rack member  24   a . That is, the actuator connecting portion  241   a  forms a part of the second group rack member  24   a . Further, the second group rack member  24   a  is engaged with the first actuator  111  via the actuator connecting portion  241   a . Therefore, when the first actuator  111  moves in the optical axis A direction of the imaging optical system, the drive force is transmitted to the second group lens barrel  20   a  via the second group rack member  24   a  (the actuator connecting portion  241   a ). Thereby, the second group lens barrel  20   a  is driven in the optical axis A direction (moves in the optical axis A direction). 
     The second cam follower  232  is rotatably attached to the second group rack member  24   a  on the side close to the cam cylinder  80 . Note that the first cam follower  231  is rotatable with respect to the second group rack member  24   a  and relatively movable together with the second group rack member  24   a  to the second group lens barrel  20   a  in the Y-direction and the Z-direction. The second cam follower  232  is then engaged with the second group cam groove  82  of the cam cylinder  80 . 
     The second group rack member  24   a  is coupled to the second group lens barrel  20   a . The second group rack member  24   a  is relatively movable with respect to the second group lens barrel  20   a  in the Z-direction (direction of approaching or separating from the cam cylinder  80  and the first actuator  111 ) and in the Y-direction (direction of approaching or separating from the first cam follower  231 ). Note that the second group rack member  24   a  may be relatively movable with respect to the second group lens barrel  20   a  in the Z-direction (direction of approaching or separating from the cam cylinder  80  and the first actuator  111 ) and may be rotatable about the axis line parallel to the Z-direction relative to the second group lens barrel  20   a . Then, the second group rack member  24   a  is actuated in the direction (+Z-direction) of approaching the first actuator  111  and in the direction (+Y-direction) of separating from the first cam follower  231  by using the rack spring  27   a , which is an example of an actuation member. 
     As illustrated in  FIG. 7  and  FIG. 8 , the second group rack member  24   a  is actuated in the direction of the arrow N by the actuation force of the rack spring  27   a , and thereby the actuator connecting portion  241   a  of the second group rack member  24   a  is actuated and engaged with the first actuator  111 . Further, by the actuation force of the rack spring  27   a  in the direction of the arrow L, the second cam follower  232  together with the second group rack member  24   a  is actuated in the direction of separating from the first cam follower  231  in the +Y-direction (direction of the arrow L, the tangential direction of the circle of the cam cylinder  80 ). That is, the first cam follower  231  and the second cam follower  232  are actuated in the direction of separating from each other in the Y-direction by the actuation force of the rack spring  27   a  (actuation force in the direction of the arrow L). 
     The rack spring  27   a , which is an example of an actuation member, has a coil spring portion  271   a , which is an elastically compressively deformable compression coil spring portion, which is an example of a first actuation portion, and an arm portion  272   a , which is an example of a second actuation portion. For example, a torsion spring can be applied to the rack spring  27   a . The torsion spring applied to the rack spring  27   a  has a coil spring portion that is elastically compressively deformable in the direction of the axis line (the coil spring portion  271   a ) and two arm portions  272   a  protruded from both end portions of the coil spring portion  271   a  in the direction perpendicular to the axial line direction. Further, the coil spring portion  271   a  functions as a first actuation portion, and the two arm portions  272   a  protruded from the coil spring portion  271   a  function as a second actuation portion. Note that, to be precise, the rack spring  27   a  functions as the second actuation unit by being twisted so that the relative angle of the two arm portions  272   a  changes. 
     Further, as illustrated in  FIG. 9B  and  FIG. 9C , the coil spring portion  271   a  actuates the second group rack member  24   a  in the diameter direction of the cam cylinder  80  (direction of the arrow N) within a plane perpendicular to the optical axis A of the imaging optical system (within a plane parallel to the Y-Z plane). Thereby, the second group rack member  24   a  and the second group lens barrel  20   a  are actuated in the direction of separating from each other (+Z-direction and −Z-direction, respectively). As a result, the second group rack member  24   a  is actuated to the first actuator  111 . Further, due to actuation force of the coil spring portion  271   a  (compression spring portion) of the rack spring  27   a  in the direction of the axis line, force (moment) in the rotational direction about the first guide bar  21  is applied to the second group lens barrel  20   a . Thereby, the second group lens barrel  20   a  is actuated in the direction perpendicular to the optical axis A of the imaging optical system (that is, direction perpendicular to the extending direction of the second guide bar  22 ) to the second guide bar  22 . With such a configuration, the second group lens barrel  20   a  is held without backlash to the first guide bar  21  and the second guide bar  22 . 
     Note that, as illustrated in  FIG. 8  and  FIG. 9A  to  FIG. 9F , when viewed in the optical axis A direction (in the Y-Z plane), the position where the second group lens barrel  20   a  is guided by the first guide bar  21  and the position where the second group lens barrel  20   a  is engaged with the second guide bar  22  are out of the extension line of actuation force applied by the coil spring portion  271   a  (first actuation portion) of the rack spring  27   a . With such a configuration, the second group lens barrel  20   a  is actuated to both the first guide bar  21  and the second guide bar  22 , and backlash to the first guide bar  21  and the second guide bar  22  is reduced. 
     The two arm portions  272   a  of the rack spring  27   a  actuate the second group lens barrel  20   a  and the second group rack member  24   a  in the direction of rotation about the center axis of the coil spring portion  271   a.    
     As illustrated in  FIG. 9C  and  FIG. 9F , for example, one arm portion  272   a  is latched to the second group lens barrel  20   a , and the other arm portion  272   a  is latched to the second group rack member  24   a . Therefore, a rotational moment about the axis line of the coil spring portion  271   a  (the center line parallel to the Z-direction) is applied to the second group lens barrel  20   a  and the second group rack member  24   a . This rotational moment then actuates the first cam follower  231  and the second cam follower  232  in the direction of separating from each other (+Y- and −Y-directions, the opposite direction). In such a way, the arm portions  272   a  of rack spring  27   a  actuate the first cam follower  231  and the second cam follower  232  in the direction of separating from each other. Thereby, the first cam follower  231  and the second cam follower  232  are actuated to the inner peripheral surface (wall surface) of the second group cam groove  82 , respectively. According to such a configuration, a state where there is no backlash between the first cam follower  231  and the cam cylinder  80  and between the second cam follower  232  and the cam cylinder  80  is maintained. 
     That is, the first cam follower  231  and the second cam follower  232  are engaged with the same single second group cam groove  82 . The first cam follower  231  and the second cam follower  232  are then actuated by the rack spring  27   a  in the direction of separating from each other in the direction perpendicular to the rotational axis B (rotation center line) of the cam cylinder  80  (the circumferential direction of the cam cylinder  80 ). Thereby, the first cam follower  231  and the second cam follower  232  will push (being actuated to come into contact with) the two inner peripheral surfaces (two wall surfaces) of the second group cam groove  82  in the opposite direction, respectively (+Y- and −Y-directions, that is, at least a direction different from the extending direction of the second group cam groove  82 ). Therefore, backlash between the first cam follower  231  and second cam follower  232  and the cam cylinder  80  (the inner peripheral surface of the second group cam groove  82 ) can be reduced. 
     As described above, the backlash of the two cam followers to the cam cylinder  80  (the first cam follower  231  and the second cam follower  232 ) and the backlash of the second group lens barrel  20   a  to the first actuator  111  can be reduced by the single rack spring  27   a , which is an example of an actuation member. According to such a configuration, the number of components can be reduced compared to a configuration in which the backlash of the two cam followers to the cam cylinder  80  (the first cam follower  231  and the second cam follower  232 ) and the backlash of the second group lens barrel  20   a  to the first actuator  111  are reduced by using separate actuation members, respectively. Therefore, the number of assembling steps can be reduced. 
     Further, since the friction loss can be reduced by the actuation with a single component, a load applied to the first actuator  111  can be reduced. Further, since the second group lens barrel  20   a  is actuated to the second guide bar  22 , an image shaking due to shaft misalignment in a zooming operation (when the second group lens L 2 , the third group lens L 3 , and the fourth group lens L 4  move) can also be reduced. 
     Note that the second group rack member  24   a  and second group lens barrel  20   a  may have detachment prevention portions  201   a  and  242   a , respectively, which prevent the second group rack member  24   a  from being detached from the second group lens barrel  20   a  due to actuation force of the rack spring  27   a  after being assembled. 
     For example, the detachment prevention portion  201   a  of the second group lens barrel  20   a  has a configuration that can be latched on the +Z-direction side (the side close to the first actuator  111 ) of the detachment prevention portion  242   a  of the second group rack member  24   a . Specifically, as illustrated in  FIG. 9B ,  FIG. 9C , and  FIG. 9E , for example, the detachment prevention portion  201   a  of the second group lens barrel  20   a  is located on the +Z-direction side (the side close to the first actuator  111 ) of the detachment prevention portion  242   a  of the second group rack member  24   a  and is provided with a groove or the like extending in the Z-direction. Further, a part of the second group rack member  24   a  enters the groove of the detachment prevention portion  201   a . The second group rack member  24   a  is able to move in the +Z-direction (direction of approaching to the first actuator  111 ) up to a position where the detachment prevention portion  242   a  latches to (comes into contact with) the detachment prevention portion  201   a  of the second group lens barrel  20   a . Then, the detachment prevention portion  242   a  of the second group rack member  24   a  is actuated toward the detachment prevention portion  201   a  of the second group lens barrel  20   a  by actuation force of the coil spring portion  271   a  of the rack spring  27   a . Therefore, with the detachment prevention portion  242   a  of the second group rack member  24   a  being latched to the detachment prevention portion  201   a  of the second group lens barrel  20   a , detachment of the second group rack member  24   a  from the second group lens barrel  20   a  is prevented. 
     Note that the detachment prevention portion  242   a  of the second group rack member  24   a  may be of any configuration that can be latched to the detachment prevention portion  201   a  of the second group lens barrel  20   a , and the specific configuration thereof is not particularly limited. According to such a configuration, the second group rack member  24   a  is not detached due to actuation force of the rack spring  27   a  even after the second group rack member  24   a , the rack spring  27   a , and the second group lens barrel  20   a  are assembled. Accordingly, since the first actuator  111  is attached with the second group rack member  24   a  and the rack spring  27   a  being assembled with (being engaged with) the second group lens barrel  20   a , assembly performance is improved. 
     Further, the first cam follower  231  and the second cam follower  232  are actuated by the arm portion  272   a  of the rack spring  27   a  so as to separate from each other in the Y-direction (in the circumferential direction of the cam cylinder  80 ). Thereby, the second cam follower  232  is actuated to a position away from the second group cam groove  82  by actuation force of the arm portion  272   a  of the rack spring  27   a . An insertion guide portion  202   a  may be provided to the detachment prevention portion  201   a  of the second group lens barrel  20   a  such that the second cam follower  232  is held in a position for facilitating engagement with the second group cam groove  82 , when the first actuator  111  is attached after the second group rack member  24   a  and the rack spring  27   a  are attached to the second group lens barrel  20   a.    
     The insertion guide portion  202   a  has an inclined surface inclined to the direction of actuation force of the arm portion  272   a  of the rack spring  27   a . Further, in response to being actuated toward the insertion guide portion  202   a  by actuation force of the arm portion  272   a  of the rack spring  27   a , a part of the second group rack member  24   a  (for example, the detachment prevention portion  242   a  ) is actuated toward the cam cylinder  80  side by the inclined surface of the insertion guide portion  202   a . With such a configuration, the position of the second cam follower  232  (the moving range in the Y-direction) in the circumferential direction (tangential direction of the circle) of the cam cylinder  80  is restricted by the insertion guide portion to a position for facilitating engagement with the second group cam groove  82 . That is, the insertion guide portion  202   a  restricts the position of the second cam follower  232  in the circumferential direction of the cam cylinder  80  (the position to the second group cam groove  82 ) so as to facilitate engagement with the second group cam groove  82  (in other words, so as not to be excessively separated from the first cam follower  231  in the Y-direction). 
     Note that the position in the Y-direction of the inclined surface of the insertion guide portion  202   a  may be any position that facilitate the second cam follower  232  to be engaged with the second group cam groove  82  (the position close to the second group cam groove  82 ) of the cam cylinder  80  and is not particularly limited. According to such a configuration, assembly performance can be improved when the first actuator  111  is engaged with the second group rack member  24   a.    
     Furthermore, the position of the first guide bar  21  in a plane perpendicular to the optical axis A of the imaging optical system may not be a position on the extended line of the actuating direction of the rack spring  27   a . According to such a configuration, sliding resistance at the second group lens barrel  20   a  and the first guide bar  21  can be reduced, and thereby a load in driving on the first actuator  111  can be reduced. As described above, it is possible to increase assembly performance of the imaging device  1  while reducing the load applied to the first actuator  111 . 
     Note that, in the present embodiment, although the configuration in which the first cam follower  231  and the second cam follower  232  are engaged with the same cam groove (the second group cam groove  82 ) has been illustrated as an example, the embodiment is not limited to such a configuration. For example, the first cam follower  231  and the second cam follower  232  may be configured to be engaged with different cam grooves, respectively, and actuated to the inner circumferential surface of each cam groove. Further, although the configuration in which the first cam follower  231  and the second cam follower  232  are actuated in the direction of separating from each other in the Y-direction has been illustrated as an example, the first cam follower  231  and the second cam follower  232  may be configured to be actuated in the direction of approaching each other. 
     Second Embodiment 
     Next, an imaging device  1  according to a second embodiment of the present invention will be described. In the imaging device  1  according to the second embodiment, configurations of a second group lens barrel  20   a , a second group rack member  24   b , and a rack spring  27   b  are different from those of the first embodiment, and the same configuration can be applied to others. Therefore, a part to which a configuration common to the first embodiment can be applied is labeled with the same reference numeral as in the first embodiment, and the description thereof may be omitted. 
       FIG. 10  is a perspective view schematically illustrating a configuration example of a second group lens barrel  20   b  and a second group rack member  24   b  of the imaging device  1  according to the second embodiment of the present invention.  FIG. 11A  to  FIG. 11F  are diagrams schematically illustrating a configuration example of a part of the second group lens barrel  20   b  (optical member-holding member) and a second group rack member  24   b  of the imaging device  1  according to the second embodiment. Note that  FIG. 11A  is a diagram when viewed from the −X-side,  FIG. 11B  is a diagram when viewed from the +X-side,  FIG. 11C  is a diagram when viewed from the +Y-side,  FIG. 11D  is a diagram when viewed from the −Z-side,  FIG. 11E  is a diagram when viewed from the +Z-side, and  FIG. 11F  is a sectional view when viewed from the +Y-side. 
     The second group rack member  24   b  is actuated by the rack spring  27   b , which is an example of an actuation member, in the direction perpendicular to the direction parallel to the optical axis A of the imaging optical system. The rack spring  27   b  has an elastically compressively deformable compression coil spring portion  271   b  (compression spring portion), which is an example of a second actuation portion, and has two arm portions  272   b , which are an example of a first actuation portion. A torsion spring can be applied to the rack spring  27   b  in the second embodiment. However, the direction of the axis line of the coil spring portion  271   b  of the rack spring  27   b  and the configuration (the protruding direction) of the arm portion  272   b  provided so as to protrude from both end portions of the coil spring portion  271   b  are different compared to the first embodiment. 
     The axis line of the coil spring portion  271   b  (compression spring portion) is in parallel to the Y-direction. Further, the coil spring portion  271   b  of the rack spring  27   b  is arranged between the second group rack member  24   b  and the second group lens barrel  20   b  and actuates the second group rack member  24   b  (the second cam follower  232 ) and the second group lens barrel  20   b  (the first cam follower  231 ) in the direction of separating from each other in the Y-direction (circumferential direction of the cam cylinder  80 ). Therefore, backlash between the first cam follower  231  and the cam cylinder  80  and between the second cam follower  232  and the cam cylinder  80  can be reduced. 
     That is, the first cam follower  231  and the second cam follower  232  are engaged with the same single second group cam groove  82 . Further, the first cam follower  231  and the second cam follower  232  are actuated by the rack spring  27   b  in the direction of separating from each other in the tangential direction of the circle of the cam cylinder  80  (±Y-direction). Thereby, the first cam follower  231  and the second cam follower  232  will push (being actuated to come into contact with) the two inner peripheral surfaces (two wall surfaces) of the second group cam groove  82  in the opposite direction, respectively (+Y and −Y-directions, that is, at least a direction different from the extending direction of the second group cam groove  82 ). Therefore, backlash between the first cam follower  231  and the cam cylinder  80  and between the second cam follower  232  and the cam cylinder  80  is reduced. 
     The rack spring  27   b  provides an actuation in the direction of rotation about the center axis of the coil spring portion  271   b  (compression spring portion) by using the two arm portions  272   b . Specifically, as illustrated in  FIG. 11E  and  FIG. 11F , the two arm portions  272   b  of the rack spring  27   b  extend within the X-Z-plane. One arm portion  272   b  of the rack spring  27   b  is engaged with (comes into contact with) the second group rack member  24   b , and the other arm portion  272   b  is engaged with (comes into contact with) the second group lens barrel  20   b.    
     The second group rack member  24   b  (the actuator connecting portion  241   b  ) and the second group lens barrel  20   b  are then actuated in the direction of separating from each other in ±Z-direction by actuation force (moment) of the two arm portions  272   b  within the X-Z-plane. Thereby, the actuator connecting portion  241   b  is engaged with the first actuator  111  with the second group rack member  24   b  being actuated toward the first actuator  111 . Further, the second group lens barrel  20   b  is actuated to the second guide bar  22  by the moment (force in the rotational direction) about the first guide bar  21 . Therefore, backlash between the second group lens barrel  20   b  and the second guide bar  22  can be reduced. 
     Note that, as illustrated in  FIG. 10  and  FIG. 11A  to  FIG. 11F , when viewed in the optical axis A direction (in the Y-Z-plane), the position where the second group lens barrel  20   b  is guided by the first guide bar  21  is out of the extension line of actuation force applied by the arm portion  272   b  (first actuation portion) of the rack spring  27   b . Similarly, the position where the second group lens barrel  20   b  is engaged with the second guide bar  22  is out of the extension line of actuation force applied by the arm portion  272   b  (first actuation portion) of the rack spring  27   b . With such a configuration, the second group lens barrel  20   b  is actuated to both the first guide bar  21  and the second guide bar  22 , and backlash to the first guide bar  21  and the second guide bar  22  can be reduced. 
     As described above, the backlash of the two cam followers to the cam cylinder  80  (the first cam follower  231  and the second cam follower  232 ) and the backlash of the second group lens barrel  20   b  to the first actuator  111  can be reduced by the single rack spring  27   b . Therefore, according to such a configuration, the same advantage as in the first embodiment can be achieved. 
     Also in the second embodiment, as with the first embodiment, the second group lens barrel  20   b  and the second group rack member  24   b  may have detachment prevention portions  201   b  and  242   b , respectively. For example, the detachment prevention portion  201   b  of the second group lens barrel  20   b  is configured to be able to latch on the +Y-direction side (direction of actuation force of the coil spring portion  271   b  of the rack spring  27   b ) of the detachment prevention portion  242   b  of the second group rack member  24   b.    
     Specifically, as illustrated in  FIG. 11C ,  FIG. 11D , and  FIG. 11E , the detachment prevention portion  201   b  of the second group lens barrel  20   b  is located on the +Y-direction side of the detachment prevention portion  242   b  of the second group rack member  24   b  and is provided with a groove or the like extending in the Y-direction. Further, a part of the second group rack member  24   b  enters the groove of the detachment prevention portion  201   b . The second group rack member  24   b  is able to move in the +Y-direction up to a position where the detachment prevention portion  242   b  latches to (comes into contact with) the detachment prevention portion  201   b  of the second group lens barrel  20   b . Then, the detachment prevention portion  242   b  of the second group rack member  24   b  is actuated toward the detachment prevention portion  201   b  of the second group lens barrel  20   b  by actuation force of the coil spring portion  271   b  of the rack spring  27   b . Thereby, detachment of the second group rack member  24   b  from the second group lens barrel  20   b  is prevented. 
     Note that the detachment prevention portion  242   b  of the second group rack member  24   b  may be of any configuration that can be latched to the detachment prevention portion  201   b  of the second group lens barrel  20   b , and the specific configuration thereof is not particularly limited. According to such a configuration, the second group rack member  24   b  is not detached due to actuation force of the rack spring  27   b  even after the second group rack member  24   b , the rack spring  27   b , and the second group lens barrel  20   b  are assembled. Therefore, a state where the second group rack member  24   b  and the rack spring  27   b  are assembled with the second group lens barrel  20   b  is maintained (the engaged state is maintained) when the first actuator  111  is attached. Accordingly, assembly performance of the imaging device  1  is improved. 
     Furthermore, also in the second embodiment, an insertion guide portion  202   b  may be provided to the detachment prevention portion  201   b  of the second group lens barrel  20   b . The insertion guide portion  202   b  has an inclined surface inclined to the direction of actuation force of the coil spring portion  271   b  of the rack spring  27   b . Further, in response to being actuated toward the insertion guide portion  202   b  by actuation force of the coil spring portion  271   b  of the rack spring  27   b , a part of the second group rack member  24   b  (for example, the detachment prevention portion  242   b  ) is actuated toward the cam cylinder  80  side by the inclined surface of the insertion guide portion  202   b . Therefore, as with the first embodiment, the position of the second cam follower  232  in the circumferential direction of the cam cylinder  80  (the position to the second group cam groove  82 ) is restricted. 
     Note that the position in the Y-direction of the inclined surface of the insertion guide portion  202   b  may be any position that facilitates the second cam follower  232  to be engaged with the second group cam groove  82  (the position close to the second group cam groove  82 ) of the cam cylinder  80  and is not particularly limited. According to such a configuration, assembly performance can be improved when the first actuator  111  is engaged with the second group rack member  24   b.    
     Furthermore, the position of the first guide bar  21  within a plane perpendicular to the optical axis A of the imaging optical system may be a position which is not on the extended line of the actuating direction of the rack spring  27   b . According to such a configuration, sliding resistance at the second group lens barrel  20   b  and the first guide bar  21  can be reduced, and thereby a load in driving on the first actuator  111  can be reduced. As described above, it is possible to increase assembly performance of the imaging device  1  while reducing the load applied to the first actuator  111 . 
     Surveillance Camera 
     Next, a surveillance camera  900  according to an embodiment of the present invention will be described with reference to the  FIG. 12 .  FIG. 12  is a sectional view schematically illustrating a configuration example of the surveillance camera  900  according to the embodiment of the present invention. The imaging device  1  according to the embodiment of the present invention is applied to the surveillance camera  900  according to the embodiment of the present invention. As illustrated in  FIG. 12 , the surveillance camera  900  has the imaging device  1 , a camera case  904 , an inner cover  903 , a tilt unit  905 , a pan unit  906 , a dome  901 , and a case  902 . 
     The camera case  904  is a member that accommodates the imaging device  1 . The tilt unit  905  supports the camera case  904  accommodating the imaging device  1  so as to be rotatable about a tilt axis T. Note that the tilt unit  905  has a tilt drive portion (not illustrated) formed of a stepping motor or the like, and the camera case  904  is driven in a tilt direction by the tilt drive portion. The pan unit  906  supports the tilt unit  905  so as to be rotatable about a pan axis P. The pan unit  906  has a pan drive portion (not illustrated) formed of a stepping motor or the like and the tilt unit  905  is electrically driven in a pan direction. 
     Thereby, the imaging device  1  is driven in the tilt direction and the pan direction. Further, the imaging device  1 , the camera case  904 , the inner cover  903 , the tilt unit  905 , and the pan unit  906  are accommodated in (covered with) the case  902  and a dome  901 . The dome  901  is a transparent or translucent plastic cover member. Note that the configuration described above is a configuration example of the surveillance camera, and the surveillance camera of the present invention is not limited to such a configuration. In short, the surveillance camera of the present invention may be of any configuration that has the imaging device of the present invention. 
     While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions. 
     The present invention is a preferable technology for imaging devices. Further, according to the present invention, it is possible to reduce the number of components and reduce the load applied to the actuator. 
     This application claims the benefit of Japanese Patent Application No. 2017-242919, filed Dec. 19, 2017, which is hereby incorporated by reference herein in its entirety.