Abstract:
An aspect of the present invention provides an image taking apparatus, comprising: a solid-state image sensor; and a taking lens including a lens barrel that houses a lens disposed in front of the solid-state image sensor, wherein a shielding member that blocks an electromagnetic wave radiated from the front surface of the solid-state image sensor is provided on an outer circumference of the lens barrel, and a metallic member electrically floating in the lens barrel is grounded.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an image taking apparatus. More specifically, it relates to a technique for eliminating electromagnetic interference (EMI). 
     2. Description of the Related Art 
     There is an increasing demand for digital cameras, such as digital still camera and digital video camera, that incorporate a solid-state image sensor, such as charge coupled device (CCD) and complementary metal oxide semiconductor (CMOS). 
     In recent years, solid-state image sensors are improved in resolution, and accordingly, digital cameras are required to read image signals from a solid-state image sensor at higher clock frequency to read image signals at higher rate. 
     A conventional digital camera, which drives the solid-state image sensor at a clock frequency of 30 MHz, does not have a problem of EMI. However, if the clock frequency is raised to 60 MHz or higher, there arises a problem that an electromagnetic wave higher than the criterion level occurs via the taking lens of the digital camera. 
     Although the drive circuit for driving the solid-state image sensor generates the strongest electromagnetic wave, the electromagnetic wave can be blocked by surrounding the drive circuit with a shielding member. However, there remains a problem that the electromagnetic wave generated from the front of the solid-state image sensor driven by the drive circuit cannot be blocked by the shielding member because the optical path for picture taking has to be ensured. 
     In order to solve the problem, there have been proposed a solid-state image sensor module for an endoscope and an image taking apparatus that have an optically-transparent electromagnetic shielding layer on the light-receiving surface of the solid-state image sensor. 
     SUMMARY OF THE INVENTION 
     However, if an optically-transparent electromagnetic shielding layer is disposed on the light-receiving surface of the solid-state image sensor or the like as described in the Japanese Patent Application Laid-Open Nos. 5-56916 and 7-38789, the amount of light incident on the solid-state image sensor decreases. If the thickness of the electromagnetic shielding layer is reduced to avoid the decrease of the amount of incident light, there arises a problem that the shielding effect becomes inadequate. 
     The present invention has been made in view of such circumstances, and an object of the present invention is to provide an image taking apparatus that can solve the problem of EMI of an electromagnetic wave radiated from the front surface of a solid-state image sensor without an optically-transparent electromagnetic shielding layer disposed on the light-receiving surface of the solid-state image sensor or the like. 
     In order to attain the object described above, according to a first aspect of the present invention, there is provided an image taking apparatus comprising: a solid-state image sensor; and a taking lens including a lens barrel that houses a lens disposed in front of the solid-state image sensor, in which a shielding member that blocks an electromagnetic wave radiated from a front surface of the solid-state image sensor is provided on an outer circumference of the lens barrel, and a metallic member electrically floating in the lens barrel is grounded. 
     The inventors have found that if the electromagnetic wave radiated from the front surface of the solid-state image sensor is incident on the electrically floating metallic member, the metallic member serves as a resonant antenna and radiates a strong electromagnetic wave. 
     Thus, the shielding member that blocks the electromagnetic wave radiated from the front surface of the solid-state image sensor is provided on the outer circumference of the lens barrel, thereby providing the electromagnetic wave radiated from the front surface of the solid-state image sensor with a certain directivity in the direction of the optical axis of the taking lens, thereby preventing the electromagnetic wave from being incident on the metallic member electrically floating in front of the solid-state image sensor. In addition, the metallic member electrically floating in the lens barrel is grounded, thereby preventing the metallic member from serving as a resonant antenna. It is to be noted that the strength of the electromagnetic wave itself that is radiated from the front surface of the solid-state image sensor and travels straight substantially in the direction of the optical axis of the taking lens is sufficiently lower than the level that causes the EMI problem. 
     According to a second aspect of the present invention, in the image taking apparatus according to the first aspect of the present invention, the shielding member covers the outer circumference of the lens barrel and the front surface of the lens barrel except for an opening of the lens barrel. Since the shielding member covers the front surface of the lens barrel except for the opening of the lens barrel, the directivity of the electromagnetic wave radiated from the front surface of the solid-state image sensor is further increased. 
     According to a third aspect of the present invention, the image taking apparatus according to the first or second aspect of the present invention further comprises a shielding plate that covers the front surface of the solid-state image sensor except for a light-receiving area thereof, and the shielding plate blocks an electromagnetic wave radiated from the front surface of the solid-state image sensor except for the light-receiving area. Since the electromagnetic wave is radiated from only the light-receiving area of the front surface of the solid-state image sensor, the area that radiates the electromagnetic wave is minimized. 
     According to a fourth aspect of the present invention, in the image taking apparatus according to any of the first to third aspects of the present invention, the taking lens is a rear focus type zoom lens including a first lens group for changing magnification and a second lens group disposed in the rear of the first lens group for performing correction and focusing when changing magnification, and the lens barrel is a focus lens guide sleeve that houses the second lens group. 
     According to a fifth aspect of the present invention, in the image taking apparatus according to the fourth aspect of the present invention, the metallic member is a guide shaft for a focus lens that moves in the focus lens guide sleeve. 
     Since the guide shaft for the focus lens that moves in the focus lens guide sleeve is electrically floating, and the electromagnetic wave radiated from the front surface of the solid-state image sensor is incident on the guide shaft, the guide shaft would otherwise serve as a resonant antenna and radiate a strong electromagnetic wave. However, since the guide shaft is grounded, the guide shaft is prevented from serving as a resonant antenna. 
     According to a sixth aspect of the present invention, in the image taking apparatus according to the fourth aspect of the present invention, the metallic member is a guide shaft for a focus lens that moves in the focus lens guide sleeve, and one end of the guide shaft is in contact with the shielding plate and thereby grounded. Thus, the guide shaft can be grounded without increasing the number of components (of course, the shielding plate is grounded). 
     According to a seventh aspect of the present invention, in the image taking apparatus according to any of the first to sixth aspects of the present invention, the taking lens is connected to a flexible wiring board and has a driving device that drives an optical member in the taking lens, and the flexible wiring board is laid along the shielding member in such a manner that a length of a part of the flexible wiring board between the driving device and the shielding member is minimized. 
     If the electromagnetic wave is incident on the flexible wiring board, the flexible wiring board radiates an electromagnetic wave. However, since the length of the part of the flexible wiring board on which the electromagnetic wave is incident (the length of the part of the flexible wiring board between the driving device and the front end of the lens barrel covered with the shielding member) is minimized, the wiring pattern on the flexible wiring board is prevented from serving as a resonant antenna and radiating an electromagnetic wave, or the electromagnetic wave radiated by the wiring pattern on the flexible wiring board is minimized. 
     According to an eighth aspect of the present invention, in the image taking apparatus according to the seventh aspect of the present invention, the driving device includes two or more of a shutter actuator, a diaphragm actuator, a camera-shake correcting actuator and a focusing actuator, and the two or more actuators are placed at different circumferential positions in the taking lens. Thus, the flexible wiring board has a number of branches at one end depending on the number of actuators and is wound around the shielding member according to the circumferential positions of the actuators in the taking lens. 
     According to the present invention, the metallic members electrically floating in the taking lens are electromagnetically shielded, and any metallic member that cannot be electromagnetically shielded is grounded. Therefore, if the electromagnetic wave is radiated from the front surface of the solid-state image sensor, the metallic members are prevented from serving as a resonant antenna and radiating a strong electromagnetic wave. Therefore, even if the solid-state image sensor is driven at a high clock frequency (60 MHz or higher, for example), the EMI problem can be avoided. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front perspective view showing an appearance of a digital camera according to an embodiment of the present invention; 
         FIG. 2  is a schematic cross-sectional view showing a configuration of a taking lens; 
         FIG. 3  is a schematic rear view showing a configuration of the taking lens; 
         FIG. 4  is a perspective view showing a layout of a flexible wiring board; 
         FIG. 5  is a schematic cross-sectional view showing a configuration of a taking lens according to another embodiment; 
         FIG. 6  is an enlarged view of essential parts of the taking lens shown in  FIG. 5 ; 
         FIG. 7  is a schematic perspective view showing a configuration of the taking lens according to the other embodiment; and 
         FIG. 8  is a schematic side view showing a configuration of the taking lens according to the other embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the following, an image taking apparatus according to a preferred embodiment of the present invention will be described with reference to the accompanying drawings. 
       FIG. 1  is a front perspective view showing an appearance of a digital camera to which the present invention is applied. 
     As shown in  FIG. 1 , a digital camera  10  is a lens-integrated single-lens reflex camera incorporating an electronic viewfinder, and a taking lens  12  is attached to the front of a camera main body  14  to form an integral unit. 
     The camera main body  14  is L-shaped, a left-hand part thereof constitutes a grip  16 , and the taking lens  12  is attached to the front thereof to form an integral unit. The taking lens  12  is a rear focus type zoom lens and has an optical camera-shake correcting function. 
     The camera main body  14  has a pop-up type flash device  18 , a hot shoe  20 , a mode dial  22 , a command dial  24 , a shutter button  26 , a power lever  28  and the like on the top thereof. Although not shown, the camera main body  14  further has an electronic viewfinder, a liquid crystal monitor, a cross-hair button, a menu button, an OK button, a cancel button and the like on the back side thereof  FIG. 2  is a schematic cross-sectional view showing a configuration of the taking lens  12 , and  FIG. 3  is a rear view of the taking lens  12 . 
     As described above, the taking lens  12  is a rear focus type zoom lens with an optical camera-shake correcting function. In a lens barrel  30  thereof, a zoom lens group  32 , a diaphragm/shutter unit  34 , a camera-shake correcting unit  36 , and a focus lens group  38  are housed and arranged along an optical axis L in this order from the front end of the lens barrel  30 . 
     The lens barrel  30  includes a cylindrical inner sleeve  40 , a rotating sleeve  42  that is fitted over the outer circumference of the inner sleeve  40  and capable of rotating, and an outer sleeve  44  that covers the outer circumference of the rotating sleeve  42 . The lens barrel  30  is attached to a lens holder  60  in the camera main body  14 . The outer sleeve  44  is fixed to the inner sleeve  40  at the base end thereof, and the rotating sleeve  42  rotates in the space between the inner sleeve  40  and the outer sleeve  44 . 
     A zoom ring  46  is integrally attached to a front end part of the rotating sleeve  42  and extends forward from the front end of the outer sleeve  44 . The rotating sleeve  42  is rotated in the space between the inner sleeve  40  and the outer sleeve  44  by rotating the zoom ring  46 . 
     The lens holder  60  has a plate-like shape and has an opening  60 A for a CCD in the middle thereof (on the optical axis L). The lens holder  60  has an integrally formed holding frame  62  for holding the lens barrel  30  on front surface thereof. The lens barrel  30  is attached to the lens holder  60  by fitting the base end part of the inner sleeve  40  into the holding frame  62  and integrally fixed to the lens holder  60  by fixing the base end part of the inner sleeve  40  to the lens holder  60  by a screw (not shown). 
     The lens holder  60  is fixed to a main body frame (not shown) of the camera main body  14  by a screw (not shown). Therefore, the lens barrel  30  is integrally fixed to the camera main body  14  by fixing the lens barrel  30  to the lens holder  60 . 
     The zoom lens group  32  is to adjust the magnification of the taking lens  12 . The zoom lens group  32  is held in a zoom lens frame  48 . 
     The zoom lens frame  48  has a cylindrical shape and has three cam pins  50  extending radially on the outer circumference thereof Each cam pin  50  is inserted in a straight groove  52  formed in the inner sleeve  40 , and the tip end thereof is fitted into a cam groove  54  formed in the inner surface of the rotating sleeve  42 . 
     If the zoom ring  46  and thus the rotating sleeve  42  rotate, the zoom lens frame  48  moves back and forth along the optical axis L as a result of interaction among the cam pins  50 , the straight grooves  52  and the cam grooves  54 . Thus, the zoom lens group  32  also moves back and forth along the optical axis L, thereby changing the focal length of the taking lens  12 . 
     The diaphragm/shutter unit  34  is to adjust the aperture and exposure of the taking lens  12 . The diaphragm/shutter unit  34  is fixed to the inner surface of the inner sleeve  40  by a bracket  56  and has a diaphragm and a mechanical shutter (not shown). The diaphragm is driven by a diaphragm actuator (not shown) incorporated in the diaphragm/shutter unit  34  to adjust the aperture of the taking lens  12 . The mechanical shutter is driven by a shutter actuator (not shown) incorporated in the diaphragm/shutter unit  34  to adjust the exposure of a CCD. 
     The camera-shake correcting unit  36  is to compensate for an image blurring on the imaging surface caused by hand movement. The camera-shake correcting unit  36  is fixed to the inner surface of the inner sleeve  40  by a bracket  58  and has a correcting lens (not shown). The correcting lens is capable of moving in a plane perpendicular to the optical axis L in the panning and the tilting direction. The correcting lens is driven by a camera-shake correcting actuator (not shown) incorporated in the camera-shake correcting unit  36  in a direction to eliminate the image blurring. In this way, the image blurring on the imaging surface caused by hand movement is compensated for. 
     The focus lens group  38  is to make a correction and a focus adjustment when changing the magnification. The focus lens group  38  is housed in a focus lens guide sleeve  70  disposed in the inner sleeve  40 . 
     The focus lens guide sleeve  70  has a cylindrical shape, and the outer surface thereof is covered with a metallic shielding member  72  capable of blocking electromagnetic waves. Typically, the shielding member is made of a conductive metal, and the shielding effect is improved if the shielding member is grounded. 
     The focus lens guide sleeve  70  is disposed on the optical axis L and integrally fixed to the lens holder  60  by fixing a flange part  70 A integrally formed at the base end part thereof to the lens holder  60  by a screw (not shown). 
     The focus lens group  38  housed in the focus lens guide sleeve  70  is held in a focus lens frame  74 . A pair of guide parts  76  extends from the outer circumference of the focus lens frame  74 . Each guide part  76  has a guide hole  78  formed along the optical axis L, and a guide shaft  80  extending in the focus lens guide sleeve  70  along the optical axis L is inserted in each guide hole  78 . The focus lens frame  74  is slidably supported by the guide shafts  80 , and thus, the focus lens group  38  is supported so that the focus lens group  38  can move along the optical axis L. 
     The guide shaft  80  slidably supporting the focus lens frame  74  is made of metal and cantilevered with the base end part inserted in through holes  82  and  84  formed in the lens holder  60  and the focus lens frame  74 , respectively. The inner diameter of the through holes  82  and  84  are slightly smaller than the outer diameter of the guide shaft  80 , so that the guide shaft  80  is supported by interference fit into the through holes  82  and  84 . As described later, the base end part of the guide shaft  80  is exposed at the back surface of the lens holder  60  through the through hole  82  and is in contact with a metallic shielding plate  106  attached to the lens holder  60 . 
     A focusing motor  86  is mounted on the outer circumference of the focus lens guide sleeve  70 , and a threaded rod  88  extending along the optical axis L is coupled to the rotating shaft of the focusing motor  86 . A nut member  90  is screwed onto the threaded rod  88 , and the nut member  90  is coupled with one of the guide parts  76  of the focus lens frame  74  via a coupling member  91 . When the focusing motor  86  is activated and rotates the threaded rod  88 , the nut member  90  moves along the threaded rod  88  back and forth according to the rotation of the threaded rod  88 , thereby making the focus lens group  38  held in the focus lens frame  74  move back and forth along the optical axis L. 
     For example, transmission of a driving signal and supply of electric power to the focusing motor  86  for driving the focus lens group  38  are accomplished via a flexible wiring board  92  connected to a main board (not shown) in the camera main body  14 . Similarly, for example, transmission of a driving signal and supply of electric power to the diaphragm actuator for driving the diaphragm of the diaphragm/shutter unit  34 , the shutter actuator for driving the mechanical shutter, and the camera-shake correcting actuator for driving the correcting lens of the camera-shake correcting unit  36  are accomplished via the flexible wiring board  92 . 
     The flexible wiring board  92  connected to the driving actuators in the taking lens  12  is introduced into the taking lens  12  through a wiring inlet  94  formed in the outer circumference of the base end part of the inner sleeve  40  and laid along the outer circumference of the focus lens guide sleeve  70  covered with the shielding member  72  as shown in  FIG. 4 . The flexible wiring board  92  laid along the outer circumference of the focus lens guide sleeve  70  covered with the shielding member  72  has branches for the driving actuators disposed in front of the focus lens guide sleeve  70  that extend straight along the optical axis L. Specifically, the flexible wiring board  92  has a base part  92 A that is laid along the outer circumference of the focus lens guide sleeve  70  covered with the shielding member  72  and extension parts  92 B that extend from the base part  92 A perpendicularly along the optical axis L, and the straight extension parts  92 B of the flexible wiring board  92  are connected to the driving actuators positioned in front of the focus lens guide sleeve  70 . 
     Thus, the length of the part of the flexible wiring board from the front end of the focus lens guide sleeve  70  to the wiring connection part of each driving actuator positioned in front of the focus lens guide sleeve  70  covered with the shielding member  72  can be minimized, so that the effect of unwanted radiation can be minimized. 
     In this embodiment, since the diaphragm actuator and the shutter actuator in the diaphragm/shutter unit  34  and the camera-shake correcting actuator in the camera-shake correcting unit  36  are positioned in front of the focus lens guide sleeve  70  covered with the shielding member  72 , the extension parts  92 B extending straight are connected to wiring connection parts  34 A and  36 A of the actuators. 
     In this embodiment, one flexible wiring board  92  has branches, and the branches are connected to the wiring connection parts of the driving actuators. However, separate flexible wiring boards may be prepared and connected to the wiring connection parts of the driving actuators. 
     The taking lens  12  is configured as described above, and a CCD  100  is attached to the lens holder  60  with the taking lens  12  attached thereto. 
     In this embodiment, a CCD is used as the solid-state image sensor. However, other solid-state image sensors, such as a CMOS device, can also be used. 
     The CCD  100  is integrally attached to a CCD substrate  104  via a CCD holder  102 . The CCD  100  is attached to the lens holder  60  by fixing the CCD substrate  104  to the lens holder  60  at a predetermined position on the back surface thereof by a screw (not shown). 
     The shielding plate  106  capable of blocking an electromagnetic wave is attached to the back surface of the lens holder  60  to which the CCD  100  is attached. The shielding plate  106  is to block the electromagnetic wave radiated from the front surface of the CCD  100  except for the light-receiving area. 
     The shielding plate  106  is made of metal and has a disk-like shape, and the outer diameter of the shielding plate  106  is larger than the inner diameter of the lens barrel  30 . 
     The shielding plate  106  has a depressed part  106 A, into which the CCD holder  102  can be fitted, at the center thereof. An opening  106 B, the size of which is substantially equal to that of the light-receiving area of the CCD  100 , is formed in the depressed part  106 A. 
     The shielding plate  106  is attached to the lens holder  60  by fitting the depressed part  106 A into the opening  60 A of the lens holder  60 . The shielding plate  106  is integrally fixed to the lens holder  60  by a screw (not shown). 
     The metallic shielding plate  106  attached to the lens holder  60  is connected to a metallic frame  110  of the camera main body  14  via a grounding cable  108 . In other words, the shielding plate  106  is grounded. 
     The metallic shielding member  72  covering the outer surface of the focus lens guide sleeve  70  described above is also connected to the metallic frame  110  of the camera main body  14  via a grounding cable  112 . In other words, the shielding member  72  is also grounded. 
     As a result of attachment of the shielding plate  106  to the lens holder  60 , the guide shafts  80  are in contact with the shielding plate  106 , and therefore, the guide shafts  80  are also grounded. 
     The CCD  100  is attached to the lens holder  60  by fixing the CCD substrate  104  to the lens holder  60  with the shielding plate  106  by a screw (not shown). Once the CCD  100  is attached to the lens holder  60 , only the light-receiving area is exposed through the opening  60 A of the lens holder  60 , while the other area is covered with the shielding plate  106 . Thus, the electromagnetic wave radiated from the front surface of the CCD  100  except for the light-receiving area is blocked by the shielding plate  106 . 
     A circuit board  116  is connected to the CCD substrate  104  with the CCD  100  attached thereto via a flexible wiring board  114  and fixed to the back surface of the lens holder  60  by a screw (not shown). A CCD driving circuit for driving the CCD  100 , a lens driving CPU, an analog signal processing circuit that performs correlated double sampling of image signals output from the CCD  100  and appropriate gain amplification, an A/D converter circuit that converts the image signals processed by the analog signal processing circuit into digital image data (CCD-RAW data), a data communication circuit for transmitting the image data to the camera main body  14 , and the like are mounted on the circuit board  116  and connected to the main board (not shown) in the camera main body  14  via a flexible wiring board  118 . 
     The digital camera  10  thus configured according to this embodiment operates in the following manner. 
     The shielding plate  106  is attached to the lens holder  60  to which the CCD  100  is attached, and the electromagnetic wave radiated from the front surface of the CCD  100  except for the light-receiving area is blocked by the shielding plate  106 . 
     The shielding plate  106  cannot block the electromagnetic wave radiated from the light-receiving area of the CCD  100  into the lens barrel  30 . However, the digital camera  10  according to this embodiment has the focus lens guide sleeve  70  surrounding the space in front of the CCD  100 , and the outer surface of the focus lens guide sleeve  70  is covered with the shielding member  72 . As a result, the range of radiation of the electromagnetic wave from the light-receiving area of the CCD  100  is limited by the shielding member  72 , and the electromagnetic wave has a certain directivity in the direction of the optical axis of the taking lens  12 . 
     Since the electromagnetic wave radiated from the light-receiving area of the CCD  100  has a certain directivity in the direction of the optical axis of the taking lens  12 , the electromagnetic wave can be prevented from being incident on a metallic member electrically floating in front of the CCD  100 , and the metallic member can be effectively prevented from serving as a resonant antenna. 
     Thus, the problem of EMI does not arise even if the CCD  100  is driven at a high clock frequency (60 MHz, for example). Furthermore, the problem of EMI of the electromagnetic wave radiated from the front surface of the CCD  100  can be solved without an optically transparent electromagnetic shielding layer disposed on the light-receiving area of the CCD  100  or the like. 
     Although it is not possible to prevent the electromagnetic wave radiated from the light-receiving area of the CCD  100  from being incident on the metallic members disposed in the focus lens guide sleeve  70 , the metallic members disposed in the focus lens guide sleeve  70  are grounded to prevent the members from serving as a resonant antenna. In the digital camera  10  according to this embodiment, the guide shafts  80  are such members. Thus, the guide shafts  80  are brought into contact with the metallic shielding plate  106  and thereby grounded, so that the guide shafts  80  are prevented from serving as a resonant antenna. 
     While the guide shafts  80  are brought into contact with the shielding plate  106  and thereby grounded in this embodiment, a grounding cable may be connected to the guide shafts  80 , and the grounding cable may be connected to a frame or the like connected to the ground. However, if the guide shafts  80  are in contact with the shielding plate  106  and thereby grounded as in this embodiment, the number of components is reduced, and the structure is simplified. 
     In the digital camera  10  according to this embodiment, the guide shafts  80  are the only metallic members disposed in the focus lens guide sleeve  70 . However, if there is another metallic member disposed in the focus lens guide sleeve  70 , the member is also grounded by connecting the member to the shielding plate  106  as with the guide shafts  80  or the like. For example, if a screw is disposed in the focus lens guide sleeve  70 , the screw is also grounded by connecting the screw to the shielding plate  106  or the like. 
     The flexible wiring board  92  also radiates an electromagnetic wave if an electromagnetic wave is incident thereon. However, in the digital camera  10  according to this embodiment, the flexible wiring board is laid in such a manner that the length of the part of the flexible wiring board on which the electromagnetic wave is incident (the length of the part of the flexible wiring board between the wiring connection part of each driving actuator and the front end of the focus lens guide sleeve  70  covered with the shielding member  72 ) is minimized, so that the wiring pattern on the flexible wiring board can be effectively prevented from serving as a resonant antenna and radiating an electromagnetic wave. 
     Such a layout is particularly advantageous in a case where the wiring inlet for the flexible wiring board and the wiring connection part of the driving actuator are circumferentially displaced from each other or in a case where the flexible wiring board is connected to a plurality of driving actuators, and the wiring connection parts of the driving actuators are circumferentially displaced from each other. 
     In this embodiment, the outer surface of the focus lens guide sleeve  70  is covered with the shielding member  72 . However, the way of covering the outer surface of the focus lens guide sleeve  70  is not particularly limited. For example, the outer surface of the focus lens guide sleeve  70  can be covered with a metallic cover, which has a shape conforming to the contour of the focus lens guide sleeve  70  and serves as the shielding member. Alternatively, the outer surface of the focus lens guide sleeve  70  can be plated with metal, which serves as the shielding member. 
     In this embodiment, the outer surface of the focus lens guide sleeve  70  is covered with the shielding member  72 , thereby preventing the electromagnetic wave radiated from the front surface of the CCD  100  from being radiating in the radial direction. However, the shielding member can be separated from the focus lens guide sleeve  70 . For example, as shown in  FIGS. 5 and 6 , the focus lens guide sleeve  70  can be surrounded by a cylindrical shielding member  120 , and radial radiation of the electromagnetic wave radiated from the light-receiving area of the CCD  120  can be prevented by the cylindrical shielding member  120 . In this case, preferably, the front end of the shielding member  120  is covered with a lid member  122 , and an opening  122 A having the minimum size required for exposure of the CCD  100  is formed in the lid member  122 . If this is the case, radial radiation of the electromagnetic wave from the light-receiving area of the CCD  100  can be effectively blocked, and the electromagnetic wave radiated from the light-receiving area of the CCD  100  can have a directivity in the direction of the optical axis of the taking lens. 
     In the example shown in  FIGS. 5 and 6 , the shielding member  120  is connected directly to the shielding plate  106 . Thus, a grounding cable can be omitted, and the structure can be further simplified. The metallic guide shafts  80  for guiding the focus lens group  38  are also connected directly to the shielding plate  106 . In addition, the threaded rod  88  driven by the focusing motor  86  is also connected directly to the shielding plate  106 . As a result, the focusing motor  86  and the threaded rod  88  are also prevented from serving as a resonant antenna. 
     In the case where the shielding member  120  separated from the focus lens guide sleeve  70  is used in this way, as shown in  FIGS. 7 and 8 , the flexible wiring board  92  for the driving actuators is laid to extend along the outer circumference of the shielding member  120 . The flexible wiring board  92  for each driving actuator disposed in front of the shielding member  120  is laid so that the length thereof is minimized. Thus, the wiring pattern on the flexible wiring board  92  effectively is prevented from serving as a resonant antenna and radiating an electromagnetic wave. 
     While an example in which the present invention is applied to a digital camera has been described in this embodiment, the application of the present invention is not limited thereto, and the present invention can be applied to a video camera, and a digital camera incorporated in a cellular phone or the like, for example.