JP2005352236A - Imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an imaging apparatus where the optical axis of an imaging optical system is directed to a horizontal direction, a lens group and a shutter move in an optical axis direction, and flare due to light from the outside of a photographing object range hardly occurs. <P>SOLUTION: A digital camera (1) is equipped with the imaging optical system constituted of three lens groups (21, 22 and 23), an imaging device (24) and a shutter unit (25). A prism which folds the optical axis is included in the lens group (21), and most of the optical axis of the imaging optical system is directed to a right-and-left direction. A motor (33) and a driving shaft (35) for moving the lens group for zoom (22) and the shutter unit 25 are arranged upper than the optical axis of the imaging optical system. Then, a situation that light from a light source such as the sun positioned above the photographing object range is reflected by the motor (33) and the driving shaft (35) and advances to the imaging device (24) side passing through a gap between the shutter unit (25) and a lens barrel (12) is prevented, whereby the flare is prevented from occurring. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an imaging apparatus including a lens group movable in the optical axis direction and a shutter.

  The camera is equipped with several lenses to form an image of the light from the object to be photographed, in order to prevent external unnecessary light from being mixed into the light from the object to be photographed and to facilitate handling as a whole. The lens is housed in a lens barrel. Some lenses are fixed, while others are movable in the optical axis direction, such as for focus adjustment and zoom.

  Conventionally, a spiral screw is provided on the inner surface of the lens barrel, a screw that engages with the lens barrel screw is provided on the lens frame that holds the lens, and the lens is moved in the optical axis direction by rotating the lens barrel. I was trying to let them. In such a configuration in which the lens is moved by the rotation of the lens barrel, the rotating lens barrel is inevitably formed in a cylindrical shape, which is limited in shape and large enough to accommodate the entire lens frame of the movable lens. It is difficult to reduce the size.

  Furthermore, if a drive unit such as a motor for driving the movable lens is arranged in the lens barrel, the size of the lens barrel is further increased. Therefore, the drive unit needs to be arranged outside the lens barrel. At this time, if the drive unit is arranged on the side of the lens barrel, the total size of the lens barrel and the drive unit increases in a direction perpendicular to the optical axis of the lens, and the drive unit extends the lens barrel. If arranged above, the overall size increases in the optical axis direction of the lens.

  Therefore, a rod-shaped drive shaft provided with a spiral screw on the outer peripheral surface is arranged in parallel to the optical axis of the lens, and a screw that engages with the screw of the drive shaft is provided on the lens frame to rotate the drive shaft. The lens is moved by this. In this case, it is necessary to prevent the inclination and displacement of the optical axis. For this purpose, a guide shaft parallel to the optical axis of the lens is provided, and a through hole through which the guide shaft passes is provided in the lens frame. It is common to support the movably. In this configuration, there is no restriction on the shape of the lens barrel, and a drive unit that rotates the drive shaft can be arranged in the lens barrel together with the drive shaft and the guide shaft, so that the overall size can be easily suppressed. Become.

  In recent years, while adopting such a configuration, the optical axis of the imaging optical system is bent by a mirror or prism, and only a part of the optical axis (the end on the subject side) faces in the front-rear direction, and the optical axis is large. It is also attempted to reduce the thickness of the camera (downsizing in the front-rear direction) by making the portion face the left-right direction or the up-down direction.

In general, a camera includes a diaphragm that blocks a peripheral portion of a light beam and restricts the amount of light, and in many cases includes a shutter that blocks the entire light beam so as to expose only for a predetermined time. When a zoom lens is used as the imaging optical system, the ideal position of the shutter may vary depending on the focal length, and it is preferable to make the shutter movable. For example, Japanese Patent Laid-Open No. 5-2557057 discloses a camera in which a shutter is moved together with a zoom lens group.
Japanese Patent Laid-Open No. 5-257057

  In a camera that supports a movable lens with a guide shaft, the lens frame of the lens is separated from the lens barrel so that the movable lens can move smoothly, and between the lens frame and the inner surface of the lens barrel. There is a gap. When the shutter is also movable, it is preferable that the shutter is movably supported with the same configuration as that for supporting the movable lens, and a gap is also formed between the shutter and the lens barrel.

  The shutter is mainly intended to control the exposure time, but also has a function of preventing the occurrence of flare by blocking light coming from outside the imaging target range. For the same purpose, an antireflection coating is usually applied to the inner surface of the lens barrel. In a camera with a movable shutter, light may pass through the gap between the shutter and the lens barrel, but an anti-reflection coating is applied from the front end to the rear end of the shutter movement range on the inner surface of the lens barrel. In this case, no light passes through the gap, and flare can be prevented.

  However, in the configuration in which the driving unit and the driving shaft for driving the movable lens are arranged in the lens barrel, the light is reflected by the surface of the driving unit and the driving shaft and passes through the gap between the shutter and the lens barrel. There are things to do. In particular, in a configuration in which most of the optical axis of the imaging optical system is horizontal and the drive unit is disposed below the optical axis of the imaging optical system, light from an extremely bright light source such as the sun or an electric light causes flare. It becomes easy.

  The reason will be described with reference to the digital camera 7 of FIG. The digital camera 7 has a housing 80 that houses an imaging optical system and an imaging element 74. The casing 80 is provided with a shutter release button 81 on the top surface and an optical viewfinder 82 on the top. The imaging optical system includes a fixed first lens group 71 including a mirror or a prism, a movable second lens group 72 for zooming, and a movable third lens group 73 for focus adjustment. The lens group 72 and the third lens group 73 are accommodated in the lens barrel 70. The imaging optical system is set so that most of the optical axis is directed in the left-right direction.

  The lens barrel 70 moves integrally with a motor 75 and a drive shaft 77 for moving the second lens group 72, a motor 76 and a drive shaft 78 for moving the third lens group 73, and the second lens group 72. A shutter 79 is also accommodated. The motors 75 and 76 and the drive shafts 77 and 78 are disposed below the optical axis of the imaging optical system. A reflective coating is applied to the entire inner surface of the lens barrel 70, but since the shutter 79 is movable, there is a gap between the lens barrel 70 and the shutter 79.

  When there is a light source 83 such as the sun or an electric light, the light source 83 is positioned above the digital camera 7 in normal shooting, and the light L from the light source 83 is present even if the light source 83 is outside the shooting target range. Enters the lens barrel 70 through the first lens group 71. Part of the light L from the light source that has entered the lens barrel 70 is reflected by the surface of the motor 75 and the surface of the drive shaft 77, passes through the gap between the lens barrel 70 and the shutter 79, reaches the image sensor 74, and flares. It becomes.

  This inconvenience can be avoided by applying an antireflection coating to the surfaces of the motor 75 and the drive shaft 77. However, applying the antireflection coating to the motor 75 and the drive shaft 77 in addition to the inner surface of the lens barrel 70 reduces the manufacturing efficiency of the digital camera 7 and increases the cost. In addition, even if an antireflection coating is applied to the surface of the drive shaft 77, the reflection coat wears due to the engagement with the lens holding frame of the second lens group 72, so that the function cannot be exhibited over a long period of time. It becomes impossible to drive the second lens group 72 with high accuracy.

  A digital camera that uses a captured image as electronic data includes a display unit that displays the captured image and uses this as a finder. However, some digital cameras include an optical finder. When a zoom lens is used as the imaging optical system, it is preferable that the size of the optical image provided by the optical finder is variable according to the focal length. However, in the configuration in which the zoom lens group 72 moves in a direction perpendicular to the front-rear direction as in the digital camera 7 described above, the size of the image provided by the optical viewfinder 82 is set to the position of the lens group 72. The structure for interlocking tends to be complicated.

  The present invention has been made in view of such problems. The optical axis of the imaging optical system faces the horizontal direction, the lens group and the shutter are movable in the optical axis direction, and flare due to light from outside the imaging target range is generated. An object of the present invention is to provide an imaging device that is unlikely to occur. It is another object of the present invention to provide an image pickup apparatus having a simple configuration that changes the size of an image of an optical viewfinder in accordance with the focal length of an image pickup optical system.

  In order to achieve the above object, the present invention has an imaging device and an imaging optical system that includes a plurality of lens groups including a lens group movable in the optical axis direction, guides light to the imaging device, and a movable imaging optical system. And a shutter that is movable in the optical axis direction of the imaging optical system and that moves in the optical axis direction of the imaging optical system. An imaging apparatus that is held by a user so as to be substantially horizontal has a movable lens group of an imaging optical system and a driving unit that moves a shutter, and the driving unit is more than the optical axis of the imaging optical system during normal shooting. It is set as the structure provided in the upper position.

  In this imaging apparatus, during normal shooting, the drive unit is positioned above the optical axis of the imaging optical system, so light from a bright light source such as the sun or an electric light outside the shooting target range directly strikes the drive unit. There is no reflection. Therefore, the occurrence of flare can be prevented without applying an antireflection coating to the surface of the drive unit.

  Here, the imaging optical system may include a reflective element that reflects light, and the optical axis of the imaging optical system may be bent by the reflective element. If it does in this way, most optical axes of an imaging optical system will turn to the left-right direction, and it will become a thin imaging device.

  The lens barrel includes a movable lens group of the imaging optical system and a shutter, and an antireflection coating is provided on a portion of the inner surface of the lens barrel that is below the optical axis of the imaging optical system during normal shooting. Alternatively, a configuration in which an antireflection member is provided is preferable. In normal shooting, light from a light source such as the sun or an electric light outside the shooting target range hits the antireflection coating or the antireflection member on the inner surface of the lens barrel, and is reflected and does not go to the drive unit.

  The above-described imaging device in which the optical axis of the imaging optical system is bent is provided at a position above the optical axis of the imaging optical system in normal shooting, and includes an optical viewfinder including a lens group movable in the front-rear direction. A movable member that moves integrally with the movable lens group of the imaging optical system, and a pinion gear that rotates by engaging with the rack gear of the movable member and moves the movable lens group of the optical finder. By changing the focal length of the imaging optical system by moving the movable lens group of the imaging optical system, and by moving the movable lens group of the optical finder linked to the movable lens group of the imaging optical system via the movable member, The size of the image provided by the optical finder may be changed according to the focal length of the imaging optical system.

  In order to change the size of the image provided by the optical viewfinder according to the focal length of the imaging optical system, the movable lens group of the optical viewfinder is perpendicular to the moving direction of the movable lens group of the imaging optical system. Will be moved in any direction. In this imaging apparatus, the movable lens group of the optical finder is interlocked with the movable lens group of the imaging optical system, and conversion of the moving direction necessary for this is realized by a simple mechanism called a rack gear and a pinion gear. Since the movable member is provided above the optical axis of the imaging optical system, flare does not occur due to light reflection on the movable member even if the movable member is not provided with an antireflection coating.

  Here, a movable lens group of the imaging optical system and a lens barrel that houses the movable member may be provided, and the lens barrel may have a window that allows the movable member at a predetermined position within the moving range to be visually recognized. . In order to make the image size provided by the optical viewfinder correspond to the focal length of the imaging optical system, it is necessary to make the position of the movable lens group of the optical viewfinder correspond to the position of the rack gear with which the pinion gear is engaged. However, at the time of assembly, if the movable member provided with the rack gear is not accommodated in the lens barrel and cannot be seen, it is difficult to realize it. By providing a window in the lens barrel so that the movable member at a predetermined position can be seen, it is easy to make the position of the movable lens group of the imaging optical system correspond to the portion of the rack gear with which the pinion gear is engaged. become.

  The image pickup apparatus of the present invention is held so that the optical axis of the image pickup optical system is substantially horizontal during normal shooting, but the drive unit is positioned above the optical axis of the image pickup optical system, so Light from bright light sources such as the sun and electric lights outside the target range will not be reflected directly on the drive unit, and flare will be prevented even if the anti-reflection coating is not applied to the surface of the drive unit. Can do. Therefore, the imaging apparatus can provide a high-quality image at a low cost.

  In the configuration in which the optical axis of the imaging optical system is bent, most of the optical axis can be directed in the left-right direction, and a thin imaging device can be easily obtained. In particular, it is provided with an optical viewfinder including a lens group movable in the front-rear direction, provided at a position above the optical axis of the imaging optical system for normal shooting, and a movable lens of the optical viewfinder with a rack gear and a pinion gear. The structure in which the group is linked to the movable lens group of the imaging optical system and the size of the image provided by the optical viewfinder is changed according to the focal length of the imaging optical system is simple and easy to downsize. However, usability can be improved. In addition, since the movable member provided with the rack gear is positioned above the optical axis of the imaging optical system, flare due to reflection on the surface of the movable member can be prevented without applying an antireflection coating to the movable member. Can do.

  Hereinafter, a digital camera according to an embodiment of the present invention will be described with reference to the drawings. The configuration of the digital camera 1 of the present embodiment is schematically shown in FIGS. FIG. 1 is a front view showing the housing of the digital camera 1 in perspective, and FIG. 2 is a front view showing the inside and the periphery of the lens barrel.

  The digital camera 1 has a substantially rectangular parallelepiped housing 10 whose shortest side is about a fraction of the other side. During normal shooting, the direction of the shortest side of the housing 10 ( 1 is the front-rear direction, the longest side direction (left-right direction in FIG. 1) is left-right direction, and the side direction between them (up-down direction in FIG. 1) is up-down direction. It is set to be gripped by the user in a state of facing. Hereinafter, the front and rear, left and right, and top and bottom directions are determined based on this state. Note that the range captured by the digital camera 1 is a rectangle, and normal shooting means that an erect user shoots a long rectangular range on the side of the front and horizontally.

  A shutter release button 11 is provided on the upper surface of the housing 10, and the user holds the digital camera 1 with the right hand so that the shutter release button 11 faces upward during normal shooting, and the index finger of the right hand is used. The shutter release button 11 is operated.

  The digital camera 1 includes an imaging optical system composed of a first lens group 21, a second lens group 22, and a third lens group 23, and an imaging element 24 composed of a CCD area sensor. The first lens group 21 includes a prism and two lenses. The prism is a triangular prism having a right-angled isosceles triangle, and the two lenses are arranged so as to face the mutually orthogonal surfaces of the prism. The optical axes of the two lenses intersect on the slope of the prism, both of which form a 45 ° angle with the slope of the prism and are orthogonal to each other. The first lens group 21 is arranged on the prism holder 13 so that the plane including the optical axes of the two lenses is horizontal, the optical axis of one lens faces the front-rear direction, and the optical axis of the other lens faces the left-right direction. It is fixed. A lens whose optical axis faces the front-rear direction is located in front of the prism, and a lens whose optical axis faces the front-rear direction is located on the side of the prism.

  The second lens group 22 and the third lens group 23 are each composed of a plurality of lenses, and their optical axes coincide with the optical axes of the lenses of the first lens group 21 facing in the left-right direction. Therefore, the optical axis of the entire image pickup optical system is bent 90 ° by the prism in the middle, and most of the optical axis is set to face in the left-right direction. A reflective coat is provided on the slope of the prism of the first lens group 21.

  Both the second lens group 22 and the third lens group 23 are movable in the optical axis direction. The movement of the second lens group 22 performs zooming, that is, the change of the focal length, and the movement of the third lens group 23 performs focusing, that is, the adjustment of the focus on the object to be imaged. The second lens group 22 and the third lens group 23 are accommodated in the lens barrel 12. The lens barrel 12 is fixed to the housing 10, and the prism holder 13 that holds the first lens group 21 is fixed to the lens barrel 12. The lens barrel 12 has a lid 15 and is closed by the lid 15 after the lens groups 22 and 23 are accommodated.

  The image sensor 24 is disposed so as to be orthogonal to the optical axis of the third lens group 23 and to pass through the optical axis of the third lens group 23 at the center. The imaging element 24 is fixed to the heat sink 14, and the heat sink 14 is fixed to the lens barrel 12.

  The digital camera 1 includes guide shafts 31 and 32 that support the second lens group 22 and the third lens group 23 and guide their movement in the optical axis direction. A motor 33 for moving the group 22 and a motor 34 for moving the third lens group 23 are provided. The guide shafts 31 and 32 have a cylindrical shape with a smooth outer peripheral surface, and are parallel to the optical axis of the second lens group 22 and the optical axis of the third lens group 23. The ends of the guide shafts 31 and 32 are fixed to the lens barrel 12, and the guide shaft 32 is located on the opposite side of the guide shaft 31 with respect to the second lens group 22 and the third lens group 23.

  The guide frame 31 is passed through the lens frame that holds the second lens group 22, and the guide shaft 32 is sandwiched between the tilt prevention unit that prevents the second lens group 22 from tilting with respect to the guide shaft 31, and the guide shaft 32. An anti-rotation unit that prevents the rotation of the second lens group 22 around the shaft 31 is provided. The lens frame that holds the third lens group 23 is also provided with a similar tilt prevention unit and rotation prevention unit.

  The motor 33 that moves the second lens group 22 and the motor 34 that moves the third lens group 23 are arranged above the imaging optical system. A cylindrical drive shaft 35 having a helical screw formed on the outer peripheral surface is coupled to the rotary shaft of the motor 33, and a helical screw is also formed on the outer peripheral surface of the rotary shaft of the motor 34. A cylindrical drive shaft 36 is coupled. These drive shafts 35 and 36 are parallel to the guide shafts 31 and 32 and are located on the same straight line. The lens frame that holds the second lens group 22 is provided with an engaging portion formed with a screw that engages with the screw of the drive shaft 35, and the lens frame that holds the third lens group 23 also has In addition, an engaging portion in which a screw that engages with the screw of the drive shaft 36 is formed is provided.

  The drive shaft 35 rotates with the rotation of the rotation shaft of the motor 33, the rotation is transmitted to the engaging portion via the screw, and the second lens group 22 moves along the guide shafts 31 and 32. Similarly, the drive shaft 36 rotates with the rotation of the rotation shaft of the motor 34, the rotation is transmitted to the engaging portion via the screw, and the third lens group 23 moves along the guide shafts 31 and 32. .

  The digital camera 1 includes a shutter unit 25 that blocks light from an object to be imaged and controls exposure of the image sensor 24. The shutter unit 25 includes a plurality of movable sectors 25a, each having a circular opening, and includes a substrate 25b and a pressing plate 25c sandwiching the sector 25a therebetween, and the sector 25a rotates in a direction parallel to the substrate 25b. The openings of the substrate 25b and the pressing plate 25c are opened and closed. The substrate 25b and the pressing plate 25c are perpendicular to the optical axis of the second lens group 22, and the optical axis passes through the centers of their openings.

  The imaging optical system has a configuration in which the position where the shutter unit 25 should be set changes by zooming, and the ideal position of the shutter unit 25 changes according to the focal length. Therefore, in the digital camera 1, the shutter unit 25 is movable in the optical axis direction of the imaging optical system so that the shutter unit 25 is always located at or near the ideal position. However, in order to achieve a simple configuration, the shutter unit 25 is moved integrally with the second lens group 22 within a predetermined focal length range, and remains at a fixed position outside the focal length range. .

  The shutter unit 25 has a support base 27 on which a guide shaft 26 is implanted, in addition to the sector 25a, the substrate 25b, and the pressing plate 25c. The guide 26 axis is parallel to the optical axis of the second lens group 22.

  The lens frame that holds the second lens group 22 is provided with a tilt prevention portion 28 that penetrates the guide shaft 26 and prevents the shutter unit 25 from tilting. In addition, the substrate 25b is provided with a rotation preventing portion that prevents the shutter unit 25 from rotating about the guide shaft 26 with the guide shaft 32 interposed therebetween.

  Between the lens frame of the second lens group 22 and the support base 27, a tension spring (expanded coil spring) 29 is laid in parallel to the guide shaft 26. The lens group 22 and the shutter unit 25 always have a biasing force in a direction approaching each other. If no other force is applied from the outside, the second lens group 22 and the shutter unit 25 stand still in a state in which the end surface of the tilt prevention portion 28 and the end surface of the support base 27 are in contact with each other.

  A stopper (not shown) that defines one end of the moving range of the shutter unit 25 is fixed to the lens barrel 12, and the shutter unit 25 is positioned closer to the first lens group 21 than the stopper. When the shutter unit 25 approaches the stopper, the end of the substrate 25b comes into contact with the stopper, and the shutter unit 25 cannot move further to the image sensor 24 side. On the other hand, the lens frame of the second lens group 22 does not come into contact with the stopper, and the second lens group 22 moves to the first lens 21 side from the stopper and to the image sensor 24 side from the stopper. can do.

  In the digital camera 1, while changing from the shortest focal length to the longest focal length, the second lens group 22 is set to move from the image sensor 24 side to the first lens group 21 side rather than the stopper. It is said. When the second lens group 22 is positioned closer to the image sensor 24 than the stopper, the shutter unit 25 stops in contact with the stopper, and the second lens group 22 is closer to the first lens group 21 than the stopper. When the second lens group 22 is located, the second lens group 22 moves.

  The main purpose of the shutter unit 25 is to control the exposure time of the image sensor 24, but the shutter unit 25 largely inclines from outside the imaging target range and blocks light entering the lens barrel 12, thereby causing flare. It also has a function to prevent the occurrence. An antireflection coating is applied to the surface of the pressing plate 25c of the shutter unit 25 on the first lens group 21 side, so that light is not reflected by the shutter unit 25. The entire inner surface of the lens barrel 12 is also provided with an antireflection coating, and no light is reflected from the inner surface of the lens barrel 12.

  In order to allow the shutter unit 25 to move smoothly, the edge of the shutter unit 25 does not contact the inner surface of the lens barrel 12, and there is a gap between them. However, since the motor 33 and the drive shaft 35 for moving the second lens group 22 and the shutter unit 25 are located above the optical axis of the imaging optical system, they are located above the photographing target range in normal photographing. Even if light from a bright light source such as the sun or an electric light enters the lens barrel 12, it does not strike the motor 33 or the drive shaft 35. Therefore, the light is reflected on the surface of the motor 33 or the drive shaft 35, and the shutter. It does not proceed to the image sensor 24 side through the gap between the unit 25 and the lens barrel 12. This prevents flare from occurring.

  The digital camera 1 includes an optical viewfinder 50, and the viewfinder 50 is attached to the lens barrel 12. The configuration of the finder 50 is shown in FIGS. 3 is a front perspective view, and FIG. 4 is a top perspective view. The optical system of the finder 50 includes three lenses 51, 52, 53, two prisms 54, 55, and an eyepiece lens 56. Light from the object to be photographed passes through the first lens 51, the second lens 52, the third lens 53, the prism 54, the prism 55, and the eyepiece lens 36 in this order, and reaches the user's eyes.

  The optical axes of the first, second, and third lenses 51, 52, and 53 are coincident with each other, and the optical axis of the eyepiece lens 56 is parallel thereto. These optical axes are directed in the front-rear direction and are perpendicular to the optical axis of the imaging optical system. The prism 54 reflects light twice and the prism 55 reflects three times. The optical axis of the optical system of the finder 50 is bent five times by the prisms 54 and 55, thereby suppressing an increase in size of the finder 50. The first, second, and third lenses 51, 52, and 53 cause light from the subject to be imaged between the prism 54 and the prism 55. The user observes the real image through the eyepiece lens 56 and the prism 55.

  The second lens 52 and the third lens 53 are movable in the optical axis direction. Depending on the positions of these lenses 52 and 53, the magnification of the aerial image formed between the prisms 54 and 55 changes. In the digital camera 1, the second and third lenses 52 and 53 of the finder 50 are arranged so that the optical image provided by the finder 50 matches the photographing target range regardless of the focal length of the imaging optical system. The second lens group 22 of the imaging optical system is moved in conjunction with the movement.

  As shown in FIGS. 1 and 2, a driving plate 41 for moving the lenses 52 and 53 of the finder 50 is fixed to the lens frame of the second lens group 22. The drive plate 41 is long in the optical axis direction of the second lens group 22, and a rack gear 41a is formed on the upper edge. The lens barrel 12 is provided with a pinion gear 42 that rotates by engaging with the rack gear 41 a of the drive plate 41. The rotation axis of the pinion gear 42 is parallel to the optical axes of the lenses 51, 53 and 53 of the finder 50. As shown in FIG. 3, the pinion gear 42 is formed by integrally forming a gear 42a having a large pitch circle and a gear 42b having a small pitch circle, and the gear 42a having a large pitch circle is engaged with the rack gear 41a.

  The finder 50 is provided with a gear 61 that engages with a gear 42 b having a small pitch circle, and a cam member 62 is coupled to the rotation shaft of the gear 61. The cam member 62 rotates integrally with the gear 61. The cam member 62 is provided with two cams 62a and 62b whose inclinations to the rotation axis are opposite. The cam member 62 is urged forward by a compression spring 63 provided at the rear end thereof, so that the position in the front-rear direction is kept constant.

  The lens frame that holds the second lens 52 is provided with a cam follower 52 a that abuts the cam 62 a, and the lens frame is urged rearward by a tension spring 58. The lens frame of the second lens 52 is always in contact with the cam 62 a by the urging force of the tension spring 58 and moves back and forth with the rotation of the cam member 62. The lens frame that holds the third lens 53 is provided with a cam follower 53 a that contacts the cam 62 b, and the lens frame is urged forward by a tension spring 59. The lens frame of the third lens 53 is always in contact with the cam 62 b by the urging force of the tension spring 59 and moves back and forth with the rotation of the cam member 62.

  Since the inclination directions of the cams 62a and 62b are opposite, when the second lens 52 moves backward, the third lens 53 moves forward, and when the second lens 52 moves forward, The third lens 53 moves backward. FIG. 4 shows the lenses 52 and 53 when the magnification of the provided optical image is the minimum, which corresponds to a state where the focal length of the imaging optical system is the shortest. As the focal length of the imaging optical system increases, the lenses 52 and 53 approach each other. 3 and 4, reference numeral 57 denotes a tension spring for keeping the position of the fixed first lens 51 constant.

  When the second lens group 22 of the imaging optical system moves, the drive plate 41 also moves together, and the pinion gear 42 engaged with the rack gear 41a of the drive plate 41 rotates. As the pinion gear 42 rotates, the gear 61 of the finder 50 rotates, the cam member 62 also rotates, and the second and third lenses 52 and 53 move. The moving direction of the second lens group 22 of the imaging optical system and the moving direction of the lenses 52 and 53 of the finder 50 are perpendicular to each other, but the second lens group 22 is configured by the above-described configuration including the rack gear 41a and the pinion gear 42. Can be converted to be suitable for the moving direction of the lenses 52 and 53 of the finder 50 and transmitted.

  The drive plate 41 is accommodated in the lens barrel 12 together with the large gear 42 a of the pinion gear 42. The gear 42 a is positioned closer to the image sensor 24 than the shutter unit 25, but the drive plate 41 is entirely positioned closer to the image sensor 24 than the shutter unit 25 as the second lens group 22 moves. In some cases, a part thereof may be located closer to the first lens group 21 than the shutter unit 25.

  However, since the drive plate 41 is located above the optical axis of the imaging optical system, even if the drive plate 41 is located closer to the first lens group 21 than the shutter unit 25, the light from the light source outside the imaging target range is driven by the drive plate 41. No 41 is hit. Therefore, it is possible to prevent the occurrence of flare due to the reflection of light on the drive plate 41 without providing the drive plate 41 with an antireflection coating.

  In order for the optical image provided by the finder 50 to coincide with the photographing target range, the positions of the lenses 52 and 53 of the finder 50 and the portion of the rack gear 41a where the pinion gear 42 (gear 42a) is engaged are determined. Appropriate responses must be made and this must be done when attaching the finder 50 to the lens barrel 12. However, the drive plate 41 and the gear 42a forming the rack gear 41a are accommodated in the lens barrel 12, and the finder 50 is attached with the lid 15 of the lens barrel 12 closed, so the drive plate 41 and the gear 42a are not visible. It becomes difficult to properly associate the positions of the lenses 52 and 53 of the finder 50 with the engagement portions of the gear 42a and the rack gear 41a.

  In the digital camera 1, in order to eliminate this inconvenience, as shown in FIG. 1, windows 15a and 15b are provided on the lid 15 of the lens barrel 12, and the second lens group 22 is the longest focus of the imaging optical system. When in a position corresponding to the distance, the rack gear 41a appears from the window 15a, and the end of the drive plate 41 appears from the window 15b. The direction of the cam member 62 is set so that the lenses 52 and 53 of the finder 50 are positioned corresponding to the longest focal length of the imaging optical system, and a predetermined plurality of teeth of the rack gear 41a can be seen from the window 15a. Alternatively, the position of the lenses 52 and 53 of the finder 50 can be obtained by attaching the finder 50 to the lens barrel 12 (with the gear 61 engaged with the gear 42b) with the end of the drive plate 41 visible from the window 15b. The portion of the rack gear 41a with which the pinion gear 42 engages is appropriately determined. After the finder 50 is attached, a light shielding film is attached and the windows 15a and 15b are closed.

  In the present embodiment, the motors 33 and 34 and the drive shafts 35 and 36 are disposed above the entire imaging optical system. However, the motors 33 and 34 and the drive shafts 35 and 36 are located on the optical axis of the imaging optical system. May be provided above. Here, the entire inner surface of the lens barrel 12 is provided with a reflective coating. However, the reflective coat has an end portion on the first lens group 21 side of the inner surface of the lens barrel 12 in the left-right direction. To the portion corresponding to the end of the moving range of the shutter unit 25 on the image sensor 24 side. In the vertical direction, it is sufficient for normal shooting to have a reflective coat on the entire area below the optical axis of the imaging optical system. However, shooting is performed with most of the optical axis of the imaging optical system facing the vertical direction. Therefore, it is preferable to provide a reflective coat from the upper end to the entire lower end. Instead of the antireflection coating, an antireflection member, for example, light-absorbing flocked paper, can be provided on the inner surface of the lens barrel 12.

  Since the guide shaft 32 for preventing the rotation of the second lens group 22, the third lens group 23, and the shutter unit 25 is located below the optical axis of the imaging optical system, it also prevents reflection on its surface. It is desirable to provide a coat. A guide groove is provided in the lens barrel 12 in place of the guide shaft 32, and a projection in contact with the inner surface of the guide groove is provided on the lens frame of the lens groups 22 and 23 and the substrate 25b of the shutter unit 25, so that the lens groups 22 and 23 and It is also possible to prevent the shutter unit 25 from rotating. Even in this configuration, it is desirable to provide an antireflection coating in the guide groove. Since the lens frame or the like is only slidably contacted with the guide shaft 32 or the guide groove, a large force is not applied unlike the drive shafts 35 and 36. Therefore, the antireflection coating provided on the surface is not easily worn and used for a long time. However, displacement of the optical axis can be prevented.

1 is a front perspective view schematically showing a lens barrel and a peripheral portion of a digital camera according to an embodiment of the present invention. FIG. 2 is a front view schematically showing the inside and the periphery of a lens barrel of the digital camera. The front perspective view which shows the finder of the said digital camera, and its peripheral part. FIG. 4 is a top perspective view of the finder of the digital camera. The figure which shows typically the structure of the digital camera which has arrange | positioned the drive part below the optical axis of an imaging optical system, and the principle which a flare generate | occur | produces with the structure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Digital camera 10 Housing | casing 11 Shutter release button 12 Lens barrel 13 Prism holder 14 Heat sink 15 Lens barrel cover 15a, 15b Window 21 1st lens group 22 2nd lens group 23 3rd lens group 24 Image sensor 25 Shutter unit 25a Shutter sector 25b Substrate 25c Holding plate 26 Guide shaft 27 Support base 28 Tilt prevention part 29 Tension spring 31, 32 Guide shaft 33, 34 Motor 35, 36 Drive shaft 41 Drive plate 41a Rack gear 42 Pinion gear 42a, 42b Gear 50 Optical viewfinder 51, 52, 53 Lens 52a, 53a Cam follower 54, 55 Prism 56 Eyepiece lens 57, 58, 59 Tension spring 61 Gear 62 Cam member 62a, 62b Cam 63 Compression spring

Claims (5)

An image pickup device, an image pickup optical system that has a plurality of lens groups including a lens group movable in the optical axis direction, guides light to the image pickup device, and a guide shaft that movably supports the moveable lens group of the image pickup optical system. And a shutter that moves forward and backward in the optical path of the light guided to the image sensor and is movable in the optical axis direction of the imaging optical system, and is held by the user so that the optical axis of the imaging optical system is substantially horizontal during normal shooting In the imaging device,
An image pickup apparatus having a movable lens group of an image pickup optical system and a drive unit for moving a shutter, and the drive unit is provided at a position above the optical axis of the image pickup optical system in normal shooting. .   The imaging apparatus according to claim 1, wherein the imaging optical system includes a reflective element that reflects light, and an optical axis of the imaging optical system is bent by the reflective element.   A lens barrel that houses a movable lens group and a shutter of the imaging optical system is provided, and an antireflection coating or a reflection is applied to a portion of the inner surface of the lens barrel that is below the optical axis of the imaging optical system during normal shooting. The imaging apparatus according to claim 1, wherein a prevention member is provided. An optical viewfinder including a lens group that is provided at a position above the optical axis of the imaging optical system in normal shooting and movable in the front-rear direction;
A movable member that is provided with a rack gear and moves integrally with a movable lens group of the imaging optical system;
A pinion gear that rotates by engaging the rack gear of the movable member and moves the movable lens group of the optical finder,
The focal length of the imaging optical system is changed by moving the movable lens group of the imaging optical system, and the optical lens is moved by moving the movable lens group of the optical finder linked to the movable lens group of the imaging optical system via a movable member. The image pickup apparatus according to claim 2, wherein the size of the image provided by the type finder is changed according to the focal length of the image pickup optical system.   The movable lens group of the imaging optical system and a lens barrel that accommodates the movable member are provided, and the lens barrel has a window that allows the movable member at a predetermined position within the moving range to be visually recognized. 5. The imaging device according to 4.

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