JP2011133621A - Lens barrel and imaging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive lens barrel that changes an aperture diameter during variable magnification with a simple mechanism, and an inexpensive imaging device including the lens barrel. <P>SOLUTION: The lens barrel includes: an imaging optical system composed of a plurality of lens groups to perform variable magnification by moving a predetermined lens group; a diaphragm mechanism that is arranged in the imaging optical system, and has a diaphragm blade for changing the aperture diameter; and a cam member having one end supported so as to be oscillated, and the other end engaged with a part of the diaphragm mechanism. A moving mirror frame for holding a lens group moving during the variable magnification is brought into contact with a cam surface of the cam member, and the cam member is oscillated by the movement of the moving mirror frame to change the aperture diameter. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a lens barrel having a diaphragm mechanism configured to change an aperture diameter at the time of zooming, and an imaging apparatus including the lens barrel.

  2. Description of the Related Art Conventionally, zoom lenses that change the aperture diameter at the time of opening are known in order to keep the open F value constant at the time of zooming or to secure the optical performance of the periphery of the photographing screen.

  As such, by rotating one of the two blade holding members that hold the plurality of diaphragm blades in which the pins are implanted, the aperture value is changed, and the other blade holding member is made to correspond to zooming. It is known that the aperture diameter at the time of opening is changed by rotating to keep the opening F value constant (see, for example, Patent Document 1).

JP 2001-290190 A

  In recent years, imaging devices that shoot moving images do not have an aperture mechanism for adjusting the amount of exposure in the imaging optical system, and can only adjust the amount of exposure under high brightness by adjusting the charge accumulation time of the image sensor. There is something to do. In this case, since the image is always taken with the aperture stop opened, it is necessary to ensure the performance when the imaging optical system is opened for all the zooming areas, leading to an increase in size and cost of the optical system.

  Therefore, it is conceivable to secure the performance by changing the aperture diameter to cut the optical flux at the periphery of the photographing screen at the time of zooming, and by cutting the light flux that deteriorates the performance. However, using the mechanism as described in Patent Document 1 to change the opening diameter at the time of opening at the time of zooming has a problem that the number of parts is large and the cost is high.

  In view of the above problems, the present invention provides a low-cost lens barrel that can change the aperture diameter at the time of zooming with a simple mechanism and a low-cost imaging device including the lens barrel. It is the purpose.

  The above object is achieved by the following configuration.

1. An imaging optical system that includes a plurality of lens groups and performs zooming by moving a predetermined lens group;
A diaphragm mechanism that is arranged in the imaging optical system and has diaphragm blades that change the aperture diameter;
A cam member that is pivotally supported at one end portion and is swingable, and the other end portion is engaged with a part of the aperture mechanism,
A movable lens frame that holds a lens group that moves during zooming is brought into contact with the cam surface of the cam member,
A lens barrel characterized in that the opening diameter is changed by swinging the cam member by movement of the movable lens frame.

  2. 2. The lens barrel according to 1, wherein one end portion of the cam member is engaged with the diaphragm blade.

  3. 3. The lens barrel according to 1 or 2, further comprising an urging member that urges the cam member in a direction in contact with the movable lens frame.

  4). At least a part of the cam member includes an actuator that moves the movable lens frame as viewed from the optical axis direction, a guide shaft that guides the movable lens frame closer to the actuator, and an optical axis of the imaging optical system. 4. The lens barrel according to any one of 1 to 3, wherein the lens barrel is disposed at a position overlapping with a connecting triangle.

  5. 5. An imaging apparatus comprising: the lens barrel according to any one of 1 to 4; and an imaging element that photoelectrically converts a subject image formed by the imaging optical system.

  According to the present invention, it is possible to provide a low-cost lens barrel capable of changing the aperture diameter at the time of zooming with a simple mechanism and a low-cost imaging device including the lens barrel. Become.

It is an external view of an imaging device provided with the lens barrel according to the present embodiment. It is sectional drawing which shows the outline of the imaging optical system which can be changed in magnification, and the lens barrel holding this imaging optical system. It is the perspective view which extracted the cam member at the time of a wide end, the 2nd lens group frame, the aperture mechanism, the 3rd lens group frame, etc. It is a figure which shows rocking | fluctuation of the cam member by the movement of a 2nd lens group lens frame. It is a front view which shows an aperture mechanism. It is a perspective view which shows the modification of an aperture mechanism. It is the figure which looked at the cam member and the 2nd lens group lens frame from the optical axis direction.

  Hereinafter, the present invention will be described in detail with reference to embodiments, but the present invention is not limited thereto.

  FIG. 1 is an external view of an imaging apparatus including a lens barrel according to the present embodiment. FIG. 1A is a perspective view of the imaging apparatus as viewed from the front and obliquely upward, and FIG. 1B is a perspective view of the imaging apparatus in use as viewed from the obliquely rear side. The figure is an example of an imaging device capable of recording still images, moving images, and audio, but may be an imaging device capable of only taking still images.

  The imaging apparatus 100 includes a variable magnification imaging optical system 10 exposed by the first lens group 11, a flash (for still image shooting) 81, a shooting button 91, and a zoom button 94. In addition, an open / close case 82 configured to switch the main power switch ON and OFF by opening / closing, and a liquid crystal monitor 83 is disposed in the open / close case 82. The open / close case 82 turns on the main power switch in the open state shown in FIG. 1B, and switches the main power switch to OFF by closing the main power switch in the main body shown in FIG.

  The shooting button 91 is input with instructions for starting and stopping moving image recording during moving image shooting, and is a release button during still image shooting. The zoom button 94 is for changing the magnification of the imaging optical system 10 and changing the image to a desired angle of view. In addition, it has a jog dial 92 for displaying the operation mode and various photographing conditions on the liquid crystal monitor 83, and a decision button 93 for selecting and confirming from the display. Although not shown, a hard disk device, a memory card, or the like is used as a recording medium, and has an interface, a connector, and the like for transferring data recorded on the recording medium to an external device.

  FIG. 2 is a cross-sectional view schematically showing an imaging optical system capable of zooming and a lens barrel 50 that holds the imaging optical system. FIG. 2A shows a state at the wide end (wide angle end), and FIG. 2B shows a state at the tele end (telephoto end).

  The imaging optical system shown in the figure includes a first lens group 11 fixed to the main body 21, a second lens group 12 made movable, a third lens group 13 fixed, and a fourth lens made movable. Group 14. Reference numeral 15 denotes a parallel plate optical filter in which an infrared light cut filter and an optical low-pass filter are stacked. Reference numeral 16 denotes an image sensor.

  The second lens group 12 is held by the second lens group lens frame 12k, guided by two guide shafts 25 and 26 arranged in the optical axis O direction, and movable in the optical axis direction. The third lens group 13 is held by a third lens group lens frame 13 k and fixed to the main body 21. The fourth lens group 14 is held by a fourth lens group lens frame 14k, guided by two guide shafts 25 and 26 disposed in the optical axis O direction, and movable in the optical axis direction.

  Although not shown, the second lens group lens frame 12k is moved in the direction of the optical axis O by a stepping motor. More specifically, a lead screw which is a male screw rotated by a stepping motor and a female screw portion integrally formed with the second lens group lens frame 12k are screwed together, and the lead screw is rotated. Thus, the second lens group lens frame 12k is moved in the direction of the optical axis O. The same applies to the fourth lens group frame 14k.

  In this example, the second lens group frame 12k that holds the second lens group 12 moves in the direction of the optical axis O, performs zooming, and the fourth lens group frame that holds the fourth lens group 14. 14k moves in the direction of the optical axis O to perform focus adjustment (focusing).

  32a and 32b are aperture blades, and 41 is a cam member. The aperture blades 32a and 32b are assembled to a ground plate (not shown) and fixed to the third lens group lens frame 13k as an aperture mechanism. The diaphragm blades 32a and 32b are slidable on the main plate in a direction substantially perpendicular to the optical axis O.

  As shown in FIG. 2 (b), the cam member 41 is supported on the main body by a swinging shaft portion 41j formed at one end, and swings in the direction of the front and back of the drawing with the swinging shaft portion 41j as an axis. It is possible. Further, a projection 41t is formed at the other end, and is engaged with the diaphragm blades 32a and 32b. Further, the cam member 41 is biased by a biasing member (not shown) in a direction in which the cam surface 41c abuts on the second lens group lens frame 12k.

  FIG. 3 is a perspective view of the cam member, the second lens group lens frame, the aperture mechanism, the third lens group lens frame and the like at the wide end.

  The swinging shaft portion 41j formed at the end of the cam member 41 is supported by a fitting shaft on a main cylinder (not shown) or a member integrally fixed to the main shell, and an arrow shown in the drawing with the swinging shaft portion 41j as an axis. It can swing in the direction. Further, the protrusion 41 t formed at the end of the cam member 41 is through-engaged with the long holes 32 m and 32 n formed in the diaphragm blades 32 a and 32 b assembled to the base plate 31 of the diaphragm mechanism 30.

  Further, a spring 42 that is a biasing member that biases the cam surface 41c in a direction in which the cam surface 41c abuts on the second lens group lens frame 12k that is a movable lens frame is hung on the cam member 41. Accordingly, the contact portion 12t formed on the second lens group frame 12k is always brought into contact with the cam surface 41c of the cam member 41, and the cam member 41 is swung by the movement of the second lens group frame 12k. Can be made.

  FIG. 4 is a view showing the swing of the cam member due to the movement of the second lens group lens frame 12k. FIG. 4 is a top view of the cam member, the second lens group lens frame, the aperture mechanism, the third lens group lens frame, etc., extracted from FIG. 3, and FIG. 4 (a) shows the state at the wide end. FIG. 4B shows a state at the tele end.

  As shown in FIG. 4A, in the wide end state where the second lens group frame 12k and the third lens group frame 13k are farthest apart, the contact portion 12t of the second lens group frame 12k is It abuts on the cam surface 41c at a position close to the swinging shaft portion 41j. At the time of zooming from the wide end state to the longer focal point side, the second lens group frame 12k is moved in the direction close to the third lens group frame 13k, and at the tele end, FIG. It will be in the state shown in At the tele end, the contact portion 12t of the second lens group lens frame 12k comes into contact with the cam surface 41c at a position separated from the swing shaft portion 41j. That is, the cam member 41 is swung by the contact portion 12t of the second lens group lens frame 12k moving while being in contact with the cam surface 41c.

  As a result, the protrusion 41t formed on the cam member 41 swings, and the diaphragm blades 32a and 32b having the long holes 32m and 32n through which the protrusion 41t is engaged are operated.

  FIG. 5 is a front view showing the aperture mechanism. 5A and 5B are views of the diaphragm mechanism as viewed from the optical axis direction. FIG. 5A shows a state at the wide end, FIG. 5B shows a state at the middle, and FIG. The state at the tele end is shown.

  As shown in FIG. 5, the diaphragm mechanism 30 is configured such that diaphragm blades 32 a and 32 b are slidably assembled to the base plate 31. Guide pins 31a, 31b, 31c are formed in the base plate 31, and long hole-shaped guide holes formed in the diaphragm blades 32a, 32b are inserted and assembled into the guide pins 31a, 31b, 31c. . The diaphragm blades 32a and 32b are movable in the longitudinal direction of the guide hole.

  The aperture blade 32a is formed with a long hole 32m inclined in a direction different from the longitudinal direction of the guide hole. Similarly, a long hole 32n inclined in a direction different from the longitudinal direction of the guide hole is formed in the diaphragm blade 32b. Further, the long hole 32m and the long hole 32n are formed to be inclined in the intersecting direction. A protrusion 41t (see FIGS. 2 to 4) formed on the cam member 41 is through-engaged with the long hole 32m and the long hole 32n.

  At the wide end shown in FIG. 5A, the position of the protrusion 41t formed on the cam member 41 is in the state shown in FIG. 4A, and the opening K formed by the aperture blades 32a and 32b is As shown in the figure, it is set to a substantially circular shape.

  5C, the protrusion 41t of the cam member 41 is moved from the position shown in FIG. 4A to the position shown in FIG. 4B (the right direction in FIG. 5). The opening K formed by the diaphragm blades 32a and 32b by being swung is set to a throttled state as illustrated.

  In the middle state shown in FIG. 5B, the position of the protrusion 41t formed on the cam member 41 is intermediate between the position at the wide end and the position at the tele end, and is formed by the diaphragm blades 32a and 32b. The opening K is also set to a diameter between the wide end and the tele end.

  As described above, the movable lens frame (in this example, the second lens group lens frame 12k) that has the cam member 41 engaged with the aperture mechanism 30 and that holds the lens group that moves when zooming is provided. Is made in contact with the cam surface 41c of the cam member 41, and the cam member 41 is swung by the movement of the movable lens frame to change the opening diameter. It is possible to obtain a lens barrel that can be changed with

  In addition, as shown in FIG. 5, the protrusion 41t formed on the cam member 41 is directly engaged with the two diaphragm blades, so that the number of parts of the diaphragm mechanism can be reduced and the cost can be reduced. Can be

  FIG. 6 is a perspective view showing a modification of the aperture mechanism. FIG. 6A shows a state at the wide end, and FIG. 6B shows a state at the tele end.

  The diaphragm mechanism 30 shown in FIG. 6 has an engaging member 35 that engages with the diaphragm blades 32a and 32b. The engaging member 35 can swing around a shaft portion 35j formed on the engaging member 35, and the diaphragm blades 32a and 32b are slid by the swinging of the engaging member 35. Further, the engaging member 35 is biased in a direction in which the aperture blades 32a and 32b are opened by a spring 42 as a biasing member.

  The protrusion 41t formed on the cam member 41 is engaged with a long hole 35h formed on the engagement member 35.

  From the state where the opening at the wide end shown in FIG. 6 (a) is substantially circular, the cam member 41 is swung (in the direction of the arrow in the figure) at the tele end shown in FIG. 6 (b). The engaging member 35 is swung as shown. Thereby, the opening K formed by the diaphragm blades 32a and 32b is in a state of being throttled as illustrated.

  Even with such a configuration, a lens barrel capable of changing the aperture diameter at the time of zooming by a simple mechanism can be obtained.

  FIG. 7 is a view of the cam member 41 and the second lens group frame 12k as viewed from the optical axis O direction.

  As shown in FIG. 7, a stepping motor 61, which is an actuator for moving the second lens group frame 12k, is disposed. The cam member 41 is disposed so that at least a part thereof overlaps with a triangle (broken line in the figure) connecting the stepping motor 61 and the guide shaft 25 closer to the stepping motor 61 and the optical axis O of the imaging optical system.

  By arranging in this way, it is possible to suppress blurring in the direction perpendicular to the optical axis O when the second lens group frame 12k that contacts the cam surface 41c of the cam member 41 moves at the contact portion 12t. . The blur in the direction orthogonal to the optical axis O is an image blur at the time of zooming, and the image blur can be suppressed by the above arrangement.

  In the present embodiment, the opening K has been described as being narrowed from the wide end toward the long focal point. However, the present invention is not limited to this, and the shape of the cam surface 41c formed on the cam member 41 is not limited thereto. By appropriately setting, a desired aperture diameter can be obtained at each focal length. In addition, the shape of the opening K has been described as an opening shape that is substantially a diamond shape from a substantially circular shape, but is not limited thereto, and by appropriately setting the shape of the opening portion formed in each of the diaphragm blades 32a and 32b, Other shapes are possible. Further, the example in which the diaphragm blades 32a and 32b are incorporated in the base plate 31 and fixed to the third lens group lens frame 13k has been described. However, the base plate 31 is eliminated and the diaphragm blades 32a and 32b are incorporated into the third lens group lens frame 13k. It may be configured.

DESCRIPTION OF SYMBOLS 11 1st lens group 12 2nd lens group 12k 2nd lens group frame 12t Contact part 13 3rd lens group 13k 3rd lens group frame 14 4th lens group 14k 4th lens group frame 15 Optical filter 16 Imaging Element 21 Main barrel 25, 26 Guide shaft 30 Diaphragm mechanism 31 Base plate 32a, 32b Diaphragm blade 41 Cam member 41c Cam surface 41j Oscillating shaft portion 41t Protrusion portion 42 Spring 50 Lens barrel 100 Imaging device K Opening portion

Claims (5)

An imaging optical system that includes a plurality of lens groups and performs zooming by moving a predetermined lens group;
A diaphragm mechanism that is arranged in the imaging optical system and has diaphragm blades that change the aperture diameter;
A cam member that is pivotally supported at one end portion and is swingable, and the other end portion is engaged with a part of the aperture mechanism,
A movable lens frame that holds a lens group that moves during zooming is brought into contact with the cam surface of the cam member,
A lens barrel characterized in that the opening diameter is changed by swinging the cam member by movement of the movable lens frame.   The lens barrel according to claim 1, wherein one end portion of the cam member is engaged with the diaphragm blade.   The lens barrel according to claim 1, further comprising an urging member that urges the cam member in a direction in which the cam member abuts on the movable lens frame.   At least a part of the cam member includes an actuator that moves the movable lens frame as viewed from the optical axis direction, a guide shaft that guides the movable lens frame closer to the actuator, and an optical axis of the imaging optical system. The lens barrel according to any one of claims 1 to 3, wherein the lens barrel is disposed at a position overlapping with a connecting triangle.   An image pickup apparatus comprising: the lens barrel according to claim 1; and an image pickup device that photoelectrically converts a subject image formed by the image pickup optical system.

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