JP6268587B2 - Lens barrel and imaging device - Google Patents

Description

  The present invention relates to a lens barrel and an imaging apparatus, and more particularly to a lens barrel having impact resistance and an imaging apparatus using the same.

  A lens barrel used for a digital still camera or the like that is an imaging device generally includes a plurality of cylindrical members that respectively hold a plurality of lens groups, and the plurality of cylindrical members are connected to each other by cam coupling or the like. It has become a state. With such a configuration, each cylindrical member appropriately moves relative to the optical axis direction to realize a zoom operation (magnification operation) and the like.

  A digital still camera having such a lens barrel is often used when a user carries it in a pocket or bag and takes out the image when desired. Here, there is a possibility that a user who desires to take an image may accidentally drop the digital still camera on the floor or the like when taking out or taking an image. In a configuration in which the lens barrel protrudes from the body of the digital still camera, the lens barrel often falls downward in the direction of gravity acceleration due to the balance of the center of gravity. Then, the front end of the lens barrel collides with the floor surface or the like, so that an unintended impact force is directly applied to the lens barrel, and as a result, between the cam groove and the cam follower for driving the movable barrel member forward and backward. There is a risk that the impact force acts to break the cam coupling between the two, or the cam groove or cam follower may be damaged.

  Conventionally, a cylindrical member constituting a lens barrel is generally formed using a resin. Further, the cam groove in the lens barrel is often formed integrally on the surface of such a resin cylinder member. On the other hand, as a form of the cam follower in the conventional lens barrel, a form integrally formed with the tubular member (that is, a resin cam pin), a form in which a metal cam pin is implanted in the tubular member, etc. Various forms have been put into practical use. Here, it is known that a metal cam pin has higher impact resistance than a resin cam pin.

  Patent Document 1 discloses a lens barrel in which the same number of resin cam pins and metal cam pins are alternately arranged at equal intervals in the circumferential direction. As in Patent Document 1, by providing half the number of cam pins made of metal with respect to the total number of cam pins, a balance between impact resistance and cost and weight reduction is achieved.

Japanese Patent No. 5042908

  By the way, in the above-described prior art, there may be a case where sufficient impact resistance cannot be secured against a large impact force generated when the digital still camera is dropped from a high position. However, if all the cam pins are made of metal or metal cam pins having different diameters are used, the impact resistance is improved, but this is not preferable because it increases the cost and weight of the lens barrel.

  An object of the present invention is to solve the above-described problems, and an object thereof is to provide a lens barrel that secures impact resistance while suppressing cost, and an imaging apparatus using the lens barrel. .

The lens barrel according to claim 1 is a lens barrel having an optical system and attached to an imaging device,
A rectilinear cylinder that moves linearly in the optical axis direction of the optical system with respect to the imaging device;
A rotating cylinder disposed coaxially with the rectilinear cylinder and rotatable with respect to the rectilinear cylinder, wherein a cam groove is formed on a peripheral surface;
A plurality of pins provided in the straight cylinder and disposed in the cam groove;
When taking a cross section in the optical axis direction of the rotating cylinder, both sides of the cam groove are inclined so as to approach toward the bottom,
Said pins, and N metal pin, Ri pin der made of resin of M (N> M),
One of the metal pins is disposed at a predetermined position when viewed in the optical axis direction,
The predetermined position is in a virtual plane that passes through the lower end of the gravitational acceleration direction at the tip of the lens barrel and the optical axis of the optical system in the posture of the photographing state,
The metal pin disposed at the predetermined position and the resin pin are not in contact with the cam groove at the time of image pickup by the image pickup apparatus, but are in contact with each other when receiving an impact force .

  According to the present invention, it is possible to improve impact resistance by providing metal pins that are more numerous than resin pins, while reducing costs by providing resin pins. Further, by providing the metal pin on the straight cylinder, it is possible to receive an impact force from the metal pin at an optimal position.

  A lens barrel according to a second aspect of the present invention is the lens barrel according to the first aspect, wherein the pins are four metal pins and two resin pins.

  By providing four metal pins, sufficient impact resistance can be ensured.

  By disposing one of the metal pins at the predetermined position, sufficient impact resistance can be ensured despite the small number of pins. Here, as a specific example of the “predetermined position”, referring to FIGS. 2 and 3, for example, when an imaging device in a photographing state is accidentally dropped, the position of the tip of the lens barrel in contact with the floor surface is There is a high possibility that the lower end LP in the direction of gravitational acceleration is the posture in the shooting state. In such a case, it is considered that the maximum impact force is transmitted along a virtual in-plane VP that passes through the bottom end LP in the gravitational acceleration direction at the tip of the lens barrel and the optical axis AX of the optical system in the shooting state posture. It is preferable that a metal pin is arranged with a predetermined position in the virtual plane or in the vicinity thereof. However, when the lens barrel has an unbalanced configuration that is not arranged at the center of the imaging device, the position of the tip of the lens barrel that is in contact with the floor or the like at the time of dropping is not necessarily in the imaging state. Since it is not necessarily the lowest end in the direction of gravitational acceleration of the device, the definition of the predetermined position is not limited to the above.

According to a third aspect of the present invention, in the lens barrel according to the first aspect , the metal pin arranged at the predetermined position has the same shape as the other metal pins. It is arranged at a position away from the optical axis with respect to the metal pin.

  If all the metal pins have the same shape, the cost can be reduced by sharing parts. Further, by disposing the metal pin disposed at the predetermined position at a position away from the optical axis with respect to the other metal pins, the predetermined position is determined when the rectilinear cylinder is moved. Since the metal pin disposed in the position can be prevented from coming into contact with the corresponding cam groove, the sliding resistance is reduced and the operability is improved.

  Sliding resistance is reduced by contacting the metal pin arranged at the predetermined position and the resin pin with the corresponding cam groove only when receiving an impact force. In addition, impact resistance can be ensured when necessary.

According to a fourth aspect of the present invention, in the lens barrel according to the first aspect , the metal pin other than the metal pin arranged at the predetermined position is formed in the cam groove at the time of imaging by the imaging device. The straight cylinder moves straight in the direction of the optical axis of the optical system with respect to the imaging device when the pin moves along the cam groove according to the rotation of the rotary cylinder. And

  As a result, the rectilinear cylinder can be linearly moved to an arbitrary position in accordance with the rotation of the rotating cylinder.

An imaging apparatus according to a fifth aspect includes the lens barrel according to any one of the first to fourth aspects.

1 is an external view of a digital still camera that is an example of an imaging apparatus including a lens barrel according to an embodiment. 1 is a perspective view of a lens barrel 100 according to the present embodiment that is attached to a digital still camera 1. FIG. It is the front view which looked at the lens barrel 100 from the optical axis direction object side. It is the figure which cut | disconnected the lens-barrel 100 of FIG. 3 by the IV-IV line, and looked at the arrow direction. FIG. 3 is a perspective view showing a straight barrel 120 and a rotary barrel 130 removed from the lens barrel 100. It is the front view which looked at the composition of Drawing 5 from the optical axis direction object side. It is the side view which looked at the structure of FIG. 5 from the optical axis orthogonal direction. It is sectional drawing which cut | disconnected the structure of FIG. 6 by the XIII-XIII line | wire, and looked at the arrow direction. It is sectional drawing which cut | disconnected the structure of FIG. 7 by the IX-IX line and looked at the arrow direction. FIG. 10 is an enlarged view of a portion indicated by an arrow X in the configuration of FIG. 9. It is the figure which expanded the site | part shown by the arrow XI in the structure of FIG. FIG. 10 is a cross-sectional view similar to FIG. 9 according to another embodiment. It is a perspective view of the 2nd holding frame.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an external view of a digital still camera that is an example of an imaging apparatus including a lens barrel according to the present embodiment. FIG. 1A is a front view of the digital still camera 1, and FIG. 1B is a rear view.

  As shown in FIG. 1, the digital still camera 1 includes an imaging unit 2 having a lens barrel and an imaging device, and a camera body unit 3.

  The imaging unit 2 includes a lens barrel capable of zoom operation and a solid-state imaging device such as a CCD, and can convert a subject image formed via the lens barrel into an image signal by the solid-state imaging device.

  The camera body 3 includes an LCD display unit 6 composed of an LCD (Liquid Crystal Display), an EVF (Electronic View Finder) 7, and an external connection terminal for connecting the digital still camera 1 to a personal computer (not shown). The image signal captured by the imaging unit 2 is subjected to predetermined signal processing, image display on the LCD display unit 6 and EVF 7, image recording on a recording medium such as a memory card (not shown), or personal Processing such as image transfer to a computer is performed.

  On the front surface of the camera body 3, a flash light emitting unit 4 is provided at an appropriate upper position. Further, an LCD display unit 6 and an EVF 7 are provided on the back side of the camera body unit 3 for displaying captured images and reproducing and displaying recorded images.

  On the upper surface of the camera body 3, there are provided a shutter button 5 and a shooting mode changeover switch (not shown) that switches between “recording mode” and “reproduction mode” near the shutter button 5. The recording mode is a mode for taking a picture from the shooting standby state through the exposure control process, and the playback mode is a mode for reproducing and displaying the shot image recorded on the memory card on the LCD display unit 6 and the EVF 7. is there.

  On the back surface of the camera body 3, a playback frame advance switch / zoom switch 9 is provided for frame playback of playback images and zoom operations during shooting. The frame advance of the playback image by the playback frame advance switch / zoom switch 9 is a mode in which the camera is set to the playback mode and the images recorded on the memory card 13 are sequentially displayed on the LCD display unit 6 together with the frame number. . Note that it is possible to instruct to change the image display on the LCD display unit 6 in the ascending order direction (direction of photographing order) or the descending order direction (direction opposite to the photographing order). Further, the zoom operation at the time of shooting is performed by operating the playback frame advance switch / zoom switch 9 to change the magnification of the imaging optical system, which is a zoom lens, in the tele direction or the wide direction.

  Further, an EVF changeover switch 8 for selecting an LCD display unit 6 and an EVF 7 for displaying an image is provided on the back surface of the camera body unit 3.

  In addition, a battery (not shown) as a power source for operating the digital still camera 1 is provided inside the bottom surface of the camera body 3.

  2 is a perspective view of the lens barrel 100 according to the present embodiment attached to the digital still camera 1, and FIG. 3 is a front view of the lens barrel 100 viewed from the object side in the optical axis direction. 4 is a view of the lens barrel 100 of FIG. 3 taken along line IV-IV and viewed in the direction of the arrow.

  The lens barrel 100 according to the present embodiment will be described using a zoom lens having a five-group configuration as an example. The lens barrel 100 includes an optical system including a first lens group L1, a second lens group L2, a third lens group L3, a fourth lens group L4, and a fifth lens group L5 in order from the object side. The first lens unit L1, the second lens unit L2, the third lens unit L3, and the fourth lens unit L4 move in the optical axis direction while zooming by changing the inter-group distance. The fourth lens unit L4 independently moves in the optical axis direction to perform focusing. The fifth lens unit L5 is a lens unit that does not move in the optical axis direction during imaging.

  A schematic configuration of the lens barrel 100 will be described with reference to FIG. The lens barrel 100 is provided with an outer fixed tube 110, a rectilinear tube 120, a rotating tube 130, and an inner fixed tube 140 coaxially from the outside in the direction orthogonal to the optical axis, all of which are made of resin. The outer fixed cylinder 110 whose end is fixed to the camera body 3 is provided with a pair of guide grooves 111 extending in the optical axis direction on the inner surface. A protrusion 121 that engages with the guide groove 111 is provided on the outer periphery of the rectilinear cylinder 120, so that the rectilinear cylinder 120 can move in the optical axis direction with respect to the outer fixed cylinder 110 without rotating. Yes. A first holding frame 112 that holds the first lens unit L1 is attached to the inner periphery of the object side end (left end in FIG. 4) of the rectilinear cylinder 120.

  As will be described in detail later, a metal pin 150 and a resin pin 160 are provided on the inner periphery of the straight cylinder 120. Cam grooves 131 for accommodating the pins 150 and 160 are formed on the outer periphery of the rotating cylinder 130 held so as to be rotatable only at the center of the optical axis. As shown in the perspective view of FIG. 13, the second holding frame 113 that holds the second lens unit L2 is an end portion of two guide shafts 114 (only one is shown in FIG. 4) extending in the optical axis direction. It is fixed to. The guide shaft 114 is engaged with the hole 140a of the inner fixed cylinder 140, and can move in the optical axis direction together with the second holding frame 113 by sliding with respect to the hole 140a. The third lens unit L3 provided in the inner fixed tube 140 is held by the third holding frame 115, and is provided with two guide shafts 116 (only one is shown in FIG. 4) extending in the optical axis direction. Along the optical axis.

  The fourth lens unit L4 provided in the inner fixed tube 140 is held by a fourth holding frame 117, and can move in the optical axis direction along two guide shafts 116 extending in the optical axis direction. It has become. The fifth lens unit L5 is fixed to the end of the outer fixed cylinder 110 by the fifth holding frame 118. A shutter mechanism 119 is disposed on the object side of the third lens unit L3.

  The operation of the lens barrel 100 will be described. When the zoom operation is performed, the motor MT shown in FIG. 2 rotates, so that the rotating cylinder 130 rotates via a power transmission mechanism (not shown). Then, the cam groove 131 of the rotating cylinder 130 rotates and the pins 150 and 160 receive a driving force in the optical axis direction and the rotating direction. However, the rectilinear cylinder 120 is only rectilinearly moved by the protrusion 121 engaged with the guide groove 111. Therefore, it moves in the optical axis direction according to the rotation of the rotary cylinder 130. As a result, the first lens unit L1 is displaced to a predetermined position in the optical axis direction.

  Furthermore, the second holding frame 113 and the third holding frame 115 each have a pin (not shown) that engages with a cam groove (not shown) provided on the inner periphery of the rotary cylinder 130. In accordance with the rotation of 130, the guide shaft 114 moves in the optical axis direction along the holes 140a and 116 in which the guide shaft 114 slides. As a result, the second lens unit L2 and the third lens unit L3 are displaced to predetermined positions in the optical axis direction.

  The fourth holding frame 117 is displaced in the optical axis direction via a motor (not shown) and a power transmission mechanism. Since the motor MT for rotating the rotating cylinder 130 and the motor for driving the fourth holding frame 117 are interlocked according to a signal from the digital still camera 1 during the zoom operation, the first lens group L1 to the fourth lens group L4. Can be displaced to positions suitable for zooming. The fifth lens unit L5 does not move. In addition, since the motor that drives the fourth holding frame 117 is driven independently according to the signal from the digital still camera 1, only the fourth lens unit L4 can be displaced in the optical axis direction during focusing.

  5 is a perspective view showing the lens barrel 100 with the rectilinear barrel 120 and the rotary barrel 130 removed, and FIG. 6 is a front view of the configuration of FIG. 5 viewed from the object side in the optical axis direction. FIG. 8 is a side view of the configuration of FIG. 5 viewed from the direction orthogonal to the optical axis, FIG. 8 is a cross-sectional view of the configuration of FIG. 6 taken along line XIII-XIII and viewed in the direction of the arrow, and FIG. It is sectional drawing which cut | disconnected the structure of FIG. 7 by the IX-IX line and looked at the arrow direction. In FIG. 9, the vertical direction is the gravitational acceleration direction (Z direction, the direction perpendicular to the Z direction in the plane perpendicular to the optical axis is the Y direction) during normal shooting. 10 and 11 are enlarged views of the parts indicated by arrows X and XI in the configuration of FIG. 9, but the optical axis is shown as being upward.

  As shown in FIGS. 5 and 9, substantially rectangular projections 121 are formed on the outer periphery of the image side end of the rectilinear cylinder 120 at intervals of 60 degrees. As shown in FIG. 9, stepped holes 122 are formed in the protrusions 121 on the upper side in the Z direction and the protrusions 121 on both sides of the protrusion 121 on the lower side in the Z direction, and the stepped holes 123 are formed in the protrusions 121 on the lower side in the Z direction. Is formed.

  As shown in FIG. 10, the stepped hole 122 has a diameter-expanded hole part 122a and a diameter-reduced hole part 122b. As shown in FIG. 11, the stepped hole 123 also has a diameter-expanded hole portion 123a and a diameter-reduced hole portion 123b. As is apparent from comparison between FIGS. 10 and 11, the depth of the diameter-expanded hole portion 123a. Da is deeper than the depth Db of the diameter-enlarged hole 122a.

  As shown in FIGS. 10 and 11, the metal pin 150 (N = 4) has a shape in which a cylindrical portion 150a, a disk portion 150b, and a truncated conical portion 150c are coaxially connected. The pin 150 having the same shape is attached to the stepped holes 122 and 123 by inserting the cylindrical portion 150a through the reduced diameter holes 122b and 123b and abutting the disk portion 150b against the enlarged diameter holes 122a and 123a. However, the pin 150 attached to the stepped hole 123 is attached at a position farther from the optical axis than the pin 150 attached to the stepped hole 122 due to the difference between the depths Da and Db. Here, the pin 150 mounted in the stepped hole 123 is provided at a position where a virtual plane including the optical axis and the Z direction intersects the inner peripheral surface of the rectilinear cylinder 120.

  As shown in FIG. 9, the inner peripheral side of the two protrusions 121 that do not form the stepped hole in the rectilinear cylinder 120 is raised like a truncated cone, and this constitutes a resin pin 160 (M = 2) To do.

  The pins 150 and 160 are accommodated in the six cam grooves 131 formed on the outer periphery of the rotary cylinder 130. Referring to FIG. 8, the cam groove 131 having the same shape has a tapered shape in which both side surfaces approach each other toward the bottom as viewed in the cross section in the optical axis direction. Here, the truncated cone portion 150 c of the pin 150 mounted in the stepped hole 122 is in contact with the side surface of the cam groove 131. On the other hand, the pin 150 and the pin 160 attached to the stepped hole 123 are not in contact with the cam groove 131.

  As described above, when the rotary cylinder 130 is rotated during the zoom operation, the cam grooves 131 are rotated so that the three circumferentially arranged pins 150 that are in contact with the cam grooves 131 receive an equal driving force. The rectilinear cylinder 120 moves in the optical axis direction without tilting according to the rotation of the rotating cylinder 130. At this time, since the pin 150 and the pin 160 mounted in the stepped hole 123 are not in contact with the cam groove 131, the sliding resistance generated when the pin 150 and the pin 160 slide on the cam groove 131 is suppressed. Power saving can be achieved.

  On the other hand, when the digital still camera 1 is accidentally dropped, the tip of the lens barrel 100 receives an impact force F from the floor surface or the like. In this case, the impact force is often directed in the Z direction in FIG. . At this time, the three pins 150 attached to the stepped holes 122 first receive a part of the impact force F, but further, the linearly moving cylinder 120 is slightly deformed, so that the pins 150 attached to the stepped holes 123 become The cam groove 131 comes into contact with the corresponding cam groove 131, so that a part of the impact force F can be received. Similarly, since the pin 160 also abuts on the corresponding cam groove 131, a part of the impact force F can be received supplementarily.

  According to the present invention, the sliding resistance during zoom operation is reduced by disposing the metal pin 150 at a position where it does not contact the cam groove 131 during normal shooting but is most susceptible to impact force when dropped. In addition, the impact resistance can be improved. Note that the pin 150 attached to the stepped hole 123 may be provided above the Z-axis direction.

  FIG. 12 is a cross-sectional view similar to FIG. 9 according to another embodiment. In the present embodiment, the straight cylinder 120 is provided with projections 121 at intervals of 60 degrees as in the above-described embodiment. As shown in FIG. 12, a stepped hole 122 is formed in a protrusion 121 on the lower side in the Z direction and two protrusions 121 that are 120 degrees apart from each other, and a metal pin 150 (N = 3) is disposed. In addition, the step adjacent to the protrusion 121 on the lower side in the Z direction is not formed with a stepped hole, and a resin pin 160 (M = 2) is formed inside thereof. However, in this embodiment, unlike the above-described embodiment, the deep stepped hole 123 is not formed. Therefore, there are five cam grooves 131. Other configurations are the same as those of the above-described embodiment.

  Also in the present embodiment, when the rotary cylinder 130 rotates during the zoom operation, the cam grooves 131 rotate, and the three circumferentially arranged pins 150 in contact with the cam grooves 131 receive an equal driving force, As a result, the rectilinear cylinder 120 moves in the optical axis direction without being tilted according to the rotation of the rotating cylinder 130. At this time, since the pin 160 is not in contact with the cam groove 131, sliding resistance can be suppressed and power saving can be achieved.

  On the other hand, when the digital still camera 1 is accidentally dropped, a part of the impact force F is obtained by the three pins 150 including the metal pins 150 arranged at positions where the impact force is most easily received when the digital still camera 1 is dropped. Further, when the straight cylinder 120 is slightly deformed, the pin 160 also comes into contact with the corresponding cam groove 131, whereby a part of the impact force F can be received supplementarily.

  The present invention is not limited to the embodiments described in the specification, and other embodiments and modifications are apparent to those skilled in the art from the embodiments and ideas described in the present specification. It is. The description and examples are for illustrative purposes only, and the scope of the invention is indicated by the following claims.

DESCRIPTION OF SYMBOLS 1 Digital still camera 2 Image pick-up part 3 Camera body part 4 Flash light emission part 5 Shutter button 6 Display part 8 Changeover switch 9 Zoom switch 13 Memory card 100 Lens barrel 110 Outer fixed cylinder 111 Guide groove 112 First holding frame 113 Second holding Frame 114 Guide shaft 115 Third holding frame 116 Guide shaft 117 Fourth holding frame 118 Fifth holding frame 120 Rectilinear cylinder 121 Projection 122 Stepped hole 122a Expanded hole portion 122b Reduced diameter hole portion 123 Stepped hole 123a Expanded hole portion 123b Reduced-diameter hole 130 Rotating cylinder 131 Cam groove 140 Inner fixed cylinder 150 Metal pin 150a Cylindrical part 150b Disk part 150c frustoconical part 160 Resin pins L1 to L5 Lens group MT Motor

Claims (5)

A lens barrel that has an optical system and is attached to an imaging device,
A rectilinear cylinder that moves linearly in the optical axis direction of the optical system with respect to the imaging device;
A rotating cylinder disposed coaxially with the rectilinear cylinder and rotatable with respect to the rectilinear cylinder, wherein a cam groove is formed on a peripheral surface;
A plurality of pins provided in the straight cylinder and disposed in the cam groove;
When taking a cross section in the optical axis direction of the rotating cylinder, both sides of the cam groove are inclined so as to approach toward the bottom,
Said pins, and N metal pin, Ri pin der made of resin of M (N> M),
One of the metal pins is disposed at a predetermined position when viewed in the optical axis direction,
The predetermined position is in a virtual plane that passes through the lower end of the gravitational acceleration direction at the tip of the lens barrel and the optical axis of the optical system in the posture of the photographing state,
The metal pin disposed at the predetermined position and the resin pin are not in contact with the cam groove at the time of image pickup by the image pickup device but are in contact with each other when receiving an impact force. Tube.   The lens barrel according to claim 1, wherein the pins are four metal pins and two resin pins. The metal pin disposed at the predetermined position has the same shape as the other metal pins, but is disposed at a position away from the optical axis with respect to the other metal pins. The lens barrel according to claim 1 . A metal pin other than the metal pin arranged at the predetermined position is in contact with the cam groove during imaging of the imaging apparatus, and the pin is moved along the cam groove according to the rotation of the rotating cylinder. There by moving the lens barrel according to claim 1, characterized in that said rectilinear tube moves linearly in the optical axis direction of the optical system relative to the imaging device. Imaging apparatus characterized by having a lens barrel according to any one of claims 1-4.

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