JP2010072627A - Lens barrel and imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve resistance of a lens barrel to a shock. <P>SOLUTION: The lens barrel includes a lens holding member for holding a lens, a guide shaft for guiding the lens holding member movably, and a cam member having a first cam surface engaging a first cam follower provided to the lens holding member and a second cam surface engaging a second cam follower provided to the lens holding member, and driving the lens holding member along the guide shaft by engagement between the first cam follower and the second cam follower. The cam member has a gap between the second cam follower and the second cam surface. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a lens barrel and an imaging apparatus.

  Patent Document 1 below describes a lens barrel that includes a guide bar that guides a moving direction, and a lens frame that has a sleeve that engages with the guide bar and holds a lens. The sleeve is further provided with a cam follower, and the lens frame is moved along the optical axis direction of the lens by rotating a cam cylinder having a cam groove engaged with the cam follower.

Japanese Patent Laid-Open No. 06-174998

  In the conventional lens barrel, an external impact is applied to the cam groove and the cam follower, and the cam groove and the cam follower may be damaged.

  Therefore, in order to solve the above problem, as a first embodiment of the present invention, a lens holding member that holds a lens, a guide shaft that movably guides the lens holding member, and a first cam follower provided on the lens holding member are provided. A first cam surface that engages and a second cam surface that can be engaged with a second cam follower provided on the lens holding member, and the lens holding member is moved along the guide shaft by the engagement of the first cam follower and the first cam surface. And a cam member for driving the lens, wherein the cam member has a gap between the second cam follower and the second cam surface.

  As a second aspect of the present invention, there is provided an imaging apparatus including the lens barrel described above and an imaging unit that captures an image by the lens.

1 is a cross-sectional view of a lens barrel 100. FIG. It is a perspective view which shows the cam cylinder 150 independently. 4 is a perspective view showing a relationship between a fixed cylinder 140 and a cam cylinder 150. FIG. FIG. 4 is a development view of the cam cylinder 150. 4 is a cross-sectional view schematically showing a relationship among a fixed cylinder 140, a cam cylinder 150, and a sliding cylinder 116. FIG. 1 is a diagram schematically illustrating a structure of an imaging apparatus 300 including a lens barrel 100. FIG.

  Hereinafter, the present invention will be described through embodiments of the invention. However, the following embodiments do not limit the invention according to the claims. In addition, not all the combinations of features described in the embodiments are essential for the solving means of the invention.

  FIG. 1 is a cross-sectional view showing the structure of the lens barrel 100. Further, the upper side of FIG. 1 shows a state in which the first group 110 has moved backward, and the lower side of FIG. 1 shows a state in which the first group 110 has advanced by focusing.

  The lens barrel 100 includes a fixed barrel 140, a cam barrel 150, a sliding barrel 116, and a zoom ring 120 that are arranged coaxially with respect to the optical axis C thereof. The fixed cylinder 140 has a mount portion 144 at the rear end corresponding to the right side in the drawing. The mount portion 144 is fitted to a mount provided on a body such as a camera and supports the fixed cylinder 140.

  Further, the fixed cylinder 140 includes a pair of guide bars 142 on the outer peripheral side in the vicinity of the front end corresponding to the left side in the drawing. Both ends of the guide bar 142 are fixed to the fixed tube 140, and the guide bar 142 is arranged in parallel with the optical axis C. Further, a cam cylinder 150 is disposed between the fixed cylinder 140 and the guide bar 142 along the outer peripheral surface of the fixed cylinder 140. The fixed cylinder 140 includes a pair of guide bars 161 on the inner peripheral side. Both ends of the guide bar 161 are fixed to the fixed cylinder 140, and the guide bar 161 is arranged in parallel with the optical axis C.

  A sliding cylinder 116 is disposed outside the guide bar 142. The sliding tube 116 has a fitting portion 118 a and a U groove 118 b that extend toward the inside in the radial direction of the lens barrel 100. In the illustrated example, the fitting portion 118 a and the U groove 118 b are disposed along the guide bar 142. Each of the fitting portion 118 a and the U groove 118 b is fitted into the guide bar 142. As a result, the sliding cylinder 116 is guided by the guide bar 142 and moves along a direction parallel to the optical axis C.

  The sliding cylinder 116 has a male lead 113 on the outer surface. The male lead 113 engages with the female lead on the inner peripheral surface of the lead ring 114. As a result, the lead ring 114 performs focusing by moving with respect to the sliding cylinder 116.

  The lead ring 114 extends to the front of the guide bar 142 outside the sliding cylinder 116 and holds the lens frame 112 inside. The lens frame 112 holds the front ball 111. With such a structure, the front ball 111 also moves as the sliding cylinder 116 moves. The front lens 111 is not limited to a single lens but may be a lens group in which a plurality of lenses are combined.

  A zoom ring 120 is disposed outside the lead ring 114. When the zoom ring 120 is rotated, the cam cylinder 150 is rotated, and the sliding cylinder 116 is moved along the guide bar, so that the sliding cylinder 116 is integrally moved and zoomed together with the second group and the third group described later. I do.

  A space between the rear end of the zoom ring 120 and the mount portion 144 of the fixed barrel 140 is covered with a cover portion 146 to prevent dust and the like from entering the lens barrel 100. The cover part 146 is fixed to the fixed cylinder 140 and does not rotate. Further, the zoom ring 120 is provided with a non-slip 122 that is grasped by the user.

  The lens barrel 100 further includes a second group 160 and a third group 170. The second group 160 and the third group 170 are supported by the guide bar 161. The second group 160 and the third group 170 move in the direction of the optical axis C by receiving the driving force from the cam cylinder 150 and being guided by the guide bar 161.

  The second group 160 includes a diaphragm unit 164 and a lens 166, a vibration correction unit 162 that corrects the vibration of the lens 166, and a lens frame 165 that holds the lens 166 via the vibration correction unit 162. The lens frame 165 includes a pair of fitting portions 167 spaced apart from each other along the guide bar 161, and a U groove provided on the opposite side of the optical axis C with respect to the pair of fitting portions 167. 169. The second group 160 is slidably supported by the guide bar 161 by fitting the pair of fitting portions 167 into one guide bar 161 and fitting another guide bar 161 into the U groove 169. The lens frame 165 further has a cam follower 168 protruding in the radial direction.

  The third group 170 includes a lens 176 and a lens frame 175 that holds the lens 176. Similarly to the lens frame 165 of the second group 160, the lens frame 175 includes a pair of fitting portions 177, a U groove 179, and a cam follower 178. Since the configuration and operation of the fitting portion 177 and the U groove 179 are the same as those of the fitting portion 167 and the U groove 169, description thereof is omitted.

  FIG. 2 is a perspective view showing the cam cylinder 150 alone. The cam cylinder 150 has a plurality of cam grooves including drive cams 151, 153, and 154 and a buffer cam 152. The driving cam 151 is engaged with the sliding cylinder 116 to drive the first group 110, as will be described later.

  In the cam cylinder 150, areas where the drive cams 151, 153, 154 and the buffer cam 152 are not formed are removed to form notches 158. Thereby, the lens barrel 100 can be reduced in weight, and the material of the cam barrel 150 can be saved.

  FIG. 3 is a perspective view showing the relationship between the fixed cylinder 140 and the cam cylinder 150. As shown, the cam cylinder 150 is mounted along the outer surface of the fixed cylinder 140 and rotates along the peripheral surface of the fixed cylinder 140.

  In FIG. 3, a driving cam follower 117 and a buffering cam follower 119 are inserted into the driving cam 151 and the buffering cam 152. The sliding cylinder 116 is coupled to the outer ends of the driving cam follower 117 and the buffering cam follower 119.

  The driving cam 153 of the cam barrel 150 drives the second group 160, and the driving cam 154 drives the third group 170. Correspondingly, the fitting portion 167 and the cam follower 168 of the second group 160 and the fitting portion 177 and the cam follower 178 of the third group 170 can move with respect to the stationary tube 140 so that the opening portion is provided in the fixing tube 140. 141 is provided.

  FIG. 4 is a development view of the cam cylinder 150. The cross sections of the driving cam follower 117 and the buffering cam follower 119 engaged with the driving cam 151 and the buffering cam 152 are also shown.

  As illustrated, the drive cam 151 and the buffer cam 152 have the same shape. On the other hand, the driving cams 153 and 154 have different shapes from the driving cam 151 and the buffer cam 152.

  On the other hand, the driving cam follower 117 that engages with the cam surface of the driving cam 151 and the buffering cam follower 119 that can engage with the cam surface of the buffering cam 152 have different diameters. That is, the drive cam follower 117 has a diameter substantially the same as the width of the drive cam 151. For this reason, the drive cam follower 117 is in contact with the cam surface of the drive cam 151.

  On the other hand, the buffer cam follower 119 has a radius smaller than the width of the buffer cam 152. For this reason, there is a gap between the cam surface of the buffer cam 152 and the buffer cam follower 119.

  The cam follower 168 of the second group 160 is inserted into the driving cam 153. The cam follower 178 of the third group 170 is inserted into the drive cam 154. Here, the width of the driving cam 153 and the diameter of the cam follower 168 are substantially the same, and the width of the driving cam 154 and the diameter of the cam follower 178 are substantially the same. As a result, the cam follower 168 is driven along the drive cam 153 and the cam follower 178 is driven along the drive cam 154 as the cam cylinder 150 rotates.

  FIG. 5 is a cross-sectional view schematically showing the relationship among the fixed cylinder 140, the cam cylinder 150, and the sliding cylinder 116. As shown in the figure, a cam cylinder 150 is mounted on the outer periphery of the fixed cylinder 140, and a sliding cylinder 116 is further disposed on the outer periphery thereof. Further, a guide bar 142 extending in a direction perpendicular to the paper surface is disposed between the cam cylinder 150 and the sliding cylinder 116. Furthermore, the sliding cylinder 116 includes a driving cam follower 117 and a buffering cam follower 119 that protrude toward the optical axis of the lens barrel 100, and a fitting portion 118 a and a U groove 118 b that engage with the guide bar 142.

  The drive cam follower 117 and the buffer cam follower 119 are inserted into the drive cam 151 and the buffer cam 152, respectively. However, the drive cam follower 117 is in contact with the cam surface of the drive cam 151, but there is a gap between the buffer cam follower 119 and the cam surface of the buffer cam 152.

  Here, the driving cam follower 117 is arranged closer to the fitting portion 118a than the buffering cam follower 119 in the circumferential direction. Thus, the driving force received by the driving cam follower 117 can be efficiently transmitted to the sliding cylinder 116. Further, it is possible to suppress the front ball 111 from being tilted.

  The fitting portion 118 a is inserted through the guide bar 142, and the guide bar 142 is fixed to the fixed cylinder 140. Therefore, when the cam cylinder 150 rotates and the driving cam follower 117 is pushed by the driving cam 151, the sliding cylinder 116 does not rotate.

  Since the driving cam follower 117 is in contact with the cam surface of the driving cam 151, the sliding cam 116 moves along the guide bar 142 when the driving cam 151 drives the driving cam follower 117. As a result, the lead ring 114, the lens frame 112, and the front ball 111 also move together with the sliding cylinder 116.

  On the other hand, since there is a gap between the cam surface of the buffer cam 152 and the buffer cam follower 119, the buffer cam follower 119 is not driven by the buffer cam 152. However, when the first cam unit including the front lens 111, the lens frame 112, the lead ring 114, and the sliding cylinder 116 is subjected to a mechanical load from the outside and the driving cam follower 117 is deformed, the buffer cam follower 119 is The load is distributed in contact with the cam surface of the buffer cam 152. Thereby, damage to the driving cam 151 and the driving cam follower 117 is suppressed.

  In this manner, the lens frame 112 including the lens frame 112 that holds the front lens 111, the lead ring 114, and the sliding cylinder 116, the guide bar 142 that guides the lens holding section to be movable, and the sliding cylinder 116 are provided. The driving cam follower 117 and the driving cam 151 include a driving cam 151 that engages with the driving cam follower 117 and a buffering cam 152 that can engage with the buffering cam follower 119 provided on the sliding cylinder 116. And the cam barrel 150 that drives the lens holding portion along the guide bar 142, and the buffer cam follower 119 and the buffer cam 152 form the lens barrel 100 having a gap therebetween.

  Thereby, when a load is applied to the first group from the outside, the load is distributed to the buffer cam 152 and the buffer cam follower 119, so that the practical strength is high and the durability is also increased. Therefore, it is possible to accurately guide the front ball 111 by the guide bar 142 and prevent the optical performance of the lens barrel 100 from being deteriorated.

  In view of the action of the buffer cam follower 119 and the buffer cam 152 as described above, the drive cam follower 117 and the buffer cam follower 119 are arranged at equal intervals along the direction around the optical axis C of the lens barrel 100. . Thereby, the load which acted on the 1st group 110 can be distributed more equally.

  In the above-described embodiment, the first group 110 in which an external load or impact often acts is described as an example. However, for example, when acceleration acts on the entire lens barrel 100, the members inside the lens barrel 100 are also subjected to the same impact as in the first group. Therefore, by adopting a structure like the first group 110 of the lens barrel 100, other lens groups can be protected.

  In the above embodiment, the widths of the driving cam follower 117 and the buffering cam follower 119 are changed by making the widths of the driving cam 151 and the buffering cam 152 the same, thereby changing between the buffering cam 152 and the buffering cam follower 119. A gap was formed. However, by using the drive cam follower 117 and the buffer cam follower 119 having the same diameter, the gap between the buffer cam 152 and the buffer cam follower 119 is changed by changing the widths of the drive cam 151 and the buffer cam 152. It can also be formed.

  Further, by making the elastic modulus of the buffer cam follower 119 lower than the elastic modulus of the drive cam follower 117, it is possible to further improve the impact dispersion effect by the buffer cam follower 119 and the buffer cam 152.

  FIG. 6 is a diagram schematically illustrating the structure of the imaging apparatus 300 including the lens barrel 100. In FIG. 6, the lens barrel 100 is schematically illustrated for the purpose of avoiding complicated drawing. However, the lens barrel 100 in FIG. 6 has the same structure as the lens barrel 100 shown in FIG. Therefore, the same components are denoted by the same reference numerals, and redundant description is omitted.

  The lens barrel 100 is detachably attached to the imaging unit 200 via the mount unit 260. In the imaging apparatus 300, the lens barrel 100 and the imaging unit 200 are also electrically coupled via a connection terminal (not shown). Thereby, the lens barrel 100 is supplied with power from the imaging unit 200. In some cases, a sub-control unit is provided in the lens barrel 100 to exchange signals with the main control unit 250 of the imaging unit 200.

  In the embodiment shown in FIGS. 1 to 5, the first group 110 is moved by the male lead 113 and the lead ring 114 during focusing. However, the focusing operation is not limited to this, and the first group 110 moves along the guide bar 142. May be moved directly. Similarly to the first group 110, the second group 160 and the third group 170 may have a structure including the buffer cam 152 and the buffer cam follower 119.

  The imaging unit 200 houses an optical system including a main mirror 240, a pentaprism 270, and an eyepiece optical system 290, and a main control unit 250. The primary mirror 240 has a standby position that is inclined on the optical path of incident light incident through the optical system 101 of the lens barrel 100, and a photographing position that rises while avoiding the incident light (shown by a dotted line in the figure). ).

  The primary mirror 240 in the standby position guides most of the incident light to the focusing screen 272 disposed above. The focusing screen 272 is disposed at a focus position of the optical system 101 of the lens barrel 100 and forms an image formed by the optical system 101.

  The image formed on the focusing screen 272 is observed from the eyepiece optical system 290 via the pentaprism 270. As a result, the image on the focusing screen 272 can be viewed as a normal image from the eyepiece optical system 290.

  Between the pentaprism 270 and the eyepiece optical system 290, a half mirror 292 that superimposes the display image formed on the finder LCD 294 on the image of the focusing screen 272 is disposed. Thereby, at the exit end of the eyepiece optical system 290, the image on the focusing screen 272 and the image on the finder LCD 294 can be seen together. Note that information such as shooting conditions and setting conditions of the imaging apparatus 300 is displayed on the finder LCD 294.

  A part of the light emitted from the pentaprism 270 is guided to the photometry unit 280. The photometry unit 280 measures the intensity of incident light, its distribution, and the like, and refers to the measurement result when determining imaging conditions.

  On the other hand, a secondary mirror 242 is disposed on the back surface of the primary mirror 240 with respect to the incident light incident surface. The secondary mirror 242 guides part of the incident light transmitted through the primary mirror 240 to the distance measuring unit 230 disposed below. Thereby, when the primary mirror 240 is in the standby position, the distance measuring unit 230 measures the distance to the subject. When the primary mirror 240 is moved to the photographing position, the secondary mirror 242 is also retracted from the optical path of the incident light.

  A shutter 220, an optical filter 212, and an image sensor 210 are sequentially arranged behind the main mirror 240 with respect to the incident light from the lens barrel 100. When the shutter 220 is opened, the primary mirror 240 moves to the photographing position immediately before that, so that the incident light travels straight and enters the image sensor 210. As a result, the image formed by the incident light is converted into an electrical signal in the image sensor 210.

  In addition, the imaging unit 200 includes a main LCD 296 facing the outside on the rear surface with respect to the lens barrel 100. The main LCD 296 can display various setting information for the image capturing unit 200 and can display an image formed on the image sensor 210 when the primary mirror 240 is moved to the photographing position.

  The main control unit 250 comprehensively controls the various operations as described above. In addition, an autofocus mechanism that drives the lens barrel 100 can be formed by referring to the distance information to the subject detected by the distance measuring unit 230 on the imaging unit 200 side. Further, the distance measuring unit 230 can form a focus aid mechanism by referring to the operation amount of the lens barrel 100.

  In this manner, the imaging device 300 having the lens barrel 100 including the buffer cam 152 and the buffer cam follower 119 is formed. The effect of the lens barrel 100 described above can be enjoyed in the imaging apparatus 300. However, the application of the lens barrel 100 is not limited to this, and for example, it can be used for a focusing mechanism, a zoom mechanism, and the like in an optical system such as a video camera, binoculars, a microscope, and a surveying instrument.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. In addition, it will be apparent to those skilled in the art that various modifications or improvements can be added to the above embodiment. Furthermore, it is apparent from the description of the scope of claims that the embodiments added with changes or improvements can be included in the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 100 Lens barrel, 101 Optical system, 110 1st group, 111 Front lens, 112 Lens frame, 113 Male lead, 114 Lead ring, 116 Sliding cylinder, 117 Driving cam follower, 118a Fitting part, 118b U groove, 119 Buffer follower, 120 Zoom ring, 122 Non-slip, 140 Fixed cylinder, 141 Opening part, 142 Guide bar, 144 Mount part, 146 Cover part, 150 Cam cylinder, 151 Driving cam, 153 Driving cam, 154 Driving cam , 152 Buffer cam, 158 Notch part, 160 Second group, 161 Guide bar, 162 Vibration correction part, 164 Aperture part, 165 Lens frame, 166 Lens, 167 Fitting part, 168 Cam follower, 169 U groove, 170 3 groups, 175 lens frame, 176 lens, 177 fit Joint section, 178 cam follower, 179 U groove, 200 imaging section, 210 imaging device, 212 optical filter, 220 shutter, 230 ranging section, 240 primary mirror, 242 secondary mirror, 250 main control section, 260 mount section, 270 pentaprism 272 Focusing screen, 280 Metering unit, 290 Eyepiece optical system, 292 Half mirror, 294 Finder LCD, 296 Main LCD, 300 Imaging device

Claims (9)

A lens holding member for holding the lens;
A guide shaft for movably guiding the lens holding member;
A first cam surface that engages with a first cam follower provided on the lens holding member; and a second cam surface that can engage with a second cam follower provided on the lens holding member, and the first cam follower and the first cam follower. A cam member that drives the lens holding member along the guide shaft by engagement of one cam surface;
The lens barrel according to claim 1, wherein the cam member has a gap between the second cam follower and the second cam surface.   The lens barrel according to claim 1, wherein the lens holding member further includes a fitting portion that fits into the guide shaft.   The lens barrel according to claim 2, wherein the first cam follower is disposed closer to the fitting portion than the second cam follower.   The lens barrel according to any one of claims 1 to 3, wherein an elastic modulus of the first cam follower is higher than an elastic modulus of the second cam follower.   5. The lens barrel according to claim 1, wherein the first cam follower and the second cam follower are arranged at equal intervals along a direction around an optical axis of the lens.   The lens barrel according to any one of claims 1 to 5, wherein the lens is a first group. A second lens holding member for holding a second lens different from the lens;
A second guide shaft for movably guiding the second lens holding member;
The lens barrel according to any one of claims 1 to 6, further comprising: The lens barrel according to claim 7, wherein the cam member drives the second lens holding member along the second guide shaft. The lens barrel according to any one of claims 1 to 8,
An imaging apparatus comprising: an imaging unit that captures an image by the lens.

Images