JP2014170060A - Lens barrel and imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the light-shielding property of a gap between a first lens barrel and a second lens barrel, without depending on the eccentricity of the first lens barrel, with a simpler configuration.SOLUTION: A lens barrel includes the first lens barrel advancing and retreating in an optical axis direction, a second lens barrel 67 arranged outside the first lens barrel, and a light-shielding member 51 provided so as to block the gap between the first lens barrel and the second lens barrel. The light-shielding member includes at least one or more engagement parts which can be engaged with a locking part 67a provided in the second lens barrel, is arranged at the top end of the second lens barrel, and engaged to be movable in a plane orthogonal to an optical axis.

Description

  The present invention relates to a lens barrel and an imaging apparatus having a light blocking member that blocks leaked light transmitted through a gap.

  In a unit that holds a lens of an imaging apparatus such as a digital camera (hereinafter also referred to as a lens barrel), a zoom operation is performed by relatively moving a plurality of constituent members.

  An appropriate gap is maintained between the relatively moving members, and it is configured to operate smoothly without load. It is inevitable that an external light beam enters the lens barrel through the gap (hereinafter referred to as light beam leakage). Therefore, a light shielding member for preventing light leakage is often disposed inside the lens barrel. The prior art will be described below.

  For example, in Patent Document 1, a ring-shaped light shielding member is arranged in a gap between a first lens barrel (moving frame) and a second lens barrel (fixed frame) arranged outside the first lens barrel, and the gap The light beam entering from is blocked. The light shielding member has a ring shape in which the width in the radial direction is larger than the width in the optical axis direction. The light shielding member has a configuration in which a first ring and a second ring are bonded together. The first ring is an elastic body such as rubber, and the second ring is an inelastic body such as plastic. In addition, a plurality of slits are arranged over the entire circumference on the inner circumference of the first ring.

  In order to enhance the light shielding property of the light shielding member, the inner diameter of the light shielding member is set to be press-fitted with respect to the outer diameter of the first lens barrel. For this reason, during the zoom operation of the lens barrel, the lens barrel is extended and stored while the first ring rubs against the first barrel.

JP-A-6-273651

  The conventional lens barrel has a problem that light enters from a slit arranged in the first ring of the light shielding member when the first barrel moves back and forth. This is because the lens barrel moves back and forth while the first ring rubs against the first lens barrel during the zoom operation of the lens barrel. Since the first ring is made of an elastic body such as rubber, the shape of the first ring is deformed when rubbed against the first lens barrel. Along with the deformation of the first ring, the slit provided in the first ring is also deformed, and the gap between the slits is widened to cause light leakage.

  Although it is possible to suppress the intrusion of light from the gap of the slit by increasing the press-fitting amount of the light shielding member to the first lens barrel, a large sliding frictional force is generated between the first lens barrel and the light shielding member. Resulting in. As a result, a large load is applied to the electric motor that is a driving source of the lens barrel, which causes an increase in power consumption. Furthermore, a sound is generated due to sliding friction between the light shielding member and the second lens barrel, and the sound increases in proportion to an increase in the sliding load, causing noise.

  Further, as a method for fixing the light shielding member, a method for fixing to the second lens barrel by using an adhesive or a double-sided tape has been proposed. However, if the attachment position of the light shielding member is shifted with respect to the second lens barrel or the first lens barrel is decentered, the gap between the light shielding member and the first lens barrel becomes non-uniform, and the light shielding property. May be damaged.

(Object of invention)
An object of the present invention is to provide a lens barrel and an imaging device capable of improving the light shielding property of the gap between the first barrel and the second barrel with a simpler configuration regardless of the eccentricity of the first barrel. Is to provide a device.

  In order to achieve the above object, a lens barrel of the present invention includes a first lens barrel that moves forward and backward in the optical axis direction, a second lens barrel that is disposed outside the first lens barrel, and the first lens barrel. A lens barrel having a light shielding member provided so as to close a gap between the tube and the second lens barrel, wherein the light shielding member is against a locking portion provided in the second lens barrel. And has at least one engaging portion that can be engaged with each other, and is disposed at a distal end portion of the second lens barrel and is movably engaged in a plane perpendicular to the optical axis. It is what.

  According to the present invention, the light shielding property of the gap between the first lens barrel and the second lens barrel can be improved with a simpler configuration regardless of the eccentricity of the first lens barrel.

It is sectional drawing which shows the lens barrel which is an Example of this invention. It is a disassembled perspective view of the lens barrel of an Example. It is a perspective view which shows the light-shielding member of an Example. It is an enlarged view of the holding | maintenance location of the light shielding member in an Example.

  The mode for carrying out the present invention is as described in the following examples.

  Hereinafter, a lens barrel that is an embodiment of the present invention will be described with reference to FIGS. This lens barrel is detachably or integrally attached to an imaging device such as a digital camera.

  In FIG. 1, 1 is an optical lens constituting the first lens group, 2 is an optical lens constituting the second lens group, 3 is an optical lens constituting the third lens group, and 4 is a fourth lens group. The optical lens which comprises is shown. In the optical system of this embodiment, the first lens group 1, the second lens group 2, and the third lens group 3 are responsible for magnification change and image plane correction, and the fourth lens group 4 performs focus adjustment. It is a focus lens.

  11 is a first group barrel that holds the first lens group 1, 12 is a barrier cover that covers the entire surface of the first group barrel 11, 13 is a barrier blade that opens and closes between a position that covers the photographing optical path and a retracted position, and 14 Is a drive ring member for driving the barrier blades 13.

  Reference numeral 21 denotes a second group barrel, 31 denotes a third group barrel (FIG. 2), and 32 denotes a light amount adjustment mechanism including a shutter and ND, which is driven by a drive source. Reference numeral 33 denotes a third group holding frame for holding the third lens group 3 and the light amount adjusting mechanism 32.

  Reference numeral 51 denotes a light shielding member. Reference numeral 66 denotes a ring-shaped decorative ring (see FIG. 2; not shown in FIG. 1) for preventing the light-shielding member 51 from falling off. Reference numeral 61 denotes first-group barrels 11 and 2 by cam grooves disposed on the inner surface and the outer surface. This is a cam cylinder that moves in the optical axis direction while holding the group barrel 21 and the third group barrel 31. The rectilinear cylinder 62 disposed inside the first group lens barrel 11 is rotatable with respect to the cam cylinder 61 and is restricted by the rectilinear plate 65, and the first group lens barrel 11, the second group lens barrel 21 and The rotation of the third group barrel 31 is restricted and moved forward and backward in the optical axis direction. The decorative ring 66 constitutes a decorative member of the light shielding member 51.

  Reference numeral 63 denotes a cam cover cylinder which is disposed on the outer periphery of the cam cylinder 61 and is held in the rotational direction with the cam cylinder 61 by bayonet coupling with the cam cylinder 61. In addition, the rotation of the rectilinear plate 65 is restricted, and the advancing and retreating operation is performed in the optical axis direction by pin-engaging with a cam groove disposed in a rotating cylinder 64 described later. Reference numeral 64 denotes a rotating cylinder that is bayonet-coupled to the outer peripheral portion of the rectilinear plate 65 and is pin-engaged with a cam groove provided in a fixed cylinder 67 described later. The rotating cylinder 64 constitutes the first lens barrel. A gear for transmitting driving from a gear train (not shown) to be described later is provided on the outer peripheral portion.

  A fixed cylinder 67 is disposed outside the rotating cylinder 64. The rectilinear key of the rectilinear plate 65 is fitted into the key groove disposed on the inner peripheral surface to restrict the rotation of the rectilinear plate 65, and the cam pin of the rotary cylinder 64 is inserted into the cam groove disposed on the inner peripheral surface. By engaging, the rotating cylinder 64 is held and moved in the optical axis direction. The fixed cylinder 67 constitutes the second lens barrel.

  Reference numeral 43 denotes a focus motor for moving the fourth group holding frame 42 holding the focus lens in the optical axis direction, and 44 denotes a feed nut that is screwed with a screw portion provided on the rotation shaft of the focus motor 43. Here, the fourth group holding frame 42 is held by a main guide shaft 45 and a sub guide shaft 46 so as to be movable in the optical axis direction. Reference numeral 75 denotes a zoom motor.

  In the lens barrel having the above configuration, a zoom operation when shifting from the retracted state to the photographing state will be described.

  For ease of explanation, a lens barrel configuration related to a zoom operation will be described with reference to a perspective view of FIG.

  When power is supplied to the zoom motor 75, power is transmitted to the rotary cylinder 64 via a zoom gear train (not shown) and the gear of the rotary cylinder 64. A guide groove parallel to the optical axis direction is provided on the inner periphery of the fixed cylinder 67, and a rectilinear key of the rectilinear plate 65 is slidably fitted in the guide groove. On the other hand, a conical cam pin is provided on the outer periphery of the rotating cylinder 64 and slidably engages with a cam groove on the inner periphery of the fixed cylinder 67. As described above, when power is transmitted to the rotating cylinder 64, it moves forward and backward in the optical axis direction following the cam groove of the fixed cylinder 67 while rotating about the optical axis as the central axis.

  The cam pin of the cam cover cylinder 63 is slidably engaged with the cam groove on the inner periphery of the rotary cylinder 64, and the rotation is restricted by the rectilinear plate 65. Further, the cam cylinder 61 is rotatably held by a bayonet connection with the rotary cylinder 64 and moves forward and backward in the optical axis direction. Thus, when the rotary cylinder 64 is rotated, the cam cylinder 61 is fed out while rotating in the optical axis direction.

  The rectilinear cylinder 62 is held in a state of being rotatable relative to the cam cylinder 61 by bayonet coupling, and the rotation is restricted by the rectilinear plate 65, so that when the cam cylinder 61 rotates, the rectilinear cylinder 62 moves straight in the optical axis direction. While being paid out.

  The first group barrel 11, the second group barrel 21, and the third group barrel 31 that are cam-engaged with the cam barrel 61 are extended while moving straight in the optical axis direction by the action of the cam barrel 61 and the rectilinear barrel 62.

  The fourth group lens barrel 41 is held in a state of being movable in the direction of the optical axis by the action of a nut 44 and a screw provided in the focus motor 43, and the rotation is restricted by the main guide shaft 45 and the sub guide shaft 46. Thus, the movement of the cam cylinder 61 is performed independently of the movement of the cam cylinder 61 in the optical axis direction.

  With the above configuration, when the rotating cylinder 64 is rotated, each lens group is extended from the sinking position toward the subject, so that the lens barrel shifts from the sinking state to the photographing state.

  The lens barrel is zoomed by adjusting the distance between them appropriately by the action of the cam barrel 61, the rotary barrel 64, and the fixed barrel 67.

  Since the lens barrel as described above is operated by sliding between the members, an appropriate gap is required between the members. However, since the light enters from the outside through the gap, it is important to reduce the gap between the components to prevent the light from entering. In order to satisfy this contradictory requirement, it has been conventionally performed to block leaked light using a light shielding member so as to close the gap. In the present embodiment, since the leaked light from between the rotating cylinder 64 and the fixed cylinder 67 adversely affects the photographed image, the light shielding member 51 is arranged on the tip of the fixed cylinder 67, that is, on the subject side as described above. .

  Next, the light shielding member 51 will be described with reference to FIG. The figure is a perspective view showing the light shielding member 51.

  The light shielding member 51 is composed of the following members. 51a is a ring-shaped light shielding sheet such as a foam having excellent flexibility. Further, the light shielding sheet 51a is formed with three convex portions 51b equally divided in the circumferential direction of 120 degrees, and an engagement hole 51c is provided in each. The engaging hole 51c constitutes an engaging portion. The inner diameter dimension of the light shielding sheet 51a is set smaller than the outer diameter of the rotating cylinder 64 for the purpose of improving the light shielding property. Therefore, the light shielding sheet 51a is kept charged when it is assembled to the rotating cylinder 64. Further, the light shielding member 51 is disposed in a space between the decorative ring 66 and the fixed cylinder 67 that cover the distal end portion of the fixed cylinder 67. If the space of the light shielding sheet 51a is too large, the light shielding sheet 51a is exposed in the direction of the optical axis, and is drawn out of the lens barrel following the movement of the rotating cylinder 64. In addition, there are methods of sandwiching the light shielding member 51 with the decorative ring 66 so as to charge or fixing the light shielding member 51 to the fixing cylinder 67 with a double-sided tape or an adhesive. As a result, the amount of charge to the rotating cylinder 64 becomes non-uniform due to such eccentricity, and light leakage cannot be prevented at portions where the amount of charge is small. In order to solve such a problem, the configuration of this embodiment will be described below.

  FIG. 4 is an enlarged cross-sectional view of the locking portion of the light shielding member 51.

  Reference numeral 67a denotes a locking portion provided on the fixed cylinder 67, and 67b denotes a locking claw, which is provided at three positions equally at 120 degrees. The engagement hole 51c of the light shielding member 51 is engageable with the locking portion 67a of the fixed cylinder 67, and a clearance sufficient to move to a plane orthogonal to the optical axis is secured. Specifically, the clearance Δd between the inner diameter portion of the convex portion 51 b of the light shielding member 51 and the outer peripheral portion of the fixed cylinder 67 is a clearance (movable amount) greater than the eccentric backlash between the rotating cylinder 64 and the fixed cylinder 67. Is set. For this reason, when the rotating cylinder 64 is eccentric or falls with respect to the fixed cylinder 67, the sliding frictional force of the light shielding member 51 temporarily increases in the eccentric portion, but the light shielding member 51 is in a direction orthogonal to the optical axis. Since it is installed so as to be movable, it moves so as to follow the eccentricity of the rotating cylinder 64. As a result, the charge amount between the light shielding member 51 and the rotary cylinder 64 can be kept constant, so that the light shielding property can be improved.

  In this embodiment, since the light shielding member 51 is fixed without using an adhesive or a double-sided tape, the assemblability of the lens barrel is improved. Further, since the movement to the plane orthogonal to the optical axis is facilitated as compared with the case where the light shielding member 51 is fixed with an adhesive or the like, the followability of the light shielding member 51 accompanying the eccentricity or falling of the rotating cylinder 64 is improved. This makes it possible to improve the light shielding property. On the other hand, there is a concern that the engagement hole 51c of the light shielding member 51 is disengaged from the locking portion 67a of the fixed cylinder 67 due to the movement of the light shielding member 51, but in this embodiment, the fixing hole 51c is fixed. A locking claw 67b for preventing the light shielding member 51 from coming off is provided at the tip of the locking portion 67a of the tube 67, and even if the light shielding member 51 is lifted in the optical axis direction, it is pulled out of the lens barrel. To prevent that.

  As mentioned above, although the preferable Example of this invention was described, this invention is not limited to these Examples, A various deformation | transformation and change are possible within the range of the summary.

  For example, the number of the locking portions 67a of the fixed cylinder 67 and the number of the engagement holes 51c of the light shielding member 51 are not limited to those of the present embodiment, and one, two, or four or more are provided. You can also.

  As described above, the present embodiment can improve the light shielding property with a simpler configuration regardless of the eccentricity of the rotating cylinder 64 (first lens barrel).

64 Rotating barrel (first barrel)
67 Fixed tube (second lens barrel)
67a Locking part 67b Locking claw 51 Light-shielding member 51c Engagement hole

Claims (5)

A first barrel that moves back and forth in the direction of the optical axis;
A second lens barrel disposed outside the first lens barrel;
A lens barrel having a light shielding member provided so as to close a gap between the first lens barrel and the second lens barrel;
The light shielding member has at least one engaging portion that can be engaged with a locking portion provided in the second lens barrel, and is disposed at a distal end portion of the second lens barrel. And a lens barrel movably engaged in a plane orthogonal to the optical axis.   2. The lens barrel according to claim 1, wherein the light shielding member is disposed in a space between a decorative member that covers a distal end portion of the second lens barrel and the second lens barrel.   The engagement portion of the second lens barrel is provided with an engagement claw for preventing the engagement portion of the light shielding member from coming off from the engagement portion of the second lens barrel. The lens barrel according to 1 or 2.   4. The movable amount of the light shielding member in a plane orthogonal to the optical axis is set to be more than an eccentric backlash between the first lens barrel and the second lens barrel. The lens barrel according to claim 1.   An imaging apparatus comprising the lens barrel according to any one of claims 1 to 4.

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