JP2014122956A - Lens barrel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a flare due to the internal reflection of a lens barrel while miniaturizing the lens barrel in radial directions.SOLUTION: A lens barrel comprises: an optical system including a first lens, a diaphragm, a second lens and a third lens; a lead part for guiding a holding frame for holding the second lens and a motor for driving the lead part from a subject side to a non-subject side. The motor is partially arranged on a side inner than the external diameter of the third lens, and the motor is arranged at the subject side as compared with the lead part and at the non-subject side as compared with the diaphragm.

Description

  The present disclosure relates to a lens barrel used in a digital still camera. The lens barrel is a concept including both fixed and replaceable ones with respect to the digital still camera.

  A lens barrel is described in Patent Document 1, for example. In the lens barrel described in Patent Document 1, a focus drive mechanism 15 is disposed on the subject side of a shutter blade (aperture) 27.

Japanese Patent Laid-Open No. 10-288729

  By the way, the lens barrel is required to be downsized in order to facilitate the carrying of the user.

  Accordingly, the lens barrel of the present disclosure aims to reduce flare caused by reflection inside the barrel while realizing a reduction in size in the radial direction.

  The lens barrel according to the present disclosure holds an optical system including a first lens, a diaphragm, a second lens, and a third lens from the subject side toward the non-subject side, and the second lens. A lead portion for guiding the holding frame, and a motor for driving the lead portion. The motor is partially disposed on the inner side of the outer diameter of the third lens. It is arranged on the object side and on the non-object side of the aperture.

  According to the lens barrel of the present disclosure, it is possible to reduce flare due to reflection inside the barrel while realizing a reduction in size in the radial direction.

1 is a perspective view of a lens barrel according to Embodiment 1. FIG. 1 is an exploded perspective view of a lens barrel according to Embodiment 1. FIG. Sectional drawing of the lens-barrel (telephoto state) concerning Embodiment 1 Sectional drawing of the lens-barrel (state where the full length becomes the shortest) concerning Embodiment 1 Sectional view of the lens barrel (wide-angle state) according to Embodiment 1

  Hereinafter, embodiments will be described in detail with reference to the drawings as appropriate. However, more detailed explanation than necessary may be omitted. For example, detailed descriptions of already well-known matters and repeated descriptions for substantially the same configuration may be omitted. This is to avoid the following description from becoming unnecessarily redundant and to facilitate understanding by those skilled in the art.

  The applicant provides the accompanying drawings and the following description in order for those skilled in the art to fully understand the present disclosure, and is not intended to limit the subject matter described in the claims. Absent.

(Embodiment 1)
Hereinafter, Embodiment 1 will be described with reference to FIGS. In the first embodiment, description will be given by taking an interchangeable lens 900 as an example of a lens barrel. The interchangeable lens 900 is used by being attached to a camera body such as a single-lens reflex camera or a mirrorless camera.
(Embodiment 1)
[1. Overall Configuration of Interchangeable Lens 900] (FIGS. 1-2)
The overall configuration of the interchangeable lens 900 will be described with reference to FIGS. 1 and 2. FIG. 1 shows a perspective view of an interchangeable lens 900. FIG. 2 is an exploded perspective view of the interchangeable lens 900.
As shown in FIG. 1, the interchangeable lens 900 includes a focus ring 910, a zoom ring 920, and an attachment index 930. When the interchangeable lens 900 is attached to the camera body, the attachment index 930 is disposed so as to come to the upper part of the normal posture.
As shown in FIG. 2, the interchangeable lens 900 includes a first group unit 100, a second group unit 200, a third group unit 300, a fourth group unit 400, a cam cylinder unit 500, an exterior unit 600, a printed circuit board 700, and a lens mount 800. doing.
The first group unit 100 has three lenses and is provided on the subject side. The first group unit 100 is configured to move relative to the cam barrel unit 500 in the optical axis direction. Specifically, the first group unit 100 is provided with a cam pin. A cam follower is formed in the cam cylinder 501. The cam pins of the first group unit 100 are engaged with the cam followers of the cam cylinder 501. As a result, when the cam cylinder 501 is rotated, the cam pins of the first unit 100 move along the cam follower of the cam cylinder 501 and relatively move in the optical axis direction.
The second group unit 200 includes four lenses and an aperture 221 and is provided closer to the non-subject side than the first group unit 100. The second group unit 200 is configured to move relative to the cam barrel unit 500 in the optical axis direction. Specifically, the second group unit 200 includes a second group holder 210 and a diaphragm OIS unit 220. The aperture OIS unit 220 is fixed to the second group holder 210. The second group holder 210 has one lens, and a cam pin is provided on the outer periphery. Cam pins provided on the second group holder 210 are engaged with cam followers formed on the cam barrel unit 500. Therefore, the second group unit 200 is configured to be movable relative to the cam cylinder unit 500 in the optical axis direction due to the relationship between the cam pin of the second group holder 210 and the cam follower of the cam cylinder 501. The aperture OIS unit 220 includes apertures 221, second and third lenses 223 and an OIS drive unit 224 from the subject side to the non-subject side.
The third group unit 300 has one lens and is disposed on the non-subject side with respect to the second group unit 200. The third group unit 300 is configured to move relative to the cam barrel unit 500 in the optical axis direction. Specifically, the third group unit 300 has a cam pin on the outer periphery. The cam pins of the third group unit 300 are engaged with cam followers formed on the cam cylinder 501. Accordingly, the third group unit 300 is configured to move relative to the cam cylinder unit 500 in relation to the cam pin of the third group unit 300 and the cam follower of the cam cylinder unit 500.
Here, the cam cylinder unit 500 is disposed inside the exterior unit 600. The cam cylinder unit 500 includes a cam cylinder 501 and a rectilinear fixing frame 502. The cam barrel 501 is connected to the zoom ring 920 and is configured to rotate when the zoom ring 920 is rotated. The rectilinear fixing frame 502 is a member supported by the cam cylinder 501 and does not rotate even when the zoom ring 920 is rotated. As a result, the cam barrel 501 is rotated by the rotation of the zoom ring 920. The first group unit 100, the second group unit 200, and the third group unit 300 move relative to the cam cylinder unit 500 by the rotation of the cam cylinder 501. Accordingly, the interchangeable lens 900 can be zoomed (from the telephoto state to the wide-angle state) by changing the distance between the lenses.
The fourth group unit 400 includes one lens and is disposed closer to the non-subject side than the third group unit 300. Fourth group unit 400 is fixed to exterior unit 600. The printed circuit board 700 is fixed to the exterior unit 600. The lens mount 800 is fixed to the exterior unit 600.
[2. Description of optical system of interchangeable lens 900] (FIGS. 3 to 5)
3 to 5 are sectional views of the interchangeable lens 900. FIG. As described above, when the zoom ring 920 is rotated, the total length of the interchangeable lens 900 changes between the telephoto state and the wide-angle state. FIG. 3 shows the telephoto state. FIG. 4 is a diagram showing the shortest overall length between the telephoto state and the wide-angle state. FIG. 5 is a diagram showing a wide-angle state.
The interchangeable lens 900 has a four-group lens configuration. The interchangeable lens 900 has, from the subject side, one negative group (three), two positive groups (four), three negative groups (one), and four positive groups (one).
The interchangeable lens 900 has a diaphragm 221 between the positive two groups. The interchangeable lens 900 includes a focus lens 303 as the negative three groups. Further, the interchangeable lens 900 includes a fourth group lens 401 as the positive fourth group.

  The outer diameter of the fourth group lens 401 is configured to be 2.5 times or more the aperture diameter of the diaphragm 221. This is to reduce the size of the first lens group and the second lens group.

As described above, in the interchangeable lens 900, the outer diameter of the fourth group lens 401 is set to be 2.5 times or more than the aperture diameter of the diaphragm 221. As a result, the light incident on the fourth lens group 401 from the focus lens 303 becomes a spreading light beam. Light rays spreading toward the fourth group lens 401 are highly likely to be reflected by peripheral components, and light reflected by the peripheral components is likely to reach the image sensor, causing flare. In order to reduce the size of the interchangeable lens 900 in the radial direction, it is necessary to design in consideration of the cause of the flare. Note that the telephoto state in FIG. 3 is the state where the occurrence of flare should be most concerned.
[3. Detailed Configuration of Interchangeable Lens 900 (Second Group Unit 200, Third Group Unit 300, Fourth Group Unit 400)] (FIG. 3)
A specific configuration of the interchangeable lens 900 will be described using the telephoto state of FIG. 3 as an example.

The exterior unit 600 has a mount base 601. The mount base 601 is a member that becomes a base of the interchangeable lens 900. A fourth group lens frame 402 is fixed to the mount base 601. In addition, a cam cylinder 501, a focus ring 910, and a zoom ring 920 are attached to the mount base 601 in a rotatable manner.
A fourth group lens 401 is fixed to the fourth group lens frame 402.

  A diaphragm 221 is fixed to the cam cylinder 501 through a second group holder 210. The cam barrel 501 is rotated as the zoom ring 920 rotates. The diaphragm 221 moves at a position as shown in FIGS. 3 to 5 when the cam cylinder 501 is rotated.

A third group holder 301 is coupled to the cam cylinder 501. A focus lens frame 302 having a focus lens 303 and a focus motor unit 304 are attached to the third group holder 301. The cam barrel 501 is rotated as the zoom ring 920 rotates. The third group holder 301 moves at a position as shown in FIGS. 3 to 5 when the cam cylinder 501 is rotated.
That is, as shown in FIG. 3, the positions of the focus lens 303 (including the focus motor unit 304) and the fourth group lens 401 are separated. As a result, the light passing through the focus lens 303 passes near the outer diameter of the fourth group lens 401.

  Here, a part of the focus motor unit 304 is disposed on the optical axis side with respect to the outer diameter of the fourth group lens 401. Specifically, the rotation axis of the focus motor unit 304 is configured to be near the outer diameter end of the fourth group lens 401. This is to reduce the outer diameter of the interchangeable lens 900.

  Further, the focus motor unit 304 includes a motor 304A and a screw 304B. The screw 304B is rotated by the rotation of the magnet in the focus motor unit 304. In the first embodiment, the motor 304A is disposed on the subject side with respect to the screw 304B and on the non-subject side with respect to the aperture. This is to reduce the occurrence of flare due to light incident on the surface of the motor 304A.

  Further, a reflection reducing member 301A (a member formed as a part of the third group holder 301) having a saw shape for reducing reflection is formed on the optical axis side of the motor 304A. In addition, when the surface of the motor 304A is a metal, it is preferable to provide the reflection reducing member 301A.

  Furthermore, the focus motor unit 304 is preferably arranged on the side where the attachment index 930 is provided. This is because when the user shoots in a normal posture, light such as sunlight passes through the second group and the third lens 223 of the second group, and then passes through the side opposite to the attachment index 930 with respect to the optical axis. It will be. On the other hand, the light coming from the ground side passes through the stop 221 and then passes through the attachment index 930 side with respect to the optical axis. That is, the light entering the attachment index 930 side is often darker than the light entering the opposite side. Therefore, the influence of the occurrence of flare is further reduced by arranging the focus motor unit 304 on the attachment index 930 side.

  The focus rack 305 is a member for connecting the screw 304B and the focus lens frame 302.

(Other embodiments)
As described above, the first embodiment has been described as an example of the implementation in the present disclosure. However, the present disclosure is not limited to this, and can also be applied to embodiments in which changes, replacements, additions, omissions, and the like have been made as appropriate. Moreover, it is also possible to combine each component demonstrated in the said Embodiment 1, and it can also be set as a new embodiment.

  As described above, the embodiments considered to be the best mode by the applicant and other embodiments are provided by the accompanying drawings and the detailed description. These are provided to those skilled in the art to illustrate the claimed subject matter by reference to specific embodiments. Therefore, the constituent elements described in the accompanying drawings and the detailed description may include not only the constituent elements essential for solving the problem but also other constituent elements. Therefore, just because those non-essential components are described in the accompanying drawings and detailed description, the non-essential components should not be recognized as essential immediately. Various modifications, replacements, additions, omissions, and the like can be made to the above-described embodiments within the scope of the claims and the equivalent scope thereof.

  The present disclosure can be applied to a lens barrel used in a digital still camera.

900 Interchangeable lens 910 Focus ring 920 Zoom ring 930 Attachment index 100 First group unit 200 Second group unit 210 Second group holder 220 Aperture OIS unit 221 Aperture 223 Second and second lenses 224 in the second group 224 OIS drive unit 300 Third group unit 301 3 Group holder 301A Reflection reduction member 302 Focus lens frame 303 Focus lens 304 Focus motor unit 304A Motor 304B Screw 305 Focus rack 400 Fourth group unit 401 Fourth group lens 402 Fourth group lens frame 500 Cam cylinder unit 501 Cam cylinder 502 Straight fixed frame 600 Exterior Unit 601 Mount base 700 Printed circuit board 800 Lens mount

Claims (4)

An optical system including a first lens, a diaphragm, a second lens, and a third lens from the subject side toward the non-subject side;
A lead portion that guides a holding frame that holds the second lens; a motor that drives the lead portion;
With
A part of the motor is disposed inside the outer diameter of the third lens,
The motor is disposed on the subject side with respect to the lead portion and on the non-subject side with respect to the aperture.
Lens barrel. A member for reducing reflection is disposed on the optical axis side of the optical system of the motor.
The lens barrel according to claim 1. The lens barrel has a mounting index on the outer periphery,
The motor is provided on the attachment index side with respect to the optical axis of the optical system.
The lens barrel according to claim 1. When the lens barrel is provided in a digital still camera, and when the digital still camera is in a normal posture, the motor is disposed on the side opposite to the optical axis of the optical system,
The lens barrel according to claim 1.