Lens apparatus and image pickup apparatus

Abstract

[Problem] To provide a lens device having a reduced size. [Solution] A lens device (100) is provided with: a plurality of lens units comprising a first lens unit (L1), a second lens unit (L2), and a rear lens unit (L3) in this order from the object side to the image side; a first holder (11) for holding the first lens unit; a second holder (12) that holds the second lens unit and is movable together with the second lens unit in the optical axis direction; and a driving unit (20) configured to drive the second holder in the optical axis direction. During zooming from the wide-angle end to the telephoto end, a distance between adjacent lens units of the plurality of lens units changes. In the optical axis direction, a first end (201) of the driving unit closest to the object is located at the same position as a position (P1) of a second end (121) of the second holder closest to the object, or at a position (P2) on the image side of the second end.

Description

Technical Field

[0001] The present invention relates to a lens device and an imaging device. Background Art

[0002] Patent Document 1 discloses a lens device having an optical system composed of five lens units (i.e., a first lens unit, a second lens unit, a third lens unit, a fourth lens unit, and a fifth lens unit in order from the object side to the image side). Patent Document 1 also discloses that the third lens unit is driven by a third unit motor for power zoom, and a focusing motor (voice coil motor) is used to drive the second lens unit for focusing.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2013-83775 Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] However, if the structure disclosed in Patent Document 1 is applied to a lens device that drives the second lens unit for power zoom, the moving stroke of the second lens unit may cause interference of the motor for driving the second lens unit with the first lens unit or the holder for holding the first lens unit. If the motor is placed in a way to avoid such interference, the size of the lens device in the radial direction may increase.

[0008] Therefore, the present invention provides a lens device with a reduced size.

[0009] Solutions to the Problems

[0010] A lens device according to an aspect of the present invention includes: a plurality of lens units composed of a first lens unit, a second lens unit, and a rear lens unit in order from the object side to the image side; a first holder for holding the first lens unit; a second holder for holding the second lens unit and capable of moving together with the second lens unit in the optical axis direction; and a driving unit configured to drive the second holder in the optical axis direction. During zooming from the wide-angle end to the telephoto end, the distance between adjacent lens units among the plurality of lens units changes. In the optical axis direction, the first end of the driving unit closest to the object is located at the same position as the second end of the second holder closest to the object, or at a position on the image side of the second end.

[0011] Other objects and further features of the present invention will be described in the following embodiments.

[0012] Effect of the Invention

[0013] The present invention can provide a lens device having a reduced size. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a cross-sectional view of the lens device in the first embodiment.

[0015] Figure 2 is a cross-sectional view of the lens device in the second embodiment.

[0016] Figure 3 is a cross-sectional view of the lens device in the third embodiment.

[0017] Figure 4 is a schematic view of the imaging device according to each embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0018] Now, with reference to the accompanying drawings, a detailed description of embodiments according to the present invention will be given.

[0019] (First Embodiment)

[0020] Now, with reference to Figure 1 , a description of the lens device 100 according to the first embodiment of the present invention will be given.

[0021] Figure 1 is a cross-sectional view of the lens device 100. In Figure 1 , the left side is the object side, and the right side is the image side. Figure 1 Only the structures directly related to the description of the present embodiment are illustrated, and the structures not directly related to the description of the present embodiment are omitted.

[0022] The lens device 100 has a plurality of lens units (imaging optical system) including a first lens unit L1, a second lens unit L2, and a rear lens unit, which are sequentially arranged from the object side to the image side. An optical image formed by the plurality of lens units is formed on the image plane IP. Figure 1 Only the third lens unit L3 disposed adjacent to the second lens unit L2 on the image side of the second lens unit L2 is illustrated as the rear lens unit, but the present embodiment is not limited to this example. As long as the rear lens unit includes at least the third lens unit L3, the rear lens unit may further include at least one lens unit on the image side of the third lens unit L3. The lens unit may include one or more lenses.

[0023] During zooming from the wide-angle end to the telephoto end, the distance between adjacent lens units among the plurality of lens units changes. In the present embodiment, during zooming, the second lens unit L2 moves by Figure 1The moving stroke MS indicated by the arrow therein moves in the direction along the optical axis OA (optical axis direction). In the present embodiment, the first lens unit L1 does not move during zooming. That is, the total lens length (the length on the optical axis from the lens surface closest to the object to the lens surface closest to the image surface of the plurality of lens units constituting the imaging optical system plus the back focal length) does not change (the total length is fixed). In the present embodiment, the lens device 100 has an aperture stop (iris) SP that moves together with the second lens unit L2, but the present embodiment is not limited to this example.

[0024] The first cage (first holding member) 11 holds the first lens unit L1. The second cage (second holding member) 12 holds the second lens unit L2 and moves in the optical axis direction together with the second lens unit L2. In the radial direction, the second cage 12 is smaller than the first cage 11. The voice coil motor (driving unit) 20 is connected to the second cage 12 and is configured to be able to transmit a driving force to the second cage 12, thereby driving the second cage 12 in the optical axis direction. The lens device 100 can perform electric zooming, and the voice coil motor 20 drives the second cage 12 through control based on a user's operation or a user's instruction.

[0025] The voice coil motor 20 includes a coil 21, a magnet 22, and a yoke 23. The coil 21 is integrated with the second cage 12. The magnet 22 and the yoke 23 are provided in the lens barrel 31 and form a magnetic field to move the coil 21.

[0026] In the lens device 100, in order to drive the second lens unit L2 using the voice coil motor 20, the coil 21, the magnet 22, and the yoke 23 are arranged near the second lens unit L2. Since the magnet 22 and the yoke 23 are large, the magnet 22 and the yoke 23 may interfere (contact or collide) with, for example, the first lens unit L1 or the first cage 11 during zooming. Attempting to retract the voice coil motor 20 in the direction away from the optical axis OA (radial direction) to avoid interference may increase the size of the lens device 100.

[0027] Therefore, in this embodiment, the positional relationship between the second cage 12 and the voice coil motor 20 in the optical axis direction is set to avoid interference between the first cage 11 and the voice coil motor 20. That is to say, in this embodiment, the front end 201 of the voice coil motor 20 (the first end of the voice coil motor 20 closest to the object) is arranged at the position P2 on the image side of the position P1 of the front end 121 of the second cage 12 (the second end of the second cage 12 closest to the object). However, this embodiment is not limited to this example, and the front end 201 of the voice coil motor 20 may be located at the same position as the position P1 of the front end 121 of the second cage 12 in the optical axis direction (P1 = P2). In other words, on the object side of the front end 121 of the second cage 12, the front end 201 of the voice coil motor 20 does not protrude.

[0028] Due to this structure, even when the second lens unit L2 moves in the optical axis direction during zooming, it is possible to reduce the size of the lens device 100 while avoiding interference between the voice coil motor 20 and the first lens unit L1 or the first cage 11. In this embodiment, the voice coil motor 20 is placed outside the second cage 12, and the size of the lens device 100 in the radial direction (i.e., in the direction orthogonal to the optical axis OA (the direction orthogonal to the optical axis)) can be reduced.

[0029] In this embodiment, the length of the yoke 23 in the radial direction (the direction perpendicular to the optical axis direction) from the outermost end to the innermost end is shorter than the length of the yoke 23 in the optical axis direction from the end closest to the object to the end closest to the image plane. This structure can reduce the size of the lens device 100 in the radial direction.

[0030] (Second Embodiment)

[0031] Now referring to Figure 2 , a description of the lens device 100a according to the second embodiment of the present invention will be given. Figure 2 is a cross-sectional view of the lens device 100a. In Figure 2 , the left side is the object side, and the right side is the image side. As Figure 1 such, Figure 2 only the structures directly related to the description of this embodiment are illustrated, and the structures not directly related to the description of this embodiment are omitted.

[0032] The lens device 100a according to this embodiment is different from the lens device 100 according to the first embodiment in that the lens device 100a includes a voice coil motor 20a instead of the voice coil motor 20. The other structures and operations of the lens device 100a are similar to those of the lens device 100, and thus their description will be omitted.

[0033] The voice coil motor 20a includes a coil 21a, a magnet 22a, and a yoke 23a, and is disposed behind (image side) the second holder 12 for holding the second lens unit L2. That is, when viewed from the object side toward the image side in the optical axis direction (when the lens device 100a is viewed from the front), at least a part of each of the coil 21a, the magnet 22a, and the yoke 23a of the voice coil motor 20a overlaps at least a part of the second holder 12. In the present embodiment, the front end 201a of the voice coil motor 20a (the first end of the voice coil motor 20a closest to the object) is disposed at a position on the image side of the front end 121 of the second holder 12 (the second end of the second holder 12 closest to the object).

[0034] Due to this structure, even when the second lens unit L2 moves in the optical axis direction during zooming, the size of the lens device 100a can be reduced while preventing the voice coil motor 20a from interfering with the first lens unit L1 or the first holder 11. In the present embodiment, the voice coil motor 20a is placed on the image side of the second holder 12, and the size of the lens device 100a in the optical axis direction can be reduced.

[0035] In the present embodiment, when viewed from the object side toward the image side in the optical axis direction, at least a part of the voice coil motor 20a overlaps at least a part of the first holder 11. This structure can reduce the size of the lens device 100a in the radial direction.

[0036] (Third Embodiment)

[0037] Now referring to Figure 3 , a description of the lens device 100b according to the third embodiment of the present invention will be given. Figure 3 is a cross-sectional view of the lens device 100b. In Figure 3 , the left side is the object side, and the right side is the image side. As Figure 1 such, Figure 3 only the structures directly related to the description of the present embodiment are illustrated, and the structures not directly related to the description of the present embodiment are omitted.

[0038] The lens device 100b according to the present embodiment is different from the lens device 100 of the first embodiment having only one voice coil motor in that the lens device 100b includes a first voice coil motor (first driving member) 20b and a second voice coil motor (second driving member) 20c as driving units. However, the present embodiment is not limited to a structure having two voice coil motors, and can also be applied to a structure having three or more than three voice coil motors. In the present embodiment, the two voice coil motors are common motors, but the present embodiment is not limited to this example, and can also be applied to two motors having different characteristics and sizes. The other structures and operations of the lens device 100b are similar to those of the lens device 100, and thus their descriptions will be omitted.

[0039] The first voice coil motor 20b includes a coil 21b, a magnet 22b, and a yoke 23b, and is disposed outside the second holder 12 for holding the second lens unit L2. Similarly, the second voice coil motor 20c includes a coil 21c, a magnet 22c, and a yoke 23c, and is disposed outside the second holder 12 for holding the second lens unit L2.

[0040] In addition, the front end 201b of the first voice coil motor 20b (the first end (third end) of the first voice coil motor 20b closest to the object) is placed at a position on the image side of the position of the front end 121 of the second holder 12 (the second end of the second holder 12 closest to the object). Similarly, the front end 201c of the second voice coil motor 20c (the first end (fourth end) of the second voice coil motor 20c closest to the object) is disposed at a position on the image side of the position of the front end 121 of the second holder 12.

[0041] In the present embodiment, in the optical axis direction, the position P3 of the third end (front end 201b) of the first voice coil motor 20b closest to the object is different from the position P4 of the fourth end (front end 202c) of the second voice coil motor 20c closest to the object. That is, the positions P3 and P4 do not coincide with each other in the optical axis direction.

[0042] In the case where the second lens unit L2 is heavy or the like, instead of using a single voice coil motor, multiple voice coil motors can be used to drive the second holder 12. When multiple voice coil motors are arranged, the possibility of interfering with other components on the object side and the image side of the second holder 12 and other components outside the second holder 12 (in the radial direction) is further increased. Shifting the positions of the multiple voice coil motors in the optical axis direction as in the present embodiment can improve the degree of freedom of component placement.

[0043] In the present embodiment, the first voice coil motor 20b and the second voice coil motor 20c are placed at different positions in the optical axis direction, so that the balance of the Lorentz force is shifted. Therefore, in the case where the second cage 12 is asymmetric in shape and thus the center of gravity of the second cage 12 is not on the optical axis OA (center), shifting the positions of the two voice coil motors can provide well-balanced driving.

[0044] Now referring to Figure 4 , a description will be given of an imaging device 200 equipped with a lens device 100 (100a, 100b) according to each embodiment. Figure 4 is a schematic diagram of the imaging device 200.

[0045] In Figure 4 , reference numeral 50 denotes a camera body, and reference numeral 11 denotes a lens device 100 (100a, 100b) according to any one of the first to third embodiments. Reference numeral 60 denotes an image sensor (photoelectric conversion element) such as a CMOS sensor or a CCD sensor, which is built into the camera body 50 and receives and photoelectrically converts an optical image formed by the optical system in the lens device 100. The camera body 50 may be a so-called single-lens reflex camera having a quick-return mirror, or a so-called mirrorless camera without a quick-return mirror. The lens device according to each embodiment is applicable not only to a digital still camera but also to other imaging devices such as a video camera.

[0046] Each embodiment can provide a lens device and an imaging device both having a reduced size.

[0047] The above-described embodiments are merely representative examples, and various modifications and changes can be made to these embodiments when implementing the present invention.

Claims

1. A lens device, comprising: a plurality of lens units, which are composed of a first lens unit, a second lens unit, and a rear lens unit in order from the object side to the image side; a first holder for holding the first lens unit; a second holder for holding the second lens unit and capable of moving together with the second lens unit in the optical axis direction; and a driving unit configured to drive the second holder in the optical axis direction, characterized in that during zooming from the wide-angle end to the telephoto end, the distance between adjacent lens units among the plurality of lens units changes, wherein, in the optical axis direction, the first end of the driving unit closest to the object is located at the same position as the second end of the second holder closest to the object, or at a position on the image side of the second end.

2. The lens device according to claim 1, wherein, The driving unit includes a voice coil motor and includes a coil provided in the second holder, and a magnet and a yoke for forming a magnetic field to move the coil.

3. The lens device according to claim 2, wherein When viewed from the object side to the image side in the optical axis direction, at least a part of each of the coil, the magnet, and the yoke of the driving unit overlaps at least a part of the second holder.

4. The lens device according to any one of claims 1 to 3, characterized in that, When viewed from the object side to the image side in the optical axis direction, at least a part of the driving unit overlaps at least a part of the first holder.

5. The lens device according to claim 1 or 2, characterized in that, The driving unit includes a first driving member and a second driving member, and wherein, in the optical axis direction, the position of the third end of the first driving member closest to the object is different from the position of the fourth end of the second driving member closest to the object.

6. The lens device according to any one of claims 1 to 5, characterized in that The first lens unit does not move during zooming.

7. The lens device according to any one of claims 1 to 6, characterized in that, The rear lens unit includes at least a third lens unit disposed on the image side of the second lens unit.

8. The lens device according to claim 2, characterized in that, The length of the yoke in the radial direction from the outermost end to the innermost end is shorter than the length of the yoke in the optical axis direction from the end closest to the object to the end closest to the image plane, and the radial direction is a direction perpendicular to the optical axis direction.

9. The lens device according to any one of claims 1 to 8, characterized in that, In the radial direction, the second holder is smaller than the first holder.

10. An imaging device, comprising the lens device according to any one of claims 1 to 9, and an image sensor.

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