JP2007218954A - Lens barrel and imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a lens barrel of which the thickness in optical axis direction in a collapse state is reduced. <P>SOLUTION: The collapsible lens barrel has: a variable magnitude imaging optical system composed of a plurality of lens groups; a cam cylinder which moves at least the two lens groups; and a front barrel moved by the cam cylinder. The front barrel is provided with an actuator which moves the lens group which is located nearest to an imaging object with respect to the front barrel and the actuator moves the lens group which is located nearest to the imaging object with respect to the front barrel when the magnitude is varied. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a lens barrel configured to be retractable and an imaging device including the lens barrel.

  Conventionally, a so-called collapsible lens that is housed in a thin shape by reducing the distance between lens groups that are optical elements constituting a variable magnification optical system in order to make it convenient to carry when not in use for photographing. A camera using a lens barrel is known.

As the retractable lens barrel, the last third lens group of the three-group configuration is used as a focusing lens, and a drive motor for driving the focusing lens is disposed in the lens barrel, and is closer to the subject side than the third lens group. A lens that performs zooming by moving a first lens group and a second lens group that are positioned using a cam cylinder is known (for example, see Patent Document 1).
JP 2003-287670 A

  FIG. 7 is a schematic cross-sectional view showing an example of a conventional retractable lens barrel. FIG. 4A shows the retracted state, FIG. 3B shows the wide-angle end, and FIG. 4C shows the telephoto end. The configuration and operation outline of a conventional retractable lens barrel will be described with reference to FIG.

  In the figure, 11 is a fixed cylinder, 14 is a cam cylinder, and 15 is a front cylinder. The first lens group 1 located closest to the subject is integrally fixed to the front cylinder 15. Two types of cam grooves are formed in the cam cylinder 14, and cam pins formed in the second lens group frame 7 that holds the cam pins formed in the front cylinder 15 and the second lens group 2 are formed in the cam grooves. Are engaged with each other. The third lens group 3 located closest to the image plane side can be moved by a motor (not shown) so that it can move independently.

  From the retracted state shown in FIG. 5A to the wide-angle end state shown in FIG. 4B, the cam cylinder 14 moves in the direction of the optical axis O while rotating, so that the front cylinder 15 or the first lens group 1 is moved. The second lens group frame 7, that is, the second lens group 2 is moved to the subject side by a predetermined amount.

  Also, from the wide-angle end state shown in FIG. 4B to the telephoto end state shown in FIG. 3C, the cam cylinder 14 is further rotated to make the front cylinder 15, that is, the first lens group 1 and the second lens group. This is done by moving the lens frame 7, that is, the second lens group 2 to change the interval.

  The third lens group 3 moves to a predetermined position corresponding to each focal length, and focusing is performed by moving further from that position.

In such a lens barrel configuration, as shown in the figure, the maximum length of the lens barrel at the wide-angle end is Lw, the length of the lens barrel in the retracted optical axis direction is Lt, and the front The length of the cylinder 15 in the optical axis direction is Lm, the fitting length of the fixed cylinder 11 and the cam cylinder 14 at the wide-angle end, which is the maximum length, and the fitting length of the cam cylinder 14 and the front cylinder 15 are d, respectively.
Lw = 2Lt + Lm-2d
When Lm is (Lt-d), the length Lt of the lens barrel in the optical axis direction when retracted is
Lt = (Lw + 3d) / 3
It becomes. Note that b is a thickness required for a mechanism portion such as a lens barrier.

  That is, in the structure of the conventional lens barrel, the length (thickness) Lt in the optical axis direction when retracted is the total length of the lens barrel at the maximum length when the required length d is secured to the required length. It is determined by Lw, and it has been difficult to further reduce the thickness of the lens barrel in the optical axis direction when retracted.

  In view of the above problems, an object of the present invention is to obtain a lens barrel in which the thickness of the lens barrel in the optical axis direction when retracted is made thinner. By providing this lens barrel, a thinner imaging device is obtained. It is for the purpose.

  The above object is achieved by the invention described below.

  1. In the lens barrel configured to be retractable, the front barrel includes an imaging optical system configured by a plurality of lens groups and capable of zooming, a cam barrel, and a front barrel moved by the cam barrel. Includes an actuator that moves the lens unit closest to the subject relative to the front cylinder, and the lens mirror moves the lens group closest to the subject relative to the front cylinder by the actuator during zooming. Torso.

  2. 2. The lens barrel according to claim 1, wherein the lens group closest to the subject moves to the subject side with respect to the front tube at least at a wide-angle end.

  3. The front cylinder has a lens barrier, and a part of the lens group closest to the subject moves to a position protruding toward the subject side from the image side surface of the lens barrier at least at the wide-angle end. The lens barrel according to 1 or 2.

  4). Focusing is performed by moving at least one lens unit other than the lens unit closest to the subject at least at the wide-angle end of the imaging optical system, and performing focusing by moving the lens unit closest to the subject at least at the telephoto end. The lens barrel according to any one of 1 to 3, wherein

  5. At least at the telephoto end of the imaging optical system, focusing is performed by moving the lens group closest to the subject from infinity to the first subject distance, and the first subject distance is closer to the first subject distance than the first subject distance. At a subject distance of 2, the focusing is performed by moving the lens unit closest to the subject side in a state of moving to the subject side and moving at least one lens unit other than the lens unit closest to the subject side. The lens barrel according to any one of 1 to 4.

  6). In the lens barrel configured to be retractable, the front barrel includes an imaging optical system configured by a plurality of lens groups and capable of zooming, a cam barrel, and a front barrel moved by the cam barrel. Includes an actuator that moves the lens group closest to the subject relative to the front cylinder, stops the lens group closest to the subject toward the subject side relative to the front cylinder, and stops the lens group closest to the subject. A lens barrel, wherein focusing is performed by moving at least one lens group other than the lens barrel.

  7). An imaging apparatus comprising: an imaging element that photoelectrically converts a subject image formed by an imaging optical system; and the lens barrel according to any one of 1 to 6.

  According to the present invention, even when the same optical system is used, it is possible to obtain a lens barrel that can be retracted in a thinner state than in the past. By providing this lens barrel, a thinner thickness can be obtained. An imaging device can be obtained.

  Hereinafter, the present invention will be described in detail with reference to embodiments, but the present invention is not limited thereto.

  FIG. 1 is an external view showing a camera which is an example of an imaging apparatus equipped with a lens barrel 80 according to the present embodiment. 1A is a perspective view of the front side of the camera, and FIG. 1B is a perspective view of the back side of the camera.

  In FIG. 1A, reference numeral 80 denotes a retractable lens barrel according to the present invention. 82 is a finder window, 83 is a release button, 84 is a flash light emitting unit, 86 is a microphone, 87 is a strap attaching unit, and 88 is a USB terminal. When not photographing, the lens barrel 80 is retracted so that the lens barrier provided in the lens barrel 80 covers the lens surface closest to the subject.

  In FIG. 1B, 91 is a viewfinder eyepiece, 92 is a red and green display lamp, and displays AF and AE information to the photographer by light emission or blinking when the release button 83 is pressed. It is. A zoom button 93 is a button for zooming up and down. Reference numeral 94 denotes a speaker, which reproduces sound recorded by the microphone 86, emits a release sound, and the like. Reference numeral 95 denotes a menu / set button, reference numeral 96 denotes a selection button, which is a four-way switch, and reference numeral 100 denotes an image or other character information on the monitor LCD. The menu / set button 95 has a function of displaying various menus on the monitor LCD 100, selecting with the selection button 96, and confirming with the menu / set button 95. Reference numeral 97 denotes a reproduction button, which is a button for reproducing a photographed image. A display button 98 is a button for selecting display or deletion of an image or other character information displayed on the monitor LCD 100. An erasure button 99 is a button for erasing the recorded image. 101 is a tripod hole, and 102 is a battery / card cover. The battery / card cover 102 is loaded with a battery for supplying power to the camera and a card-type removable memory for recording captured images.

  FIG. 2 is a schematic cross-sectional view showing a state in which the lens barrel 80 according to the present embodiment is retracted.

  In the figure, reference numeral 1 denotes a first lens group having a negative power, 2 denotes a second lens group having a positive power, and 3 denotes a third lens group having a positive power, which are included in the lens barrel 80 shown in this example. The obtained photographing lens has a three-group configuration. Reference numeral 4 denotes an OLPF (optical low-pass filter), which removes high-frequency components of subject light in order to prevent false colors and moire. Reference numeral 5 denotes an image sensor that photoelectrically converts imaged subject light, such as a CCD (Charge Coupled Device) type image sensor or a CMOS (Complementary Metal-Oxide Semiconductor) type image sensor.

  The first lens group 1 is held by a first lens group lens frame 6, the second lens group 2 is held by a second lens group lens frame 7, and the third lens group 3 is held by a third lens group lens frame 8. ing.

  Reference numeral 11 denotes a fixed barrel which is integrally fixed to a camera body (not shown) and has a cam groove on the inner periphery. A base plate 12 is fixed to the rear portion of the fixed drum 11. The OLPF 4 and the image sensor 5 are attached to the base plate 12 in this order. The image sensor 5 is electrically connected to the printed circuit board 13.

  Reference numeral 14 denotes a cam cylinder. A cam pin that engages with a cam groove of the fixed cylinder 11 is formed on the outer periphery, and a partial gear 14b is formed on a part of the rear part. A cam groove is formed in the inner periphery of the cam cylinder 14.

  Further, the cam cylinder 14 is assembled such that the rectilinear movement member 17 and the rectilinear guide plate 18 can move as the cam cylinder 14 moves in the optical axis direction. A drive gear 21 meshed with the partial gear 14b is pivotally supported on the linear guide plate 18. The drive gear 21 meshes with the long gear 22. The long gear 22 is driven by a motor and a reduction gear train (not shown).

  Reference numeral 15 denotes a front cylinder, and a cam pin is erected on the outer periphery of the front cylinder 15 and is engaged with a cam groove of the cam cylinder 14.

  The front cylinder 15 includes an actuator (not shown) that holds the first lens group 1 that is the lens group closest to the subject and moves the first lens group frame 6 relative to the front cylinder 15. Thus, the first lens group 1 can be moved relative to the front cylinder 15.

  The rectilinear guide plate 18 comes into contact with and slides on an annular surface of the cam cylinder 14 on the image sensor 5 side. Further, the rectilinear movement member 17 is formed with a rectilinear guide portion 17t that engages with the front cylinder 15 and the second lens group lens frame 7 and guides the front cylinder 15 and the second lens group lens frame 7 in a straight line. Reference numeral 33 denotes an aperture shutter unit, which is fixed to the second lens group frame 7.

  41 is a stepping motor to which a feed screw 42 is connected. A rotation-controlled nut 43 is screwed onto the feed screw 42, and the arm portion of the third lens group frame 8 is pressed against the nut 43 by a spring 44. Accordingly, when the feed screw 42 is rotated by the stepping motor 41, the nut 43 moves in the optical axis O direction, and accordingly, the third lens group lens frame 8 can move in the optical axis O direction. .

  Reference numeral 51 denotes a lens barrier that covers the front of the first lens group 1 in the retracted state and is opened in the photographing state so that photographing is possible. This barrier is not shown, but when the lens barrel is retracted, the barrier is engaged and closed, and when the lens group is extended, the barrier is disengaged from the straight guide 17t and an urging force (not shown) is applied. It is opened by the member.

  FIG. 3 is a perspective view showing an example of a mechanism for moving the first lens group 1 held inside the front cylinder 15 relative to the front cylinder 15. In addition, in order to avoid duplication of description in the following drawings, the same reference numerals are given to the same functional members.

  As shown in the figure, guide shafts 31 and 32 are implanted in the front cylinder 15 substantially parallel to the optical axis O. The guide shafts 31 and 32 are fitted by a flange portion formed on the first lens group frame 6 that holds the first lens group 1. Further, a male screw member 24 is screwed into the flange portion of the first lens group lens frame 6, and a stepping motor 23 which is an actuator for rotating the male screw member 24 is fixed to the front cylinder 15.

  Thereby, the first lens group lens frame 6 screwed by the flange portion is guided by the guide shafts 31 and 32 by rotating the male screw member 24 by driving the stepping motor 23, and the optical axis with respect to the front tube 15. It is relatively movable in the O direction. Further, a tongue portion 6g is formed on the flange portion of the first lens group frame 6, and a photo interrupter 25 is fixed to the front tube 15 in the moving direction of the tongue portion 6g. By passing the tongue-like portion 6g through the light projecting / receiving portion of the photo interrupter 25 and controlling the amount of rotation of the stepping motor 23 based on this position, the relative position of the first lens group lens barrel 6 with respect to the front tube 15 can be determined. It comes to control.

  FIG. 4 is a schematic cross-sectional view showing a state of the lens barrel 80 according to the present embodiment at the wide-angle end. The retraction from the retracted state to the wide-angle end state shown in the figure is performed as follows.

  A motor (not shown) is driven, and the cam cylinder 14 is rotated by the long gear 22 and the drive gear 21. As a result, the cam cylinder 14 is guided to the cam groove 11a formed in the fixed cylinder 11 and is fed to the subject side, before the cam pin 16 engaged with the cam groove 14c formed on the inner periphery of the cam cylinder 14 is fixed. The second lens group frame 7 engaged with a cam groove (not shown) formed in the cylinder 15 and the cam cylinder 14 is guided in a straight line by a straight guide part 17t and drawn out in the direction of the subject. It becomes a state. At this time, the rectilinear movement member 17 and the rectilinear guide plate 18 move linearly with the cam cylinder 14. Next, the stepping motor 41 is driven to move the third lens group frame 8 to a predetermined wide-angle end position on the subject side.

  Further, in the lens barrel according to the present embodiment, the stepping motor 23 shown in FIG. 3 is driven to move the first lens group frame 6, that is, the first lens group 1 to the subject side with respect to the front tube 15. As shown in the drawing, the object-side surface of the first lens group 1 is extended to a position protruding toward the object side from the image-side surface of the lens barrier 51, and the first lens group 1 and the second lens group 2 are at the wide-angle end. It becomes the position.

  At the wide-angle end, focusing is performed by driving the stepping motor 41 to move the third lens group 3 in the optical axis direction.

  FIG. 5 is a schematic cross-sectional view showing a state of the lens barrel 80 according to the present embodiment at the telephoto end. The zooming from the wide-angle end state to the telephoto end state shown in the figure is performed as follows.

  A motor (not shown) is driven, and the cam cylinder 14 is rotated by the long gear 22 and the drive gear 21. Between the wide-angle end and the telephoto end, the cam groove 11a formed in the fixed cylinder 11 is formed so as not to be inclined, and the cam cylinder 14 only rotates. The cam groove 14c formed on the inner periphery of the cam cylinder 14 is also formed so as not to be inclined, and the front cylinder 15 to which the engaging cam pin 16 is fixed is also prevented from moving.

  At this time, the stepping motor 23 is driven, and the first lens group frame 6, that is, the first lens group 1 is moved toward the image plane side with respect to the front cylinder 15 and is retracted. Moves to a predetermined position at the telephoto end.

  On the other hand, the second lens group frame 7 engaged with a cam groove (not shown) formed in the cam cylinder 14 is guided in a straight line by a straight guide part 17t, and is fed out in the direction of the subject, so that a predetermined telephoto end as shown in FIG. Move to the position. At this time, the rectilinear movement member 17 and the rectilinear guide plate 18 move linearly with the cam cylinder 14. Next, the stepping motor 41 is driven to move the third lens group frame 8 to a predetermined telephoto end position.

  Regarding focusing at the telephoto end, when the subject distance is within a predetermined distance from infinity, focusing is performed by driving the stepping motor 23 to move the first lens group 1 toward the subject side. . Further, in a subject distance range close to a predetermined distance, the stepping motor 41 is driven to stop the third lens group 3 on the optical axis while stopped at the subject side end position of the movable range of the first lens group 1. Focusing is performed by moving in the direction.

  The focal length at which the focusing at the wide-angle end and the focusing at the telephoto end are switched is set to be switched at an intermediate focal length according to the specification.

  4 and 5, the stepping motor 23 is driven from the extended state at the time of photographing shown in FIG. 2 to the retracted state shown in FIG. 2 to stop the first lens group 1 at a predetermined position where it does not interfere with the barrier 51. 41 is driven to move the third lens group 3 to the position just before the OLPF 4, and then a motor (not shown) is driven in the opposite direction to that when it is extended, and the cam cylinder 14 is rotated reversely by the long gear 22 and the drive gear 21. Done in

  FIG. 6 is a movement diagram showing the positional changes of the first lens group 1 to the third lens group 3 and the front tube 15.

  As shown in the figure, in the movement from the retracted state to the wide-angle end, which is the imaging region, the front cylinder 15 and the first lens group 1 are moved together by the cam cylinder 14, and after reaching the wide-angle end, the stepping motor 23, the first lens group 1 is moved in the subject direction with respect to the front tube 15 (shown by A in the figure). The front tube 15 does not move between the wide-angle end and the telephoto end, which are the photographing regions, and the first lens group 1 is moved with respect to the front tube 15 by the stepping motor 23, so that a predetermined position for each intermediate focal length is obtained. The first lens group 1 is moved to (indicated by B in the drawing).

  On the other hand, the second lens group 2 is moved to a predetermined position with respect to each focal length by the cam cylinder 14. The third lens group 3 is independently moved to a predetermined position with respect to each focal length by a stepping motor 41.

  The above is the configuration and operation of the lens barrel according to the present embodiment.

  As described above, the lens barrel 80 of the present embodiment includes the actuator that enables the first lens group 1 in the front tube 15 to move with respect to the front tube 15, and with respect to the fixed barrel 11 at the wide-angle end. After the cam cylinder 14 and the front cylinder 15 are extended to the maximum while securing a predetermined fitting length, the first lens group 1 is further extended toward the subject with respect to the front cylinder 15, whereby the front cylinder 15 Compared to the configuration in which the first lens group 1 is fixed and moved to the maximum extension position, the total length (Lw) of the lens barrel at the maximum extension can be shortened, and thereby the thickness (Lt) at the time of retracting can be reduced. A thinner lens barrel can be obtained.

  More specifically, for example, when the first lens group 1 is extended about 3 mm toward the subject with respect to the front tube 15, Lw is shortened by about 3 mm compared to the total length Lw of the conventional lens barrel. Thus, the thickness when retracted can be reduced by about 1 mm.

  Further, when telephoto, the first lens group 1 is moved to the image plane side with respect to the front cylinder 15, so that it is not necessary to move the front cylinder 15 itself to the image plane side. There is also an effect that the first lens group 1 and the second lens group 2 can be sufficiently brought close to each other in a state where the engaging portion of the two-lens group lens frame 7 with the cam cylinder 14 is separated.

  Further, the movement in the optical axis direction related to the zooming of the first lens group 1 is formed in the cam cylinder 14 by moving the first lens group 1 relative to the front cylinder 15 with the front cylinder 15 stopped. The cam shape can be made simple, and the cost of the mold can be reduced.

  Further, focusing is performed by moving the third lens group 3 other than the first lens group 1 at the wide-angle end, and focusing is performed by moving the first lens group 1 at the telephoto end. Optimal focusing can be performed for each focal length of the three-group zoom configuration, and changes in imaging performance due to lens position changes during focusing can be suppressed.

  Further, focusing is performed by moving the first lens group 1 from infinity to a predetermined subject distance at the telephoto end, and when the subject distance is closer than the predetermined subject distance, the first lens group 1 closest to the subject is moved to the subject side. It is preferable to perform focusing by moving the third lens group 3 in a state where it is moved to the position of the zoom lens. By doing so, it is possible to perform macro photography up to a closer distance on the telephoto side with high magnification. Thus, a lens barrel with improved close-up capability can be obtained.

  Further, in the lens barrel according to the present embodiment, the first lens group is described as being moved with respect to the front tube at the time of zooming. However, when the lens barrel is in the wide-angle end state, the first lens is used. The group is stopped with the front lens barrel moved toward the subject, and the third lens unit is moved to perform focusing. In the region from the wide-angle end to the telephoto end, the first lens unit is moved to the subject side with respect to the front tube. The front cylinder may be moved by the rotation of the cam cylinder while it is stopped in the state of being moved to the position. In this case, the first lens group is moved to the maximum extension position by extending the front cylinder. Compared with the configuration, the total length (Lw) of the lens barrel portion at the time of maximum extension can be shortened, whereby a lens barrel having a thinner thickness (Lt) at the time of retraction can be obtained.

  Although the lens barrel having the three-group structure has been described, the present invention is not limited to this, and the present invention can be applied to a two-group structure or a structure having four or more groups. In addition, the movement mechanism in the front cylinder of the first lens group has been described by using an example using a motor and a lead screw. However, other movement mechanisms using a piezoelectric element, for example, may be used.

It is an external view which shows the camera which is an example of the imaging device carrying the lens barrel which concerns on this Embodiment. It is a schematic sectional drawing which shows the state at the time of retraction of the lens barrel which concerns on this Embodiment. It is a perspective view showing an example of a mechanism for moving the first lens group held inside the front cylinder relative to the front cylinder. It is a schematic sectional drawing which shows the state at the time of the wide angle end of the lens barrel which concerns on this Embodiment. It is a schematic sectional drawing which shows the state at the time of a telephoto end of the lens barrel which concerns on this Embodiment. It is a movement diagram which shows the position change of a 1st lens group-a 3rd lens group, and a front cylinder. It is a schematic cross section showing an example of a conventional retractable lens barrel.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st lens group 2 2nd lens group 3 3rd lens group 4 OLPF (optical low pass filter)
DESCRIPTION OF SYMBOLS 5 Image pick-up element 6 1st lens group lens frame 7 2nd lens group lens frame 8 3rd lens group lens frame 11 Fixed cylinder 12 Base plate 14 Cam cylinder 15 Front cylinder 21 Drive gear 22 Long gear 23 Stepping motor 31, 32 Guide shaft 41 Stepping motor 51 Lens barrier 80 Lens barrel

Claims (7)

In a lens barrel configured to be retractable, including an imaging optical system configured by a plurality of lens groups capable of zooming, a cam cylinder, and a front cylinder moved by the cam cylinder,
The front cylinder includes an actuator that moves the lens group closest to the subject relative to the front cylinder, and the actuator moves the lens group closest to the subject relative to the front cylinder at the time of zooming. Lens barrel to be used. 2. The lens barrel according to claim 1, wherein the lens group closest to the subject moves to the subject side with respect to the front tube at least at a wide-angle end. The front cylinder has a lens barrier, and a part of the lens group closest to the subject moves to a position protruding toward the subject side from the image side surface of the lens barrier at least at the wide-angle end. The lens barrel according to claim 1 or 2. Focusing is performed by moving at least one lens unit other than the lens unit closest to the subject at least at the wide-angle end of the imaging optical system, and performing focusing by moving the lens unit closest to the subject at least at the telephoto end. The lens barrel according to any one of claims 1 to 3. At least at the telephoto end of the imaging optical system, focusing is performed by moving the lens group closest to the subject from infinity to the first subject distance, and the first subject distance is closer to the first subject distance than the first subject distance. At a subject distance of 2, the focusing is performed by moving the lens unit closest to the subject side in a state of moving to the subject side and moving at least one lens unit other than the lens unit closest to the subject side. The lens barrel according to any one of claims 1 to 4. In a lens barrel configured to be retractable, including an imaging optical system configured by a plurality of lens groups capable of zooming, a cam cylinder, and a front cylinder moved by the cam cylinder,
The front cylinder includes an actuator that moves the lens group closest to the subject relative to the front cylinder, stops the lens group closest to the subject toward the subject side with respect to the front cylinder, A lens barrel characterized in that focusing is performed by moving at least one lens group other than the first lens group. An imaging apparatus comprising: an imaging element that performs photoelectric conversion on a subject image formed by an imaging optical system; and the lens barrel according to claim 1.

Images