JP2014056142A - Focus lens unit, lens barrel, and imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the tilt of a lens caused by the backlash of a fixed barrel and a cam barrel, with a compact configuration.SOLUTION: A lens barrel comprises: a fixed barrel 1; a cam barrel 2 configured to be rotatable with respect to the fixed barrel; an output gear 7b rotating the cam barrel around the optical axis of a lens 3a; and an energizing member 10 energizing the cam barrel in a direction orthogonal to the optical axis. The direction where the output gear 7b goes to a point for applying a drive force to the cam barrel from the center of the lens is different from the direction where the spring member 10 goes to a point for applying an elastic force to the cam barrel from the center of the lens, when viewed from an optical axis direction.

Description

  The present invention relates to a focus lens unit, a lens barrel, and an imaging device.

  In a lens barrel, it is necessary to improve the optical performance and focusing accuracy by preventing the tilting of various movable lenses such as a focus lens. In recent years, so-called live view display and moving image shooting for confirming a photographed image on a liquid crystal monitor on the back have become widespread, and the required accuracy for image shake has become strict, and prevention of the focus lens from falling has become an important issue. .

  Patent Document 1 discloses a lens barrel having a rotation output member that rotates a cam cylinder relative to a fixed cylinder on the outer peripheral surface of the cam cylinder to prevent the focus lens from collapsing due to backlash between the fixed cylinder and the cam cylinder. A spring is provided. In Patent Document 1, as viewed from the optical axis direction, the direction from the lens center toward the rotation output member is the same as the direction from the lens center toward the point where the leaf spring applies elastic force to the rotation output member.

JP 2000-266981 A

  However, in Patent Document 1, since the leaf spring and the rotation output member overlap in the radial direction from the lens center, the cam cylinder easily moves relative to the fixed cylinder by the driving force when the rotation output member drives the cam cylinder. Also, the lens barrel tends to be large.

  It is an exemplary object of the present invention to provide a focus lens unit, a lens barrel, and an imaging device that can reduce the tilt of a lens due to backlash between a fixed cylinder and a cam cylinder with a small configuration.

  The lens barrel of the present invention includes a fixed barrel, a cam barrel that engages with the fixed barrel, a moving barrel that holds the lens and moves linearly in conjunction with the rotation of the cam barrel, and the fixed barrel. A driving means for rotating the cam cylinder around the optical axis of the lens; and an elastic member for urging the cam cylinder in a direction perpendicular to the optical axis. The direction from the center toward the point where the driving means applies a driving force to the cam cylinder is different from the direction from the center of the lens toward the point where the elastic member applies an elastic force to the cam cylinder.

  According to the present invention, it is possible to provide a focus lens unit, a lens barrel, and an imaging apparatus that can reduce the tilting of the lens due to backlash between the fixed cylinder and the cam cylinder with a small configuration.

It is a figure of the lens-barrel of this invention. Example 1 It is another figure of the lens-barrel shown in FIG. Example 1 It is a figure for demonstrating the problem when there is no spring member shown in FIG. Example 1 FIG. 3 is a partially enlarged plan view of a lens barrel for explaining attachment of a spring member shown in FIGS. 1 and 2. Example 1 It is a figure of the modification of the lens-barrel shown in FIG. Example 1 It is a figure of the lens-barrel of this invention. (Example 2)

  Hereinafter, a lens barrel according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. The lens barrel is attached to a camera body (imaging device) (not shown). The imaging device of the present invention is a single-lens reflex digital camera or mirrorless camera that includes a lens barrel and a camera body to which the lens barrel is detachably mounted. However, the present invention is a lens-integrated imaging device. May be. The imaging device includes a digital camera, a digital video camera, and the like. The lens barrel houses an imaging optical system that forms an optical image of an object. That is, the lens barrel holds the lens. The imaging apparatus includes an imaging element that photoelectrically converts an optical image formed by the imaging optical system.

  The imaging optical system includes a fixed lens that is fixed in the lens barrel and a movable lens that moves in the lens barrel. The movable lens is a focus lens that moves in the optical axis direction to adjust the focus, a zoom lens that moves in the optical axis direction to change the focal length, and a correction lens that moves in the direction perpendicular to the optical axis to correct image blur including. The movable lens is composed of one or a plurality of lens groups. In the following embodiments, a focus lens unit included in a lens barrel is described.

  FIG. 1A is a partially exploded perspective view of the focus lens unit of the lens barrel of the first embodiment. The focus lens unit includes a fixed cylinder 1, a cam cylinder 2 that engages with the fixed cylinder, a first moving cylinder 3, and a second moving cylinder 4. The fixed cylinder 1 is fixed in the lens barrel. The cam cylinder 2 is configured to be rotatable with respect to the fixed cylinder 1. The first moving cylinder 3 and the second moving cylinder 4 are configured to be movable in the optical axis direction in conjunction with the rotation of the cam cylinder 2.

  A fixed cylinder 1 having a mount portion mounted on a camera body (not shown) is provided with a plurality of guide grooves 1a extending in the optical axis direction. A cam cylinder 2 is rotatably fitted on the outer periphery of the fixed cylinder 1, and a plurality of cam grooves 2 a are formed in the cam cylinder 2. In this embodiment, the cam cylinder 2 is disposed outside the fixed cylinder 1, but the present invention is not limited to this.

  The fixed cylinder 1 is provided with a motor unit 7 which is a driving means for rotating the cam cylinder 2 around the optical axis. The rotation output of the motor 7a is output via an output gear 7b ( Drive means). In the present embodiment, the motor 7 a and the gear train are provided inside the fixed cylinder 1. The driving means is not limited to a motor and a gear train such as a key window and a lever that can be displaced within a range of ± 30 °.

  In each figure, in order to visualize the inside of the motor unit 7, the housing of the motor unit 7 that supports the gear train is omitted. The output gear 7b meshes with the gear portion 2b of the cam cylinder 2 and can drive the cam cylinder 2 to rotate. The cam cylinder 2 is rotated in a state in which movement in the optical axis direction is restricted by the movement restricting portion 2c. The gear portion 2 b is provided on the inner side of the cam cylinder 2, not on the entire inner circumference of the cam cylinder 2 but on a part thereof.

  The first moving cylinder 3 provided on the inner peripheral portion of the fixed cylinder 1 holds a moving lens group (focus lens group) 3a and is guided in the guide groove 1a of the fixed cylinder 1 and can move in the optical axis direction. It has become. A cam pin 3 b is provided on the outer peripheral portion of the first moving cylinder 3, and penetrates the guide groove 1 a of the corresponding fixed cylinder 1 to contact the cam groove 2 a of the corresponding cam cylinder 2.

  FIG. 1B is an enlarged cross-sectional view of the cam pin 3b as viewed from the optical axis direction. Since the guide groove 1a and the width restricting portion 3c are engaged and the rotation of the first moving cylinder 3 is restricted, the cam pin 3b receives the acting force from the corresponding cam groove 2a, and the cam cylinder 2 is driven to rotate. It is converted into a straight movement of the first moving cylinder 3. Between the fixed cylinder 1 and the first moving cylinder 3, the force of a plurality of springs 8 acts in the optical axis direction, and the play in the optical axis direction of the first moving cylinder 3 is packed in one direction. , Has solved the rattle.

  The second moving cylinder 4 provided on the inner peripheral portion of the fixed cylinder 1 holds a moving lens group (focus lens group) 4 a and is guided by guide shafts 5 and 6 provided on the first moving cylinder 3. Thus, it can move in the optical axis direction. A cam pin 4 b is also provided on the outer peripheral portion of the second movable cylinder 4, passes through the guide groove 1 a of the corresponding fixed cylinder 1, and contacts the cam groove 2 a of the corresponding cam cylinder 2.

  Since the rotation of the second moving cylinder 4 around the optical axis is restricted by the guide shafts 5 and 6, the cam pin 4b receives an acting force from the corresponding cam groove 2a, and the cam cylinder 2 is driven to rotate second. Is converted to straight drive of the movable cylinder 4.

  FIG. 1C is an enlarged cross-sectional view of the cam pin 4b as seen from the extending direction of the cam groove 2a. A spring 9 acting in the radial direction is provided inside the cam pin 4b of the first moving cylinder 4, and the action of the cam pin 4b and the tapered surface of the cam groove 2a causes the second moving cylinder 4 in the optical axis direction. The backlash is packed in one direction to eliminate the backlash.

  In the above configuration, first, when the lens barrel is mounted on a camera body (not shown) and the release button is pressed halfway, the focus detection signal calculated by the focus detection device in the camera body is converted into the CPU ( (Not shown). Then, the CPU drives the motor 7a and rotates the cam cylinder 2 via the output gear 7b. Along with this, the cam groove 2a of the cam cylinder 2 rotates, and the first moving cylinder 3 and the second moving cylinder 4 move in the optical axis direction to perform focusing.

  2A is a front view of the lens barrel, FIG. 2B is an SS cross-sectional view of FIG. 2A, FIG. 2C is a partially enlarged plan view around the spring member 10, and FIG. d) A plan view and a side view (a side view seen from the upper left and a side view seen from the upper right) of the spring member 10 mounted on the lens barrel.

  The spring member 10 is provided at a position that does not overlap the output gear 7b when viewed in the radial direction from the optical axis. The spring member 10 is an example of an elastic member that applies an elastic force between the fixed cylinder 1 and the cam cylinder 2 and prevents backlash between the fixed cylinder 1 and the cam cylinder 2. Other elastic members include rubber. The spring member 10 of the present embodiment is disposed between the fixed cylinder 1 and the cam cylinder 2, but may be provided outside the cam cylinder 2.

  Since it is provided at a position that does not overlap with the output gear 7b, the lens barrel does not become thicker in the radial direction, and a compact configuration can be maintained. Further, since the radial movement of the cam cylinder 2 does not occur due to the elastic force applied by the spring member 10, the focus lens is prevented from falling due to the shift of the contact point between the cam pin and the cam groove, and the optical performance and focusing accuracy are improved. can do. Furthermore, it is possible to prevent image shaking during live view display and moving image shooting.

  That is, if the spring member 10 is not provided, an engagement play a exists between the fixed cylinder 1 and the cam cylinder 2 as shown in FIG. For this reason, the cam cylinder 2 has a radius corresponding to the maximum engagement backlash a due to a change in the gravity direction due to a difference in posture between the vertical position shooting and the horizontal position shooting, a turning force of the cam cylinder 2 and a reversal of the rotation direction. Will move in the direction. At this time, if the three cam pins 3b are 3b1, 3b2, and 3b3, the contact points of the cam pins 3b2, 3b3 and the cam groove 2b are likely to be shifted, and actually, along the cam grooves 2b in which the respective cam pins 3 are fitted. Moving. As a result, the lens collapse of the following two components may occur.

As shown in FIG. 3B, the first component is a focus lens represented by the following formula, where r is the radius of the contact point between the cam pin 3b and the cam groove 2b, and α is the lead angle of the cam groove 2b. The rotation axis that is the fall component θ1 and that falls is the X axis in a direction parallel to the direction of the displacement a.
θ1 = arctan [(a × sin 60 ° × tan α) / (r × cos 30 °)] (1)
As shown in FIG. 3 (c), the second component is the tilt of the focus lens represented by the following formula, where r is the radius of the contact point between the cam pin 3b and the cam groove 2b and β is the taper angle of the cam pin 3b. The rotation axis that is the component θ2 and falls down is the Y axis that is orthogonal to the direction of the displacement a.
θ2 = arctan [(a × (1 + cos 60 °) × tan β) / (r × (1 + sin 30 °))] (2)
In an optical system in which the sensitivity of the focus lens is high, θ1 and θ2 degrade the optical performance, and the focusing accuracy deteriorates due to the focus shift around the image.

  The spring member 10 of the present embodiment is a leaf spring, and includes a fixed portion 11, a connecting portion 12, and an arm portion 13 as shown in FIG.

  The fixed portion 11 is a flat plate member arranged perpendicular to the optical axis and has an L shape. As shown in FIGS. 2A and 2C, a fixing hole 11a that is fastened to the fixing cylinder 1 with screws (screws) 14 is provided at one end of the L shape. Since the spring member 10 is fastened by a screw extending in the direction of the optical axis, the pilot hole of the screw 14 is easy to mold due to the structure of the mold and is easy to fasten. Further, the clockwise rotation that fastens the screw 14 with the fixing hole 11a as the center of rotation is the contact portion (second portion) with the fixed tube 1 that is closer to the contact portion (first contact portion) 13b with the cam tube 2. Of the urging force on the cam cylinder 2 is less likely to occur.

  A connecting portion 12 is coupled to one end of the L shape. The connecting portion 12 is bent at a substantially right angle from the fixed portion 11 and extends substantially parallel to the optical axis. The connecting portion 12 is coupled to the arm portion 13 in the vicinity of the contact portion 13 a of the arm portion 13.

  The arm portion 13 has a flat plate shape and is bent at the contact portion 13b. The arm part 13 has contact parts 13a to 13c. In the contact portion 13b, the spring member 10 presses the inside of the cam cylinder 2. The tip of the arm part 13 functions as the contact part 13c. The contact portions 13 a and 13 c are in contact with the outside of the fixed cylinder 1. As a result, the spring member 10 urges the cam cylinder 2 in the radial direction A, so that the cam cylinder 2 does not move by the amount corresponding to the backlash, and the tilt of the focus lens can be reduced.

  The spring member 10 is fixed to the fixed cylinder 1 at one end of the fixed portion 11, and the opposite side is a free end. Thereby, the change of the urging force per unit deformation amount is small, and even if the dimensional variation occurs, the variation of the urging force can be suppressed, and the tilt of the focus lens can be easily suppressed.

  As shown in FIG. 2A, in any direction orthogonal to the optical axis (that is, in the circumferential direction of the lens barrel), the spring member 10 has a range Z in which the output gear 7b is provided and a part thereof. It is provided in the overlapping range W. The spring member 10 is provided because the driving force applied by the output gear 7b and the elastic force applied by the spring member 10 are unlikely to generate a couple of rotation C that causes the central axis of the cam cylinder 2 to fall with respect to the optical axis. This makes it difficult for the cam cylinder 2 to fall over.

  As shown in FIG. 2A, when the lens barrel is viewed from the optical axis direction, the spring member 10 is provided in a region Y that is 90 ° away from the region X where the output gear 7b is provided. As a result, the output gear 7b and the spring member 10 do not interfere with each other, so that the lens barrel can be kept small.

  Further, with this arrangement, a biasing force acts in a radial direction A substantially parallel to the direction B of the driving force applied by the output gear 7b. For this reason, it is possible to efficiently prevent the cam cylinder 2 from moving due to the turning force of the cam cylinder 2 generated by the driving force applied by the output gear 7b or the reversal of the rotation direction, etc. with a minimum biasing force. . It is sufficient that the spring member 10 is arranged so that the elastic force applied by the spring member 10 cancels at least a part of the driving force applied by the output gear 7b.

  In the present embodiment, the spring member 10 is in contact with the cam cylinder 2 at one point of the contact portion 13b, but the spring member 10 is prohibited from contacting the cam cylinder 2 at a plurality of points or in surface contact. It is not a thing. In this case, the direction of the elastic force of the spring member 10 is the direction of the resultant force of the plurality of radial elastic forces or the direction of the resultant elastic force in the surface contact.

  The angle formed by the direction from the center of the lens toward the point where the output gear 7b acts on the cam cylinder 2 and the direction from the center of the lens toward the point where the spring member 10 biases the cam cylinder 2 as viewed from the optical axis direction is 90 °. It is not limited to. As a range in which the cam cylinder 2 can be efficiently prevented from being moved by the driving force applied by the output gear 7b with the smallest possible biasing force, the output gear acting force and the spring biasing force form an acute angle of 90 °. A range of ± 45 ° is preferable.

  The cam cylinder 2 has a contact portion (third contact portion) 2 d with the spring member 10. And since the cam cylinder 2 rotates with respect to the fixed cylinder 1, the contact part 2d rotates as shown by the arrow of FIG.4 (b). In the first rotational position shown in FIG. 4A, the contact portion 2d does not contact the contact portion 13b. The spring member 10 is attached to the fixed cylinder 1 and fastened with a screw 14 at the first rotational position shown in FIG. Thereafter, the cam cylinder 2 is rotated in the direction of the arrow to the second rotational position shown in FIG. 4B, and the abutting portion 2d of the cam cylinder 2 is brought into contact with the abutting portion 13b to apply an elastic force. . As a result, the assembly work of the spring member 10 becomes easy.

  In order to reduce the backlash of the cam cylinder 2, it is preferable that the elastic force by the spring member 10 is larger than the component in the biasing direction by the spring member 10 of the acting force on the cam cylinder 2 generated by the output gear 7b. More preferably, the weight of the cam cylinder 2 and the force acting on the cam cylinder 2 generated by the output gear 7b are larger than the component in the urging direction by the spring member 10.

  As shown in FIG. 2 (c), between the contact portions 13 b and 13 c, which are part of the arm portion 13 of the spring member 10, is pressed in the optical axis direction from above by the pressing member 15 fixed to the fixed cylinder 1. It has been. As a result, the position in the vicinity of the contact portion 13c, which is a free end, is likely to fluctuate, so that it is easy to maintain a constant variation in the elastic force applied by the contact portion 13b to the cam cylinder 2.

  In this embodiment, as shown in FIG. 2B, since the range Z and the range W overlap, there is also an effect of downsizing in the optical axis direction as compared to the case where the ranges do not overlap. The lens barrel may have an annular detection means that rotates in conjunction with an operation ring operated by a user and detects the rotation of the operation ring, and FIG. 5 shows an example thereof. FIG. 5A is a front view, and FIG. 5B is an SS cross-sectional view of FIG. An encoder 17 having a comb-shaped shielding portion is provided as a detection means on the entire circumference, and the presence or absence of the shielding portion is continuously detected by the photo interrupter 18 to detect the rotation of the operation ring. In the case of the lens barrel having such a configuration, the encoder as the detection means needs to be present all around, so that the dimensions of the lens barrel in the optical axis direction are the same as the dimensions in the optical axis direction of the encoder as the detection means. Will increase. For this reason, the effect of miniaturization by overlapping the range Z and the range W is great. If the lens barrel of the present embodiment is used in the photographing apparatus, it is possible to realize a photographing apparatus that has the same effect as described above.

  The present embodiment is different from the first embodiment in that a spring member 20 composed of a wire spring is used instead of the spring member 10 composed of a leaf spring. 6A is a front view of the lens barrel, and FIG. 6B is a plan view and a side view of the spring member 20. Similar to the spring member 10, the spring member 20 includes a fixing portion 21, a connection portion 22, and an arm portion 23. The spring member 20 is fixed to the fixed cylinder 1 by the fixing portion 21, the cam cylinder 2 is urged by the contact portion 23b of the arm portion 23, and the fixed cylinder 1 is urged by the contact portions 23a and 23c. 1 can be obtained.

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

  The lens barrel can be applied to the field of single-lens reflex digital cameras.

DESCRIPTION OF SYMBOLS 1 ... Fixed cylinder, 2 ... Cam cylinder, 3 ... 1st moving cylinder, 4 ... 2nd moving cylinder, 3a, 4a ... Focus lens, 7b ... Output gear (drive means) 10, 20 ... Spring member (elasticity) Element)

Claims (15)

A fixed cylinder;
A cam cylinder engaged with the fixed cylinder;
A moving cylinder that holds the lens and moves linearly in conjunction with the rotation of the cam cylinder;
Driving means for rotating the cam cylinder around the optical axis of the lens with respect to the fixed cylinder;
An elastic member that urges the cam cylinder in a direction perpendicular to the optical axis;
Have
When viewed from the optical axis direction, the direction from the center of the lens toward the point where the driving means applies a driving force to the cam cylinder and the direction from the center of the lens toward the point where the elastic member applies an elastic force to the cam cylinder A lens barrel characterized by the fact that they are different.   When viewed from the optical axis direction, the direction from the center of the lens toward the point where the driving means applies a driving force to the cam barrel and the point from the center of the lens toward the point where the elastic member applies an elastic force to the cam barrel. The lens barrel according to claim 1, wherein an angle formed by the directions is 90 ° ± 45 °.   The lens barrel according to claim 1, wherein the driving unit and the elastic member overlap in any direction orthogonal to the optical axis. The drive means has a gear part formed on the cam cylinder, and an output gear meshing with the gear part,
The lens barrel according to any one of claims 1 to 3, wherein the gear portion is formed on a part of an inner periphery of the cam barrel.   The lens according to any one of claims 1 to 4, wherein the elastic member is in contact with the cam cylinder inside the cam cylinder and the fixed cylinder outside the fixed cylinder. A lens barrel.   The lens barrel according to any one of claims 1 to 5, wherein the elastic member is fixed to the fixed cylinder at one location.   The lens barrel according to any one of claims 1 to 6, wherein the elastic member is fastened with a screw extending in the optical axis direction. The elastic member has a fixing portion having a fixing hole fixed to the fixing cylinder by a screw, and an arm portion fixed to the fixing portion,
The arm portion includes a first contact portion that contacts the inside of the cam tube, and a second contact portion that contacts the outside of the fixed tube and is closer to the fixing hole than the first contact portion. And having
The lens barrel according to claim 6, wherein rotation of the elastic member in a direction in which the screw is fastened around the fixing hole is restricted by the second contact portion. The cam cylinder has a third contact portion that contacts the elastic member,
When the cam cylinder is in the first rotational position with respect to the fixed cylinder, the elastic member and the third contact portion do not contact each other, and when the cam cylinder is in the second rotational position with respect to the fixed cylinder. The lens barrel according to any one of claims 1 to 8, wherein the elastic member and the third contact portion are in contact with each other.   The elastic force applied by the elastic member is larger than a component in a direction of the elastic force of the driving force applied by the driving unit to the cam cylinder. The lens barrel described.   The lens barrel according to claim 10, wherein the elastic force is greater than a component of the driving force and the weight of the cam tube in the direction of the elastic force. An operating ring for rotating the cam cylinder;
Detecting means for rotating in conjunction with the operation ring and detecting rotation of the operation ring;
The lens barrel according to claim 3, further comprising: Fastened with screws extending in the optical axis direction,
The elastic member has a fixing part having a fixing hole fixed to the fixed cylinder, and an arm part fixed to the fixing part,
The lens barrel according to claim 6, wherein the fixed barrel includes a pressing member that holds a part of the arm portion in the optical axis direction. An imaging apparatus comprising the lens barrel according to claim 1. A fixed cylinder;
A cam cylinder engaged with the fixed cylinder;
Holding a focus lens that moves in the optical axis direction to adjust the focus, and moves in a straight line in conjunction with the rotation of the cam cylinder;
Drive means for rotationally driving the cam cylinder about the optical axis of the focus lens with respect to the fixed cylinder;
An elastic member that urges the cam cylinder in a direction perpendicular to the optical axis;
Have
When viewed from the optical axis direction, the direction from the center of the focus lens toward the point where the driving means applies a driving force to the cam cylinder and from the center of the focus lens to the point where the elastic member applies an elastic force to the cam cylinder. A focus lens unit characterized by different directions.