JP6766933B2 - Lens barrel and image pickup device - Google Patents

Description

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

In the lens barrel, there is a structure in which a part of the profile of the cam groove is cut out and the cut out part is replaced with a key and a key groove in order to avoid interference between the cam groove driving the cam pin and another member (Patent Document). 1).
[Patent Document 1] Japanese Unexamined Patent Publication No. 2004-029318

The key and keyway drive mechanism cannot change the curvature in the middle of the profile. Therefore, the cam profile that can be assigned to the keyway is limited, and the layout of the members in the lens barrel is restricted.

In the first aspect of the present invention, a lens holding portion for holding the lens and a first cylinder having a first cam groove and a second cam groove and having a notch portion for avoiding interference with the lens holding portion are formed. A second cylinder having a first protrusion that engages with the first cam groove and a second protrusion that engages with the second cam groove is provided, and the first cam groove has a first protrusion for retracting. Within the movable range, the notch divides the first part cam groove and the second part cam groove, and when at least the first protrusion is in the position corresponding to the notch, the second cam groove and the second protrusion A lens barrel that engages with is provided.

In the second aspect of the present invention, an imaging device including the lens barrel is provided.

The above-mentioned outline of the invention does not list all the necessary features of the present invention. Sub-combinations of these feature groups can also be inventions.

It is a schematic sectional view of the image pickup apparatus 100. It is a schematic sectional view of the image pickup apparatus 100. It is a partial perspective view of the lens barrel 200. It is a partial perspective view of the lens barrel 200. It is a partial exploded perspective view of a lens barrel 200. It is a partial exploded perspective view of a lens barrel 200. It is a partial exploded perspective view of a lens barrel 200. It is a schematic development view of the fixed cam cylinder 140. It is a partial rear view of the lens barrel 200. It is a partial perspective view of the lens barrel 200.

Hereinafter, the present invention will be described through embodiments of the invention. The following embodiments do not limit the invention according to the claims. Not all combinations of features described in the embodiments are essential to the solution of the invention.

FIG. 1 is a schematic cross-sectional view of the image pickup apparatus 100. The image pickup device 100 includes an image pickup element 102 and a lens barrel 200. In FIG. 1, the lens barrel 200 is in an extended state. In the following description, the side closer to the subject is referred to as the front and the side far from the subject is referred to as the rear with respect to the imaging device 100.

The image sensor 102 is supported by the sensor base 101 and fixed near the rear end of the image sensor 100. The image sensor 102 converts the subject luminous flux incident through the lens barrel 200 into an electric signal and outputs it.

The lens barrel 200 includes a first lens group 111, a second lens group 121, and a third lens group 131, and a fixed cam cylinder 140, a rotating cam cylinder 150, and a straight-moving cylinder 160. The first lens group 111, the second lens group 121, and the third lens group 131 are arranged along a common optical axis X to form the optical system of the lens barrel 200.

The first lens group 111 is held at the tip of the first group cylinder 113 via the first lens chamber 112. The first group cylinder 113 is driven by the rotary cam cylinder 150 through a cam pin 114 provided near the rear end while engaging with the straight guide groove 161 of the straight cylinder 160 to regulate the rotation. As a result, the first group cylinder 113 advances and retreats the first lens group 111 along the optical axis X.

The second lens group 121 is held in the second lens chamber 122. A cam pin 124 is provided on the outer peripheral surface of the second lens chamber 122. The cam pin 124 is driven by the rotary cam cylinder 150 while being restricted in rotation by the straight guide groove 164 of the straight cylinder 160. As a result, the second lens chamber 122 advances and retreats the second lens group 121 along the optical axis X.

The third lens group 131 is held in the third lens chamber 132. The third lens chamber 132 is connected to the fitting portion 133 and the nut 134. The fitting portion 133 is fitted to the guide shaft 103 fixed to the sensor base 101 in parallel with the optical axis X. As a result, it is movably supported in a direction parallel to the optical axis X.

Further, the fitting portion 133 is fitted with the guide shaft 103 at a plurality of locations. As a result, the third lens chamber 132 maintains a state in which the third lens group 131 is orthogonal to the optical axis X, and regulates the tilt of the third lens group 131.

The nut 134 is screwed with a lead screw 172 arranged parallel to the optical axis X. The lead screw 172 is rotationally driven by the motor 171. When the lead screw 172 is rotationally driven, the nut 134 moves along the longitudinal direction of the lead screw 172. As a result, by electrically controlling the drive amount of the motor 171, the third lens group 131 is moved along the optical axis X, and the focal position of the optical system of the lens barrel 200 is moved along the optical axis X. Can be made to.

In the lens barrel 200, the fixed cam barrel 140 is fixed to the sensor base 101. A straight guide groove 142 is provided on the inner surface of the fixed cam cylinder 140 to guide the straight travel while restricting the rotation of the straight cylinder 160. Further, the fixed cam cylinder 140 is formed with a notch portion 144 provided for the purpose of avoiding interference with the fitting portion 133 of the third lens chamber 132. Further, the fixed cam cylinder 140 has a main cam groove 146 on the inner surface that engages with the main cam pin 154 provided near the rear end of the rotary cam cylinder 150.

The rotating cam cylinder 150 is arranged inside the fixed cam cylinder 140, and has a main cam pin 154 projecting outward in the radial direction of the lens barrel 200 near the rear end. The main cam pin 154 engages with the main cam groove 146 of the fixed cam cylinder 140. As a result, when the rotary cam cylinder 150 is rotationally driven from the outside, the rotary cam cylinder 150 advances and retreats in the optical axis X direction by the driving force received through the main cam pin 154.

Further, the rotary cam cylinder 150 has a plurality of cam grooves 151 and 152 on the inner surface. One cam groove 151 engages with a cam pin 114 provided near the rear end of the first group cylinder 113 to drive the first group cylinder 113. The other cam groove 152 engages with the cam pin 124 of the second lens chamber 122 to drive the second lens chamber 122.

The straight cylinder 160 engages with the first group cylinder 113 by the straight guide groove 161 provided on the outer peripheral surface. As a result, the rotation of the first group cylinder 113 around the optical axis X is restricted. Further, the straight-moving cylinder 160 engages the guide pin 162 provided at the rear end with the straight-moving guide groove 142 of the fixed cam cylinder 140. As a result, the movement of the straight cylinder 160 in the optical axis X direction is guided, and the rotation of the straight cylinder 160 itself around the optical axis X is restricted.

Further, the straight cylinder 160 engages with the peripheral groove 153 of the rotary cam cylinder 150 at the rib 163 provided on the outer peripheral surface near the rear end. As a result, the straight-moving cylinder 160 moves in the optical axis X direction as the rotating cam cylinder 150 advances and retreats in the optical axis X direction while allowing rotation of the rotating cam cylinder 150 around the optical axis X.

In the image pickup apparatus 100 having the above structure, the magnification of the optical system of the lens barrel 200 is increased by moving the first lens group 111 and the second lens group 121 forward and backward in the X direction of the optical axis. Change. Further, by moving the third lens group 131 in the X direction of the optical axis, the subject image formed by the optical system of the lens barrel 200 can be focused on the image pickup surface of the image pickup element 102.

In the lens barrel 200, the rotary cam cylinder 150 rotates around the optical axis X. As the rotary cam cylinder 150 rotates, the main cam pin 154 of the rotary cam cylinder 150 moves across the paper surface. In FIG. 1, the main cam pin 154 is illustrated for the purpose of showing that the rotary cam cylinder 150 engages with the fixed cam cylinder 140 through the main cam pin 154, but the main cam pin 154 does not always appear in the cross section shown.

FIG. 2 is a schematic cross-sectional view of the image pickup apparatus 100. As shown in the figure, the lens barrel 200 moves each of the first lens chamber 112, the second lens chamber 122, and the third lens chamber 132 to the end of the movable range, and the total length of the lens barrel 200. Is greatly shortened. Thereby, portability can be improved. However, when the lens barrel 200 is retracted, the first lens chamber 112 and the second lens chamber 122 are moved to a range different from the moving range in the case of scaling or focusing.

FIG. 3 is a partial perspective view of the lens barrel 200. FIG. 3 shows a state in which the assembly of the fixed cam cylinder 140, the rotating cam cylinder 150, and the third lens chamber 132 is looked up from the obliquely rear side of the image pickup apparatus 100. In the illustrated assembly, the rotary cam cylinder 150 is arranged inside the fixed cam cylinder 140, and the third lens chamber 132 is further arranged inside the rotary cam cylinder 150.

On the upper side in the drawing, a part of the third lens chamber 132 extends over the rotating cam cylinder 150 to the outer peripheral side of the fixed cam cylinder 140. As a result, the third lens chamber 132 is connected to the fitting portion 133 fitted to the guide shaft 103. Therefore, the third lens chamber 132 is guided by the guide shaft 103 to move the third lens group inside the fixed cam cylinder 140.

On the lower left side in the drawing, a gear portion 155 is provided on the outer peripheral surface of the rotary cam cylinder 150. The gear portion 155 is rotationally driven by meshing with the output gear of the actuator housed in the housing 145 provided on the outer peripheral surface of the fixed cam cylinder 140. As a result, the rotary cam cylinder 150 is rotated to drive the first lens group 111 and the second lens group 121.

FIG. 4 is a partial perspective view of the lens barrel 200. FIG. 4 shows a state in which the assembly of the fixed cam cylinder 140 and the third lens chamber 132 is looked up from the obliquely front side of the image pickup apparatus 100.

Since the rotating cam cylinder 150 is removed in the illustrated assembly, the inner surface of the fixed cam cylinder 140 is widely exposed. A main cam groove 146 is further formed on the inner surface of the fixed cam cylinder 140 covered with the light-shielding line 149.

In the fixed cam cylinder 140, the main cam groove 146 is arranged so as to intersect the notch 144. Therefore, the cam profile of the main cam groove 146 is temporarily interrupted in the section where the notch portion 144 is provided, and a pair of partial cam grooves 147 sandwiching the notch portion 144 are formed.

The main cam pin 154 of the rotary cam cylinder 150 passes through the notch 144 and moves back and forth between the pair of partial cam grooves 147 forming the main cam groove 146. However, in the section where the cam profile is cut off by the notch portion 144, the main cam pin 154 cannot be driven by the main cam groove 146.

FIG. 5 is a partially exploded perspective view of the lens barrel 200. FIG. 5 shows the engagement relationship between the fixed cam cylinder 140 and the rotating cam cylinder 150 by looking up from diagonally rearward in the image pickup apparatus 100.

The rotary cam cylinder 150 has a plurality of main cam pins 154 provided as protrusions on the outer periphery near the rear end. In the illustrated example, three main cam pins 154 are provided at substantially equal intervals in the circumferential direction of the rotary cam cylinder 150.

Three sets of main cam grooves 146 are also provided on the inner surface of the fixed cam cylinder 140 corresponding to the three main cam pins 154. Each main cam groove 146 has a side wall formed by sinking a part of the inner surface of the fixed cam cylinder 140 in the thickness direction as a cam surface.

Of these three main cam grooves 146, one main cam groove 146 that intersects the notch portion 144 is formed by a pair of partial cam grooves 147. In other words, the other two main cam grooves 146 are formed as one cam groove complete with a continuous cam profile without intersecting the notch 144.

FIG. 6 is a partially exploded perspective view of the lens barrel 200. FIG. 6 shows a state in which the fixed cam cylinder 140 and the rotating cam cylinder 150, which are the same as those in FIG. 5, are viewed from different viewpoints diagonally rearward.

The rotary cam cylinder 150 further has a single sub cam pin 158 provided as a protrusion between the pair of main cam pins 154. The sub cam pin 158 is provided near the rear end of the rotary cam cylinder 150 so as to project outward in the radial direction. The sub cam pin 158 is provided adjacent to the main cam pin 154 that engages the main cam groove 146 combined with the partial cam groove 147.

In the region where the sub cam pin 158 is sandwiched in the circumferential direction of the rotary cam cylinder 150, a small diameter portion 159 in which the diameter of the rotary cam cylinder 150 is reduced is provided. In other words, the sub cam pin 158 is provided in the small diameter portion 159 having a diameter smaller than the portion where the main cam pin 154 is provided.

FIG. 7 is a partially exploded perspective view of the lens barrel 200. FIG. 7 shows a state in which the fixed cam cylinder 140 and the rotary cam cylinder 150, which are the same as those in FIG. 6, are looked up from positions symmetrical with respect to the optical axis X.

As shown, a sub cam groove 148 that engages with the sub cam pin 158 is arranged on the inner surface of the fixed cam cylinder 140. The auxiliary cam groove 148 has a side wall formed by a pair of ridge-shaped portions protruding inward in the radial direction from the inner surface of the fixed cam cylinder 140 as a cam surface.

As described above, the main cam groove 146 in the fixed cam cylinder 140 is provided so as to be recessed with respect to the inner surface of the fixed cam cylinder 140. On the other hand, the sub cam groove 148 in the fixed cam cylinder 140 is formed so as to rise from the inner surface of the fixed cam cylinder 140.

FIG. 8 is a schematic development view of the fixed cam cylinder 140. In FIG. 8, the left side in the figure is the front side of the image pickup apparatus 100.

In FIG. 8, the main cam pin 154 and the sub cam pin 158 of the rotary cam cylinder 150 are drawn together for the purpose of explaining the functions of the main cam groove 146 and the sub cam groove 148. Further, for the purpose of showing the correspondence between FIGS. 8 and 9, a part of the fixed cam cylinder 140 and the rotating cam cylinder 150 viewed from the rear side in the X direction of the optical axis is shown by being surrounded by a dotted line A.

Of the three main cam grooves 146, a part of the cam profile of the main cam groove 146 intersecting the notch portion 144 is cut off by the notch portion 144 to form a pair of partial cam grooves 147. The cam profiles of the pair of partial cam grooves 147 each form part of the cam profile of the entire main cam groove 146. However, the cam profile of the region overlapping the notch 144 is not included in any of the pair of partial cam grooves 147.

The single sub cam groove 148 has a cam profile including a part of the cam profile cut out in the notch 144 in the main cam groove 146 described above. Further, the sub cam groove 148 has the above-mentioned main cam groove 146 and other mains so that the engagement of the sub cam pin 158 with the sub cam groove 148 is in phase with the engagement of the main cam pin 154 with the main cam groove 146. It is arranged between the cam groove 146 and the cam groove 146.

In the process of rotating the rotary cam cylinder 150, when the main cam pin 154 that has moved in the main cam groove 146 approaches the notch 144 and comes out of the partial cam groove 147, the main cam groove 146 becomes the main cam pin 154. It will not be engaged. However, even in this state, the sub cam groove 148 and the sub cam pin 158 are engaged to transmit the driving force from the fixed cam cylinder 140 to the rotary cam cylinder 150.

Thus, the lens barrel 200 has a main cam groove 146 and a main cam pin 154 that have a notch 144 and are not partially engaged, but two other sets that do not intersect the notch 144. In addition to the main cam groove 146 and the main cam pin 154, a set of sub cam grooves 148 and the sub cam pin 158 are engaged. As a result, even if one of the main cam grooves 146 intersects the notch 144, the rotating cam cylinder 150 is driven or positioned by three sets of cam grooves and cam pins over the entire cam profile of the main cam groove 146. To.

Of the cam profiles of the main cam groove 146, the cam profile of the portion cut from the main cam groove 146 and covered by the sub cam groove 148 includes a curved line. However, since the sub cam pin 158 has a circular cross section orthogonal to the fitting direction with respect to the sub cam groove 148, the sub cam pin 158 smoothly moves inside the sub cam groove 148 having a bent cam profile. Therefore, the sub cam groove 148 can take charge of a part of the cam profile of the main cam groove 146 regardless of whether the cam profile is a straight line or a curved line.

Further, the sub cam groove 148 has a cam profile corresponding to a part of the cam profile of the main cam groove 146. Therefore, the length of the sub cam groove 148 in the extending direction is shorter than the length of the main cam groove 146 in the extending direction.

On the other hand, the sub cam pin 158 is provided in the rotary cam cylinder 150 common to the main cam pin 154. Therefore, when the rotating cam cylinder 150 rotates with respect to the fixed cam cylinder 140, the movement amounts of the main cam pin 154 and the sub cam pin 158 with respect to the fixed cam cylinder 140 are equal to each other. Therefore, as the rotary cam cylinder 150 rotates, the sub cam pin 158 comes out of the sub cam groove 148 or enters the sub cam groove 148.

Here, both ends of the sub cam groove 148 are open. Therefore, by widening the distance between the pair of side walls forming the secondary cam groove 148 at the end of the secondary cam groove 148, the secondary cam pin 158 can smoothly enter and exit the secondary cam groove 148.

Further, at the position where the sub cam pin 158 separates or enters the sub cam groove 148, the cam profile of the sub cam groove 148 is orthogonal to the circumferential direction of the fixed cam cylinder 140, that is, the optical axis X of the lens barrel 200. It extends almost linearly in the direction of the cam. As a result, it is possible to prevent the driving force in the optical axis X direction from changing to the rotating cam cylinder 150 through the sub cam pin 158 when entering and exiting the sub cam groove 148.

By the way, in the cam profile of the main cam groove 146, the portion located on the lower side in the drawing is optically significant for the first lens group 111 and the second lens group 121 for the purpose of changing the magnification of the lens barrel 200. It becomes an optical area to be moved to. On the other hand, in the cam profile of the main cam groove 146, the portion located on the upper side in the drawing is a non-optical region for moving the first lens group 111 and the second lens group 121 for the purpose of retracting the lens barrel 200. ..

In the lens barrel 200, the portion cut out from the cam profile of the main cam groove 146 is included in the non-optical region. Therefore, when the main cam pin 154 moves in and out of the partial cam groove 147 and the sub cam pin 158 moves in and out of the sub cam groove 148, even if the driving force transmitted to the rotary cam cylinder 150 changes, the lens barrel 200 It is prevented from affecting the performance as an optical device.

In FIG. 8, the side view in which the dotted line A is oriented shows the portion including the sub cam groove 148 from the partial cam groove 147 on the non-optical region side of the main cam groove 146 from the rear of the lens barrel 200 in the optical axis X direction. Show what you saw. The same portion is enlarged and shown in FIG.

FIG. 9 is a partial rear view of the lens barrel 200, and shows a portion surrounded by a dotted line A in FIG. However, in FIG. 9, the corresponding portion is enlarged, and the fixed cam cylinder 140 and the rotary cam cylinder 150 are shown in a state of being separated from each other.

In the fixed cam cylinder 140, all of the partial cam grooves 147 forming the main cam groove 146 are formed so as to be depressed from the inner surface of the fixed cam cylinder 140. On the other hand, the sub cam groove 148 is formed by a ridge-shaped side wall that rises from the inner surface of the fixed cam cylinder 140. Therefore, in the lens barrel 200, the side wall of the sub cam groove 148 is closer to the opposite rotary cam tube 150 than the side wall of the main cam groove 146.

The sub cam pin 158 that engages with the sub cam groove 148 is arranged in a small diameter portion 159 that has a smaller diameter than the region where the main cam pin 154 is formed. Therefore, the sub cam groove 148 raised from the fixed cam cylinder 140 does not interfere with the outer surface of the rotating cam cylinder 150.

In the sub cam pin 158, the diameter D ₂ of the cross section orthogonal to the fitting direction with respect to the sub cam groove 148 is smaller than the diameter D _{1 of} the cross section orthogonal to the fitting direction with respect to the main cam groove 146 in the main cam pin 154. .. Further, due to the above difference in diameter, the engagement depth H ₁ of the main cam pin 154 with respect to the main cam groove 146 is deeper than the engagement depth H ₂ of the sub cam pin 158 with respect to the sub cam groove 148.

However, the sub cam pin 158 drives the rotary cam cylinder 150 only in the non-optical region where the lens barrel 200 is retracted in the cam profile of the main cam groove 146. In the non-optical region, the secondary cam pin 158 stops only when the lens barrel 200 is fully retracted or fully extended. Therefore, the sub cam pin 158 does not stop at the intermediate portion where the cam profile of the sub cam groove 148 is inclined, and even if the sub cam pin 158 is thinner than the main cam pin 154, the positioning accuracy of the rotary cam cylinder 150 is not affected. ..

In this way, the fixed cam cylinder 140 is provided with the notch portion 144, and the passage path of the fitting portion 133 of the third lens chamber 132 and the passage path of the main cam pin 154 are intersected with each other to obtain the diameter of the lens barrel 200. The diameter of the lens barrel 200 can be reduced by arranging the fitting portion 133 inside in the direction. Further, by providing the sub cam groove 148 and the sub cam pin 158, the drive and positioning accuracy of the rotary cam cylinder 150 can be prevented from being lowered regardless of the above arrangement. Further, by making the sub cam pin 158 cylindrical or conical trapezoidal, the cam profile handled by the sub cam groove 148 is not restricted.

Further, the engagement portion of the main cam pin 154 with respect to the main cam groove 146 intersecting the notch portion 144 and the engagement portion of the sub cam pin 158 with the sub cam groove 148 supplementing the notch portion 144 of the main cam groove 146 are lensed. By arranging the lens barrel 200 so as to be displaced in the radial direction, the sliding resistance due to the sub cam pin 158 can be reduced and the load on the actuator can be reduced. Further, by shortening the length of the auxiliary cam groove 148 provided on the inner surface of the fixed cam cylinder 140 in the extending direction, the area of the light-shielding line provided on the inner surface of the fixed cam cylinder 140 is increased, and the optical characteristics of the lens barrel 200 are improved. Can be improved.

FIG. 10 is a partial perspective view of the lens barrel 200, in which the third lens chamber 132 driven by the motor 171 and the lead screw 172 moves to the front side of the lens barrel 200 from the state shown in FIG. Indicates the state of the lens. In this case, the fitting portion 133 of the third lens chamber 132 penetrates deeply into the notch portion 144. Therefore, the fitting portion 133 enters between the partial cam grooves 147, and the main cam pin 154 of the rotary cam cylinder 150 cannot pass through the notch portion 144.

Therefore, by controlling the movement of the third lens chamber 132 only when the main cam pin 154 is engaged with the partial cam groove 147, the main cam pin 154 and the third lens chamber 132 of the rotary cam cylinder 150 are controlled. Interference with the fitting portion 133 can be prevented. Further, when the fitting portion 133 of the third lens chamber 132 is located between the partial cam grooves 147, the main cam pin 154 and the fitting portion 133 can be combined by restricting the movement of the third lens chamber 132. Interference can be prevented.

Further, when the main cam pin 154 of the rotary cam cylinder 150 and the fitting portion 133 of the third lens chamber 132 interfere with each other, the main cam pin 154 is moved away from the notch portion 144 of the fixed cam cylinder 140. The interference state can be canceled by moving it in the direction once. Then, by sequentially moving the rotary cam cylinder 150 and the third lens chamber 132 as described above, it is possible to prevent the interference from reoccurring.

Although the present invention has been described above using the embodiments, the technical scope of the present invention is not limited to the scope described in the above embodiments. It will be apparent to those skilled in the art that various changes or improvements can be made to the above embodiments. It is clear from the description of the claims that such modified or improved forms may also be included in the technical scope of the present invention.

100 Imaging device, 101 Sensor base, 102 Imaging element, 103 Guide axis, 111 First lens group, 112 First lens chamber, 113 First group cylinder, 114, 124 Cam pin, 121 Second lens group, 122 Second lens chamber , 131 3rd lens group, 132 3rd lens chamber, 133 fitting part, 134 nut, 140 fixed cam cylinder, 142, 161, 164 straight guide groove, 144 notch, 145 housing, 146 main cam groove, 147 part Cam groove, 148 secondary cam groove, 149 light-shielding line, 150 rotating cam cylinder, 151, 152 cam groove, 153 peripheral groove, 154 main cam pin, 155 gear part, 158 secondary cam pin, 159 small diameter part, 160 straight cylinder, 162 guide pin , 163 ribs, 171 motors, 172 lead screws, 200 lens barrels

Claims (14)

The lens holding part that holds the lens and
A first cylinder having a first cam groove and a second cam groove, and a notch portion having an open end in the optical axis direction in order to avoid interference with the lens holding portion.
A second cylinder having a first protrusion that engages with the first cam groove and a second protrusion that engages with the second cam groove is provided.
The first cam groove is divided into a first partial cam groove and a second partial cam groove by the notch within a range in which the first protrusion can move in order to retract.
A lens barrel in which the second cam groove and the second protrusion are engaged when at least the first protrusion is in a position corresponding to the notch. The lens holding portion is movable in the optical axis direction and can be moved.
The lens barrel according to claim 1, wherein when the lens holding portion and the first cylinder are closest to each other, at least a part of the lens holding portion is located in the region of the notch portion. The lens barrel according to claim 1 or 2, wherein the notch is opened at one end on the image side of the first cylinder. The lens barrel according to any one of claims 1 to 3, wherein the second partial cam groove is formed in a range in which the first protrusion can move in order to retract. The method according to any one of claims 1 to 4, wherein when the second cam groove and the second protrusion are not engaged, the first partial cam groove and the first protrusion are engaged. Lens barrel. The lens barrel according to any one of claims 1 to 5 , wherein the second cam groove and the second protrusion engage in a region where the second protrusion moves in order to retract . The lens barrel according to any one of claims 1 to 6 , wherein the shape of the first cam groove and the shape of the second cam groove are different. The lens barrel according to any one of claims 1 to 7 , wherein the second cam groove is shorter than the first cam groove. The lens barrel according to any one of claims 1 to 8, wherein the first cylinder does not rotate. The lens barrel according to any one of claims 1 to 9 , wherein the second cylinder rotates about an optical axis. The depth at which the first protrusion engages with the first cam groove is deeper than the depth at which the second protrusion engages with the second cam groove, according to any one of claims 1 to 10. The lens barrel described. The lens barrel according to any one of claims 1 to 11 , wherein the portion of the second cylinder provided with the second protrusion has a smaller diameter than the portion provided with the first protrusion. The lens barrel according to any one of claims 1 to 12 , wherein the second cam groove is formed by a pair of side walls protruding radially from the surface of the first cylinder. An image pickup apparatus comprising the lens barrel according to any one of claims 1 to 13 .

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