JP2006349798A - Cam groove structure of cam barrel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the cam groove structure of a cam barrel improved in the actuation of a follower pin and a cam groove, preventing faulty actuation caused by a manufacture error, and obtaining smooth actuation without deteriorating performance. <P>SOLUTION: Front and rear cam grooves 101 and 102 having the same locus and guiding first and second follower pins P1 and P2 are formed on the inner peripheral surface of the cam barrel 6A. When the first follower pin P1 in the front cam groove 101 is arranged in a first abutting area 103, the second follower pin P2 in the rear cam groove 102 is arranged in a second non-abutting area 106. When the first follower pin P1 arranged in the first abutting area 103 in the cam groove 101 comes out of the first abutting area 103 associated with the withdrawing/extending operation of the cam barrel 6A, the second follower pin P2 arranged in the second non-abutting area 106 in the rear cam groove 102 is arranged in the second abutting area 105, thereby transferring the abutting area. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a cam groove structure of a cam barrel that moves a lens group and a lens frame with a predetermined displacement in an optical axis direction.

2. Description of the Related Art Conventionally, in order to make a camera compact, it has been desired to shorten the overall length in the optical axis direction of a cam cylinder, which is one of components. However, since it is necessary to secure a certain amount of movement of the lens group, the movement amount of the lens group may be longer than the total length of the cam cylinder. In that case, there was a problem that the cam configuration was not realized.
Therefore, in order to shorten the overall length of the cam cylinder while ensuring the amount of movement of the lens group in the optical axis direction, a plurality of cam grooves with the same locus are provided on the inner peripheral surface of the cam cylinder, Among the follower pins to be combined, even if one follower pin is removed from the cam groove, the other follower pin moves along the cam groove to operate, and a lens moving mechanism for preventing complete removal is known (for example, , See Patent Document 1).
JP 2004-85932 A

However, in the lens moving mechanism described in Patent Document 1, it is necessary to provide cam grooves with the same locus, and high accuracy is required in the manufacturing stage. For this reason, if the plurality of cam grooves are not exactly the same locus, there is a problem that friction occurs between the follower pin and the cam groove, resulting in poor operation. In addition, if the cam groove is formed larger than the follower pin to provide a margin, there is a problem that zoom accuracy cannot be obtained.
Therefore, the present invention has been made in view of the above circumstances, and the operation of the outer protrusion (follower pin) and the cam groove is good, it is possible to prevent a malfunction due to a manufacturing error, and a smooth operation without deterioration in performance. It is an object of the present invention to provide a cam groove structure of a cam cylinder that can be obtained.

In order to solve the above problems, the invention of claim 1 is a lens group holding frame (second lens group holding frame) for holding a lens group (second lens group 31) as shown in FIGS. 100) the same trajectory that projects outwardly from the outer peripheral surface of 100) and engages and guides a plurality of outward projections (first follower pin P1 and second follower pin P2) that are substantially parallel to each other along the optical axis direction. A plurality of cam grooves (a front cam groove 101 and a rear cam groove 102) are formed in parallel with each other along the optical axis direction, and the cam cylinder 6A moves the lens group with a predetermined displacement in the optical axis direction. Cam groove structure,
The cam groove has an abutment area (first abutment area 103, second abutment area 105) that is engaged when the outer peripheral surface of the outward projection abuts against a wall surface of the cam groove; A non-contact area (first non-contact area 104, second non-contact area 106) formed so that the outer peripheral surface does not contact,
In the plurality of cam grooves, when the outer protrusion in one cam groove is disposed in the contact area, the outer protrusion in the other cam groove is disposed in the non-contact area,
When the outer projection arranged in the contact region in the one cam groove is removed from the contact region in accordance with the feeding / feeding operation of the cam cylinder, the non-contact in the other cam groove is detected. The outward projection disposed in the contact area is disposed in the contact area in the other cam groove, whereby the contact area is transferred.

  According to the first aspect of the present invention, the plurality of cam grooves having the same locus are formed so as to be substantially parallel to each other along the optical axis direction, and the cam groove includes the contact area and the non-contact area. When the outer protrusion in one cam groove is removed from the contact area in accordance with the loading / unloading operation, the outer protrusion in the non-contact area in the other cam groove is contacted in the other cam groove. By being arranged in the contact area, the contact area is transferred. Thus, the lens group and the lens group holding frame move with a predetermined displacement in the optical axis direction without stopping the rotation of the cam cylinder. Accordingly, since the two outward projections arranged along the optical axis direction do not contact the cam groove wall surface at the same time as in the prior art, the outer projections are in contact with the contact region of the cam groove one by one. The cam groove and the cam groove are good in operation, so that malfunction due to manufacturing errors can be prevented, and smooth operation can be obtained without deterioration in performance. Therefore, even when the amount of movement of the outward projection that is greater than or equal to the total thickness of the cam cylinder is required, it can be easily eliminated, and the total length of the cam cylinder can be further shortened. As a result, it is possible to reduce the size of an optical device such as a camera provided with such a cam cylinder.

The invention of claim 2 is the cam groove structure of the cam cylinder according to claim 1,
The lens group is retracted and extended by a step zoom lens system, and the contact area is transferred by the outward projection in an area where the zoom is not stopped as a step zoom.

  According to the second aspect of the present invention, since the contact area is transferred by the outward projection in the area where the step zoom is not stopped, the feeding / feeding operation is smoothly performed without affecting the photographing. be able to.

  According to the cam groove structure of the cam cylinder according to the present invention, since the outer protrusion is in contact with the contact area of the cam groove one by one, the operation of the outer protrusion and the cam groove is good, and the operation is due to manufacturing error. Defects can be prevented, and smooth operation can be obtained without performance degradation. Therefore, even when the stroke of the outward projection more than the total thickness of the cam cylinder is necessary, it can be easily eliminated, and the total length of the cam cylinder can be further shortened.

Embodiments of the present invention will be described below.
In this embodiment, a case where a lens barrel driving mechanism using a cam cylinder is applied to a digital camera exemplified as an example of an optical apparatus will be described. The digital camera has a step zoom function that can change the photographing magnification in six steps.
FIG. 1 is a cross-sectional view along the lens barrel drive mechanism according to the present embodiment and shows a case in a wide state (photographing state), and FIG. 2 is a cross-sectional view and shows a case in a tele state. Show. FIG. 3 is a development view showing the front and rear cam grooves 101 and 102 formed on the inner peripheral surface of the cam cylinder 6A.
In the following description, the state in which the digital camera can capture the widest range of subjects is referred to as the wide state (the state in which the image can be captured in the widest range), and the state in which the subject can be captured at the highest magnification in the narrowest range. Is referred to as a tele state (a state in which imaging can be performed in the narrowest range), and a state in which each member is housed and is most compact when the digital camera is not used is referred to as a housed state.

First, the main configuration of the lens barrel drive mechanism will be described with reference to FIGS.
The lens barrel drive mechanism 1 mainly includes a lens barrel body 10, a first lens frame 2, a shutter unit 8, a second lens frame 3, a third lens frame 4, a first rectilinear barrel 5A, a second rectilinear barrel 5B, and a cam. It is composed of a cylinder 6A, a rotary drive cylinder 6B, and a fixed cylinder 7. And each member 2-8 is hold | maintained in the lens-barrel main body 10 in the state in which the optical axis which passes along the approximate center of each member 2-8 substantially corresponds.

The lens barrel body 10 is provided on the outermost side, and the imaging unit 9 is attached to the rear end opening.
The fixed cylinder 7 is provided on the inner side of the lens barrel main body 10, and a first rectilinear groove 71 parallel to the helicoid along the optical axis direction is provided on the inner peripheral surface thereof.

The rotational drive cylinder 6B is provided inside the fixed cylinder 7, and a helicoid is provided on the outer peripheral surface thereof, and is screwed with the helicoid of the fixed cylinder 7. The helicoid on the outer periphery of the rotary drive cylinder 6B is provided with a gear portion (not shown) and is gear-coupled with a drive motor (not shown).
Further, a second rectilinear groove 61B parallel to the optical axis direction is provided on the inner peripheral surface of the rotary drive cylinder 6B.

  The first rectilinear cylinder 5A is provided on the inner side of the rotary drive cylinder 6B, and protrudes outward from the side wall portion at the rear end portion thereof, and engages with the first rectilinear groove 71 of the fixed cylinder 7. Is provided. As a result, while the rotational drive cylinder 6B rotates and moves back and forth along the optical axis direction, the first rectilinear cylinder 5A moves back and forth while being restricted from rotating in the circumferential direction.

The cam cylinder 6A is provided inside the rotary drive cylinder 6B, and a pin 61A that fits into the second rectilinear groove 61B on the inner peripheral surface of the rotary drive cylinder 6B is provided at the rear end portion of the outer peripheral face. The pin 61A is inserted into the first cam groove 52A of the first rectilinear cylinder 5A. Therefore, the rotation of the rotary drive cylinder 6B is transmitted to the cam cylinder 6A, and the cam cylinder 6A itself is moved back and forth along the optical axis direction by the first cam groove 52A.
Further, a second cam groove 62A that engages with the first frame portion 22 of the first lens frame 2 is formed on the outer peripheral surface of the cam cylinder 6A.

  Further, as shown in FIG. 3, the cam cylinder 6A is provided on the inner peripheral surface so as to protrude outward from the outer peripheral surface of the second lens group holding frame 100 provided in the shutter unit 8, which will be described later. Cam grooves 101 and 102 for engaging the first follower pin (outward protrusion) P1 and the second follower pin (outward protrusion) P2 arranged in two rows in parallel are substantially parallel along the optical axis direction. It is formed in two rows so that The front cam groove 101 formed forward in the optical axis direction and the rear cam groove 102 formed rearward have the same locus. That is, the front cam groove 101 and the rear cam groove 102 are formed to extend in the circumferential direction of the inner peripheral surface of the cam cylinder 6A, and the front cam groove 101 and the rear cam groove 102 are formed on the cam cylinder 6A. Three are formed in the circumferential direction of the inner circumferential surface.

  In FIG. 3, six first follower pins P1 are illustrated in one front cam groove 101. This is because the first follower pin P1 is moved when the cam cylinder 6A is moved in accordance with the feeding and feeding operations. It represents a trajectory. Similarly, six second follower pins P2 are shown in one rear cam groove 102, which also represents the locus of the second follower pin P2. Therefore, in practice, one front follower pin P1 and one second follower pin P2 are arranged in each of one front cam groove 101 and one rear cam groove 102, respectively.

The front cam groove 101 has a first contact area 103 in which the first follower pin P1 engages with an outer peripheral surface of the first follower pin P1 on a wall surface forming the front cam groove 101, and the first follower pin P1. And a first non-contact region 104 formed so that the outer peripheral surface does not contact. That is, the predetermined range in the longitudinal direction of the front cam groove 101 is the first non-contact area 104, and the other range is the first contact area 103.
The groove width of the first contact area 103 is formed slightly larger than the diameter of the first follower pin P1 so that the outer peripheral surface of the first follower pin P1 contacts, and the groove width of the first non-contact area 104 is The outer periphery of the first follower pin P1 is formed in such a size that a gap S is formed between the first follower pin P1 and the wall surface.

The rear cam groove 102 includes a second contact area 105 in which the outer surface of the second follower pin P2 comes into contact with a wall surface forming the rear cam groove 102, and the second follower pin P2 engages with the second follower pin P2. And a second non-contact region 106 formed so that the outer peripheral surface of P2 does not contact. That is, the predetermined range in the longitudinal direction of the rear cam groove 102 is the second non-contact area 106, and the other range is the second contact area 105.
The groove width of the second contact region 105 is formed slightly larger than the diameter of the second follower pin P2 so that the outer peripheral surface of the second follower pin P2 contacts, and the groove width of the second non-contact region 106 is The outer periphery of the second follower pin P2 is formed in such a size that a gap S is formed between the second follower pin P2 and the wall surface.

When the first follower pin P1 in the front cam groove 101 is disposed in the first contact area 103, the second follower pin P2 in the rear cam groove 102 is disposed in the second non-contact area 106. One of the follower pins comes into contact with each contact area.
When the first follower pin P1 disposed in the first contact area 103 in the front cam groove 101 is disengaged from the first contact area 103 in accordance with the feeding operation of the cam cylinder 6A, the rear cam groove 102 The second follower pin P2 disposed in the second non-contact area 106 is engaged with the rear cam groove 102 by being disposed in the second contact area 105 in the rear cam groove 102, and the contact area is transferred. Is done. Further, when the second follower pin P <b> 2 disposed in the second contact area 105 in the rear cam groove 102 is disengaged from the second contact area 105 with the retraction operation of the cam cylinder 6 </ b> A, the front cam groove 101. The first follower pin P <b> 1 disposed in the first non-contact area 104 is engaged with the front cam groove 101 by being disposed in the first contact area 103 in the front cam groove 101. Delivery takes place.
As a result of the delivery to each contact area in this way, the cam cylinder 6B rotates smoothly, and the delivery of the contact area is performed in an area where the zoom does not stop as a step zoom. Therefore, the operation is smooth without affecting the shooting and without degrading the performance.

  Note that the second cam groove 62A is formed deeper than the front cam groove 101 and the rear cam groove 102 in order to easily withstand the impact when the camera is dropped.

  The second rectilinear cylinder 5B is disposed in front of the first rectilinear cylinder 5A and is provided inside the rotational drive cylinder 6B. A fourth rectilinear groove 51B parallel to the optical axis direction is provided on the inner peripheral surface of the second rectilinear cylinder 5B.

The first lens frame 2 is provided on the inner side of the second rectilinear cylinder 5B, and holds the first lens group 21 at its front end. A side wall portion at the rear end portion of the first lens frame 2 is provided with a first frame portion 22 that penetrates the side wall portion and protrudes inward from the inner peripheral surface thereof. Further, a second rotation restricting portion 23 that protrudes outward and engages with the fourth rectilinear groove 51B of the second rectilinear cylinder 5B is provided on the side wall portion at the rear end portion of the first lens frame 2. As a result, the rotation of the first lens frame 2 in the circumferential direction is restricted and moves back and forth.
A caliper ring 24 and a barrier mechanism are attached to the front end portion of the first lens frame 2 where the first lens group 21 is provided.
The barrier mechanism includes a barrier drive ring and barrier blades 25 that are opened and closed by the barrier drive ring.

The shutter unit 8 is disposed behind the first lens frame 2 and is provided inside the cam cylinder 6A. The shutter unit 8 includes a shutter substrate 81 on which an exposure opening is formed, a shutter blade 83 that opens and closes or opens the exposure opening, and a drive source that drives the shutter blade 83.
The shutter substrate 81 is fixed to the front side of the second lens group holding frame 100 that engages with the rear end portion of the cam cylinder 6A. Further, a biasing means B using a coil spring that biases the shutter substrate 81 and the first lens frame 2 in a direction away from each other is provided.
Further, a third rotation restricting portion 84 is provided at the rear end portion of the second lens group holding frame 100 so that the side wall portion at the rear end portion protrudes outward and engages with the cam cylinder 6A. Therefore, the second lens group holding frame 100 moves back and forth while the movement in the circumferential direction is restricted by the third rotation restricting portion 84.
The second lens group holding frame 100 has a first side wall that extends through the side wall, protrudes outward from the outer peripheral surface thereof, and engages with the front cam groove 101 and the rear cam groove 102 of the cam cylinder 6A. A follower pin P1 and a second follower pin P2 are provided. The first follower pin P1 and the second follower pin P2 are each provided at predetermined intervals in the circumferential direction of the second lens group holding frame 100 (see FIG. 3).
Further, the driving source drives the shutter blade 83 based on a command from a control circuit (not shown) provided in the camera, thereby opening and closing the exposure opening or narrowing it to a predetermined aperture.
Further, the shutter unit 8 is provided with a slide moving means (not shown) for sliding up and down from a position where a second lens frame 3 described later is disposed in the optical path to a position where it is retracted outside the optical path.

  The second lens frame 3 is disposed behind the shutter unit 8 and holds the second lens group 31 at its front end. The outer periphery of the second lens frame 3 is held by the second lens group holding frame 100, and the drawing and feeding operation is performed as the second lens group holding frame 100 moves in the optical axis direction.

  The third lens frame 4 is disposed behind the second lens frame 3 and holds the third lens group 41 at its front end. A motor (not shown) for adjusting the position of the third lens group 41 is connected to the outer periphery of the third lens frame 4. As the motor rotates, the distance between the third lens group 41 and the image pickup unit 9 disposed behind the third lens group 41 is adjusted to achieve focus.

  The imaging unit 9 includes a receiving portion 91 attached to the inner peripheral rear end portion of the lens barrel body 10, a low-pass filter 92 fitted in the receiving portion 91, and an elastic body (not shown) at the rear portion of the low-pass filter 92. The provided image sensor 93 and a pressing plate for holding the image sensor 93 between the low-pass filter 92 are provided.

Next, the operation of the lens barrel drive mechanism 1 will be described.
Although not shown, when the driving force from the motor (not shown) is transmitted to the gear portion (not shown) of the rotation driving cylinder 6B to the lens barrel driving mechanism 1 in the housed state, the rotation driving cylinder 6B rotates. Along with the rotation of the rotation driving cylinder 6B, the first rotation restricting portion 51A of the first rectilinear cylinder 5A moves straight forward along the first rectilinear groove 71. At the same time, the rotation of the rotary drive cylinder 6B is transmitted to the pin 61A of the cam cylinder 6A, and the cam cylinder 6A advances straight forward along the first cam groove 52A of the first rectilinear cylinder 5A. With the rotation of the cam cylinder 6A, the third rotation restricting portion 84 also moves straight forward, and the first frame portion 22 of the first lens frame 2 moves straight along the second cam groove 62A.

  Here, the first follower pin P <b> 1 of the second lens group holding frame 100 is arranged in the first contact region 103 of the front cam groove 101, and its outer peripheral surface is in contact with and engaged with the front cam groove 101. . At this time, the second follower pin P <b> 2 is arranged so that the outer peripheral surface thereof does not contact the second non-contact region 106 of the rear cam groove 102. As the cam cylinder 6A rotates, the first follower pin P1 moves along the groove of the first contact region 103 of the front cam groove 101, and the second follower pin P2 is the second non-contact of the rear cam groove 102. It moves along the groove in the region 106. When the first follower pin P1 moves from the first contact area 103 to the first non-contact area 104, the second follower pin P2 moves from the second non-contact area 106 to the second contact area 105 ( (See the arrow I portion in FIG. 3). As described above, the first follower pin P1 is not stopped by the transfer of the contact region between the first follower pin P1 in the first contact region 103 and the second follower pin P2 in the second contact region 105. Moves in the first non-contact area 104, and the second follower pin P2 moves in the second contact area 105 and goes straight.

  At this time, the first rotation restricting portion 51A of the first rectilinear cylinder 5A is restricted from moving in the circumferential direction by the first rectilinear groove 71, and the second rotation restricting portion 23 is the fourth rectilinear groove 51B of the second rectilinear cylinder 5B. Since the third rotation restricting portion 84 is restricted from moving in the circumferential direction, the third rotation restricting portion 84 is restricted in the optical axis direction without rotating in synchronism with the rotation driving cylinder 6B or the cam cylinder 6A. Move to.

Thereafter, when the cam cylinder 6A rotates by a predetermined distance by the movement of the first and second follower pins P1 and P2 as described above, the first lens frame 2 is extended to be in the wide state shown in FIG. The first lens frame 2 is in the widened state and is in the most extended state. When the cam cylinder 6A is further rotated, the first lens frame 2 is extended once and then extended until it reaches the tele state (see FIG. 2). . At this time, the shutter unit 8 is extended forward by the guidance of the front cam groove 101 and the rear cam groove 102 by the first follower pin P1 and the second follower pin P2, and performs zooming by changing the group interval.
Further, a motor (not shown) adjusts the position of the third lens frame 4 and moves the third lens group 41 according to the positions of the first lens group 21 and the second lens group 31, so that the focus is imaged. It will fit part 9.

In the operation of returning from the tele state to the wide state and further storing the lens groups 21, 31, and 41, the rotation drive cylinder 6B and the cam cylinder 6A rotate in the opposite direction to that during the extension. By these rotations, the first lens frame 2 in the wide state is retracted by the guide of the second cam groove 62A. Further, the shutter unit 8 and the second lens frame 3 are retracted by the guidance of the front cam groove 101 and the rear cam groove 102, and the third rotation restricting portion 84 is also retracted simultaneously. Further, the first rectilinear cylinder 5 </ b> A is retracted by guiding the first rectilinear groove 71.
Here, with the rotation of the cam cylinder 6A, the second follower pin P2 in the second contact region 105 of the rear cam groove 102 moves along the second contact region 105, and the first non-contact of the front cam groove 101 is increased. The first follower pin P <b> 1 in the contact area 104 moves along the first non-contact area 104. When the second follower pin P2 moves from the second contact area 105 to the second non-contact area 106, the first follower pin P1 moves from the first non-contact area 104 to the first contact area 103 ( (See arrow II in FIG. 3). In this way, as in the feeding operation, the rotation is stopped by the transfer of the contact area between the first follower pin P1 in the first non-contact area 104 and the second follower pin P2 in the second contact area 105. Without doing so, the second follower pin P2 moves in the second non-contact area 106, and the first follower pin P1 moves in the first contact area 103 and goes straight.
Thereafter, the barrier blade 25 is closed at a predetermined position.

As described above, according to the embodiment of the present invention, the first and second follower pins P1 and P2 protruding from the outer peripheral surface of the second lens group holding frame 100 are engaged with and guided by the inner peripheral surface of the cam cylinder 6A. The front cam groove 101 and the rear cam groove 102 of the same locus are formed so as to be arranged substantially in parallel along the optical axis direction, and each cam groove 101, 102 is in contact with the outer peripheral surface of the follower pins P1, P2. The first follower pin P1 in the front cam groove 101 is provided with the first and second contact regions 103, 105 and the first and second non-contact regions 104, 106 that are not in contact with each other. When the second follower pin P2 in the second non-contact region 106 in the rear cam groove 102 is disposed in the second contact region 105 when the first contact region 103 is removed from the first contact region 103, Delivery is made. Accordingly, the second lens group 31 and the second lens group holding frame 100 move with a predetermined displacement without stopping the rotation of the cam cylinder 6A.
Therefore, even when the amount of movement of the follower pins P1 and P2 in the optical axis direction is required to be longer than the entire length of the cam barrel 6A, it can be easily handled. Furthermore, the overall length of the cam cylinder 6A can be shortened, and the camera can be miniaturized.

In addition, this invention is not limited to the said embodiment, In the range which does not deviate from the summary, it can change suitably.
For example, in the above embodiment, the six-stage zoom method is used, but a stepless zoom method mechanism may be used.

  In addition, the fixed cylinder 7 and the rotation driving cylinder 6B are driven by a helicoid structure, but the present invention is not limited to this and may be driven by a cam structure. In addition, in the above embodiment, the member driven by the cam structure may be driven by the helicoid structure.

  Furthermore, in the above embodiment, the three lens groups of the first lens group 21, the second lens group 31, and the third lens group 41 are provided, but a configuration including two lens groups may be used. A configuration including four or more lens groups may be used.

FIG. 5 is a cross-sectional view taken along the optical axis direction in the wide state of the lens barrel drive mechanism for illustrating an embodiment of the present invention. It is sectional drawing along the optical axis direction in the tele state of a lens-barrel drive mechanism. FIG. 6 is a development view showing cam grooves formed on the inner peripheral surface of the cam cylinder.

Explanation of symbols

6A Cam barrel 31 Second lens group (lens group)
100 Second lens group holding frame (lens group holding frame)
101 Front cam groove (cam groove)
102 Rear cam groove (cam groove)
103 First contact area (contact area)
104 First non-contact area (non-contact area)
105 Second contact area (contact area)
106 Second non-contact area (non-contact area)
P1 First follower pin (outward projection)
P2 Second follower pin (outward projection)

Claims (2)

A plurality of cams of the same locus that project outward from the outer peripheral surface of the lens group holding frame that holds the lens group and that are engaged with and guided by a plurality of outer protrusions that are arranged substantially parallel to each other along the optical axis direction. The groove is formed in a cam groove structure of a cam cylinder that is formed in parallel with each other along the optical axis direction and moves the lens group with a predetermined displacement in the optical axis direction.
The cam groove is formed such that a contact area engaged by an outer peripheral surface of the outer protrusion abuts on a wall surface forming the cam groove and an outer peripheral surface of the outer protrusion. A non-contact area
In the plurality of cam grooves, when the outer protrusion in one cam groove is disposed in the contact area, the outer protrusion in the other cam groove is disposed in the non-contact area,
When the outer projection arranged in the contact region in the one cam groove is removed from the contact region in accordance with the feeding / feeding operation of the cam cylinder, the non-contact in the other cam groove is detected. A cam groove structure of a cam cylinder, wherein an outer protrusion disposed in a contact area is disposed in the contact area in the other cam groove, whereby the contact area is transferred.   The lens group is subjected to a retraction / retraction operation by a step zoom lens system, and the contact region is transferred by the outer protrusion in a region where the step zoom is not stopped. Cam groove structure of cam cylinder.

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