JP2007219305A - Barrier mechanism and imaging device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a barrier mechanism that maintains stability of opening/closing operation of barrier blades and makes an image forming device radially compact, and also to provide the imaging device. <P>SOLUTION: A lens barrier comprises a barrier cover 1, a closing spring 2, a small barrier blade 3, a large barrier blade 4, an opening spring 5, and a barrier blade driving member 6. The large barrier blade 4 covers the majority of an opening part 13 of the barrier cover 1 when no photography is performed. The small barrier blade 3 covers the outside of a portion of the opening part 13 of the barrier cover 1 which is shielded by the large barrier blade 4 when no photography is performed. The large barrier blade 4 is provided with a cut part 45, and the small barrier blade 3 is provided with a projection part 34 which is engaged with the cut part 45 of the large barrier blade 4 to receive the large barrier blade 4 along an optical axis. The barrier blade driving mechanism 5 is provided with a cam surface 66, and a projection part 35 which abuts against the cam surface 66 is provided on the opposite side of the small barrier blade 3 from a subject side. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a barrier mechanism that protects a subject side surface of a lens mounted on an imaging apparatus such as a silver salt camera or a digital still camera, and an imaging apparatus.

  2. Description of the Related Art Conventionally, there is a camera that is configured to retract a lens barrel into a camera casing (non-collapsed state) during non-photographing and to extend a lens barrel from the front of the camera casing during photographing. This type of camera incorporates a lens barrier made up of one or two pairs of barrier blades that closes the lens front face when the lens is retracted to protect the lens and opens the lens front face when shooting. The lens barrier is generally configured to be opened and closed by a barrier blade driving member that is rotated in conjunction with the movement of the lens barrel in the optical axis direction and the rotation of the rotating cylinder.

As for the lens barrier, the following technique has been proposed (see, for example, Patent Document 1). In the lens barrier described in Patent Document 1, the shapes of the tip portions of the pair of thin plate-like barrier blades are extended, and part of the barrier blades always overlap when the lens barrier is closed, opened, or in the middle of opening and closing. The structure is as follows. Thus, the barrier blades can be surely overlapped without contacting each other when the lens barrier is closed.
JP 2000-231137 A

  However, in the conventional lens barrier structure, it is necessary to extend the tip of the barrier blade extremely long in order to allow the barrier blades to overlap even when the lens barrier is open. For this reason, in addition to the blade-shaped portion that forms the minimum necessary area for closing the opening of the lens barrel when the lens barrier is closed, a space corresponding to the length of the tip of the barrier blade is extended. As a result, the degree of freedom in design is narrowed, which may hinder the miniaturization of the camera. In addition, the shape of the barrier blade that extends the tip extremely long has a low possibility of being molded by a mold, and may be an unstable part that is easily deformed even by sheet metal.

  In addition to the lens barrier with the long tip of the barrier blade as described above, a lens barrier with a four-blade structure that opens and closes by arranging two large barrier blades and two small barrier blades on the same plane is also practical. It has become. However, the lens barrier with a four-blade structure has a problem that a frictional force is generated at the sliding portion between the large barrier blade and the small barrier blade, which causes a defective opening / closing operation of the lens barrier.

  An object of the present invention is to provide a barrier mechanism and an imaging apparatus that can maintain the stability of the opening / closing operation of the barrier blades and can downsize the imaging apparatus in the radial direction.

  In order to achieve the above-described object, the barrier mechanism of the present invention is disposed on the subject side of the lens barrel holding the photographing optical component, and rotates about a cover member having an opening and an axis parallel to the optical axis. A first barrier blade that covers the portion including at least the center of the opening of the cover member at the time of non-photographing, and is arranged to be rotatable about an axis parallel to the optical axis. A second barrier blade that engages with the blade and covers the outside of the shielding portion of the opening of the cover member by the first barrier blade during non-photographing, and between the lens barrel and the cover member And a barrier blade driving member that is engaged with the lens barrel so as to be rotatable about an optical axis and that is engaged with the first barrier blade, Providing a notch, the second barrier blade Characterized in that a receiving portion for receiving said notch engages the first barrier blade of the first barrier blade in the optical axis direction.

  According to the present invention, the first barrier blade is provided with a notch, and the second barrier blade is provided with a receiving portion that engages with the notch of the first barrier blade. It becomes a receiver in the optical axis direction of the first barrier blade. This makes it possible to maintain the stability of the opening and closing operations of the first and second barrier blades.

  Further, at the time of non-photographing, the first barrier blade covers a portion including at least the center of the opening of the cover member, and the second barrier blade covers the outside of the shielding portion of the opening of the cover member by the first barrier blade. . Thereby, the area formed by the first and second barrier blades may be a minimum necessary area for covering the opening of the cover member, and the imaging apparatus can be downsized in the radial direction.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is an exploded perspective view showing a configuration of a lens barrier and a first group barrel that are attached to a camera as an imaging apparatus according to an embodiment of the present invention. FIG. 2 is a front view showing a closed state of the lens barrier. FIG. 3 is a front view showing an open state of the lens barrier. FIG. 4 is a cross-sectional view showing the internal structure of the lens barrier and the first group barrel along the line AA in FIG.

  1 to 4, the lens barrier includes a barrier cover 1, a closing spring 2, a small barrier blade 3, a large barrier blade 4, an opening spring 5, and a barrier blade driving member 6. The first lens barrel 7 is a member constituting a part of a lens barrel attached to the camera, and holds a lens 8. The closing spring 2 is a spring hung between the barrier small blade 3 and the barrier large blade 4. The opening spring 5 is a spring hung between the barrier blade driving member 6 and the first group lens barrel 7. The closing spring 2, the small barrier blade 3, the large barrier blade 4, and the opening spring 5 are arranged at a rotationally symmetric position of 180 degrees around the optical axis.

  Hereinafter, the configuration of the lens barrier and its opening / closing mechanism will be described in detail.

  The first group lens barrel 7 includes projecting portions 71 and 72, a spring hooking portion 73, shafts 74 and 75, a front end plate portion (hereinafter referred to as a flange portion) 77, and an outer diameter portion 78. A barrier blade driving member 6 is disposed on the subject side of the flange portion 77 of the first group barrel 7. An opening spring 5 is hung between a spring hooking portion 64 (described later) of the barrier blade driving member 6 and a spring hooking portion 73 of the first group barrel 7 (see FIG. 2). The barrier spring driving member 6 is urged counterclockwise by the opening spring 5 when viewed from the front.

  The barrier blade driving member 6 includes a plurality of rail portions 61, a protruding portion 62, an engaging portion 63, a spring hook portion 64, and an inner diameter portion 65. The inner diameter portion 65 of the barrier blade driving member 6 is fitted with the outer diameter portion 78 of the first group barrel 7. Thereby, the barrier blade driving member 6 is rotatable around the optical axis. The protrusion 62 of the barrier blade driving member 6 extends through the flange 77 of the first group barrel 7 to the imaging side (opposite to the subject side) and is disposed inside the first group barrel 7 (not shown). It contacts with the member. Thereby, the barrier blade drive member 6 can rotate clockwise.

  The barrier small blade 3 includes a shaft hole 31, a spring hooking portion 32, a sliding portion 33, a protruding portion 34, and a protruding portion 35 (see FIG. 5). The large barrier blade 4 includes a shaft hole 41, a spring hook 42, a protrusion 43 (see FIG. 5), a sliding part 44, and a notch 45. The large barrier blade 4 covers most of the opening 13 of the barrier cover 1 when the lens barrel is retracted (not photographed). The barrier small blade 3 covers the outside of the shielding portion by the large barrier blade 4 in the opening 13 of the barrier cover 1 (diagonal portion of the opening 13) when the lens barrel is retracted.

  The barrier small blade 3 and the barrier large blade 4 are disposed in the same plane and are disposed on the subject side of the barrier blade driving member 6. The barrier small blade 3 and the barrier large blade 4 are configured to be slidable along the rail surface of the rail portion 61 of the barrier blade driving member 6 and protect the lens 8 when retracted. The shaft hole 31 of the barrier small blade 3 is fitted to the shaft 74 of the first group lens barrel 7, and the shaft hole 41 of the barrier large blade 4 is fitted to the shaft 75 of the first group lens barrel 7. Thereby, the barrier small blade 3 and the barrier large blade 4 can rotate around the shaft 74 and the shaft 75 parallel to the optical axis, respectively.

  The closing spring 2 is hung between the spring hooking portion 32 of the barrier small blade 3 and the spring hooking portion 42 of the barrier large blade 4 (see FIGS. 2 and 3). The closing spring 2 urges the barrier small blade 3 and the barrier large blade 4 in the closing direction. The protrusion 43 of the large barrier blade 4 is engaged with the engaging portion 63 of the barrier blade driving member 6 (see FIG. 5). Accordingly, when the barrier blade driving member 6 rotates counterclockwise, the large barrier blade 4 rotates clockwise about the shaft 75. Conversely, when the barrier blade driving member 6 rotates in the clockwise direction, the engagement between the protrusion 43 of the large barrier blade 4 and the engaging portion 63 of the barrier blade driving member 6 is released, and the closing force of the closing spring 2 The barrier large blade 4 rotates counterclockwise.

  The barrier cover 1 includes protrusions 11 and 12 and an opening 13. The barrier cover 1 is disposed on the subject side of the barrier small blade 3 and the barrier large blade 4 and protects the lens 8 together with the barrier small blade 3 and the barrier large blade 4. The barrier cover 1 is assembled so that the protrusions 11 and 12 enter the imaging side (opposite to the subject side) of the protrusions 71 and 72 provided on the first group barrel 7, respectively. Thereby, the barrier cover 1 is fixed to the first group barrel 7 by the bayonet method.

  Next, the operation of the lens barrier mounted on the camera of the present embodiment having the above-described configuration will be described for each case when the camera is not shooting and when shooting.

  When the camera is not photographing, the lens barrier is in the closed state shown in FIG. In the closed state of FIG. 2, a member (not shown) inside the first group barrel 7 is in contact with the protrusion 62 of the barrier blade driving member 6. Accordingly, the barrier blade driving member 6 is rotated clockwise while charging the opening force of the opening spring 5.

  At this time, the barrier blade driving member 6 rotates to a phase where the protrusion 43 of the barrier large blade 4 and the engaging portion 63 of the barrier blade driving member 6 are sufficiently separated. Thereby, only the closing force of the closing spring 2 and the closing force received from the barrier small blade 3 are applied to the large barrier blade 4, so that the lens barrier is kept closed. Since the opening 13 of the barrier cover 1 is completely blocked by the barrier small blade 3 and the barrier large blade 4, the lens 8 is protected.

  On the other hand, the lens barrier is in the open state shown in FIG. In the open state of FIG. 3, a member (not shown) inside the first group barrel 7 that is in contact with the protrusion 62 of the barrier blade driving member 6 in the closed state of FIG. 2 is retracted. As a result, contact between a member (not shown) inside the first group barrel 7 and the protrusion 62 of the barrier blade driving member 6 is released. Accordingly, the barrier blade driving member 6 is rotated counterclockwise by the opening force of the opening spring 5.

  At this time, the engagement portion 63 of the barrier blade driving member 6 abuts on the protrusion 43 of the barrier large blade 4 to rotate the barrier large blade 4 clockwise about the shaft 75, thereby opening the barrier large blade 4. It is. Due to the opening force of the large barrier blade 4, the sliding portion 44 of the large barrier blade 4 spreads the sliding portion 33 of the small barrier blade 3. As a result, the barrier blade 3 rotates counterclockwise about the shaft 74, so that the lens barrier is kept open. By completely retracting the barrier small blade 3 and the barrier large blade 4 from the opening 13 of the barrier cover 1, it becomes possible to take a picture.

  As shown in FIGS. 3 and 4, the barrier small blade 3 and the barrier large blade 4 are respectively provided with a protrusion 34 and a notch 45 for increasing the sliding stability of the barrier small blade 3 and the barrier large blade 4. Is formed. The protrusion 34 of the barrier small blade 3 is configured to enter the notch 45 of the large barrier blade 4 (FIG. 4). Thereby, the barrier small blade 3 receives the barrier large blade 4 in the optical axis direction at any timing of opening and closing of the barrier small blade 3 and the barrier large blade 4.

  As shown in FIGS. 2 and 4, in the closed state of the lens barrier, the receiving portion of the barrier large blade 4 in the optical axis direction by the rail portion 61 of the barrier blade driving member 6 is only the root of the barrier large blade 4. It becomes. On the other hand, the stable projection 34 of the barrier small blade 3 that receives the entire barrier small blade 3 by the rail portion 61 of the barrier blade driving member 6 serves as the receiving end of the large barrier blade 4 (FIG. 4). Thereby, even when the barrier large blade 4 receives an external force, the closed state of the lens barrier is not destroyed.

  Next, a mechanism for shifting the closing timing of the barrier small blade 3 and the barrier large blade 4 in the lens barrier of the present embodiment will be described.

  FIG. 5 is a perspective view showing the barrier small blade 3, the barrier large blade 4, and the barrier blade driving member 6 in the open state of the lens barrier. FIG. 6 is a front view showing the state of FIG. 5 as viewed from the front. FIG. 7 is a front view showing a state in which only the barrier large blade 4 is slightly closed in the configuration of FIG. FIG. 8 is a front view showing a closed state of the lens barrier in the configuration of FIG. FIG. 9 is a characteristic diagram (conventional type) schematically showing the closing timing of the barrier blades. FIG. 10 is a characteristic diagram (barrier small blade delay type) schematically showing the closing timing of the barrier blades.

  5 to 10, as described above, the transition from the open state to the closed state of the lens barrier is performed as follows. In FIG. 6, the barrier blade driving member 6 rotates in the clockwise direction, so that the barrier large blade 4 rotates counterclockwise about the axis while maintaining the engagement between the engaging portion 63 and the protrusion 43 of the barrier large blade 4. The above transition is performed. At that time, the barrier small blade 3 follows the movement of the barrier large blade 4 and rotates clockwise about the axis.

  During the transition from the open state to the closed state of the lens barrier, the barrier large blade 4 always rotates while rubbing against the barrier small blade 3, and therefore receives a frictional force from the barrier small blade 3 at the tip. For this reason, the slidability of the barrier small blade 3 and the barrier large blade 4 may be hindered. In particular, receiving a force opposite to the closing direction at the beginning of the movement of the large barrier blade 4 is mechanically disadvantageous for a large barrier mechanism such as the large barrier blade 4 having a long distance from the rotation axis to the action point. is there.

  Therefore, as shown in FIG. 5, the protrusion 35 is provided on the imaging side of the barrier small blade 3 (opposite the subject side), and the cam surface 66 is provided on the side surface of the rail portion 61 of the barrier blade driving member 6. Thereby, for a while after the transition from the open state to the closed state of the lens barrier starts, the protrusion 35 of the barrier small blade 3 is brought into contact with the cam surface 66 of the barrier blade driving member 6 so that the barrier small blade 3 is moved. Keep it in a closed position.

  FIG. 6 shows a state in which the projection 35 of the barrier small blade 3 and the cam surface 66 of the barrier blade driving member 6 are in contact with each other when the lens barrier is open. When the lens barrier closing operation is started, as shown in FIG. 7, the barrier blade driving member 6 is slightly rotated clockwise. At this time, since the projection 35 of the barrier small blade 3 is still in contact with the cam surface 66 of the barrier blade driving member 6, the barrier small blade 3 is maintained as it is. Therefore, only the barrier large blade 4 rotates in the closing direction while the barrier small blade 3 is fixed. For this reason, a gap is formed between the barrier large blade 4 and the barrier small blade 3, and the barrier large blade 4 does not receive a frictional force from the barrier small blade 3 as long as it is separated.

  Further, when the lens barrier closing operation proceeds and the barrier blade driving member 6 rotates in the clockwise direction, the contact between the projection 35 of the barrier small blade 3 and the cam surface 66 of the barrier blade driving member 6 is released. Along with this, the barrier small blade 3 rotates at a stretch until it comes into contact with the large barrier blade 4 by the spring force of the closing spring 2 hung between the large barrier blade 4 and the small barrier blade 3. Thereafter, the protrusion 35 of the barrier small blade 3 is separated from the cam surface 66 of the barrier blade driving member 6 until the lens barrier is closed. Since the barrier small blade 3 receives only the force in the closing direction by the closing spring 2, the barrier small blade 3 follows the closing operation of the barrier large blade 4.

  FIG. 8 shows a closed state of the lens barrier. The protrusion 35 of the barrier small blade 3 is far away from the cam surface 66 of the barrier blade driving member 6, and the barrier small blade 3 does not receive any action from the barrier blade driving member 6. Therefore, even when the barrier blade driving member 6 starts to rotate counterclockwise at the stage where the transition from the closed state to the open state of the lens barrier is started, the barrier small blade 3 maintains a smooth operation.

  9 and 10 are graphs showing the operation described above in a simplified manner. FIG. 9 shows the closing timing of the barrier blade when the protrusion 35 of the barrier small blade 3 is not provided. FIG. 10 shows the closing timing of the barrier blades when the protrusions 35 of the barrier blades 3 are present. 9 and 10, the horizontal axis represents the time t required for the lens barrier closing operation. The vertical axis represents the rotation angle α when the closed state of the barrier small blade 3 and the barrier large blade 4 is 0 degree.

  Although FIG. 9 shows a conventional type, in order to make a comparison with FIG. 10 (this embodiment), the barrier small blade and the barrier large blade in FIG. 9 are given the same reference numerals as in this embodiment. It shall be.

  In FIG. 9, time t1 is the transition start time from the open state of the lens barrier to the closed state. It is assumed that the behavior shown in the figure is simply shown until the lens barrier is closed at time t2. The rotation angle α1 is the rotation angle of the barrier small blade 3 in the open state, and the rotation angle α2 is the rotation angle of the barrier large blade 4 in the open state.

  When the barrier small blade 3 always follows and closes the barrier large blade 4, the barrier small blade 3 and the barrier large blade 4 are smoothly closed between time t1 and time t2, as shown in FIG. However, a frictional force acts between the barrier small blade 3 and the barrier large blade 4 in all processes.

  FIG. 10 shows a state in which the movement of the barrier small blade 3 is restricted by the cam surface 66 of the barrier blade driving member 6 until time t3 (time for keeping the barrier small blade 3 in a fixed position). During this time, the barrier blade driving member 6 continues to rotate in the clockwise direction, but the cam surface 66 that abuts the projection 35 of the barrier small blade 3 continues to maintain the state shown in FIG. At the moment when the protrusion 35 of the barrier small blade 3 is separated from the cam surface 66 of the barrier blade driving member 6 and the contact is released, the barrier small blade 3 rapidly rotates to the position of the barrier large blade 4. After that, the barrier small blade 3 follows the rotation of the barrier large blade 4 and exhibits the same behavior as FIG.

  The time t3 for keeping the barrier small blade 3 in place can be adjusted by the spline of the cam surface 66 of the barrier blade driving member 6. However, it is desirable to set the time t3 for keeping the barrier small blade 3 in a fixed position within the time until the contact portion between the barrier small blade 3 and the barrier large blade 4 reaches the opening 13 of the barrier cover 1.

  As described above, according to the present embodiment, the barrier large blade 4 is provided with the notch portion 45, and the barrier small blade 3 is engaged with the notch portion 45 of the barrier large blade 4 so that the barrier large blade 4 is engaged. Is provided in the optical axis direction. By nesting the barrier small blades 3 and the barrier large blades 4, the barrier small blades 3 always receive the barrier large blades 4 in the optical axis direction. As a result, it is possible to prevent irregular movement (tilting) of the barrier small blade 3 and the barrier large blade 4 and dropping of the barrier small blade 3 and the barrier large blade 4 from the rail portion 61 of the barrier blade driving member 6. This makes it possible to maintain the stability of the lens barrier opening / closing operation.

  During non-photographing, the barrier large blade 4 covers most of the opening 13 of the barrier cover 1, and the barrier small blade 3 covers the outside of the shielding portion of the barrier large blade 4 in the opening 13 of the barrier cover 1. . As a result, the total area formed by the barrier small blades 3 and the large barrier blades 4 in the closed state of the lens barrier may be the minimum necessary area that covers the opening 13 of the barrier cover 1. As a result, it is possible to improve the degree of freedom in design other than the space occupied by the shape of the barrier small blade 3 and the barrier large blade 4 in the lens barrel, and the camera can be downsized in the radial direction. .

  Further, a cam surface 66 is provided on the side surface of the rail portion 61 of the barrier blade driving member 6, and a protrusion 35 that contacts the cam surface 66 of the barrier blade driving member 6 is provided on the side opposite to the subject side of the barrier small blade 3. Provide. For a while from the start of the transition from the open state to the closed state of the lens barrier, the protrusion 35 of the barrier small blade 3 is brought into contact with the cam surface 66 of the barrier blade driving member 6 so that the barrier small blade 3 is in the closed position. Keep on. In other words, the closing timing of the barrier small blade 3 is slightly delayed from the closing timing of the barrier large blade 4. Thereby, since it is possible to prevent the frictional force between the barrier small blades 3 and the large barrier blades 4 from being generated, it is possible to maintain the stability of the opening / closing operation of the lens barrier as described above.

  Further, the cam surface 66 of the barrier blade driving member 6 with which the protruding portion 35 of the barrier small blade 3 abuts uses the side surface of the rail portion 61 of the barrier blade driving member 6. As a result, it is not necessary to provide a separate member as a configuration for delaying the closing timing of the barrier small blade 3. This makes it possible to maintain the stability of the lens barrier opening / closing operation as described above without increasing the number of components.

[Other embodiments]
In the above embodiment, the type of camera provided with the lens barrier is not mentioned, but it is not limited to a specific camera. The lens barrier of the present invention can be applied to various cameras including a silver salt camera and a digital still camera.

It is a disassembled perspective view which shows the structure of the lens barrier with which the camera as an imaging device which concerns on embodiment of this invention, and a 1 group lens-barrel. It is a front view which shows the closed state of a lens barrier. It is a front view which shows the open state of a lens barrier. FIG. 3 is a cross-sectional view showing an internal structure of a lens barrier and a first group barrel along the line AA in FIG. 2. It is a perspective view which shows the barrier small blade in the open state of a lens barrier, a barrier large blade, and a barrier blade drive member. It is a front view which shows the state which looked at the structure of FIG. 5 from the front. FIG. 6 is a front view showing a state where only the barrier large blades are slightly closed in the configuration of FIG. 5. It is a front view which shows the closed state of a lens barrier in the structure of FIG. It is a characteristic view (conventional type) which shows simply the closing timing of a barrier blade. It is a characteristic view (barrier small blade delay type) which shows the closing timing of a barrier blade simply.

Explanation of symbols

1 Barrier cover (cover member)
13 Opening (Opening)
2 Closing spring 3 Barrier blade (second barrier blade)
34 Protrusion (receiving part)
35 Protrusion (protrusion)
4 barrier large feathers (first barrier feather)
45 Notch (notch)
5 Opening spring 6 Barrier blade drive member (barrier blade drive member)
61 Rail section (rail section)
66 Cam surface (cam surface)
7 Group of lens barrels
77 Flange 8 Lens (Optical components for photography)

Claims (5)

A cover member that is disposed on the subject side of the lens barrel that holds the optical components for photographing and has an opening;
A first barrier blade disposed so as to be rotatable about an axis parallel to the optical axis and covering a portion including at least the center of the opening of the cover member at the time of non-photographing;
It is disposed so as to be rotatable about an axis parallel to the optical axis, is engaged with the first barrier blade, and is outside the shielding portion by the first barrier blade at the opening of the cover member when not photographing. A second barrier blade covering
A barrier blade driving member that is disposed between the lens barrel and the cover member, is engaged with the lens barrel so as to be rotatable about an optical axis, and is engaged with the first barrier blade; Prepared,
The first barrier blade is provided with a notch,
A barrier mechanism, wherein the second barrier blade is provided with a receiving portion that engages with the notch portion of the first barrier blade and receives the first barrier blade in the optical axis direction. A cam surface is provided on a part of the barrier blade driving member,
The barrier mechanism according to claim 1, wherein a protrusion that contacts the cam surface of the barrier blade driving member is provided on the opposite side of the second barrier blade from the subject side. Provided on the subject side of the barrier blade driving member is a rail portion on which the first barrier blade and the second barrier blade slide;
The barrier mechanism according to claim 1 or 2, wherein a side surface of the rail portion is used as the cam surface of the barrier blade driving member.   The cam surface of the barrier blade driving member and the second barrier blade at the time of transition from the open state to the closed state of the opening of the cover member by the first barrier blade and the second barrier blade. The barrier mechanism according to any one of claims 1 to 3, wherein the movement of the second barrier blade is restricted by the contact of the protrusion.   An imaging apparatus comprising the barrier mechanism according to claim 1.

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