JP7600812B2 - Aperture unit and lens barrel - Google Patents

Description

Regarding aperture units and lens barrels.

The lens barrel is provided with an aperture unit (see, for example, Patent Document 1). There is a demand for improving the aperture accuracy of the aperture unit.

Japanese Unexamined Patent Publication No. 4-128727

According to a first aspect, the lens includes a plurality of aperture blades, each having a first protrusion and a second protrusion, a first opening member having a plurality of grooves that engage with each of the first protrusions, a second opening member having a plurality of holes that engage with each of the second protrusions, and a biasing portion that biases the first protrusion against the groove that engages with the first protrusion , wherein a portion of the biasing portion is disposed between the aperture blade and the first opening member, and another portion of the biasing portion is disposed on the opposite side of the first opening member from the aperture blade .

According to the second aspect, the lens barrel is provided with the aperture unit.

The configuration of the embodiments described below may be modified as appropriate, and at least a portion of the configuration may be replaced with other components. Furthermore, components that are not specifically limited in their placement may be placed in any position that achieves their function, not limited to the placement disclosed in the embodiments.

FIG. 1 is a diagram showing a camera including a lens barrel and a camera body according to an embodiment. FIG. 2 is an exploded perspective view of the aperture unit according to the embodiment, as viewed from the camera body side. FIG. 3 is an exploded perspective view of the aperture unit according to the embodiment, as viewed from the subject side. FIG. 4A is a plan view of the cam plate as viewed from the camera body side, and FIG. 4B is a plan view of the cam plate as viewed from the subject side. FIG. 5(A) is an oblique view of the urging portion, FIG. 5(B) is an oblique view for explaining the attachment of the urging portion to the cam plate, and FIG. 5(C) is a plan view showing the state in which the urging portion is attached to the cam plate. Figure 6(A) is a diagram for explaining the relationship between the cam groove, the biasing portion, and the cam follower of the aperture blade in the small aperture state, and Figure 6(B) is a diagram for explaining the relationship between the cam groove, the biasing portion, and the cam follower of the aperture blade in the open state.

The lens barrel according to one embodiment will be described below with reference to the drawings. In order to facilitate explanation and understanding, an XYZ Cartesian coordinate system is provided in the drawings shown below. In this coordinate system, the direction from the subject toward the camera body 10 in the camera position (hereinafter referred to as the normal position) when the photographer takes a landscape image with the optical axis OA horizontal is defined as the +X direction. In addition, the direction toward the right side as viewed from the camera body 10 in the normal position is defined as the +Y direction. In addition, the direction toward the upper side in the normal position is defined as the +Z direction. Note that the scale of the shape, length, thickness, etc. of each part shown in the embodiment does not necessarily match the actual product, and parts not necessary for explanation are appropriately omitted or simplified.

Fig. 1 is a schematic diagram of a camera 1 including a lens barrel 20 according to this embodiment and a camera body 10. The camera 1 includes the camera body 10 and the lens barrel 20 that is detachable from the camera body 10. Note that the lens barrel 20 and the camera body 10 may be integrated.

Lens barrel 20 includes lenses 21 and 22 as optical members that refract incident subject light to form a subject image on the exit side, and aperture unit 30 that adjusts the aperture. In FIG. 1, lenses 21 and 22 are depicted as single lenses, but lenses 21 and 22 may be a lens group including multiple lenses. Furthermore, lens barrel 20 may have only one of lenses 21 and 22.

The camera body 10 is equipped with an image sensor 12 that captures the subject image formed by the lens 21 and converts it into an electrical signal.

Next, the configuration of the aperture unit 30 in this embodiment will be described. Figure 2 is an exploded perspective view of the aperture unit 30 according to one embodiment as seen from the camera body side, and Figure 3 is an exploded perspective view of the aperture unit 30 as seen from the subject side.

The aperture unit 30 is an aperture device, and as shown in Figures 2 and 3, includes an aperture member 31, a rotating member 32, a number of aperture blades 33 (only one is shown in Figure 2), a cam plate 34, a number of biasing members 35 (only one is shown in Figure 2), and a stepping motor 36.

The opening member 31 is an annular member having a fitting opening 311 in the center. In addition, a stepping motor 36 is attached to the +X side of the opening member 31.

The rotating member 32 is an annular member with an opening in the center, and has an annular protrusion 321 in the center that fits into the fitting opening 311 of the opening member 31. A segment gear 322 is formed on the outer edge of the rotating member 32, and meshes with a pinion gear 361 attached to the rotating shaft of the stepping motor 36. The rotating member 32 also has holes 323 in the same number as the number of diaphragm blades 33. A support portion 331 for the diaphragm blade 33, which will be described later, is inserted into each hole 323.

Support parts 331 are provided on the +X side of the multiple aperture blades 33, and cam followers 332 are provided on the -X side. The support parts 331 are inserted into holes 323 provided in the rotating member 32, and the cam followers 332 are inserted into cam grooves 341 provided in the cam plate 34.

The cam plate 34 is an annular member with an opening in the center, and has the same number of cam grooves 341 as the number of diaphragm blades 33. As described above, the cam followers 332 of the diaphragm blades 33 are inserted into the cam grooves 341. The cam grooves 341 may be through grooves that pass through the cam plate 34, or they may be grooves that do not pass through the cam plate 34.

When an instruction to change the F-number is given from the camera body 10, the stepping motor 36 is rotated, and the rotating member 32 having a segment gear 322 meshing with a pinion gear 361 attached to the rotating shaft of the stepping motor 36 rotates. Since the support portion 331 of the diaphragm blade 33 is inserted into a hole 323 formed in the rotating member 32, when the rotating member 32 rotates around the optical axis OA, the diaphragm blade 33 also rotates around the optical axis OA. Since the cam follower 332 of the diaphragm blade 33 is inserted into the cam groove 341 of the cam plate 34, the cam follower 332 of the diaphragm blade 33 rotates along the cam groove 341 with the support portion 331 as a fulcrum. In this way, the size of the aperture (diaphragm aperture) 37 (see FIG. 1) of the iris diaphragm can be adjusted by the multiple diaphragm blades 33.

Next, the configuration of the cam plate 34 will be described in more detail. Figure 4(A) is a plan view of the cam plate 34 as seen from the camera body 10 side, and Figure 4(B) is a plan view of the cam plate 34 as seen from the subject side.

As shown in FIG. 4A, the +X side of the cam plate 34 has cam grooves 341 formed in the same number as the number of aperture blades 33. In this embodiment, the cam grooves 341 are linear, but may be curved.

The cam groove 341 has a pair of opposing walls 341a and 341b. In this embodiment, the cam follower 332 of the aperture blade 33 inserted into the cam groove 341 moves while being guided by the wall 341a. The wall 341a is closer to the optical axis OA than the wall 341b. A clearance (gap) is provided between the cam groove 341 and the cam follower 332 of the aperture blade 33 to accommodate changes in temperature and humidity. This clearance causes play between the cam groove 341 and the aperture blade 33. Therefore, the aperture unit 30 according to this embodiment is provided with a biasing portion 35 that biases the cam follower 332 against the wall 341a of the cam groove 341 in order to suppress the play.

Figure 5 (A) is a perspective view showing an example of the biasing portion 35. In this embodiment, the biasing portion 35 is a torsion coil spring having a coil portion 351, a first arm 352, and a second arm 353.

In this embodiment, the urging unit 35 is attached to the cam plate 34. FIG. 5B is a perspective view for explaining the attachment of the urging unit 35 to the cam plate 34. As shown in FIG. 5B, the coil portion 351 of the urging unit 35 is engaged with the coil engagement portion 343 formed on the -X side of the cam plate 34, and the first arm 352 is passed through a through hole 342 penetrating the cam plate 34, with a part of it being disposed on the +X side. The second arm 353 is engaged with the arm engagement portion 344 formed on the -X side of the cam plate 34. That is, a part of the urging unit 35 (a part of the first arm 352) is disposed between the cam plate 34 and the aperture blade 33, and the other part of the urging unit 35 (the second arm 353) is disposed on the opposite side (-X side) of the cam plate 34 to the aperture blade 33.

Figure 5 (C) is a plan view showing the state in which the urging unit 35 is attached to the cam plate 34. As shown in Figure 5 (C), the first arm 352 of the urging unit 35 attached to the cam plate 34 is approximately parallel to the linear cam groove 341. The cam follower 332 of the assembled diaphragm blade 33 is inserted into the cam groove 341 of the cam plate 34 to which the urging unit 35 is attached in this manner. When inserting the cam follower 332 into the cam groove 341, the first arm 352 is flipped up as shown by the arrow A11 using a jig or the like. This creates a space between the wall 341a and the flipped up first arm 352, so that the cam follower 332 of the diaphragm blade 33 can be easily inserted into the space. Then, after inserting the cam follower 332, the flipped up first arm 352 is returned to its original position, so that the first arm 352 of the urging unit 35 can urge the cam follower 332. By doing this, in this embodiment, the cam followers 332 of the assembled aperture blades 33 can be inserted at once into the multiple cam grooves 341 of the cam plate 34 to which the biasing portion 35 is attached, making it easy to assemble the aperture unit 30.

Furthermore, if all of the biasing parts 35 are provided between the cam plate 34 and the aperture blade 33, a load is applied directly to the aperture blade 33, which may cause the aperture blade 33 to twist. On the other hand, if the biasing parts 35 are arranged as in this embodiment, the biasing parts 35 press the cam followers 332, which reduces the possibility of the aperture blade 33 twisting. The cam followers 332 have a higher rigidity than the aperture blade 33, so the cam followers 332 are unlikely to deform.

In addition, when all of the biasing portion 35 is provided between the cam plate 34 and the aperture blade 33, in order to bring the first arm 352 into contact with the cam follower 332 and to lock the second arm 353, the cam plate 34 needs to be thicker than in the present embodiment. Therefore, by arranging a part of the first arm 352 between the cam plate 34 and the aperture blade 33 and arranging the second arm 353 on the opposite side (-X side) of the cam plate 34 to the aperture blade 33, the cam plate 34 can be made thinner than when all of the biasing portion 35 is provided between the cam plate 34 and the aperture blade 33, and the cam plate 34 and therefore the aperture unit 30 can be made lighter.

Next, we will explain the relationship between the cam groove 341 of the cam plate 34, the biasing portion 35, and the cam follower 332 of the aperture blade 33 in the aperture unit 30 after assembly.

Figures 6(A) and 6(B) are diagrams for explaining the relationship between the cam groove 341, the biasing portion 35, and the cam follower 332. Figure 6(A) shows a small aperture state in which the aperture opening 37 formed by the multiple aperture blades 33 is the smallest, and Figure 6(B) shows an open state in which the aperture opening 37 formed by the multiple aperture blades 33 is the largest.

As shown in Figures 6(A) and 6(B), the first arm 352 (biasing portion 35) biases the cam follower 332 of the aperture blade 33 against the cam groove 341 with which it is engaged. Specifically, the first arm 352 biases the cam follower 332 against the wall 341a of the cam groove 341 (see arrows A1 and A2). More specifically, the first arm 352 biases the cam follower 332 of the aperture blade 33 against the wall 341a in a direction substantially perpendicular to the wall 341a of the cam groove 341.

This makes it possible to suppress rattling between the cam groove 341 and the cam follower 332. In addition, since the first arm 352 presses the cam follower 332 against the wall 341a of the cam groove 341, it is possible to suppress the movement of the aperture blade 33 from the stopped position. This makes it possible to improve the aperture precision. Furthermore, since the first arm 352 biases the cam follower 332 of the aperture blade 33 in a direction substantially perpendicular to the wall 341a of the cam groove 341, it is possible to suppress the reaction force that the aperture blade 33 receives from the wall 341a from acting in a direction that rotates the aperture blade 33, and it is possible to suppress the generation of an excessive load on the stepping motor 36.

The first arm 352 of the biasing portion 35 biases the cam follower 332 between one end and the other end of the range R1 in which the cam follower 332 moves. More specifically, the first arm 352 biases the cam follower 332 between the position of the cam follower 332 in the small aperture state (small aperture position) and the position of the cam follower 332 in the open state (open position). This makes it possible to suppress rattling between the cam groove 341 and the cam follower 332 while the cam follower 332 moves along the wall 341a of the cam groove 341.

The biasing force of the first arm 352 is stronger the closer it is to the coil portion 351 and decreases the farther it is from the coil portion 351. In this embodiment, the small throttle position of the cam follower 332 is closer to the coil portion 351 than the open position of the cam follower 332. Therefore, the biasing force with which the biasing portion 35 biases the cam follower 332 in the small throttle position is greater than the biasing force with which the biasing portion 35 biases the cam follower 332 in the open position.

When the aperture 37 becomes smaller, the tips of the aperture blades 33 overlap and rise (see FIG. 3, for example). As a result, each aperture blade 33 urges the other aperture blades 33 that overlap it in the direction in which the aperture 37 becomes larger. Therefore, the smaller the aperture 37 becomes, the more the stepping motor 36 receives a force (reaction force) from the aperture blades 33 in the opposite direction to the direction in which the aperture 37 becomes smaller, and the load on the stepping motor 36 increases. By placing the small aperture position of the cam follower 332 closer to the coil portion 351 than the open position of the cam follower 332, the closer to the small aperture position, the greater the urging force of the urging portion 35 becomes, so that the reaction force transmitted to the stepping motor 36 when the aperture 37 is reduced can be reduced, and the load on the stepping motor 36 can be reduced.

As described above in detail, according to this embodiment, the aperture unit 30 includes a plurality of aperture blades 33, each having a cam follower 332 and a support portion 331, a cam plate 34 having a plurality of cam grooves 341 that engage with each of the cam followers 332, a rotating member 32 having a plurality of holes 323 that engage with each of the support portions 331, and a biasing portion 35 that biases the cam follower 332 against the cam groove 341 that engages with the cam follower 332. This suppresses rattle between the cam follower 332 and the cam groove 341.

In addition, in this embodiment, the cam groove 341 has a wall 341a that guides the cam follower 332, and the biasing unit 35 biases the cam follower 332 against the wall 341a of the cam groove 341. The biasing unit 35 biases the cam follower 332 in a direction substantially perpendicular to the wall 341a of the cam groove 341 (see arrows A1 and A2 in Figures 6(A) and 6(B)). This makes it possible to prevent the reaction force that the diaphragm blade 33 receives from the wall 341a due to the biasing unit 35 biasing the cam follower 332 from increasing the load on the stepping motor 36.

In addition, in this embodiment, the cam groove 341 has a wall 341b that faces a wall 341a that guides the cam follower 332, and the wall 341a is closer to the optical axis OA than the wall 341b. If there is no biasing unit 35, or if the biasing unit 35 biases the cam follower 332 toward the wall 341b, in the small aperture state, the aperture blades 33 receive a reaction force and warp, deteriorating the accuracy of the aperture diameter. On the other hand, in this embodiment, the biasing unit 35 biases the cam follower 332 toward the wall 341a that is closer to the optical axis OA, so that warping is suppressed and the accuracy of the aperture diameter in the small aperture state can be improved.

In addition, in this embodiment, the biasing portion 35 biases the cam follower 332 from one end to the other end of the range in which the cam follower 332 moves. This makes it possible to suppress rattling between the cam groove 341 and the cam follower 332 while the cam follower 332 moves along the cam groove 341.

In this embodiment, the biasing force of the biasing portion 35 at one end of the range in which the cam follower 332 moves is greater than the biasing force of the biasing portion 35 at the other end. At one end of the range in which the cam follower 332 moves, the cam follower 332 is located in a small aperture state in which the aperture opening 37 formed by the multiple aperture blades 33 is smallest. As described above, the smaller the aperture opening 37, the greater the force that each aperture blade 33 receives from the other aperture blades 33 in the direction of enlarging the aperture opening 37, and the greater the load on the stepping motor 36. By increasing the biasing force of the biasing portion 35 at the small aperture position (one end of the range in which the cam follower 332 moves) where the cam follower 332 is located in the small aperture state, the reaction force transmitted from the aperture blade 33 in the small aperture position to the stepping motor 36 can be reduced, and the load on the stepping motor 36 can be reduced.

In this embodiment, the biasing portion 35 is a torsion coil spring, and the first arm 352 that contacts the cam follower 332 is approximately parallel to the cam groove 341. This allows the cam follower 332 to be biased in a direction that is approximately perpendicular to the wall 341a of the cam groove 341 (see arrows A1 and A2 in Figures 6(A) and 6(B)).

In addition, in this embodiment, the first arm 352 of the urging portion 35 is disposed between the aperture blade 33 and the cam plate 34, and the second arm 353 of the urging portion 35 is disposed on the side of the cam plate 34 opposite the aperture blade 33. This allows the cam plate 34 to be thinner than when the entire urging portion 35 is disposed between the cam plate 34 and the aperture blade 33, making it possible to reduce the weight of the cam plate 34 and, ultimately, the aperture unit 30.

In the above embodiment, a torsion coil spring is used as the biasing portion 35, but this is not limited thereto. For example, a leaf spring or a compression spring may be used as long as it is capable of biasing the cam follower 332 toward the wall 341a.

In the above embodiment, the biasing portion 35 biases the cam follower 332 toward the wall 341a, but the biasing portion 35 may bias the cam follower 332 toward the wall 341b. In this case, the wall 341b becomes the wall that guides the cam follower 332.

In addition, in the above embodiment, the biasing portion 35 was attached to the cam plate 34, but the biasing portion 35 may be attached to the rotating member 32 as long as it can bias the cam follower 332 toward the wall 341a or 341b of the cam groove 341.

The above-described embodiment is a preferred example. However, the present invention is not limited to this embodiment, and various modifications are possible without departing from the spirit of the present invention, and any combination of components may be used.

Reference Signs List 1 camera 20 lens barrel 30 aperture unit 32 rotating member 33 aperture blade 34 cam plate 35 biasing portion 37 aperture opening 331 support portion 332 cam follower 341 cam grooves 341a, 341b wall 352 first arm

Claims (11)

A plurality of aperture blades each having a first protrusion and a second protrusion;
a first opening member having a plurality of grooves that engage with the first protrusions;
a second opening member having a plurality of holes that engage with the second protrusions;
a biasing portion that biases the first protrusion against the groove that engages with the first protrusion;
Equipped with
a portion of the urging portion is disposed between the diaphragm blade and the first opening member,
Another part of the urging portion is disposed on the opposite side of the first opening member from the aperture blade.
Aperture unit. the groove has a wall that guides the first protrusion,
The biasing portion biases the first protrusion against the wall of the groove.
The aperture unit according to claim 1 . the groove has a wall facing a wall that guides the first protrusion,
the wall that guides the first protrusion is closer to the optical axis than the opposing wall;
The aperture unit according to claim 2. The biasing portion biases the first protrusion in a direction substantially perpendicular to the wall of the groove.
The aperture unit according to claim 2 or 3. The biasing portion biases the first protrusion from one end to the other end of a range in which the first protrusion moves.
The aperture unit according to any one of claims 1 to 4. The biasing force of the biasing portion at the one end is greater than the biasing force of the biasing portion at the other end.
The aperture unit according to claim 5. the first protrusion is located at the one end in a small aperture state in which the aperture opening formed by the plurality of aperture blades is smallest;
The aperture unit according to claim 5 or 6. At least a portion of the biasing portion is substantially parallel to the groove.
The aperture unit according to any one of claims 1 to 7. The biasing portion is a torsion coil spring,
The arm portion of the torsion coil spring that contacts the first protrusion is substantially parallel to the groove.
The aperture unit according to any one of claims 1 to 8. The groove is linear.
The aperture unit according to any one of claims 1 to 9. A lens barrel comprising the aperture unit according to any one of claims 1 to 10 .

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