JP2016042107A - Bayonet structure for lens barrels and accessories - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bayonet structure for lens barrels and accessories that enables the photographer to recognize, when he or she tries to fit a hood to a lens barrel in a state in which the position of the lens barrel is not properly set in its rotating position, the improper positioning of an accessory relative to the rotating position of the lens barrel before a bayonet pawl on the accessory side passes between adjoining bayonet pawls on the lens barrel side.SOLUTION: By making the outer diameter of a first circular part 17 different from that of a second circular part 18 and the inner diameter of an accessory-side first bayonet pawl 31 and that of an accessory-side second bayonet pawl 32 different from each other, not only the accessory-side first bayonet pawl is enabled to pass a first circular part 17 but also the accessory-side second bayonet pawl is enabled to pass a second circular part 18 only when a lens barrel 10 and an accessory 25 are placed in respectively prescribed relative rotating positions.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a lens barrel and an accessory bayonet structure.

  Conventionally, accessories such as a hood are connected to the front end of a lens barrel of a camera using a bayonet structure. Patent Documents 1 and 2 are conventional examples of this type of invention.

  Three lens-side bayonet claws that project toward the outer peripheral side and form three arc-shaped grooves (gap) between the front end portion of the outer peripheral surface of the lens barrels of Patent Documents 1 and 2 and located immediately after Are projected at intervals of 120 ° in the circumferential direction. The hood (accessory) has a mounting hole formed of a circular through hole, and three hood-side bayonet claws projecting toward the inner peripheral side are provided at intervals of 120 ° in the circumferential direction on the inner peripheral surface of the mounting hole. It is. One of the three arcuate grooves is a narrow arcuate groove whose dimension in the optical axis direction is shorter (narrower) than the remaining two. One of the three hood-side bayonet claws is a thin hood-side bayonet claw whose optical axis direction dimension is shorter (thin) than the remaining two. The thin hood side bayonet claw can be fitted (inserted) into the narrow arcuate groove, but the remaining two hood side bayonet claws cannot be fitted (inserted) into the narrow arcuate groove. .

  When the rotational direction position around the optical axis of the hood positioned in front of the lens barrel is set to a predetermined position and this hood is moved backward, the three hood side bayonet claws of the hood are adjacent to the lens side. It passes rearwardly through the three arc-shaped gaps formed between the bayonet claws and reaches the same position in the optical axis direction as the three arc-shaped grooves. When the hood is rotated in one direction in this state, the thin hood-side bayonet claws are fitted into the narrow arc-shaped grooves, and the remaining two hood-side bayonet claws are fitted into the remaining two arc-shaped grooves, respectively. The hood is attached to the front end of the lens barrel.

  On the other hand, when the position of the hood around the optical axis of the hood positioned in front of the lens barrel is shifted 120 ° from the predetermined position and the hood is moved backward, the hood 3 The two hood-side bayonet claws pass backward through the three arc-shaped gaps and reach the same position in the optical axis direction as the three arc-shaped grooves. When the hood is rotated in one direction in this state, a hood-side bayonet claw different from the thin hood-side bayonet claw attempts to fit into the narrow arcuate groove. However, since the thickness (dimension in the optical axis direction) of the hood side bayonet claw is larger than that of the narrow arc-shaped groove, fitting (insertion) to the narrow arc-shaped groove is restricted. Therefore, the camera user (photographer) can recognize that the relative rotation direction position of the hood with respect to the lens barrel is not correct.

JP 2001-264851 A JP 2001-264852 A

However, in the inventions of Patent Documents 1 and 2, until the hood side bayonet claw of the hood passes rearwardly through the arcuate gap on the lens barrel side and reaches the same position in the optical axis direction as the arcuate groove, the photographer It cannot be recognized that the position in the rotational direction relative to the lens barrel is not correct.
Therefore, after the hood-side bayonet claw reaches the same position in the optical axis direction as the arcuate groove of the lens barrel, the photographer separates the hood forward from the lens barrel, and then sets the hood at the predetermined position. It was necessary to move the hood backwards and attach it to the lens barrel.

  In the present invention, when the hood is attached to the lens barrel in a state where the rotational direction position with respect to the lens barrel is not set to the correct position, the bayonet claw on the accessory side is attached to the lens side adjacent to the lens barrel. Provided is a lens barrel and accessory bayonet structure in which a photographer can recognize that the rotational position of the accessory relative to the lens barrel is not in the correct position before passing through the gap formed between the bayonet claws. For the purpose.

  The lens barrel and accessory bayonet structure of the present invention include a lens barrel having a plurality of lens-side bayonet claws and a plurality of arcuate portions positioned between the adjacent lens-side bayonet claws, and an accessory-side bayonet claw. Mounting the accessory to the lens barrel by positioning the accessory-side bayonet claw that passes through a gap between the adjacent lens-side bayonet claws immediately after the lens-side bayonet claw. In the bayonet structure for maintaining the state, the arcuate portion of the lens barrel forms a pair of the first arcuate portion and the second arcuate portion having the same logarithm as the circumferential position different from the first arcuate portion. The accessory-side bayonet claws of the accessory are paired with the accessory-side first bayonet claws and the The accessory-side first bayonet claw is different from the accessory-side first bayonet claw and has the same logarithm of the accessory-side second bayonet claw, the outer diameters of the first arcuate part and the second arcuate part differing, and the accessory side By making the inner diameters of the first bayonet claw and the accessory-side second bayonet claw different, the accessory-side first bayonet claw is moved only when the relative rotation position of the lens barrel and the accessory reaches a predetermined position. The accessory-side second bayonet claw can pass through the second arcuate part and can pass through the arcuate part.

  On the outer peripheral surface of the lens barrel, an even number of the lens-side bayonet claws protruding toward the outer peripheral side and the same number of the arcuate portions having an outer diameter smaller than that of the lens-side bayonet claws are provided, There is a mounting hole that can be loosely fitted to the outer peripheral surface of the lens barrel, and the inner peripheral surface of the mounting hole protrudes toward the inner peripheral side and has the same number of even pairs as the lens-side bayonet claws. The accessory side bayonet claw is provided, the circumferential length of the accessory side first bayonet claw is F, the circumferential length of the accessory side second bayonet claw is G, the circumferential length of the first arcuate portion is H, When the circumferential length of the second arcuate portion is I, it is preferable that the following conditional expression (1) is satisfied. H, I> F, G ... Formula (1)

On the outer peripheral surface of the lens barrel, an even number of the lens-side bayonet claws protruding toward the outer peripheral side and the same number of the arcuate portions having an outer diameter smaller than that of the lens-side bayonet claws are provided, There is a mounting hole that can be loosely fitted to the outer peripheral surface of the lens barrel, and the inner peripheral surface of the mounting hole protrudes toward the inner peripheral side and has the same number of even pairs as the lens-side bayonet claws. The accessory side bayonet claws are provided with a pair, and the accessory side first bayonet claws are paired with an inner diameter A, the pair of accessory side bayonet claws paired with an inner diameter B, and the pair of the first arcuate portions outside the pair. When the diameter is C, the outer diameter of the pair of second arcuate portions is D, and the radial clearance between the inner peripheral surface of the mounting hole and the facing portion of the lens barrel with respect to the inner peripheral surface is E, Conditional expressions (2) and (3) below It is desirable to satisfy. A>C>B> D Expression (2), CBE / 2> 0 Expression (3)
Further, the accessory-side third bayonet claw and the accessory-side third bayonet claw that are different from the accessory-side first bayonet claw and have the same logarithm in the part of the mounting hole in front of the accessory-side bayonet claw Provided with the same number of accessory-side fourth bayonet claws that are different in circumferential direction from the two bayonet claws, the inner diameter of the paired accessory-side third bayonet claws is A, and the pair of accessory-side fourth bayonet claws The inner diameter may be B.

  Four lens-side bayonet claws are provided at 90 ° intervals in the circumferential direction, the first arc-shaped portion pair, the second arc-shaped portion pair, the accessory-side first bayonet claw pair, and the accessory-side second bayonet claw pair. The accessory-side third bayonet claw pair and the accessory-side fourth bayonet claw pair may be provided in pairs at 180 ° intervals in the circumferential direction.

  According to the present invention, when an attempt is made to attach the hood to the lens barrel in a state where the rotational direction position with respect to the lens barrel is not set to the correct position, the accessory-side bayonet claw of the accessory is adjacent to the lens barrel. The photographer can recognize that the rotational direction position of the accessory with respect to the lens barrel is not at the correct position before passing through the gap formed between the lens side bayonet claws.

It is a perspective view of the separation state of the lens barrel and hood of one embodiment of the present invention. (A) is a front view of a hood, (b) is a front view of a lens side mount block. It is a front view when the food | hood bayonet nail | claw of the hood which set the rotation direction position to the normal position passes toward the back in the circular arc-shaped clearance gap of the lens barrel. FIG. 6 is a front view when the hood side bayonet claw is set to be inserted into the arcuate gap on the lens barrel side after setting the rotational direction position of the hood concentric with the lens barrel to be shifted by 90 ° from the normal position. . FIG. 5 is a front view similar to FIG. 4 when the hood and the lens barrel are eccentric. It is a front view when a hood is attached to the lens barrel. 3 to 6 are front views corresponding to FIG. 3 when the front and rear directions of the hood are reversed. 3 to 6 are front views corresponding to FIG. 4 when the front and rear directions of the hood are reversed. 3 to 6 are front views corresponding to FIG. 5 when the front and rear directions of the hood are reversed. 3 to 6 are front views corresponding to FIG. 6 when the front and rear directions of the hood are reversed. It is a front view similar to FIG. 3 of the modification of this invention.

Hereinafter, an embodiment of the present invention will be described with reference to FIGS. In addition, the front-back direction in the following description is based on the arrow direction in the figure.
The camera of this embodiment includes an interchangeable lens barrel 10 that can be attached to and detached from a camera body (not shown), and a hard resin hood 25 that can be attached to and detached from the front end of the lens barrel 10 (accessory). And.
The lens barrel 10 includes a cylindrical barrel main body 11 and a lens-side mount block 12. A lens group (not shown) composed of a plurality of lenses is disposed inside the lens barrel body 11. The lens barrel body 11 has a rotationally symmetric shape centered on the optical axis OA (extending in the front-rear direction) of the lens group.

The lens-side mount block 12 made of hard resin (or metal) may be fixed to the front end portion of the barrel main body 11. The lens side mount block 12 is an annular member having a circular cross section with the optical axis OA as the center.
Four front side arc-shaped lens-side bayonet claws 13 projecting toward the outer peripheral side protrude from the front end portion of the outer peripheral surface of the lens-side mount block 12. The lens side bayonet claws 13 are provided at equiangular intervals (90 ° intervals) in the circumferential direction. The four lens-side bayonet claws 13 are composed of a pair of lens-side first bayonet claws 14 that are 180 ° apart from each other and a pair of lens-side second bayonet claws 15 that are 180 ° apart from each other. The pair of lens-side first bayonet claws 14 have the same circumferential length and their radial dimensions, and the pair of lens-side second bayonet claws 15 have the same circumferential length and their radial dimensions. A lock groove 15 a is recessed in the outer peripheral surface of each lens-side second bayonet claw 15.
Furthermore, the lens side bayonet claw 13 (the lens side first bayonet claw 14 and the lens side second bayonet claw 15) on the outer peripheral surface of the lens side mounting block 12 is adjacent to the lens side first bayonet. Four arcuate portions 16 formed between the claw 14 and the lens-side second bayonet claw 15 project toward the outer peripheral side. The four arcuate parts 16 are composed of a pair of first arcuate parts 17 that are 180 degrees apart from each other and a pair of second arcuate parts 18 that are 180 degrees apart from each other. However, the radial dimension (width) of the first arc-shaped portion 17 (the lens barrel 10) is larger than the second arc-shaped portion 18. Further, the outer diameter of the pair of first arcuate portions 17 and the outer diameter of the pair of second arcuate portions 18 are the outer diameter of the pair of lens side first bayonet claws 14 and the outer diameter of the pair of lens side second bayonet claws 15. Smaller than.
Further, a space surrounded by the adjacent lens-side first bayonet claw 14 and lens-side second bayonet claw 15 and the outer peripheral edge of the first arc-shaped portion 17 constitutes a first arc-shaped space 19 and is adjacent. A space surrounded by the lens side first bayonet claw 14 and the lens side second bayonet claw 15 and the outer peripheral edge of the second arcuate portion 18 constitutes a second arcuate space 20.
Further, on the outer peripheral portion of the lens-side mount block 12, an annular stopper surface 21 (see FIG. 5) located at a position (immediately after) rearward from the lens-side bayonet claw 13 and the arc-shaped portion 16 and having the optical axis OA as the center. 1) is formed. The annular stopper surface 21 is a plane orthogonal to the optical axis OA. The outer diameter of the annular stopper surface 21 is larger than the inner diameters of the arc-shaped portion 16 and the hood-side first bayonet claw 31 and the hood-side third bayonet claw 36 described later. Therefore, when the lens barrel 10 (lens side mount block 12) is viewed from the front along the optical stopper OA along the optical axis OA, the portion located immediately after the lens side bayonet claw 13 is the lens side first bayonet claw 14 and the lens. While the portion located immediately after the arc-shaped portion 16 is completely covered with the second side bayonet claw 15, the outer peripheral side portion is exposed forward (the inner peripheral portion of the annular stopper surface 21 is exposed by the arc-shaped portion 16. Covered).
Further, an annular mounting surface 22 is formed on the outer peripheral surface of the lens-side mount block 12 and is located immediately after the annular stopper surface 21 and has the same diameter as the outer diameter of the annular stopper surface 21. The annular mounting surface 22 is a cylindrical surface centered on the optical axis OA.

The hood 25 is an annular member having a circular cross section around the optical axis OA. A through hole centering on the optical axis OA is formed inside the hood 25, and a rear end portion of the through hole is formed by a mounting hole 26 having a cylindrical surface centering on the optical axis OA. The inner diameter of the mounting hole 26 is slightly larger than the outer diameter of the annular mounting surface 22 of the lens side mount block 12. Further, the front half of the hood 25 is formed with a pair of long light shielding portions 27 provided at equal angular intervals (180 ° intervals) in the circumferential direction and a pair of short light shielding portions 28 provided at equal angular intervals. It is.
Further, on the inner peripheral surface of the mounting hole 26 of the hood 25, there are four steps of a normal use bayonet claw 30 (accessory side bayonet claw) and a normal use bayonet claw 30 projecting toward the inner peripheral side. Four bayonet claws 35 (accessory-side bayonet claws) are provided in a projecting manner in the form of four arcs in front view that are located in the front and are used in the reverse direction.
The four bayonet claws 30 in normal use are paired with a pair of hood side second bayonet claws 32 (accessories) that are 180 degrees apart from each other as well as a pair of hood side first bayonet claws 31 (accessory side first bayonet claws). Side second bayonet claws). The inner diameter of the pair of hood side second bayonet claws 32 is smaller than the inner diameter of the pair of hood side first bayonet claws 31.
The four bayonet claws 35 when used in opposite directions are paired with a pair of hood side fourth bayonet claws 37 (180 ° apart from each other), as well as a pair of hood side third bayonet claws 36 (accessory side third bayonet claws) 180 degrees apart from each other. Accessory side fourth bayonet claws). The inner diameter of the pair of hood side third bayonet claws 36 is the same as the inner diameter of the pair of hood side first bayonet claws 31, and the inner diameter of the pair of hood side fourth bayonet claws 37 is that of the pair of hood side second bayonet claws 32. It is the same as the inner diameter. The circumferential length of the hood side third bayonet claw 36 is the same as that of the hood side first bayonet claw 31, and the circumferential length of the hood side fourth bayonet claw 37 is the same as that of the hood side second bayonet claw 32. Further, a notch 37a for dividing each hood-side fourth bayonet claw 37 into two parts is formed at the center of each hood-side fourth bayonet claw 37 in the longitudinal direction. Further, as shown in the figure, the circumferential position of each hood-side third bayonet claw 36 is shifted by a predetermined angle in one direction with respect to each hood-side first bayonet claw 31. The circumferential position is deviated by the predetermined angle in one direction with respect to each hood-side second bayonet claw 32. That is, the hood-side third bayonet claw 36 and the hood-side fourth bayonet claw 37 are connected to the hood-side first bayonet claw 31 and the hood-side second bayonet with respect to a predetermined reference line extending in the radial direction of the hood 25 through the optical axis OA. The shape of the claw 32 is inverted (except for the notch 37a).
The recess formed in the inner peripheral surface of the hood 25 is located immediately before the two hood-side second bayonet claws 32 and the position in the optical axis OA direction is the hood-side third bayonet claw 36 (and the hood-side fourth bayonet claw 37). The two normal use locking members 38, which are identical to), are rotatably attached (around the central axis extending in the front-rear direction). Each normal use lock member 38 has a circular shape when viewed from the front, and a part of the lock member 38 projects to the inner peripheral side from the mounting hole 26. The recess formed in the inner peripheral surface of the hood 25 is located immediately after the two hood-side fourth bayonet claws 37 (notches 37a) and the position in the optical axis OA direction is the hood-side second bayonet claw 32 (and the hood Two reverse use locking members 39 identical to the first side bayonet claws 31) are rotatably mounted (around the central axis extending in the front-rear direction). Each reverse use lock member 39 has the same specifications as the normal use lock member 38, and a part of the lock member 39 protrudes from the mounting hole 26 to the inner peripheral side.

The dimensions of each part of the lens side mount block 12 and the hood 25 satisfy the following conditional expressions (1) to (3). However, the inner diameter of the pair of hood side first bayonet claws 31 and the inner diameter of the pair of hood side third bayonet claws 36 are A, the inner diameter of the pair of hood side second bayonet claws 32 and the pair of hood side fourth bayonet claws 37. The inner diameter is B, the outer diameter of the pair of first arc-shaped portions 17 is C, the outer diameter of the pair of second arc-shaped portions 18 is D, and the annular mounting surface 22 (outer peripheral surface) (opposite portion) of the lens-side mount block 12 E is the total radial clearance of the mounting hole 26 of the hood 25, F is the circumferential length of the hood-side first bayonet claw 31 and hood-side third bayonet claw 36, and the hood-side second bayonet claw 32 and hood-side fourth. The circumferential length of the bayonet claw 37 is G, the circumferential length of the first arcuate portion 17 is H, and the circumferential length of the second arcuate portion 18 is I.
H, I> F, G ... Formula (1)
A>C>B> D Formula (2)
C-B-E / 2> 0 Formula (3)

Next, a procedure for attaching and detaching the hood 25 to and from the lens side mount block 12 will be described.
First, the case where the long light shielding part 27 and the short light shielding part 28 are located in front will be described.
First, the hood 25 positioned immediately before the lens-side mount block 12 is concentric with the lens-side mount block 12, and the rotational direction position of the hood 25 with respect to the lens-side mount block 12 is a normal position shown in FIG. To.
When the hood 25 is moved rearward along the optical axis OA in this state, as shown in FIG. 3, the pair of hood-side first bayonet claws 31 pass through the pair of first arcuate spaces 19 backward and the hood, respectively. Since the rear end surface of the side first bayonet claw 31 abuts against the annular stopper surface 21, the hood 25 cannot move rearward with respect to the lens side mount block 12. Further, the pair of hood side third bayonet claws 36 are respectively positioned in the pair of first arcuate spaces 19. Similarly, the pair of hood-side second bayonet claws 32 respectively pass through the pair of second arcuate spaces 20 rearward, the rear end surface of the hood-side second bayonet claws 32 abuts against the annular stopper surface 21, and the pair of hoods The side fourth bayonet claws 37 are respectively positioned in the pair of second arcuate spaces 20.
When the hood 25 is rotated by a predetermined angle clockwise in front view with respect to the lens-side mount block 12 from the state of FIG. 3, the lens-side first bayonet claws 14 of the lens-side mount block 12 and Since the hood-side first bayonet claw 31 and the hood-side second bayonet claw 32 of the hood 25 are positioned immediately after the lens-side second bayonet claw 15, the forward movement of the hood 25 with respect to the lens-side mount block 12 is restricted. Is done. Further, a pair of normal use lock members 38 (portions projecting inward from the mounting holes 26) engage with the lock grooves 15a of the pair of second bayonet claws 15 on the lens side while rotating and slightly elastically deforming. (At this time, the entire hood 25 is slightly elastically deformed). Further, at this time, the rotation restricting portions (stoppers) formed on the pair of hood-side third bayonet claws 36 come into contact with the rotation restricting portions (stoppers) formed on the pair of lens-side first bayonet claws 14, respectively. Relative rotation in the clockwise direction with respect to the lens-side mount block 12 is restricted.
When the hood 25 is attached to the lens-side mount block 12 in this way, the movement and relative rotation of the hood 25 with respect to the lens-side mount block 12 in the optical axis OA direction are restricted. There is almost no risk of sudden dropout.
When the photographer holds the hood 25 by hand and rotates the hood 25 counterclockwise with respect to the lens-side mount block 12 in front view, each lens-side second bayonet claw 15 (lock groove 15a) and the normal use Since the engagement of the lock member 38 is released, the lens side mount block 12 and the hood 25 can be shifted to the state shown in FIG. If the photographer manually moves the hood 25 with respect to the lens side mount block 12 along the optical axis OA after the lens side mount block 12 and the hood 25 are in the state shown in FIG. Can be removed forward from the lens-side mounting block 12.

Subsequently, the hood 25 in a state where the long light-shielding portion 27 and the short light-shielding portion 28 are positioned forward is concentric with the lens-side mount block 12 and the non-normal position shown in FIG. 4 (the normal position in FIG. 3). The case where the hood 25 is attached to the lens-side mount block 12 while being set at a position rotated about 90 ° in the clockwise direction when viewed from the front is described.
In this case, when the hood 25 is moved rearward along the optical axis OA, the pair of hood-side second bayonet claws 32 abut against the pair of first arcuate portions 17 from the front as shown in FIG. . Therefore, the hood 25 cannot move backward with respect to the lens side mount block 12. Therefore, the photographer is at the lens side of the hood 25 at this time (before the hood-side first bayonet claw 31 and the hood-side second bayonet claw 32 pass through the first arcuate space 19 and the second arcuate space 20). It can be recognized that the rotational direction position with respect to the mount block 12 is not located at the normal position. Therefore, the photographer rotates the hood 25 in one direction with respect to the lens-side mount block 12 from the state of FIG. 4 so that the pair of hood-side first bayonet claws 31 are positioned immediately before the pair of first arcuate spaces 19. In addition, the pair of hood-side second bayonet claws 32 are positioned immediately before the pair of second arcuate spaces 20, and then the hood 25 is moved rearward with respect to the lens-side mount block 12 (the pair of hood-side first bayonets). And the pair of hood-side second bayonet claws 32 are passed rearward with respect to the pair of second arcuate spaces 20), and the hood 25 is further removed. The hood 25 can be attached to the lens-side mount block 12 by rotating the lens-side mount block 12 by a predetermined angle clockwise in front view. .

Further, with reference to FIG. 5, the hood 25 in a state where the long light-shielding portion 27 and the short light-shielding portion 28 are located in the front is positioned at an irregular position with respect to the lens-side mount block 12 and with respect to the lens-side mount block 12. A case where the hood 25 is attached to the lens side mount block 12 while being decentered by E / 2 will be described.
Between the lens side mount block 12 and the hood 25, a relationship of CBE / 2> 0 (3) is established. Therefore, also in this case, when the hood 25 is moved rearward along the optical axis OA, the pair of hood-side second bayonet claws 32 abut against the pair of first arcuate portions 17 from the front (see FIG. 5). Accordingly, in this case as well, the photographer can use the hood 25 at this time (before the hood-side first bayonet claw 31 and the hood-side second bayonet claw 32 pass through the first arcuate space 19 and the second arcuate space 20). It is possible to recognize that the rotational direction position of the lens side mount block 12 is not at the normal position.

Next, the hood 25, which is positioned immediately before the lens side mount block 12 in a state where the long light shielding portion 27 and the short light shielding portion 28 are positioned rearward (a state opposite to FIGS. 3 to 6), is mounted on the lens side. The point of mounting on the lens-side mount block 12 while being concentric with the block 12 will be described with reference to FIGS.
In this case, when the rotational direction position of the hood 25 with respect to the lens side mount block 12 is positioned at the normal position shown in FIG. 7, the pair of hood side third bayonet claws 36 pass through the pair of first arcuate spaces 19 backward. In addition, since the rear end surface of the hood side third bayonet claw 36 abuts on the annular stopper surface 21, the hood 25 cannot move rearward with respect to the lens side mount block 12. Further, the pair of hood side first bayonet claws 31 are respectively positioned in the pair of first arcuate spaces 19. Similarly, the pair of hood-side fourth bayonet claws 37 respectively pass through the pair of second arcuate spaces 20 to the rear, the rear end surfaces of the hood-side fourth bayonet claws 37 abut against the stopper surface 21, and the pair of hoods The side second bayonet claws 32 are respectively positioned in the pair of second arcuate spaces 20.
When the hood 25 is rotated by a predetermined angle clockwise in front view with respect to the lens-side mount block 12 from the state of FIG. 7, each lens-side first bayonet claw 14 of the lens-side mount block 12 and Since the hood-side third bayonet claw 36 and the hood-side fourth bayonet claw 37 of the hood 25 are positioned immediately after the lens-side second bayonet claw 15, the forward movement of the hood 25 with respect to the lens-side mount block 12 is restricted. Is done. In addition, a pair of lock members 39 (portions projecting inward from the mounting holes 26) of the pair of lens-side second bayonet claws 15 are used while being rotated and slightly elastically deformed. Match. Further, since the rotation restricting portions (stoppers) formed on the pair of hood-side second bayonet claws 32 abut against the rotation restricting portions (stoppers) formed on the pair of lens-side second bayonet claws 15, respectively, the lens of the hood 25 Relative rotation in the clockwise direction in front view with respect to the side mount block 12 is restricted. When the hood 25 is attached to the lens-side mount block 12 in this manner, the optical axis of the hood 25 with respect to the lens-side mount block 12 is the same as when the long light-shielding portion 27 and the short light-shielding portion 28 are positioned forward. Since movement in the OA direction and relative rotation are restricted, there is almost no possibility that the hood 25 will unexpectedly fall off the lens-side mount block 12.

Next, a case where the hood 25 is attached to the lens side mount block 12 while the hood 25 is concentric with the lens side mount block 12 and set in the non-regular position shown in FIG. 8 will be described.
In this case, when the hood 25 is moved rearward along the optical axis OA, the pair of hood-side fourth bayonet claws 37 abut against the pair of first arcuate portions 17 from the front as shown in FIG. . Therefore, the hood 25 cannot move backward with respect to the lens side mount block 12. Therefore, the photographer is at this time point (before the hood side third bayonet claw 36 and the hood side fourth bayonet claw 37 pass through the first arcuate space 19 and the second arcuate space 20). It can be recognized that the rotational direction position with respect to the mount block 12 is not located at the normal position. Therefore, the photographer rotates the hood 25 in one direction with respect to the lens-side mount block 12 from the state of FIG. 8 so that the pair of hood-side third bayonet claws 36 are positioned immediately before the pair of first arcuate spaces 19. The pair of hood-side fourth bayonet claws 37 are positioned immediately before the pair of second arcuate spaces 20, and then the hood 25 is moved rearward with respect to the lens-side mount block 12 (a pair of hood-side third bayonets). And the pair of hood side fourth bayonet claws 37 are passed rearward with respect to the pair of second arcuate spaces 20), and the hood 25 is further removed. The hood 25 can be attached to the lens-side mount block 12 by rotating the lens-side mount block 12 by a predetermined angle clockwise in front view. .

Further, a case where the hood 25 is mounted at the lens side mount block 12 while being positioned at an irregular position with respect to the lens side mount block 12 and decentered by E / 2 with respect to the lens side mount block 12 will be described with reference to FIG. To do.
Between the lens side mount block 12 and the hood 25, a relationship of CBE / 2> 0 (3) is established. Therefore, also in this case, when the hood 25 is moved rearward along the optical axis OA, the pair of hood-side fourth bayonet claws 37 abut against the pair of first arcuate portions 17 from the front (see FIG. 9). Accordingly, in this case as well, the photographer can take the hood 25 at this time (before the hood-side third bayonet claw 36 and the hood-side fourth bayonet claw 37 pass through the first arcuate space 19 and the second arcuate space 20). It is possible to recognize that the rotational direction position of the lens side mount block 12 is not at the normal position.

As mentioned above, although this invention was demonstrated based on said each embodiment, this invention is not limited to the said embodiment, It can implement, giving various deformation | transformation.
For example, the embodiment shown in FIG.
The lens-side mount block 12 ′ in FIG. 11 includes four lens-side bayonet claws 13 ′ that are arc-shaped when viewed from the front. The four lens-side bayonet claws 13 ′ are composed of a pair of lens-side first bayonet claws 14 ′ that are 180 ° apart from each other and a pair of lens-side second bayonet claws 15 ′ that are 180 ° apart from each other. The pair of lens side first bayonet claws 14 'have the same radial dimension (width), and the pair of lens side second bayonet claws 15' have the same radial dimension (width). Further, the circumferential lengths of the two lens-side second bayonet claws 15 ′ are longer than the two lens-side first bayonet claws 14 ′. Further, a lock groove 15a ′ is formed in the outer peripheral surface of each lens side second bayonet claw 15 ′.
Further, an adjacent lens is located at the same front-rear position as the lens-side bayonet claw 13 ′ (lens-side first bayonet claw 14 ′, lens-side second bayonet claw 15 ′) on the outer peripheral surface of the lens-side mount block 12 ′. Four arcuate portions 16 ′ formed between the side first bayonet claws 14 ′ and the lens side second bayonet claws 15 ′ project toward the outer peripheral side. The four arcuate portions 16 'are composed of a pair of first arcuate portions 17' spaced apart from each other by approximately 180 ° and a pair of second arcuate portions 18 'spaced apart from each other by approximately 180 °.
Further, the space surrounded by the adjacent lens side first bayonet claw 14 'and lens side second bayonet claw 15' and the outer peripheral edge of the first arcuate portion 17 'constitutes a first arcuate space 19'. The space surrounded by the adjacent lens side first bayonet claw 14 'and lens side second bayonet claw 15' and the outer peripheral edge of the second arcuate portion 18 'constitutes a second arcuate space 20'. ing.
Four bayonet claws 30 ′ in normal use protruding from the inner peripheral surface of the mounting hole 26 ′ of the hood 25 ′ (accessory) projecting toward the inner peripheral side are projected. The four bayonet claws 30 'in normal use are composed of a pair of hood side first bayonet claws 31' (accessory side first bayonet claws) and a pair of hood side second bayonet claws 32 '(accessory side second bayonet claws). It will be. The inner diameter of the pair of hood side second bayonet claws 32 ′ is smaller than the inner diameter of the pair of hood side first bayonet claws 31 ′. The pair of hood side first bayonet claws 31 ′ are in positions slightly deviated from 180 ° in the circumferential direction, and the pair of hood side second bayonet claws 32 ′ are also in positions slightly deviated from 180 ° in the circumferential direction. is there.
On the inner peripheral surface of the hood 25 ′, two normal use lock members 38 ′ positioned immediately before the two hood side second bayonet claws 32 ′ are fixed. During normal use, a part of the lock member 38 ′ protrudes to the inner peripheral side from the mounting hole 26 ′.
The dimensions of each part of the lens side mount block 12 ′ and the hood 25 ′ satisfy the following conditional expressions (1) to (3). However, the inner diameter of the pair of hood-side first bayonet claws 31 ′ is A, the inner diameter of the pair of hood-side second bayonet claws 32 ′ is B, the outer diameter of the pair of first arcuate portions 17 ′ is C, and the pair of first bayonet claws 31 ′. The outer diameter of the two arcuate portions 18 'is D, the total amount of radial clearance between the annular mounting surface 22 (opposing portion) of the lens side mount block 12' and the mounting hole 26 'of the hood 25' is E, and the hood side first bayonet. The circumferential length of the claw 31 'is F, the circumferential length of the hood-side second bayonet claw 32' is G, the circumferential length of the first arcuate portion 17 'is H, and the circumferential length of the second arcuate portion 18'. Is I.
H, I> F, G ... Formula (1)
A>C>B> D Formula (2)
C-B-E / 2> 0 Formula (3)
Since the lens-side mount block 12 ′ and the hood 25 ′ of this modification also satisfy the expressions (1) to (3), the same effects as those of the above embodiment can be exhibited (however, the hood 25 ′ is reversed). It cannot be mounted on the lens side mounting block 12 ′ in the direction).
The bayonet claw 35 corresponding to the bayonet claw 35 (the hood side third bayonet claw 36, the hood side fourth bayonet claw 37) is formed on the hood 25 'of this modification, and the reverse use is further performed. An hour lock member 39 may be provided.

The lens-side bayonet claws and arcuate portions of the lens-side mounting blocks 12 and 12 'and the accessory-side bayonet claws of the hoods 25 and 25' (the bayonet claws during normal use and the bayonet claws during reverse use) The total number may be other than four. However, the same number of first arcuate parts and second arcuate parts, and the same number of accessory-side first bayonet claws (accessory-side third bayonet claws) and accessory-side second bayonet claws (accessory-side fourth bayonet claws) It is necessary to.
Further, the outer circumference of the lens side bayonet claws 13, 13 ′ (one of the lens side first bayonet claws 14, 14 ′ and the lens side second bayonet claws 15, 15 ′) of the lens side mounting blocks 12, 12 ′. The total amount of radial clearance between the surface (opposing portion) and the mounting hole 26 (the inner peripheral surface) of the hood 25 may be E.
Further, the present invention may be applied between a lens barrel accessory (for example, a lens cover, a filter, etc.) other than the hoods 25, 25 ′ and the lens barrel 10.

DESCRIPTION OF SYMBOLS 10 Lens barrel 11 Lens barrel main body 12 12 'Lens side mount block 13 13' Lens side bayonet nail (opposing part)
14 14 ′ Lens side first bayonet claw 14a 14a ′ Lock groove 15 15 ′ Lens side second bayonet claw 16 16 ′ Arc-shaped portion 17 17 ′ First arc-shaped portion 18 18 ′ Second arc-shaped portion 19 19 ′ First Arc-shaped gap 20 20 ′ Second arc-shaped gap 21 Annular stopper surface 22 Annular mounting surface (outer peripheral surface) (opposing portion)
25 25 'Hood (Accessory)
26 26 'Mounting hole 27 Long light shielding part 28 Short light shielding part 30 30' Bayonet claw at normal use (accessory side bayonet claw)
31 31 'Hood side first bayonet claw (Accessory side first bayonet claw)
32 32 'Hood side second bayonet claw (Accessory side second bayonet claw)
35 Bayonet claw (accessory side bayonet claw)
36 Hood side third bayonet claw (Accessory side third bayonet claw)
37 Hood side 4th bayonet claw (Accessory side 4th bayonet claw)
37a Notch 38 Lock member 39 in normal use 39 Lock member OA in reverse use Optical axis

Claims (5)

A lens barrel having a plurality of lens-side bayonet claws and a plurality of arcuate portions located between the adjacent lens-side bayonet claws;
An accessory including an accessory side bayonet claw,
In the bayonet structure that maintains the attachment state of the accessory to the lens barrel by positioning the accessory-side bayonet claw that has passed through a gap between adjacent lens-side bayonet claws immediately after the lens-side bayonet claw ,
The arcuate part of the lens barrel has a pair of first arcuate parts and the second arcuate part having the same number of logarithmic positions different from the first arcuate part,
The accessory-side bayonet claws of the accessory have a pair of accessory-side first bayonet claws and the accessory-side first bayonet claws that have different circumferential positions and the same number of accessory-side second bayonet claws,
The lens barrel and the accessory can be obtained by making the outer diameters of the first arcuate portion and the second arcuate portion different and making the accessory side first bayonet claw and the accessory side second bayonet claw different in inner diameter. The accessory-side first bayonet claw can pass through the first arcuate portion and the accessory-side second bayonet claw can pass through the second arcuate portion only when the relative rotation position of the is the predetermined position. A lens barrel and accessory bayonet structure. In the lens barrel and accessory bayonet structure according to claim 1,
On the outer peripheral surface of the lens barrel, an even number of pairs of the lens-side bayonet claws projecting toward the outer peripheral side and the same number of the arc-shaped portions having an outer diameter smaller than that of the lens-side bayonet claws,
The accessory has a mounting hole that can be loosely fitted to the outer peripheral surface of the lens barrel,
Provided on the inner peripheral surface of the mounting hole is the accessory side bayonet claw protruding toward the inner peripheral side and having the same number of even pairs as the lens side bayonet claw,
The circumferential length of the accessory-side first bayonet claw is F, the circumferential length of the accessory-side second bayonet claw is G, the circumferential length of the first arcuate portion is H, and the circumferential direction of the second arcuate portion A lens barrel and an accessory bayonet structure satisfying the following conditional expression (1) when the length is I.
H, I> F, G ... Formula (1) In the bayonet structure of the lens barrel and accessory according to claim 1 or 2,
On the outer peripheral surface of the lens barrel, an even number of pairs of the lens-side bayonet claws projecting toward the outer peripheral side and the same number of the arc-shaped portions having an outer diameter smaller than that of the lens-side bayonet claws,
The accessory has a mounting hole that can be loosely fitted to the outer peripheral surface of the lens barrel,
Provided on the inner peripheral surface of the mounting hole is the accessory side bayonet claw protruding toward the inner peripheral side and having the same number of even pairs as the lens side bayonet claw,
The inside diameter of the accessory side first bayonet claws forming a pair is A, the inner diameter of the pair of accessory side second bayonet claws is B, the outer diameter of the pair of first arcuate portions is C, and the above pair. When the outer diameter of the second arcuate portion is D and the total amount of radial clearance of the inner peripheral surface of the mounting hole and the facing portion of the lens barrel with respect to the inner peripheral surface is E, the following conditional expression (2 ) The lens barrel and accessory bayonet structure satisfying (3).
A>C>B> D Formula (2)
C-B-E / 2> 0 Formula (3) In the bayonet structure of the lens barrel and accessory according to claim 3,
The accessory-side third bayonet claw and the accessory-side second bayonet claw and the accessory-side second bayonet claw that are different from the accessory-side first bayonet claw and have the same logarithm in the part of the mounting hole in front of the accessory-side bayonet claw. The bayonet claw is different from the bayonet claw in the circumferential direction and has the same logarithm of the accessory side fourth bayonet claw.
The inside diameter of the accessory side third bayonet claws forming a pair is A,
A lens barrel and an accessory bayonet structure in which the inner diameter of the paired accessory side fourth bayonet claws is B. In the lens barrel and accessory bayonet structure according to any one of claims 2 to 4,
Four lens side bayonet claws are provided at 90 ° intervals in the circumferential direction,
The first arcuate part pair, the second arcuate part pair, the accessory side first bayonet claw pair, the accessory side second bayonet claw pair, the accessory side third bayonet claw pair, and the accessory side fourth bayonet A lens barrel and an accessory bayonet structure in which a pair of claws are provided at intervals of 180 ° in the circumferential direction.

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