JPS6064332A - Device for preventing bound of aperture blade - Google Patents

Abstract

PURPOSE:To prevent aperture blades from bounding due to the collision between an opening/closing ring for the aperture blades and a rotational angle specifying part by extending a tension spring between the opening/closing ring and a damping member, and hooking one of hooks at both ends of the spring to the damping member or opening/closing ring in a relatively movable state. CONSTITUTION:The opening/closing ring 16 is energized in the opposite direction of an arrow A to close the aperture fully before shutter release, so the damping ring 40 is drawn by the tension spring 43 is the same direction with the opening/closing ring 16 to allow a collision surface 42 to contact a set pin 31. When a shutter button is pressed, the opening/closing ring 16 is put in stop-down operation as shown by the arrow A before the shutter operates. When the opening/closing ring 16 is rotated, the hook 43a of the tension spring moves in a run-off hole 44 after the tensile force of the spring is ceased, so the damping ring 40 does not rotate in the same direction and the rotational-angle specifying pin 17 abuts on the collision surface 42. This collision reduces the rotating speeds of the rotational angle specifying pin 17 and opening/closing ring 16, and the damping ring 40 receives the energy of rotation from the opening/ closing ring 16 to rotate up to an angle of rotation corresponding to a set aperture value, preventing the bounding of the aperture blades.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a diaphragm opening/closing device for an interchangeable lens, and more particularly to a bounce prevention device that prevents the diaphragm blades from bouncing during instantaneous diaphragm operation.

An automatic aperture is a device that normally keeps the aperture open and instantaneously closes the aperture to a predetermined reference value when the aperture is activated, and is widely used in reflex cameras. This diaphragm opening/closing device opens and closes the diaphragm by rotating the opening/closing ring relative to the support ring of the diaphragm blades, and normally holds the opening/closing ring in the diaphragm open position. The rotation angle of the opening/closing ring is controlled by making the opening/closing ring contact (collide) with some kind of rotation angle regulating member. However, since narrowing down must be instantaneous, the rotational speed of the opening/closing ring is fast, whereas the rotation angle regulating member is stationary, so when the two collide, the opening/closing ring bounces, and therefore the diaphragm blades bounce. occurs. If the shutter opens before the diaphragm blades are no longer bound, it will cause uneven exposure. Although there is no problem if the time from when the shutter button is pressed to when the shutter opens is made longer, it is desirable that this time be as short as possible in order not to lose the shutter opportunity. Furthermore, the bouncing of the aperture blades clearly has a negative effect on the accuracy and stability of the aperture diameter.

In order to prevent such a bouncing phenomenon of the aperture blades, various proposals have been made in the past. For example, the patent application 1977-1
No. 41982 prevents bouncing of the diaphragm blades by providing a braking member separate from the rotation angle regulating member and slowing down the rotational speed by applying the braking member to this braking member immediately before the diaphragm opening/closing ring contacts the rotation angle regulating member. are doing. However, in the conventional device, in order to reset the braking member, a spring is used that biases the braking member in the opposite direction to the moving direction of the opening/closing ring, and therefore, when the opening/closing ring collides with the braking member, the braking is not applied. A vibration phenomenon occurs in which the member moves against the spring force due to the movement energy of the opening/closing ring, and then collides with the opening/closing ring again due to the spring force. To avoid this, a device has been proposed in which the position of the braking member is controlled using a cam, but this increases the number of parts and inevitably complicates the shape of the parts and the overall structure.

In view of the problems of the conventional device, the present invention was made with the aim of preventing bouncing of the diaphragm blades with a simple structure. The tension of the spring means that biases the spring means is
The brake member is characterized by being stretched between the braking member and the opening/closing ring via an escape means so that the opening/closing ring disappears or weakens when the opening/closing ring rotates in the narrowing direction.

The invention will now be described with reference to the illustrated embodiments. In FIGS. 1 to 3, reference numeral 11 denotes a fixed barrel fixed to a lens barrel that supports a lens, etc., and inside thereof is a support ring 14 that rotatably supports a rotation fulcrum pin 13 of an aperture blade 12. is fixed, and the opening/closing ring 1 is fitted with the opening/closing pin 15 of the diaphragm blade 12.
6 is rotatably supported by a presser ring 19. Only one aperture blade 12 is shown as a representative, and the opening/closing ring 1
6 changes the size of the aperture formed by the plurality of aperture blades 12. This opening/closing ring 16 has a rotation angle regulating bin 1.
7 and the spring hook have arms 18 protruding from each other. The opening/closing ring 16 is normally held at a position where the diaphragm is fully opened by a position regulating means (not shown), and rotates in the diaphragm direction by a spring force or the force of a drive member on the camera body side when the diaphragm is closed. Arrow A in FIGS. 1 and 3 indicates the narrowing down direction.

The fixed barrel 11 further supports a cam ring 20 and a brake ring 40 rotatable around the optical axis inside thereof. 21.
Reference numerals 41 denote retaining rings for removing the cam ring 20° and the brake ring 40, respectively. The cam ring 20 rotates integrally with an aperture preset ring (not shown), and when a calibration value is set by the aperture preset ring, its cam surface 22 changes its position. Cam surface 2
2 is a rotation angle regulating lever 2 pivotally connected to the fixed cylinder 11 by a shaft 23;
It comes into contact with the cam stopper pin 25 of No. 4. 26 is a torsion spring provided around the shaft 23, one leg of which is connected to the fixed cylinder 1.
The spring hook attached to the rotation angle regulating lever 24 is attached to the bin 27, and the spring hook attached to the rotation angle regulating lever 24 is attached to the bin 28. It is rotationally biased in the direction of contacting the surface 22.

As shown in FIG.
1, and its head is rotatably supported by a set screw 30, with the rotation angle regulating lever 24 being prevented from being removed.

The rotation angle regulating lever 24 is further provided with a set bin 31 at its free end, and a radial surface near the set bin 31 constitutes a rotation angle regulating surface 32.

The positions of the set bin 31 and the rotation angle regulating surface 32 are as follows.
When the calibration value is changed using the diaphragm preset ring, the cam ring 20 rotates and the abutting position of the cam stopper pin 25 against the cam surface 22 changes, so that it changes in accordance with the calibration value. The rotation angle regulating surface 32 contacts the rotation angle regulating pin 17 of the opening/closing ring 16 to regulate the rotation angle of the opening/closing ring 16 to an angle corresponding to a calibration value, while the set bin 31 contacts the rotation angle regulating pin 17 of the opening/closing ring 16. The collision surface 42 is brought into contact with the collision surface 42 of the rotation angle regulation surface 32, and the position of the collision surface 42 is always restricted to the rotation angle regulation bin 17 side by a very small distance Δ from the rotation angle regulation surface 32. That is, regardless of the calibration value, the rotational angle regulating bottle 17 is made to collide with the collision surface 42 immediately before colliding with the rotational angle regulating surface 32, and the rotational energy of the rotational angle regulating bin 17, that is, the opening/closing ring 16 is transferred to the braking ring 40. The rotational energy is converted into rotational energy, and then the rotational angle regulating bottle 17 is brought into contact with the rotational angle regulating surface 32.

The present invention provides a spring means for constantly bringing the collision surface 42 of the brake ring 40 into contact with the set pin 31, that is, the brake ring 40
A tension spring 43 that rotates and urges the opening/closing ring 16 in a direction opposite to the tightening direction is tensioned between the arm 18 (opening/closing ring 16) and the brake ring 40, and the tension spring 43 is One of the hooks 43a and 43b at both ends, the hook 43a on the brake ring 40 side
is formed into an oval shape, and is hooked into a relief hole 44 which is long in the direction of extension of the tension spring 43. In this way, the hook 43a can move relative to the brake ring 40, so that the tension of the tension spring 43 applied to the brake ring 40 is reduced to the opening/closing ring 16.
It disappears or weakens in conjunction with the rotation of. Of course, for the spring hook of the opening/closing ring 16 and the spring hook of the arm 18, the hole 45 may be a similar elongated escape hole.

The present device having the above configuration therefore operates as follows.

Before the shutter is released, the opening/closing ring 16 is urged to rotate in the direction opposite to the arrow A as described above to hold the diaphragm in the fully open position, and therefore the tension spring 43 causes the braking ring 40 to The collision surface 42 is brought into contact with the set bin 31. The position of the set bin 31 is
As mentioned above, it changes depending on the set comparison value, but the collision surface 42
Since it is always in contact with this set bin 31, it is located on the side of the rotation angle regulation bin 17 from the rotation angle regulation surface 32 by the distance Δ, regardless of the set comparison value.

When the shutter button is pressed, the opening/closing ring 16 rotates in the direction of the arrow and narrows the area before the shutter operates.
The rotation angle regulating bin 17 integrated with the arm 18 of the spring hook rotates in the same direction. When the opening/closing ring 16 rotates, the tension spring 43
Since the hook 43a moves inside the relief hole 44 after the tension of the spring 43 is released, the brake ring 40 does not rotate in the same direction.
collide with Due to this collision, the rotational speed of the rotational angle regulating bottle 17, that is, the opening/closing ring 16 is slowed down, and the braking ring 40 rotates by receiving the rotational energy of the opening/closing ring 16, so that the rotational angle regulating bin 17 is then rotated by the rotational angle regulating surface 32. It comes into contact with and stops at a rotation angle according to the set calibration value. According to the present invention, when the brake ring 40 rotates, the tension of the tension spring 43 applied to the brake ring 40 is transferred to the escape hole 44 and the hook 4.
3a, there is no risk that the brake ring 40 will collide with the rotation angle regulating bottle 17 again and cause a vibration phenomenon. FIG. 4 shows the result of controlling the rotation speed of the opening/closing ring 16 in this way. This is a graph showing the bounce prevention effect of Fil to F2 where the rotation angle of the opening/closing ring 16 becomes large.
2, the bounce prevention effect of the aperture blades is clearly recognized. Of course, by setting the strength of the tension spring 43, the length of the escape hole 44, etc., it is possible to obtain a similar bounce prevention effect even with the F value on the open side, but in this case, the bounce prevention effect on the minimum aperture side is unnecessary. It is desirable to adjust it so that it does not become too large.

The brake ring 40 rotates in the same direction as the rotation angle regulation bin 17 within the range of the rotation angle regulation bin 17 and the post-collision escape hole 44, but further rotation is regulated by the tension spring 43, and then the shutter is activated to open and close. When the ring 16 returns to its original position, it is pulled by the tension spring 43 and returns to its original position.

In addition, the rotation angle of the brake ring 40 may be determined by, for example, the rotation angle of the brake ring 40.
A rotation range regulating means can be provided between the fixed cylinder 11 and the fixed cylinder 11 to regulate the rotation range to an appropriate angle.

Specifically, for example, one of the brake ring 40 and the fixed cylinder 11 may be provided with a projection, and the other may be provided with a long hole or a projection that engages with the projection. Furthermore, the same bounce prevention effect can be obtained even if the brake ring 40 is not a complete ring.

As described above, according to the aperture blade bounce prevention device of the present invention, a tension spring is provided in tension between the opening/closing ring and the braking member, and at least one of the hooks at both ends of the tension spring is
A simple structure in which the braking member or the opening/closing ring is movably hooked onto the braking member or the opening/closing ring has the effect of reducing or preventing the bouncing phenomenon caused by the collision between the opening/closing ring and the rotation angle regulating member. .

[Brief explanation of the drawing]

Fig. 1 is a front view of the main parts showing an embodiment of the aperture blade bounce prevention device according to the present invention, Fig. 2 is a sectional view taken along line II-II in Fig. 1, and Fig. 3 is an exploded view of the main parts. The perspective view and FIG. 4 are graphs showing the bounce prevention effect. DESCRIPTION OF SYMBOLS 11... Fixed tube, 12... Aperture blade, 16... Opening/closing ring, 17... Rotation angle regulating bottle, 20... Cam ring, 2
2...Cam surface, 24...Rotation angle regulation lever (rotation angle regulation member), 25...Cam stopper bin, 31...
Set bin, 32... Rotation angle regulating surface, 40... Braking ring (braking member), 42... Collision surface, 43... Tension spring, 43a, 43b... Hook, 44... Escape Hole. Patent applicant: Asahi Optical Industry Co., Ltd. Agent: Kunio Miura Figure 1 ■ 1 Figure 2 Figure 4

Claims (1)

[Claims] (1) A plurality of diaphragm blades, an opening/closing ring that opens and closes the aperture caused by the diaphragm blades as they rotate, and a rotation angle regulating member that regulates the rotation angle of the opening/closing ring to an angle according to a set comparison value; When the opening/closing ring rotates in the narrowing direction, the aperture blade bounce prevention device includes a braking member that comes into contact with the opening/closing ring and moves together with the opening/closing ring before contacting the rotation angle regulating member,
A tension spring is provided between the braking member and the opening/closing ring to urge them toward each other, and at least one of the hooks at both ends of the tension spring is connected to the braking member or the opening/closing ring. A diaphragm blade bounce prevention device characterized in that the hook is fixed so as to be relatively movable.