JPS6120575Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an aperture mechanism for an interchangeable lens, in which the aperture operation ring has a manual preset range and an automatic aperture position, and is further equipped with an aperture blade bounce prevention mechanism.

Conventionally, mechanisms for preventing bounce of aperture blades in the manual preset range are known, for example, from Japanese Patent Laid-Open No. 52-82226, Japanese Patent Publication No. 56-31574, and the like. However, these aperture blade bounce prevention mechanisms cannot be directly applied to interchangeable lenses in which both a manual preset range and an automatic aperture position can be selected using an aperture operation ring. In other words, this type of interchangeable lens is compatible with aperture-priority, shutter-priority, and programmable automatic exposure cameras.In the manual preset range, the aperture is manually preset, and in the automatic aperture position, the exposure on the camera body side is adjusted. The aperture is automatically adjusted by a control mechanism, but due to differences in the means for connecting the camera body and the interchangeable lens, the aperture interlocking method, the aperture information signal transmission interlocking method, the aperture control method, etc.
If the aperture blade bounce prevention mechanism works in the automatic aperture position in the same way as in the manual preset range, the desired aperture value and the actual aperture value will deviate, often resulting in improper exposure.

Therefore, the purpose of the present invention is to provide an aperture mechanism in which the bounce prevention mechanism of the aperture blades operates in the manual preset range to obtain the correct aperture value, and in the automatic aperture position, the bounce prevention mechanism does not operate to provide an appropriate exposure. In the manual preset range, the buffer member and the diaphragm operation ring are engaged to prevent the aperture blades from bouncing, and the buffer member is moved to a position where it does not interfere with the diaphragm operation ring. It is characterized by

The invention will now be described with reference to the illustrated embodiments. Figures 1 and 2 are general views of the aperture mechanism, with a fixed lens barrel 2 whose rear end is a mount 1 that connects to the camera body.
A diaphragm operation ring 3 is rotatably fitted on the outer periphery of the
An internal frame 5 that supports the rear group lens 4 is located inside the fixed lens barrel 2. Depending on the lens system, the internal frame 5 may be integrated with the fixed lens barrel 2, or may be supported by a well-known lens extension mechanism so as to be movable straight forward and backward.

The diaphragm operation ring 3 has an interlocking portion 3a extending radially inward.
On the other hand, the interlocking ring 6 rotatably fitted into the inner frame 5 has an interlocking leg 6a parallel to the optical axis direction that engages with this interlocking part 3a, and always rotates at the same rate as the diaphragm operation ring 6. is configured to do so.

The aperture blade 7 has its rotary pin 7b fitted into the rotation fulcrum hole 8 on the inner frame 5 side, and the opening/closing pin 7a fitted into the cam groove 10 of the diaphragm opening/closing ring 9.
When the diaphragm opening/closing ring 9 rotatably supported is rotated, the diaphragm opening by the diaphragm blades 7 is opened and closed as is well known. Reference numeral 11 denotes an operating pin installed in this diaphragm opening/closing ring 9, which protrudes from the connection mount 1 of the fixed lens barrel 2 toward the camera body, and rotates the diaphragm from fully open to closing in conjunction with the shutter release operation of the body. Ru.

The aperture ring 9 is also provided with a regulating pin 12, which is connected to the rotation angle regulating lever 1.
The rotation angle limiting lever 13, which is pivotally mounted to the inner frame 5 by a pin 14, has an aperture diameter limiting pin 15 which fits into a cam groove 16 formed in the interlocking ring 6 and changes the position of the aperture limiting surface 13a in accordance with the aperture value set by the aperture operating ring 3.

The above is a conventionally known aperture mechanism,
The present invention is an aperture mechanism in which an aperture blade bounce prevention mechanism and a release mechanism are added to the aperture mechanism, and this will be explained next with reference to FIG. 3 and subsequent figures. At a part of the peripheral wall of the internal frame 5, at a position facing the diaphragm opening/closing ring 9,
A lever-shaped buffer member 20 is pivotally mounted by a pin 18 . The buffer member 20 has a buffer surface 21 and a forced rotation surface 22 on substantially opposite sides with respect to the pin 18, and has both ends locked to the spring dowel 23 and the peripheral wall of the internal frame 5, and the coil portion is attached to the pin 18. A wound torsion coil spring 24 biases the buffer surface 21 to protrude radially inward. The protruding end is regulated by the buffer member 20 in contact with the peripheral wall of the internal frame 5.

On the other hand, a buffer pin 25 that can come into contact with the buffer surface 21 is installed in the throttle opening/closing ring 9, and a bounce prevention mechanism release pin 26 that can come into contact with the forced rotation surface 22 is installed in the interlocking ring 6. has been planted. The buffer pin 25 comes into contact with the buffer surface 21 before the regulation pin 12 collides with the diaphragm regulation surface 13a in the manual preset range of the diaphragm operation ring 3. In addition, the bounce prevention mechanism release pin 26 does not interfere with the buffer member 20 in the manual preset range of the diaphragm operation ring 3, and when it rotates to the automatic diaphragm position, it moves to the forced rotation surface 2.
2, the buffer member 20 is rotated against the force of the spring 24, and its buffer surface 21 is retreated to a position where it does not interfere with the buffer pin 25.

Therefore, in the main diaphragm mechanism having the above-mentioned structure, the bounce prevention mechanism of the diaphragm blades works in the manual preset range as shown in FIGS. 3 to 5. In other words, considering the case where the aperture is stopped down to the minimum aperture, the aperture opening/closing ring 9 in the fully open state starts to rotate in the direction of the arrow in FIG. It comes into contact with the buffer surface 21 of 20 to provide rotational resistance (FIG. 4). Then, a part of the rotational energy of the opening/closing ring 9 is wasted in rotating the buffer member 20 against the force of the spring 24, and the rotational energy is consumed until the restriction pin 12 comes into contact with the aperture restriction surface 13a. becomes small (Figure 5). Therefore, the bouncing of the diaphragm opening/closing ring 9, that is, the bouncing phenomenon of the diaphragm blades 7 due to the collision between the pin 12 and the regulating surface 13a is prevented.

On the other hand, when the aperture operation ring 3 is rotated to the automatic aperture position, the release pin 26 of the interlocking ring 6, which rotates together with the aperture operation ring 3, as shown in FIGS. 6 and 7 as described above, contacts the forced rotation surface 22, rotates the buffer member 20, and retreats the buffer surface 21 to a position where it does not interfere with the buffer pin 25. Therefore, the diaphragm opening/closing ring 9 keeps the bounce prevention mechanism in a state where mosquitoes are removed. Can rotate freely. Therefore, when controlling the aperture using the exposure control mechanism on the camera body side, there is no possibility that the aperture value will become inaccurate.

FIG. 8 shows another embodiment of the present invention, in which a compression spring 27 is used instead of the torsion coil spring 24, and this is inserted between the peripheral wall of the internal frame 5 and the spring storage groove 28 of the buffer member 20. When inserted, the buffer member 20 is biased so that the buffer surface 21 protrudes inward. This embodiment also provides the same effects as the first embodiment.

If the forced rotation surface 22 of the buffer member 20 has a steep angle, the bounce prevention mechanism can be switched between activation and release with a small rotation angle of the diaphragm operation ring 3; If you do, the weak aperture control ring 3
The above switching can be performed with the rotational force of . Therefore, it is possible to design with a high degree of freedom by taking both into account.

As described above, according to the aperture mechanism of the present invention, in the manual preset range, the aperture blade bounce prevention mechanism operates to quickly obtain an accurate and stable aperture value, and in the automatic aperture position, the aperture blade bounce prevention mechanism is released. Therefore, since the aperture value can be accurately determined based on the signal from the camera body, correct exposure can be obtained in both the manual preset range and the automatic aperture position.

[Brief explanation of the drawing]

Fig. 1 is a vertical sectional view of the main parts showing an embodiment of the aperture mechanism of the interchangeable lens according to the present invention, Fig. 2 is an exploded perspective view of the main parts, and Figs. 3, 4, and 5 are manual operation. A perspective view of the main parts showing the operating state when the bounce prevention mechanism is activated in the preset range. Figures 6 and 7 are perspective views of the main parts showing the operating state when the bounce prevention mechanism is released at the automatic throttle position. , FIG. 8 is a perspective view of main parts showing another embodiment of the present invention. 3... Aperture operation ring, 5... Internal frame, 6... Interlocking ring, 7... Aperture blade, 9... Aperture opening/closing ring, 11...
Operating pin, 12...Restriction pin, 13...Rotation angle regulation lever, 20...Buffer member, 21...Buffer surface, 22...Forced rotation surface, 24, 27...Spring,
25...Buffer pin, 26...Bound prevention mechanism release pin.

Claims (1)

[Scope of utility model registration request] Aperture control ring that can be rotated between the manual preset range, where the aperture is preset manually, and the automatic aperture position, where the aperture is automatically adjusted using the exposure control mechanism on the camera body; the aperture is adjusted by the aperture operation signal from the camera body. a diaphragm opening/closing ring that rotates in a direction to close the diaphragm opening/closing ring; and a rotation angle regulating member that collides with a regulating pin integrated with the diaphragm opening/closing ring to regulate the rotation angle of the diaphragm opening/closing ring to an angle corresponding to the aperture value in the manual preset range. In the diaphragm mechanism of the interchangeable lens, a buffer member is provided which comes into contact with the diaphragm opening/closing ring and imparts rotational resistance to the diaphragm opening/closing ring before the regulation pin of the diaphragm opening/closing ring collides with the rotation angle regulating member; A diaphragm mechanism for an interchangeable lens, comprising a moving mechanism that moves the buffer member to a position where it does not interfere with the diaphragm opening/closing ring in conjunction with the rotation of the diaphragm operation ring to the automatic diaphragm position.