JPS6047574B2 - Aperture bounce prevention device for lens barrel for single-lens reflex camera - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an aperture bounce prevention device for a lens barrel equipped with an automatic aperture mechanism in a single-lens reflex camera.

A feature of a single-lens reflex camera is that it is possible to confirm in the camera's viewfinder an image range that almost matches the image range of the subject exposed to the film (more precisely, the difference occurs depending on the focal length of the lens). This is its biggest feature. In order to prepare for shooting while checking the condition of the subject through the camera's viewfinder, and to quickly and reliably capture the moment that matches the purpose of shooting, the aperture of the lens barrel should be set to its maximum brightness at its maximum aperture. It is clear that it is desirable to have a lens barrel equipped with an automatic aperture mechanism that adjusts the aperture of the lens barrel to a preset aperture diameter in conjunction with various camera operations after the shutter button is pressed. In addition, single-lens reflex cameras have made it possible to easily adjust the focus of a subject that closely matches the subject being photographed through the viewfinder using lenses with different focal lengths, but all interchangeable lens barrels have an automatic aperture mechanism. If you don't have these, you won't be able to take full advantage of its greatest features.

Before releasing the shutter button, the aperture of the lens barrel is manually set to the aperture value that corresponds to the shutter speed used.Comparing the usage of a lens barrel with a preset aperture to a lens barrel with an automatic aperture mechanism, it is possible to imagine It is a well-known fact that there are far greater obstacles to photographing operations. The premise behind the establishment of the automatic aperture mechanism of the lens barrel is that after pressing the camera's shutter button, the aperture of the lens barrel reaches the preset aperture in coordination with various internal camera operations, and before the camera enters the film exposure state. It is that the caliber has stopped completely.

If the aperture of the lens barrel bounces during film exposure and does not reach the set value, it is natural that uneven exposure will occur. It is a phenomenon. If the time lag between pressing the shutter button and when the aperture of the lens barrel stops at the previously set aperture is made long enough, the number of lenses with automatic aperture mechanisms will increase. Time due to functional demands such as gender. It is desirable that the lag be set to a fairly short amount of time. Furthermore, because the lens barrel for single-lens reflex cameras has an automatic aperture mechanism and operates in conjunction with the camera shutter button to adjust the aperture to the set aperture, it is impossible to reduce the time lag to zero.・However, fortunately, the reality is that the time lag is set at a time that does not interfere with quick shooting due to human reflexes. Therefore, there inevitably arises lens barrels for single-lens reflex cameras that cannot be equipped with an automatic aperture mechanism. The reason why a conventional lens barrel does not have an automatic aperture mechanism will be explained with reference to FIG.

The vertical axis is the logarithmically converted value of the light intensity corresponding to the aperture diameter, and the horizontal axis is the time value, where T1 is the time until the aperture reaches the minimum aperture diameter (hereinafter referred to as maximum aperture time), T3 is the set time lag, and T4 is the maximum time required for the aperture diameter to stabilize (
(hereinafter referred to as maximum aperture stabilization time). Although the maximum aperture stabilization time T1 is sufficiently earlier than the time lag T3, the maximum aperture stabilization time T4 is longer than the time lag T3.
The unstable bouncing phenomenon of the aperture aperture that occurs during the time from T1 to T4 is due to the inertia generated from the strength relationship related to the cooperation between the camera and the lens barrel and the movement system of the aperture operating member within the lens barrel. It arises from the balance of etc. There are limits to reducing the mass of the parts involved in diaphragm operation in order to reduce inertia, and there are also limitations on the strength of the connection between the camera and lens barrel, such as shutter button pressure, film winding torque, mirror shock, etc. In relation to this, it is also extremely difficult to have the ability to sufficiently control the rebound. Therefore, with conventional automatic diaphragm mechanisms, it is difficult to avoid the aperture bounce that occurs from T1 to T4, and a lens barrel in which T4 does not fall within T3 becomes a lens barrel that does not have an automatic diaphragm mechanism. I end up. However, since the maximum aperture time is much faster than the time lag T3, if a means to prevent aperture bounce is used, there is a possibility that a lens barrel that was not previously equipped with an automatic aperture mechanism can become a lens barrel that is equipped with an automatic aperture mechanism. is hidden. The present invention has almost completely eliminated the aperture rebound of the lens barrel, and has created an automatic aperture mechanism for the lens barrel for single-lens reflex cameras, which could not be equipped with an automatic aperture mechanism other than changing the time lag T3 due to the aperture rebound. It was developed with the aim of making it easy to wear.

The present invention will be explained below based on examples.

Fig. 1 is a perspective view showing the main parts of the embodiment, Fig. 2 is a plan view of the main parts of the embodiment, with the aperture set to its maximum aperture before the shutter button is released, and Fig. 3 shows the main part of the embodiment. A plan view of the main parts, showing the state where the aperture diameter reaches the set aperture diameter after the shutter button is released, Figure 4 shows the aperture dynamic characteristic curve of a lens barrel with a conventional automatic diaphragm mechanism, and Figure 5 shows a specific aperture. Caliber (
Figure 6 shows the aperture dynamic characteristic curve of the automatic aperture mechanism lens barrel when the aperture rebound prevention mechanism is applied to F4) in the figure. Characteristic curve. In the figure, 1 is an aperture blade, 2 is an aperture opening/closing ring that opens and closes the aperture blade via a dowel 1b of the aperture blade.
Reference numeral 3 denotes an aperture support ring that supports the dowel 1a, which becomes the rotational axis of the aperture blades. Reference numeral 4 denotes an aperture opening/closing ring rotation pin fixed to the aperture opening/closing ring 2, which drives the aperture on the camera side in conjunction with the shutter release operation of the camera. , an aperture opening/closing member (not shown) on the lens side is driven by the operation of a moving member (not shown), and the rotating pin 4 is pushed around by the driving of the aperture opening/closing member. The aperture opening/closing ring 2 rotates to narrow down the aperture blades 1 to a preset aperture diameter. Reference numeral 5 denotes a buffer ring that buffers the bounce of the diaphragm, that is, the bounce of the rotating pin 4, and is rotatably attached to the member (shown in the figure) to which the diaphragm support ring 3 is attached with the optical axis as the rotation axis. buffer ring 5
A cutout portion into which the rotation pin 4 intervenes is formed at one end.

Reference numeral 6 denotes a set lever having one end rotatably supported on the shock ring 5 by a shaft 8, and the other end abutting the rotation pin 4 inserted in the notch of the buffer ring 5. A set lever pin 7 is implanted in the set lever 6, and the set lever pin 7 connects to a cam surface 15 of a cam ring 15, which will be described later.
It is engaged with a.

9 has one end pivotally supported by a shaft 17, the other end facing the rotating area of the rotating pin 4, and rotating the rotating pin 4 according to a preset aperture diameter.
A pin 11 and a spring-loaded pin 13 are installed in the throttle control lever for regulating the amount of rotation.

The spring 12 has one end hooked to a spring hook screw 14 implanted in a member (not shown) that is rotatably attached to a shaft 17, and the other end hooked to a front spring hook pin 13. The pin 11 of the aperture regulating lever 9 engages with a cam surface 15b of a cam ring 15, which will be described later, and the aperture regulating lever 9 is urged to rotate counterclockwise. Rotation in the counterclockwise direction is restricted by the cam surface 15b.

Reference numeral 10 is a locking pin that is implanted at the other end of the diaphragm restriction lever 9 and located in a notch of the buffer ring 5, and engages with the end surface of the buffer ring 5.

Reference numeral 15 denotes a cam ring that rotates around the optical axis integrally with an external diaphragm setting member (not shown);
As mentioned above, the set lever 6 and the aperture regulation lever 9 are
Cam surfaces 15a, 1 that engage with pins 7, 11 provided in
5b is formed, and the pins 7, 11 and the cam surface 15a
, 15b, the cam ring 15 and the set lever 6
There is a predetermined relationship between the diaphragm regulation lever 9 and the diaphragm regulation lever 9, which regulates the amount of rotation of the rotary pin 4 even when the diaphragm regulation lever 9 is moved via the cam ring 15 by the aperture value setting operation. The buffer end face 5a of the buffer ring 5 always protrudes by an amount Δθ from the regulating end face 9a of the buffer ring 9.

Reference numeral 16 denotes an interlocking pin that is rotated integrally with an external aperture setting operation member (not shown).

In the above embodiment, the pins 7 and 11 are connected to the set lever 6 and the aperture regulating lever 9, and the cam surface 5a is connected to the cam ring 15.
, 5b are provided, but the cam ring 15 is made into a simple ring shape, and the pins 7, 5b are provided at predetermined positions of the cam ring 15.
Even if a pin corresponding to 11 is provided and cam surfaces corresponding to the cam surfaces 5a and 5b provided on the cam ring 15 of the above embodiment are formed on the set lever 6 and the aperture regulating lever 9, the above correlation cannot be maintained. Furthermore, it is also possible to form a pin on one of the set lever 6 and the aperture regulating lever 9 and form a cam surface on the other, and provide the cam ring 15 with a cam surface and a pin that engage with the pin and the cam surface. A similar correlation can be established.

The operating system of the above members is as shown in FIG. The cam surfaces 15a and 15b of the cam ring 15 are connected to the pins 7 and 1.
1, the distal end surface 6a of the set lever 6, the distal end surface 9a of the aperture regulation lever 9, and the locking pin 10 are set in a predetermined relationship, and the aperture opening/closing ring rotating pin 4 is rotated clockwise to open the aperture blades 1. Since the tip surface 6a of the set lever 6 is held in the state of When it comes into contact with pin 4, the aperture hole lever 9
The end surface 5b of the buffer ring 5 comes into contact with the locking pin 10 implanted in the aperture control lever 9, and the end surface 5a of the buffer ring 5 is positioned in a direction that makes the aperture brighter by Δθ than the end surface 9a of the aperture regulating lever 9. In this state, set the aperture using an external operation member (not shown).
When the cam ring 15 is rotated to change the aperture value by operating the aperture control lever 9, the cam surface 15b of the cam ring 15 engages with the pin 11 of the aperture control lever 9.
rotates about the shaft 17 along the cam surface 15b, and its restricting end surface 9a also faces a position corresponding to the amount of rotation of the rotary pin 4 corresponding to a preset aperture value. On the other hand, the set lever 6 also tries to move from the place where the pin 7 of the set lever 6 and the cam surface 15a of the cam ring 15 are engaged toward the notch of the buffer ring 5, but in the preliminary state of the aperture value, it cannot be rotated. Since the pin 4 is always in a fixed position, the set lever 6 also rotates somewhat around the shaft 8, but the buffer ring 5 is rotated through the set lever 6.
is pushed around, and the end surface 5b of the buffer ring 5 touches the locking pin 1.
0 and protrudes from the regulating end surface 9a of the aperture regulating lever 9 by Δθ. Therefore, when changing the aperture value by operating the aperture value setting external operation member (shown), only θ in FIG. 2 changes, but Δθ does not change.

The state in which θ changes becomes smaller as the aperture diameter becomes brighter, and becomes larger as the aperture diameter becomes darker. Next, release the shutter button and rotate the aperture opening/closing ring pin 4 counterclockwise using the linking member (not shown) with the lens barrel on the camera side and the lens barrel diaphragm opening/closing member (not shown). When rotated instantaneously, it collides with the end face 5a of the buffer ring 5, imparting most of the kinetic energy to the buffer ring 5, and then hits the tip face 9a of the diaphragm regulating lever 9 and stops, reaching the set aperture diameter. At this time, the buffer ring 5 which has received kinetic energy hits the locking pin 10 implanted in the throttle control lever 9 in the counterclockwise direction and stops if the energy received by the end surface 5c is large. The movement of the buffer ring 5 after receiving kinetic energy varies depending on the amount of energy at the time of collision and the mass of the buffer ring 5. However, the effect of preventing ripple is that the mass of the buffer ring 5 The same effect can be obtained as long as the mass is greater than or equal to the energy received in the collision, so the range is very wide. Also, since the position of the shaft 8 of the set lever 6 attached to the buffer ring 5 changes by the rotation angle of the buffer ring 5, the pin 7 installed in the set lever 6 separates from the cam surface 15a, and the buffer ring 5 It will stop at any position regardless of where it stopped. Furthermore, after the exposure is completed, the state is restored to the state shown in FIG. In order to more clearly explain the effect of this structural action in preventing aperture ripple, let us consider a situation in which the buffer ring 5 acts only at a certain aperture diameter (F4 in Fig. 5), as shown in Fig. 5. In this case, there is no set lever 6, and the locking pin 10 installed at the tip of the aperture regulating lever 9 is installed on another member, for example, the member that fixes the support ring 3, and the buffer ring 5 is provided with a notch directly corresponding to θ, θ is constant and Δθ changes.

), the maximum aperture completion time changes from T1 to T2, the speed at which the aperture is reduced decreases, and Δθ increases as it goes from F3 to F1. , from a momentary stall state, energy is constantly being received in the direction to narrow down the aperture blades, so it accelerates and accumulates kinetic energy, and when the aperture reaches F1, the energy in the direction to open the aperture blades is restored considerably, and the fourth Although the aperture rebound is smaller and the maximum aperture stabilization time is faster than in the figure, it is not possible to satisfy the time lag T3 over the entire aperture diameter due to the change in the maximum aperture completion time T1 to T2. Also, the reason why the aperture rebound of the aperture diameter F4 in FIG.
Since it stops at a, the kinetic energy is extremely small,
This is because the constricting force that is constantly acting is sufficient to suppress the repulsive energy. Therefore, if Δθ is large, the throttle force is constantly being applied from the instantaneous stall state, and energy is accumulated again by the time it collides with the end face 9a of the throttle regulation lever 9, and the repulsive force becomes superior to the throttle force. This causes damped vibration and aperture rebound. For this reason, the more Δθ is made constant for each aperture diameter and the end face 5a of the buffer ring 5 is involved by an extremely smaller amount than the end face 9a of the aperture regulating lever 9, the greater the effect of preventing aperture rebound. The curve showing this state is shown in FIG. 6, and the maximum aperture stabilization time T4 almost changes the maximum aperture completion time T1.
also satisfies the time lag T3. As described above, with conventional mechanisms, the automatic aperture mechanism is either abandoned due to the large aperture rebound even though the maximum aperture completion time T1 is faster than the time lag T3, or the time lag T3 is made longer in consideration of the hindrance to photography. However, they were forced to choose between expanding the range of lens barrels to which automatic diaphragm mechanisms could be applied, and the features of single-lens reflex camera systems were significantly set back.

According to the present invention, the time lag T3 can be set to a time that does not cause any trouble in photographing, and the maximum aperture completion time can hardly be changed, and automatic diaphragm can be used for long focal length lenses, large aperture lenses, etc., which conventionally could not be equipped with an automatic diaphragm mechanism. It can also be easily incorporated into a conventional automatic diaphragm mechanism, and the strict precision between parts required in a conventional automatic diaphragm mechanism is reduced.
This has a great effect of greatly improving the advantages of single-lens reflex camera systems.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing the main parts of the embodiment, Fig. 2 is a plan view showing the main parts of the embodiment, with the aperture open and before the shutter button is released, and Fig. 3 the main parts of the embodiment. Fig. 4 shows the conventional aperture dynamic characteristic curve;
The figure shows the aperture dynamic characteristic curve with an aperture ripple prevention device installed on a portion of the aperture diameter. FIG. 6 shows the aperture dynamic characteristic curve of the example. 1: Aperture blade, 2: Aperture opening/closing ring, 3: Aperture support ring, 4: Aperture opening/closing ring rotating pin,
5: Buffer ring, 6: Set lever, 7: Set lever pin, 8: Set lever shaft, 9: Aperture regulation lever, 10
: Locking pin, 11: Aperture regulation lever pin, 12: Spring,
15: Cam ring, 16: Interlocking pin.

Claims (1)

[Scope of Claims] 1. The diaphragm blade drive member is driven by the operation of the diaphragm drive member on the camera side that is linked with the shutter release operation of the camera, and the diaphragm blade drive member is driven to cause the diaphragm opening/closing ring to be imprinted. A lens barrel for a single-lens reflex camera in which an aperture opening/closing ring rotates via a rotary pin provided to narrow down the aperture blades to a preset aperture diameter, and the lens barrel has a notch in which the rotary pin intervenes. a buffer ring that rotates around an optical axis; and a set lever having one end pivotally supported by the buffer ring and the other end abutting the rotation pin interposed in a notch of the buffer ring;
An aperture regulation lever with one end pivoted and the other end facing the rotation range of the rotation pin, which regulates the amount of rotation of the rotation pin according to a preset aperture diameter, and an optical axis integrated with the external aperture setting operation member. It consists of a cam ring that rotates around the cam ring, and there is a mechanism between the cam ring and the above-mentioned set lever and aperture control lever to control the amount of rotation of the rotation pin even when the aperture control lever is moved via the cam ring in an aperture value setting operation. An aperture bounce prevention device for a lens barrel for a single-lens reflex camera, characterized in that the buffer end face of a buffer ring is always projected by an amount Δθ from the regulating end face of a regulating aperture regulating lever. 2. A pin is installed in each of the set lever and the aperture control lever, and a cam surface that engages the pin is provided on the cam ring, and the correlation is established by the pin and the cam surface. An aperture bounce prevention device for a lens barrel for a single-lens reflex camera according to claim 1. 3. A cam surface is provided on the set lever and the aperture regulation lever, and a pin that engages with the cam surface is implanted in the cam ring,
2. The aperture bounce prevention device for a lens barrel for a single-lens reflex camera according to claim 1, wherein said cam surface and said pin provide said correlation. 4 A pin is implanted in the set lever, a cam surface is provided in the aperture regulation lever, a cam surface that engages with a pin of the set lever and a pin that engages with a cam surface of the aperture regulation lever are provided in the cam ring, and the cam surface 2. The aperture bounce prevention device for a lens barrel for a single-lens reflex camera according to claim 1, wherein the correlation is established by a pin and a pin. 5. The set lever is provided with a cam surface, the aperture regulation lever is provided with a pin, the cam ring is provided with a pin that engages with the cam surface of the set lever, and a cam surface that engages with the pin of the aperture regulation lever, and the cam 2. The aperture backand prevention device for a lens barrel for a single-lens reflex camera according to claim 1, wherein said correlation is provided by a surface and a pin.