JPH05127220A - Lens shutter - Google Patents

Abstract

PURPOSE:To develop a lens shutter which uses a stepping motor and by which two ways of program shutter modes can be obtained without changing the rotational speed of the stepping motor. CONSTITUTION:The lens shutter is provided with a first cam 12 and a second cam 13 whose shapes are different on a shutter driving ring 10 which is driven to be rotated by the stepping motor. By opening and closing shutter blades 2 and 3 at a working speed corresponding to the shape of the first cam 12, the first program shutter mode is obtained. By opening and closing the blades 2 and 3 at the working speed corresponding to the shape of the second cam 13, the second program shutter mode is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens shutter, and more particularly to a program shutter in which shutter blades are also used as diaphragms.

[0002]

2. Description of the Related Art A camera equipped with a program shutter that also uses shutter blades as an aperture is advantageous for snap shots and other shots that require rapid shooting, while it also has the effect of blurring the shot depth in shooting such as portrait photography. Therefore, it becomes unsuitable for shooting with the intention of drawing by the photographer, because the opening and closing operations of the shutter blades are rapid. A widely known aperture-priority AE mechanism is effective for shooting with this intention of drawing, but in order to have this aperture-priority AE mechanism, the lens shutter and the aperture must be configured separately,
As a result, the space for incorporating the components is increased, the size of the camera is increased, and the production cost of the camera is increased. Particularly in recent years, stepper motors are used to control the opening and closing of the shutter blades, and the number of program shutters configured as self-charged shutters has increased because cameras equipped with zoom lenses have become mainstream.

[0003]

[Problems to be Solved by the Invention]
A shutter using a motor has a drawback that the shutter opening speed is determined because it is used at a constant motor rotation, and only one type of program shutter mode can be obtained. It is conceivable to change the motor rotation speed to obtain different program shutter modes. However, if the rotation speed is slowed, clicking, which is a characteristic of stepping motors, occurs and the shutter opening becomes intermittent. ,
Further, when the rotation speed is increased, the rotation of the stepping motor is out of synchronization because it is out of synchronization with the rotation of the stepping motor.

Therefore, if the opening speed of the shutter blades is increased in order to increase the maximum shutter speed, fine control cannot be performed at the intermediate aperture, and conversely, the shutter blades are opened to perform control at the intermediate aperture. If the speed is slowed down, the shutter speed becomes slower and the camera shake easily affects the camera. For this reason, it has been difficult for a camera provided with such a program shutter to shoot with the intention of drawing with a deep or shallow depth of field.

In view of the above situation, the present invention provides a shutter mode in which the opening of the shutter blades is made faster and a shutter mode in which the opening of the shutter blades is made slower without changing the rotation speed of the stepping motor. The objective is to develop a lens shutter that can be used.

[0006]

In order to achieve the above-mentioned object, the present invention relates to a lens shutter in which a shutter blade is opened and closed in conjunction with a shutter drive ring which is rotationally driven by a stepping motor. Around the ring, first and second cams having different cam shapes are provided at a predetermined interval, and a shutter blade interlocking portion having a normally closing force is disposed between the first and second cams. The shutter in which the interlocking portion is pushed by the first cam and the shutter blade is opened and closed at an operation speed corresponding to the shape of the first cam according to the rotation of the shutter drive ring, and the shutter is pushed by the second cam. A lens shutter is proposed in which the shutter blade is configured to open and close at an operating speed corresponding to the second cam shape in accordance with the rotation of the drive ring.

[0007]

Two cams having different cam shapes are provided at predetermined intervals around the shutter drive ring, and the interlocking portion of the shutter blades having a normally closing force is arranged between the two cams.

When the shutter drive ring which is rotationally driven by the stepping motor is rotated in the direction in which the first cam pushes the interlocking portion of the shutter blade among the two cams, the shutter blade has the first cam shape. When the second cam rotates in a direction to push the interlocking portion of the shutter blade, the shutter blade opens and closes at the operating speed corresponding to the second cam shape.

With this structure, two types of program shutter modes can be obtained without changing the rotation speed of the stepping motor. For example, of these, the first program shutter mode is a shutter mode in which the depth of the subject is made shallow to give a blur effect (shutter blades are opened quickly and the diaphragm is opened as much as possible),
Further, the second program shutter mode can be a shutter mode in which the depth of the subject is deep (the shutter blade is slowly opened and the diaphragm is not opened much).

Further, in a shutter that stops the shutter blade halfway as a diaphragm-priority shutter, if the shutter blade is stopped halfway under the conditions so far, the cam angle is too steep and the shutter blade is bound to a large extent. Although it was not available, it can be used as a cam exclusively for aperture priority by grading the cam angle, and it has a wide range of applications.

[0011]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a mechanism diagram showing a lens shutter according to the present invention. The shutter 1 is constituted by two shutter blades 2 and 3 pivotally mounted on a shutter base plate (not shown) by blade shafts 4 and 5. .. These shutter blades 2,
3, elongated holes 2a and 3a (see FIGS. 3 and 4) are formed so as to overlap with each other, and an interlocking pin 6 as an interlocking portion communicates with the elongated holes 2a and 3a.

The interlocking pin 6 is provided at the tip of a drive lever 7 which is pivotally mounted on a shutter base plate with a support shaft 7a and protrudes into the long holes 2a and 3a of the shutter blades 2 and 3 described above. There is.

The drive lever 7 is subjected to a counterclockwise turning force by a spring 8 suspended between the drive lever 7 and the shutter base plate, and a cam push pin 9 provided on the lever 7 is rotationally driven by a stepping motor. Shutter drive ring 1
It is in contact with the outer circumference of 0 and maintains the illustrated state.

The above-mentioned shutter blade 2 turns counterclockwise about the blade shaft 4 within the range in which the interlocking pin 6 moves, and the shutter blade 3 rotates clockwise about the blade shaft 5 within the range in which the interlocking pin 6 moves. Turn to open the shutter.

The shutter drive ring 10 is provided on the lens barrel of the camera, and as can be seen from FIG. 1, a gear 11 is formed on a part of the outer periphery of the shutter 11 at a predetermined interval, and two drive cams having different shapes. 12 and 13 are provided, and an interlocking gear 14 for rotationally driving the shutter drive ring 10 is meshed with the gear 11 at substantially the center thereof. The interlocking gear 14 is interlocked with a stepping motor (not shown).

The cam push pin 9 which is in contact with the outer circumference of the shutter drive ring 10 is provided with these two drive cams 1.
It is located between 2 and 13. Two drive cams 12,
Reference numeral 13 denotes a cam that interlocks with the above-mentioned cam pushing pin 9 when the shutter drive ring 10 is driven by a stepping motor. For example, the shutter drive ring 1 in FIG.
When 0 is rotationally driven by the interlocking gear 14 in the clockwise direction, the first drive cam 12 interlocks with the cam push pin 9, and the shutter drive ring 10 is rotationally driven by the interlocking gear 14 in the counterclockwise direction. Then, the second drive cam 13 interlocks with the cam push pin 9.

The first and second drive cams 12, 1 are also provided.
In No. 3, the cam ridges are formed in different shapes. That is, the first driving cam 12 is formed so that the cam portion that interlocks with the cam pushing pin 9 rises at a steep slope from the outer periphery of the shutter driving ring 10, and the cam pushing pin 9 is used for the first driving. When interlocked with the cam 12, the interlocking speed becomes faster.
On the other hand, the cam portion of the second driving cam 13 is formed so as to rise more gently than the cam portion of the first driving cam 12, and the cam pushing pin 9 is formed on the second driving cam 13. The interlocking speed at the time of interlocking becomes slower than that of the first driving cam 12.

As a result, the shutter 1 which is opened by the cam pushing pin 9 interlocked with the driving cams 12 and 13 has an opening speed by the first driving cam 12 and the second driving cam 13. In contrast, as shown in FIG. 2, when the cam push pin 9 is opened by interlocking with the first drive cam 12, the opening speed of the shutter 1 becomes a P curve, and the cam push pin 9 is moved by the second drive cam 13. The opening speed of the shutter 1 becomes a Q curve when the shutter 1 is opened in association with. The stepping motor has a constant rotation speed.

With this configuration, two types of program shutter modes can be obtained without changing the rotation speed of the stepping motor. For example, when the shutter is opened by the first drive cam 12, When the shutter depth is shallow and the blur is blurred, and when the shutter is opened by the second drive cam 13, the shutter depth can be increased. In addition, reference numeral 15 in the drawing denotes a passage of photographing light.

Next, the operation of the lens shutter configured as described above will be described. A camera provided with this lens shutter is provided with a mode switching button or the like so that the first program shutter mode and the second program shutter mode can be selected by a switching operation. Note that such shutter mode switching may be configured to be automatically switched based on the brightness of the subject or the like. When the first program shutter mode is selected, the shutter drive ring 10 is operated by the stepping motor.
Is rotated clockwise, and when the second program shutter mode is selected, the shutter drive ring 10 is rotated counterclockwise.

First, in the state before shifting to the shutter release, the drive lever 7 receives a counterclockwise turning force by the spring 8 so that the cam push pin 9 is driven by the drive cams 12, 1.
3, the shutter blades 2 and 3 are closed as shown in FIG.

When the first program shutter mode is selected in the above state, the shutter release causes the stepping motor to rotate, and the interlocking gear 14 rotates left in FIG. Rotate clockwise. The rotation of the shutter drive ring 10 causes the cam push pin 9 to move the first drive cam 1 of the shutter drive ring 10.
It is pushed by 2, and the drive lever 7 turns clockwise against the spring force. As a result, the interlocking pin 6 has the long hole 2a,
3a is moved to the right in the figure while entering the shutter 3a, the shutter blades 2 and 3 are rotated, and the shutter 1 is opened as shown in FIG.

The exposure control circuit calculates the shutter time according to the conditions such as the photometric value and controls the stepping motor to rotate in reverse according to the shutter time, whereby the interlocking gear 14 rotates right in FIG. The shutter drive ring 10 is rotated counterclockwise to close the shutter blades 2, 3.

Next, when the operation button is operated to select the second program shutter mode, the shutter release causes the stepping motor to rotate, and the interlocking gear 14 causes the shutter drive ring 10 to move upward in the counterclockwise direction in FIG. Rotate in the direction. Due to the rotation of the shutter drive ring 10, the cam push pin 9 is pushed by the second drive cam 13, and the drive lever 7 turns clockwise to move the interlocking pin 6 to the right in FIG. From this, the interlocking pin 6 has the long holes 2a, 3
The shutter blades 2 and 3 are swung while moving in the position a, and the shutter 1 is opened as shown in FIG.

Further, if the stepping motor is reversed in the same manner as described above in accordance with the shutter time, the interlocking gear 14 rotates counterclockwise to rotate the shutter drive ring 10 clockwise in FIG. 4 and close the shutter blades 2, 3. Complete

The shutter opening speed P in the first program shutter mode and the shutter opening speed Q in the second program shutter mode have the opening characteristics shown in FIG. With this structure, the lens shutter has two types of program shutter modes without changing the rotation speed of the stepping motor. Incidentally, in the adjustment at the time of mass production of the shutter, the positional relationship between the cam and the drive lever is adjusted by a conventional method, for example, an eccentric pin or the like.

[0027]

As described above, according to the lens shutter of the present invention, the shutter drive ring rotatably driven by the stepping motor is provided with the first and second cams having different cam shapes, and the shutter blades are Since the opening / closing operation is performed at the operation speed corresponding to the cam shape of the first cam or the second cam, the lens shutter has two kinds of program shutter modes without changing the rotation speed of the stepping motor.

[Brief description of drawings]

FIG. 1 is a mechanism diagram of a lens shutter shown as an embodiment of the present invention.

FIG. 2 is a diagram showing a shutter opening characteristic of a shutter mode.

FIG. 3 is a mechanism diagram of a lens shutter similar to FIG. 1, showing a state where shutter blades are opened by a first driving cam.

FIG. 4 is a mechanism diagram of a lens shutter similar to FIG. 1, showing a state where shutter blades are opened by a second drive cam.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 shutter 2, 3 shutter blades 6 interlocking pin 7 drive lever 9 cam pushing pin 10 shutter drive ring 12 first drive cam 13 second drive cam 14 interlocking gear

Claims (1)

[Claims] 1. A lens shutter configured to open and close the shutter blades by interlocking with a shutter drive ring that is rotationally driven by a stepping motor. First and second cam shutters having different cam shapes are provided around the shutter drive ring. Cams are provided at predetermined intervals, and an interlocking portion of the shutter blades that always has a closing force is disposed between the first and second cams, and the interlocking portion of the shutter drive ring is pushed by the first cam. According to the rotation, the shutter blade is opened and closed at an operation speed corresponding to the first cam shape, and the interlocking portion is pushed by the second cam. According to the rotation of the shutter drive ring, the shutter blade is changed to the second cam shape. A lens shutter characterized by being configured to open and close at a corresponding operating speed.