JPS6134500Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention is an aperture control device for a single-lens reflex camera, more specifically, a shutter speed priority type or a program type single-lens reflex camera. The present invention relates to an aperture control device that controls.

As is well known, in shutter speed priority type or program type single-lens reflex cameras, it is necessary to automatically control the aperture value, and for this reason, the aperture mechanism of the photographic lens is controlled by the elasticity stored in the elastic means. This movement was stopped at a predetermined aperture value using an electromagnet. However, when the aperture mechanism is driven by the elasticity stored in the elastic means, the squeezing speed differs between the beginning of the operation of the aperture mechanism and the end of its operation due to the elastic constant of the elastic means, the inertia of the aperture mechanism, etc. However, there was a problem in that the aperture delay from when the electromagnet was activated until the aperture actually stopped varied depending on the aperture value. For this reason, accurate aperture control has become difficult.

In order to solve such conventional problems, an aperture control device has already been proposed that reduces the aperture closing speed as the aperture value becomes smaller, thereby improving the accuracy of aperture control (JP-A-50-2003).
However, this aperture control device slows down the aperture speed at small aperture values, which results in a long aperture time.
This has the drawback that the time between the shutter release operation and the start of exposure, that is, the release time lag, becomes large, and there is a high possibility that the shutter chance will be lost.

In addition, an aperture control device has already been proposed that aims to improve the accuracy of aperture control by expanding the stroke per step of the member that controls the aperture stop at a small aperture value. Kosho 53-
(See Publication No. 21653). However, this aperture control device has the disadvantage that since the lever ratio is increased at a small aperture value, the operation of the control lever becomes unstable, and the elastic means for operating the control lever must have strong elasticity. It was hot. Furthermore, even if the lever ratio is varied by changing the contact point between the control lever and the actuating lever, in reality, the change is extremely small;
Little practical effect could be expected.

In view of the above-mentioned points, an object of the present invention is to increase the distance between the expanding mechanism that expands the movement of the narrowing drive member and the locking member that engages with this expanding mechanism and stops the movement of the narrowing driving member. To provide an aperture control device for a single-lens reflex camera in which the aperture is made closer to each other as the aperture is narrowed down.

According to the present invention, the distance between the expansion mechanism and the locking member is changed according to the narrowing operation, so that the narrowing delay is kept almost constant, so that the narrowing delay can be substantially eliminated. Accurate aperture control becomes possible.

Hereinafter, the present invention will be explained based on an illustrated embodiment.

FIG. 1 shows an aperture control device for a single-lens reflex camera, which is an embodiment of the present invention.

As is well known, single-lens reflex cameras have
A movable mirror 1 inclined at 45 degrees with respect to the photographing optical path is disposed in front of the photographic film surface. It is rotatably attached to both left and right walls (not shown) of Mirabox. A mirror drive pin 4 is attached to the projecting piece 2a hanging from the upper right end of the mirror support frame 2.
is firmly planted, and the tip of the pin 4 is fitted into an elongated hole 5a formed in the upper end of the mirror drive member 5.

The mirror driving member 5 is formed of a rod-shaped floating member arranged in the vertical direction, and its upper part is bent rearward and its lower part is inclined forward. A partially arcuate elongated hole 5b into which the lower movable pin 6 is loosely inserted is bored at the lower end, and the mirror drive member 5 rotates counterclockwise around the fixed pin 6. , the movable mirror 1 is connected to the support shaft 3 via the elongated hole 5a and the mirror drive pin 4.
It is designed to be flipped up by rotating clockwise around it. Further, a pushed pin 7 is installed near the middle lower part of the left side of the mirror drive member 5, and the pin 7 is attached to a charge lever 1 which will be described later.
When the movable mirror 1 moves back to the unbiased position, it is pushed by the pushing piece 10a provided on the lever 10, and serves to move the mirror drive member 5 back to the lowered position of the movable mirror 1. . Further, a latching pin 12 latched to a latching portion 11a of a mirror lever 11, which will be described later, is installed near the bottom of the right side surface of the mirror drive member 5. Furthermore,
The above-mentioned latching pin 1 on the right side of the mirror drive member 5
A pin 13 that engages one end of a mirror drive spring 14, which will be described later, is installed further below where the mirror drive spring 2 is provided.

The mirror lever 11 is formed of a vertically elongated lever, and is pivotally attached at the middle by a support shaft 16, and the hook-shaped hook portion 11a is formed at the end of the upper arm. has been done. This mirror lever lever 11 is wound around a support shaft 16, and rotates counterclockwise around the support shaft 16 by a torsion spring 18, which is secured at one end to the upper arm of the lever 11 and at the other end to an immovable pin 17. It is given the habit of rotating in the direction. Mirror foot lever 1 due to this habit
1 is regulated by the upper arm of the lever 11 coming into contact with the latching pin 12 when the movable mirror 1 is in the lowered state. Note that when the charge lever 10 is in the non-energized position as shown in FIG. 1, the latching portion 11a is not completely engaged with the latching pin 12, and a slight gap is formed between the two. There is. The lower arm of the mirror lever lever 11 extends diagonally forward and then hangs down. This serves as a pressed portion 11b. When the movable mirror 1 is in the lowered state, the pushed portion 11b is connected to the start lever 19.
It is opposed to the pushing portion 19a of 2 with a slight gap therebetween.

The start lever 19 has an upper arm bent at a right angle toward the left to form an inverted L shape, and is swingably disposed around a support shaft 20. The upper arm portion bent toward the left forms the pushing portion 19a, while the armature 21a of the release magnet 21 is attached to the lower arm of the start lever 19. Further, one end of a compressible coil spring 22 is attached to the lower arm of the start lever 19, and the lever 19 is given the habit of rotating counterclockwise around a support shaft 20. . The rotation of the lever 19 due to this habit is due to the armature 2 before operating the shutter release.
1a is regulated by being attracted to a release magnet 21 which is a release type electromagnet.
When the release magnet 21 is energized, the start lever 19 is rotated by the elasticity of the spring 22, pushing the mirror lever 11 and the aperture lever 23, which will be described later.

The aperture lever 23 is formed of a vertically elongated lever, and its middle portion is pivotally connected to a support shaft 24 so as to be swingable. A hook portion 23a that engages with a hook 9c of an aperture drive arm 9, which will be described later, is formed at the upper arm end of the aperture lever 23, and a lower arm end is formed at the push portion 1 of the start lever 19.
Pushed part 23 facing 9a with a slight gap
b. The aperture lever 23 is wound around the support shaft 24, and rotates counterclockwise around the support shaft 24 by a torsion spring 26, which has one end secured to the upper arm of the lever 23 and the other end secured to the immovable pin 25. It is given the habit of rotating. The rotation of the aperture lever 23 due to this habit is regulated by the upper arm of the lever 23 coming into contact with the hook 9c of the aperture drive arm 9 when the movable mirror 1 is in the lowered state. Note that when the charge lever 10 is in the non-energized position as shown in FIG.
The hook a is not completely engaged with the hook 9c, and a slight gap is formed between the two.

The charge lever 10 is formed of an inverted L-shaped plate, and is pivotally mounted at its midpoint by a support shaft 28. This charge lever 1
In the middle of 0's arm that extends downward,
A locked pin 2 that engages and disengages from a return lever 30, which will be described later.
9 have been planted. In addition, at the lower end of the same arm,
A pushed portion 10b is formed which is bent horizontally, and this pushed portion 10b is pushed forward in conjunction with winding of the film by a pushing member (not shown). and the charge lever 10 is moved to the support shaft 2.
It serves to rotate clockwise around 8.

The return lever 30 is formed of an inverted L-shaped plate, and its middle part is pivotably attached to a support shaft 31, and the end of one arm extending forward is attached to the cover. A locking portion 30a that engages with and disengages from the locking pin 29 is provided. The other arm end of the return lever 30, which extends downward, is moved forward by a pushing member (not shown) when the shutter is activated and the trailing curtain has finished traveling. This serves as a pushed portion 30b that is pushed and moved. Return lever 3
0 is rotated counterclockwise around the support shaft 31 by a torsion spring 33 that is wound around the support shaft 31 and has one end locked to one arm of the lever 30 and the other end locked to the immovable pin 32. They are given the habit of moving. The rotation of the return lever 30 due to this habit is regulated by one arm coming into contact with the locked pin 29.

On the other hand, the other arm of the charge lever 10 extends forward, and its middle lower edge near the support shaft 28 extends further downward to engage with the pushed pin 7. A matching pushing piece 10a is formed. In addition, the lower edge of the arm near the tip is once bent to the left and then extended so as to hang down.
The pushing piece 10c comes into contact with the pushed piece 9b. Further, near the tip of the same arm, there is a pin 34 between which the mirror drive spring 14 made of a compressible coil spring is hung between the pin 13 and a pin 37 of the diaphragm drive arm 9 which will be described later. Pins 36 are fixedly mounted to span the aperture drive springs 35 made of compressible coil springs.

The aperture drive arm 9 has a base end pivotally connected coaxially to the charge lever 10 by a support shaft 28,
The drive unit 9 is formed of a swinging arm whose free end extends forward, and is provided at the free end.
a serves to narrow down an aperture mechanism (not shown) disposed within the photographic lens barrel. The middle upper edge of this aperture drive arm 9 is further extended upward and serves as a pushed piece 9b that abuts against the pushing piece 10c of the charge lever 10. Further, the lower edge of the diaphragm drive arm 9 near the free end in the middle thereof extends downward, and the tip thereof has a hook 9 that engages with the hook portion 23a of the diaphragm lever 23.
c is formed. Furthermore, the aperture drive spring 35 is located near the free end of the aperture drive arm 9.
A pin 37 is implanted to lock one end of the pin 37. The aperture drive arm 9 is connected to a charge lever 10.
In the state shown in FIG. 1 in which the diaphragm is in the non-energized position, the lower surface near the free end abuts against the stopper pin 38, preventing further rotation in the counterclockwise direction. When the drive arm 9 narrows down the aperture to the minimum value, the drive portion 9a is brought into contact with the stopper pin 39, and further rotation in the clockwise direction is prevented.

Further, a transmission pin 40 is installed near the free end of the left side of the aperture drive arm 9. The transmission pin 40 serves to transmit the movement of the aperture drive arm 9 to the enlarging mechanism, and its tip portion extends so as to face the completely missing end surface of the partially toothed gear 41. The partially toothed gear 41 is rotatably attached to a support shaft 42, and the teeth on the lower half of the gear 41 are cut out over approximately half a period. A part of the cutout surface forms a cam surface 41a that is spaced apart from the support shaft 42 in the counterclockwise direction. A driven portion 53a of a driven lever 53, which will be described later, is in contact with this cam surface 41a. Further, the partially toothed gear 41 is wound around a support shaft 42, and has one end attached to a pin 43 that is erected on the gear 41.
Furthermore, by means of torsion springs 45 whose other ends are respectively engaged with immovable pins 44, they are given the habit of rotating counterclockwise around the support shaft 42. The rotation of the partially toothed gear 41 due to this behavior is regulated by the opposing completely missing end surface of the transmission pin 40 abutting against the stopper pin 46 before the narrowing operation.

The partially toothed gear 41 is meshed with a small diameter gear 48 rotatably attached to a support shaft 47, and a large diameter gear 49 coaxially and integrally formed with the small diameter gear 48 is integrally formed with a ratchet 51. It is meshed with a small diameter gear 50 which is formed as follows. Small diameter gear 50 and ratchet wheel 5
1 is rotatably attached to a support shaft 52.

The driven lever 53 is formed of an L-shaped lever, and is pivotally supported by a support shaft 54 so as to be swingable. The arm that extends forward of the driven lever 53 once extends to the right in the middle, and then extends forward again, and the driven portion 53a provided at the tip end of the arm extends to the right. The above partially toothed gear 4
It is in contact with the cam surface 41a of No. 1. Further, in the middle of the other arm that extends upward from the driven lever 53, there is an aperture stopping magnet 5 which is a release type electromagnet.
5 is attached, and a support shaft 57 that swingably supports a locking lever 56 is fixedly planted at the tip of the arm. The driven lever 53 is wound around the support shaft 54, and rotates clockwise around the support shaft 54 by a torsion spring 59, which has one end secured to one arm of the lever 53 and the other end secured to the immovable pin 58. It is given the habit of rotating in the direction. Driven lever 53 due to this habit
Rotation is restricted by the driven portion 53a coming into contact with the cam surface 41a.

The locking lever 56 is formed of a vertically elongated lever, and a claw portion 56a that engages with the claw of the ratchet wheel 51 is provided at the upper arm end of the locking lever 56. Further, an armature 55a of the aperture stopping magnet 55 is attached to the lower arm of the locking lever 56.
This armature 55a is attached by a regulation pin 60 planted on the lower arm of the locking lever 56, and the tip of the pin 60 extends toward the right to form one arm of the regulation lever 61. engaged with the end. The regulation lever 61 is formed of an L-shaped plate, and its middle portion is pivotally supported by a support shaft 62 so as to be swingable. And the regulation lever 61
The lever 61 moves around the support shaft 62 by a torsion spring 63 that is wound around the support shaft 62 and has one end locked to one arm of the lever 61 and the other end locked to the regulated pin 60. The arm is biased in a direction to bring the regulated pin 60 closer to each other. Further, one end of a tight coil spring 64 is attached to one arm of the regulation lever 61, and the lever 61 as a whole is given the habit of rotating counterclockwise around a support shaft 62. . The other end of the regulation lever 61 extends forward, and the lower edge of the tip thereof is slightly bulged to form a pushed portion 61a.
This pushed portion 61a is the charge lever 10.
When the charge lever 10 is moved to the biased position as shown in FIG. and 64 to rotate clockwise around the support shaft 62. Note that the elasticity of the spring 64 applied to the regulation lever 61 is set to be weaker than the elasticity of the spring 59 applied to the driven lever 53.

As described above, the aperture control device for the single-lens reflex camera of the present invention is constructed.

Next, the operation of this diaphragm control device will be explained.

FIG. 1 shows the state of the aperture control device before film winding of the camera. In this state,
In the mirror driving member 5, the pushed pin 7 is connected to the pushing piece 10.
a, and by being pulled by the mirror drive spring 14, it tends to rotate clockwise about the pin 7. Therefore, when the elongated hole 5a pushes down the mirror drive pin 4, the movable mirror 1 rotates counterclockwise around the support shaft 3 and abuts against a stopper member (not shown), so that the movable mirror 1 45 for the shooting optical path
The viewfinder optical path is formed at a tilted position. In addition, in this state, a slight gap is formed between the pin 12 to be latched and the latching portion 11a, and the pin 6 is located closer to the front in the elongated hole 5b. A gap is formed at the rear between the hole 5b and the hole 5b. Furthermore, the aperture drive arm 9 is
It is pressed by the charge lever 10 and abuts against the stopper pin 38, and a slight gap is also formed between the hook 9c and the hook portion 23a.

When the film is wound up by one photographed frame from the state shown in FIG. Push the mirror drive spring 14 and the aperture drive spring 3 toward
The charge lever 10 is rotated clockwise around the support shaft 28 while storing restoring elasticity in each of the positions 5 and 5. Then, the pushed pin 7 by the pushing piece 10a
The mirror drive member 5, which has been released from the restriction, moves slightly due to the elasticity of the mirror drive spring 14, and engages the latching pin 12 with the latching portion 11a, and the elongated hole 5
Position the pin 6 in the middle of b (see Figure 2). Also, the pushed piece 9b by the pushing piece 10c
The aperture drive arm 9, which has been released from the restriction, rotates slightly due to the elasticity of the aperture drive spring 35, and engages the hook 9c with the hook portion 23a, and the transmission pin 4
0 is brought closer to the all-missing end face of the partially-toothed gear 41 (see FIG. 2). Furthermore, the charge lever 10 is
During the rotation, the pushed portion 61a is brought into contact with the upper end surface, and the regulating lever 61 is rotated clockwise around the support shaft 62 against the elasticity of the springs 63 and 64. Therefore, the regulated pin 61 and the regulating lever 61
At the same time, an urging force is applied to the regulated pin 60 to move it toward the regulating lever 61. (See Figure 2). When the charge lever 10 rotates to the biased position shown in FIG. When engaged, the charge lever 10 is locked in the same position. Thereafter, the pushing member that pushed the pushed portion 10b returns to its original position when winding of the film is completed.

Next, when a shutter release button (not shown) is pressed in the charge state after the film winding is completed, the release magnet 21 is temporarily energized and the magnetic force of the magnet 21 is demagnetized. Therefore, the start lever 19 whose armature 21a has been released from the attraction by the release magnet 21 rotates counterclockwise around the support shaft 20 due to the elasticity of the spring 22, and the pushing part 19a moves to the pushed part 11b. and 23b, respectively. By pushing and moving the pushed portion 11b, the mirror lever 11 moves around the support shaft 16 with the spring 19.
The latch portion 11a rotates clockwise against the elasticity of the latch portion 11a.
The latching of the latched pin 12 is released. Then, the mirror drive member 5 moves slightly due to the tension elasticity of the mirror drive spring 14 until the rear end surface of the long hole 5b abuts against the pin 6, and then rotates counterclockwise using the pin 6 as a pivot point. start the movement. Therefore, the elongated hole 5a rotates to the left, the movable mirror 1 is rotated clockwise around the support shaft 3 via the mirror drive pin 4, and a jumping operation of the movable mirror 1 is started.

At the same time, as the pushed portion 23b is pushed, the aperture hook lever 23 rotates clockwise around the support shaft 24 against the elasticity of the spring 26, and the hook 9c is moved by the hook portion 23a. Release the latch. Then, the aperture drive arm 9 starts to rotate clockwise around the support shaft 28 due to the elasticity of the aperture drive spring 35, and the drive section 9a moves upward, causing the aperture mechanism of the photographic lens barrel to rotate. The narrowing down operation starts. In addition, due to the rotation of the aperture drive arm 9, the transmission pin 40 moves upward and comes into contact with the completely missing end surface of the partially toothed gear 41, and the gear 41 is rotated against the elasticity of the spring 45 as a support shaft. Rotate clockwise around 42. When the partially toothed gear 41 rotates, this rotation causes the small diameter gear 48 and the large diameter gear 49 to rotate.
and is transmitted to the ratchet wheel 51 via the small diameter gear 50, causing the ratchet wheel 51 to rotate at high speed. Furthermore, when the partially toothed gear 41 rotates, the cam surface 41a moves, so the contact portion of the cam surface 41a with the driven portion 53a changes. Therefore, the driven portion 53a is displaced in the direction of gradually separating from the support shaft 42 of the partially toothed gear 41, and the driven lever 53 is moved around the support shaft 54 by the spring 59.
is rotated counterclockwise against the elastic force of Therefore, the locking lever 56 attached to the driven lever 53 by the support shaft 57 also rotates to the left around the support shaft 54, gradually moving the claw portion 56a toward the outer periphery of the ratchet wheel 51 rotating at high speed.

When the aperture is narrowed down to a predetermined aperture value, the aperture stopping magnet 55 is temporarily energized and the magnetic force of the magnet 55 is demagnetized. Then, the locking lever 5 is released from attracting the armature 55a by the aperture stop magnet 55.
6 rotates counterclockwise around the support shaft 57 due to the elasticity of the spring 63 applied to the regulated pin 60, and the claw portion 5
6a is engaged with the pawl of the ratchet wheel 51. Therefore, the rotation of the ratchet 51 is forcibly stopped, and the small diameter gear 5
0, the rotation of the partially toothed gear 41 is also stopped via the large diameter gear 49 and the small diameter gear 48. By stopping the rotation of the partially toothed gear 41, rotation of the aperture drive arm 9 is prevented via the transmission pin 40, and the aperture is stopped in a state where the aperture is narrowed down to a predetermined aperture value.

On the other hand, just before the completion of the jumping motion of the movable mirror 1, the front curtain of the focal plane shutter starts traveling by a mechanism (not shown). Then, after a preset or program-determined shutter time elapses after the leading shutter curtain starts running, the trailing shutter curtain runs and the exposure is completed. Then, in connection with the completion of travel of the shutter trailing curtain, a pushing member (not shown) moves, pushes the pressed portion 30b of the return lever 30 forward, and moves the return lever 30 by the spring 33.
The device is rotated clockwise around the support shaft 31 against the elastic force of the device. Due to this rotation of the return lever 30, the engagement between the locking portion 30a and the locked pin 29 is disengaged, and the remaining tension elasticity of the mirror drive spring 14 and the aperture drive spring 35 causes the charge lever 10 to move onto the support shaft 2.
Start rotating counterclockwise around 8. When the charge lever 10 starts rotating counterclockwise, the pushing piece 10c first comes into contact with the pushed piece 9b, and the aperture drive arm 9 rotates around the support shaft 28 while being integrated with the charge lever 10. Rotated clockwise. As a result, the driving section 9a descends, so that the aperture mechanism in the photographic lens barrel is operated and the aperture is gradually opened. Also, connecting pin 4
0 is retracted downward from the position facing the partially toothed gear 41. When the aperture drive arm 9 rotates to the state shown in FIG. 1, the hook 9c climbs over and engages with the hook portion 23a, and the aperture drive arm 9 abuts against the stopper pin 38 and stops. At this stop position of the diaphragm drive arm 9, the diaphragm is fully opened.

Further, in parallel with the return operation of the aperture drive arm 9, the return operation of the mirror drive member 5 is performed. That is, when the charge lever 10 starts to rotate counterclockwise, the pushing piece 10a engages the pushed pin 7.
The mirror drive member 5 comes to abut against the pin 7, and receives a force that moves the mirror drive member 5 downward. Therefore, after the mirror drive member 5 moves slightly to a position where the pin 6 abuts against the front end surface of the elongated hole 5b, it begins to rotate clockwise using the pin 6 as a pivot point. Then, the movable mirror 1 is moved to the support shaft 3 via the elongated hole 5a and the mirror drive pin 4.
The mirror 1 is rotated counterclockwise around the mirror 1, and the mirror 1 is gradually lowered. Then, the mirror drive member 5
When rotated to the state shown in the figure, the latched pin 12
The mirror drive member 5 is stopped when the charge lever 10 completes its backward movement. At this stop position of the mirror drive member 5, the movable mirror 1 abuts against a stopper member (not shown) and assumes the finder optical path forming position.

On the other hand, the regulation lever 61 whose pressed portion 61a is no longer restricted by the other arm of the charge lever 10 due to the return movement of the charge lever 10 rotates counterclockwise around the support shaft 62 due to the elasticity of the spring 64. , pushes the regulated pin 60 forward. Therefore, the locking lever 56 rotates clockwise around the support shaft 57 to attract the armature 55a to the aperture stopping magnet 55 and disengage the claw portion 56a from the ratchet wheel 51. Claw portion 56 of ratchet wheel 51
When the locking by a is released, the partially toothed gear 41 rotates counterclockwise around the support shaft 42 due to the elasticity of the spring 45, so that the small diameter gear 48 and the large diameter gear 49 move around the support shaft 47. The small diameter gear 50 and the ratchet wheel 51 each rotate in a counterclockwise direction around the support shaft 52 . Further, as the cam surface 41a moves as the partially toothed gear 41 rotates, the driven lever 53 rotates clockwise around the support shaft 54 due to the elasticity of the spring 59. For this reason, the driven lever 5
The claw portion 56a of the locking lever 56 attached to 3
and the ratchet wheel 51 are gradually spaced apart. The rotation of the partially toothed gear 41 is stopped when the completely missing end surface of the gear 41 abuts against the stopper pin 46, and the ratchet 51, driven lever 53, locking lever 56, etc. are stopped at the corresponding position. Each member is stopped. Further, in connection with the backward movement of the charge lever 10, a pushing member (not shown) is connected to the start lever 1.
9 is rotated clockwise around the support shaft 20 against the elasticity of the spring 22, and the armature 21a is attracted to the release magnet 21. In this way, the aperture control device of the present invention returns to the state shown in FIG. 1 before film winding.

Incidentally, the rotation angle θ of the aperture drive arm 9 between the aperture fully open state (for example, F1.4) and the minimum aperture state (for example, F16) is normally set to about 15 degrees (see FIG. 3). However, the aperture drive arm 9 does not rotate at a uniform speed during this period. That is, since the diaphragm drive arm 9 is rotated by the tension elasticity of the diaphragm drive spring 35, the rotation speed ν of the arm 9 is the third
As shown in the figure, when the rotation angle θ is small, the rotation angle increases rapidly, and when the rotation angle θ is large, the rotation angle increases gradually. For this reason, conventionally, as shown by curve A in FIG. 4, as the rotation angle θ becomes larger,
In other words, there was a problem in that the smaller the account size, the greater the delay. Note that the aperture delay does not become zero even in the open state, and a slight delay occurs.

Therefore, in the aperture control device of the present invention, the cam surface 41a and the driven lever 53 change the distance between the ratchet wheel 51 and the pawl portion 56a according to the aperture operation, as shown by the straight line B in FIG. , the aperture delay is made almost constant over the entire aperture range. In this way, if the aperture delay becomes almost constant, by setting the demagnetization timing of the aperture stop magnet 55 at a fixed time in the electric circuit and always demagnetizing it early, there will be virtually no aperture delay. It is possible to obtain the same effect as with the previous one, and it is possible to set the aperture accurately.

As described above, according to the present invention, the effect of the aperture delay can be eliminated by making the aperture delay almost constant, thereby eliminating the conventional drawbacks mentioned at the beginning of the specification. It is possible to provide an aperture control device for a single-lens reflex camera that is extremely convenient to use.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of an aperture control device for a single-lens reflex camera showing an embodiment of the present invention, and FIG. 2 is a perspective view showing the operating mode of the aperture control device shown in FIG. FIG. 3 is a diagram showing the relationship between the rotation angle and rotation speed of the diaphragm drive arm in the diaphragm control device shown in FIG. FIG. 6 is a diagram showing the relationship between the rotation angle of the diaphragm drive arm and the diaphragm delay in the diaphragm control device shown in FIG. 9...Aperture drive arm (aperture drive member), 3
5...Aperture drive spring, 40...Transmission pin, 41...
... Partial tooth gear (enlargement mechanism), 41a... Cam surface, 4
8... Small diameter gear (enlargement mechanism), 49... Large diameter gear (enlargement mechanism), 50... Small diameter gear (enlargement mechanism), 5
DESCRIPTION OF SYMBOLS 1... Ratchet wheel (enlargement mechanism), 53... Driven lever (moving member), 53a... Driven part, 55... Aperture stop magnet (control means), 56... Locking lever (locking member), 56a...Claw portion.

Claims (1)

[Scope of claim for utility model registration] An aperture drive member that operates the aperture mechanism of a photographic lens, an enlargement mechanism that works in conjunction with this aperture drive member and expands its movement, and an electromagnet that attracts the aperture during the aperture operation. The electromagnet is engaged with the expansion mechanism by the release operation,
A locking member that stops the movement of the narrowing drive member; and a moving member that gradually approaches the locking portion of the expansion mechanism in conjunction with the narrowing operation. A distinctive feature of the aperture control device for single-lens reflex cameras.