JPH058410B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vibration isolator for a shutter, and more particularly to a vibration isolator for a camera shutter that prevents vibration of a camera body caused by a reaction when a shutter curtain or shutter blade moves.

Camera shake that occurs when the shutter is opened and closed in a camera equipped with a shutter that has a shutter curtain that runs in one direction, such as a focal plane shutter, or a light-shielding member (hereinafter simply referred to as a "light-shielding body") such as a shutter blade. Conventionally, this was mainly due to the impact when the light shield stopped traveling. Accordingly, various anti-vibration means are known to reduce the impact and prevent camera shake and bounce of the light shield at the same time.

On the other hand, in order to increase the speed of the shutter beyond a certain level, the running speed of the light blocking body itself must be increased compared to conventional ones, but in order to meet this requirement, it is necessary to increase the acceleration of the running light blocking body. There is. Therefore, as a reaction to the large acceleration, the force applied to the camera body increases in the direction opposite to the traveling direction of the light shield, and the resulting displacement of the camera body, that is, camera shake, becomes non-negligible. In particular, when the camera is attached to a support such as a tripod, the camera body, which is displaced by the reaction of the light shield while it is traveling, returns to its original position due to the elasticity of the camera support as soon as the travel ends. It vibrates along with the camera support. Moreover, since the vibration continues for a long time, camera shake persists, which adversely affects the photographs taken. The vibration occurs both when the shutter is opened and when it is closed, but if the vibration continues after the shutter is closed, it will not affect the photograph taken.
However, since the vibrations generated when the shutter is opened have an adverse effect on the photograph taken, sufficient means must be provided to prevent at least the vibrations caused by the reaction of the light shield moving to open the aperture.

The camera shake caused by the reaction to the running of the light shield as described above can be solved by moving a counterweight having an inertial mass almost equivalent to that of the light shield in the opposite direction at the same speed as the light shield, according to the law of motion. This can be prevented by configuring the structure so that the forces due to their reactions cancel each other out. However, within a narrow camera, it is difficult to secure a large space in which the counterweight can be moved approximately the same distance as the light shield.

SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide a camera shutter vibration isolation device having a counterweight means that can be installed within a narrow space of a camera without increasing the external dimensions of the camera. In order to achieve the above object, the present invention includes:
In a camera shutter that exposes light by opening and closing the shutter opening with a pair of light shields running in one direction, at least one of the pair of light shields is linked with a counterweight having an inertial mass larger than that of the light shield. At the same time, the counterweight is swingably supported by a support shaft provided parallel to the exposure edge of the light shielding body, and at the same time as the light shielding body travels, the counterweight The device is characterized in that it is configured to be displaced in a direction opposite to the moving direction of the edge, and the amount of displacement is shorter than the moving distance of the exposure edge.

Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.

FIG. 1 is a plan view showing an embodiment of the present invention, showing a state in which the shutter is charged, and FIG. 2 is an enlarged cross-sectional view of FIG. 1. The shutter shown in Fig. 1 is a so-called vertically running focal plane shutter in which a leading blade group and a trailing blade group consisting of a plurality of shutter blades travel in a direction perpendicular to the longitudinal direction of the shutter opening to perform exposure. The blade structure is shown in FIG.

In FIG. 1, a shutter base plate 1 is provided with a shutter opening 2, and this shutter opening 2 is covered by a leading blade group 3 consisting of a plurality of blades. Further, the plurality of blades of the other rear blade group 4 are placed in a stacked position above the shutter opening 2 in a holding position. In FIG. 3, the leading blade group 3 deployed to cover the opening 2 includes a rectangular blade 3a supported by a leading blade driving arm 5 and an auxiliary arm 6, which constitute a known parallelogram linkage mechanism. Five auxiliary blades 3b, 3c, 3d, 3e, 3f to cover the remainder of the opening 2 that cannot be covered with the rectangular blade 3a.
It is composed of. The exposure edge E formed on the upper part of the rectangular blade 3a is parallel to the inner edge of the opening 2 in the longitudinal direction. Further, the leading blade drive arm 5 and the auxiliary arm 6 are rotatably supported by pin shafts 7 and 8 arranged in parallel on the shutter base plate 1, respectively. The pin shaft 8 that supports the auxiliary arm has five additional auxiliary blades 3b to 3b.
3f is rotatably supported. These leading blade groups 3 are driven by a leading blade drive lever 9 shown in FIG. 1, and are moved to a retracted position below the shutter opening 2 and overlapped with each other. Similarly to the leading blade group, the trailing blade group 4 also supports a rectangular blade supported by a trailing blade drive arm and an auxiliary arm (see Fig. 3) that constitute a parallelogram link mechanism, and an auxiliary arm. The blade group consists of five auxiliary blades that can be rotated around a pin shaft.Following the movement of the leading blade group 3, after a predetermined delay time, the blade group then travels downward and unfolds, opening the shutter opening 2. It is constructed to cover.

The leading blade drive lever 9 that drives the leading blade group 3 is
As shown in FIGS. 1 and 2, it is rotatably supported by a pin shaft 10 implanted in the shutter base plate 1, and is attached so as to rotate clockwise at all times by a leading blade drive spring 11. The rotation of the blade is prevented by the leading blade retaining pawl 12.
Further, the leading blade driving pin 13 implanted at one end of the leading blade driving lever 9 passes through an arcuate groove 1a formed in the shutter board 1 with the pin shaft 10 as the center, and passes through the cam of the leading blade driving arm 5. It is engaged with the groove 5a. Further, the leading blade drive pin 13 is engaged with a cam groove (not shown) formed in each of the five auxiliary blades 3b to 3f.

On the other hand, in the rear blade group 4, similarly to the leading blade group 3, the rear blade drive lever 9' is rotatably supported by a pin shaft 10' implanted in the shutter base plate 1, and the rear blade drive lever 9' is rotatably supported by the rear blade drive spring 11'. Therefore, it is always urged to rotate clockwise, and the rotation is controlled by the rear blade retaining pawl 12'.
is prevented by. Further, the rear blade drive pin 13' installed at one end of the rear blade drive lever 9' is
It is configured to pass through an arcuate groove 1b formed in the shutter base plate 1 with the pin shaft 10' as the center and engage with a cam groove (not shown) formed in each of the rear blade drive arm and the auxiliary blade.

A gear 14 is fixed to the leading blade drive lever 9,
Both are configured to be able to rotate around the pin shaft 14. A segment gear 15 that meshes with this gear 14 is connected to a pin shaft 16 implanted in the shutter board 1.
is rotatably supported by. A bending plate 17 is integrally fixed to this segment gear 15, and a pin 18 is implanted in a bent portion 17a of the bending plate 17. Further, a bearing pedestal 20 is fixedly provided on the shutter board 1, and a weight drive shaft 19 that engages with the pin 18 is rotatably supported on this bearing pedestal 20. The weight drive shaft 19 is parallel to the running surface of the leading blade group 3 which is parallel to the shutter substrate 1, and is provided so that the axis of the shaft is parallel to the exposure edge E of the leading blade group 3. Further, the flange portion 19a formed at one end of the weight drive shaft 19 is provided with a notch groove 19b that engages with the pin 18 as shown in FIG.
The pin 18 is urged by a spring 21 so as to be in constant pressure contact with one wall surface of the notch groove 19b. Due to the engagement between the notch groove 19b and the pin 18, the direction of rotation of the segment gear 15 is changed, and the weight drive shaft 19 is perpendicular to the pin shaft 16.
is transmitted to.

Furthermore, a counterweight 2 is attached to the other end of the weight drive shaft 19.
A swinging arm 23 for supporting one end 22a of 2 is fixedly provided as shown in FIGS. 2 and 5. A support stand 24 is fixed on the shutter board 1 at a position facing the bearing stand 20, sandwiching the counterweight 22 therebetween.
A support shaft 25 is implanted in the support base 24 so as to coincide with the axis of the weight drive shaft 19 . This support shaft 25 includes a swinging arm 23' that supports the other end 22b of the counterweight 22.
is rotatably supported via a bush 26. In addition, in order to integrally connect the counterweight 22 and the swinging arms 23, 23', both ends 22 of the counterweight 22
a, 22b are formed in a step shape, and both ends 22a,
22b are bent portions 23a and 2 formed on the swinging arms 23 and 23', respectively, as shown in FIGS. 5 and 6.
They are crimped and connected by 3'a. Therefore, the counterweight 22 and the swinging arms 23, 23' can swing integrally about both the weight drive shaft 19 and the support shaft 23. In this case, the counterweight 22 is brought close to the running surface of the leading blade group 3, and the
It is necessary to balance the momentum of the counterweight 22, which is displaced in conjunction with this, and the momentum of the leading blade group 3, and to reduce the space occupied by the counterweight 22. Therefore, the amount of displacement S of the counterweight 22 is reduced, and the distance l from its center of oscillation to the center of gravity G is reduced.
In order to make the inertial mass of the counterweight 22 larger than the inertial mass of the leading blade group, the counterweight 22 is made of tantalum (Ta), tungsten (W), or an alloy thereof, which has a higher specific gravity than lead. It is made of a metal or alloy with a specific gravity of approximately 13.5 or more, such as.

FIG. 7 is a sectional view of the embodiment shown in FIG. 1 installed in a single-lens reflex camera having a TTL photometry device. In this camera, the light from the subject that has passed through the photographic lens _L1 is passed through a swinging mirror.
A part of the image is reflected by M ₁ and forms an image on the focus plate SC, and the other part passes through the swinging mirror M ₁ and then is reflected by the sub-mirror M ₂ and then passes through the imaging lens L ₂ . It is configured to form an image on the photoelectric conversion element D. A vertically running focal plane shutter is provided between the sub-mirror M ₂ and the film F, and a counterweight 22 is placed in an extremely narrow lower space S ₁ outside the path of the photometric light beam in front of the shutter substrate 1 on the front side of the shutter. will be installed. In this case, the counterweight 22
Since it is small and the amount of displacement is small, it can be installed without any problems.

Since the first embodiment shown in FIGS. 1 to 7 is constructed as described above, when the release button (not shown) provided on the camera body is pressed, the leading blade latching pawl 12 is activated by a known method. Rotate counterclockwise to release the restraint of the leading blade drive lever 9. Upon release, the leading blade drive lever 9 is rotated clockwise by the biasing force of the leading blade drive spring 11, and the leading blade drive arm 5 is rotated clockwise around the pin shaft 7 via the leading blade drive pin 13. With the help of the auxiliary lever 6, the rectangular blade 3a is translated downward. At the same time, the leading blade drive lever 9 rotates the auxiliary blades 3b to 3f in the clockwise direction around the pin shaft 8 via the leading blade driving pin 13, thereby rotating the rectangular blades 3a.
At the same time, it is moved to a retracted position below the opening 2, and exposure is performed.

On the other hand, as the leading blade drive lever 9 is rotated clockwise, the gear 14 is rotated clockwise, and the segment gear 15 that meshes with the gear 14 is rotated counterclockwise. This counterclockwise rotation of the segment gear 15 causes the pin 18 to rotate counterclockwise around the pin shaft 16 via the bending plate 17 fixed to the segment gear 15 . This counterclockwise rotation of the pin 18 means that the pin 18 is displaced to the left in FIG. 4, so the flange of the weight drive shaft 19 is Rotate the section 19a clockwise. By this clockwise rotation of the flange portion 19a, the counterweight 22 is moved to the weight drive shaft 1 along with the swing arms 23 and 23'.
9 and the support shaft 25 in a clockwise direction to the position shown by the chain line in FIG. Therefore, the center of gravity G of the counterweight 22 is displaced by a distance S to the left in FIG. This direction of displacement is opposite to the running direction of the rectangular blade 3a. Also,
The auxiliary blades 3b to 3f are rotationally displaced around the pin shaft 8, but the center of gravity of each auxiliary blade 3b to 3f does not displace much in the left-right direction (lateral direction) in FIG. 3 when the shutter is running. First, since it is largely displaced only in the vertical direction (vertical direction), it can be considered that the entire leading blade group including the rectangular blade 3a runs in the vertical direction. In other words, the rectangular blade 3a
It can be seen as traveling in a direction perpendicular to the exposed edge of the . Therefore, if the multiplicative product (m-s) of the inertial mass m of the counterweight 22 and the movement amount s of its center of gravity is made approximately equal to the multiplicative product of the inertial mass of the leading blade group 3 and the movement amount of its center of gravity, the balance can be achieved. Since the weight 22 and the leading vane group 3 have approximately the same momentum and move in opposite directions, the reactions between them cancel each other out. However, in this case, the multiplicative product of the inertial mass and the center of gravity movement of the leading blade group 3 is the sum of the multiplicative products of the inertial mass m' and the center of gravity movement s' for each blade (3a to 3f) (Σm's'). Therefore, by making the inertial mass m of the counterweight 22 sufficiently larger than the inertial mass of the leading blade group 3, it is possible to maintain balance with the leading blade group 3 even if the movement amount s of the center of gravity of the balancing weight 22 is extremely small. , it is possible to almost prevent vibrations caused by the running of the leading blade of the camera body.

In the embodiment shown in FIG. 1, the leading blade travels downward and the leading blade drive lever 9 is provided below the trailing blade drive lever 9', so that the counterweight 2
2 is provided on the shutter board below the shutter opening 2. However, some longitudinally running focal plane shutters in which the leading and trailing blades run in the opposite direction (upward) to the shutter shown in FIG. 1 are also commonly used. FIG. 8 is a plan view showing a second embodiment of the present invention incorporated into a vertically running focal plane shutter of the type in which the blades run upward. This second embodiment corresponds to an upside-down version of the first embodiment shown in FIG. 1, and the functions of the components used therein are the same as those in FIG. 1. Therefore, in the embodiment shown in FIG. 8, all members having the same functions as those in the first embodiment are designated by the same reference numerals as in FIG. 1, and a detailed explanation of the structure thereof will be omitted.

In the second embodiment shown in FIG. 8, when the shutter button (not shown) is pressed, the leading blade drive lever 9, which had been latched by the leading blade latching pawl 12, is released from its restraint, and the leading blade drive lever 9 is released. The biasing force of the spring 11 rotates the pin shaft 10 in a counterclockwise direction. This rotation of the leading blade drive lever 9 causes the trailing blade 3 to travel upward via the leading blade driving pin 13.

On the other hand, due to the counterclockwise rotation of the leading blade drive lever 9, the pin 18 rotates clockwise around the pin shaft 16 via the gear 14, the segment gear 15, and the bending plate 17, and has a flange 19a. The counterweight 22 is rotated downward in FIG. 8 via the weight drive shaft 19 and the swing arm 23. This counterweight 2
The direction of displacement of the counterweight 2 is opposite to the running direction of the leading blade 3, and in order to balance the momentum of both, the specific gravity of the counterweight 22 is set to be approximately 13.5 or more, which is greater than lead, so that the inertial mass of the counterweight 22 is the same as that of the leading blade 3. is constructed so that it is larger than the inertial mass of. Therefore,
In the second embodiment as well, the counterweight 22 can be made small and its displacement can be made extremely small. Therefore, the space required for this counterweight 22 may be extremely small, so in the second embodiment, the counterweight 22 is arranged as shown in FIG.
It can be installed in an extremely narrow space _S2 between the focusing plate SC and the shutter board 1 above the swinging mirror _M1 .

FIG. 10 shows a configuration in which a trailing blade vibration isolator is further added to the leading blade vibration isolator shown in FIG. In the rear blade vibration isolator, similarly to the leading blade vibration isolator, a rear blade drive lever 9' biased by a rear blade drive spring 11' and a gear 14' are integrated, and both are attached to the shutter board 1. A segment gear 15' that is rotatably supported by a pin shaft 8' implanted in the shutter board 1 and meshed with the gear 14' is rotatably supported by a pin shaft 16' implanted in the shutter base plate 1. .
Swing arms 23A, 23A' that support a counterweight 22' from a rear blade latching claw 12' that latches the rear blade drive lever 9' and a bending plate 17' that is fixed to the segment gear 15'. The weight displacement mechanism up to the support shaft 25' and the vibration isolator for the leading blade are all constructed of the same members as those in the embodiment shown in FIG. 1, so a detailed explanation of their construction will be omitted.

In the third embodiment shown in FIG. 10, when the shutter button (not shown) is pressed, the leading blade latching pawl 12 is displaced counterclockwise, the restraint of the leading blade drive lever 9 is released, and the leading blade 3 is moved as shown in FIG. This is exactly the same as the first embodiment shown in FIG. 1, in which the counterweight 22 is rotated upward via the gear 14 at the same time as the leading blade is caused to travel downward, thereby preventing vibration of the leading blade during travel.

When the trailing blade latching pawl 12' is rotated clockwise by known means after a predetermined delay time following the running of the leading blade 3, the trailing blade drive lever 9' is released and the trailing blade drive spring 11' is released. Due to the biasing force, it rotates clockwise about the pin shaft 8', causes the rear blade (not shown) to travel downward via the drive pin 13', and closes the shutter opening 2. Further, the gear 14' rotates clockwise together with the rear blade drive lever 9', and the segment gear 15' rotates counterclockwise about the pin shaft 16'. The counterclockwise rotation of the segment gear 15' causes the bending plate 17' to rotate counterclockwise, and the counterweight displacement mechanism of the leading blade prevention device is implanted in the bending plate 17', which has the same structure as the counterweight displacement mechanism of the leading blade prevention device. The pivot arm 23A fixed to the weight drive shaft 19' and the support implanted in the support base 24' are connected to each other via the spindle drive shaft 19' rotatably supported on the bearing stand 20'. The counterweight 22', whose both ends are supported by a swinging arm 23A' pivotally supported by a shaft 25', is displaced upward in a direction opposite to the running direction (downward) of the rear blade.
Therefore, the vibration caused by the running of the trailing blade is also canceled out by the displacement of the counterweight 22'.

The above-described rear blade vibration prevention device is effective when camera shake as a reaction to the running of the rear blade is extremely large and cannot be substantially ignored. but,
As is clear from a comparison between FIG. 1 and FIG. 10, adding a vibration prevention device to the rear blade also doubles the weight and cost. However, regarding the leading blade, both the displacement of the camera body due to the reaction when the blade is running (camera shake while the blade is running) and the vibration due to the restoring force of the camera support body after that displacement (camera shake after the blade is running) are reflected in the camera. On the other hand, since the rear blade closes the screen at the end of its travel, the period in which it affects the photographic screen is only while the rear blade is traveling. The amount of displacement of the camera (camera shake amount) due to this blade running increases as the distance traveled by the blade increases, that is, as the blade approaches the end of its travel. This occurs only in a small portion of the area that is still exposed to light at the end of the process. On the other hand, vibrations caused by the restoring force of the camera support after the leading blade travels cause camera shake in the entire exposed photographic screen, and the effect thereof is extremely large. Therefore, if the camera shake while the trailing blade is running can be ignored, it is not necessary to provide a counterweight that is linked to only the leading blade and not to the trailing blade. Thereby, weight and cost can be reduced.

In each of the longitudinally running focal plane shutters in the above embodiments, as shown in FIG. It is composed of a plurality of auxiliary blades that rotate around a pin shaft to cover the remainder of the shutter opening that cannot be covered by the blades. but,
The shutter used in the present invention has a plurality of rectangular blades connected to the drive arm and auxiliary arm that constitute a parallelogram link mechanism, and these rectangular blades move in parallel together to open and close the shutter opening. It may be something you have done. Further, since the vibration prevention device of the present invention can be installed in an extremely narrow space, it can be effectively applied not only to a focal plane shutter installed immediately in front of a film, but also to a behind shutter installed immediately after a photographic lens.

As described above, according to the present invention, the counterweight that moves in the opposite direction to the light shielding body in conjunction with the travel of the light shielding body can be formed in a small size, and the amount of displacement thereof can be made extremely small. It can be installed within a small space and can sufficiently prevent camera shake.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing a first embodiment in which the present invention is applied to prevent vibration of a leading blade, and FIG. 2 is a plan view showing the − of FIG.
3 is a plan view showing the structure of the shutter blade in FIG. 1, FIG. 4 is a cross-sectional view in FIG. 2, FIG. 5 is a cross-sectional view in FIG. FIG. 7 is a sectional view of the embodiment shown in FIG. 1 installed in a single-lens reflex camera, FIG. 8 is a plan view showing the second embodiment of the present invention, and FIG. 8
FIG. 10 is a cross-sectional view of a single-lens reflex camera equipped with the illustrated embodiment, and FIG. 10 is a plan view of a third embodiment of the present invention applied to vibration prevention of both the leading blade and the trailing blade. 1... Shutter board, 3, 4... Light shielding body, 1
9, 19', 25, 25'... Support shaft, 22, 22'
...Balance weight, E...Exposure edge.

Claims (1)

[Scope of Claims] 1. A camera shutter whose aperture is opened and closed by a pair of light shielding bodies running in one direction, in which at least one of the light shielding bodies is linked with a counterweight having an inertial mass larger than that of the one light shielding body; The counterweight is swingably supported by a support shaft provided parallel to the exposure edge of the body, and the counterweight is moved in the direction in which the exposure edge moves in conjunction with the movement of the light shield. 1. A camera shutter anti-vibration device, characterized in that it is configured to be displaced in the opposite direction and the amount of displacement is shorter than the moving distance of the exposure edge. 2. The one light shield is a first light shield 3 that opens an opening, and the counterweight 22 is displaced in a direction opposite to the travel of the first light shield in conjunction with only the travel of the first light shield. The vibration isolating device for a camera shutter according to claim 1, characterized in that the vibration isolating device is configured as follows. 3. The camera shutter according to claim 1 or 2, wherein the counterweight 22 is fixed to swing arms 23, 23' supported by the support shafts 19, 25. Anti-vibration device.