JPH07152065A - Exposure unevenness preventing device for focal-plane shutter for camera - Google Patents

Abstract

PURPOSE:To prevent the occurrence of the unevenness of an exposure caused by a big change in the prescribed posture of a slit forming blade, when a blade group is braked by a braking device before the completion of exposure traveling, in a focal-plane shutter provided with 1st and 2nd blade groups. CONSTITUTION:First and second regions 9b and 9c are formed on a leading blade pressing plate 9 coming into slide contact with the tip of the leading blade group on the part of an exposure aperture. A leaf spring 8 is arranged between the base plate 1 of a shutter and the leading blade group pressing plate 9, to press the second region 9b. When the leading blade group is braked by the braking device before the completion of the exposure traveling, the tip of the slit forming blade 4 is pressed by the first region 9b and its posture is held.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure unevenness prevention apparatus for a focal-plane shutter for a camera, which is provided with two sets of blade groups composed of a plurality of sheets.

[0002]

2. Description of the Related Art This type of focal plane shutter is
Usually, each blade group is pivotally supported by an arm pivotally attached to the side of the exposure opening, and each blade group can be expanded and folded like a fan by rotating these arms. Each blade group is provided with a slit forming blade so that the slits formed by them expose the film. Therefore, the exposure time of the film is determined by the traveling speed of each blade group and the size of the slit width. As described above, the slit width is an extremely important factor for the exposure of the film, and the posture of one slit forming blade is collapsed and tilted during traveling, and the slit width formed between the other slit forming blade is constant. If there is no relation, that is, if the parallelism of the slit forming sides of the two slit forming blades exceeds the tolerance, the film surface is not uniformly exposed, resulting in uneven exposure. . The slit forming blade is usually designed so that the slit forming side operates in parallel with the long side of the exposure opening. Nevertheless, the slit forming blade causes the inclination and the inclination. Although there are tolerances in the pivot between the arm and the arm, the traveling speed and inertia of the blades, the degree of friction of each sliding surface, etc., the most important factor is the existence of the braking device. This braking device applies braking to the traveling of the blade group before the slit forming side of the slit forming blade has finished traveling through the exposure opening in order to prevent the bouncing phenomenon from occurring at the end of traveling of the blade group. Therefore, various configurations have been conventionally proposed. With the increase in shutter speed in recent years, this braking device brakes the arm and the drive lever without directly braking the blade group to prevent the blade group from being destroyed, and as a result, reduces the traveling speed of the blade group. . Therefore, when the brake is applied by the braking device, the tip of the slit forming blade moves due to inertia prior to the movement of the arm, and the above-described inclination occurs.

[0003]

In order to prevent the parallelism of the slit forming side from changing during the exposure run, it is best to make the tolerance in the pivotal support between the arm and the slit forming blade as small as possible. But doing so has its own limits. Furthermore, in order to prevent the inclination due to the contact with the braking device as described above, it is not possible to solve it at all by only taking measures on the processing accuracy.

The present invention has been made in view of the above problems, and an object thereof is to arrange the arm on the side opposite to the side of the exposure opening to which the arm is pivotally mounted. For a camera in which the slit forming blades are prevented from tilting as described above and the parallelism of the slit forming sides is maintained by using a well-known pressing plate that is in sliding contact with the end of the blade group (hereinafter referred to as the tip). An object of the present invention is to provide a device for preventing uneven exposure of a focal plane shutter.

[0005]

In order to achieve the above object, an exposure unevenness preventing apparatus for a focal plane shutter for a camera according to the present invention includes a front blade group including a slit forming blade pivotally supported by a front blade driving arm. A rear blade group including slit forming blades pivotally supported by the rear blade drive arm, a substrate on which the front blade drive arm and the rear blade drive arm are pivotally attached at one side of the exposure opening, and the front blade. Cover plate attached to the substrate so as to cover the group and the rear blade group with the substrate, and an intermediate plate attached to the substrate so as to separate the front blade group and the rear blade group from each other. And a leading blade holding plate arranged so as to sandwich the end portion of the leading blade group between the intermediate plate and the other side portion of the exposure opening, and an end of the trailing blade group on the other side portion of the exposure opening. Part is sandwiched between the intermediate plate and In a focal plane shutter for a camera including a trailing blade holding plate, at least one of the leading blade holding plate and the trailing blade holding plate is provided with a cutout portion or a long groove portion for forming two regions separately. An elastic member for pressing the end of the slit forming blade is provided in one of the areas.

[0006]

The leading blade group is started by the shutter release, and the exposure aperture is opened by the slit forming blade while being folded downward. After a predetermined time, the rear blade group starts to cover the exposure opening with the slit forming blade at the top. Both blade groups continue to run by moving the slits formed by both slit forming blades downward.
The leading blade group is braked by the braking device before the slit forming blade reaches the lower end of the exposure opening. At this time, a force acts to tilt the slit-forming blades of the leading blade group to break the parallelism with the slit-forming blades of the trailing blade group. First of board
Since it has reached the corresponding position of the area and is sufficiently pressurized by the action of the leaf spring, the leading blade group completes the traveling without being affected by the force for breaking the parallelism described above. The trailing blades also complete the running in the same manner.

[0007]

Embodiments of the present invention will be described with reference to FIGS. FIG. 1 is a front view showing a charged state of a shutter, and FIGS. 2A to 2G are main component parts of the embodiment shown in FIG. 1 excluding a blade group and the like. FIG. 3 is a front view of relevant parts showing a position where the front blade group is braked by the braking device immediately before the end of the exposure traveling, and FIG. 4 is an enlarged right side view of FIG.

In the figure, 1 is a substrate, and an exposure opening 1
a, arc-shaped holes 1b, 1c, and shafts 1d, 1 in the rear direction
e, 1f, 1g, 1h, 1i are planted. Reference numerals 2 and 3 denote leading blade group arms pivotally attached to the shafts 1f and 1g, respectively, and pivotally support a leading blade group having a five-blade structure including the slit forming blade 4 in a known manner. Reference numerals 5 and 6 denote rear blade group arms pivotally attached to the shafts 1d and 1e, respectively, which pivotally support the rear blade group having five sheets, but only the slit forming blade 7 is shown in FIG. Illustration of other blades is omitted.
The arms 3 and 5 are formed with holes 3a and 5a, respectively,
Pins of a leading blade driving member and a trailing blade driving member (not shown) are fitted through the arcuate holes 1b and 1c.

A leaf spring 8, a leading blade holding plate 9, an auxiliary holding plate 10, an intermediate plate 11, a trailing blade holding plate 12 and a cover plate 13 are attached to the shafts 1h and 1i of the substrate 1 in this order from the rear side. There is. Although not explicitly shown on the shafts 1e, 1f, 1h, 1i, a stepped portion is formed, and the cover plate 13 is formed on the shafts 1h, 1h.
The recesses 13d and 13e are adapted to engage with the shafts 1e and 1f by sliding them to the left in FIG. 1 after they are fitted into the shafts 1e, 1f and 1f.
It is held securely with h and 1i. The bifurcated portions 13a, 13b serve to prevent the arms 3, 5 from axially moving on the shafts 1d, 1g during operation. Leading blade presser plate 9,
The auxiliary pressing plate 10, the intermediate plate 11, and the trailing blade pressing plate 12 are attached to the shafts 1h and 1i so as to be movable in the axial direction. Although not shown, the intermediate plate 1 is attached to the shaft 1h.
A spacer is provided between 1 and the rear blade pressing plate 12.

A hole 12a is formed in the trailing blade holding plate 12, and a projecting portion 13c provided on the cover plate 13 is loosely fitted thereto. The leading blade pressing plate 9 is made of synthetic resin, is provided with a notch 9a, and separates a first region 9b and a second region 9c on both sides thereof. Since the notch 9a is intended to separate the first region 9b and the second region 9c from each other, it may be a long groove (slot). The leaf spring 8 has a V shape when viewed from the side and pushes the leading blade pressing plate 9, the auxiliary pressing plate 10, and the intermediate plate 11 to the right in FIG. It has been blocked from moving to the right. The auxiliary pressing plate 10 has a projecting portion 10a, which is for covering the notch groove 11a of the intermediate plate 11, and the purpose thereof is described in Japanese Utility Model Laid-Open No. 5-45659. Is omitted. The leading edge of the leading blade group is sandwiched between the leading blade pressing plate 9 and the auxiliary pressing plate 10 so as to be slidable.
The rear blade group has an intermediate plate 11 and a rear blade pressing plate 1 at the front end thereof.
It is sandwiched so as to be slidable between the two.

FIG. 1 shows the shutter being charged. When the shutter is released in this state, the pin of the leading blade driving member (not shown) fitted in the hole 3a of the arm 3 operates along the arcuate hole 1c. As a result, the arm 3 rotates right about the shaft 1g. Accompanied therewith, the arm 2 connected via the front blade group also turns to the right. By rotating the arms 2 and 3 to the right, the leading blade group starts to move downward so as to be folded, and the slit forming blade 4 opens the exposure opening 1a. Slit forming blade 4 of the leading blade group
3 reaches the position shown in FIG. 3 immediately before the exposure opening 1a is completely opened, the front blade group is braked. Various proposals have been made for this braking device as described above,
Recently, as the shutter speed increases, the blades are less likely to be directly braked, and it is common to directly brake the drive unit or arm. Since many such braking devices are known, detailed description thereof will be omitted.

When braking is performed by the above braking device,
The slit forming blade 4 receives a force in the clockwise direction due to inertia at a pivotal support portion with the arms 2 and 3. Therefore, the slit forming blade 4 tends to tilt to the lower right, but at this time, the tip end portion of the slit forming blade 4 comes into contact with the first region 9b of the leading blade pressing plate 9 pressed by the leaf spring 8. Since the pressure is applied from the direction orthogonal to the running direction of the slit forming blade 4, the running is completed without tilting. After a predetermined time has elapsed since the leading blade group started running, the trailing blade group similarly starts running by the arms 5 and 6, but the slit forming blade 4 of the leading blade group does not tilt as described above. Therefore, the slits formed between the slit forming blades 7 of the rear blade group complete the shooting without impairing their parallelism.

In the above description, the case where braking is applied only to the leading blade group has been described. However, in practice, braking is often applied to both the leading blade group and the trailing blade group, and braking is applied only to the trailing blade group. It is also possible to hang it. When braking is applied to the trailing blade group, the first region is provided by providing the trailing blade holding plate 12 with a notch or a long groove portion like the notch 9a provided in the leading blade holding plate 9. And a second region is formed, a leaf spring is arranged between the trailing blade holding plate 12 and the cover plate 13, and the first region of the trailing blade holding plate 12 may be pushed.

In the above embodiment, the auxiliary holding plate 10 is formed with the first region and the second region, and the leaf spring 8 is attached to the auxiliary holding plate 1.
Even if it is arranged between 0 and the intermediate plate 11, the same effect as the above-mentioned embodiment can be obtained. Further, the protrusion 13c of the cover plate 13 is eliminated, a protrusion or a protrusion corresponding thereto is provided on the substrate 1 side, and the intermediate plate 11 is formed with the first region and the second region.
By disposing the leaf spring 8 between the leading blade pressing plate 10 and the intermediate plate 11, it is possible to prevent the inclination of the slit forming blade 7 of the trailing blade group. Further, it is conceivable to provide a second auxiliary pressing plate adjacent to the back of the intermediate plate 11, that is, on the right side of the intermediate plate 11 in FIG. Of course, the second auxiliary pressing plate does not have the projecting portion 10a as provided in the auxiliary pressing plate 10. In this case, the first region and the second region are formed in each auxiliary pressing plate, and leaf springs are respectively arranged between each auxiliary pressing plate and the intermediate plate 11 so as to eliminate the protruding portion 13c of the cover plate 13. In this case, it is possible to prevent both the slit forming blades 4 and 7 from tilting.

In the above embodiment, the leading blade pressing plate 9 is made of synthetic resin, but if a metal plate is used,
When the first area 9b is pushed by the leaf spring 8, the second area 9c
This is because that also deforms due to the influence, and may affect the traveling of blades other than the slit forming blade 4. In that respect, if a resin sheet is used, it is easy to bend so that only the first region 9b can be easily deformed, and a surface treatment softer than the surface of the shutter blade can be applied. The risk of causing

[0016]

As described above, according to the present invention, at least one of the blade pressing plate and the intermediate plate, which are arranged so as to be in slidable contact with the leading end of the blade group on the side of the exposure opening, has a notch or By providing the long groove portion, the first region and the second region are formed separately, and one region is pressed by the elastic member,
Since the tip of the slit-forming blade during traveling is pressed when the blade group is braked, the slit-forming blade can travel without damaging a predetermined posture during braking and prevent uneven exposure.

[Brief description of drawings]

FIG. 1 is a front view of an embodiment of the present invention showing a charged state of a shutter.

FIG. 2 is a diagram of main components excluding the blade group in the embodiment shown in FIG.

FIG. 3 is a front view of an essential part showing a position where a front blade group is braked by a braking device.

FIG. 4 is a right side enlarged view of FIG.

[Explanation of symbols]

 1 substrate 1a exposure opening 1b, 1c arcuate hole 1d, 1e, 1f, 1g, 1h, 1i axis 2,3 leading blade group arm 3a, 5a, 12a hole 4,7 slit forming blade 5,6 trailing blade group arm 8 leaf springs 9 front blade group holding plate 9a notch 9b first region 9c second region 10 auxiliary holding plate 10a overhanging portion 11 intermediate plate 11a notched groove 12 rear blade holding plate 13 cover plates 13a, 13b bifurcated portion 13c protruding portion 13d, 13e recess

Claims (3)

[Claims] 1. A leading blade group including slit forming blades pivotally supported by a leading blade driving arm, a trailing blade group including slit forming blades pivotally supported by a trailing blade driving arm, the leading blade driving arm, and A substrate having a trailing blade drive arm pivotally attached to one side of the exposure opening, a cover plate attached to the substrate so as to cover the leading blade group and the trailing blade group with the substrate, and the leading edge. Arranged so that the blade group and the trailing blade group are separated from each other, and an end plate of the leading blade group is sandwiched between the intermediate plate attached to the substrate and the other side of the exposure opening. In a focal-plane shutter for a camera, the front-blade pressing plate is provided with a front-blade pressing plate, and a rear-blade pressing plate is disposed on the other side of the exposure opening so as to sandwich an end portion of the rear-blade group with the intermediate plate. , The number of leading blade holding plate and the number of trailing blade holding plate On one side, a notch or a long groove for separately forming two regions is formed, and an elastic member for pressing the end of the slit forming blade on one side of the region is provided. Exposure unevenness prevention device for focal plane shutter. 2. An auxiliary pressing plate is provided adjacent to at least one side surface of the intermediate plate, and a notch or a long groove for separating and forming the two regions is formed in the auxiliary pressing plate, and the auxiliary pressing plate is formed. The exposure unevenness preventing apparatus for a focal plane shutter for a camera according to claim 1, wherein the elastic member is provided between the plate and the intermediate plate. 3. An auxiliary pressing plate is provided adjacent to one side surface of the intermediate plate, a notch or a long groove is formed in the intermediate plate to separate and form the two regions, and the auxiliary pressing plate is provided. The exposure unevenness prevention apparatus for a focal-plane shutter for a camera according to claim 1, wherein the elastic member is provided between the elastic plate and the intermediate plate.