JP2001083572A - Focal plane shutter for camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive focal plane shutter constituted so that the tip parts of each blade is prevented from being displaced in the axial direction of an optical axis in the midst of actuating a blade group. SOLUTION: A shutter base plate 1 and an auxiliary base plate 3 are made of metal and space between them is partitioned by an intermediate plate 2 so as to constitute the blade chambers of a front blade group and a rear blade group. Each of the blade groups is constituted of plural arms and the plural blades pivotally supported in turn in the length directions of the arms. The plates 1 and 3 are not mutually fitted in parallel but they are mutually fitted by leaving a prescribed interval by a shaft 1p, a bending part 3d and the like in the actuation areas of the arms. However, they are mutually fitted in the actuation areas of the tip parts of each of the blades so that an interval being narrower than the prescribed interval is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of operating a front blade group and a rear blade group sequentially in the same direction during photographing, and exposing an image forming surface by slits formed by slit forming blades of both blade groups. And a focal plane shutter for a camera.

[0002]

2. Description of the Related Art Most of recent focal plane shutters have two blade chambers formed by partitioning most of a space between two ground plates with an intermediate plate, and these blade chambers have a front blade group and a rear blade group. The blades are arranged. Each of the blade groups has substantially the same configuration. Basically, two blades pivotally attached to one main plate at one side position of the exposure opening, and two horizontally long It consists of a plurality of blades that are pivotally supported in the longitudinal direction of the two arms by one connection shaft at a time, and among the plurality of blades, the blade is pivotally supported at the tip of the arm. The blade is a slit forming blade. Exceptionally, it is also known that the arm has three or more arms. Even in such a case, one blade is pivotally supported on any two of the arms. I am trying to.

[0003] Further, as a specific pivotal structure of each blade with respect to the two arms, generally, the arm and the blade are overlapped, and rivet parts are used for holes formed in them. The connecting shaft is inserted from the arm side, and the inserted end is swaged against the blade. When arranging each blade group in each blade chamber, it is usual that a plurality of blades are set to the intermediate plate side and the arm is set to the main plate side. It will stick out. In addition, each blade group has a lot of pivot portions having such a configuration, and a fitting portion between the hole and the shaft is provided with a tolerance. In such a case, rattling of the fitting portions becomes a major factor, causing a complicated operation, which makes it impossible to perform appropriate exposure control by the slit forming blades or breaks the blade group. It will be.

[0004] In order to solve such a situation, how to prevent a blade or an arm made of a thin material from being displaced or deformed in the axial direction of the optical axis during operation. The important point is how to reduce the impact when the exposure operation is stopped.However, since it is impossible to solve it with just one measure, The current situation is that the proposed measures are combined to solve the problem.

[0005] By the way, as is well known, the two ground plates are:
The opening formed in the substantially central portion is arranged so as to overlap the opening formed in the intermediate plate, and at least one of the openings regulates the shape of the rectangular exposure opening. I have to. In a normal photographing posture of the camera, the exposure opening is usually a horizontally long rectangle, and the arms of each of the above-mentioned blade groups are arranged on one short side of the exposure opening. It is pivoted to one area.

Therefore, the distance between the base plate and the intermediate plate is equal to the sum of the thickness of the plurality of blades, the thickness of the arm, and the amount of protrusion of the head of the connecting shaft in the vicinity of one of the short sides. However, since there is no arm in the side region on the other short side, an extra space is provided by the thickness of the arm and the amount of protrusion of the head of the connecting shaft, (The end opposite to the pivot with respect to the arm) is easily displaced in the axial direction of the optical axis. Therefore, conventionally, in order to fill the extra space, when the base plate is made of metal, a member called a blade holding plate is arranged between the base plate and the intermediate plate, and when the base plate is made of synthetic resin. Is
The thick portion raised on the intermediate plate side is formed by integral molding. The former example is disclosed in
This is described in JP-A-1-38470, and the latter example is described in JP-A-10-133255.

[0007]

The structure disclosed in Japanese Patent Application Laid-Open No. H11-38470 is a structure which has been used for a long time, and is advantageous for stably obtaining high-speed operation of the blade group. Configuration. However, at present, there is a problem in that the cost is increased by the necessity of manufacturing the blade holding plate as a separate part. The one described in JP-A-10-133255 is very advantageous in terms of cost because the base plate is made of synthetic resin and the blade holding plate is not manufactured as a separate part. However, in order to ensure rigidity and strength, there is a problem that the thickness of the ground plane must be greater than that of a metal case. In particular, the auxiliary ground plane (the ground plane arranged on the image forming plane side, When the thickness of the cover plate (also referred to as a cover plate) increases, the operating surface of the blade group is too far from the image forming surface, so that there is a problem that it is difficult to be used in a high-end machine.

The present invention has been made in order to solve such a problem, and an object of the present invention is to make the auxiliary base plate a thin metal, but without providing a conventional blade holding plate. Another object of the present invention is to provide a low-cost focal plane shutter for a camera, which is capable of suppressing displacement of a blade tip in an axial direction of an optical axis.

[0009]

In order to achieve the above object, in a focal plane shutter for a camera according to the present invention, a group of front blades and a group of rear blades arranged between a shutter base plate and an auxiliary base plate are provided. Each of the plurality of arms has one end of a plurality of blades having an elongated shape pivotally supported in the longitudinal direction of the plurality of arms in order, and the plurality of arms of both the blade groups share the same side area of the exposure aperture. The two ground plates are pivotally attached to one of the two ground plates, and at least the auxiliary ground plate is made of metal, and the distance between the ground plates is opposite to the side region in the side region. So that they are attached to each other. In that case, it is a peripheral position of the two ground plates,
In the vicinity of the position where the side of the exposure opening on the side where the arms of both blade groups are pivotally attached is extended, at least one of the two ground plates is provided with a spacing control means. It becomes possible to secure suitably. Further, the auxiliary base plate is formed with at least two bent portions in order to reduce the interval between the auxiliary base plate and the shutter base plate in the opposite side region than the region where the arms of both blade groups operate. It is advantageous for mass production.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to a first embodiment shown in FIGS. 1 to 3 and a second embodiment shown in FIG. FIG. 1 is a plan view of the first embodiment viewed from the subject side when assembled in a camera, FIG. 2 is a bottom view of FIG. 1, and FIG. 3 is a right side view of FIG. FIG. 4 is a bottom view of the second embodiment shown in the same manner as FIG. FIG. 5 is a bottom view of a conventional example shown in the same manner as FIGS. 2 and 4 for comparison with the two embodiments.

First, the structure of the first embodiment will be described.
For convenience of explanation, in FIG. 1, the object side of each component is referred to as a front side, and the image forming surface side is referred to as a back side. The shutter base plate 1 of this embodiment is made of metal, and has an opening 1a at a substantially central portion. The opening 1a
Are formed with two arc-shaped long holes 1b and 1c in the left region of them.
A well-known buffer member is attached. The holes 1d, 1e, 1f formed at the three corners of the shutter base plate 1 are:
A hole for attaching the shutter unit to the camera body.

Further, a shaft 1 is provided on the front side of the shutter base plate 1.
g, 1h. A drive member for the front blade and a drive member for the rear blade are rotatably mounted on these shafts 1g and 1h, and the respective drive pins are elongated holes 1b and 1c.
And project to the rear side of the shutter base plate 1. However, since their configurations are well known, they are not shown. In the normal case, the area on the left side of the opening 1a includes:
Although the mechanisms necessary for shutter opening / closing control, such as a set member and an electromagnet, including the above-described driving members, are arranged, their configuration is not directly related to the present invention. The approximate range occupied is indicated by a two-dot chain line.

On the rear side of the shutter base plate 1, eight shafts 1 are provided.
i, 1j, 1k, 1m, 1n, 1p, 1q, 1r are erected. Among them, the shafts 1i and 1k are arranged concentrically with the shafts 1g and 1h on the surface side described above, and the shafts 1j and 1k are arranged concentrically.
It is for attaching each blade group described later together with 1 m. Although not explicitly shown, screw holes are formed in the tip surfaces of the shafts 1n and 1p, and grooves are formed in the circumferential surface of the tip portions of the shafts 1q and 1r. The shafts 1n, 1q, and 1r are for mounting an intermediate plate and an auxiliary base plate, which will be described later, and the shaft 1p is for mounting an auxiliary base plate.

With the above description, the structure of the shutter base plate 1 has been described. Hereinafter, members to be mounted on the back side of the shutter base plate 1 and the mounting structure thereof will be described. However, the overall configuration on the back side will be briefly described. Shutter base plate 1
An intermediate plate 2 and an auxiliary base plate 3 are sequentially mounted at a predetermined interval on the back side of the base plate. In this embodiment, the space between the shutter base plate 1 and the intermediate plate 2 A blade chamber is provided, and a space between the intermediate plate 2 and the auxiliary main plate 3 is a blade chamber of a rear blade group.

An opening similar to the opening 1a of the shutter base plate 1 is formed substantially at the center of each of the intermediate plate 2 and the auxiliary base plate 3, and these three openings are overlapped to form a rectangular shape. Is formed so as to be horizontally elongated. However, FIG. 1 omits the illustration of the intermediate plate 2 to prevent the drawing from being difficult to see, and shows the shape of the auxiliary base plate 3 by a one-dot chain line. Only 3a is shown. In the present embodiment, the intermediate plate 2 is also formed with a long hole having the same shape at a position corresponding to the long holes 1b and 1c of the shutter base plate 1.

Therefore, first, the configuration of the front blade group will be described. The front blade group is composed of two arms 4 and 5 and four blades 6, 7, 8, and 9 pivotally supported in the longitudinal direction thereof. 9 is a slit forming blade. The arms 4 and 5 are rotatably attached to the shafts 1 i and 1 j of the shutter base plate 1, respectively. The arm 4 is formed with a long hole 4a, in which a driving pin of the driving member for the leading blade (not shown) is fitted.

The respective pivotal structures of the two arms 4, 5 and the four blades 6, 7, 8, 9 are the same as in the prior art. 5 and the blades 6, 7, 8, 9 are inserted into the predetermined holes formed from the arms 4, 5 side, and the inserted ends are fixed to the blades 6, 7, 8, 9 by caulking. I have. Then, the arms 4 and 5 have the shutter base plate 1 more than the blades 6, 7, 8 and 9.
, The heads of the connecting shafts protrude from the arms 4 and 5 toward the shutter base plate 1 side.

Next, the structure of the rear blade group disposed on the back side of the intermediate plate 2 will be described. The rear blade group is composed of two arms 10, 11 and four blades 12, 13, 14, 15 pivotally supported by them via a well-known connecting shaft. It is. The rear blade group is arranged such that the above-mentioned front blade group is turned upside down. The two arms 10 and 11 are on the auxiliary base plate 3 side, and the blades 12, 13, 14, and 15 are intermediate. Board 2
Side. Therefore, the heads of the circular connection shafts protrude from the arms 10 and 11 toward the auxiliary base plate 3. The arms 10 and 11 are connected to the shaft 1 of the shutter base plate 1.
k, 1 m
A driving pin of a rear blade driving member (not shown) is fitted into the long hole 10a.

The auxiliary base plate 3 of this embodiment is a shutter base plate 1
The opening 3a, which has been described above, is formed substantially at the center in the same manner as described above. Further, a slot having substantially the same shape is formed at a position corresponding to the slots 1b and 1c of the shutter base plate 1, and the slot overlapping the slot 1b is the slot 1
It is formed slightly longer than b, and a bent portion 3b is formed at its lower end. In addition, the four bent portions 3c, 3d, 3e, and 3f are provided around the auxiliary base plate 3.
Are formed, of which the bent portions 3b and 3c
Are for maintaining the interval between the intermediate plate 2 and the auxiliary base plate 3, and the bent portions 3d, 3e, 3f are for maintaining the interval between the shutter base plate 1 and the auxiliary base plate 3. Further, the auxiliary base plate 3 has holes formed at four corners. Two of them are holes 3g and 3h in the shape of a keyhole on the side, and the other two are circular, though not explicitly shown, and have a shutter base plate 1
Are formed at positions corresponding to the axes 1n and 1p.

Here, how to assemble the present embodiment will be described. First, the arms 4 and 5 of the front blade group are moved to the shutter base plate 1.
Rotatably mounted on the shafts 1i, 1j of the
(See FIG. 3) is rotatably fitted to the shaft 1q of the shutter base plate 1. Thereafter, three holes (not shown) formed in the intermediate plate 2 are connected to the shafts 1n, 1q,
1r. Next, the arms 10 and 11 of the rear blade group
Is rotatably fitted to the shafts 1k and 1m of the shutter base plate 1, and the annular spacer 17 (see FIG. 3) is rotatably fitted to the shaft 1r of the shutter base plate 1.

Thereafter, the auxiliary base plate 3 is attached to the shafts 1n, 1p, 1q, 1r of the shutter base plate 1. At this time, first, the shafts 1q, 1r are inserted into the large openings of the holes 3g, 3h. The auxiliary base plate 3 is moved to the left in FIG. 1 so that the edges of the small openings of the holes 3g and 3h are
q, 1r. Then, after inserting the screws into the holes of the auxiliary base plate 3 which are not explicitly shown, the screws are screwed into the screw holes formed on the tip surfaces of the shafts 1n and 1p, and the assembling operation is completed. At this time, the head of one screw 18 screwed to the shaft 1p is shown in FIG.

In the state assembled in this manner, the shutter base plate 1, the intermediate plate 2, the auxiliary base plate 3
Has the following relationship: First, as can be seen from FIG. 2, the intermediate plate 2 is disposed obliquely between the shutter base plate 1 and the auxiliary base plate 3, but as described above, the spacers 16 and 17 It is maintained because it is arranged on the opposite side of the plate and the bent portion 3c formed on the auxiliary base plate 3 is formed higher than the bent portion 3b. It is well-known that the intermediate plate 2 is arranged in this manner. When the four blades of each blade group are in the unfolded state rather than in the superimposed state, the intermediate plate 2 and the local plates 1 and 3 This is because the extra interval is not required, so that the extra interval is made as small as possible to obtain a stable developed state, and the shutter is made as thin as possible.

On the other hand, in the present embodiment, the bent portions 3d,
The height of 3e is substantially the same as the height of axes 1n and 1p,
It is higher than the height of the shafts 1q and 1r up to the annular groove. Therefore, as can be seen from FIG. 2, the thin metal auxiliary base plate 3 bends from a position slightly to the right of the bent portion 3d (and the bent portion 3e) to the position of the shaft 1r (and the shaft 1q). It is attached so as to be substantially oblique to the shutter base plate 1. For this reason, in the present embodiment, in the operation region of the arm, the distance of the sum of the thickness when the four blades are superimposed, the thickness of the arm, and the height of the head of the connecting shaft is: Bent part 3d,
3e is suitably secured, and in the area on the right side of the exposure opening, a minimum interval required for operating only the blade is secured.

In the present embodiment, the auxiliary base plate 3 is provided with the bent portions 3d and 3e in order to suitably secure the interval between the shutter base plate 1 and the auxiliary base plate 3 in the arm operating region. However, such an interval regulating means may be provided on the shutter base plate 1 and does not have to be formed as a bent portion. In the above description, it has been described that the auxiliary base plate 3 is bent in the assembled state. However, the auxiliary base plate 3 is previously processed so as to be oblique from the vicinity of the bent portions 3d and 3e and then assembled. You can do it. However, even in such a case, it is better to provide the above-mentioned space regulating means in consideration of various processing errors.

By the way, in order to make it easier to understand the difference between this embodiment and the conventional example, the configuration of the conventional example will be described with reference to FIG. FIG. 5 is similar to FIG. 2 of the present embodiment. In the case of this conventional example, since the height of the shaft 1p is the same as the height of the shaft 1r up to the annular groove, the auxiliary base plate 3 is horizontal to the shutter base plate 1. Therefore, it is necessary to reduce the distance between the two ground plates 1 and 3 in the area on the right side of the exposure opening, and the blade holding plates 19 and 20 are provided in the respective blade chambers (the planar shape is indicated by a two-dot chain line in FIG. 1). Has been arranged. On the other hand, in this embodiment, since the thickness of the auxiliary base plate 3 is the same as the conventional one,
The distance from the imaging plane can be suitably obtained as before, and
The blade holding plates 19 and 20 are not required.

Next, the operation of this embodiment will be briefly described. FIG. 1 shows a state immediately after the end of the exposure operation. At this time, the front blade driving member (not shown) rotatably attached to the shaft 1g on the front side of the shutter base plate 1 includes:
The drive pin is in contact with a buffer member (not shown) attached to the upper end of the elongated hole 1b, so that the counterclockwise rotation is prevented. Therefore, arm 4 also
The blades are rotated counterclockwise by the drive pins, and the four blades 6, 7, 8, 9 of the front blade group are superimposed and stored above the exposure opening.

On the other hand, a rear blade driving member (not shown) rotatably mounted on the shaft 1h on the front side of the shutter base plate 1 is shown with its driving pin mounted on the upper end of the elongated hole 1c. The arm 10 is also rotated counterclockwise by its drive pin because the counterclockwise rotation is prevented by abutting against the non-cushioning member. Feather 12,1
3, 14, and 15 are developed to cover the exposure aperture.

In the state of FIG. 1, when the shutter is set, first, the driving member for the front blade described above is turned clockwise against the urging force of the driving spring for the front blade (not shown). And the drive pin fitted into the hole 4a rotates the arm 4 clockwise to reduce the overlapping amount of the four blades 6, 7, 8, 9 of the front blade group. While operating downward. Thereafter, the slit forming blades 9 of the front blade group and the slit forming blades 15 of the rear blade group
When the overlap amount with the rear blade reaches a predetermined amount, the rear blade driving member is rotated clockwise against the urging force of the rear blade driving spring (not shown), and fitted in the hole 10a. The drive pin rotates the arm 10 in the clockwise direction to operate the four blades 12, 13, 14, 15 of the rear blade group downward while increasing the amount of overlap therebetween.

As described above, since the leading blade group and the trailing blade group have many pivots with tolerances, the arms and the blades move in the axial direction of the optical axis during the set operation. It is easy to displace. Therefore, particularly, the tip of each blade becomes unstable. In the case of the present embodiment, the shutter base plate is provided in the operation region of the tip of each blade even if the conventional blade holding plate is not provided. 1 and the auxiliary base plate 3 are narrow, so that the tip of each blade is hard to be displaced.
The set operation is performed smoothly. Then, the four blades 6, 7, 8, and 9 of the front blade group are in a developed state to completely cover the exposure opening, and the four blades 12, 1 of the rear blade group are set.
The set operation is completed when 3, 14, and 15 are superimposed and stored at a position below the exposure opening.

Next, when the release button of the camera is depressed during photographing, first, a driving member (not shown) for the front blade is rotated counterclockwise, and its driving pin is
Is rotated in the counterclockwise direction to cause the front blade group to perform an exposure operation. At this time, the four blades 6, 7, 8,
The exposure opening 9 is opened by the slit forming edge of the slit forming blade 9 while increasing the mutual overlapping amount. This operation is performed by a strong urging force of a driving spring for the front blade (not shown). Therefore, the force for displacing the tips of the blades 6, 7, 8, 9 in the axial direction of the optical axis is not the ratio at the time of the set operation. However, also in this case, the unevenness of the tip of each blade is suitably suppressed, and a smooth exposure operation is performed. After that, the front blade group stops when the driving pin of the driving member for the front blade (not shown) comes into contact with the buffer member (not shown) attached to the upper end of the long hole 1b.

As described above, when a predetermined time has elapsed since the start of the exposure operation of the front blade group, the rear blade driving member (not shown) is rotated counterclockwise. As a result, the drive pin rotates the arm 10 in the counterclockwise direction, so that the four blades 12, 13, 1
The exposure openings 4 and 15 are closed by the slit forming edges of the slit forming blades 15 while reducing the amount of overlap between them. The exposure operation is performed by a strong biasing force of a rear blade drive spring (not shown), so that the blades 12, 13, 14, 1 are similar to the case of the front blade group.
The distal end portion 5 is about to be largely displaced, but the displacement is suitably suppressed as in the case of the set operation. Thereafter, the rear blade group stops when the drive pin of the rear blade drive member (not shown) comes into contact with a buffer member (not shown) attached to the upper end of the elongated hole 1c. The state where the exposure operation has been completed is the state shown in FIG.

Next, only the configuration of the second embodiment will be described with reference to FIG. FIG. 4 shows the same reference numerals as those in the first embodiment, but differs from the configuration of the first embodiment in that, at the stage of manufacturing the auxiliary base plate 3, 2 The point is that bending is performed linearly in the vertical direction in FIG. Therefore, in the assembled state, only the portion between A and B is inclined with respect to the shutter base plate 1.

If the auxiliary base plate 3 is formed in such a shape in advance, the processing cost of the auxiliary base plate 3 naturally increases. However, an excessive force is not applied to the shafts 1q and 1r as compared with the case of the first embodiment, so that a uniform quality mounting state can be obtained. In the first embodiment, in order to prevent an excessive force from being applied to the shafts 1q and 1r, the shafts 1q and 1r must be formed into a special shape or a material that is difficult to process. Therefore, there is almost no difference between the two, but in mass production,
The embodiment is more advantageous.

In each of the above embodiments, the case where the shutter base plate 1 is made of metal has been described.
Does not affect the distance between the imaging surface and the working surface of each blade group, so if there is no other problem, be prepared to be made of synthetic resin, assuming that the plate thickness will be thicker. .
In that case, the operating region at the tip of each blade may be formed thick.

[0035]

As described above, according to the present invention, it is possible to arrange the operating surface of each blade group immediately before the image forming surface of the object image, and to use the conventional blade holding plate. Therefore, it is possible to obtain a focal plane shutter that is advantageous in cost.

[Brief description of the drawings]

FIG. 1 is a plan view of a first embodiment viewed from a subject side, that is, a photographing lens side, and shows a state immediately after an exposure operation is completed.

FIG. 2 is a bottom view of FIG. 1, in which illustration of a blade group is omitted.

FIG. 3 is a right side view of FIG. 1, in which illustration of a blade group is omitted.

FIG. 4 is a plan view of the second embodiment shown in the same manner as FIG. 2;

5 and FIG. 4 for comparison with the two embodiments.
It is a bottom view of the conventional example shown similarly to FIG.

[Explanation of symbols]

1 shutter base plate 1a, 3a opening 1b, 1c, 4a, 10a long hole 1d, 1e, 1f, 3g, 3h hole 1g, 1h, 1i, 1j, 1k, 1m, 1n, 1p, 1
q, 1r axis 2 Intermediate plate 3 Auxiliary base plate 3b, 3c, 3d, 3e, 3f Bent portion 4, 5, 10, 11 Arm 6, 7, 8, 9, 12, 13, 14, 15 Between blades 16, 17 Seat 18 Screw 19, 20 Blade holding plate

Claims (3)

[Claims] 1. A front blade group and a rear blade group arranged between a shutter base plate and an auxiliary base plate each have one end of a plurality of elongated blades in the length direction of a plurality of arms. Pivoting in turn, the arms of both blade groups are both pivotally connected to one of the two ground planes at the same lateral area of the exposure aperture, the two ground planes being at least auxiliary. A focal plane for a camera, wherein the base plates are made of metal, and the base plates are attached to each other such that the distance between the base plates is smaller in the opposite side region than in the side region. Shutter. 2. A peripheral position of the two ground plates,
In addition, at least one of the two ground plates is provided with a gap regulating means near a position where the side of the exposure opening on the side where the arms of the two blade groups are pivotally attached is extended. A focal plane shutter for a camera according to claim 1. 3. The auxiliary base plate has at least two bent portions in order to make the space between the auxiliary base plate and the shutter base plate narrower in the side region on the opposite side than the region where the arms of both blade groups operate. The focal plane shutter for a camera according to claim 1, wherein the shutter is formed.