JPS6353533B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a blade-type focal plane shutter in which avertures are opened and closed by overlapping blades made of a plurality of opaque thin plates and changing the amount of overlap. be.

The focal plane shutter described above has many advantages such as fast blade operation, high shutter speed, and easy assembly. There was a problem that could easily arise.

In recent years, the sensitivity of films, etc. has improved, and films with several times the sensitivity of conventional films are already on the market, but it is extremely likely that this trend of increasing film sensitivity will continue in the future. Seem.

In blade-type focal plane shutters, as mentioned above, there is a possibility of light leakage from the overlapping part of the blades, and as film sensitivity has improved, this possibility has become inevitable. .

Therefore, many proposals have been made and implemented to prevent light leakage from this overlapped portion, but many of them have extremely complicated structures or operations, and unnecessarily increase costs. Or, the effect of preventing light leakage was small.

In view of the prior art as described above, the present invention has made it possible to reliably prevent photomoles by performing extremely simple additional processing without changing the number of parts or the outline shape of the parts at all. To provide a blade type focal plane shutter.

The present invention will be explained below with reference to illustrated embodiments.

First, an example of a conventional blade-type focal plane shutter will be shown in FIGS. 1 and 2, and its structure and operation, as well as one of the causes of light leakage, will be explained. Fourth
Embodiments of the present invention will be described with reference to the drawings.

Figure 1 shows a conventional blade-type focal plane shutter with two arms 2 and 3.
Five blades 6, 7, 8, 9, 10 were crimped and pivoted on two shafts 11, 12, 13, 14, 15 at one end side, respectively, to form a set of blade assemblies. The object is shown pivotally supported on the base plate 1 by support shafts 4 and 5. Actually, this blade assembly constitutes a shutter with two sets of opening blades for opening the aperture 1a provided in the base plate and closing blades for closing the aperture 1a.
FIG. 1 and the following drawings are shown in only one set, as they are not necessary for explaining the invention and for the sake of conciseness.

The support shafts 4 and 5 shown in FIG. 1 are provided on a straight line F, and the shafts 11, 12, 13, 14, and 15 provided on the arms 2 and 3, respectively, are parallel to this straight line F. Therefore, when the arms 2 and 3 rotate to the left, the blades 6 to 10 simultaneously rise without changing their postures, revealing the aperture 1a. When the arms 2 and 3 return to the right rotation, they return to the state shown in FIG. 1 again.

Here, according to FIG. 2, the above-mentioned arm 2,
The attachment state of the blades 6, 7, 8, 9, and 10 to 3 will be explained.

FIG. 2 is an enlarged cross-sectional view of the arm 3 and the blades 6, 7, 8, 9, and 10 taken at their respective pivot points, as seen from the direction of arrow A in FIG. Cover plate 16 not shown in FIG.
is shown, and a blade assembly is disposed in the space provided between the cover plate 16 and the base plate 1.

As shown in FIG. 2, the arms 3 and 2 are made of a single planar plate, and each of the blades pivotally attached to the arms 3 and 2 is also made of an extremely thin, arrow-stripe plate. Therefore, the blade 6, which is pivotally attached to the arms 3 and 2 in close contact with it, is pivoted by the shaft 11 while maintaining its flat state. However, the blade 7 above it, i.e., pivoted to the arms 3, 2 separated by the blade 6, engages the end of the blade 6 near the axis 12 and is pushed up, so that the blade 7 is tilted. If it is attached in such a state that a gap is created between the blade 6 and the blade 6, the blade 6 is not in close contact with the blade 6. Blades 8 and 9 are also pushed up under similar conditions, but blade 10, which is attached last, has its tip contacting cover blade 16 and being bent.

As mentioned above, in conventional blade-type focal plane shutters, the overlapping parts of the blades do not come into close contact with each other, although the degree of overlap varies depending on the position where the blades are stacked.
Factors that cause gaps were included in the configuration.

With respect to the conventional blade type focal plane shutter as described above, an embodiment of the present invention will be explained below with reference to FIGS. 3 and 4.

1 and 2 will be omitted. Among the five shutter blades, blade 6 is the lowest in the stacking order in the overlapping direction with respect to arms 3 and 2. Only the two blades, the blade closest to arm 3 and 2 and the top blade 10, the blade furthest from arm 3 and 2, face each other between the pivot position and the other end, respectively. In addition, the entire blade is brought into close contact with each other by applying mazes 6a and 10a that extend across the width of the blade.

The mag angle shown in FIG. 4 for each of these mages varies depending on the thickness of the blade material and other conditions, and the shape of each maze shown in FIG. 3 is completely parallel to the straight line F. This is not necessarily the case.

In blade-type focal plane shutters, light leakage from the overlapped portions is not only caused by the stepped portions caused by the thickness of the blades themselves, but is also caused by distortions such as warping of the blades. However, many of these problems can be remedied by the present invention.

According to the present invention, there is no need to increase the number of parts compared to the conventional technology, and there is no need to change the press punching mold, and the process can be carried out immediately by simply performing machining. Therefore, the cost hardly increases and it is extremely economically advantageous.

According to the present invention, light leakage, which is the only drawback of blade-type focal plane shutters, can be reliably eliminated with an extremely simple structure, and this can sufficiently cope with the use of high-sensitivity films. This greatly contributes to quality improvement.

[Brief explanation of the drawing]

Figure 1 is a front view of the main parts of a specific example of a conventional blade-type focal plane shutter;
FIG. 2 is an enlarged cross-sectional view showing the arm 3 and blades 6 to 10 as seen from the direction of arrow A in FIG. 1, and FIG. 3 is a front view of the main parts showing an embodiment of the present invention FIG. 4 is an enlarged cross-sectional view showing the arm 3 and each blade cut away, as seen from the direction of arrow B in FIG. 3 described above. 1... Base plate, 2, 3... Arm, 6
~10...Blade, 6a, 10a...Mage, 1
1 to 15...Shaft, 16...Cover plate.

Claims (1)

[Claims] 1. A plurality of blades made of opaque thin plate material,
A blade type focal plane shutter in which the pivot position by caulking to the arm is sequentially changed on one end side of the shaft, and the aperture is opened and closed by sequentially overlapping a plurality of blades and changing the overlapping amount. Among the plurality of blades described above, the blade closest to the arm in the overlapping direction and the blade furthest from the arm are respectively placed between the pivot position and the other end side, in a direction facing each other, and in the width direction of the blade itself. A blade-type focal plane shutter characterized by a cross-sectional marage process.