JPS6240686B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a blade for a lens shutter in a camera, and particularly to an improvement in the shape of a fitting part forming a driving part thereof.

The shutter in a lens shutter camera is opened and closed by rotating multiple blades using rotational force from a drive source to open and close the lens opening. A method is used in which a drive shaft rotated by a drive source is fitted into an elongated hole to move each blade in the opening or closing direction.

In conventional lens shutters, by setting a large ratio between the amount of movement of the blade drive shaft and the aperture diameter of the blade, rattling during opening and closing of the blades is prevented from affecting the aperture diameter as much as possible.

However, if the ratio is set too large, the arrangement of the drive system will be restricted, and if this ratio is set too small, the rattling of the blades will greatly affect the change in the aperture diameter. This tends to cause shutter opening unevenness (cutting unevenness), and some kind of countermeasure is required to reduce the ratio.

The present invention has been made in view of the above points, and it is possible to improve the shape of the fitting portion between the shutter blade and the drive shaft, even when the ratio is small, where the fitting error of the blade adversely affects the accuracy of the shutter. By simply changing the shape of the fitting part of the blade without adding any other parts, it is possible to minimize the fitting error between the blade and the drive shaft, and this allows for a stable shutter opening at all times. It was made so that it could be obtained.

The present invention will be explained in detail below with reference to the drawings. FIG. 1 is an exploded perspective view showing an embodiment of a lens shutter blade according to the present invention. In the figure, 1,
1' is a shutter blade, and in this embodiment, a two-blade type lens shutter is shown. Reference numeral 2 denotes an opening lever that serves as a drive source for the shutter blades, and rotates around a rotation shaft (not shown). Reference numeral 3 denotes a drive shaft installed on the opening lever 2, which engages with elongated fitting holes 4, 4' as cam grooves provided in the shutter blades 1, 1' to open and close the blades. .
Reference numerals 5 and 5' denote holes that fit into the rotational center shafts (not shown) of the blades 1 and 1', into which the center shafts implanted on the shutter blade substrate (not shown) are rotatably fitted. .

FIG. 2 is an enlarged perspective view of the fitting portion of the shutter blade shown in FIG. 1. FIG. In the configurations shown in FIGS. 1 and 2, when the opening lever 2 starts operating, the drive shaft 3
and the elongated holes 4, 4' of the blades are fitted, and the blades 1, 1' begin to rotate around the rotation center shaft fitted in the holes 5, 5', and the shutter blades 1, 1' are mutually connected. The shutter can be opened by moving in the opposite direction. At this time, if the long holes 4 and 4' of the blades are configured so that the gap a is slightly narrower than the diameter of the drive pin 3, as shown in FIG. The shaft 3 is pressed, which causes the blade elongated hole 4,
There is no looseness between 4' and the drive shaft 3. Therefore, the blades 1 and 1' rotate completely in unison with the movement of the drive shaft 3, and uneven openings (uneven cutting) caused by fitting errors are avoided.
can be minimized.

Fig. 3 is a curve diagram comparing the variation (cutting unevenness) in the image plane light amount value in a lens shutter using the shutter blade of the present invention and a conventional shutter blade, and the horizontal axis shows the brightness (EV). There is.
The figure shows the case of a half-open lens shutter (shutter that also serves as an aperture blade), and curve A shows the blade of the present invention,
Curve B is for a blade with a conventional fitting. As shown in the figure, it is recognized that the shutter having the blades of the present invention has less uneven cutting than the conventional shutter, especially at high brightness.

The shutter blade of the present invention can be applied to any material that is rich in elasticity, and can be designed in an optimal state by appropriately selecting the dimensional difference between the dimension a in Fig. 2 and the drive shaft diameter depending on the material. You can.

4 and 5 are enlarged perspective views of the fitting part showing other embodiments of the present invention. In FIG. 3, a second elongated hole 6 is provided near the elongated hole 4 to be fitted, and these two
In this method, the elongated hole 4 is made slightly narrower than the diameter of the drive shaft, and the elasticity of the part b allows for a light pressure contact. In the embodiment shown in FIG. 5, a notch 7 is provided in the fitting elongated hole 4 to obtain the same effect. Note that the fitting portion of the present invention does not have to be applied to all of the plurality of blades used in the shutter, and can be effective even if applied to only one specific blade.

As described above, by using the fitting part between the blade and the drive shaft according to the present invention, even if the long hole part as the cam groove of the blade or the diameter of the drive shaft is manufactured with somewhat lower precision, the blade will always be driven. Since it is possible to prevent fitting errors between the shaft and the shaft, the unevenness of the shutter opening is reduced by about half compared to conventional devices, and the positional relationship between the rotation center of the blade and the drive unit can be set relatively freely. It is possible to obtain sufficient effects without adding any other special components.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view showing one embodiment of a lens shutter blade according to the present invention, FIG. 2 is an enlarged perspective view of a fitting portion of the shutter blade shown in FIG. 4 and 5 are enlarged perspective views of the shutter blade fitting portion showing other embodiments of the present invention. be. 1, 1'...Shutter blade, 2...Blade drive opening lever, 3...Drive shaft, 4,4'...Blade fitting long hole, 5,5'...Blade rotation shaft fitting hole, 6...Second long hole Hole, 7...Mating long hole notch.

Claims (1)

[Scope of Claims] 1. Movement of a drive shaft of a drive member that is rotatably supported around a rotation center axis on a substrate and has an elongated cam groove, and is inserted into the cam groove. In a lens shutter blade of a camera that rotates to open and close a lens opening based on the cam groove, a fixed cam surface is formed on one inner surface of the cam groove, and a deformable part that is elastically deformed is formed on the other inner surface of the cam groove. By setting the width of the cam groove to be slightly narrower than the outer diameter of the drive shaft, the drive shaft is elastically pressed by the deformed portion during the movement, and is always in sliding contact with the fixed cam surface. Features a lens shutter blade.