JPS627533B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing exposure control blades such as aperture blades of an aperture device or shutter blades of a shutter device, which are disposed in the barrel of a photographic lens or in the optical path of a photographic device.

Conventionally, lens barrels have used aperture blades or shutter blades made of thin metal plates. Thin metal plates with a thickness of around 0.05 mm are generally used, and most of them have anti-reflection treatment applied to their surfaces. In recent years, the optical performance of lenses has improved significantly, and the deterioration in performance due to reflections from the end faces of aperture blades or shutter blades can no longer be ignored.

However, in terms of mechanical strength, it has been almost impossible to reduce the thickness of the blade. The present invention has been made in view of these points, and aims to propose a method for manufacturing a blade, particularly an efficient manufacturing method, which can eliminate reflections at the blade end face and obtain good optical performance. A detailed explanation will be given below with reference to the drawings. Figure 1 is a front view of a conventional blade and A
-A' line sectional view, Fig. 2 is a front view and B-B' line sectional view of the blade according to the manufacturing method of the present invention, and Fig. 3 shows an example when processed by the progressive method. FIG. 2 is a front view of the hoop material at each step, b is an enlarged cross-sectional view of the blade edge portion at each step, and c is a front view of the die at each step. FIG. 4 is an embodiment of another edge manufacturing method, and is a schematic side view of a press die.

In the figure, 1 is a conventional blade, 1a is an edge portion of a conventional blade, 3 is a blade according to the present invention, 3a is an edge portion of a blade according to the present invention, 5 is a hoop material, 6 is a pilot hole, 7 is a die hole, and 8 is a die hole. Die set, 9 is packing plate, 10 is punching plate, 11
is a punch, 12 is a die, 13 is a stopper, 14
is a spring, and 15 is a blade. FIG. 1 shows a conventionally used blade, in which a thin metal plate is processed by a method such as press working or etching. Looking at the cross section of the blade (A-A' in FIG. 1), since the edge portion is punched out with almost the same thickness, a flat portion 1a is formed in the thickness direction. On the other hand, in FIG. 2, the edge portion is formed in a tapered shape 3a, and the portion that actually blocks the light rays has a shape similar to a knife edge. Figure 3a shows the manufacturing order of the blade shown in Figure 2. In the figure, from the left side, the blade is punched, pressed, finished punched, and cut using the pilot hole 6 as a guide. A blade 3 with a knife edge is produced. FIG. 3b is an enlarged sectional view of the edge portion of the blade in FIG. 3a,
FIG. 3c is a diagram showing the shape of the die side of the mold in the processing step, in which a punch is driven into the die hole 7. When the hoop material 5 shown in Fig. 3a is sent from the left side to the die side shown in Fig. 3c, first, in the punching process, parts _a1 to _a4 around the part where the blades will be formed are punched out to form the blades. Part b remains. Next, in the surface pressing process, the end of the curvature surface of part b (the part that will become the opening forming surface of the aperture blade) is pressed, and the curvature of part a 3 of the punching process is processed as shown in the middle drawing of Figure ₃ b. A tapered portion 3a and an extruded end portion 3b are formed on the cut surface of the surface. Then, in the next finish punching step (cutting), the end portion 3b is cut, and finally the portion where the hoop material 5 and the member b are connected is cut, thereby completing the blade 3 shown in FIG. 2. Figure 4 shows an example where the edge is formed using a different method from Figure 3, where the blade is fed into the die set at a fixed angle and punched out, and b is an enlarged view of the edge. . The example in FIG. 4 shows a different example from those in FIGS. A taper is formed on the end surface of the aperture blade of the hoop material 15 using a punch 11 fixed to a punch plate 10 with a hoop material 16 fixed thereto. In addition to these methods, there is also a method of cutting at a certain angle using a cutter, for example. Further, it is also possible to simultaneously apply anti-reflection treatment to the tapered portion during the surface pressing process shown in FIG. 3a. In addition, when synthetic resin material is used for the blades, if the blades are tapered, light will pass through the thinner parts, so after the surface stamping process, the hoop material may be sent continuously to the dyeing process. can.
In addition to the above-mentioned tapered surface, the end surface of the blade 3 has a fifth surface.
Pressing may be performed to form the stepped portion 3c shown in the figure. In this case, if the blade is molded from a resin material and the plate thickness is reduced, it will become translucent, but if the step part 3c is formed by press processing, the density of the step part 3c will become thicker and it will become opaque, which is not convenient. get well. Furthermore, when making the exposure control blades from synthetic resin materials, it is difficult to process them as thin as conventional metal materials due to physical strength, processing accuracy, etc., and it is also necessary to make the walls thicker to some extent. However, by forming a tapered portion or a stepped portion on the end face according to the present invention, even if the end face becomes thick, it is possible to eliminate the adverse effect on optical performance due to reflection by the end face. As described above, if the blade according to the present invention is used, there is no transmission or reflection from the blade edge part, and it is possible to form an ideal diaphragm part or shutter part, and the performance is as good as before at a lower price. We are now able to provide lens barrels.

[Brief explanation of the drawing]

FIG. 1a is a front view of a conventional blade. FIG. 1b is a sectional view taken along the line A-A' in FIG. FIG. 2a is a front view of a blade showing an embodiment of the present invention. Figure 2b is Figure 2B
−B′ direction cross-sectional view. FIG. 3a is a front view of the hoop material used to progressively process the blades using the hoop material. Figure 3b is the third
FIG. 3c is a partial cross-sectional view of the blade at each step in FIG. 3a. FIG. 3c is a front view of the die side of the mold used in FIG. 3a. FIG. 4 is an explanatory diagram of another processing method of the present invention. FIG. 5 is a sectional view of a main part of an embodiment using another processing method.

Claims (1)

[Claims] 1. When punching out the periphery of the part that will become the blades constituting the diaphragm from the base material, a punching process that leaves a part of the blade on the base material, and a punching process that leaves part of the blade in the base material and the edge of the diaphragm opening forming side of the blade formed in the punching process. A process of face pressing so that the wall is thin compared to the material, a finish punching process of cutting the tip extruded by the face pushing process after the face pressing process, and a finish punching process of cutting the tip of the blade into the base material after the finish punching process. A method for manufacturing an exposure control blade, comprising a step of cutting the blade.