JPH0334733Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a blade of a light receiving section of a camera.

[Prior Art] Conventionally, the light-receiving blade used in the light-receiving part of a camera has been designed to form an aperture (aperture) that exposes the light-receiving element in one blade so as to obtain a desired change in exposure amount. It was equipped with windows having shapes ranging from small area portions to large area portions.

Then, in the front of the light receiving element (light receiving section),
The window of the light receiving blade is moved from the small area part to the large area part, and the size of the hole (aperture) formed by the overlap of the window of this blade and the light receiving window which is the window of the light receiving part is changed. It is intended to do so.

In conventional light-receiving blades, when the hole is extremely small, a groove-shaped notch is formed in a part of the window in order to reduce the amount of change in the area of the hole compared to the amount of operation of the light-receiving blade. The cut portion moved forward and backward at the peripheral edge of the light receiving window.

Therefore, when the window of the blade formed in this way overlaps the light receiving window of the light receiving element, when the tip of the groove-shaped notch first appears in the light receiving window, an extremely small hole (opening) is formed, and the blade further advances. Then, the notch gradually moves in the direction of becoming larger, and when the end of the notch finally retreats outside the light-receiving window, there is a light-receiving blade divided into two parts by the window inside the light-receiving window. appear.

The groove-shaped notch that appears in the light-receiving window is created by covering two parts of the light-receiving window (upper and lower in the drawing) with the light-receiving blade as described above, and gradually moving the covered parts to both sides as the blade moves. Expand the size of your opening by pushing it away (narrowing it).

In other words, with respect to the light receiving window, the light receiving blade moves the window from the narrow part to the wide part of the groove-shaped notch according to its operation, so that the width of the window is It is possible to reduce the amount of change in the area of the hole formed within the light receiving window.

For this reason, compared to the well-known light-receiving blade having a window without a notch, in the light-receiving blade having a window with such a notch, the amount of change in the area of the hole relative to the amount of blade operation is controlled at a predetermined ratio. This was an extremely effective configuration.

A conventional light receiving blade will be explained with reference to FIG.

Reference numeral 1 denotes a light-receiving window, which approximately corresponds to the light-receiving surface of a light-receiving element (not shown).

2 is a light-receiving blade, which is provided with a window 2a consisting of a groove-shaped notch 2a ₁ and a large-area forming edge 2a ₂ ;
It can be linked with the opening/closing movement of a shutter blade (not shown).

A guide 3 provides direction guidance when the light receiving blade 2 is operated.

In the state before photographing, the light receiving blade 2 completely covers the light receiving window 1.

When shooting begins, when the light receiving blade 2 is operated in the direction of arrow A in conjunction with the opening/closing operation of a program shutter (not shown) that is linked to the light receiving unit, the notch _2a1 of the light receiving blade 2 will be aligned as shown in FIG. As shown, it overlaps the light-receiving window 1, forming an opening (opening) through which light can pass, and providing exposure of a predetermined exposure area S to the light-receiving window.

However, the value of the exposed area S must be extremely accurate because it directly affects the amount of exposure to the film.

For this reason, high precision is required in the shape and dimensions of the groove-shaped notch _2a1 provided in the light-receiving blade 2.

[Problem] The window 2a of the light-receiving blade as described above is usually formed by press punching, but when high accuracy is required in the processing dimensions, the shape is minute enough to correspond to the notch. Not only is it difficult to manufacture a press die, but it also has disadvantages such as poor durability and the need to make a large number of them within a certain period of time, resulting in an increase in costs.

However, the size (diameter) of the light-receiving window is usually much smaller than that of a photographic lens, and its diameter is approximately several mm at most.

For example, if the diameter of the light-receiving window is about 2.2 mm, the width of the groove-shaped notch at its narrowest tip will be about 0.2 mm, and this number is suitable for press punching. The dimensions are extremely small.

Since the light-receiving blade is made of a thin plate-like material, the window is usually processed by press processing, which is suitable for mass production. Not only is it extremely difficult to process the press mold, but the durability of the mold is also extremely poor, requiring frequent replacement of the mold. There were disadvantages such as the fact that machining of the groove-like cut portion was extremely difficult.

[Purpose of the invention] In view of the above-mentioned shortcomings of the conventional technology, the purpose of the invention is to reduce the amount of light received compared to the amount of movement of the light receiving blade without forming a narrow groove-like cut that is difficult to process on the receiving blade. To provide a light-receiving blade in which the amount of change is small when the area of the hole formed in the window is small.

[Structure of the invention] The purpose of the invention is to provide a thin plate-like material, which is arranged in front of the light receiving element, and which is arranged between the closed position and the open position with respect to the light receiving window of the light receiving element facing the incident optical path. is movable, and at least one of the edges forming the outer contour shape is a hole-forming edge that forms a light-receiving hole together with the edge of the light-receiving window, and the hole-forming edge is capable of moving itself. This is achieved by being formed in a shape that is inclined with respect to the direction.

[Example] Hereinafter, an example of the present invention will be described with reference to FIG.

Reference numeral 1 denotes a light-receiving window, which approximately corresponds to the light-receiving surface of the light-receiving element, and has an approximately circular outer shape in this embodiment.

Reference numeral 12 denotes a light-receiving blade, which has an outer edge 12a that forms an outer contour shape, and an opening that forms an opening in the light-receiving window 1 along with the edge of the light-receiving window 1. It has an edge _12a1 and can move in conjunction with the operation of a shutter blade (not shown).

In the state before photographing, the light-receiving blade 12 is located slightly to the right of the illustrated position, and is in a position that completely covers the light-receiving window 1 (closed position).

When the shutter release is performed, the light receiving blade 12
starts moving in the direction of arrow A along the guide 3 in conjunction with a shutter blade (not shown).

When the blade 12 operates, the annular forming edge 12a ₁ gradually overlaps with the light receiving window ₁ as shown in FIG. An opening (aperture) having an exposure area S is formed.

The exposure area S is initially extremely small, but as the shutter blade moves, the light receiving blade 12
As the blade moves further to the left, the width of the blade that covers the light receiving window 1 becomes gradually narrower, and the part that covers the light receiving part becomes smaller accordingly, while the hole spreads and the exposed area S gradually becomes larger.

Eventually, the light receiving window becomes circular and reaches its maximum aperture.

It goes without saying that if a predetermined amount of exposure is obtained before the maximum aperture is reached, the shutter blade may return to the closed position before this, similar to the shutter blade.

In the present invention, the shape of the annular forming edge _12a1 may be formed into a straight line or a curved line as required, and the operation of the light receiving blade 12 may be controlled by means other than being regulated by the guide 3, for example, by its own control. It goes without saying that the present invention can also be achieved by a rocking motion with one point as a fulcrum.

Further, in this embodiment, the light receiving section of the program shutter of the light receiving section interlocking type is analog controlled, but the present invention is not limited to this.

For example, the present invention can be applied to a shutter that performs aperture-priority exposure control, or a setting means for film sensitivity (ASA) conversion.

[Effects of the invention] According to the invention, a part of the outer edge 12a forming the outline shape of the light-receiving blade 12 made of a piece of thin plate-like material is formed to be used as the annular forming edge _12a1 . Therefore, the operating space of the light-receiving blade 12 is sufficiently shielded from external light, and therefore there is no risk of light leaking from the operating space to the light-receiving window 1, which has a gap greater than the thickness of the light-receiving blade 12. When used in shutters of This has extremely high practical effects, as it simplifies the process and facilitates punching.

According to the present invention, when a small-area hole is formed in the light-receiving window and the change in the area is made small compared to the operating amount of the light-receiving blade, a part of the periphery of the light-receiving window is used as one side, and the light-receiving blade is An annular shape is formed by forming an annular shape cut into a groove shape with the annular forming edge forming a part of the outer edge forming the external contour shape as the other side, and operating only one side of the annular forming edge. Since the area of the light-receiving blade is changed, it is possible to control the angle even in a small area without forming a groove-like notch in the light-receiving blade itself.

According to the present invention, since there is no need to form a groove-like notch in the light-receiving blade, it is extremely easy to process a mold for press molding, and the durability of the mold is improved. The advantage is that the processing of the light-receiving blades can be made extremely easy.

[Brief explanation of the drawing]

Figure 1 is a plan view of the main parts of a conventional example;
The figure is a front view of main parts showing an embodiment of the present invention. 1... Light receiving window, 2... Light receiving blade, 2a... Window,
2a ₁ ... cut portion, 2a ₂ ... large area forming edge, 3
... Guide, 12 ... Light receiving blade, 12a ... Outer edge, 12a ₁ ... Ana formation edge, S ... Exposure area.

Claims (1)

[Claims for Utility Model Registration] Made of a thin plate-like material, disposed in front of the light receiving element, and movable between a closed position and an open position with respect to the light receiving window of the light receiving element facing the incident optical path. At least a part of the edge forming the outer contour shape is a hole-forming edge that forms a light-receiving hole together with the edge of the light-receiving window, and the hole-forming edge is oriented with respect to its own movement direction. A light-receiving blade characterized in that it is formed in a shape that is inclined.