JPH063729A - Production of light shielding blade for vertical traveling focal-plane shutter - Google Patents

Abstract

PURPOSE:To decrease the unevenness of exposure at the time of slit exposure by a vertical traveling focal-plane shutter. CONSTITUTION:In the case of producing a light shielding blade for a vertical traveling focal-plane shutter by blanking a plate-like material in the shape of a light shielding blade, an end face is ground after blanking. It is desirable to grind the end face so that its ruggedness may be <=30mum. It is sufficient to grind only the slit formed surfaces of first blades 11 and 21. It is desirable to use resin (FRP) reinforced by carbon fiber or other fiber as the material. The effect is remarkable in the case that whitening painting is performed in order to make the reflectance of the light shielding blade high in a photometric system (especially, multipattern photometric system) performing the photometry of reflected light from the surface of a shutter curtain, in the case that the blade is made of FRP, and in the case of very high speed shutter whose speed exceeds 1/8000 second.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a light-shielding blade for a vertically running focal plane shutter (hereinafter, "longitudinal running" is omitted and simply referred to as "focal plane shutter").

[0002]

2. Description of the Related Art A vertically running focal plane shutter is
A shutter substrate having an exposure window, a shutter curtain composed of a plurality of divided blades (light-shielding blades), a main arm and a slave arm rotatably connected to the shutter substrate and each of the divided blades to form a parallel link. A drive pin that engages with a drive pin hole formed in the main arm changes each of the split blades from a state of being folded outside the exposure window to a state of being expanded to cover the exposure window, or And a drive mechanism for moving the unfolded state to the folded state. The shutter curtain is usually composed of a front curtain and a rear curtain, and each curtain is composed of 4 to 5 light-shielding blades (split blades).

By the way, in the first TTL photometry, a predetermined exposure amount level is obtained by averaging a predetermined area of the film surface exposed by the light receiving element at the time of dimming during flash photography.
It was to control the light emission amount of the strobe. for that reason,
Depending on the situation of the subject, there were large variations in the quality of the photographs. For example, in a camera in which the light-sensitive element covers the entire surface of the film, when the main subject is a small flash on the screen and the back is wide, the area where the flash light does not reflect is large. However, the controlled light emission amount is overexposed for the main subject. On the other hand, when a high-reflectance object such as a gold folding screen stands right behind the main subject, on the contrary, the controlled light emission amount is underexposed.

In order to solve this problem, as a means for eliminating variations in exposure of the main subject due to differences in conditions such as the position and reflectance of the subject during flash photography, a TTL automatic light adjustment control device (Japanese Patent Laid-Open No. 3-68928). No.) is proposed. This device divides the object field into one part in the central part and a plurality of areas in the peripheral part at a position looking at the film surface, arranges a plurality of photoelectric conversion means capable of photometry, and immediately before opening the focal plane shutter. Pre-flash the strobe,
The light reflected by the subject image due to the light on the surface of the shutter curtain is captured by a plurality of photoelectric conversion means, and the output is individually integrated and detected as the field reflectance of each area due to the stroboscopic light emission. Then, the degree of weighting for each divided area that provides the optimum exposure for the main subject is determined by comprehensively calculating the information on the detected field reflectance of each area. This photometric method is called a multi-pattern photometric method.

After that, immediately after the shutter is opened, the strobe is made to emit main light, the light reflected on the film surface is captured by the same plurality of photoelectric conversion means as described above, and the output thereof is weighted in advance. Then, the light emission of the strobe is stopped at the timing determined by adding and integrating and then comparing it with a predetermined value, and the dimming of the main light emission is completed.

In this case, in the focal plane shutter, the reflectance of the shutter curtain surface needs to be almost the same as that of the film surface. Therefore, in order to increase the reflectance of the shutter curtain surface on the lens side, the light shielding blade is whitened ( It was painted). In recent years, there is a demand for higher camera shutter speeds and flash sync speeds for reasons such as improved film sensitivity and the desire for new video expressions. Actually, high shutter speeds up to 1/8000 second and sync speeds 1 A camera that realizes / 250 seconds is provided.

In such a focal plane shutter, at a high shutter speed exceeding the strobe synchronization speed, the front curtain and the rear curtain start to move with the timing shifted,
This is achieved by performing slit exposure in which the amount of the gap (slit) with the first blade of the front curtain that moves simultaneously is fixed at a certain interval or changed according to the speed. Currently, the highest shutter speed that has been put to practical use is 1/8000, and the light-shielding blades used for this are two types, aluminum and FRP. FRP is disclosed in JP-A-59
As disclosed in Japanese Laid-Open Patent Publication No. -61827, continuous fibers of carbon fibers are used as fibers, and epoxy resin is used as a matrix resin. In FRP, a plurality of prepreg sheets, which are precursors, are laminated (laminated so that their fiber directions are orthogonal or substantially orthogonal to each other), and the entire laminate is heated and cured while being pressed. Manufactured by. The manufactured FRP material has almost the same thickness as the light-shielding blade (generally 70 to 120 μm).
For example, it is a plate with a rectangular shape having a length of 80 mm and a width of 400 mm.
The prepreg sheet is made by aligning continuous fibers of carbon fibers in one direction and arranging them thinly on a plate material, impregnating this with "uncured epoxy resin liquid" which is a precursor of matrix resin, and making this resin liquid into a B stage state. It was done. The B stage state is a state in which it is solidified and has no apparent fluidity, but can be finally cured by heating. FR
In order to manufacture P, it is necessary to prepare at least one prepreg sheet for each of the front and back surfaces for the surface material layer and at least one prepreg sheet for the intermediate layer.

To manufacture the light-shielding blade, use FRP,
A metal, for example, a lightweight metal such as aluminum or titanium, is prepared by preparing a plate-shaped material and punching it into a light-shielding blade shape. In the case of FRP, punching is performed so that the direction of continuous fibers in the surface material layer coincides with the longitudinal direction of the blade. Next, the cut light-shielding blades are painted black (commonly known as dry lube) on both the front and back surfaces and the cut surface (end surface). In this way, 20 to 40 blades can be obtained from one material.

Recently, photographers have been demanding a shutter having an ultrahigh shutter speed of 1/2000 or more, which exceeds 1/8000, in search of a new image expression.

[0010]

However, it has been found that the light-shielding blade manufactured by the conventional method has a problem that uneven exposure is likely to occur. And this problem is FR
In the case of P, whitening coating on the front surface, black coating on the back surface, ultra-high speed shutter of 1/2000 or more, and slit spacing at the start of exposure of 0.45 mm or less are particularly noticeable. It was

[0011]

Therefore, in the first aspect of the present invention, there is provided a "light-shielding blade for a vertically running focal plane shutter, characterized in that a plate-shaped material is punched into a light-shielding blade shape and then an end face is polished. A manufacturing method (claim 1) "is provided. In addition, the present invention is, secondly, that the unevenness of the end face is 30 μm.
The manufacturing method according to claim 1 (claim 2) characterized by the following is provided.

Thirdly, the present invention provides "a manufacturing method according to claim 1 or 2 (claim 3), characterized in that the light-shielding blade is the first blade.

[0013]

The plate-shaped material includes FRP, lightweight metal, plastic, and lightweight ceramic. FRP is an abbreviation for the English expression of fiber reinforced resin, and consists of fibers and matrix resin. As the fiber, a continuous fiber such as a carbon fiber, a continuous fiber such as an aromatic polyamide fiber, or a continuous fiber such as an ultrahigh molecular weight polyethylene can be used. In particular, other than carbon fiber can be used for the intermediate layer. Further, short fibers may be used instead of continuous fibers for the intermediate layer in the three-layer structure (three layers of the surface material layer on the front side, the intermediate layer and the surface material layer on the back side).

The matrix resin includes (1) celluloid, cellulose acetate, cellulose propionate, cellulose butyrate, 6-nylon, 6,6-nylon, ABS, AS resin, high density polyethylene, polypropylene, polyacetal, polycarbonate, Polyethylene terephthalate, polybutylene terephthalate,
Thermoplastic resins such as polyetherketone, polyetheretherketone, polysulfone, polyethersulfone, polyetherimide, polyarylate, polyamide elastomer, ionomer, liquid crystal polymer, polyimide, polyamideimide, fluororesin, PPS, modified polyphenylene oxide, etc., Alternatively, (2) a thermosetting resin such as epoxy resin, unsaturated polyester, polyurethane or polyimide can be used.

When carbon fibers are used, the carbon fibers are black, so that the FRP has a temporary light-shielding property. However, in order to improve the light-shielding property, carbon black may be previously added and dispersed in the resin liquid that is a precursor of the matrix resin when the prepreg sheet is manufactured. Alternatively, a resin solution in which carbon black is mixed at a high concentration is separately prepared, and this may be press-fitted and permeated into an ordinary prepreg sheet by using a roll coater or the like. Carbon black has the effect of improving the sliding of the blades. Even if the blade rubs, it will wear less if it is slippery.

Carbon black has an average particle size of 0.07 μm.
It is particularly preferably 0.01 μm or less. The blending amount of carbon black is 3 to the resin liquid (solid content 100 parts by weight).
15% by weight is preferred. If it is 15% by weight or more, the arrangement of the fibers becomes too bad and the flatness is adversely affected. In addition, since the fluidity of the resin liquid becomes too poor, voids may be formed inside or delamination may occur. The amount of resin in the prepreg sheet is
30 to 50% by weight, especially 38 to 48% are suitable. When the amount of resin is small, voids and fine cracks are visible on the appearance, and the coatability is deteriorated. Furthermore, since the surface of the material has irregularities, the wear resistance and lubricity of the blades are inferior, and further the aesthetic appearance is deteriorated. In addition, if the amount of resin is small, a striped pattern may appear during resin flow, which also deteriorates the appearance.

The fiber basis weight of the prepreg sheet (how many g of fiber is contained per 1 m ² ) is 10 g / m ^{2 to} 60 g / m.
^{Is 2} . The thickness of one layer of prepreg sheet is 15-70μ
m. The prepreg sheets need not all have the same plate thickness. If they are used so as to be plane-symmetric with respect to the neutral plane in the thickness direction, it is possible to combine various plate thicknesses and various basis weights. If the plate thickness is within the specified value, increase the bending rigidity of the whole by changing the plate thickness and weight of the intermediate layer to the surface material layer (in this case,
It is advantageous to make it thicker or more than just the layers).

In the prepreg sheet, the surface layer and the intermediate layer are so arranged that the directions of the fibers are orthogonal or substantially orthogonal to each other.
In addition, at least three or more sheets, for example, three, four, or five sheets are superposed so as to be plane-symmetric in the thickness direction from the center plane, and heat press molding is performed on them to obtain a plate material. As a result, the uncured thermosetting resin liquid is crosslinked and hardened. In this way, a plate-shaped material (thickness 70 to 120 μm) made of FRP is obtained.

The material is then punched into a predetermined light-shielding blade shape (see FIGS. 1 and 2). 20-40 from one piece of material
About one blade is punched out. In the case of FRP, punching is performed so that the direction of the continuous fibers in the surface material layer coincides with the longitudinal direction of the blade. At the time of cutting, it is common to simultaneously make a hole for passing the connecting pin. The cut light-shielding blade has its end face polished according to the present invention. Polishing includes lapping, polishing, and smoothing according to the roughness, and fixed abrasive grains (emery paper,
Water-resistant abrasive paper) and loose abrasive grains. The polishing solves the problem of uneven exposure during slit exposure. For example, each blade is # 80 or more (preferably #
It may be ground with fine water-resistant abrasive paper (400 or more) (emery paper), or may be stacked with several blades and set on a jig, and then polished with a polishing machine or lapping machine. Also, DL on the blade
When color coating (black coating for the main purpose of surface lubricity and antireflection) is applied, polishing can be performed before or after coating, but it is preferable to perform polishing after coating. The reason is that the final unevenness can be smoothed. As a polishing amount, it is preferable to scrape a part or all of the coating film portion in order to avoid a change in blade size. Therefore, since it is difficult to stabilize the quality when a coarse abrasive or abrasive paper is used, it is desirable to use a finer abrasive or abrasive paper.

Although the exposure unevenness varies depending on the slit spacing, for example, the slit spacing at the start of exposure is 0.8 to 0.9 mm.
In case of 40 μmφ or 40 μm square, if there are protrusions or recesses, exposure unevenness will appear clearly, so polishing should be 30 μm.
Hereafter, it is necessary to finish the unevenness of preferably 20 to 10 μm or less. When the slit spacing at the start of exposure is 0.45 mm or less, unevenness in exposure clearly appears when there are protrusions or recesses exceeding 20 μmφ or 20 μm square, so it is necessary to eliminate such protrusions or recesses.

Film thickness of black or white coating (after drying and curing)
Is generally 0.1 to 10 μm, preferably 3 to 6 μm. If thickened, the blades will warp. Hereinafter, the present invention will be described in more detail with reference to the examples with reference to the drawings.
The present invention is not limited to this.

[0022]

Example 1 (1) Prepreg Sheet a: Carbon fiber (average diameter 6 to 7 μm) continuous fiber in which the matrix resin precursor is “uncured epoxy resin liquid” and the fibers are aligned in one direction. A prepreg sheet a was prepared. It has a resin content of about 40 to 45% by weight and a fiber basis weight of 20 g / m ² . The thickness of the sheet is 20-25 μm.

(2) Prepreg sheet b: Same as prepreg sheet a except that 10% by weight of carbon black is mixed in the resin liquid. (3) 90 μm thick FRP material: 2 sheets a and 2 sheets b are prepared so that the fiber direction is 0 ° surface layer / 90 ° intermediate layer / 90 ° intermediate layer / 0 ° surface layer In addition, the above four sheets are laminated in plane symmetry so that the types of sheets are surface material layer a / intermediate layer b / intermediate layer b / surface material layer a, and 5 to 15 kg / cm ² at a temperature of 130 ° C. Then, the material was cured for 1 to 2 hours, and then slowly cooled under pressure to obtain a FRP material. This material is a rectangular plate measuring 80 mm long and 400 mm wide.

(4) Punching of the light-shielding blades: No. 1 to 4 blades (see FIG. 1) for the leading blade and No. 1 for the trailing blade from the plate-shaped material made of FRP having a thickness of 90 μm manufactured in the preceding paragraph. Feather-fourth
The blades (see FIG. 2) were punched out by pressing. At this time, the punching was performed so that the longitudinal direction of the blade and the longitudinal direction of the carbon fiber of the surface material layer were parallel to each other.

(5) Coating: As for the punched-out blades, a plurality of blades of the same kind were prepared, and the surface was whitened with a thickness of 3 to 6 μm. The whitening coating was also applied to the end faces. Since the overlapping of the blades is 3 to 5 mm or less, light leakage between curtains is likely to occur, and in order to prevent this, a black coating with a thickness of 3 to 6 μm was applied to the back surface. The black coating was also applied to the end faces. After painting, the warped blade was discarded.
The non-defective rate is 20 to 50%.

(6) Polishing: Only non-defective blades were selected, and the end faces thereof were lightly polished with # 150 or # 400, # 600, and # 1200 emery paper (water-resistant abrasive paper). As a result, protrusions or recesses exceeding 20 μmφ or 20 μm square on the slit forming surface were eliminated. It should be noted that several tens of sheets may be polished at once using a dedicated jig. It is also possible to use a polishing machine, a lapping machine, or the like, and carry out polishing at a constant pressure for several seconds to several tens of seconds. Polishing may be carried out not only on the No. 1 blade having the largest momentum, but also on the slit forming surface instead of the entire end surface.

[0027]

Example 2 Using the light-shielding blade manufactured in Example 1, a focal plane shutter (slit interval at the start of exposure = 0.45 mm) shown in FIGS. 3 to 4 was assembled. 3-5
[Fig. 4] is a schematic front view of the shutter. 3 shows a state in which the exposure window is closed by the front curtain, FIG. 4 shows a state in which the front curtain is folded down to open the rear curtain and the exposure window is closed, and FIG. 5 shows a state during slit exposure.

The shutter of the second embodiment is subjected to a live-action test (120
When subjected to 1/00), there was almost no occurrence of exposure unevenness. In the shutter of the second embodiment, the blades of the first to fourth blades are the blades of the first embodiment (that is, the polished blades).
However, the blade of Example 1 may be used only for the first blade.

[0029]

As described above, according to the present invention, uneven exposure is unlikely to occur. The effect of the present invention is 12 when the whitening coating is applied to the front surface and the black coating is applied to the back surface when the product is made of FRP.
In the case of an ultrahigh-speed shutter of 1/000 or more, it is particularly advantageous when the slit interval at the start of exposure is 0.45 mm or less.

Even in mass production, the defects of the light-shielding blades due to the uneven exposure could not be discriminated until the shutter was assembled and the actual shooting test was performed. If the blade is defective, the blade is replaced with another blade, which requires a complicated process of reconnecting the arm. However, according to the invention,
Since this defect is reduced, the manufacturing cost of the shutter can be reduced.

[Brief description of drawings]

FIG. 1 is a plan view of a light-shielding blade (for a front film) that has just been punched out from a material in Example 1 of the present invention.

FIG. 2 is a plan view of the light-shielding blade (for the rear film) that has just been punched out of the material in the first embodiment of the present invention.

FIG. 3 is a schematic front view of the focal plane shutter according to the second embodiment of the present invention, showing a state in which the front curtain is expanded to cover the exposure window.

FIG. 4 is a schematic front view of the focal plane shutter according to the second embodiment of the present invention, in which the rear curtain is expanded to cover the exposure window.

FIG. 5 is a schematic front view showing a state where slit exposure is performed by the front curtain and the rear curtain.

[Explanation of symbols]

10 Front curtain 11-14, 21-24 Light-shielding blades 15, 25 Secondary arm 16, 26 Main arm 17, 18, 27, 28 Caulking pin 19, 29 Drive mechanism 20 Rear curtain 31, 32 Drive shaft 40, 41 Brake piece 50- 54 Shock Absorbing Member 61 Slit Side End Surface X _{1 to} X ₄ Axis

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[Procedure amendment]

[Submission date] July 8, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0019

[Correction method] Change

[Correction content]

The material is then punched into a predetermined light-shielding blade shape (see FIGS. 1 and 2). 20-40 from one piece of material
About one blade is punched out. In the case of FRP, punching is performed so that the direction of the continuous fibers in the surface material layer coincides with the longitudinal direction of the blade. At the time of cutting, it is common to simultaneously make a hole for passing the connecting pin. The cut light-shielding blade has its end face polished according to the present invention. Polishing includes lapping, polishing, and smoothing according to the roughness, and fixed abrasive grains (emery paper,
Water-resistant abrasive paper) and loose abrasive grains. The polishing solves the problem of uneven exposure during slit exposure. For example, each blade is # 80 or more (preferably #
It may be ground with fine water-resistant abrasive paper (400 or more) (emery paper), or may be stacked with several blades and set on a jig, and then polished with a polishing machine or lapping machine. Also, DL on the blade
When color coating (black coating for the main purpose of surface lubricity and antireflection) is applied, polishing can be performed before or after coating, but it is preferable to perform polishing after coating. The reason is that the final unevenness can be smoothed. As a polishing amount, it is preferable to grind (polish) a part or all of the coating film portion in order to avoid a change in blade size. Study all
When polished, the base coating (white coating) or the background is exposed on the end surface.
Put out. Reflection of exposed undercoat (white paint) or background
If the rate is high, uneven exposure may occur. This
To eliminate this, it is preferable to apply a smooth black paint.
Good Of course, this black paint film has irregularities of 30μ.
It must have a smooth surface of m or less. Paint film part
It is desirable to use a finer abrasive or abrasive paper because it is difficult to stabilize the quality when using a coarse abrasive or abrasive paper when polishing.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] Explanation of code

[Correction method] Change

[Correction content]

[Explanation of Codes] 10 Front curtain 11-14, 21-24 Light-shielding blade 15, 25 Secondary arm 16, 26 Main arm 17, 18, 27, 28 Caulking pin 19, 29 Drive mechanism 20 Rear curtain 31, 32 Drive shaft 40, 41 brake shoe 61 a slit-side end face X ₁ to X ₄ axis

Claims (3)

[Claims] 1. A method of manufacturing a light-shielding blade for a vertically-running focal plane shutter, which comprises punching a plate-shaped material into a light-shielding blade shape and polishing an end face. 2. The manufacturing method according to claim 1, wherein the unevenness of the end face is set to 30 μm or less. 3. The manufacturing method according to claim 1, wherein the light-shielding blade is the first blade.