JP4131761B2 - Focal plane shutter device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a focal plane shutter device and a light shielding blade used therefor. More specifically, the present invention relates to a focal plane shutter device using a laminated plate having a multilayer structure in which prepreg sheets reinforced with carbon fibers are stacked as a light shielding blade.
[0002]
[Prior art]
FIG. 5 shows an example of the light shielding blade incorporated in the focal plane shutter device. The light shielding blade 10 has a substantially long shape having a certain width dimension and a longitudinal dimension, and a pair of fixing connection holes 20 are formed at one end thereof.
[0003]
FIG. 6 shows an example in which the light shielding blade shown in FIG. 5 is incorporated in the focal plane shutter device. A rectangular opening 12 (shown by a one-dot chain line) is provided at the center of the shutter substrate 11. In the resting state, the four leading blades 10 partially overlap each other to shield the exposure opening 12. Although not shown, the rear blade group is disposed below the front blade group. Unnecessary movement of the tip of each shutter blade is regulated by the blade presser 14. A pair of arms 15 and 16 are pivotally supported at the left end portion of the substrate 11 so as to be rotatable in parallel with each other. Each leading blade 10 is locked to a pair of arms 15 and 16 at its tip. Similarly, the rear blade group is locked by a pair of arms (not shown). A long hole 17 is provided in the main arm 15, and a long groove 18 is provided in the substrate 11 along the movement locus of the long hole 17 as the main arm 15 rotates. Although not shown, the long hole 17 is engaged with a drive pin that penetrates the substrate 11 through the long groove 18. When a shutter release button (not shown) is pressed, the drive pin moves upward by a biasing force applied along the long groove 18 provided in the substrate 11. Accordingly, the main arm 15 engaged with the drive pin in the elongated hole 17 and the slave arm 16 interlocked therewith rotate upward. By this rotation, the leading blade 10 runs vertically (opens in the width direction of the light shielding blade) and opens the opening 12. Next, a rear blade group (not shown) travels longitudinally to shield the opening 12 and the exposure ends.
[0004]
The light shielding blade for the focal plane shutter travels at a high speed along the exposure opening (focal plane) and is instantaneously stopped with a large impact force. Accordingly, the light-shielding blade is required to be lightweight and strong rigidity. Therefore, a plate material having such required characteristics is used as the light shielding blade. Japanese Utility Model Laid-Open No. 60-140034 discloses a single-layer plate of a plastic sheet reinforced with carbon fiber as an example of a light shielding blade. This reinforced plastic sheet has a matrix structure in which carbon fibers that are aligned in one direction and densely arranged in a thin plate shape are hardened with an impregnating resin. Such a carbon fiber reinforced plastic sheet is characterized in that it is lightweight and has high rigidity. However, the waist strength (rigidity) along the fiber alignment direction is sufficient, but the waist strength along the orthogonal direction does not necessarily satisfy the required characteristics.
[0005]
As an improvement on this point, Japanese Utility Model Laid-Open No. 60-63825 discloses an example using a carbon fiber reinforced plastic sheet material having a laminated structure. This laminated structure is shown in FIG. According to this example, the light shielding blade for the focal plane shutter device is composed of three plastic sheets in which the carbon fibers 101 are densely arranged in one direction and fixed by the matrix resin 102, and the directions of the fibers are substantially perpendicular to each other. In this way, it is formed of laminated thin plates that are stacked and bonded together. The three plastic sheets correspond to the intermediate core portion 104 and the skin portions 103 and 105 on both sides thereof. In such a three-layer structure, the alignment direction of the carbon fibers contained in each layer is orthogonal to each other, and therefore has a certain degree of rigidity at least in the width direction and the longitudinal direction of the light shielding blade.
[0006]
In addition, conventionally, light shielding blades having various structures have been proposed. For example, Japanese Patent Application Laid-Open No. 59-61827 discloses a light-shielding blade for a light control device composed of a composite member composed of a core portion having a hollow portion and a skin portion. At least one of the core part or the skin part is made of a resin reinforced with continuous carbon fiber. Japanese Unexamined Patent Publication No. 63-17435 discloses a sheet of unidirectionally oriented thermosetting resin prepreg containing 0.5 to 15% by weight of carbon black and 7 to 150 g / m ² of carbon fiber based on the synthetic resin. An ultra-thin carbon fiber reinforced thermosetting resin camera shutter blade having a total thickness of 20 to 150 μm, which is obtained by cross-laminating and curing layers or more symmetrically with respect to the neutral plane in the thickness direction, is disclosed. In Japanese Utility Model Laid-Open No. 4-61323, three or more reinforced resin sheets formed by encapsulating a plurality of carbon fibers continuous in one direction with a synthetic resin are laminated, and each of the carbon fibers of the reinforced resin sheet is formed. There is disclosed a light-shielding blade for a camera, characterized in that the directions are crossed and stacked at an angle obtained by 360 ° ÷ the number of reinforced resin sheets × 2. Japanese Patent Application Laid-Open No. 5-134289 has a multilayer structure in which carbon fibers arranged densely in a predetermined alignment direction and fixed with a matrix resin are stacked and cured, and carbon of each prepreg sheet. A light-shielding blade for a camera is disclosed that includes a laminated plate having an isotropic rigid structure in which fiber alignment directions are oriented at substantially equal acute angle intervals.
[0007]
[Problems to be solved by the invention]
Since the light shielding blade for the focal plane shutter device travels at a high speed, the light shielding blade is required to be lightweight and have high rigidity. By the way, a plurality of light shielding blades having a substantially long shape are stacked and incorporated in the focal plane shutter device. These light shielding blades travel at high speed along the exposure opening (focal plane) and stop rapidly. Since a large braking is applied, each light shielding blade may be bent when stopped. If the light-shielding blades that overlap each other bend, a gap is formed between adjacent blades, which may cause light leakage. Conventionally, material development for the purpose of improving rigidity as a single unit has been advanced as described above in order to prevent the light-shielding blade from being bent. However, in practice, a plurality of light shielding blades are incorporated in the focal plane shutter device, and light leakage from a gap generated between adjacent light shielding blades due to bending becomes a problem. In order to prevent this light leakage, it is necessary to pay attention not only to the material characteristics of a single light shielding blade but also to the relative material characteristics of adjacent light shielding blades. In this regard, no special measures have been taken in the past, which is a problem to be solved.
[0008]
[Means for solving the problems]
In order to solve the above-mentioned problems of the prior art, the following measures were taken. In other words, the focal plane shutter device according to the present invention basically has a plurality of light shielding blades that are formed in a longitudinal shape with a predetermined width, and the light shielding blades are driven to shield and retreat over the exposure aperture. The drive means to perform is provided. As a characteristic feature, each shading blade has a resin layer reinforced with fibers aligned in the direction of about 45 ° with the longitudinal direction as a core, and the resin layer reinforced with fibers aligned substantially in parallel with the longitudinal direction as an outer skin. part has a three-layer structure stacked on both surfaces of the core portion as a, that have the core of the light shielding blade adjacent the aligned direction of the fibers (fiber direction) is substantially perpendicular to each other to each other.
[0009]
According to the present invention, in the first light shielding blade, the fiber direction of the core portion is about 45 ° with respect to the longitudinal direction of the blade. In the second light-shielding blade that overlaps with the first light-shielding blade, the fiber direction of the core portion is substantially orthogonal to the fiber direction of the core portion of the first blade. Similarly, in the third and subsequent light shielding blades, the fiber direction of the core portion is substantially orthogonal to the fiber direction of the core portion of the adjacent light shielding blade. With such a configuration, even when the light shielding blade is bent during braking, it is possible to maintain such rigidity that the light shielding blades cancel the bending.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic diagram showing the structure of a focal plane shutter device and a light shielding blade according to the present invention. As shown in (A), the focal plane shutter device has a plurality of light shielding blades 10a, 10b formed in a longitudinal shape with a predetermined width, and the light shielding blades 10a, 10b travel along the width direction. And a driving means for shielding and retracting at the exposure opening 12. In the figure, the main arm 15 and the slave arm 16 engaged with the light shielding blades 10a and 10b are shown as a part of the driving means. The structure and operation of the focal plane shutter device shown in FIG. 1A are basically the same as those of the focal plane shutter device shown in FIG. 6, and corresponding parts are given corresponding reference numerals for understanding. Making it easy. In this embodiment, five light shielding blades are overlapped and incorporated in the focal plane shutter device. For convenience of explanation, the odd-numbered light shielding blades are represented by 10a, and the even-numbered light shielding blades are represented by 10b. However, the number of light shielding blades is not limited to the illustrated example.
[0011]
(B) schematically shows the structure of the five light shielding blades 10a and 10b arranged to overlap each other. Each of the light shielding blades 10a and 10b has a resin layer reinforced with fibers 101 aligned in the direction of about 45 ° with the longitudinal direction as an intermediate core portion 104, and is reinforced with fibers 101 that are also aligned substantially parallel to the longitudinal direction. It has a three-layer structure in which the resin layer is superposed on both surfaces of the intermediate core portion 104 as the skin portions 103 and 105. In the core portions 104 and 104 of the light shielding blades 10a and 10b adjacent to each other, the alignment directions of the fibers 101 are substantially orthogonal to each other. The first light-shielding blade 10a as viewed from the top is such that the fiber direction of the skin portion 103 is substantially parallel to the longitudinal direction of the blade, and the fiber direction of the core portion 104 is about 45 ° with respect to the longitudinal direction of the blade. The fiber direction of the symmetrical skin portion 105 is substantially parallel to the longitudinal direction of the blade. In the second light shielding blade 10b, the fiber direction of the skin portions 103 and 105 is substantially parallel to the longitudinal direction of the blade, and the fiber direction of the core portion 104 is the fiber direction of the core portion 104 of the first light shielding blade 10a. It is almost orthogonal to. Similarly, in the third light shielding blade 10a, the fiber direction of the skin portions 103 and 105 is substantially parallel to the longitudinal direction of the blade, and the fiber direction of the core portion 104 is the core portion 104 of the second light shielding blade 10b. It is almost orthogonal to the fiber direction. In the fourth light shielding blade 10b, the fiber direction of the skin portions 103 and 105 is substantially parallel to the longitudinal direction of the blade, and the fiber direction of the core portion 104 is the fiber direction of the core portion 104 of the third light shielding blade 10a. It is almost orthogonal to. In the fifth light shielding blade 10a, the fiber direction of the skin portions 103 and 105 is substantially parallel to the longitudinal direction of the blade, and the fiber direction of the core portion 104 is the fiber direction of the core portion 104 of the fourth light shielding blade 10b. It is almost orthogonal to.
[0012]
One light shielding blade 10a or 10b has a multilayer structure in which three so-called prepreg sheets are stacked and cured. The three prepreg sheets correspond to the intermediate core portion 104 and the skin portions 103 and 105 on both sides thereof. Each prepreg sheet has basically the same structure. That is, the carbon fibers 101 densely arranged along a predetermined alignment direction are fixed with a matrix resin. In the prepreg sheet, the matrix resin is in a semi-cured state. Therefore, it is possible to obtain a laminate that is completely cured and chemically stable by stacking prepreg sheets and heating them under pressure. In order to manufacture the prepreg sheet, for example, a bundle of carbon fibers cut in advance may be loosened and arranged on a plane and fixed with an impregnating resin. Or the bundle | flux of the carbon fiber which flows continuously may be separated and aligned for every fiber through a predetermined | prescribed mechanical means, and the carbon fiber and resin film which planarly aligned downstream may be bonded together. More preferably, in order to produce a prepreg sheet having excellent carbon fiber alignment uniformity and a small thickness, there is the following method. That is, first, a continuous yarn made of carbon fibers is wound at a predetermined pitch along the circumferential surface of the rotating drum, thereby forming a cylindrical fabric layer made of continuous yarns periodically arranged. Subsequently, after this cylindrical fabric layer is fixed with a matrix resin to form a cylindrical prepreg, the cylindrical prepreg is cut along the axial direction, peeled off from the rotating drum, and formed into a sheet shape.
[0013]
In addition, although the thing reinforced with the carbon fiber is generally used as a reinforcement member, it may replace with this and the thing reinforced with the fiber of polyparaphenylene benzobisoxazole (PBO) may be used. PBO fibers are fibers obtained by spinning liquid crystals having a rigid and extremely linear molecular structure. PBO fiber has twice the strength and elastic modulus of para-aramid fiber, and has the highest characteristics among existing organic fibers in heat resistance and flame retardancy. PBO fibers are commercially available from Toyobo Co., Ltd. under the trade name ZYLON, for example.
[0014]
FIG. 2 schematically shows the structure of a conventional light-shielding blade incorporated in a focal plane shutter device. For easy understanding, portions corresponding to the light shielding blades shown in FIG. 1B are given corresponding reference numbers. In all of the five light shielding blades 10, the fiber direction of the skin portion 103 is substantially parallel to the longitudinal direction of the blade, and the fiber direction of the core portion 104 is substantially orthogonal to the longitudinal direction of the blade and is symmetrical. The fiber direction of 105 is substantially parallel to the longitudinal direction of the blade.
[0015]
FIG. 3 schematically shows a state in which each blade 10 is bent during braking in the focal plane shutter device incorporating the conventional light shielding blade shown in FIG. As shown in the drawing, when each blade 10 travels at a high speed and is braked and stops rapidly, each light-shielding blade 10 is bent so as to wave along the longitudinal direction by the impact. In the case of the conventional example, the direction in which the rigidity of each light shielding blade 10 works (indicated by a double-headed arrow) is all the longitudinal direction, so that a large gap is formed between adjacent light shielding blades 10. This causes the film to be exposed. It should be noted that the direction in which the rigidity of the light shielding blade indicated by the double-headed arrow is in parallel with the alignment direction of the fibers included in the skin portion.
[0016]
FIG. 4 is a plan view showing a state when the light shielding blade according to the present invention is bent during braking of the focal plane shutter device. Even when the light shielding blades 10a and 10b are bent during braking, the rigidity (indicated by a double-headed arrow) can be maintained such that the blades cancel each other. That is, in the odd-numbered light-shielding blades 10a and the even-numbered light-shielding blades 10b, the alignment direction of the fibers contained in the core is 45 ° with respect to the longitudinal direction and orthogonal to each other. For this reason, the light shielding blades 10a and 10b adjacent to each other intersect with each other in the direction of rigidity indicated by a double-headed arrow, and the light shielding blades act so as to cancel the deflection. Accordingly, when viewed as the focal plane shutter device as a whole, the deflection of the light shielding blades during braking can be reduced, so that re-exposure from between the light shielding blades can be suppressed and the durability is also improved.
[0017]
【The invention's effect】
As described above, according to the present invention, in the focal plane shutter device incorporating a plurality of light-shielding blades, the first blade has a fiber direction of the core portion of about 45 ° with respect to the longitudinal direction of the blades. In the second blade that overlaps the first blade, the fiber direction of the core portion is substantially perpendicular to the fiber direction of the core portion of the first blade, and the third and subsequent blades are also in the same manner. The fiber direction is substantially perpendicular to the fiber direction of the overlapping blade cores. With such a configuration, even when the blades are bent at the time of braking, it is possible to maintain such rigidity that the blades cancel each other. As a result, the deflection of the blades during braking can be reduced, durability can be improved, and re-exposure from between the blades can be suppressed.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a focal plane shutter device and a light shielding blade according to the present invention.
FIG. 2 is a schematic view showing a conventional light shielding blade.
FIG. 3 is a schematic diagram showing an operation state of a conventional focal plane shutter device.
FIG. 4 is a schematic diagram showing an operating state of the focal plane shutter device according to the present invention.
FIG. 5 is a perspective view showing a conventional light shielding blade.
FIG. 6 is a plan view showing a configuration of a conventional focal plane shutter device.
FIG. 7 is an exploded view showing a structure of a conventional light shielding blade.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Light-shielding blade, 10a ... Light-shielding blade, 10b ... Light-shielding blade, 12 ... Opening, 15 ... Main arm, 16 ... Secondary arm, 101 ... Carbon fiber, 102. ..Matrix resin, 103 ... Skin, 104 ... Core, 105 ... Skin

Claims (1)

In a focal plane shutter device comprising a plurality of light shielding blades formed in a longitudinal shape with a predetermined width, and having driving means for driving each light shielding blade to shield and retract on the exposure opening,
Each shading blade has a core made of a resin layer reinforced with fibers aligned in the direction of about 45 ° with the longitudinal direction, and a core made of a resin layer reinforced with fibers aligned substantially parallel to the longitudinal direction. It has a three-layer structure stacked on both sides of the part,
A focal plane shutter device characterized in that the fiber alignment directions of the core portions of the light shielding blades adjacent to each other are substantially orthogonal to each other.

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