JP2532442Y2 - Sliding sheet - Google Patents

Description

[Detailed description of the invention]

[0001]

This invention relates to a sliding sheet.
More specifically, the present invention relates to a sliding sheet that is required to move at a high speed, such as a focal plane shutter of a camera or a shutter blade or an aperture blade of a lens shutter.

[0002]

2. Description of the Related Art In a focal plane shutter in which a shutter speed is increased to widen a photographing area or the like, in a configuration using a sliding sheet made of metal such as a duralumin plate, the weight can be suppressed to a certain level or less. It is impossible, and the shutter speed is limited to about 1/4000 second. Therefore, in order to achieve higher speed, a sliding sheet in which a prepreg (semi-cured) sheet obtained by impregnating a matrix resin into a lightweight carbon fiber having a high specific rigidity is used.
It has been proposed (JP-A-62-109032).

[0003]

[Problems to be Solved by the Invention] By the way, shutter blades and the like require a short moving distance and a high speed, so that a rapid rise in the speed is required.
It is necessary to reduce the inertial mass, and weight reduction is extremely important. Also, if the shutter blades are blurred or bent during high-speed movement, the light-shielding properties will be reduced, causing a problem.
It is necessary to have sufficient bending strength. However, the conventional laminated structure of carbon fiber-containing prepreg sheets has limitations in achieving both weight reduction and strength maintenance.

Therefore, the purpose of the present invention is to use carbon fiber,
Another object of the present invention is to provide a sliding sheet that achieves both weight reduction and strength maintenance.

[0005]

In order to achieve the above object, a sliding sheet according to the present invention comprises a surface layer formed from a prepreg sheet obtained by impregnating a unidirectionally oriented carbon fiber with a matrix resin. And an intermediate layer formed of a prepreg sheet in which a fibrous synthetic resin lighter than carbon fibers is oriented in a direction orthogonal to the carbon fibers and is impregnated with a matrix resin.

[0006]

Since the bending strength of the sheet-like member is more related to the portion closer to the surface layer, in a sheet having the same thickness as the conventional one, a prepreg in which the surface layer is impregnated with carbon fiber having a high elastic modulus and a matrix resin. Using a sheet, the intermediate layer, even if using a prepreg sheet impregnated with a matrix resin in a lighter weight fibrous synthetic resin having a smaller elastic modulus than carbon fibers, the overall bending strength is not so small, that is, The weight can be reduced without substantially changing the bending strength.

[0007] Incidentally, the elastic modulus of the entire laminate of a laminate comprising a pair of surface layers and an intermediate layer is as follows when the same material is used for both surface layers.

[0008] Based on this result, the present inventor assumed that a shutter blade would be made, and as shown in FIG.
m), a prepreg sheet in which the same carbon fiber is impregnated with a matrix resin is used for both the surface layer and the intermediate layer, and the direction of the carbon fiber is orthogonal to the surface layer and the intermediate layer. The total elastic modulus in the direction of the carbon fibers in the surface layer was obtained by changing the thickness variously. (Since the total thickness is the same, the total elastic modulus in the direction of the carbon fibers in the surface layer is known. The bending strength in the direction of the fiber is determined as a value proportional thereto.) The number of carbon fibers in the unit cross-sectional area in the direction perpendicular to the carbon fiber direction is the same.

That is, the elastic modulus of the prepreg sheet in the carbon fiber direction is 6 × 10 ³ kgf / mm ² (the leftmost position in FIG. 2), and the elastic modulus in the direction perpendicular to the carbon fiber direction is 0.3. × 10 ³ kgf / mm ² (rightmost position in FIG. 2). Considering the elastic modulus of the surface layer in the direction of the carbon fiber, the elastic modulus of the surface layer is 6 × 10 ³ kgf / mm ^2.
And the elastic modulus of the intermediate layer is 0.28 × 10 ³ kgf / m
m ² .

[0010] As is apparent from this figure, the elastic modulus of the entire thickness of the surface layer in the direction of the carbon fibers reaches the point P1 at a ratio of surface layer: intermediate layer: surface layer = 1: 1: 1. Even if the thickness of the intermediate layer is increased, it hardly changes. Although the elastic modulus of the intermediate layer is almost small (nearly 0) as described above, the surface layer: intermediate layer: surface layer = 1: 1: 1.
Even when the point P1 is reached, the overall elastic modulus hardly changes.

The elastic modulus of the shutter blade for a high-speed focal plane is about 4000 kgf / mm ^2.
If necessary, the thickness of the intermediate layer at this time is about 63 μm as shown in FIG. 2 (shown at a point P2), that is, even if the intermediate layer is formed up to 70% of the total thickness, it can be used.

In these descriptions, the elastic modulus of the entire thickness of the surface layer in the direction perpendicular to the carbon fiber direction is not considered, but in the case of an elongated shape such as a shutter blade, the width direction is not considered. The bending moment is not so large, and thus the elastic modulus (ie, bending strength) of the entire thickness in the width direction may be small. In the present invention, the elastic modulus of the entire thickness in the width direction is determined by the synthetic resin of the intermediate layer. And the elastic modulus in the width direction of the carbon fiber prepreg sheet of the surface layer (that is, the direction perpendicular to the carbon fiber direction).

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings.

First, in FIG. 1, a prepreg sheet in which carbon fibers 1a are oriented in one direction and impregnated with a matrix resin 1b made of a thermosetting resin is used for both surface layers 1, as in the prior art. As the matrix resin 1b, an epoxy resin, an unsaturated polyester resin, or the like can be used.

As the intermediate layer 2, a prepreg sheet formed by orienting the elongated synthetic resin fibers 2a in one direction and impregnating a matrix resin 2b made of a thermosetting resin is used. As the synthetic resin, carbon fiber (specific gravity: 1.78
High molecular weight polyethylene (specific gravity: about 0.97), aramid (specific gravity: about 1.4)
4), polypropylene (specific gravity: about 0.90), polyester (specific gravity: about 1.38), nylon (trade name of DuPont, specific gravity: about 1.14) and the like are used. The synthetic resin fiber 2a can be produced in the same manner as in a conventional synthetic fiber manufacturing method. As the matrix resin 2b, the same as the matrix resin 1b used for the surface layer 1 can be used.

The total thickness of the laminated layers is, for example, 90 to 150 μm.
At this time, as described above, the thickness of the intermediate layer is 70% or less of the total thickness, and the thickness of both surface layers is 15% or more correspondingly.

In order to produce the shutter blades 3, these prepreg sheets are laminated with the middle layer and both surface layers having the fiber directions orthogonal to each other.
Apply pressure. At this time, since both the intermediate layer and the surface layer use a matrix resin made of a thermosetting resin,
The layers can be strongly adhered to each other during hot pressing, and peeling between layers can be prevented. Then, the direction of the carbon fibers in the surface layer is set to the longitudinal direction, and the direction of the fibers in the intermediate layer is set to the width direction.

As a result, the weight of the shutter blades 3 can be reduced while maintaining sufficient strength to withstand use.

The shutter blade 3 manufactured in the above embodiment may be provided with a coating or the like on the upper surface of the surface layer for improving the sliding property and the light shielding property.

The shutter blade 3 thus manufactured
3, an embossed portion 30 is formed, and as shown in FIG. 4, the embossed portion 30 is attached to the connecting shafts 31, 32, and attached to the arms 33, 34. Further, the other three blades 36, 37, and 38 manufactured in the same manner are similarly attached to the arm, and when the rotating portion 39 is rotated by a predetermined means, the blades 3, 3 are rotated by the parallel crank mechanism.
6, 37, 38 move in parallel to open and close the shutter. Here, since the blades 3, 36, 37, and 38 are lightweight, the shutter speed can be increased. Also, since it has a sufficient bending strength, there is no blurring or bending, and light-shielding properties are maintained.

In the above embodiment, a three-layer structure is shown.
The present invention can be applied to a case where more layers are stacked. For example, in the gap between the intermediate layer and both surface layers, a thin prepreg sheet made of carbon fiber or the above-mentioned synthetic resin fiber is interposed with the fiber direction in the width direction, and the prepreg sheet made of carbon fiber is placed on the fiber direction in the fiber direction. What was laminated | stacked in the longitudinal direction may be sufficient. In this case, the elastic modulus in the width direction can be carried by the prepreg sheet made of the carbon fiber or the synthetic resin fiber laminated on the intermediate layer. At this time, since this layer is located at a position away from the neutral plane, In addition, the overall elastic modulus in the width direction can be considerably increased.

[0022]

According to the present invention, as described above, carbon fibers are oriented in one direction in the surface layer, and a fibrous synthetic resin lighter than carbon fibers is oriented in the direction perpendicular to the carbon fibers in the intermediate layer. Therefore, it is possible to obtain a sliding sheet that satisfies both weight reduction and strength.

[Brief description of the drawings]

FIG. 1 is a sectional view in the width direction of a shutter blade according to an embodiment of the present invention.

FIG. 2 is a diagram showing the relationship between the ratio of the thickness of both surface layers and the intermediate layer and the overall elastic modulus.

FIG. 3 is a plan view of one shutter blade.

FIG. 4 is a plan view of a focal plane shutter incorporating the shutter blades of FIG. 3;

[Explanation of symbols]

 Reference Signs List 1 surface layer 1a carbon fiber 1b, 2b matrix resin 2 intermediate layer 2a fibrous synthetic resin

Claims (1)

(57) [Scope of request for utility model registration] 1. A surface layer formed from a prepreg sheet obtained by impregnating a matrix resin into unidirectionally oriented carbon fibers, and a fibrous material located in a gap between the surface layers and lighter than the carbon fibers. And a middle layer formed from a prepreg sheet impregnated with a matrix resin, wherein the synthetic resin is oriented in a direction perpendicular to the carbon fibers.