JPH08274488A - Electromagnetic wave shielding material - Google Patents

Abstract

PURPOSE: To provide an electromagnetic wave shielding material which can be easily fitted to a material to be shielded, can surely block electromagnetic waves, and has a simple constitution. CONSTITUTION: An electromagnetic wave shielding material is constituted of a sheet-like insulating cover 12 formed in a spiral cross section and a conductive sheet 14 which is put on the internal surface of the cover 12 and fixed to the inner end section 12a of the cover 12. An electric wire inserted into inside the cover 12 is not only covered with the conductive sheet 14, but also covered and pressed by the cover 12. Therefore, the joint of the sheet 14 is surely conducted in a plane due to the pressure of the cover 12. Since the cover 12 has a spiral cross section, in addition, the electric wire inserted into the cover 12 does not fall down and not special tool is required to hold the joint of the cover 12, because the joint of the cover 12 naturally closes due to the pressure of the cover 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention protects a material to be shielded from external electromagnetic waves by coating a linear material to be shielded such as electric wires and signal lines, or prevents electromagnetic waves generated from the material to be shielded from the outside. The present invention relates to an electromagnetic wave shield material that prevents leakage into the air.

[0002]

2. Description of the Related Art Conventionally, as an electromagnetic wave shielding material of this type, for example, a conductive knitted material braided with metal wires or the like or a shield material made of a metal foil such as an aluminum foil and an insulating material made of a synthetic resin or the like are stuck together. , A conductive sheet that is used by wrapping around an electric wire, etc., or a shield tube that is formed by forming a conductive layer on the inner peripheral surface of a resin-made tubular body and used by inserting an electric wire, etc. There is known a conductive tape or the like which is formed by forming a shielding material such as a metal foil or the like in a tape shape and is wound around an electric wire or the like in a spiral shape.

[0003]

However, in the case of a conductive sheet, in order to hold the conductive sheet wound around an electric wire, it is necessary to provide a fastener such as a fastener at a portion where the conductive sheets are overlapped. However, when such a fixture is provided, there is a problem that the overall shape becomes large, and since the fixture is attached in the wiring direction of the electric wire, flexibility with respect to bending is reduced. In addition, in order to reliably shield electromagnetic waves, it is necessary to make the shield material contact and conduct at the portion where the conductive sheets are overlapped to cover the wire electromagnetically without any gaps, but the insulation material will intervene so that conduction is maintained. In order to achieve this, it is necessary to take some measures and there is a problem that the configuration becomes complicated.

On the other hand, in the case of the shield tube, since the electric wire is inserted and used, the mounting work is troublesome, and if the size does not match, the mounting cannot be performed,
On the contrary, there was a problem that the mounting position would move even if it was mounted. On the other hand, a shield tube configured to be heat-shrinkable is also known, but in this case, a heating process must be performed after the wire is inserted, which increases the number of working steps, and the conductive layer. Is difficult to form on the inside of the tube when it is formed by surface treatment such as plating. Furthermore, the conductive layer does not undergo sufficient heat shrinkage, or the conductive layer peels off when heat shrinks. There was also the problem of doing.

Further, in the case of a conductive tape, the workability is poor because it is necessary to wind the wire in a spiral shape while sequentially laying the edges of the tape on the electric wire and the like. There was a problem that when the mounted part was bent, a gap was created, and electromagnetic waves could not be shielded reliably.

In order to solve the above problems, the present invention provides
It is an object of the present invention to provide an electromagnetic wave shielding material which has a good workability of attaching to a material to be shielded and has a simple structure capable of reliably shielding electromagnetic waves.

[0007]

In order to achieve the above object, the invention according to claim 1 is made of a material that reflects or absorbs an electromagnetic wave, and is for coating a linear shielded material. An electromagnetic wave shield material comprising a sheet-shaped shield member, which protects the shielded material from external electromagnetic waves, or prevents the electromagnetic waves generated from the shielded material from leaking to the outside, wherein an elastic member is provided around the shield member. It is characterized in that an insulating cover which is deformable and formed so as to cover the shielded material is provided, and the shield member and the insulating cover are partially joined.

According to a second aspect of the invention, in the electromagnetic wave shielding material according to the first aspect, the insulating cover is
A warp or weft made of a woven fabric made of a shape memory resin or a fiber made of a shape memory alloy whose surface has been insulation-treated, and when heat-treated at a predetermined temperature, it transforms into a shape that covers the shielded material. Is characterized by.

Next, the invention according to claim 3 is the electromagnetic wave shielding material according to claim 1, wherein the insulating cover is
It is characterized in that it is formed by sequentially laminating sheet-shaped resins having different heat-shrinkability, and when heat-treated at a predetermined temperature, it deforms into a shape that covers the shielded material.

Further, the invention according to claim 4 is the electromagnetic wave shielding material according to claim 1, wherein the insulating cover is made of an elastically deformable resin having thermoplasticity, and is preheated to form a shielded material. It is characterized in that it is formed into a covering shape.

According to a fifth aspect of the invention, in the electromagnetic wave shield material according to the fourth aspect, the shield member is elastically deformable and is formed in advance in a shape that covers the shielded material. Characterize.

[0012]

In the electromagnetic wave shield material according to claim 1 configured as described above, the insulating member, which is elastically deformable and formed to cover the shielded material, serves as the shield member. The coated shielded material is further coated from the outside, and the shield member is pressed inward by the force to keep the shape of the insulating cover itself. In this way, covering with an insulating cover,
By being pressed, the mating portion of the shield member is surely brought into contact with the surface for conduction, and as a result, the shielded material is electromagnetically covered by the shield member without any gap.

Therefore, according to the electromagnetic wave shielding material of the present invention, the shielded material can be surely protected from the external electromagnetic wave, and the electromagnetic wave generated from the shielded material can be surely prevented from leaking. Further, according to the present invention,
When the shielded material is covered, a pressing force is applied to the insulating cover in the direction of pressing the shielded material, so this pressing force prevents the electromagnetic shield material attached to the shielded material from being displaced in its mounting position. In addition, the mating portion of the insulating cover can be reliably closed without using a special fixture. As a result, it is not necessary to provide a fixture or the like for closing the mating portion, and the member can be downsized.

Further, according to the present invention, since the mating portion of the insulating cover is closed only by the pressing force of the insulating cover and is not fixed to each other, bending of the electromagnetic shield material such as bending in the wiring direction occurs. The insulating cover can be displaced according to the deformation, and as a result, the insulating cover is less likely to loosen at the deformed portion, and the electromagnetic wave shielding material can be easily deformed.

Next, in the electromagnetic wave shielding material according to claim 2, the insulating cover is a woven fabric in which at least one of the warp yarn and the weft yarn is made of a shape memory resin or a fiber made of a shape memory alloy whose surface is insulation-treated. When heated to a predetermined temperature at which the shape memory resin is deformed, the shape memory resin is deformed into a shape that covers the shielded material, and the shape is maintained thereafter.

Therefore, according to the electromagnetic wave shielding material of the present invention, when coating the material to be shielded, first, it is attached to the insulating cover on the flat insulating cover in a state before being deformed by heating. By covering the shielded material with a shield member, and then heating the insulating cover, it is only necessary to deform the shielded material into a shape that covers the shielded material, for example, passing the shielded material like a heat-shrinkable tube,
Since it is not necessary to fix the mating portion of the insulating cover with some fixing tool unlike the shield material formed in a sheet shape, the covering work can be facilitated.

Further, according to the present invention, since the woven fabric used as the insulating cover may be formed in a flat shape, it can be easily manufactured. The shape memory resin is a resin that deforms into a predetermined shape when heated to a predetermined temperature, and for example, polynorbornene, transisobutylene, special polyurethane, or the like can be used.

Next, in the electromagnetic wave shield material according to the third aspect, the insulating cover is formed by sequentially laminating sheet-shaped resins having different heat shrinkability, and when heat-treated, is shaped to cover the shielded material. It deforms and retains its shape thereafter. That is, when an insulating cover formed by laminating sheet-shaped resins having different heat shrinkability is heated, a difference in heat shrinkage between the laminated resins causes a stress in a joint portion to cause a resin having a small heat shrinkability. Is curved inside, and as a result, the shielded material is covered.

Therefore, according to the electromagnetic wave shielding material of the present invention, when the material to be shielded is covered, first of all, as in the invention described in claim 2, first, the planar insulation which is in a state before being deformed by heating is applied. It is enough to cover the shielded material on the cover with the shield member attached to the insulating cover, and then heat the insulating cover to deform the shielded material into a shape that covers the shielded material. it can.

In the insulating cover, the number of the resins to be stuck together may be two, or may be three or more as long as they are stuck in the order of the heat shrinkability. For example, when the heat shrinkage of the resin used is extremely different, if the resin is heated and deformed as it is, the adhesive surface may peel off and the insulating cover may be destroyed. Such destruction can be prevented by sandwiching a resin having properties.

As the resin constituting the insulating cover in the present invention, polyvinyl chloride and its copolymer, polyamide and its copolymer, polypropylene and its copolymer and the like can be used. Next, in the electromagnetic wave shielding material according to the fourth aspect, the insulating cover is made of an elastically deformable resin having thermoplasticity, and is heat-treated in advance to cover the shielded material.

That is, since the shape of the thermoplastic resin can be fixed by heat treatment, it can be easily formed into a shape that covers the shielded material by winding it around a cylindrical jig for heating and cooling. Is done. Then, in this way, in the electromagnetic wave shield material in which the insulating cover is formed in a shape to cover the shielded material in advance, the inside of the insulating cover elastically deformed from the shape to cover the shielded material by an external force is opened. , After inserting a line-shaped shielded material such as an electric wire or a signal line, covering the inserted shielded material with a shield member provided inside the insulating cover, and releasing the external force to the insulating cover, The insulating cover that tries to return to the original shape covers and presses the shielded material from the outside of the shield member. As a result, the electromagnetic wave shield material is attached to the shielded material by the pressing force of the insulating cover.

Therefore, according to the present invention, the insulating cover is formed in advance so as to cover the shielded material.
Once the shielded material is fitted inside the insulating cover, it does not fall off the shield material, so that the covering work can be performed more efficiently.

Further, according to the present invention, since the insulating cover can be made of only a single thermoplastic resin, it can be manufactured easily and at low cost. The insulating cover may be formed of a thermoplastic resin in a sheet shape, or may be a knitted woven fabric or a non-woven fabric made of a fiber made of a thermoplastic resin or a fiber coated with the thermoplastic resin. In addition, a knitted fabric coated with a polyester-based resin or the like in order to improve shape retention can be preferably used.

As the thermoplastic resin constituting the insulating cover, polyvinyl chloride, nylon, polyethylene terephthalate, polyethylene, polypropylene, etc. can be used. Next, in the electromagnetic wave shield material according to the fifth aspect, the shield member is elastically deformable and is formed in a shape that covers the shielded material in advance. Then, the shield member together with the insulating cover is deformed into an open shape by an external force, and after the shielded material is inserted inside the shield member, first, the external force to the shield member is released,
When the shield member that tries to return to the original shape covers and presses the shielded material, and then the external force to the insulating cover is released, the insulation cover that tries to return to the original shape further moves the shielded material from the outside of the shield member. Cover and press.

Therefore, according to the electromagnetic wave shield material of the present invention, the shielded material and the insulating cover doubly press the shielded material, and therefore the pressing force does not shift the mounting position of the electromagnetic wave shield material. Electromagnetic waves can be reliably shielded. Also, like the insulating cover, the shield member is formed in advance to cover the material to be shielded, so by inserting the material to be shielded inside the shield member and releasing the external force to the shield member, The member to be shielded can be easily covered by the member, and the covering work can be performed more efficiently.

[0027]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing the overall configuration of the electromagnetic wave shield material 10 of the first embodiment. As shown in FIG. 1, an electromagnetic wave shielding material 10 includes a sheet-shaped insulating cover 12 having a spiral cross-section, and end portions 12 of the insulating cover 12 which are arranged inside the insulating cover 12 and overlap each other.
Of the a and 12b, the conductive sheet 14 is fixed to the inner end 12a. The conductive sheet 14 is fixed to the outer surface of the insulating cover 12 at the end portion 12a of the insulating cover 12 by adhesion or sewing while being slightly folded back.

Here, the conductive sheet 14 is made of metal fibers such as copper or stainless steel, plated fibers obtained by plating synthetic fibers with these metals, or conductive knitted woven fabric or non-woven fabric using carbon fibers or the like, It has sufficient conductivity and flexibility. On the other hand, the insulating cover 12 is made of a fiber made of a thermoplastic resin such as polyethylene terephthalate or a braided fabric braided with a fiber coated with a thermoplastic resin, or a resin film of a thermoplastic resin.

The insulating cover 12 is initially formed in a flat shape, and after the conductive sheet 14 is bonded or sewn to the end 12a, the insulating cover 12 is heated and cooled while being wound around a cylindrical jig. As a result, it is formed in a spiral shape in cross section. Electromagnetic wave shield material 10 configured in this way
Is used by being attached to an electric wire, a signal wire or the like as follows.

That is, as shown in FIG. 2A, first, the insulating cover 12 is elastically deformed and opened so that the electric wire L can be inserted between the both ends 12a and 12b of the insulating cover 12. Along with the conductive sheet 14, the insulating cover 12
Place along the inner surface of. In this state, the conductive sheet 1
After accommodating the electric wire L inside 4, the end 14b of the conductive sheet 14 is inserted inside the end 14a joined to the insulating cover 12, as shown in FIG. 2B.

After that, the insulating cover 12 is attached to the conductive sheet 1.
On the outside of the end 12a to which the other end 4 is joined, the other end 1
2b is positioned so that when the external force that has opened the insulating cover 12 is released, the insulating cover 12 is elastically moved so as to return to its original shape, as shown in FIG. 2C. The electric wire L covered with 14 is pressed and tightened. As a result, the electromagnetic shield material 10 is attached to the outer peripheral portion of the electric wire L by the pressing force of the insulating cover 12.

As described above, according to the electromagnetic wave shield material 10 of this embodiment, the conductive sheet 1 for covering the electric wire L is used.
Since the insulating cover 12 covers 4 while pressing it from the outside, the conductive sheet 14 inserted inside the end portion 12a where the insulating cover 12 and the conductive sheet 14 are joined is
It is possible to closely contact the inner periphery between the end portion 14b and the other end 14a by a surface, and to surely bring the mating portion of the conductive sheet 14 into conduction. Further, the end portion 14a of the conductive sheet has the insulating cover 12
Since it is bent to the outer side surface of the, the conduction can be further ensured. As a result, the conductive sheet 14 electromagnetically covers the periphery of the accommodated electric wire L, so that the electric wire L can be reliably protected from external electromagnetic waves, and the electromagnetic waves generated from the electric wire L can be protected. Leakage can be reliably prevented.

Further, when the electromagnetic wave shielding material 10 is attached to the electric wire L, a force is generated in the insulating cover 12 in the direction of pressing the electric wire L, and the electric wire L is gripped by this pressing force. Not only does the mounting position of the shield material 10 not be displaced, but the end 12b arranged outside the end 12a acts so as to come into close contact with the outer surface of the insulating cover 12, so a special fixture is used. It is possible to reliably close the mating portion of both ends 12a and 12b of the insulating cover 12.

As described above, according to the electromagnetic wave shielding material 10 of this embodiment, it is not necessary to provide a fixing tool for closing the mating portion of the insulating cover 12, and the electromagnetic shielding material 10 is composed only of the conductive sheet 14 and the insulating cover 12. Therefore, the size can be reduced to the minimum. Further, according to the present embodiment, the mating portion of the insulating cover 12 is only closed by the pressing force and is not fixed, so that the electromagnetic shielding material 10 is deformed in accordance with the bending of the electric wire L in the wiring direction or the like. The end 12b of the insulating cover 12 can be freely displaced with respect to the outer surface of the insulating cover 12, and as a result, the overhang of the insulating cover 12 at the deformed portion can be minimized, and the electromagnetic wave shielding material 10 cannot be forced. It can be transformed without.

Further, according to this embodiment, the insulating cover 12
Since it is formed in a shape to cover the electric wire L in advance, once the electric wire L is fitted into the inside of the insulating cover 12, it does not fall off, and as described above, the insulating cover 12 is fixed by the special fixing tool. Since it is not necessary to fix the mating portion, the workability is extremely good and the covering work can be performed efficiently.

Here, in the above-described embodiment, the conductive sheet 14 having a flexibility that can be deformed relatively freely is used, but like the insulating cover 12, its shape is formed in a spiral cross section. You may use what was done. In this case, for example, a wire mesh braided with a wire coated with a low melting point metal may be used as the conductive sheet 14, and the conductive sheet 14 is heated to a temperature at which the low melting point metal melts in a state of being held in a predetermined shape. After that, when cooled, the shape of the conductive sheet 14 is maintained by the low melting point metal.

When the conductive sheet 14 is formed in a spiral shape as described above, when the electric wire L is covered, the electric wire L is pressed not only by the insulating cover 12 but also by the conductive sheet 14, so that the electric wire L is doubled. Since it is pressed, this pressing force
It is possible to more reliably prevent the mounting position of the electromagnetic wave shielding material 10 from being displaced from the electric wire L.

Further, since the conductive sheet 14 is formed in a spiral cross section, the electromagnetic wave shielding material 10 is connected to the electric wire L.
When it is attached to the end of the insulating cover 12,
open the ends 14a, 14b of the conductive sheet 14 together with b,
The electric wire L is simply inserted by inserting the electric wire L from between the opened ends 14a and 14b.
Since the conductive sheet 14 is easily coated, the coating work can be performed more efficiently.

Further, in the above embodiment, the conductive sheet 14 is joined to the end portion 12a of the insulating cover 12, but, for example, as shown in FIG. 3, both end portions 12a and 12b of the insulating cover 12 are omitted. Conductive sheet 14 at the intermediate point P
The end portions 14a and 14b may be joined to each other at approximately the midpoints thereof, that is, the inner surface of the insulating cover 12 is sandwiched between the mating portions of the insulating cover 12 when the electric wire L is stored. It may be joined at any position as long as it is in a unique position.

Next, the second embodiment will be described. FIG.
FIG. 3 is a perspective view showing the overall configuration of the electromagnetic wave shield material 20 of this embodiment. As shown in FIG. 4, the electromagnetic wave shielding material 2
0 is the first and second resin layers 2 having different heat shrinkability
An insulating cover 26 made of a resin film having a two-layer structure having 2, 24, and being fixed or adhered or sewn along the longitudinal direction to the surface of the insulating cover 26 at the approximate center and on the side of the second resin layer 24. And a conductive sheet 28.

Here, the conductive sheet 28 is made of the same conductive knitted woven fabric or nonwoven fabric as the conductive sheet 14 of the first embodiment. On the other hand, in the insulating cover 26, a resin having a relatively small heat shrinkability such as polyethylene terephthalate is used as the first resin layer 22, while polyethylene terephthalate and polyethylene are used as the second resin layer 24. A resin having a relatively large heat shrinkability such as a copolymer of isophthalate is used.

The insulating cover 26 is made up of resin layers 22, 2
Since the heat shrinkage ratios of Nos. 4 are different from each other, stress is generated at the joint surface when heated, and the second resin layer 24 having a large heat shrinkage ratio is deformed into a shape that is wound inside. The electromagnetic wave shielding material 20 thus configured is attached to an electric wire, a signal line or the like as follows.

That is, as shown in FIG. 5A, the electric wire L is placed on the conductive sheet 28 with the surface on which the conductive sheet 28 is attached facing upward. Next, FIG.
As shown in (b), the electric wire L placed on the conductive sheet 28 is covered with the conductive sheet 28 by overlapping both ends 28a and 28b of the conductive sheet 28.

When the insulating cover 26 is heated in this state, as shown in FIG. 5C, the insulating cover 26 has a spiral cross-section so that the second resin layer 24 to which the conductive sheet 28 is fixed is rolled up. The electric wire L, which has been deformed into a sheet and is covered with the conductive sheet 28, is covered and pressed from the outside. As a result, the electromagnetic wave shielding material 20 is attached to the outer peripheral portion of the electric wire L. The insulating cover 26 that has been heated and deformed is then held in the deformed shape.

As described above, according to the electromagnetic wave shielding material 20 of this embodiment, the state of being attached to the electric wire L is exactly the same as that of the electromagnetic wave shielding material 10 of the first embodiment. The effect can be obtained. In addition,
In order to surely deform the insulating cover 26 in a spiral shape in cross section, for example, the heat shrinkage rate of the second resin layer 24 is gradually or gradually reduced from one end 26a to the other end 26b of the insulating cover 26. , That is, the resin layer 22,
The difference in the heat shrinkage ratio between 24 may be gradually or gradually reduced from one end 26a to the other end 26b.

When the difference in heat shrinkage between the first and second resin layers 22 and 24 is large, a third resin layer having an intermediate heat shrinkage between them is provided to form a three-layer structure. By doing so, the stress generated on each adhesive surface is relieved, so that it is possible to prevent the insulating cover 26 from being broken, such as peeling of the resin layer on the adhesive surface during heat deformation. Further, the resin layers forming the insulating cover 26 are not limited to two or three layers, but may be four layers or more as long as they are sequentially laminated in the order of magnitude of heat shrinkage.

Next, in the second embodiment, the insulating cover 26 is constructed by laminating the first and second resin layers 22 and 24 having different heat shrinkability from each other, but a predetermined material such as transpolyisoprene is used. A woven fabric using fibers made of a shape memory resin that deforms to a predetermined shape when heated to a temperature may be used.

That is, when the insulating cover woven in a flat shape using the fiber made of the shape memory resin is heated,
Since the shape memory resin fiber woven into the insulating cover is deformed into a loop shape or a spiral shape, the shape memory resin fiber is deformed into a spiral shape in cross section like the insulating cover 26 of the second embodiment.
Even if this insulating cover is used in the electromagnetic wave shielding material 20 of the embodiment, the same effect can be obtained.

In this case, when the woven fabric constituting the insulating cover is heated and deformed, the weft H becomes parallel to the wiring direction X of the electric wire to be mounted, as shown in FIG. 6 (a). When the warp yarn V is orthogonal to this, a fiber made of a shape memory resin is used only for the warp yarn V, and as shown in FIG. 6B, both the warp yarn V and the weft yarn H are in the wiring direction of the electric wire. When they intersect, a fiber made of a shape memory resin may be used for both the warp yarn V and the weft yarn H. Further, instead of the fiber made of the shape memory resin, the fiber made of the shape memory alloy whose surface is subjected to insulation treatment may be used.

[Brief description of drawings]

FIG. 1 is a perspective view showing an overall configuration of an electromagnetic wave shield material according to a first embodiment.

FIG. 2 is an explanatory diagram showing a method of using the electromagnetic wave shield material of the first embodiment.

FIG. 3 is an explanatory diagram showing a bonding position between an insulating cover and a conductive sheet.

FIG. 4 is a perspective view showing an overall configuration of an electromagnetic wave shield material according to a second embodiment.

FIG. 5 is an explanatory diagram showing a method of using the electromagnetic wave shield material of the second embodiment.

FIG. 6 is an explanatory diagram showing details of an insulating cover made of a woven fabric using a shape memory resin fiber.

[Explanation of symbols]

10, 20 ... Electromagnetic wave shield material 12, 26 ... Insulating cover 14, 28 ... Conductive sheet 22 ... First resin layer
24 ... Second resin layer L ... Electric wire

Claims (5)

[Claims] 1. A sheet-shaped shield member made of a material that reflects or absorbs electromagnetic waves and is used to coat a linear shielded material, and protects the shielded material from external electromagnetic waves. In an electromagnetic wave shield material for preventing electromagnetic waves generated from the shield material from leaking to the outside, an insulating cover formed in a shape that is elastically deformable and covers the shielded material is provided around the shield member, and An electromagnetic wave shield material, wherein the shield member and the insulating cover are partially joined. 2. The insulating cover is made of a fabric using at least one of a warp yarn and a weft yarn, which is made of a shape memory resin or a fiber made of a shape memory alloy whose surface is insulated.
The electromagnetic wave shield material according to claim 1, wherein the electromagnetic wave shield material is deformed into a shape that covers the shielded material when heat-treated at a predetermined temperature. 3. The insulating cover is formed by sequentially laminating sheet-shaped resins having different heat shrinkability, and when heat-treated at a predetermined temperature, the insulating cover is transformed into a shape that covers the shielded material. The electromagnetic wave shielding material according to 1. 4. The electromagnetic wave shield according to claim 1, wherein the insulating cover is made of an elastically deformable resin having thermoplasticity, and is formed in a shape which is preheated to cover the shielded material. Material. 5. The electromagnetic wave shield material according to claim 4, wherein the shield member is elastically deformable and is formed in a shape that covers the shielded material in advance.