WO2022269745A1

WO2022269745A1 - Mask

Info

Publication number: WO2022269745A1
Application number: PCT/JP2021/023554
Authority: WO
Inventors: 聖剛藤島; 丈晴石川
Original assignee: 株式会社Roki
Priority date: 2021-06-22
Filing date: 2021-06-22
Publication date: 2022-12-29
Also published as: JPWO2022269745A1; JP7037000B1

Abstract

Provided is a mask with improved close-contact properties between the mask and each part of a face including a jaw part, the mask allowing easy breathing and having improved comfortableness. A mask 1 comprises: a sheet-shaped mask main body 10 covering a target position of the face of a wearer; and a pair of right and left ear hook parts 20 hooked behind the ears of the wearer to lock the mask main body 10. The mask main body 10 comprises a plurality of pleats 12 formed by folding a sheet 11, wherein a back surface to abut the face and a front surface on the reverse side of the back surface are distinguished from each other; the mask main body 10 is divided into a first covering region X that is an upper part and covers the nose and the periphery of the nose of the wearer, a second covering region Y that is a lower part and covers the jaw and the periphery of the jaw of the wearer, and a third covering region X that is a part between the upper part and the lower part and covers the mouth and the periphery of the mouth of the wearer; the folded width of the pleats 12 in the second covering region Y is smaller than those in the first covering region X and the third covering region Y; and a plurality of mountains of the folds of the pleats 12 is formed in the direction from bottom to top and toward the back surface side when viewed from the front surface side.

Description

mask

The present invention relates to masks.

Conventionally, masks made of non-woven fabric or the like have faced the challenge of covering the edges without any gaps while suppressing discomfort when worn by the wearer. For example, there is a known example in which a sheet is folded to form a plurality of pleats so that it can be stretched, and at the lower end of the mask body, a convexly curved dent is provided to enhance the fit to the chin of the wearer. (see Patent Document 1 below).

JP 2019-183347 A

However, in the conventional mask described above, the plurality of pleats are formed symmetrically and have equal folding widths. The length ratio is different, and the side shape (concavity and convexity and curvature) of each part is different, and even if the pleats are stretchable, it is difficult to fit each part of the face. In particular, the chin is located below the face, and when the mask is worn, it curves from the mouth of the wearer toward the neck. Due to the appearance of slack, there was a gap between the side edges and the face. This problem could not be solved even by providing a dent in the chin portion to improve the fit of the chin portion itself.

Therefore, it is an object of the present invention to provide a mask that has improved adhesion to each part of the face, including the chin, and that is easy to breathe and has improved comfort.

A mask according to an aspect of the present invention includes a sheet-like mask body covering a target portion of a wearer's face, and a pair of left and right ear hooks for engaging the mask body with the wearer's ears. The mask body includes a plurality of pleats formed by folding a sheet, a back surface that contacts the face and an opposite surface are distinguished, and a first mask that covers the wearer's nose and its surroundings on the top. It is divided into a covering area, a second covering area that covers the wearer's chin and its surroundings in the lower part, and a third covering area that covers the wearer's mouth and its surroundings between the upper and lower parts. In the second covering area, the fold width of the pleats is smaller than those of the first covering area and the third covering area, and a plurality of folds of the pleats are formed from the bottom to the top and toward the back side as viewed from the surface.

According to this aspect, since the fold width of the pleats in the chin portion is narrower than the other portions, the mask can follow the curved shape of the chin portion and fit. As a result, the surplus in this portion can be eliminated, and as a result, the fit between the side edges and the face can be improved. In addition, the folds of the pleats in the chin portion are formed in a plurality from the bottom to the top and toward the back side when viewed from the front surface, so that when the pleats are stretched, the folds protrude toward the front surface side, resulting in the mask main body. becomes easier to maintain the shape along the curve of the jaw. This improves the fit of the mask body to the chin.

In the above aspect, in the first covered region, a plurality of folds of the pleats may be formed from above downward and toward the back side when viewed from the surface.

According to this aspect, when the mask is worn, the pleats at the nose portion are stretched, so that the folds protrude toward the surface side, and the mask body has a shape that follows the curve of the nose portion of the wearer. Improves body fit. Furthermore, when the mask is worn, both the first covering region and the second covering region are in a state where the pleats are stretched and the folds protrude to the front side, so that the entire mask has a shape that draws a convex curve to the front side. A gap is created between the mouth and the mask main body in the third covering region covering the mouth, and a mask that facilitates breathing can be provided.

In the above aspect, two pleats are formed in each of the first covering region and the second covering region, and the folding width of the pleats in the second covering region is smaller than the folding width of the pleats in the first covering region. good too.

According to this aspect, by making the folding width of the pleats of the second covering region covering the chin portion smaller than that of the first covering region covering the nose portion, the fit to the chin portion can be improved and the chin portion can be improved. The pleats can be positioned relatively below the mask body, allowing the chin portion to be covered in an appropriate vertical position.

In the above aspect, in the third covering region, between the pleats of the first covering region and the second covering region, a band-shaped portion having vertical folds is formed on the back surface, and the upper and lower center positions of the band-shaped portion are located at the mask It may be positioned below the vertical center of the main body. Further, preferably, the vertical center position of the band-shaped portion is lower than half of the vertical length of the mask body, up to a range of approximately 7:3. position.

According to this aspect, by forming the third covering region covering the mouth portion downward at the upper and lower positions of the mask body, the third covering region is aligned with the mouth portion, and the second covering region is vertically aligned with the chin portion. position.

In the above aspect, a thin rod-shaped metal member, a thermoplastic member, or a thermoplastic coating metal may be provided in the left-right direction near the upper end of the mask body.
According to this aspect, by providing a metallic member, a thermoplastic member, or a thermoplastic covering metal on the upper portion of the first covering portion covering the nose portion, the upper end portion of the mask body can be formed into the convex shape of each wearer's nose. can be fitted to suit.

According to the present invention, it is possible to provide a mask that has improved adhesion to each part of the face, including the chin, and that is easy to breathe and has improved comfort.

The figure which shows the whole mask structure of this embodiment. The figure which shows the cross-sectional structure of the mask main body of this embodiment. FIG. 2 is an exploded view showing the configuration of the sheet of the mask body of the present embodiment; The figure which shows the cross-sectional structure of the mask main body which described the reference dimension in FIG. FIG. 4 is a diagram showing the relationship between each region of the mask body and the pleats shown in the example. The figure which shows the structure of the constriction of the mask main body of this embodiment.

A preferred embodiment of the present invention will be described with reference to the accompanying drawings. (In addition, in each figure, those with the same reference numerals have the same or similar configurations.)

[overall structure]
FIG. 1 is a diagram showing the overall structure of the mask 1, and FIG. 2 is a diagram showing the cross-sectional structure of the mask body 10. As shown in FIG. As shown in FIG. 1, the mask 1 according to the present embodiment includes a sheet-like mask body 10 that covers a target portion of the wearer's face, and a pair of left and right ears for locking the mask body 10 to the ears of the wearer. It consists of an ear hanging part 20 made of a hanging string.

As shown in the cross-sectional views of FIGS. 1 and 2, the mask body 10 has a horizontally long rectangular shape as a whole. 12 are formed.

FIG. 3 is an exploded view showing the configuration of the sheet 11 of the mask body 10. FIG. The mask main body 10 has a back side B on the side that contacts the face, and a front side A and a back side B as a side A on the opposite side. Specifically, as shown in FIG. 3, the sheet 11 is composed of three nonwoven fabrics, and the surface layer 11A located on the surface A side is made of a spunbond nonwoven fabric with low pressure loss and is water repellent (blood barrier property). The spunbond nonwoven fabric is also used for the mouth layer 11B located on the back surface B side, and is hydrophilic in order to absorb splashes and prevent stuffiness. On the other hand, the intermediate layer 11C is made of a meltblown nonwoven fabric and has water repellency (blood barrier properties) in order to function as a filter layer.

The mask body 10 has an upper edge 13 and a lower edge 14 that contact the wearer's nose and its surroundings and the chin and its surroundings, and a left edge 15 and a right edge 16 that contact the wearer's cheeks. The laminated nonwoven fabrics are crimped by embossing.

As shown in FIG. 2, the upper edge portion 13 is formed by folding the laminated sheet 11 to the surface A side, giving the upper portion a width of about 15 mm, and crimping it by two embossing E. As shown in FIG. 1, a nose fitter 17 made of a thin rod-shaped thermoplastic member is fitted in the gap of the embossing E in the left-right direction. In addition, the lower edge portion 14 is formed by folding the laminated sheet 11 to the surface A side, giving a width of about 10 mm to the lower portion, and crimping it by two embossing E. As shown in FIG.

The left edge portion 15 and the right edge portion 16 are crimped by a single embossing process E. The shapes are upper

inclined lines

15A and 16A extending downward and toward the center of the mask body 10 from above, and A constriction 18 is formed by intersecting lower

inclined lines

15B, 16B directed upward and toward the center. That is, the left and right edges of the mask body 10 are trimmed so that the entire left and right edges have constrictions 18, except for the upper and lower folding margins to which the embossing E is applied. A line of embossing E in the portion 16 is performed along the shape of this trimmed constriction 18 .

In the present embodiment, the constriction 18 is formed by excluding the folding margin of the upper edge portion 13 and the lower edge portion 14, but the present invention is not limited to such an aspect, and the upper edge portion 13 and the lower edge portion are formed. It is also possible to provide upper

inclined lines

15A, 16A and lower

inclined lines

15B, 16B from the portion 14, and conversely, in addition to the folding allowance of the upper edge 13 and the lower edge 14, a suitable vertical It is also possible to form the upper

slanted lines

15A, 16A and the lower

slanted lines

15B, 16B with a gap, and such changes are made within the scope of the effects described above regarding the constriction of the present invention. It is possible.

The ear hooking portion 20 is welded to the left and right ends of the upper edge portion 13 and the lower edge portion 14 . A wide ear string is adopted for the ear hooking part 20, so that the wearer's ears do not hurt even when used for a long time, and the durability and fit are improved.

[Composition of pleats]
Next, referring to FIG. 2, the configuration of the pleats 12 of the mask body 10 will be described in detail.
The mask body 10 has a first covering region X covering the wearer's nose and its periphery on the top, a second covering region Y covering the wearer's chin and its periphery on the bottom, and a mask between the top and the bottom. , and a third covering zone Z covering the wearer's mouth and its surroundings. It should be noted that this distinction between the regions is for describing the mask body 10 by virtually distinguishing it from a functional and application point of view, and does not mean that these regions are physically demarcated.

The folding width of the pleats 12 in the second covering region Y is configured to be smaller than the first covering region X and the third covering region Y. In addition, the folds 12M of the pleats 12 in this region are formed from the bottom to the top when viewed from the surface A, and a plurality of ridges 12M are formed toward the back surface B side.

On the other hand, in the first covered region X, the folds 12M (MA, MB) of the pleats 12 are formed from top to bottom when viewed from the front surface A, and are formed in plurality toward the rear surface B side.

This point will be explained more specifically using FIG. As shown in FIG. 2, in the mask body 10, the pleats 12 are formed in four stages in total, two

pleats

12A, 12B, 12C and 12D in each of the first covering region X and the second covering region Y. there is In the third covering area Z, as a result of the pleats 12A to 12D of the first covering area X and the second covering area Y, a belt-like portion 12E having folds 12ME on the back surface B is formed.

FIG. 4 shows the reference dimensions of the mask body 10 in this embodiment. Assuming that the length from the top end to the bottom end of the mask body 10 is 95 mm, the first covering region X is formed in a range of 57 mm from the top end, and the second covering region Y is formed in a range of 28 mm from the bottom end, The third covering area Z is formed in a range of 30 mm between the first covering area X and the second covering area Y while overlapping the areas thereof. In the state in which the pleats 12 of the mask body 10 shown in FIG. 2 are folded, the third covering region Z has an overlapping region with the first covering region X and the second covering region Y. When 1 is worn, the pleats 12 are stretched vertically, so that the regions X to Z do not overlap.

In the first covering region X, as shown in FIG. 4, of the total length of 57 mm in the vertical direction, no pleats 12 are formed in a region 30 mm from the upper end, and pleats 12A are formed in a region 12 mm below that. Further, after leaving a gap of 3 mm in the lower portion, pleats 12B are formed in the area of 12 mm in the lower portion. That is, the fold width of the

pleats

12A and 12B in the first covering region X is 12 mm.

Further, in the first covering region X, as shown in FIG. 2, the folds 12MA and 12MB of the

pleats

12A and 12B are both formed downward when viewed from the surface A side, and the pleat 12B is It is located on the back side of the pleat 12A.

In the second covering region Y, as shown in FIG. 4, the pleats 12 are not formed in the region 12 mm from the lower end of the total length of 28 mm in the vertical direction, and the pleats 12D are formed in the region 8 mm above it. Further, after leaving a gap of 2 mm above it, a pleat 12C is further formed in an area of 8 mm above it. That is, the fold width of the

pleats

12C and 12D in the second covering region Y is 8 mm.

In addition, in the second covering region Y, as shown in FIG. 2, the folds 12MC and 12MD of the

pleats

12C and 12D are both formed upward when viewed from the surface A side. It is located on the back side of 12D.

As shown in FIGS. 2 and 4, the gap between the first covering region X where the third covering region Z is formed and the second covering region Y, when viewed from the surface A side, is the crease between the pleats 12B and the pleats 12C. 12MB and 12MC end gaps are formed with a length of 10 mm, while the

pleats

12B and 12C are formed in the third covering region Z as a result of folding back with fold widths of 12 mm and 8 mm, respectively. The band-shaped portion 12E is formed with a total of 10 mm, 12 mm and 8 mm and a length of 30 mm in the vertical direction.

2, the

pleats

12A and 12D are located closest to the surface A, followed by the pleats 12B and 12C. is positioned one step closer to the rear surface B side, and the band-shaped portion 12E is positioned closest to the rear surface B side. That is, in this mask body 10, the pleats 12 are folded from the surface A side toward the back surface B side.

Further, as described above, the total length of the first covering region X in the vertical direction is 57 mm, the total length of the second covering region Y in the vertical direction is 28 mm, and when viewed from the surface A side in the third covering region Z The length of the gap between X and Y is 10 mm, but as shown in FIG. The reference position O is formed below C, which is the central position. That is, when the upper region of the mask body 10 from the reference position O in the band-shaped portion 12E is defined as region P and the lower region is defined as region Q, the length of P is 60 mm and the length of Q is 35 mm, and the ratio is It is approximately 6 to 4. That is, the mask main body 10 is configured such that the reference position O is lower than the central position C. As shown in FIG. The ratio between the area P and the area Q indicates the optimum embodiment. In the mask of the present invention, the reference position O should be located below the center position C, so The ratio of the length of P to the length of Q can be configured to range from greater than approximately 1:1 to approximately 7:3.

[Example regarding pleat configuration]
The lengths of the pleats 12A to 12D and the belt-like portion 12E described above merely indicate the optimum embodiment. In this regard, the present applicant made trial masks 1 with a plurality of lengths as shown in the table below regarding the lengths of the pleats 12A to 12D. It has been found to be preferable to set the range to 12 mm, that is, the range of 8.4% to 12.6% of the vertical length of the mask body 10 . The relationship between the mask main body shown in Table 1 and the regions 1 to 8 and the pleats 12A to 12D is shown in FIG.

Conversely, when the lengths of the

pleats

12C and 12D exceed 12 mm (the length exceeds the length of Example 3), when the second covering region Y comes into contact with the chin of the wearer, The result was that it did not follow the curve. Also, in this case, since the lengths of the first covering region X and the third covering region Z cannot be sufficiently secured, the space between the nose portion and the mask main body 10 cannot be sufficiently maintained, and the wearer's nose cannot be secured. The gap between the apex and the mask body 10 became narrower, resulting in a feeling of suffocation when worn for a long time.

In addition, when the length of the

pleats

12C and 12D is 8 mm or less (Comparative Examples 1, 2 and 3), when the pleats come into contact with the chin of the wearer, they do not follow the curve of the chin. rice field.

[Configuration of constriction]
Next, the configuration of the constriction 18 of the mask body 10 will be described in detail with reference to FIG.
As described above, the left edge portion 15 and the right edge portion 16 are divided into upper

inclined lines

15A and 16A extending downward and toward the center of the mask body 10, and lower

inclined lines

15B and 16B extending upward and toward the center from below. has a constriction 18 formed by intersecting. Here, since the mask body 10 is bilaterally symmetrical, only the right edge portion 16 side will be shown and explained in FIG. 6 and the following explanation for convenience.

The intersection of the upper sloping line 16A and the lower sloping line 16B forming the constriction 18 is configured to be positioned below the center position C of the mask body 10. More specifically, the constriction 18 is formed at a position 30 mm from the lower end of the mask body 10 and 65 mm from the upper end.

The vertical position of this constriction 18 and the degree of depression toward the center are determined by how the upper inclined line 16A and the lower inclined line 16B are set. That is, in this embodiment, the upper inclined line 16A forming the constriction 18 is formed at an angle of 9 degrees with respect to the line connecting the upper edge portion 13 and the lower edge portion 14 of the mask body 10. On the other hand, the lower slant line 16B is formed at an angle of 138 degrees so that the waist 18 is formed 8 mm inward toward the center of the mask.

The angles of the upper

slanted lines

15A, 16A and the lower

slanted lines

15B, 16B described above represent an optimum embodiment, and the angles of the upper

slanted lines

15A, 16A are preferably in the range of 8 degrees to 10 degrees. , and the angle of the lower

inclined lines

15B and 16B with respect to the upper

inclined lines

15A and 16A can be configured in the range of 29 degrees or more and 36.5 degrees. It can be configured in the range of ~152 degrees. The angle of the upper

inclined lines

15A, 16A should be in the range of 2 degrees to 45 degrees, and the angle of the lower

inclined lines

15B, 16B with respect to the upper

inclined lines

15A, 16A should be 3 degrees or more and less than 75 degrees. , the angle of the constriction 18 can be configured to be 50 degrees or more and less than 180 degrees, and at that time, the constriction 18 can be positioned below half of the vertical length of the mask body and up to a range of approximately 7:3. The effect of the present invention can be obtained as long as the value is set so as to form

Furthermore, in the constriction 18, the angle formed by the upper

inclined lines

15A, 16A and the lower

inclined lines

15B, 16B is not used as it is, but the intersection is cut into an R (arc) shape. This is to prevent the mask from folding over when the mask is worn, or from bending the edges of the mask in the direction opposite to the face, thereby improving the sealability of the mask to the face. This circular arc is preferably configured to draw a curve with an R of 9 to 11 mm, more preferably with an R of 10 mm.

[Effect]
In the mask 1 of the present embodiment configured as described above, the folding width of the

pleats

12C and 12D in the second covering region is narrower than that in the other portions, so that the

pleats

12C and 12D are fitted to the curved shape in the chin portion. be able to. As a result, the surplus of the mask body 10 in this portion can be eliminated, and as a result, the right and left

edges

15 and 16 of the mask body 10 and the face fit can be improved. In addition, since the folds of the

pleats

12C and 12D in the second covering region are formed from below to the upper side and toward the back side as viewed from the surface A, when the

pleats

12C and 12D are stretched during wearing, the folds 12MC , 12MD protrude to the surface side, and the mask body 10 can easily maintain the shape along the curve of the jaw. This improves the fit of the mask body 10 to the chin.

In the mask 1 of the present embodiment, the folds 12MA and 12MB of the

pleats

12A and 12B are also formed in the first covering region X from above toward the back side when viewed from the front surface. 1, the

pleats

12A and 12B are stretched in the nose portion, so that the folds 12MA and 12MB protrude toward the surface A, and the mask body 10 maintains the shape along the curve of the wearer's nose portion. becomes easier. As a result, the fit of the mask body 10 to the nose portion is improved. Furthermore, both the first covering region X and the second covering region Y are in a state in which the pleats 12 are stretched and the folds 12M protrude toward the surface side when the mask 1 is worn. It has a shape that draws a convex curve toward it, and a gap is created between the mouth and the mask body even in the third covering region Z covering the mouth, so that a mask that is easy to breathe can be provided.

In addition, by making the folding width of the pleats 12 smaller in the second covering area Y covering the chin than in the first covering area X covering the nose, the fit to the chin can be improved, and the chin can be easily adjusted. The pleats can be positioned relatively below the mask body 10 to cover the chin portion in an appropriate vertical position.

In particular, the length of the upper region P is 60 mm and the length of the lower region Q is 35 mm, and the ratio is approximately 6:4. It can be formed downward at 10 vertical positions, so that the third covering area Z can be aligned with the mouth portion, and the second covering area Y can be vertically aligned with the chin portion.

In the present invention, the reference position O, which is the vertical center position of the band-shaped portion 12E, may be set below the vertical center position C of the mask body 10. The ratio of the length of P to the length of Q is , from a range exceeding about 1:1 to a range of about 7:3.

A nose fitter 17 made of a thin rod-shaped metal member is fitted in the left-right direction in the gap formed by crimping the upper edge portion 13 of the mask body 10 by the embossing process E. As a result, the mask body 10 The upper edge portion 13 of the can be fitted according to the convex shape of the nose of each wearer. In addition, the nose fitter 17 is not limited to a metal member, and can be configured by a thermoplastic member or a thermoplastic coated metal.

According to the configuration of the pleats 12 in the present embodiment as described above, it is possible to provide a mask that improves the adhesion to each part of the face including the chin, and that facilitates breathing and improves comfort. can be done.

In addition, in the mask body 10 of the present embodiment, by providing the constrictions 18 in the left edge 15 and the right edge 16, even if the mask body is greatly curved especially at the position from the mouth to the chin, Since it can be bent at the constricted portion 18, it is possible to prevent the mask body 10 from rising from the face. This makes it possible to provide a mask with improved adhesion and followability to the wearer's face.

The constriction 18 is located below the vertical center position C of the mask body 10, and in particular, the constriction 18 is formed at a position 30 mm from the lower end of the mask body 10 and 65 mm from the upper end of the mask body 10, so that the curved portion of the constriction 18 is positioned below the mask body 10, the position of the constriction 18 can be aligned with the position where the mask body 10 is greatly curved, and the ability of the side edges of the mask body 10 to follow the face can be further enhanced. become.

In the constriction 18, the angles of the upper

inclined lines

15A, 16A and the lower

inclined lines

15B, 16B can be set to 50 degrees or more and less than 180 degrees. Therefore, it is possible to prevent the side edges of the mask body 10 from rising from the face when worn.

According to the mask 1 of this embodiment, even if there is a difference in the shape and size of the wearer's face, there is no gap between the face and the side edge of the mask body 10, and the wearer's face is It is possible to provide a mask with improved adhesion to and followability and followability.

The embodiments described above are for facilitating understanding of the present invention, and are not for limiting interpretation of the present invention. Each element included in the embodiment and its arrangement, materials, conditions, shape, size, etc. are not limited to those illustrated and can be changed as appropriate. Also, it is possible to partially replace or combine the configurations shown in different embodiments.

DESCRIPTION OF SYMBOLS 1... Mask, 10... Mask main body, 11A... Surface layer, 11B... Mouth layer, 11C... Intermediate layer, 11... Sheet, 12A, 12A to D... Pleats, 12E... Belt-shaped part, 12M... Folded mountain, 13... Upper edge part , 14... lower edge, 15... left edge, 15A, 16A... upper sloping line, 15B, 16B... lower sloping line, 16... right edge, 17... nose fitter, 18... constriction, 20... ear hook, A... front surface, B... back surface, C... center position, O... reference position, P... upper area, Q... lower area, X... first covering area, Y... second covering area, Z... third covering area

Claims

A mask comprising: a sheet-like mask body covering a target portion of a wearer's face; a plurality of pleats formed by folding a face-contacting back surface and an opposite surface thereof; A second covering area that covers the chin and its surroundings, and a third covering area that covers the wearer's mouth and its surroundings between the upper and lower parts,
In the second covering area, the fold width of the pleats is smaller than those of the first covering area and the third covering area, and the folds of the pleats are formed in a plurality from below as viewed from the surface toward the back side. Formed, mask.
2. The mask according to claim 1, wherein in the first covering region, a plurality of folds of the pleats are formed from above to below and toward the back side when viewed from the surface.
Two pleats are formed in each of the first covering region and the second covering region, and the folding width of the pleats in the second covering region is smaller than the folding width of the pleats in the first covering region. 3. A mask according to claim 2.
In the third covering area, between the pleats of the first covering area and the second covering area, a band-shaped portion having vertical folds on the back surface is formed,
4. The mask according to claim 2 or 3, wherein the vertical center position of said band-like portion is located below the vertical center of said mask body.
The mask according to claim 4, wherein the vertical center position of the band-shaped portion is located at a position lower than half of the vertical length of the mask main body and up to a range of approximately 7:3.
The mask according to any one of claims 1 to 4, wherein a thin rod-shaped metal member, a thermoplastic member, or a thermoplastic covering metal is provided in the left-right direction in the vicinity of the upper end of the mask body.