KR102149675B1 - surgical mask - Google Patents

Abstract

The present invention relates to a surgical mask used for bacterial infection during surgery. More specifically, according to the present invention, the surgical mask comprises: an external blocking film formed on the outside of a filter film filtering dust or pathogens generated during surgery. The filter film and the external blocking film have a space part formed by integrally coupling all or a part of both edges and a lower end and spacing the insides, such that air rising from a lower part should flow at the outside by the external blocking film and air of an upper space between the filter film and the external blocking film is supplied and inhaled when an operator breathes, thereby minimizing inhalation of harmful gas.

Description

Surgical mask

The present invention relates to a surgical mask used to prevent bacterial transmission during surgery, and more particularly, to further form an external blocking film outside the filter film for filtering dust or pathogens generated during surgery, the filter film and the external blocking film The upper part of the upper space between the filter membrane and the outer barrier membrane is made to flow outward by the outer barrier membrane so that the air rising from the lower part is integrally combined with the lower part and all or part of both edges and the inner side is spaced apart. It relates to a surgical mask capable of minimizing inhalation of harmful gases by inhaling air.

The mask blocks the inhalation of contaminants from the outside into the nose or mouth, or blocks the discharge of various bacteria in the mouth to the outside. In particular, hospitals dealing with patients are the most basic preventive device to prevent secondary hepatitis between patients and medical personnel.

Typically, a surgical mask is composed of a filter membrane made of a material that is expandable and air-permeable through the formation of wrinkles, and a hanging means that is integrally coupled to both sides of the filter membrane and coupled to the wearer's head or ears to fix the mask. . In addition, in order to improve the airtightness, a metal band is mounted on the top of the filter membrane, and after mounting the wearer, the metal band is pressed to fit the top of the mask with the wearer's facial curves.

A commonly used mask is a structure that covers the nose and mouth and closes the edge to the face as much as possible to inhale only the air that has passed through the filter membrane of the mask when breathing. This structure can be provided by separating dust or bacteria through a filter membrane, but has a disadvantage in that it cannot separate harmful gases.

For example, looking at the operation situation, when the patient lies on the operating table, the surgeon performs the operation while looking at the patient downward from the top of the operating table, and at this time, the surgeon performs the operation by bowing his head 30 to 45 degrees downward based on the vertical. In the process of surgery, the operation of blocking blood vessels by cutting with a laser or touching the tissue is performed. In this process, combustion gas is generated as the tissue is burned by high heat, and the generated combustion gas is moved to the upper part of the operator's face. It moves upward past. At this time, the operator can remove dust larger than a certain size through the mask, but the ultrafine dust and harmful gas cannot be removed, so inhalation is repeatedly performed with a respirator.

For example, in prostate surgery, an endoscope is inserted into the bladder through the urethra, so the gas generated during the operation is collected in the bladder, and when the endoscope is removed from the urethra after the operation is completed, the urethra is opened and the gas collected in the bladder is discharged. When the surgery is repeatedly performed, such as being transmitted to the surgeon and inhalation is performed, the exposure and inhalation of harmful gases to the surgeon increases, which has a detrimental effect on health.

Korean Patent Publication No. 10-1997-7005938 (published on November 3, 1997; hereinafter referred to as'priority document 1') proposed a surgical face mask. The prior document 1 is to form a mask material positioned on the wearer's mouth part of the transparent film so that the wearer's mouth can be seen even while wearing the mask. However, the Prior Document 1 also forms a transparent film on the mouth or eyes, and air inhalation into the mask is made through the lower side where the transparent film is formed, and thus the inhalation of harmful gas that moves upward during surgery cannot be blocked.

Korean Utility Model No. 20-2017-0001213 (published on April 4, 2017; hereinafter referred to as'priority document 2') proposed a mask for blocking UV rays. The Prior Document 2 includes a first cover that covers the user's face and a second cover that is in close contact with the user's nose and mouth. Prior Document 2 covers the face as much as possible to block ultraviolet rays, while the filter function of the mask is made by a second cover that covers the nose and mouth with a minimum area. However, the prior document 2 also blocks only ultraviolet rays, but does not provide a function of blocking harmful gases flowing from the bottom.

Accordingly, there is a need for a mask having a new structure that can prevent the surgeon from directly inhaling combustion gases or various harmful gases generated during surgery.

Korean Patent Publication No. 10-1997-7005938 (published on November 3, 1997): Face mask for surgery Korean Utility Model Publication No. 20-2017-0001213 (published on April 4, 2017): UV protection mask

The surgical mask of the present invention for solving the problems of the prior art as described above,

An object of the present invention is to provide a mask having a structure in which an external barrier layer is bonded to the outside of the filter membrane, and harmful gas that moves upward from the bottom is pushed outward by the external barrier layer and is sucked through the filter membrane.

The surgical mask of the present invention for solving the above problems,

A surgical mask comprising: a filter membrane covering a wearer's mouth and nose; An external blocking film disposed on an outer surface of the filter film, the lower end and the side edge thereof being coupled to the filter film, and spaced apart from the filter film to form an inner space therein; It is configured to include a; fixing strap for fixing the filter membrane to be in close contact with the wearer's face.

The outer barrier layer may be formed of a film that blocks gas flow, and a pair of seating grooves on which a magnifying glass is mounted may be formed on an upper portion of the outer barrier layer.

In addition, a lateral flow blade may be further formed on the outer barrier layer to be folded in multiple stages.

At this time, the lateral flow blade may be folded while being opened or overlapped with a cutout portion formed along the central line.

In addition, an elastic band is attached to the incision to cover the gap so as to prevent harmful gas from being moved upward through the incision.

In addition, the lateral flow blade is formed of a first-stage horizontal portion, which is a surface folded outward from the outer barrier, and a two-stage vertical portion that is folded downward from the first-stage horizontal portion, and the first-stage horizontal portion has a center point as a low point and upwards to both sides. It is configured to have an inclination so that the central gas can be moved upward while being pushed to both sides.

In addition, the sealing film 70 is horizontally long at the inner or outer upper end of the filter film, and only the upper end of the sealing film is attached to the filter film, so that when the wearer exhales air, the sealing film opens from the filter film and seals the gap between the filter film and the face skin. Alternatively, movement to a region adjacent to the filter film may be blocked.

In addition, under the filter film and the outer barrier film, a chin strap that is bent or gently bent in a "b" shape may be further formed in a predetermined section.

The surgical mask of the present invention by the solution means,

Since the lower part of the outer barrier membrane is attached to the lower part of the filter membrane, harmful gases that move upward from the bottom are pushed outward along the outer surface of the outer barrier membrane, and the operator can inhale the air inside the outer barrier membrane and the space above it. .

In addition, a multi-stage folded lateral flow blade is formed on the outer barrier layer to allow harmful gas that moves upward from the front of the mask to flow to the side, thereby preventing inflow into the inner space through the central upper space.

In this way, the external blocking membrane can promote the health of the surgeon by blocking the inhalation of the high-concentration harmful gas discharged during the surgery to the surgeon through the filter membrane.

In addition, by forming a seating groove on the upper part of the external blocking film, it is possible to prevent the magnifying glass from getting caught in the external blocking film while ensuring stable support when using the magnifying glass, thereby minimizing the inhalation of harmful gases to improve the health and convenience of the operator. do.

1 and 2 are a perspective view and a wearing state diagram of a surgical mask according to an embodiment of the present invention.
3A and 3B are a front view and a state of use of a surgical mask having a seating groove according to an embodiment of the present invention.
3C is a cross-sectional view showing a form in which a wider portion is further formed in the seating groove based on the cross-sectional view AA of FIG.
4A to 4C are vertical cross-sectional, front and plan views of an outer barrier showing a lateral flow blade according to the present invention.
5A to 5C are vertical cross-sectional, front and plan views of an external barrier showing another type of lateral flow blade according to the present invention.
6A and 6B are a front view and a plan view showing a form in which an incision is formed to be opened outward in the center line of the side flow blade according to the present invention.
Figure 6c is a perspective view showing a main portion showing a form formed so as to open the incision inward to the center line of the side flow wing according to the present invention
7A and 7B are a plan view and a main perspective view showing an elastic band or an upper barrier film attached to the incision portion of the side flow blade according to the present invention.
8A and 8B are a front view and a vertical cross-sectional view showing a mask in which side-guided wrinkles are formed according to the present invention.
9A and 9B are cross-sectional views showing a state in which a sealing film is installed on the filter film according to the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The present invention may be modified in various ways and may have various forms. Specific embodiments are illustrated in the drawings, and the present invention will be described in detail in the text. However, this is not intended to limit the present invention to a specific form of disclosure, it is to be understood as including all changes, equivalents, or substitutes included in the spirit and scope of the present invention. In describing each drawing, similar reference numerals have been used for similar elements. In the accompanying drawings, the dimensions of the structures are shown to be enlarged or reduced than in actuality for clarity of the present invention.

The terms used in the present application are used only to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In the present application, terms such as "comprise", "include" or "have" are intended to designate the presence of features, numbers, steps, actions, elements, or a combination thereof described in the specification. It is to be understood that the presence or addition of other features, numbers, steps, actions, components, or combinations thereof, does not preclude in advance.

Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs. Terms commonly used and defined in the dictionary should be construed as having a meaning consistent with the meaning of the related technology, and should not be interpreted as an ideal or excessively formal meaning unless explicitly defined in the present application. .

1 is a perspective view showing a surgical mask according to a preferred embodiment, Figure 2 is a side cross-sectional view showing a wearing state of the surgical mask according to the present invention.

As referenced, the surgical mask 10 according to the present invention includes a filter film 20, an external blocking film 30, and a fixing strap 50.

The filter film 20 is a film for separating various bacteria or dust contained in the outside air by forming a multi-layered filter layer of various materials, and a material generally used as a medical mask can be used, and the inner surface is formed to be wrinkled. Thus, it can be transformed to fit the shape of the wearer's face.

The outer barrier layer 30 is a material that blocks air or moisture, and typically, a film-type vinyl or plastic material that is thin and capable of maintaining its shape may be used. The outer barrier layer 30 may be formed of a variety of materials such as transparent, semi-transparent, or opaque material, and may be mixed with colors.

The outer blocking film 30 and the filter film 20 are attached or coupled to each other through a lower end and a side edge.

Here, the lower end of the outer blocking film 30 may be formed to have a short width, the upper end may be formed to have a long width, and the width of the lower end may be formed to have the same length as the lower end of the filter film 20 formed in a rectangular shape.

When the outer blocking film 30 having such a shape is combined with the filter film 20 by matching the lower and side ends, the outer blocking film 30 is attached to the vertically disposed filter film at the lower end to be sealed. An inner space 40 is formed between the outer blocking film 30 and the filter film 20 while spreading outward, and the inner space 40 has a structure that opens upward.

Therefore, the operation or procedure is performed with the wearer wearing the mask 10 and the head bent at 30 to 40 degrees. At this time, when the wearer breathes, the air above the inner space 40 is introduced into the inner space, filtered by the filter membrane 20, and then sucked into the wearer. In addition, the harmful gas generated during the surgery or procedure moves upward and comes into contact with the outer barrier layer of the mask 10, and the outer barrier layer 30 pushes the harmful gas away from the filter membrane, and protrudes from the top of the outer barrier layer. By the part, the harmful gas is pushed to both sides from the center line of the outer barrier film and moves upward. This can significantly prevent the inflow of harmful gas into the upper area of the inner space where the wearer's breathing takes place, and thus the amount of harmful gas inhaled by the wearer can be drastically reduced compared to a general surgical mask.

The fixing strap 50 minimizes the inflow of external air into the space between the filter membrane and the facial skin by attaching the filter membrane 20 to the face of the wearer to prevent the edge of the filter membrane from being in close contact with the face and being lifted.

The fixing strap 50 may be provided in the form of a closed ring or hook to be hung on the ear of the wearer, or may be formed as a pair of open straps to be tied behind the ear or head of the wearer.

In the surgical mask 10 according to the present invention configured as described above, a pair of seating grooves 31 may be formed on the outer barrier layer as shown in FIGS. 3A and 3B.

The seating groove 31 is to allow the wearer to place the magnifying glass 60 mounted on the wearer, and formed to have a size equal to or slightly smaller than the diameter of the magnifying glass to allow the magnifying glass 60 to be simply placed or fixed. have.

In addition, as shown in FIG. 3C, the surface of the seating groove 31 may have a wider wide portion 311 further formed in order to stably support the magnifying glass. Here, the wide portion 311 may be provided in various forms according to a usage environment, such as protruding both inside and outside in the face-side direction as shown, or protruding only the outside or the inside.

The surgical mask 10 of the present invention may further have a multi-stage lateral flow blade 32 folded outward on the outer blocking film 30 as shown in FIGS. 4A to 4C.

As shown in FIG. 4A, the lateral flow blade 32 is a first-stage horizontal part by first folding in the horizontal direction at the top of the outer barrier layer 30 arranged in the vertical direction and the second folding in the horizontal direction again downward ( 321 and a two-stage vertical portion 322 are formed.

Looking at the process of moving the noxious gas in the mask in which the side flow blades 32 are formed by the two-stage folding, the noxious gas moving upward from the lower part rises along the outer surface of the outer barrier layer 30 (FIG. 4A). The risen harmful gas flows into the inside of the side flow wing 32 in the form of a conduit open downward, and when it reaches the first stage horizontal portion 321 of the side flow wing, upward movement is blocked by the second stage vertical portion 322 and the inside of the side flow wing It moves to the side along the pipe, which is a space, and is discharged from the side to the outside (FIGS. 4B and 4C).

The outer barrier film 30 of the present invention has a central portion protruding forward in an inverted cone shape, so that the harmful gas rising to the center is moved to both sides by the protruding portion, and the residual harmful gas not moved to both sides is a side flow blade. (32) It is guided to both sides through the central part to carry out movement and discharge.

Referring to Figure 4b, the two-stage vertical portion 322 of the side flow blade 32 is formed to have a narrower length extending downward from the center to both sides, so that both sides are first opened to the outside, so that the flow of the ascending air flow is moved from the center to both sides. Can be made.

In addition, as shown in Figs. 5A to 5C, the folding line, which is the boundary between the outer barrier layer 30 and the side flow blade 32, has the center line as a low point and has an upward slope to both sides, so that the central gas is pushed to both sides. It can be moved upward.

That is, the first stage horizontal portion 321 of the side flow blade may be formed in a low center, and disposed in a V-shape formed high on both sides. When formed in a V-shape in this way, the gas flowing into the center is moved upward along the slope of the first stage horizontal part 321 to the side so that the harmful gas moving upward from the front side of the face can be easily changed to move to both sides. You can let it go.

In the present invention, the lateral flow blade 32 has been described as being formed in a two-stage folding, but it will include a variety of shapes for moving the rising gas to both sides, such as a single-stage form, a two-stage or more form, a pleat form, and a detachable form.

As shown in FIGS. 6A and 6B, the lateral flow blade 32 according to the present invention is further formed with a cutout 323 along the center line, so that the cutout is opened and can be easily folded when folded to the outside in multiple stages.

That is, when the flat film is bent to a curved surface and the upper portion is folded outward, the folded surface is in close contact with the body surface, and thus it is difficult to form a space for guiding the gas to the side. Accordingly, by forming the cutout portion 323 to open the center to both sides, the first-stage horizontal portion 321 maintains the shape horizontally, thereby forming a space for moving to the side while blocking the upper movement of the harmful gas.

In addition, various shape maintaining means may be applied to the lateral flow blade 32, such as a corrugated part that can be provided in a form of forming a plurality of corrugations so that it can be spread in a fan shape at the place of the incision.

In addition, the cutout portion is formed on the entire surface of the first horizontal portion 321 and the second vertical portion, or is formed only on a portion of the outer side of the first horizontal portion and the second vertical portion. While maintaining the curved surface by the inside that is not formed, it is possible to facilitate bending by the cutout on the outside.

As shown in FIG. 6C, the cutout 323 may be formed to be continuous with the inner side of the lateral flow blade 32 and the upper part of the outer blocking film 30 connected thereto. When wearing a mask having such a structure, a load is applied to the outer blocking film in a direction bending outward, and the first horizontal portion 321 of the side flow blade 32 overlaps or overlaps the incision formed in the inner side. It is folded by, and the degree of folding is made into a smooth curved surface by the two-stage vertical portion 322 in which the incision is not formed. Here, overlapping occurs as an overlap width of the horizontal portion of the first stage of the lateral flow blade as a part of the upper portion of the outer blocking film.

As shown in FIG. 7A, an elastic band 33 may be attached to the incision 323 to cover the gap. For example, when the side flow blade 32 is folded, the cutout 323 is opened, and harmful gas may be discharged through the gap.

Therefore, if the elastic band 33 is attached to the cut-out part 323, even if the cut-out part is opened, the elastic band fills the gap, so that the harmful gas can be moved to both sides.

In addition, since the elastic band 33 pulls the cut-out first-stage horizontal portions 321 on both sides toward the center, the lateral flow wings 32 folded forward are prevented from being excessively widened to both sides, thereby having a space therein. It is possible to maintain the shape of the side flow wing in the form of a pipe.

7B shows an example in which the upper blocking film 34 is attached to the incision 323. As shown, an upper barrier layer 34 covering the incision is attached to an upper portion of the lateral flow blade 32 of the external barrier according to the present invention on which the incision 323 is formed, so that the gap created when the incision opens when the lateral flow wing is bent. It is blocked by covering the upper barrier. Here, the upper barrier layer 34 is an adhesive surface only on one side of both sides of the incision so that the side flow blade 32 composed of the first horizontal portion 321 and the second vertical portion 322 can cover the incision open when it is bent. Attachment is made via (341) and the other side can only be placed in a stacked state. When combined in this way, the incision can be freely expanded within the region of the overlapped upper barrier layer, thereby preventing the gas component from being discharged through the open gap of the incision.

As shown in FIGS. 8A and 8B, side induction wrinkles 35 may be further formed on the outer barrier layer 30. The side guiding wrinkles 35 are formed in a V-shape with the center as a low point and an upward slope toward both sides.

These side induction wrinkles 35 are formed in one or a plurality, and may be formed in various shapes to have an upward slope from the center to both sides, such as gradually widening the wrinkle spacing from the center to both sides or forming at the same distance.

In particular, the side guiding wrinkles 35 allow a U-shaped or V-shaped groove to be formed that is opened downward by the wrinkles on the outer surface exposed to the outside. The groove confines gas rising along the outer surface of the outer barrier layer in the groove so that the moving direction is moved laterally. That is, the harmful gas moving upward to the center is guided to the groove of the side guide folds and is moved to the side, and the remaining amount of harmful gas is blocked from moving upward from the center by the side flow blades, and the inner space of the mask where the wearer breathes air. It is possible to block the inflow of harmful gas into the upper area of the.

Accordingly, the harmful gas discharged from the combustion of human tissue during surgery or procedure is shifted to the side by the shape of the outer barrier formed on the wearer's mask, thereby minimizing the wearer's inhalation.

As shown in FIG. 9A, in the surgical mask according to the present invention, a sealing film 70 may be further attached to an inner upper end of the filter film 20.

The sealing film 70 has a pocket shape in a reverse direction with only the upper end and the side end attached to the upper portion of the filter film and the lower side being opened. The sealing film is formed of a thin vinyl or film having a top and bottom width in the range of 0.5 to 3 cm, and is moved to be separated from the filter film or interviewed.

When the wearer exhales air, the sealing film 70 flows between the sealing film and the filter film 20 and pushes the sealing film away from the filter film due to a blockage of the discharge passage. Here, since the wearer's face is located in the direction away from the filter film, the sealing film is moved in a direction in which the sealing film is in close contact with the wearer's face by exhaled air pressure to remove the gap between the wearer's face and the filter film. Therefore, since the wearer's exhaled air is not discharged through the space between the face and the filter membrane, fogging on the glasses can be prevented when wearing glasses.

As shown in FIG. 9B, the sealing film 70 may be attached to an outer upper end of the filter film 20. At this time, the sealing film can further prevent fogging of the glasses by reducing the amount of the exhaust air rising to the inner space between the outer barrier films to the space close to the wearer's face surface.

As shown, the sealing membrane may be installed solely on the outside, in addition to the type installed on both the inner and outer tops of the filter membrane.

In addition, it is possible to block exhaust air in a wider area by further increasing the protruding length of the sealing film formed on the outside than the inner sealing film.

In addition, the lower portion of the filter film 20 and the outer barrier film 30 is formed with a bent chin rest 80 in a "b" shape, so that when wearing a mask, the chin rest wraps or adheres to the wearer's chin to move upward. Can be blocked.

The chin rest 80 may be formed on either or both of the front or both sides of the wearer to provide both locking and adhesion when worn, and may be formed as a smooth curved surface or formed by bending as shown. have.

In addition, the shape of the curved surface for forming the chin rest may be maintained by the outer blocking film, or a separate shape-retaining layer may be further interposed only in a lower portion of the filter film and the outer blocking film to maintain the shape of the chin rest. .

Looking at the harmful gas blocking process of the surgical mask 10 of the present invention configured as described above,

When human tissues are burned during an operation or procedure, harmful gas is generated, and the generated harmful gas moves upward and passes through the face of the wearer who is the operator.

At this time, the harmful gas rises along the outer surface of the outer barrier layer 30 among the wearer's mask, and the central harmful gas moves to the side due to the forward protrusion of the outer barrier layer, and the residual harmful gas that has not completely moved to the side flows to the side. Since it is collected by the wings 32 and guided to both sides to be discharged, it is possible to minimize the inflow of harmful gas into the upper area of the mask inner space 40.

In addition, when the wearer inhales air, the air in the upper region of the mask flows into the inner space 40 and is purified through the filter membrane 20 and then suction is performed.

Therefore, the surgical mask 10 of the present invention minimizes the inhalation of the harmful gas generated during the surgery by forming a path of the movement of the harmful gas and the movement path of the inhaled air of the wearer differently, thereby promoting the health of the wearer. .

10: mask
20: filter membrane
30: external barrier
31: seating groove 32: side flow wing
33: elastic band 34: upper barrier
35: Lateral induction wrinkle
311: wide part 321: 1-stage horizontal part
322: 2-stage vertical part 323: cutout
40: internal space
50: fixing strap
60: magnifying glass
70: sealing film
80: chin rest

Claims (11)

In the surgical mask,
A filter membrane 20 covering the wearer's mouth and nose;
An outer blocking film 30 disposed on the outer surface of the filter film, the lower end and the side edge being coupled to the filter film, and spaced apart from the filter film to form an inner space 40 on the inside;
Consists of including; a fixing strap 50 for fixing the filter membrane to be in close contact with the wearer's face,
The external blocking film 30 is a surgical mask, characterized in that formed of a film that blocks gas flow. delete The method of claim 1,
A surgical mask, characterized in that a pair of seating grooves (31) in which a magnifying glass is seated are formed on an upper portion of the outer blocking film (30). The method of claim 1,
A surgical mask, characterized in that a lateral flow blade 32 that is multi-folded outward is further formed on the outer blocking film 30. The method of claim 4,
The lateral flow blade 32 is a surgical mask, characterized in that the incision 323 is formed along the central line to be opened or folded around the incision. The method of claim 5,
The incision 323 is characterized in that the elastic band 33 is attached to cover the gap, or an upper blocking film 34 is attached to cover the upper part of the gap to prevent harmful gas from moving upward through the incision. Surgical mask. The method of claim 4,
The lateral flow blade 32 is formed of a first-stage horizontal portion 321, which is a surface folded outward from the outer blocking film, and a two-stage vertical portion 322, which is folded downward from the first-stage horizontal portion,
The first-stage horizontal part 321 is configured to have a central point as a low point and an upward slope to both sides, so that the central gas is pushed to both sides and moves upward. The method of claim 1,
The outer barrier layer 30 forms a V-shaped side guiding crease 35 having a center as a low point and an upward slope to both sides, the side guiding crease formed as one or a plurality of creases along the outer surface of the outer barrier layer. Surgical mask, characterized in that the rising gas flow is moved upward from the center to the left and right sides. The method of claim 8,
The side induction wrinkle 35 is a surgical mask, characterized in that the outer surface exposed to the outside has a U-shaped or V-shaped groove that is opened downward to confine the rising gas in the groove to move to the side. The method of claim 1,
A sealing film 70 is disposed horizontally at an inner or outer upper end of the filter film 20, and only the upper end of the sealing film is attached to the filter film. A surgical mask, characterized in that the sealing or blocking of movement to a region adjacent to the filter membrane is made. The method of claim 1,
A surgical mask, characterized in that the lower portion of the filter film and the outer blocking film is further formed with a "b" shape bent or gently curved chin rest in a certain section.

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