FR2740689A1 - EYEPIECE FOR A RESPIRATORY PROTECTION MASK, MASK PROVIDED WITH THE EYEPIECE AND HELMET AND SCAPHANDRE PROVIDED WITH THE MASK - Google Patents

Abstract

The invention relates to an eyepiece (1) for a respiratory protective mask (2), comprising a transparent curved wall (9) bounded by a curved outer edge (4) and provided with an opening (11) with which is intended to cooperate a snout, relative to the mask (2) provided with the eyepiece (1) being in the position corresponding to a carrier having the right head and the horizontal axis of vision (S), the eyepiece (1) comprises an upper part (13) forming the usual binocular field of the wearer and whose shape called sphero-conical is generated by the displacement of an arc of a circle (C) rotating, on a given sector, around an axis of revolution (16) located in the vertical plane of symmetry of the wearer's head, inclined to the horizontal and the vertical and passing substantially in or near the middle area of the wearer's brain (R) and the area of the lips.

Description

The invention relates to an eyepiece for a protective mask

  respiratory mask, such a mask provided with such an eyepiece, as well as a protective helmet and a

  spacesuit comprising such a mask.

  The respiratory protection mask considered is according to a typical application intended for firefighters. Such

  mask can also be used in industry.

  Document EP-A-600 258 describes an eyepiece in which, first of all, the curvature at the level of the azimuthal section planes decreases continuously from the axis of meridian symmetry towards the edge of the eyepiece. Second, the azimuthal curvature on the axis of symmetry

  meridian decreases as one moves away from the snout area.

  Third, the meridian curvature is significantly

  uniform along the meridian axis of symmetry.

  According to this document, the eyepiece is characterized by its curvature and more precisely its relative curvature (respectively the variation or the constancy of the curvature) considered in an azimuthal and meridian manner.

  along the axis of symmetry of the eyepiece.

  According to this document, these curvature characteristics aim to provide a field of vision without practically

no visual distortion.

  EP-A-600 258 does not define the eyepiece

  otherwise than by its curvature or relative curvature.

  However, the shape of the eyepiece according to this document is such that when the mask rests, for whatever reason, on the eyepiece, the latter can be damaged

  especially scratched, since it is prominent.

  Furthermore, this document does not mention an eyepiece arrangement intended to correct the optical deformations resulting from the curved shape of the wall which constitutes it. Document US Pat. No. 5,297,544 also describes a respiratory protection mask in which the eyepiece has a meridian section of rectilinear symmetry, which

  provides significant distortions outside this area.

  In addition, the field of vision is narrow.

  The document EP-A-511 593 describes a respiratory protection mask, the eyepiece of which has a substantially toroidal shape. This eyepiece is strongly domed, and does not correct the optical deformations resulting from its curved shape. Such an eyepiece can be

scratch easily.

  The invention therefore aims to remedy these drawbacks and, simultaneously, to give the eyepiece a wide field of vision both laterally and downwards, and to allow in particular quality manufacturing of its production tools, which makes it possible to '' get an eyepiece

High quality.

  To this end and according to a first aspect, the invention relates to an eyepiece intended for a respiratory protective mask, comprising a curved transparent wall bounded by a curved outer edge and provided with a

  opening with which is intended to cooperate a snout.

  Compared to the mask provided with the eyepiece being in the position corresponding to a wearer having the right head and the horizontal viewing axis, the eyepiece has an upper part forming the usual binocular field of the wearer and whose shape is called sphero -conical is generated by the displacement of a rotating arc of circle, on a given sector, around an axis of revolution located in the vertical plane of symmetry of the wearer's head, inclined on the horizontal and the vertical and passing substantially in or near the middle zone of the

  wearer's brain and lip area.

  According to other non-limiting characteristics of the eyepiece: - The axis of revolution makes an angle with the horizontal of between 33 and 53, more particularly between

  38 and 48 and more especially equal to or close to 43.

  The eyepiece is limited, downwards, by the plane of the snout which makes an angle with the horizontal of the order of 45; - The upper part forms a binocular field having a vertical opening angle relative to the horizontal vision axis of the wearer of between 80 and 100, more particularly between 85 and 95, and more

  specially equal to or close to 90.

  - The upper part forms a binocular field located partly above, partly below

  the wearer's horizontal line of vision, the part above

  above and the part below having equal, similar or similar vertical opening angles. - The radius of curvature of the circular arc defining by its revolution around the axis of revolution the upper part of the eyepiece is between 570 and 700 mm, more particularly between 600 and 665 mm and more

  especially of the order of 632 to 636 mm.

  - The distance between the axis of revolution and the outer edge at the upper end of the eyepiece is between 40 and 120 mm, more particularly between 80

  and 100 mm, and more particularly of the order of 85 mm.

  - The distance between the axis of revolution and the outer edge at the lower front end of the eyepiece is between 20 and 40 mm, more particularly between 34.5

  and 38.5 mm and more especially of the order of 37 mm.

  - The length of the transparent wall in the upper part and in the meridian plane of symmetry is between 110 and 190 mm, more particularly between

  and 160 mm and more especially of the order of 147 mm.

  - The length of the transparent wall in the widest upper zone of the upper part and in an azimuth plane is less than 300 mm, in particular between 200 and 250 mm, more particularly between 220 and

  240 mm and more especially equal to or close to 230 mm.

  - The sector on which the upper part extends has an opening greater than 180 and of the order

of 210.

  - The upper part of the eyepiece extends, in the middle meridian zone up to or near the peripheral edge outside

free lower.

  - The upper part of the eyepiece extends, in the lateral meridian zones so as to be separated

  from the outer peripheral edge to the lower end.

  - The eyepiece also has a lower part extending the upper part down continuously, without breaking, said lower part having the shape of a left surface. This left surface is wholly or partly sphero-conical or not. She is not

  not, in any event, necessarily sphero-conical.

  - The lower left part extends mainly in the lateral meridian zones, on either side of the downward extension of the upper part in the median meridian zone. The lower part has a shape defined, in an azimuthal section plane, by a contour comprising two lateral sections of straight or substantially straight lines coming to be connected forwards to the downward extension of the upper part in the median meridian zone and backwards to a circular or substantially circular sector. The two sections of straight or substantially straight lines are connected to the downward extension of the upper part in the middle zone

  meridian tangent or substantially tangent.

  - The combination of the upper sphero-

  taper and the lower left part has the function of defining an overall shape of the eyepiece having simultaneously the effects of allowing machine polishing of the production tools of the eyepiece, of offering excellent optical qualities, of maximizing the field of vision including downward, to allow the eyepiece to be placed close to the wearer's face, and to avoid scratches

  of the eyepiece by a plane on which it could rest.

  - Thanks to this combination, the size of the eyepiece is easily defined so as to fit into a predetermined size, such as that of the opening

a helmet.

  - The eyepiece comprises on the one hand on its outer edge a flange, forming an integral part of it, directed towards the outside, allowing the mounting of a skirt connecting the eyepiece with the face of the wearer, and on the other hand, a shoulder around its opening of

snout reception.

  - According to one characteristic, the collar has an intersection with the upper part of the eyepiece and possibly a lower part, which is substantially extended along a left line included in the envelope

  of a circular section cylinder.

  - On all or substantially all of its surface, and at least in the usual binocular field of the wearer, the wall of the eyepiece is located on the same side and spaced-even slightly- from a plane passing through the outer edges of

the collar and the shoulder.

  - At least in its upper part and at least in the usual binocular field of the wearer, the external and / or internal surfaces of the wall are defined to satisfy at least in part, the optical law of Descartes, the thickness of the wall of the eyepiece being variable and between 1.5 and 4 mm, more particularly equal or of the order of 3 mm, the variation in thickness being equal or of the order of 1.5 mm. Thus, the wall of the eyepiece is thicker in its lower region than in its upper region and thicker in its central region than

in its side areas.

  - According to one characteristic, the upper part, and possibly a lower part of the eyepiece, comprises several and for example four zones of different quality or optical class, the thickness of the eyepiece being calculated within at least one of these zones to respond to Descartes' law according to parameters

  clean, such as astigmatic power.

  - In one example, the eyepiece includes a zone located in the upper part symmetrically extended on either side of a meridian plane of symmetry of the eyepiece on an angular opening greater than 170 for example of the order of 180 , the thickness of the eyepiece in this area being calculated so that the power

  astigmatic is between 0 and 0.06 diopters.

  - According to one embodiment, the upper part, and possibly a lower part of the eyepiece, comprises a plurality of zones, slices, discrete meshes which constitute it or them jointly, the thickness being calculated separately within these zones, slices or meshes, by determination of the distance between an internal surface part and an external surface part, for example initially defined for all of the zones, sections, or meshes; an overall bonding surface, approximately coincident with the discrete parts determined for the calculation of the thicknesses being

  defined to obtain the shape of the eyepiece.

  - The eyepiece comprises, with regard to its sphero-conical upper part, two axes of revolution corresponding respectively to the outer surface and to the inner surface. The first is closer to the vertical than the second; the two axes form, between them, an angle less than 0.5 and in particular of the order of a tenth to a twentieth of a degree, in particular equal or

close to 0.1530.

  - The intersection of these two axes is located substantially in a horizontal plane, relative to an eyepiece carrier having the right head and the horizontal viewing axis, where the center of the arc of

  rotating circle defining the upper sphero-

  conical. - The eyepiece comprises, with regard to its sphero-conical upper part, two centers corresponding respectively to the arcs of a circle defining the outer and inner surfaces. The first center is closer to the eyepiece than the second, the spacing between the two being between 1 and 3 mm and in particular equal to or of the order of 2 mm. The two centers of the arcs of a circle are, in a first alternative embodiment, located in the horizontal plane passing through the intersection of the two axes of revolution, previously mentioned. In a second variant embodiment, the two centers are aligned on the common radius of the two arcs of circle meeting the axis

  vision of the wearer at the location of the eyepiece wall.

  - The radius of curvature of the arc of a circle corresponding to the external surface of the sphero-conical upper part is slightly larger than that corresponding to the internal surface, the difference between them being between 1 and 1.4 mm, in particular equal

or close to 1.2 mm.

  According to a second aspect, the invention relates to a respiratory mask comprising an eyepiece as just described, a skirt for connecting the eyepiece with an inner mask on the wearer's face, and

respiratory means.

  According to a third aspect, the invention relates to a protective helmet comprising a mask as it comes

to be described.

  According to a fourth aspect, the invention relates to a protective suit comprising an eyepiece such that it has

was previously described.

  The invention is not limited to these aspects and will be

  better understood on reading the detailed description which

  follows, and which refers to the attached drawings.

  Figure 1 is a schematic sectional view through a vertical azimuthal median plane of a respiratory mask comprising an eyepiece according to the invention, this being shown in normal situation on the head of a wearer

  having the right head and the horizontal axis of vision.

  Figure 2 is a front view of the eyepiece

  in the general direction of arrow F in FIG. 1.

  Figure 3 is a sectional view along line III-III of Figure 2, which line corresponds to the plane

  azimuthal median vertical in Figure 1.

  Figure 4 is a top view of the eyepiece

  in the general direction of arrow T in Figure 1.

  Figure 5 is a view similar to that of Figure 3 showing the eyepiece in the position of Figure 1, axes, centers, arcs, planes, etc. competing in its definition in the case of a first embodiment of the corrections relating to Descartes' law. Figure 6 is a schematic sectional view through an azimuthal plane showing the different constitutive sphero-conical and left bearing surfaces of the

eyepiece wall.

  Figure 7 is a schematic view through a vertical median plane in the case of a second alternative embodiment of the corrections relating to the law of Descartes. Figure 8 is a schematic perspective view from above of an eyepiece according to the invention, which represents

  the different optical class areas of this eyepiece.

  The eyepiece 1 shown in the drawings is specially adapted and intended for a protective mask

respiratory 2.

  Such a mask 2 is, according to a typical application,

intended for firefighters.

  The mask 2 also comprises a skirt 3 of generally annular shape intended to be placed around the eyepiece 1, towards the outside, by being rigidly connected to it. The eyepiece 1 includes, for this purpose, on its large free peripheral outer edge 4, a flange 5 forming an integral part of it, directed towards the outside of the eyepiece 1 and on which the free edge of the skirt 3 is folded , the assembly being made rigid by an attached U-shaped tightening joint 6. The skirt 3 provides the connection between the eyepiece 1 and the face V of a wearer R. The mask 2 also includes an inner mask

  7 as well as respiratory means 8.

  Such a mask 2 can be integrated into a helmet 2a

  or a spacesuit 2b of which it then forms an integral part.

  The eyepiece 1 essentially comprises a one-piece transparent wall 9 shaped so as to fulfill the various functions of the eyepiece. The wall 9 is shaped by being curved with an overall concavity turned towards the face V of the wearer R, that is to say inside the eyepiece 1, while the convexity is turned towards the outside. The eyepiece 1, that is to say the transparent wall 9, is made in particular of polycarbonate. In the embodiment shown in the drawings, the wall 9 has a thickness

equal to or about 3 mm.

  The wall 9 is curved and limited by the edge 4, which defines a first large rear opening 10 intended to be placed opposite and in the vicinity of the face V. Furthermore, the wall 9 comprises a second small lower opening 11 with which is intended to cooperate a snout forming part of the respiratory means 8. The wall 9 forms around the opening 11 an annular shoulder 12, plane, intended to position the

snout 8.

  The eyepiece 1 is therefore limited, downwards, by a plane P (Figures 3, 4, 5, 7) which - compared to a carrier R having the right head and a horizontal axis of vision S - made with l 'horizontal an angle J (Figures 5 and 7) of the order of 45. This plan P includes the opening 11

and shoulder 12.

  The qualifiers "rear" and "lower" are

  refer, like the whole description, to an eyepiece 1

  carried, thanks to the mask 2, by a carrier R having the right head (i.e. vertical up-down axis Z) and the axis of

vision S horizontal.

12 2740689

  Such a situation or position is subsequently called a "reference" for the sole convenience of

description.

  It is understood, however, that the wearer, in current use of the eyepiece 1, lifts or lowers the head and / or lifts or lowers the eyes or even turns them

  laterally on one side or the other.

  Therefore, for the convenience of the

  description, eyepiece 1 is defined in relation to the

  reference situation or position. However, this position is only relative, the eyepiece 1 can occupy any other position, whether in use or not in use (storage, storage, etc.). The collar 5 delimits the opening 10 which, at least in part, is planar or substantially planar in particular towards the bottom of the eyepiece 1. Here, a planar part is notably situated in a vertical plane or close to vertical when the eyepiece is in normal reference situation, as in FIG. 5 or 7. Towards its upper part, the flange 5 is curved downwards,

back and forth (Figure 3).

  We will return later to the shape of the collar 5, as well as to an advantageous manner of the

determine.

  Apart from the flange 5 and the shoulder 12, the wall 9 has an upper part 13 forming the usual binocular field of vision of the wearer and a lower part 14 extending the upper part down continuously, that is to say without breaking. However, this constructive characteristic does not exclude the presence between the parts 13 and 14 of a relief such as a hollow as it is visible in FIG. 3 or even an inflection. There is shown in Figure 3, a line 15

  separating the two upper 13 and lower 14 parts.

  It is understood, however, that this line is purely fictitious, no materialized line existing between the

parts 13 and 14.

  The upper part 13 is the so-called sphero-shaped

  conical and generated by the displacement of an arc of a circle C (Figure 1) rotating, on a given sector, around an axis of revolution 16 located in the vertical plane of symmetry III-III of the head of the carrier R, inclined horizontally and vertically and passing substantially in or near the mid-region of the wearer's brain R

and the lip area.

  The axis 16 is inclined from front to back and from bottom to top relative to the head of the carrier R in a situation of

reference.

  In the embodiment shown in Figure 1, the axis 16 makes with the horizontal an angle equal or close

of 43.

  The upper part 13 forms a binocular field having a vertical opening angle B (FIG. 3) relative to the axis S of horizontal vision of the carrier R, equal to or close to 90. This field is partly located above this line of sight S and partly below. In particular, in the embodiment shown in the figure

  3, the opening angles of the upper part 13 au-

  above and below the horizontal to the S axis are equal, neighboring or of the same order of magnitude. The radius of curvature of the arc of a circle C is, in the embodiment shown in FIGS. 5 and 7, of

in the range of 632 to 636 mm.

  In the embodiment shown in Figures 3 and 5, the radius of curvature is different for the arc of circle CE defining the outer face of the part

  upper 13 and the arc CI defining the internal face.

  Here, the radius of curvature AE of the external axis CE is 634.5 mm, while the radius AI of the internal axis CI

is 633.3 mm.

  The spacing BS between the axis 16 and the edge 4 is of the order of 92 mm at the upper end 17 of the eyepiece 1 and the spacing BI is 36 mm at the lower end 18. The length of wall 9 in part 13 and in the meridian plane of symmetry III-III is equal or close

from 130 to 160 mm.

  In the embodiment shown in FIG. 2, the length L of the wall 9 in the upper zone 13 widest from the upper part 13 and in an azimuth plane

is equal or close to 230 mm.

  In FIG. 6, the sector over which the

  upper part 13 has an opening M greater than 1800.

  Consequently, in this embodiment, the collar 5 is at least partly located substantially in a plane N (FIG. 5) close to the vertical, but slightly inclined from front to back and from top to bottom, by an angle e

around 5.

  Let's go back to the form and how to obtain

eyepiece 1.

  Generally an eyepiece 1 provided with a collar directed towards the outside, is a difficult part, of complex shape, to be produced by injection, and in

particular to unmold.

  One aspect of the invention is a design and manufacturing process, and the resulting eyepiece, which solves the above injection and molding problems. A first general definition of the shapes and dimensions of the eyepiece 1 is made, according to the functionalities which it must fulfill. In particular, the eyepiece 1 is defined according to mechanical specifications,

  optics, external dimensions and ergonomics.

  On this basis, we then look for a cylinder in the envelope of which the outline of the shape defined above is inscribed. The intersection between the defined form of

  eyepiece 1 and the cylinder is a left line.

  For example, the axis of the cylinder is in the meridian plane of symmetry of the eyepiece, where it is perpendicular to it. And a collar 5 is determined which corresponds to this left line common to the cylinder and to the defined shape of the eyepiece 1. Specifically, it is the concave edge of the collar 5 with the parts 13 and 14 which here belongs to the cylinder. Thus, it is ensured that the part comprising the eyepiece 1 and the flange can be removed from the mold, along the axis of the cylinder. It goes without saying that, in order to find an acceptable intersection, the shape defined first for eyepiece 1 and / or, on subsequent approach, the cylinder can be

  modified or reduced to an acceptable approximation.

  Note also that the cylinder has a straight generator and is parallel to its axis. And that although it is in reality a volume, for example with a wall thickness of the order of 3 mm, just as the intersection is a surface

  linear, we consider it here as an envelope.

  In FIG. 3, the upper part 13 extends, in the middle meridian zone up to the proximity of the free edge 4 at the end 18 of the eyepiece 1, while in its lateral meridian zones 20, it is spaced apart. The lower part 14 therefore extends upwards, downwards essentially in the lateral meridian zones, on either side of the downward extension of the

  upper part 13 in the middle meridian zone 21.

  The lower part 14 has a surface shape

  left which, in whole or in part is sphero-conical or not.

  In the embodiment shown in the drawings, the lower part 14 has a defined shape, in an azimuthal section plane corresponding to FIG. 6, by a contour comprising two lateral sections of straight lines or

substantially straight 22.

  These sections 22 are connected forwards to the downward extension of the upper part 13 in the middle meridian zone 21 and rearwards to a

  circular or substantially circular sector 23.

  More precisely, the two sections 22 are connected to the downward extension of the upper part 13 in the middle meridian zone 21 so

tangent or substantially tangent.

  We see in Figure 7 that in the eyepiece 1, the wall 9 on all or substantially all of its surface and at least in the upper part 13 as well as in the usual binocular field of the wearer at least, is located on the same side and moved away - even slightly - from a plane D passing through the respective outer edges 5a, 12a of the collar 5

and shoulder 12.

  This constructive arrangement is provided so that when the eyepiece 1 rests on a plane such as a shelf, it is in contact only by the projecting outer edges of the flange 5 and the shoulder 12. It follows that we avoid scratching the outer surface 24 of the wall 9

eyepiece 1.

  It is the same when the eyepiece 1 comes into contact with any flat surface. The optical qualities of the eyepiece are thus preserved throughout the eyepiece. In order to satisfy, at least partially in its upper part 13 and in the usual binocular field of the wearer under Descartes' law, the outer 24 and inner 25 surfaces of the wall 9 are defined specifically, the thickness of the wall 9 of eyepiece 1

being variable.

  The variation in thickness in the illustrated embodiment is equal to or of the order of 1.5 mm. The wall 9 is thicker in its lower region than in its upper region. And compared to the central zone 21 of the eyepiece 1, the thickness is less important in its lateral zones 20. For example, the thickness is between 1.5 and

4 mm.

  We will now describe more specifically the methods according to which the wall 9 of FIG. 5 - and in particular its outer surface 24 and its inner surface 25 - meets Descartes' law at least in the upper part 13 and for the binocular field of vision.

of the wearer.

  The wall 9 comprises, with regard to the upper part 13, two axes of revolution 16a, 16b and two centers 25a, 25b corresponding respectively to the surfaces

exterior 24 and interior 25.

  The axis of revolution 16a is closer to the vertical than the axis of revolution 16b, the two axes of revolution 15a, 15b forming between them an angle 6 equal or

close to 0.1530.

  The intersection 26 of the two axes of revolution 16a, 16b lies substantially in a horizontal plane E, or in the vicinity of which is the center of the arc of a circle C

  turning defining the upper part 13 sphero-

conical. In the case of FIG. 5, the two centers 25a, b of the arcs CE, CI are at

  proximity or on the E plane. The preceding constructive arrangements allow especially, in combination with those which follow, to optimize the relative arrangement of the two

  surfaces 24, 25 in the azimuthal planes.

  With regard to optimization in the meridian planes, the two centers 25a, 25b of the arcs of circle CE and CI are spaced apart, their spacing F (FIG. 5) being equal to or of the order of 2 mm. The center 25a of the circular arc CE corresponding to the external surface 24 is closer to the wall 9 than the center 25b of the circular arc CI corresponding to the internal surface 24b, in the direction of the rays AI and AE in the plane E. We have seen that in a first alternative embodiment corresponding to the case of FIG. 5, the two centers 25a, 25b of the arcs of circle CE and CI are located in the horizontal plane E passing through the intersection 26 of the

two axes of revolution 16a, 16b.

  According to a second alternative embodiment represented by the diagram in FIG. 7, the two centers a, 25b are aligned on a common radius A of the two arcs of circle CE and CI meeting, at the location of the wall 9, the axis vision of the wearer. The radius of curvature A of the arc of a circle CE corresponding to the external surface 24 is therefore slightly larger than the radius of curvature A of the arc of a circle CI corresponding to the internal surface 25. The difference G between the two radii of curvature AE, AI is equal to or close to 1.2 mm, in the embodiment shown in FIG. 7. In this embodiment, the radius of

  AI curvature is equal to or close to 633.3 mm.

  In this embodiment and the first variant concerning optical optimization in the meridian planes, the spacing HE, HI respectively between the intersection 26 of the axes of revolution 16a, 16b and the centers 25a, 25b is equal to or close to 771.8 mm for the outer surface 24,

  and 773.8 mm for the interior surface 25.

  a) According to an example, for the thickness value (t) to satisfy Descartes' law, it is determined as a function of the optical power or

  astigmatic of the eyepiece in the usual binocular field.

  The goal is to minimize this power.

  As a general rule, in order to meet a given optical class or quality, the astigmnatic power must not exceed the power inherent in the curvature and the required thickness by a diopter value which corresponds to this class. This diopter value is defined for an angular opening in a meridian plane parallel to the axis of vision S. An equation for calculating the inherent power of the eyepiece in the usual binocular field is: F = (F1 + F2) - (t / n.F1.F2); such that F1 = (n-1) / AI and F2 = (1-n) / AE, where F: is the inherent power in diopters; Fi: is the power at the surface 25 in diopters; F2: is the power at the surface 24 in diopters; n: is the refractive index of the eyepiece material (example: Polycarbonate = 1.586); t: is the thickness in m; AI: is the radius of curvature of the surface 25, in m; and? AE: is the radius of curvature of the surface 24, in

m.

  b) By applying in particular this calculation to the example of an eyepiece 1 illustrated, it is noted that in order to obtain an optical class of high quality over the entire angular opening of the part 13 in a plane parallel to the axis S, l the thickness "t" of the eyepiece 1 is markedly reduced to

near the flange 5.

  In order to meet the requirements of mechanical strength, provision is made according to the invention to divide the

  parts 13 and 14 in several zones.

  The aim being, by giving each zone a chosen optical class, to obtain a compromise between the resistance

mechanical and optical quality.

  An example of division into zones of eyepiece 1,

is illustrated in figure 8.

  c) Here, parts 13 and 14 are divided into

  four (4) zones (27, 28, 29 and 30) of different classes.

  The area 27 is extended over an opening distributed equally on either side of the meridian plane of symmetry comprising the axis 16, over an angle K between 170 and. Zone 27 is extended to the upper edge 17, where it is separated from the lower edge 18 by a portion

across areas 28 and 30.

  Zone 28 is as illustrated, generally in the shape of a "U" and surrounds zone 27, except at its part

  upper contiguous to the collar 5.

  The zone 29 comprises two separate parts, which are each extended substantially along the axis 16, on either side of the zones 27, 28. Each part of the zone 29 is extended between the flange 5 and a lateral limit

outside of zone 28.

  Zone 30 is made up of all parts of

  eyepiece 1 not included in zones 27 to 29.

  d) Here, the values of diopters allocated are: - between 0 and 0.06 for the area 27, which is said to be of "optical" class, that is to say of high quality; - between 0.06 and 0.12 for zone 28; - between 0.12 and 0.25 for zone 29, and

  - greater than 0.25 for zone 30.

  Thanks to this arrangement, the visibility through the eyepiece 1 is particularly good in the usual binocular fields and the mechanical strength of

eyepiece 1 is high.

  In practice, for a given optical class, thickness variations are provided according to the angle B

(figure 3).

  In absolute terms, the surface 25 therefore does not have an arc strictly as a generator but a curved line

  complex, nevertheless comparable to a curve.

  The shape of the surface 25 is for example

  determined as follows, referring to Figure 2.

  e) The first step in this determination

  consists in dividing the eyepiece 1 into "slices" 31 (a-f).

  The term "slice" is understood to mean a division of the eyepiece 1 defined here by two planes perpendicular to the direction Z and therefore parallel to the axis S, one upper, the other lower. The lower and upper limit planes are spaced from each other by a chosen distance, for example 10 mm in the direction Z. In FIG. 2, the edge 31 is only delimited by a lower plane 32a, the flange 5 in

  the lower end 17 replacing the lower plane.

  When, as in FIG. 8, the eyepiece 1 is divided into zones, the sections 31 (a-f) are limited to the opening (for example, the angle K) of the zone (27) o

they are formed.

  Similarly, from an initially defined shape, with a pitch of the order of 1 to 10 mm for example, is applicable to the eyepiece 1 to reduce it to a juxtaposition of simple meshes, inside each of which are defined optical and mechanical conditions to be respected, by varying the thickness "t" in each mesh; f) The second step consists in defining for each section 31, the corresponding ideal thickness "t" of

* eyepiece 1, to meet the chosen optical class.

  In the example, the thickness variations "t" are obtained without modification of the external surface 24. It is therefore by varying with respect to the external surface 24, the distance from the internal surface 25 inside of a

  section 21, what is obtained the variation in thickness "t".

  Thus, for surface 25, a juxtaposition of discrete surfaces is obtained, each of which corresponds

to a tranche 31.

  The third step is to "smooth" the juxtaposition of discrete surfaces of

  slices 31, to obtain a continuous surface 25.

  This smoothing consists in finding, by an approximation acceptable from a mechanical and optical point of view, a bonding surface of the discrete surfaces of the wafers 31. This bonding surface, that is to say the surface 25, is a "smooth" surface. "with curved generator

similar to an arc.

  Note that the eyepiece 1 once produced, for example by molding the shape defined above, is in some cases subjected to a hardening and / or anti-scratch treatment. In addition, a gold plating is in some embodiments applied to the surface 24, in order to increase

  the fireproofing and thermal insulation qualities.

  g) Then, the layer of gold or the like is to be taken into account for the calculation of the optical class of the eyepiece

  1 or of the parts / zones which constitute it.

Claims (48)

  1. Eyepiece (1) intended for a respiratory protection mask (2), comprising a transparent curved wall (9) bounded by a curved outer edge (4) and provided with an opening (11) with which is intended to cooperate snout, characterized in that with respect to the mask (2) provided with the eyepiece (1) being in the position corresponding to a wearer having the right head and the horizontal viewing axis, the eyepiece (1) comprises an upper part (13) forming the usual binocular field of the wearer and whose so-called sphero-conical shape is generated by the displacement of an arc of a circle (C) rotating, over a given sector, around an axis of revolution ( 16) located in the vertical plane of symmetry (III-III) of the wearer's head, inclined to the horizontal and the vertical and passing substantially in or near the median area of the wearer's brain (R) and the area lips.   2. Eyepiece (1) according to claim 1, characterized in that the axis of revolution (16) makes with the horizontal an angle (a) between 33 and 53, more particularly between 38 and 48 and more especially equal or close to 430.   3. Eyepiece (1) according to claim 1 or 2, characterized in that the upper part (13) forms a binocular field having an angle (B) of vertical opening relative to the axis (S) of horizontal vision of the carrier (R), between 80 and 100, more particularly between     and 95, and more especially equal to or close to 90.   4. Eyepiece (1) according to any one of   claims 1 to 3, characterized in that the part   upper (13) forms a binocular field located partly above, partly below the axis (S) of horizontal vision of the wearer (R), the part situated above and the part situated below having equal, similar, or similar vertical opening angles. 5. Eyepiece (1) according to any one of   Claims 1 to 4, characterized in that the radius (AI,   AE) of curvature of the arc of a circle (C) defining by its revolution around the axis of revolution (16) the upper part (13) is between 570 and 700 mm, more particularly between 600 and 665 mm and more specially on the order of 632 to 636 mm.   6. Eyepiece (1) according to any one of   Claims 1 to 5, characterized in that the spacing   (Bs) between the axis of revolution (16) and the outer edge (4) at the upper end (17) of the eyepiece (1) is between 40 and 120 mm, more particularly between   mm and 100 mm, and more particularly of the order of 85 mm.   7. Eyepiece (1) according to one of claims 1 to   6, characterized in that the spacing (BI) between the axis of revolution (16) and the outer edge (4) at the front lower end (18) is between 20 and 40 mm, more particularly between 34 , 5 mm and 38.5 mm and more especially of the order of 37 mm.   8. Eyepiece (1) according to one of claims 1 to   6, characterized in that the length of the transparent wall (9) in the upper part (13) and in the meridian plane of symmetry is between 110 and 190 mm,   more particularly between 130 and 160 mm and 147 mm.   9. Eyepiece (1) according to one of claims 1 to   8, characterized in that the length (L) of the transparent wall (9) in the widest upper region (19) of the upper part (13) and in an azimuth plane is less than 300 mm, in particular between 200 mm and 250 mm, more particularly between 220 mm and 240 mm and   more especially equal to or close to 230 mm.   10. Eyepiece (1) according to claim 1 to 9, characterized in that the sector (M) over which the upper part extends (13) has an opening greater than 180 and of the order of 210 mm.   11. Eyepiece (1) according to one of claims 1 to   , characterized in that the upper part (13) extends, in the middle meridian zone (21) up to or near the outer peripheral edge (4) at the lower end (18).   12. Eyepiece (1) according to claim 1 to 11, characterized in that the upper part (13) extends, in the lateral meridian zones (20) so as to be spaced from the outer peripheral edge (4) to the end lower (18).   13. Eyepiece (1) according to one of claims 1 to   12, characterized in that it also comprises a lower part (14) extending the upper part (13) down continuously without breaking, said lower part (14) having the shape of a left surface not necessarily sphero-conical.   14. Eyepiece (1) according to claim 13, characterized in that the lower part (14) extends essentially in the lateral meridian zones (20), on either side of the downward extension of the part   superior (13) in the middle meridian zone (21).   15. Eyepiece (1) according to claim 13 or 14, characterized in that the lower part (14) has a defined shape, in an azimuthal cutting plane, by a contour comprising two lateral sections of straight or substantially straight lines (22 ) coming to be connected forwards to the downward extension of the upper part (13) in the middle meridian zone (21) and backwards to a   circular or substantially circular sector (23).   16. Eyepiece (1) according to claim 15, characterized in that the two lateral sections of straight or substantially straight lines (22) are connected to the downward extension of the upper part (13) in the median meridian zone (21 ) tangentially or substantially tangent.   17. Eyepiece (1) according to one of claims 1 to   16, characterized in that the combination of the upper part (13) and the lower part (14) has the function of defining an overall shape of the eyepiece (1) having the simultaneous effects of allowing machine polishing of the production tools, to offer excellent optical qualities, to maximize the field of vision including downward, to allow the eyepiece (1) to be placed close to the wearer's face (R), and d '' avoid scratching the eyepiece (1) by a plane (D) on which it could rest.   18. Eyepiece (1) according to one of claims 1 to   17, characterized in that it comprises on its outer edge a collar (5), forming an integral part of it, directed towards the outside, allowing the mounting of a skirt (3) for connecting the eyepiece (1) with the face of carrier (R).   19. Eyepiece (1) according to claim 1, characterized in that the collar (5) has an intersection with the upper part (13) of the eyepiece and possibly a lower part (14), which is substantially extended along a line left included in   the envelope of a circular section cylinder.   20. Eyepiece (1) according to one of claims 1 to   19, characterized in that it has a shoulder (12)   around its opening (11) for receiving the snout.   21. Eyepiece (1) according to claims 18 to 20,   characterized in that at least in the usual binocular field of the wearer, the wall (9) is located on the same side and spaced-even slightly- from a plane (D) passing through external edges (5a, 12a) of the collar (5) and of the shoulder (12), respectively.   22. Eyepiece (1) according to claim 21, characterized in that over all or substantially all of its surface, the wall (9) is located on the same side and spaced-even slightly- from a plane passing through the outer edges (5a, 12a) of the collar (5) and of the shoulder (12). 31 2740689   23. Eyepiece (1) according to one of claims 1 to   22, characterized in that at least in its upper part (13) and at least in the usual binocular field of the wearer, the external (24) and / or internal (25) surfaces of the wall (9) are defined to satisfy at least for part, the law of Descartes.   24. Eyepiece (1) according to one of claims 1 to   23, characterized in that the thickness of the wall (9) is between 1.5 and 4 mm, more particularly is equal or of the order of 3 mm.   25. Eyepiece (1) according to claim 23, characterized in that the thickness of the eyepiece (1) is variable in order to satisfy, at least in part, the law by Descartes.   26. Eyepiece (1) according to claim 25, characterized in that the variation in thickness of the wall   (9) is equal to or about 1.5 mm.   27. Eyepiece (1) according to claim 23, characterized in that its upper part (13), and possibly a lower part (14) comprises several and for example four zones (27; 28; 29; 30) of quality or class different optics, the thickness (t) of the eyepiece (1) being calculated within at least one of these zones (27; 28; 29; 30) in order to respond to Descartes' law as a function of proper parameters, such as astigmatic power.   28. Eyepiece (1) according to claim 27, characterized in that it comprises a zone (27) located in the upper part (13) extended symmetrically on either side of a meridian plane of symmetry of the eyepiece on an angular opening (K) greater than 170 and for example of the order of 180, the thickness (t) of the eyepiece (1) in this zone (27) being calculated so that the astigmatic power is between 0 and 0.06 diopters.   29. Eyepiece (1) according to claim 23, characterized in that its upper part (13), and possibly a lower part (14), comprises a plurality of zones (27; 28; 29; 30), edges (31) or discrete meshes which constitute it or them jointly, the thickness (t) being calculated separately within these zones (27; 28; 29; 30), sections (31) or meshes, by determining the distance between a part of internal surface (24) and a part of external surface (25) for example initially defined for the whole of the zones (27 28; 29; 30), sections (31) or meshes; an overall connecting surface (24), approximately coincident with the discrete parts determined for the calculation of the thicknesses (t) being defined to obtain the shape of the eyepiece (1).   30. Eyepiece (1) according to one of claims 25   or 26, characterized in that the wall (9) is thicker   in its lower zone than in its high zone.   31. Eyepiece (1) according to any one of   Claims 25 to 30, characterized in that the wall (9)   is thicker in its middle zone (21) than in its lateral zones (20).   32. Eyepiece (1) according to any one of   claims 1 to 31, characterized in that it comprises,   with regard to the sphero-conical upper part, two axes of revolution (16a, 16b) corresponding respectively to the outer surface (24) and the inner surface (25). 33. Eyepiece (1) according to claim 32, characterized in that the axis of revolution (16a) corresponding to the external surface (24) is closer to the vertical than the axis of revolution (16b) corresponding to the interior surface (25).   34. Eyepiece (1) according to any one of claims 32 or 33, characterized in that the two axes of revolution (16a, 16b) form, between them, an angle (6) less than 0.5 and in particular of l order from tenth to twentieth of a degree, in particular equal to or close to 0.153.   35. Eyepiece (1) according to any one of claims 32 to 34, characterized in that the intersection (26) of the two axes of revolution (16a, 16b) lies substantially in a horizontal plane (E), relative to a wearer of the eyepiece (1) having the right head and the horizontal axis of vision (S), o or in the vicinity of which the center 525a, 25b is located) of the circular arc (C, CE, CI ) turning which defines the sphero-conical upper part (13). 36. Eyepiece (1) according to any one of claims 1 to 35, characterized in that, with regard to the sphero-conical upper part (13), two centers (25a and 25b) corresponding respectively to the arcs of circle (CE and CI) defining the surfaces   exterior and interior (24 and 25).   37. Eyepiece (1) according to claim 36, characterized in that the center (25a) of the arc of a circle (CE) corresponding to the external surface (24) is closer to the wall (9) of the eyepiece (1) that the center (25b) of the circular arc (CI) corresponding to the surface interior (25).   38. Eyepiece (1) according to any one of   claims 35 or 36, characterized in that both   centers (25a, 25b) of the arcs of a circle (CE and CI) have a spacing (F) of between 1 and 3 mm between them and in particular equal to or about 2 mm.   39. Eyepiece (1) according to any one of   claims 35 to 38, characterized in that both   centers (25a, 25b) of the arcs of a circle (CE and CI) are located in the horizontal plane (E) passing through   the intersection (26) of the two axes of revolution (16a, 16b).   40. Eyepiece (1) according to any one of   claims 35 to 38, characterized in that both   centers (25a, 25b) of the arcs of a circle (CE and CI) are aligned on the common radius (AE, AI) of these two arcs which meet at the location of the wall (9) the axis of vision (S) of the wearer (R). 2740689   41. Eyepiece (1) according to any one of   Claims 1 to 40, characterized in that the radius of   curvature (AE) of the circular arc (CE) corresponding to the   outer surface (24) of the spherical upper part   conical (13) is slightly larger than the radius of curvature (AI) of the arc of a circle (CI) corresponding to the inner surface (25).   42. Eyepiece (1) according to claim 41, characterized in that the difference (G) between the two radii of curvature (AI and AE) is between 1 and 1.4   mm, in particular is equal to or close to 1.2 mm.   43. Eyepiece (1) according to any one of   claims 41 or 42, characterized in that the radius of   curvature (AE) of the circular arc (CE) corresponding to the external surface (24) is equal or close to 634.5 mm, + 2 mm approximately and the radius of curvature (AI) of the circular arc ( CI) corresponding to the interior surface (25) is   equal or close to 633.3 mm, + 2 mm approximately.   44. Eyepiece (1) according to claim 39, characterized in that the spacing (HE, HI) respectively between the intersection of the axes of revolution (16a, 16b) and the centers (25a, 25b) of the arcs of a circle ( AE, AI) is equal to or close to 771.8 mm, approximately + 3 mm for the exterior surface (24), and 773.8 mm, approximately + 3 mm for the inner surface (25).   45. Eyepiece (1) according to any one of   claims 1 to 43, characterized in that it is limited,   downwards, by a plane (P) where there is the opening (11) for the snout which - compared to a carrier with the right head and the horizontal axis of vision (S) - made with   the horizontal an angle (J) of the order of 45.   46. Mask (2) for respiratory protection comprising an eyepiece (1) according to any one of   claims 1 to 45, a skirt (3) for connecting   the eyepiece (1) with the wearer's face (V) (R), a mask   interior (7), and respiratory means (8).   47. Protective suit (2b) comprising a   mask (2) according to claim 46.   48. Protective helmet (2a) including a mask according to claim 46.