Note: Descriptions are shown in the official language in which they were submitted.
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Protective screen and visor produced therewith for a safety helmet,
particularly a
forestry worker's helmet
The invention relates to a protective screen for the face and above all the
eyes of a per-
son, against flying particles and pointed objects, in particular during
forestry work, having a
mesh with a mesh structure which is formed by a multiplicity of mutually
adjacent rows of
noncircular openings which are delimited by mesh webs which are common to the
open-
ings.
A protective face screen of this type is known from document EP 1 182 943 B1.
The for-
mer is manufactured by etching metal, and comprises a mesh which forms a large
number
of light-permeable openings, the openings containing various surfaces. The
protective
screen has at least two regions. The surface of each opening within each
region is identi-
cal and the surfaces of the openings in different regions differ. The mesh is
enclosed by a
continuous rim, the width of which corresponds to about the thickness of one
of the mesh
webs between adjacent openings of the mesh. Such a rim cannot be expected to
substan-
tially contribute toward the stability of the mesh. Once the protective screen
is insertion-
molded with a support frame of plastic which encloses the mesh, irregular
transitions be-
tween the inner boundary of the support frame and the mesh moreover arise,
because the
plastic spreads in an irregular manner into some openings of the mesh and not
into other
openings. Furthermore, the mesh of the known protective face screen in the
various re-
gions has in each case different stability and strength, because the latter
are determined
on the one hand by the size of the openings of the mesh, which differs in the
various re-
gions, and on the other hand by the thickness of the mesh webs, which likewise
differs in
the various regions. The size of the surfaces which differs from region to
region also brings
about that the mesh also has a degree of light transmission which differs from
region to
region.
Document FR-A-826 990 discloses a screen for protecting the human eye from
excessive
sunlight, which replaces the usual colored lenses in sunglasses. The screen is
composed
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of a circular plate which is adapted so as to be insertable into the lens
opening of a spec-
tacle frame. The screen comprises a multiplicity of mutually adjacent rows of
round, that is
to say circular, openings of the same diameter, or rows of circular openings
having two
different diameters. There should be no problems in respect of stability and
quality of ap-
pearance in the case of the known screen, since the screen overall has only a
diameter
which in the initial state of the screen is not much larger than the lens
opening of a specta-
cle frame in which said screen is gripped on its entire circumference.
Protective screens
such as employed in a visor of a protective helmet are many times larger and
thus not
comparable to a protective screen of the size of a spectacle lens, at least
not in terms of
stability.
It is an object of the invention to improve stability in a mesh of the type
mentioned at the
outset, and to improve the quality of appearance of a support frame which is
molded to the
mesh. Moreover, a visor for a protective helmet, particularly a forestry
worker's helmet, is
to be provided.
Proceeding from a support frame of the type mentioned at the outset, this
object is
achieved according to the invention in that the openings, apart from part-
openings which
immediately adjoin a rim of the mesh which is without a mesh structure, in
each case have
a substantially identical surface area, wherein the rim encloses the mesh and
along its
circumference has a width which is at least equal to a height of a row of
openings of the
mesh structure. The large width of the rim of the protective screen according
to the inven-
tion substantially contributes toward increasing stability of the mesh. The
same surface
areas of the openings of the mesh impart to the latter a degree of light
transmission which
is substantially homogenous in the region of the entire mesh. The wide rim
moreover ena-
bles the protective screen according to the invention to be provided with a
support frame
having a uniformly running inner boundary.
A visor for a protective helmet, particularly a forestry worker's helmet,
which is manufac-
tured from a protective screen according to the invention, the rim of which is
insertion-
molded with a support frame of plastic, has the desired increased stability
and the targeted
improved appearance.
Advantageous design embodiments of the protective screen and of the visor
according to
the invention form the subject matter of the dependent claims.
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In one design embodiment of the protective screen according to the invention
the width of
the rim is at least equal to the height of two vertically adjacent rows of
openings of the
mesh structure. Based on the minimum width of the rim which is used in this
design em-
bodiment, this configuration imparts to the protective screen and to the visor
according to
the invention the targeted greater stability.
In one further design embodiment of the protective screen according to the
invention the
rim is provided with clearance holes which are distributed across its length
and which pre-
dominantly are each smaller than each of the mesh openings. These clearance
holes are
a few clearance holes of a comparatively large diameter which as fitting holes
facilitate
insertion of the protective screen into a processing machine in which the
protective screen
in its entirety is coated with a protective layer, or in which the protective
screen is inser-
tion-molded with a support frame, and are substantially more clearance holes
of compara-
tively small diameter through which the plastic can pass during the
manufacture of the
support frame in order to improve the connection between the mesh and the
support
frame.
In a further design embodiment of the protective screen according to the
invention the min-
imum number of openings in the mesh per square centimeter is at least 15. The
number of
openings per square centimeter here is selected according to the protection
requirements.
For example, if it is known that shavings of softwood arise during forestry
work, a coarser
mesh may be selected. However, a finer mesh should be selected where shavings
of
hardwood arise. In the present context, coarse means, for example, 16
openings/cm2, in
contrast thereto fine means, for example, 39 openings/cm2.
In a further design embodiment of the protective screen according to the
invention the
thickness of the mesh webs is selected so as to be inversely proportional to
the number of
openings per square centimeter. Thus, in the case of the selected coarse mesh
having 16
openings/cm2 the thickness of the mesh webs may be approx. 0.3 mm, in contrast
thereto
in the case of the fine mesh having 39 openings/cm2 approx. 0.2 mm. The
associated
height of one row of openings of the mesh structure in the two aforementioned
examples
may be approx. 3 mm or approx. 2 mm, respectively, wherein this value would
then also
be the minimum width according to the invention of one row of openings of the
mesh struc-
ture.
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In a further design embodiment of the protective screen according to the
invention the
mesh webs, that in a zone the width of which is at least equal to the vertical
height of one
of the rows and that is adjacent to the rim on its circumference, the mesh
webs are config-
ured to be thicker than the mesh webs of the remaining openings. On account
thereof, a
further increase in the already high and adequate stability per se of the
protective screen
according to the invention may be achieved.
In a further design embodiment of the protective screen according to the
invention the
width of the zone is substantially equal to the height of two vertically
adjacent rows of
openings of the mesh structure. In comparison to the overall mesh, the zone
thus has a
modest width which, however, on account of the mesh webs which are configured
so as to
be thicker within the zone, still substantially increases the strength and
stability of the
mesh. The degree of transmission within the zone is substantially equal to the
degree of
transmission of the mesh outside the zone, since the surface areas of the
openings which
are surrounded by comparatively thick webs are substantially equal to those of
the open-
ings which are surrounded by comparatively thin mesh webs.
In a further design embodiment of the protective screen according to the
invention the
openings in the zone have the same vertical center spacing as the openings in
the remain-
ing mesh. The achieved additional rigidity of the mesh does not compromise the
degree of
light transmission, in particular not in the so-called viewing opening, since
the zone lies at
the rim of the mesh, and moreover since all openings of the mesh which are
outside and
within the zone are disposed in the same grid pattern.
In a further design embodiment of the protective screen according to the
invention the
mesh is manufactured from spring steel sheet. In this case, a thin metal sheet
may be em-
ployed in order to achieve the desired stability at the lowest weight of the
protective screen
and, in particular, to ensure protection against high-velocity particles.
In a further design embodiment according to the invention the mesh is
manufactured by
etching. Etching is the preferred manufacturing method when metal is employed
for the
mesh of the protective screen. Protective face screens may indeed also be
manufactured
from a woven metal wire or plastic mesh, but such meshes have various
disadvantages for
the carrier which etched metal meshes do not have. Such disadvantages include,
for ex-
ample, that the wires occupy a large part of the entire surface of the mesh
and result in
lower stability and mechanical strength than an etched metal mesh. Moreover,
such wo-
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ven wire or plastic meshes may be pierced by pointed objects, such as pointed
branches
or twigs, because wires or plastic threads are displaceable in relation to one
another.
In one design embodiment of the visor according to the invention an inner
boundary of the
support frame which faces the mesh has a spacing from an inner circumference
of the rim
which adjoins the mesh. On account thereof, a clean appearance of the inner
boundary of
the support frame is ensured in a simple manner.
Exemplary embodiments of the invention are described in more detail in the
following with
reference to the drawings, in which:
Fig. 1 shows a plan view of a first exemplary embodiment of a
protective screen
according to the invention, having a mesh of spring steel sheet;
Fig. la shows a detail of the protective screen according to fig. 1 in a
larger scale;
Fig. 2 shows a second exemplary embodiment of the protective screen
according
to the invention, having a mesh of spring steel sheet which has a finer mesh
structure than the mesh of the first exemplary embodiment;
Fig. 2a shows a detail of the protective screen according to fig. 2 in
a larger scale;
Fig. 3 shows a third exemplary embodiment of the protective screen
according to
the invention, which corresponds to the first exemplary embodiment but has
a different mesh structure in the peripheral region;
Fig. 3a shows as a detail the peripheral region of the protective
screen according to
fig. 3 in a larger scale;
Fig. 4 shows a fourth exemplary embodiment of the protective screen
according to
the invention, which corresponds to the second exemplary embodiment but
in a zone which is adjacent to the rim has a different mesh structure; and
Fig. 4a shows as a detail the zone and an adjacent region of the
protective screen
according to fig. 4 in a larger scale.
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Fig. 1 shows a plan view of a first exemplary embodiment of a protective
screen according
to the invention, which in its entirety is referred to as 10, having a mesh 12
of a thin spring
steel sheet.
Fig. la shows a detail of the protective screen 10 according to fig. 1 in a
larger scale. The
mesh 12 has a mesh structure which is formed from a multiplicity of mutually
adjacent
rows of noncircular openings 14. According to the illustration in fig. la, the
openings are in
each case hexagonal and delimited by common mesh webs 16 which have a
thickness D.
Apart from part-openings 13 which immediately adjoin an encircling rim 18,
which is with-
out a mesh structure, but which are negligible in the overall scheme, the
openings 14 of
the mesh 12 have in each case identical surface areas. Furthermore, on account
of this
construction, in each case two adjacent rows of openings 14 of the mesh have
one and
the same vertical center spacing M.
The mesh 12 is enclosed by the rim 18 which has a width B which is at leas' t
equal to a
height H of one row of openings 14 of the mesh structure. Preferably, the
width of the rim
10 is at least equal to the height of two vertically adjacent rows of openings
14 of the mesh
structure.
The rim 18 is provided with clearance holes 15, 17 which are distributed
across its length
and which predominantly are each much smaller than each of the openings 14 of
the
mesh 12. In the case of the first exemplary embodiment of the protective
screen 10 which
is illustrated in figs. 1 and la, these clearance holes are clearance holes 15
of a compara-
tively large diameter and predominantly clearance holes 17 of a comparatively
small di-
ameter. Each clearance hole 15 substantially has a surface area which is
identical to one
of the openings 14 of the mesh structure. The clearance holes 15 of a
comparatively large
diameter are fitting holes which facilitate the insertion of the protective
screen 10 into a
processing machine in which the protective screen in its entirety is coated
with a protective
coating and/or in which the protective screen is insertion-molded with a
support frame (not
illustrated). The clearance holes 17 of a comparatively small diameter, of
which there are
substantially more than of the clearance holes 15 of a comparatively large
diameter, ena-
ble the plastic to pass through during molding of a support frame 52 which is
indicated in
fig. 4, in order to improve the connection between the mesh 12 and the support
frame 52.
Fig. 2 shows a second exemplary embodiment of a protective screen according to
the in-
vention, which in its entirety is referred to as 20, having a mesh 22 of
spring steel sheet
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which has openings 24 which are smaller than the openings 14, and has a finer
mesh
structure than the mesh 12 of the first exemplary embodiment. The minimum
number of
openings 14, 24 per square centimeter in the mesh 12 or 22, respectively, is
at least 15,
according to DIN EN 1731. The actually used number of openings in the mesh is
selected
according to the protective requirements, that is to say according to whether,
for example,
protection against flying particles which are softwood shavings or hardwood
shavings is to
be ensured. The mesh 22 has mesh webs 26 which have a thickness D which is
inversely
proportional to the number of openings per square centimeter. In the first
exemplary em-
bodiment of the protective screen according to the invention the mesh 12 is a
compare-
tively coarse mesh having sixteen openings 14 per square centimeter. In the
second ex-
emplary embodiment of the protective screen 20 according to the invention the
mesh 22 is
a comparatively fine mesh having thirty-nine openings 24 per square
centimeter. The de-
tails which are shown in figs. la and 2 make it apparent that the thickness D
of the mesh
webs 16 in the comparatively coarse mesh 12 is greater than the thickness D in
the com-
paratively fine mesh 22. The details in figs. la and 2a are illustrated on the
same scale of
enlargement, such that it is immediately obvious that the comparatively coarse
mesh 22
has substantially fewer rows and openings 14 than the comparatively fine mesh
22 has
rows of openings 24. The openings 24 of the mesh 22 all have identical surface
areas.
The same applies to the openings 14 of the mesh 12, wherein however the mesh
22, hay-
ing an identical surface area to that of the mesh 12, has substantially more
openings 24
than the mesh 12 has openings 14.
Fig. 3 shows a third exemplary embodiment of the protective screen according
to the in-
vention, which in its entirety is referred to as 30 and which corresponds to
the protective
screen 10 according to the first exemplary embodiment, but has a different
mesh structure
in the peripheral region. As a detail, fig. 3a shows the peripheral region of
the protective
screen 30 according to fig. 3 on a larger scale. Same parts as in figs. 1 and
2 are provided
with the same reference signs in figs. 3 and 4 and do not require renewed
description.
In the exemplary embodiments according to figs. 3 and 4, mesh webs 36a and
46a, re-
spectively, of openings 34a and 44a, respectively, which lie in a zone 70
(shown in fig.
having a dashed delimitation) adjacent to the rim 38 and 48, respectively,
have a larger
thickness D than mesh webs 36b and 46b, respectively, of the remaining
openings 34 and
44, respectively. Here, openings 34 and 34a or 44 and 44a, respectively, in
adjacent rows
outside or within the zone 70, respectively, have the same vertical center
spacing M as the
openings in the remaining adjacent rows of the mesh 32 and 42, respectively.
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The zone 70 has a width BZ which is at least equal to the vertical height H of
one of the
rows. In the exemplary embodiments according to figs. 3 and 4 the width BZ of
the zone
70 substantially is equal to the height of two vertically adjacent rows of
openings 34 or 44,
respectively, of the mesh structure. For improved clarity of the openings 44a
which lie
within the zone 70, their areas are marked with dots in fig. 4a. The
comparatively thick
webs of the openings 44a are achieved by way of a somewhat modified hexagonal
shape
within the openings 44a in relation to the hexagonal shape within the openings
44. In the
corners of the hexagon of the openings 44a, said corners are configured so as
to be
rounded, in contrast to the corners of the hexagon of the openings 44, which
have no cur-
vature radius. In this way, thicker webs 46a of the openings 44a than the webs
46b of the
openings 44 are achieved while maintaining the grid pattern, specifically
while maintaining
a substantially identical surface area of the openings 44a and 44.
The protective screens 10, 20, and 30, like the protective screen 40, may be
provided with
a zone 70 in which the mesh webs are configured so as to be thicker than in
the remaining
part of the mesh 12, 22, and 32, respectively.
In all exemplary embodiments which are described above and illustrated in the
drawings
the mesh 12, 22, 32, and 42, respectively, is manufactured from spring steel
sheet, specif-
ically by etching. According to a photolithographic process or similar, the
mesh structure is
applied onto the metal sheet, using a protective lacquer. The mesh is etched
from all
points which are not covered by the lacquer, in order to manufacture in this
manner the
desired mesh structure having the wide rim 18, 28, 38, and 48, respectively,
which enclos-
es the mesh structure.
The protective screen 10, 20, 30, and 40, respectively, is insertion-molded
with a support
frame of plastic, and is thus employable as a visor for a protective helmet,
particularly a
forestry worker's helmet. Here, according to the illustration indicated in
fig. 4, an inner
boundary 50 of an indicated support frame 52, which faces the mesh 42, has a
spacing A
from an inner circumference 54 of the rim 48, which adjoins the mesh 42. On
account
thereof, the support frame 52 has no contact with the actual mesh 42 and,
after manufac-
turing, has a uniform inner delimitation.
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List of reference signs
10 Protective screen
12 Mesh
13 Part-opening
14 Opening
Clearance hole
10 16 Mesh web
17 Clearance hole
18 Rim
Protective screen
22 Mesh
15 23 Part-opening
24 Opening
26 Mesh web
28 = Rim
Protective screen
20 32 Mesh
33 Part-opening
34a Opening
36a Mesh web
36b Mesh web
25 38 Rim
Protective screen
42 Mesh
43 Part-opening
44 Opening
30 44a Opening
46a Mesh web
46b Mesh web
48 Rim
Boundary
35 52 Support frame
54 Inner circumference
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A Spacing
B Width
D Web thickness
H Height
M Center spacing
BZ Zone width
