Note: Descriptions are shown in the official language in which they were submitted.
1063570
The present invention is directed to an improved reflector
structure that is highly visible both in daylight and at night,
The present invention provides a reflector atructure for
reflecting light back toward the source thereof, said reflector
structure comprising a one-piece substantially rigid body of - :
transparent material having a substantially smooth light receiv-
ing front face, said body having therein a plurality of recesses
extending from the rear thereof toward said front face and each
defining a cell surrounded by a support wall, the rear faces of
said support walls defining a continuous support surface extending -
substantially throughout the rear of said body, and a plurality
of retrodirective reflector elements o~ said body in said recesses
and oriented therein to reflect light falling upon said front face,
said reflector elements reflecting from said reflector structure
light falling upon said front face in the area thereof correspond-
ing to said cells for reflecting the light back toward the source
thereof to render said reflector structure highly visible at night.
Further features and advantages of the invention together with
its organization and method of operation, will best be understood by -.
reference to the following specification taken in connection with
the accompanying drawings, in which:
Figure 1 is a d$agrammatic view illustrating the placement of
pavement markers along a highway the pavement markers incorporating
therein reflector structures of the present invention;
Figure 2 is a perspective view of a pavement marker carrying
thereon a reflector structure of the present invention;
,
.. ~ Figure 3 is a view of the rear of the pavement marker of Figure
, ~
2;
Figure 4 is an enlarged plan view of a reflector structure made
'' 11;2
.'
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063570
in accordance with the present invention;
Figure ~ is a fragmentary enlarged plan view of the rear of
the l~wer righthand corner of the reflector structure of Figure
4, the backing member having been broken away;
Figure 6 is a view in section along the line 6-60~f
.'~. ..
, .,
, ., ~, .
.. ~ .
. ~ ~
,
~,'
~ . ~
~ -2-
. ,.
: ,,~ '. -' '
: "', '~'
:, :'
-,
.
B
... . . . . .. . I . .. ~ . . ~ . ..
: ~ , . ,; .; . , ~ . . . . .
; . . ` . . `
- 1063570
Figure 5.
Figure 6A is a vlew similar to Flgure 6 and showing
a modlfication Or the rerlector structure;
Figure 6B is another view similar to Figure 6 and il-
5 lustrating another modiricatlon o~ the rerlector structure; :
Figure 7 is a view ln vertlcal sectlon on a still~urther enlarged scale along the line 7-7 of Flgure 4;
Figure 8 is a rurther enlarged view o~ the righthand
end o~ the rerlector structure Or Figure 4 as viewed in the
dlrection of the arrows along the l~ne 8-8 o~ Figure 7;
Figure 9 is a view Or a stop slgn havlng the letters
thereon rormed from retrorerlectlve sheets made ln accordance
with the present invention;
Figure 10 is a ~ragmentary plan view on an enlarged
scale of that portion o~ Flgure 9 enclosed wlthin the clrcle
marked 10;
Figure 11 is a ~urther enlarged plan vlew o~ that
portion Or Figure 10 enclosed wlthln the dotted area marked
11; and
Flgure 12 ls a vlew in vertical section along the
. line 12-12 o~ Figure 11.
~: Referring to Figures l to 3 of the drawings, there
:. ~
is illustrated a highway marker 100 which incorporates therein
two reflector structures 200 made in accordance with and em-
bodylng the princlples of the present lnvention. The highway
marker 100 is particularly userul in indlcating lanes ln a
highway, such ror example as lllustrated ln Figure 1, whereln
a hlghway 50 is divlded lnto four lanes 51, 52, 53 and 54.
In order to mark the boundaries o~ the lanes 51, 52, 53 and
54, a plurality Or the highway markers 100 are arranged in
aligned rows thus to direct lanes Or trarfic respectively
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1063570
along the highway lanes 51, 52J 53 and 54 of the hlghway 50.
It wlll be appreclated that ln the use of the high-
way markers 100, it is hlghly desirable bhat the markers 100
be fully visible both ln the dayllght and at night; the day-
time visibllity is provlded by random light falling on the re-
flector structure 200 and being specularly reflected thereby
into the eyes of the drivers, and the nlghttime vislbillty ls
provided by the llght ~rom the headlights of automobiles fall-
-; ing upon the reflector structures 200 and being retrodlrective-
ly re~lected thereby lnto the eyes of the drlvers. In order
to mount and hold the reflector structures 200 in the prefer-
red operatlng posltlon upon the hlghway 50, for example, the
~ hlghway markers 100 lnclude a metal base 101 having upstanding
- side walls 102 ~oined by a plate 103 that ls adapted to be
dlsposed upon the surface of the associated highway, the slde
walls 102 including portions 104 dlsposed below the plate 103
and extendlng into grooves in the hlghway, a suitable resln -
such as an epoxy resln being provlded ~irmly to mount and se-
cure the base 101 in positlon on the highway. A palr of mount-
.
ing plates 105 also extend between the side walls 102 and are
lnclinqd at an angle o~ ~or example 30 with respect to the
plate 103 to mount the two rerlector structures 200 in the in-
clined positions shown.
."
- The details of constructlon of the reflector struc-
tures 200 are illustrated ln Flgures 4 to 8 of the drawingsJ
wherein it will be seen in Figure 4 that each reflector struc-
ture 200 lncludes a body 201 of synthetic organic plastic
resin, the preferred resin being a methyl methacrylate resin,
the body 201 providing a substantially flat front race 202 and
a substantlally flat rear face 203. In outline as vlewed in
Figure 4, the reflector structure 200 is in the general form
., .
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1063570
of a trapezold having a longer edge 205 normally arlented up-
wardly in use, a shorter lower edge 206 and a palr of normally
upwardly and outwardly incllned slde edges 207 and 208.
A plurallty of recesses or cells 210 are provlded ln
the rear ~ace 203 o~ the body 201, the recesses also servlng
to define support walls or ribs 211 that surround each of the
recesses 210, the cells 210 being rectangular as viewed per-
.
pendicular to the front face 202 as in Flgure 4 but belng es-
~entially square when viewed ln the directlon of the arrows
.': 10 along the llne 8-8 ln Figure 7 (see the lllustratlon ln Flgure
` 8) and in effect constltuting,lslands in the rear,.face 203. In
. order to serve at nlght as a reflector for llght from the head-
,' llghts o~ an approachlng automoblle, each of the cells 210 ls
provlded`throughout the area thereof wlth a plurallty of re-
. 15 ~lector elements 220, the reflector elements 220 being of the
,~ retrodlrectlve type and speclflcally of the cube corner type. ,
~; Referrlng partlcularly to Flgure 8, lt wlll be seen that each , : !
' o~ the cells 210 lncludes four reflector elements 220, each of , :~
the reflector elements 220 belng square ln plan vlew as seen ' :
,
~i, 20 ln Flgure 8 with four of the reflector elements 220 arranged '
7 '' to form a larger square completely fllllng the assoclated cell ,- -~
210. Each reflector element 220 further lncludes three re-
flectlng surfaces 221, 222 and 223 dlsposed mutually perpen-
. dlcular one to the other and ~olnlng a rear corner or apex 224
.~',, 25 and along edges 225, 226 and 227 extendlng forwardly from the
;~: corner 224; more particularly, the edge 225 ls dlsposed be-
.. ~ tween the reflectlng surfaces 221 and 222, the edge 226 1B
:~ disposed betwen the reflectlng surfaces 222 and 223, and the
, .
',:' edge 227 is disposed between the reflectlng sur~aces 221 and
223. It further ls polnted out that the edges 225 and 226 are ,
dlrected toward and termlnate 3t polnts lntermedllte the ends
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:1063570
of the ad~acent slde of the reflector element 220, whereas the
edge 227 extends to and termlnates at a corner of the reflec-
tor element 220. It will be appreciated that each of the re-
flector elements 220 comprlses a triple mirror reflex reflec-
tor that serves effectively to reflect retrodlrectively ln-
cident light falling thereon.
Each of the reflector elements 220 also has a cube
- corner axis about which the reflecting surfaces 221, 222 and
223 are symmetrically arranged, and in order to obtain good
reflectlon, it is deslrable that the light from headlights
entering the reflector element 220 be directed along llnes es-
-.
sentially parallel to the cube corner axls 228. In order to
accomplish thls, the cube corner axes 228 have been arranged
at an acute angle with respect to the front face 202, and
specifically at an angle of approximately 65 30' with respect
thereto, and ln use are dlsposed at an angle of approximately
; 24 30' with respect to the horizontal. Thls inclination o~ ;
the cube corner axes has been found desirable in order to per-
mit the front surface 202 to be inclined at an angle of approx-
20 imately 30 wlth respect to the horizontal ln use and stlll ;~
; obtain a good reflected signal from the reflector elements 220
- when light falls thereon from the headlights of oncoming ve-
. . .
hicles. More particularly, lt has been found that ln use the
front face 202 o~ the reflector body 201 is wiped clean and
not too greatly abraded by automobile tlres passing thereover
provided that the front face 202 is disposed at an angle of
approximately 30 with respect to the horizontal, l.e., the
.
position illustrated in Figure 7 of the drawings. Moreover,
the light emanating from oncoming automobiles is practically
parallel to the highway surface at distances from which the
marker 100 must be viewed, whereby the light from the head-
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1063570
lights of oncoming vehicles strikes the front face 202 at an
acute angle of approximately 30,
The manner ln which the reflector elements 220 oper-
ate to re~lect incldent light ~alling upon the ~ront face 202
at an acute angle of about 30 back toward the source of the
incident llght as lllustrated in Figure 7. An incident ray
240 from the headlights of an oncoming vehicle directed gener-
ally horizontally strikes the front surface 202 at an angle of
about 30 and in passlng into the body 201 is refracted 3S at
240a into a path substantially parallel to the cube corner
axis 228 of the associated reflector element 220. The ray
240a strikes at least two o~ the re~lecting sur~aces 221, 222
and 223 of the reflector element 220 and ls reflected back
therefrom as at 240b through the body 201 and to the front
face 202. At the front ~ace 202, the ray 240b ls re~racted to
provide the exit ray 240c which is directed rearwardly toward
the source of the incident ray 240 and substantially parallel
to the incident ray 240.
From Flgures 4, 5 and 8 it will be seen that sub-
20 stantially 50% Or the total area of the rear o~ the reflector
body 201 ls devoted to the ~lat sur~ace 203 and substantially
50% of the total area of the rear o~ the body 201 is devoted
? to the cells 210 havlng disposed therein the reflector elements
220~ It also is pointed out that the rear sur~ace 203 is con-
25 tinuous in the sense that any point on the surface can be
reached from any other point on the surface without leaving
the sur~ace, and it also is pointed out that each o~ the cells
210 is completely surrounded by the walls 211 and the area
thereof completely surrounded by the sur~ace 203. Withln each
30 of the cells 210, the area thereof is completely filled by
closely packed and interfltting regular geometric shapes~ the
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1063570
reflector elements 220 havlng square outlines as vlewed in
Figure 8 and rectangular outlines as viewed in Figures4 and 5,
all as has been explained hereinabove. There more specifical-
- ly is provided in each cell 210 four Or the rerlector elements
- 5 220J the reflector elements 220 having a rirst orientation
; with respect to the body 201 in the vertlcal row of cells 210
.: , , .
dlsposed to the left in Figure 8, and having a second and dlf~
rerent orientation with respect to the body 201 in the vertical
~- row disposed to the right ln Figure 8. It wlll be understood
that other types of retrodirective reflector elements may be
used in place Or the reflector elements 220J and other geo-
metric ahapes and other arrangements of the reflector surfaces
~ can be utillzed effectively in the present invention.
- It has been found that adequate daytime visibility
and nighttime vlslbillty is provided by the reflector struc-
... , ~, . .
ture 100 when the area of the surface 203 includes rrom about
10~ to about 90% of the total area of the rear of the body 201
and conversely, when the comblned area of the cells 210 in-
cludes rrom about 10~ to about 90~ of the total area of the
. 20 rear of the body 201J the preferred construction being one in
whlch approximately 50% of the t~tal area of the rear of the
body 201 is devoted to the surface 203 and approximately 50~
of the rear of the body 201 i8 devoted to the cells 210. In -
thls connection it i8 noted that in daylight the cells 210 ap-
~ 25 pear dark and contribute substantially no signal and convers,e-
- ly at night the surface 203 appears dark and contributes sub-
~: .
stantially no slgnal. It further is desirable that the re-
flector structure 200 when vlewed from the front at a dlstance
from about one hundred feet or more appear unlformly llghted
throughout ~he area thereof and appear to be of the same shape
both when llghted by dayllght ralling upon the rront face in
. . . - . . - .
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1063570
the area thereof corresponding to the surface 203 ~or the re-
flecting of daylight therefrom and when lighted by llght ~rom
an oncomlng vehicle falling upon the front ~ace 202 in the
area thereo~ corresponding to the cells 210 ~or reflectlng
light back toward the vehicle. To thls end the ma~or dimen-
sions of each of the cells 210 as viewed ln the front face 202
is no greater than about 0.35 lnch and the dlstances between
ad~acent ones of the cells 210 as viewed in the front face 202
is no greater than about 0.35 inch. When the parts have these . :
:~ 10 dimensions, the human eye at one hundred ~eet cannot distin-
: guish between or resolve the indivldual elements seen through
.. ~. . .
the ~ront ~ace 402, whereby the front ~ace 202 appears to be
unl~ormly llghted and o~ uni~orm shape both in the daylight
when lighted by random light and at night when lighted by the ;
. 15 headlights of an oncomlng vehicle.
. .
The rear of the reflector structure 200 is sealed by
a backlng member 250 which ln the rorm o~ the inventlon lllus-
; trated ln Flgures 6 and 7 is in the rorm of a thln metal roil
secured to the surface 203 throughout the area thereof by a ~ . .
thin film-like coating 255 o~ heat-sealable synthetlc plastlc
materlal that is ~usion bonded upon both the surface 203 and
. the adlacent sur~ace of the metal ~oil 250. The metal foll
; 250 may be formed ~or example o~ lead or alumlnum metal, and
may have a thlckness ln the range from about 1 mll to about 5
mlls.
The backing member 250 serves to cover and hermetic-
ally to seal each o~ the cells 210 in a manner independent o~
: each and every other cell 210 in the reflector structure 200.
. 30 As a result, the backing member 250 serves positively to ex- .
clude water, dirt and the like from the cells 210 and thus to
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1063570
prevent the placement of such materlals upon the reflecting
surraces 221, 222 and 223 of the reflector elements 220, there-
- by to preserve unimpaired the optimum light re~leçting proper-
tles thereof. Slnce each of the cells 210 is lndlvldually
5 sealed lndependent of each and every other cell, any break in
the backing member 250 or ln the plastic body 201 which may
permit access of water, dirt and the llke to one cell wlll not
adversely afrect other cells 210 whlch are independently her-
metlcally sealed. Consequently, the reflector structure 210
10 exhibits greater weatherablllty and durabllity in use, even
when the reflector structure is e*tremèly thln, as wlll be ex-
plained more fully herelnafter3 slnce a break or impairment in
one of the cells 210 will not be propagated to ad~acent cells
210 in accordance with the present invention.
It further is polnted out that the support walls 211 -~
extend throughout the rear area of the plastic body 201 and in
the flnal assembly of the re~lector structure 200 on the marker
base 101 distribute the forces applled to the front face 202
throughout the area of the plastlc body 201. In other words,
20 there ls support for the plastlc body 201 throughout the area
thereof`, the only portlons not having direct support belng ,in
the lndlvldual cells 210. As a consequence, the completed re-
rlector structure 200 has great strength even when the total
thickness thereof is only a rractlon of an inch, all as will
25 be expla ined more fully hereinafter.
The coating 255 is transparent, whereby the surface
of the backing member 250 disposed toward the rear face 203 of
~ the reflector body 201 is visible, and prererably forms the
- reflecting surface for reflecting daylight to achieve dayllght
. . .
30 visibillty of the reflector structure 200. Alternatively, a
light reflecting ~ilm such as a metalized ~ilm, may be placed
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1063S70
,
on the sur~ace 203 or on the front surface 202 that corresponds
to and ls coextensive with the surface 203. However, it will
be appreciated that it is prererrèd to protect the re~lectlng
SUrface givlng daylight vlslblllty, wherefore the utlllzatlon
of the front surface of the backlng member 250, whlch may be
- formed o~ pollshed alumlnum, for example, as the dayllght re-
flectlng sur~ace ls to be preferred.
;~ It also ls pointed out that the re~lector body 201
may be formed of clear synthetic organlc plastic resln, where-
by a whlte beam of llght 18 reflected thereby both ln dayllght
and at nlght. However, a color such as red, yellow, blue and
the like may be incorporated ln the body 201, thereby to glve
a colored signal both ln dayllght and at nlght. Alternatlvely,
the reflectlng surfaces of the body 201 may be colored, there-
by to glve colored reflectlons therefrom.
The reflector structure 200 ls conveniently mountedupon the highway-marker base 101 by means o~ a suitable resln,
an epoxy resln belng preferred for thls purpose. In a typlcal
constructlon of the hlghway marker 100 and Or the reflector
structure 200 used thereln, the edge 205 has a length of 4.0
lnches; the edge 206 has a length of 3.675 lnches; the edges
207 and 208 have a length of o.85 lnch; the dlstance between
the surfaces 202 and 203 ls 0.105 lnch; the dlstance between
, ..................................................................... . ..
the corner 224 and the ad~acçnt surrace of the backlng member
250 ls 0.010 lnch; the length of the slde of each of the cells
210 as vlewed ln Flgure 8 ls 0.08 lnch; the vertlcal dimenslon
of each cell 210 as vlewed in Flgure 4 1~ 0.10 lnch; and the
~, wl~th of each slde wall 211 between ad~acent cells 210 ls 0.04
lnch9 the wldth thereo~ preferably belng at least about 0.01
lnchO
In a first modlflcatlon of the reflector structure
; -11 -
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1063570
.
200, the coating 255 may be simply an adheslve that sets at
room temperature rather than a heat-sealable adhesive of the
type descrlbed hereinabove In another modlficatlon of the
invention, it is contemplated that the adheslve coating 255 be
light re~lecting rather than light transmitting whereby the
adhesive coating 255 constitutes a reflecting surface through-
out the area of the rear surface 203, thereby to provide for
- the reflection of daylight for daytime visibility. In other
modifications, the desired dayllght reflecting areas are paint-
ed to provide the desired color and daylight reflecting charac-
teristics.
There is shown in Flgure 6A of the drawings a stlll
further modl~ication Or the present invention wherein the
backing member 250A is a sheet of synthetic organic plastic
resin, such as a sheet of acrylic film that is ~olned directly
to the reflector body 201 as by ultrasonic welding. In this
form of the invention, inasmuch as the film 250A is transpar-
ent, selected portions thereof corresponding to the rear sur- -
face 203 are rendered reflective as by metalizing at 251A to
20 render that area light re~lecting to provide daylight visibil- -
ity. It will be understood that the sheet 250A serves hermet-
ically to seal the cells 210, thereby to provide all of the ad-
vantages of the backing member 250 described above wlth respect
to Figure 6. In yet another form of the lnvention, the film
250A may be opaque and light diffusing, ln which case there is
no need to provide the metallized layer 251A illustrated in
Figure 6A.
Referrlng to Figure 6B of the drawings, there is
shown a further modification of the invention wherein the
several reflecting sur~aces 221, 222 and 223 on each reflector
. - .
element 220 is coated with a thin layer of metal, such as
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~: 1063570
.
aluminum, l.e.~ these surfaces are metalized/ to increase the
reflectlvlty thereof at wide entrance angles. More speciflc-
ally, each of the rerlecting surfaces 221, 222 and 223 ls pro-
vided respectively wlth a thln layer 251B of metal, such as
- 5 aluminum,-thereon. In applylng the layers 251B, the entire
rear surface of the body 201 may be metalllzed, and thereafter
selected areas thereof, such as the surface 203, may have the
metal removed therefrom as by a release hot-stamp process.
Referrlng to Figures 9 to 12 of the drawlngs, and
speciflcally to Flgure 9, there ls lllustrated therein a stop
sign 300 including the usual octagonal shaped support mounted
on a post 302. In accordance with the present invention, the
letters spelllng out the word "STOP" are formed from a retro-
reflective sheet 400. Originally the retroreflective sheet
400 may have been rectangular in shape, for example, and has
been cut into the shapes illustrated to provide the various
letters on the stop sign 300 by cutting with a scissors, for
example.
The details of construction of the retroreflectlve
sheet 400 are illustrated in Figures 10 to 12 of the drawlngs,
whereln it wlll be seen in Flgure 12 that the sheet 400 ln-
cludes a body 401 of synthetlc organic plastlc resin, the pre-
ferred resln being a methyl methacrylate resln, the body 401
. .
provldlng a substantlally flat front face 402 and a substan-
tially flat rear face 403. A plurality o~ recesses or cells
410 are provlded in the rear face 403 of the body 401, the re-
cesses also servlng to define support walls or ribs 411 that
surround each of the recesses or ceIls 410, the cells 410 be~
ing square in shape as viewed perpendicular to the rront face
402 and as illustrated in Flgure 11. In order to serve at
night as a reflector ~or light ~rom the headllghts of an ap-
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1063570
proaching automobile, each of the cells 410 is provlded through-
out the area thereof with a pl~ra~.ity of re~lector elements
. 420, the re~lector elements 420 being of the retrodlrectlve
type and specifically of the cube corner type havlng the same
constructlon as the reflector elements 220 de.scribed above.
However, in the form of the invention illustrated in.~igures
9 to 12, the axes of the reflector elements 420 are disposed
normal to the front face 402; the rear apeces of the reflector
elements 420 are spaced a small distance forwardly with re-
spect to the rear face 403. Summarizing, it will be appreci-
ated that each of the reflector elements 420 comprlses a triple
.~ mirror reflex reflector that serves effectively to reflect
. retrodlrectively lncldent light falllng thereon. :
. Prom Flgures 10 and 11 it wlll be seen that substan- tlally 50~ of the total area of the rear of the reflector body
401 is devoted to the flat rear surface 403 and substantlally
50% of the total area of the rear of the body 401 ls devoted
- to the cells 410 havlng dlsposed therein the re~lector ele- .ments 420. It also ls polnted out that the rear surface 403 ..
. 20 ls contlnuous ln the sense that any polnt on the surface can
be reached from any other poin~ on the surface without leavlng
bhe surface, and it also ls polnted out that each of the cells .
. -410 ls completely surrounded by the walls 411 and the area
` thereof completely surrounded by the surface 403. Wlthln each I ~-
Or the cells 41~, the area thereof ls completely fllled by
closely packed and lnterfltting regular geometric shapes, the
reflector elements 420 havlng square outlines. There more
speclfically ls provided in each cell 410 four of the reflector
elements 420, the reflector elements having a flrst orienta-
tion with respect to the body 401 ln one vertlcal row of cells
~ 410 and havlng a second and different orlentation with respect
.~ -14-
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. .
. : ,
': . ' . ~. . .
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1063570
to the body 410 ln the other vertical rows. It wlll be
understood that other types of retrodirectlve reflector ele-
ments may b~ used ln place of the reflector elements 420, ~ -
and other geometrlc shapes and other arrangements of the re-
5 flector surfaces can be utllized effectively ln the present
invention.
It has been round that adequate night time visl-
bility is provlded by the retrodirective sheet 400 when the
combined area of the cells 410 includes from about 10% to
10 about 90% of the total area of the rear of the body 401,
the preferred construction being one in whlch approximately
50% of the total area of the rear of the body 401 is devoted
to the surface 403 and approximately 50,~ of the rear of the
body 401 is devoted to the cells 410. In this connection
15 lt is noted that in daylight the cells 410 appear dark and
accordingly if posltloned on a contrastingly light or color-
4V
ed support 301 will provide daylight visibllity also. Al-
ternatively, the Surface 403 or an area corresponding to the
surface 403 may be colored or provided with material to give
20 at least specular reflectlon of daylight, whereby the retro-
reflective sheet 400 would itself provide good vislbllity ln
daylight.
It further is desirable that the retroreflective
sheet 400 when viewed from the front at a distance from about
25 one hundred feet or more appear unlfo rmly lighted throughout
the area thereof and appear to be of the same shape both when
lighted by daylight and when lighted by llght at night from an
oncoming vehicle falling upon the front face 402 in the area
thereof corresponding to the cells 410 for reflecting light
30 back toward the vehicle, To this end the ma~or dimensions of
each of the cells 410 as viewed ln the front face 402 is no
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1063570
greater than about 0.35 inch and the distance between ad~acentones of the cells 410 as viewed in the front ~ace 402 is no
greater than about 0.35 lnch~ When the parts have these dimen-
slons, the human eye at one hundred reet cannot dlstlngulsh
between or resolve the indlvidual elements seen through the
~ront face 402, whereby the front face 402 appears to be unl-
formly llghted and o~ uni~orm shape both ln the daylight when
llghted by random llght and at nlght when lighted by headlights
of an oncomlng vehlcle.
The rear of the retrore~lective sheet 400 is sealed
by a backing member 450 which ls prererably a sheet of syn-
thetic organic plastic resin, such as a sheqt of acryllc fllm,
that is Joined directly to the body 401 as by ultrasonic weld- ;
ing. The backing member 450 serves to cover and hermetically
to seal such of the cells 410 in a manner independent o~ each
and every other cell 410 in the retrore~lective sheet 400. As
a result, the bac~ing member 450 serves positively to exclude
water, dirt and the like ~rom the cells 410 and thus to pre-
:,~ ,. .
'`~; vent the placement Or such materials upon the ref~ cting sur- ~
. . .
~aces of the reflector elements 420, thereby to preserve unim-
palred the optimum light reflecting properties thereo~. Since
each of the cells 410 ls indivldually sealed lndependent of
each and every other cell, any break ln a cell 410 such as the
cuttlng therethrough in the ~ormation o~ a letter from the
sheet 400 will not adversely a~fect other cells 410 adJacent
thereto which are independently hermetically sealed! Conse-
quently, the reflective properties o~ the sheet 400 are sub-
stantially unlmpaired by the cuttlng required to form the let-
ters as illustrated in Figures 9 to 12, and the resultant cut
letter exhlblts greater weatherabillty and durability in use
since any break or lmpalrment ln one of the cells 410 wlll not
-16-
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1063570
be propagated to ad~acent cells 410 ln accordance with thepresent inventlon.
The body 401 may be formed of clear synthetic or-
ganic plastic resln, whereby a whlte beam of light is reflect-
ed thereby at night. However, a color such as red, blue, yel-
low and the like may be incorporated in the body 401, thereby
to give a colored signal there~rom~ It also will be appreci-
ated that the sur~ace 403 or areas on the sheet 400 correspond-
ing to the surface 403 may be colored or provlded wlth light
reflecting coatings so as to glve at least specular reflectlon
4.
therefrom ln daylight.
The letters ~ormed of the retroreflectlve sheet 400
may be conveniently mounted on the support 301 by means of a
suitable resin. In a typical construction of the sheet 400,
the distance between the surfaces 402 and 403 is 0.025 lnch;
the dlstance between the front face 402 and the lnnermost
-point of the recesses forming the cells 410 is 0.01 inch; the
thickness from rront to rear of the reflector elements 420 is
approximately 0.01 inch; the length of the side of each of the
cells 410 ls 0.04 lnch; the width of each side wall 411 be-
tween ad~acent cells 410 is 0.01 inch; and the thlckness o~
the backing member 450 is 0.003 inch. When the retroreflective
sheet 400 has the dimensions noted, it can be readily cut into
the shape of various indicia including letters~ numerals, ar-
rows, and the llke and even if such indicla have compllcatedshapes, all without adversely af~ecting the appearance of the
resultant lndicla and without adversely affectlng the retro-
; reflecting properties thereof.
From the above it wlll be seen that there has been
provided a reflector structure 200 that is useful both for re-
flecting daylight falling generally upon the front face 202
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106357Q :
thereof to render the reflector structure 200 highly vlsible
in daylight and for reflecting light falling upon the front
face 202 to reflect the light back toward the source thereof
from the reflector elements 220 to render the reflector struc-
. 5 ture 200 hlghly vlslble at night in the headlights of a vehicle
directed toward the reflector structur.e 200. The reflector
structure 200 more partlcularly has a plurality of lndividuaI
i .,
cells 210 on the rear thereof surrounded by walls 211 havlng a
rear surface all lylng ln a common plane to provlde a rear
face 203, the lndivldual cells 210 comprlslng from about 10
to about 90% of the total area of the rear face, a preferred
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.~ arrangement being one whereln approximately 50~ of the total
area of the rear of the body 201 i5 the cells 210.
: Further there ls provided a backlng member 250 her- ~:
metically seallng each of the cells 210 to prevent an entry of
water, dirt and the llke therelnto, the rearmost portion 224
of the reflector elements 220 belng spaced forwardly a short :.
distance away from the ad3acent surface of the backlng member
~: 250. As a consequence of this structure, a break ln one cell
: 20 210 will not cause the loss of reflectivity ln ad~acent un- ~
:;~ broken cells 210, whereby an unusually thin reflector structure : .
having hlgh strength ls provlded, the walls 211 provldlng sup-
: port for the plastlc body 201 throughout the rear thereof. In
. short, better weatherability and greater durablllty is provid-
.: 25 ed in the reflector structure 200.
It ls preferred that the ma~or dlmension of each of
the cells as viewed ln the front face be no greater than about
. 0.35 lnch and that the distances between ad~acent cells as
vlewed in the front face 202 be no greater than about 0.35
- 30 lnch, whereby when the reflector structure 200 is ~lewed ln
the front face 202 at a dlstance of about one hundred feet or
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1063570
more, lt appears uniformly lighted throughout anc of the same
shape both when lighted by dayllght f311ing upon the front
face 202 and when lighted by light from the headllghts of an
oncomlng vehlcle falllng upon the front face and reflected
back toward the source of light by the reflector elements~
thereby to glve good vislbility both in daytlme and ln night-
tlmeO
Flnally, there has been provided a retroreflectlve
sheet 400 which can be readily cut lnto indicia o~ even com-
pllcated shape without materlally adversely affecting the ap-
pearance of the resultlng lndlcla and wlthout m.aterlally ad-
versely affecting the retroreflecting properties thereof~
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