Light shield for vehicles having transparent members

A light-blocking device similar to a so-called sun visor, which is adapted for use in vehicles having transparent members such as glass windshields or windows. The device includes a shield in the form of a relatively stiff and generally flat sheet having sufficient opacity to at least serve as a light-filtering medium. A preferred material for the shield is a sheet of polarized plastic having a thickness of 0.030 inch or less, and a minimum area of about 70 square centimeters. A first magnet is affixed to one side of the shield in such a way that the shield may lay generally flush against the inside surface of the transparent member. A second magnet is adapted to be placed on the outside of the vehicle's transparent member in a position so that it is juxtaposed with the interior magnet. The first and second magnets respectively have magnetic orientations such that their confronting faces have opposite polarities, with the result that the two magnets are attracted to each other and the shield is held adjacent the transparent member by the interacting magnetic fields of the two magnets. Each of the magnets preferably has a minimum magnetic strength of about 800 gauss, so that wind loads on the outer magnet will not cause it to be blown off when the vehicle travels at reasonable speeds. In the daytime, the shield is continually re-positioned from time to time in order to remain on a line which extends generally between the sun and the driver's eyes, and the position of the shield is changed by manually adjusting only the interior magnet; the position of the outside magnet is automatically changed by virtue of the magnetic attraction between two magnets. At night time, the shield is positioned on a side window and selectively moved to and from a position where it blocks light reflected from an external rearview mirror (when a second vehicle approaches the first vehicle from the rear).

This invention relates generally to safety devices for use on vehicles, and 
more specifically it relates to a filter or shield for use in blocking at 
least some of the light rays which could interfere with the normal vision 
of a driver or other occupant in the vehicle. A common, although not 
necessarily accurate, name for such a safety device is a sun visor. 
It has long been recognized that operators of vehicles, and especially 
drivers of automobiles and trucks, are greatly hampered in their task of 
guiding their vehicles when a blinding light is positioned such that its 
rays can enter a person's eyes. For this reason, it is common for vehicles 
to be provided with opaque shields, commonly called sun shields or sun 
visors, which are mounted interiorly of a vehicle at a position adjacent 
the vehicle's windshield. A person driving westwardly in the late 
afternoon toward a setting sun would typically move a sun visor so that it 
blocks off the sun's direct rays, thereby permitting the driver to see at 
least some of the road and traffic ahead of him--except for that region 
which is completely blocked off by the sun visor. The size of such an 
opaque sun visor is obviously of some concern to those persons who are 
involved with traffic safety, and governmental agencies often have seen 
fit to issue regulations in this field--even to the extent of proscribing 
a maximum size for a vehicle sun visor. 
The mere size of a traditional sun visor is not the only factor which is 
significant, however, and the placement of that sun visor is also quite 
important. It has been common to mount conventional sun visors on a 
horizontal rod having a pivotal mounting bracket at the corners of a 
windshield, so that a sun visor can be used either directly in front of a 
driver or to his left side. Such a pivotable sun visor has not been 
without its limitations, though, especially when the direction from which 
the sun's rays are coming is below or beyond the "reach" of a permanently 
mounted sun visor. To overcome these deficiencies, it has been proposed in 
U.S. Pat. No. 2,613,104 to Parsons to provide an independently movable 
"light reflector" which can be held at essentially any desired position 
around a metal window frame or windshield frame. A permanent magnet is 
secured to an edge of a planar sheet, and the magnet serves as the 
attaching means for mounting the sheet at any of a variety of positions. 
While the Parsons construction may have had significant utility in 1950 
(when most window frames were made of steel), the modern use of 
light-weight and non-magnetic materials such as plastics around windows 
and windshields has rendered the Parsons construction essentially 
obsolete. 
An alternative to the Parsons magnetically-held sun visor is a sun visor 
adapted to be held to a glass pane by a suction cup, which is shown in 
U.S. Pat. No. 2,715,043 to Schewell. The Schewell construction offers much 
more flexibility in selecting a mounting location, because it can be 
attached to a windshield at most any place where a rubber suction cup can 
establish an adequate seal to the glass pane. While the principle of the 
Schewell construction is certainly meritorious--in theory, those persons 
who have had practical experience with suction cups can testify that they 
often lack true effectiveness in holding something for an extended period 
in a vertical or near vertical plane. And, a sun shield which falls off 
the windshield at an inopportune time can contribute to greater problems 
than were perhaps initially solved by providing such a sun visor. Thus, if 
a driver is distracted by his need to suddenly recover a fallen sun visor 
and then labor to re-mount it on the windshield in front of him, his 
distraction from the road and surrounding traffic could even contribute to 
an accident. Hence, the inherent deficiencies of suction cups which are 
small enough to be useful on a sun visor but large enough to create an 
adequate vacuum (with resultant holding power) have left open the 
possibility of still further improvements in sun visors. Accordingly, it 
is an object of this invention to provide an article in the nature of a 
sun visor which overcomes many of the above-described problems. 
Another object is to provide a relatively small sun visor or glare 
protector which is particularly easy to position exactly where it is 
needed in order that the overall size of the device is not unduly great. 
Still another object is to provide a device which requires essentially no 
installation effort, and which can be easily transferred from one car to 
another. 
Still another object is to provide a construction which is useful at 
nighttime to block any offending light rays emanating from a car 
approaching from the rear--and more specifically, light rays which would 
otherwise be visible in an external rear-view mirror.

Before proceeding with a detailed description of the invention, it is 
interesting to note that the U.S. Government has seen fit to regulate the 
amount of reflectance which is permissible from surfaces within an 
automobile, e.g., the reflectance from instrument panels, windshield wiper 
arms, rear-view mirror mounting hardware, the horn ring, etc. One such 
Federal Standard (No. 515-13 entitled "Glare Reduction 
Surfaces--Instrument Panel and Windshield Wipers for Automotive Vehicles") 
proscribes the maximum amount of light reflection which is permissible 
within the operator's field of view. Of course, the greatest source of 
hazardous light which could temporarily blind a driver is not reflected 
light; it is the light which comes directly from a relatively bright 
source such as the sun or another vehicle's headlights. Hence, all of the 
well-intentioned governmental regulations with regard to controlling 
reflections off interior surfaces in an automobile is really of minor 
significance--as compared with the matter of dealing with direct 
impingement of light rays. Furthermore, there are at least two other 
sources of reflected light which are not regulated and which are much 
greater than anything which exists within a given automobile, namely, the 
light which reaches a driver's eyes after being reflected from certain 
exterior surfaces of other vehicles (such as windows, mirrors and shiny 
bumpers), and naturally occurring "reflectors" such as ice, snow and wet 
streets. It should be appreciated that the construction disclosed herein 
is ideally suited to handle all of the above-mentioned direct and indirect 
sources of light, because the glare-preventor described herein can be 
moved to essentially any location on a windshield or side window. That is, 
the shield disclosed herein is not restricted by any artificial limits of 
mounting hardware, space or weight limits, etc.; it can be placed where it 
is needed at any given time to block light from a specific source without 
simultaneously creating an unnecessarily large "dead space" behind the 
shield. 
In brief, the invention comprises a filter or shield of light-weight, 
planar material (such as a sheet of translucent plastic) to which is 
securely affixed a small magnet. The size of a preferred plastic shield is 
about 125 square centimeters, and the configuration is preferably that of 
a generally rectangular shape, typically about 12.5 cm by 10 cm. Ideally, 
the shield has an opacity which is similar to that of material which is 
utilized in sunglasses, and it may be polarized to enhance its 
sun-blocking qualities. A second magnet is not permanently connected to 
either the shield or the first magnet, but it is shaped so that it may be 
easily juxtaposed with the first magnet in order that the magnetic fields 
of the two magnets may cooperate to attract each other. In use, the shield 
and its connected magnet are adapted to be placed next to the interior 
side of a transparent member (such as a window or windshield) in a 
vehicle. The other magnet is then manually placed on the exterior side of 
the transparent member and juxtaposed with the first magnet, such that the 
two magnetic fields will interact and the shield will be held in place by 
the mutual attraction of the two magnets. For use on wheeled vehicles such 
as automobiles, trucks and motorcycles, the magnets preferably have a 
minimum magnetic strength of about 800 gauss. 
Referring specifically to FIGS. 1 and 2, the light-blocking device 10 is 
shown in an operative position adjacent a transparent member of a vehicle. 
Exemplary transparent members are windshields and windows of automobiles, 
trucks, boats and airplanes, as well as windscreens on motorcycles and the 
like. Of course, the transparent member, per se, forms no part of this 
invention; but it is the transparency of such a member that contributes to 
the problem which is solved by the present invention. Hence, a certain 
amount of attention is appropriate with regard to the transparent members 
which are likely to be encountered in practicing the invention. 
Federal standards for windshields and the like are found in Motor Vehicle 
Safety Standards, which are primarily intended to insure that a windshield 
made of glass will not create a large number of potentially dangerous 
glass fragments if it breaks. The most common technique for avoiding 
dangerous glass fragments is to laminate a piece of plastic between two 
layers of tempered glass, with the bonded plastic serving to hold broken 
glass pieces together after fracture of the windshield. Nearly all 
windshields and side windows in modern automotive vehicles range in 
thickness from about 6.0 to 7.2 mm. Therefore, in order for this invention 
to be operative on an essentially universal basis, the magnets which are 
described hereinafter must be sufficiently strong as to be effective 
through about 0.72 cm of what is commonly referred to as safety glass. 
The windshield 12 represented in FIG. 1 is inclined with respect to 
vertical at about 50 degrees, which is a fairly typical value for 
automobiles; trucks and motorcycles often have a more nearly vertical 
windshield or windscreen. The thickness of the light shield 14 will 
typically be about 30 mils, so the requisite strength of the magnets 16, 
18 in order to hold the shield 14 in place on a windshield is primarily 
established by the thickness of the windshield. 
A preferred size for the light shield 14 is about 120 square centimeters, 
so that there will be a sufficient quantity of light-blocking material in 
order that the shield will not have to be moved every time that the 
vehicle changes direction by a couple of degrees. That is, if the shield 
14 is initially positioned so as to be centered with respect to an 
imaginary line between the sun and the driver's eyes, it is advantageous 
if the vehicle's direction can be at least slightly changed without 
requiring the driver to move the shield in order to maintain the value of 
its light-blocking properties. The minimum spot size projected by the sun 
is about 1.25 cm at a typical windshield. Hence, when the shield 14 has a 
length of about 10 cm, there is ample opportunity for the vehicle's 
direction to be slightly changed without requiring re-adjustment of the 
shield's position. A minimum size for the shield 14 is probably about 10 
cm in length and 7 cm in height; such a minimum size would adequately 
block off any anticipated direct or reflected sun rays. 
As for the maximum size of an opaque shield 14, it is believed that a size 
about 15.times.18 cm is realistic, because a larger size would approach 
the point of covering too much of a windshield. To explain this, it must 
be remembered that the shield 14 is to promote safety. And, to perhaps 
eliminate one hazard (such as the blinding effect of the sun's rays) but 
substitute another hazard (blocking off too much of a driver's frontal 
field of view) would not be a particularly desirable trade. It is 
preferred, therefore, that an opaque shield 14 be much smaller than the 
typical sun visor which is found in modern automobiles and trucks. But, to 
the extent that the shield 14 is translucent, so that a driver might see a 
road hazard in front of his vehicle through the shield, the rationale for 
establishing a maximum size is less valid. 
A further consideration with regard to the maximum size of a shield is its 
unsupported length beyond the location of the juxtaposed magnets 16, 18. 
When only a single pair of magnets are utilized to hold the shield 14 next 
to a windshield, it is inevitable that a substantial quantity of the 
shield will extend in a cantilevered manner from a central "base". By 
making the shield exceedingly large, there is a greater opportunity for 
the generally flat shield to warp or bend, such that it might cause 
unwanted optical effects. It is therefore desirable that the shield 14 be 
made relatively stiff, and have an unsupported length (from its magnet) of 
much less than 10 cm. And, if it should be desired to make a relatively 
long and narrow shield 14, then two pairs of widely separated magnets 
would be advantageous, in oder that the unsupported distance from an edge 
of the shield to the nearest magnet might be kept relatively small. 
The first or inner magnet 16 is preferably affixed to one side of the 
shield 14 with a dependable glue; and, to both foster adhesion between the 
shield and the magnet, it is useful to place a small aperture in the 
shield exactly below the spot where the magnet is to be glued, as shown by 
aperture 22 in FIG. 5. This is because it is easier to achieve a reliable 
joint when at least some kind of an edge (around the aperture) is 
provided. Of course, the aperture size should be somewhat less than the 
surface area of the magnet 16 which is to abut the shield 14. In order to 
foster a desirable interaction between the magnets 16, 18, it is preferred 
that each of the magnets 16, 18 be configured so as to be rather thin and 
"short". Ideally, a magnet configured like a very short cylinder with 
smooth ends provides a favorable interaction of two spaced magnets. As was 
explained hereinabove, the minimum size of the sun's image at a vehicle's 
windshield is about 1.25 cm; hence, a generally cylindrical magnet having 
a diameter of about 2 cm will offer relatively good cover for the expected 
light rays from the sun. Ceramic magnets made from barium ferrite or iron 
ferrite are particularly advantageous, for the reasons that they are 
relatively economical to fabricate and they offer a particularly 
advantageous strength-to-weight ratio. Also, ceramic magnets are quite 
capable of providing the minimum magnetic strength (800 gauss) which has 
been found to be desirable for an optimum embodiment of the invention. 
The inner magnet 16 is not likely to ever make direct contact with the 
inside of a windshield, because it will always be separated from that 
inner surface by the thickness of the shield 14. The outer magnet 18, on 
the other hand, is always in contact with the windshield's outer surface. 
And, one of the advantages of the construction disclosed herein is that 
the light shield 14 is movable within the vehicle by merely grasping the 
shield, or the inner magnet 16, and gently pulling sideways. The outer 
magnet 18 will "track" or follow the inner magnet 16, maintaining a nearly 
constant spatial relationship with the inner magnet. Naturally this is 
advantageous as far as being able to easily change the position of a 
shield 14. But, if the magnetic attraction between the two magnets was 
excessively great, and if there was a rough texture on the inwardly facing 
surface of the outer magnet 18, there would be some potential for 
scratching the outer windshield surface with a rough magnet. To minimize 
the chances of scratching the outer windshield surface, it is preferred 
that the inwardly facing surface of the outer magnet 18 be smooth. And, to 
promote economy in manufacture and stocking of magnets, it is reasonable 
that both the inner and outer magnets be identical. Therefore, the facing 
surfaces of each pair of juxtaposed magnets 16, 18 are preferably smooth, 
such that the shield 14 may be manually pulled across a transparent member 
12 without the risk of causing a scratch in the member. 
If the magnets 16, 18 are made of so-called ceramic material, they will 
typically be opaque. And, if a single pair of juxtaposed magnets 16, 18 
are provided in the center of a light shield 14, then there will obviously 
be a central portion of the construction which will block all light. 
However, the bulk of the shield 14 is preferably not completely opaque, 
although it will naturally have sufficient opacity to at least serve as a 
light-filtering medium. In the same manner as with personal sun glasses, 
the user will typically desire to block off those light rays which might 
tend to temporarily blind him; but he would not wish to introduce a 
barrier that would preclude him from seeing other cars, obstacles, or the 
roadway which may be just below the horizon. To the extent that there may 
be a desire to increase the opaque area in the center of a device 10 
without unduly contributing to an excessively large shield, it would be 
appropriate to add an intermediate element 20 to the shield 14. The extra 
element 20 would logically have a size that is greater than the size of 
the magnet, but it would be smaller than the size of the shield 14; and, 
it would logically increase the opacity of the portion of the device 10 
over which it lies. In such an embodiment, a three-tier arrangement of 
light-blocking effectiveness would be possible including 100% blockage in 
the center, about 50% blockage near the periphery, and an intermediate 
blockage (between 50 and 100%) between the center and the periphery. As 
suggested hereinbefore with regard to the minimum size of a light shield 
14, it is not likely that even an intermediate element 20 would be less 
than 20 square centimeters. 
The preferred material from which the shield 14 is fabricated is a 
relatively stiff plastic sheet having a thickness of at least 0.013 cm. A 
suitable material is Kodacel plastic sheet 7M4 produced by Eastman 
Plastics Products. Another satisfactory material is a dyed and 
"weatherized" polyester film marketed by the Transilwrap Co. of Missouri, 
Inc., which has an ultra-violet resistance rating of at least 10 years. If 
the advantages of a polarized film are desired, a 7-layer laminate offered 
by American Polarizers, Inc. and having a thickness of 30 mils is an 
excellent material for the shield 14. This API product includes a 
polarizing film, ultra-violet absorbers and two layers of cellulose 
acetate butyrate. All of the listed materials offer the necessary thermal 
stability which is required for an element which is likely to be stored in 
a parked automobile on a hot summer afternoon. Interior temperatures in an 
automobile which is completely closed (with windows tightly sealed, etc.) 
often exceed 150.degree. F. on summer days. It follows, then, that the 
material for a satisfactory light shield 14 should have excellent 
stability in a hot environment. 
In use, it will be assumed that the driver of a vehicle is about to be 
confronted with light rays (from the sun) which would tend to temporarily 
blind him if the light rays reached his eyes. And, it will be further 
assumed that the driver anticipates that the sun will be only a relatively 
small distance above the horizon and in front of his vehicle--such that 
the light rays are going to be directly in the driver's eyes. To block 
these potentially blinding light rays, the driver will place the planar 
shield 14 (and its attached magnet 16) on the interior surface of the 
windshield, and also place the other magnet 18 on the outer surface of the 
windshield so that the two magnets are juxtaposed. The magnetic field of 
the two magnets will immediately interact to hold the shield 14 where it 
was initially placed. Later, as the relative position between the sun and 
the driver's eyes changes, the shield is merely repositioned by manually 
pulling it along the inner surface of the windshield. That is, the driver 
needs only to manually adjust the position of the interior magnet and its 
attached shield; the position of the outside magnet is automatically 
changed by virtue of the magnetic attraction between the two magnets. But 
while the outer magnet 18 moves easily in response to manual relocation of 
the inner magnet 16, the outer magnet is not moved in response to any 
realistic wind loads on the magnet. That is, relatively small experimental 
models have been tested with relative wind speeds approaching 100 mph 
(accomplished by driving an automobile at a legal speed against a strong 
headwind), and the outer magnet has not been blown away from the 
windshield. This surprising result appears to be relatively independent of 
the shape of the tested magnets, as long as the magnets are relatively 
flat; so, commercially available magnets of conventional shape and size 
may be employed with the invention described herein. 
If the driver changes the direction of movement of his vehicle by 
approximately 90.degree., he can still utilize the shield 14 by 
transferring it to one of his side windows. Or, he can utilize a second 
device on a side window and leave the first set on his windshield. Pulling 
the first device down to the bottom of his windshield will completely 
remove it from a position where it could be within the field of view of 
the driver. 
Among the many advantages for the construction disclosed herein are its 
light weight, typically weighing ony about one-half ounce when a pair of 
800 gauss magnets (each weighing about 8 grams) are utilized as the 
holding means. Another advantage of the construction is its adaptability 
at being positionable at essentially any desirable spot so as to block off 
light rays from a blinding sun. Additionally, the smooth and generally 
planar "interior" surface of the plastic shield 14 can provide a 
convenient place to temporarily put messages or reminders to the driver. 
For example, a user could write notes with a common crayon or grease 
pencil on the smooth plastic shield such as "cleaners", "bread and milk", 
"change oil", etc. Such a readily visible reminder to accomplish some task 
will be prominently in front of the driver at a time when he needs to see 
the reminder and respond to it by performing the required action. After 
the required action has been completed, the reminder can be wiped off the 
smooth plastic surface with relative ease, restoring the shield 14 to a 
clean condition. Also, instead of using the shield surface as a temporary 
memo board, the surface can also be utilized as a permanent reminder to 
drive in a cautious manner or behave in a desirable manner. For example, 
the shield 14 may have permanently printed thereon (by silk screening or 
the like) statements such as: "Maximum Speed: 55 MPH", "Drive 
Defensively", "Courtesy Pays", etc. Such a statement is illustrated on the 
shield 14A shown in FIG. 5. And, of course, there are also opportunities 
for token advertising on such a shield 14; a modest reminder in the form 
of the name of the merchant who gave the shield to a driver would not 
interfere with its basic function as a shield to block off offensive light 
rays. 
In addition to utility of the device 10 during daylight hours, it is also 
of substantial value at night time. Perhaps one of the most offensive 
things that can happen to the driver of a vehicle is to have a car 
approach from the rear with high-beam headlights shining brightly into the 
eyes of the leading driver--through reflections in rearview mirrors. Many 
vehicles have dual-mode rearview mirrors on the inside of the vehicle, so 
that a driver might switch from a daylight mode to a night time mode--in 
order to diminish the offensive light which would otherwise reach his 
eyes. As far as is known, though, there is no comparable technique for 
switching external mirrors into a mode that effectively softens the glare 
of headlights from a trailing vehicle. A person who wishes to eliminate 
offensive reflections in his external mirror is forced to manually change 
the adjustment of the mirror, either by virtue by maneuvering a 
remote-control knob on the inside of the vehicle or reaching his hand 
through an open window and physically touching the mirror in order to 
change its orientation. Regardless of how the outside rearview mirror is 
changed, the action of the driver in defeating the effectiveness of his 
rearview mirror is obviously not a safe practice, for the reason that the 
mirror is no longer functional to warn the driver of another approaching 
vehicle. Until such time as the driver readjusts his outside mirror, he 
has greatly diminished his sensory tools for maintaining awareness of what 
is going on around him. By use of this invention, however, a driver does 
not have to change the orientation of his external mirror, and its 
effectiveness is never completely eliminated. 
Using the device 10 at night time is accomplished by placing the device on 
the window in a position so that it is near the line of sight between the 
driver's eyes and the external mirror, as shown in FIG. 3. Anytime that a 
driver of an approaching vehicle fails to dim his headlights and an 
offensive glare becomes visible in an external rearview mirror, the driver 
who has the device 10 available to him need only pull the shield 14 
slightly forward so that it lies directly on a line which extends from the 
mirror to the driver's eyes (shown in FIG. 4). The harsh effect of the 
offending light rays is instantaneously removed, although at least some 
light will still be visible through a translucent shield 14. If the 
following car should pass the first car or turn off on a side road, the 
driver can immediately restore his rearview mirror to 100% effectiveness 
by merely sliding the shield 14 backward by a few cms. Such a procedure is 
obviously much safer than previously employed techniques, in that it never 
completely eliminates the utility of a rearview mirror, no matter how 
temporary such an interruption may be. And this procedure does not require 
the distraction of a driver who may be trying to properly adjust his 
rearview miror at a time that he should be concentrating on the road or 
traffic in front of him. For this reason alone, the construction disclosed 
herein is believed to have substantial value as a safety device for travel 
on streets and highways. 
In so far as some of the goals of two particular constructions are 
concerned, the present device may be said to be similar to the device 
shown in U.S. Pat. No. 4,003,597 to Acuff. That is, both the Acuff device 
and the present device are conerned with the elimination of what Acuff 
calls "sun blindness", particularly in those areas not protected by a 
conventional automobile sun visor. However, the Acuff device is operable 
only in conjunction with a conventional sun visor--not independently 
thereof; hence, there is no apparent way in which an Acuff device could be 
used to eliminate offending light rays in an external rearview 
mirror--without simultaneously blocking off an inordinate amount of 
visibility to the side of a vehicle. 
In describing the use of the present construction, the word "driver" has 
been regularly utilized--as a brief way of referring to the occupant of a 
vehicle who is most likely to benefit from the device 10. It should be 
understood, though, that any other occupant of a vehicle could also 
utilize one or more of the devices 10. Hence, the word "driver" should be 
understood to broadly encompass any vehicle occupant who wishes to have 
protection from offending light rays. The device 10 is as readily 
serviceable on one side of a vehicle as the other, and at any time of day 
and in any kind of weather. Indeed, a standard outer magnet 18 has been 
found to hold a shield 14 in place just as well in rainy weather as in dry 
weather, etc. This wet-proof property of the device 10 naturally means 
that it could be utilized on a boat having a windshield just as readily as 
on an automobile or truck, etc. 
While only a preferred embodiment of the invention (plus a few 
modifications thereof) have been described in great detail herein, it 
should be apparent to those skilled in the art that numerous variations on 
the basic idea would be possible without departing from the spirit of the 
invention. For example, the strength of the magnets could be increased--if 
desired. But increasing magnet strength by a factor of 10 would still 
require only a modest force (between one and two pounds) to move a shield 
around on the inside of a window. Accordingly, the invention would be 
deemed to be limited only by the scope of the appended claims.