U.S. patent application number 09/094805 was filed with the patent office on 2001-08-16 for on-glass antenna.
Invention is credited to BELLI, CHERYL E., DISHART, PETER T., MICHELOTTI, DONALD P., SUTARA, STEVE J., WINTER, JOHN A..
Application Number | 20010013841 09/094805 |
Document ID | / |
Family ID | 22247263 |
Filed Date | 2001-08-16 |
United States Patent
Application |
20010013841 |
Kind Code |
A1 |
DISHART, PETER T. ; et
al. |
August 16, 2001 |
ON-GLASS ANTENNA
Abstract
The present invention provides a transparent antenna including a
transparent dielectric substrate, an electroconductive antenna
element positioned along a major surface of the substrate, an
electroconductive patch capacitively or directly connected to the
antenna element, and a connector secured to the patch to permit
transfer of signals generated by the antenna element to an
electromagnetic energy transmitting and/or receiving device. The
patch, is configured to have a visibility coefficient (i.e. a ratio
of the non-opaque area to the total area) between 0 and 1. In one
particular embodiment of the invention, the antenna element
includes one or more transparent, electroconductive coatings
positioned between first and second glass plies of a windshield for
a motor vehicle and the electroconductive patch is applied to an
exposed major surface of the windshield such that it overlays at
least a portion of the antenna element and is capacitively coupled
to the antenna element. The patch is may be formed from an opaque
electroconductive ceramic IR, UV, thermoplastic or thermoset
paint.
Inventors: |
DISHART, PETER T.;
(PITTSBURGH, PA) ; WINTER, JOHN A.; (PITTSBURGH,
PA) ; BELLI, CHERYL E.; (NEW KENSINGTON, PA) ;
SUTARA, STEVE J.; (NEWBURGH, IN) ; MICHELOTTI, DONALD
P.; (ROCHESTER HILLS, MI) |
Correspondence
Address: |
PPG INDUSTRIES INC
INTELLECTUAL PROPERTY DEPARTMENT
ONE PPG PLACE
PITTSBURGH
PA
15272
|
Family ID: |
22247263 |
Appl. No.: |
09/094805 |
Filed: |
June 15, 1998 |
Current U.S.
Class: |
343/700MS ;
343/712; 343/713; 343/911R |
Current CPC
Class: |
B32B 17/10174 20130101;
H01Q 1/1278 20130101; H01Q 1/1285 20130101; B32B 17/10036 20130101;
H01Q 1/1271 20130101 |
Class at
Publication: |
343/700.0MS ;
343/911.00R; 343/712; 343/713 |
International
Class: |
H01Q 001/32; H01Q
015/08 |
Claims
We claim:
1. A transparent antenna comprising: a transparent dielectric
substrate; an electroconductive antenna element positioned along a
major surface of said substrate; an electroconductive patch having
opaque elements electrically connected to said antenna element,
wherein said patch has a visibility coefficient between 0 and 1;
and a connector secured to said patch to permit transfer of signals
generated by said antenna element to an electromagnetic energy
transmitting and/or receiving device.
2. The antenna as in claim 1 wherein said opaque elements of said
patch are formed from material selected from the group consisting
of electroconductive ceramic IR paints, electroconductive ceramic
thermoplastic paints, electroconductive ceramic thermoset paints,
and electroconductive ceramic UV paints.
3. The antenna as in claim 1 wherein said transparent substrate is
a glass ply, said antenna element is a transparent
electroconductive coating applied to said major surface of said
glass ply, and said patch includes an opaque electroconductive
paint in direct electrical contact with selected portions of said
electroconductive coating.
4. The antenna as in claim 1 wherein said transparent substrate is
a glass ply, said antenna element is a transparent
electroconductive coating applied to said major surface of said
glass ply, and said patch includes a nonelectroconductive material
applied in a predetermined pattern over a portion of said
electroconductive coating and an opaque electroconductive paint
applied over selected portions of said nonelectroconductive
material such that said electroconductive paint is spaced from and
capacitively coupled to said electroconductive coating.
5. The antenna as in claim 1 wherein said transparent substrate is
a glass ply, said antenna element is a transparent
electroconductive coating applied to said major surface of said
glass ply, and said patch includes an opaque electroconductive
paint applied along an opposing major surface of said glass ply
such that said paint overlays at least a portion of said coating
and is capacitively coupled to said electroconductive coating.
6. The antenna as in claim 1 wherein said patch includes a
plurality of interconnected opaque elements forming a pattern
having a visibility coefficient of 0.1 to 0.95.
7. A transparent antenna for a motor vehicle, comprising: a first
glass ply; a second glass ply secured in overlaying relation to
said first glass ply to form a windshield; a transparent
electroconductive antenna element positioned between said first and
second glass plies; an electroconductive patch positioned at least
in close proximity to an exposed major surface of said second ply,
and including opaque elements forming a pattern which overlays at
least a portion of said antenna element to capacitively couple with
said antenna element, wherein said patch has a visibility
coefficient between 0 and 1; and a connector secured to said patch
to permit transfer of signals generated by said antenna element to
an electromagnetic energy transmitting and/or receiving device.
8. The antenna as in claim 7 wherein said antenna element is a
transparent electroconductive coating applied to a major surface of
said first ply and said patch includes an opaque coating applied to
said exposed major surface of said second ply.
9. The antenna as in claim 8 wherein said patch is spaced a
sufficient distance from any electroconductive elements of said
motor vehicle to prevent degradation of said signal due to
electrical interaction between said patch and said
electroconductive elements of said motor vehicle.
10. The antenna as in claim 8 wherein said patch has a visibility
coefficient of 0.1 to 0.95.
11. The antenna as in claim 10 wherein said antenna element is a
first antenna element positioned at least on a central portion of
said major surface of said first ply of said windshield and spaced
from and extending along peripheral edges of said first ply, and at
least one additional antenna element positioned on said first major
surface of said first ply between said first antenna element and a
selected peripheral edge of said first ply, wherein said patch
overlays at least a portion of said additional antenna element.
12. The antenna as in claim 10 wherein said opaque coating of said
patch is formed from material selected from the group consisting of
electroconductive ceramic IR paints, electroconductive ceramic
thermoplastic paints, electroconductive ceramic thermoset paints,
and electroconductive ceramic UV paints.
13. The antenna as in claim 10 wherein said patch is spaced a
sufficient distance from any electroconductive elements of said
motor vehicle to prevent degradation of said signal due to
electrical interaction between said patch and said
electroconductive elements of said motor vehicle.
14. The antenna as in claim 10 wherein said patch has a visibility
coefficient of 0.1 to 0.5.
15. The antenna as in claim 10 wherein said patch has a visibility
coefficient of 0.5 to 0.95.
16. The antenna as in claim 10 wherein said patch further includes
a transparent electroconductive coating.
17. The antenna as in claim 10 wherein said patch further includes
an opaque pad portion of electroconductive material for securing
said connector to said patch.
18. The antenna as in claim 17 wherein said patch includes a first
section spaced from an edge of said second substrate and a second
section extending from said first section toward said edge of said
second substrate, wherein said opaque pad portion is positioned
within said second portion of said patch.
19. A connector for electrically connecting to a transparent
antenna element positioned along a major surface of a transparent
dielectric substrate, comprising; first opaque electroconductive
elements forming a pattern with selected portions corresponding to
selected portions of said antenna element, wherein said pattern has
a visibility coefficient between 0 and 1; and a second opaque
electroconductive element to secure a lead to said connector to
permit transfer of signals generated by said antenna element to an
electromagnetic energy transmitting and/or receiving device.
20. The antenna as in clam 19 wherein said patch further including
a transparent electroconductive coating.
21. The antenna as in claim 19 wherein said patch has a visibility
coefficient of 0.1 to 0.95.
22. The antenna as in clam 21 wherein said first and second
elements are an opaque electroconductive ceramic paint.
23. A method of making a transparent antenna comprising the steps
of: positioning an electroconductive antenna element at least in
close proximity to a major surface of a rigid transparent
dielectric ply; configuring an electroconductive patch with opaque
elements forming a pattern having a visibility coefficient between
0 and 1; positioning said patch such that said patch is
electrically connected to said antenna element; and securing a lead
to said patch to permit transfer of signals generated by said
antenna element to an electromagnetic energy transmitting and/or
receiving device.
24. The method as in claim 23 wherein said ply is a glass ply and
said first positioning step includes the step of applying a
transparent electroconductive coating to said major surface of said
ply, and said second positioning step includes the step of
positioning said patch on said major surface such that said patch
is in direct electrical contact with said coating.
25. The method as in claim 23 wherein said ply is a glass ply and
said first positioning step includes the step of applying a
transparent electroconductive coating to said major surface of said
glass ply, and said second positioning step includes the step of
positioning said patch in spaced apart relation from said coating
such that said patch overlays at least a portion of said antenna
element and is capacitively coupled to said antenna element.
26. The method as in claim 25 further including the step of
securing a second glass ply to said first glass ply to form a
laminate, such that said antenna element is between said first and
second plies, and wherein said second positioning step includes the
step of applying said electroconductive patch to an exposed major
surface of said laminate.
27. The method as in claim 23 wherein said ply is a glass ply and
said first positioning step includes the step of applying a
transparent electroconductive coating to said major surface of said
glass ply, and said second positioning step includes the step of
positioning said patch on an opposing major surface of said glass
ply such that said patch overlays at least a portion of said
antenna element and is capacitively coupled to said antenna
element.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a vehicle antenna and, in
particular to an antenna formed by a transparent coating laminated
between two glass plies and an electrical connection arrangement
for connecting the antenna to a radio or other
transmitting/receiving device.
[0003] 2. Technical Considerations
[0004] In the past, the traditional motor vehicle antenna for
receiving and transmitting electromagnetic signals was a mast or
whip type antenna. Recently there has been a trend towards
incorporating the antenna into the vehicle structure. For example,
U.S. Pat. Nos. 4,768,037 and 4,849,766 to Anaba, et al. and
5,355,144 to Walton, et al. disclose a transparent
electroconductive coating over a substantial portion of a window
and, in particular a vehicle windshield to form an antenna. In
designing an antenna system, attention is given to matching the
impedance of the system's components and, in particular matching
the impedance of the radio, the antenna and a feed line
electrically interconnecting the two components to improve the
reception of selected radio signals. One way this issue has been
addressed by antenna designers is to design the antenna to have a
desired impedance, for example as disclosed in U.S. Pat. Nos.
5,083,135; 5,528,314; and 5,648,758 to Nagey, et al. However,
designing an antenna to have a predetermined impedance would
require each antenna to be designed specifically for the particular
type of radio and feed line used in the particular antenna system,
as well as the vehicle into which the antenna is installed.
[0005] In order to link the antenna element to an external device,
connectors such as wires, braids or tabs have been laminated within
the transparency to make electrical contact with an antenna
element. However, it has been found that when incorporating these
type of connectors between the plies of the laminate, air may be
trapped in the laminate in the vicinity of the connector. It is
believed that the air entrapment is the result of the connector
hindering the de-airing of the laminate during a conventional roll
prepress operation. Bubbles formed by the entrapped air detract
from the aesthetics of the laminate, as well as increase the
possibility of delamination and/or corrosion at or near the
connection.
[0006] To solve both these problems, a capacitive type connection
has been used to electrically interconnect the antenna elements to
the feed lines for a radio, e.g. as disclosed in U.S. Pat. No.
5,355,144. More specifically, an electroconductive material is
applied on the inner surface of the windshield and is capacitively
coupled to a portion of a coating within the windshield that forms
an antenna element. The area of the material on the inner surface
of the windshield is adjusted to provide the proper capacitance
between the antenna coating and the material. However, the presence
of the connector material blocks the vision of the vehicle
operator. It would be advantageous to provide a connection
arrangement which provides the required capacitive performance for
the connection while at the same time providing the vehicle
operator increased visibility in the vicinity of the connector with
minimal distraction.
SUMMARY OF THE INVENTION
[0007] The present invention provides a transparent antenna
including a transparent dielectric substrate, an electroconductive
antenna element positioned along a major surface of the substrate,
an electroconductive patch capacitively or directly connected to
the antenna element, and a connector secured to the patch to permit
transfer of signals generated by the antenna element to an
electromagnetic energy transmitting and/or receiving device. The
patch, is configured to have a visibility coefficient (i.e. a ratio
of the non-opaque area to the total area) between 0 and 1. In one
particular embodiment of the invention, the antenna element
includes one or more transparent, electroconductive coatings
positioned between first and second glass plies of a windshield for
a motor vehicle and the electroconductive patch is applied to an
exposed major surface of the windshield such that it overlays at
least a portion of the antenna element and is capacitively coupled
to the antenna element.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a plan view of a transparent glass antenna
incorporating features of the present invention.
[0009] FIG. 2 is an enlarged plan view of the particular embodiment
of the antenna connection arrangement illustrated in FIG. 1 showing
a patch connector of the present invention, with portions removed
for clarity.
[0010] FIG. 3 is a sectional view taken along line 3-3 in FIG. 1,
with portions removed for clarity.
[0011] FIGS. 4, 5 and 6 are plan views similar to FIG. 2
illustrating additional embodiments of the invention, with portions
removed for clarity.
[0012] FIG. 7 is a plan view similar to FIG. 2 illustrating an
alternate embodiment of the invention, with portions removed for
clarity.
[0013] FIG. 8 is a sectional view taken along line 8-8 in FIG.
7.
[0014] FIG. 9 is a plan view similar to FIG. 2 illustrating an
alternate embodiment of the invention, with portions removed for
clarity.
[0015] FIG. 10 is a sectional view taken along line 10-10 in FIG.
9.
[0016] FIGS. 11 and 12 are plan views similar to FIG. 2 wherein the
antenna connection arrangement is designed to provide limited
visibility through the patch connector, with portions removed for
clarity.
DETAILED DESCRIPTION OF THE INVENTION
[0017] The present invention provides an improved connector
arrangement for a glass antenna system. However, it should be
appreciated that the present invention may be used in other
transmitting or receiving antenna systems where increased
visibility is a priority.
[0018] FIG. 1 illustrates an antenna system 10, including a
laminated vehicle window, i.e. a windshield 12 formed by outer and
inner glass plies 14 and 16, respectively, which are bonded
together by a thermoplastic interlayer 18, preferably polyvinyl
butyral. As an alternative, plies 14 and 16 may be other
transparent rigid materials, for example, acrylic, polycarbonate,
or the windshield 12 may include a combination of different
transparent rigid materials. Windshield 12 further includes at
least one antenna element 20. In the particular antenna
configuration illustrated in FIG. 1, the antenna element 20 is a
transparent electroconductive coating applied on surface 22 of
outer ply 14, in a manner well known in the art, and generally
occupies the central portion of the windshield 12. The coating may
be a single or multilayered metal containing coating, for example,
as disclosed in U.S. Pat. Nos. 3,655,545 to Gillery, et al.;
3,962,488 to Gillery; and 4,898,789 to Finley. The windshield 12
may further include a decorative border (not shown) bonded to the
marginal edge portion of the windshield 12. This border is
typically formed from an opaque non-electrically conductive ceramic
paint applied to surface 24 of inner ply 16, as is well known to
those skilled in the art.
[0019] Although the antenna element 20 discussed above is a
transparent coating, if the antenna element is not positioned in
the major vision area of the windshield 12, or does not obstruct
the windshield's main viewing area, antenna 20 may be a non
transparent electroconductive material, for example,
silver-containing ceramic paint, wires, metal foil, etc. In
addition the antenna element 20 may include a combination of paint,
wire and/or ceramic antenna elements. However, it is preferred that
the antenna pattern provide a degree of visibility through the
pattern.
[0020] With continued reference to FIG. 1, antenna element 20 in
this particular configuration is basically quadrilateral in shape
and preferably spaced from the peripheral edges of the windshield
12. However, it should be appreciated that the antenna element 20
may have a configuration different from that shown in FIG. 1. The
exact shape and position of the antenna element 20, as well as
inclusion of any additional antenna elements, depends in part on
the design of the vehicle into which the windshield 12 is
installed, the angle of the windshield installation, the coating
resistivity, the type of signal to be transferred or received, and
the desired performance of the antenna. These types of design
considerations for a transparent glass antenna are discussed in
U.S. Pat. Nos. 4,768,037 and 4,849,766. For example, antenna
element 20 may have a shape and/or incorporate multiple elements as
disclosed in U.S. Pat. Nos. 5,083,135; 5,528,514; 5,648,758; and
5,670,966.
[0021] An antenna feed arrangement 26 provides a connection between
the antenna element 20 and an electromagnetic energy transmitting
and/or receiving unit 28 via a feed line, for example, a coaxial
cable 30. The connection may be a capacitive connection, as will be
discussed with respect to FIGS. 1-12 of the present application, or
it may be a direct electrical connection as will be discussed later
in more detail. Unit 28 may be a radio, cellular phone, television,
computer, global positioning system, or any other type of system
that uses antenna element 20 to transmit and/or receive signals.
Though not required in the particular antenna arrangement shown in
FIG. 1, the antenna feed arrangement 26 is positioned along the
upper edge 32 of the windshield 12. The antenna feed arrangement 26
is configured such that it is not laminated between plies 14 and
16. More specifically and referring to FIGS. 2 and 3, arrangement
26 includes an electroconductive element or patch 34 which is
positioned in spaced apart relation from and overlays a portion of
the antenna element 20. In the particular embodiment illustrated in
these figures, patch 34 is secured to an exposed surface of
windshield 12, and in particular, surface 24 of inner ply 16, and
is spaced from the coating by inner ply 16 and interlayer 18 such
that the patch 34 is capacitively coupled to the antenna element
20. It has been found that a capacitive connection may be
configured to produce a capacitive reactance that matches the
inductive reactance of the antenna to the radio 28 and coaxial
cable 30 by minimizing the net reactive component, as disclosed in
U.S. Pat. No. 5,535,144. This in turn results in optimal energy
transfer from the antenna to the radio or other receiver.
[0022] Although the coating forming antenna element 20 in the
embodiment of the invention in FIGS. 1-3 is positioned along
surface 22 of outer ply 14, and more specifically, applied to
surface 22 and laminated between two glass plies, the coating
forming the antenna element may be applied to surface 35 of inner
ply 16 or as an alternative, incorporated into the interlayer 18.
Without limiting the present invention, for example, an antenna
wire or electroconductive element may be positioned on or within
interlayer 18. It is also contemplated that the antenna element may
be applied to a flexible substrate such as a polyester film, which
is turn is incorporated into an interlayer and/or laminate as
disclosed in U.S. Pat. No. 5,306,547 to Hood, et al. In addition,
it is anticipated that the antenna may be formed on a monolithic
window assembly, e.g. along a major surface of a single glass ply
with the antenna feed arrangement being positioned on the opposing
major surface of the ply.
[0023] The required area of patch 34 overlaying a corresponding
portion of antenna element 20 is based in part on the spacing
between patch 34 and the antenna element 20, i.e. the thickness of
the interlayer 18 and inner ply 16; the types of material used for
the antenna element, patch, interlayer and glass; and the required
antenna performance. Because signal transfer through the patch 34
is frequency dependent, lower frequency signals (such as AM radio
signals) require a larger patch area than higher frequency signals
(such as FM radio signals) to achieve acceptable antenna
performance. In general, as the overlaying area of the capacitive
patch increases, the signal transfer from the antenna connector
arrangement approaches that of a direct connection to the antenna
element. Capacitance may be controlled, among other ways, by either
varying the electroconductivity of the patch material or by
changing the area of overlap between the patch and a corresponding
portion of the antenna coating.
[0024] An objective of the present invention is to provide a
capacitive connection between the antenna element 20 and the feed
arrangement 26 in such a manner that the patch 34 provides a
desired amount of visibility through the windshield 12 so that the
vehicle operator's visibility is not impaired through the portion
of the windshield where the antenna feeding arrangement 26 is
located, and in particular the upper portion of the windshield 12
as shown in FIG. 1, for example, when viewing a traffic signal. In
addition, providing a degree of visibility through the patch 34 may
be more aesthetically pleasing to the occupants of the vehicle.
More specifically, the patch 34 may be designed to provide
visibility through the connection. As an alternative, patch 34 may
be designed to purposely block a portion of the light passing
through the windshield 12, as will be discussed later in more
detail. To this end, in one particular embodiment of the invention,
the patch 34 is formed into a grid-like pattern as shown in FIGS. 2
and 3 using an opaque electroconductive material. The material used
to form interconnected grid lines 36 may be, for example, an opaque
electroconductive ceramic coating or paint. This type of material
typically includes silver and glass frit combined with one of
several types of carriers. It should be appreciated that the amount
of silver used in an electroconductive ceramic paint depends on the
conductivity required to produce the required capacitance between
the grid lines 36 forming the patch 34 and the coating forming
antenna element 20 and prevent significant resistive losses.
[0025] One type of paint that may be used to form patch 34 is an
electroconductive ceramic paint of the type typically used to form
heating lines on the rear window of vehicles. This paint generally
includes silver particles, flow modifying agents, pigments and an
infrared radiation dried carrier (this paint hereinafter referred
to as "electroconductive ceramic IR paint"). With this type of
material, the grid lines 36 are screen printed onto surface 24 of
ply 16 using techniques well known in the art and heated in an oven
or furnace to dry the ceramic paint. Additional or prolonged
heating is required to cure the paint and bond it to the glass
surface. Although it provides acceptable results, one short coming
of using this type of ceramic paint is that it remains wet for an
extended period of time, i.e. generally until it is dried by an
oven. As an alternative, it is contemplated that the grid pattern
may be formed using an opaque electroconductive ceramic paint which
includes silver particles, flow modifiers and pigment and
incorporates a thermoplastic or thermoset carrier (hereinafter
referred to as "electroconductive ceramic thermoplastic paint" and
"electroconductive ceramic thermoset paint", respectively). Paints
which use a thermoplastic or thermoset carrier are often referred
to as hot melt paints. Non-electrically conductive hot melt
coatings for use on glass are disclosed in U.S. Pat. Nos. 5,346,933
to Knell and 5,411,768 to Knell et al. Non electrically conductive
hot melt paints are also used in the can and bottling industry to
mark the outer surface of the vessel. Electroconductive ceramic
thermoplastic paint has been used to form heating lines on a rear
window of a vehicle, as disclosed in Canadian Patent 1,193,150. In
the instant invention, an electroconductive ceramic thermoplastic
or thermoset paint is applied along surface 24 of ply 16 to form
patch 34 using a screen printing process which incorporates a
heated metal screen that melts the paint and maintains it in liquid
form. When the hot paint contacts the cooler glass surface, the
paint sets, i.e. it immediately dries. It should be appreciated
that although the paint may be dry, it still must be heated to cure
and bond the paint to the glass surface, as with an
electroconductive ceramic IR paint. This type of paint provides an
advantage over electroconductive ceramic IR paints in that since
the thermoplastic/thermoset paints dries immediately, the glass ply
may be handled without fear of smudging the pattern formed by the
grid lines 36, and additional material may be screen printed
directly over the previously screened pattern. As another
alternative, the grid pattern may be formed using an opaque
electroconductive ceramic paint which includes silver particles,
flow modifiers and pigment and incorporates an ultraviolet
radiation cured carrier (hereinafter referred to as
"electroconductive ceramic UV paint"). The electroconductive
ceramic UV paint is dried by exposing the grid pattern to UV light;
however, like the other paints discussed above, the
electroconductive ceramic UV paint still must be heated to cure and
bond the paint to the glass surface.
[0026] It should be appreciated that although the patch material
discussed above is an electroconductive ceramic paint, other
electroconductive materials may be used to form a capacitive
connection to the antenna coating with the required visibility
coefficient, such as but limited to electrically conductive screens
or meshes, wires, inks, plastics, tapes or decals.
[0027] The patch pattern includes an opaque area, i.e. an area
physically coated with the grid lines, and a non-opaque area, i.e.
the uncoated area between the grid lines. In order to measure the
degree of visibility through the patch, as used herein, the term
"visibility coefficient" means the ratio of the non-opaque area of
the patch to the total area of the patch, i.e. the sum of the
non-opaque and opaque areas. It is apparent that the higher the
visibility coefficient, the more "transparent" the patch. More
specifically, a visibility coefficient of 1 would indicate that
there are no opaque elements in the connector arrangement while a
visibility coefficient of 0 would indicate a completely opaque
connector arrangement.
[0028] To connect the patch 34 to cable 30, a wire lead 38 is
secured to the patch 34. Although not required, in the particular
embodiment illustrated in FIGS. 2 and 3, wire 38 is soldered
directly to the patch 34. A terminal assembly 40 (shown only in
FIG. 3), for example a reinforced spade assembly, a male Jaso pin,
or other electrical connection device well known in the art, is
connected to end 42 of wire 38 so that the coaxial cable 30 may be
secured to feed arrangement 26. To facilitate connection of lead 38
to patch 34 by soldering, a connector pad 44 in the form of a solid
coating of the patch material may be provided in the patch 34. As
an alternative to soldering a wire lead 38 to patch 34, a metal
clip (not shown) of a type well known in the art, may be secured to
pad 44 of patch 34, for example by soldering, with a wire or
coaxial cable being secured to the metal clip. Furthermore, if
desired, coaxial cable 30 may be connected directly to pad 44.
[0029] Referring to embodiment of the invention illustrated in FIG.
4, if it is desired to position an antenna feed arrangement 126
near the upper edge 32 of the windshield 12 and the antenna element
is configured such that it is spaced from edge 32, a patch 134
having grid lines 136 may be configured to include an extension 170
which extends along surface 24 of inner ply 16 from the portion of
the patch 134 overlaying the coating forming antenna element 120,
toward upper edge 32. A connector pad 144 is positioned at the end
of extension 170 near edge 32. Although not shown in FIG. 4, the
coating forming antenna element 120 may also be extended toward
edge 32 to provide additional antenna area which may be overlaid by
the patch 134 in order to provide the desired capacitance for the
antenna feed arrangement 126. FIG. 5 illustrates another embodiment
where it is desired to move the entire patch of an antenna feed
arrangement 226 close to windshield edge 32 while maintaining the
antenna coating spaced from the edge 32. More specifically, a
portion of the coating forming antenna element 220, and in
particular coated area 280 is positioned on surface 22 of outer ply
14 along edge 32 with connecting area 282 electrically
interconnecting area 280 with antenna element 220. Patch 234 with
grid lines 236 and connecting pad 244 is positioned on surface 24
of inner ply 16 to overlay at least a portion of the area 280 and
provide the desired capacitive characteristics of the connection.
Although not required, the coated areas 280 and connecting area 282
may be made of the same material as antenna element 220.
[0030] Although not required, it is preferred that the coating
forming the antenna elements 20, 120 and 220 and additional coating
areas such as area 280 not extend to the edge 32 of the windshield
12, but rather terminate at least 1 mm from edge 32. This will
insure that the coating is completely sealed within the windshield
12 and will inhibit coating degradation along edge 32. It is also
desired that the patch 34, 134 and 234 be positioned on the
windshield 12 such that it does not electrically interact, either
by direct electrical contact or capacitive coupling, with other
electroconductive elements in the motor vehicle because such
interaction may degrade and weaken the strength of the signal
generated by the antenna element. More specifically, referring to
FIG. 3, a windshield 12 is typically supported in a motor vehicle
46 on a metal ledge 48 and secured to the vehicle by an adhesive
50, which in some instances is electrically conductive. In
addition, ornamental strips 52 or other types of moldings which may
be formed from electrically conductive materials, may be positioned
along selected edges of the windshield 12 to hide the space between
the windshield 12 and the mounting frame of the vehicle 46. The
patch 34 should be spaced from such vehicle elements a sufficient
distance to at least minimize and preferably avoid such adverse
electrical interaction.
[0031] FIG. 6 illustrates another embodiment of the instant
invention wherein the antenna element includes various shapes and
the patch overlays selected portions of the coating forming the
antenna element(s). More specifically, the antenna pattern, which
is applied to surface 22 of outer ply 14 and is similar to that
disclosed in U.S. Pat. No. 5,528,314, includes a first coating
element 320 covering the central portion of the windshield 12, a
second coating element 380 positioned between the first coating
element 320 and the upper edge 32 of the windshield 12, and a third
coating element 382 electrically interconnecting the first and
second coating elements. Patch 334 of the antenna connector
arrangement 326 includes grid lines 336 and is configured to extend
along surface 24 of inner ply 16 from the upper edge 32 of the
windshield 12 and overlay a selected portion of the second coating
element 380. More specifically, patch 334 includes a section 372
which overlays a portion of coating element 380 and a section 370
which extends from section 372 toward edge 32. A connection pad 344
is positioned near windshield edge 32 for connection of the patch
334 to a lead to the radio. Although not required, the coating
pattern may include a fourth coating element 384 extending from the
second coating element 382 toward the windshield edge 32. As
discussed earlier, this additional element provides additional
coating area that may be overlaid by the patch 334 for additional
capacitive coupling. However, it should be appreciated that the
antenna pattern may eliminate the third and fourth antenna
elements, as disclosed in U.S. Pat. No. 5,670,966.
[0032] An embodiment of the invention that provides an acceptable
signal for an antenna 20 to a receiving device 28, includes an
antenna coating configured as in FIG. 6, with the coating having a
resistivity of approximately 3 ohms per square. Patch 334 is "T"
shaped as discussed above and overlays selected portions of the
antenna coating element. More specifically, in this particular
embodiment, section 372 of patch 334 is about 45 mm by 130 mm and
overlays a portion of second coating 380, and section 370 of patch
334 is about 22 mm by 45 mm and overlays a portion of the fourth
coating element 384. Grid lines 336 are 0.4 mm wide and spaced both
horizontally and vertically at intervals ranging from about 4.5 to
20 mm, depending on the particular location of the grid line within
the overall pattern. An area of section 370 about 22 mm by 13 mm is
covered with a solid coating of electroconductive ceramic paint,
i.e. without the grid pattern, to form connection pad 344 for a
connecting wire or coaxial cable. The grid lines 336 and connector
pad 344 are formed by an opaque electroconductive thermoplastic
paint produced by Cerdec Corporation, Washington, Pa., which
includes about 76% silver powder, 2% lead borosilicate glass frit,
and the remainder pigment, acrylic resin (flow modifier) and
1-octadecanol (thermoplastic carrier). The thermoplastic paint has
a resistivity of about 0.035 ohms per square and overlays
approximately 1008 mm.sup.2 (excluding connection pad 344) of the
antenna coating, while extending over a total area of approximately
6554 mm.sup.2 (excluding connection pad 344). This pattern results
in a visibility coefficient of about 0.85. Increasing the grid line
width from 0.4 mm to 0.8 mm would reduce the visibility coefficient
to about 0.69, while reducing the line width to 0.2 mm would
increase the visibility coefficient to about 0.92.
[0033] It should be appreciated that the opaque area required to
overlay a corresponding portion of the antenna element, i.e. the
actual area covered by grid lines that overlays a corresponding
area of the antenna element coating, will depend on the performance
requirements of the antenna and the materials forming the
windshield, antenna and connection. It should be further
appreciated that the patch may extend beyond the antenna element
such that the entire opaque area does not overlay and capacitively
couple to a corresponding portion of the antenna element.
[0034] Although FIGS. 2-6 illustrate rectangular grid patterns for
patches 34, 134, 234 and 334, respectively, other patterns, such as
but not limited to interconnected circles or other curvilinear
shapes and patterns, may be used to provide the necessary
capacitive connection to the antenna 20 while allowing the occupant
of the vehicle to "see through" the patch. Based on the design
requirements, it is expected that a pattern with the visibility
coefficient approaching 1 may be formed from opaque lines and still
provide acceptable capacitive coupling performance.
[0035] As an alternative to using only a single type of material
for the patch, it should be appreciated that the patch may be
constructed from a combination of materials of the type discussed
earlier, such as but not limited to electroconductive paints and
metal tape. Referring to FIGS. 7 and 8, it is also contemplated
that an antenna connector arrangement 426 may include a patch 434
formed from a transparent electroconductive coating 450 used in
combination with opaque electroconductive members 436 to
capacitively couple with antenna element 420. The coating 450 for
patch 434 is applied to surface 22 of outer ply 14 and may be
similar to the transparent coating forming the antenna element 420.
Members 436 are applied to surface 24 of inner ply 16 and may be
opaque electroconductive materials as discussed earlier. Member 436
may have any configuration required to provide the desired
performance. If required, the arrangement 426 may include an
electroconductive connector pad 444, similar to pad 44 discussed
earlier, to facilitate connection of a connecting wire and/or
coaxial cable to the patch. It should be appreciated that if the
arrangement 426 does not include the opaque members 436, the
visibility coefficient of the arrangement (excluding pad 444) would
be 1.
[0036] In the embodiments of the invention discussed above, at
least one glass ply serves to separate the antenna element from the
antenna connection. However it should be appreciated that the
antenna coating and the connector may both be applied to the same
surface of the substrate. More specifically, referring to FIGS. 9
and 10, the coating forming antenna element 520 is applied to major
surface 24 of inner ply 16. Connector arrangement 526 includes a
patch 534 having a non-electroconductive material 590 applied in a
predetermined pattern over a portion of antenna element 520, and an
electroconductive material 536 applied over the pattern of material
590. Material 590 will electrically insulate material 536 from
antenna element 520 such that material 536 is capacitively coupled
to the antenna coating. If required, the pattern formed by material
590 may be slightly larger than the overlaying pattern of material
536 to ensure that material 536 does not make direct electrical
contact with antenna element 520. Although it is anticipated that
both materials 590 and 536 would be opaque, if material 590 is
opaque, e.g. a conventional ceramic paint typically used in the
automotive glass industry for decorative borders, material 536 may
be transparent. Conversely, if material 536 is opaque, e.g. an
opaque electroconductive paint of the type discussed earlier,
material 590 may be transparent. In addition, although FIGS. 9 and
10 shown the antenna element on the exposed surface of a laminate,
it should be appreciated that an antenna element positioned on a
single transparent ply may use the same connector arrangement as
discussed above.
[0037] It is also contemplated that the pattern used for the
capacitive patch may be enlarged to provide partial shading for
occupants of the vehicle. More specifically, sun visors are
typically positioned at the upper left and right portions of the
windshield of a motor vehicle to provide shading from sunlight for
the driver and the front seat passenger, respectively. Referring to
FIGS. 11 and 12, it is contemplated that a patch 634 may be
positioned at the center of a windshield 12 and configured as a
"third visor" to provide both shade to the inner vehicle
compartment and, if desired, limited amount of visibility through
the patch covered portion of the windshield, while still
functioning as part of an antenna feed 626 for the antenna system.
In the particular embodiment of the invention illustrated in FIG.
11, the patch 634 configuration includes a plurality of
horizontally oriented lines 636 formed from electroconductive
ceramic paints of the type discussed earlier. Lines 636 are all
electrically interconnected by a plurality of vertical lines 690
spaced along the length of the lines 636. This particular patch
pattern includes ten lines each spaced 3 mm apart. The line width
progressively changes from a 10 mm width at the top (i.e. near
windshield edge 32) to a 1 mm width at the bottom of the pattern.
In positioning the pattern on the inner major surface of the
windshield 12, the uppermost line may be positioned either above or
below the opaque decorative border (not shown) that may extend
around the periphery of the windshield. In addition, if desired, at
least a portion of the pattern may be aligned behind a shadeband
(not shown) which is typically incorporated into the interlayer 18.
The entire pattern serves to block a desired amount of sunlight
from entering the vehicle while still providing a limited amount of
visibility through the patch. The horizontal line configuration in
FIG. 12 is similar to FIG. 11 except that a single vertical line
790 is used to electrically interconnect all the horizontal lines
736. The portion of the patches in FIGS. 11 and 12 which overlays a
portion of the coating forming antenna elements 620 and 720,
respectively, forms a capacitive couple to the antenna as discussed
earlier. These particular configurations provide a visibility
coefficient of approximately 0.33. It should be noted that in the
particular embodiment of the invention illustrated in FIG. 11, the
coating forming antenna element 620 is similar to that coating
pattern in FIG. 6 and the pattern of patch 634 overlays a portion
of antenna coating but does not directly correspond to the shape of
coating, while in the embodiment of the invention illustrated in
FIG. 12, that coating forming antenna element 720 is configured
such that most, if not all of the patch 734 overlays a
corresponding portion of the antenna coating.
[0038] The incorporation of the capacitive connector into a third
visor enables very large patches, which in turn improve signal
coupling for low frequency signal antenna, without aesthetic
impairment of the windshield.
[0039] In designing the capacitive patch as a third visor, since
the line elements are electroconductive, care should be taken to
configure the line elements so that the patch does not act as an
antenna that interferes with antenna element 620.
[0040] The present invention provides an antenna connection
arrangement having a predetermined amount of visibility through the
connector while capacitively coupling to the antenna coating. More
specifically, the patch area has a visibility coefficient between 0
and 1, i.e. greater than 0 but less than 1, and preferably 0.1 to
0.95. In embodiments of the invention where the connector
arrangement is also used to provide additional shading to the
interior of the vehicle, it is preferred that the patch have a
visibility coefficient of up to about 0.5, and preferably, about
0.1 to 0.4. For other connector arrangements, it is preferred that
the patch have a visibility coefficient of about 0.5 to 0.95,
preferably about 0.6 to 0.9.
[0041] Although the embodiments of the invention discussed above
show the patch being applied directly to a major surface of the
transparent substrate, it should be appreciated that the patch may
be applied to a separate element, e.g. a polyester film, which in
turn is secured to the substrate in a manner that allows the patch
to overlay and capacitively couple to the antenna element.
[0042] The antenna feed arrangement as discussed above and shown in
FIGS. 1-12 is a capacitive connection. More specifically, the
electroconductive patch overlays and is spaced from the coating
forming the antenna element(s) by a dielectric. However, it should
be appreciated that a "see through" connector of the type disclosed
herein may also be configured to make direct electrical connection
to the antenna element. More specifically, for example, referring
to FIGS. 9 and 10, material 590 may be eliminated so that
electroconductive patch material 536 is in direct electrical
contact with antenna element 520. The patch material making the
direct electrical connection is preferably an electroconductive
ceramic paint of the type discussed earlier and would be configured
to provide a visibility coefficient between 0 and 1. It is noted
that for a direct electrical connection, it is not necessary for
the patch to overlay a portion of the antenna element but merely be
in direct electrical contact with the antenna element. It should
also be appreciated that outer ply 14 and interlayer 18 may be
eliminated so that the transparent antenna would include only a
single glass ply. In addition, another ply may be secured to the
single glass ply such that the antenna element and direct
connection are laminated between the plies.
[0043] The invention described and illustrated herein represents a
description of illustrative preferred embodiments thereof. It is
understood that various changes may be made without departing from
the gist of the invention defined in the following claims.
* * * * *