Abstrict
An electric heater plate is disclosed which is formed on one surface
of a base material. A plurality of thin lines of a nonprecious material
which acts as a resistor when electrical energy flows therethrough
is bonded to the first surface of the base material and extends
from a first location thereon to a second location thereon. At least
two interconnection areas of a non-precious metal which acts as
a resistor when electrical energy flows therethrough are provided.
These interconnection areas are bonded to the first surface of the
base material with one interconnection area interconnecting the
plurality of thin lines at the first location and the second of
the interconnection areas interconnecting the plurality of thin
lines at the second location on the first surface of the base material.
A termination area of silver ceramic material is associated with
each of the interconnection areas. Each of the terminal areas is
in contact with an associated interconnection area. An electrical
lead is bonded to each of the terminal areas for making electrical
connection to the plurality of thin lines. If the electric heater
plate is installed as the rear window of a motor vehicle, the heat
generated by flowing the current through the thin lines can defog
and deice the window.
Claims
I claim:
1. An electric heater plate comprising:
a base material of electrically nonconductive material having at
least a first surface to which metallic materials may be bonded;
a plurality of thin lines of a nonprecious metal which acts as
a resistor when electrical energy flows therethrough, said plurality
of thin lines being bonded to said first surface of said base material
and extending from a first location on said first surface to a second
location on said first surface;
at least two interconnection areas of a nonprecious metal which
acts as a resistor when electrical energy flows therethrough, said
interconnection areas being bonded to said first surface of said
base material, one of said interconnection areas physically and
electrically interconnecting said plurality of thin lines at said
first location on said first surface and a second of said interconnection
areas physically and electrically interconnecting said plurality
of thin lines at said second location on said first surface;
a terminal area of silver ceramic material associated with each
of said interconnection areas, each of said terminal areas having
both a first portion thereof overlying and physically and electrically
bonded to an associated interconnection area and a second portion
thereof overlying and bonded to said first surface of said base
material and not in contact with said associated interconnection
area; and
an electrical lead bonded to each of said terminal areas for making
electrical connection to said plurality of thin lines.
2. An electric heater plate comprising:
a base material of electrically nonconductive material having at
least a first surface to which metallic materials may be bonded;
a plurality of thin lines of a nonprecious metal which acts as
a resistor when electrical energy flows therethrough, said plurality
of thin lines being bonded to said first surface of said base material
and extending from a first location on said first surface to a second
location on said first surface;
at least two interconnection areas of a nonprecious metal which
acts as a resistor when electrical energy flows therethrough, said
interconnection areas being bonded to said first surface of said
base material, one of said interconnection areas physically and
electrically interconnecting said plurality of thin lines at said
first location on said first surface and a second of said interconnection
areas physically and electrically interconnecting said plurality
of thin lines at said second location on said first surface;
a terminal area of silver ceramic material associated with each
of said interconnection areas, each of said terminal areas bonded
to said first surface of said base material and having both a first
portion thereof underlying and physically and electrically bonded
to an associated interconnection area and a second portion thereof
not in contact with said associated interconnection area; and
an electrical lead bonded to each of said terminal areas for making
electrical connection to said plurality of thin lines.
3. The electric heater plate of claim 1 or 2, wherein said nonprecious
metal is selected from the group consisting of copper, nickel and
aluminum.
4. The electric heater plate of claim 1 or 2, wherein said electrical
lead is bonded to said terminal areas by a solder bonding operation.
5. The electric heater plate of claim 1 or 2, wherein said base
material is a sheet of glass.
6. The electric heater plate of claim 1 or 2, wherein said base
material also has bonded to said first surface thereof at least
two power terminations areas, formed of electrically conductive
material wherein one of said electrical leads is bonded to each
of said power termination areas, and wherein a power terminal is
bonded to each of said power termination areas.
Description BACKGROUND OF THE INVENTION AND PRIOR ART STATEMENT
No prior art patent search was conducted on the subject matter
of this specification in the U.S. Patent Office or any other search
facility.
I am aware of my own U.S. Pat. No. 4,137,447, as being probably
the most relevant prior art. My prior patent teaches an electric
heater plate in which there is a substantial reduction in the amount
of silver ceramic material used to form the heater plate.
My prior patent teaches an electric heater plate which is formed
on one surface of a sheet of tempered glass. The one surface of
tempered glass has a plurality of thin lines of a silver ceramic
material bonded thereto, the thin lines extending in a generally
parallel but spaced apart relationship across the sheet of glass.
Left hand and right hand end portions of the plurality of thin lines
are interconnected by a thin interconnection area of a silver ceramic
material. A small terminal area of silver ceramic material is also
associated with each of the interconnection areas located at opposite
ends of the plurality of thin lines. A termination area is also
bonded to the one surface of the sheet of tempered glass at a position
spaced from the left hand and right hand interconnection areas.
A thin copper strip is bonded to each of the terminal areas and
the termination area associated with the left hand or right hand
interconnection area to electrically interconnect the same. Electrical
leads are connected to each of the pair of termination areas to
provide a connection to a power system. When the power system is
actuated, current flows through the plurality of thin lines in order
to heat the tempered glass sheet. If the tempered glass sheet in
installed as a rear window of a motor vehicle, the heat generated
by flowing the current through the thin lines can defog and deice
the window.
The structure proposed in this specification is one which once
again substantially reduces the amount of silver ceramic material
used in an electric heater plate construction. The structure proposed
in this specification is also one which retains terminal areas formed
of silver ceramic material so that secure bonds of electrical leads
may be made thereto. The reduction in the amount of silver ceramic
material used in forming the heater plate results in a significant
cost savings.
The heater plates formed in accordance with the teachings of this
specification have particular utility if they are formed on a sheet
of glass which acts as the rear window of a motor vehicle. Electrical
energy may be flowed through the heater plate construction in order
to heat the same to cause a deicing and defogging action on any
moisture which may have condensed upon or frozen upon the rear window.
SUMMARY OF THE INVENTION
This invention relates to an electric heater plate and more particularly
to an electric heater plate in which both nonprecious metal and
silver ceramic material are used to form the conductive pattern
of the heater plate. The conductive pattern has a resistance which
causes a heating of the pattern and associated heater plate when
current flows through the pattern.
In accordance with the general teachings of this invention, an
electric heater plate is formed in the following manner. A base
material is selected for the heater plate. This base material has
a first surface to which metallic materials may be bonded.
A plurality of thin lines of a nonprecious metal which acts as
a resistor when electrical energy flows therethrough is bonded to
the first surface of the base material. The plurality of thin lines
extend from a first location on the first surface to a second location
on that first surface of the base material. At least two interconnection
areas of a nonprecious metal which acts as a resistor when electrical
energy flows therethrough are bonded to the first surface of the
base material. One of the interconnection areas interconnects the
plurality of thin lines at the first location on the first surface.
A second of the interconnection areas interconnects the plurality
of thin lines at the second location on the first surface.
In accordance with the teachings of the structure of this invention,
a terminal area of silver ceramic material is associated with each
of the interconnection areas. Each of these terminal areas is in
contact with an associated one of the interconnection areas. An
electrical lead is bonded to each of the terminal areas for making
electrical contact to the pluality of thin lines.
In accordance with one preferred embodiment of the structure of
this invention, each terminal area has both a first portion thereof
in contact with an associated interconnection area formed of the
nonprecious metal and a second portion thereof bonded to the first
surface of the base material. The second portion of each terminal
area is not in contact with the associated interconnection area.
The electrical lead is bonded to the second portion of each terminal
area for providing the electrical connection to the plurality of
thin lines.
In still greater detail, alternate embodiments of the electric
heater of this invention provide that the first portion of the terminal
area may either overlie or underlie the portion of the interconnection
area with which it is associated.
Still further detailed embodiments of the structure of this invention
require that the base material be a glass sheet. Other embodiments
are ones in which the non-precious metal is selected from the group
consisting of copper, nickel and aluminum. As an additional detail,
the electrical lead can be bonded to the terminal area by a solder
bond.
BRIEF DESCRIPTION OF THE DRAWINGS
The novel features that are considered characteristic of the invention
are set forth with particularlity in the appended claims. The invention
itself, however, both as to its organization and its method of operation,
together with additional objects and advantages thereof, will best
be understood from the following description of specific embodiments
when read in connection with the accompanying drawings, wherein
like reference characters indicate like parts throughout the several
figures, and in which:
FIG. 1 is an elevation view of an electric heater plate constructed
in accordance with the teachings of this invention;
FIG. 2 is an enlarged drawing of a cross-section taken along line
II--II of FIG. 1;
FIG. 3 is an enlarged drawing of a cross-section taken along line
III--III of FIG. 1; and
FIG. 4 is an enlarged cross-section view similar to FIG. 2 showing
an alternate embodiment of the structure of this invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
In FIG. 1 there is seen an electric heater plate generally identified
by the numeral 10 which is constructed in accordance with the teachings
of a preferred embodiment of this invention. The preferred embodiment
is not intended to be a limitation upon the scope of this invention,
but merely is a descriptive example of the application of this invention
to the manufacture of a product for consumption in the industrial
market.
As seen in FIG. 1, the electric heater plate 10 includes a sheet
of glass 12 which, in accordance with general principles, is normally
a glass sheet which will be tempered in a manner described hereinbelow.
In accordance with the teachings of this preferred embodiment, the
sheet of glass 12 is used as a backlite for an automotive vehicle.
As shown in FIG. 1, the sheet of glass 12 has a plurality of thin
lines 14--14 of a nonprecious metal which acts as a resistor bonded
to one surface thereof. In general, the one surface of the sheet
of glass is that surface which faces the interior of the vehicle
when the sheet of glass is located in an installed position. The
plurality of thin lines 14--14 extend in a generally parallel but
spaced apart relationship across a dimension of the sheet of glass.
In the preferred embodiment, the parallel lines extend across the
length of the glass sheet. As shown in FIG. 1, there are two groups
of four parallel lines.
In accordance with the teachings of this invention, each of the
group of plurality of thin lines 14--14 have right hand end portions
16--16 and similarly constructed left hand portions, not numbered,
at opposite ends thereof. The right hand end portions and left hand
end portions define interconnection areas. These interconnection
areas are formed from a nonprecious metal which acts as a resistor
when electrical energy flows therethrough. Each of the interconnection
areas is bonded to the first surface of the sheet of glass 12. As
mentioned above, one pair of the interconnection areas in the preferred
embodiment interconnects the two groups of thin lines 14--14 at
a first location on the first surface at the right hand edge of
the sheet of glass, and a second pair of interconnection areas interconnect
the two groups of thin lines at a second location on the first surface
located at the left hand side of the sheet of glass.
The plurality of thin lines 14--14 and interconnection areas therefor
such as the right hand end portions 16--16 are formed as mentioned
above from a nonprecious metal which acts as a resistor when electrical
energy flows therethrough. For example, a nonprecious metal which
will work in this area is aluminum. This type of material is produced
and sold by Englehard Company under the trade name E-373A Aluminum
Paste. This nonprecious metal is applied in a conventional manner
through a silk screen printing operation to form in a single operation
both the thin lines 14--14 and their associated interconnection
areas. The nonprecious metal in the form of a paste is applied through
a suitable silk screen. As it passes through this screen, it adheres
to the first surface of the sheet of glass 12. The nonprecious metal
paste are finely divided particles of aluminum milled in low melting
glass frits and other organic additives to facilitate silk screening
of the paste. The additives burn out during the firing of the device.
After the silk screen printing of the thin lines 14--14 and associated
interconnection areas such as the right hand end portion 16--16,
a second silk screen operation takes place in order to apply a terminal
area 18 in association with each of the interconnection areas such
as the right hand end portions 16--16. These terminal areas 18--18
are formed from a silver ceramic material. The silver ceramic material
is applied in a conventional manner through a silk screen printing
operation. A low resistance, conductive silver paste is applied
through a suitable silk screen. As it passes through this screen,
it adheres to the sheet of glass 12 or underlying areas of an associated
one of the interconnection areas such as the right hand end portions
16--16. In accordance with the teachings of the preferred embodiment,
the silver ceramic silk screening operation is the second silk screening
option. However, the silk screening operations may be reversed,
as will be discussed in greater detail hereinbelow.
Typical of low resistance, conductive silver paste that may be
used are Drakefield Silver Paste, A653, or Englehard Hanovia Silver
Paste, 9124, both commercially available. The conductive silver
paste contains finely divided particles of silver milled in squeegy
oil and other organic additives and ceramic materials to facilitate
silk screening of the paste. The additives burn out during the firing
of the device.
After the two silk screening operations have been carried out,
the sheet of glass 12 and the silk screened areas of both the nonprecious
metal and the silver ceramic material applied thereto are heated
to a temperature in the range of about 600.degree. C. to 625.degree.
C. from four to five minutes in a tempering furnace. This temperature
is above the strain point of the glass. During the heating of the
glass, the nonprecious metal particles and silver ceramic particles
bond to the glass by a bond which is believed to be in part chemical
and in part mechanical. The glass sheet is subsequently cooled at
a rapid rate to room temperature in order to temper the same and
produce a tempered sheet of glass having both the nonprecious metal
and the silver ceramic material bonded thereto.
In accordance with the teachings of a preferred embodiment of this
invention, a power termination area 20 of a silver ceramic material
may be formed at both the right hand side of the glass sheet as
shown in FIG. 1 and at the left hand side of the glass sheet, not
numbered, at the same time as the terminal areas are formed. The
power termination area is used if one desires to make a two-lead
connection from the thin lines 14--14 to the power supplying electrical
system of the vehicle. This type of termination area will be discussed
in greater detail hereinbelow.
Each of the terminal areas 18--18 on the right hand side of the
sheet of glass 12 are interconnected by an electrical lead 22. This
electrical lead can be in the form of a braided copper strip having
a coating of solder thereover. This is in accordance with the teachings
of the preferred embodiment of this invention as set forth herein.
The electrical lead 22 is connected to the terminal areas 18--18
by applying heat to the electrical lead in a location in association
with the terminal areas 18--18 in order to develop a solder bond
24 therebetween. This manner of connecting an electrical lead to
terminal areas of silver ceramic material is well known in the art.
In accordance with the preferred embodiment disclosed herein, as
is best shown in FIG. 3, the electrical lead 22 is also bonded by
means of solder bond 26 to the power termination area 20. This condition
would exist on both the right hand side of the glass sheet 12 and
the left hand side of the glass sheet. A power terminal 28 is connected
by means of a copper tab 30 and a solder bond 32 to the power termination
area 20. In this manner, electrical energy may be supplied through
the power terminal 28 from the electrical generation system of the
automobile to the electrical lead 22, which is in turn electrically
interconnected to the plurality of thin lines 14--14 by means of
the interconnection areas, the right hand end portions 16--16 being
numbered in FIG. 1. Thus, when the backlite becomes clouded by fog
or ice, the vehicle operator turns on the appropriate switch, permitting
electrical energy to flow through the plurality of thin lines 14--14.
Because these lines do have an electrical resistance, the passage
of electrical energy therethrough generates the required heat to
effect a defogging or deicing of the backlite.
If one desires, the electrical lead 22 may be coupled directly
to the power terminal 28 and the power termination area on both
sides of the thin lines 14--14 may be eliminated.
As described, the role of silk screen printing the nonprecious
metal and the silver ceramic material may be interchanged. If this
is carried out, the interconnection areas will, as demonstrated
by a right hand end portion thereof 16 in FIG. 4, overlie a portion
of the terminal area of silver ceramic material 18 as the silver
ceramic material will be the first applied to the surface of the
glass sheet in the silk screening operations.
As an additional matter, I prefer that each of the terminal areas
18--18 of silver ceramic material associated with each of the interconnection
areas such as the right hand end portion 16--16 be in two portions.
A first portion of the terminal area is in contact with an associated
interconnection area and a second portion of the terminal area is
bonded to the surface of the glass sheet 12 and not in contact with
the associated interconnection area. I then desire that the electrical
lead 22 be bonded to the second portion of each of the terminal
areas. I prefer this construction because a very reliable solder
joint can be made when the silver ceramic is directly printed on
the base glass. However, if one desires, the termination of the
electrical lead to the terminal area may be made at a location at
which the terminal area overlies the interconnection area.
While, in the preferred embodiment, there has been illustrated
a soldering operation as a method for attaching the various leads,
it is understood that other bonding operations such as electrically
conductive adhesives may be used in order to bond the leads to the
various terminal areas.
While particular embodiments of the invention have been illustrated
and described, it will be obvious to those skilled in the art that
various changes and modifications may be made without departing
from the invention, and it is intended to cover in the appended
claims all such modifications and equivalents as fall within the
true spirit and scope of this invention.
|