Information
-
Patent Grant
-
6480672
-
Patent Number
6,480,672
-
Date Filed
Wednesday, March 7, 200123 years ago
-
Date Issued
Tuesday, November 12, 200221 years ago
-
Inventors
-
Original Assignees
-
Examiners
Agents
- Hoffman & Baron, LLP
- Marino; Francis E.
-
CPC
-
US Classifications
Field of Search
US
- 392 363
- 392 360
- 392 435
- 392 438
- 392 439
- 392 432
- D23 332
- D23 335
- D23 341
- D23 317
- 219 537
- 219 539
- 219 255
- 338 293
- 338 290
- 338 292
- 338 287
-
International Classifications
-
Abstract
A heater includes a housing having an outer surface and sidewalls defining an interior space that holds a heating element. The heater further includes a heating element having a lower portion and an upper portion, where the heating element has differing power densities from the lower portion to the upper portion. The heating element includes a heat shield positioned in substantially parallel relation to the heating element to create a duct where air may travel through. The heater is provided with an air displacement device positioned adjacent to the heating element to create a planar flow of air through the duct. The heater may be controlled by a control circuit having a circuit board, which controls the power supplied to the heating element and the air displacement device.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a portable electric heater, and more particularly to a improved flat panel heater having a flat panel heating element with a plurality of heating zones creating an efficient heating utilizing a planar air flow over the heating element.
2. Description of the Prior Art
Portable electric heaters are commonly used in many offices and households. Portable electric heaters in general are well known in the art and commonly used. Prior designs of heaters typically involve using a forced air system where a heating coil or other resistance type wire is used to supply heat after a current is passed through it. A fan is located adjacent the heating coil to blow air over the heated coil, thereby warming the air.
U.S. Pat. No. 5,655,055 to Goldstein et al. discloses a heater having a cylindrical housing with a fan blade positioned on the bottom of the housing below a heating element. Goldstein et al. discloses that the fan will blow air upward in a forced manner past the heating element through the housing and then through vents out of the housing. The air would become heated by passing over the heating element.
However, one disadvantage of heaters designed in this manner is that the heating element must become extremely hot in order to sufficiently heat the air moving past it, since the air is only passing over the heating element for a brief period of time. In addition, another disadvantage to this design is that the forced air from the fan may not flow evenly over the heating element, therefore the heating element is not cooled at an even rate creating an inefficient heater.
To address both problems, flat panel heaters have been created to provide a more even heat flow from the heating element itself. These flat panel heaters are typically shaped in large rectangular shapes and are heated so that the air immediately adjacent to the flat panel heater is heated. U.S. Pat. No. 6,134,386 to O'Donnell discloses a flat panel heater. The heater disclosed has a plurality of coils running beneath the surface of the flat panel heater which heats the top surface of the flat panel heater. The heating coils underneath the top surface heat the entire top of the flat panel heater thereby increasing the amount of air that is warmed immediately adjacent to the heater. One disadvantage of this design is that the flat panel heater only heats the air which is immediately adjacent to the flat panel heater itself, thus should the air be stagnant, very little volume of air is heated.
Therefore, in view of the prior art it would be desirable to have a heater which efficiently and evenly cools the heating element.
It would further be desirable to have a portable electric heater which creates an even flow of warm air being discharged from the unit.
OBJECTS AND SUMMARY OF THE INVENTION
It is an object of the present invention to provide a heater having an efficient heating element.
It is an object of the present invention to provide a flat panel heater having a heating element with a plurality of heating zones.
It is another object of the present invention to provide a heater having a planar and homogeneous air flow to provide even cooling of the heating element.
According to the heater of the present invention, the heater includes a housing having sidewalls defining an interior space that holds a heating element. The heating element is preferably in the form of a flat panel having a lower portion and an upper portion, wherein the heating element has differing power densities from the lower portion to the upper portion. The heater also includes a heat shield positioned in substantially parallel relation to the heating element to create a duct for directing air flow therethrough. To move the air over the heating element, the heater is provided with an air displacement device positioned adjacent to the heating element providing a planar flow of air through the duct. The heater may be controlled by a control circuit having a circuit board, which controls the power supplied to the heating element and the air displacement device.
In the preferred embodiment of the present invention, the air displacement device is a fan having a fan housing holding a motor connected by a shaft to at least one fan blade rotatably mounted to the motor. The fan housing may have an outlet directed toward the duct and an inlet for drawing air into the fan. The fan preferably uses a first squirrel cage fan blade positioned in linear alignment with a second squirrel cage fan blade so that a single motor may be used to rotate both fan blades. The squirrel cage fan blade is positioned so that air exiting the fan is directed into the duct. Some of the air may flow over the front face of the heating element opposite the duct.
The heating element is preferably made of a heat conductive material such as steel and is substantially flat and has a rectangular shape. The heating element is preferably positioned in a substantially vertical orientation within the heater housing and the axis of rotation of the fan blade is substantially perpendicular to the longitudinal axis of the heating element. The heating element may use an electrical resistance element which is attached to the heating element to create the power density. The electrical resistance element is preferably a continuous resistance wire made of an electrically conductive material, such as copper, that releases heat when a current is passed through it. The continuous resistance wire may be positioned on the heating element in an “S” curve configuration so that the element is spaced closer to itself on the lower portion of said heating element and is spaced a distance further apart on the upper portion of the heating element, thereby creating differing heating zones in the heating element. Preferably there is a first resistance wire and a second resistance wire positioned in parallel relationship to each other and power to the heating element is controlled by the electronic control circuit.
An advantage of the present invention is that the heating element has differing different heating zones thereby increasing the output efficiency of the heater. The bottom of the heating element is heated at a higher rate so that the high speed air at ambient temperature drawn in by the fan and directed over the heating element will be heated quickly by the higher power heating element portion at the lower end of the heating element. After passing over the lower portion, the now slower moving air passes over the upper portion and will stay in contact with the heating element a longer amount of time than it did at the lower portion. Therefore, the upper portion does not have to be as hot as the lower portion to sufficiently heat the air. The air will then pass over the upper portion and flow out of the duct into the space to be heated.
A further advantage of the present invention is that the air which exits the fan is directed in a substantially planar manner over the heating element so that its surface is cooled at a substantially even rate. The combination of the duct and the varying power density of the heating element create an environment where the heating element is cooled in a homogenous and even rate.
In order to provide a safer heater, the preferred embodiment of the present invention includes a control circuit having a circuit board controlling the current supplied to the heating element and the motor. The control circuit may include a current limiting sensor and a thermister to both prevent the heating element from over-heating and limit the amount of heat produced by the heater. The circuit board also includes a power light to alert the user when the heater is activated. In addition, a tip over switch may be mounted to heater, so that if the heater were to tip over, it would automatically shut off the fan and the heating element.
A preferred form of the portable electric heater, as well as other embodiments, objects, features and advantages of the present invention will be apparent from the following detailed description of illustrative embodiments thereof, which will be read in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is a top perspective view of the present invention;
FIG. 2
is an exploded perspective view of the present invention;
FIG. 3
is a cross-section of the present invention taken along line
3
—
3
of
FIG. 1
;
FIG. 4
is a top perspective view of the heating element; and
FIG. 5
is a circuit schematic for the present invention.
DETAILED DESCRIPTION OF THE INVENTION
As illustrated in
FIGS. 1-3
, a portable electric heater
10
formed in accordance with the present invention includes a housing
12
having a free standing base
20
, a heating element
30
which is supported by the housing
12
and an air displacement device
62
for moving air over to the heating element
30
. The housing
12
is preferably hollow having an interior space
14
with mounting braces
22
for supporting the heating element
30
inside the housing
12
. In the preferred embodiment, the heating element
30
has a substantially flat panel configuration in a rectangular shape. The flat panel heating element
30
may be positioned in the housing
12
so that the longitudinal axis of the heating element
30
is in a substantially vertical position with the air displacement device
62
positioned below the heating element
30
.
The flat panel heating element
30
may be attached to the housing
12
using a plurality of mounting braces
22
. In the preferred embodiment the mounting braces
22
are made of a heat resistant material, and may comprise a series of posts which are attached to the four corners of the rectangular heating element
30
. The heating element
30
is preferably positioned so that its longer dimension or its longitudinal axis is in a substantially vertical position. It is contemplated, however, that the flat panel heating element could also be oriented in a horizontal manner. In such an embodiment, the management of the heating element could also be re-oriented so that a higher power density is provided at a lower portion of the heating element closest to the fan.
In the preferred embodiment, positioned behind the heating element
30
in substantially parallel thereto is a heat shield
50
having a similar size and shape to the flat panel heating element
30
and creating an air space
55
therebetween. More specifically, the heat shield
50
is positioned spaced from the heating element to form a duct
56
which air may flow through. The heat shield
50
may be made of a metallic material or any other material which reflects heat. The heat shield
50
of the preferred embodiment has a back portion
52
with two sidewalls
54
extending substantially perpendicular from the back portion
52
. Preferably the sidewalls
54
terminate in close proximity to or may contact the heating element
30
thereby creating the duct
56
. The duct
56
has a duct inlet
58
defined by the lower edge
38
of the heating element
30
and the heat shield
50
, and a duct outlet
60
defined by the upper edge
42
of the heating element
30
and heat shield
50
. The heat shield
50
forming the duct
56
is directed toward the front of the housing after it reaches the upper edge
42
of the heating element
30
. The duct
56
is then connected to an opening
16
on the front face
11
of the housing
12
to complete the duct outlet
60
.
An air displacement device
62
is preferably positioned below the heating element
30
. In the preferred embodiment the air displacement device
62
is a fan assembly
64
having a fan housing
66
with an interior space
70
defined by an outer sidewall
68
, a motor
78
positioned in the fan interior space
70
and at least one fan blade
82
rotatably connected to a shaft of the motor
78
. The fan housing
66
is used to add structural rigidity to the fan assembly
64
and to direct the flow of air created by the fan assembly
64
. The fan housing
66
may have a fan inlet opening
74
which corresponds to a inlet opening
24
on the side wall
26
of the heater
10
to allow air to flow into the fan assembly
64
, and a fan housing outlet
76
where the fan assembly
64
then expels the air. The fan outlet
76
is preferably positioned below the duct inlet
58
so that air exiting the fan outlet
76
may blow air into the duct
56
so that it may then travel up through the duct
56
and over the surface of the flat panel heating element
30
to the duct outlet
60
. Preferably, the majority of the air exiting the fan outlet
76
will be directed into the duct
56
, however, it is envisioned that some of the air exiting the fan outlet
76
will travel up the front surface
32
of the heating element
30
opposite the duct
56
.
Referring to
FIG. 1
, the present invention preferably has a motor
78
positioned in the center of the fan interior space
70
. The motor
78
preferably has a first shaft
80
and a second shaft
81
extending outward from the motor
78
connected to a first
82
and second fan blade
83
positioned on opposite sides of the motor
78
in linear alignment with each other. In the preferred embodiment, the fan blades are squirrel cage fan blades
84
which are positioned inside the fan interior space
70
. Squirrel cage fan blades
84
typically have a cylindrical configuration with an inner surface
86
and an outer surface
88
. Air enters the inner surface
86
of the squirrel cage fan blade
84
as it is rotating and is then displaced in a outward direction from its axis of rotation past the outer surface
88
of the squirrel cage fan blade
84
. The fan outlet
76
is preferably positioned on the top of the fan housing
66
to direct the air from the squirrel cage fan blade
84
into the duct inlet
58
. The fan interior space
70
may have an inner surface
72
which is contoured to follow the outer surface
88
of the squirrel cage fan blade
84
so that the air displaced by the fan blade
82
is directed toward the fan outlet
76
and into the duct
56
. The axis of rotation of the fan blades
82
is preferably substantially perpendicular to the longitudinal axis of the heating element
30
to further focus the air to flow over evenly over the heating element
30
.
An advantage to using the squirrel cage fan blades
84
in the present invention is that the air flow upon exiting the fan housing
66
is substantially focused creating a planar and homogeneous air flow over the heating element
30
thereby increasing the heater's efficiency.
The heating element
30
is preferably made of a heat conductive material. In the preferred embodiment the heating element
30
is made from a sheet of rectangular steel which is positioned vertically inside of the housing
12
. The heating element
30
has a front surface
32
and a back surface
34
and a lower portion
36
delimited by a lower edge
38
and an upper portion
40
delimited by an upper edge
42
. In the preferred embodiment, the heating element
30
uses an electrical resistance element
44
positioned on the surface of the heating element
30
that allows that the power density of the heating element
30
to be greater on the lower portion
36
than on the upper portion
40
of the heating element
30
. The increased power density on the lower portion
36
of the heating element
30
causes the lower portion
36
to be heated to a higher temperature than the upper portion
40
of the heating element
30
. The electrical resistance element
44
is preferably made of an electrically conductive material such as a cooper so that when an electrical current is passed through the electrical resistance element
44
, heat will be released.
Referring to
FIG. 4
, the electrical resistance element
44
for the present invention is preferably made of a continuous wire or electrical trace used in the formation of printed circuit boards which runs from the lower portion
36
of the heating element
30
to the upper portion
40
of the heating element
30
. The wire or trace is preferably attached to the back surface
34
facing the inside of the duct
56
created by the heating element
30
and the heat shield
50
. The electrical resistance element
44
is preferably positioned on the heating element
30
so that it runs in a substantially horizontal position on the heating element
30
and continues up the heating element
30
in a “S” type configuration to the top of the heating element
30
. The power density of the electrical resistance element
44
is varied by having the individual “S” curves of the resistance element placed in a close parallel relationship, distance D
1
, to each other on the lower portion
36
of the heating element
30
. The “S” curves of the wires are gradually spaced farther away from each other as the wire is positioned higher on the heating element
30
, distance D
2
, thereby decreasing the power density on the upper portion
40
. In the preferred embodiment there will be two parallel wires, namely, a low heat element
46
and a high heat element
48
positioned next to each other following the same path so that should the user wish to increase the amount of heat produced by the heating element
30
when the low heat element
46
is activated, the high heat element
48
may be activated to create a higher power density to create more heat.
One of the advantages of the present design is that the heating element
30
has at least two different heating zones to further increase the efficiency of the heater. It is contemplated that more than two power densities may be formed on the heating element to achieve even greater efficiency of operation. The bottom of the heating element
30
is heated at a higher rate so that the high speed air at ambient temperature which is immediately exiting the fan assembly
64
will be heated quickly by the higher heat at the lower portion
36
of the heating element
30
. As the air passes over the lower portion
36
, it will be heated and then travel upward to the upper portion
40
of the heating element
30
.
After passing over the lower portion
36
, the air will then pass over the upper portion
40
of the heating element
30
. The air will be moving slower over the upper portion
40
since it is now a further distance away from the fan assembly
64
and will stay in contact with the heating element
30
a longer amount of time than it did at the lower portion
36
of the heating element
30
. The heating element upper portion
40
does not have to be as hot as the lower portion
36
to sufficiently heat the air, since the air will stay in contact longer with the upper portion
40
. The air will then pass over the upper portion
40
of the heating element
30
and flow out of the duct outlet
60
to the front of the heater.
An advantage of using a heat shield
50
behind the heating element
30
is that the air which passes through the duct
56
is directed to travel straight through the duct
56
thereby increasing the amount of time the air contacts the heating element
30
. The heat shield
50
also provides insulation against the heat escaping out of the air directing its travel through the duct. Another advantage of the present invention is that the air which exits the fan assembly
64
is directed in a substantially planar manner over the entire heating element
30
so that its surface is cooled at a substantially even rate. Preferably the majority of the air passes through the duct
56
, however, it is envisioned that some air may flow over the front surface
32
of the heating element
30
. Although, the air which is flowing past the front face surface
32
of the heating element
30
is not directed in the same manner as the air through the duct
56
, it will nevertheless assist in evenly cooling the heating element
30
. The combination of the duct
56
and the varying power density of the heating element
30
create a heater
10
with a heating element
30
that is cooled in a homogenous and even rate.
The housing
12
of the heater
10
is preferably constructed so that the front face
11
has an opening
16
which is positioned in front of the heating element
30
. In the preferred embodiment, the opening has a rectangular shape that is the same size as the heating element
30
. The opening in the front face of the housing may have a grill covering
18
with a plurality of holes in it so that air which flows over the front face of the heating element
30
may be allowed to exit out the front of the housing. The air exiting the duct outlet
60
preferably flows out of a top portion
15
of the grill covering
18
. The air inlets for the fan
24
are preferably positioned on the sidewalls
26
of the housing
12
and are perforated grills which allow air to freely flow through. The air inlets
24
on the sidewalls
26
are preferably positioned over the squirrel cage fan blades
84
, thus the fan blades
84
can draw air through the air inlets
24
into the center of the fan blade
84
and then push the air to the outer surface
88
of the fan blade
84
and through the fan housing outlet
76
.
The heating element
30
may be controlled by a control circuit
100
as shown in FIG.
5
. The control circuit
100
may include a printed circuit board
102
to control the current supplied to the low heat element
46
and the high heat element
48
. Preferably the printed circuit board
102
may include a microprocessor. The low heat element
46
and the high heat element
48
are preferably connected in parallel to each other and may be independently controlled by the circuit board
102
independent of each other. A current limiting sensor
103
may be used in conjunction with high heat element
48
to prevent the high heat element
48
from over heating. The circuit board
102
may also control the motor
78
of the fan assembly
64
and may include a power light
106
to alert the user that the heater is activated. Referring to
FIGS. 2 and 5
, a thermister
108
may be attached to the heating element
30
to regulate the amount of heat that is produced by the heater
10
. Thermisters
108
are well known to those of ordinary skill in the art and do not need to be described in detail. The control circuit
100
may also include a photodiode
112
and a PTC switch
114
which are well known in the art. In addition, a tip-over switch
110
may be internally mounted to the heat shield
50
by a mounting bracket
28
such that if the heater
10
were to tip over, it would automatically shut off the fan assembly
64
and the heating element
30
.
Although the illustrative embodiments of the present invention have been described herein with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precis embodiments, and the various other changes and modifications may be effected therein by one skilled in the art without the departing from the scope or spirit of the invention.
Claims
- 1. A portable electric heater comprising:a housing having an interior space; a flat panel heating element oriented in a substantially vertical plane and having a vertical axis associated therewith; and a fan assembly, said fan assembly including a motor having a shaft attached to a fan blade, wherein the axis of rotation of the fan blade is substantially perpendicular to said vertical axis of the flat panel heating element and further wherein said axis of rotation of said fan blade is in substantially parallel plane to said vertical plane of said flat panel heating element.
- 2. A portable heater as defined in claim 1, wherein said fan assembly further includes a first squirrel cage fan blade positioned in linear alignment with a second squirrel cage fan blade, said second squirrel cage fan blade being rotatably mounted on an opposite side of said motor than the first squirrel cage fan blade.
- 3. A portable heater as defined in claim 2, wherein said flat panel heating element is positioned in said interior space of said housing, said heating element having a front face and a back face, and a lower portion and an upper portion, said heating element having differing power densities from the lower portion to the upper portion; anda heat shield positioned in substantially parallel relation to said heating element, whereby air travels through a duct formed by said heating element and said heat shield, said duct having a duct inlet and a duct outlet.
- 4. A portable heater as defined in claim 3, wherein said fan assembly creates a planar flow of air which travels adjacent said heating panel in said duct.
- 5. A portable heater as defined in claim 4, wherein said flat panel heating element includes at least a first portion having a first power density and a second portion having a second power density.
- 6. A portable heater comprising:a housing having an outer surface and sidewalls defining an interior space; a flat panel heating element positioned in said interior space of said housing and oriented in a substantially vertical plane, said heating element having a front face and a back face, and a lower portion and an upper portion, said heating element having differing power densities from the lower portion to the upper portion; a heat shield positioned in substantially parallel relation to said heating element, whereby air travels through a duct formed by said heating element and said heat shield, said duct having a duct inlet and a duct outlet; an air displacement device positioned adjacent to said heating element, said air displacement device creating a planar flow of air which travels adjacent and substantially parallel to said vertical plane of said heating panel in said duct, said air displacement device comprising a fan assembly including a motor having a shaft attached to a fan blade, wherein the axis of rotation of the fan blade is substantially perpendicular to said vertical axis of the flat panel heating element and further wherein said axis of rotation of the fan blade is in a substantially parallel plane to said vertical plane of said flat panel heating element; and a control circuit electrically coupled to the heating element to control power supplied to said heating element and said air displacement device.
- 7. A portable heater as defined in claim 6, wherein said fan assembly further includes:a fan housing having an outer sidewall defining a fan interior space; a motor positioned in said fan interior space; and at least one fan blade rotatably mounted to said motor by a shaft.
- 8. A portable heater as defined in claim 7, wherein said at least one fan blade is a squirrel cage fan blade, said squirrel cage fan blade having an inner and an outer surface.
- 9. A portable heater as defined in claim 8, wherein said fan housing further includes an interior surface, said interior surface is shaped to closely follow the outer surface of said squirrel cage fan blade.
- 10. A portable heater as defined in claim 9, wherein said fan housing has an inlet to allow air to flow into said inner surface of said squirrel cage fan blade, and a fan outlet positioned on a top surface of said fan housing to expel air from said fan housing.
- 11. A portable heater as defined in claim 7, wherein said fan further includes a first squirrel cage fan blade positioned in linear alignment with a second squirrel cage fan blade, said second squirrel cage fan blade being rotatably mounted on an opposite side of said motor than the first squirrel cage fan blade.
- 12. A portable heater as defined in claim 7, wherein the axis of rotation of said fan blade is substantially perpendicular to a longitudinal axis of said flat panel heating element.
- 13. A portable heater as defined in claim 12, wherein an electrical resistance element is attached to said heating element to create said power density.
- 14. A portable heater as defined in claim 13, wherein said electrical resistance element is at least one continuous resistance wire attached to said heating element.
- 15. A portable heater as defined in claim 13, wherein said at least one continuous resistance wire is positioned on said back surface of said heating element in an “S” curve configuration.
- 16. A portable heater as defined in claim 15, wherein said “S” curve configuration of said at least one continuous resistance wire is spaced closer to each other on the lower portion of said heating element and are spaced a distance further apart on the upper portion of said heating element.
- 17. A portable heater as defined in claim 16, wherein said electrical resistance element has a first resistance wire and a second resistance wire, said first and second resistance wire being positioned adjacent to each other and arranged in parallel electrical relationship.
- 18. A portable heater as defined in claim 17, wherein said heater further includes an electrical control circuit including:a circuit board; a thermistor attached to said heating element and controlled by said circuit board; a tip over switch connected to said housing, wherein the electric current to said heating element and said fan will be terminated should the heater activate said switch.
- 19. A portable heater as defined in claim 6, wherein said fan assembly is positioned so that air exiting the fan outlet is directed into said duct inlet and a portion of the air exiting the fan outlet will be directed to flow over the front face of said heating element.
- 20. A portable heater as defined in claim 6, wherein said heating element has a substantially rectangular shape having a longitudinal axis.
- 21. A portable heater as defined in claim 20, wherein said longitudinal axis of said heating element is positioned in a substantially vertical position in said housing.
- 22. A portable heater comprising:a housing having an outer surface and sidewalls defining an interior space; a flat panel heating element positioned in said interior space of said housing, such heating element having a front face and back face and a lower portion and a upper portion, said heating element having different power densities from the lower portion to the upper portion and said front surface and said back surface of said heating panel defining a vertical plane and having a vertical axis associated therewith; a heat shield positioned in substantially parallel relation to said heating element, whereby air travels through a duct formed by said heating element and said heat shield, said duct having a duct inlet and a duct outlet; an air displacement device positioned adjacent to said heating element, said air displacement device creating a planar flow of air which travels adjacent and substantially parallel to said first plane of said heating element in said duct, wherein said air displacement device is a motor having a fan blade wherein an axis rotation of said fan is positioned perpendicular to the vertical axis of said heating element and said axis of rotation is in substantially parallel plane as said vertical plane of said flat panel heating element; and a control circuit electrically coupled to the heating element to control power supplied to said heating element and said air displacement device.
- 23. A portable heater comprising:a housing having an outer surface and sidewalls defining an interior space; a flat panel heating element positioned in said interior space of said housing and oriented in a first plane and defining a first longitudinal axis of said heating element; an air duct having an inlet and an outlet, wherein said heating element is positioned within said air duct, whereby air travels through the duct from said inlet to said outlet; an air displacement device positioned adjacent to said heating element, said air displacement device creating a substantially planar flow of air which travels along said first plane of said heating panel in said air duct, said air displacement device comprising a fan assembly including a motor having a shaft attached to a fan blade, wherein the axis of rotation of the fan blade is substantially perpendicular to said first longitudinal axis of the flat panel heating element and further wherein said axis of rotation of the fan blade is in a substantially parallel plane to said first plane of said flat panel heating element; and a control circuit electrically coupled to the heating element to control power supplied to said heating element and said air displacement device.
US Referenced Citations (20)
Foreign Referenced Citations (3)
Number |
Date |
Country |
2616289 |
Dec 1988 |
FR |
786577 |
Nov 1957 |
GB |
2255262 |
Oct 1992 |
GB |