ENSEMBLE DE FENETRE POUR PORTE DE FOUR

SELF CONTAINED WINDOW UNIT FOR OVEN DOORS (COMMON CAVITY)

Abrégé anglais

ABSTRACT OF THE DISCLOSURE
A self-contained window unit adapted to be
assembled into an oven door, having three glass panes
and a microwave shield. Two of the glass panes are held
in spaced parallel relation by a frame of electrically-
conducting material which has a peripheral mounting
flange in electrical contact with the edge of the micro-
wave shield. The third pane is secured to the frame by
a plurality of individual mounting clips. Fasteners
around the four sides of the window unit secure the
mounting flange to the door to both mount the window
unit and ground the microwave shield.

Revendications

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A self contained window unit adapted to be
assembled into an oven door having front and back panels
with aligned window openings therein and means defining an
air passage to allow air to flow upwardly through the door
and window unit therein, comprising a window sub-assebly
having a pair of glass panes, means to hold said panes in
spaced parallel relation, a third glass pane, and means
for securing said third glass pane to said window sub-
assembly in a position at one side thereof and in spaced
parallel relation to the adjacent glass pane of said sub-
assembly, said securing means providing areas between said
third pane and said adjacent pane of said sub-assembly at
the top and bottom of said window unit defining an opening
adapted to communicate with the air passage in the door to
allow the air to flow upwardly therebetween, said holding
means comprising a frame of electrically-conducting
material extending about the peripheries of said pair of
panes and having a mounting flange, a microwave shield
having an edge portion in surface-to-surface electrical
contact with said flange, and means for securing said
flange to one of said door panels to mount said window
unit and ground said shield.
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2. The self-contained window unit defined in
Claim 1, wherein said means for securing said flange com-
prises fasteners provided at spaced points along said
flange.
3. The self contained window unit defined in
Claim 1, wherein said means for securing said third pane
to said window sub-assembly comprises a plurality of
spaced mounting clips.
4. The self-contained window unit defined in
Claim 3, wherein said mounting clips include bottom and
side clips at the bottom and side edges of said window
unit engaging peripheral portions of said third pane.
5. The self-contained window unit defined in
Claim 4, wherein each bottom and side clip has a part ex-
tending over the peripheral edge of said third pane and
inner and outer flanges extending over the inner and
outer peripheral surfaces respectively of said third pane.
6. The self-contained window unit defined in
Claim 4, wherein said mounting clips include at least one
top clip at the top of said window unit engaging a top
peripheral portion of said third pane.
7. The self-contained window unit defined in
Claim 6, said top clip having a flange extending over the
inner peripheral surface of said third pane,said top clip
also having a terminal part extending over the peripheral
edge of said third pane but not appreciably therebeyond so
as normally to releasably hold said third pane against
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upward movement but permitting said third pane to be
pressed outwardly clear of said terminal part for upward
removal.
8. The self-contained window unit defined in
Claim 1, wherein said mounting flange extends laterally
outwardly beyond said pair of glass panes about sub-
stantially the entire peripheries thereof, said edge
portion of said microwave shield about substantially the
entire periphery thereof being in electrical contact with
said flange, and said means for securing said flange com-
prises metal fasteners provided at spaced points along
the peripheral extent of said flange.
9. The self-contained window unit defined in
Claim 1, wherein said frame is generally channel-shaped
in cross section having a base extending across the space
between said pair of glass panes and laterally inwardly ex-
tending retaining flanges engaging the outer peripheral sur-
faces thereof, said base being divided into front and rear
portions by an integral generally U-shaped section extend-
ing laterally outwardly beyond said pair of glass panes
about substantially the entire periphery thereof and con-
stituting said mounting flange, the edge portion of said
microwave shield extending into said U-shaped section,
and said means for securing said mounting flange to one
of said door panels comprising metal fasteners clamping
said edge portion of said microwave shield within said
U-shaped section.
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10. The self-contained window unit defined in
Claim 9, wherein the width of the space within said U-shaped
section in its free state condition is greater than the
thickness of said shield,said fasteners compressing said
U-shaped section into clamping engagement with the edge
portion of said shield and also drawing said retaining
flanges into pressure contact with the outer peripheral
surfaces of said pair of glass panes.
11. The self-contained window unit defined in
Claim 3, wherein said mounting clips include top, bottom
and side clips at the top, bottom and side edges of said
window unit engaging peripheral portions of said third
pane.
12. The self-contained window unit defined in
Claim 11, said top clip having a flange extending over the
inner peripheral surface of said third pane, said top clip
having a terminal part extending part way only over the
peripheral edge of said third pane so as normally to re-
leasably hold said third pane against upward movement but
permitting said third pane to be pressed outwardly clear
of said terminal part for upward removal.
13. A self-contained window unit adapted to be
assembled into an oven door having front and back panels with
aligned window openings therein and means defining an air
passage to allow air to flow upwardly through the door and
window unit therein, comprising a window sub-assembly having
a pair of glass panes, means to hold said panes in spaced
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parallel relation, a third glass pane, and means for
securing said third glass pane to said window sub-assembly
in a position at one side thereof and in spaced parallel
relation to the adjacent glass pane of said sub-assembly,
said securing means providing areas between said third pane
and said adjacent pane of said sub-assembly at the top and
bottom of said window unit defining an opening adapted to
communicate with the air passage in the door to allow the
air to flow upwardly therebetween, said holding means com-
prising a frame of electrically-conducting material extend-
ing about the peripheries of said pair of panes and having a
mounting flange, a microwave shield extending parallel to
said pair of panes and having an edge portion overlying
said mounting flange, and means for clamping said edge
portion of said shield and said flange together and for
securing said flange to one of said door panels to both
mount said window unit and ground said microwave shield.
14. An oven door having front and back panels
with aligned window openings therein and means defining an
air passage to allow air to flow upwardly through the door,
a self-contained window unit mounted in said door between
said panels in register with the openings therein including
a window sub-assembly having a pair of glass panes,means to
hold said panes in spaced parallel relation, a third glass
pane, means for securing said third glass pane to said
window sub-assembly in a position at one side thereof and
in spaced parallel relation to the adjacent glass pane of
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said sub-assembly, said securing means providing areas be-
tween said third pane and said adjacent pane of said sub-
assembly at the top and bottom of said window unit de-
fining an opening adapted to communicate with the air
passage in the door to allow the air to flow upwardly
therebetween, and a fourth glass pane mounted on one of
the door panels in register with the window opening therein
and in spaced relation to said third glass pane to provide
an opening therebetween communicating with the air passage
in the door to allow the air to flow upwardly therethrough.
15. The self-contained window unit defined in
Claim 14, wherein said securing means for said third glass
pane comprises a plurality of spaced mounting clips.
16. The oven door defined in claim 15, wherein
said mounting clips include bottom and side clips at the
bottom and side edges of said window unit engaging peripheral
portions of said third pane.
17. The oven door defined in Claim 14, wherein
said holding means comprises a frame of electrically con-
ductive material extending about the peripheries of said
pair of panes and having a mounting flange, a micro-
wave shield having an edge portion in surface-to-surface
electrical contact with said flange, and means for securing
said flange to one of said door panels to mount said window
unit and ground said shield.
18. The oven door defined in claim 17, wherein
said mounting flange extends laterally outwardly beyond
said pair of glass panes about substantially the entire
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peripheries thereof, said edge portion of said microwave
shield about substantially the entire periphery thereof
being in electrical contact with said flange, and said
means for securing said flange comprises metal fasteners
provided at spaced points along the peripheral extent of
said flange.
19. The oven door defined in Claim 17, wherein
said frame is generally channel-shaped in cross section
having a base extending across the space between said
pair of glass panes and laterally inwardly extending re-
taining flanges engaging the outer peripheral surfaces
thereof, said base being divided into front and rear portions
by an integral generally U-shaped section extending laterally
outwardly beyond said pair of glass panes about substantially
the entire periphery thereof and constituting said mounting
flange, the edge portion of said microwave shield extending
into said U-shaped section, and said means for securing said
mounting flange to one of said door panels comprising metal
fasteners clamping said edge portion of said microwave
shield within said U-shaped section.
20. The oven door defined in Claim 19, wherein
the width of the space within said U-shaped section in its
free state condition is greater than the thickness of said
shield, said fasteners compressing said U-shaped section
into clamping engagement with the edge portion of said shield
and also drawing said retaining flanges into pressure contact
with the outer peripheral surfaces of said pair of glass
panes.
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Description

S P E C I F I C A _ I O ~
This invention relates to a self-con-tained three-
pane window unit which is equipped with a microwave shield
and is thus particularly adapted for use in a microwave oven.
In accordance with the construction to be described, a
self-contained window unit for an oven door comprises a window
sub-assembly having a pair of glass panes, means to hold the
panes in spaced parallel relation, and means for securing
a third glass pane to the sub-assembly in a position at one
side thereof and in spaced parallel relation to the adjacent
glass pane or -the sub-assembly. The securing means provides
areas between third pane and the adjacent pane of the sub-
assembly at the top and bottom of the window unit defining
an opening adapted to communicate with an air passage in
the door. The holding means comprises a frame of electrically-
conducting material extending about the peripheries of the
pair of panes and having a mounting flange. A microwave shield
has an edge portion in surface-to-surface ele~trical contact
with the mounting flange, and means are provided for securing
~0 the flange to one of the door panels to mount the window unit
and ground the shield.
The use of spaced mounting clips for the third
pane of the self-contained window unit minimizes thermal con-
duction and provides for maximum air flow in the spaces be-
tween the clips~
This ~elf-contained window unit is particularly
adapted ~or use in microwave ovens equipped for pyrol~tic

self-cleaning. No other shielding devices are necessary
during the pyrolytic cleaning process.
Other objects and features of this invention will
become more apparent as this description proceeds,especially
when taken in conjunction with the accompanying drawings
wherein:
Fig. 1 is a perspective view with parts broken away
and in section of a self-contained window unit embodying the
invention.
Fig. 2 is a fragmentary vertical sectional view
showing the self-contained window unit of Fig~ 1 mounted in
oven door.
Referring now more particularly to the drawings,
the self-contained window unit 9 comprises a window sub-
assembly 10 having rectangular glass panes 11 and 12 main-
tained in spaced paraliel relationship by a spacer 14 and a
clamping frame 16. A rectangular front glass pane 18 is
secured to the sub-assembly 10 in spaced parallel relation
in front of pane 11 by mounting clips 20 along the top,
bottom and side edges of the window unit.
A rectangular microwave shielcl 22 parallel to and
hetween glass panes 11 and 12 is disposed in surface-to-
surface conkact with the inner face of the pane 12. The
shield is formed of electrically conducting metal and has
nume~o~s perforations of a size to prevent microwave
radiation from passing through but large enough to permit
the oven chamber to be viewed from the outside.
The spacer 14 is a rectangular member of channel

cross section having radially outwardly turned flanges 24 in
contact with the inner peripheral surfaces of the glass pane
11 and the shield 22.
The clamping frame 16 is a rectangular member formed
of electrically conducting metal. The clamping fr~ e is gener-
ally channel shaped in cross section having ~ base 26 extend-
ing ac~oss the space between the glass panes 11 and 12 and
having laterally inwardly extending retaining flanges 28 and
30 along the outer peripheral surfaces of the panes. Speci-
fically, each flange 28,30 has a portion 32 which extends
from the base 26 laterally inwardly along the peripheral
edge portion of the outer surface of the ~djacent glass pane,
and a generally u-shaped terminal portion 34 which opens in-
wardly toward the outer surface of the adjacent glass pane.
A strip of asbestos tape 36 lines the inner surface of the
base 26 as well as the inner surfaces of the retaining flanges
28 and 30 and is clamped in the terminal portions 34 thereof.
The base of the clamping frame 16 on each of the
four sides thereof is divided into front and rear portions 38
and 40 by an integral generally U-shaped section 42 which ex-
tends laterally outwardly beyond the base 26 and constitutes a
mounting flange. This mounting flange 42 extends continuously
along the top, bottom and side edges of the window unit, being
interrupted only at the corners as shown in Fig. 1. The reason
for the corner intexruptions is that the clamping frame is
initially made of a length of stock which is bent into rec-
tangular shape.

The microwave shield 22 is both wider and longer
than the glass panes 11 and 12 so that it extends outward
beyond the peripheries of the glass panes along all four sides.
Thus the peripheral portions of the microwave shield along the
top, bottom and side edges project into the U-shaped mounting
flange 42. The shield cuts through the asbestos tape.
The top, bottom and side portions of the mounting
flange 42 are formed with apertures 44 which extend through
both parts of the ~-shaped section~ The tOpr bottom and side
peripheral edge portions of the microwave shield received in
the mounting -flange are formed with apertures which register
with the apert~res 44 in the mounting flangen These apertures
are for receiving mounting bolts 46.
The window unit is shown installed in an oven door
48 which has a front door panel 50 and a back door panel 52
and an intermediate panel 54 with insul.ating matarial 56 be-
tween the panels 52 and 54. The rear door panel is of elec-
trically conducting metal~ The front panel 50 has an annular
rearwardly turned flange 56 and the rear panel 52 has an
: 20 annular forwardly turned flange 58. The flanges 56 and 58 de-
fine registering apertures constituting the opening of the oven
door in which the window unit 9 is installed. A front glass
pane 60 is clamped to the flange 56 of the front door panel
50 by stops 62 s-ecured to brackets 64 by fasteners 66.
Brackets 64 are secured by any suitable means to the door
panel 50 which may be of porcelain,for example. In place of
the front panal 50 and glass 60, a full glass front may be
employed.

The window unit is mounted in the door within the
opening thereof by means of the bolts 46 and a plurality of
generally Z-shape~ brackets 68. These bolts 46 and brackets
68 are formed oE electrically conducting metal. Each bracket
68 has one leg welded or otherwise permanently secured in
surface-to-surface electrical contact to the inner surface of
the rear door panel 52. The other leg is in full surface
contact with the mounting flange 42 and has a threaded aper-
ture 70. These brackets 68 are arranged around the four sides
of the window opening in the oven door in positions to receive
the mounting bolts 46 which extend through the apertures in
the mounting flange 42 and in the microwave shield 22. The
mounting bolts 46 extend through such apertures and thread
into the apertures 70 in the brackets 68 to securely mount
the window unit to the rear panel of the oven door. The bolt
head bears in electrical contact against one side of the
mounting flange 42 and clamps the mounting flange in el~c-
trical contact with the microwave shield 22 and against the
apertured leg of bracket 68.
It will be understood that before the mounting bolts
46 are applied, the width of the space within the mounting
flange 42 is greater than the thickness of the microwave shield.
Accordingly, when the bolts 46 are tightened to draw the head
of each bolt towaxd the apertured leg of a bracket 68,the
mounting flange 42 is compressed into tight electrical con-
tact with both sides of the pexi?heral portion of the micro-
wave shield, ak the same time drawing the flanges 28 and 30

of the clamping frame 16 toward one another tightly against
the outer surface of the glass panes 11 and 12 and this pro-
vides a substantially rattle-proof assembly. The edges of
the glass panes as well as the outer peripheral surfaces
thereof are contacted by the asbestos tape 36 to cushion
the assembly thereby preventing breakage, and also forming a
seal to keep oven vapors -from escaping.
In use, the mounting by the bolts ~6 and bxacke.ts 68
to the mounting flange a~ points along each of the four sides
of the window unit provides a secure mounting for the window
unit and also grounds the microwave shield at each mounting
po nt. Thus microwave radiation impinging upon the microwave
shield at any point on its surface is immediately dissipated
through the nearest mounting bolt and bracket to the back
panel of the ~oor.
An annular trim riny or moulding 84 of generally
J shape in cross section extends around the outer peripheral
surface of the rear glass pane 12. The trim ring or moulding
8~ has a radially outwardly extending leg 86 which extends
between and contacts the outer peripheral surface of pane 12
and the asbestos tape 36 along a flange portion 32 of the
frame 16. An elongated asbestos cord 88 extends within the
trim ring and seals against the edge of flange 58 of the
inner door panel 52 when the window unit is installed in
the door. Instead of asbestos, the cord may be of fiherglass
or in the form of a silicone extrusion.
The asbestos strip 36 ~ining the flange portions 32
of the frame 16 engages the outer surface of the front panel 11

and the leg 86 of the trim xing 84, and the spacer flanges
24 engage the inner surface of pane 11 and shield 22 to
clamp the window sub-assembly 10 together and -Eorm a sealed
package.
The self-contained window unit 9, as before stated,
includes in addition to the glass panes 11 and 12 a front
glass pane 18 secured ko the sub-assembly 10 by mounting
clips 20 spaced apart along the top, bottom and side edges
of the window unit. One or more of the cl.ips 20 are provided
on each side edge of the window unit and one or more of the
clips 20 are provided along the bottom edga and also along
the top edge thereof. The clips 20 at the top and bottom of
the unit are spaced apart to provide openings communicating
with khe air passage 70 between panels 50 and 54 in the door
to allow air to flow upwardly between panes 11 and 18. Air,
o~ course, also flows upwardly between panes 18 and 60.This
dùal air wash across the pane 18 maximizes the dissipation
o heat, and the use o~ clips to mount the pane 18 minimizes
thermal conduction to pane 18.
Each clip 20 has a plate portion 72 which is
secured to the base 26 of the clamping frame 16 as by means
of integral tabs 74 on the clamping frame. A leg 76 of the
clip 20 projects forwardly from the plate portion 72 across
the peripheral edge of the front pane 18 and has a laterally
inwardl.y turned ~lange 78 extending ove.r the front periph-
sral surface of the front pane 18. A second leg 80 extends
forwardly from the plate portion 72 of clip 20 and termi.nates
:in a laterally inwardly turned flange 82 which extends over
the rear peripheral surface of the pane 18.
--7--

The flanges 78 and 82 of clips 20 clamp the front
pane 18 against forward or rearward movement. The legs 76
of the clips prevent sidewise as well as upward and down-
ward movement of the pane. However, the pane 18 is re-
movable from the assembly by bending one or more of the
clips laterally outwardly to release the pane. This may
or may not result in a deformation of the clips depending
upon the springeness of the material from which they are
made. In some instances, it is desirable to remove the
pane 18 temporarily so that the inner surfaces o~ the panes
11 and 18 may be cleaned. Even if there is some deformation
of the clip flanges resultiny from the release and removal
of the pane 18, these clip flanges may be bent back into
position to retain the cleaned pane 18 after it is re-
assembled into the window unit~
The dot-dash line 85 in Fig. 1 illustrates a modi-
fied clip construction that may, if desired,be employed along
the top edge to make it easier to release and remove the pane
18. In the modified clip cons~ruction, the flange 78 is
omitted and the leg 76 terminates at the line 85 so as to
extend only park way across the top peripheral edge of the
pane 18. In a broad sense, the leg 76 could conceivably ex-
tend entixely across the top edge of the pane 18 and even
slightly although not appreciably therebeyond. Preferably
however, the leg 76 would ~e as shown and termina-te at the
line 85 in the drawings. Use of this modified clip con-
struction along the top permits easier removal of the pane
18~ The pane may be pressed out~ard at the top a distance
sufficient to clear the foreshortened leg 76 and then re-
moved by an upward sliding movementO

The type of glass used for the various panes may
vary depending upon individual preferences and/or appli-
cations. The pane 12 may be of a borosilicate composition
for high temperature applications such, for example, as
ovens equipped for pyrol~tic self-cleaningO The pane 11
may be of tempered glass with or without a heat reflective
coating.
When the self-contained window unit is installed
in the door, the microwave shield is positivel~ grounded to
the door frame. Moreover,use of the unit in conjunction
with a full. or partial glass in the front door panel elim-
inates the need for any additional shieldiny device during
the pyrolytic cleaning process. The clip type mounting of
the pane 18 minimizes thermal conduction and the position
of the pane 18 within the door provides a dual air wash
which maximizes dissipation of heat.
The pane 18 of the self-contained window unit
is removable for cleaning as noted above, after removal of
the front door panel 50 either by swinging it down or by
separating it completely from the inner door panel,
_g_